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_deopt_mark(NULL);
1690   set_deopt_compiled_method(NULL);
1691   clear_must_deopt_id();
1692   set_monitor_chunks(NULL);
1693   _on_thread_list = false;
1694   set_thread_state(_thread_new);
1695   _terminated = _not_terminated;
1696   _array_for_gc = NULL;
1697   _suspend_equivalent = false;
1698   _in_deopt_handler = 0;
1699   _doing_unsafe_access = false;
1700   _stack_guard_state = stack_guard_unused;
1701 #if INCLUDE_JVMCI
1702   _pending_monitorenter = false;
1703   _pending_deoptimization = -1;
1704   _pending_failed_speculation = 0;
1705   _pending_transfer_to_interpreter = false;
1706   _in_retryable_allocation = false;
1707   _jvmci._alternate_call_target = NULL;
1708   assert(_jvmci._implicit_exception_pc == NULL, "must be");
1709   _jvmci_counters = NULL;
1710   if (JVMCICounterSize > 0) {
1711     resize_counters(0, (int) JVMCICounterSize);
1712   }
1713 #endif // INCLUDE_JVMCI
1714   _reserved_stack_activation = NULL;  // stack base not known yet
1715   (void)const_cast<oop&>(_exception_oop = oop(NULL));
1716   _exception_pc  = 0;
1717   _exception_handler_pc = 0;
1718   _is_method_handle_return = 0;
1719   _jvmti_thread_state= NULL;
1720   _should_post_on_exceptions_flag = JNI_FALSE;
1721   _interp_only_mode    = 0;
1722   _special_runtime_exit_condition = _no_async_condition;
1723   _pending_async_exception = NULL;
1724   _thread_stat = NULL;
1725   _thread_stat = new ThreadStatistics();
1726   _blocked_on_compilation = false;
1727   _jni_active_critical = 0;
1728   _pending_jni_exception_check_fn = NULL;
1729   _do_not_unlock_if_synchronized = false;
1730   _cached_monitor_info = NULL;
1731   _parker = Parker::Allocate(this);
1732 
1733 #ifndef PRODUCT
1734   _jmp_ring_index = 0;
1735   for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1736     record_jump(NULL, NULL, NULL, 0);
1737   }
1738 #endif // PRODUCT
1739 
1740   // Setup safepoint state info for this thread
1741   ThreadSafepointState::create(this);
1742 
1743   debug_only(_java_call_counter = 0);
1744 
1745   // JVMTI PopFrame support
1746   _popframe_condition = popframe_inactive;
1747   _popframe_preserved_args = NULL;
1748   _popframe_preserved_args_size = 0;
1749   _frames_to_pop_failed_realloc = 0;
1750 
1751   if (SafepointMechanism::uses_thread_local_poll()) {
1752     SafepointMechanism::initialize_header(this);
1753   }
1754 
1755   _class_to_be_initialized = NULL;
1756 
1757   pd_initialize();
1758 }
1759 
1760 JavaThread::JavaThread(bool is_attaching_via_jni) :
1761                        Thread() {
1762   initialize();
1763   if (is_attaching_via_jni) {
1764     _jni_attach_state = _attaching_via_jni;
1765   } else {
1766     _jni_attach_state = _not_attaching_via_jni;
1767   }
1768   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1769 }
1770 
1771 bool JavaThread::reguard_stack(address cur_sp) {
1772   if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1773       && _stack_guard_state != stack_guard_reserved_disabled) {
1774     return true; // Stack already guarded or guard pages not needed.
1775   }
1776 
1777   if (register_stack_overflow()) {
1778     // For those architectures which have separate register and
1779     // memory stacks, we must check the register stack to see if
1780     // it has overflowed.
1781     return false;
1782   }
1783 
1784   // Java code never executes within the yellow zone: the latter is only
1785   // there to provoke an exception during stack banging.  If java code
1786   // is executing there, either StackShadowPages should be larger, or
1787   // some exception code in c1, c2 or the interpreter isn't unwinding
1788   // when it should.
1789   guarantee(cur_sp > stack_reserved_zone_base(),
1790             "not enough space to reguard - increase StackShadowPages");
1791   if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1792     enable_stack_yellow_reserved_zone();
1793     if (reserved_stack_activation() != stack_base()) {
1794       set_reserved_stack_activation(stack_base());
1795     }
1796   } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1797     set_reserved_stack_activation(stack_base());
1798     enable_stack_reserved_zone();
1799   }
1800   return true;
1801 }
1802 
1803 bool JavaThread::reguard_stack(void) {
1804   return reguard_stack(os::current_stack_pointer());
1805 }
1806 
1807 
1808 void JavaThread::block_if_vm_exited() {
1809   if (_terminated == _vm_exited) {
1810     // _vm_exited is set at safepoint, and Threads_lock is never released
1811     // we will block here forever
1812     Threads_lock->lock();
1813     ShouldNotReachHere();
1814   }
1815 }
1816 
1817 
1818 // Remove this ifdef when C1 is ported to the compiler interface.
1819 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1820 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1821 
1822 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1823                        Thread() {
1824   initialize();
1825   _jni_attach_state = _not_attaching_via_jni;
1826   set_entry_point(entry_point);
1827   // Create the native thread itself.
1828   // %note runtime_23
1829   os::ThreadType thr_type = os::java_thread;
1830   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1831                                                      os::java_thread;
1832   os::create_thread(this, thr_type, stack_sz);
1833   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1834   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1835   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1836   // the exception consists of creating the exception object & initializing it, initialization
1837   // will leave the VM via a JavaCall and then all locks must be unlocked).
1838   //
1839   // The thread is still suspended when we reach here. Thread must be explicit started
1840   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1841   // by calling Threads:add. The reason why this is not done here, is because the thread
1842   // object must be fully initialized (take a look at JVM_Start)
1843 }
1844 
1845 JavaThread::~JavaThread() {
1846 
1847   // JSR166 -- return the parker to the free list
1848   Parker::Release(_parker);
1849   _parker = NULL;
1850 
1851   // Free any remaining  previous UnrollBlock
1852   vframeArray* old_array = vframe_array_last();
1853 
1854   if (old_array != NULL) {
1855     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1856     old_array->set_unroll_block(NULL);
1857     delete old_info;
1858     delete old_array;
1859   }
1860 
1861   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1862   if (deferred != NULL) {
1863     // This can only happen if thread is destroyed before deoptimization occurs.
1864     assert(deferred->length() != 0, "empty array!");
1865     do {
1866       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1867       deferred->remove_at(0);
1868       // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1869       delete dlv;
1870     } while (deferred->length() != 0);
1871     delete deferred;
1872   }
1873 
1874   // All Java related clean up happens in exit
1875   ThreadSafepointState::destroy(this);
1876   if (_thread_stat != NULL) delete _thread_stat;
1877 
1878 #if INCLUDE_JVMCI
1879   if (JVMCICounterSize > 0) {
1880     if (jvmci_counters_include(this)) {
1881       for (int i = 0; i < JVMCICounterSize; i++) {
1882         _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1883       }
1884     }
1885     FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1886   }
1887 #endif // INCLUDE_JVMCI
1888 }
1889 
1890 
1891 // First JavaThread specific code executed by a new Java thread.
1892 void JavaThread::pre_run() {
1893   // empty - see comments in run()
1894 }
1895 
1896 // The main routine called by a new Java thread. This isn't overridden
1897 // by subclasses, instead different subclasses define a different "entry_point"
1898 // which defines the actual logic for that kind of thread.
1899 void JavaThread::run() {
1900   // initialize thread-local alloc buffer related fields
1901   this->initialize_tlab();
1902 
1903   // Used to test validity of stack trace backs.
1904   // This can't be moved into pre_run() else we invalidate
1905   // the requirement that thread_main_inner is lower on
1906   // the stack. Consequently all the initialization logic
1907   // stays here in run() rather than pre_run().
1908   this->record_base_of_stack_pointer();
1909 
1910   this->create_stack_guard_pages();
1911 
1912   this->cache_global_variables();
1913 
1914   // Thread is now sufficiently initialized to be handled by the safepoint code as being
1915   // in the VM. Change thread state from _thread_new to _thread_in_vm
1916   ThreadStateTransition::transition(this, _thread_new, _thread_in_vm);
1917   // Before a thread is on the threads list it is always safe, so after leaving the
1918   // _thread_new we should emit a instruction barrier. The distance to modified code
1919   // from here is probably far enough, but this is consistent and safe.
1920   OrderAccess::cross_modify_fence();
1921 
1922   assert(JavaThread::current() == this, "sanity check");
1923   assert(!Thread::current()->owns_locks(), "sanity check");
1924 
1925   DTRACE_THREAD_PROBE(start, this);
1926 
1927   // This operation might block. We call that after all safepoint checks for a new thread has
1928   // been completed.
1929   this->set_active_handles(JNIHandleBlock::allocate_block());
1930 
1931   if (JvmtiExport::should_post_thread_life()) {
1932     JvmtiExport::post_thread_start(this);
1933 
1934   }
1935 
1936   // We call another function to do the rest so we are sure that the stack addresses used
1937   // from there will be lower than the stack base just computed.
1938   thread_main_inner();
1939 }
1940 
1941 void JavaThread::thread_main_inner() {
1942   assert(JavaThread::current() == this, "sanity check");
1943   assert(this->threadObj() != NULL, "just checking");
1944 
1945   // Execute thread entry point unless this thread has a pending exception
1946   // or has been stopped before starting.
1947   // Note: Due to JVM_StopThread we can have pending exceptions already!
1948   if (!this->has_pending_exception() &&
1949       !java_lang_Thread::is_stillborn(this->threadObj())) {
1950     {
1951       ResourceMark rm(this);
1952       this->set_native_thread_name(this->get_thread_name());
1953     }
1954     HandleMark hm(this);
1955     this->entry_point()(this, this);
1956   }
1957 
1958   DTRACE_THREAD_PROBE(stop, this);
1959 
1960   // Cleanup is handled in post_run()
1961 }
1962 
1963 // Shared teardown for all JavaThreads
1964 void JavaThread::post_run() {
1965   this->exit(false);
1966   // Defer deletion to here to ensure 'this' is still referenceable in call_run
1967   // for any shared tear-down.
1968   this->smr_delete();
1969 }
1970 
1971 static void ensure_join(JavaThread* thread) {
1972   // We do not need to grab the Threads_lock, since we are operating on ourself.
1973   Handle threadObj(thread, thread->threadObj());
1974   assert(threadObj.not_null(), "java thread object must exist");
1975   ObjectLocker lock(threadObj, thread);
1976   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1977   thread->clear_pending_exception();
1978   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1979   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1980   // Clear the native thread instance - this makes isAlive return false and allows the join()
1981   // to complete once we've done the notify_all below
1982   java_lang_Thread::set_thread(threadObj(), NULL);
1983   lock.notify_all(thread);
1984   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1985   thread->clear_pending_exception();
1986 }
1987 
1988 static bool is_daemon(oop threadObj) {
1989   return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj));
1990 }
1991 
1992 // For any new cleanup additions, please check to see if they need to be applied to
1993 // cleanup_failed_attach_current_thread as well.
1994 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1995   assert(this == JavaThread::current(), "thread consistency check");
1996 
1997   elapsedTimer _timer_exit_phase1;
1998   elapsedTimer _timer_exit_phase2;
1999   elapsedTimer _timer_exit_phase3;
2000   elapsedTimer _timer_exit_phase4;
2001 
2002   if (log_is_enabled(Debug, os, thread, timer)) {
2003     _timer_exit_phase1.start();
2004   }
2005 
2006   HandleMark hm(this);
2007   Handle uncaught_exception(this, this->pending_exception());
2008   this->clear_pending_exception();
2009   Handle threadObj(this, this->threadObj());
2010   assert(threadObj.not_null(), "Java thread object should be created");
2011 
2012   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
2013   {
2014     EXCEPTION_MARK;
2015 
2016     CLEAR_PENDING_EXCEPTION;
2017   }
2018   if (!destroy_vm) {
2019     if (uncaught_exception.not_null()) {
2020       EXCEPTION_MARK;
2021       // Call method Thread.dispatchUncaughtException().
2022       Klass* thread_klass = SystemDictionary::Thread_klass();
2023       JavaValue result(T_VOID);
2024       JavaCalls::call_virtual(&result,
2025                               threadObj, thread_klass,
2026                               vmSymbols::dispatchUncaughtException_name(),
2027                               vmSymbols::throwable_void_signature(),
2028                               uncaught_exception,
2029                               THREAD);
2030       if (HAS_PENDING_EXCEPTION) {
2031         ResourceMark rm(this);
2032         jio_fprintf(defaultStream::error_stream(),
2033                     "\nException: %s thrown from the UncaughtExceptionHandler"
2034                     " in thread \"%s\"\n",
2035                     pending_exception()->klass()->external_name(),
2036                     get_thread_name());
2037         CLEAR_PENDING_EXCEPTION;
2038       }
2039     }
2040     JFR_ONLY(Jfr::on_java_thread_dismantle(this);)
2041 
2042     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
2043     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
2044     // is deprecated anyhow.
2045     if (!is_Compiler_thread()) {
2046       int count = 3;
2047       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
2048         EXCEPTION_MARK;
2049         JavaValue result(T_VOID);
2050         Klass* thread_klass = SystemDictionary::Thread_klass();
2051         JavaCalls::call_virtual(&result,
2052                                 threadObj, thread_klass,
2053                                 vmSymbols::exit_method_name(),
2054                                 vmSymbols::void_method_signature(),
2055                                 THREAD);
2056         CLEAR_PENDING_EXCEPTION;
2057       }
2058     }
2059     // notify JVMTI
2060     if (JvmtiExport::should_post_thread_life()) {
2061       JvmtiExport::post_thread_end(this);
2062     }
2063 
2064     // We have notified the agents that we are exiting, before we go on,
2065     // we must check for a pending external suspend request and honor it
2066     // in order to not surprise the thread that made the suspend request.
2067     while (true) {
2068       {
2069         MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2070         if (!is_external_suspend()) {
2071           set_terminated(_thread_exiting);
2072           ThreadService::current_thread_exiting(this, is_daemon(threadObj()));
2073           break;
2074         }
2075         // Implied else:
2076         // Things get a little tricky here. We have a pending external
2077         // suspend request, but we are holding the SR_lock so we
2078         // can't just self-suspend. So we temporarily drop the lock
2079         // and then self-suspend.
2080       }
2081 
2082       ThreadBlockInVM tbivm(this);
2083       java_suspend_self();
2084 
2085       // We're done with this suspend request, but we have to loop around
2086       // and check again. Eventually we will get SR_lock without a pending
2087       // external suspend request and will be able to mark ourselves as
2088       // exiting.
