1 /*
   2  * Copyright (c) 1997, 2019, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "jvm.h"
  27 #include "aot/aotLoader.hpp"
  28 #include "classfile/classLoader.hpp"
  29 #include "classfile/javaClasses.hpp"
  30 #include "classfile/moduleEntry.hpp"
  31 #include "classfile/systemDictionary.hpp"
  32 #include "classfile/vmSymbols.hpp"
  33 #include "code/codeCache.hpp"
  34 #include "code/scopeDesc.hpp"
  35 #include "compiler/compileBroker.hpp"
  36 #include "compiler/compileTask.hpp"
  37 #include "gc/shared/barrierSet.hpp"
  38 #include "gc/shared/gcId.hpp"
  39 #include "gc/shared/gcLocker.inline.hpp"
  40 #include "gc/shared/workgroup.hpp"
  41 #include "interpreter/interpreter.hpp"
  42 #include "interpreter/linkResolver.hpp"
  43 #include "interpreter/oopMapCache.hpp"
  44 #include "jfr/jfrEvents.hpp"
  45 #include "jvmtifiles/jvmtiEnv.hpp"
  46 #include "logging/log.hpp"
  47 #include "logging/logConfiguration.hpp"
  48 #include "logging/logStream.hpp"
  49 #include "memory/allocation.inline.hpp"
  50 #include "memory/metaspaceShared.hpp"
  51 #include "memory/oopFactory.hpp"
  52 #include "memory/resourceArea.hpp"
  53 #include "memory/universe.hpp"
  54 #include "oops/access.inline.hpp"
  55 #include "oops/instanceKlass.hpp"
  56 #include "oops/objArrayOop.hpp"
  57 #include "oops/oop.inline.hpp"
  58 #include "oops/symbol.hpp"
  59 #include "oops/typeArrayOop.inline.hpp"
  60 #include "oops/verifyOopClosure.hpp"
  61 #include "prims/jvm_misc.hpp"
  62 #include "prims/jvmtiExport.hpp"
  63 #include "prims/jvmtiThreadState.hpp"
  64 #include "runtime/arguments.hpp"
  65 #include "runtime/atomic.hpp"
  66 #include "runtime/biasedLocking.hpp"
  67 #include "runtime/fieldDescriptor.inline.hpp"
  68 #include "runtime/flags/jvmFlagConstraintList.hpp"
  69 #include "runtime/flags/jvmFlagRangeList.hpp"
  70 #include "runtime/flags/jvmFlagWriteableList.hpp"
  71 #include "runtime/deoptimization.hpp"
  72 #include "runtime/frame.inline.hpp"
  73 #include "runtime/handles.inline.hpp"
  74 #include "runtime/handshake.hpp"
  75 #include "runtime/init.hpp"
  76 #include "runtime/interfaceSupport.inline.hpp"
  77 #include "runtime/java.hpp"
  78 #include "runtime/javaCalls.hpp"
  79 #include "runtime/jniHandles.inline.hpp"
  80 #include "runtime/jniPeriodicChecker.hpp"
  81 #include "runtime/memprofiler.hpp"
  82 #include "runtime/mutexLocker.hpp"
  83 #include "runtime/objectMonitor.hpp"
  84 #include "runtime/orderAccess.hpp"
  85 #include "runtime/osThread.hpp"
  86 #include "runtime/prefetch.inline.hpp"
  87 #include "runtime/safepoint.hpp"
  88 #include "runtime/safepointMechanism.inline.hpp"
  89 #include "runtime/safepointVerifiers.hpp"
  90 #include "runtime/sharedRuntime.hpp"
  91 #include "runtime/statSampler.hpp"
  92 #include "runtime/stubRoutines.hpp"
  93 #include "runtime/sweeper.hpp"
  94 #include "runtime/task.hpp"
  95 #include "runtime/thread.inline.hpp"
  96 #include "runtime/threadCritical.hpp"
  97 #include "runtime/threadSMR.inline.hpp"
  98 #include "runtime/threadStatisticalInfo.hpp"
  99 #include "runtime/timer.hpp"
 100 #include "runtime/timerTrace.hpp"
 101 #include "runtime/vframe.inline.hpp"
 102 #include "runtime/vframeArray.hpp"
 103 #include "runtime/vframe_hp.hpp"
 104 #include "runtime/vmThread.hpp"
 105 #include "runtime/vmOperations.hpp"
 106 #include "runtime/vm_version.hpp"
 107 #include "services/attachListener.hpp"
 108 #include "services/management.hpp"
 109 #include "services/memTracker.hpp"
 110 #include "services/threadService.hpp"
 111 #include "utilities/align.hpp"
 112 #include "utilities/copy.hpp"
 113 #include "utilities/defaultStream.hpp"
 114 #include "utilities/dtrace.hpp"
 115 #include "utilities/events.hpp"
 116 #include "utilities/macros.hpp"
 117 #include "utilities/preserveException.hpp"
 118 #include "utilities/singleWriterSynchronizer.hpp"
 119 #include "utilities/vmError.hpp"
 120 #if INCLUDE_JVMCI
 121 #include "jvmci/jvmci.hpp"
 122 #include "jvmci/jvmciEnv.hpp"
 123 #endif
 124 #ifdef COMPILER1
 125 #include "c1/c1_Compiler.hpp"
 126 #endif
 127 #ifdef COMPILER2
 128 #include "opto/c2compiler.hpp"
 129 #include "opto/idealGraphPrinter.hpp"
 130 #endif
 131 #if INCLUDE_RTM_OPT
 132 #include "runtime/rtmLocking.hpp"
 133 #endif
 134 #if INCLUDE_JFR
 135 #include "jfr/jfr.hpp"
 136 #endif
 137 
 138 // Initialization after module runtime initialization
 139 void universe_post_module_init();  // must happen after call_initPhase2
 140 
 141 #ifdef DTRACE_ENABLED
 142 
 143 // Only bother with this argument setup if dtrace is available
 144 
 145   #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
 146   #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
 147 
 148   #define DTRACE_THREAD_PROBE(probe, javathread)                           \
 149     {                                                                      \
 150       ResourceMark rm(this);                                               \
 151       int len = 0;                                                         \
 152       const char* name = (javathread)->get_thread_name();                  \
 153       len = strlen(name);                                                  \
 154       HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */               \
 155         (char *) name, len,                                                \
 156         java_lang_Thread::thread_id((javathread)->threadObj()),            \
 157         (uintptr_t) (javathread)->osthread()->thread_id(),                 \
 158         java_lang_Thread::is_daemon((javathread)->threadObj()));           \
 159     }
 160 
 161 #else //  ndef DTRACE_ENABLED
 162 
 163   #define DTRACE_THREAD_PROBE(probe, javathread)
 164 
 165 #endif // ndef DTRACE_ENABLED
 166 
 167 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 168 // Current thread is maintained as a thread-local variable
 169 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
 170 #endif
 171 
 172 // ======= Thread ========
 173 // Support for forcing alignment of thread objects for biased locking
 174 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
 175   if (UseBiasedLocking) {
 176     const int alignment = markOopDesc::biased_lock_alignment;
 177     size_t aligned_size = size + (alignment - sizeof(intptr_t));
 178     void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
 179                                           : AllocateHeap(aligned_size, flags, CURRENT_PC,
 180                                                          AllocFailStrategy::RETURN_NULL);
 181     void* aligned_addr     = align_up(real_malloc_addr, alignment);
 182     assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
 183            ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
 184            "JavaThread alignment code overflowed allocated storage");
 185     if (aligned_addr != real_malloc_addr) {
 186       log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
 187                               p2i(real_malloc_addr),
 188                               p2i(aligned_addr));
 189     }
 190     ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
 191     return aligned_addr;
 192   } else {
 193     return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
 194                        : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
 195   }
 196 }
 197 
 198 void Thread::operator delete(void* p) {
 199   if (UseBiasedLocking) {
 200     FreeHeap(((Thread*) p)->_real_malloc_address);
 201   } else {
 202     FreeHeap(p);
 203   }
 204 }
 205 
 206 void JavaThread::smr_delete() {
 207   if (_on_thread_list) {
 208     ThreadsSMRSupport::smr_delete(this);
 209   } else {
 210     delete this;
 211   }
 212 }
 213 
 214 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
 215 // JavaThread
 216 
 217 DEBUG_ONLY(Thread* Thread::_starting_thread = NULL;)
 218 
 219 Thread::Thread() {
 220 
 221   DEBUG_ONLY(_run_state = PRE_CALL_RUN;)
 222 
 223   // stack and get_thread
 224   set_stack_base(NULL);
 225   set_stack_size(0);
 226   set_self_raw_id(0);
 227   set_lgrp_id(-1);
 228   DEBUG_ONLY(clear_suspendible_thread();)
 229 
 230   // allocated data structures
 231   set_osthread(NULL);
 232   set_resource_area(new (mtThread)ResourceArea());
 233   DEBUG_ONLY(_current_resource_mark = NULL;)
 234   set_handle_area(new (mtThread) HandleArea(NULL));
 235   set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
 236   set_active_handles(NULL);
 237   set_free_handle_block(NULL);
 238   set_last_handle_mark(NULL);
 239   DEBUG_ONLY(_missed_ic_stub_refill_verifier = NULL);
 240 
 241   // Initial value of zero ==> never claimed.
 242   _threads_do_token = 0;
 243   _threads_hazard_ptr = NULL;
 244   _threads_list_ptr = NULL;
 245   _nested_threads_hazard_ptr_cnt = 0;
 246   _rcu_counter = 0;
 247 
 248   // the handle mark links itself to last_handle_mark
 249   new HandleMark(this);
 250 
 251   // plain initialization
 252   debug_only(_owned_locks = NULL;)
 253   NOT_PRODUCT(_no_safepoint_count = 0;)
 254   NOT_PRODUCT(_skip_gcalot = false;)
 255   _jvmti_env_iteration_count = 0;
 256   set_allocated_bytes(0);
 257   _vm_operation_started_count = 0;
 258   _vm_operation_completed_count = 0;
 259   _current_pending_monitor = NULL;
 260   _current_pending_monitor_is_from_java = true;
 261   _current_waiting_monitor = NULL;
 262   _num_nested_signal = 0;
 263   omFreeList = NULL;
 264   omFreeCount = 0;
 265   omFreeProvision = 32;
 266   omInUseList = NULL;
 267   omInUseCount = 0;
 268 
 269 #ifdef ASSERT
 270   _visited_for_critical_count = false;
 271 #endif
 272 
 273   _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
 274                          Monitor::_safepoint_check_sometimes);
 275   _suspend_flags = 0;
 276 
 277   // thread-specific hashCode stream generator state - Marsaglia shift-xor form
 278   _hashStateX = os::random();
 279   _hashStateY = 842502087;
 280   _hashStateZ = 0x8767;    // (int)(3579807591LL & 0xffff) ;
 281   _hashStateW = 273326509;
 282 
 283   _OnTrap   = 0;
 284   _Stalled  = 0;
 285   _TypeTag  = 0x2BAD;
 286 
 287   // Many of the following fields are effectively final - immutable
 288   // Note that nascent threads can't use the Native Monitor-Mutex
 289   // construct until the _MutexEvent is initialized ...
 290   // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
 291   // we might instead use a stack of ParkEvents that we could provision on-demand.
 292   // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
 293   // and ::Release()
 294   _ParkEvent   = ParkEvent::Allocate(this);
 295   _SleepEvent  = ParkEvent::Allocate(this);
 296   _MuxEvent    = ParkEvent::Allocate(this);
 297 
 298 #ifdef CHECK_UNHANDLED_OOPS
 299   if (CheckUnhandledOops) {
 300     _unhandled_oops = new UnhandledOops(this);
 301   }
 302 #endif // CHECK_UNHANDLED_OOPS
 303 #ifdef ASSERT
 304   if (UseBiasedLocking) {
 305     assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
 306     assert(this == _real_malloc_address ||
 307            this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
 308            "bug in forced alignment of thread objects");
 309   }
 310 #endif // ASSERT
 311 
 312   // Notify the barrier set that a thread is being created. The initial
 313   // thread is created before the barrier set is available.  The call to
 314   // BarrierSet::on_thread_create() for this thread is therefore deferred
 315   // to BarrierSet::set_barrier_set().
 316   BarrierSet* const barrier_set = BarrierSet::barrier_set();
 317   if (barrier_set != NULL) {
 318     barrier_set->on_thread_create(this);
 319   } else {
 320     // Only the main thread should be created before the barrier set
 321     // and that happens just before Thread::current is set. No other thread
 322     // can attach as the VM is not created yet, so they can't execute this code.
 323     // If the main thread creates other threads before the barrier set that is an error.
 324     assert(Thread::current_or_null() == NULL, "creating thread before barrier set");
 325   }
 326 }
 327 
 328 void Thread::initialize_thread_current() {
 329 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 330   assert(_thr_current == NULL, "Thread::current already initialized");
 331   _thr_current = this;
 332 #endif
 333   assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
 334   ThreadLocalStorage::set_thread(this);
 335   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 336 }
 337 
 338 void Thread::clear_thread_current() {
 339   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 340 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 341   _thr_current = NULL;
 342 #endif
 343   ThreadLocalStorage::set_thread(NULL);
 344 }
 345 
 346 void Thread::record_stack_base_and_size() {
 347   // Note: at this point, Thread object is not yet initialized. Do not rely on
 348   // any members being initialized. Do not rely on Thread::current() being set.
 349   // If possible, refrain from doing anything which may crash or assert since
 350   // quite probably those crash dumps will be useless.
 351   set_stack_base(os::current_stack_base());
 352   set_stack_size(os::current_stack_size());
 353 
 354 #ifdef SOLARIS
 355   if (os::is_primordial_thread()) {
 356     os::Solaris::correct_stack_boundaries_for_primordial_thread(this);
 357   }
 358 #endif
 359 
 360   // Set stack limits after thread is initialized.
 361   if (is_Java_thread()) {
 362     ((JavaThread*) this)->set_stack_overflow_limit();
 363     ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
 364   }
 365 }
 366 
 367 #if INCLUDE_NMT
 368 void Thread::register_thread_stack_with_NMT() {
 369   MemTracker::record_thread_stack(stack_end(), stack_size());
 370 }
 371 #endif // INCLUDE_NMT
 372 
 373 void Thread::call_run() {
 374   DEBUG_ONLY(_run_state = CALL_RUN;)
 375 
 376   // At this point, Thread object should be fully initialized and
 377   // Thread::current() should be set.
 378 
 379   assert(Thread::current_or_null() != NULL, "current thread is unset");
 380   assert(Thread::current_or_null() == this, "current thread is wrong");
 381 
 382   // Perform common initialization actions
 383 
 384   register_thread_stack_with_NMT();
 385 
 386   JFR_ONLY(Jfr::on_thread_start(this);)
 387 
 388   log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
 389     PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
 390     os::current_thread_id(), p2i(stack_base() - stack_size()),
 391     p2i(stack_base()), stack_size()/1024);
 392 
 393   // Perform <ChildClass> initialization actions
 394   DEBUG_ONLY(_run_state = PRE_RUN;)
 395   this->pre_run();
 396 
 397   // Invoke <ChildClass>::run()
 398   DEBUG_ONLY(_run_state = RUN;)
 399   this->run();
 400   // Returned from <ChildClass>::run(). Thread finished.
 401 
 402   // Perform common tear-down actions
 403 
 404   assert(Thread::current_or_null() != NULL, "current thread is unset");
 405   assert(Thread::current_or_null() == this, "current thread is wrong");
 406 
 407   // Perform <ChildClass> tear-down actions
 408   DEBUG_ONLY(_run_state = POST_RUN;)
 409   this->post_run();
 410 
 411   // Note: at this point the thread object may already have deleted itself,
 412   // so from here on do not dereference *this*. Not all thread types currently
 413   // delete themselves when they terminate. But no thread should ever be deleted
 414   // asynchronously with respect to its termination - that is what _run_state can
 415   // be used to check.
 416 
 417   assert(Thread::current_or_null() == NULL, "current thread still present");
 418 }
 419 
 420 Thread::~Thread() {
 421 
 422   // Attached threads will remain in PRE_CALL_RUN, as will threads that don't actually
 423   // get started due to errors etc. Any active thread should at least reach post_run
 424   // before it is deleted (usually in post_run()).
 425   assert(_run_state == PRE_CALL_RUN ||
 426          _run_state == POST_RUN, "Active Thread deleted before post_run(): "
 427          "_run_state=%d", (int)_run_state);
 428 
 429   // Notify the barrier set that a thread is being destroyed. Note that a barrier
 430   // set might not be available if we encountered errors during bootstrapping.
 431   BarrierSet* const barrier_set = BarrierSet::barrier_set();
 432   if (barrier_set != NULL) {
 433     barrier_set->on_thread_destroy(this);
 434   }
 435 
 436   // stack_base can be NULL if the thread is never started or exited before
 437   // record_stack_base_and_size called. Although, we would like to ensure
 438   // that all started threads do call record_stack_base_and_size(), there is
 439   // not proper way to enforce that.
 440 #if INCLUDE_NMT
 441   if (_stack_base != NULL) {
 442     MemTracker::release_thread_stack(stack_end(), stack_size());
 443 #ifdef ASSERT
 444     set_stack_base(NULL);
 445 #endif
 446   }
 447 #endif // INCLUDE_NMT
 448 
 449   // deallocate data structures
 450   delete resource_area();
 451   // since the handle marks are using the handle area, we have to deallocated the root
 452   // handle mark before deallocating the thread's handle area,
 453   assert(last_handle_mark() != NULL, "check we have an element");
 454   delete last_handle_mark();
 455   assert(last_handle_mark() == NULL, "check we have reached the end");
 456 
 457   // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
 458   // We NULL out the fields for good hygiene.
 459   ParkEvent::Release(_ParkEvent); _ParkEvent   = NULL;
 460   ParkEvent::Release(_SleepEvent); _SleepEvent  = NULL;
 461   ParkEvent::Release(_MuxEvent); _MuxEvent    = NULL;
 462 
 463   delete handle_area();
 464   delete metadata_handles();
 465 
 466   // SR_handler uses this as a termination indicator -
 467   // needs to happen before os::free_thread()
 468   delete _SR_lock;
 469   _SR_lock = NULL;
 470 
 471   // osthread() can be NULL, if creation of thread failed.
 472   if (osthread() != NULL) os::free_thread(osthread());
 473 
 474   // Clear Thread::current if thread is deleting itself and it has not
 475   // already been done. This must be done before the memory is deallocated.
 476   // Needed to ensure JNI correctly detects non-attached threads.
 477   if (this == Thread::current_or_null()) {
 478     Thread::clear_thread_current();
 479   }
 480 
 481   CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
 482 }
 483 
 484 #ifdef ASSERT
 485 // A JavaThread is considered "dangling" if it is not the current
 486 // thread, has been added the Threads list, the system is not at a
 487 // safepoint and the Thread is not "protected".
 488 //
 489 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
 490   assert(!thread->is_Java_thread() || Thread::current() == thread ||
 491          !((JavaThread *) thread)->on_thread_list() ||
 492          SafepointSynchronize::is_at_safepoint() ||
 493          ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
 494          "possibility of dangling Thread pointer");
 495 }
 496 #endif
 497 
 498 ThreadPriority Thread::get_priority(const Thread* const thread) {
 499   ThreadPriority priority;
 500   // Can return an error!
 501   (void)os::get_priority(thread, priority);
 502   assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
 503   return priority;
 504 }
 505 
 506 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
 507   debug_only(check_for_dangling_thread_pointer(thread);)
 508   // Can return an error!
 509   (void)os::set_priority(thread, priority);
 510 }
 511 
 512 
 513 void Thread::start(Thread* thread) {
 514   // Start is different from resume in that its safety is guaranteed by context or
 515   // being called from a Java method synchronized on the Thread object.
 516   if (!DisableStartThread) {
 517     if (thread->is_Java_thread()) {
 518       // Initialize the thread state to RUNNABLE before starting this thread.
 519       // Can not set it after the thread started because we do not know the
 520       // exact thread state at that time. It could be in MONITOR_WAIT or
 521       // in SLEEPING or some other state.
 522       java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
 523                                           java_lang_Thread::RUNNABLE);
 524     }
 525     os::start_thread(thread);
 526   }
 527 }
 528 
 529 // Enqueue a VM_Operation to do the job for us - sometime later
 530 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
 531   VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
 532   VMThread::execute(vm_stop);
 533 }
 534 
 535 
 536 // Check if an external suspend request has completed (or has been
 537 // cancelled). Returns true if the thread is externally suspended and
 538 // false otherwise.
 539 //
 540 // The bits parameter returns information about the code path through
 541 // the routine. Useful for debugging:
 542 //
 543 // set in is_ext_suspend_completed():
 544 // 0x00000001 - routine was entered
 545 // 0x00000010 - routine return false at end
 546 // 0x00000100 - thread exited (return false)
 547 // 0x00000200 - suspend request cancelled (return false)
 548 // 0x00000400 - thread suspended (return true)
 549 // 0x00001000 - thread is in a suspend equivalent state (return true)
 550 // 0x00002000 - thread is native and walkable (return true)
 551 // 0x00004000 - thread is native_trans and walkable (needed retry)
 552 //
 553 // set in wait_for_ext_suspend_completion():
 554 // 0x00010000 - routine was entered
 555 // 0x00020000 - suspend request cancelled before loop (return false)
 556 // 0x00040000 - thread suspended before loop (return true)
 557 // 0x00080000 - suspend request cancelled in loop (return false)
 558 // 0x00100000 - thread suspended in loop (return true)
 559 // 0x00200000 - suspend not completed during retry loop (return false)
 560 
 561 // Helper class for tracing suspend wait debug bits.
 562 //
 563 // 0x00000100 indicates that the target thread exited before it could
 564 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
 565 // 0x00080000 each indicate a cancelled suspend request so they don't
 566 // count as wait failures either.
 567 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
 568 
 569 class TraceSuspendDebugBits : public StackObj {
 570  private:
 571   JavaThread * jt;
 572   bool         is_wait;
 573   bool         called_by_wait;  // meaningful when !is_wait
 574   uint32_t *   bits;
 575 
 576  public:
 577   TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
 578                         uint32_t *_bits) {
 579     jt             = _jt;
 580     is_wait        = _is_wait;
 581     called_by_wait = _called_by_wait;
 582     bits           = _bits;
 583   }
 584 
 585   ~TraceSuspendDebugBits() {
 586     if (!is_wait) {
 587 #if 1
 588       // By default, don't trace bits for is_ext_suspend_completed() calls.
