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 "classfile/classLoader.hpp"
  28 #include "classfile/javaClasses.hpp"
  29 #include "classfile/moduleEntry.hpp"
  30 #include "classfile/systemDictionary.hpp"
  31 #include "classfile/vmSymbols.hpp"
  32 #include "code/codeCache.hpp"
  33 #include "code/scopeDesc.hpp"
  34 #include "compiler/compileBroker.hpp"
  35 #include "compiler/compileTask.hpp"
  36 #include "gc/shared/barrierSet.hpp"
  37 #include "gc/shared/gcId.hpp"
  38 #include "gc/shared/gcLocker.inline.hpp"
  39 #include "gc/shared/workgroup.hpp"
  40 #include "interpreter/interpreter.hpp"
  41 #include "interpreter/linkResolver.hpp"
  42 #include "interpreter/oopMapCache.hpp"
  43 #include "jfr/jfrEvents.hpp"
  44 #include "jvmtifiles/jvmtiEnv.hpp"
  45 #include "logging/log.hpp"
  46 #include "logging/logConfiguration.hpp"
  47 #include "logging/logStream.hpp"
  48 #include "memory/allocation.inline.hpp"
  49 #include "memory/metaspaceShared.hpp"
  50 #include "memory/oopFactory.hpp"
  51 #include "memory/resourceArea.hpp"
  52 #include "memory/universe.hpp"
  53 #include "oops/access.inline.hpp"
  54 #include "oops/instanceKlass.hpp"
  55 #include "oops/objArrayOop.hpp"
  56 #include "oops/oop.inline.hpp"
  57 #include "oops/symbol.hpp"
  58 #include "oops/typeArrayOop.inline.hpp"
  59 #include "oops/verifyOopClosure.hpp"
  60 #include "prims/jvm_misc.hpp"
  61 #include "prims/jvmtiExport.hpp"
  62 #include "prims/jvmtiThreadState.hpp"
  63 #include "runtime/arguments.hpp"
  64 #include "runtime/atomic.hpp"
  65 #include "runtime/biasedLocking.hpp"
  66 #include "runtime/fieldDescriptor.inline.hpp"
  67 #include "runtime/flags/jvmFlagConstraintList.hpp"
  68 #include "runtime/flags/jvmFlagRangeList.hpp"
  69 #include "runtime/flags/jvmFlagWriteableList.hpp"
  70 #include "runtime/deoptimization.hpp"
  71 #include "runtime/frame.inline.hpp"
  72 #include "runtime/handles.inline.hpp"
  73 #include "runtime/handshake.hpp"
  74 #include "runtime/init.hpp"
  75 #include "runtime/interfaceSupport.inline.hpp"
  76 #include "runtime/java.hpp"
  77 #include "runtime/javaCalls.hpp"
  78 #include "runtime/jniHandles.inline.hpp"
  79 #include "runtime/jniPeriodicChecker.hpp"
  80 #include "runtime/memprofiler.hpp"
  81 #include "runtime/mutexLocker.hpp"
  82 #include "runtime/objectMonitor.hpp"
  83 #include "runtime/orderAccess.hpp"
  84 #include "runtime/osThread.hpp"
  85 #include "runtime/prefetch.inline.hpp"
  86 #include "runtime/safepoint.hpp"
  87 #include "runtime/safepointMechanism.inline.hpp"
  88 #include "runtime/safepointVerifiers.hpp"
  89 #include "runtime/sharedRuntime.hpp"
  90 #include "runtime/statSampler.hpp"
  91 #include "runtime/stubRoutines.hpp"
  92 #include "runtime/sweeper.hpp"
  93 #include "runtime/task.hpp"
  94 #include "runtime/thread.inline.hpp"
  95 #include "runtime/threadCritical.hpp"
  96 #include "runtime/threadSMR.inline.hpp"
  97 #include "runtime/threadStatisticalInfo.hpp"
  98 #include "runtime/timer.hpp"
  99 #include "runtime/timerTrace.hpp"
 100 #include "runtime/vframe.inline.hpp"
 101 #include "runtime/vframeArray.hpp"
 102 #include "runtime/vframe_hp.hpp"
 103 #include "runtime/vmThread.hpp"
 104 #include "runtime/vmOperations.hpp"
 105 #include "runtime/vm_version.hpp"
 106 #include "services/attachListener.hpp"
 107 #include "services/management.hpp"
 108 #include "services/memTracker.hpp"
 109 #include "services/threadService.hpp"
 110 #include "utilities/align.hpp"
 111 #include "utilities/copy.hpp"
 112 #include "utilities/defaultStream.hpp"
 113 #include "utilities/dtrace.hpp"
 114 #include "utilities/events.hpp"
 115 #include "utilities/macros.hpp"
 116 #include "utilities/preserveException.hpp"
 117 #include "utilities/singleWriterSynchronizer.hpp"
 118 #include "utilities/vmError.hpp"
 119 #if INCLUDE_JVMCI
 120 #include "jvmci/jvmci.hpp"
 121 #include "jvmci/jvmciEnv.hpp"
 122 #endif
 123 #ifdef COMPILER1
 124 #include "c1/c1_Compiler.hpp"
 125 #endif
 126 #ifdef COMPILER2
 127 #include "opto/c2compiler.hpp"
 128 #include "opto/idealGraphPrinter.hpp"
 129 #endif
 130 #if INCLUDE_RTM_OPT
 131 #include "runtime/rtmLocking.hpp"
 132 #endif
 133 #if INCLUDE_JFR
 134 #include "jfr/jfr.hpp"
 135 #endif
 136 
 137 // Initialization after module runtime initialization
 138 void universe_post_module_init();  // must happen after call_initPhase2
 139 
 140 #ifdef DTRACE_ENABLED
 141 
 142 // Only bother with this argument setup if dtrace is available
 143 
 144   #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
 145   #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
 146 
 147   #define DTRACE_THREAD_PROBE(probe, javathread)                           \
 148     {                                                                      \
 149       ResourceMark rm(this);                                               \
 150       int len = 0;                                                         \
 151       const char* name = (javathread)->get_thread_name();                  \
 152       len = strlen(name);                                                  \
 153       HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */               \
 154         (char *) name, len,                                                \
 155         java_lang_Thread::thread_id((javathread)->threadObj()),            \
 156         (uintptr_t) (javathread)->osthread()->thread_id(),                 \
 157         java_lang_Thread::is_daemon((javathread)->threadObj()));           \
 158     }
 159 
 160 #else //  ndef DTRACE_ENABLED
 161 
 162   #define DTRACE_THREAD_PROBE(probe, javathread)
 163 
 164 #endif // ndef DTRACE_ENABLED
 165 
 166 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 167 // Current thread is maintained as a thread-local variable
 168 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
 169 #endif
 170 
 171 // ======= Thread ========
 172 // Support for forcing alignment of thread objects for biased locking
 173 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
 174   if (UseBiasedLocking) {
 175     const int alignment = markOopDesc::biased_lock_alignment;
 176     size_t aligned_size = size + (alignment - sizeof(intptr_t));
 177     void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
 178                                           : AllocateHeap(aligned_size, flags, CURRENT_PC,
 179                                                          AllocFailStrategy::RETURN_NULL);
 180     void* aligned_addr     = align_up(real_malloc_addr, alignment);
 181     assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
 182            ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
 183            "JavaThread alignment code overflowed allocated storage");
 184     if (aligned_addr != real_malloc_addr) {
 185       log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
 186                               p2i(real_malloc_addr),
 187                               p2i(aligned_addr));
 188     }
 189     ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
 190     return aligned_addr;
 191   } else {
 192     return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
 193                        : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
 194   }
 195 }
 196 
 197 void Thread::operator delete(void* p) {
 198   if (UseBiasedLocking) {
 199     FreeHeap(((Thread*) p)->_real_malloc_address);
 200   } else {
 201     FreeHeap(p);
 202   }
 203 }
 204 
 205 void JavaThread::smr_delete() {
 206   if (_on_thread_list) {
 207     ThreadsSMRSupport::smr_delete(this);
 208   } else {
 209     delete this;
 210   }
 211 }
 212 
 213 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
 214 // JavaThread
 215 
 216 DEBUG_ONLY(Thread* Thread::_starting_thread = NULL;)
 217 
 218 Thread::Thread() {
 219 
 220   DEBUG_ONLY(_run_state = PRE_CALL_RUN;)
 221 
 222   // stack and get_thread
 223   set_stack_base(NULL);
 224   set_stack_size(0);
 225   set_self_raw_id(0);
 226   set_lgrp_id(-1);
 227   DEBUG_ONLY(clear_suspendible_thread();)
 228 
 229   // allocated data structures
 230   set_osthread(NULL);
 231   set_resource_area(new (mtThread)ResourceArea());
 232   DEBUG_ONLY(_current_resource_mark = NULL;)
 233   set_handle_area(new (mtThread) HandleArea(NULL));
 234   set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
 235   set_active_handles(NULL);
 236   set_free_handle_block(NULL);
 237   set_last_handle_mark(NULL);
 238   DEBUG_ONLY(_missed_ic_stub_refill_verifier = NULL);
 239 
 240   // Initial value of zero ==> never claimed.
 241   _threads_do_token = 0;
 242   _threads_hazard_ptr = NULL;
 243   _threads_list_ptr = NULL;
 244   _nested_threads_hazard_ptr_cnt = 0;
 245   _rcu_counter = 0;
 246 
 247   // the handle mark links itself to last_handle_mark
 248   new HandleMark(this);
 249 
 250   // plain initialization
 251   debug_only(_owned_locks = NULL;)
 252   debug_only(_allow_allocation_count = 0;)
 253   NOT_PRODUCT(_allow_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 
1014 #endif
1015 
1016 #ifndef PRODUCT
1017 
1018 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially
1019 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
1020 // no locks which allow_vm_block's are held
1021 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
1022   // Check if current thread is allowed to block at a safepoint
1023   if (!(_allow_safepoint_count == 0)) {
1024     fatal("Possible safepoint reached by thread that does not allow it");
1025   }
1026   if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
1027     fatal("LEAF method calling lock?");
1028   }
1029 
1030 #ifdef ASSERT
1031   if (potential_vm_operation && is_Java_thread()
1032       && !Universe::is_bootstrapping()) {
1033     // Make sure we do not hold any locks that the VM thread also uses.
1034     // This could potentially lead to deadlocks
1035     for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
1036       // Threads_lock is special, since the safepoint synchronization will not start before this is
1037       // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
1038       // since it is used to transfer control between JavaThreads and the VMThread
1039       // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
1040       if ((cur->allow_vm_block() &&
1041            cur != Threads_lock &&
1042            cur != Compile_lock &&               // Temporary: should not be necessary when we get separate compilation
1043            cur != VMOperationRequest_lock &&
1044            cur != VMOperationQueue_lock) ||
1045            cur->rank() == Mutex::special) {
1046         fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
1047       }
1048     }
1049   }
1050 
1051   if (GCALotAtAllSafepoints) {
1052     // We could enter a safepoint here and thus have a gc
1053     InterfaceSupport::check_gc_alot();
1054   }
1055 #endif
1056 }
1057 #endif
1058 
1059 bool Thread::is_in_stack(address adr) const {
1060   assert(Thread::current() == this, "is_in_stack can only be called from current thread");
1061   address end = os::current_stack_pointer();
1062   // Allow non Java threads to call this without stack_base
1063   if (_stack_base == NULL) return true;
1064   if (stack_base() >= adr && adr >= end) return true;
1065 
1066   return false;
1067 }
1068 
1069 bool Thread::is_in_usable_stack(address adr) const {
1070   size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1071   size_t usable_stack_size = _stack_size - stack_guard_size;
1072 
1073   return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1074 }
1075 
1076 
1077 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1078 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1079 // used for compilation in the future. If that change is made, the need for these methods
1080 // should be revisited, and they should be removed if possible.
1081 
1082 bool Thread::is_lock_owned(address adr) const {
1083   return on_local_stack(adr);
1084 }
1085 
1086 bool Thread::set_as_starting_thread() {
1087   assert(_starting_thread == NULL, "already initialized: "
1088          "_starting_thread=" INTPTR_FORMAT, p2i(_starting_thread));
1089   // NOTE: this must be called inside the main thread.
1090   DEBUG_ONLY(_starting_thread = this;)
1091   return os::create_main_thread((JavaThread*)this);
1092 }
1093 
1094 static void initialize_class(Symbol* class_name, TRAPS) {
1095   Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1096   InstanceKlass::cast(klass)->initialize(CHECK);
1097 }
1098 
1099 
1100 // Creates the initial ThreadGroup
1101 static Handle create_initial_thread_group(TRAPS) {
1102   Handle system_instance = JavaCalls::construct_new_instance(
1103                             SystemDictionary::ThreadGroup_klass(),
1104                             vmSymbols::void_method_signature(),
1105                             CHECK_NH);
1106   Universe::set_system_thread_group(system_instance());
1107 
1108   Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1109   Handle main_instance = JavaCalls::construct_new_instance(
1110                             SystemDictionary::ThreadGroup_klass(),
1111                             vmSymbols::threadgroup_string_void_signature(),
1112                             system_instance,
1113                             string,
1114                             CHECK_NH);
1115   return main_instance;
1116 }
1117 
1118 // Creates the initial Thread
1119 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1120                                  TRAPS) {
1121   InstanceKlass* ik = SystemDictionary::Thread_klass();
1122   assert(ik->is_initialized(), "must be");
1123   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1124 
1125   // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1126   // constructor calls Thread.current(), which must be set here for the
1127   // initial thread.
1128   java_lang_Thread::set_thread(thread_oop(), thread);
1129   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1130   thread->set_threadObj(thread_oop());
1131 
1132   Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1133 
1134   JavaValue result(T_VOID);
1135   JavaCalls::call_special(&result, thread_oop,
1136                           ik,
1137                           vmSymbols::object_initializer_name(),
1138                           vmSymbols::threadgroup_string_void_signature(),
1139                           thread_group,
1140                           string,
1141                           CHECK_NULL);
1142   return thread_oop();
1143 }
1144 
1145 char java_runtime_name[128] = "";
1146 char java_runtime_version[128] = "";
1147 
1148 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1149 static const char* get_java_runtime_name(TRAPS) {
1150   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1151                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1152   fieldDescriptor fd;
1153   bool found = k != NULL &&
1154                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1155                                                         vmSymbols::string_signature(), &fd);
1156   if (found) {
1157     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1158     if (name_oop == NULL) {
1159       return NULL;
1160     }
1161     const char* name = java_lang_String::as_utf8_string(name_oop,
1162                                                         java_runtime_name,
1163                                                         sizeof(java_runtime_name));
1164     return name;
1165   } else {
1166     return NULL;
1167   }
1168 }
1169 
1170 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1171 static const char* get_java_runtime_version(TRAPS) {
1172   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1173                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1174   fieldDescriptor fd;
1175   bool found = k != NULL &&
1176                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1177                                                         vmSymbols::string_signature(), &fd);
1178   if (found) {
1179     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1180     if (name_oop == NULL) {
1181       return NULL;
1182     }
1183     const char* name = java_lang_String::as_utf8_string(name_oop,
1184                                                         java_runtime_version,
1185                                                         sizeof(java_runtime_version));
1186     return name;
1187   } else {
1188     return NULL;
1189   }
1190 }
1191 
1192 // General purpose hook into Java code, run once when the VM is initialized.
1193 // The Java library method itself may be changed independently from the VM.
1194 static void call_postVMInitHook(TRAPS) {
1195   Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1196   if (klass != NULL) {
1197     JavaValue result(T_VOID);
1198     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1199                            vmSymbols::void_method_signature(),
1200                            CHECK);
1201   }
1202 }
1203 
1204 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1205                                     bool daemon, TRAPS) {
1206   assert(thread_group.not_null(), "thread group should be specified");
1207   assert(threadObj() == NULL, "should only create Java thread object once");
1208 
1209   InstanceKlass* ik = SystemDictionary::Thread_klass();
1210   assert(ik->is_initialized(), "must be");
1211   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1212 
1213   // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon.
1214   // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1215   // constructor calls Thread.current(), which must be set here.
1216   java_lang_Thread::set_thread(thread_oop(), this);
1217   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1218   set_threadObj(thread_oop());
1219 
1220   JavaValue result(T_VOID);
1221   if (thread_name != NULL) {
1222     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1223     // Thread gets assigned specified name and null target
1224     JavaCalls::call_special(&result,
1225                             thread_oop,
1226                             ik,
1227                             vmSymbols::object_initializer_name(),
1228                             vmSymbols::threadgroup_string_void_signature(),
1229                             thread_group,
1230                             name,
1231                             THREAD);
1232   } else {
1233     // Thread gets assigned name "Thread-nnn" and null target
1234     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1235     JavaCalls::call_special(&result,
1236                             thread_oop,
1237                             ik,
1238                             vmSymbols::object_initializer_name(),
1239                             vmSymbols::threadgroup_runnable_void_signature(),
1240                             thread_group,
1241                             Handle(),
1242                             THREAD);
1243   }
1244 
1245 
1246   if (daemon) {
1247     java_lang_Thread::set_daemon(thread_oop());
1248   }
1249 
1250   if (HAS_PENDING_EXCEPTION) {
1251     return;
1252   }
1253 
1254   Klass* group =  SystemDictionary::ThreadGroup_klass();
1255   Handle threadObj(THREAD, this->threadObj());
1256 
1257   JavaCalls::call_special(&result,
1258                           thread_group,
1259                           group,
1260                           vmSymbols::add_method_name(),
1261                           vmSymbols::thread_void_signature(),
1262                           threadObj,          // Arg 1
1263                           THREAD);
1264 }
1265 
1266 // List of all NonJavaThreads and safe iteration over that list.
1267 
1268 class NonJavaThread::List {
1269 public:
1270   NonJavaThread* volatile _head;
1271   SingleWriterSynchronizer _protect;
1272 
1273   List() : _head(NULL), _protect() {}
1274 };
1275 
1276 NonJavaThread::List NonJavaThread::_the_list;
1277 
1278 NonJavaThread::Iterator::Iterator() :
1279   _protect_enter(_the_list._protect.enter()),
1280   _current(OrderAccess::load_acquire(&_the_list._head))
1281 {}
1282 
1283 NonJavaThread::Iterator::~Iterator() {
1284   _the_list._protect.exit(_protect_enter);
1285 }
1286 
1287 void NonJavaThread::Iterator::step() {
1288   assert(!end(), "precondition");
1289   _current = OrderAccess::load_acquire(&_current->_next);
1290 }
1291 
1292 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) {
1293   assert(BarrierSet::barrier_set() != NULL, "NonJavaThread created too soon!");
1294 }
1295 
1296 NonJavaThread::~NonJavaThread() { }
1297 
1298 void NonJavaThread::add_to_the_list() {
1299   MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1300   // Initialize BarrierSet-related data before adding to list.