2089     }
2090     // no more external suspends are allowed at this point
2091   } else {
2092     assert(!is_terminated() && !is_exiting(), "must not be exiting");
2093     // before_exit() has already posted JVMTI THREAD_END events
2094   }
2095 
2096   if (log_is_enabled(Debug, os, thread, timer)) {
2097     _timer_exit_phase1.stop();
2098     _timer_exit_phase2.start();
2099   }
2100 
2101   // Capture daemon status before the thread is marked as terminated.
2102   bool daemon = is_daemon(threadObj());
2103 
2104   // Notify waiters on thread object. This has to be done after exit() is called
2105   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
2106   // group should have the destroyed bit set before waiters are notified).
2107   ensure_join(this);
2108   assert(!this->has_pending_exception(), "ensure_join should have cleared");
2109 
2110   if (log_is_enabled(Debug, os, thread, timer)) {
2111     _timer_exit_phase2.stop();
2112     _timer_exit_phase3.start();
2113   }
2114   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
2115   // held by this thread must be released. The spec does not distinguish
2116   // between JNI-acquired and regular Java monitors. We can only see
2117   // regular Java monitors here if monitor enter-exit matching is broken.
2118   //
2119   // ensure_join() ignores IllegalThreadStateExceptions, and so does
2120   // ObjectSynchronizer::release_monitors_owned_by_thread().
2121   if (exit_type == jni_detach) {
2122     // Sanity check even though JNI DetachCurrentThread() would have
2123     // returned JNI_ERR if there was a Java frame. JavaThread exit
2124     // should be done executing Java code by the time we get here.
2125     assert(!this->has_last_Java_frame(),
2126            "should not have a Java frame when detaching or exiting");
2127     ObjectSynchronizer::release_monitors_owned_by_thread(this);
2128     assert(!this->has_pending_exception(), "release_monitors should have cleared");
2129   }
2130 
2131   // These things needs to be done while we are still a Java Thread. Make sure that thread
2132   // is in a consistent state, in case GC happens
2133   JFR_ONLY(Jfr::on_thread_exit(this);)
2134 
2135   if (active_handles() != NULL) {
2136     JNIHandleBlock* block = active_handles();
2137     set_active_handles(NULL);
2138     JNIHandleBlock::release_block(block);
2139   }
2140 
2141   if (free_handle_block() != NULL) {
2142     JNIHandleBlock* block = free_handle_block();
2143     set_free_handle_block(NULL);
2144     JNIHandleBlock::release_block(block);
2145   }
2146 
2147   // These have to be removed while this is still a valid thread.
2148   remove_stack_guard_pages();
2149 
2150   if (UseTLAB) {
2151     tlab().retire();
2152   }
2153 
2154   if (JvmtiEnv::environments_might_exist()) {
2155     JvmtiExport::cleanup_thread(this);
2156   }
2157 
2158   // We must flush any deferred card marks and other various GC barrier
2159   // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
2160   // before removing a thread from the list of active threads.
2161   BarrierSet::barrier_set()->on_thread_detach(this);
2162 
2163   log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2164     exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2165     os::current_thread_id());
2166 
2167   if (log_is_enabled(Debug, os, thread, timer)) {
2168     _timer_exit_phase3.stop();
2169     _timer_exit_phase4.start();
2170   }
2171   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2172   Threads::remove(this, daemon);
2173 
2174   if (log_is_enabled(Debug, os, thread, timer)) {
2175     _timer_exit_phase4.stop();
2176     ResourceMark rm(this);
2177     log_debug(os, thread, timer)("name='%s'"
2178                                  ", exit-phase1=" JLONG_FORMAT
2179                                  ", exit-phase2=" JLONG_FORMAT
2180                                  ", exit-phase3=" JLONG_FORMAT
2181                                  ", exit-phase4=" JLONG_FORMAT,
2182                                  get_thread_name(),
2183                                  _timer_exit_phase1.milliseconds(),
2184                                  _timer_exit_phase2.milliseconds(),
2185                                  _timer_exit_phase3.milliseconds(),
2186                                  _timer_exit_phase4.milliseconds());
2187   }
2188 }
2189 
2190 void JavaThread::cleanup_failed_attach_current_thread(bool is_daemon) {
2191   if (active_handles() != NULL) {
2192     JNIHandleBlock* block = active_handles();
2193     set_active_handles(NULL);
2194     JNIHandleBlock::release_block(block);
2195   }
2196 
2197   if (free_handle_block() != NULL) {
2198     JNIHandleBlock* block = free_handle_block();
2199     set_free_handle_block(NULL);
2200     JNIHandleBlock::release_block(block);
2201   }
2202 
2203   // These have to be removed while this is still a valid thread.
2204   remove_stack_guard_pages();
2205 
2206   if (UseTLAB) {
2207     tlab().retire();
2208   }
2209 
2210   BarrierSet::barrier_set()->on_thread_detach(this);
2211 
2212   Threads::remove(this, is_daemon);
2213   this->smr_delete();
2214 }
2215 
2216 JavaThread* JavaThread::active() {
2217   Thread* thread = Thread::current();
2218   if (thread->is_Java_thread()) {
2219     return (JavaThread*) thread;
2220   } else {
2221     assert(thread->is_VM_thread(), "this must be a vm thread");
2222     VM_Operation* op = ((VMThread*) thread)->vm_operation();
2223     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2224     assert(ret->is_Java_thread(), "must be a Java thread");
2225     return ret;
2226   }
2227 }
2228 
2229 bool JavaThread::is_lock_owned(address adr) const {
2230   if (Thread::is_lock_owned(adr)) return true;
2231 
2232   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2233     if (chunk->contains(adr)) return true;
2234   }
2235 
2236   return false;
2237 }
2238 
2239 
2240 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2241   chunk->set_next(monitor_chunks());
2242   set_monitor_chunks(chunk);
2243 }
2244 
2245 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2246   guarantee(monitor_chunks() != NULL, "must be non empty");
2247   if (monitor_chunks() == chunk) {
2248     set_monitor_chunks(chunk->next());
2249   } else {
2250     MonitorChunk* prev = monitor_chunks();
2251     while (prev->next() != chunk) prev = prev->next();
2252     prev->set_next(chunk->next());
2253   }
2254 }
2255 
2256 // JVM support.
2257 
2258 // Note: this function shouldn't block if it's called in
2259 // _thread_in_native_trans state (such as from
2260 // check_special_condition_for_native_trans()).
2261 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2262 
2263   if (has_last_Java_frame() && has_async_condition()) {
2264     // If we are at a polling page safepoint (not a poll return)
2265     // then we must defer async exception because live registers
2266     // will be clobbered by the exception path. Poll return is
2267     // ok because the call we a returning from already collides
2268     // with exception handling registers and so there is no issue.
2269     // (The exception handling path kills call result registers but
2270     //  this is ok since the exception kills the result anyway).
2271 
2272     if (is_at_poll_safepoint()) {
2273       // if the code we are returning to has deoptimized we must defer
2274       // the exception otherwise live registers get clobbered on the
2275       // exception path before deoptimization is able to retrieve them.
2276       //
2277       RegisterMap map(this, false);
2278       frame caller_fr = last_frame().sender(&map);
2279       assert(caller_fr.is_compiled_frame(), "what?");
2280       if (caller_fr.is_deoptimized_frame()) {
2281         log_info(exceptions)("deferred async exception at compiled safepoint");
2282         return;
2283       }
2284     }
2285   }
2286 
2287   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2288   if (condition == _no_async_condition) {
2289     // Conditions have changed since has_special_runtime_exit_condition()
2290     // was called:
2291     // - if we were here only because of an external suspend request,
2292     //   then that was taken care of above (or cancelled) so we are done
2293     // - if we were here because of another async request, then it has
2294     //   been cleared between the has_special_runtime_exit_condition()
2295     //   and now so again we are done
2296     return;
2297   }
2298 
2299   // Check for pending async. exception
2300   if (_pending_async_exception != NULL) {
2301     // Only overwrite an already pending exception, if it is not a threadDeath.
2302     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2303 
2304       // We cannot call Exceptions::_throw(...) here because we cannot block
2305       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2306 
2307       LogTarget(Info, exceptions) lt;
2308       if (lt.is_enabled()) {
2309         ResourceMark rm;
2310         LogStream ls(lt);
2311         ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2312           if (has_last_Java_frame()) {
2313             frame f = last_frame();
2314            ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2315           }
2316         ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2317       }
2318       _pending_async_exception = NULL;
2319       clear_has_async_exception();
2320     }
2321   }
2322 
2323   if (check_unsafe_error &&
2324       condition == _async_unsafe_access_error && !has_pending_exception()) {
2325     condition = _no_async_condition;  // done
2326     switch (thread_state()) {
2327     case _thread_in_vm: {
2328       JavaThread* THREAD = this;
2329       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2330     }
2331     case _thread_in_native: {
2332       ThreadInVMfromNative tiv(this);
2333       JavaThread* THREAD = this;
2334       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2335     }
2336     case _thread_in_Java: {
2337       ThreadInVMfromJava tiv(this);
2338       JavaThread* THREAD = this;
2339       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2340     }
2341     default:
2342       ShouldNotReachHere();
2343     }
2344   }
2345 
2346   assert(condition == _no_async_condition || has_pending_exception() ||
2347          (!check_unsafe_error && condition == _async_unsafe_access_error),
2348          "must have handled the async condition, if no exception");
2349 }
2350 
2351 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2352 
2353   // Check for pending external suspend.
2354   if (is_external_suspend_with_lock()) {
2355     frame_anchor()->make_walkable(this);
2356     java_suspend_self_with_safepoint_check();
2357   }
2358 
2359   // We might be here for reasons in addition to the self-suspend request
2360   // so check for other async requests.
2361   if (check_asyncs) {
2362     check_and_handle_async_exceptions();
2363   }
2364 
2365   JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
2366 }
2367 
2368 void JavaThread::send_thread_stop(oop java_throwable)  {
2369   assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2370   assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2371   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2372 
2373   // Do not throw asynchronous exceptions against the compiler thread
2374   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2375   if (!can_call_java()) return;
2376 
2377   {
2378     // Actually throw the Throwable against the target Thread - however
2379     // only if there is no thread death exception installed already.
2380     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2381       // If the topmost frame is a runtime stub, then we are calling into
2382       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2383       // must deoptimize the caller before continuing, as the compiled  exception handler table
2384       // may not be valid
2385       if (has_last_Java_frame()) {
2386         frame f = last_frame();
2387         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2388           // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2389           RegisterMap reg_map(this, UseBiasedLocking);
2390           frame compiled_frame = f.sender(&reg_map);
2391           if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2392             Deoptimization::deoptimize(this, compiled_frame, &reg_map);
2393           }
2394         }
2395       }
2396 
2397       // Set async. pending exception in thread.
2398       set_pending_async_exception(java_throwable);
2399 
2400       if (log_is_enabled(Info, exceptions)) {
2401          ResourceMark rm;
2402         log_info(exceptions)("Pending Async. exception installed of type: %s",
2403                              InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2404       }
2405       // for AbortVMOnException flag
2406       Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2407     }
2408   }
2409 
2410 
2411   // Interrupt thread so it will wake up from a potential wait()
2412   Thread::interrupt(this);
2413 }
2414 
2415 // External suspension mechanism.
2416 //
2417 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2418 // to any VM_locks and it is at a transition
2419 // Self-suspension will happen on the transition out of the vm.
2420 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2421 //
2422 // Guarantees on return:
2423 //   + Target thread will not execute any new bytecode (that's why we need to
2424 //     force a safepoint)
2425 //   + Target thread will not enter any new monitors
2426 //
2427 void JavaThread::java_suspend() {
2428   ThreadsListHandle tlh;
2429   if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2430     return;
2431   }
2432 
2433   { MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2434     if (!is_external_suspend()) {
2435       // a racing resume has cancelled us; bail out now
2436       return;
2437     }
2438 
2439     // suspend is done
2440     uint32_t debug_bits = 0;
2441     // Warning: is_ext_suspend_completed() may temporarily drop the
2442     // SR_lock to allow the thread to reach a stable thread state if
2443     // it is currently in a transient thread state.
2444     if (is_ext_suspend_completed(false /* !called_by_wait */,
2445                                  SuspendRetryDelay, &debug_bits)) {
2446       return;
2447     }
2448   }
2449 
2450   if (Thread::current() == this) {
2451     // Safely self-suspend.
2452     // If we don't do this explicitly it will implicitly happen
2453     // before we transition back to Java, and on some other thread-state
2454     // transition paths, but not as we exit a JVM TI SuspendThread call.
2455     // As SuspendThread(current) must not return (until resumed) we must
2456     // self-suspend here.
2457     ThreadBlockInVM tbivm(this);
2458     java_suspend_self();
2459   } else {
2460     VM_ThreadSuspend vm_suspend;
2461     VMThread::execute(&vm_suspend);
2462   }
2463 }
2464 
2465 // Part II of external suspension.
2466 // A JavaThread self suspends when it detects a pending external suspend
2467 // request. This is usually on transitions. It is also done in places
2468 // where continuing to the next transition would surprise the caller,
2469 // e.g., monitor entry.
2470 //
2471 // Returns the number of times that the thread self-suspended.
2472 //
2473 // Note: DO NOT call java_suspend_self() when you just want to block current
2474 //       thread. java_suspend_self() is the second stage of cooperative
2475 //       suspension for external suspend requests and should only be used
2476 //       to complete an external suspend request.
2477 //
2478 int JavaThread::java_suspend_self() {
2479   assert(thread_state() == _thread_blocked, "wrong state for java_suspend_self()");
2480   int ret = 0;
2481 
2482   // we are in the process of exiting so don't suspend
2483   if (is_exiting()) {
2484     clear_external_suspend();
2485     return ret;
2486   }
2487 
2488   assert(_anchor.walkable() ||
2489          (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2490          "must have walkable stack");
2491 
2492   MonitorLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2493 
2494   assert(!this->is_ext_suspended(),
2495          "a thread trying to self-suspend should not already be suspended");
2496 
2497   if (this->is_suspend_equivalent()) {
2498     // If we are self-suspending as a result of the lifting of a
2499     // suspend equivalent condition, then the suspend_equivalent
2500     // flag is not cleared until we set the ext_suspended flag so
2501     // that wait_for_ext_suspend_completion() returns consistent
2502     // results.
2503     this->clear_suspend_equivalent();
2504   }
2505 
2506   // A racing resume may have cancelled us before we grabbed SR_lock
2507   // above. Or another external suspend request could be waiting for us
2508   // by the time we return from SR_lock()->wait(). The thread
2509   // that requested the suspension may already be trying to walk our
2510   // stack and if we return now, we can change the stack out from under
2511   // it. This would be a "bad thing (TM)" and cause the stack walker
2512   // to crash. We stay self-suspended until there are no more pending
2513   // external suspend requests.