 589       // That trace is very chatty.
 590       return;
 591 #else
 592       if (!called_by_wait) {
 593         // If tracing for is_ext_suspend_completed() is enabled, then only
 594         // trace calls to it from wait_for_ext_suspend_completion()
 595         return;
 596       }
 597 #endif
 598     }
 599 
 600     if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
 601       if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
 602         MutexLocker ml(Threads_lock);  // needed for get_thread_name()
 603         ResourceMark rm;
 604 
 605         tty->print_cr(
 606                       "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
 607                       jt->get_thread_name(), *bits);
 608 
 609         guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
 610       }
 611     }
 612   }
 613 };
 614 #undef DEBUG_FALSE_BITS
 615 
 616 
 617 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
 618                                           uint32_t *bits) {
 619   TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
 620 
 621   bool did_trans_retry = false;  // only do thread_in_native_trans retry once
 622   bool do_trans_retry;           // flag to force the retry
 623 
 624   *bits |= 0x00000001;
 625 
 626   do {
 627     do_trans_retry = false;
 628 
 629     if (is_exiting()) {
 630       // Thread is in the process of exiting. This is always checked
 631       // first to reduce the risk of dereferencing a freed JavaThread.
 632       *bits |= 0x00000100;
 633       return false;
 634     }
 635 
 636     if (!is_external_suspend()) {
 637       // Suspend request is cancelled. This is always checked before
 638       // is_ext_suspended() to reduce the risk of a rogue resume
 639       // confusing the thread that made the suspend request.
 640       *bits |= 0x00000200;
 641       return false;
 642     }
 643 
 644     if (is_ext_suspended()) {
 645       // thread is suspended
 646       *bits |= 0x00000400;
 647       return true;
 648     }
 649 
 650     // Now that we no longer do hard suspends of threads running
 651     // native code, the target thread can be changing thread state
 652     // while we are in this routine:
 653     //
 654     //   _thread_in_native -> _thread_in_native_trans -> _thread_blocked
 655     //
 656     // We save a copy of the thread state as observed at this moment
 657     // and make our decision about suspend completeness based on the
 658     // copy. This closes the race where the thread state is seen as
 659     // _thread_in_native_trans in the if-thread_blocked check, but is
 660     // seen as _thread_blocked in if-thread_in_native_trans check.
 661     JavaThreadState save_state = thread_state();
 662 
 663     if (save_state == _thread_blocked && is_suspend_equivalent()) {
 664       // If the thread's state is _thread_blocked and this blocking
 665       // condition is known to be equivalent to a suspend, then we can
 666       // consider the thread to be externally suspended. This means that
 667       // the code that sets _thread_blocked has been modified to do
 668       // self-suspension if the blocking condition releases. We also
 669       // used to check for CONDVAR_WAIT here, but that is now covered by
 670       // the _thread_blocked with self-suspension check.
 671       //
 672       // Return true since we wouldn't be here unless there was still an
 673       // external suspend request.
 674       *bits |= 0x00001000;
 675       return true;
 676     } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
 677       // Threads running native code will self-suspend on native==>VM/Java
 678       // transitions. If its stack is walkable (should always be the case
 679       // unless this function is called before the actual java_suspend()
 680       // call), then the wait is done.
 681       *bits |= 0x00002000;
 682       return true;
 683     } else if (!called_by_wait && !did_trans_retry &&
 684                save_state == _thread_in_native_trans &&
 685                frame_anchor()->walkable()) {
 686       // The thread is transitioning from thread_in_native to another
 687       // thread state. check_safepoint_and_suspend_for_native_trans()
 688       // will force the thread to self-suspend. If it hasn't gotten
 689       // there yet we may have caught the thread in-between the native
 690       // code check above and the self-suspend. Lucky us. If we were
 691       // called by wait_for_ext_suspend_completion(), then it
 692       // will be doing the retries so we don't have to.
 693       //
 694       // Since we use the saved thread state in the if-statement above,
 695       // there is a chance that the thread has already transitioned to
 696       // _thread_blocked by the time we get here. In that case, we will
 697       // make a single unnecessary pass through the logic below. This
 698       // doesn't hurt anything since we still do the trans retry.
 699 
 700       *bits |= 0x00004000;
 701 
 702       // Once the thread leaves thread_in_native_trans for another
 703       // thread state, we break out of this retry loop. We shouldn't
 704       // need this flag to prevent us from getting back here, but
 705       // sometimes paranoia is good.
 706       did_trans_retry = true;
 707 
 708       // We wait for the thread to transition to a more usable state.
 709       for (int i = 1; i <= SuspendRetryCount; i++) {
 710         // We used to do an "os::yield_all(i)" call here with the intention
 711         // that yielding would increase on each retry. However, the parameter
 712         // is ignored on Linux which means the yield didn't scale up. Waiting
 713         // on the SR_lock below provides a much more predictable scale up for
 714         // the delay. It also provides a simple/direct point to check for any
 715         // safepoint requests from the VMThread
 716 
 717         // temporarily drops SR_lock while doing wait with safepoint check
 718         // (if we're a JavaThread - the WatcherThread can also call this)
 719         // and increase delay with each retry
 720         if (Thread::current()->is_Java_thread()) {
 721           SR_lock()->wait(i * delay);
 722         } else {
 723           SR_lock()->wait_without_safepoint_check(i * delay);
 724         }
 725 
 726         // check the actual thread state instead of what we saved above
 727         if (thread_state() != _thread_in_native_trans) {
 728           // the thread has transitioned to another thread state so
 729           // try all the checks (except this one) one more time.
 730           do_trans_retry = true;
 731           break;
 732         }
 733       } // end retry loop
 734 
 735 
 736     }
 737   } while (do_trans_retry);
 738 
 739   *bits |= 0x00000010;
 740   return false;
 741 }
 742 
 743 // Wait for an external suspend request to complete (or be cancelled).
 744 // Returns true if the thread is externally suspended and false otherwise.
 745 //
 746 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
 747                                                  uint32_t *bits) {
 748   TraceSuspendDebugBits tsdb(this, true /* is_wait */,
 749                              false /* !called_by_wait */, bits);
 750 
 751   // local flag copies to minimize SR_lock hold time
 752   bool is_suspended;
 753   bool pending;
 754   uint32_t reset_bits;
 755 
 756   // set a marker so is_ext_suspend_completed() knows we are the caller
 757   *bits |= 0x00010000;
 758 
 759   // We use reset_bits to reinitialize the bits value at the top of
 760   // each retry loop. This allows the caller to make use of any
 761   // unused bits for their own marking purposes.
 762   reset_bits = *bits;
 763 
 764   {
 765     MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
 766     is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 767                                             delay, bits);
 768     pending = is_external_suspend();
 769   }
 770   // must release SR_lock to allow suspension to complete
 771 
 772   if (!pending) {
 773     // A cancelled suspend request is the only false return from
 774     // is_ext_suspend_completed() that keeps us from entering the
 775     // retry loop.
 776     *bits |= 0x00020000;
 777     return false;
 778   }
 779 
 780   if (is_suspended) {
 781     *bits |= 0x00040000;
 782     return true;
 783   }
 784 
 785   for (int i = 1; i <= retries; i++) {
 786     *bits = reset_bits;  // reinit to only track last retry
 787 
 788     // We used to do an "os::yield_all(i)" call here with the intention
 789     // that yielding would increase on each retry. However, the parameter
 790     // is ignored on Linux which means the yield didn't scale up. Waiting
 791     // on the SR_lock below provides a much more predictable scale up for
 792     // the delay. It also provides a simple/direct point to check for any
 793     // safepoint requests from the VMThread
 794 
 795     {
 796       Thread* t = Thread::current();
 797       MonitorLocker ml(SR_lock(),
 798                        t->is_Java_thread() ? Mutex::_safepoint_check_flag : Mutex::_no_safepoint_check_flag);
 799       // wait with safepoint check (if we're a JavaThread - the WatcherThread
 800       // can also call this)  and increase delay with each retry
 801       ml.wait(i * delay);
 802 
 803       is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 804                                               delay, bits);
 805 
 806       // It is possible for the external suspend request to be cancelled
 807       // (by a resume) before the actual suspend operation is completed.
 808       // Refresh our local copy to see if we still need to wait.
 809       pending = is_external_suspend();
 810     }
 811 
 812     if (!pending) {
 813       // A cancelled suspend request is the only false return from
 814       // is_ext_suspend_completed() that keeps us from staying in the
 815       // retry loop.
 816       *bits |= 0x00080000;
 817       return false;
 818     }
 819 
 820     if (is_suspended) {
 821       *bits |= 0x00100000;
 822       return true;
 823     }
 824   } // end retry loop
 825 
 826   // thread did not suspend after all our retries
 827   *bits |= 0x00200000;
 828   return false;
 829 }
 830 
 831 // Called from API entry points which perform stack walking. If the
 832 // associated JavaThread is the current thread, then wait_for_suspend
 833 // is not used. Otherwise, it determines if we should wait for the
 834 // "other" thread to complete external suspension. (NOTE: in future
 835 // releases the suspension mechanism should be reimplemented so this
 836 // is not necessary.)
 837 //
 838 bool
 839 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
 840   if (this != JavaThread::current()) {
 841     // "other" threads require special handling.
 842     if (wait_for_suspend) {
 843       // We are allowed to wait for the external suspend to complete
 844       // so give the other thread a chance to get suspended.
 845       if (!wait_for_ext_suspend_completion(SuspendRetryCount,
 846                                            SuspendRetryDelay, bits)) {
 847         // Didn't make it so let the caller know.
 848         return false;
 849       }
 850     }
 851     // We aren't allowed to wait for the external suspend to complete
 852     // so if the other thread isn't externally suspended we need to
 853     // let the caller know.
 854     else if (!is_ext_suspend_completed_with_lock(bits)) {
 855       return false;
 856     }
 857   }
 858 
 859   return true;
 860 }
 861 
 862 #ifndef PRODUCT
 863 void JavaThread::record_jump(address target, address instr, const char* file,
 864                              int line) {
 865 
 866   // This should not need to be atomic as the only way for simultaneous
 867   // updates is via interrupts. Even then this should be rare or non-existent
 868   // and we don't care that much anyway.
 869 
 870   int index = _jmp_ring_index;
 871   _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
 872   _jmp_ring[index]._target = (intptr_t) target;
 873   _jmp_ring[index]._instruction = (intptr_t) instr;
 874   _jmp_ring[index]._file = file;
 875   _jmp_ring[index]._line = line;
 876 }
 877 #endif // PRODUCT
 878 
 879 void Thread::interrupt(Thread* thread) {
 880   debug_only(check_for_dangling_thread_pointer(thread);)
 881   os::interrupt(thread);
 882 }
 883 
 884 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
 885   debug_only(check_for_dangling_thread_pointer(thread);)
 886   // Note:  If clear_interrupted==false, this simply fetches and
 887   // returns the value of the field osthread()->interrupted().
 888   return os::is_interrupted(thread, clear_interrupted);
 889 }
 890 
 891 
 892 // GC Support
 893 bool Thread::claim_par_threads_do(uintx claim_token) {
 894   uintx token = _threads_do_token;
 895   if (token != claim_token) {
 896     uintx res = Atomic::cmpxchg(claim_token, &_threads_do_token, token);
 897     if (res == token) {
 898       return true;
 899     }
 900     guarantee(res == claim_token, "invariant");
 901   }
 902   return false;
 903 }
 904 
 905 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
 906   active_handles()->oops_do(f);
 907   // Do oop for ThreadShadow
 908   f->do_oop((oop*)&_pending_exception);
 909   handle_area()->oops_do(f);
 910 
 911   // We scan thread local monitor lists here, and the remaining global
 912   // monitors in ObjectSynchronizer::oops_do().
 913   ObjectSynchronizer::thread_local_used_oops_do(this, f);
 914 }
 915 
 916 void Thread::metadata_handles_do(void f(Metadata*)) {
 917   // Only walk the Handles in Thread.
 918   if (metadata_handles() != NULL) {
 919     for (int i = 0; i< metadata_handles()->length(); i++) {
 920       f(metadata_handles()->at(i));
 921     }
 922   }
 923 }
 924 
 925 void Thread::print_on(outputStream* st, bool print_extended_info) const {
 926   // get_priority assumes osthread initialized
 927   if (osthread() != NULL) {
 928     int os_prio;
 929     if (os::get_native_priority(this, &os_prio) == OS_OK) {
 930       st->print("os_prio=%d ", os_prio);
 931     }
 932 
 933     st->print("cpu=%.2fms ",
 934               os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0
 935               );
 936     st->print("elapsed=%.2fs ",
 937               _statistical_info.getElapsedTime() / 1000.0
 938               );
 939     if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) {
 940       size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes();
 941       st->print("allocated=" SIZE_FORMAT "%s ",
 942                 byte_size_in_proper_unit(allocated_bytes),
 943                 proper_unit_for_byte_size(allocated_bytes)
 944                 );
 945       st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount());
 946     }
 947 
 948     st->print("tid=" INTPTR_FORMAT " ", p2i(this));
 949     osthread()->print_on(st);
 950   }
 951   ThreadsSMRSupport::print_info_on(this, st);
 952   st->print(" ");
 953   debug_only(if (WizardMode) print_owned_locks_on(st);)
 954 }
 955 
 956 void Thread::print() const { print_on(tty); }
 957 
 958 // Thread::print_on_error() is called by fatal error handler. Don't use
 959 // any lock or allocate memory.
 960 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
 961   assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
 962 
 963   if (is_VM_thread())                 { st->print("VMThread"); }
 964   else if (is_GC_task_thread())       { st->print("GCTaskThread"); }
 965   else if (is_Watcher_thread())       { st->print("WatcherThread"); }
 966   else if (is_ConcurrentGC_thread())  { st->print("ConcurrentGCThread"); }
 967   else                                { st->print("Thread"); }
 968 
 969   if (is_Named_thread()) {
 970     st->print(" \"%s\"", name());
 971   }
 972 
 973   st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
 974             p2i(stack_end()), p2i(stack_base()));
 975 
 976   if (osthread()) {
 977     st->print(" [id=%d]", osthread()->thread_id());
 978   }
 979 
 980   ThreadsSMRSupport::print_info_on(this, st);
 981 }
 982 
 983 void Thread::print_value_on(outputStream* st) const {
 984   if (is_Named_thread()) {
 985     st->print(" \"%s\" ", name());
 986   }
 987   st->print(INTPTR_FORMAT, p2i(this));   // print address
 988 }
 989 
 990 #ifdef ASSERT
 991 void Thread::print_owned_locks_on(outputStream* st) const {
 992   Monitor *cur = _owned_locks;
 993   if (cur == NULL) {
 994     st->print(" (no locks) ");
 995   } else {
 996     st->print_cr(" Locks owned:");
 997     while (cur) {
 998       cur->print_on(st);
 999       cur = cur->next();
1000     }
1001   }
1002 }
1003 
1004 static int ref_use_count  = 0;
1005 
1006 bool Thread::owns_locks_but_compiled_lock() const {
1007   for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
1008     if (cur != Compile_lock) return true;
1009   }
1010   return false;
1011 }
1012 
1013 // Checks safepoint allowed and clears unhandled oops at potential safepoints.
1014 void Thread::check_possible_safepoint() {
1015   if (!is_Java_thread()) return;
1016 
1017   if (_no_safepoint_count > 0) {
1018     fatal("Possible safepoint reached by thread that does not allow it");
1019   }
1020 #ifdef CHECK_UNHANDLED_OOPS
1021   // Clear unhandled oops in JavaThreads so we get a crash right away.
1022   clear_unhandled_oops();
1023 #endif // CHECK_UNHANDLED_OOPS
1024 }
1025 
1026 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially
1027 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
1028 // no locks which allow_vm_block's are held
1029 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
1030   if (!is_Java_thread()) return;
1031 
1032   check_possible_safepoint();
1033 
1034   if (((JavaThread*)this)->thread_state() != _thread_in_vm) {
1035     fatal("LEAF method calling lock?");
1036   }
1037 
1038   if (potential_vm_operation && !Universe::is_bootstrapping()) {
1039     // Make sure we do not hold any locks that the VM thread also uses.
1040     // This could potentially lead to deadlocks
1041     for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
1042       // Threads_lock is special, since the safepoint synchronization will not start before this is
1043       // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
1044       // since it is used to transfer control between JavaThreads and the VMThread
1045       // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
1046       if ((cur->allow_vm_block() &&
1047            cur != Threads_lock &&
1048            cur != Compile_lock &&               // Temporary: should not be necessary when we get separate compilation
1049            cur != VMOperationRequest_lock &&
1050            cur != VMOperationQueue_lock) ||
1051            cur->rank() == Mutex::special) {
1052         fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
1053       }
1054     }
1055   }
1056 
1057   if (GCALotAtAllSafepoints) {
1058     // We could enter a safepoint here and thus have a gc
1059     InterfaceSupport::check_gc_alot();
1060   }
1061 }
1062 #endif // ASSERT
1063 
1064 bool Thread::is_in_stack(address adr) const {
1065   assert(Thread::current() == this, "is_in_stack can only be called from current thread");
1066   address end = os::current_stack_pointer();
1067   // Allow non Java threads to call this without stack_base
1068   if (_stack_base == NULL) return true;
1069   if (stack_base() >= adr && adr >= end) return true;
1070 
1071   return false;
1072 }
1073 
1074 bool Thread::is_in_usable_stack(address adr) const {
1075   size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1076   size_t usable_stack_size = _stack_size - stack_guard_size;
1077 
1078   return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1079 }
1080 
1081 
1082 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1083 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1084 // used for compilation in the future. If that change is made, the need for these methods
1085 // should be revisited, and they should be removed if possible.
1086 
1087 bool Thread::is_lock_owned(address adr) const {
1088   return on_local_stack(adr);
1089 }
1090 
1091 bool Thread::set_as_starting_thread() {
1092   assert(_starting_thread == NULL, "already initialized: "
1093          "_starting_thread=" INTPTR_FORMAT, p2i(_starting_thread));
1094   // NOTE: this must be called inside the main thread.
1095   DEBUG_ONLY(_starting_thread = this;)
1096   return os::create_main_thread((JavaThread*)this);
1097 }
1098 
1099 static void initialize_class(Symbol* class_name, TRAPS) {
1100   Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1101   InstanceKlass::cast(klass)->initialize(CHECK);
1102 }
1103 
1104 
1105 // Creates the initial ThreadGroup
1106 static Handle create_initial_thread_group(TRAPS) {
1107   Handle system_instance = JavaCalls::construct_new_instance(
1108                             SystemDictionary::ThreadGroup_klass(),
1109                             vmSymbols::void_method_signature(),
1110                             CHECK_NH);
1111   Universe::set_system_thread_group(system_instance());
1112 
1113   Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1114   Handle main_instance = JavaCalls::construct_new_instance(
1115                             SystemDictionary::ThreadGroup_klass(),
1116                             vmSymbols::threadgroup_string_void_signature(),
1117                             system_instance,
1118                             string,
1119                             CHECK_NH);
1120   return main_instance;
1121 }
1122 
1123 // Creates the initial Thread
1124 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1125                                  TRAPS) {
1126   InstanceKlass* ik = SystemDictionary::Thread_klass();
1127   assert(ik->is_initialized(), "must be");
1128   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1129 
1130   // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1131   // constructor calls Thread.current(), which must be set here for the
1132   // initial thread.
1133   java_lang_Thread::set_thread(thread_oop(), thread);
1134   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1135   thread->set_threadObj(thread_oop());
1136 
1137   Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1138 
1139   JavaValue result(T_VOID);
1140   JavaCalls::call_special(&result, thread_oop,
1141                           ik,
1142                           vmSymbols::object_initializer_name(),
1143                           vmSymbols::threadgroup_string_void_signature(),
1144                           thread_group,
1145                           string,
1146                           CHECK_NULL);
1147   return thread_oop();
1148 }
1149 
1150 char java_runtime_name[128] = "";
1151 char java_runtime_version[128] = "";
1152 
1153 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1154 static const char* get_java_runtime_name(TRAPS) {
1155   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1156                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1157   fieldDescriptor fd;
1158   bool found = k != NULL &&
1159                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1160                                                         vmSymbols::string_signature(), &fd);
1161   if (found) {
1162     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1163     if (name_oop == NULL) {
1164       return NULL;
1165     }
1166     const char* name = java_lang_String::as_utf8_string(name_oop,
1167                                                         java_runtime_name,
1168                                                         sizeof(java_runtime_name));
1169     return name;
1170   } else {
1171     return NULL;
1172   }
1173 }
1174 
1175 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1176 static const char* get_java_runtime_version(TRAPS) {
1177   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1178                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1179   fieldDescriptor fd;
1180   bool found = k != NULL &&
1181                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1182                                                         vmSymbols::string_signature(), &fd);
1183   if (found) {
1184     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1185     if (name_oop == NULL) {
1186       return NULL;
1187     }
1188     const char* name = java_lang_String::as_utf8_string(name_oop,
1189                                                         java_runtime_version,
1190                                                         sizeof(java_runtime_version));
1191     return name;
1192   } else {
1193     return NULL;
1194   }
1195 }
1196 
1197 // General purpose hook into Java code, run once when the VM is initialized.
1198 // The Java library method itself may be changed independently from the VM.
1199 static void call_postVMInitHook(TRAPS) {
1200   Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1201   if (klass != NULL) {
1202     JavaValue result(T_VOID);
1203     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1204                            vmSymbols::void_method_signature(),
1205                            CHECK);
1206   }
1207 }
1208 
1209 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1210                                     bool daemon, TRAPS) {
1211   assert(thread_group.not_null(), "thread group should be specified");
1212   assert(threadObj() == NULL, "should only create Java thread object once");
1213 
1214   InstanceKlass* ik = SystemDictionary::Thread_klass();
1215   assert(ik->is_initialized(), "must be");
1216   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1217 
1218   // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon.
1219   // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1220   // constructor calls Thread.current(), which must be set here.