1301   BarrierSet::barrier_set()->on_thread_attach(this);
1302   OrderAccess::release_store(&_next, _the_list._head);
1303   OrderAccess::release_store(&_the_list._head, this);
1304 }
1305 
1306 void NonJavaThread::remove_from_the_list() {
1307   {
1308     MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1309     // Cleanup BarrierSet-related data before removing from list.
1310     BarrierSet::barrier_set()->on_thread_detach(this);
1311     NonJavaThread* volatile* p = &_the_list._head;
1312     for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) {
1313       if (t == this) {
1314         *p = _next;
1315         break;
1316       }
1317     }
1318   }
1319   // Wait for any in-progress iterators.  Concurrent synchronize is not
1320   // allowed, so do it while holding a dedicated lock.  Outside and distinct
1321   // from NJTList_lock in case an iteration attempts to lock it.
1322   MutexLocker ml(NonJavaThreadsListSync_lock, Mutex::_no_safepoint_check_flag);
1323   _the_list._protect.synchronize();
1324   _next = NULL;                 // Safe to drop the link now.
1325 }
1326 
1327 void NonJavaThread::pre_run() {
1328   add_to_the_list();
1329 
1330   // This is slightly odd in that NamedThread is a subclass, but
1331   // in fact name() is defined in Thread
1332   assert(this->name() != NULL, "thread name was not set before it was started");
1333   this->set_native_thread_name(this->name());
1334 }
1335 
1336 void NonJavaThread::post_run() {
1337   JFR_ONLY(Jfr::on_thread_exit(this);)
1338   remove_from_the_list();
1339   // Ensure thread-local-storage is cleared before termination.
1340   Thread::clear_thread_current();
1341 }
1342 
1343 // NamedThread --  non-JavaThread subclasses with multiple
1344 // uniquely named instances should derive from this.
1345 NamedThread::NamedThread() :
1346   NonJavaThread(),
1347   _name(NULL),
1348   _processed_thread(NULL),
1349   _gc_id(GCId::undefined())
1350 {}
1351 
1352 NamedThread::~NamedThread() {
1353   if (_name != NULL) {
1354     FREE_C_HEAP_ARRAY(char, _name);
1355     _name = NULL;
1356   }
1357 }
1358 
1359 void NamedThread::set_name(const char* format, ...) {
1360   guarantee(_name == NULL, "Only get to set name once.");
1361   _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1362   guarantee(_name != NULL, "alloc failure");
1363   va_list ap;
1364   va_start(ap, format);
1365   jio_vsnprintf(_name, max_name_len, format, ap);
1366   va_end(ap);
1367 }
1368 
1369 void NamedThread::print_on(outputStream* st) const {
1370   st->print("\"%s\" ", name());
1371   Thread::print_on(st);
1372   st->cr();
1373 }
1374 
1375 
1376 // ======= WatcherThread ========
1377 
1378 // The watcher thread exists to simulate timer interrupts.  It should
1379 // be replaced by an abstraction over whatever native support for
1380 // timer interrupts exists on the platform.
1381 
1382 WatcherThread* WatcherThread::_watcher_thread   = NULL;
1383 bool WatcherThread::_startable = false;
1384 volatile bool  WatcherThread::_should_terminate = false;
1385 
1386 WatcherThread::WatcherThread() : NonJavaThread() {
1387   assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1388   if (os::create_thread(this, os::watcher_thread)) {
1389     _watcher_thread = this;
1390 
1391     // Set the watcher thread to the highest OS priority which should not be
1392     // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1393     // is created. The only normal thread using this priority is the reference
1394     // handler thread, which runs for very short intervals only.
1395     // If the VMThread's priority is not lower than the WatcherThread profiling
1396     // will be inaccurate.
1397     os::set_priority(this, MaxPriority);
1398     if (!DisableStartThread) {
1399       os::start_thread(this);
1400     }
1401   }
1402 }
1403 
1404 int WatcherThread::sleep() const {
1405   // The WatcherThread does not participate in the safepoint protocol
1406   // for the PeriodicTask_lock because it is not a JavaThread.
1407   MonitorLocker ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1408 
1409   if (_should_terminate) {
1410     // check for termination before we do any housekeeping or wait
1411     return 0;  // we did not sleep.
1412   }
1413 
1414   // remaining will be zero if there are no tasks,
1415   // causing the WatcherThread to sleep until a task is
1416   // enrolled
1417   int remaining = PeriodicTask::time_to_wait();
1418   int time_slept = 0;
1419 
1420   // we expect this to timeout - we only ever get unparked when
1421   // we should terminate or when a new task has been enrolled
1422   OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1423 
1424   jlong time_before_loop = os::javaTimeNanos();
1425 
1426   while (true) {
1427     bool timedout = ml.wait(remaining);
1428     jlong now = os::javaTimeNanos();
1429 
1430     if (remaining == 0) {
1431       // if we didn't have any tasks we could have waited for a long time
1432       // consider the time_slept zero and reset time_before_loop
1433       time_slept = 0;
1434       time_before_loop = now;
1435     } else {
1436       // need to recalculate since we might have new tasks in _tasks
1437       time_slept = (int) ((now - time_before_loop) / 1000000);
1438     }
1439 
1440     // Change to task list or spurious wakeup of some kind
1441     if (timedout || _should_terminate) {
1442       break;
1443     }
1444 
1445     remaining = PeriodicTask::time_to_wait();
1446     if (remaining == 0) {
1447       // Last task was just disenrolled so loop around and wait until
1448       // another task gets enrolled
1449       continue;
1450     }
1451 
1452     remaining -= time_slept;
1453     if (remaining <= 0) {
1454       break;
1455     }
1456   }
1457 
1458   return time_slept;
1459 }
1460 
1461 void WatcherThread::run() {
1462   assert(this == watcher_thread(), "just checking");
1463 
1464   this->set_active_handles(JNIHandleBlock::allocate_block());
1465   while (true) {
1466     assert(watcher_thread() == Thread::current(), "thread consistency check");
1467     assert(watcher_thread() == this, "thread consistency check");
1468 
1469     // Calculate how long it'll be until the next PeriodicTask work
1470     // should be done, and sleep that amount of time.
1471     int time_waited = sleep();
1472 
1473     if (VMError::is_error_reported()) {
1474       // A fatal error has happened, the error handler(VMError::report_and_die)
1475       // should abort JVM after creating an error log file. However in some
1476       // rare cases, the error handler itself might deadlock. Here periodically
1477       // check for error reporting timeouts, and if it happens, just proceed to
1478       // abort the VM.
1479 
1480       // This code is in WatcherThread because WatcherThread wakes up
1481       // periodically so the fatal error handler doesn't need to do anything;
1482       // also because the WatcherThread is less likely to crash than other
1483       // threads.
1484 
1485       for (;;) {
1486         // Note: we use naked sleep in this loop because we want to avoid using
1487         // any kind of VM infrastructure which may be broken at this point.
1488         if (VMError::check_timeout()) {
1489           // We hit error reporting timeout. Error reporting was interrupted and
1490           // will be wrapping things up now (closing files etc). Give it some more
1491           // time, then quit the VM.
1492           os::naked_short_sleep(200);
1493           // Print a message to stderr.
1494           fdStream err(defaultStream::output_fd());
1495           err.print_raw_cr("# [ timer expired, abort... ]");
1496           // skip atexit/vm_exit/vm_abort hooks
1497           os::die();
1498         }
1499 
1500         // Wait a second, then recheck for timeout.
1501         os::naked_short_sleep(999);
1502       }
1503     }
1504 
1505     if (_should_terminate) {
1506       // check for termination before posting the next tick
1507       break;
1508     }
1509 
1510     PeriodicTask::real_time_tick(time_waited);
1511   }
1512 
1513   // Signal that it is terminated
1514   {
1515     MutexLocker mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1516     _watcher_thread = NULL;
1517     Terminator_lock->notify_all();
1518   }
1519 }
1520 
1521 void WatcherThread::start() {
1522   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1523 
1524   if (watcher_thread() == NULL && _startable) {
1525     _should_terminate = false;
1526     // Create the single instance of WatcherThread
1527     new WatcherThread();
1528   }
1529 }
1530 
1531 void WatcherThread::make_startable() {
1532   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1533   _startable = true;
1534 }
1535 
1536 void WatcherThread::stop() {
1537   {
1538     // Follow normal safepoint aware lock enter protocol since the
1539     // WatcherThread is stopped by another JavaThread.
1540     MutexLocker ml(PeriodicTask_lock);
1541     _should_terminate = true;
1542 
1543     WatcherThread* watcher = watcher_thread();
1544     if (watcher != NULL) {
1545       // unpark the WatcherThread so it can see that it should terminate
1546       watcher->unpark();
1547     }
1548   }
1549 
1550   MonitorLocker mu(Terminator_lock);
1551 
1552   while (watcher_thread() != NULL) {
1553     // This wait should make safepoint checks, wait without a timeout,
1554     // and wait as a suspend-equivalent condition.
1555     mu.wait(0, Mutex::_as_suspend_equivalent_flag);
1556   }
1557 }
1558 
1559 void WatcherThread::unpark() {
1560   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1561   PeriodicTask_lock->notify();
1562 }
1563 
1564 void WatcherThread::print_on(outputStream* st) const {
1565   st->print("\"%s\" ", name());
1566   Thread::print_on(st);
1567   st->cr();
1568 }
1569 
1570 // ======= JavaThread ========
1571 
1572 #if INCLUDE_JVMCI
1573 
1574 jlong* JavaThread::_jvmci_old_thread_counters;
1575 
1576 bool jvmci_counters_include(JavaThread* thread) {
1577   return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1578 }
1579 
1580 void JavaThread::collect_counters(jlong* array, int length) {
1581   assert(length == JVMCICounterSize, "wrong value");
1582   for (int i = 0; i < length; i++) {
1583     array[i] = _jvmci_old_thread_counters[i];
1584   }
1585   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) {
1586     if (jvmci_counters_include(tp)) {
1587       for (int i = 0; i < length; i++) {
1588         array[i] += tp->_jvmci_counters[i];
1589       }
1590     }
1591   }
1592 }
1593 
1594 #endif // INCLUDE_JVMCI
1595 
1596 // A JavaThread is a normal Java thread
1597 
1598 void JavaThread::initialize() {
1599   // Initialize fields
1600 
1601   set_saved_exception_pc(NULL);
1602   set_threadObj(NULL);
1603   _anchor.clear();
1604   set_entry_point(NULL);
1605   set_jni_functions(jni_functions());
1606   set_callee_target(NULL);
1607   set_vm_result(NULL);
1608   set_vm_result_2(NULL);
1609   set_vframe_array_head(NULL);
1610   set_vframe_array_last(NULL);
1611   set_deferred_locals(NULL);
1612   set_deopt_mark(NULL);
1613   set_deopt_compiled_method(NULL);
1614   clear_must_deopt_id();
1615   set_monitor_chunks(NULL);
1616   _on_thread_list = false;
1617   set_thread_state(_thread_new);
1618   _terminated = _not_terminated;
1619   _array_for_gc = NULL;
1620   _suspend_equivalent = false;
1621   _in_deopt_handler = 0;
1622   _doing_unsafe_access = false;
1623   _stack_guard_state = stack_guard_unused;
1624 #if INCLUDE_JVMCI
1625   _pending_monitorenter = false;
1626   _pending_deoptimization = -1;
1627   _pending_failed_speculation = 0;
1628   _pending_transfer_to_interpreter = false;
1629   _in_retryable_allocation = false;
1630   _jvmci._alternate_call_target = NULL;
1631   assert(_jvmci._implicit_exception_pc == NULL, "must be");
1632   if (JVMCICounterSize > 0) {
1633     _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1634     memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1635   } else {
1636     _jvmci_counters = NULL;
1637   }
1638 #endif // INCLUDE_JVMCI
1639   _reserved_stack_activation = NULL;  // stack base not known yet
1640   (void)const_cast<oop&>(_exception_oop = oop(NULL));
1641   _exception_pc  = 0;
1642   _exception_handler_pc = 0;
1643   _is_method_handle_return = 0;
1644   _jvmti_thread_state= NULL;
1645   _should_post_on_exceptions_flag = JNI_FALSE;
1646   _interp_only_mode    = 0;
1647   _special_runtime_exit_condition = _no_async_condition;
1648   _pending_async_exception = NULL;
1649   _thread_stat = NULL;
1650   _thread_stat = new ThreadStatistics();
1651   _blocked_on_compilation = false;
1652   _jni_active_critical = 0;
1653   _pending_jni_exception_check_fn = NULL;
1654   _do_not_unlock_if_synchronized = false;
1655   _cached_monitor_info = NULL;
1656   _parker = Parker::Allocate(this);
1657 
1658 #ifndef PRODUCT
1659   _jmp_ring_index = 0;
1660   for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1661     record_jump(NULL, NULL, NULL, 0);
1662   }
1663 #endif // PRODUCT
1664 
1665   // Setup safepoint state info for this thread
1666   ThreadSafepointState::create(this);
1667 
1668   debug_only(_java_call_counter = 0);
1669 
1670   // JVMTI PopFrame support
1671   _popframe_condition = popframe_inactive;
1672   _popframe_preserved_args = NULL;
1673   _popframe_preserved_args_size = 0;
1674   _frames_to_pop_failed_realloc = 0;
1675 
1676   if (SafepointMechanism::uses_thread_local_poll()) {
1677     SafepointMechanism::initialize_header(this);
1678   }
1679 
1680   _class_to_be_initialized = NULL;
1681 
1682   pd_initialize();
1683 }
1684 
1685 JavaThread::JavaThread(bool is_attaching_via_jni) :
1686                        Thread() {
1687   initialize();
1688   if (is_attaching_via_jni) {
1689     _jni_attach_state = _attaching_via_jni;
1690   } else {
1691     _jni_attach_state = _not_attaching_via_jni;
1692   }
1693   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1694 }
1695 
1696 bool JavaThread::reguard_stack(address cur_sp) {
1697   if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1698       && _stack_guard_state != stack_guard_reserved_disabled) {
1699     return true; // Stack already guarded or guard pages not needed.
1700   }
1701 
1702   if (register_stack_overflow()) {
1703     // For those architectures which have separate register and
1704     // memory stacks, we must check the register stack to see if
1705     // it has overflowed.
1706     return false;
1707   }
1708 
1709   // Java code never executes within the yellow zone: the latter is only
1710   // there to provoke an exception during stack banging.  If java code
1711   // is executing there, either StackShadowPages should be larger, or
1712   // some exception code in c1, c2 or the interpreter isn't unwinding
1713   // when it should.
1714   guarantee(cur_sp > stack_reserved_zone_base(),
1715             "not enough space to reguard - increase StackShadowPages");
1716   if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1717     enable_stack_yellow_reserved_zone();
1718     if (reserved_stack_activation() != stack_base()) {
1719       set_reserved_stack_activation(stack_base());
1720     }
1721   } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1722     set_reserved_stack_activation(stack_base());
1723     enable_stack_reserved_zone();
1724   }
1725   return true;
1726 }
1727 
1728 bool JavaThread::reguard_stack(void) {
1729   return reguard_stack(os::current_stack_pointer());
1730 }
1731 
1732 
1733 void JavaThread::block_if_vm_exited() {
1734   if (_terminated == _vm_exited) {
1735     // _vm_exited is set at safepoint, and Threads_lock is never released
1736     // we will block here forever
1737     Threads_lock->lock_without_safepoint_check();
1738     ShouldNotReachHere();
1739   }
1740 }
1741 
1742 
1743 // Remove this ifdef when C1 is ported to the compiler interface.
1744 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1745 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1746 
1747 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1748                        Thread() {
1749   initialize();
1750   _jni_attach_state = _not_attaching_via_jni;
1751   set_entry_point(entry_point);
1752   // Create the native thread itself.
1753   // %note runtime_23
1754   os::ThreadType thr_type = os::java_thread;
1755   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1756                                                      os::java_thread;
1757   os::create_thread(this, thr_type, stack_sz);
1758   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1759   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1760   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1761   // the exception consists of creating the exception object & initializing it, initialization
1762   // will leave the VM via a JavaCall and then all locks must be unlocked).
1763   //
1764   // The thread is still suspended when we reach here. Thread must be explicit started
1765   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1766   // by calling Threads:add. The reason why this is not done here, is because the thread
1767   // object must be fully initialized (take a look at JVM_Start)
1768 }
1769 
1770 JavaThread::~JavaThread() {
1771 
1772   // JSR166 -- return the parker to the free list
1773   Parker::Release(_parker);
1774   _parker = NULL;
1775 
1776   // Free any remaining  previous UnrollBlock
1777   vframeArray* old_array = vframe_array_last();
1778 
1779   if (old_array != NULL) {
1780     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1781     old_array->set_unroll_block(NULL);
1782     delete old_info;
1783     delete old_array;
1784   }
1785 
1786   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1787   if (deferred != NULL) {
1788     // This can only happen if thread is destroyed before deoptimization occurs.
1789     assert(deferred->length() != 0, "empty array!");
1790     do {
1791       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1792       deferred->remove_at(0);
1793       // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1794       delete dlv;
1795     } while (deferred->length() != 0);
1796     delete deferred;
1797   }
1798 
1799   // All Java related clean up happens in exit
1800   ThreadSafepointState::destroy(this);
1801   if (_thread_stat != NULL) delete _thread_stat;
1802 
1803 #if INCLUDE_JVMCI
1804   if (JVMCICounterSize > 0) {
1805     if (jvmci_counters_include(this)) {
1806       for (int i = 0; i < JVMCICounterSize; i++) {
1807         _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1808       }
1809     }
1810     FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1811   }
1812 #endif // INCLUDE_JVMCI
1813 }
1814 
1815 
1816 // First JavaThread specific code executed by a new Java thread.
1817 void JavaThread::pre_run() {
1818   // empty - see comments in run()
1819 }
1820 
1821 // The main routine called by a new Java thread. This isn't overridden
1822 // by subclasses, instead different subclasses define a different "entry_point"
1823 // which defines the actual logic for that kind of thread.