2514   while (is_external_suspend()) {
2515     ret++;
2516     this->set_ext_suspended();
2517 
2518     // _ext_suspended flag is cleared by java_resume()
2519     while (is_ext_suspended()) {
2520       ml.wait();
2521     }
2522   }
2523   return ret;
2524 }
2525 
2526 // Helper routine to set up the correct thread state before calling java_suspend_self.
2527 // This is called when regular thread-state transition helpers can't be used because
2528 // we can be in various states, in particular _thread_in_native_trans.
2529 // Because this thread is external suspended the safepoint code will count it as at
2530 // a safepoint, regardless of what its actual current thread-state is. But
2531 // is_ext_suspend_completed() may be waiting to see a thread transition from
2532 // _thread_in_native_trans to _thread_blocked. So we set the thread state directly
2533 // to _thread_blocked. The problem with setting thread state directly is that a
2534 // safepoint could happen just after java_suspend_self() returns after being resumed,
2535 // and the VM thread will see the _thread_blocked state. So we must check for a safepoint
2536 // after restoring the state to make sure we won't leave while a safepoint is in progress.
2537 // However, not all initial-states are allowed when performing a safepoint check, as we
2538 // should never be blocking at a safepoint whilst in those states. Of these 'bad' states
2539 // only _thread_in_native is possible when executing this code (based on our two callers).
2540 // A thread that is _thread_in_native is already safepoint-safe and so it doesn't matter
2541 // whether the VMThread sees the _thread_blocked state, or the _thread_in_native state,
2542 // and so we don't need the explicit safepoint check.
2543 
2544 void JavaThread::java_suspend_self_with_safepoint_check() {
2545   assert(this == Thread::current(), "invariant");
2546   JavaThreadState state = thread_state();
2547   set_thread_state(_thread_blocked);
2548   java_suspend_self();
2549   set_thread_state_fence(state);
2550   // Since we are not using a regular thread-state transition helper here,
2551   // we must manually emit the instruction barrier after leaving a safe state.
2552   OrderAccess::cross_modify_fence();
2553   if (state != _thread_in_native) {
2554     SafepointMechanism::block_if_requested(this);
2555   }
2556 }
2557 
2558 #ifdef ASSERT
2559 // Verify the JavaThread has not yet been published in the Threads::list, and
2560 // hence doesn't need protection from concurrent access at this stage.
2561 void JavaThread::verify_not_published() {
2562   // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
2563   // since an unpublished JavaThread doesn't participate in the
2564   // Thread-SMR protocol for keeping a ThreadsList alive.
2565   assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
2566 }
2567 #endif
2568 
2569 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2570 // progress or when _suspend_flags is non-zero.
2571 // Current thread needs to self-suspend if there is a suspend request and/or
2572 // block if a safepoint is in progress.
2573 // Async exception ISN'T checked.
2574 // Note only the ThreadInVMfromNative transition can call this function
2575 // directly and when thread state is _thread_in_native_trans
2576 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2577   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2578 
2579   assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2580 
2581   if (thread->is_external_suspend()) {
2582     thread->java_suspend_self_with_safepoint_check();
2583   } else {
2584     SafepointMechanism::block_if_requested(thread);
2585   }
2586 
2587   JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);)
2588 }
2589 
2590 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2591 // progress or when _suspend_flags is non-zero.
2592 // Current thread needs to self-suspend if there is a suspend request and/or
2593 // block if a safepoint is in progress.
2594 // Also check for pending async exception (not including unsafe access error).
2595 // Note only the native==>VM/Java barriers can call this function and when
2596 // thread state is _thread_in_native_trans.
2597 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2598   check_safepoint_and_suspend_for_native_trans(thread);
2599 
2600   if (thread->has_async_exception()) {
2601     // We are in _thread_in_native_trans state, don't handle unsafe
2602     // access error since that may block.
2603     thread->check_and_handle_async_exceptions(false);
2604   }
2605 }
2606 
2607 // This is a variant of the normal
2608 // check_special_condition_for_native_trans with slightly different
2609 // semantics for use by critical native wrappers.  It does all the
2610 // normal checks but also performs the transition back into
2611 // thread_in_Java state.  This is required so that critical natives
2612 // can potentially block and perform a GC if they are the last thread
2613 // exiting the GCLocker.
2614 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2615   check_special_condition_for_native_trans(thread);
2616 
2617   // Finish the transition
2618   thread->set_thread_state(_thread_in_Java);
2619 
2620   if (thread->do_critical_native_unlock()) {
2621     ThreadInVMfromJavaNoAsyncException tiv(thread);
2622     GCLocker::unlock_critical(thread);
2623     thread->clear_critical_native_unlock();
2624   }
2625 }
2626 
2627 // We need to guarantee the Threads_lock here, since resumes are not
2628 // allowed during safepoint synchronization
2629 // Can only resume from an external suspension
2630 void JavaThread::java_resume() {
2631   assert_locked_or_safepoint(Threads_lock);
2632 
2633   // Sanity check: thread is gone, has started exiting or the thread
2634   // was not externally suspended.
2635   ThreadsListHandle tlh;
2636   if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2637     return;
2638   }
2639 
2640   MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2641 
2642   clear_external_suspend();
2643 
2644   if (is_ext_suspended()) {
2645     clear_ext_suspended();
2646     SR_lock()->notify_all();
2647   }
2648 }
2649 
2650 size_t JavaThread::_stack_red_zone_size = 0;
2651 size_t JavaThread::_stack_yellow_zone_size = 0;
2652 size_t JavaThread::_stack_reserved_zone_size = 0;
2653 size_t JavaThread::_stack_shadow_zone_size = 0;
2654 
2655 void JavaThread::create_stack_guard_pages() {
2656   if (!os::uses_stack_guard_pages() ||
2657       _stack_guard_state != stack_guard_unused ||
2658       (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2659       log_info(os, thread)("Stack guard page creation for thread "
2660                            UINTX_FORMAT " disabled", os::current_thread_id());
2661     return;
2662   }
2663   address low_addr = stack_end();
2664   size_t len = stack_guard_zone_size();
2665 
2666   assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2667   assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2668 
2669   int must_commit = os::must_commit_stack_guard_pages();
2670   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2671 
2672   if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2673     log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2674     return;
2675   }
2676 
2677   if (os::guard_memory((char *) low_addr, len)) {
2678     _stack_guard_state = stack_guard_enabled;
2679   } else {
2680     log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2681       PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2682     if (os::uncommit_memory((char *) low_addr, len)) {
2683       log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2684     }
2685     return;
2686   }
2687 
2688   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2689     PTR_FORMAT "-" PTR_FORMAT ".",
2690     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2691 }
2692 
2693 void JavaThread::remove_stack_guard_pages() {
2694   assert(Thread::current() == this, "from different thread");
2695   if (_stack_guard_state == stack_guard_unused) return;
2696   address low_addr = stack_end();
2697   size_t len = stack_guard_zone_size();
2698 
2699   if (os::must_commit_stack_guard_pages()) {
2700     if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2701       _stack_guard_state = stack_guard_unused;
2702     } else {
2703       log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2704         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2705       return;
2706     }
2707   } else {
2708     if (_stack_guard_state == stack_guard_unused) return;
2709     if (os::unguard_memory((char *) low_addr, len)) {
2710       _stack_guard_state = stack_guard_unused;
2711     } else {
2712       log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2713         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2714       return;
2715     }
2716   }
2717 
2718   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2719     PTR_FORMAT "-" PTR_FORMAT ".",
2720     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2721 }
2722 
2723 void JavaThread::enable_stack_reserved_zone() {
2724   assert(_stack_guard_state == stack_guard_reserved_disabled, "inconsistent state");
2725 
2726   // The base notation is from the stack's point of view, growing downward.
2727   // We need to adjust it to work correctly with guard_memory()
2728   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2729 
2730   guarantee(base < stack_base(),"Error calculating stack reserved zone");
2731   guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2732 
2733   if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2734     _stack_guard_state = stack_guard_enabled;
2735   } else {
2736     warning("Attempt to guard stack reserved zone failed.");
2737   }
2738   enable_register_stack_guard();
2739 }
2740 
2741 void JavaThread::disable_stack_reserved_zone() {
2742   assert(_stack_guard_state == stack_guard_enabled, "inconsistent state");
2743 
2744   // Simply return if called for a thread that does not use guard pages.
2745   if (_stack_guard_state != stack_guard_enabled) return;
2746 
2747   // The base notation is from the stack's point of view, growing downward.
2748   // We need to adjust it to work correctly with guard_memory()
2749   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2750 
2751   if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2752     _stack_guard_state = stack_guard_reserved_disabled;
2753   } else {
2754     warning("Attempt to unguard stack reserved zone failed.");
2755   }
2756   disable_register_stack_guard();
2757 }
2758 
2759 void JavaThread::enable_stack_yellow_reserved_zone() {
2760   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2761   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2762 
2763   // The base notation is from the stacks point of view, growing downward.
2764   // We need to adjust it to work correctly with guard_memory()
2765   address base = stack_red_zone_base();
2766 
2767   guarantee(base < stack_base(), "Error calculating stack yellow zone");
2768   guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2769 
2770   if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2771     _stack_guard_state = stack_guard_enabled;
2772   } else {
2773     warning("Attempt to guard stack yellow zone failed.");
2774   }
2775   enable_register_stack_guard();
2776 }
2777 
2778 void JavaThread::disable_stack_yellow_reserved_zone() {
2779   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2780   assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2781 
2782   // Simply return if called for a thread that does not use guard pages.
2783   if (_stack_guard_state == stack_guard_unused) return;
2784 
2785   // The base notation is from the stacks point of view, growing downward.
2786   // We need to adjust it to work correctly with guard_memory()
2787   address base = stack_red_zone_base();
2788 
2789   if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2790     _stack_guard_state = stack_guard_yellow_reserved_disabled;
2791   } else {
2792     warning("Attempt to unguard stack yellow zone failed.");
2793   }
2794   disable_register_stack_guard();
2795 }
2796 
2797 void JavaThread::enable_stack_red_zone() {
2798   // The base notation is from the stacks point of view, growing downward.
2799   // We need to adjust it to work correctly with guard_memory()
2800   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2801   address base = stack_red_zone_base() - stack_red_zone_size();
2802 
2803   guarantee(base < stack_base(), "Error calculating stack red zone");
2804   guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2805 
2806   if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2807     warning("Attempt to guard stack red zone failed.");
2808   }
2809 }
2810 
2811 void JavaThread::disable_stack_red_zone() {
2812   // The base notation is from the stacks point of view, growing downward.
2813   // We need to adjust it to work correctly with guard_memory()
2814   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2815   address base = stack_red_zone_base() - stack_red_zone_size();
2816   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2817     warning("Attempt to unguard stack red zone failed.");
2818   }
2819 }
2820 
2821 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2822   // ignore is there is no stack
2823   if (!has_last_Java_frame()) return;
2824   // traverse the stack frames. Starts from top frame.
2825   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2826     frame* fr = fst.current();
2827     f(fr, fst.register_map());
2828   }
2829 }
2830 
2831 
2832 #ifndef PRODUCT
2833 // Deoptimization
2834 // Function for testing deoptimization
2835 void JavaThread::deoptimize() {
2836   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2837   StackFrameStream fst(this, UseBiasedLocking);
2838   bool deopt = false;           // Dump stack only if a deopt actually happens.
2839   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2840   // Iterate over all frames in the thread and deoptimize
2841   for (; !fst.is_done(); fst.next()) {
2842     if (fst.current()->can_be_deoptimized()) {
2843 
2844       if (only_at) {
2845         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
2846         // consists of comma or carriage return separated numbers so
2847         // search for the current bci in that string.
2848         address pc = fst.current()->pc();
2849         nmethod* nm =  (nmethod*) fst.current()->cb();
2850         ScopeDesc* sd = nm->scope_desc_at(pc);
2851         char buffer[8];
2852         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2853         size_t len = strlen(buffer);
2854         const char * found = strstr(DeoptimizeOnlyAt, buffer);
2855         while (found != NULL) {
2856           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2857               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2858             // Check that the bci found is bracketed by terminators.
2859             break;
2860           }
2861           found = strstr(found + 1, buffer);
2862         }
2863         if (!found) {
2864           continue;
2865         }
2866       }
2867 
2868       if (DebugDeoptimization && !deopt) {
2869         deopt = true; // One-time only print before deopt
2870         tty->print_cr("[BEFORE Deoptimization]");
2871         trace_frames();
2872         trace_stack();
2873       }
2874       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2875     }
2876   }
2877 
2878   if (DebugDeoptimization && deopt) {
2879     tty->print_cr("[AFTER Deoptimization]");
2880     trace_frames();
2881   }
2882 }
2883 
2884 
2885 // Make zombies
2886 void JavaThread::make_zombies() {
2887   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2888     if (fst.current()->can_be_deoptimized()) {
2889       // it is a Java nmethod
2890       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2891       nm->make_not_entrant();
2892     }
2893   }
2894 }
2895 #endif // PRODUCT
2896 
2897 
2898 void JavaThread::deoptimized_wrt_marked_nmethods() {
2899   if (!has_last_Java_frame()) return;
2900   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2901   StackFrameStream fst(this, UseBiasedLocking);
2902   for (; !fst.is_done(); fst.next()) {
2903     if (fst.current()->should_be_deoptimized()) {
2904       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2905     }
2906   }
2907 }
2908 
2909 
2910 // If the caller is a NamedThread, then remember, in the current scope,
2911 // the given JavaThread in its _processed_thread field.
2912 class RememberProcessedThread: public StackObj {
2913   NamedThread* _cur_thr;
2914  public:
2915   RememberProcessedThread(JavaThread* jthr) {
2916     Thread* thread = Thread::current();
2917     if (thread->is_Named_thread()) {
2918       _cur_thr = (NamedThread *)thread;
2919       _cur_thr->set_processed_thread(jthr);
2920     } else {
2921       _cur_thr = NULL;
2922     }
2923   }
2924 
2925   ~RememberProcessedThread() {
2926     if (_cur_thr) {
2927       _cur_thr->set_processed_thread(NULL);
2928     }
2929   }
2930 };
2931 
2932 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2933   // Verify that the deferred card marks have been flushed.