1221   java_lang_Thread::set_thread(thread_oop(), this);
1222   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1223   set_threadObj(thread_oop());
1224 
1225   JavaValue result(T_VOID);
1226   if (thread_name != NULL) {
1227     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1228     // Thread gets assigned specified name and null target
1229     JavaCalls::call_special(&result,
1230                             thread_oop,
1231                             ik,
1232                             vmSymbols::object_initializer_name(),
1233                             vmSymbols::threadgroup_string_void_signature(),
1234                             thread_group,
1235                             name,
1236                             THREAD);
1237   } else {
1238     // Thread gets assigned name "Thread-nnn" and null target
1239     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1240     JavaCalls::call_special(&result,
1241                             thread_oop,
1242                             ik,
1243                             vmSymbols::object_initializer_name(),
1244                             vmSymbols::threadgroup_runnable_void_signature(),
1245                             thread_group,
1246                             Handle(),
1247                             THREAD);
1248   }
1249 
1250 
1251   if (daemon) {
1252     java_lang_Thread::set_daemon(thread_oop());
1253   }
1254 
1255   if (HAS_PENDING_EXCEPTION) {
1256     return;
1257   }
1258 
1259   Klass* group =  SystemDictionary::ThreadGroup_klass();
1260   Handle threadObj(THREAD, this->threadObj());
1261 
1262   JavaCalls::call_special(&result,
1263                           thread_group,
1264                           group,
1265                           vmSymbols::add_method_name(),
1266                           vmSymbols::thread_void_signature(),
1267                           threadObj,          // Arg 1
1268                           THREAD);
1269 }
1270 
1271 // List of all NonJavaThreads and safe iteration over that list.
1272 
1273 class NonJavaThread::List {
1274 public:
1275   NonJavaThread* volatile _head;
1276   SingleWriterSynchronizer _protect;
1277 
1278   List() : _head(NULL), _protect() {}
1279 };
1280 
1281 NonJavaThread::List NonJavaThread::_the_list;
1282 
1283 NonJavaThread::Iterator::Iterator() :
1284   _protect_enter(_the_list._protect.enter()),
1285   _current(OrderAccess::load_acquire(&_the_list._head))
1286 {}
1287 
1288 NonJavaThread::Iterator::~Iterator() {
1289   _the_list._protect.exit(_protect_enter);
1290 }
1291 
1292 void NonJavaThread::Iterator::step() {
1293   assert(!end(), "precondition");
1294   _current = OrderAccess::load_acquire(&_current->_next);
1295 }
1296 
1297 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) {
1298   assert(BarrierSet::barrier_set() != NULL, "NonJavaThread created too soon!");
1299 }
1300 
1301 NonJavaThread::~NonJavaThread() { }
1302 
1303 void NonJavaThread::add_to_the_list() {
1304   MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1305   // Initialize BarrierSet-related data before adding to list.
1306   BarrierSet::barrier_set()->on_thread_attach(this);
1307   OrderAccess::release_store(&_next, _the_list._head);
1308   OrderAccess::release_store(&_the_list._head, this);
1309 }
1310 
1311 void NonJavaThread::remove_from_the_list() {
1312   {
1313     MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1314     // Cleanup BarrierSet-related data before removing from list.
1315     BarrierSet::barrier_set()->on_thread_detach(this);
1316     NonJavaThread* volatile* p = &_the_list._head;
1317     for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) {
1318       if (t == this) {
1319         *p = _next;
1320         break;
1321       }
1322     }
1323   }
1324   // Wait for any in-progress iterators.  Concurrent synchronize is not
1325   // allowed, so do it while holding a dedicated lock.  Outside and distinct
1326   // from NJTList_lock in case an iteration attempts to lock it.
1327   MutexLocker ml(NonJavaThreadsListSync_lock, Mutex::_no_safepoint_check_flag);
1328   _the_list._protect.synchronize();
1329   _next = NULL;                 // Safe to drop the link now.
1330 }
1331 
1332 void NonJavaThread::pre_run() {
1333   add_to_the_list();
1334 
1335   // This is slightly odd in that NamedThread is a subclass, but
1336   // in fact name() is defined in Thread
1337   assert(this->name() != NULL, "thread name was not set before it was started");
1338   this->set_native_thread_name(this->name());
1339 }
1340 
1341 void NonJavaThread::post_run() {
1342   JFR_ONLY(Jfr::on_thread_exit(this);)
1343   remove_from_the_list();
1344   // Ensure thread-local-storage is cleared before termination.
1345   Thread::clear_thread_current();
1346 }
1347 
1348 // NamedThread --  non-JavaThread subclasses with multiple
1349 // uniquely named instances should derive from this.
1350 NamedThread::NamedThread() :
1351   NonJavaThread(),
1352   _name(NULL),
1353   _processed_thread(NULL),
1354   _gc_id(GCId::undefined())
1355 {}
1356 
1357 NamedThread::~NamedThread() {
1358   if (_name != NULL) {
1359     FREE_C_HEAP_ARRAY(char, _name);
1360     _name = NULL;
1361   }
1362 }
1363 
1364 void NamedThread::set_name(const char* format, ...) {
1365   guarantee(_name == NULL, "Only get to set name once.");
1366   _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1367   guarantee(_name != NULL, "alloc failure");
1368   va_list ap;
1369   va_start(ap, format);
1370   jio_vsnprintf(_name, max_name_len, format, ap);
1371   va_end(ap);
1372 }
1373 
1374 void NamedThread::print_on(outputStream* st) const {
1375   st->print("\"%s\" ", name());
1376   Thread::print_on(st);
1377   st->cr();
1378 }
1379 
1380 
1381 // ======= WatcherThread ========
1382 
1383 // The watcher thread exists to simulate timer interrupts.  It should
1384 // be replaced by an abstraction over whatever native support for
1385 // timer interrupts exists on the platform.
1386 
1387 WatcherThread* WatcherThread::_watcher_thread   = NULL;
1388 bool WatcherThread::_startable = false;
1389 volatile bool  WatcherThread::_should_terminate = false;
1390 
1391 WatcherThread::WatcherThread() : NonJavaThread() {
1392   assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1393   if (os::create_thread(this, os::watcher_thread)) {
1394     _watcher_thread = this;
1395 
1396     // Set the watcher thread to the highest OS priority which should not be
1397     // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1398     // is created. The only normal thread using this priority is the reference
1399     // handler thread, which runs for very short intervals only.
1400     // If the VMThread's priority is not lower than the WatcherThread profiling
1401     // will be inaccurate.
1402     os::set_priority(this, MaxPriority);
1403     if (!DisableStartThread) {
1404       os::start_thread(this);
1405     }
1406   }
1407 }
1408 
1409 int WatcherThread::sleep() const {
1410   // The WatcherThread does not participate in the safepoint protocol
1411   // for the PeriodicTask_lock because it is not a JavaThread.
1412   MonitorLocker ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1413 
1414   if (_should_terminate) {
1415     // check for termination before we do any housekeeping or wait
1416     return 0;  // we did not sleep.
1417   }
1418 
1419   // remaining will be zero if there are no tasks,
1420   // causing the WatcherThread to sleep until a task is
1421   // enrolled
1422   int remaining = PeriodicTask::time_to_wait();
1423   int time_slept = 0;
1424 
1425   // we expect this to timeout - we only ever get unparked when
1426   // we should terminate or when a new task has been enrolled
1427   OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1428 
1429   jlong time_before_loop = os::javaTimeNanos();
1430 
1431   while (true) {
1432     bool timedout = ml.wait(remaining);
1433     jlong now = os::javaTimeNanos();
1434 
1435     if (remaining == 0) {
1436       // if we didn't have any tasks we could have waited for a long time
1437       // consider the time_slept zero and reset time_before_loop
1438       time_slept = 0;
1439       time_before_loop = now;
1440     } else {
1441       // need to recalculate since we might have new tasks in _tasks
1442       time_slept = (int) ((now - time_before_loop) / 1000000);
1443     }
1444 
1445     // Change to task list or spurious wakeup of some kind
1446     if (timedout || _should_terminate) {
1447       break;
1448     }
1449 
1450     remaining = PeriodicTask::time_to_wait();
1451     if (remaining == 0) {
1452       // Last task was just disenrolled so loop around and wait until
1453       // another task gets enrolled
1454       continue;
1455     }
1456 
1457     remaining -= time_slept;
1458     if (remaining <= 0) {
1459       break;
1460     }
1461   }
1462 
1463   return time_slept;
1464 }
1465 
1466 void WatcherThread::run() {
1467   assert(this == watcher_thread(), "just checking");
1468 
1469   this->set_active_handles(JNIHandleBlock::allocate_block());
1470   while (true) {
1471     assert(watcher_thread() == Thread::current(), "thread consistency check");
1472     assert(watcher_thread() == this, "thread consistency check");
1473 
1474     // Calculate how long it'll be until the next PeriodicTask work
1475     // should be done, and sleep that amount of time.
1476     int time_waited = sleep();
1477 
1478     if (VMError::is_error_reported()) {
1479       // A fatal error has happened, the error handler(VMError::report_and_die)
1480       // should abort JVM after creating an error log file. However in some
1481       // rare cases, the error handler itself might deadlock. Here periodically
1482       // check for error reporting timeouts, and if it happens, just proceed to
1483       // abort the VM.
1484 
1485       // This code is in WatcherThread because WatcherThread wakes up
1486       // periodically so the fatal error handler doesn't need to do anything;
1487       // also because the WatcherThread is less likely to crash than other
1488       // threads.
1489 
1490       for (;;) {
1491         // Note: we use naked sleep in this loop because we want to avoid using
1492         // any kind of VM infrastructure which may be broken at this point.
1493         if (VMError::check_timeout()) {
1494           // We hit error reporting timeout. Error reporting was interrupted and
1495           // will be wrapping things up now (closing files etc). Give it some more
1496           // time, then quit the VM.
1497           os::naked_short_sleep(200);
1498           // Print a message to stderr.
1499           fdStream err(defaultStream::output_fd());
1500           err.print_raw_cr("# [ timer expired, abort... ]");
1501           // skip atexit/vm_exit/vm_abort hooks
1502           os::die();
1503         }
1504 
1505         // Wait a second, then recheck for timeout.
1506         os::naked_short_sleep(999);
1507       }
1508     }
1509 
1510     if (_should_terminate) {
1511       // check for termination before posting the next tick
1512       break;
1513     }
1514 
1515     PeriodicTask::real_time_tick(time_waited);
1516   }
1517 
1518   // Signal that it is terminated
1519   {
1520     MutexLocker mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1521     _watcher_thread = NULL;
1522     Terminator_lock->notify_all();
1523   }
1524 }
1525 
1526 void WatcherThread::start() {
1527   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1528 
1529   if (watcher_thread() == NULL && _startable) {
1530     _should_terminate = false;
1531     // Create the single instance of WatcherThread
1532     new WatcherThread();
1533   }
1534 }
1535 
1536 void WatcherThread::make_startable() {
1537   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1538   _startable = true;
1539 }
1540 
1541 void WatcherThread::stop() {
1542   {
1543     // Follow normal safepoint aware lock enter protocol since the
1544     // WatcherThread is stopped by another JavaThread.
1545     MutexLocker ml(PeriodicTask_lock);
1546     _should_terminate = true;
1547 
1548     WatcherThread* watcher = watcher_thread();
1549     if (watcher != NULL) {
1550       // unpark the WatcherThread so it can see that it should terminate
1551       watcher->unpark();
1552     }
1553   }
1554 
1555   MonitorLocker mu(Terminator_lock);
1556 
1557   while (watcher_thread() != NULL) {
1558     // This wait should make safepoint checks, wait without a timeout,
1559     // and wait as a suspend-equivalent condition.
1560     mu.wait(0, Mutex::_as_suspend_equivalent_flag);
1561   }
1562 }
1563 
1564 void WatcherThread::unpark() {
1565   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1566   PeriodicTask_lock->notify();
1567 }
1568 
1569 void WatcherThread::print_on(outputStream* st) const {
1570   st->print("\"%s\" ", name());
1571   Thread::print_on(st);
1572   st->cr();
1573 }
1574 
1575 // ======= JavaThread ========
1576 
1577 #if INCLUDE_JVMCI
1578 
1579 jlong* JavaThread::_jvmci_old_thread_counters;
1580 
1581 bool jvmci_counters_include(JavaThread* thread) {
1582   return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1583 }
1584 
1585 void JavaThread::collect_counters(jlong* array, int length) {
1586   assert(length == JVMCICounterSize, "wrong value");
1587   for (int i = 0; i < length; i++) {
1588     array[i] = _jvmci_old_thread_counters[i];
1589   }
1590   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) {
1591     if (jvmci_counters_include(tp)) {
1592       for (int i = 0; i < length; i++) {
1593         array[i] += tp->_jvmci_counters[i];
1594       }
1595     }
1596   }
1597 }
1598 
1599 // Attempt to enlarge the array for per thread counters.
1600 jlong* resize_counters_array(jlong* old_counters, int current_size, int new_size) {
1601   jlong* new_counters = NEW_C_HEAP_ARRAY(jlong, new_size, mtJVMCI);
1602   if (new_counters == NULL) {
1603     return NULL;
1604   }
1605   if (old_counters == NULL) {
1606     old_counters = new_counters;
1607     memset(old_counters, 0, sizeof(jlong) * new_size);
1608   } else {
1609     for (int i = 0; i < MIN2((int) current_size, new_size); i++) {
1610       new_counters[i] = old_counters[i];
1611     }
1612     if (new_size > current_size) {
1613       memset(new_counters + current_size, 0, sizeof(jlong) * (new_size - current_size));
1614     }
1615     FREE_C_HEAP_ARRAY(jlong, old_counters);
1616   }
1617   return new_counters;
1618 }
1619 
1620 // Attempt to enlarge the array for per thread counters.
1621 bool JavaThread::resize_counters(int current_size, int new_size) {
1622   jlong* new_counters = resize_counters_array(_jvmci_counters, current_size, new_size);
1623   if (new_counters == NULL) {
1624     return false;
1625   } else {
1626     _jvmci_counters = new_counters;
1627     return true;
1628   }
1629 }
1630 
1631 class VM_JVMCIResizeCounters : public VM_Operation {
1632  private:
1633   int _new_size;
1634   bool _failed;
1635 
1636  public:
1637   VM_JVMCIResizeCounters(int new_size) : _new_size(new_size), _failed(false) { }
1638   VMOp_Type type()                  const        { return VMOp_JVMCIResizeCounters; }
1639   bool allow_nested_vm_operations() const        { return true; }
1640   void doit() {
1641     // Resize the old thread counters array
1642     jlong* new_counters = resize_counters_array(JavaThread::_jvmci_old_thread_counters, JVMCICounterSize, _new_size);
1643     if (new_counters == NULL) {
1644       _failed = true;
1645       return;
1646     } else {
1647       JavaThread::_jvmci_old_thread_counters = new_counters;
1648     }
1649 
1650     // Now resize each threads array
1651     for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) {
1652       if (!tp->resize_counters(JVMCICounterSize, _new_size)) {
1653         _failed = true;
1654         break;
1655       }
1656     }
1657     if (!_failed) {
1658       JVMCICounterSize = _new_size;
1659     }
1660   }
1661 
1662   bool failed() { return _failed; }
1663 };
1664 
1665 bool JavaThread::resize_all_jvmci_counters(int new_size) {
1666   VM_JVMCIResizeCounters op(new_size);
1667   VMThread::execute(&op);
1668   return !op.failed();
1669 }
1670 
1671 #endif // INCLUDE_JVMCI
1672 
1673 // A JavaThread is a normal Java thread
1674 
1675 void JavaThread::initialize() {
1676   // Initialize fields
1677 
1678   set_saved_exception_pc(NULL);
1679   set_threadObj(NULL);
1680   _anchor.clear();
1681   set_entry_point(NULL);
1682   set_jni_functions(jni_functions());
1683   set_callee_target(NULL);
1684   set_vm_result(NULL);
1685   set_vm_result_2(NULL);
1686   set_vframe_array_head(NULL);
1687   set_vframe_array_last(NULL);
1688   set_deferred_locals(NULL);
1689   set_keepalive_cleanup(new (ResourceObj::C_HEAP, mtInternal) GrowableArray<WeakHandle<vm_nmethod_keepalive_data> >(16, true));
1690   set_deopt_mark(NULL);
1691   set_deopt_compiled_method(NULL);
1692   clear_must_deopt_id();
1693   set_monitor_chunks(NULL);
1694   _on_thread_list = false;
1695   set_thread_state(_thread_new);
1696   _terminated = _not_terminated;
1697   _array_for_gc = NULL;
1698   _suspend_equivalent = false;
1699   _in_deopt_handler = 0;
1700   _doing_unsafe_access = false;
1701   _stack_guard_state = stack_guard_unused;
1702   DEBUG_ONLY(_continuation = NULL;)
1703 #if INCLUDE_JVMCI
1704   _pending_monitorenter = false;
1705   _pending_deoptimization = -1;
1706   _pending_failed_speculation = 0;
1707   _pending_transfer_to_interpreter = false;
1708   _in_retryable_allocation = false;
1709   _jvmci._alternate_call_target = NULL;
1710   assert(_jvmci._implicit_exception_pc == NULL, "must be");
1711   _jvmci_counters = NULL;
1712   if (JVMCICounterSize > 0) {
1713     resize_counters(0, (int) JVMCICounterSize);
1714   }
1715 #endif // INCLUDE_JVMCI
1716   _reserved_stack_activation = NULL;  // stack base not known yet
1717   (void)const_cast<oop&>(_exception_oop = oop(NULL));
1718   _exception_pc  = 0;
1719   _exception_handler_pc = 0;
1720   _is_method_handle_return = 0;
1721   _jvmti_thread_state= NULL;
1722   _should_post_on_exceptions_flag = JNI_FALSE;
1723   _interp_only_mode    = 0;
1724   _special_runtime_exit_condition = _no_async_condition;
1725   _pending_async_exception = NULL;
1726   _thread_stat = NULL;
1727   _thread_stat = new ThreadStatistics();
1728   _blocked_on_compilation = false;
1729   _jni_active_critical = 0;
1730   _pending_jni_exception_check_fn = NULL;
1731   _do_not_unlock_if_synchronized = false;
1732   _cached_monitor_info = NULL;
1733   _parker = Parker::Allocate(this);
1734 
1735   _cont_yield = false;
1736   _cont_preempt = false;
1737   _cont_fastpath = 0;
1738   memset(&_cont_frame, 0, sizeof(FrameInfo));
1739 
1740 #ifndef PRODUCT
1741   _jmp_ring_index = 0;
1742   for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1743     record_jump(NULL, NULL, NULL, 0);
1744   }
1745 #endif // PRODUCT
1746 
1747   // Setup safepoint state info for this thread
1748   ThreadSafepointState::create(this);
1749 
1750   debug_only(_java_call_counter = 0);
1751 
1752   // JVMTI PopFrame support
1753   _popframe_condition = popframe_inactive;
1754   _popframe_preserved_args = NULL;
1755   _popframe_preserved_args_size = 0;
1756   _frames_to_pop_failed_realloc = 0;
1757 
1758   if (SafepointMechanism::uses_thread_local_poll()) {
1759     SafepointMechanism::initialize_header(this);
1760   }
1761 
1762   _class_to_be_initialized = NULL;
1763 
1764   pd_initialize();
1765 }
1766 
1767 JavaThread::JavaThread(bool is_attaching_via_jni) :
1768                        Thread() {
1769   initialize();
1770   if (is_attaching_via_jni) {
1771     _jni_attach_state = _attaching_via_jni;
1772   } else {
1773     _jni_attach_state = _not_attaching_via_jni;
1774   }
1775   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1776 }
1777 
1778 bool JavaThread::reguard_stack(address cur_sp) {
1779   if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1780       && _stack_guard_state != stack_guard_reserved_disabled) {
1781     return true; // Stack already guarded or guard pages not needed.
1782   }
1783 
1784   if (register_stack_overflow()) {
1785     // For those architectures which have separate register and
1786     // memory stacks, we must check the register stack to see if
1787     // it has overflowed.
1788     return false;
1789   }
1790 
1791   // Java code never executes within the yellow zone: the latter is only
1792   // there to provoke an exception during stack banging.  If java code
1793   // is executing there, either StackShadowPages should be larger, or
1794   // some exception code in c1, c2 or the interpreter isn't unwinding
1795   // when it should.
1796   guarantee(cur_sp > stack_reserved_zone_base(),
1797             "not enough space to reguard - increase StackShadowPages");
1798   if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1799     enable_stack_yellow_reserved_zone();
1800     if (reserved_stack_activation() != stack_base()) {
1801       set_reserved_stack_activation(stack_base());
1802     }
1803   } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1804     set_reserved_stack_activation(stack_base());
1805     enable_stack_reserved_zone();
1806   }
1807   return true;
1808 }
1809 
1810 bool JavaThread::reguard_stack(void) {
1811   return reguard_stack(os::current_stack_pointer());
1812 }
1813 
1814 
1815 void JavaThread::block_if_vm_exited() {
1816   if (_terminated == _vm_exited) {
1817     // _vm_exited is set at safepoint, and Threads_lock is never released
1818     // we will block here forever
1819     Threads_lock->lock();
1820     ShouldNotReachHere();
1821   }
1822 }
1823 
1824 
1825 // Remove this ifdef when C1 is ported to the compiler interface.
1826 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1827 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1828 
1829 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1830                        Thread() {
1831   initialize();
1832   _jni_attach_state = _not_attaching_via_jni;
1833   set_entry_point(entry_point);
1834   // Create the native thread itself.
1835   // %note runtime_23
1836   os::ThreadType thr_type = os::java_thread;
1837   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1838                                                      os::java_thread;
1839   os::create_thread(this, thr_type, stack_sz);
1840   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1841   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1842   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1843   // the exception consists of creating the exception object & initializing it, initialization
1844   // will leave the VM via a JavaCall and then all locks must be unlocked).
1845   //
1846   // The thread is still suspended when we reach here. Thread must be explicit started
1847   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1848   // by calling Threads:add. The reason why this is not done here, is because the thread
1849   // object must be fully initialized (take a look at JVM_Start)
1850 }
1851 
1852 JavaThread::~JavaThread() {
1853 
1854   // JSR166 -- return the parker to the free list
1855   Parker::Release(_parker);
1856   _parker = NULL;
1857 
1858   // Free any remaining  previous UnrollBlock
1859   vframeArray* old_array = vframe_array_last();
1860 
1861   if (old_array != NULL) {
1862     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1863     old_array->set_unroll_block(NULL);
1864     delete old_info;
1865     delete old_array;
1866   }
1867 
1868   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1869   if (deferred != NULL) {
1870     // This can only happen if thread is destroyed before deoptimization occurs.