1824 void JavaThread::run() {
1825   // initialize thread-local alloc buffer related fields
1826   this->initialize_tlab();
1827 
1828   // Used to test validity of stack trace backs.
1829   // This can't be moved into pre_run() else we invalidate
1830   // the requirement that thread_main_inner is lower on
1831   // the stack. Consequently all the initialization logic
1832   // stays here in run() rather than pre_run().
1833   this->record_base_of_stack_pointer();
1834 
1835   this->create_stack_guard_pages();
1836 
1837   this->cache_global_variables();
1838 
1839   // Thread is now sufficiently initialized to be handled by the safepoint code as being
1840   // in the VM. Change thread state from _thread_new to _thread_in_vm
1841   ThreadStateTransition::transition(this, _thread_new, _thread_in_vm);
1842   // Before a thread is on the threads list it is always safe, so after leaving the
1843   // _thread_new we should emit a instruction barrier. The distance to modified code
1844   // from here is probably far enough, but this is consistent and safe.
1845   OrderAccess::cross_modify_fence();
1846 
1847   assert(JavaThread::current() == this, "sanity check");
1848   assert(!Thread::current()->owns_locks(), "sanity check");
1849 
1850   DTRACE_THREAD_PROBE(start, this);
1851 
1852   // This operation might block. We call that after all safepoint checks for a new thread has
1853   // been completed.
1854   this->set_active_handles(JNIHandleBlock::allocate_block());
1855 
1856   if (JvmtiExport::should_post_thread_life()) {
1857     JvmtiExport::post_thread_start(this);
1858 
1859   }
1860 
1861   // We call another function to do the rest so we are sure that the stack addresses used
1862   // from there will be lower than the stack base just computed.
1863   thread_main_inner();
1864 }
1865 
1866 void JavaThread::thread_main_inner() {
1867   assert(JavaThread::current() == this, "sanity check");
1868   assert(this->threadObj() != NULL, "just checking");
1869 
1870   // Execute thread entry point unless this thread has a pending exception
1871   // or has been stopped before starting.
1872   // Note: Due to JVM_StopThread we can have pending exceptions already!
1873   if (!this->has_pending_exception() &&
1874       !java_lang_Thread::is_stillborn(this->threadObj())) {
1875     {
1876       ResourceMark rm(this);
1877       this->set_native_thread_name(this->get_thread_name());
1878     }
1879     HandleMark hm(this);
1880     this->entry_point()(this, this);
1881   }
1882 
1883   DTRACE_THREAD_PROBE(stop, this);
1884 
1885   // Cleanup is handled in post_run()
1886 }
1887 
1888 // Shared teardown for all JavaThreads
1889 void JavaThread::post_run() {
1890   this->exit(false);
1891   // Defer deletion to here to ensure 'this' is still referenceable in call_run
1892   // for any shared tear-down.
1893   this->smr_delete();
1894 }
1895 
1896 static void ensure_join(JavaThread* thread) {
1897   // We do not need to grab the Threads_lock, since we are operating on ourself.
1898   Handle threadObj(thread, thread->threadObj());
1899   assert(threadObj.not_null(), "java thread object must exist");
1900   ObjectLocker lock(threadObj, thread);
1901   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1902   thread->clear_pending_exception();
1903   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1904   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1905   // Clear the native thread instance - this makes isAlive return false and allows the join()
1906   // to complete once we've done the notify_all below
1907   java_lang_Thread::set_thread(threadObj(), NULL);
1908   lock.notify_all(thread);
1909   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1910   thread->clear_pending_exception();
1911 }
1912 
1913 static bool is_daemon(oop threadObj) {
1914   return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj));
1915 }
1916 
1917 // For any new cleanup additions, please check to see if they need to be applied to
1918 // cleanup_failed_attach_current_thread as well.
1919 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1920   assert(this == JavaThread::current(), "thread consistency check");
1921 
1922   elapsedTimer _timer_exit_phase1;
1923   elapsedTimer _timer_exit_phase2;
1924   elapsedTimer _timer_exit_phase3;
1925   elapsedTimer _timer_exit_phase4;
1926 
1927   if (log_is_enabled(Debug, os, thread, timer)) {
1928     _timer_exit_phase1.start();
1929   }
1930 
1931   HandleMark hm(this);
1932   Handle uncaught_exception(this, this->pending_exception());
1933   this->clear_pending_exception();
1934   Handle threadObj(this, this->threadObj());
1935   assert(threadObj.not_null(), "Java thread object should be created");
1936 
1937   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1938   {
1939     EXCEPTION_MARK;
1940 
1941     CLEAR_PENDING_EXCEPTION;
1942   }
1943   if (!destroy_vm) {
1944     if (uncaught_exception.not_null()) {
1945       EXCEPTION_MARK;
1946       // Call method Thread.dispatchUncaughtException().
1947       Klass* thread_klass = SystemDictionary::Thread_klass();
1948       JavaValue result(T_VOID);
1949       JavaCalls::call_virtual(&result,
1950                               threadObj, thread_klass,
1951                               vmSymbols::dispatchUncaughtException_name(),
1952                               vmSymbols::throwable_void_signature(),
1953                               uncaught_exception,
1954                               THREAD);
1955       if (HAS_PENDING_EXCEPTION) {
1956         ResourceMark rm(this);
1957         jio_fprintf(defaultStream::error_stream(),
1958                     "\nException: %s thrown from the UncaughtExceptionHandler"
1959                     " in thread \"%s\"\n",
1960                     pending_exception()->klass()->external_name(),
1961                     get_thread_name());
1962         CLEAR_PENDING_EXCEPTION;
1963       }
1964     }
1965     JFR_ONLY(Jfr::on_java_thread_dismantle(this);)
1966 
1967     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1968     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1969     // is deprecated anyhow.
1970     if (!is_Compiler_thread()) {
1971       int count = 3;
1972       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1973         EXCEPTION_MARK;
1974         JavaValue result(T_VOID);
1975         Klass* thread_klass = SystemDictionary::Thread_klass();
1976         JavaCalls::call_virtual(&result,
1977                                 threadObj, thread_klass,
1978                                 vmSymbols::exit_method_name(),
1979                                 vmSymbols::void_method_signature(),
1980                                 THREAD);
1981         CLEAR_PENDING_EXCEPTION;
1982       }
1983     }
1984     // notify JVMTI
1985     if (JvmtiExport::should_post_thread_life()) {
1986       JvmtiExport::post_thread_end(this);
1987     }
1988 
1989     // We have notified the agents that we are exiting, before we go on,
1990     // we must check for a pending external suspend request and honor it
1991     // in order to not surprise the thread that made the suspend request.
1992     while (true) {
1993       {
1994         MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1995         if (!is_external_suspend()) {
1996           set_terminated(_thread_exiting);
1997           ThreadService::current_thread_exiting(this, is_daemon(threadObj()));
1998           break;
1999         }
2000         // Implied else:
2001         // Things get a little tricky here. We have a pending external
2002         // suspend request, but we are holding the SR_lock so we
2003         // can't just self-suspend. So we temporarily drop the lock
2004         // and then self-suspend.
2005       }
2006 
2007       ThreadBlockInVM tbivm(this);
2008       java_suspend_self();
2009 
2010       // We're done with this suspend request, but we have to loop around
2011       // and check again. Eventually we will get SR_lock without a pending
2012       // external suspend request and will be able to mark ourselves as
2013       // exiting.
2014     }
2015     // no more external suspends are allowed at this point
2016   } else {
2017     assert(!is_terminated() && !is_exiting(), "must not be exiting");
2018     // before_exit() has already posted JVMTI THREAD_END events
2019   }
2020 
2021   if (log_is_enabled(Debug, os, thread, timer)) {
2022     _timer_exit_phase1.stop();
2023     _timer_exit_phase2.start();
2024   }
2025 
2026   // Capture daemon status before the thread is marked as terminated.
2027   bool daemon = is_daemon(threadObj());
2028 
2029   // Notify waiters on thread object. This has to be done after exit() is called
2030   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
2031   // group should have the destroyed bit set before waiters are notified).
2032   ensure_join(this);
2033   assert(!this->has_pending_exception(), "ensure_join should have cleared");
2034 
2035   if (log_is_enabled(Debug, os, thread, timer)) {
2036     _timer_exit_phase2.stop();
2037     _timer_exit_phase3.start();
2038   }
2039   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
2040   // held by this thread must be released. The spec does not distinguish
2041   // between JNI-acquired and regular Java monitors. We can only see
2042   // regular Java monitors here if monitor enter-exit matching is broken.
2043   //
2044   // ensure_join() ignores IllegalThreadStateExceptions, and so does
2045   // ObjectSynchronizer::release_monitors_owned_by_thread().
2046   if (exit_type == jni_detach) {
2047     // Sanity check even though JNI DetachCurrentThread() would have
2048     // returned JNI_ERR if there was a Java frame. JavaThread exit
2049     // should be done executing Java code by the time we get here.
2050     assert(!this->has_last_Java_frame(),
2051            "should not have a Java frame when detaching or exiting");
2052     ObjectSynchronizer::release_monitors_owned_by_thread(this);
2053     assert(!this->has_pending_exception(), "release_monitors should have cleared");
2054   }
2055 
2056   // These things needs to be done while we are still a Java Thread. Make sure that thread
2057   // is in a consistent state, in case GC happens
2058   JFR_ONLY(Jfr::on_thread_exit(this);)
2059 
2060   if (active_handles() != NULL) {
2061     JNIHandleBlock* block = active_handles();
2062     set_active_handles(NULL);
2063     JNIHandleBlock::release_block(block);
2064   }
2065 
2066   if (free_handle_block() != NULL) {
2067     JNIHandleBlock* block = free_handle_block();
2068     set_free_handle_block(NULL);
2069     JNIHandleBlock::release_block(block);
2070   }
2071 
2072   // These have to be removed while this is still a valid thread.
2073   remove_stack_guard_pages();
2074 
2075   if (UseTLAB) {
2076     tlab().retire();
2077   }
2078 
2079   if (JvmtiEnv::environments_might_exist()) {
2080     JvmtiExport::cleanup_thread(this);
2081   }
2082 
2083   // We must flush any deferred card marks and other various GC barrier
2084   // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
2085   // before removing a thread from the list of active threads.
2086   BarrierSet::barrier_set()->on_thread_detach(this);
2087 
2088   log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2089     exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2090     os::current_thread_id());
2091 
2092   if (log_is_enabled(Debug, os, thread, timer)) {
2093     _timer_exit_phase3.stop();
2094     _timer_exit_phase4.start();
2095   }
2096   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2097   Threads::remove(this, daemon);
2098 
2099   if (log_is_enabled(Debug, os, thread, timer)) {
2100     _timer_exit_phase4.stop();
2101     ResourceMark rm(this);
2102     log_debug(os, thread, timer)("name='%s'"
2103                                  ", exit-phase1=" JLONG_FORMAT
2104                                  ", exit-phase2=" JLONG_FORMAT
2105                                  ", exit-phase3=" JLONG_FORMAT
2106                                  ", exit-phase4=" JLONG_FORMAT,
2107                                  get_thread_name(),
2108                                  _timer_exit_phase1.milliseconds(),
2109                                  _timer_exit_phase2.milliseconds(),
2110                                  _timer_exit_phase3.milliseconds(),
2111                                  _timer_exit_phase4.milliseconds());
2112   }
2113 }
2114 
2115 void JavaThread::cleanup_failed_attach_current_thread(bool is_daemon) {
2116   if (active_handles() != NULL) {
2117     JNIHandleBlock* block = active_handles();
2118     set_active_handles(NULL);
2119     JNIHandleBlock::release_block(block);
2120   }
2121 
2122   if (free_handle_block() != NULL) {
2123     JNIHandleBlock* block = free_handle_block();
2124     set_free_handle_block(NULL);
2125     JNIHandleBlock::release_block(block);
2126   }
2127 
2128   // These have to be removed while this is still a valid thread.
2129   remove_stack_guard_pages();
2130 
2131   if (UseTLAB) {
2132     tlab().retire();
2133   }
2134 
2135   BarrierSet::barrier_set()->on_thread_detach(this);
2136 
2137   Threads::remove(this, is_daemon);
2138   this->smr_delete();
2139 }
2140 
2141 JavaThread* JavaThread::active() {
2142   Thread* thread = Thread::current();
2143   if (thread->is_Java_thread()) {
2144     return (JavaThread*) thread;
2145   } else {
2146     assert(thread->is_VM_thread(), "this must be a vm thread");
2147     VM_Operation* op = ((VMThread*) thread)->vm_operation();
2148     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2149     assert(ret->is_Java_thread(), "must be a Java thread");
2150     return ret;
2151   }
2152 }
2153 
2154 bool JavaThread::is_lock_owned(address adr) const {
2155   if (Thread::is_lock_owned(adr)) return true;
2156 
2157   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2158     if (chunk->contains(adr)) return true;
2159   }
2160 
2161   return false;
2162 }
2163 
2164 
2165 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2166   chunk->set_next(monitor_chunks());
2167   set_monitor_chunks(chunk);
2168 }
2169 
2170 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2171   guarantee(monitor_chunks() != NULL, "must be non empty");
2172   if (monitor_chunks() == chunk) {
2173     set_monitor_chunks(chunk->next());
2174   } else {
2175     MonitorChunk* prev = monitor_chunks();
2176     while (prev->next() != chunk) prev = prev->next();
2177     prev->set_next(chunk->next());
2178   }
2179 }
2180 
2181 // JVM support.
2182 
2183 // Note: this function shouldn't block if it's called in
2184 // _thread_in_native_trans state (such as from
2185 // check_special_condition_for_native_trans()).
2186 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2187 
2188   if (has_last_Java_frame() && has_async_condition()) {
2189     // If we are at a polling page safepoint (not a poll return)
2190     // then we must defer async exception because live registers
2191     // will be clobbered by the exception path. Poll return is
2192     // ok because the call we a returning from already collides
2193     // with exception handling registers and so there is no issue.
2194     // (The exception handling path kills call result registers but
2195     //  this is ok since the exception kills the result anyway).
2196 
2197     if (is_at_poll_safepoint()) {
2198       // if the code we are returning to has deoptimized we must defer
2199       // the exception otherwise live registers get clobbered on the
2200       // exception path before deoptimization is able to retrieve them.
2201       //
2202       RegisterMap map(this, false);
2203       frame caller_fr = last_frame().sender(&map);
2204       assert(caller_fr.is_compiled_frame(), "what?");
2205       if (caller_fr.is_deoptimized_frame()) {
2206         log_info(exceptions)("deferred async exception at compiled safepoint");
2207         return;
2208       }
2209     }
2210   }
2211 
2212   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2213   if (condition == _no_async_condition) {
2214     // Conditions have changed since has_special_runtime_exit_condition()
2215     // was called:
2216     // - if we were here only because of an external suspend request,
2217     //   then that was taken care of above (or cancelled) so we are done
2218     // - if we were here because of another async request, then it has
2219     //   been cleared between the has_special_runtime_exit_condition()
2220     //   and now so again we are done
2221     return;
2222   }
2223 
2224   // Check for pending async. exception
2225   if (_pending_async_exception != NULL) {
2226     // Only overwrite an already pending exception, if it is not a threadDeath.
2227     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2228 
2229       // We cannot call Exceptions::_throw(...) here because we cannot block
2230       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2231 
2232       LogTarget(Info, exceptions) lt;
2233       if (lt.is_enabled()) {
2234         ResourceMark rm;
2235         LogStream ls(lt);
2236         ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2237           if (has_last_Java_frame()) {
2238             frame f = last_frame();
2239            ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2240           }
2241         ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2242       }
2243       _pending_async_exception = NULL;
2244       clear_has_async_exception();
2245     }
2246   }
2247 
2248   if (check_unsafe_error &&
2249       condition == _async_unsafe_access_error && !has_pending_exception()) {
2250     condition = _no_async_condition;  // done
2251     switch (thread_state()) {
2252     case _thread_in_vm: {
2253       JavaThread* THREAD = this;
2254       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2255     }
2256     case _thread_in_native: {
2257       ThreadInVMfromNative tiv(this);
2258       JavaThread* THREAD = this;
2259       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2260     }
2261     case _thread_in_Java: {
2262       ThreadInVMfromJava tiv(this);
2263       JavaThread* THREAD = this;
2264       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2265     }
2266     default:
2267       ShouldNotReachHere();
2268     }
2269   }
2270 
2271   assert(condition == _no_async_condition || has_pending_exception() ||
2272          (!check_unsafe_error && condition == _async_unsafe_access_error),
2273          "must have handled the async condition, if no exception");
2274 }
2275 
2276 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2277   //
2278   // Check for pending external suspend.
2279   // If JNIEnv proxies are allowed, don't self-suspend if the target
2280   // thread is not the current thread. In older versions of jdbx, jdbx
2281   // threads could call into the VM with another thread's JNIEnv so we
2282   // can be here operating on behalf of a suspended thread (4432884).
2283   bool do_self_suspend = is_external_suspend_with_lock();
2284   if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2285     frame_anchor()->make_walkable(this);
2286     java_suspend_self_with_safepoint_check();
2287   }
2288 
2289   // We might be here for reasons in addition to the self-suspend request
2290   // so check for other async requests.
2291   if (check_asyncs) {
2292     check_and_handle_async_exceptions();
2293   }
2294 
2295   JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
2296 }
2297 
2298 void JavaThread::send_thread_stop(oop java_throwable)  {
2299   assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2300   assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2301   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2302 
2303   // Do not throw asynchronous exceptions against the compiler thread
2304   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2305   if (!can_call_java()) return;
2306 
2307   {
2308     // Actually throw the Throwable against the target Thread - however
2309     // only if there is no thread death exception installed already.
2310     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2311       // If the topmost frame is a runtime stub, then we are calling into
2312       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2313       // must deoptimize the caller before continuing, as the compiled  exception handler table
2314       // may not be valid
2315       if (has_last_Java_frame()) {
2316         frame f = last_frame();
2317         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2318           // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2319           RegisterMap reg_map(this, UseBiasedLocking);
2320           frame compiled_frame = f.sender(&reg_map);
2321           if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2322             Deoptimization::deoptimize(this, compiled_frame, &reg_map);
2323           }
2324         }
2325       }
2326 
2327       // Set async. pending exception in thread.