2934   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2935 
2936   // Traverse the GCHandles
2937   Thread::oops_do(f, cf);
2938 
2939   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2940          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2941 
2942   if (has_last_Java_frame()) {
2943     // Record JavaThread to GC thread
2944     RememberProcessedThread rpt(this);
2945 
2946     // traverse the registered growable array
2947     if (_array_for_gc != NULL) {
2948       for (int index = 0; index < _array_for_gc->length(); index++) {
2949         f->do_oop(_array_for_gc->adr_at(index));
2950       }
2951     }
2952 
2953     // Traverse the monitor chunks
2954     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2955       chunk->oops_do(f);
2956     }
2957 
2958     // Traverse the execution stack
2959     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2960       fst.current()->oops_do(f, cf, fst.register_map());
2961     }
2962   }
2963 
2964   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2965   // If we have deferred set_locals there might be oops waiting to be
2966   // written
2967   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2968   if (list != NULL) {
2969     for (int i = 0; i < list->length(); i++) {
2970       list->at(i)->oops_do(f);
2971     }
2972   }
2973 
2974   // Traverse instance variables at the end since the GC may be moving things
2975   // around using this function
2976   f->do_oop((oop*) &_threadObj);
2977   f->do_oop((oop*) &_vm_result);
2978   f->do_oop((oop*) &_exception_oop);
2979   f->do_oop((oop*) &_pending_async_exception);
2980 
2981   if (jvmti_thread_state() != NULL) {
2982     jvmti_thread_state()->oops_do(f);
2983   }
2984 }
2985 
2986 #ifdef ASSERT
2987 void JavaThread::verify_states_for_handshake() {
2988   // This checks that the thread has a correct frame state during a handshake.
2989   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2990          (has_last_Java_frame() && java_call_counter() > 0),
2991          "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
2992          has_last_Java_frame(), java_call_counter());
2993 }
2994 #endif
2995 
2996 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2997   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2998          (has_last_Java_frame() && java_call_counter() > 0),
2999          "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
3000          has_last_Java_frame(), java_call_counter());
3001 
3002   if (has_last_Java_frame()) {
3003     // Traverse the execution stack
3004     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3005       fst.current()->nmethods_do(cf);
3006     }
3007   }
3008 }
3009 
3010 void JavaThread::metadata_do(MetadataClosure* f) {
3011   if (has_last_Java_frame()) {
3012     // Traverse the execution stack to call f() on the methods in the stack
3013     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3014       fst.current()->metadata_do(f);
3015     }
3016   } else if (is_Compiler_thread()) {
3017     // need to walk ciMetadata in current compile tasks to keep alive.
3018     CompilerThread* ct = (CompilerThread*)this;
3019     if (ct->env() != NULL) {
3020       ct->env()->metadata_do(f);
3021     }
3022     CompileTask* task = ct->task();
3023     if (task != NULL) {
3024       task->metadata_do(f);
3025     }
3026   }
3027 }
3028 
3029 // Printing
3030 const char* _get_thread_state_name(JavaThreadState _thread_state) {
3031   switch (_thread_state) {
3032   case _thread_uninitialized:     return "_thread_uninitialized";
3033   case _thread_new:               return "_thread_new";
3034   case _thread_new_trans:         return "_thread_new_trans";
3035   case _thread_in_native:         return "_thread_in_native";
3036   case _thread_in_native_trans:   return "_thread_in_native_trans";
3037   case _thread_in_vm:             return "_thread_in_vm";
3038   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
3039   case _thread_in_Java:           return "_thread_in_Java";
3040   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
3041   case _thread_blocked:           return "_thread_blocked";
3042   case _thread_blocked_trans:     return "_thread_blocked_trans";
3043   default:                        return "unknown thread state";
3044   }
3045 }
3046 
3047 #ifndef PRODUCT
3048 void JavaThread::print_thread_state_on(outputStream *st) const {
3049   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
3050 };
3051 void JavaThread::print_thread_state() const {
3052   print_thread_state_on(tty);
3053 }
3054 #endif // PRODUCT
3055 
3056 // Called by Threads::print() for VM_PrintThreads operation
3057 void JavaThread::print_on(outputStream *st, bool print_extended_info) const {
3058   st->print_raw("\"");
3059   st->print_raw(get_thread_name());
3060   st->print_raw("\" ");
3061   oop thread_oop = threadObj();
3062   if (thread_oop != NULL) {
3063     st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
3064     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
3065     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
3066   }
3067   Thread::print_on(st, print_extended_info);
3068   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
3069   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
3070   if (thread_oop != NULL) {
3071     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
3072   }
3073 #ifndef PRODUCT
3074   _safepoint_state->print_on(st);
3075 #endif // PRODUCT
3076   if (is_Compiler_thread()) {
3077     CompileTask *task = ((CompilerThread*)this)->task();
3078     if (task != NULL) {
3079       st->print("   Compiling: ");
3080       task->print(st, NULL, true, false);
3081     } else {
3082       st->print("   No compile task");
3083     }
3084     st->cr();
3085   }
3086 }
3087 
3088 void JavaThread::print() const { print_on(tty); }
3089 
3090 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
3091   st->print("%s", get_thread_name_string(buf, buflen));
3092 }
3093 
3094 // Called by fatal error handler. The difference between this and
3095 // JavaThread::print() is that we can't grab lock or allocate memory.
3096 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
3097   st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
3098   oop thread_obj = threadObj();
3099   if (thread_obj != NULL) {
3100     if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
3101   }
3102   st->print(" [");
3103   st->print("%s", _get_thread_state_name(_thread_state));
3104   if (osthread()) {
3105     st->print(", id=%d", osthread()->thread_id());
3106   }
3107   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
3108             p2i(stack_end()), p2i(stack_base()));
3109   st->print("]");
3110 
3111   ThreadsSMRSupport::print_info_on(this, st);
3112   return;
3113 }
3114 
3115 // Verification
3116 
3117 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3118 
3119 void JavaThread::verify() {
3120   // Verify oops in the thread.
3121   oops_do(&VerifyOopClosure::verify_oop, NULL);
3122 
3123   // Verify the stack frames.
3124   frames_do(frame_verify);
3125 }
3126 
3127 // CR 6300358 (sub-CR 2137150)
3128 // Most callers of this method assume that it can't return NULL but a
3129 // thread may not have a name whilst it is in the process of attaching to
3130 // the VM - see CR 6412693, and there are places where a JavaThread can be
3131 // seen prior to having it's threadObj set (eg JNI attaching threads and
3132 // if vm exit occurs during initialization). These cases can all be accounted
3133 // for such that this method never returns NULL.
3134 const char* JavaThread::get_thread_name() const {
3135 #ifdef ASSERT
3136   // early safepoints can hit while current thread does not yet have TLS
3137   if (!SafepointSynchronize::is_at_safepoint()) {
3138     Thread *cur = Thread::current();
3139     if (!(cur->is_Java_thread() && cur == this)) {
3140       // Current JavaThreads are allowed to get their own name without
3141       // the Threads_lock.
3142       assert_locked_or_safepoint(Threads_lock);
3143     }
3144   }
3145 #endif // ASSERT
3146   return get_thread_name_string();
3147 }
3148 
3149 // Returns a non-NULL representation of this thread's name, or a suitable
3150 // descriptive string if there is no set name
3151 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3152   const char* name_str;
3153   oop thread_obj = threadObj();
3154   if (thread_obj != NULL) {
3155     oop name = java_lang_Thread::name(thread_obj);
3156     if (name != NULL) {
3157       if (buf == NULL) {
3158         name_str = java_lang_String::as_utf8_string(name);
3159       } else {
3160         name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3161       }
3162     } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3163       name_str = "<no-name - thread is attaching>";
3164     } else {
3165       name_str = Thread::name();
3166     }
3167   } else {
3168     name_str = Thread::name();
3169   }
3170   assert(name_str != NULL, "unexpected NULL thread name");
3171   return name_str;
3172 }
3173 
3174 
3175 const char* JavaThread::get_threadgroup_name() const {
3176   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3177   oop thread_obj = threadObj();
3178   if (thread_obj != NULL) {
3179     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3180     if (thread_group != NULL) {
3181       // ThreadGroup.name can be null
3182       return java_lang_ThreadGroup::name(thread_group);
3183     }
3184   }
3185   return NULL;
3186 }
3187 
3188 const char* JavaThread::get_parent_name() const {
3189   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3190   oop thread_obj = threadObj();
3191   if (thread_obj != NULL) {
3192     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3193     if (thread_group != NULL) {
3194       oop parent = java_lang_ThreadGroup::parent(thread_group);
3195       if (parent != NULL) {
3196         // ThreadGroup.name can be null
3197         return java_lang_ThreadGroup::name(parent);
3198       }
3199     }
3200   }
3201   return NULL;
3202 }
3203 
3204 ThreadPriority JavaThread::java_priority() const {
3205   oop thr_oop = threadObj();
3206   if (thr_oop == NULL) return NormPriority; // Bootstrapping
3207   ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3208   assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3209   return priority;
3210 }
3211 
3212 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3213 
3214   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3215   // Link Java Thread object <-> C++ Thread
3216 
3217   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3218   // and put it into a new Handle.  The Handle "thread_oop" can then
3219   // be used to pass the C++ thread object to other methods.
3220 
3221   // Set the Java level thread object (jthread) field of the
3222   // new thread (a JavaThread *) to C++ thread object using the
3223   // "thread_oop" handle.
3224 
3225   // Set the thread field (a JavaThread *) of the
3226   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3227 
3228   Handle thread_oop(Thread::current(),
3229                     JNIHandles::resolve_non_null(jni_thread));
3230   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3231          "must be initialized");
3232   set_threadObj(thread_oop());
3233   java_lang_Thread::set_thread(thread_oop(), this);
3234 
3235   if (prio == NoPriority) {
3236     prio = java_lang_Thread::priority(thread_oop());
3237     assert(prio != NoPriority, "A valid priority should be present");
3238   }
3239 
3240   // Push the Java priority down to the native thread; needs Threads_lock
3241   Thread::set_priority(this, prio);
3242 
3243   // Add the new thread to the Threads list and set it in motion.
3244   // We must have threads lock in order to call Threads::add.
3245   // It is crucial that we do not block before the thread is
3246   // added to the Threads list for if a GC happens, then the java_thread oop
3247   // will not be visited by GC.
3248   Threads::add(this);
3249 }
3250 
3251 oop JavaThread::current_park_blocker() {
3252   // Support for JSR-166 locks
3253   oop thread_oop = threadObj();
3254   if (thread_oop != NULL) {
3255     return java_lang_Thread::park_blocker(thread_oop);
3256   }
3257   return NULL;
3258 }
3259 
3260 
3261 void JavaThread::print_stack_on(outputStream* st) {
3262   if (!has_last_Java_frame()) return;
3263   ResourceMark rm;
3264   HandleMark   hm;
3265 
3266   RegisterMap reg_map(this);
3267   vframe* start_vf = last_java_vframe(&reg_map);
3268   int count = 0;
3269   for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3270     if (f->is_java_frame()) {
3271       javaVFrame* jvf = javaVFrame::cast(f);
3272       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3273 
3274       // Print out lock information
3275       if (JavaMonitorsInStackTrace) {
3276         jvf->print_lock_info_on(st, count);
3277       }
3278     } else {
3279       // Ignore non-Java frames
3280     }
3281 
3282     // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3283     count++;
3284     if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3285   }
3286 }
3287 
3288 
3289 // JVMTI PopFrame support
3290 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3291   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3292   if (in_bytes(size_in_bytes) != 0) {
3293     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3294     _popframe_preserved_args_size = in_bytes(size_in_bytes);
3295     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3296   }
3297 }
3298 
3299 void* JavaThread::popframe_preserved_args() {
3300   return _popframe_preserved_args;
3301 }
3302 
3303 ByteSize JavaThread::popframe_preserved_args_size() {
3304   return in_ByteSize(_popframe_preserved_args_size);
3305 }
3306 
3307 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3308   int sz = in_bytes(popframe_preserved_args_size());
3309   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3310   return in_WordSize(sz / wordSize);
3311 }
3312 
3313 void JavaThread::popframe_free_preserved_args() {
3314   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3315   FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3316   _popframe_preserved_args = NULL;
3317   _popframe_preserved_args_size = 0;
3318 }
3319 
3320 #ifndef PRODUCT
3321 
3322 void JavaThread::trace_frames() {
3323   tty->print_cr("[Describe stack]");
3324   int frame_no = 1;
3325   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3326     tty->print("  %d. ", frame_no++);
3327     fst.current()->print_value_on(tty, this);
3328     tty->cr();
3329   }
3330 }
3331 
3332 class PrintAndVerifyOopClosure: public OopClosure {
3333  protected:
3334   template <class T> inline void do_oop_work(T* p) {
3335     oop obj = RawAccess<>::oop_load(p);
3336     if (obj == NULL) return;
3337     tty->print(INTPTR_FORMAT ": ", p2i(p));
3338     if (oopDesc::is_oop_or_null(obj)) {
3339       if (obj->is_objArray()) {
3340         tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3341       } else {
3342         obj->print();
3343       }
3344     } else {
3345       tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3346     }
3347     tty->cr();
3348   }
3349  public:
3350   virtual void do_oop(oop* p) { do_oop_work(p); }
3351   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
3352 };
3353 
3354 
3355 static void oops_print(frame* f, const RegisterMap *map) {
3356   PrintAndVerifyOopClosure print;
3357   f->print_value();
3358   f->oops_do(&print, NULL, (RegisterMap*)map);
3359 }
3360 
3361 // Print our all the locations that contain oops and whether they are
3362 // valid or not.  This useful when trying to find the oldest frame
3363 // where an oop has gone bad since the frame walk is from youngest to
3364 // oldest.
