1 /*
   2  * Copyright (c) 1997, 2015, 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 "classfile/classLoader.hpp"
  27 #include "classfile/javaClasses.hpp"
  28 #include "classfile/systemDictionary.hpp"
  29 #include "classfile/vmSymbols.hpp"
  30 #include "code/codeCache.hpp"
  31 #include "code/codeCacheExtensions.hpp"
  32 #include "code/scopeDesc.hpp"
  33 #include "compiler/compileBroker.hpp"
  34 #include "gc/shared/gcId.hpp"
  35 #include "gc/shared/gcLocker.inline.hpp"
  36 #include "gc/shared/workgroup.hpp"
  37 #include "interpreter/interpreter.hpp"
  38 #include "interpreter/linkResolver.hpp"
  39 #include "interpreter/oopMapCache.hpp"
  40 #include "jvmtifiles/jvmtiEnv.hpp"
  41 #include "logging/logConfiguration.hpp"
  42 #include "memory/metaspaceShared.hpp"
  43 #include "memory/oopFactory.hpp"
  44 #include "memory/universe.inline.hpp"
  45 #include "oops/instanceKlass.hpp"
  46 #include "oops/objArrayOop.hpp"
  47 #include "oops/oop.inline.hpp"
  48 #include "oops/symbol.hpp"
  49 #include "oops/verifyOopClosure.hpp"
  50 #include "prims/jvm_misc.hpp"
  51 #include "prims/jvmtiExport.hpp"
  52 #include "prims/jvmtiThreadState.hpp"
  53 #include "prims/privilegedStack.hpp"
  54 #include "runtime/arguments.hpp"
  55 #include "runtime/atomic.inline.hpp"
  56 #include "runtime/biasedLocking.hpp"
  57 #include "runtime/commandLineFlagConstraintList.hpp"
  58 #include "runtime/commandLineFlagRangeList.hpp"
  59 #include "runtime/deoptimization.hpp"
  60 #include "runtime/fprofiler.hpp"
  61 #include "runtime/frame.inline.hpp"
  62 #include "runtime/globals.hpp"
  63 #include "runtime/init.hpp"
  64 #include "runtime/interfaceSupport.hpp"
  65 #include "runtime/java.hpp"
  66 #include "runtime/javaCalls.hpp"
  67 #include "runtime/jniPeriodicChecker.hpp"
  68 #include "runtime/memprofiler.hpp"
  69 #include "runtime/mutexLocker.hpp"
  70 #include "runtime/objectMonitor.hpp"
  71 #include "runtime/orderAccess.inline.hpp"
  72 #include "runtime/osThread.hpp"
  73 #include "runtime/safepoint.hpp"
  74 #include "runtime/sharedRuntime.hpp"
  75 #include "runtime/statSampler.hpp"
  76 #include "runtime/stubRoutines.hpp"
  77 #include "runtime/sweeper.hpp"
  78 #include "runtime/task.hpp"
  79 #include "runtime/thread.inline.hpp"
  80 #include "runtime/threadCritical.hpp"
  81 #include "runtime/vframe.hpp"
  82 #include "runtime/vframeArray.hpp"
  83 #include "runtime/vframe_hp.hpp"
  84 #include "runtime/vmThread.hpp"
  85 #include "runtime/vm_operations.hpp"
  86 #include "runtime/vm_version.hpp"
  87 #include "services/attachListener.hpp"
  88 #include "services/management.hpp"
  89 #include "services/memTracker.hpp"
  90 #include "services/threadService.hpp"
  91 #include "trace/traceMacros.hpp"
  92 #include "trace/tracing.hpp"
  93 #include "utilities/defaultStream.hpp"
  94 #include "utilities/dtrace.hpp"
  95 #include "utilities/events.hpp"
  96 #include "utilities/macros.hpp"
  97 #include "utilities/preserveException.hpp"
  98 #if INCLUDE_ALL_GCS
  99 #include "gc/cms/concurrentMarkSweepThread.hpp"
 100 #include "gc/g1/concurrentMarkThread.inline.hpp"
 101 #include "gc/parallel/pcTasks.hpp"
 102 #endif // INCLUDE_ALL_GCS
 103 #if INCLUDE_JVMCI
 104 #include "jvmci/jvmciCompiler.hpp"
 105 #include "jvmci/jvmciRuntime.hpp"
 106 #endif
 107 #ifdef COMPILER1
 108 #include "c1/c1_Compiler.hpp"
 109 #endif
 110 #ifdef COMPILER2
 111 #include "opto/c2compiler.hpp"
 112 #include "opto/idealGraphPrinter.hpp"
 113 #endif
 114 #if INCLUDE_RTM_OPT
 115 #include "runtime/rtmLocking.hpp"
 116 #endif
 117 
 118 #ifdef DTRACE_ENABLED
 119 
 120 // Only bother with this argument setup if dtrace is available
 121 
 122   #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
 123   #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
 124 
 125   #define DTRACE_THREAD_PROBE(probe, javathread)                           \
 126     {                                                                      \
 127       ResourceMark rm(this);                                               \
 128       int len = 0;                                                         \
 129       const char* name = (javathread)->get_thread_name();                  \
 130       len = strlen(name);                                                  \
 131       HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */               \
 132         (char *) name, len,                                                \
 133         java_lang_Thread::thread_id((javathread)->threadObj()),            \
 134         (uintptr_t) (javathread)->osthread()->thread_id(),                 \
 135         java_lang_Thread::is_daemon((javathread)->threadObj()));           \
 136     }
 137 
 138 #else //  ndef DTRACE_ENABLED
 139 
 140   #define DTRACE_THREAD_PROBE(probe, javathread)
 141 
 142 #endif // ndef DTRACE_ENABLED
 143 
 144 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 145 // Current thread is maintained as a thread-local variable
 146 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
 147 #endif
 148 
 149 // Class hierarchy
 150 // - Thread
 151 //   - VMThread
 152 //   - WatcherThread
 153 //   - ConcurrentMarkSweepThread
 154 //   - JavaThread
 155 //     - CompilerThread
 156 
 157 // ======= Thread ========
 158 // Support for forcing alignment of thread objects for biased locking
 159 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
 160   if (UseBiasedLocking) {
 161     const int alignment = markOopDesc::biased_lock_alignment;
 162     size_t aligned_size = size + (alignment - sizeof(intptr_t));
 163     void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
 164                                           : AllocateHeap(aligned_size, flags, CURRENT_PC,
 165                                                          AllocFailStrategy::RETURN_NULL);
 166     void* aligned_addr     = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
 167     assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
 168            ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
 169            "JavaThread alignment code overflowed allocated storage");
 170     if (TraceBiasedLocking) {
 171       if (aligned_addr != real_malloc_addr) {
 172         tty->print_cr("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
 173                       p2i(real_malloc_addr), p2i(aligned_addr));
 174       }
 175     }
 176     ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
 177     return aligned_addr;
 178   } else {
 179     return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
 180                        : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
 181   }
 182 }
 183 
 184 void Thread::operator delete(void* p) {
 185   if (UseBiasedLocking) {
 186     void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
 187     FreeHeap(real_malloc_addr);
 188   } else {
 189     FreeHeap(p);
 190   }
 191 }
 192 
 193 
 194 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
 195 // JavaThread
 196 
 197 
 198 Thread::Thread() {
 199   // stack and get_thread
 200   set_stack_base(NULL);
 201   set_stack_size(0);
 202   set_self_raw_id(0);
 203   set_lgrp_id(-1);
 204   DEBUG_ONLY(clear_suspendible_thread();)
 205 
 206   // allocated data structures
 207   set_osthread(NULL);
 208   set_resource_area(new (mtThread)ResourceArea());
 209   DEBUG_ONLY(_current_resource_mark = NULL;)
 210   set_handle_area(new (mtThread) HandleArea(NULL));
 211   set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
 212   set_active_handles(NULL);
 213   set_free_handle_block(NULL);
 214   set_last_handle_mark(NULL);
 215 
 216   // This initial value ==> never claimed.
 217   _oops_do_parity = 0;
 218 
 219   // the handle mark links itself to last_handle_mark
 220   new HandleMark(this);
 221 
 222   // plain initialization
 223   debug_only(_owned_locks = NULL;)
 224   debug_only(_allow_allocation_count = 0;)
 225   NOT_PRODUCT(_allow_safepoint_count = 0;)
 226   NOT_PRODUCT(_skip_gcalot = false;)
 227   _jvmti_env_iteration_count = 0;
 228   set_allocated_bytes(0);
 229   _vm_operation_started_count = 0;
 230   _vm_operation_completed_count = 0;
 231   _current_pending_monitor = NULL;
 232   _current_pending_monitor_is_from_java = true;
 233   _current_waiting_monitor = NULL;
 234   _num_nested_signal = 0;
 235   omFreeList = NULL;
 236   omFreeCount = 0;
 237   omFreeProvision = 32;
 238   omInUseList = NULL;
 239   omInUseCount = 0;
 240 
 241 #ifdef ASSERT
 242   _visited_for_critical_count = false;
 243 #endif
 244 
 245   _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
 246                          Monitor::_safepoint_check_sometimes);
 247   _suspend_flags = 0;
 248 
 249   // thread-specific hashCode stream generator state - Marsaglia shift-xor form
 250   _hashStateX = os::random();
 251   _hashStateY = 842502087;
 252   _hashStateZ = 0x8767;    // (int)(3579807591LL & 0xffff) ;
 253   _hashStateW = 273326509;
 254 
 255   _OnTrap   = 0;
 256   _schedctl = NULL;
 257   _Stalled  = 0;
 258   _TypeTag  = 0x2BAD;
 259 
 260   // Many of the following fields are effectively final - immutable
 261   // Note that nascent threads can't use the Native Monitor-Mutex
 262   // construct until the _MutexEvent is initialized ...
 263   // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
 264   // we might instead use a stack of ParkEvents that we could provision on-demand.
 265   // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
 266   // and ::Release()
 267   _ParkEvent   = ParkEvent::Allocate(this);
 268   _SleepEvent  = ParkEvent::Allocate(this);
 269   _MutexEvent  = ParkEvent::Allocate(this);
 270   _MuxEvent    = ParkEvent::Allocate(this);
 271 
 272 #ifdef CHECK_UNHANDLED_OOPS
 273   if (CheckUnhandledOops) {
 274     _unhandled_oops = new UnhandledOops(this);
 275   }
 276 #endif // CHECK_UNHANDLED_OOPS
 277 #ifdef ASSERT
 278   if (UseBiasedLocking) {
 279     assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
 280     assert(this == _real_malloc_address ||
 281            this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
 282            "bug in forced alignment of thread objects");
 283   }
 284 #endif // ASSERT
 285 }
 286 
 287 void Thread::initialize_thread_current() {
 288 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 289   assert(_thr_current == NULL, "Thread::current already initialized");
 290   _thr_current = this;
 291 #endif
 292   assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
 293   ThreadLocalStorage::set_thread(this);
 294   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 295 }
 296 
 297 void Thread::clear_thread_current() {
 298   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 299 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 300   _thr_current = NULL;
 301 #endif
 302   ThreadLocalStorage::set_thread(NULL);
 303 }
 304 
 305 void Thread::record_stack_base_and_size() {
 306   set_stack_base(os::current_stack_base());
 307   set_stack_size(os::current_stack_size());
 308   if (is_Java_thread()) {
 309     ((JavaThread*) this)->set_stack_overflow_limit();
 310     ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
 311   }
 312   // CR 7190089: on Solaris, primordial thread's stack is adjusted
 313   // in initialize_thread(). Without the adjustment, stack size is
 314   // incorrect if stack is set to unlimited (ulimit -s unlimited).
 315   // So far, only Solaris has real implementation of initialize_thread().
 316   //
 317   // set up any platform-specific state.
 318   os::initialize_thread(this);
 319 
 320 #if INCLUDE_NMT
 321   // record thread's native stack, stack grows downward
 322   address stack_low_addr = stack_base() - stack_size();
 323   MemTracker::record_thread_stack(stack_low_addr, stack_size());
 324 #endif // INCLUDE_NMT
 325 }
 326 
 327 
 328 Thread::~Thread() {
 329   // Reclaim the objectmonitors from the omFreeList of the moribund thread.
 330   ObjectSynchronizer::omFlush(this);
 331 
 332   EVENT_THREAD_DESTRUCT(this);
 333 
 334   // stack_base can be NULL if the thread is never started or exited before
 335   // record_stack_base_and_size called. Although, we would like to ensure
 336   // that all started threads do call record_stack_base_and_size(), there is
 337   // not proper way to enforce that.
 338 #if INCLUDE_NMT
 339   if (_stack_base != NULL) {
 340     address low_stack_addr = stack_base() - stack_size();
 341     MemTracker::release_thread_stack(low_stack_addr, stack_size());
 342 #ifdef ASSERT
 343     set_stack_base(NULL);
 344 #endif
 345   }
 346 #endif // INCLUDE_NMT
 347 
 348   // deallocate data structures
 349   delete resource_area();
 350   // since the handle marks are using the handle area, we have to deallocated the root
 351   // handle mark before deallocating the thread's handle area,
 352   assert(last_handle_mark() != NULL, "check we have an element");
 353   delete last_handle_mark();
 354   assert(last_handle_mark() == NULL, "check we have reached the end");
 355 
 356   // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
 357   // We NULL out the fields for good hygiene.