2328       set_pending_async_exception(java_throwable);
2329 
2330       if (log_is_enabled(Info, exceptions)) {
2331          ResourceMark rm;
2332         log_info(exceptions)("Pending Async. exception installed of type: %s",
2333                              InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2334       }
2335       // for AbortVMOnException flag
2336       Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2337     }
2338   }
2339 
2340 
2341   // Interrupt thread so it will wake up from a potential wait()
2342   Thread::interrupt(this);
2343 }
2344 
2345 // External suspension mechanism.
2346 //
2347 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2348 // to any VM_locks and it is at a transition
2349 // Self-suspension will happen on the transition out of the vm.
2350 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2351 //
2352 // Guarantees on return:
2353 //   + Target thread will not execute any new bytecode (that's why we need to
2354 //     force a safepoint)
2355 //   + Target thread will not enter any new monitors
2356 //
2357 void JavaThread::java_suspend() {
2358   ThreadsListHandle tlh;
2359   if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2360     return;
2361   }
2362 
2363   { MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2364     if (!is_external_suspend()) {
2365       // a racing resume has cancelled us; bail out now
2366       return;
2367     }
2368 
2369     // suspend is done
2370     uint32_t debug_bits = 0;
2371     // Warning: is_ext_suspend_completed() may temporarily drop the
2372     // SR_lock to allow the thread to reach a stable thread state if
2373     // it is currently in a transient thread state.
2374     if (is_ext_suspend_completed(false /* !called_by_wait */,
2375                                  SuspendRetryDelay, &debug_bits)) {
2376       return;
2377     }
2378   }
2379 
2380   if (Thread::current() == this) {
2381     // Safely self-suspend.
2382     // If we don't do this explicitly it will implicitly happen
2383     // before we transition back to Java, and on some other thread-state
2384     // transition paths, but not as we exit a JVM TI SuspendThread call.
2385     // As SuspendThread(current) must not return (until resumed) we must
2386     // self-suspend here.
2387     ThreadBlockInVM tbivm(this);
2388     java_suspend_self();
2389   } else {
2390     VM_ThreadSuspend vm_suspend;
2391     VMThread::execute(&vm_suspend);
2392   }
2393 }
2394 
2395 // Part II of external suspension.
2396 // A JavaThread self suspends when it detects a pending external suspend
2397 // request. This is usually on transitions. It is also done in places
2398 // where continuing to the next transition would surprise the caller,
2399 // e.g., monitor entry.
2400 //
2401 // Returns the number of times that the thread self-suspended.
2402 //
2403 // Note: DO NOT call java_suspend_self() when you just want to block current
2404 //       thread. java_suspend_self() is the second stage of cooperative
2405 //       suspension for external suspend requests and should only be used
2406 //       to complete an external suspend request.
2407 //
2408 int JavaThread::java_suspend_self() {
2409   assert(thread_state() == _thread_blocked, "wrong state for java_suspend_self()");
2410   int ret = 0;
2411 
2412   // we are in the process of exiting so don't suspend
2413   if (is_exiting()) {
2414     clear_external_suspend();
2415     return ret;
2416   }
2417 
2418   assert(_anchor.walkable() ||
2419          (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2420          "must have walkable stack");
2421 
2422   MonitorLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2423 
2424   assert(!this->is_ext_suspended(),
2425          "a thread trying to self-suspend should not already be suspended");
2426 
2427   if (this->is_suspend_equivalent()) {
2428     // If we are self-suspending as a result of the lifting of a
2429     // suspend equivalent condition, then the suspend_equivalent
2430     // flag is not cleared until we set the ext_suspended flag so
2431     // that wait_for_ext_suspend_completion() returns consistent
2432     // results.
2433     this->clear_suspend_equivalent();
2434   }
2435 
2436   // A racing resume may have cancelled us before we grabbed SR_lock
2437   // above. Or another external suspend request could be waiting for us
2438   // by the time we return from SR_lock()->wait(). The thread
2439   // that requested the suspension may already be trying to walk our
2440   // stack and if we return now, we can change the stack out from under
2441   // it. This would be a "bad thing (TM)" and cause the stack walker
2442   // to crash. We stay self-suspended until there are no more pending
2443   // external suspend requests.
2444   while (is_external_suspend()) {
2445     ret++;
2446     this->set_ext_suspended();
2447 
2448     // _ext_suspended flag is cleared by java_resume()
2449     while (is_ext_suspended()) {
2450       ml.wait();
2451     }
2452   }
2453   return ret;
2454 }
2455 
2456 // Helper routine to set up the correct thread state before calling java_suspend_self.
2457 // This is called when regular thread-state transition helpers can't be used because
2458 // we can be in various states, in particular _thread_in_native_trans.
2459 // Because this thread is external suspended the safepoint code will count it as at
2460 // a safepoint, regardless of what its actual current thread-state is. But
2461 // is_ext_suspend_completed() may be waiting to see a thread transition from
2462 // _thread_in_native_trans to _thread_blocked. So we set the thread state directly
2463 // to _thread_blocked. The problem with setting thread state directly is that a
2464 // safepoint could happen just after java_suspend_self() returns after being resumed,
2465 // and the VM thread will see the _thread_blocked state. So we must check for a safepoint
2466 // after restoring the state to make sure we won't leave while a safepoint is in progress.
2467 // However, not all initial-states are allowed when performing a safepoint check, as we
2468 // should never be blocking at a safepoint whilst in those states. Of these 'bad' states
2469 // only _thread_in_native is possible when executing this code (based on our two callers).
2470 // A thread that is _thread_in_native is already safepoint-safe and so it doesn't matter
2471 // whether the VMThread sees the _thread_blocked state, or the _thread_in_native state,
2472 // and so we don't need the explicit safepoint check.
2473 
2474 void JavaThread::java_suspend_self_with_safepoint_check() {
2475   assert(this == Thread::current(), "invariant");
2476   JavaThreadState state = thread_state();
2477   set_thread_state(_thread_blocked);
2478   java_suspend_self();
2479   set_thread_state_fence(state);
2480   // Since we are not using a regular thread-state transition helper here,
2481   // we must manually emit the instruction barrier after leaving a safe state.
2482   OrderAccess::cross_modify_fence();
2483   if (state != _thread_in_native) {
2484     SafepointMechanism::block_if_requested(this);
2485   }
2486 }
2487 
2488 #ifdef ASSERT
2489 // Verify the JavaThread has not yet been published in the Threads::list, and
2490 // hence doesn't need protection from concurrent access at this stage.
2491 void JavaThread::verify_not_published() {
2492   // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
2493   // since an unpublished JavaThread doesn't participate in the
2494   // Thread-SMR protocol for keeping a ThreadsList alive.
2495   assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
2496 }
2497 #endif
2498 
2499 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2500 // progress or when _suspend_flags is non-zero.
2501 // Current thread needs to self-suspend if there is a suspend request and/or
2502 // block if a safepoint is in progress.
2503 // Async exception ISN'T checked.
2504 // Note only the ThreadInVMfromNative transition can call this function
2505 // directly and when thread state is _thread_in_native_trans
2506 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2507   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2508 
2509   JavaThread *curJT = JavaThread::current();
2510   bool do_self_suspend = thread->is_external_suspend();
2511 
2512   assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2513 
2514   // If JNIEnv proxies are allowed, don't self-suspend if the target
2515   // thread is not the current thread. In older versions of jdbx, jdbx
2516   // threads could call into the VM with another thread's JNIEnv so we
2517   // can be here operating on behalf of a suspended thread (4432884).
2518   if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2519     thread->java_suspend_self_with_safepoint_check();
2520   } else {
2521     SafepointMechanism::block_if_requested(curJT);
2522   }
2523 
2524   JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);)
2525 }
2526 
2527 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2528 // progress or when _suspend_flags is non-zero.
2529 // Current thread needs to self-suspend if there is a suspend request and/or
2530 // block if a safepoint is in progress.
2531 // Also check for pending async exception (not including unsafe access error).
2532 // Note only the native==>VM/Java barriers can call this function and when
2533 // thread state is _thread_in_native_trans.
2534 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2535   check_safepoint_and_suspend_for_native_trans(thread);
2536 
2537   if (thread->has_async_exception()) {
2538     // We are in _thread_in_native_trans state, don't handle unsafe
2539     // access error since that may block.
2540     thread->check_and_handle_async_exceptions(false);
2541   }
2542 }
2543 
2544 // This is a variant of the normal
2545 // check_special_condition_for_native_trans with slightly different
2546 // semantics for use by critical native wrappers.  It does all the
2547 // normal checks but also performs the transition back into
2548 // thread_in_Java state.  This is required so that critical natives
2549 // can potentially block and perform a GC if they are the last thread
2550 // exiting the GCLocker.
2551 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2552   check_special_condition_for_native_trans(thread);
2553 
2554   // Finish the transition
2555   thread->set_thread_state(_thread_in_Java);
2556 
2557   if (thread->do_critical_native_unlock()) {
2558     ThreadInVMfromJavaNoAsyncException tiv(thread);
2559     GCLocker::unlock_critical(thread);
2560     thread->clear_critical_native_unlock();
2561   }
2562 }
2563 
2564 // We need to guarantee the Threads_lock here, since resumes are not
2565 // allowed during safepoint synchronization
2566 // Can only resume from an external suspension
2567 void JavaThread::java_resume() {
2568   assert_locked_or_safepoint(Threads_lock);
2569 
2570   // Sanity check: thread is gone, has started exiting or the thread
2571   // was not externally suspended.
2572   ThreadsListHandle tlh;
2573   if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2574     return;
2575   }
2576 
2577   MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2578 
2579   clear_external_suspend();
2580 
2581   if (is_ext_suspended()) {
2582     clear_ext_suspended();
2583     SR_lock()->notify_all();
2584   }
2585 }
2586 
2587 size_t JavaThread::_stack_red_zone_size = 0;
2588 size_t JavaThread::_stack_yellow_zone_size = 0;
2589 size_t JavaThread::_stack_reserved_zone_size = 0;
2590 size_t JavaThread::_stack_shadow_zone_size = 0;
2591 
2592 void JavaThread::create_stack_guard_pages() {
2593   if (!os::uses_stack_guard_pages() ||
2594       _stack_guard_state != stack_guard_unused ||
2595       (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2596       log_info(os, thread)("Stack guard page creation for thread "
2597                            UINTX_FORMAT " disabled", os::current_thread_id());
2598     return;
2599   }
2600   address low_addr = stack_end();
2601   size_t len = stack_guard_zone_size();
2602 
2603   assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2604   assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2605 
2606   int must_commit = os::must_commit_stack_guard_pages();
2607   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2608 
2609   if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2610     log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2611     return;
2612   }
2613 
2614   if (os::guard_memory((char *) low_addr, len)) {
2615     _stack_guard_state = stack_guard_enabled;
2616   } else {
2617     log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2618       PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2619     if (os::uncommit_memory((char *) low_addr, len)) {
2620       log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2621     }
2622     return;
2623   }
2624 
2625   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2626     PTR_FORMAT "-" PTR_FORMAT ".",
2627     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2628 }
2629 
2630 void JavaThread::remove_stack_guard_pages() {
2631   assert(Thread::current() == this, "from different thread");
2632   if (_stack_guard_state == stack_guard_unused) return;
2633   address low_addr = stack_end();
2634   size_t len = stack_guard_zone_size();
2635 
2636   if (os::must_commit_stack_guard_pages()) {
2637     if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2638       _stack_guard_state = stack_guard_unused;
2639     } else {
2640       log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2641         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2642       return;
2643     }
2644   } else {
2645     if (_stack_guard_state == stack_guard_unused) return;
2646     if (os::unguard_memory((char *) low_addr, len)) {
2647       _stack_guard_state = stack_guard_unused;
2648     } else {
2649       log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2650         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2651       return;
2652     }
2653   }
2654 
2655   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2656     PTR_FORMAT "-" PTR_FORMAT ".",
2657     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2658 }
2659 
2660 void JavaThread::enable_stack_reserved_zone() {
2661   assert(_stack_guard_state == stack_guard_reserved_disabled, "inconsistent state");
2662 
2663   // The base notation is from the stack's point of view, growing downward.
2664   // We need to adjust it to work correctly with guard_memory()
2665   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2666 
2667   guarantee(base < stack_base(),"Error calculating stack reserved zone");
2668   guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2669 
2670   if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2671     _stack_guard_state = stack_guard_enabled;
2672   } else {
2673     warning("Attempt to guard stack reserved zone failed.");
2674   }
2675   enable_register_stack_guard();
2676 }
2677 
2678 void JavaThread::disable_stack_reserved_zone() {
2679   assert(_stack_guard_state == stack_guard_enabled, "inconsistent state");
2680 
2681   // Simply return if called for a thread that does not use guard pages.
2682   if (_stack_guard_state != stack_guard_enabled) return;
2683 
2684   // The base notation is from the stack's point of view, growing downward.
2685   // We need to adjust it to work correctly with guard_memory()
2686   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2687 
2688   if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2689     _stack_guard_state = stack_guard_reserved_disabled;
2690   } else {
2691     warning("Attempt to unguard stack reserved zone failed.");
2692   }
2693   disable_register_stack_guard();
2694 }
2695 
2696 void JavaThread::enable_stack_yellow_reserved_zone() {
2697   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2698   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2699 
2700   // The base notation is from the stacks point of view, growing downward.
2701   // We need to adjust it to work correctly with guard_memory()
2702   address base = stack_red_zone_base();
2703 
2704   guarantee(base < stack_base(), "Error calculating stack yellow zone");
2705   guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2706 
2707   if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2708     _stack_guard_state = stack_guard_enabled;
2709   } else {
2710     warning("Attempt to guard stack yellow zone failed.");
2711   }
2712   enable_register_stack_guard();
2713 }
2714 
2715 void JavaThread::disable_stack_yellow_reserved_zone() {
2716   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2717   assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2718 
2719   // Simply return if called for a thread that does not use guard pages.
2720   if (_stack_guard_state == stack_guard_unused) return;
2721 
2722   // The base notation is from the stacks point of view, growing downward.
2723   // We need to adjust it to work correctly with guard_memory()
2724   address base = stack_red_zone_base();
2725 
2726   if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2727     _stack_guard_state = stack_guard_yellow_reserved_disabled;
2728   } else {
2729     warning("Attempt to unguard stack yellow zone failed.");
2730   }
2731   disable_register_stack_guard();
2732 }
2733 
2734 void JavaThread::enable_stack_red_zone() {
2735   // The base notation is from the stacks point of view, growing downward.
2736   // We need to adjust it to work correctly with guard_memory()
2737   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2738   address base = stack_red_zone_base() - stack_red_zone_size();
2739 
2740   guarantee(base < stack_base(), "Error calculating stack red zone");
2741   guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2742 
2743   if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2744     warning("Attempt to guard stack red zone failed.");
2745   }
2746 }
2747 
2748 void JavaThread::disable_stack_red_zone() {
2749   // The base notation is from the stacks point of view, growing downward.
2750   // We need to adjust it to work correctly with guard_memory()
2751   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2752   address base = stack_red_zone_base() - stack_red_zone_size();
2753   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2754     warning("Attempt to unguard stack red zone failed.");
2755   }
2756 }
2757 
2758 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2759   // ignore is there is no stack
2760   if (!has_last_Java_frame()) return;
2761   // traverse the stack frames. Starts from top frame.
2762   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2763     frame* fr = fst.current();
2764     f(fr, fst.register_map());
2765   }
2766 }
2767 
2768 
2769 #ifndef PRODUCT
2770 // Deoptimization
2771 // Function for testing deoptimization
2772 void JavaThread::deoptimize() {
2773   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2774   StackFrameStream fst(this, UseBiasedLocking);
2775   bool deopt = false;           // Dump stack only if a deopt actually happens.
2776   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2777   // Iterate over all frames in the thread and deoptimize
2778   for (; !fst.is_done(); fst.next()) {
2779     if (fst.current()->can_be_deoptimized()) {
2780 
2781       if (only_at) {
2782         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
2783         // consists of comma or carriage return separated numbers so
2784         // search for the current bci in that string.
2785         address pc = fst.current()->pc();
2786         nmethod* nm =  (nmethod*) fst.current()->cb();
2787         ScopeDesc* sd = nm->scope_desc_at(pc);
2788         char buffer[8];
2789         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2790         size_t len = strlen(buffer);
2791         const char * found = strstr(DeoptimizeOnlyAt, buffer);
2792         while (found != NULL) {
2793           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2794               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2795             // Check that the bci found is bracketed by terminators.
2796             break;
2797           }
2798           found = strstr(found + 1, buffer);
2799         }
2800         if (!found) {
2801           continue;
2802         }
2803       }
2804 
2805       if (DebugDeoptimization && !deopt) {
2806         deopt = true; // One-time only print before deopt
2807         tty->print_cr("[BEFORE Deoptimization]");
2808         trace_frames();
2809         trace_stack();
2810       }
2811       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2812     }
2813   }
2814 
2815   if (DebugDeoptimization && deopt) {
2816     tty->print_cr("[AFTER Deoptimization]");
2817     trace_frames();
2818   }
2819 }
2820 
2821 
2822 // Make zombies
2823 void JavaThread::make_zombies() {
2824   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2825     if (fst.current()->can_be_deoptimized()) {
2826       // it is a Java nmethod
2827       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2828       nm->make_not_entrant();
2829     }
2830   }
2831 }
2832 #endif // PRODUCT
2833 
2834 
2835 void JavaThread::deoptimize_marked_methods(bool in_handshake) {
2836   if (!has_last_Java_frame()) return;
2837   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2838   StackFrameStream fst(this, UseBiasedLocking);
2839   for (; !fst.is_done(); fst.next()) {
2840     if (fst.current()->should_be_deoptimized()) {
2841       Deoptimization::deoptimize(this, *fst.current(), fst.register_map(), in_handshake);
2842     }
2843   }
2844 }
2845 
2846 // If the caller is a NamedThread, then remember, in the current scope,
2847 // the given JavaThread in its _processed_thread field.
2848 class RememberProcessedThread: public StackObj {
2849   NamedThread* _cur_thr;
2850  public:
2851   RememberProcessedThread(JavaThread* jthr) {
2852     Thread* thread = Thread::current();
2853     if (thread->is_Named_thread()) {
2854       _cur_thr = (NamedThread *)thread;
2855       _cur_thr->set_processed_thread(jthr);
2856     } else {
2857       _cur_thr = NULL;
2858     }
2859   }
2860 
2861   ~RememberProcessedThread() {
2862     if (_cur_thr) {
2863       _cur_thr->set_processed_thread(NULL);
2864     }
2865   }
2866 };
2867 
2868 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2869   // Verify that the deferred card marks have been flushed.