3365 void JavaThread::trace_oops() {
3366   tty->print_cr("[Trace oops]");
3367   frames_do(oops_print);
3368 }
3369 
3370 
3371 #ifdef ASSERT
3372 // Print or validate the layout of stack frames
3373 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3374   ResourceMark rm;
3375   PRESERVE_EXCEPTION_MARK;
3376   FrameValues values;
3377   int frame_no = 0;
3378   for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3379     fst.current()->describe(values, ++frame_no);
3380     if (depth == frame_no) break;
3381   }
3382   if (validate_only) {
3383     values.validate();
3384   } else {
3385     tty->print_cr("[Describe stack layout]");
3386     values.print(this);
3387   }
3388 }
3389 #endif
3390 
3391 void JavaThread::trace_stack_from(vframe* start_vf) {
3392   ResourceMark rm;
3393   int vframe_no = 1;
3394   for (vframe* f = start_vf; f; f = f->sender()) {
3395     if (f->is_java_frame()) {
3396       javaVFrame::cast(f)->print_activation(vframe_no++);
3397     } else {
3398       f->print();
3399     }
3400     if (vframe_no > StackPrintLimit) {
3401       tty->print_cr("...<more frames>...");
3402       return;
3403     }
3404   }
3405 }
3406 
3407 
3408 void JavaThread::trace_stack() {
3409   if (!has_last_Java_frame()) return;
3410   ResourceMark rm;
3411   HandleMark   hm;
3412   RegisterMap reg_map(this);
3413   trace_stack_from(last_java_vframe(&reg_map));
3414 }
3415 
3416 
3417 #endif // PRODUCT
3418 
3419 
3420 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3421   assert(reg_map != NULL, "a map must be given");
3422   frame f = last_frame();
3423   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3424     if (vf->is_java_frame()) return javaVFrame::cast(vf);
3425   }
3426   return NULL;
3427 }
3428 
3429 
3430 Klass* JavaThread::security_get_caller_class(int depth) {
3431   vframeStream vfst(this);
3432   vfst.security_get_caller_frame(depth);
3433   if (!vfst.at_end()) {
3434     return vfst.method()->method_holder();
3435   }
3436   return NULL;
3437 }
3438 
3439 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3440   assert(thread->is_Compiler_thread(), "must be compiler thread");
3441   CompileBroker::compiler_thread_loop();
3442 }
3443 
3444 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3445   NMethodSweeper::sweeper_loop();
3446 }
3447 
3448 // Create a CompilerThread
3449 CompilerThread::CompilerThread(CompileQueue* queue,
3450                                CompilerCounters* counters)
3451                                : JavaThread(&compiler_thread_entry) {
3452   _env   = NULL;
3453   _log   = NULL;
3454   _task  = NULL;
3455   _queue = queue;
3456   _counters = counters;
3457   _buffer_blob = NULL;
3458   _compiler = NULL;
3459 
3460   // Compiler uses resource area for compilation, let's bias it to mtCompiler
3461   resource_area()->bias_to(mtCompiler);
3462 
3463 #ifndef PRODUCT
3464   _ideal_graph_printer = NULL;
3465 #endif
3466 }
3467 
3468 CompilerThread::~CompilerThread() {
3469   // Delete objects which were allocated on heap.
3470   delete _counters;
3471 }
3472 
3473 bool CompilerThread::can_call_java() const {
3474   return _compiler != NULL && _compiler->is_jvmci();
3475 }
3476 
3477 // Create sweeper thread
3478 CodeCacheSweeperThread::CodeCacheSweeperThread()
3479 : JavaThread(&sweeper_thread_entry) {
3480   _scanned_compiled_method = NULL;
3481 }
3482 
3483 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3484   JavaThread::oops_do(f, cf);
3485   if (_scanned_compiled_method != NULL && cf != NULL) {
3486     // Safepoints can occur when the sweeper is scanning an nmethod so
3487     // process it here to make sure it isn't unloaded in the middle of
3488     // a scan.
3489     cf->do_code_blob(_scanned_compiled_method);
3490   }
3491 }
3492 
3493 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3494   JavaThread::nmethods_do(cf);
3495   if (_scanned_compiled_method != NULL && cf != NULL) {
3496     // Safepoints can occur when the sweeper is scanning an nmethod so
3497     // process it here to make sure it isn't unloaded in the middle of
3498     // a scan.
3499     cf->do_code_blob(_scanned_compiled_method);
3500   }
3501 }
3502 
3503 
3504 // ======= Threads ========
3505 
3506 // The Threads class links together all active threads, and provides
3507 // operations over all threads. It is protected by the Threads_lock,
3508 // which is also used in other global contexts like safepointing.
3509 // ThreadsListHandles are used to safely perform operations on one
3510 // or more threads without the risk of the thread exiting during the
3511 // operation.
3512 //
3513 // Note: The Threads_lock is currently more widely used than we
3514 // would like. We are actively migrating Threads_lock uses to other
3515 // mechanisms in order to reduce Threads_lock contention.
3516 
3517 int         Threads::_number_of_threads = 0;
3518 int         Threads::_number_of_non_daemon_threads = 0;
3519 int         Threads::_return_code = 0;
3520 uintx       Threads::_thread_claim_token = 1; // Never zero.
3521 size_t      JavaThread::_stack_size_at_create = 0;
3522 
3523 #ifdef ASSERT
3524 bool        Threads::_vm_complete = false;
3525 #endif
3526 
3527 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3528   Prefetch::read((void*)addr, prefetch_interval);
3529   return *addr;
3530 }
3531 
3532 // Possibly the ugliest for loop the world has seen. C++ does not allow
3533 // multiple types in the declaration section of the for loop. In this case
3534 // we are only dealing with pointers and hence can cast them. It looks ugly
3535 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3536 #define DO_JAVA_THREADS(LIST, X)                                                                                          \
3537     for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes,                           \
3538              *MACRO_list = (JavaThread*)(LIST),                                                                           \
3539              **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(),  \
3540              **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(),                                     \
3541              *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval);                 \
3542          MACRO_current_p != MACRO_end;                                                                                    \
3543          MACRO_current_p++,                                                                                               \
3544              X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3545 
3546 // All JavaThreads
3547 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3548 
3549 // All NonJavaThreads (i.e., every non-JavaThread in the system).
3550 void Threads::non_java_threads_do(ThreadClosure* tc) {
3551   NoSafepointVerifier nsv;
3552   for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) {
3553     tc->do_thread(njti.current());
3554   }
3555 }
3556 
3557 // All JavaThreads
3558 void Threads::java_threads_do(ThreadClosure* tc) {
3559   assert_locked_or_safepoint(Threads_lock);
3560   // ALL_JAVA_THREADS iterates through all JavaThreads.
3561   ALL_JAVA_THREADS(p) {
3562     tc->do_thread(p);
3563   }
3564 }
3565 
3566 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) {
3567   assert_locked_or_safepoint(Threads_lock);
3568   java_threads_do(tc);
3569   tc->do_thread(VMThread::vm_thread());
3570 }
3571 
3572 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
3573 void Threads::threads_do(ThreadClosure* tc) {
3574   assert_locked_or_safepoint(Threads_lock);
3575   java_threads_do(tc);
3576   non_java_threads_do(tc);
3577 }
3578 
3579 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3580   uintx claim_token = Threads::thread_claim_token();
3581   ALL_JAVA_THREADS(p) {
3582     if (p->claim_threads_do(is_par, claim_token)) {
3583       tc->do_thread(p);
3584     }
3585   }
3586   VMThread* vmt = VMThread::vm_thread();
3587   if (vmt->claim_threads_do(is_par, claim_token)) {
3588     tc->do_thread(vmt);
3589   }
3590 }
3591 
3592 // The system initialization in the library has three phases.
3593 //
3594 // Phase 1: java.lang.System class initialization
3595 //     java.lang.System is a primordial class loaded and initialized
3596 //     by the VM early during startup.  java.lang.System.<clinit>
3597 //     only does registerNatives and keeps the rest of the class
3598 //     initialization work later until thread initialization completes.
3599 //
3600 //     System.initPhase1 initializes the system properties, the static
3601 //     fields in, out, and err. Set up java signal handlers, OS-specific
3602 //     system settings, and thread group of the main thread.
3603 static void call_initPhase1(TRAPS) {
3604   Klass* klass =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3605   JavaValue result(T_VOID);
3606   JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3607                                          vmSymbols::void_method_signature(), CHECK);
3608 }
3609 
3610 // Phase 2. Module system initialization
3611 //     This will initialize the module system.  Only java.base classes
3612 //     can be loaded until phase 2 completes.
3613 //
3614 //     Call System.initPhase2 after the compiler initialization and jsr292
3615 //     classes get initialized because module initialization runs a lot of java
3616 //     code, that for performance reasons, should be compiled.  Also, this will
3617 //     enable the startup code to use lambda and other language features in this
3618 //     phase and onward.
3619 //
3620 //     After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3621 static void call_initPhase2(TRAPS) {
3622   TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3623 
3624   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3625 
3626   JavaValue result(T_INT);
3627   JavaCallArguments args;
3628   args.push_int(DisplayVMOutputToStderr);
3629   args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3630   JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3631                                          vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3632   if (result.get_jint() != JNI_OK) {
3633     vm_exit_during_initialization(); // no message or exception
3634   }
3635 
3636   universe_post_module_init();
3637 }
3638 
3639 // Phase 3. final setup - set security manager, system class loader and TCCL
3640 //
3641 //     This will instantiate and set the security manager, set the system class
3642 //     loader as well as the thread context class loader.  The security manager
3643 //     and system class loader may be a custom class loaded from -Xbootclasspath/a,
3644 //     other modules or the application's classpath.
3645 static void call_initPhase3(TRAPS) {
3646   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3647   JavaValue result(T_VOID);
3648   JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3649                                          vmSymbols::void_method_signature(), CHECK);
3650 }
3651 
3652 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3653   TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3654 
3655   if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3656     create_vm_init_libraries();
3657   }
3658 
3659   initialize_class(vmSymbols::java_lang_String(), CHECK);
3660 
3661   // Inject CompactStrings value after the static initializers for String ran.
3662   java_lang_String::set_compact_strings(CompactStrings);
3663 
3664   // Initialize java_lang.System (needed before creating the thread)
3665   initialize_class(vmSymbols::java_lang_System(), CHECK);
3666   // The VM creates & returns objects of this class. Make sure it's initialized.
3667   initialize_class(vmSymbols::java_lang_Class(), CHECK);
3668   initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3669   Handle thread_group = create_initial_thread_group(CHECK);
3670   Universe::set_main_thread_group(thread_group());
3671   initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3672   oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3673   main_thread->set_threadObj(thread_object);
3674 
3675   // Set thread status to running since main thread has
3676   // been started and running.
3677   java_lang_Thread::set_thread_status(thread_object,
3678                                       java_lang_Thread::RUNNABLE);
3679 
3680   // The VM creates objects of this class.
3681   initialize_class(vmSymbols::java_lang_Module(), CHECK);
3682 
3683 #ifdef ASSERT
3684   InstanceKlass *k = SystemDictionary::UnsafeConstants_klass();
3685   assert(k->is_not_initialized(), "UnsafeConstants should not already be initialized");
3686 #endif
3687 
3688   // initialize the hardware-specific constants needed by Unsafe
3689   initialize_class(vmSymbols::jdk_internal_misc_UnsafeConstants(), CHECK);
3690   jdk_internal_misc_UnsafeConstants::set_unsafe_constants();
3691 
3692   // The VM preresolves methods to these classes. Make sure that they get initialized
3693   initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3694   initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3695 
3696   // Phase 1 of the system initialization in the library, java.lang.System class initialization
3697   call_initPhase1(CHECK);
3698 
3699   // get the Java runtime name after java.lang.System is initialized
3700   JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3701   JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3702 
3703   // an instance of OutOfMemory exception has been allocated earlier
3704   initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3705   initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3706   initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3707   initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3708   initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3709   initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3710   initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3711   initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3712 
3713   // Eager box cache initialization only if AOT is on and any library is loaded.
3714   AOTLoader::initialize_box_caches(CHECK);
3715 }
3716 
3717 void Threads::initialize_jsr292_core_classes(TRAPS) {
3718   TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3719 
3720   initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3721   initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3722   initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3723   initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3724 }
3725 
3726 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3727   extern void JDK_Version_init();
3728 
3729   // Preinitialize version info.
3730   VM_Version::early_initialize();
3731 
3732   // Check version
3733   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3734 
3735   // Initialize library-based TLS
3736   ThreadLocalStorage::init();
3737 
3738   // Initialize the output stream module
3739   ostream_init();
3740 
3741   // Process java launcher properties.
3742   Arguments::process_sun_java_launcher_properties(args);
3743 
3744   // Initialize the os module
3745   os::init();
3746 
3747   // Record VM creation timing statistics
3748   TraceVmCreationTime create_vm_timer;
3749   create_vm_timer.start();
3750 
3751   // Initialize system properties.
3752   Arguments::init_system_properties();
3753 
3754   // So that JDK version can be used as a discriminator when parsing arguments
3755   JDK_Version_init();
3756 
3757   // Update/Initialize System properties after JDK version number is known
3758   Arguments::init_version_specific_system_properties();
3759 
3760   // Make sure to initialize log configuration *before* parsing arguments
3761   LogConfiguration::initialize(create_vm_timer.begin_time());
3762 
3763   // Parse arguments
3764   // Note: this internally calls os::init_container_support()
3765   jint parse_result = Arguments::parse(args);
3766   if (parse_result != JNI_OK) return parse_result;
3767 
3768   os::init_before_ergo();
3769 
3770   jint ergo_result = Arguments::apply_ergo();
3771   if (ergo_result != JNI_OK) return ergo_result;
3772 
3773   // Final check of all ranges after ergonomics which may change values.
3774   if (!JVMFlagRangeList::check_ranges()) {
3775     return JNI_EINVAL;
3776   }
3777 
3778   // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3779   bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo);
3780   if (!constraint_result) {
3781     return JNI_EINVAL;
3782   }
3783 
3784   JVMFlagWriteableList::mark_startup();
3785 
3786   if (PauseAtStartup) {
3787     os::pause();
3788   }
3789 
3790   HOTSPOT_VM_INIT_BEGIN();
3791 
3792   // Timing (must come after argument parsing)
3793   TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3794 
3795   // Initialize the os module after parsing the args
3796   jint os_init_2_result = os::init_2();
3797   if (os_init_2_result != JNI_OK) return os_init_2_result;
3798 
3799 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
3800   // Initialize assert poison page mechanism.
3801   if (ShowRegistersOnAssert) {
3802     initialize_assert_poison();
3803   }
3804 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
3805 
3806   SafepointMechanism::initialize();
3807 
3808   jint adjust_after_os_result = Arguments::adjust_after_os();
3809   if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3810 
3811   // Initialize output stream logging
3812   ostream_init_log();
3813 
3814   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3815   // Must be before create_vm_init_agents()
3816   if (Arguments::init_libraries_at_startup()) {
3817     convert_vm_init_libraries_to_agents();
3818   }
3819 
3820   // Launch -agentlib/-agentpath and converted -Xrun agents
3821   if (Arguments::init_agents_at_startup()) {
3822     create_vm_init_agents();
3823   }
3824 
3825   // Initialize Threads state
3826   _number_of_threads = 0;
3827   _number_of_non_daemon_threads = 0;
3828 
3829   // Initialize global data structures and create system classes in heap
3830   vm_init_globals();
3831 
3832 #if INCLUDE_JVMCI
3833   if (JVMCICounterSize > 0) {
3834     JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtJVMCI);
3835     memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3836   } else {
3837     JavaThread::_jvmci_old_thread_counters = NULL;
3838   }
3839 #endif // INCLUDE_JVMCI
3840 
3841   // Attach the main thread to this os thread
3842   JavaThread* main_thread = new JavaThread();
3843   main_thread->set_thread_state(_thread_in_vm);
3844   main_thread->initialize_thread_current();
3845   // must do this before set_active_handles
3846   main_thread->record_stack_base_and_size();
3847   main_thread->register_thread_stack_with_NMT();
3848   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3849 
3850   if (!main_thread->set_as_starting_thread()) {
3851     vm_shutdown_during_initialization(
3852                                       "Failed necessary internal allocation. Out of swap space");
3853     main_thread->smr_delete();
3854     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3855     return JNI_ENOMEM;
3856   }
3857 
3858   // Enable guard page *after* os::create_main_thread(), otherwise it would
3859   // crash Linux VM, see notes in os_linux.cpp.