1871     assert(deferred->length() != 0, "empty array!");
1872     do {
1873       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1874       deferred->remove_at(0);
1875       // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1876       delete dlv;
1877     } while (deferred->length() != 0);
1878     delete deferred;
1879   }
1880 
1881   // All Java related clean up happens in exit
1882   ThreadSafepointState::destroy(this);
1883   if (_thread_stat != NULL) delete _thread_stat;
1884 
1885 #if INCLUDE_JVMCI
1886   if (JVMCICounterSize > 0) {
1887     if (jvmci_counters_include(this)) {
1888       for (int i = 0; i < JVMCICounterSize; i++) {
1889         _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1890       }
1891     }
1892     FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1893   }
1894 #endif // INCLUDE_JVMCI
1895 }
1896 
1897 
1898 // First JavaThread specific code executed by a new Java thread.
1899 void JavaThread::pre_run() {
1900   // empty - see comments in run()
1901 }
1902 
1903 // The main routine called by a new Java thread. This isn't overridden
1904 // by subclasses, instead different subclasses define a different "entry_point"
1905 // which defines the actual logic for that kind of thread.
1906 void JavaThread::run() {
1907   // initialize thread-local alloc buffer related fields
1908   this->initialize_tlab();
1909 
1910   // Used to test validity of stack trace backs.
1911   // This can't be moved into pre_run() else we invalidate
1912   // the requirement that thread_main_inner is lower on
1913   // the stack. Consequently all the initialization logic
1914   // stays here in run() rather than pre_run().
1915   this->record_base_of_stack_pointer();
1916 
1917   this->create_stack_guard_pages();
1918 
1919   this->cache_global_variables();
1920 
1921   // Thread is now sufficiently initialized to be handled by the safepoint code as being
1922   // in the VM. Change thread state from _thread_new to _thread_in_vm
1923   ThreadStateTransition::transition(this, _thread_new, _thread_in_vm);
1924   // Before a thread is on the threads list it is always safe, so after leaving the
1925   // _thread_new we should emit a instruction barrier. The distance to modified code
1926   // from here is probably far enough, but this is consistent and safe.
1927   OrderAccess::cross_modify_fence();
1928 
1929   assert(JavaThread::current() == this, "sanity check");
1930   assert(!Thread::current()->owns_locks(), "sanity check");
1931 
1932   DTRACE_THREAD_PROBE(start, this);
1933 
1934   // This operation might block. We call that after all safepoint checks for a new thread has
1935   // been completed.
1936   this->set_active_handles(JNIHandleBlock::allocate_block());
1937 
1938   if (JvmtiExport::should_post_thread_life()) {
1939     JvmtiExport::post_thread_start(this);
1940 
1941   }
1942 
1943   // We call another function to do the rest so we are sure that the stack addresses used
1944   // from there will be lower than the stack base just computed.
1945   thread_main_inner();
1946 }
1947 
1948 void JavaThread::thread_main_inner() {
1949   assert(JavaThread::current() == this, "sanity check");
1950   assert(this->threadObj() != NULL, "just checking");
1951 
1952   // Execute thread entry point unless this thread has a pending exception
1953   // or has been stopped before starting.
1954   // Note: Due to JVM_StopThread we can have pending exceptions already!
1955   if (!this->has_pending_exception() &&
1956       !java_lang_Thread::is_stillborn(this->threadObj())) {
1957     {
1958       ResourceMark rm(this);
1959       this->set_native_thread_name(this->get_thread_name());
1960     }
1961     HandleMark hm(this);
1962     this->entry_point()(this, this);
1963   }
1964 
1965   DTRACE_THREAD_PROBE(stop, this);
1966 
1967   // Cleanup is handled in post_run()
1968 }
1969 
1970 // Shared teardown for all JavaThreads
1971 void JavaThread::post_run() {
1972   this->exit(false);
1973   // Defer deletion to here to ensure 'this' is still referenceable in call_run
1974   // for any shared tear-down.
1975   this->smr_delete();
1976 }
1977 
1978 static void ensure_join(JavaThread* thread) {
1979   // We do not need to grab the Threads_lock, since we are operating on ourself.
1980   Handle threadObj(thread, thread->threadObj());
1981   assert(threadObj.not_null(), "java thread object must exist");
1982   ObjectLocker lock(threadObj, thread);
1983   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1984   thread->clear_pending_exception();
1985   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1986   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1987   // Clear the native thread instance - this makes isAlive return false and allows the join()
1988   // to complete once we've done the notify_all below
1989   java_lang_Thread::set_thread(threadObj(), NULL);
1990   lock.notify_all(thread);
1991   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1992   thread->clear_pending_exception();
1993 }
1994 
1995 static bool is_daemon(oop threadObj) {
1996   return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj));
1997 }
1998 
1999 // For any new cleanup additions, please check to see if they need to be applied to
2000 // cleanup_failed_attach_current_thread as well.
2001 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
2002   assert(this == JavaThread::current(), "thread consistency check");
2003 
2004   elapsedTimer _timer_exit_phase1;
2005   elapsedTimer _timer_exit_phase2;
2006   elapsedTimer _timer_exit_phase3;
2007   elapsedTimer _timer_exit_phase4;
2008 
2009   if (log_is_enabled(Debug, os, thread, timer)) {
2010     _timer_exit_phase1.start();
2011   }
2012 
2013   HandleMark hm(this);
2014   Handle uncaught_exception(this, this->pending_exception());
2015   this->clear_pending_exception();
2016   Handle threadObj(this, this->threadObj());
2017   assert(threadObj.not_null(), "Java thread object should be created");
2018 
2019   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
2020   {
2021     EXCEPTION_MARK;
2022 
2023     CLEAR_PENDING_EXCEPTION;
2024   }
2025   if (!destroy_vm) {
2026     if (uncaught_exception.not_null()) {
2027       EXCEPTION_MARK;
2028       // Call method Thread.dispatchUncaughtException().
2029       Klass* thread_klass = SystemDictionary::Thread_klass();
2030       JavaValue result(T_VOID);
2031       JavaCalls::call_virtual(&result,
2032                               threadObj, thread_klass,
2033                               vmSymbols::dispatchUncaughtException_name(),
2034                               vmSymbols::throwable_void_signature(),
2035                               uncaught_exception,
2036                               THREAD);
2037       if (HAS_PENDING_EXCEPTION) {
2038         ResourceMark rm(this);
2039         jio_fprintf(defaultStream::error_stream(),
2040                     "\nException: %s thrown from the UncaughtExceptionHandler"
2041                     " in thread \"%s\"\n",
2042                     pending_exception()->klass()->external_name(),
2043                     get_thread_name());
2044         CLEAR_PENDING_EXCEPTION;
2045       }
2046     }
2047     JFR_ONLY(Jfr::on_java_thread_dismantle(this);)
2048 
2049     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
2050     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
2051     // is deprecated anyhow.
2052     if (!is_Compiler_thread()) {
2053       int count = 3;
2054       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
2055         EXCEPTION_MARK;
2056         JavaValue result(T_VOID);
2057         Klass* thread_klass = SystemDictionary::Thread_klass();
2058         JavaCalls::call_virtual(&result,
2059                                 threadObj, thread_klass,
2060                                 vmSymbols::exit_method_name(),
2061                                 vmSymbols::void_method_signature(),
2062                                 THREAD);
2063         CLEAR_PENDING_EXCEPTION;
2064       }
2065     }
2066     // notify JVMTI
2067     if (JvmtiExport::should_post_thread_life()) {
2068       JvmtiExport::post_thread_end(this);
2069     }
2070 
2071     // We have notified the agents that we are exiting, before we go on,
2072     // we must check for a pending external suspend request and honor it
2073     // in order to not surprise the thread that made the suspend request.
2074     while (true) {
2075       {
2076         MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2077         if (!is_external_suspend()) {
2078           set_terminated(_thread_exiting);
2079           ThreadService::current_thread_exiting(this, is_daemon(threadObj()));
2080           break;
2081         }
2082         // Implied else:
2083         // Things get a little tricky here. We have a pending external
2084         // suspend request, but we are holding the SR_lock so we
2085         // can't just self-suspend. So we temporarily drop the lock
2086         // and then self-suspend.
2087       }
2088 
2089       ThreadBlockInVM tbivm(this);
2090       java_suspend_self();
2091 
2092       // We're done with this suspend request, but we have to loop around
2093       // and check again. Eventually we will get SR_lock without a pending
2094       // external suspend request and will be able to mark ourselves as
2095       // exiting.
2096     }
2097     // no more external suspends are allowed at this point
2098   } else {
2099     assert(!is_terminated() && !is_exiting(), "must not be exiting");
2100     // before_exit() has already posted JVMTI THREAD_END events
2101   }
2102 
2103   if (log_is_enabled(Debug, os, thread, timer)) {
2104     _timer_exit_phase1.stop();
2105     _timer_exit_phase2.start();
2106   }
2107 
2108   // Capture daemon status before the thread is marked as terminated.
2109   bool daemon = is_daemon(threadObj());
2110 
2111   // Notify waiters on thread object. This has to be done after exit() is called
2112   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
2113   // group should have the destroyed bit set before waiters are notified).
2114   ensure_join(this);
2115   assert(!this->has_pending_exception(), "ensure_join should have cleared");
2116 
2117   if (log_is_enabled(Debug, os, thread, timer)) {
2118     _timer_exit_phase2.stop();
2119     _timer_exit_phase3.start();
2120   }
2121   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
2122   // held by this thread must be released. The spec does not distinguish
2123   // between JNI-acquired and regular Java monitors. We can only see
2124   // regular Java monitors here if monitor enter-exit matching is broken.
2125   //
2126   // ensure_join() ignores IllegalThreadStateExceptions, and so does
2127   // ObjectSynchronizer::release_monitors_owned_by_thread().
2128   if (exit_type == jni_detach) {
2129     // Sanity check even though JNI DetachCurrentThread() would have
2130     // returned JNI_ERR if there was a Java frame. JavaThread exit
2131     // should be done executing Java code by the time we get here.
2132     assert(!this->has_last_Java_frame(),
2133            "should not have a Java frame when detaching or exiting");
2134     ObjectSynchronizer::release_monitors_owned_by_thread(this);
2135     assert(!this->has_pending_exception(), "release_monitors should have cleared");
2136   }
2137 
2138   // These things needs to be done while we are still a Java Thread. Make sure that thread
2139   // is in a consistent state, in case GC happens
2140   JFR_ONLY(Jfr::on_thread_exit(this);)
2141 
2142   if (active_handles() != NULL) {
2143     JNIHandleBlock* block = active_handles();
2144     set_active_handles(NULL);
2145     JNIHandleBlock::release_block(block);
2146   }
2147 
2148   if (free_handle_block() != NULL) {
2149     JNIHandleBlock* block = free_handle_block();
2150     set_free_handle_block(NULL);
2151     JNIHandleBlock::release_block(block);
2152   }
2153 
2154   // These have to be removed while this is still a valid thread.
2155   remove_stack_guard_pages();
2156 
2157   if (UseTLAB) {
2158     tlab().retire();
2159   }
2160 
2161   if (JvmtiEnv::environments_might_exist()) {
2162     JvmtiExport::cleanup_thread(this);
2163   }
2164 
2165   // We must flush any deferred card marks and other various GC barrier
2166   // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
2167   // before removing a thread from the list of active threads.
2168   BarrierSet::barrier_set()->on_thread_detach(this);
2169 
2170   log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2171     exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2172     os::current_thread_id());
2173 
2174   if (log_is_enabled(Debug, os, thread, timer)) {
2175     _timer_exit_phase3.stop();
2176     _timer_exit_phase4.start();
2177   }
2178   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2179   Threads::remove(this, daemon);
2180 
2181   if (log_is_enabled(Debug, os, thread, timer)) {
2182     _timer_exit_phase4.stop();
2183     ResourceMark rm(this);
2184     log_debug(os, thread, timer)("name='%s'"
2185                                  ", exit-phase1=" JLONG_FORMAT
2186                                  ", exit-phase2=" JLONG_FORMAT
2187                                  ", exit-phase3=" JLONG_FORMAT
2188                                  ", exit-phase4=" JLONG_FORMAT,
2189                                  get_thread_name(),
2190                                  _timer_exit_phase1.milliseconds(),
2191                                  _timer_exit_phase2.milliseconds(),
2192                                  _timer_exit_phase3.milliseconds(),
2193                                  _timer_exit_phase4.milliseconds());
2194   }
2195 }
2196 
2197 void JavaThread::cleanup_failed_attach_current_thread(bool is_daemon) {
2198   if (active_handles() != NULL) {
2199     JNIHandleBlock* block = active_handles();
2200     set_active_handles(NULL);
2201     JNIHandleBlock::release_block(block);
2202   }
2203 
2204   if (free_handle_block() != NULL) {
2205     JNIHandleBlock* block = free_handle_block();
2206     set_free_handle_block(NULL);
2207     JNIHandleBlock::release_block(block);
2208   }
2209 
2210   // These have to be removed while this is still a valid thread.
2211   remove_stack_guard_pages();
2212 
2213   if (UseTLAB) {
2214     tlab().retire();
2215   }
2216 
2217   BarrierSet::barrier_set()->on_thread_detach(this);
2218 
2219   Threads::remove(this, is_daemon);
2220   this->smr_delete();
2221 }
2222 
2223 JavaThread* JavaThread::active() {
2224   Thread* thread = Thread::current();
2225   if (thread->is_Java_thread()) {
2226     return (JavaThread*) thread;
2227   } else {
2228     assert(thread->is_VM_thread(), "this must be a vm thread");
2229     VM_Operation* op = ((VMThread*) thread)->vm_operation();
2230     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2231     assert(ret->is_Java_thread(), "must be a Java thread");
2232     return ret;
2233   }
2234 }
2235 
2236 bool JavaThread::is_lock_owned(address adr) const {
2237   if (Thread::is_lock_owned(adr)) return true;
2238 
2239   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2240     if (chunk->contains(adr)) return true;
2241   }
2242 
2243   return false;
2244 }
2245 
2246 
2247 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2248   chunk->set_next(monitor_chunks());
2249   set_monitor_chunks(chunk);
2250 }
2251 
2252 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2253   guarantee(monitor_chunks() != NULL, "must be non empty");
2254   if (monitor_chunks() == chunk) {
2255     set_monitor_chunks(chunk->next());
2256   } else {
2257     MonitorChunk* prev = monitor_chunks();
2258     while (prev->next() != chunk) prev = prev->next();
2259     prev->set_next(chunk->next());
2260   }
2261 }
2262 
2263 // JVM support.
2264 
2265 // Note: this function shouldn't block if it's called in
2266 // _thread_in_native_trans state (such as from
2267 // check_special_condition_for_native_trans()).
2268 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2269 
2270   if (has_last_Java_frame() && has_async_condition()) {
2271     // If we are at a polling page safepoint (not a poll return)
2272     // then we must defer async exception because live registers
2273     // will be clobbered by the exception path. Poll return is
2274     // ok because the call we a returning from already collides
2275     // with exception handling registers and so there is no issue.
2276     // (The exception handling path kills call result registers but
2277     //  this is ok since the exception kills the result anyway).
2278 
2279     if (is_at_poll_safepoint()) {
2280       // if the code we are returning to has deoptimized we must defer
2281       // the exception otherwise live registers get clobbered on the
2282       // exception path before deoptimization is able to retrieve them.
2283       //
2284       RegisterMap map(this, false);
2285       frame caller_fr = last_frame().sender(&map);
2286       assert(caller_fr.is_compiled_frame(), "what?");
2287       if (caller_fr.is_deoptimized_frame()) {
2288         log_info(exceptions)("deferred async exception at compiled safepoint");
2289         return;
2290       }
2291     }
2292   }
2293 
2294   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2295   if (condition == _no_async_condition) {
2296     // Conditions have changed since has_special_runtime_exit_condition()
2297     // was called:
2298     // - if we were here only because of an external suspend request,
2299     //   then that was taken care of above (or cancelled) so we are done
2300     // - if we were here because of another async request, then it has
2301     //   been cleared between the has_special_runtime_exit_condition()
2302     //   and now so again we are done
2303     return;
2304   }
2305 
2306   // Check for pending async. exception
2307   if (_pending_async_exception != NULL) {
2308     // Only overwrite an already pending exception, if it is not a threadDeath.
2309     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2310 
2311       // We cannot call Exceptions::_throw(...) here because we cannot block
2312       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2313 
2314       LogTarget(Info, exceptions) lt;
2315       if (lt.is_enabled()) {
2316         ResourceMark rm;
2317         LogStream ls(lt);
2318         ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2319           if (has_last_Java_frame()) {
2320             frame f = last_frame();
2321            ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2322           }
2323         ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2324       }
2325       _pending_async_exception = NULL;
2326       clear_has_async_exception();
2327     }
2328   }
2329 
2330   if (check_unsafe_error &&
2331       condition == _async_unsafe_access_error && !has_pending_exception()) {
2332     condition = _no_async_condition;  // done
2333     switch (thread_state()) {
2334     case _thread_in_vm: {
2335       JavaThread* THREAD = this;
2336       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2337     }
2338     case _thread_in_native: {
2339       ThreadInVMfromNative tiv(this);
2340       JavaThread* THREAD = this;
2341       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2342     }
2343     case _thread_in_Java: {
2344       ThreadInVMfromJava tiv(this);
2345       JavaThread* THREAD = this;
2346       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2347     }
2348     default:
2349       ShouldNotReachHere();
2350     }
2351   }
2352 
2353   assert(condition == _no_async_condition || has_pending_exception() ||
2354          (!check_unsafe_error && condition == _async_unsafe_access_error),
2355          "must have handled the async condition, if no exception");
2356 }
2357 
2358 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2359 
2360   // Check for pending external suspend.
2361   if (is_external_suspend_with_lock()) {
2362     frame_anchor()->make_walkable(this);
2363     java_suspend_self_with_safepoint_check();
2364   }
2365 
2366   // We might be here for reasons in addition to the self-suspend request
2367   // so check for other async requests.
2368   if (check_asyncs) {
2369     check_and_handle_async_exceptions();
2370   }
2371 
2372   if (is_cont_force_yield()) {
2373     log_develop_trace(jvmcont)("handle_special_runtime_exit_condition is_cont_force_yield: %d check_asyncs: %d", is_cont_force_yield(), check_asyncs);
2374     if (check_asyncs) { // TODO: we should probably be even more selective than that
2375       // we need this only for interpreted frames -- for compiled frames we install a return barrier on the safepoint stub in Continuation::try_force_yield
2376       StubRoutines::cont_jump_from_sp_C()();
2377     }
2378   }
2379 
2380   JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
2381 }
2382 
2383 void JavaThread::send_thread_stop(oop java_throwable)  {
2384   assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2385   assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2386   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2387 
2388   // Do not throw asynchronous exceptions against the compiler thread
2389   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2390   if (!can_call_java()) return;
2391 
2392   {
2393     // Actually throw the Throwable against the target Thread - however
2394     // only if there is no thread death exception installed already.
2395     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2396       // If the topmost frame is a runtime stub, then we are calling into
2397       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2398       // must deoptimize the caller before continuing, as the compiled  exception handler table
2399       // may not be valid
2400       if (has_last_Java_frame()) {
2401         frame f = last_frame();
2402         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2403           // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2404           RegisterMap reg_map(this, UseBiasedLocking);
2405           frame compiled_frame = f.sender(&reg_map);
2406           if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2407             Deoptimization::deoptimize(this, compiled_frame, &reg_map);
2408           }
2409         }
2410       }
2411 
2412       // Set async. pending exception in thread.
2413       set_pending_async_exception(java_throwable);
2414 
2415       if (log_is_enabled(Info, exceptions)) {
2416          ResourceMark rm;
2417         log_info(exceptions)("Pending Async. exception installed of type: %s",
2418                              InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2419       }
2420       // for AbortVMOnException flag
2421       Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2422     }
2423   }
2424 
2425 
2426   // Interrupt thread so it will wake up from a potential wait()
2427   Thread::interrupt(this);
2428 }
2429 
2430 // External suspension mechanism.
2431 //
2432 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2433 // to any VM_locks and it is at a transition
2434 // Self-suspension will happen on the transition out of the vm.
2435 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2436 //
2437 // Guarantees on return:
2438 //   + Target thread will not execute any new bytecode (that's why we need to
2439 //     force a safepoint)
2440 //   + Target thread will not enter any new monitors
2441 //
2442 void JavaThread::java_suspend() {
2443   ThreadsListHandle tlh;
2444   if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2445     return;
2446   }
2447 
2448   { MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2449     if (!is_external_suspend()) {
2450       // a racing resume has cancelled us; bail out now
2451       return;
2452     }
2453 
2454     // suspend is done
2455     uint32_t debug_bits = 0;
2456     // Warning: is_ext_suspend_completed() may temporarily drop the
2457     // SR_lock to allow the thread to reach a stable thread state if
2458     // it is currently in a transient thread state.
2459     if (is_ext_suspend_completed(false /* !called_by_wait */,
2460                                  SuspendRetryDelay, &debug_bits)) {
2461       return;
2462     }
2463   }
2464 
2465   if (Thread::current() == this) {
2466     // Safely self-suspend.
2467     // If we don't do this explicitly it will implicitly happen
2468     // before we transition back to Java, and on some other thread-state
2469     // transition paths, but not as we exit a JVM TI SuspendThread call.
2470     // As SuspendThread(current) must not return (until resumed) we must
2471     // self-suspend here.
2472     ThreadBlockInVM tbivm(this);
2473     java_suspend_self();
2474   } else {
2475     VM_ThreadSuspend vm_suspend;
2476     VMThread::execute(&vm_suspend);
2477   }
2478 }
2479 
2480 // Part II of external suspension.
2481 // A JavaThread self suspends when it detects a pending external suspend
2482 // request. This is usually on transitions. It is also done in places
2483 // where continuing to the next transition would surprise the caller,
2484 // e.g., monitor entry.
2485 //
2486 // Returns the number of times that the thread self-suspended.
2487 //
2488 // Note: DO NOT call java_suspend_self() when you just want to block current
2489 //       thread. java_suspend_self() is the second stage of cooperative
2490 //       suspension for external suspend requests and should only be used
2491 //       to complete an external suspend request.