2870   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2871 
2872   // Traverse the GCHandles
2873   Thread::oops_do(f, cf);
2874 
2875   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2876          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2877 
2878   if (has_last_Java_frame()) {
2879     // Record JavaThread to GC thread
2880     RememberProcessedThread rpt(this);
2881 
2882     // traverse the registered growable array
2883     if (_array_for_gc != NULL) {
2884       for (int index = 0; index < _array_for_gc->length(); index++) {
2885         f->do_oop(_array_for_gc->adr_at(index));
2886       }
2887     }
2888 
2889     // Traverse the monitor chunks
2890     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2891       chunk->oops_do(f);
2892     }
2893 
2894     // Traverse the execution stack
2895     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2896       fst.current()->oops_do(f, cf, fst.register_map());
2897     }
2898   }
2899 
2900   // callee_target is never live across a gc point so NULL it here should
2901   // it still contain a methdOop.
2902 
2903   set_callee_target(NULL);
2904 
2905   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2906   // If we have deferred set_locals there might be oops waiting to be
2907   // written
2908   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2909   if (list != NULL) {
2910     for (int i = 0; i < list->length(); i++) {
2911       list->at(i)->oops_do(f);
2912     }
2913   }
2914 
2915   // Traverse instance variables at the end since the GC may be moving things
2916   // around using this function
2917   f->do_oop((oop*) &_threadObj);
2918   f->do_oop((oop*) &_vm_result);
2919   f->do_oop((oop*) &_exception_oop);
2920   f->do_oop((oop*) &_pending_async_exception);
2921 
2922   if (jvmti_thread_state() != NULL) {
2923     jvmti_thread_state()->oops_do(f);
2924   }
2925 }
2926 
2927 #ifdef ASSERT
2928 void JavaThread::verify_states_for_handshake() {
2929   // This checks that the thread has a correct frame state during a handshake.
2930   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2931          (has_last_Java_frame() && java_call_counter() > 0),
2932          "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
2933          has_last_Java_frame(), java_call_counter());
2934 }
2935 #endif
2936 
2937 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2938   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2939          (has_last_Java_frame() && java_call_counter() > 0),
2940          "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
2941          has_last_Java_frame(), java_call_counter());
2942 
2943   if (has_last_Java_frame()) {
2944     // Traverse the execution stack
2945     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2946       fst.current()->nmethods_do(cf);
2947     }
2948   }
2949 }
2950 
2951 void JavaThread::metadata_do(MetadataClosure* f) {
2952   if (has_last_Java_frame()) {
2953     // Traverse the execution stack to call f() on the methods in the stack
2954     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2955       fst.current()->metadata_do(f);
2956     }
2957   } else if (is_Compiler_thread()) {
2958     // need to walk ciMetadata in current compile tasks to keep alive.
2959     CompilerThread* ct = (CompilerThread*)this;
2960     if (ct->env() != NULL) {
2961       ct->env()->metadata_do(f);
2962     }
2963     CompileTask* task = ct->task();
2964     if (task != NULL) {
2965       task->metadata_do(f);
2966     }
2967   }
2968 }
2969 
2970 // Printing
2971 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2972   switch (_thread_state) {
2973   case _thread_uninitialized:     return "_thread_uninitialized";
2974   case _thread_new:               return "_thread_new";
2975   case _thread_new_trans:         return "_thread_new_trans";
2976   case _thread_in_native:         return "_thread_in_native";
2977   case _thread_in_native_trans:   return "_thread_in_native_trans";
2978   case _thread_in_vm:             return "_thread_in_vm";
2979   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
2980   case _thread_in_Java:           return "_thread_in_Java";
2981   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
2982   case _thread_blocked:           return "_thread_blocked";
2983   case _thread_blocked_trans:     return "_thread_blocked_trans";
2984   default:                        return "unknown thread state";
2985   }
2986 }
2987 
2988 #ifndef PRODUCT
2989 void JavaThread::print_thread_state_on(outputStream *st) const {
2990   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
2991 };
2992 void JavaThread::print_thread_state() const {
2993   print_thread_state_on(tty);
2994 }
2995 #endif // PRODUCT
2996 
2997 // Called by Threads::print() for VM_PrintThreads operation
2998 void JavaThread::print_on(outputStream *st, bool print_extended_info) const {
2999   st->print_raw("\"");
3000   st->print_raw(get_thread_name());
3001   st->print_raw("\" ");
3002   oop thread_oop = threadObj();
3003   if (thread_oop != NULL) {
3004     st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
3005     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
3006     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
3007   }
3008   Thread::print_on(st, print_extended_info);
3009   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
3010   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
3011   if (thread_oop != NULL) {
3012     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
3013   }
3014 #ifndef PRODUCT
3015   _safepoint_state->print_on(st);
3016 #endif // PRODUCT
3017   if (is_Compiler_thread()) {
3018     CompileTask *task = ((CompilerThread*)this)->task();
3019     if (task != NULL) {
3020       st->print("   Compiling: ");
3021       task->print(st, NULL, true, false);
3022     } else {
3023       st->print("   No compile task");
3024     }
3025     st->cr();
3026   }
3027 }
3028 
3029 void JavaThread::print() const { print_on(tty); }
3030 
3031 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
3032   st->print("%s", get_thread_name_string(buf, buflen));
3033 }
3034 
3035 // Called by fatal error handler. The difference between this and
3036 // JavaThread::print() is that we can't grab lock or allocate memory.
3037 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
3038   st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
3039   oop thread_obj = threadObj();
3040   if (thread_obj != NULL) {
3041     if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
3042   }
3043   st->print(" [");
3044   st->print("%s", _get_thread_state_name(_thread_state));
3045   if (osthread()) {
3046     st->print(", id=%d", osthread()->thread_id());
3047   }
3048   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
3049             p2i(stack_end()), p2i(stack_base()));
3050   st->print("]");
3051 
3052   ThreadsSMRSupport::print_info_on(this, st);
3053   return;
3054 }
3055 
3056 // Verification
3057 
3058 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3059 
3060 void JavaThread::verify() {
3061   // Verify oops in the thread.
3062   oops_do(&VerifyOopClosure::verify_oop, NULL);
3063 
3064   // Verify the stack frames.
3065   frames_do(frame_verify);
3066 }
3067 
3068 // CR 6300358 (sub-CR 2137150)
3069 // Most callers of this method assume that it can't return NULL but a
3070 // thread may not have a name whilst it is in the process of attaching to
3071 // the VM - see CR 6412693, and there are places where a JavaThread can be
3072 // seen prior to having it's threadObj set (eg JNI attaching threads and
3073 // if vm exit occurs during initialization). These cases can all be accounted
3074 // for such that this method never returns NULL.
3075 const char* JavaThread::get_thread_name() const {
3076 #ifdef ASSERT
3077   // early safepoints can hit while current thread does not yet have TLS
3078   if (!SafepointSynchronize::is_at_safepoint()) {
3079     Thread *cur = Thread::current();
3080     if (!(cur->is_Java_thread() && cur == this)) {
3081       // Current JavaThreads are allowed to get their own name without
3082       // the Threads_lock.
3083       assert_locked_or_safepoint(Threads_lock);
3084     }
3085   }
3086 #endif // ASSERT
3087   return get_thread_name_string();
3088 }
3089 
3090 // Returns a non-NULL representation of this thread's name, or a suitable
3091 // descriptive string if there is no set name
3092 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3093   const char* name_str;
3094   oop thread_obj = threadObj();
3095   if (thread_obj != NULL) {
3096     oop name = java_lang_Thread::name(thread_obj);
3097     if (name != NULL) {
3098       if (buf == NULL) {
3099         name_str = java_lang_String::as_utf8_string(name);
3100       } else {
3101         name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3102       }
3103     } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3104       name_str = "<no-name - thread is attaching>";
3105     } else {
3106       name_str = Thread::name();
3107     }
3108   } else {
3109     name_str = Thread::name();
3110   }
3111   assert(name_str != NULL, "unexpected NULL thread name");
3112   return name_str;
3113 }
3114 
3115 
3116 const char* JavaThread::get_threadgroup_name() const {
3117   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3118   oop thread_obj = threadObj();
3119   if (thread_obj != NULL) {
3120     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3121     if (thread_group != NULL) {
3122       // ThreadGroup.name can be null
3123       return java_lang_ThreadGroup::name(thread_group);
3124     }
3125   }
3126   return NULL;
3127 }
3128 
3129 const char* JavaThread::get_parent_name() const {
3130   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3131   oop thread_obj = threadObj();
3132   if (thread_obj != NULL) {
3133     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3134     if (thread_group != NULL) {
3135       oop parent = java_lang_ThreadGroup::parent(thread_group);
3136       if (parent != NULL) {
3137         // ThreadGroup.name can be null
3138         return java_lang_ThreadGroup::name(parent);
3139       }
3140     }
3141   }
3142   return NULL;
3143 }
3144 
3145 ThreadPriority JavaThread::java_priority() const {
3146   oop thr_oop = threadObj();
3147   if (thr_oop == NULL) return NormPriority; // Bootstrapping
3148   ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3149   assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3150   return priority;
3151 }
3152 
3153 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3154 
3155   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3156   // Link Java Thread object <-> C++ Thread
3157 
3158   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3159   // and put it into a new Handle.  The Handle "thread_oop" can then
3160   // be used to pass the C++ thread object to other methods.
3161 
3162   // Set the Java level thread object (jthread) field of the
3163   // new thread (a JavaThread *) to C++ thread object using the
3164   // "thread_oop" handle.
3165 
3166   // Set the thread field (a JavaThread *) of the
3167   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3168 
3169   Handle thread_oop(Thread::current(),
3170                     JNIHandles::resolve_non_null(jni_thread));
3171   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3172          "must be initialized");
3173   set_threadObj(thread_oop());
3174   java_lang_Thread::set_thread(thread_oop(), this);
3175 
3176   if (prio == NoPriority) {
3177     prio = java_lang_Thread::priority(thread_oop());
3178     assert(prio != NoPriority, "A valid priority should be present");
3179   }
3180 
3181   // Push the Java priority down to the native thread; needs Threads_lock
3182   Thread::set_priority(this, prio);
3183 
3184   // Add the new thread to the Threads list and set it in motion.
3185   // We must have threads lock in order to call Threads::add.
3186   // It is crucial that we do not block before the thread is
3187   // added to the Threads list for if a GC happens, then the java_thread oop
3188   // will not be visited by GC.
3189   Threads::add(this);
3190 }
3191 
3192 oop JavaThread::current_park_blocker() {
3193   // Support for JSR-166 locks
3194   oop thread_oop = threadObj();
3195   if (thread_oop != NULL) {
3196     return java_lang_Thread::park_blocker(thread_oop);
3197   }
3198   return NULL;
3199 }
3200 
3201 
3202 void JavaThread::print_stack_on(outputStream* st) {
3203   if (!has_last_Java_frame()) return;
3204   ResourceMark rm;
3205   HandleMark   hm;
3206 
3207   RegisterMap reg_map(this);
3208   vframe* start_vf = last_java_vframe(&reg_map);
3209   int count = 0;
3210   for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3211     if (f->is_java_frame()) {
3212       javaVFrame* jvf = javaVFrame::cast(f);
3213       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3214 
3215       // Print out lock information
3216       if (JavaMonitorsInStackTrace) {
3217         jvf->print_lock_info_on(st, count);
3218       }
3219     } else {
3220       // Ignore non-Java frames
3221     }
3222 
3223     // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3224     count++;
3225     if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3226   }
3227 }
3228 
3229 
3230 // JVMTI PopFrame support
3231 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3232   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3233   if (in_bytes(size_in_bytes) != 0) {
3234     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3235     _popframe_preserved_args_size = in_bytes(size_in_bytes);
3236     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3237   }
3238 }
3239 
3240 void* JavaThread::popframe_preserved_args() {
3241   return _popframe_preserved_args;
3242 }
3243 
3244 ByteSize JavaThread::popframe_preserved_args_size() {
3245   return in_ByteSize(_popframe_preserved_args_size);
3246 }
3247 
3248 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3249   int sz = in_bytes(popframe_preserved_args_size());
3250   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3251   return in_WordSize(sz / wordSize);
3252 }
3253 
3254 void JavaThread::popframe_free_preserved_args() {
3255   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3256   FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3257   _popframe_preserved_args = NULL;
3258   _popframe_preserved_args_size = 0;
3259 }
3260 
3261 #ifndef PRODUCT
3262 
3263 void JavaThread::trace_frames() {
3264   tty->print_cr("[Describe stack]");
3265   int frame_no = 1;
3266   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3267     tty->print("  %d. ", frame_no++);
3268     fst.current()->print_value_on(tty, this);
3269     tty->cr();
3270   }
3271 }
3272 
3273 class PrintAndVerifyOopClosure: public OopClosure {
3274  protected:
3275   template <class T> inline void do_oop_work(T* p) {
3276     oop obj = RawAccess<>::oop_load(p);
3277     if (obj == NULL) return;
3278     tty->print(INTPTR_FORMAT ": ", p2i(p));
3279     if (oopDesc::is_oop_or_null(obj)) {
3280       if (obj->is_objArray()) {
3281         tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3282       } else {
3283         obj->print();
3284       }
3285     } else {
3286       tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3287     }
3288     tty->cr();
3289   }
3290  public:
3291   virtual void do_oop(oop* p) { do_oop_work(p); }
3292   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
3293 };
3294 
3295 
3296 static void oops_print(frame* f, const RegisterMap *map) {
3297   PrintAndVerifyOopClosure print;
3298   f->print_value();
3299   f->oops_do(&print, NULL, (RegisterMap*)map);
3300 }
3301 
3302 // Print our all the locations that contain oops and whether they are
3303 // valid or not.  This useful when trying to find the oldest frame
3304 // where an oop has gone bad since the frame walk is from youngest to
3305 // oldest.
3306 void JavaThread::trace_oops() {
3307   tty->print_cr("[Trace oops]");
3308   frames_do(oops_print);
3309 }
3310 
3311 
3312 #ifdef ASSERT
3313 // Print or validate the layout of stack frames
3314 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3315   ResourceMark rm;
3316   PRESERVE_EXCEPTION_MARK;
3317   FrameValues values;
3318   int frame_no = 0;
3319   for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3320     fst.current()->describe(values, ++frame_no);
3321     if (depth == frame_no) break;
3322   }
3323   if (validate_only) {
3324     values.validate();
3325   } else {
3326     tty->print_cr("[Describe stack layout]");
3327     values.print(this);
3328   }
3329 }
3330 #endif
3331 
3332 void JavaThread::trace_stack_from(vframe* start_vf) {
3333   ResourceMark rm;
3334   int vframe_no = 1;
3335   for (vframe* f = start_vf; f; f = f->sender()) {
3336     if (f->is_java_frame()) {
3337       javaVFrame::cast(f)->print_activation(vframe_no++);
3338     } else {
3339       f->print();
3340     }
3341     if (vframe_no > StackPrintLimit) {
3342       tty->print_cr("...<more frames>...");
3343       return;
3344     }
3345   }
3346 }
3347 
3348 
3349 void JavaThread::trace_stack() {
3350   if (!has_last_Java_frame()) return;
3351   ResourceMark rm;
3352   HandleMark   hm;
3353   RegisterMap reg_map(this);
3354   trace_stack_from(last_java_vframe(&reg_map));
3355 }
3356 
3357 
3358 #endif // PRODUCT
3359 
3360 
3361 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3362   assert(reg_map != NULL, "a map must be given");
3363   frame f = last_frame();
3364   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3365     if (vf->is_java_frame()) return javaVFrame::cast(vf);
3366   }
3367   return NULL;
3368 }
3369 
3370 
3371 Klass* JavaThread::security_get_caller_class(int depth) {
3372   vframeStream vfst(this);
3373   vfst.security_get_caller_frame(depth);
3374   if (!vfst.at_end()) {
3375     return vfst.method()->method_holder();
3376   }
3377   return NULL;
3378 }
3379 
3380 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3381   assert(thread->is_Compiler_thread(), "must be compiler thread");
3382   CompileBroker::compiler_thread_loop();
3383 }
3384 
3385 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3386   NMethodSweeper::sweeper_loop();
3387 }
3388 
3389 // Create a CompilerThread
3390 CompilerThread::CompilerThread(CompileQueue* queue,
3391                                CompilerCounters* counters)
3392                                : JavaThread(&compiler_thread_entry) {
3393   _env   = NULL;
3394   _log   = NULL;
3395   _task  = NULL;
3396   _queue = queue;
3397   _counters = counters;
3398   _buffer_blob = NULL;
3399   _compiler = NULL;
3400 
3401   // Compiler uses resource area for compilation, let's bias it to mtCompiler
3402   resource_area()->bias_to(mtCompiler);
3403 
3404 #ifndef PRODUCT
3405   _ideal_graph_printer = NULL;
3406 #endif
3407 }
3408 
3409 CompilerThread::~CompilerThread() {
3410   // Delete objects which were allocated on heap.
3411   delete _counters;
3412 }
3413 
3414 bool CompilerThread::can_call_java() const {
3415   return _compiler != NULL && _compiler->is_jvmci();
3416 }
3417 
3418 // Create sweeper thread
3419 CodeCacheSweeperThread::CodeCacheSweeperThread()
3420 : JavaThread(&sweeper_thread_entry) {
3421   _scanned_compiled_method = NULL;
3422 }
3423 
3424 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3425   JavaThread::oops_do(f, cf);
3426   if (_scanned_compiled_method != NULL && cf != NULL) {
3427     // Safepoints can occur when the sweeper is scanning an nmethod so
3428     // process it here to make sure it isn't unloaded in the middle of
3429     // a scan.
3430     cf->do_code_blob(_scanned_compiled_method);
3431   }
3432 }
3433 
3434 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3435   JavaThread::nmethods_do(cf);
3436   if (_scanned_compiled_method != NULL && cf != NULL) {
3437     // Safepoints can occur when the sweeper is scanning an nmethod so
3438     // process it here to make sure it isn't unloaded in the middle of
3439     // a scan.
3440     cf->do_code_blob(_scanned_compiled_method);
3441   }
3442 }
3443 
3444 
3445 // ======= Threads ========
3446 
3447 // The Threads class links together all active threads, and provides
3448 // operations over all threads. It is protected by the Threads_lock,
3449 // which is also used in other global contexts like safepointing.
3450 // ThreadsListHandles are used to safely perform operations on one
3451 // or more threads without the risk of the thread exiting during the
3452 // operation.