 358   ParkEvent::Release(_ParkEvent); _ParkEvent   = NULL;
 359   ParkEvent::Release(_SleepEvent); _SleepEvent  = NULL;
 360   ParkEvent::Release(_MutexEvent); _MutexEvent  = NULL;
 361   ParkEvent::Release(_MuxEvent); _MuxEvent    = NULL;
 362 
 363   delete handle_area();
 364   delete metadata_handles();
 365 
 366   // osthread() can be NULL, if creation of thread failed.
 367   if (osthread() != NULL) os::free_thread(osthread());
 368 
 369   delete _SR_lock;
 370 
 371   // clear Thread::current if thread is deleting itself.
 372   // Needed to ensure JNI correctly detects non-attached threads.
 373   if (this == Thread::current()) {
 374     clear_thread_current();
 375   }
 376 
 377   CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
 378 }
 379 
 380 // NOTE: dummy function for assertion purpose.
 381 void Thread::run() {
 382   ShouldNotReachHere();
 383 }
 384 
 385 #ifdef ASSERT
 386 // Private method to check for dangling thread pointer
 387 void check_for_dangling_thread_pointer(Thread *thread) {
 388   assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
 389          "possibility of dangling Thread pointer");
 390 }
 391 #endif
 392 
 393 ThreadPriority Thread::get_priority(const Thread* const thread) {
 394   ThreadPriority priority;
 395   // Can return an error!
 396   (void)os::get_priority(thread, priority);
 397   assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
 398   return priority;
 399 }
 400 
 401 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
 402   debug_only(check_for_dangling_thread_pointer(thread);)
 403   // Can return an error!
 404   (void)os::set_priority(thread, priority);
 405 }
 406 
 407 
 408 void Thread::start(Thread* thread) {
 409   // Start is different from resume in that its safety is guaranteed by context or
 410   // being called from a Java method synchronized on the Thread object.
 411   if (!DisableStartThread) {
 412     if (thread->is_Java_thread()) {
 413       // Initialize the thread state to RUNNABLE before starting this thread.
 414       // Can not set it after the thread started because we do not know the
 415       // exact thread state at that time. It could be in MONITOR_WAIT or
 416       // in SLEEPING or some other state.
 417       java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
 418                                           java_lang_Thread::RUNNABLE);
 419     }
 420     os::start_thread(thread);
 421   }
 422 }
 423 
 424 // Enqueue a VM_Operation to do the job for us - sometime later
 425 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
 426   VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
 427   VMThread::execute(vm_stop);
 428 }
 429 
 430 
 431 // Check if an external suspend request has completed (or has been
 432 // cancelled). Returns true if the thread is externally suspended and
 433 // false otherwise.
 434 //
 435 // The bits parameter returns information about the code path through
 436 // the routine. Useful for debugging:
 437 //
 438 // set in is_ext_suspend_completed():
 439 // 0x00000001 - routine was entered
 440 // 0x00000010 - routine return false at end
 441 // 0x00000100 - thread exited (return false)
 442 // 0x00000200 - suspend request cancelled (return false)
 443 // 0x00000400 - thread suspended (return true)
 444 // 0x00001000 - thread is in a suspend equivalent state (return true)
 445 // 0x00002000 - thread is native and walkable (return true)
 446 // 0x00004000 - thread is native_trans and walkable (needed retry)
 447 //
 448 // set in wait_for_ext_suspend_completion():
 449 // 0x00010000 - routine was entered
 450 // 0x00020000 - suspend request cancelled before loop (return false)
 451 // 0x00040000 - thread suspended before loop (return true)
 452 // 0x00080000 - suspend request cancelled in loop (return false)
 453 // 0x00100000 - thread suspended in loop (return true)
 454 // 0x00200000 - suspend not completed during retry loop (return false)
 455 
 456 // Helper class for tracing suspend wait debug bits.
 457 //
 458 // 0x00000100 indicates that the target thread exited before it could
 459 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
 460 // 0x00080000 each indicate a cancelled suspend request so they don't
 461 // count as wait failures either.
 462 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
 463 
 464 class TraceSuspendDebugBits : public StackObj {
 465  private:
 466   JavaThread * jt;
 467   bool         is_wait;
 468   bool         called_by_wait;  // meaningful when !is_wait
 469   uint32_t *   bits;
 470 
 471  public:
 472   TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
 473                         uint32_t *_bits) {
 474     jt             = _jt;
 475     is_wait        = _is_wait;
 476     called_by_wait = _called_by_wait;
 477     bits           = _bits;
 478   }
 479 
 480   ~TraceSuspendDebugBits() {
 481     if (!is_wait) {
 482 #if 1
 483       // By default, don't trace bits for is_ext_suspend_completed() calls.
 484       // That trace is very chatty.
 485       return;
 486 #else
 487       if (!called_by_wait) {
 488         // If tracing for is_ext_suspend_completed() is enabled, then only
 489         // trace calls to it from wait_for_ext_suspend_completion()
 490         return;
 491       }
 492 #endif
 493     }
 494 
 495     if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
 496       if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
 497         MutexLocker ml(Threads_lock);  // needed for get_thread_name()
 498         ResourceMark rm;
 499 
 500         tty->print_cr(
 501                       "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
 502                       jt->get_thread_name(), *bits);
 503 
 504         guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
 505       }
 506     }
 507   }
 508 };
 509 #undef DEBUG_FALSE_BITS
 510 
 511 
 512 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
 513                                           uint32_t *bits) {
 514   TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
 515 
 516   bool did_trans_retry = false;  // only do thread_in_native_trans retry once
 517   bool do_trans_retry;           // flag to force the retry
 518 
 519   *bits |= 0x00000001;
 520 
 521   do {
 522     do_trans_retry = false;
 523 
 524     if (is_exiting()) {
 525       // Thread is in the process of exiting. This is always checked
 526       // first to reduce the risk of dereferencing a freed JavaThread.
 527       *bits |= 0x00000100;
 528       return false;
 529     }
 530 
 531     if (!is_external_suspend()) {
 532       // Suspend request is cancelled. This is always checked before
 533       // is_ext_suspended() to reduce the risk of a rogue resume
 534       // confusing the thread that made the suspend request.
 535       *bits |= 0x00000200;
 536       return false;
 537     }
 538 
 539     if (is_ext_suspended()) {
 540       // thread is suspended
 541       *bits |= 0x00000400;
 542       return true;
 543     }
 544 
 545     // Now that we no longer do hard suspends of threads running
 546     // native code, the target thread can be changing thread state
 547     // while we are in this routine:
 548     //
 549     //   _thread_in_native -> _thread_in_native_trans -> _thread_blocked
 550     //
 551     // We save a copy of the thread state as observed at this moment
 552     // and make our decision about suspend completeness based on the
 553     // copy. This closes the race where the thread state is seen as
 554     // _thread_in_native_trans in the if-thread_blocked check, but is
 555     // seen as _thread_blocked in if-thread_in_native_trans check.
 556     JavaThreadState save_state = thread_state();
 557 
 558     if (save_state == _thread_blocked && is_suspend_equivalent()) {
 559       // If the thread's state is _thread_blocked and this blocking
 560       // condition is known to be equivalent to a suspend, then we can
 561       // consider the thread to be externally suspended. This means that
 562       // the code that sets _thread_blocked has been modified to do
 563       // self-suspension if the blocking condition releases. We also
 564       // used to check for CONDVAR_WAIT here, but that is now covered by
 565       // the _thread_blocked with self-suspension check.
 566       //
 567       // Return true since we wouldn't be here unless there was still an
 568       // external suspend request.
 569       *bits |= 0x00001000;
 570       return true;
 571     } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
 572       // Threads running native code will self-suspend on native==>VM/Java
 573       // transitions. If its stack is walkable (should always be the case
 574       // unless this function is called before the actual java_suspend()
 575       // call), then the wait is done.
 576       *bits |= 0x00002000;
 577       return true;
 578     } else if (!called_by_wait && !did_trans_retry &&
 579                save_state == _thread_in_native_trans &&
 580                frame_anchor()->walkable()) {
 581       // The thread is transitioning from thread_in_native to another
 582       // thread state. check_safepoint_and_suspend_for_native_trans()
 583       // will force the thread to self-suspend. If it hasn't gotten
 584       // there yet we may have caught the thread in-between the native
 585       // code check above and the self-suspend. Lucky us. If we were
 586       // called by wait_for_ext_suspend_completion(), then it
 587       // will be doing the retries so we don't have to.
 588       //
 589       // Since we use the saved thread state in the if-statement above,
 590       // there is a chance that the thread has already transitioned to
 591       // _thread_blocked by the time we get here. In that case, we will
 592       // make a single unnecessary pass through the logic below. This
 593       // doesn't hurt anything since we still do the trans retry.
 594 
 595       *bits |= 0x00004000;
 596 
 597       // Once the thread leaves thread_in_native_trans for another
 598       // thread state, we break out of this retry loop. We shouldn't
 599       // need this flag to prevent us from getting back here, but
 600       // sometimes paranoia is good.
 601       did_trans_retry = true;
 602 
 603       // We wait for the thread to transition to a more usable state.
 604       for (int i = 1; i <= SuspendRetryCount; i++) {
 605         // We used to do an "os::yield_all(i)" call here with the intention
 606         // that yielding would increase on each retry. However, the parameter
 607         // is ignored on Linux which means the yield didn't scale up. Waiting
 608         // on the SR_lock below provides a much more predictable scale up for
 609         // the delay. It also provides a simple/direct point to check for any
 610         // safepoint requests from the VMThread
 611 
 612         // temporarily drops SR_lock while doing wait with safepoint check
 613         // (if we're a JavaThread - the WatcherThread can also call this)
 614         // and increase delay with each retry
 615         SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 616 
 617         // check the actual thread state instead of what we saved above
 618         if (thread_state() != _thread_in_native_trans) {
 619           // the thread has transitioned to another thread state so
 620           // try all the checks (except this one) one more time.
 621           do_trans_retry = true;
 622           break;
 623         }
 624       } // end retry loop
 625 
 626 
 627     }
 628   } while (do_trans_retry);
 629 
 630   *bits |= 0x00000010;
 631   return false;
 632 }
 633 
 634 // Wait for an external suspend request to complete (or be cancelled).
 635 // Returns true if the thread is externally suspended and false otherwise.
 636 //
 637 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
 638                                                  uint32_t *bits) {
 639   TraceSuspendDebugBits tsdb(this, true /* is_wait */,
 640                              false /* !called_by_wait */, bits);
 641 
 642   // local flag copies to minimize SR_lock hold time
 643   bool is_suspended;
 644   bool pending;
 645   uint32_t reset_bits;
 646 
 647   // set a marker so is_ext_suspend_completed() knows we are the caller
 648   *bits |= 0x00010000;
 649 
 650   // We use reset_bits to reinitialize the bits value at the top of
 651   // each retry loop. This allows the caller to make use of any
 652   // unused bits for their own marking purposes.
 653   reset_bits = *bits;
 654 
 655   {
 656     MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
 657     is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 658                                             delay, bits);
 659     pending = is_external_suspend();
 660   }
 661   // must release SR_lock to allow suspension to complete
 662 
 663   if (!pending) {
 664     // A cancelled suspend request is the only false return from
 665     // is_ext_suspend_completed() that keeps us from entering the
 666     // retry loop.
 667     *bits |= 0x00020000;
 668     return false;
 669   }
 670 
 671   if (is_suspended) {
 672     *bits |= 0x00040000;
 673     return true;
 674   }
 675 
 676   for (int i = 1; i <= retries; i++) {
 677     *bits = reset_bits;  // reinit to only track last retry
 678 
 679     // We used to do an "os::yield_all(i)" call here with the intention
 680     // that yielding would increase on each retry. However, the parameter
 681     // is ignored on Linux which means the yield didn't scale up. Waiting
 682     // on the SR_lock below provides a much more predictable scale up for
 683     // the delay. It also provides a simple/direct point to check for any
 684     // safepoint requests from the VMThread
 685 
 686     {
 687       MutexLocker ml(SR_lock());
 688       // wait with safepoint check (if we're a JavaThread - the WatcherThread
 689       // can also call this)  and increase delay with each retry
 690       SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 691 
 692       is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 693                                               delay, bits);
 694 
 695       // It is possible for the external suspend request to be cancelled
 696       // (by a resume) before the actual suspend operation is completed.
 697       // Refresh our local copy to see if we still need to wait.
 698       pending = is_external_suspend();
 699     }
 700 
 701     if (!pending) {
 702       // A cancelled suspend request is the only false return from
 703       // is_ext_suspend_completed() that keeps us from staying in the
 704       // retry loop.
 705       *bits |= 0x00080000;
 706       return false;
 707     }
 708 
 709     if (is_suspended) {
 710       *bits |= 0x00100000;
 711       return true;
 712     }
 713   } // end retry loop
 714 
 715   // thread did not suspend after all our retries
 716   *bits |= 0x00200000;
 717   return false;
 718 }
 719 
 720 #ifndef PRODUCT
 721 void JavaThread::record_jump(address target, address instr, const char* file,
 722                              int line) {
 723 
 724   // This should not need to be atomic as the only way for simultaneous
 725   // updates is via interrupts. Even then this should be rare or non-existent
 726   // and we don't care that much anyway.