2492 //
2493 int JavaThread::java_suspend_self() {
2494   assert(thread_state() == _thread_blocked, "wrong state for java_suspend_self()");
2495   int ret = 0;
2496 
2497   // we are in the process of exiting so don't suspend
2498   if (is_exiting()) {
2499     clear_external_suspend();
2500     return ret;
2501   }
2502 
2503   assert(_anchor.walkable() ||
2504          (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2505          "must have walkable stack");
2506 
2507   MonitorLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2508 
2509   assert(!this->is_ext_suspended(),
2510          "a thread trying to self-suspend should not already be suspended");
2511 
2512   if (this->is_suspend_equivalent()) {
2513     // If we are self-suspending as a result of the lifting of a
2514     // suspend equivalent condition, then the suspend_equivalent
2515     // flag is not cleared until we set the ext_suspended flag so
2516     // that wait_for_ext_suspend_completion() returns consistent
2517     // results.
2518     this->clear_suspend_equivalent();
2519   }
2520 
2521   // A racing resume may have cancelled us before we grabbed SR_lock
2522   // above. Or another external suspend request could be waiting for us
2523   // by the time we return from SR_lock()->wait(). The thread
2524   // that requested the suspension may already be trying to walk our
2525   // stack and if we return now, we can change the stack out from under
2526   // it. This would be a "bad thing (TM)" and cause the stack walker
2527   // to crash. We stay self-suspended until there are no more pending
2528   // external suspend requests.
2529   while (is_external_suspend()) {
2530     ret++;
2531     this->set_ext_suspended();
2532 
2533     // _ext_suspended flag is cleared by java_resume()
2534     while (is_ext_suspended()) {
2535       ml.wait();
2536     }
2537   }
2538   return ret;
2539 }
2540 
2541 // Helper routine to set up the correct thread state before calling java_suspend_self.
2542 // This is called when regular thread-state transition helpers can't be used because
2543 // we can be in various states, in particular _thread_in_native_trans.
2544 // Because this thread is external suspended the safepoint code will count it as at
2545 // a safepoint, regardless of what its actual current thread-state is. But
2546 // is_ext_suspend_completed() may be waiting to see a thread transition from
2547 // _thread_in_native_trans to _thread_blocked. So we set the thread state directly
2548 // to _thread_blocked. The problem with setting thread state directly is that a
2549 // safepoint could happen just after java_suspend_self() returns after being resumed,
2550 // and the VM thread will see the _thread_blocked state. So we must check for a safepoint
2551 // after restoring the state to make sure we won't leave while a safepoint is in progress.
2552 // However, not all initial-states are allowed when performing a safepoint check, as we
2553 // should never be blocking at a safepoint whilst in those states. Of these 'bad' states
2554 // only _thread_in_native is possible when executing this code (based on our two callers).
2555 // A thread that is _thread_in_native is already safepoint-safe and so it doesn't matter
2556 // whether the VMThread sees the _thread_blocked state, or the _thread_in_native state,
2557 // and so we don't need the explicit safepoint check.
2558 
2559 void JavaThread::java_suspend_self_with_safepoint_check() {
2560   assert(this == Thread::current(), "invariant");
2561   JavaThreadState state = thread_state();
2562   set_thread_state(_thread_blocked);
2563   java_suspend_self();
2564   set_thread_state_fence(state);
2565   // Since we are not using a regular thread-state transition helper here,
2566   // we must manually emit the instruction barrier after leaving a safe state.
2567   OrderAccess::cross_modify_fence();
2568   if (state != _thread_in_native) {
2569     SafepointMechanism::block_if_requested(this);
2570   }
2571 }
2572 
2573 #ifdef ASSERT
2574 // Verify the JavaThread has not yet been published in the Threads::list, and
2575 // hence doesn't need protection from concurrent access at this stage.
2576 void JavaThread::verify_not_published() {
2577   // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
2578   // since an unpublished JavaThread doesn't participate in the
2579   // Thread-SMR protocol for keeping a ThreadsList alive.
2580   assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
2581 }
2582 #endif
2583 
2584 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2585 // progress or when _suspend_flags is non-zero.
2586 // Current thread needs to self-suspend if there is a suspend request and/or
2587 // block if a safepoint is in progress.
2588 // Async exception ISN'T checked.
2589 // Note only the ThreadInVMfromNative transition can call this function
2590 // directly and when thread state is _thread_in_native_trans
2591 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2592   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2593 
2594   assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2595 
2596   if (thread->is_external_suspend()) {
2597     thread->java_suspend_self_with_safepoint_check();
2598   } else {
2599     SafepointMechanism::block_if_requested(thread);
2600   }
2601 
2602   JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);)
2603 }
2604 
2605 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2606 // progress or when _suspend_flags is non-zero.
2607 // Current thread needs to self-suspend if there is a suspend request and/or
2608 // block if a safepoint is in progress.
2609 // Also check for pending async exception (not including unsafe access error).
2610 // Note only the native==>VM/Java barriers can call this function and when
2611 // thread state is _thread_in_native_trans.
2612 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2613   check_safepoint_and_suspend_for_native_trans(thread);
2614 
2615   if (thread->has_async_exception()) {
2616     // We are in _thread_in_native_trans state, don't handle unsafe
2617     // access error since that may block.
2618     thread->check_and_handle_async_exceptions(false);
2619   }
2620 }
2621 
2622 // This is a variant of the normal
2623 // check_special_condition_for_native_trans with slightly different
2624 // semantics for use by critical native wrappers.  It does all the
2625 // normal checks but also performs the transition back into
2626 // thread_in_Java state.  This is required so that critical natives
2627 // can potentially block and perform a GC if they are the last thread
2628 // exiting the GCLocker.
2629 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2630   check_special_condition_for_native_trans(thread);
2631 
2632   // Finish the transition
2633   thread->set_thread_state(_thread_in_Java);
2634 
2635   if (thread->do_critical_native_unlock()) {
2636     ThreadInVMfromJavaNoAsyncException tiv(thread);
2637     GCLocker::unlock_critical(thread);
2638     thread->clear_critical_native_unlock();
2639   }
2640 }
2641 
2642 // We need to guarantee the Threads_lock here, since resumes are not
2643 // allowed during safepoint synchronization
2644 // Can only resume from an external suspension
2645 void JavaThread::java_resume() {
2646   assert_locked_or_safepoint(Threads_lock);
2647 
2648   // Sanity check: thread is gone, has started exiting or the thread
2649   // was not externally suspended.
2650   ThreadsListHandle tlh;
2651   if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2652     return;
2653   }
2654 
2655   MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2656 
2657   clear_external_suspend();
2658 
2659   if (is_ext_suspended()) {
2660     clear_ext_suspended();
2661     SR_lock()->notify_all();
2662   }
2663 }
2664 
2665 size_t JavaThread::_stack_red_zone_size = 0;
2666 size_t JavaThread::_stack_yellow_zone_size = 0;
2667 size_t JavaThread::_stack_reserved_zone_size = 0;
2668 size_t JavaThread::_stack_shadow_zone_size = 0;
2669 
2670 void JavaThread::create_stack_guard_pages() {
2671   if (!os::uses_stack_guard_pages() ||
2672       _stack_guard_state != stack_guard_unused ||
2673       (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2674       log_info(os, thread)("Stack guard page creation for thread "
2675                            UINTX_FORMAT " disabled", os::current_thread_id());
2676     return;
2677   }
2678   address low_addr = stack_end();
2679   size_t len = stack_guard_zone_size();
2680 
2681   assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2682   assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2683 
2684   int must_commit = os::must_commit_stack_guard_pages();
2685   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2686 
2687   if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2688     log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2689     return;
2690   }
2691 
2692   if (os::guard_memory((char *) low_addr, len)) {
2693     _stack_guard_state = stack_guard_enabled;
2694   } else {
2695     log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2696       PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2697     if (os::uncommit_memory((char *) low_addr, len)) {
2698       log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2699     }
2700     return;
2701   }
2702 
2703   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2704     PTR_FORMAT "-" PTR_FORMAT ".",
2705     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2706 }
2707 
2708 void JavaThread::remove_stack_guard_pages() {
2709   assert(Thread::current() == this, "from different thread");
2710   if (_stack_guard_state == stack_guard_unused) return;
2711   address low_addr = stack_end();
2712   size_t len = stack_guard_zone_size();
2713 
2714   if (os::must_commit_stack_guard_pages()) {
2715     if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2716       _stack_guard_state = stack_guard_unused;
2717     } else {
2718       log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2719         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2720       return;
2721     }
2722   } else {
2723     if (_stack_guard_state == stack_guard_unused) return;
2724     if (os::unguard_memory((char *) low_addr, len)) {
2725       _stack_guard_state = stack_guard_unused;
2726     } else {
2727       log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2728         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2729       return;
2730     }
2731   }
2732 
2733   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2734     PTR_FORMAT "-" PTR_FORMAT ".",
2735     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2736 }
2737 
2738 void JavaThread::enable_stack_reserved_zone() {
2739   assert(_stack_guard_state == stack_guard_reserved_disabled, "inconsistent state");
2740 
2741   // The base notation is from the stack's point of view, growing downward.
2742   // We need to adjust it to work correctly with guard_memory()
2743   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2744 
2745   guarantee(base < stack_base(),"Error calculating stack reserved zone");
2746   guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2747 
2748   if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2749     _stack_guard_state = stack_guard_enabled;
2750   } else {
2751     warning("Attempt to guard stack reserved zone failed.");
2752   }
2753   enable_register_stack_guard();
2754 }
2755 
2756 void JavaThread::disable_stack_reserved_zone() {
2757   assert(_stack_guard_state == stack_guard_enabled, "inconsistent state");
2758 
2759   // Simply return if called for a thread that does not use guard pages.
2760   if (_stack_guard_state != stack_guard_enabled) return;
2761 
2762   // The base notation is from the stack's point of view, growing downward.
2763   // We need to adjust it to work correctly with guard_memory()
2764   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2765 
2766   if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2767     _stack_guard_state = stack_guard_reserved_disabled;
2768   } else {
2769     warning("Attempt to unguard stack reserved zone failed.");
2770   }
2771   disable_register_stack_guard();
2772 }
2773 
2774 void JavaThread::enable_stack_yellow_reserved_zone() {
2775   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2776   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2777 
2778   // The base notation is from the stacks point of view, growing downward.
2779   // We need to adjust it to work correctly with guard_memory()
2780   address base = stack_red_zone_base();
2781 
2782   guarantee(base < stack_base(), "Error calculating stack yellow zone");
2783   guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2784 
2785   if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2786     _stack_guard_state = stack_guard_enabled;
2787   } else {
2788     warning("Attempt to guard stack yellow zone failed.");
2789   }
2790   enable_register_stack_guard();
2791 }
2792 
2793 void JavaThread::disable_stack_yellow_reserved_zone() {
2794   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2795   assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2796 
2797   // Simply return if called for a thread that does not use guard pages.
2798   if (_stack_guard_state == stack_guard_unused) return;
2799 
2800   // The base notation is from the stacks point of view, growing downward.
2801   // We need to adjust it to work correctly with guard_memory()
2802   address base = stack_red_zone_base();
2803 
2804   if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2805     _stack_guard_state = stack_guard_yellow_reserved_disabled;
2806   } else {
2807     warning("Attempt to unguard stack yellow zone failed.");
2808   }
2809   disable_register_stack_guard();
2810 }
2811 
2812 void JavaThread::enable_stack_red_zone() {
2813   // The base notation is from the stacks point of view, growing downward.
2814   // We need to adjust it to work correctly with guard_memory()
2815   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2816   address base = stack_red_zone_base() - stack_red_zone_size();
2817 
2818   guarantee(base < stack_base(), "Error calculating stack red zone");
2819   guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2820 
2821   if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2822     warning("Attempt to guard stack red zone failed.");
2823   }
2824 }
2825 
2826 void JavaThread::disable_stack_red_zone() {
2827   // The base notation is from the stacks point of view, growing downward.
2828   // We need to adjust it to work correctly with guard_memory()
2829   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2830   address base = stack_red_zone_base() - stack_red_zone_size();
2831   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2832     warning("Attempt to unguard stack red zone failed.");
2833   }
2834 }
2835 
2836 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2837   // ignore is there is no stack
2838   if (!has_last_Java_frame()) return;
2839   // traverse the stack frames. Starts from top frame.
2840   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2841     frame* fr = fst.current();
2842     f(fr, fst.register_map());
2843   }
2844 }
2845 
2846 
2847 #ifndef PRODUCT
2848 // Deoptimization
2849 // Function for testing deoptimization
2850 void JavaThread::deoptimize() {
2851   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2852   StackFrameStream fst(this, UseBiasedLocking);
2853   bool deopt = false;           // Dump stack only if a deopt actually happens.
2854   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2855   // Iterate over all frames in the thread and deoptimize
2856   for (; !fst.is_done(); fst.next()) {
2857     if (fst.current()->can_be_deoptimized()) {
2858 
2859       if (only_at) {
2860         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
2861         // consists of comma or carriage return separated numbers so
2862         // search for the current bci in that string.
2863         address pc = fst.current()->pc();
2864         nmethod* nm =  (nmethod*) fst.current()->cb();
2865         ScopeDesc* sd = nm->scope_desc_at(pc);
2866         char buffer[8];
2867         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2868         size_t len = strlen(buffer);
2869         const char * found = strstr(DeoptimizeOnlyAt, buffer);
2870         while (found != NULL) {
2871           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2872               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2873             // Check that the bci found is bracketed by terminators.
2874             break;
2875           }
2876           found = strstr(found + 1, buffer);
2877         }
2878         if (!found) {
2879           continue;
2880         }
2881       }
2882 
2883       if (DebugDeoptimization && !deopt) {
2884         deopt = true; // One-time only print before deopt
2885         tty->print_cr("[BEFORE Deoptimization]");
2886         trace_frames();
2887         trace_stack();
2888       }
2889       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2890     }
2891   }
2892 
2893   if (DebugDeoptimization && deopt) {
2894     tty->print_cr("[AFTER Deoptimization]");
2895     trace_frames();
2896   }
2897 }
2898 
2899 
2900 // Make zombies
2901 void JavaThread::make_zombies() {
2902   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2903     if (fst.current()->can_be_deoptimized()) {
2904       // it is a Java nmethod
2905       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2906       nm->make_not_entrant();
2907     }
2908   }
2909 }
2910 #endif // PRODUCT
2911 
2912 
2913 void JavaThread::deoptimized_wrt_marked_nmethods() {
2914   if (!has_last_Java_frame()) return;
2915   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2916   StackFrameStream fst(this, UseBiasedLocking);
2917   for (; !fst.is_done(); fst.next()) {
2918     if (fst.current()->should_be_deoptimized()) {
2919       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2920     }
2921   }
2922 }
2923 
2924 
2925 // If the caller is a NamedThread, then remember, in the current scope,
2926 // the given JavaThread in its _processed_thread field.
2927 class RememberProcessedThread: public StackObj {
2928   NamedThread* _cur_thr;
2929  public:
2930   RememberProcessedThread(JavaThread* jthr) {
2931     Thread* thread = Thread::current();
2932     if (thread->is_Named_thread()) {
2933       _cur_thr = (NamedThread *)thread;
2934       _cur_thr->set_processed_thread(jthr);
2935     } else {
2936       _cur_thr = NULL;
2937     }
2938   }
2939 
2940   ~RememberProcessedThread() {
2941     if (_cur_thr) {
2942       _cur_thr->set_processed_thread(NULL);
2943     }
2944   }
2945 };
2946 
2947 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2948   // Verify that the deferred card marks have been flushed.
2949   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2950 
2951   // Traverse the GCHandles
2952   Thread::oops_do(f, cf);
2953 
2954   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2955          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2956 
2957   if (has_last_Java_frame()) {
2958     // Record JavaThread to GC thread
2959     RememberProcessedThread rpt(this);
2960 
2961     // traverse the registered growable array
2962     if (_array_for_gc != NULL) {
2963       for (int index = 0; index < _array_for_gc->length(); index++) {
2964         f->do_oop(_array_for_gc->adr_at(index));
2965       }
2966     }
2967 
2968     // Traverse the monitor chunks
2969     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2970       chunk->oops_do(f);
2971     }
2972 
2973     // Traverse the execution stack
2974     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2975       fst.current()->oops_do(f, cf, fst.register_map());
2976     }
2977   }
2978 
2979   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2980   // If we have deferred set_locals there might be oops waiting to be
2981   // written
2982   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2983   if (list != NULL) {
2984     for (int i = 0; i < list->length(); i++) {
2985       list->at(i)->oops_do(f);
2986     }
2987   }
2988 
2989   // Traverse instance variables at the end since the GC may be moving things
2990   // around using this function
2991   f->do_oop((oop*) &_threadObj);
2992   f->do_oop((oop*) &_vm_result);
2993   f->do_oop((oop*) &_exception_oop);
2994   f->do_oop((oop*) &_pending_async_exception);
2995 
2996   if (jvmti_thread_state() != NULL) {
2997     jvmti_thread_state()->oops_do(f);
2998   }
2999 }
3000 
3001 #ifdef ASSERT
3002 void JavaThread::verify_states_for_handshake() {
3003   // This checks that the thread has a correct frame state during a handshake.
3004   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
3005          (has_last_Java_frame() && java_call_counter() > 0),
3006          "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
3007          has_last_Java_frame(), java_call_counter());
3008 }
3009 #endif
3010 
3011 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
3012   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
3013          (has_last_Java_frame() && java_call_counter() > 0),
3014          "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
3015          has_last_Java_frame(), java_call_counter());
3016 
3017   if (has_last_Java_frame()) {
3018     // Traverse the execution stack
3019     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3020       fst.current()->nmethods_do(cf);
3021     }
3022   }
3023 }
3024 
3025 void JavaThread::metadata_do(MetadataClosure* f) {
3026   if (has_last_Java_frame()) {
3027     // Traverse the execution stack to call f() on the methods in the stack
3028     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3029       fst.current()->metadata_do(f);
3030     }
3031   } else if (is_Compiler_thread()) {
3032     // need to walk ciMetadata in current compile tasks to keep alive.
3033     CompilerThread* ct = (CompilerThread*)this;
3034     if (ct->env() != NULL) {
3035       ct->env()->metadata_do(f);
3036     }
3037     CompileTask* task = ct->task();
3038     if (task != NULL) {
3039       task->metadata_do(f);
3040     }
3041   }
3042 }
3043 
3044 // Printing
3045 const char* _get_thread_state_name(JavaThreadState _thread_state) {
3046   switch (_thread_state) {
3047   case _thread_uninitialized:     return "_thread_uninitialized";
3048   case _thread_new:               return "_thread_new";
3049   case _thread_new_trans:         return "_thread_new_trans";
3050   case _thread_in_native:         return "_thread_in_native";
3051   case _thread_in_native_trans:   return "_thread_in_native_trans";
3052   case _thread_in_vm:             return "_thread_in_vm";
3053   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
3054   case _thread_in_Java:           return "_thread_in_Java";
3055   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
3056   case _thread_blocked:           return "_thread_blocked";
3057   case _thread_blocked_trans:     return "_thread_blocked_trans";
3058   default:                        return "unknown thread state";
3059   }
3060 }
3061 
3062 #ifndef PRODUCT
3063 void JavaThread::print_thread_state_on(outputStream *st) const {
3064   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
3065 };
3066 void JavaThread::print_thread_state() const {
3067   print_thread_state_on(tty);
3068 }
3069 const char* JavaThread::thread_state_name() const {
3070   return _get_thread_state_name(_thread_state);
3071 }
3072 #endif // PRODUCT
3073 
3074 // Called by Threads::print() for VM_PrintThreads operation
3075 void JavaThread::print_on(outputStream *st, bool print_extended_info) const {
3076   st->print_raw("\"");
3077   st->print_raw(get_thread_name());
3078   st->print_raw("\" ");
3079   oop thread_oop = threadObj();
3080   if (thread_oop != NULL) {
3081     st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
3082     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
3083     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
3084   }
3085   Thread::print_on(st, print_extended_info);
3086   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
3087   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
3088   if (thread_oop != NULL) {
3089     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
3090   }
3091 #ifndef PRODUCT
3092   _safepoint_state->print_on(st);
3093 #endif // PRODUCT
3094   if (is_Compiler_thread()) {
3095     CompileTask *task = ((CompilerThread*)this)->task();
3096     if (task != NULL) {
3097       st->print("   Compiling: ");
3098       task->print(st, NULL, true, false);
3099     } else {
3100       st->print("   No compile task");
3101     }
3102     st->cr();
3103   }
3104 }
3105 
3106 void JavaThread::print() const { print_on(tty); }
3107 
3108 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
3109   st->print("%s", get_thread_name_string(buf, buflen));
3110 }
3111 
3112 // Called by fatal error handler. The difference between this and
3113 // JavaThread::print() is that we can't grab lock or allocate memory.
3114 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
3115   st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
3116   oop thread_obj = threadObj();
3117   if (thread_obj != NULL) {
3118     if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
3119   }
3120   st->print(" [");
3121   st->print("%s", _get_thread_state_name(_thread_state));
3122   if (osthread()) {
3123     st->print(", id=%d", osthread()->thread_id());
3124   }
3125   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
3126             p2i(stack_end()), p2i(stack_base()));
3127   st->print("]");
3128 
3129   ThreadsSMRSupport::print_info_on(this, st);
3130   return;
3131 }
3132 
3133 // Verification
3134 
3135 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3136 
3137 void JavaThread::verify() {
3138   // Verify oops in the thread.
3139   oops_do(&VerifyOopClosure::verify_oop, NULL);
3140 
3141   // Verify the stack frames.
3142   frames_do(frame_verify);
3143 }
3144 
3145 // CR 6300358 (sub-CR 2137150)
3146 // Most callers of this method assume that it can't return NULL but a
3147 // thread may not have a name whilst it is in the process of attaching to
3148 // the VM - see CR 6412693, and there are places where a JavaThread can be
3149 // seen prior to having it's threadObj set (eg JNI attaching threads and
3150 // if vm exit occurs during initialization). These cases can all be accounted
3151 // for such that this method never returns NULL.
3152 const char* JavaThread::get_thread_name() const {
3153 #ifdef ASSERT
3154   // early safepoints can hit while current thread does not yet have TLS
3155   if (!SafepointSynchronize::is_at_safepoint()) {
3156     Thread *cur = Thread::current();
3157     if (!(cur->is_Java_thread() && cur == this)) {
3158       // Current JavaThreads are allowed to get their own name without
3159       // the Threads_lock.