3860   main_thread->create_stack_guard_pages();
3861 
3862   // Initialize Java-Level synchronization subsystem
3863   ObjectMonitor::Initialize();
3864 
3865   // Initialize global modules
3866   jint status = init_globals();
3867   if (status != JNI_OK) {
3868     main_thread->smr_delete();
3869     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3870     return status;
3871   }
3872 
3873   JFR_ONLY(Jfr::on_vm_init();)
3874 
3875   // Should be done after the heap is fully created
3876   main_thread->cache_global_variables();
3877 
3878   HandleMark hm;
3879 
3880   { MutexLocker mu(Threads_lock);
3881     Threads::add(main_thread);
3882   }
3883 
3884   // Any JVMTI raw monitors entered in onload will transition into
3885   // real raw monitor. VM is setup enough here for raw monitor enter.
3886   JvmtiExport::transition_pending_onload_raw_monitors();
3887 
3888   // Create the VMThread
3889   { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3890 
3891   VMThread::create();
3892     Thread* vmthread = VMThread::vm_thread();
3893 
3894     if (!os::create_thread(vmthread, os::vm_thread)) {
3895       vm_exit_during_initialization("Cannot create VM thread. "
3896                                     "Out of system resources.");
3897     }
3898 
3899     // Wait for the VM thread to become ready, and VMThread::run to initialize
3900     // Monitors can have spurious returns, must always check another state flag
3901     {
3902       MonitorLocker ml(Notify_lock);
3903       os::start_thread(vmthread);
3904       while (vmthread->active_handles() == NULL) {
3905         ml.wait();
3906       }
3907     }
3908   }
3909 
3910   assert(Universe::is_fully_initialized(), "not initialized");
3911   if (VerifyDuringStartup) {
3912     // Make sure we're starting with a clean slate.
3913     VM_Verify verify_op;
3914     VMThread::execute(&verify_op);
3915   }
3916 
3917   // We need this to update the java.vm.info property in case any flags used
3918   // to initially define it have been changed. This is needed for both CDS and
3919   // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info
3920   // is initially computed. See Abstract_VM_Version::vm_info_string().
3921   // This update must happen before we initialize the java classes, but
3922   // after any initialization logic that might modify the flags.
3923   Arguments::update_vm_info_property(VM_Version::vm_info_string());
3924 
3925   Thread* THREAD = Thread::current();
3926 
3927   // Always call even when there are not JVMTI environments yet, since environments
3928   // may be attached late and JVMTI must track phases of VM execution
3929   JvmtiExport::enter_early_start_phase();
3930 
3931   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3932   JvmtiExport::post_early_vm_start();
3933 
3934   initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3935 
3936   quicken_jni_functions();
3937 
3938   // No more stub generation allowed after that point.
3939   StubCodeDesc::freeze();
3940 
3941   // Set flag that basic initialization has completed. Used by exceptions and various
3942   // debug stuff, that does not work until all basic classes have been initialized.
3943   set_init_completed();
3944 
3945   LogConfiguration::post_initialize();
3946   Metaspace::post_initialize();
3947 
3948   HOTSPOT_VM_INIT_END();
3949 
3950   // record VM initialization completion time
3951 #if INCLUDE_MANAGEMENT
3952   Management::record_vm_init_completed();
3953 #endif // INCLUDE_MANAGEMENT
3954 
3955   // Signal Dispatcher needs to be started before VMInit event is posted
3956   os::initialize_jdk_signal_support(CHECK_JNI_ERR);
3957 
3958   // Start Attach Listener if +StartAttachListener or it can't be started lazily
3959   if (!DisableAttachMechanism) {
3960     AttachListener::vm_start();
3961     if (StartAttachListener || AttachListener::init_at_startup()) {
3962       AttachListener::init();
3963     }
3964   }
3965 
3966   // Launch -Xrun agents
3967   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3968   // back-end can launch with -Xdebug -Xrunjdwp.
3969   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3970     create_vm_init_libraries();
3971   }
3972 
3973   if (CleanChunkPoolAsync) {
3974     Chunk::start_chunk_pool_cleaner_task();
3975   }
3976 
3977 
3978   // initialize compiler(s)
3979 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3980 #if INCLUDE_JVMCI
3981   bool force_JVMCI_intialization = false;
3982   if (EnableJVMCI) {
3983     // Initialize JVMCI eagerly when it is explicitly requested.
3984     // Or when JVMCILibDumpJNIConfig or JVMCIPrintProperties is enabled.
3985     force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties || JVMCILibDumpJNIConfig;
3986 
3987     if (!force_JVMCI_intialization) {
3988       // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3989       // compilations via JVMCI will not actually block until JVMCI is initialized.
3990       force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3991     }
3992   }
3993 #endif
3994   CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
3995   // Postpone completion of compiler initialization to after JVMCI
3996   // is initialized to avoid timeouts of blocking compilations.
3997   if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
3998     CompileBroker::compilation_init_phase2();
3999   }
4000 #endif
4001 
4002   // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
4003   // It is done after compilers are initialized, because otherwise compilations of
4004   // signature polymorphic MH intrinsics can be missed
4005   // (see SystemDictionary::find_method_handle_intrinsic).
4006   initialize_jsr292_core_classes(CHECK_JNI_ERR);
4007 
4008   // This will initialize the module system.  Only java.base classes can be
4009   // loaded until phase 2 completes
4010   call_initPhase2(CHECK_JNI_ERR);
4011 
4012   // Always call even when there are not JVMTI environments yet, since environments
4013   // may be attached late and JVMTI must track phases of VM execution
4014   JvmtiExport::enter_start_phase();
4015 
4016   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
4017   JvmtiExport::post_vm_start();
4018 
4019   // Final system initialization including security manager and system class loader
4020   call_initPhase3(CHECK_JNI_ERR);
4021 
4022   // cache the system and platform class loaders
4023   SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
4024 
4025 #if INCLUDE_CDS
4026   // capture the module path info from the ModuleEntryTable
4027   ClassLoader::initialize_module_path(THREAD);
4028 #endif
4029 
4030 #if INCLUDE_JVMCI
4031   if (force_JVMCI_intialization) {
4032     JVMCI::initialize_compiler(CHECK_JNI_ERR);
4033     CompileBroker::compilation_init_phase2();
4034   }
4035 #endif
4036 
4037   // Always call even when there are not JVMTI environments yet, since environments
4038   // may be attached late and JVMTI must track phases of VM execution
4039   JvmtiExport::enter_live_phase();
4040 
4041   // Make perfmemory accessible
4042   PerfMemory::set_accessible(true);
4043 
4044   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
4045   JvmtiExport::post_vm_initialized();
4046 
4047   JFR_ONLY(Jfr::on_vm_start();)
4048 
4049 #if INCLUDE_MANAGEMENT
4050   Management::initialize(THREAD);
4051 
4052   if (HAS_PENDING_EXCEPTION) {
4053     // management agent fails to start possibly due to
4054     // configuration problem and is responsible for printing
4055     // stack trace if appropriate. Simply exit VM.
4056     vm_exit(1);
4057   }
4058 #endif // INCLUDE_MANAGEMENT
4059 
4060   if (MemProfiling)                   MemProfiler::engage();
4061   StatSampler::engage();
4062   if (CheckJNICalls)                  JniPeriodicChecker::engage();
4063 
4064   BiasedLocking::init();
4065 
4066 #if INCLUDE_RTM_OPT
4067   RTMLockingCounters::init();
4068 #endif
4069 
4070   call_postVMInitHook(THREAD);
4071   // The Java side of PostVMInitHook.run must deal with all
4072   // exceptions and provide means of diagnosis.
4073   if (HAS_PENDING_EXCEPTION) {
4074     CLEAR_PENDING_EXCEPTION;
4075   }
4076 
4077   {
4078     MutexLocker ml(PeriodicTask_lock);
4079     // Make sure the WatcherThread can be started by WatcherThread::start()
4080     // or by dynamic enrollment.
4081     WatcherThread::make_startable();
4082     // Start up the WatcherThread if there are any periodic tasks
4083     // NOTE:  All PeriodicTasks should be registered by now. If they
4084     //   aren't, late joiners might appear to start slowly (we might
4085     //   take a while to process their first tick).
4086     if (PeriodicTask::num_tasks() > 0) {
4087       WatcherThread::start();
4088     }
4089   }
4090 
4091   create_vm_timer.end();
4092 #ifdef ASSERT
4093   _vm_complete = true;
4094 #endif
4095 
4096   if (DumpSharedSpaces) {
4097     MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
4098     ShouldNotReachHere();
4099   }
4100 
4101   return JNI_OK;
4102 }
4103 
4104 // type for the Agent_OnLoad and JVM_OnLoad entry points
4105 extern "C" {
4106   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
4107 }
4108 // Find a command line agent library and return its entry point for
4109 //         -agentlib:  -agentpath:   -Xrun
4110 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
4111 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
4112                                     const char *on_load_symbols[],
4113                                     size_t num_symbol_entries) {
4114   OnLoadEntry_t on_load_entry = NULL;
4115   void *library = NULL;
4116 
4117   if (!agent->valid()) {
4118     char buffer[JVM_MAXPATHLEN];
4119     char ebuf[1024] = "";
4120     const char *name = agent->name();
4121     const char *msg = "Could not find agent library ";
4122 
4123     // First check to see if agent is statically linked into executable
4124     if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
4125       library = agent->os_lib();
4126     } else if (agent->is_absolute_path()) {
4127       library = os::dll_load(name, ebuf, sizeof ebuf);
4128       if (library == NULL) {
4129         const char *sub_msg = " in absolute path, with error: ";
4130         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4131         char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4132         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4133         // If we can't find the agent, exit.
4134         vm_exit_during_initialization(buf, NULL);
4135         FREE_C_HEAP_ARRAY(char, buf);
4136       }
4137     } else {
4138       // Try to load the agent from the standard dll directory
4139       if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4140                              name)) {
4141         library = os::dll_load(buffer, ebuf, sizeof ebuf);
4142       }
4143       if (library == NULL) { // Try the library path directory.
4144         if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4145           library = os::dll_load(buffer, ebuf, sizeof ebuf);
4146         }
4147         if (library == NULL) {
4148           const char *sub_msg = " on the library path, with error: ";
4149           const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4150 
4151           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4152                        strlen(ebuf) + strlen(sub_msg2) + 1;
4153           char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4154           if (!agent->is_instrument_lib()) {
4155             jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4156           } else {
4157             jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4158           }
4159           // If we can't find the agent, exit.
4160           vm_exit_during_initialization(buf, NULL);
4161           FREE_C_HEAP_ARRAY(char, buf);
4162         }
4163       }
4164     }
4165     agent->set_os_lib(library);
4166     agent->set_valid();
4167   }
4168 
4169   // Find the OnLoad function.
4170   on_load_entry =
4171     CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4172                                                           false,
4173                                                           on_load_symbols,
4174                                                           num_symbol_entries));
4175   return on_load_entry;
4176 }
4177 
4178 // Find the JVM_OnLoad entry point
4179 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4180   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4181   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4182 }
4183 
4184 // Find the Agent_OnLoad entry point
4185 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4186   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4187   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4188 }
4189 
4190 // For backwards compatibility with -Xrun
4191 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4192 // treated like -agentpath:
4193 // Must be called before agent libraries are created
4194 void Threads::convert_vm_init_libraries_to_agents() {
4195   AgentLibrary* agent;
4196   AgentLibrary* next;
4197 
4198   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4199     next = agent->next();  // cache the next agent now as this agent may get moved off this list
4200     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4201 
4202     // If there is an JVM_OnLoad function it will get called later,
4203     // otherwise see if there is an Agent_OnLoad
4204     if (on_load_entry == NULL) {
4205       on_load_entry = lookup_agent_on_load(agent);
4206       if (on_load_entry != NULL) {
4207         // switch it to the agent list -- so that Agent_OnLoad will be called,
4208         // JVM_OnLoad won't be attempted and Agent_OnUnload will
4209         Arguments::convert_library_to_agent(agent);
4210       } else {
4211         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4212       }
4213     }
4214   }
4215 }
4216 
4217 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
4218 // Invokes Agent_OnLoad
4219 // Called very early -- before JavaThreads exist
4220 void Threads::create_vm_init_agents() {
4221   extern struct JavaVM_ main_vm;
4222   AgentLibrary* agent;
4223 
4224   JvmtiExport::enter_onload_phase();
4225 
4226   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4227     // CDS dumping does not support native JVMTI agent.
4228     // CDS dumping supports Java agent if the AllowArchivingWithJavaAgent diagnostic option is specified.
4229     if (DumpSharedSpaces || DynamicDumpSharedSpaces) {
4230       if(!agent->is_instrument_lib()) {
4231         vm_exit_during_cds_dumping("CDS dumping does not support native JVMTI agent, name", agent->name());
4232       } else if (!AllowArchivingWithJavaAgent) {
4233         vm_exit_during_cds_dumping(
4234           "Must enable AllowArchivingWithJavaAgent in order to run Java agent during CDS dumping");
4235       }
4236     }
4237 
4238     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
4239 
4240     if (on_load_entry != NULL) {
4241       // Invoke the Agent_OnLoad function
4242       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4243       if (err != JNI_OK) {
4244         vm_exit_during_initialization("agent library failed to init", agent->name());
4245       }
4246     } else {
4247       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4248     }
4249   }
4250 
4251   JvmtiExport::enter_primordial_phase();
4252 }
4253 
4254 extern "C" {
4255   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4256 }
4257 
4258 void Threads::shutdown_vm_agents() {
4259   // Send any Agent_OnUnload notifications
4260   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4261   size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4262   extern struct JavaVM_ main_vm;
4263   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4264 
4265     // Find the Agent_OnUnload function.
4266     Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4267                                                    os::find_agent_function(agent,
4268                                                    false,
4269                                                    on_unload_symbols,
4270                                                    num_symbol_entries));
4271 
4272     // Invoke the Agent_OnUnload function
4273     if (unload_entry != NULL) {
4274       JavaThread* thread = JavaThread::current();
4275       ThreadToNativeFromVM ttn(thread);
4276       HandleMark hm(thread);
4277       (*unload_entry)(&main_vm);
4278     }
4279   }
4280 }
4281 
4282 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4283 // Invokes JVM_OnLoad
4284 void Threads::create_vm_init_libraries() {
4285   extern struct JavaVM_ main_vm;
4286   AgentLibrary* agent;
4287 
4288   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4289     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4290 
4291     if (on_load_entry != NULL) {
4292       // Invoke the JVM_OnLoad function
4293       JavaThread* thread = JavaThread::current();
4294       ThreadToNativeFromVM ttn(thread);
4295       HandleMark hm(thread);
4296       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4297       if (err != JNI_OK) {
4298         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4299       }
4300     } else {
4301       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4302     }
4303   }
4304 }
4305 
4306 
4307 // Last thread running calls java.lang.Shutdown.shutdown()
4308 void JavaThread::invoke_shutdown_hooks() {
4309   HandleMark hm(this);
4310 
4311   // We could get here with a pending exception, if so clear it now.