3453 //
3454 // Note: The Threads_lock is currently more widely used than we
3455 // would like. We are actively migrating Threads_lock uses to other
3456 // mechanisms in order to reduce Threads_lock contention.
3457 
3458 int         Threads::_number_of_threads = 0;
3459 int         Threads::_number_of_non_daemon_threads = 0;
3460 int         Threads::_return_code = 0;
3461 uintx       Threads::_thread_claim_token = 1; // Never zero.
3462 size_t      JavaThread::_stack_size_at_create = 0;
3463 
3464 #ifdef ASSERT
3465 bool        Threads::_vm_complete = false;
3466 #endif
3467 
3468 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3469   Prefetch::read((void*)addr, prefetch_interval);
3470   return *addr;
3471 }
3472 
3473 // Possibly the ugliest for loop the world has seen. C++ does not allow
3474 // multiple types in the declaration section of the for loop. In this case
3475 // we are only dealing with pointers and hence can cast them. It looks ugly
3476 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3477 #define DO_JAVA_THREADS(LIST, X)                                                                                          \
3478     for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes,                           \
3479              *MACRO_list = (JavaThread*)(LIST),                                                                           \
3480              **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(),  \
3481              **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(),                                     \
3482              *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval);                 \
3483          MACRO_current_p != MACRO_end;                                                                                    \
3484          MACRO_current_p++,                                                                                               \
3485              X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3486 
3487 // All JavaThreads
3488 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3489 
3490 // All NonJavaThreads (i.e., every non-JavaThread in the system).
3491 void Threads::non_java_threads_do(ThreadClosure* tc) {
3492   NoSafepointVerifier nsv(!SafepointSynchronize::is_at_safepoint(), false);
3493   for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) {
3494     tc->do_thread(njti.current());
3495   }
3496 }
3497 
3498 // All JavaThreads
3499 void Threads::java_threads_do(ThreadClosure* tc) {
3500   assert_locked_or_safepoint(Threads_lock);
3501   // ALL_JAVA_THREADS iterates through all JavaThreads.
3502   ALL_JAVA_THREADS(p) {
3503     tc->do_thread(p);
3504   }
3505 }
3506 
3507 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) {
3508   assert_locked_or_safepoint(Threads_lock);
3509   java_threads_do(tc);
3510   tc->do_thread(VMThread::vm_thread());
3511 }
3512 
3513 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
3514 void Threads::threads_do(ThreadClosure* tc) {
3515   assert_locked_or_safepoint(Threads_lock);
3516   java_threads_do(tc);
3517   non_java_threads_do(tc);
3518 }
3519 
3520 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3521   uintx claim_token = Threads::thread_claim_token();
3522   ALL_JAVA_THREADS(p) {
3523     if (p->claim_threads_do(is_par, claim_token)) {
3524       tc->do_thread(p);
3525     }
3526   }
3527   VMThread* vmt = VMThread::vm_thread();
3528   if (vmt->claim_threads_do(is_par, claim_token)) {
3529     tc->do_thread(vmt);
3530   }
3531 }
3532 
3533 // The system initialization in the library has three phases.
3534 //
3535 // Phase 1: java.lang.System class initialization
3536 //     java.lang.System is a primordial class loaded and initialized
3537 //     by the VM early during startup.  java.lang.System.<clinit>
3538 //     only does registerNatives and keeps the rest of the class
3539 //     initialization work later until thread initialization completes.
3540 //
3541 //     System.initPhase1 initializes the system properties, the static
3542 //     fields in, out, and err. Set up java signal handlers, OS-specific
3543 //     system settings, and thread group of the main thread.
3544 static void call_initPhase1(TRAPS) {
3545   Klass* klass =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3546   JavaValue result(T_VOID);
3547   JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3548                                          vmSymbols::void_method_signature(), CHECK);
3549 }
3550 
3551 // Phase 2. Module system initialization
3552 //     This will initialize the module system.  Only java.base classes
3553 //     can be loaded until phase 2 completes.
3554 //
3555 //     Call System.initPhase2 after the compiler initialization and jsr292
3556 //     classes get initialized because module initialization runs a lot of java
3557 //     code, that for performance reasons, should be compiled.  Also, this will
3558 //     enable the startup code to use lambda and other language features in this
3559 //     phase and onward.
3560 //
3561 //     After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3562 static void call_initPhase2(TRAPS) {
3563   TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3564 
3565   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3566 
3567   JavaValue result(T_INT);
3568   JavaCallArguments args;
3569   args.push_int(DisplayVMOutputToStderr);
3570   args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3571   JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3572                                          vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3573   if (result.get_jint() != JNI_OK) {
3574     vm_exit_during_initialization(); // no message or exception
3575   }
3576 
3577   universe_post_module_init();
3578 }
3579 
3580 // Phase 3. final setup - set security manager, system class loader and TCCL
3581 //
3582 //     This will instantiate and set the security manager, set the system class
3583 //     loader as well as the thread context class loader.  The security manager
3584 //     and system class loader may be a custom class loaded from -Xbootclasspath/a,
3585 //     other modules or the application's classpath.
3586 static void call_initPhase3(TRAPS) {
3587   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3588   JavaValue result(T_VOID);
3589   JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3590                                          vmSymbols::void_method_signature(), CHECK);
3591 }
3592 
3593 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3594   TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3595 
3596   if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3597     create_vm_init_libraries();
3598   }
3599 
3600   initialize_class(vmSymbols::java_lang_String(), CHECK);
3601 
3602   // Inject CompactStrings value after the static initializers for String ran.
3603   java_lang_String::set_compact_strings(CompactStrings);
3604 
3605   // Initialize java_lang.System (needed before creating the thread)
3606   initialize_class(vmSymbols::java_lang_System(), CHECK);
3607   // The VM creates & returns objects of this class. Make sure it's initialized.
3608   initialize_class(vmSymbols::java_lang_Class(), CHECK);
3609   initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3610   Handle thread_group = create_initial_thread_group(CHECK);
3611   Universe::set_main_thread_group(thread_group());
3612   initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3613   oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3614   main_thread->set_threadObj(thread_object);
3615 
3616   // Set thread status to running since main thread has
3617   // been started and running.
3618   java_lang_Thread::set_thread_status(thread_object,
3619                                       java_lang_Thread::RUNNABLE);
3620 
3621   // The VM creates objects of this class.
3622   initialize_class(vmSymbols::java_lang_Module(), CHECK);
3623 
3624 #ifdef ASSERT
3625   InstanceKlass *k = SystemDictionary::UnsafeConstants_klass();
3626   assert(k->is_not_initialized(), "UnsafeConstants should not already be initialized");
3627 #endif
3628 
3629   // initialize the hardware-specific constants needed by Unsafe
3630   initialize_class(vmSymbols::jdk_internal_misc_UnsafeConstants(), CHECK);
3631   jdk_internal_misc_UnsafeConstants::set_unsafe_constants();
3632 
3633   // The VM preresolves methods to these classes. Make sure that they get initialized
3634   initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3635   initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3636 
3637   // Phase 1 of the system initialization in the library, java.lang.System class initialization
3638   call_initPhase1(CHECK);
3639 
3640   // get the Java runtime name after java.lang.System is initialized
3641   JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3642   JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3643 
3644   // an instance of OutOfMemory exception has been allocated earlier
3645   initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3646   initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3647   initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3648   initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3649   initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3650   initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3651   initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3652   initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3653 }
3654 
3655 void Threads::initialize_jsr292_core_classes(TRAPS) {
3656   TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3657 
3658   initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3659   initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3660   initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3661   initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3662 }
3663 
3664 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3665   extern void JDK_Version_init();
3666 
3667   // Preinitialize version info.
3668   VM_Version::early_initialize();
3669 
3670   // Check version
3671   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3672 
3673   // Initialize library-based TLS
3674   ThreadLocalStorage::init();
3675 
3676   // Initialize the output stream module
3677   ostream_init();
3678 
3679   // Process java launcher properties.
3680   Arguments::process_sun_java_launcher_properties(args);
3681 
3682   // Initialize the os module
3683   os::init();
3684 
3685   // Record VM creation timing statistics
3686   TraceVmCreationTime create_vm_timer;
3687   create_vm_timer.start();
3688 
3689   // Initialize system properties.
3690   Arguments::init_system_properties();
3691 
3692   // So that JDK version can be used as a discriminator when parsing arguments
3693   JDK_Version_init();
3694 
3695   // Update/Initialize System properties after JDK version number is known
3696   Arguments::init_version_specific_system_properties();
3697 
3698   // Make sure to initialize log configuration *before* parsing arguments
3699   LogConfiguration::initialize(create_vm_timer.begin_time());
3700 
3701   // Parse arguments
3702   // Note: this internally calls os::init_container_support()
3703   jint parse_result = Arguments::parse(args);
3704   if (parse_result != JNI_OK) return parse_result;
3705 
3706   os::init_before_ergo();
3707 
3708   jint ergo_result = Arguments::apply_ergo();
3709   if (ergo_result != JNI_OK) return ergo_result;
3710 
3711   // Final check of all ranges after ergonomics which may change values.
3712   if (!JVMFlagRangeList::check_ranges()) {
3713     return JNI_EINVAL;
3714   }
3715 
3716   // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3717   bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo);
3718   if (!constraint_result) {
3719     return JNI_EINVAL;
3720   }
3721 
3722   JVMFlagWriteableList::mark_startup();
3723 
3724   if (PauseAtStartup) {
3725     os::pause();
3726   }
3727 
3728   HOTSPOT_VM_INIT_BEGIN();
3729 
3730   // Timing (must come after argument parsing)
3731   TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3732 
3733   // Initialize the os module after parsing the args
3734   jint os_init_2_result = os::init_2();
3735   if (os_init_2_result != JNI_OK) return os_init_2_result;
3736 
3737 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
3738   // Initialize assert poison page mechanism.
3739   if (ShowRegistersOnAssert) {
3740     initialize_assert_poison();
3741   }
3742 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
3743 
3744   SafepointMechanism::initialize();
3745 
3746   jint adjust_after_os_result = Arguments::adjust_after_os();
3747   if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3748 
3749   // Initialize output stream logging
3750   ostream_init_log();
3751 
3752   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3753   // Must be before create_vm_init_agents()
3754   if (Arguments::init_libraries_at_startup()) {
3755     convert_vm_init_libraries_to_agents();
3756   }
3757 
3758   // Launch -agentlib/-agentpath and converted -Xrun agents
3759   if (Arguments::init_agents_at_startup()) {
3760     create_vm_init_agents();
3761   }
3762 
3763   // Initialize Threads state
3764   _number_of_threads = 0;
3765   _number_of_non_daemon_threads = 0;
3766 
3767   // Initialize global data structures and create system classes in heap
3768   vm_init_globals();
3769 
3770 #if INCLUDE_JVMCI
3771   if (JVMCICounterSize > 0) {
3772     JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3773     memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3774   } else {
3775     JavaThread::_jvmci_old_thread_counters = NULL;
3776   }
3777 #endif // INCLUDE_JVMCI
3778 
3779   // Attach the main thread to this os thread
3780   JavaThread* main_thread = new JavaThread();
3781   main_thread->set_thread_state(_thread_in_vm);
3782   main_thread->initialize_thread_current();
3783   // must do this before set_active_handles
3784   main_thread->record_stack_base_and_size();
3785   main_thread->register_thread_stack_with_NMT();
3786   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3787 
3788   if (!main_thread->set_as_starting_thread()) {
3789     vm_shutdown_during_initialization(
3790                                       "Failed necessary internal allocation. Out of swap space");
3791     main_thread->smr_delete();
3792     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3793     return JNI_ENOMEM;
3794   }
3795 
3796   // Enable guard page *after* os::create_main_thread(), otherwise it would
3797   // crash Linux VM, see notes in os_linux.cpp.
3798   main_thread->create_stack_guard_pages();
3799 
3800   // Initialize Java-Level synchronization subsystem
3801   ObjectMonitor::Initialize();
3802 
3803   // Initialize global modules
3804   jint status = init_globals();
3805   if (status != JNI_OK) {
3806     main_thread->smr_delete();
3807     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3808     return status;
3809   }
3810 
3811   JFR_ONLY(Jfr::on_vm_init();)
3812 
3813   // Should be done after the heap is fully created
3814   main_thread->cache_global_variables();
3815 
3816   HandleMark hm;
3817 
3818   { MutexLocker mu(Threads_lock);
3819     Threads::add(main_thread);
3820   }
3821 
3822   // Any JVMTI raw monitors entered in onload will transition into
3823   // real raw monitor. VM is setup enough here for raw monitor enter.
3824   JvmtiExport::transition_pending_onload_raw_monitors();
3825 
3826   // Create the VMThread
3827   { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3828 
3829   VMThread::create();
3830     Thread* vmthread = VMThread::vm_thread();
3831 
3832     if (!os::create_thread(vmthread, os::vm_thread)) {
3833       vm_exit_during_initialization("Cannot create VM thread. "
3834                                     "Out of system resources.");
3835     }
3836 
3837     // Wait for the VM thread to become ready, and VMThread::run to initialize
3838     // Monitors can have spurious returns, must always check another state flag
3839     {
3840       MonitorLocker ml(Notify_lock);
3841       os::start_thread(vmthread);
3842       while (vmthread->active_handles() == NULL) {
3843         ml.wait();
3844       }
3845     }
3846   }
3847 
3848   assert(Universe::is_fully_initialized(), "not initialized");
3849   if (VerifyDuringStartup) {
3850     // Make sure we're starting with a clean slate.
3851     VM_Verify verify_op;
3852     VMThread::execute(&verify_op);
3853   }
3854 
3855   // We need this to update the java.vm.info property in case any flags used
3856   // to initially define it have been changed. This is needed for both CDS and
3857   // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info
3858   // is initially computed. See Abstract_VM_Version::vm_info_string().
3859   // This update must happen before we initialize the java classes, but
3860   // after any initialization logic that might modify the flags.
3861   Arguments::update_vm_info_property(VM_Version::vm_info_string());
3862 
3863   Thread* THREAD = Thread::current();
3864 
3865   // Always call even when there are not JVMTI environments yet, since environments
3866   // may be attached late and JVMTI must track phases of VM execution
3867   JvmtiExport::enter_early_start_phase();
3868 
3869   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3870   JvmtiExport::post_early_vm_start();
3871 
3872   initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3873 
3874   quicken_jni_functions();
3875 
3876   // No more stub generation allowed after that point.
3877   StubCodeDesc::freeze();
3878 
3879   // Set flag that basic initialization has completed. Used by exceptions and various
3880   // debug stuff, that does not work until all basic classes have been initialized.
3881   set_init_completed();
3882 
3883   LogConfiguration::post_initialize();
3884   Metaspace::post_initialize();
3885 
3886   HOTSPOT_VM_INIT_END();
3887 
3888   // record VM initialization completion time
3889 #if INCLUDE_MANAGEMENT
3890   Management::record_vm_init_completed();
3891 #endif // INCLUDE_MANAGEMENT
3892 
3893   // Signal Dispatcher needs to be started before VMInit event is posted
3894   os::initialize_jdk_signal_support(CHECK_JNI_ERR);
3895 
3896   // Start Attach Listener if +StartAttachListener or it can't be started lazily
3897   if (!DisableAttachMechanism) {
3898     AttachListener::vm_start();
3899     if (StartAttachListener || AttachListener::init_at_startup()) {
3900       AttachListener::init();
3901     }
3902   }
3903 
3904   // Launch -Xrun agents
3905   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3906   // back-end can launch with -Xdebug -Xrunjdwp.
3907   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3908     create_vm_init_libraries();
3909   }
3910 
3911   if (CleanChunkPoolAsync) {
3912     Chunk::start_chunk_pool_cleaner_task();
3913   }
3914 
3915   // initialize compiler(s)
3916 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3917 #if INCLUDE_JVMCI
3918   bool force_JVMCI_intialization = false;
3919   if (EnableJVMCI) {
3920     // Initialize JVMCI eagerly when it is explicitly requested.
3921     // Or when JVMCILibDumpJNIConfig or JVMCIPrintProperties is enabled.
3922     force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties || JVMCILibDumpJNIConfig;
3923 
3924     if (!force_JVMCI_intialization) {
3925       // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3926       // compilations via JVMCI will not actually block until JVMCI is initialized.
3927       force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3928     }
3929   }
3930 #endif
3931   CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
3932   // Postpone completion of compiler initialization to after JVMCI
3933   // is initialized to avoid timeouts of blocking compilations.
3934   if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
3935     CompileBroker::compilation_init_phase2();
3936   }
3937 #endif
3938 
3939   // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3940   // It is done after compilers are initialized, because otherwise compilations of
3941   // signature polymorphic MH intrinsics can be missed
3942   // (see SystemDictionary::find_method_handle_intrinsic).
3943   initialize_jsr292_core_classes(CHECK_JNI_ERR);
3944 
3945   // This will initialize the module system.  Only java.base classes can be
3946   // loaded until phase 2 completes
3947   call_initPhase2(CHECK_JNI_ERR);
3948 
3949   // Always call even when there are not JVMTI environments yet, since environments
3950   // may be attached late and JVMTI must track phases of VM execution
3951   JvmtiExport::enter_start_phase();
3952 
3953   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3954   JvmtiExport::post_vm_start();
3955 
3956   // Final system initialization including security manager and system class loader
3957   call_initPhase3(CHECK_JNI_ERR);
3958 
3959   // cache the system and platform class loaders
3960   SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3961 
3962 #if INCLUDE_CDS
3963   // capture the module path info from the ModuleEntryTable
3964   ClassLoader::initialize_module_path(THREAD);
3965 #endif
3966 
3967 #if INCLUDE_JVMCI
3968   if (force_JVMCI_intialization) {
3969     JVMCI::initialize_compiler(CHECK_JNI_ERR);
3970     CompileBroker::compilation_init_phase2();
3971   }
3972 #endif
3973 
3974   // Always call even when there are not JVMTI environments yet, since environments
3975   // may be attached late and JVMTI must track phases of VM execution
3976   JvmtiExport::enter_live_phase();
3977 
3978   // Make perfmemory accessible
3979   PerfMemory::set_accessible(true);
3980 
3981   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3982   JvmtiExport::post_vm_initialized();
3983 
3984   JFR_ONLY(Jfr::on_vm_start();)
3985 
3986 #if INCLUDE_MANAGEMENT
3987   Management::initialize(THREAD);
3988 
3989   if (HAS_PENDING_EXCEPTION) {
3990     // management agent fails to start possibly due to
3991     // configuration problem and is responsible for printing
3992     // stack trace if appropriate. Simply exit VM.