 727 
 728   int index = _jmp_ring_index;
 729   _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
 730   _jmp_ring[index]._target = (intptr_t) target;
 731   _jmp_ring[index]._instruction = (intptr_t) instr;
 732   _jmp_ring[index]._file = file;
 733   _jmp_ring[index]._line = line;
 734 }
 735 #endif // PRODUCT
 736 
 737 // Called by flat profiler
 738 // Callers have already called wait_for_ext_suspend_completion
 739 // The assertion for that is currently too complex to put here:
 740 bool JavaThread::profile_last_Java_frame(frame* _fr) {
 741   bool gotframe = false;
 742   // self suspension saves needed state.
 743   if (has_last_Java_frame() && _anchor.walkable()) {
 744     *_fr = pd_last_frame();
 745     gotframe = true;
 746   }
 747   return gotframe;
 748 }
 749 
 750 void Thread::interrupt(Thread* thread) {
 751   debug_only(check_for_dangling_thread_pointer(thread);)
 752   os::interrupt(thread);
 753 }
 754 
 755 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
 756   debug_only(check_for_dangling_thread_pointer(thread);)
 757   // Note:  If clear_interrupted==false, this simply fetches and
 758   // returns the value of the field osthread()->interrupted().
 759   return os::is_interrupted(thread, clear_interrupted);
 760 }
 761 
 762 
 763 // GC Support
 764 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
 765   jint thread_parity = _oops_do_parity;
 766   if (thread_parity != strong_roots_parity) {
 767     jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
 768     if (res == thread_parity) {
 769       return true;
 770     } else {
 771       guarantee(res == strong_roots_parity, "Or else what?");
 772       return false;
 773     }
 774   }
 775   return false;
 776 }
 777 
 778 void Thread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
 779   active_handles()->oops_do(f);
 780   // Do oop for ThreadShadow
 781   f->do_oop((oop*)&_pending_exception);
 782   handle_area()->oops_do(f);
 783 }
 784 
 785 void Thread::nmethods_do(CodeBlobClosure* cf) {
 786   // no nmethods in a generic thread...
 787 }
 788 
 789 void Thread::metadata_handles_do(void f(Metadata*)) {
 790   // Only walk the Handles in Thread.
 791   if (metadata_handles() != NULL) {
 792     for (int i = 0; i< metadata_handles()->length(); i++) {
 793       f(metadata_handles()->at(i));
 794     }
 795   }
 796 }
 797 
 798 void Thread::print_on(outputStream* st) const {
 799   // get_priority assumes osthread initialized
 800   if (osthread() != NULL) {
 801     int os_prio;
 802     if (os::get_native_priority(this, &os_prio) == OS_OK) {
 803       st->print("os_prio=%d ", os_prio);
 804     }
 805     st->print("tid=" INTPTR_FORMAT " ", p2i(this));
 806     ext().print_on(st);
 807     osthread()->print_on(st);
 808   }
 809   debug_only(if (WizardMode) print_owned_locks_on(st);)
 810 }
 811 
 812 // Thread::print_on_error() is called by fatal error handler. Don't use
 813 // any lock or allocate memory.
 814 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
 815   if (is_VM_thread())                 st->print("VMThread");
 816   else if (is_Compiler_thread())      st->print("CompilerThread");
 817   else if (is_Java_thread())          st->print("JavaThread");
 818   else if (is_GC_task_thread())       st->print("GCTaskThread");
 819   else if (is_Watcher_thread())       st->print("WatcherThread");
 820   else if (is_ConcurrentGC_thread())  st->print("ConcurrentGCThread");
 821   else                                st->print("Thread");
 822 
 823   st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
 824             p2i(_stack_base - _stack_size), p2i(_stack_base));
 825 
 826   if (osthread()) {
 827     st->print(" [id=%d]", osthread()->thread_id());
 828   }
 829 }
 830 
 831 #ifdef ASSERT
 832 void Thread::print_owned_locks_on(outputStream* st) const {
 833   Monitor *cur = _owned_locks;
 834   if (cur == NULL) {
 835     st->print(" (no locks) ");
 836   } else {
 837     st->print_cr(" Locks owned:");
 838     while (cur) {
 839       cur->print_on(st);
 840       cur = cur->next();
 841     }
 842   }
 843 }
 844 
 845 static int ref_use_count  = 0;
 846 
 847 bool Thread::owns_locks_but_compiled_lock() const {
 848   for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 849     if (cur != Compile_lock) return true;
 850   }
 851   return false;
 852 }
 853 
 854 
 855 #endif
 856 
 857 #ifndef PRODUCT
 858 
 859 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
 860 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
 861 // no threads which allow_vm_block's are held
 862 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
 863   // Check if current thread is allowed to block at a safepoint
 864   if (!(_allow_safepoint_count == 0)) {
 865     fatal("Possible safepoint reached by thread that does not allow it");
 866   }
 867   if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
 868     fatal("LEAF method calling lock?");
 869   }
 870 
 871 #ifdef ASSERT
 872   if (potential_vm_operation && is_Java_thread()
 873       && !Universe::is_bootstrapping()) {
 874     // Make sure we do not hold any locks that the VM thread also uses.
 875     // This could potentially lead to deadlocks
 876     for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 877       // Threads_lock is special, since the safepoint synchronization will not start before this is
 878       // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
 879       // since it is used to transfer control between JavaThreads and the VMThread
 880       // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
 881       if ((cur->allow_vm_block() &&
 882            cur != Threads_lock &&
 883            cur != Compile_lock &&               // Temporary: should not be necessary when we get separate compilation
 884            cur != VMOperationRequest_lock &&
 885            cur != VMOperationQueue_lock) ||
 886            cur->rank() == Mutex::special) {
 887         fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
 888       }
 889     }
 890   }
 891 
 892   if (GCALotAtAllSafepoints) {
 893     // We could enter a safepoint here and thus have a gc
 894     InterfaceSupport::check_gc_alot();
 895   }
 896 #endif
 897 }
 898 #endif
 899 
 900 bool Thread::is_in_stack(address adr) const {
 901   assert(Thread::current() == this, "is_in_stack can only be called from current thread");
 902   address end = os::current_stack_pointer();
 903   // Allow non Java threads to call this without stack_base
 904   if (_stack_base == NULL) return true;
 905   if (stack_base() >= adr && adr >= end) return true;
 906 
 907   return false;
 908 }
 909 
 910 
 911 bool Thread::is_in_usable_stack(address adr) const {
 912   size_t stack_guard_size = os::uses_stack_guard_pages() ? (StackReservedPages + StackYellowPages + StackRedPages) * os::vm_page_size() : 0;
 913   size_t usable_stack_size = _stack_size - stack_guard_size;
 914 
 915   return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
 916 }
 917 
 918 
 919 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
 920 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
 921 // used for compilation in the future. If that change is made, the need for these methods
 922 // should be revisited, and they should be removed if possible.
 923 
 924 bool Thread::is_lock_owned(address adr) const {
 925   return on_local_stack(adr);
 926 }
 927 
 928 bool Thread::set_as_starting_thread() {
 929   // NOTE: this must be called inside the main thread.
 930   return os::create_main_thread((JavaThread*)this);
 931 }
 932 
 933 static void initialize_class(Symbol* class_name, TRAPS) {
 934   Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
 935   InstanceKlass::cast(klass)->initialize(CHECK);
 936 }
 937 
 938 
 939 // Creates the initial ThreadGroup
 940 static Handle create_initial_thread_group(TRAPS) {
 941   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
 942   instanceKlassHandle klass (THREAD, k);
 943 
 944   Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
 945   {
 946     JavaValue result(T_VOID);
 947     JavaCalls::call_special(&result,
 948                             system_instance,
 949                             klass,
 950                             vmSymbols::object_initializer_name(),
 951                             vmSymbols::void_method_signature(),
 952                             CHECK_NH);
 953   }
 954   Universe::set_system_thread_group(system_instance());
 955 
 956   Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
 957   {
 958     JavaValue result(T_VOID);
 959     Handle string = java_lang_String::create_from_str("main", CHECK_NH);
 960     JavaCalls::call_special(&result,
 961                             main_instance,
 962                             klass,
 963                             vmSymbols::object_initializer_name(),
 964                             vmSymbols::threadgroup_string_void_signature(),
 965                             system_instance,
 966                             string,
 967                             CHECK_NH);
 968   }
 969   return main_instance;
 970 }
 971 
 972 // Creates the initial Thread
 973 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
 974                                  TRAPS) {
 975   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
 976   instanceKlassHandle klass (THREAD, k);
 977   instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
 978 
 979   java_lang_Thread::set_thread(thread_oop(), thread);
 980   java_lang_Thread::set_priority(thread_oop(), NormPriority);
 981   thread->set_threadObj(thread_oop());
 982 
 983   Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
 984 
 985   JavaValue result(T_VOID);
 986   JavaCalls::call_special(&result, thread_oop,
 987                           klass,
 988                           vmSymbols::object_initializer_name(),
 989                           vmSymbols::threadgroup_string_void_signature(),
 990                           thread_group,
 991                           string,
 992                           CHECK_NULL);
 993   return thread_oop();
 994 }
 995 
 996 static void call_initializeSystemClass(TRAPS) {
 997   Klass* k =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
 998   instanceKlassHandle klass (THREAD, k);
 999 
1000   JavaValue result(T_VOID);
1001   JavaCalls::call_static(&result, klass, vmSymbols::initializeSystemClass_name(),
1002                          vmSymbols::void_method_signature(), CHECK);
1003 }
1004 
1005 char java_runtime_name[128] = "";
1006 char java_runtime_version[128] = "";
1007 
1008 // extract the JRE name from sun.misc.Version.java_runtime_name
1009 static const char* get_java_runtime_name(TRAPS) {
1010   Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(),
1011                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1012   fieldDescriptor fd;
1013   bool found = k != NULL &&
1014                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1015                                                         vmSymbols::string_signature(), &fd);
1016   if (found) {
1017     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1018     if (name_oop == NULL) {
1019       return NULL;
1020     }
1021     const char* name = java_lang_String::as_utf8_string(name_oop,
1022                                                         java_runtime_name,
1023                                                         sizeof(java_runtime_name));
1024     return name;
1025   } else {
1026     return NULL;
1027   }
1028 }
1029 
1030 // extract the JRE version from sun.misc.Version.java_runtime_version
1031 static const char* get_java_runtime_version(TRAPS) {
1032   Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(),
1033                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1034   fieldDescriptor fd;
1035   bool found = k != NULL &&
1036                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1037                                                         vmSymbols::string_signature(), &fd);
1038   if (found) {
1039     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1040     if (name_oop == NULL) {
1041       return NULL;
1042     }
1043     const char* name = java_lang_String::as_utf8_string(name_oop,
1044                                                         java_runtime_version,
1045                                                         sizeof(java_runtime_version));
1046     return name;
1047   } else {
1048     return NULL;
1049   }
1050 }
1051 
1052 // General purpose hook into Java code, run once when the VM is initialized.
1053 // The Java library method itself may be changed independently from the VM.
1054 static void call_postVMInitHook(TRAPS) {
1055   Klass* k = SystemDictionary::resolve_or_null(vmSymbols::sun_misc_PostVMInitHook(), THREAD);
1056   instanceKlassHandle klass (THREAD, k);
1057   if (klass.not_null()) {
1058     JavaValue result(T_VOID);
1059     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1060                            vmSymbols::void_method_signature(),
1061                            CHECK);
1062   }
1063 }
1064 
1065 static void reset_vm_info_property(TRAPS) {
1066   // the vm info string
1067   ResourceMark rm(THREAD);
1068   const char *vm_info = VM_Version::vm_info_string();
1069 
1070   // java.lang.System class
1071   Klass* k =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1072   instanceKlassHandle klass (THREAD, k);
1073 
1074   // setProperty arguments
1075   Handle key_str    = java_lang_String::create_from_str("java.vm.info", CHECK);
1076   Handle value_str  = java_lang_String::create_from_str(vm_info, CHECK);
1077 
1078   // return value
1079   JavaValue r(T_OBJECT);
1080 
1081   // public static String setProperty(String key, String value);
1082   JavaCalls::call_static(&r,
1083                          klass,
1084                          vmSymbols::setProperty_name(),
1085                          vmSymbols::string_string_string_signature(),
1086                          key_str,
1087                          value_str,
1088                          CHECK);
1089 }
1090 
1091 
1092 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1093                                     bool daemon, TRAPS) {
1094   assert(thread_group.not_null(), "thread group should be specified");
1095   assert(threadObj() == NULL, "should only create Java thread object once");
1096 
1097   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1098   instanceKlassHandle klass (THREAD, k);
1099   instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1100 
1101   java_lang_Thread::set_thread(thread_oop(), this);
1102   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1103   set_threadObj(thread_oop());
1104 
1105   JavaValue result(T_VOID);
1106   if (thread_name != NULL) {
1107     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1108     // Thread gets assigned specified name and null target
1109     JavaCalls::call_special(&result,
1110                             thread_oop,
1111                             klass,
1112                             vmSymbols::object_initializer_name(),
1113                             vmSymbols::threadgroup_string_void_signature(),
1114                             thread_group, // Argument 1
1115                             name,         // Argument 2
1116                             THREAD);
1117   } else {
1118     // Thread gets assigned name "Thread-nnn" and null target
1119     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1120     JavaCalls::call_special(&result,
1121                             thread_oop,
1122                             klass,
1123                             vmSymbols::object_initializer_name(),
1124                             vmSymbols::threadgroup_runnable_void_signature(),
1125                             thread_group, // Argument 1
1126                             Handle(),     // Argument 2
1127                             THREAD);
1128   }
1129 
1130 
1131   if (daemon) {
1132     java_lang_Thread::set_daemon(thread_oop());
1133   }
1134 
1135   if (HAS_PENDING_EXCEPTION) {
1136     return;
1137   }
1138 
1139   KlassHandle group(THREAD, SystemDictionary::ThreadGroup_klass());
1140   Handle threadObj(THREAD, this->threadObj());
1141 
1142   JavaCalls::call_special(&result,
1143                           thread_group,
1144                           group,
1145                           vmSymbols::add_method_name(),
1146                           vmSymbols::thread_void_signature(),
1147                           threadObj,          // Arg 1
1148                           THREAD);
1149 }
1150 
1151 // NamedThread --  non-JavaThread subclasses with multiple
1152 // uniquely named instances should derive from this.