4312   if (this->has_pending_exception()) {
4313     this->clear_pending_exception();
4314   }
4315 
4316   EXCEPTION_MARK;
4317   Klass* shutdown_klass =
4318     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4319                                       THREAD);
4320   if (shutdown_klass != NULL) {
4321     // SystemDictionary::resolve_or_null will return null if there was
4322     // an exception.  If we cannot load the Shutdown class, just don't
4323     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
4324     // won't be run.  Note that if a shutdown hook was registered,
4325     // the Shutdown class would have already been loaded
4326     // (Runtime.addShutdownHook will load it).
4327     JavaValue result(T_VOID);
4328     JavaCalls::call_static(&result,
4329                            shutdown_klass,
4330                            vmSymbols::shutdown_name(),
4331                            vmSymbols::void_method_signature(),
4332                            THREAD);
4333   }
4334   CLEAR_PENDING_EXCEPTION;
4335 }
4336 
4337 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4338 // the program falls off the end of main(). Another VM exit path is through
4339 // vm_exit() when the program calls System.exit() to return a value or when
4340 // there is a serious error in VM. The two shutdown paths are not exactly
4341 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4342 // and VM_Exit op at VM level.
4343 //
4344 // Shutdown sequence:
4345 //   + Shutdown native memory tracking if it is on
4346 //   + Wait until we are the last non-daemon thread to execute
4347 //     <-- every thing is still working at this moment -->
4348 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4349 //        shutdown hooks
4350 //   + Call before_exit(), prepare for VM exit
4351 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4352 //        currently the only user of this mechanism is File.deleteOnExit())
4353 //      > stop StatSampler, watcher thread, CMS threads,
4354 //        post thread end and vm death events to JVMTI,
4355 //        stop signal thread
4356 //   + Call JavaThread::exit(), it will:
4357 //      > release JNI handle blocks, remove stack guard pages
4358 //      > remove this thread from Threads list
4359 //     <-- no more Java code from this thread after this point -->
4360 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4361 //     the compiler threads at safepoint
4362 //     <-- do not use anything that could get blocked by Safepoint -->
4363 //   + Disable tracing at JNI/JVM barriers
4364 //   + Set _vm_exited flag for threads that are still running native code
4365 //   + Call exit_globals()
4366 //      > deletes tty
4367 //      > deletes PerfMemory resources
4368 //   + Delete this thread
4369 //   + Return to caller
4370 
4371 bool Threads::destroy_vm() {
4372   JavaThread* thread = JavaThread::current();
4373 
4374 #ifdef ASSERT
4375   _vm_complete = false;
4376 #endif
4377   // Wait until we are the last non-daemon thread to execute
4378   { MonitorLocker nu(Threads_lock);
4379     while (Threads::number_of_non_daemon_threads() > 1)
4380       // This wait should make safepoint checks, wait without a timeout,
4381       // and wait as a suspend-equivalent condition.
4382       nu.wait(0, Mutex::_as_suspend_equivalent_flag);
4383   }
4384 
4385   EventShutdown e;
4386   if (e.should_commit()) {
4387     e.set_reason("No remaining non-daemon Java threads");
4388     e.commit();
4389   }
4390 
4391   // Hang forever on exit if we are reporting an error.
4392   if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4393     os::infinite_sleep();
4394   }
4395   os::wait_for_keypress_at_exit();
4396 
4397   // run Java level shutdown hooks
4398   thread->invoke_shutdown_hooks();
4399 
4400   before_exit(thread);
4401 
4402   thread->exit(true);
4403 
4404   // Stop VM thread.
4405   {
4406     // 4945125 The vm thread comes to a safepoint during exit.
4407     // GC vm_operations can get caught at the safepoint, and the
4408     // heap is unparseable if they are caught. Grab the Heap_lock
4409     // to prevent this. The GC vm_operations will not be able to
4410     // queue until after the vm thread is dead. After this point,
4411     // we'll never emerge out of the safepoint before the VM exits.
4412 
4413     MutexLocker ml(Heap_lock, Mutex::_no_safepoint_check_flag);
4414 
4415     VMThread::wait_for_vm_thread_exit();
4416     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4417     VMThread::destroy();
4418   }
4419 
4420   // Now, all Java threads are gone except daemon threads. Daemon threads
4421   // running Java code or in VM are stopped by the Safepoint. However,
4422   // daemon threads executing native code are still running.  But they
4423   // will be stopped at native=>Java/VM barriers. Note that we can't
4424   // simply kill or suspend them, as it is inherently deadlock-prone.
4425 
4426   VM_Exit::set_vm_exited();
4427 
4428   // Clean up ideal graph printers after the VMThread has started
4429   // the final safepoint which will block all the Compiler threads.
4430   // Note that this Thread has already logically exited so the
4431   // clean_up() function's use of a JavaThreadIteratorWithHandle
4432   // would be a problem except set_vm_exited() has remembered the
4433   // shutdown thread which is granted a policy exception.
4434 #if defined(COMPILER2) && !defined(PRODUCT)
4435   IdealGraphPrinter::clean_up();
4436 #endif
4437 
4438   notify_vm_shutdown();
4439 
4440   // exit_globals() will delete tty
4441   exit_globals();
4442 
4443   // We are after VM_Exit::set_vm_exited() so we can't call
4444   // thread->smr_delete() or we will block on the Threads_lock.
4445   // Deleting the shutdown thread here is safe because another
4446   // JavaThread cannot have an active ThreadsListHandle for
4447   // this JavaThread.
4448   delete thread;
4449 
4450 #if INCLUDE_JVMCI
4451   if (JVMCICounterSize > 0) {
4452     FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4453   }
4454 #endif
4455 
4456   LogConfiguration::finalize();
4457 
4458   return true;
4459 }
4460 
4461 
4462 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4463   if (version == JNI_VERSION_1_1) return JNI_TRUE;
4464   return is_supported_jni_version(version);
4465 }
4466 
4467 
4468 jboolean Threads::is_supported_jni_version(jint version) {
4469   if (version == JNI_VERSION_1_2) return JNI_TRUE;
4470   if (version == JNI_VERSION_1_4) return JNI_TRUE;
4471   if (version == JNI_VERSION_1_6) return JNI_TRUE;
4472   if (version == JNI_VERSION_1_8) return JNI_TRUE;
4473   if (version == JNI_VERSION_9) return JNI_TRUE;
4474   if (version == JNI_VERSION_10) return JNI_TRUE;
4475   return JNI_FALSE;
4476 }
4477 
4478 
4479 void Threads::add(JavaThread* p, bool force_daemon) {
4480   // The threads lock must be owned at this point
4481   assert(Threads_lock->owned_by_self(), "must have threads lock");
4482 
4483   BarrierSet::barrier_set()->on_thread_attach(p);
4484 
4485   // Once a JavaThread is added to the Threads list, smr_delete() has
4486   // to be used to delete it. Otherwise we can just delete it directly.
4487   p->set_on_thread_list();
4488 
4489   _number_of_threads++;
4490   oop threadObj = p->threadObj();
4491   bool daemon = true;
4492   // Bootstrapping problem: threadObj can be null for initial
4493   // JavaThread (or for threads attached via JNI)
4494   if ((!force_daemon) && !is_daemon((threadObj))) {
4495     _number_of_non_daemon_threads++;
4496     daemon = false;
4497   }
4498 
4499   ThreadService::add_thread(p, daemon);
4500 
4501   // Maintain fast thread list
4502   ThreadsSMRSupport::add_thread(p);
4503 
4504   // Possible GC point.
4505   Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4506 }
4507 
4508 void Threads::remove(JavaThread* p, bool is_daemon) {
4509 
4510   // Reclaim the ObjectMonitors from the omInUseList and omFreeList of the moribund thread.
4511   ObjectSynchronizer::omFlush(p);
4512 
4513   // Extra scope needed for Thread_lock, so we can check
4514   // that we do not remove thread without safepoint code notice
4515   { MonitorLocker ml(Threads_lock);
4516 
4517     assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4518 
4519     // Maintain fast thread list
4520     ThreadsSMRSupport::remove_thread(p);
4521 
4522     _number_of_threads--;
4523     if (!is_daemon) {
4524       _number_of_non_daemon_threads--;
4525 
4526       // Only one thread left, do a notify on the Threads_lock so a thread waiting
4527       // on destroy_vm will wake up.
4528       if (number_of_non_daemon_threads() == 1) {
4529         ml.notify_all();
4530       }
4531     }
4532     ThreadService::remove_thread(p, is_daemon);
4533 
4534     // Make sure that safepoint code disregard this thread. This is needed since
4535     // the thread might mess around with locks after this point. This can cause it
4536     // to do callbacks into the safepoint code. However, the safepoint code is not aware
4537     // of this thread since it is removed from the queue.
4538     p->set_terminated_value();
4539   } // unlock Threads_lock
4540 
4541   // Since Events::log uses a lock, we grab it outside the Threads_lock
4542   Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4543 }
4544 
4545 // Operations on the Threads list for GC.  These are not explicitly locked,
4546 // but the garbage collector must provide a safe context for them to run.
4547 // In particular, these things should never be called when the Threads_lock
4548 // is held by some other thread. (Note: the Safepoint abstraction also
4549 // uses the Threads_lock to guarantee this property. It also makes sure that
4550 // all threads gets blocked when exiting or starting).
4551 
4552 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4553   ALL_JAVA_THREADS(p) {
4554     p->oops_do(f, cf);
4555   }
4556   VMThread::vm_thread()->oops_do(f, cf);
4557 }
4558 
4559 void Threads::change_thread_claim_token() {
4560   if (++_thread_claim_token == 0) {
4561     // On overflow of the token counter, there is a risk of future
4562     // collisions between a new global token value and a stale token
4563     // for a thread, because not all iterations visit all threads.
4564     // (Though it's pretty much a theoretical concern for non-trivial
4565     // token counter sizes.)  To deal with the possibility, reset all
4566     // the thread tokens to zero on global token overflow.
4567     struct ResetClaims : public ThreadClosure {
4568       virtual void do_thread(Thread* t) {
4569         t->claim_threads_do(false, 0);
4570       }
4571     } reset_claims;
4572     Threads::threads_do(&reset_claims);
4573     // On overflow, update the global token to non-zero, to
4574     // avoid the special "never claimed" initial thread value.
4575     _thread_claim_token = 1;
4576   }
4577 }
4578 
4579 #ifdef ASSERT
4580 void assert_thread_claimed(const char* kind, Thread* t, uintx expected) {
4581   const uintx token = t->threads_do_token();
4582   assert(token == expected,
4583          "%s " PTR_FORMAT " has incorrect value " UINTX_FORMAT " != "
4584          UINTX_FORMAT, kind, p2i(t), token, expected);
4585 }
4586 
4587 void Threads::assert_all_threads_claimed() {
4588   ALL_JAVA_THREADS(p) {
4589     assert_thread_claimed("Thread", p, _thread_claim_token);
4590   }
4591   assert_thread_claimed("VMThread", VMThread::vm_thread(), _thread_claim_token);
4592 }
4593 #endif // ASSERT
4594 
4595 class ParallelOopsDoThreadClosure : public ThreadClosure {
4596 private:
4597   OopClosure* _f;
4598   CodeBlobClosure* _cf;
4599 public:
4600   ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4601   void do_thread(Thread* t) {
4602     t->oops_do(_f, _cf);
4603   }
4604 };
4605 
4606 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4607   ParallelOopsDoThreadClosure tc(f, cf);
4608   possibly_parallel_threads_do(is_par, &tc);
4609 }
4610 
4611 void Threads::nmethods_do(CodeBlobClosure* cf) {
4612   ALL_JAVA_THREADS(p) {
4613     // This is used by the code cache sweeper to mark nmethods that are active
4614     // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4615     // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4616     if(!p->is_Code_cache_sweeper_thread()) {
4617       p->nmethods_do(cf);
4618     }
4619   }
4620 }
4621 
4622 void Threads::metadata_do(MetadataClosure* f) {
4623   ALL_JAVA_THREADS(p) {
4624     p->metadata_do(f);
4625   }
4626 }
4627 
4628 class ThreadHandlesClosure : public ThreadClosure {
4629   void (*_f)(Metadata*);
4630  public:
4631   ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4632   virtual void do_thread(Thread* thread) {
4633     thread->metadata_handles_do(_f);
4634   }
4635 };
4636 
4637 void Threads::metadata_handles_do(void f(Metadata*)) {
4638   // Only walk the Handles in Thread.
4639   ThreadHandlesClosure handles_closure(f);
4640   threads_do(&handles_closure);
4641 }
4642 
4643 void Threads::deoptimized_wrt_marked_nmethods() {
4644   ALL_JAVA_THREADS(p) {
4645     p->deoptimized_wrt_marked_nmethods();
4646   }
4647 }
4648 
4649 
4650 // Get count Java threads that are waiting to enter the specified monitor.
4651 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4652                                                          int count,
4653                                                          address monitor) {
4654   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4655 
4656   int i = 0;
4657   DO_JAVA_THREADS(t_list, p) {
4658     if (!p->can_call_java()) continue;
4659 
4660     address pending = (address)p->current_pending_monitor();
4661     if (pending == monitor) {             // found a match
4662       if (i < count) result->append(p);   // save the first count matches
4663       i++;
4664     }
4665   }
4666 
4667   return result;
4668 }
4669 
4670 
4671 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4672                                                       address owner) {
4673   // NULL owner means not locked so we can skip the search
4674   if (owner == NULL) return NULL;
4675 
4676   DO_JAVA_THREADS(t_list, p) {
4677     // first, see if owner is the address of a Java thread
4678     if (owner == (address)p) return p;
4679   }
4680 
4681   // Cannot assert on lack of success here since this function may be
4682   // used by code that is trying to report useful problem information
4683   // like deadlock detection.
4684   if (UseHeavyMonitors) return NULL;
4685 
4686   // If we didn't find a matching Java thread and we didn't force use of
4687   // heavyweight monitors, then the owner is the stack address of the
4688   // Lock Word in the owning Java thread's stack.