3993     vm_exit(1);
3994   }
3995 #endif // INCLUDE_MANAGEMENT
3996 
3997   if (MemProfiling)                   MemProfiler::engage();
3998   StatSampler::engage();
3999   if (CheckJNICalls)                  JniPeriodicChecker::engage();
4000 
4001   BiasedLocking::init();
4002 
4003 #if INCLUDE_RTM_OPT
4004   RTMLockingCounters::init();
4005 #endif
4006 
4007   call_postVMInitHook(THREAD);
4008   // The Java side of PostVMInitHook.run must deal with all
4009   // exceptions and provide means of diagnosis.
4010   if (HAS_PENDING_EXCEPTION) {
4011     CLEAR_PENDING_EXCEPTION;
4012   }
4013 
4014   {
4015     MutexLocker ml(PeriodicTask_lock);
4016     // Make sure the WatcherThread can be started by WatcherThread::start()
4017     // or by dynamic enrollment.
4018     WatcherThread::make_startable();
4019     // Start up the WatcherThread if there are any periodic tasks
4020     // NOTE:  All PeriodicTasks should be registered by now. If they
4021     //   aren't, late joiners might appear to start slowly (we might
4022     //   take a while to process their first tick).
4023     if (PeriodicTask::num_tasks() > 0) {
4024       WatcherThread::start();
4025     }
4026   }
4027 
4028   create_vm_timer.end();
4029 #ifdef ASSERT
4030   _vm_complete = true;
4031 #endif
4032 
4033   if (DumpSharedSpaces) {
4034     MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
4035     ShouldNotReachHere();
4036   }
4037 
4038   return JNI_OK;
4039 }
4040 
4041 // type for the Agent_OnLoad and JVM_OnLoad entry points
4042 extern "C" {
4043   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
4044 }
4045 // Find a command line agent library and return its entry point for
4046 //         -agentlib:  -agentpath:   -Xrun
4047 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
4048 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
4049                                     const char *on_load_symbols[],
4050                                     size_t num_symbol_entries) {
4051   OnLoadEntry_t on_load_entry = NULL;
4052   void *library = NULL;
4053 
4054   if (!agent->valid()) {
4055     char buffer[JVM_MAXPATHLEN];
4056     char ebuf[1024] = "";
4057     const char *name = agent->name();
4058     const char *msg = "Could not find agent library ";
4059 
4060     // First check to see if agent is statically linked into executable
4061     if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
4062       library = agent->os_lib();
4063     } else if (agent->is_absolute_path()) {
4064       library = os::dll_load(name, ebuf, sizeof ebuf);
4065       if (library == NULL) {
4066         const char *sub_msg = " in absolute path, with error: ";
4067         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4068         char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4069         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4070         // If we can't find the agent, exit.
4071         vm_exit_during_initialization(buf, NULL);
4072         FREE_C_HEAP_ARRAY(char, buf);
4073       }
4074     } else {
4075       // Try to load the agent from the standard dll directory
4076       if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4077                              name)) {
4078         library = os::dll_load(buffer, ebuf, sizeof ebuf);
4079       }
4080       if (library == NULL) { // Try the library path directory.
4081         if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4082           library = os::dll_load(buffer, ebuf, sizeof ebuf);
4083         }
4084         if (library == NULL) {
4085           const char *sub_msg = " on the library path, with error: ";
4086           const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4087 
4088           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4089                        strlen(ebuf) + strlen(sub_msg2) + 1;
4090           char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4091           if (!agent->is_instrument_lib()) {
4092             jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4093           } else {
4094             jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4095           }
4096           // If we can't find the agent, exit.
4097           vm_exit_during_initialization(buf, NULL);
4098           FREE_C_HEAP_ARRAY(char, buf);
4099         }
4100       }
4101     }
4102     agent->set_os_lib(library);
4103     agent->set_valid();
4104   }
4105 
4106   // Find the OnLoad function.
4107   on_load_entry =
4108     CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4109                                                           false,
4110                                                           on_load_symbols,
4111                                                           num_symbol_entries));
4112   return on_load_entry;
4113 }
4114 
4115 // Find the JVM_OnLoad entry point
4116 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4117   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4118   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4119 }
4120 
4121 // Find the Agent_OnLoad entry point
4122 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4123   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4124   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4125 }
4126 
4127 // For backwards compatibility with -Xrun
4128 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4129 // treated like -agentpath:
4130 // Must be called before agent libraries are created
4131 void Threads::convert_vm_init_libraries_to_agents() {
4132   AgentLibrary* agent;
4133   AgentLibrary* next;
4134 
4135   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4136     next = agent->next();  // cache the next agent now as this agent may get moved off this list
4137     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4138 
4139     // If there is an JVM_OnLoad function it will get called later,
4140     // otherwise see if there is an Agent_OnLoad
4141     if (on_load_entry == NULL) {
4142       on_load_entry = lookup_agent_on_load(agent);
4143       if (on_load_entry != NULL) {
4144         // switch it to the agent list -- so that Agent_OnLoad will be called,
4145         // JVM_OnLoad won't be attempted and Agent_OnUnload will
4146         Arguments::convert_library_to_agent(agent);
4147       } else {
4148         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4149       }
4150     }
4151   }
4152 }
4153 
4154 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
4155 // Invokes Agent_OnLoad
4156 // Called very early -- before JavaThreads exist
4157 void Threads::create_vm_init_agents() {
4158   extern struct JavaVM_ main_vm;
4159   AgentLibrary* agent;
4160 
4161   JvmtiExport::enter_onload_phase();
4162 
4163   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4164     // CDS dumping does not support native JVMTI agent.
4165     // CDS dumping supports Java agent if the AllowArchivingWithJavaAgent diagnostic option is specified.
4166     if (DumpSharedSpaces || DynamicDumpSharedSpaces) {
4167       if(!agent->is_instrument_lib()) {
4168         vm_exit_during_cds_dumping("CDS dumping does not support native JVMTI agent, name", agent->name());
4169       } else if (!AllowArchivingWithJavaAgent) {
4170         vm_exit_during_cds_dumping(
4171           "Must enable AllowArchivingWithJavaAgent in order to run Java agent during CDS dumping");
4172       }
4173     }
4174 
4175     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
4176 
4177     if (on_load_entry != NULL) {
4178       // Invoke the Agent_OnLoad function
4179       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4180       if (err != JNI_OK) {
4181         vm_exit_during_initialization("agent library failed to init", agent->name());
4182       }
4183     } else {
4184       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4185     }
4186   }
4187 
4188   JvmtiExport::enter_primordial_phase();
4189 }
4190 
4191 extern "C" {
4192   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4193 }
4194 
4195 void Threads::shutdown_vm_agents() {
4196   // Send any Agent_OnUnload notifications
4197   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4198   size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4199   extern struct JavaVM_ main_vm;
4200   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4201 
4202     // Find the Agent_OnUnload function.
4203     Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4204                                                    os::find_agent_function(agent,
4205                                                    false,
4206                                                    on_unload_symbols,
4207                                                    num_symbol_entries));
4208 
4209     // Invoke the Agent_OnUnload function
4210     if (unload_entry != NULL) {
4211       JavaThread* thread = JavaThread::current();
4212       ThreadToNativeFromVM ttn(thread);
4213       HandleMark hm(thread);
4214       (*unload_entry)(&main_vm);
4215     }
4216   }
4217 }
4218 
4219 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4220 // Invokes JVM_OnLoad
4221 void Threads::create_vm_init_libraries() {
4222   extern struct JavaVM_ main_vm;
4223   AgentLibrary* agent;
4224 
4225   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4226     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4227 
4228     if (on_load_entry != NULL) {
4229       // Invoke the JVM_OnLoad function
4230       JavaThread* thread = JavaThread::current();
4231       ThreadToNativeFromVM ttn(thread);
4232       HandleMark hm(thread);
4233       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4234       if (err != JNI_OK) {
4235         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4236       }
4237     } else {
4238       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4239     }
4240   }
4241 }
4242 
4243 
4244 // Last thread running calls java.lang.Shutdown.shutdown()
4245 void JavaThread::invoke_shutdown_hooks() {
4246   HandleMark hm(this);
4247 
4248   // We could get here with a pending exception, if so clear it now.
4249   if (this->has_pending_exception()) {
4250     this->clear_pending_exception();
4251   }
4252 
4253   EXCEPTION_MARK;
4254   Klass* shutdown_klass =
4255     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4256                                       THREAD);
4257   if (shutdown_klass != NULL) {
4258     // SystemDictionary::resolve_or_null will return null if there was
4259     // an exception.  If we cannot load the Shutdown class, just don't
4260     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
4261     // won't be run.  Note that if a shutdown hook was registered,
4262     // the Shutdown class would have already been loaded
4263     // (Runtime.addShutdownHook will load it).
4264     JavaValue result(T_VOID);
4265     JavaCalls::call_static(&result,
4266                            shutdown_klass,
4267                            vmSymbols::shutdown_name(),
4268                            vmSymbols::void_method_signature(),
4269                            THREAD);
4270   }
4271   CLEAR_PENDING_EXCEPTION;
4272 }
4273 
4274 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4275 // the program falls off the end of main(). Another VM exit path is through
4276 // vm_exit() when the program calls System.exit() to return a value or when
4277 // there is a serious error in VM. The two shutdown paths are not exactly
4278 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4279 // and VM_Exit op at VM level.
4280 //
4281 // Shutdown sequence:
4282 //   + Shutdown native memory tracking if it is on
4283 //   + Wait until we are the last non-daemon thread to execute
4284 //     <-- every thing is still working at this moment -->
4285 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4286 //        shutdown hooks
4287 //   + Call before_exit(), prepare for VM exit
4288 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4289 //        currently the only user of this mechanism is File.deleteOnExit())
4290 //      > stop StatSampler, watcher thread, CMS threads,
4291 //        post thread end and vm death events to JVMTI,
4292 //        stop signal thread
4293 //   + Call JavaThread::exit(), it will:
4294 //      > release JNI handle blocks, remove stack guard pages
4295 //      > remove this thread from Threads list
4296 //     <-- no more Java code from this thread after this point -->
4297 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4298 //     the compiler threads at safepoint
4299 //     <-- do not use anything that could get blocked by Safepoint -->
4300 //   + Disable tracing at JNI/JVM barriers
4301 //   + Set _vm_exited flag for threads that are still running native code
4302 //   + Call exit_globals()
4303 //      > deletes tty
4304 //      > deletes PerfMemory resources
4305 //   + Delete this thread
4306 //   + Return to caller
4307 
4308 bool Threads::destroy_vm() {
4309   JavaThread* thread = JavaThread::current();
4310 
4311 #ifdef ASSERT
4312   _vm_complete = false;
4313 #endif
4314   // Wait until we are the last non-daemon thread to execute
4315   { MonitorLocker nu(Threads_lock);
4316     while (Threads::number_of_non_daemon_threads() > 1)
4317       // This wait should make safepoint checks, wait without a timeout,
4318       // and wait as a suspend-equivalent condition.
4319       nu.wait(0, Mutex::_as_suspend_equivalent_flag);
4320   }
4321 
4322   EventShutdown e;
4323   if (e.should_commit()) {
4324     e.set_reason("No remaining non-daemon Java threads");
4325     e.commit();
4326   }
4327 
4328   // Hang forever on exit if we are reporting an error.
4329   if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4330     os::infinite_sleep();
4331   }
4332   os::wait_for_keypress_at_exit();
4333 
4334   // run Java level shutdown hooks
4335   thread->invoke_shutdown_hooks();
4336 
4337   before_exit(thread);
4338 
4339   thread->exit(true);
4340 
4341   // Stop VM thread.
4342   {
4343     // 4945125 The vm thread comes to a safepoint during exit.
4344     // GC vm_operations can get caught at the safepoint, and the
4345     // heap is unparseable if they are caught. Grab the Heap_lock
4346     // to prevent this. The GC vm_operations will not be able to
4347     // queue until after the vm thread is dead. After this point,
4348     // we'll never emerge out of the safepoint before the VM exits.
4349 
4350     MutexLocker ml(Heap_lock, Mutex::_no_safepoint_check_flag);
4351 
4352     VMThread::wait_for_vm_thread_exit();
4353     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4354     VMThread::destroy();
4355   }
4356 
4357   // Now, all Java threads are gone except daemon threads. Daemon threads
4358   // running Java code or in VM are stopped by the Safepoint. However,
4359   // daemon threads executing native code are still running.  But they
4360   // will be stopped at native=>Java/VM barriers. Note that we can't
4361   // simply kill or suspend them, as it is inherently deadlock-prone.
4362 
4363   VM_Exit::set_vm_exited();
4364 
4365   // Clean up ideal graph printers after the VMThread has started
4366   // the final safepoint which will block all the Compiler threads.
4367   // Note that this Thread has already logically exited so the
4368   // clean_up() function's use of a JavaThreadIteratorWithHandle
4369   // would be a problem except set_vm_exited() has remembered the
4370   // shutdown thread which is granted a policy exception.
4371 #if defined(COMPILER2) && !defined(PRODUCT)
4372   IdealGraphPrinter::clean_up();
4373 #endif
4374 
4375   notify_vm_shutdown();
4376 
4377   // exit_globals() will delete tty
4378   exit_globals();
4379 
4380   // We are after VM_Exit::set_vm_exited() so we can't call
4381   // thread->smr_delete() or we will block on the Threads_lock.
4382   // Deleting the shutdown thread here is safe because another
4383   // JavaThread cannot have an active ThreadsListHandle for
4384   // this JavaThread.
4385   delete thread;
4386 
4387 #if INCLUDE_JVMCI
4388   if (JVMCICounterSize > 0) {
4389     FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4390   }
4391 #endif
4392 
4393   LogConfiguration::finalize();
4394 
4395   return true;
4396 }
4397 
4398 
4399 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4400   if (version == JNI_VERSION_1_1) return JNI_TRUE;
4401   return is_supported_jni_version(version);
4402 }
4403 
4404 
4405 jboolean Threads::is_supported_jni_version(jint version) {
4406   if (version == JNI_VERSION_1_2) return JNI_TRUE;
4407   if (version == JNI_VERSION_1_4) return JNI_TRUE;
4408   if (version == JNI_VERSION_1_6) return JNI_TRUE;
4409   if (version == JNI_VERSION_1_8) return JNI_TRUE;
4410   if (version == JNI_VERSION_9) return JNI_TRUE;
4411   if (version == JNI_VERSION_10) return JNI_TRUE;
4412   return JNI_FALSE;
4413 }
4414 
4415 
4416 void Threads::add(JavaThread* p, bool force_daemon) {
4417   // The threads lock must be owned at this point
4418   assert(Threads_lock->owned_by_self(), "must have threads lock");
4419 
4420   BarrierSet::barrier_set()->on_thread_attach(p);
4421 
4422   // Once a JavaThread is added to the Threads list, smr_delete() has
4423   // to be used to delete it. Otherwise we can just delete it directly.
4424   p->set_on_thread_list();
4425 
4426   _number_of_threads++;
4427   oop threadObj = p->threadObj();
4428   bool daemon = true;
4429   // Bootstrapping problem: threadObj can be null for initial
4430   // JavaThread (or for threads attached via JNI)
4431   if ((!force_daemon) && !is_daemon((threadObj))) {
4432     _number_of_non_daemon_threads++;
4433     daemon = false;
4434   }
4435 
4436   ThreadService::add_thread(p, daemon);
4437 
4438   // Maintain fast thread list
4439   ThreadsSMRSupport::add_thread(p);
4440 
4441   // Possible GC point.
4442   Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4443 }
4444 
4445 void Threads::remove(JavaThread* p, bool is_daemon) {
4446 
4447   // Reclaim the ObjectMonitors from the omInUseList and omFreeList of the moribund thread.
4448   ObjectSynchronizer::omFlush(p);
4449 
4450   // Extra scope needed for Thread_lock, so we can check
4451   // that we do not remove thread without safepoint code notice
4452   { MonitorLocker ml(Threads_lock);
4453 
4454     assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4455 
4456     // Maintain fast thread list
4457     ThreadsSMRSupport::remove_thread(p);
4458 
4459     _number_of_threads--;
4460     if (!is_daemon) {
4461       _number_of_non_daemon_threads--;
4462 
4463       // Only one thread left, do a notify on the Threads_lock so a thread waiting
4464       // on destroy_vm will wake up.
4465       if (number_of_non_daemon_threads() == 1) {
4466         ml.notify_all();
4467       }
4468     }
4469     ThreadService::remove_thread(p, is_daemon);
4470 
4471     // Make sure that safepoint code disregard this thread. This is needed since
4472     // the thread might mess around with locks after this point. This can cause it
4473     // to do callbacks into the safepoint code. However, the safepoint code is not aware
4474     // of this thread since it is removed from the queue.
4475     p->set_terminated_value();
4476   } // unlock Threads_lock
4477 
4478   // Since Events::log uses a lock, we grab it outside the Threads_lock
4479   Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4480 }
4481 
4482 // Operations on the Threads list for GC.  These are not explicitly locked,
4483 // but the garbage collector must provide a safe context for them to run.
4484 // In particular, these things should never be called when the Threads_lock
4485 // is held by some other thread. (Note: the Safepoint abstraction also
4486 // uses the Threads_lock to guarantee this property. It also makes sure that
4487 // all threads gets blocked when exiting or starting).
4488 
4489 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4490   ALL_JAVA_THREADS(p) {
4491     p->oops_do(f, cf);
4492   }
4493   VMThread::vm_thread()->oops_do(f, cf);
4494 }
4495 
4496 void Threads::change_thread_claim_token() {
4497   if (++_thread_claim_token == 0) {
4498     // On overflow of the token counter, there is a risk of future
4499     // collisions between a new global token value and a stale token
4500     // for a thread, because not all iterations visit all threads.
4501     // (Though it's pretty much a theoretical concern for non-trivial
4502     // token counter sizes.)  To deal with the possibility, reset all
4503     // the thread tokens to zero on global token overflow.
4504     struct ResetClaims : public ThreadClosure {
4505       virtual void do_thread(Thread* t) {
4506         t->claim_threads_do(false, 0);
4507       }
4508     } reset_claims;
4509     Threads::threads_do(&reset_claims);
4510     // On overflow, update the global token to non-zero, to
4511     // avoid the special "never claimed" initial thread value.