3160       assert_locked_or_safepoint(Threads_lock);
3161     }
3162   }
3163 #endif // ASSERT
3164   return get_thread_name_string();
3165 }
3166 
3167 // Returns a non-NULL representation of this thread's name, or a suitable
3168 // descriptive string if there is no set name
3169 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3170   const char* name_str;
3171   oop thread_obj = threadObj();
3172   if (thread_obj != NULL) {
3173     oop name = java_lang_Thread::name(thread_obj);
3174     if (name != NULL) {
3175       if (buf == NULL) {
3176         name_str = java_lang_String::as_utf8_string(name);
3177       } else {
3178         name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3179       }
3180     } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3181       name_str = "<no-name - thread is attaching>";
3182     } else {
3183       name_str = Thread::name();
3184     }
3185   } else {
3186     name_str = Thread::name();
3187   }
3188   assert(name_str != NULL, "unexpected NULL thread name");
3189   return name_str;
3190 }
3191 
3192 
3193 const char* JavaThread::get_threadgroup_name() const {
3194   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3195   oop thread_obj = threadObj();
3196   if (thread_obj != NULL) {
3197     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3198     if (thread_group != NULL) {
3199       // ThreadGroup.name can be null
3200       return java_lang_ThreadGroup::name(thread_group);
3201     }
3202   }
3203   return NULL;
3204 }
3205 
3206 const char* JavaThread::get_parent_name() const {
3207   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3208   oop thread_obj = threadObj();
3209   if (thread_obj != NULL) {
3210     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3211     if (thread_group != NULL) {
3212       oop parent = java_lang_ThreadGroup::parent(thread_group);
3213       if (parent != NULL) {
3214         // ThreadGroup.name can be null
3215         return java_lang_ThreadGroup::name(parent);
3216       }
3217     }
3218   }
3219   return NULL;
3220 }
3221 
3222 ThreadPriority JavaThread::java_priority() const {
3223   oop thr_oop = threadObj();
3224   if (thr_oop == NULL) return NormPriority; // Bootstrapping
3225   ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3226   assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3227   return priority;
3228 }
3229 
3230 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3231 
3232   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3233   // Link Java Thread object <-> C++ Thread
3234 
3235   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3236   // and put it into a new Handle.  The Handle "thread_oop" can then
3237   // be used to pass the C++ thread object to other methods.
3238 
3239   // Set the Java level thread object (jthread) field of the
3240   // new thread (a JavaThread *) to C++ thread object using the
3241   // "thread_oop" handle.
3242 
3243   // Set the thread field (a JavaThread *) of the
3244   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3245 
3246   Handle thread_oop(Thread::current(),
3247                     JNIHandles::resolve_non_null(jni_thread));
3248   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3249          "must be initialized");
3250   set_threadObj(thread_oop());
3251   java_lang_Thread::set_thread(thread_oop(), this);
3252 
3253   if (prio == NoPriority) {
3254     prio = java_lang_Thread::priority(thread_oop());
3255     assert(prio != NoPriority, "A valid priority should be present");
3256   }
3257 
3258   // Push the Java priority down to the native thread; needs Threads_lock
3259   Thread::set_priority(this, prio);
3260 
3261   // Add the new thread to the Threads list and set it in motion.
3262   // We must have threads lock in order to call Threads::add.
3263   // It is crucial that we do not block before the thread is
3264   // added to the Threads list for if a GC happens, then the java_thread oop
3265   // will not be visited by GC.
3266   Threads::add(this);
3267 }
3268 
3269 oop JavaThread::current_park_blocker() {
3270   // Support for JSR-166 locks
3271   oop thread_oop = threadObj();
3272   if (thread_oop != NULL) {
3273     return java_lang_Thread::park_blocker(thread_oop);
3274   }
3275   return NULL;
3276 }
3277 
3278 
3279 void JavaThread::print_stack_on(outputStream* st) {
3280   if (!has_last_Java_frame()) return;
3281   ResourceMark rm;
3282   HandleMark   hm;
3283 
3284   RegisterMap reg_map(this);
3285   vframe* start_vf = last_java_vframe(&reg_map);
3286   int count = 0;
3287   for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3288     if (f->is_java_frame()) {
3289       javaVFrame* jvf = javaVFrame::cast(f);
3290       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3291 
3292       // Print out lock information
3293       if (JavaMonitorsInStackTrace) {
3294         jvf->print_lock_info_on(st, count);
3295       }
3296     } else {
3297       // Ignore non-Java frames
3298     }
3299 
3300     // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3301     count++;
3302     if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3303   }
3304 }
3305 
3306 
3307 // JVMTI PopFrame support
3308 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3309   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3310   if (in_bytes(size_in_bytes) != 0) {
3311     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3312     _popframe_preserved_args_size = in_bytes(size_in_bytes);
3313     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3314   }
3315 }
3316 
3317 void* JavaThread::popframe_preserved_args() {
3318   return _popframe_preserved_args;
3319 }
3320 
3321 ByteSize JavaThread::popframe_preserved_args_size() {
3322   return in_ByteSize(_popframe_preserved_args_size);
3323 }
3324 
3325 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3326   int sz = in_bytes(popframe_preserved_args_size());
3327   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3328   return in_WordSize(sz / wordSize);
3329 }
3330 
3331 void JavaThread::popframe_free_preserved_args() {
3332   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3333   FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3334   _popframe_preserved_args = NULL;
3335   _popframe_preserved_args_size = 0;
3336 }
3337 
3338 #ifndef PRODUCT
3339 
3340 void JavaThread::trace_frames() {
3341   tty->print_cr("[Describe stack]");
3342   int frame_no = 1;
3343   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3344     tty->print("  %d. ", frame_no++);
3345     fst.current()->print_value_on(tty, this);
3346     tty->cr();
3347   }
3348 }
3349 
3350 class PrintAndVerifyOopClosure: public OopClosure {
3351  protected:
3352   template <class T> inline void do_oop_work(T* p) {
3353     oop obj = RawAccess<>::oop_load(p);
3354     if (obj == NULL) return;
3355     tty->print(INTPTR_FORMAT ": ", p2i(p));
3356     if (oopDesc::is_oop_or_null(obj)) {
3357       if (obj->is_objArray()) {
3358         tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3359       } else {
3360         obj->print();
3361       }
3362     } else {
3363       tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3364     }
3365     tty->cr();
3366   }
3367  public:
3368   virtual void do_oop(oop* p) { do_oop_work(p); }
3369   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
3370 };
3371 
3372 
3373 static void oops_print(frame* f, const RegisterMap *map) {
3374   PrintAndVerifyOopClosure print;
3375   f->print_value();
3376   f->oops_do(&print, NULL, (RegisterMap*)map);
3377 }
3378 
3379 // Print our all the locations that contain oops and whether they are
3380 // valid or not.  This useful when trying to find the oldest frame
3381 // where an oop has gone bad since the frame walk is from youngest to
3382 // oldest.
3383 void JavaThread::trace_oops() {
3384   tty->print_cr("[Trace oops]");
3385   frames_do(oops_print);
3386 }
3387 
3388 
3389 #ifdef ASSERT
3390 // Print or validate the layout of stack frames
3391 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3392   ResourceMark rm;
3393   PRESERVE_EXCEPTION_MARK;
3394   FrameValues values;
3395   int frame_no = 0;
3396   for (StackFrameStream fst(this, false, true); !fst.is_done(); fst.next()) {
3397     fst.current()->describe(values, ++frame_no, fst.register_map());
3398     if (depth == frame_no) break;
3399   }
3400   Continuation::describe(values);
3401   if (validate_only) {
3402     values.validate();
3403   } else {
3404     tty->print_cr("[Describe stack layout]");
3405     values.print(this);
3406   }
3407 }
3408 #endif
3409 
3410 void JavaThread::trace_stack_from(vframe* start_vf) {
3411   ResourceMark rm;
3412   int vframe_no = 1;
3413   for (vframe* f = start_vf; f; f = f->sender()) {
3414     if (f->is_java_frame()) {
3415       javaVFrame::cast(f)->print_activation(vframe_no++);
3416     } else {
3417       f->print();
3418     }
3419     if (vframe_no > StackPrintLimit) {
3420       tty->print_cr("...<more frames>...");
3421       return;
3422     }
3423   }
3424 }
3425 
3426 
3427 void JavaThread::trace_stack() {
3428   if (!has_last_Java_frame()) return;
3429   ResourceMark rm;
3430   HandleMark   hm;
3431   RegisterMap reg_map(this, true, true);
3432   trace_stack_from(last_java_vframe(&reg_map));
3433 }
3434 
3435 
3436 #endif // PRODUCT
3437 
3438 
3439 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3440   assert(reg_map != NULL, "a map must be given");
3441   frame f = last_frame();
3442   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3443     if (vf->is_java_frame()) return javaVFrame::cast(vf);
3444   }
3445   return NULL;
3446 }
3447 
3448 oop JavaThread::last_continuation() {
3449   if (threadObj() == (oop)NULL) return (oop)NULL; // happens during initialization
3450   
3451   return java_lang_Thread::continuation(threadObj());
3452 }
3453 
3454 Klass* JavaThread::security_get_caller_class(int depth) {
3455   vframeStream vfst(this);
3456   vfst.security_get_caller_frame(depth);
3457   if (!vfst.at_end()) {
3458     return vfst.method()->method_holder();
3459   }
3460   return NULL;
3461 }
3462 
3463 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3464   assert(thread->is_Compiler_thread(), "must be compiler thread");
3465   CompileBroker::compiler_thread_loop();
3466 }
3467 
3468 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3469   NMethodSweeper::sweeper_loop();
3470 }
3471 
3472 // Create a CompilerThread
3473 CompilerThread::CompilerThread(CompileQueue* queue,
3474                                CompilerCounters* counters)
3475                                : JavaThread(&compiler_thread_entry) {
3476   _env   = NULL;
3477   _log   = NULL;
3478   _task  = NULL;
3479   _queue = queue;
3480   _counters = counters;
3481   _buffer_blob = NULL;
3482   _compiler = NULL;
3483 
3484   // Compiler uses resource area for compilation, let's bias it to mtCompiler
3485   resource_area()->bias_to(mtCompiler);
3486 
3487 #ifndef PRODUCT
3488   _ideal_graph_printer = NULL;
3489 #endif
3490 }
3491 
3492 CompilerThread::~CompilerThread() {
3493   // Delete objects which were allocated on heap.
3494   delete _counters;
3495 }
3496 
3497 bool CompilerThread::can_call_java() const {
3498   return _compiler != NULL && _compiler->is_jvmci();
3499 }
3500 
3501 // Create sweeper thread
3502 CodeCacheSweeperThread::CodeCacheSweeperThread()
3503 : JavaThread(&sweeper_thread_entry) {
3504   _scanned_compiled_method = NULL;
3505 }
3506 
3507 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3508   JavaThread::oops_do(f, cf);
3509   if (_scanned_compiled_method != NULL && cf != NULL) {
3510     // Safepoints can occur when the sweeper is scanning an nmethod so
3511     // process it here to make sure it isn't unloaded in the middle of
3512     // a scan.
3513     cf->do_code_blob(_scanned_compiled_method);
3514   }
3515 }
3516 
3517 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3518   JavaThread::nmethods_do(cf);
3519   if (_scanned_compiled_method != NULL && cf != NULL) {
3520     // Safepoints can occur when the sweeper is scanning an nmethod so
3521     // process it here to make sure it isn't unloaded in the middle of
3522     // a scan.
3523     cf->do_code_blob(_scanned_compiled_method);
3524   }
3525 }
3526 
3527 
3528 // ======= Threads ========
3529 
3530 // The Threads class links together all active threads, and provides
3531 // operations over all threads. It is protected by the Threads_lock,
3532 // which is also used in other global contexts like safepointing.
3533 // ThreadsListHandles are used to safely perform operations on one
3534 // or more threads without the risk of the thread exiting during the
3535 // operation.
3536 //
3537 // Note: The Threads_lock is currently more widely used than we
3538 // would like. We are actively migrating Threads_lock uses to other
3539 // mechanisms in order to reduce Threads_lock contention.
3540 
3541 int         Threads::_number_of_threads = 0;
3542 int         Threads::_number_of_non_daemon_threads = 0;
3543 int         Threads::_return_code = 0;
3544 uintx       Threads::_thread_claim_token = 1; // Never zero.
3545 size_t      JavaThread::_stack_size_at_create = 0;
3546 
3547 #ifdef ASSERT
3548 bool        Threads::_vm_complete = false;
3549 #endif
3550 
3551 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3552   Prefetch::read((void*)addr, prefetch_interval);
3553   return *addr;
3554 }
3555 
3556 // Possibly the ugliest for loop the world has seen. C++ does not allow
3557 // multiple types in the declaration section of the for loop. In this case
3558 // we are only dealing with pointers and hence can cast them. It looks ugly
3559 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3560 #define DO_JAVA_THREADS(LIST, X)                                                                                          \
3561     for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes,                           \
3562              *MACRO_list = (JavaThread*)(LIST),                                                                           \
3563              **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(),  \
3564              **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(),                                     \
3565              *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval);                 \
3566          MACRO_current_p != MACRO_end;                                                                                    \
3567          MACRO_current_p++,                                                                                               \
3568              X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3569 
3570 // All JavaThreads
3571 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3572 
3573 // All NonJavaThreads (i.e., every non-JavaThread in the system).
3574 void Threads::non_java_threads_do(ThreadClosure* tc) {
3575   NoSafepointVerifier nsv;
3576   for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) {
3577     tc->do_thread(njti.current());
3578   }
3579 }
3580 
3581 // All JavaThreads
3582 void Threads::java_threads_do(ThreadClosure* tc) {
3583   assert_locked_or_safepoint(Threads_lock);
3584   // ALL_JAVA_THREADS iterates through all JavaThreads.
3585   ALL_JAVA_THREADS(p) {
3586     tc->do_thread(p);
3587   }
3588 }
3589 
3590 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) {
3591   assert_locked_or_safepoint(Threads_lock);
3592   java_threads_do(tc);
3593   tc->do_thread(VMThread::vm_thread());
3594 }
3595 
3596 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
3597 void Threads::threads_do(ThreadClosure* tc) {
3598   assert_locked_or_safepoint(Threads_lock);
3599   java_threads_do(tc);
3600   non_java_threads_do(tc);
3601 }
3602 
3603 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3604   uintx claim_token = Threads::thread_claim_token();
3605   ALL_JAVA_THREADS(p) {
3606     if (p->claim_threads_do(is_par, claim_token)) {
3607       tc->do_thread(p);
3608     }
3609   }
3610   VMThread* vmt = VMThread::vm_thread();
3611   if (vmt->claim_threads_do(is_par, claim_token)) {
3612     tc->do_thread(vmt);
3613   }
3614 }
3615 
3616 // The system initialization in the library has three phases.
3617 //
3618 // Phase 1: java.lang.System class initialization
3619 //     java.lang.System is a primordial class loaded and initialized
3620 //     by the VM early during startup.  java.lang.System.<clinit>
3621 //     only does registerNatives and keeps the rest of the class
3622 //     initialization work later until thread initialization completes.
3623 //
3624 //     System.initPhase1 initializes the system properties, the static
3625 //     fields in, out, and err. Set up java signal handlers, OS-specific
3626 //     system settings, and thread group of the main thread.
3627 static void call_initPhase1(TRAPS) {
3628   Klass* klass =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3629   JavaValue result(T_VOID);
3630   JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3631                                          vmSymbols::void_method_signature(), CHECK);
3632 }
3633 
3634 // Phase 2. Module system initialization
3635 //     This will initialize the module system.  Only java.base classes
3636 //     can be loaded until phase 2 completes.
3637 //
3638 //     Call System.initPhase2 after the compiler initialization and jsr292
3639 //     classes get initialized because module initialization runs a lot of java
3640 //     code, that for performance reasons, should be compiled.  Also, this will
3641 //     enable the startup code to use lambda and other language features in this
3642 //     phase and onward.
3643 //
3644 //     After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3645 static void call_initPhase2(TRAPS) {
3646   TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3647 
3648   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3649 
3650   JavaValue result(T_INT);
3651   JavaCallArguments args;
3652   args.push_int(DisplayVMOutputToStderr);
3653   args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3654   JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3655                                          vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3656   if (result.get_jint() != JNI_OK) {
3657     vm_exit_during_initialization(); // no message or exception
3658   }
3659 
3660   universe_post_module_init();
3661 }
3662 
3663 // Phase 3. final setup - set security manager, system class loader and TCCL
3664 //
3665 //     This will instantiate and set the security manager, set the system class
3666 //     loader as well as the thread context class loader.  The security manager
3667 //     and system class loader may be a custom class loaded from -Xbootclasspath/a,
3668 //     other modules or the application's classpath.
3669 static void call_initPhase3(TRAPS) {
3670   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3671   JavaValue result(T_VOID);
3672   JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3673                                          vmSymbols::void_method_signature(), CHECK);
3674 }
3675 
3676 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3677   TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3678 
3679   if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3680     create_vm_init_libraries();
3681   }
3682 
3683   initialize_class(vmSymbols::java_lang_String(), CHECK);
3684 
3685   // Inject CompactStrings value after the static initializers for String ran.
3686   java_lang_String::set_compact_strings(CompactStrings);
3687 
3688   // Initialize java_lang.System (needed before creating the thread)
3689   initialize_class(vmSymbols::java_lang_System(), CHECK);
3690   // The VM creates & returns objects of this class. Make sure it's initialized.
3691   initialize_class(vmSymbols::java_lang_Class(), CHECK);
3692   initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3693   Handle thread_group = create_initial_thread_group(CHECK);
3694   Universe::set_main_thread_group(thread_group());
3695   initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3696   oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3697   main_thread->set_threadObj(thread_object);
3698 
3699   // Set thread status to running since main thread has
3700   // been started and running.
3701   java_lang_Thread::set_thread_status(thread_object,
3702                                       java_lang_Thread::RUNNABLE);
3703 
3704   // The VM creates objects of this class.
3705   initialize_class(vmSymbols::java_lang_Module(), CHECK);
3706 
3707 #ifdef ASSERT
3708   InstanceKlass *k = SystemDictionary::UnsafeConstants_klass();
3709   assert(k->is_not_initialized(), "UnsafeConstants should not already be initialized");
3710 #endif
3711 
3712   // initialize the hardware-specific constants needed by Unsafe
3713   initialize_class(vmSymbols::jdk_internal_misc_UnsafeConstants(), CHECK);
3714   jdk_internal_misc_UnsafeConstants::set_unsafe_constants();
3715 
3716   // The VM preresolves methods to these classes. Make sure that they get initialized
3717   initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3718   initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3719 
3720   // Phase 1 of the system initialization in the library, java.lang.System class initialization
3721   call_initPhase1(CHECK);
3722 
3723   // get the Java runtime name after java.lang.System is initialized
3724   JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3725   JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3726 
3727   // an instance of OutOfMemory exception has been allocated earlier
3728   initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3729   initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3730   initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3731   initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3732   initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3733   initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3734   initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3735   initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3736 
3737   // Eager box cache initialization only if AOT is on and any library is loaded.
3738   AOTLoader::initialize_box_caches(CHECK);
3739 }
3740 
3741 void Threads::initialize_jsr292_core_classes(TRAPS) {
3742   TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3743 
3744   initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3745   initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3746   initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3747   initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3748 }
3749 
3750 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3751   extern void JDK_Version_init();
3752 
3753   // Preinitialize version info.
3754   VM_Version::early_initialize();
3755 
3756   // Check version
3757   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3758 
3759   // Initialize library-based TLS
3760   ThreadLocalStorage::init();
3761 
3762   // Initialize the output stream module
3763   ostream_init();
3764 
3765   // Process java launcher properties.
3766   Arguments::process_sun_java_launcher_properties(args);
3767 
3768   // Initialize the os module
3769   os::init();
3770 
3771   // Record VM creation timing statistics
3772   TraceVmCreationTime create_vm_timer;
3773   create_vm_timer.start();
3774 
3775   // Initialize system properties.
3776   Arguments::init_system_properties();
3777 
3778   // So that JDK version can be used as a discriminator when parsing arguments
3779   JDK_Version_init();
3780 
3781   // Update/Initialize System properties after JDK version number is known
3782   Arguments::init_version_specific_system_properties();
3783 
3784   // Make sure to initialize log configuration *before* parsing arguments
3785   LogConfiguration::initialize(create_vm_timer.begin_time());
3786 
3787   // Parse arguments
3788   // Note: this internally calls os::init_container_support()
3789   jint parse_result = Arguments::parse(args);
3790   if (parse_result != JNI_OK) return parse_result;
3791 
3792   os::init_before_ergo();
3793 
3794   jint ergo_result = Arguments::apply_ergo();
3795   if (ergo_result != JNI_OK) return ergo_result;
3796 
3797   // Final check of all ranges after ergonomics which may change values.
3798   if (!JVMFlagRangeList::check_ranges()) {
3799     return JNI_EINVAL;
3800   }
3801 
3802   // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3803   bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo);
3804   if (!constraint_result) {
3805     return JNI_EINVAL;
3806   }
3807 
3808   JVMFlagWriteableList::mark_startup();
3809 
3810   if (PauseAtStartup) {
3811     os::pause();
3812   }
3813 
3814   HOTSPOT_VM_INIT_BEGIN();
3815 
3816   // Timing (must come after argument parsing)
3817   TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3818 
3819   // Initialize the os module after parsing the args
3820   jint os_init_2_result = os::init_2();
3821   if (os_init_2_result != JNI_OK) return os_init_2_result;
3822 
3823 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
3824   // Initialize assert poison page mechanism.