1153 NamedThread::NamedThread() : Thread() {
1154   _name = NULL;
1155   _processed_thread = NULL;
1156   _gc_id = GCId::undefined();
1157 }
1158 
1159 NamedThread::~NamedThread() {
1160   if (_name != NULL) {
1161     FREE_C_HEAP_ARRAY(char, _name);
1162     _name = NULL;
1163   }
1164 }
1165 
1166 void NamedThread::set_name(const char* format, ...) {
1167   guarantee(_name == NULL, "Only get to set name once.");
1168   _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1169   guarantee(_name != NULL, "alloc failure");
1170   va_list ap;
1171   va_start(ap, format);
1172   jio_vsnprintf(_name, max_name_len, format, ap);
1173   va_end(ap);
1174 }
1175 
1176 void NamedThread::initialize_named_thread() {
1177   set_native_thread_name(name());
1178 }
1179 
1180 void NamedThread::print_on(outputStream* st) const {
1181   st->print("\"%s\" ", name());
1182   Thread::print_on(st);
1183   st->cr();
1184 }
1185 
1186 
1187 // ======= WatcherThread ========
1188 
1189 // The watcher thread exists to simulate timer interrupts.  It should
1190 // be replaced by an abstraction over whatever native support for
1191 // timer interrupts exists on the platform.
1192 
1193 WatcherThread* WatcherThread::_watcher_thread   = NULL;
1194 bool WatcherThread::_startable = false;
1195 volatile bool  WatcherThread::_should_terminate = false;
1196 
1197 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) {
1198   assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1199   if (os::create_thread(this, os::watcher_thread)) {
1200     _watcher_thread = this;
1201 
1202     // Set the watcher thread to the highest OS priority which should not be
1203     // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1204     // is created. The only normal thread using this priority is the reference
1205     // handler thread, which runs for very short intervals only.
1206     // If the VMThread's priority is not lower than the WatcherThread profiling
1207     // will be inaccurate.
1208     os::set_priority(this, MaxPriority);
1209     if (!DisableStartThread) {
1210       os::start_thread(this);
1211     }
1212   }
1213 }
1214 
1215 int WatcherThread::sleep() const {
1216   // The WatcherThread does not participate in the safepoint protocol
1217   // for the PeriodicTask_lock because it is not a JavaThread.
1218   MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1219 
1220   if (_should_terminate) {
1221     // check for termination before we do any housekeeping or wait
1222     return 0;  // we did not sleep.
1223   }
1224 
1225   // remaining will be zero if there are no tasks,
1226   // causing the WatcherThread to sleep until a task is
1227   // enrolled
1228   int remaining = PeriodicTask::time_to_wait();
1229   int time_slept = 0;
1230 
1231   // we expect this to timeout - we only ever get unparked when
1232   // we should terminate or when a new task has been enrolled
1233   OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1234 
1235   jlong time_before_loop = os::javaTimeNanos();
1236 
1237   while (true) {
1238     bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1239                                             remaining);
1240     jlong now = os::javaTimeNanos();
1241 
1242     if (remaining == 0) {
1243       // if we didn't have any tasks we could have waited for a long time
1244       // consider the time_slept zero and reset time_before_loop
1245       time_slept = 0;
1246       time_before_loop = now;
1247     } else {
1248       // need to recalculate since we might have new tasks in _tasks
1249       time_slept = (int) ((now - time_before_loop) / 1000000);
1250     }
1251 
1252     // Change to task list or spurious wakeup of some kind
1253     if (timedout || _should_terminate) {
1254       break;
1255     }
1256 
1257     remaining = PeriodicTask::time_to_wait();
1258     if (remaining == 0) {
1259       // Last task was just disenrolled so loop around and wait until
1260       // another task gets enrolled
1261       continue;
1262     }
1263 
1264     remaining -= time_slept;
1265     if (remaining <= 0) {
1266       break;
1267     }
1268   }
1269 
1270   return time_slept;
1271 }
1272 
1273 void WatcherThread::run() {
1274   assert(this == watcher_thread(), "just checking");
1275 
1276   this->record_stack_base_and_size();
1277   this->set_native_thread_name(this->name());
1278   this->set_active_handles(JNIHandleBlock::allocate_block());
1279   while (true) {
1280     assert(watcher_thread() == Thread::current(), "thread consistency check");
1281     assert(watcher_thread() == this, "thread consistency check");
1282 
1283     // Calculate how long it'll be until the next PeriodicTask work
1284     // should be done, and sleep that amount of time.
1285     int time_waited = sleep();
1286 
1287     if (is_error_reported()) {
1288       // A fatal error has happened, the error handler(VMError::report_and_die)
1289       // should abort JVM after creating an error log file. However in some
1290       // rare cases, the error handler itself might deadlock. Here we try to
1291       // kill JVM if the fatal error handler fails to abort in 2 minutes.
1292       //
1293       // This code is in WatcherThread because WatcherThread wakes up
1294       // periodically so the fatal error handler doesn't need to do anything;
1295       // also because the WatcherThread is less likely to crash than other
1296       // threads.
1297 
1298       for (;;) {
1299         if (!ShowMessageBoxOnError
1300             && (OnError == NULL || OnError[0] == '\0')
1301             && Arguments::abort_hook() == NULL) {
1302           os::sleep(this, (jlong)ErrorLogTimeout * 1000, false); // in seconds
1303           fdStream err(defaultStream::output_fd());
1304           err.print_raw_cr("# [ timer expired, abort... ]");
1305           // skip atexit/vm_exit/vm_abort hooks
1306           os::die();
1307         }
1308 
1309         // Wake up 5 seconds later, the fatal handler may reset OnError or
1310         // ShowMessageBoxOnError when it is ready to abort.
1311         os::sleep(this, 5 * 1000, false);
1312       }
1313     }
1314 
1315     if (_should_terminate) {
1316       // check for termination before posting the next tick
1317       break;
1318     }
1319 
1320     PeriodicTask::real_time_tick(time_waited);
1321   }
1322 
1323   // Signal that it is terminated
1324   {
1325     MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1326     _watcher_thread = NULL;
1327     Terminator_lock->notify();
1328   }
1329 }
1330 
1331 void WatcherThread::start() {
1332   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1333 
1334   if (watcher_thread() == NULL && _startable) {
1335     _should_terminate = false;
1336     // Create the single instance of WatcherThread
1337     new WatcherThread();
1338   }
1339 }
1340 
1341 void WatcherThread::make_startable() {
1342   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1343   _startable = true;
1344 }
1345 
1346 void WatcherThread::stop() {
1347   {
1348     // Follow normal safepoint aware lock enter protocol since the
1349     // WatcherThread is stopped by another JavaThread.
1350     MutexLocker ml(PeriodicTask_lock);
1351     _should_terminate = true;
1352 
1353     WatcherThread* watcher = watcher_thread();
1354     if (watcher != NULL) {
1355       // unpark the WatcherThread so it can see that it should terminate
1356       watcher->unpark();
1357     }
1358   }
1359 
1360   MutexLocker mu(Terminator_lock);
1361 
1362   while (watcher_thread() != NULL) {
1363     // This wait should make safepoint checks, wait without a timeout,
1364     // and wait as a suspend-equivalent condition.
1365     //
1366     // Note: If the FlatProfiler is running, then this thread is waiting
1367     // for the WatcherThread to terminate and the WatcherThread, via the
1368     // FlatProfiler task, is waiting for the external suspend request on
1369     // this thread to complete. wait_for_ext_suspend_completion() will
1370     // eventually timeout, but that takes time. Making this wait a
1371     // suspend-equivalent condition solves that timeout problem.
1372     //
1373     Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1374                           Mutex::_as_suspend_equivalent_flag);
1375   }
1376 }
1377 
1378 void WatcherThread::unpark() {
1379   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1380   PeriodicTask_lock->notify();
1381 }
1382 
1383 void WatcherThread::print_on(outputStream* st) const {
1384   st->print("\"%s\" ", name());
1385   Thread::print_on(st);
1386   st->cr();
1387 }
1388 
1389 // ======= JavaThread ========
1390 
1391 #if INCLUDE_JVMCI
1392 
1393 jlong* JavaThread::_jvmci_old_thread_counters;
1394 
1395 bool jvmci_counters_include(JavaThread* thread) {
1396   oop threadObj = thread->threadObj();
1397   return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1398 }
1399 
1400 void JavaThread::collect_counters(typeArrayOop array) {
1401   if (JVMCICounterSize > 0) {
1402     MutexLocker tl(Threads_lock);
1403     for (int i = 0; i < array->length(); i++) {
1404       array->long_at_put(i, _jvmci_old_thread_counters[i]);
1405     }
1406     for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) {
1407       if (jvmci_counters_include(tp)) {
1408         for (int i = 0; i < array->length(); i++) {
1409           array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1410         }
1411       }
1412     }
1413   }
1414 }
1415 
1416 #endif // INCLUDE_JVMCI
1417 
1418 // A JavaThread is a normal Java thread
1419 
1420 void JavaThread::initialize() {
1421   // Initialize fields
1422 
1423   // Set the claimed par_id to UINT_MAX (ie not claiming any par_ids)
1424   set_claimed_par_id(UINT_MAX);
1425 
1426   set_saved_exception_pc(NULL);
1427   set_threadObj(NULL);
1428   _anchor.clear();
1429   set_entry_point(NULL);
1430   set_jni_functions(jni_functions());
1431   set_callee_target(NULL);
1432   set_vm_result(NULL);
1433   set_vm_result_2(NULL);
1434   set_vframe_array_head(NULL);
1435   set_vframe_array_last(NULL);
1436   set_deferred_locals(NULL);
1437   set_deopt_mark(NULL);
1438   set_deopt_nmethod(NULL);
1439   clear_must_deopt_id();
1440   set_monitor_chunks(NULL);
1441   set_next(NULL);
1442   set_thread_state(_thread_new);
1443   _terminated = _not_terminated;
1444   _privileged_stack_top = NULL;
1445   _array_for_gc = NULL;
1446   _suspend_equivalent = false;
1447   _in_deopt_handler = 0;
1448   _doing_unsafe_access = false;
1449   _stack_guard_state = stack_guard_unused;
1450 #if INCLUDE_JVMCI
1451   _pending_monitorenter = false;
1452   _pending_deoptimization = -1;
1453   _pending_failed_speculation = NULL;
1454   _pending_transfer_to_interpreter = false;
1455   _jvmci._alternate_call_target = NULL;
1456   assert(_jvmci._implicit_exception_pc == NULL, "must be");
1457   if (JVMCICounterSize > 0) {
1458     _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1459     memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1460   } else {
1461     _jvmci_counters = NULL;
1462   }
1463 #endif // INCLUDE_JVMCI
1464   _reserved_stack_activation = NULL;  // stack base not known yet
1465   (void)const_cast<oop&>(_exception_oop = oop(NULL));
1466   _exception_pc  = 0;
1467   _exception_handler_pc = 0;
1468   _is_method_handle_return = 0;
1469   _jvmti_thread_state= NULL;
1470   _should_post_on_exceptions_flag = JNI_FALSE;
1471   _jvmti_get_loaded_classes_closure = NULL;
1472   _interp_only_mode    = 0;
1473   _special_runtime_exit_condition = _no_async_condition;
1474   _pending_async_exception = NULL;
1475   _thread_stat = NULL;
1476   _thread_stat = new ThreadStatistics();
1477   _blocked_on_compilation = false;
1478   _jni_active_critical = 0;
1479   _pending_jni_exception_check_fn = NULL;
1480   _do_not_unlock_if_synchronized = false;
1481   _cached_monitor_info = NULL;
1482   _parker = Parker::Allocate(this);
1483 
1484 #ifndef PRODUCT
1485   _jmp_ring_index = 0;
1486   for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1487     record_jump(NULL, NULL, NULL, 0);
1488   }
1489 #endif // PRODUCT
1490 
1491   set_thread_profiler(NULL);
1492   if (FlatProfiler::is_active()) {
1493     // This is where we would decide to either give each thread it's own profiler
1494     // or use one global one from FlatProfiler,
1495     // or up to some count of the number of profiled threads, etc.