4512     _thread_claim_token = 1;
4513   }
4514 }
4515 
4516 #ifdef ASSERT
4517 void assert_thread_claimed(const char* kind, Thread* t, uintx expected) {
4518   const uintx token = t->threads_do_token();
4519   assert(token == expected,
4520          "%s " PTR_FORMAT " has incorrect value " UINTX_FORMAT " != "
4521          UINTX_FORMAT, kind, p2i(t), token, expected);
4522 }
4523 
4524 void Threads::assert_all_threads_claimed() {
4525   ALL_JAVA_THREADS(p) {
4526     assert_thread_claimed("Thread", p, _thread_claim_token);
4527   }
4528   assert_thread_claimed("VMThread", VMThread::vm_thread(), _thread_claim_token);
4529 }
4530 #endif // ASSERT
4531 
4532 class ParallelOopsDoThreadClosure : public ThreadClosure {
4533 private:
4534   OopClosure* _f;
4535   CodeBlobClosure* _cf;
4536 public:
4537   ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4538   void do_thread(Thread* t) {
4539     t->oops_do(_f, _cf);
4540   }
4541 };
4542 
4543 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4544   ParallelOopsDoThreadClosure tc(f, cf);
4545   possibly_parallel_threads_do(is_par, &tc);
4546 }
4547 
4548 void Threads::nmethods_do(CodeBlobClosure* cf) {
4549   ALL_JAVA_THREADS(p) {
4550     // This is used by the code cache sweeper to mark nmethods that are active
4551     // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4552     // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4553     if(!p->is_Code_cache_sweeper_thread()) {
4554       p->nmethods_do(cf);
4555     }
4556   }
4557 }
4558 
4559 void Threads::metadata_do(MetadataClosure* f) {
4560   ALL_JAVA_THREADS(p) {
4561     p->metadata_do(f);
4562   }
4563 }
4564 
4565 class ThreadHandlesClosure : public ThreadClosure {
4566   void (*_f)(Metadata*);
4567  public:
4568   ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4569   virtual void do_thread(Thread* thread) {
4570     thread->metadata_handles_do(_f);
4571   }
4572 };
4573 
4574 void Threads::metadata_handles_do(void f(Metadata*)) {
4575   // Only walk the Handles in Thread.
4576   ThreadHandlesClosure handles_closure(f);
4577   threads_do(&handles_closure);
4578 }
4579 
4580 // Get count Java threads that are waiting to enter the specified monitor.
4581 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4582                                                          int count,
4583                                                          address monitor) {
4584   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4585 
4586   int i = 0;
4587   DO_JAVA_THREADS(t_list, p) {
4588     if (!p->can_call_java()) continue;
4589 
4590     address pending = (address)p->current_pending_monitor();
4591     if (pending == monitor) {             // found a match
4592       if (i < count) result->append(p);   // save the first count matches
4593       i++;
4594     }
4595   }
4596 
4597   return result;
4598 }
4599 
4600 
4601 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4602                                                       address owner) {
4603   // NULL owner means not locked so we can skip the search
4604   if (owner == NULL) return NULL;
4605 
4606   DO_JAVA_THREADS(t_list, p) {
4607     // first, see if owner is the address of a Java thread
4608     if (owner == (address)p) return p;
4609   }
4610 
4611   // Cannot assert on lack of success here since this function may be
4612   // used by code that is trying to report useful problem information
4613   // like deadlock detection.
4614   if (UseHeavyMonitors) return NULL;
4615 
4616   // If we didn't find a matching Java thread and we didn't force use of
4617   // heavyweight monitors, then the owner is the stack address of the
4618   // Lock Word in the owning Java thread's stack.
4619   //
4620   JavaThread* the_owner = NULL;
4621   DO_JAVA_THREADS(t_list, q) {
4622     if (q->is_lock_owned(owner)) {
4623       the_owner = q;
4624       break;
4625     }
4626   }
4627 
4628   // cannot assert on lack of success here; see above comment
4629   return the_owner;
4630 }
4631 
4632 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4633 void Threads::print_on(outputStream* st, bool print_stacks,
4634                        bool internal_format, bool print_concurrent_locks,
4635                        bool print_extended_info) {
4636   char buf[32];
4637   st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4638 
4639   st->print_cr("Full thread dump %s (%s %s):",
4640                VM_Version::vm_name(),
4641                VM_Version::vm_release(),
4642                VM_Version::vm_info_string());
4643   st->cr();
4644 
4645 #if INCLUDE_SERVICES
4646   // Dump concurrent locks
4647   ConcurrentLocksDump concurrent_locks;
4648   if (print_concurrent_locks) {
4649     concurrent_locks.dump_at_safepoint();
4650   }
4651 #endif // INCLUDE_SERVICES
4652 
4653   ThreadsSMRSupport::print_info_on(st);
4654   st->cr();
4655 
4656   ALL_JAVA_THREADS(p) {
4657     ResourceMark rm;
4658     p->print_on(st, print_extended_info);
4659     if (print_stacks) {
4660       if (internal_format) {
4661         p->trace_stack();
4662       } else {
4663         p->print_stack_on(st);
4664       }
4665     }
4666     st->cr();
4667 #if INCLUDE_SERVICES
4668     if (print_concurrent_locks) {
4669       concurrent_locks.print_locks_on(p, st);
4670     }
4671 #endif // INCLUDE_SERVICES
4672   }
4673 
4674   VMThread::vm_thread()->print_on(st);
4675   st->cr();
4676   Universe::heap()->print_gc_threads_on(st);
4677   WatcherThread* wt = WatcherThread::watcher_thread();
4678   if (wt != NULL) {
4679     wt->print_on(st);
4680     st->cr();
4681   }
4682 
4683   st->flush();
4684 }
4685 
4686 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4687                              int buflen, bool* found_current) {
4688   if (this_thread != NULL) {
4689     bool is_current = (current == this_thread);
4690     *found_current = *found_current || is_current;
4691     st->print("%s", is_current ? "=>" : "  ");
4692 
4693     st->print(PTR_FORMAT, p2i(this_thread));
4694     st->print(" ");
4695     this_thread->print_on_error(st, buf, buflen);
4696     st->cr();
4697   }
4698 }
4699 
4700 class PrintOnErrorClosure : public ThreadClosure {
4701   outputStream* _st;
4702   Thread* _current;
4703   char* _buf;
4704   int _buflen;
4705   bool* _found_current;
4706  public:
4707   PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4708                       int buflen, bool* found_current) :
4709    _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4710 
4711   virtual void do_thread(Thread* thread) {
4712     Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4713   }
4714 };
4715 
4716 // Threads::print_on_error() is called by fatal error handler. It's possible
4717 // that VM is not at safepoint and/or current thread is inside signal handler.
4718 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4719 // memory (even in resource area), it might deadlock the error handler.
4720 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4721                              int buflen) {
4722   ThreadsSMRSupport::print_info_on(st);
4723   st->cr();
4724 
4725   bool found_current = false;
4726   st->print_cr("Java Threads: ( => current thread )");
4727   ALL_JAVA_THREADS(thread) {
4728     print_on_error(thread, st, current, buf, buflen, &found_current);
4729   }
4730   st->cr();
4731 
4732   st->print_cr("Other Threads:");
4733   print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4734   print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4735 
4736   PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4737   Universe::heap()->gc_threads_do(&print_closure);
4738 
4739   if (!found_current) {
4740     st->cr();
4741     st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4742     current->print_on_error(st, buf, buflen);
4743     st->cr();
4744   }
4745   st->cr();
4746 
4747   st->print_cr("Threads with active compile tasks:");
4748   print_threads_compiling(st, buf, buflen);
4749 }
4750 
4751 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen, bool short_form) {
4752   ALL_JAVA_THREADS(thread) {
4753     if (thread->is_Compiler_thread()) {
4754       CompilerThread* ct = (CompilerThread*) thread;
4755 
4756       // Keep task in local variable for NULL check.
4757       // ct->_task might be set to NULL by concurring compiler thread
4758       // because it completed the compilation. The task is never freed,
4759       // though, just returned to a free list.
4760       CompileTask* task = ct->task();
4761       if (task != NULL) {
4762         thread->print_name_on_error(st, buf, buflen);
4763         st->print("  ");
4764         task->print(st, NULL, short_form, true);
4765       }
4766     }
4767   }
4768 }
4769 
4770 
4771 // Internal SpinLock and Mutex
4772 // Based on ParkEvent
4773 
4774 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4775 //
4776 // We employ SpinLocks _only for low-contention, fixed-length
4777 // short-duration critical sections where we're concerned
4778 // about native mutex_t or HotSpot Mutex:: latency.
4779 // The mux construct provides a spin-then-block mutual exclusion
4780 // mechanism.
4781 //
4782 // Testing has shown that contention on the ListLock guarding gFreeList
4783 // is common.  If we implement ListLock as a simple SpinLock it's common
4784 // for the JVM to devolve to yielding with little progress.  This is true
4785 // despite the fact that the critical sections protected by ListLock are
4786 // extremely short.
4787 //
4788 // TODO-FIXME: ListLock should be of type SpinLock.
4789 // We should make this a 1st-class type, integrated into the lock
4790 // hierarchy as leaf-locks.  Critically, the SpinLock structure
4791 // should have sufficient padding to avoid false-sharing and excessive
4792 // cache-coherency traffic.
4793 
4794 
4795 typedef volatile int SpinLockT;
4796 
4797 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4798   if (Atomic::cmpxchg (1, adr, 0) == 0) {
4799     return;   // normal fast-path return
4800   }
4801 
4802   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4803   int ctr = 0;
4804   int Yields = 0;
4805   for (;;) {
4806     while (*adr != 0) {
4807       ++ctr;
4808       if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4809         if (Yields > 5) {
4810           os::naked_short_sleep(1);
4811         } else {
4812           os::naked_yield();
4813           ++Yields;
4814         }
4815       } else {
4816         SpinPause();
4817       }
4818     }
4819     if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4820   }
4821 }
4822 
4823 void Thread::SpinRelease(volatile int * adr) {
4824   assert(*adr != 0, "invariant");
4825   OrderAccess::fence();      // guarantee at least release consistency.
4826   // Roach-motel semantics.
4827   // It's safe if subsequent LDs and STs float "up" into the critical section,
4828   // but prior LDs and STs within the critical section can't be allowed
4829   // to reorder or float past the ST that releases the lock.
4830   // Loads and stores in the critical section - which appear in program
4831   // order before the store that releases the lock - must also appear
4832   // before the store that releases the lock in memory visibility order.
4833   // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4834   // the ST of 0 into the lock-word which releases the lock, so fence
4835   // more than covers this on all platforms.
4836   *adr = 0;
4837 }
4838 
4839 // muxAcquire and muxRelease:
4840 //
4841 // *  muxAcquire and muxRelease support a single-word lock-word construct.
4842 //    The LSB of the word is set IFF the lock is held.
4843 //    The remainder of the word points to the head of a singly-linked list
4844 //    of threads blocked on the lock.
4845 //
4846 // *  The current implementation of muxAcquire-muxRelease uses its own
4847 //    dedicated Thread._MuxEvent instance.  If we're interested in
4848 //    minimizing the peak number of extant ParkEvent instances then
4849 //    we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4850 //    as certain invariants were satisfied.  Specifically, care would need
4851 //    to be taken with regards to consuming unpark() "permits".
4852 //    A safe rule of thumb is that a thread would never call muxAcquire()
4853 //    if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4854 //    park().  Otherwise the _ParkEvent park() operation in muxAcquire() could
4855 //    consume an unpark() permit intended for monitorenter, for instance.
4856 //    One way around this would be to widen the restricted-range semaphore
4857 //    implemented in park().  Another alternative would be to provide
4858 //    multiple instances of the PlatformEvent() for each thread.  One
4859 //    instance would be dedicated to muxAcquire-muxRelease, for instance.
4860 //
4861 // *  Usage:
4862 //    -- Only as leaf locks
4863 //    -- for short-term locking only as muxAcquire does not perform
4864 //       thread state transitions.
4865 //
4866 // Alternatives:
4867 // *  We could implement muxAcquire and muxRelease with MCS or CLH locks
4868 //    but with parking or spin-then-park instead of pure spinning.
4869 // *  Use Taura-Oyama-Yonenzawa locks.
4870 // *  It's possible to construct a 1-0 lock if we encode the lockword as
4871 //    (List,LockByte).  Acquire will CAS the full lockword while Release
4872 //    will STB 0 into the LockByte.  The 1-0 scheme admits stranding, so
4873 //    acquiring threads use timers (ParkTimed) to detect and recover from
4874 //    the stranding window.  Thread/Node structures must be aligned on 256-byte
4875 //    boundaries by using placement-new.
4876 // *  Augment MCS with advisory back-link fields maintained with CAS().
4877 //    Pictorially:  LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4878 //    The validity of the backlinks must be ratified before we trust the value.
4879 //    If the backlinks are invalid the exiting thread must back-track through the
4880 //    the forward links, which are always trustworthy.
4881 // *  Add a successor indication.  The LockWord is currently encoded as
4882 //    (List, LOCKBIT:1).  We could also add a SUCCBIT or an explicit _succ variable
4883 //    to provide the usual futile-wakeup optimization.
4884 //    See RTStt for details.
4885 //
4886 
4887 
4888 const intptr_t LOCKBIT = 1;
4889 
4890 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4891   intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4892   if (w == 0) return;
4893   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4894     return;
4895   }
4896 
4897   ParkEvent * const Self = Thread::current()->_MuxEvent;
4898   assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4899   for (;;) {
4900     int its = (os::is_MP() ? 100 : 0) + 1;
4901 
4902     // Optional spin phase: spin-then-park strategy
4903     while (--its >= 0) {
4904       w = *Lock;
4905       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4906         return;
4907       }
4908     }
4909 
4910     Self->reset();
4911     Self->OnList = intptr_t(Lock);
4912     // The following fence() isn't _strictly necessary as the subsequent
4913     // CAS() both serializes execution and ratifies the fetched *Lock value.
4914     OrderAccess::fence();
4915     for (;;) {
4916       w = *Lock;
4917       if ((w & LOCKBIT) == 0) {
4918         if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4919           Self->OnList = 0;   // hygiene - allows stronger asserts
4920           return;
4921         }
4922         continue;      // Interference -- *Lock changed -- Just retry
4923       }
4924       assert(w & LOCKBIT, "invariant");
4925       Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4926       if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4927     }
4928 
4929     while (Self->OnList != 0) {
4930       Self->park();
4931     }
4932   }
4933 }
4934 
4935 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4936   intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4937   if (w == 0) return;
4938   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4939     return;
4940   }
4941 
4942   ParkEvent * ReleaseAfter = NULL;
4943   if (ev == NULL) {
4944     ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4945   }
4946   assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4947   for (;;) {
4948     guarantee(ev->OnList == 0, "invariant");
4949     int its = (os::is_MP() ? 100 : 0) + 1;
4950 
4951     // Optional spin phase: spin-then-park strategy
4952     while (--its >= 0) {
4953       w = *Lock;
4954       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4955         if (ReleaseAfter != NULL) {
4956           ParkEvent::Release(ReleaseAfter);
4957         }
4958         return;
4959       }
4960     }
4961 
4962     ev->reset();
4963     ev->OnList = intptr_t(Lock);
4964     // The following fence() isn't _strictly necessary as the subsequent
4965     // CAS() both serializes execution and ratifies the fetched *Lock value.
4966     OrderAccess::fence();
4967     for (;;) {
4968       w = *Lock;
4969       if ((w & LOCKBIT) == 0) {
4970         if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4971           ev->OnList = 0;
4972           // We call ::Release while holding the outer lock, thus
4973           // artificially lengthening the critical section.
4974           // Consider deferring the ::Release() until the subsequent unlock(),
4975           // after we've dropped the outer lock.
4976           if (ReleaseAfter != NULL) {
4977             ParkEvent::Release(ReleaseAfter);
4978           }
4979           return;
4980         }
4981         continue;      // Interference -- *Lock changed -- Just retry
4982       }
4983       assert(w & LOCKBIT, "invariant");
4984       ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4985       if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4986     }
4987 
4988     while (ev->OnList != 0) {
4989       ev->park();
4990     }
4991   }
4992 }
4993 
4994 // Release() must extract a successor from the list and then wake that thread.
4995 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4996 // similar to that used by ParkEvent::Allocate() and ::Release().  DMR-based
4997 // Release() would :
4998 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4999 // (B) Extract a successor from the private list "in-hand"
5000 // (C) attempt to CAS() the residual back into *Lock over null.
5001 //     If there were any newly arrived threads and the CAS() would fail.
5002 //     In that case Release() would detach the RATs, re-merge the list in-hand
5003 //     with the RATs and repeat as needed.  Alternately, Release() might
5004 //     detach and extract a successor, but then pass the residual list to the wakee.
5005 //     The wakee would be responsible for reattaching and remerging before it
5006 //     competed for the lock.
5007 //
5008 // Both "pop" and DMR are immune from ABA corruption -- there can be
5009 // multiple concurrent pushers, but only one popper or detacher.
5010 // This implementation pops from the head of the list.  This is unfair,
5011 // but tends to provide excellent throughput as hot threads remain hot.
5012 // (We wake recently run threads first).
5013 //
5014 // All paths through muxRelease() will execute a CAS.
5015 // Release consistency -- We depend on the CAS in muxRelease() to provide full
5016 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
5017 // executed within the critical section are complete and globally visible before the
5018 // store (CAS) to the lock-word that releases the lock becomes globally visible.
5019 void Thread::muxRelease(volatile intptr_t * Lock)  {
5020   for (;;) {
5021     const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
5022     assert(w & LOCKBIT, "invariant");
5023     if (w == LOCKBIT) return;
5024     ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
5025     assert(List != NULL, "invariant");
5026     assert(List->OnList == intptr_t(Lock), "invariant");
5027     ParkEvent * const nxt = List->ListNext;
5028     guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
5029 
5030     // The following CAS() releases the lock and pops the head element.
5031     // The CAS() also ratifies the previously fetched lock-word value.
5032     if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
5033       continue;
5034     }
5035     List->OnList = 0;
5036     OrderAccess::fence();
5037     List->unpark();
5038     return;
5039   }
5040 }
5041 
5042 
5043 void Threads::verify() {
5044   ALL_JAVA_THREADS(p) {
5045     p->verify();
5046   }
5047   VMThread* thread = VMThread::vm_thread();
5048   if (thread != NULL) thread->verify();
5049 }