3825   if (ShowRegistersOnAssert) {
3826     initialize_assert_poison();
3827   }
3828 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
3829 
3830   SafepointMechanism::initialize();
3831 
3832   jint adjust_after_os_result = Arguments::adjust_after_os();
3833   if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3834 
3835   // Initialize output stream logging
3836   ostream_init_log();
3837 
3838   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3839   // Must be before create_vm_init_agents()
3840   if (Arguments::init_libraries_at_startup()) {
3841     convert_vm_init_libraries_to_agents();
3842   }
3843 
3844   // Launch -agentlib/-agentpath and converted -Xrun agents
3845   if (Arguments::init_agents_at_startup()) {
3846     create_vm_init_agents();
3847   }
3848 
3849   // Initialize Threads state
3850   _number_of_threads = 0;
3851   _number_of_non_daemon_threads = 0;
3852 
3853   // Initialize global data structures and create system classes in heap
3854   vm_init_globals();
3855 
3856 #if INCLUDE_JVMCI
3857   if (JVMCICounterSize > 0) {
3858     JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtJVMCI);
3859     memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3860   } else {
3861     JavaThread::_jvmci_old_thread_counters = NULL;
3862   }
3863 #endif // INCLUDE_JVMCI
3864 
3865   // Attach the main thread to this os thread
3866   JavaThread* main_thread = new JavaThread();
3867   main_thread->set_thread_state(_thread_in_vm);
3868   main_thread->initialize_thread_current();
3869   // must do this before set_active_handles
3870   main_thread->record_stack_base_and_size();
3871   main_thread->register_thread_stack_with_NMT();
3872   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3873 
3874   if (!main_thread->set_as_starting_thread()) {
3875     vm_shutdown_during_initialization(
3876                                       "Failed necessary internal allocation. Out of swap space");
3877     main_thread->smr_delete();
3878     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3879     return JNI_ENOMEM;
3880   }
3881 
3882   // Enable guard page *after* os::create_main_thread(), otherwise it would
3883   // crash Linux VM, see notes in os_linux.cpp.
3884   main_thread->create_stack_guard_pages();
3885 
3886   // Initialize Java-Level synchronization subsystem
3887   ObjectMonitor::Initialize();
3888 
3889   // Initialize global modules
3890   jint status = init_globals();
3891   if (status != JNI_OK) {
3892     main_thread->smr_delete();
3893     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3894     return status;
3895   }
3896 
3897   JFR_ONLY(Jfr::on_vm_init();)
3898 
3899   // Should be done after the heap is fully created
3900   main_thread->cache_global_variables();
3901 
3902   HandleMark hm;
3903 
3904   { MutexLocker mu(Threads_lock);
3905     Threads::add(main_thread);
3906   }
3907 
3908   // Any JVMTI raw monitors entered in onload will transition into
3909   // real raw monitor. VM is setup enough here for raw monitor enter.
3910   JvmtiExport::transition_pending_onload_raw_monitors();
3911 
3912   // Create the VMThread
3913   { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3914 
3915   VMThread::create();
3916     Thread* vmthread = VMThread::vm_thread();
3917 
3918     if (!os::create_thread(vmthread, os::vm_thread)) {
3919       vm_exit_during_initialization("Cannot create VM thread. "
3920                                     "Out of system resources.");
3921     }
3922 
3923     // Wait for the VM thread to become ready, and VMThread::run to initialize
3924     // Monitors can have spurious returns, must always check another state flag
3925     {
3926       MonitorLocker ml(Notify_lock);
3927       os::start_thread(vmthread);
3928       while (vmthread->active_handles() == NULL) {
3929         ml.wait();
3930       }
3931     }
3932   }
3933 
3934   assert(Universe::is_fully_initialized(), "not initialized");
3935   if (VerifyDuringStartup) {
3936     // Make sure we're starting with a clean slate.
3937     VM_Verify verify_op;
3938     VMThread::execute(&verify_op);
3939   }
3940 
3941   // We need this to update the java.vm.info property in case any flags used
3942   // to initially define it have been changed. This is needed for both CDS and
3943   // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info
3944   // is initially computed. See Abstract_VM_Version::vm_info_string().
3945   // This update must happen before we initialize the java classes, but
3946   // after any initialization logic that might modify the flags.
3947   Arguments::update_vm_info_property(VM_Version::vm_info_string());
3948 
3949   Thread* THREAD = Thread::current();
3950 
3951   // Always call even when there are not JVMTI environments yet, since environments
3952   // may be attached late and JVMTI must track phases of VM execution
3953   JvmtiExport::enter_early_start_phase();
3954 
3955   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3956   JvmtiExport::post_early_vm_start();
3957 
3958   initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3959 
3960   quicken_jni_functions();
3961 
3962   // No more stub generation allowed after that point.
3963   StubCodeDesc::freeze();
3964 
3965   // Set flag that basic initialization has completed. Used by exceptions and various
3966   // debug stuff, that does not work until all basic classes have been initialized.
3967   set_init_completed();
3968 
3969   LogConfiguration::post_initialize();
3970   Metaspace::post_initialize();
3971 
3972   HOTSPOT_VM_INIT_END();
3973 
3974   // record VM initialization completion time
3975 #if INCLUDE_MANAGEMENT
3976   Management::record_vm_init_completed();
3977 #endif // INCLUDE_MANAGEMENT
3978 
3979   // Signal Dispatcher needs to be started before VMInit event is posted
3980   os::initialize_jdk_signal_support(CHECK_JNI_ERR);
3981 
3982   // Start Attach Listener if +StartAttachListener or it can't be started lazily
3983   if (!DisableAttachMechanism) {
3984     AttachListener::vm_start();
3985     if (StartAttachListener || AttachListener::init_at_startup()) {
3986       AttachListener::init();
3987     }
3988   }
3989 
3990   // Launch -Xrun agents
3991   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3992   // back-end can launch with -Xdebug -Xrunjdwp.
3993   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3994     create_vm_init_libraries();
3995   }
3996 
3997   if (CleanChunkPoolAsync) {
3998     Chunk::start_chunk_pool_cleaner_task();
3999   }
4000 
4001 
4002   // initialize compiler(s)
4003 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
4004 #if INCLUDE_JVMCI
4005   bool force_JVMCI_intialization = false;
4006   if (EnableJVMCI) {
4007     // Initialize JVMCI eagerly when it is explicitly requested.
4008     // Or when JVMCILibDumpJNIConfig or JVMCIPrintProperties is enabled.
4009     force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties || JVMCILibDumpJNIConfig;
4010 
4011     if (!force_JVMCI_intialization) {
4012       // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
4013       // compilations via JVMCI will not actually block until JVMCI is initialized.
4014       force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
4015     }
4016   }
4017 #endif
4018   CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
4019   // Postpone completion of compiler initialization to after JVMCI
4020   // is initialized to avoid timeouts of blocking compilations.
4021   if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
4022     CompileBroker::compilation_init_phase2();
4023   }
4024 #endif
4025 
4026   // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
4027   // It is done after compilers are initialized, because otherwise compilations of
4028   // signature polymorphic MH intrinsics can be missed
4029   // (see SystemDictionary::find_method_handle_intrinsic).
4030   initialize_jsr292_core_classes(CHECK_JNI_ERR);
4031 
4032   // This will initialize the module system.  Only java.base classes can be
4033   // loaded until phase 2 completes
4034   call_initPhase2(CHECK_JNI_ERR);
4035 
4036   // Always call even when there are not JVMTI environments yet, since environments
4037   // may be attached late and JVMTI must track phases of VM execution
4038   JvmtiExport::enter_start_phase();
4039 
4040   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
4041   JvmtiExport::post_vm_start();
4042 
4043   // Final system initialization including security manager and system class loader
4044   call_initPhase3(CHECK_JNI_ERR);
4045 
4046   // cache the system and platform class loaders
4047   SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
4048 
4049 #if INCLUDE_CDS
4050   // capture the module path info from the ModuleEntryTable
4051   ClassLoader::initialize_module_path(THREAD);
4052 #endif
4053 
4054 #if INCLUDE_JVMCI
4055   if (force_JVMCI_intialization) {
4056     JVMCI::initialize_compiler(CHECK_JNI_ERR);
4057     CompileBroker::compilation_init_phase2();
4058   }
4059 #endif
4060 
4061   // Always call even when there are not JVMTI environments yet, since environments
4062   // may be attached late and JVMTI must track phases of VM execution
4063   JvmtiExport::enter_live_phase();
4064 
4065   // Make perfmemory accessible
4066   PerfMemory::set_accessible(true);
4067 
4068   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
4069   JvmtiExport::post_vm_initialized();
4070 
4071   JFR_ONLY(Jfr::on_vm_start();)
4072 
4073 #if INCLUDE_MANAGEMENT
4074   Management::initialize(THREAD);
4075 
4076   if (HAS_PENDING_EXCEPTION) {
4077     // management agent fails to start possibly due to
4078     // configuration problem and is responsible for printing
4079     // stack trace if appropriate. Simply exit VM.
4080     vm_exit(1);
4081   }
4082 #endif // INCLUDE_MANAGEMENT
4083 
4084   if (MemProfiling)                   MemProfiler::engage();
4085   StatSampler::engage();
4086   if (CheckJNICalls)                  JniPeriodicChecker::engage();
4087 
4088   BiasedLocking::init();
4089 
4090 #if INCLUDE_RTM_OPT
4091   RTMLockingCounters::init();
4092 #endif
4093 
4094   call_postVMInitHook(THREAD);
4095   // The Java side of PostVMInitHook.run must deal with all
4096   // exceptions and provide means of diagnosis.
4097   if (HAS_PENDING_EXCEPTION) {
4098     CLEAR_PENDING_EXCEPTION;
4099   }
4100 
4101   {
4102     MutexLocker ml(PeriodicTask_lock);
4103     // Make sure the WatcherThread can be started by WatcherThread::start()
4104     // or by dynamic enrollment.
4105     WatcherThread::make_startable();
4106     // Start up the WatcherThread if there are any periodic tasks
4107     // NOTE:  All PeriodicTasks should be registered by now. If they
4108     //   aren't, late joiners might appear to start slowly (we might
4109     //   take a while to process their first tick).
4110     if (PeriodicTask::num_tasks() > 0) {
4111       WatcherThread::start();
4112     }
4113   }
4114 
4115   create_vm_timer.end();
4116 #ifdef ASSERT
4117   _vm_complete = true;
4118 #endif
4119 
4120   if (DumpSharedSpaces) {
4121     MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
4122     ShouldNotReachHere();
4123   }
4124 
4125   return JNI_OK;
4126 }
4127 
4128 // type for the Agent_OnLoad and JVM_OnLoad entry points
4129 extern "C" {
4130   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
4131 }
4132 // Find a command line agent library and return its entry point for
4133 //         -agentlib:  -agentpath:   -Xrun
4134 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
4135 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
4136                                     const char *on_load_symbols[],
4137                                     size_t num_symbol_entries) {
4138   OnLoadEntry_t on_load_entry = NULL;
4139   void *library = NULL;
4140 
4141   if (!agent->valid()) {
4142     char buffer[JVM_MAXPATHLEN];
4143     char ebuf[1024] = "";
4144     const char *name = agent->name();
4145     const char *msg = "Could not find agent library ";
4146 
4147     // First check to see if agent is statically linked into executable
4148     if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
4149       library = agent->os_lib();
4150     } else if (agent->is_absolute_path()) {
4151       library = os::dll_load(name, ebuf, sizeof ebuf);
4152       if (library == NULL) {
4153         const char *sub_msg = " in absolute path, with error: ";
4154         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4155         char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4156         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4157         // If we can't find the agent, exit.
4158         vm_exit_during_initialization(buf, NULL);
4159         FREE_C_HEAP_ARRAY(char, buf);
4160       }
4161     } else {
4162       // Try to load the agent from the standard dll directory
4163       if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4164                              name)) {
4165         library = os::dll_load(buffer, ebuf, sizeof ebuf);
4166       }
4167       if (library == NULL) { // Try the library path directory.
4168         if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4169           library = os::dll_load(buffer, ebuf, sizeof ebuf);
4170         }
4171         if (library == NULL) {
4172           const char *sub_msg = " on the library path, with error: ";
4173           const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4174 
4175           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4176                        strlen(ebuf) + strlen(sub_msg2) + 1;
4177           char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4178           if (!agent->is_instrument_lib()) {
4179             jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4180           } else {
4181             jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4182           }
4183           // If we can't find the agent, exit.
4184           vm_exit_during_initialization(buf, NULL);
4185           FREE_C_HEAP_ARRAY(char, buf);
4186         }
4187       }
4188     }
4189     agent->set_os_lib(library);
4190     agent->set_valid();
4191   }
4192 
4193   // Find the OnLoad function.
4194   on_load_entry =
4195     CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4196                                                           false,
4197                                                           on_load_symbols,
4198                                                           num_symbol_entries));
4199   return on_load_entry;
4200 }
4201 
4202 // Find the JVM_OnLoad entry point
4203 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4204   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4205   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4206 }
4207 
4208 // Find the Agent_OnLoad entry point
4209 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4210   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4211   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4212 }
4213 
4214 // For backwards compatibility with -Xrun
4215 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4216 // treated like -agentpath:
4217 // Must be called before agent libraries are created
4218 void Threads::convert_vm_init_libraries_to_agents() {
4219   AgentLibrary* agent;
4220   AgentLibrary* next;
4221 
4222   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4223     next = agent->next();  // cache the next agent now as this agent may get moved off this list
4224     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4225 
4226     // If there is an JVM_OnLoad function it will get called later,
4227     // otherwise see if there is an Agent_OnLoad
4228     if (on_load_entry == NULL) {
4229       on_load_entry = lookup_agent_on_load(agent);
4230       if (on_load_entry != NULL) {
4231         // switch it to the agent list -- so that Agent_OnLoad will be called,
4232         // JVM_OnLoad won't be attempted and Agent_OnUnload will
4233         Arguments::convert_library_to_agent(agent);
4234       } else {
4235         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4236       }
4237     }
4238   }
4239 }
4240 
4241 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
4242 // Invokes Agent_OnLoad
4243 // Called very early -- before JavaThreads exist
4244 void Threads::create_vm_init_agents() {
4245   extern struct JavaVM_ main_vm;
4246   AgentLibrary* agent;
4247 
4248   JvmtiExport::enter_onload_phase();
4249 
4250   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4251     // CDS dumping does not support native JVMTI agent.
4252     // CDS dumping supports Java agent if the AllowArchivingWithJavaAgent diagnostic option is specified.
4253     if (DumpSharedSpaces || DynamicDumpSharedSpaces) {
4254       if(!agent->is_instrument_lib()) {
4255         vm_exit_during_cds_dumping("CDS dumping does not support native JVMTI agent, name", agent->name());
4256       } else if (!AllowArchivingWithJavaAgent) {
4257         vm_exit_during_cds_dumping(
4258           "Must enable AllowArchivingWithJavaAgent in order to run Java agent during CDS dumping");
4259       }
4260     }
4261 
4262     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
4263 
4264     if (on_load_entry != NULL) {
4265       // Invoke the Agent_OnLoad function
4266       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4267       if (err != JNI_OK) {
4268         vm_exit_during_initialization("agent library failed to init", agent->name());
4269       }
4270     } else {
4271       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4272     }
4273   }
4274 
4275   JvmtiExport::enter_primordial_phase();
4276 }
4277 
4278 extern "C" {
4279   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4280 }
4281 
4282 void Threads::shutdown_vm_agents() {
4283   // Send any Agent_OnUnload notifications
4284   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4285   size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4286   extern struct JavaVM_ main_vm;
4287   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4288 
4289     // Find the Agent_OnUnload function.
4290     Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4291                                                    os::find_agent_function(agent,
4292                                                    false,
4293                                                    on_unload_symbols,
4294                                                    num_symbol_entries));
4295 
4296     // Invoke the Agent_OnUnload function
4297     if (unload_entry != NULL) {
4298       JavaThread* thread = JavaThread::current();
4299       ThreadToNativeFromVM ttn(thread);
4300       HandleMark hm(thread);
4301       (*unload_entry)(&main_vm);
4302     }
4303   }
4304 }
4305 
4306 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4307 // Invokes JVM_OnLoad
4308 void Threads::create_vm_init_libraries() {
4309   extern struct JavaVM_ main_vm;
4310   AgentLibrary* agent;
4311 
4312   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4313     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4314 
4315     if (on_load_entry != NULL) {
4316       // Invoke the JVM_OnLoad function
4317       JavaThread* thread = JavaThread::current();
4318       ThreadToNativeFromVM ttn(thread);
4319       HandleMark hm(thread);
4320       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4321       if (err != JNI_OK) {
4322         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4323       }
4324     } else {
4325       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4326     }
4327   }
4328 }
4329 
4330 
4331 // Last thread running calls java.lang.Shutdown.shutdown()
4332 void JavaThread::invoke_shutdown_hooks() {
4333   HandleMark hm(this);
4334 
4335   // We could get here with a pending exception, if so clear it now.
4336   if (this->has_pending_exception()) {
4337     this->clear_pending_exception();
4338   }
4339 
4340   EXCEPTION_MARK;
4341   Klass* shutdown_klass =
4342     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4343                                       THREAD);
4344   if (shutdown_klass != NULL) {
4345     // SystemDictionary::resolve_or_null will return null if there was
4346     // an exception.  If we cannot load the Shutdown class, just don't
4347     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
4348     // won't be run.  Note that if a shutdown hook was registered,
4349     // the Shutdown class would have already been loaded
4350     // (Runtime.addShutdownHook will load it).
4351     JavaValue result(T_VOID);
4352     JavaCalls::call_static(&result,
4353                            shutdown_klass,
4354                            vmSymbols::shutdown_name(),
4355                            vmSymbols::void_method_signature(),
4356                            THREAD);
4357   }
4358   CLEAR_PENDING_EXCEPTION;
4359 }
4360 
4361 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4362 // the program falls off the end of main(). Another VM exit path is through
4363 // vm_exit() when the program calls System.exit() to return a value or when
4364 // there is a serious error in VM. The two shutdown paths are not exactly
4365 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4366 // and VM_Exit op at VM level.
4367 //
4368 // Shutdown sequence:
4369 //   + Shutdown native memory tracking if it is on
4370 //   + Wait until we are the last non-daemon thread to execute
4371 //     <-- every thing is still working at this moment -->
4372 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4373 //        shutdown hooks
4374 //   + Call before_exit(), prepare for VM exit
4375 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4376 //        currently the only user of this mechanism is File.deleteOnExit())
4377 //      > stop StatSampler, watcher thread, CMS threads,
4378 //        post thread end and vm death events to JVMTI,
4379 //        stop signal thread
4380 //   + Call JavaThread::exit(), it will:
4381 //      > release JNI handle blocks, remove stack guard pages
4382 //      > remove this thread from Threads list
4383 //     <-- no more Java code from this thread after this point -->
4384 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4385 //     the compiler threads at safepoint
4386 //     <-- do not use anything that could get blocked by Safepoint -->
4387 //   + Disable tracing at JNI/JVM barriers
4388 //   + Set _vm_exited flag for threads that are still running native code
4389 //   + Call exit_globals()
4390 //      > deletes tty
4391 //      > deletes PerfMemory resources
4392 //   + Delete this thread
4393 //   + Return to caller
4394 
4395 bool Threads::destroy_vm() {
4396   JavaThread* thread = JavaThread::current();
4397 
4398 #ifdef ASSERT
4399   _vm_complete = false;
4400 #endif
4401   // Wait until we are the last non-daemon thread to execute
4402   { MonitorLocker nu(Threads_lock);
4403     while (Threads::number_of_non_daemon_threads() > 1)
4404       // This wait should make safepoint checks, wait without a timeout,
4405       // and wait as a suspend-equivalent condition.
4406       nu.wait(0, Mutex::_as_suspend_equivalent_flag);
4407   }
4408 
4409   EventShutdown e;
4410   if (e.should_commit()) {
4411     e.set_reason("No remaining non-daemon Java threads");
4412     e.commit();
4413   }
4414 
4415   // Hang forever on exit if we are reporting an error.
4416   if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4417     os::infinite_sleep();
4418   }
4419   os::wait_for_keypress_at_exit();
4420 
4421   // run Java level shutdown hooks
4422   thread->invoke_shutdown_hooks();
4423 
4424   before_exit(thread);
4425 
4426   thread->exit(true);
4427 
4428   // Stop VM thread.
4429   {
4430     // 4945125 The vm thread comes to a safepoint during exit.
4431     // GC vm_operations can get caught at the safepoint, and the
4432     // heap is unparseable if they are caught. Grab the Heap_lock
4433     // to prevent this. The GC vm_operations will not be able to
4434     // queue until after the vm thread is dead. After this point,
4435     // we'll never emerge out of the safepoint before the VM exits.
4436 
4437     MutexLocker ml(Heap_lock, Mutex::_no_safepoint_check_flag);
4438 
4439     VMThread::wait_for_vm_thread_exit();
4440     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4441     VMThread::destroy();
4442   }
4443 
4444   // Now, all Java threads are gone except daemon threads. Daemon threads
4445   // running Java code or in VM are stopped by the Safepoint. However,
4446   // daemon threads executing native code are still running.  But they
4447   // will be stopped at native=>Java/VM barriers. Note that we can't
4448   // simply kill or suspend them, as it is inherently deadlock-prone.
4449 
4450   VM_Exit::set_vm_exited();
4451 
4452   // Clean up ideal graph printers after the VMThread has started
4453   // the final safepoint which will block all the Compiler threads.
4454   // Note that this Thread has already logically exited so the
4455   // clean_up() function's use of a JavaThreadIteratorWithHandle
4456   // would be a problem except set_vm_exited() has remembered the
4457   // shutdown thread which is granted a policy exception.
4458 #if defined(COMPILER2) && !defined(PRODUCT)
4459   IdealGraphPrinter::clean_up();
4460 #endif
4461 
4462   notify_vm_shutdown();
4463 
4464   // exit_globals() will delete tty
4465   exit_globals();
4466 
4467   // We are after VM_Exit::set_vm_exited() so we can't call
4468   // thread->smr_delete() or we will block on the Threads_lock.
4469   // Deleting the shutdown thread here is safe because another
4470   // JavaThread cannot have an active ThreadsListHandle for
4471   // this JavaThread.
4472   delete thread;
4473 
4474 #if INCLUDE_JVMCI
4475   if (JVMCICounterSize > 0) {
4476     FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4477   }
4478 #endif
4479 
4480   LogConfiguration::finalize();
4481 
4482   return true;
4483 }
4484 
4485 
4486 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4487   if (version == JNI_VERSION_1_1) return JNI_TRUE;
4488   return is_supported_jni_version(version);
4489 }
4490 
4491 
4492 jboolean Threads::is_supported_jni_version(jint version) {
4493   if (version == JNI_VERSION_1_2) return JNI_TRUE;
4494   if (version == JNI_VERSION_1_4) return JNI_TRUE;
4495   if (version == JNI_VERSION_1_6) return JNI_TRUE;
4496   if (version == JNI_VERSION_1_8) return JNI_TRUE;
4497   if (version == JNI_VERSION_9) return JNI_TRUE;
4498   if (version == JNI_VERSION_10) return JNI_TRUE;
4499   return JNI_FALSE;
4500 }
4501 
4502 
4503 void Threads::add(JavaThread* p, bool force_daemon) {
4504   // The threads lock must be owned at this point
4505   assert(Threads_lock->owned_by_self(), "must have threads lock");
4506 
4507   BarrierSet::barrier_set()->on_thread_attach(p);
4508 
4509   // Once a JavaThread is added to the Threads list, smr_delete() has
4510   // to be used to delete it. Otherwise we can just delete it directly.