1496     ThreadProfiler* pp = new ThreadProfiler();
1497     pp->engage();
1498     set_thread_profiler(pp);
1499   }
1500 
1501   // Setup safepoint state info for this thread
1502   ThreadSafepointState::create(this);
1503 
1504   debug_only(_java_call_counter = 0);
1505 
1506   // JVMTI PopFrame support
1507   _popframe_condition = popframe_inactive;
1508   _popframe_preserved_args = NULL;
1509   _popframe_preserved_args_size = 0;
1510   _frames_to_pop_failed_realloc = 0;
1511 
1512   pd_initialize();
1513 }
1514 
1515 #if INCLUDE_ALL_GCS
1516 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1517 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1518 #endif // INCLUDE_ALL_GCS
1519 
1520 JavaThread::JavaThread(bool is_attaching_via_jni) :
1521                        Thread()
1522 #if INCLUDE_ALL_GCS
1523                        , _satb_mark_queue(&_satb_mark_queue_set),
1524                        _dirty_card_queue(&_dirty_card_queue_set)
1525 #endif // INCLUDE_ALL_GCS
1526 {
1527   initialize();
1528   if (is_attaching_via_jni) {
1529     _jni_attach_state = _attaching_via_jni;
1530   } else {
1531     _jni_attach_state = _not_attaching_via_jni;
1532   }
1533   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1534 }
1535 
1536 bool JavaThread::reguard_stack(address cur_sp) {
1537   if (_stack_guard_state != stack_guard_yellow_disabled
1538       && _stack_guard_state != stack_guard_reserved_disabled) {
1539     return true; // Stack already guarded or guard pages not needed.
1540   }
1541 
1542   if (register_stack_overflow()) {
1543     // For those architectures which have separate register and
1544     // memory stacks, we must check the register stack to see if
1545     // it has overflowed.
1546     return false;
1547   }
1548 
1549   // Java code never executes within the yellow zone: the latter is only
1550   // there to provoke an exception during stack banging.  If java code
1551   // is executing there, either StackShadowPages should be larger, or
1552   // some exception code in c1, c2 or the interpreter isn't unwinding
1553   // when it should.
1554   guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages");
1555   if (_stack_guard_state == stack_guard_yellow_disabled) {
1556     enable_stack_yellow_zone();
1557     if (reserved_stack_activation() != stack_base()) {
1558       set_reserved_stack_activation(stack_base());
1559     }
1560   } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1561     set_reserved_stack_activation(stack_base());
1562     enable_stack_reserved_zone();
1563   }
1564   return true;
1565 }
1566 
1567 bool JavaThread::reguard_stack(void) {
1568   return reguard_stack(os::current_stack_pointer());
1569 }
1570 
1571 
1572 void JavaThread::block_if_vm_exited() {
1573   if (_terminated == _vm_exited) {
1574     // _vm_exited is set at safepoint, and Threads_lock is never released
1575     // we will block here forever
1576     Threads_lock->lock_without_safepoint_check();
1577     ShouldNotReachHere();
1578   }
1579 }
1580 
1581 
1582 // Remove this ifdef when C1 is ported to the compiler interface.
1583 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1584 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1585 
1586 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1587                        Thread()
1588 #if INCLUDE_ALL_GCS
1589                        , _satb_mark_queue(&_satb_mark_queue_set),
1590                        _dirty_card_queue(&_dirty_card_queue_set)
1591 #endif // INCLUDE_ALL_GCS
1592 {
1593   initialize();
1594   _jni_attach_state = _not_attaching_via_jni;
1595   set_entry_point(entry_point);
1596   // Create the native thread itself.
1597   // %note runtime_23
1598   os::ThreadType thr_type = os::java_thread;
1599   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1600                                                      os::java_thread;
1601   os::create_thread(this, thr_type, stack_sz);
1602   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1603   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1604   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1605   // the exception consists of creating the exception object & initializing it, initialization
1606   // will leave the VM via a JavaCall and then all locks must be unlocked).
1607   //
1608   // The thread is still suspended when we reach here. Thread must be explicit started
1609   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1610   // by calling Threads:add. The reason why this is not done here, is because the thread
1611   // object must be fully initialized (take a look at JVM_Start)
1612 }
1613 
1614 JavaThread::~JavaThread() {
1615 
1616   // JSR166 -- return the parker to the free list
1617   Parker::Release(_parker);
1618   _parker = NULL;
1619 
1620   // Free any remaining  previous UnrollBlock
1621   vframeArray* old_array = vframe_array_last();
1622 
1623   if (old_array != NULL) {
1624     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1625     old_array->set_unroll_block(NULL);
1626     delete old_info;
1627     delete old_array;
1628   }
1629 
1630   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1631   if (deferred != NULL) {
1632     // This can only happen if thread is destroyed before deoptimization occurs.
1633     assert(deferred->length() != 0, "empty array!");
1634     do {
1635       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1636       deferred->remove_at(0);
1637       // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1638       delete dlv;
1639     } while (deferred->length() != 0);
1640     delete deferred;
1641   }
1642 
1643   // All Java related clean up happens in exit
1644   ThreadSafepointState::destroy(this);
1645   if (_thread_profiler != NULL) delete _thread_profiler;
1646   if (_thread_stat != NULL) delete _thread_stat;
1647 
1648 #if INCLUDE_JVMCI
1649   if (JVMCICounterSize > 0) {
1650     if (jvmci_counters_include(this)) {
1651       for (int i = 0; i < JVMCICounterSize; i++) {
1652         _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1653       }
1654     }
1655     FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1656   }
1657 #endif // INCLUDE_JVMCI
1658 }
1659 
1660 
1661 // The first routine called by a new Java thread
1662 void JavaThread::run() {
1663   // initialize thread-local alloc buffer related fields
1664   this->initialize_tlab();
1665 
1666   // used to test validity of stack trace backs
1667   this->record_base_of_stack_pointer();
1668 
1669   // Record real stack base and size.
1670   this->record_stack_base_and_size();
1671 
1672   this->create_stack_guard_pages();
1673 
1674   this->cache_global_variables();
1675 
1676   // Thread is now sufficient initialized to be handled by the safepoint code as being
1677   // in the VM. Change thread state from _thread_new to _thread_in_vm
1678   ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1679 
1680   assert(JavaThread::current() == this, "sanity check");
1681   assert(!Thread::current()->owns_locks(), "sanity check");
1682 
1683   DTRACE_THREAD_PROBE(start, this);
1684 
1685   // This operation might block. We call that after all safepoint checks for a new thread has
1686   // been completed.
1687   this->set_active_handles(JNIHandleBlock::allocate_block());
1688 
1689   if (JvmtiExport::should_post_thread_life()) {
1690     JvmtiExport::post_thread_start(this);
1691   }
1692 
1693   EventThreadStart event;
1694   if (event.should_commit()) {
1695     event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj()));
1696     event.commit();
1697   }
1698 
1699   // We call another function to do the rest so we are sure that the stack addresses used
1700   // from there will be lower than the stack base just computed
1701   thread_main_inner();
1702 
1703   // Note, thread is no longer valid at this point!
1704 }
1705 
1706 
1707 void JavaThread::thread_main_inner() {
1708   assert(JavaThread::current() == this, "sanity check");
1709   assert(this->threadObj() != NULL, "just checking");
1710 
1711   // Execute thread entry point unless this thread has a pending exception
1712   // or has been stopped before starting.
1713   // Note: Due to JVM_StopThread we can have pending exceptions already!
1714   if (!this->has_pending_exception() &&
1715       !java_lang_Thread::is_stillborn(this->threadObj())) {
1716     {
1717       ResourceMark rm(this);
1718       this->set_native_thread_name(this->get_thread_name());
1719     }
1720     HandleMark hm(this);
1721     this->entry_point()(this, this);
1722   }
1723 
1724   DTRACE_THREAD_PROBE(stop, this);
1725 
1726   this->exit(false);
1727   delete this;
1728 }
1729 
1730 
1731 static void ensure_join(JavaThread* thread) {
1732   // We do not need to grap the Threads_lock, since we are operating on ourself.
1733   Handle threadObj(thread, thread->threadObj());
1734   assert(threadObj.not_null(), "java thread object must exist");
1735   ObjectLocker lock(threadObj, thread);
1736   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1737   thread->clear_pending_exception();
1738   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1739   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1740   // Clear the native thread instance - this makes isAlive return false and allows the join()
1741   // to complete once we've done the notify_all below
1742   java_lang_Thread::set_thread(threadObj(), NULL);
1743   lock.notify_all(thread);
1744   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1745   thread->clear_pending_exception();
1746 }
1747 
1748 
1749 // For any new cleanup additions, please check to see if they need to be applied to
1750 // cleanup_failed_attach_current_thread as well.
1751 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1752   assert(this == JavaThread::current(), "thread consistency check");
1753 
1754   HandleMark hm(this);
1755   Handle uncaught_exception(this, this->pending_exception());
1756   this->clear_pending_exception();
1757   Handle threadObj(this, this->threadObj());
1758   assert(threadObj.not_null(), "Java thread object should be created");
1759 
1760   if (get_thread_profiler() != NULL) {
1761     get_thread_profiler()->disengage();
1762     ResourceMark rm;
1763     get_thread_profiler()->print(get_thread_name());
1764   }
1765 
1766 
1767   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1768   {
1769     EXCEPTION_MARK;
1770 
1771     CLEAR_PENDING_EXCEPTION;
1772   }
1773   if (!destroy_vm) {
1774     if (uncaught_exception.not_null()) {
1775       EXCEPTION_MARK;
1776       // Call method Thread.dispatchUncaughtException().
1777       KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1778       JavaValue result(T_VOID);
1779       JavaCalls::call_virtual(&result,
1780                               threadObj, thread_klass,
1781                               vmSymbols::dispatchUncaughtException_name(),
1782                               vmSymbols::throwable_void_signature(),
1783                               uncaught_exception,
1784                               THREAD);
1785       if (HAS_PENDING_EXCEPTION) {
1786         ResourceMark rm(this);
1787         jio_fprintf(defaultStream::error_stream(),
1788                     "\nException: %s thrown from the UncaughtExceptionHandler"
1789                     " in thread \"%s\"\n",
1790                     pending_exception()->klass()->external_name(),
1791                     get_thread_name());
1792         CLEAR_PENDING_EXCEPTION;
1793       }
1794     }
1795 
1796     // Called before the java thread exit since we want to read info
1797     // from java_lang_Thread object
1798     EventThreadEnd event;
1799     if (event.should_commit()) {
1800       event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj()));
1801       event.commit();
1802     }
1803 
1804     // Call after last event on thread
1805     EVENT_THREAD_EXIT(this);
1806 
1807     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1808     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1809     // is deprecated anyhow.
1810     if (!is_Compiler_thread()) {
1811       int count = 3;
1812       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1813         EXCEPTION_MARK;
1814         JavaValue result(T_VOID);
1815         KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1816         JavaCalls::call_virtual(&result,
1817                                 threadObj, thread_klass,
1818                                 vmSymbols::exit_method_name(),
1819                                 vmSymbols::void_method_signature(),
1820                                 THREAD);
1821         CLEAR_PENDING_EXCEPTION;
1822       }
1823     }
1824     // notify JVMTI
1825     if (JvmtiExport::should_post_thread_life()) {
1826       JvmtiExport::post_thread_end(this);
1827     }
1828 
1829     // We have notified the agents that we are exiting, before we go on,
1830     // we must check for a pending external suspend request and honor it
1831     // in order to not surprise the thread that made the suspend request.
1832     while (true) {
1833       {
1834         MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1835         if (!is_external_suspend()) {
1836           set_terminated(_thread_exiting);
1837           ThreadService::current_thread_exiting(this);
1838           break;
1839         }
1840         // Implied else:
1841         // Things get a little tricky here. We have a pending external
1842         // suspend request, but we are holding the SR_lock so we
1843         // can't just self-suspend. So we temporarily drop the lock
1844         // and then self-suspend.
1845       }
1846 
1847       ThreadBlockInVM tbivm(this);
1848       java_suspend_self();
1849 
1850       // We're done with this suspend request, but we have to loop around
1851       // and check again. Eventually we will get SR_lock without a pending
1852       // external suspend request and will be able to mark ourselves as
1853       // exiting.
1854     }
1855     // no more external suspends are allowed at this point
1856   } else {
1857     // before_exit() has already posted JVMTI THREAD_END events
1858   }
1859 
1860   // Notify waiters on thread object. This has to be done after exit() is called
1861   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1862   // group should have the destroyed bit set before waiters are notified).
1863   ensure_join(this);
1864   assert(!this->has_pending_exception(), "ensure_join should have cleared");
1865 
1866   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1867   // held by this thread must be released. The spec does not distinguish
1868   // between JNI-acquired and regular Java monitors. We can only see
1869   // regular Java monitors here if monitor enter-exit matching is broken.
1870   //
1871   // Optionally release any monitors for regular JavaThread exits. This
1872   // is provided as a work around for any bugs in monitor enter-exit
1873   // matching. This can be expensive so it is not enabled by default.
1874   //
1875   // ensure_join() ignores IllegalThreadStateExceptions, and so does
1876   // ObjectSynchronizer::release_monitors_owned_by_thread().
1877   if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1878     // Sanity check even though JNI DetachCurrentThread() would have
1879     // returned JNI_ERR if there was a Java frame. JavaThread exit
1880     // should be done executing Java code by the time we get here.