4689   //
4690   JavaThread* the_owner = NULL;
4691   DO_JAVA_THREADS(t_list, q) {
4692     if (q->is_lock_owned(owner)) {
4693       the_owner = q;
4694       break;
4695     }
4696   }
4697 
4698   // cannot assert on lack of success here; see above comment
4699   return the_owner;
4700 }
4701 
4702 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4703 void Threads::print_on(outputStream* st, bool print_stacks,
4704                        bool internal_format, bool print_concurrent_locks,
4705                        bool print_extended_info) {
4706   char buf[32];
4707   st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4708 
4709   st->print_cr("Full thread dump %s (%s %s):",
4710                VM_Version::vm_name(),
4711                VM_Version::vm_release(),
4712                VM_Version::vm_info_string());
4713   st->cr();
4714 
4715 #if INCLUDE_SERVICES
4716   // Dump concurrent locks
4717   ConcurrentLocksDump concurrent_locks;
4718   if (print_concurrent_locks) {
4719     concurrent_locks.dump_at_safepoint();
4720   }
4721 #endif // INCLUDE_SERVICES
4722 
4723   ThreadsSMRSupport::print_info_on(st);
4724   st->cr();
4725 
4726   ALL_JAVA_THREADS(p) {
4727     ResourceMark rm;
4728     p->print_on(st, print_extended_info);
4729     if (print_stacks) {
4730       if (internal_format) {
4731         p->trace_stack();
4732       } else {
4733         p->print_stack_on(st);
4734       }
4735     }
4736     st->cr();
4737 #if INCLUDE_SERVICES
4738     if (print_concurrent_locks) {
4739       concurrent_locks.print_locks_on(p, st);
4740     }
4741 #endif // INCLUDE_SERVICES
4742   }
4743 
4744   VMThread::vm_thread()->print_on(st);
4745   st->cr();
4746   Universe::heap()->print_gc_threads_on(st);
4747   WatcherThread* wt = WatcherThread::watcher_thread();
4748   if (wt != NULL) {
4749     wt->print_on(st);
4750     st->cr();
4751   }
4752 
4753   st->flush();
4754 }
4755 
4756 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4757                              int buflen, bool* found_current) {
4758   if (this_thread != NULL) {
4759     bool is_current = (current == this_thread);
4760     *found_current = *found_current || is_current;
4761     st->print("%s", is_current ? "=>" : "  ");
4762 
4763     st->print(PTR_FORMAT, p2i(this_thread));
4764     st->print(" ");
4765     this_thread->print_on_error(st, buf, buflen);
4766     st->cr();
4767   }
4768 }
4769 
4770 class PrintOnErrorClosure : public ThreadClosure {
4771   outputStream* _st;
4772   Thread* _current;
4773   char* _buf;
4774   int _buflen;
4775   bool* _found_current;
4776  public:
4777   PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4778                       int buflen, bool* found_current) :
4779    _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4780 
4781   virtual void do_thread(Thread* thread) {
4782     Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4783   }
4784 };
4785 
4786 // Threads::print_on_error() is called by fatal error handler. It's possible
4787 // that VM is not at safepoint and/or current thread is inside signal handler.
4788 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4789 // memory (even in resource area), it might deadlock the error handler.
4790 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4791                              int buflen) {
4792   ThreadsSMRSupport::print_info_on(st);
4793   st->cr();
4794 
4795   bool found_current = false;
4796   st->print_cr("Java Threads: ( => current thread )");
4797   ALL_JAVA_THREADS(thread) {
4798     print_on_error(thread, st, current, buf, buflen, &found_current);
4799   }
4800   st->cr();
4801 
4802   st->print_cr("Other Threads:");
4803   print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4804   print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4805 
4806   PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4807   Universe::heap()->gc_threads_do(&print_closure);
4808 
4809   if (!found_current) {
4810     st->cr();
4811     st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4812     current->print_on_error(st, buf, buflen);
4813     st->cr();
4814   }
4815   st->cr();
4816 
4817   st->print_cr("Threads with active compile tasks:");
4818   print_threads_compiling(st, buf, buflen);
4819 }
4820 
4821 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen, bool short_form) {
4822   ALL_JAVA_THREADS(thread) {
4823     if (thread->is_Compiler_thread()) {
4824       CompilerThread* ct = (CompilerThread*) thread;
4825 
4826       // Keep task in local variable for NULL check.
4827       // ct->_task might be set to NULL by concurring compiler thread
4828       // because it completed the compilation. The task is never freed,
4829       // though, just returned to a free list.
4830       CompileTask* task = ct->task();
4831       if (task != NULL) {
4832         thread->print_name_on_error(st, buf, buflen);
4833         st->print("  ");
4834         task->print(st, NULL, short_form, true);
4835       }
4836     }
4837   }
4838 }
4839 
4840 
4841 // Internal SpinLock and Mutex
4842 // Based on ParkEvent
4843 
4844 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4845 //
4846 // We employ SpinLocks _only for low-contention, fixed-length
4847 // short-duration critical sections where we're concerned
4848 // about native mutex_t or HotSpot Mutex:: latency.
4849 // The mux construct provides a spin-then-block mutual exclusion
4850 // mechanism.
4851 //
4852 // Testing has shown that contention on the ListLock guarding gFreeList
4853 // is common.  If we implement ListLock as a simple SpinLock it's common
4854 // for the JVM to devolve to yielding with little progress.  This is true
4855 // despite the fact that the critical sections protected by ListLock are
4856 // extremely short.
4857 //
4858 // TODO-FIXME: ListLock should be of type SpinLock.
4859 // We should make this a 1st-class type, integrated into the lock
4860 // hierarchy as leaf-locks.  Critically, the SpinLock structure
4861 // should have sufficient padding to avoid false-sharing and excessive
4862 // cache-coherency traffic.
4863 
4864 
4865 typedef volatile int SpinLockT;
4866 
4867 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4868   if (Atomic::cmpxchg (1, adr, 0) == 0) {
4869     return;   // normal fast-path return
4870   }
4871 
4872   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4873   int ctr = 0;
4874   int Yields = 0;
4875   for (;;) {
4876     while (*adr != 0) {
4877       ++ctr;
4878       if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4879         if (Yields > 5) {
4880           os::naked_short_sleep(1);
4881         } else {
4882           os::naked_yield();
4883           ++Yields;
4884         }
4885       } else {
4886         SpinPause();
4887       }
4888     }
4889     if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4890   }
4891 }
4892 
4893 void Thread::SpinRelease(volatile int * adr) {
4894   assert(*adr != 0, "invariant");
4895   OrderAccess::fence();      // guarantee at least release consistency.
4896   // Roach-motel semantics.
4897   // It's safe if subsequent LDs and STs float "up" into the critical section,
4898   // but prior LDs and STs within the critical section can't be allowed
4899   // to reorder or float past the ST that releases the lock.
4900   // Loads and stores in the critical section - which appear in program
4901   // order before the store that releases the lock - must also appear
4902   // before the store that releases the lock in memory visibility order.
4903   // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4904   // the ST of 0 into the lock-word which releases the lock, so fence
4905   // more than covers this on all platforms.
4906   *adr = 0;
4907 }
4908 
4909 // muxAcquire and muxRelease:
4910 //
4911 // *  muxAcquire and muxRelease support a single-word lock-word construct.
4912 //    The LSB of the word is set IFF the lock is held.
4913 //    The remainder of the word points to the head of a singly-linked list
4914 //    of threads blocked on the lock.
4915 //
4916 // *  The current implementation of muxAcquire-muxRelease uses its own
4917 //    dedicated Thread._MuxEvent instance.  If we're interested in
4918 //    minimizing the peak number of extant ParkEvent instances then
4919 //    we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4920 //    as certain invariants were satisfied.  Specifically, care would need
4921 //    to be taken with regards to consuming unpark() "permits".
4922 //    A safe rule of thumb is that a thread would never call muxAcquire()
4923 //    if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4924 //    park().  Otherwise the _ParkEvent park() operation in muxAcquire() could
4925 //    consume an unpark() permit intended for monitorenter, for instance.
4926 //    One way around this would be to widen the restricted-range semaphore
4927 //    implemented in park().  Another alternative would be to provide
4928 //    multiple instances of the PlatformEvent() for each thread.  One
4929 //    instance would be dedicated to muxAcquire-muxRelease, for instance.
4930 //
4931 // *  Usage:
4932 //    -- Only as leaf locks
4933 //    -- for short-term locking only as muxAcquire does not perform
4934 //       thread state transitions.
4935 //
4936 // Alternatives:
4937 // *  We could implement muxAcquire and muxRelease with MCS or CLH locks
4938 //    but with parking or spin-then-park instead of pure spinning.
4939 // *  Use Taura-Oyama-Yonenzawa locks.
4940 // *  It's possible to construct a 1-0 lock if we encode the lockword as
4941 //    (List,LockByte).  Acquire will CAS the full lockword while Release
4942 //    will STB 0 into the LockByte.  The 1-0 scheme admits stranding, so
4943 //    acquiring threads use timers (ParkTimed) to detect and recover from
4944 //    the stranding window.  Thread/Node structures must be aligned on 256-byte
4945 //    boundaries by using placement-new.
4946 // *  Augment MCS with advisory back-link fields maintained with CAS().
4947 //    Pictorially:  LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4948 //    The validity of the backlinks must be ratified before we trust the value.
4949 //    If the backlinks are invalid the exiting thread must back-track through the
4950 //    the forward links, which are always trustworthy.
4951 // *  Add a successor indication.  The LockWord is currently encoded as
4952 //    (List, LOCKBIT:1).  We could also add a SUCCBIT or an explicit _succ variable
4953 //    to provide the usual futile-wakeup optimization.
4954 //    See RTStt for details.
4955 //
4956 
4957 
4958 const intptr_t LOCKBIT = 1;
4959 
4960 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4961   intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4962   if (w == 0) return;
4963   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4964     return;
4965   }
4966 
4967   ParkEvent * const Self = Thread::current()->_MuxEvent;
4968   assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4969   for (;;) {
4970     int its = (os::is_MP() ? 100 : 0) + 1;
4971 
4972     // Optional spin phase: spin-then-park strategy
4973     while (--its >= 0) {
4974       w = *Lock;
4975       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4976         return;
4977       }
4978     }
4979 
4980     Self->reset();
4981     Self->OnList = intptr_t(Lock);
4982     // The following fence() isn't _strictly necessary as the subsequent
4983     // CAS() both serializes execution and ratifies the fetched *Lock value.
4984     OrderAccess::fence();
4985     for (;;) {
4986       w = *Lock;
4987       if ((w & LOCKBIT) == 0) {
4988         if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4989           Self->OnList = 0;   // hygiene - allows stronger asserts
4990           return;
4991         }
4992         continue;      // Interference -- *Lock changed -- Just retry
4993       }
4994       assert(w & LOCKBIT, "invariant");
4995       Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4996       if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4997     }
4998 
4999     while (Self->OnList != 0) {
5000       Self->park();
5001     }
5002   }
5003 }
5004 
5005 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
5006   intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
5007   if (w == 0) return;
5008   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5009     return;
5010   }
5011 
5012   ParkEvent * ReleaseAfter = NULL;
5013   if (ev == NULL) {
5014     ev = ReleaseAfter = ParkEvent::Allocate(NULL);
5015   }
5016   assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
5017   for (;;) {
5018     guarantee(ev->OnList == 0, "invariant");
5019     int its = (os::is_MP() ? 100 : 0) + 1;
5020 
5021     // Optional spin phase: spin-then-park strategy
5022     while (--its >= 0) {
5023       w = *Lock;
5024       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5025         if (ReleaseAfter != NULL) {
5026           ParkEvent::Release(ReleaseAfter);
5027         }
5028         return;
5029       }
5030     }
5031 
5032     ev->reset();
5033     ev->OnList = intptr_t(Lock);
5034     // The following fence() isn't _strictly necessary as the subsequent
5035     // CAS() both serializes execution and ratifies the fetched *Lock value.
5036     OrderAccess::fence();
5037     for (;;) {
5038       w = *Lock;
5039       if ((w & LOCKBIT) == 0) {
5040         if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5041           ev->OnList = 0;
5042           // We call ::Release while holding the outer lock, thus
5043           // artificially lengthening the critical section.
5044           // Consider deferring the ::Release() until the subsequent unlock(),
5045           // after we've dropped the outer lock.
5046           if (ReleaseAfter != NULL) {
5047             ParkEvent::Release(ReleaseAfter);
5048           }
5049           return;
5050         }
5051         continue;      // Interference -- *Lock changed -- Just retry
5052       }
5053       assert(w & LOCKBIT, "invariant");
5054       ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
5055       if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
5056     }
5057 
5058     while (ev->OnList != 0) {
5059       ev->park();
5060     }
5061   }
5062 }
5063 
5064 // Release() must extract a successor from the list and then wake that thread.
5065 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
5066 // similar to that used by ParkEvent::Allocate() and ::Release().  DMR-based
5067 // Release() would :
5068 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
5069 // (B) Extract a successor from the private list "in-hand"
5070 // (C) attempt to CAS() the residual back into *Lock over null.
5071 //     If there were any newly arrived threads and the CAS() would fail.
5072 //     In that case Release() would detach the RATs, re-merge the list in-hand
5073 //     with the RATs and repeat as needed.  Alternately, Release() might
5074 //     detach and extract a successor, but then pass the residual list to the wakee.
5075 //     The wakee would be responsible for reattaching and remerging before it
5076 //     competed for the lock.
5077 //
5078 // Both "pop" and DMR are immune from ABA corruption -- there can be
5079 // multiple concurrent pushers, but only one popper or detacher.
5080 // This implementation pops from the head of the list.  This is unfair,
5081 // but tends to provide excellent throughput as hot threads remain hot.
5082 // (We wake recently run threads first).
5083 //
5084 // All paths through muxRelease() will execute a CAS.
5085 // Release consistency -- We depend on the CAS in muxRelease() to provide full
5086 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
5087 // executed within the critical section are complete and globally visible before the
5088 // store (CAS) to the lock-word that releases the lock becomes globally visible.
5089 void Thread::muxRelease(volatile intptr_t * Lock)  {
5090   for (;;) {
5091     const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
5092     assert(w & LOCKBIT, "invariant");
5093     if (w == LOCKBIT) return;
5094     ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
5095     assert(List != NULL, "invariant");
5096     assert(List->OnList == intptr_t(Lock), "invariant");
5097     ParkEvent * const nxt = List->ListNext;
5098     guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
5099 
5100     // The following CAS() releases the lock and pops the head element.
5101     // The CAS() also ratifies the previously fetched lock-word value.
5102     if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
5103       continue;
5104     }
5105     List->OnList = 0;
5106     OrderAccess::fence();
5107     List->unpark();
5108     return;
5109   }
5110 }
5111 
5112 
5113 void Threads::verify() {
5114   ALL_JAVA_THREADS(p) {
5115     p->verify();
5116   }
5117   VMThread* thread = VMThread::vm_thread();
5118   if (thread != NULL) thread->verify();
5119 }