4511   p->set_on_thread_list();
4512 
4513   _number_of_threads++;
4514   oop threadObj = p->threadObj();
4515   bool daemon = true;
4516   // Bootstrapping problem: threadObj can be null for initial
4517   // JavaThread (or for threads attached via JNI)
4518   if ((!force_daemon) && !is_daemon((threadObj))) {
4519     _number_of_non_daemon_threads++;
4520     daemon = false;
4521   }
4522 
4523   ThreadService::add_thread(p, daemon);
4524 
4525   // Maintain fast thread list
4526   ThreadsSMRSupport::add_thread(p);
4527 
4528   // Possible GC point.
4529   Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4530 }
4531 
4532 void Threads::remove(JavaThread* p, bool is_daemon) {
4533 
4534   // Reclaim the ObjectMonitors from the omInUseList and omFreeList of the moribund thread.
4535   ObjectSynchronizer::omFlush(p);
4536 
4537   // Extra scope needed for Thread_lock, so we can check
4538   // that we do not remove thread without safepoint code notice
4539   { MonitorLocker ml(Threads_lock);
4540 
4541     assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4542 
4543     // Maintain fast thread list
4544     ThreadsSMRSupport::remove_thread(p);
4545 
4546     _number_of_threads--;
4547     if (!is_daemon) {
4548       _number_of_non_daemon_threads--;
4549 
4550       // Only one thread left, do a notify on the Threads_lock so a thread waiting
4551       // on destroy_vm will wake up.
4552       if (number_of_non_daemon_threads() == 1) {
4553         ml.notify_all();
4554       }
4555     }
4556     ThreadService::remove_thread(p, is_daemon);
4557 
4558     // Make sure that safepoint code disregard this thread. This is needed since
4559     // the thread might mess around with locks after this point. This can cause it
4560     // to do callbacks into the safepoint code. However, the safepoint code is not aware
4561     // of this thread since it is removed from the queue.
4562     p->set_terminated_value();
4563   } // unlock Threads_lock
4564 
4565   // Since Events::log uses a lock, we grab it outside the Threads_lock
4566   Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4567 }
4568 
4569 // Operations on the Threads list for GC.  These are not explicitly locked,
4570 // but the garbage collector must provide a safe context for them to run.
4571 // In particular, these things should never be called when the Threads_lock
4572 // is held by some other thread. (Note: the Safepoint abstraction also
4573 // uses the Threads_lock to guarantee this property. It also makes sure that
4574 // all threads gets blocked when exiting or starting).
4575 
4576 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4577   ALL_JAVA_THREADS(p) {
4578     p->oops_do(f, cf);
4579   }
4580   VMThread::vm_thread()->oops_do(f, cf);
4581 }
4582 
4583 void Threads::change_thread_claim_token() {
4584   if (++_thread_claim_token == 0) {
4585     // On overflow of the token counter, there is a risk of future
4586     // collisions between a new global token value and a stale token
4587     // for a thread, because not all iterations visit all threads.
4588     // (Though it's pretty much a theoretical concern for non-trivial
4589     // token counter sizes.)  To deal with the possibility, reset all
4590     // the thread tokens to zero on global token overflow.
4591     struct ResetClaims : public ThreadClosure {
4592       virtual void do_thread(Thread* t) {
4593         t->claim_threads_do(false, 0);
4594       }
4595     } reset_claims;
4596     Threads::threads_do(&reset_claims);
4597     // On overflow, update the global token to non-zero, to
4598     // avoid the special "never claimed" initial thread value.
4599     _thread_claim_token = 1;
4600   }
4601 }
4602 
4603 #ifdef ASSERT
4604 void assert_thread_claimed(const char* kind, Thread* t, uintx expected) {
4605   const uintx token = t->threads_do_token();
4606   assert(token == expected,
4607          "%s " PTR_FORMAT " has incorrect value " UINTX_FORMAT " != "
4608          UINTX_FORMAT, kind, p2i(t), token, expected);
4609 }
4610 
4611 void Threads::assert_all_threads_claimed() {
4612   ALL_JAVA_THREADS(p) {
4613     assert_thread_claimed("Thread", p, _thread_claim_token);
4614   }
4615   assert_thread_claimed("VMThread", VMThread::vm_thread(), _thread_claim_token);
4616 }
4617 #endif // ASSERT
4618 
4619 class ParallelOopsDoThreadClosure : public ThreadClosure {
4620 private:
4621   OopClosure* _f;
4622   CodeBlobClosure* _cf;
4623 public:
4624   ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4625   void do_thread(Thread* t) {
4626     t->oops_do(_f, _cf);
4627   }
4628 };
4629 
4630 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4631   ParallelOopsDoThreadClosure tc(f, cf);
4632   possibly_parallel_threads_do(is_par, &tc);
4633 }
4634 
4635 void Threads::nmethods_do(CodeBlobClosure* cf) {
4636   ALL_JAVA_THREADS(p) {
4637     // This is used by the code cache sweeper to mark nmethods that are active
4638     // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4639     // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4640     if(!p->is_Code_cache_sweeper_thread()) {
4641       p->nmethods_do(cf);
4642     }
4643   }
4644 }
4645 
4646 void Threads::metadata_do(MetadataClosure* f) {
4647   ALL_JAVA_THREADS(p) {
4648     p->metadata_do(f);
4649   }
4650 }
4651 
4652 class ThreadHandlesClosure : public ThreadClosure {
4653   void (*_f)(Metadata*);
4654  public:
4655   ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4656   virtual void do_thread(Thread* thread) {
4657     thread->metadata_handles_do(_f);
4658   }
4659 };
4660 
4661 void Threads::metadata_handles_do(void f(Metadata*)) {
4662   // Only walk the Handles in Thread.
4663   ThreadHandlesClosure handles_closure(f);
4664   threads_do(&handles_closure);
4665 }
4666 
4667 void Threads::deoptimized_wrt_marked_nmethods() {
4668   ALL_JAVA_THREADS(p) {
4669     p->deoptimized_wrt_marked_nmethods();
4670   }
4671 }
4672 
4673 
4674 // Get count Java threads that are waiting to enter the specified monitor.
4675 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4676                                                          int count,
4677                                                          address monitor) {
4678   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4679 
4680   int i = 0;
4681   DO_JAVA_THREADS(t_list, p) {
4682     if (!p->can_call_java()) continue;
4683 
4684     address pending = (address)p->current_pending_monitor();
4685     if (pending == monitor) {             // found a match
4686       if (i < count) result->append(p);   // save the first count matches
4687       i++;
4688     }
4689   }
4690 
4691   return result;
4692 }
4693 
4694 
4695 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4696                                                       address owner) {
4697   // NULL owner means not locked so we can skip the search
4698   if (owner == NULL) return NULL;
4699 
4700   DO_JAVA_THREADS(t_list, p) {
4701     // first, see if owner is the address of a Java thread
4702     if (owner == (address)p) return p;
4703   }
4704 
4705   // Cannot assert on lack of success here since this function may be
4706   // used by code that is trying to report useful problem information
4707   // like deadlock detection.
4708   if (UseHeavyMonitors) return NULL;
4709 
4710   // If we didn't find a matching Java thread and we didn't force use of
4711   // heavyweight monitors, then the owner is the stack address of the
4712   // Lock Word in the owning Java thread's stack.
4713   //
4714   JavaThread* the_owner = NULL;
4715   DO_JAVA_THREADS(t_list, q) {
4716     if (q->is_lock_owned(owner)) {
4717       the_owner = q;
4718       break;
4719     }
4720   }
4721 
4722   // cannot assert on lack of success here; see above comment
4723   return the_owner;
4724 }
4725 
4726 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4727 void Threads::print_on(outputStream* st, bool print_stacks,
4728                        bool internal_format, bool print_concurrent_locks,
4729                        bool print_extended_info) {
4730   char buf[32];
4731   st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4732 
4733   st->print_cr("Full thread dump %s (%s %s):",
4734                VM_Version::vm_name(),
4735                VM_Version::vm_release(),
4736                VM_Version::vm_info_string());
4737   st->cr();
4738 
4739 #if INCLUDE_SERVICES
4740   // Dump concurrent locks
4741   ConcurrentLocksDump concurrent_locks;
4742   if (print_concurrent_locks) {
4743     concurrent_locks.dump_at_safepoint();
4744   }
4745 #endif // INCLUDE_SERVICES
4746 
4747   ThreadsSMRSupport::print_info_on(st);
4748   st->cr();
4749 
4750   ALL_JAVA_THREADS(p) {
4751     ResourceMark rm;
4752     p->print_on(st, print_extended_info);
4753     if (print_stacks) {
4754       if (internal_format) {
4755         p->trace_stack();
4756       } else {
4757         p->print_stack_on(st);
4758       }
4759     }
4760     st->cr();
4761 #if INCLUDE_SERVICES
4762     if (print_concurrent_locks) {
4763       concurrent_locks.print_locks_on(p, st);
4764     }
4765 #endif // INCLUDE_SERVICES
4766   }
4767 
4768   VMThread::vm_thread()->print_on(st);
4769   st->cr();
4770   Universe::heap()->print_gc_threads_on(st);
4771   WatcherThread* wt = WatcherThread::watcher_thread();
4772   if (wt != NULL) {
4773     wt->print_on(st);
4774     st->cr();
4775   }
4776 
4777   st->flush();
4778 }
4779 
4780 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4781                              int buflen, bool* found_current) {
4782   if (this_thread != NULL) {
4783     bool is_current = (current == this_thread);
4784     *found_current = *found_current || is_current;
4785     st->print("%s", is_current ? "=>" : "  ");
4786 
4787     st->print(PTR_FORMAT, p2i(this_thread));
4788     st->print(" ");
4789     this_thread->print_on_error(st, buf, buflen);
4790     st->cr();
4791   }
4792 }
4793 
4794 class PrintOnErrorClosure : public ThreadClosure {
4795   outputStream* _st;
4796   Thread* _current;
4797   char* _buf;
4798   int _buflen;
4799   bool* _found_current;
4800  public:
4801   PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4802                       int buflen, bool* found_current) :
4803    _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4804 
4805   virtual void do_thread(Thread* thread) {
4806     Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4807   }
4808 };
4809 
4810 // Threads::print_on_error() is called by fatal error handler. It's possible
4811 // that VM is not at safepoint and/or current thread is inside signal handler.
4812 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4813 // memory (even in resource area), it might deadlock the error handler.
4814 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4815                              int buflen) {
4816   ThreadsSMRSupport::print_info_on(st);
4817   st->cr();
4818 
4819   bool found_current = false;
4820   st->print_cr("Java Threads: ( => current thread )");
4821   ALL_JAVA_THREADS(thread) {
4822     print_on_error(thread, st, current, buf, buflen, &found_current);
4823   }
4824   st->cr();
4825 
4826   st->print_cr("Other Threads:");
4827   print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4828   print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4829 
4830   PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4831   Universe::heap()->gc_threads_do(&print_closure);
4832 
4833   if (!found_current) {
4834     st->cr();
4835     st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4836     current->print_on_error(st, buf, buflen);
4837     st->cr();
4838   }
4839   st->cr();
4840 
4841   st->print_cr("Threads with active compile tasks:");
4842   print_threads_compiling(st, buf, buflen);
4843 }
4844 
4845 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen, bool short_form) {
4846   ALL_JAVA_THREADS(thread) {
4847     if (thread->is_Compiler_thread()) {
4848       CompilerThread* ct = (CompilerThread*) thread;
4849 
4850       // Keep task in local variable for NULL check.
4851       // ct->_task might be set to NULL by concurring compiler thread
4852       // because it completed the compilation. The task is never freed,
4853       // though, just returned to a free list.
4854       CompileTask* task = ct->task();
4855       if (task != NULL) {
4856         thread->print_name_on_error(st, buf, buflen);
4857         st->print("  ");
4858         task->print(st, NULL, short_form, true);
4859       }
4860     }
4861   }
4862 }
4863 
4864 
4865 // Internal SpinLock and Mutex
4866 // Based on ParkEvent
4867 
4868 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4869 //
4870 // We employ SpinLocks _only for low-contention, fixed-length
4871 // short-duration critical sections where we're concerned
4872 // about native mutex_t or HotSpot Mutex:: latency.
4873 // The mux construct provides a spin-then-block mutual exclusion
4874 // mechanism.
4875 //
4876 // Testing has shown that contention on the ListLock guarding gFreeList
4877 // is common.  If we implement ListLock as a simple SpinLock it's common
4878 // for the JVM to devolve to yielding with little progress.  This is true
4879 // despite the fact that the critical sections protected by ListLock are
4880 // extremely short.
4881 //
4882 // TODO-FIXME: ListLock should be of type SpinLock.
4883 // We should make this a 1st-class type, integrated into the lock
4884 // hierarchy as leaf-locks.  Critically, the SpinLock structure
4885 // should have sufficient padding to avoid false-sharing and excessive
4886 // cache-coherency traffic.
4887 
4888 
4889 typedef volatile int SpinLockT;
4890 
4891 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4892   if (Atomic::cmpxchg (1, adr, 0) == 0) {
4893     return;   // normal fast-path return
4894   }
4895 
4896   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4897   int ctr = 0;
4898   int Yields = 0;
4899   for (;;) {
4900     while (*adr != 0) {
4901       ++ctr;
4902       if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4903         if (Yields > 5) {
4904           os::naked_short_sleep(1);
4905         } else {
4906           os::naked_yield();
4907           ++Yields;
4908         }
4909       } else {
4910         SpinPause();
4911       }
4912     }
4913     if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4914   }
4915 }
4916 
4917 void Thread::SpinRelease(volatile int * adr) {
4918   assert(*adr != 0, "invariant");
4919   OrderAccess::fence();      // guarantee at least release consistency.
4920   // Roach-motel semantics.
4921   // It's safe if subsequent LDs and STs float "up" into the critical section,
4922   // but prior LDs and STs within the critical section can't be allowed
4923   // to reorder or float past the ST that releases the lock.
4924   // Loads and stores in the critical section - which appear in program
4925   // order before the store that releases the lock - must also appear
4926   // before the store that releases the lock in memory visibility order.
4927   // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4928   // the ST of 0 into the lock-word which releases the lock, so fence
4929   // more than covers this on all platforms.
4930   *adr = 0;
4931 }
4932 
4933 // muxAcquire and muxRelease:
4934 //
4935 // *  muxAcquire and muxRelease support a single-word lock-word construct.
4936 //    The LSB of the word is set IFF the lock is held.
4937 //    The remainder of the word points to the head of a singly-linked list
4938 //    of threads blocked on the lock.
4939 //
4940 // *  The current implementation of muxAcquire-muxRelease uses its own
4941 //    dedicated Thread._MuxEvent instance.  If we're interested in
4942 //    minimizing the peak number of extant ParkEvent instances then
4943 //    we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4944 //    as certain invariants were satisfied.  Specifically, care would need
4945 //    to be taken with regards to consuming unpark() "permits".
4946 //    A safe rule of thumb is that a thread would never call muxAcquire()
4947 //    if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4948 //    park().  Otherwise the _ParkEvent park() operation in muxAcquire() could
4949 //    consume an unpark() permit intended for monitorenter, for instance.
4950 //    One way around this would be to widen the restricted-range semaphore
4951 //    implemented in park().  Another alternative would be to provide
4952 //    multiple instances of the PlatformEvent() for each thread.  One
4953 //    instance would be dedicated to muxAcquire-muxRelease, for instance.
4954 //
4955 // *  Usage:
4956 //    -- Only as leaf locks
4957 //    -- for short-term locking only as muxAcquire does not perform
4958 //       thread state transitions.
4959 //
4960 // Alternatives:
4961 // *  We could implement muxAcquire and muxRelease with MCS or CLH locks
4962 //    but with parking or spin-then-park instead of pure spinning.
4963 // *  Use Taura-Oyama-Yonenzawa locks.
4964 // *  It's possible to construct a 1-0 lock if we encode the lockword as
4965 //    (List,LockByte).  Acquire will CAS the full lockword while Release
4966 //    will STB 0 into the LockByte.  The 1-0 scheme admits stranding, so
4967 //    acquiring threads use timers (ParkTimed) to detect and recover from
4968 //    the stranding window.  Thread/Node structures must be aligned on 256-byte
4969 //    boundaries by using placement-new.
4970 // *  Augment MCS with advisory back-link fields maintained with CAS().
4971 //    Pictorially:  LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4972 //    The validity of the backlinks must be ratified before we trust the value.
4973 //    If the backlinks are invalid the exiting thread must back-track through the
4974 //    the forward links, which are always trustworthy.
4975 // *  Add a successor indication.  The LockWord is currently encoded as
4976 //    (List, LOCKBIT:1).  We could also add a SUCCBIT or an explicit _succ variable
4977 //    to provide the usual futile-wakeup optimization.
4978 //    See RTStt for details.
4979 //
4980 
4981 
4982 const intptr_t LOCKBIT = 1;
4983 
4984 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4985   intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4986   if (w == 0) return;
4987   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4988     return;
4989   }
4990 
4991   ParkEvent * const Self = Thread::current()->_MuxEvent;
4992   assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4993   for (;;) {
4994     int its = (os::is_MP() ? 100 : 0) + 1;
4995 
4996     // Optional spin phase: spin-then-park strategy
4997     while (--its >= 0) {
4998       w = *Lock;
4999       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5000         return;
5001       }
5002     }
5003 
5004     Self->reset();
5005     Self->OnList = intptr_t(Lock);
5006     // The following fence() isn't _strictly necessary as the subsequent
5007     // CAS() both serializes execution and ratifies the fetched *Lock value.
5008     OrderAccess::fence();
5009     for (;;) {
5010       w = *Lock;
5011       if ((w & LOCKBIT) == 0) {
5012         if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5013           Self->OnList = 0;   // hygiene - allows stronger asserts
5014           return;
5015         }
5016         continue;      // Interference -- *Lock changed -- Just retry
5017       }
5018       assert(w & LOCKBIT, "invariant");
5019       Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
5020       if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
5021     }
5022 
5023     while (Self->OnList != 0) {
5024       Self->park();
5025     }
5026   }
5027 }
5028 
5029 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
5030   intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
5031   if (w == 0) return;
5032   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5033     return;
5034   }
5035 
5036   ParkEvent * ReleaseAfter = NULL;
5037   if (ev == NULL) {
5038     ev = ReleaseAfter = ParkEvent::Allocate(NULL);
5039   }
5040   assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
5041   for (;;) {
5042     guarantee(ev->OnList == 0, "invariant");
5043     int its = (os::is_MP() ? 100 : 0) + 1;
5044 
5045     // Optional spin phase: spin-then-park strategy
5046     while (--its >= 0) {
5047       w = *Lock;
5048       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5049         if (ReleaseAfter != NULL) {
5050           ParkEvent::Release(ReleaseAfter);
5051         }
5052         return;
5053       }
5054     }
5055 
5056     ev->reset();
5057     ev->OnList = intptr_t(Lock);
5058     // The following fence() isn't _strictly necessary as the subsequent
5059     // CAS() both serializes execution and ratifies the fetched *Lock value.
5060     OrderAccess::fence();
5061     for (;;) {
5062       w = *Lock;
5063       if ((w & LOCKBIT) == 0) {
5064         if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5065           ev->OnList = 0;
5066           // We call ::Release while holding the outer lock, thus
5067           // artificially lengthening the critical section.
5068           // Consider deferring the ::Release() until the subsequent unlock(),
5069           // after we've dropped the outer lock.
5070           if (ReleaseAfter != NULL) {
5071             ParkEvent::Release(ReleaseAfter);
5072           }
5073           return;
5074         }
5075         continue;      // Interference -- *Lock changed -- Just retry
5076       }
5077       assert(w & LOCKBIT, "invariant");
5078       ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
5079       if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
5080     }
5081 
5082     while (ev->OnList != 0) {
5083       ev->park();
5084     }
5085   }
5086 }
5087 
5088 // Release() must extract a successor from the list and then wake that thread.
5089 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
5090 // similar to that used by ParkEvent::Allocate() and ::Release().  DMR-based
5091 // Release() would :
5092 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
5093 // (B) Extract a successor from the private list "in-hand"
5094 // (C) attempt to CAS() the residual back into *Lock over null.
5095 //     If there were any newly arrived threads and the CAS() would fail.
5096 //     In that case Release() would detach the RATs, re-merge the list in-hand
5097 //     with the RATs and repeat as needed.  Alternately, Release() might
5098 //     detach and extract a successor, but then pass the residual list to the wakee.
5099 //     The wakee would be responsible for reattaching and remerging before it
5100 //     competed for the lock.
5101 //
5102 // Both "pop" and DMR are immune from ABA corruption -- there can be
5103 // multiple concurrent pushers, but only one popper or detacher.
5104 // This implementation pops from the head of the list.  This is unfair,
5105 // but tends to provide excellent throughput as hot threads remain hot.
5106 // (We wake recently run threads first).
5107 //
5108 // All paths through muxRelease() will execute a CAS.
5109 // Release consistency -- We depend on the CAS in muxRelease() to provide full
5110 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
5111 // executed within the critical section are complete and globally visible before the
5112 // store (CAS) to the lock-word that releases the lock becomes globally visible.
5113 void Thread::muxRelease(volatile intptr_t * Lock)  {
5114   for (;;) {
5115     const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
5116     assert(w & LOCKBIT, "invariant");
5117     if (w == LOCKBIT) return;
5118     ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
5119     assert(List != NULL, "invariant");
5120     assert(List->OnList == intptr_t(Lock), "invariant");
5121     ParkEvent * const nxt = List->ListNext;
5122     guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
5123 
5124     // The following CAS() releases the lock and pops the head element.
5125     // The CAS() also ratifies the previously fetched lock-word value.
5126     if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
5127       continue;
5128     }
5129     List->OnList = 0;
5130     OrderAccess::fence();
5131     List->unpark();
5132     return;
5133   }
5134 }
5135 
5136 
5137 void Threads::verify() {
5138   ALL_JAVA_THREADS(p) {
5139     p->verify();
5140   }
5141   VMThread* thread = VMThread::vm_thread();
5142   if (thread != NULL) thread->verify();
5143 }