1881     assert(!this->has_last_Java_frame(),
1882            "should not have a Java frame when detaching or exiting");
1883     ObjectSynchronizer::release_monitors_owned_by_thread(this);
1884     assert(!this->has_pending_exception(), "release_monitors should have cleared");
1885   }
1886 
1887   // These things needs to be done while we are still a Java Thread. Make sure that thread
1888   // is in a consistent state, in case GC happens
1889   assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1890 
1891   if (active_handles() != NULL) {
1892     JNIHandleBlock* block = active_handles();
1893     set_active_handles(NULL);
1894     JNIHandleBlock::release_block(block);
1895   }
1896 
1897   if (free_handle_block() != NULL) {
1898     JNIHandleBlock* block = free_handle_block();
1899     set_free_handle_block(NULL);
1900     JNIHandleBlock::release_block(block);
1901   }
1902 
1903   // These have to be removed while this is still a valid thread.
1904   remove_stack_guard_pages();
1905 
1906   if (UseTLAB) {
1907     tlab().make_parsable(true);  // retire TLAB
1908   }
1909 
1910   if (JvmtiEnv::environments_might_exist()) {
1911     JvmtiExport::cleanup_thread(this);
1912   }
1913 
1914   // We must flush any deferred card marks before removing a thread from
1915   // the list of active threads.
1916   Universe::heap()->flush_deferred_store_barrier(this);
1917   assert(deferred_card_mark().is_empty(), "Should have been flushed");
1918 
1919 #if INCLUDE_ALL_GCS
1920   // We must flush the G1-related buffers before removing a thread
1921   // from the list of active threads. We must do this after any deferred
1922   // card marks have been flushed (above) so that any entries that are
1923   // added to the thread's dirty card queue as a result are not lost.
1924   if (UseG1GC) {
1925     flush_barrier_queues();
1926   }
1927 #endif // INCLUDE_ALL_GCS
1928 
1929   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1930   Threads::remove(this);
1931 }
1932 
1933 #if INCLUDE_ALL_GCS
1934 // Flush G1-related queues.
1935 void JavaThread::flush_barrier_queues() {
1936   satb_mark_queue().flush();
1937   dirty_card_queue().flush();
1938 }
1939 
1940 void JavaThread::initialize_queues() {
1941   assert(!SafepointSynchronize::is_at_safepoint(),
1942          "we should not be at a safepoint");
1943 
1944   SATBMarkQueue& satb_queue = satb_mark_queue();
1945   SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1946   // The SATB queue should have been constructed with its active
1947   // field set to false.
1948   assert(!satb_queue.is_active(), "SATB queue should not be active");
1949   assert(satb_queue.is_empty(), "SATB queue should be empty");
1950   // If we are creating the thread during a marking cycle, we should
1951   // set the active field of the SATB queue to true.
1952   if (satb_queue_set.is_active()) {
1953     satb_queue.set_active(true);
1954   }
1955 
1956   DirtyCardQueue& dirty_queue = dirty_card_queue();
1957   // The dirty card queue should have been constructed with its
1958   // active field set to true.
1959   assert(dirty_queue.is_active(), "dirty card queue should be active");
1960 }
1961 #endif // INCLUDE_ALL_GCS
1962 
1963 void JavaThread::cleanup_failed_attach_current_thread() {
1964   if (get_thread_profiler() != NULL) {
1965     get_thread_profiler()->disengage();
1966     ResourceMark rm;
1967     get_thread_profiler()->print(get_thread_name());
1968   }
1969 
1970   if (active_handles() != NULL) {
1971     JNIHandleBlock* block = active_handles();
1972     set_active_handles(NULL);
1973     JNIHandleBlock::release_block(block);
1974   }
1975 
1976   if (free_handle_block() != NULL) {
1977     JNIHandleBlock* block = free_handle_block();
1978     set_free_handle_block(NULL);
1979     JNIHandleBlock::release_block(block);
1980   }
1981 
1982   // These have to be removed while this is still a valid thread.
1983   remove_stack_guard_pages();
1984 
1985   if (UseTLAB) {
1986     tlab().make_parsable(true);  // retire TLAB, if any
1987   }
1988 
1989 #if INCLUDE_ALL_GCS
1990   if (UseG1GC) {
1991     flush_barrier_queues();
1992   }
1993 #endif // INCLUDE_ALL_GCS
1994 
1995   Threads::remove(this);
1996   delete this;
1997 }
1998 
1999 
2000 
2001 
2002 JavaThread* JavaThread::active() {
2003   Thread* thread = Thread::current();
2004   if (thread->is_Java_thread()) {
2005     return (JavaThread*) thread;
2006   } else {
2007     assert(thread->is_VM_thread(), "this must be a vm thread");
2008     VM_Operation* op = ((VMThread*) thread)->vm_operation();
2009     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2010     assert(ret->is_Java_thread(), "must be a Java thread");
2011     return ret;
2012   }
2013 }
2014 
2015 bool JavaThread::is_lock_owned(address adr) const {
2016   if (Thread::is_lock_owned(adr)) return true;
2017 
2018   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2019     if (chunk->contains(adr)) return true;
2020   }
2021 
2022   return false;
2023 }
2024 
2025 
2026 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2027   chunk->set_next(monitor_chunks());
2028   set_monitor_chunks(chunk);
2029 }
2030 
2031 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2032   guarantee(monitor_chunks() != NULL, "must be non empty");
2033   if (monitor_chunks() == chunk) {
2034     set_monitor_chunks(chunk->next());
2035   } else {
2036     MonitorChunk* prev = monitor_chunks();
2037     while (prev->next() != chunk) prev = prev->next();
2038     prev->set_next(chunk->next());
2039   }
2040 }
2041 
2042 // JVM support.
2043 
2044 // Note: this function shouldn't block if it's called in
2045 // _thread_in_native_trans state (such as from
2046 // check_special_condition_for_native_trans()).
2047 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2048 
2049   if (has_last_Java_frame() && has_async_condition()) {
2050     // If we are at a polling page safepoint (not a poll return)
2051     // then we must defer async exception because live registers
2052     // will be clobbered by the exception path. Poll return is
2053     // ok because the call we a returning from already collides
2054     // with exception handling registers and so there is no issue.
2055     // (The exception handling path kills call result registers but
2056     //  this is ok since the exception kills the result anyway).
2057 
2058     if (is_at_poll_safepoint()) {
2059       // if the code we are returning to has deoptimized we must defer
2060       // the exception otherwise live registers get clobbered on the
2061       // exception path before deoptimization is able to retrieve them.
2062       //
2063       RegisterMap map(this, false);
2064       frame caller_fr = last_frame().sender(&map);
2065       assert(caller_fr.is_compiled_frame(), "what?");
2066       if (caller_fr.is_deoptimized_frame()) {
2067         if (TraceExceptions) {
2068           ResourceMark rm;
2069           tty->print_cr("deferred async exception at compiled safepoint");
2070         }
2071         return;
2072       }
2073     }
2074   }
2075 
2076   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2077   if (condition == _no_async_condition) {
2078     // Conditions have changed since has_special_runtime_exit_condition()
2079     // was called:
2080     // - if we were here only because of an external suspend request,
2081     //   then that was taken care of above (or cancelled) so we are done
2082     // - if we were here because of another async request, then it has
2083     //   been cleared between the has_special_runtime_exit_condition()
2084     //   and now so again we are done
2085     return;
2086   }
2087 
2088   // Check for pending async. exception
2089   if (_pending_async_exception != NULL) {
2090     // Only overwrite an already pending exception, if it is not a threadDeath.
2091     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2092 
2093       // We cannot call Exceptions::_throw(...) here because we cannot block
2094       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2095 
2096       if (TraceExceptions) {
2097         ResourceMark rm;
2098         tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2099         if (has_last_Java_frame()) {
2100           frame f = last_frame();
2101           tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2102         }
2103         tty->print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2104       }
2105       _pending_async_exception = NULL;
2106       clear_has_async_exception();
2107     }
2108   }
2109 
2110   if (check_unsafe_error &&
2111       condition == _async_unsafe_access_error && !has_pending_exception()) {
2112     condition = _no_async_condition;  // done
2113     switch (thread_state()) {
2114     case _thread_in_vm: {
2115       JavaThread* THREAD = this;
2116       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2117     }
2118     case _thread_in_native: {
2119       ThreadInVMfromNative tiv(this);
2120       JavaThread* THREAD = this;
2121       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2122     }
2123     case _thread_in_Java: {
2124       ThreadInVMfromJava tiv(this);
2125       JavaThread* THREAD = this;
2126       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2127     }
2128     default:
2129       ShouldNotReachHere();
2130     }
2131   }
2132 
2133   assert(condition == _no_async_condition || has_pending_exception() ||
2134          (!check_unsafe_error && condition == _async_unsafe_access_error),
2135          "must have handled the async condition, if no exception");
2136 }
2137 
2138 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2139   //
2140   // Check for pending external suspend. Internal suspend requests do
2141   // not use handle_special_runtime_exit_condition().
2142   // If JNIEnv proxies are allowed, don't self-suspend if the target
2143   // thread is not the current thread. In older versions of jdbx, jdbx
2144   // threads could call into the VM with another thread's JNIEnv so we
2145   // can be here operating on behalf of a suspended thread (4432884).
2146   bool do_self_suspend = is_external_suspend_with_lock();
2147   if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2148     //
2149     // Because thread is external suspended the safepoint code will count
2150     // thread as at a safepoint. This can be odd because we can be here
2151     // as _thread_in_Java which would normally transition to _thread_blocked
2152     // at a safepoint. We would like to mark the thread as _thread_blocked
2153     // before calling java_suspend_self like all other callers of it but
2154     // we must then observe proper safepoint protocol. (We can't leave
2155     // _thread_blocked with a safepoint in progress). However we can be
2156     // here as _thread_in_native_trans so we can't use a normal transition
2157     // constructor/destructor pair because they assert on that type of
2158     // transition. We could do something like:
2159     //
2160     // JavaThreadState state = thread_state();
2161     // set_thread_state(_thread_in_vm);
2162     // {
2163     //   ThreadBlockInVM tbivm(this);
2164     //   java_suspend_self()
2165     // }
2166     // set_thread_state(_thread_in_vm_trans);
2167     // if (safepoint) block;
2168     // set_thread_state(state);
2169     //
2170     // but that is pretty messy. Instead we just go with the way the
2171     // code has worked before and note that this is the only path to
2172     // java_suspend_self that doesn't put the thread in _thread_blocked
2173     // mode.
2174 
2175     frame_anchor()->make_walkable(this);
2176     java_suspend_self();
2177 
2178     // We might be here for reasons in addition to the self-suspend request
2179     // so check for other async requests.
2180   }
2181 
2182   if (check_asyncs) {
2183     check_and_handle_async_exceptions();
2184   }
2185 }
2186 
2187 void JavaThread::send_thread_stop(oop java_throwable)  {
2188   assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2189   assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2190   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2191 
2192   // Do not throw asynchronous exceptions against the compiler thread
2193   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2194   if (!can_call_java()) return;
2195 
2196   {
2197     // Actually throw the Throwable against the target Thread - however
2198     // only if there is no thread death exception installed already.
2199     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2200       // If the topmost frame is a runtime stub, then we are calling into
2201       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2202       // must deoptimize the caller before continuing, as the compiled  exception handler table
2203       // may not be valid
2204       if (has_last_Java_frame()) {
2205         frame f = last_frame();
2206         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2207           // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2208           RegisterMap reg_map(this, UseBiasedLocking);
2209           frame compiled_frame = f.sender(&reg_map);
2210           if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2211             Deoptimization::deoptimize(this, compiled_frame, &reg_map);
2212           }
2213         }
2214       }
2215 
2216       // Set async. pending exception in thread.
2217       set_pending_async_exception(java_throwable);
2218 
2219       if (TraceExceptions) {
2220         ResourceMark rm;
2221         tty->print_cr("Pending Async. exception installed of type: %s", _pending_async_exception->klass()->external_name());
2222       }
2223       // for AbortVMOnException flag
2224       Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2225     }
2226   }
2227 
2228 
2229   // Interrupt thread so it will wake up from a potential wait()
2230   Thread::interrupt(this);
2231 }
2232 
2233 // External suspension mechanism.
2234 //
2235 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2236 // to any VM_locks and it is at a transition
2237 // Self-suspension will happen on the transition out of the vm.
2238 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2239 //
2240 // Guarantees on return:
2241 //   + Target thread will not execute any new bytecode (that's why we need to
2242 //     force a safepoint)
2243 //   + Target thread will not enter any new monitors
2244 //
2245 void JavaThread::java_suspend() {
2246   { MutexLocker mu(Threads_lock);
2247     if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2248       return;
2249     }
2250   }
2251 
2252   { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2253     if (!is_external_suspend()) {
2254       // a racing resume has cancelled us; bail out now
2255       return;
2256     }
2257 
2258     // suspend is done
2259     uint32_t debug_bits = 0;
2260     // Warning: is_ext_suspend_completed() may temporarily drop the
2261     // SR_lock to allow the thread to reach a stable thread state if
2262     // it is currently in a transient thread state.
2263     if (is_ext_suspend_completed(false /* !called_by_wait */,
2264                                  SuspendRetryDelay, &debug_bits)) {
2265       return;
2266     }
2267   }
2268 
2269   VM_ForceSafepoint vm_suspend;
2270   VMThread::execute(&vm_suspend);
2271 }
2272 
2273 // Part II of external suspension.
2274 // A JavaThread self suspends when it detects a pending external suspend
2275 // request. This is usually on transitions. It is also done in places
2276 // where continuing to the next transition would surprise the caller,
2277 // e.g., monitor entry.
2278 //
2279 // Returns the number of times that the thread self-suspended.
2280 //
2281 // Note: DO NOT call java_suspend_self() when you just want to block current
2282 //       thread. java_suspend_self() is the second stage of cooperative
2283 //       suspension for external suspend requests and should only be used
2284 //       to complete an external suspend request.
2285 //
2286 int JavaThread::java_suspend_self() {
2287   int ret = 0;
2288 
2289   // we are in the process of exiting so don't suspend
2290   if (is_exiting()) {
2291     clear_external_suspend();
2292     return ret;
2293   }
2294 
2295   assert(_anchor.walkable() ||
2296          (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2297          "must have walkable stack");
2298 
2299   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2300 
2301   assert(!this->is_ext_suspended(),
2302          "a thread trying to self-suspend should not already be suspended");
2303 
2304   if (this->is_suspend_equivalent()) {
2305     // If we are self-suspending as a result of the lifting of a
2306     // suspend equivalent condition, then the suspend_equivalent
2307     // flag is not cleared until we set the ext_suspended flag so
2308     // that wait_for_ext_suspend_completion() returns consistent
2309     // results.
2310     this->clear_suspend_equivalent();
2311   }
2312 
2313   // A racing resume may have cancelled us before we grabbed SR_lock
2314   // above. Or another external suspend request could be waiting for us
2315   // by the time we return from SR_lock()->wait(). The thread
2316   // that requested the suspension may already be trying to walk our
2317   // stack and if we return now, we can change the stack out from under
2318   // it. This would be a "bad thing (TM)" and cause the stack walker
2319   // to crash. We stay self-suspended until there are no more pending
2320   // external suspend requests.
2321   while (is_external_suspend()) {
2322     ret++;
2323     this->set_ext_suspended();
2324 
2325     // _ext_suspended flag is cleared by java_resume()
2326     while (is_ext_suspended()) {
2327       this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2328     }
2329   }
2330 
2331   return ret;
2332 }
2333 
2334 #ifdef ASSERT
2335 // verify the JavaThread has not yet been published in the Threads::list, and
2336 // hence doesn't need protection from concurrent access at this stage
2337 void JavaThread::verify_not_published() {
2338   if (!Threads_lock->owned_by_self()) {
2339     MutexLockerEx ml(Threads_lock,  Mutex::_no_safepoint_check_flag);
2340     assert(!Threads::includes(this),
2341            "java thread shouldn't have been published yet!");
2342   } else {
2343     assert(!Threads::includes(this),
2344            "java thread shouldn't have been published yet!");
2345   }
2346 }
2347 #endif
2348 
2349 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2350 // progress or when _suspend_flags is non-zero.
2351 // Current thread needs to self-suspend if there is a suspend request and/or
2352 // block if a safepoint is in progress.
2353 // Async exception ISN'T checked.
2354 // Note only the ThreadInVMfromNative transition can call this function
2355 // directly and when thread state is _thread_in_native_trans
2356 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2357   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2358 
2359   JavaThread *curJT = JavaThread::current();
2360   bool do_self_suspend = thread->is_external_suspend();
2361 
2362   assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2363 
2364   // If JNIEnv proxies are allowed, don't self-suspend if the target
2365   // thread is not the current thread. In older versions of jdbx, jdbx
2366   // threads could call into the VM with another thread's JNIEnv so we
2367   // can be here operating on behalf of a suspended thread (4432884).
2368   if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2369     JavaThreadState state = thread->thread_state();
2370 
2371     // We mark this thread_blocked state as a suspend-equivalent so
2372     // that a caller to is_ext_suspend_completed() won't be confused.
2373     // The suspend-equivalent state is cleared by java_suspend_self().
2374     thread->set_suspend_equivalent();
2375 
2376     // If the safepoint code sees the _thread_in_native_trans state, it will
2377     // wait until the thread changes to other thread state. There is no
2378     // guarantee on how soon we can obtain the SR_lock and complete the
2379     // self-suspend request. It would be a bad idea to let safepoint wait for
2380     // too long. Temporarily change the state to _thread_blocked to
2381     // let the VM thread know that this thread is ready for GC. The problem
2382     // of changing thread state is that safepoint could happen just after
2383     // java_suspend_self() returns after being resumed, and VM thread will
2384     // see the _thread_blocked state. We must check for safepoint
2385     // after restoring the state and make sure we won't leave while a safepoint
2386     // is in progress.
2387     thread->set_thread_state(_thread_blocked);
2388     thread->java_suspend_self();
2389     thread->set_thread_state(state);
2390     // Make sure new state is seen by VM thread
2391     if (os::is_MP()) {
2392       if (UseMembar) {
2393         // Force a fence between the write above and read below
2394         OrderAccess::fence();
2395       } else {
2396         // Must use this rather than serialization page in particular on Windows
2397         InterfaceSupport::serialize_memory(thread);
2398       }
2399     }
2400   }
2401 
2402   if (SafepointSynchronize::do_call_back()) {
2403     // If we are safepointing, then block the caller which may not be
2404     // the same as the target thread (see above).
2405     SafepointSynchronize::block(curJT);
2406   }
2407 
2408   if (thread->is_deopt_suspend()) {
2409     thread->clear_deopt_suspend();
2410     RegisterMap map(thread, false);
2411     frame f = thread->last_frame();
2412     while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2413       f = f.sender(&map);
2414     }
2415     if (f.id() == thread->must_deopt_id()) {
2416       thread->clear_must_deopt_id();
2417       f.deoptimize(thread);
2418     } else {
2419       fatal("missed deoptimization!");
2420     }
2421   }
2422 }
2423 
2424 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2425 // progress or when _suspend_flags is non-zero.
2426 // Current thread needs to self-suspend if there is a suspend request and/or
2427 // block if a safepoint is in progress.
2428 // Also check for pending async exception (not including unsafe access error).
2429 // Note only the native==>VM/Java barriers can call this function and when
2430 // thread state is _thread_in_native_trans.
2431 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2432   check_safepoint_and_suspend_for_native_trans(thread);
2433 
2434   if (thread->has_async_exception()) {
2435     // We are in _thread_in_native_trans state, don't handle unsafe
2436     // access error since that may block.
2437     thread->check_and_handle_async_exceptions(false);
2438   }
2439 }
2440 
2441 // This is a variant of the normal
2442 // check_special_condition_for_native_trans with slightly different
2443 // semantics for use by critical native wrappers.  It does all the
2444 // normal checks but also performs the transition back into
2445 // thread_in_Java state.  This is required so that critical natives
2446 // can potentially block and perform a GC if they are the last thread
2447 // exiting the GC_locker.
2448 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2449   check_special_condition_for_native_trans(thread);
2450 
2451   // Finish the transition
2452   thread->set_thread_state(_thread_in_Java);
2453 
2454   if (thread->do_critical_native_unlock()) {
2455     ThreadInVMfromJavaNoAsyncException tiv(thread);
2456     GC_locker::unlock_critical(thread);
2457     thread->clear_critical_native_unlock();
2458   }
2459 }
2460 
2461 // We need to guarantee the Threads_lock here, since resumes are not
2462 // allowed during safepoint synchronization
2463 // Can only resume from an external suspension
2464 void JavaThread::java_resume() {
2465   assert_locked_or_safepoint(Threads_lock);
2466 
2467   // Sanity check: thread is gone, has started exiting or the thread
2468   // was not externally suspended.
2469   if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2470     return;
2471   }
2472 
2473   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2474 
2475   clear_external_suspend();
2476 
2477   if (is_ext_suspended()) {
2478     clear_ext_suspended();
2479     SR_lock()->notify_all();
2480   }
2481 }
2482 
2483 void JavaThread::create_stack_guard_pages() {
2484   if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return;
2485   address low_addr = stack_base() - stack_size();
2486   size_t len = (StackReservedPages + StackYellowPages + StackRedPages) * os::vm_page_size();
2487 
2488   int allocate = os::allocate_stack_guard_pages();
2489   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2490 
2491   if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) {
2492     warning("Attempt to allocate stack guard pages failed.");
2493     return;
2494   }
2495 
2496   if (os::guard_memory((char *) low_addr, len)) {
2497     _stack_guard_state = stack_guard_enabled;
2498   } else {
2499     warning("Attempt to protect stack guard pages failed.");
2500     if (os::uncommit_memory((char *) low_addr, len)) {
2501       warning("Attempt to deallocate stack guard pages failed.");
2502     }
2503   }
2504 }
2505 
2506 void JavaThread::remove_stack_guard_pages() {
2507   assert(Thread::current() == this, "from different thread");
2508   if (_stack_guard_state == stack_guard_unused) return;
2509   address low_addr = stack_base() - stack_size();
2510   size_t len = (StackReservedPages + StackYellowPages + StackRedPages) * os::vm_page_size();
2511 
2512   if (os::allocate_stack_guard_pages()) {
2513     if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2514       _stack_guard_state = stack_guard_unused;
2515     } else {
2516       warning("Attempt to deallocate stack guard pages failed.");
2517     }
2518   } else {
2519     if (_stack_guard_state == stack_guard_unused) return;
2520     if (os::unguard_memory((char *) low_addr, len)) {
2521       _stack_guard_state = stack_guard_unused;
2522     } else {
2523       warning("Attempt to unprotect stack guard pages failed.");
2524     }
2525   }
2526 }
2527 
2528 void JavaThread::enable_stack_reserved_zone() {
2529   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2530   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2531 
2532   // The base notation is from the stack's point of view, growing downward.
2533   // We need to adjust it to work correctly with guard_memory()
2534   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2535 
2536   guarantee(base < stack_base(),"Error calculating stack reserved zone");
2537   guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2538 
2539   if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2540     _stack_guard_state = stack_guard_enabled;
2541   } else {
2542     warning("Attempt to guard stack reserved zone failed.");
2543   }
2544   enable_register_stack_guard();
2545 }
2546 
2547 void JavaThread::disable_stack_reserved_zone() {
2548   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2549   assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2550 
2551   // Simply return if called for a thread that does not use guard pages.
2552   if (_stack_guard_state == stack_guard_unused) return;
2553 
2554   // The base notation is from the stack's point of view, growing downward.
2555   // We need to adjust it to work correctly with guard_memory()
2556   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2557 
2558   if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2559     _stack_guard_state = stack_guard_reserved_disabled;
2560   } else {
2561     warning("Attempt to unguard stack reserved zone failed.");
2562   }
2563   disable_register_stack_guard();
2564 }
2565 
2566 void JavaThread::enable_stack_yellow_zone() {
2567   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2568   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2569 
2570   // The base notation is from the stacks point of view, growing downward.
2571   // We need to adjust it to work correctly with guard_memory()
2572   address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2573 
2574   guarantee(base < stack_base(), "Error calculating stack yellow zone");
2575   guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2576 
2577   if (os::guard_memory((char *) base, stack_yellow_zone_size())) {
2578     _stack_guard_state = stack_guard_enabled;
2579   } else {
2580     warning("Attempt to guard stack yellow zone failed.");
2581   }
2582   enable_register_stack_guard();
2583 }
2584 
2585 void JavaThread::disable_stack_yellow_zone() {
2586   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2587   assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled");
2588 
2589   // Simply return if called for a thread that does not use guard pages.
2590   if (_stack_guard_state == stack_guard_unused) return;
2591 
2592   // The base notation is from the stacks point of view, growing downward.
2593   // We need to adjust it to work correctly with guard_memory()
2594   address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2595 
2596   if (os::unguard_memory((char *)base, stack_yellow_zone_size())) {
2597     _stack_guard_state = stack_guard_yellow_disabled;
2598   } else {
2599     warning("Attempt to unguard stack yellow zone failed.");
2600   }
2601   disable_register_stack_guard();
2602 }
2603 
2604 void JavaThread::enable_stack_red_zone() {
2605   // The base notation is from the stacks point of view, growing downward.
2606   // We need to adjust it to work correctly with guard_memory()
2607   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2608   address base = stack_red_zone_base() - stack_red_zone_size();
2609 
2610   guarantee(base < stack_base(), "Error calculating stack red zone");
2611   guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2612 
2613   if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2614     warning("Attempt to guard stack red zone failed.");
2615   }
2616 }
2617 
2618 void JavaThread::disable_stack_red_zone() {
2619   // The base notation is from the stacks point of view, growing downward.
2620   // We need to adjust it to work correctly with guard_memory()
2621   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2622   address base = stack_red_zone_base() - stack_red_zone_size();
2623   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2624     warning("Attempt to unguard stack red zone failed.");
2625   }
2626 }
2627 
2628 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2629   // ignore is there is no stack
2630   if (!has_last_Java_frame()) return;
2631   // traverse the stack frames. Starts from top frame.
2632   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2633     frame* fr = fst.current();
2634     f(fr, fst.register_map());
2635   }
2636 }
2637 
2638 
2639 #ifndef PRODUCT
2640 // Deoptimization
2641 // Function for testing deoptimization
2642 void JavaThread::deoptimize() {
2643   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2644   StackFrameStream fst(this, UseBiasedLocking);
2645   bool deopt = false;           // Dump stack only if a deopt actually happens.
2646   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2647   // Iterate over all frames in the thread and deoptimize
2648   for (; !fst.is_done(); fst.next()) {
2649     if (fst.current()->can_be_deoptimized()) {
2650 
2651       if (only_at) {
2652         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
2653         // consists of comma or carriage return separated numbers so
2654         // search for the current bci in that string.
2655         address pc = fst.current()->pc();
2656         nmethod* nm =  (nmethod*) fst.current()->cb();
2657         ScopeDesc* sd = nm->scope_desc_at(pc);
2658         char buffer[8];
2659         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2660         size_t len = strlen(buffer);
2661         const char * found = strstr(DeoptimizeOnlyAt, buffer);
2662         while (found != NULL) {
2663           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2664               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2665             // Check that the bci found is bracketed by terminators.
2666             break;
2667           }
2668           found = strstr(found + 1, buffer);
2669         }
2670         if (!found) {
2671           continue;
2672         }
2673       }
2674 
2675       if (DebugDeoptimization && !deopt) {
2676         deopt = true; // One-time only print before deopt
2677         tty->print_cr("[BEFORE Deoptimization]");
2678         trace_frames();
2679         trace_stack();
2680       }
2681       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2682     }
2683   }
2684 
2685   if (DebugDeoptimization && deopt) {
2686     tty->print_cr("[AFTER Deoptimization]");
2687     trace_frames();
2688   }
2689 }
2690 
2691 
2692 // Make zombies
2693 void JavaThread::make_zombies() {
2694   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2695     if (fst.current()->can_be_deoptimized()) {
2696       // it is a Java nmethod
2697       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2698       nm->make_not_entrant();
2699     }
2700   }
2701 }
2702 #endif // PRODUCT
2703 
2704 
2705 void JavaThread::deoptimized_wrt_marked_nmethods() {
2706   if (!has_last_Java_frame()) return;
2707   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2708   StackFrameStream fst(this, UseBiasedLocking);
2709   for (; !fst.is_done(); fst.next()) {
2710     if (fst.current()->should_be_deoptimized()) {
2711       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2712     }
2713   }
2714 }
2715 
2716 
2717 // If the caller is a NamedThread, then remember, in the current scope,
2718 // the given JavaThread in its _processed_thread field.
2719 class RememberProcessedThread: public StackObj {
2720   NamedThread* _cur_thr;
2721  public:
2722   RememberProcessedThread(JavaThread* jthr) {
2723     Thread* thread = Thread::current();
2724     if (thread->is_Named_thread()) {
2725       _cur_thr = (NamedThread *)thread;
2726       _cur_thr->set_processed_thread(jthr);
2727     } else {
2728       _cur_thr = NULL;
2729     }
2730   }
2731 
2732   ~RememberProcessedThread() {
2733     if (_cur_thr) {
2734       _cur_thr->set_processed_thread(NULL);
2735     }
2736   }
2737 };
2738 
2739 void JavaThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
2740   // Verify that the deferred card marks have been flushed.
2741   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2742 
2743   // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2744   // since there may be more than one thread using each ThreadProfiler.
2745 
2746   // Traverse the GCHandles
2747   Thread::oops_do(f, cld_f, cf);
2748 
2749   JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2750 
2751   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2752          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2753 
2754   if (has_last_Java_frame()) {
2755     // Record JavaThread to GC thread
2756     RememberProcessedThread rpt(this);
2757 
2758     // Traverse the privileged stack
2759     if (_privileged_stack_top != NULL) {
2760       _privileged_stack_top->oops_do(f);
2761     }
2762 
2763     // traverse the registered growable array
2764     if (_array_for_gc != NULL) {
2765       for (int index = 0; index < _array_for_gc->length(); index++) {
2766         f->do_oop(_array_for_gc->adr_at(index));
2767       }
2768     }
2769 
2770     // Traverse the monitor chunks
2771     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2772       chunk->oops_do(f);
2773     }
2774 
2775     // Traverse the execution stack
2776     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2777       fst.current()->oops_do(f, cld_f, cf, fst.register_map());
2778     }
2779   }
2780 
2781   // callee_target is never live across a gc point so NULL it here should
2782   // it still contain a methdOop.
2783 
2784   set_callee_target(NULL);
2785 
2786   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2787   // If we have deferred set_locals there might be oops waiting to be
2788   // written
2789   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2790   if (list != NULL) {
2791     for (int i = 0; i < list->length(); i++) {
2792       list->at(i)->oops_do(f);
2793     }
2794   }
2795 
2796   // Traverse instance variables at the end since the GC may be moving things
2797   // around using this function
2798   f->do_oop((oop*) &_threadObj);
2799   f->do_oop((oop*) &_vm_result);
2800   f->do_oop((oop*) &_exception_oop);
2801   f->do_oop((oop*) &_pending_async_exception);
2802 
2803   if (jvmti_thread_state() != NULL) {
2804     jvmti_thread_state()->oops_do(f);
2805   }
2806 }
2807 
2808 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2809   Thread::nmethods_do(cf);  // (super method is a no-op)
2810 
2811   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2812          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2813 
2814   if (has_last_Java_frame()) {
2815     // Traverse the execution stack
2816     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2817       fst.current()->nmethods_do(cf);
2818     }
2819   }
2820 }
2821 
2822 void JavaThread::metadata_do(void f(Metadata*)) {
2823   if (has_last_Java_frame()) {
2824     // Traverse the execution stack to call f() on the methods in the stack
2825     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2826       fst.current()->metadata_do(f);
2827     }
2828   } else if (is_Compiler_thread()) {
2829     // need to walk ciMetadata in current compile tasks to keep alive.
2830     CompilerThread* ct = (CompilerThread*)this;
2831     if (ct->env() != NULL) {
2832       ct->env()->metadata_do(f);
2833     }
2834     if (ct->task() != NULL) {
2835       ct->task()->metadata_do(f);
2836     }
2837   }
2838 }
2839 
2840 // Printing
2841 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2842   switch (_thread_state) {
2843   case _thread_uninitialized:     return "_thread_uninitialized";
2844   case _thread_new:               return "_thread_new";
2845   case _thread_new_trans:         return "_thread_new_trans";
2846   case _thread_in_native:         return "_thread_in_native";
2847   case _thread_in_native_trans:   return "_thread_in_native_trans";
2848   case _thread_in_vm:             return "_thread_in_vm";
2849   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
2850   case _thread_in_Java:           return "_thread_in_Java";
2851   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
2852   case _thread_blocked:           return "_thread_blocked";
2853   case _thread_blocked_trans:     return "_thread_blocked_trans";
2854   default:                        return "unknown thread state";
2855   }
2856 }
2857 
2858 #ifndef PRODUCT
2859 void JavaThread::print_thread_state_on(outputStream *st) const {
2860   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
2861 };
2862 void JavaThread::print_thread_state() const {
2863   print_thread_state_on(tty);
2864 }
2865 #endif // PRODUCT
2866 
2867 // Called by Threads::print() for VM_PrintThreads operation
2868 void JavaThread::print_on(outputStream *st) const {
2869   st->print("\"%s\" ", get_thread_name());
2870   oop thread_oop = threadObj();
2871   if (thread_oop != NULL) {
2872     st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop));
2873     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
2874     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2875   }
2876   Thread::print_on(st);
2877   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2878   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2879   if (thread_oop != NULL) {
2880     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2881   }
2882 #ifndef PRODUCT
2883   print_thread_state_on(st);
2884   _safepoint_state->print_on(st);
2885 #endif // PRODUCT
2886 }
2887 
2888 // Called by fatal error handler. The difference between this and
2889 // JavaThread::print() is that we can't grab lock or allocate memory.
2890 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2891   st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2892   oop thread_obj = threadObj();
2893   if (thread_obj != NULL) {
2894     if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2895   }
2896   st->print(" [");
2897   st->print("%s", _get_thread_state_name(_thread_state));
2898   if (osthread()) {
2899     st->print(", id=%d", osthread()->thread_id());
2900   }
2901   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2902             p2i(_stack_base - _stack_size), p2i(_stack_base));
2903   st->print("]");
2904   return;
2905 }
2906 
2907 // Verification
2908 
2909 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2910 
2911 void JavaThread::verify() {
2912   // Verify oops in the thread.
2913   oops_do(&VerifyOopClosure::verify_oop, NULL, NULL);
2914 
2915   // Verify the stack frames.
2916   frames_do(frame_verify);
2917 }
2918 
2919 // CR 6300358 (sub-CR 2137150)
2920 // Most callers of this method assume that it can't return NULL but a
2921 // thread may not have a name whilst it is in the process of attaching to
2922 // the VM - see CR 6412693, and there are places where a JavaThread can be
2923 // seen prior to having it's threadObj set (eg JNI attaching threads and
2924 // if vm exit occurs during initialization). These cases can all be accounted
2925 // for such that this method never returns NULL.
2926 const char* JavaThread::get_thread_name() const {
2927 #ifdef ASSERT
2928   // early safepoints can hit while current thread does not yet have TLS
2929   if (!SafepointSynchronize::is_at_safepoint()) {
2930     Thread *cur = Thread::current();
2931     if (!(cur->is_Java_thread() && cur == this)) {
2932       // Current JavaThreads are allowed to get their own name without
2933       // the Threads_lock.
2934       assert_locked_or_safepoint(Threads_lock);
2935     }
2936   }
2937 #endif // ASSERT
2938   return get_thread_name_string();
2939 }
2940 
2941 // Returns a non-NULL representation of this thread's name, or a suitable
2942 // descriptive string if there is no set name
2943 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2944   const char* name_str;
2945   oop thread_obj = threadObj();
2946   if (thread_obj != NULL) {
2947     oop name = java_lang_Thread::name(thread_obj);
2948     if (name != NULL) {
2949       if (buf == NULL) {
2950         name_str = java_lang_String::as_utf8_string(name);
2951       } else {
2952         name_str = java_lang_String::as_utf8_string(name, buf, buflen);
2953       }
2954     } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
2955       name_str = "<no-name - thread is attaching>";
2956     } else {
2957       name_str = Thread::name();
2958     }
2959   } else {
2960     name_str = Thread::name();
2961   }
2962   assert(name_str != NULL, "unexpected NULL thread name");
2963   return name_str;
2964 }
2965 
2966 
2967 const char* JavaThread::get_threadgroup_name() const {
2968   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2969   oop thread_obj = threadObj();
2970   if (thread_obj != NULL) {
2971     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2972     if (thread_group != NULL) {
2973       // ThreadGroup.name can be null
2974       return java_lang_ThreadGroup::name(thread_group);
2975     }
2976   }
2977   return NULL;
2978 }
2979 
2980 const char* JavaThread::get_parent_name() const {
2981   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2982   oop thread_obj = threadObj();
2983   if (thread_obj != NULL) {
2984     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2985     if (thread_group != NULL) {
2986       oop parent = java_lang_ThreadGroup::parent(thread_group);
2987       if (parent != NULL) {
2988         // ThreadGroup.name can be null
2989         return java_lang_ThreadGroup::name(parent);
2990       }
2991     }
2992   }
2993   return NULL;
2994 }
2995 
2996 ThreadPriority JavaThread::java_priority() const {
2997   oop thr_oop = threadObj();
2998   if (thr_oop == NULL) return NormPriority; // Bootstrapping
2999   ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3000   assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3001   return priority;
3002 }
3003 
3004 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3005 
3006   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3007   // Link Java Thread object <-> C++ Thread
3008 
3009   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3010   // and put it into a new Handle.  The Handle "thread_oop" can then
3011   // be used to pass the C++ thread object to other methods.
3012 
3013   // Set the Java level thread object (jthread) field of the
3014   // new thread (a JavaThread *) to C++ thread object using the
3015   // "thread_oop" handle.
3016 
3017   // Set the thread field (a JavaThread *) of the
3018   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3019 
3020   Handle thread_oop(Thread::current(),
3021                     JNIHandles::resolve_non_null(jni_thread));
3022   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3023          "must be initialized");
3024   set_threadObj(thread_oop());
3025   java_lang_Thread::set_thread(thread_oop(), this);
3026 
3027   if (prio == NoPriority) {
3028     prio = java_lang_Thread::priority(thread_oop());
3029     assert(prio != NoPriority, "A valid priority should be present");
3030   }
3031 
3032   // Push the Java priority down to the native thread; needs Threads_lock
3033   Thread::set_priority(this, prio);
3034 
3035   prepare_ext();
3036 
3037   // Add the new thread to the Threads list and set it in motion.
3038   // We must have threads lock in order to call Threads::add.
3039   // It is crucial that we do not block before the thread is
3040   // added to the Threads list for if a GC happens, then the java_thread oop
3041   // will not be visited by GC.
3042   Threads::add(this);
3043 }
3044 
3045 oop JavaThread::current_park_blocker() {
3046   // Support for JSR-166 locks
3047   oop thread_oop = threadObj();
3048   if (thread_oop != NULL &&
3049       JDK_Version::current().supports_thread_park_blocker()) {
3050     return java_lang_Thread::park_blocker(thread_oop);
3051   }
3052   return NULL;
3053 }
3054 
3055 
3056 void JavaThread::print_stack_on(outputStream* st) {
3057   if (!has_last_Java_frame()) return;
3058   ResourceMark rm;
3059   HandleMark   hm;
3060 
3061   RegisterMap reg_map(this);
3062   vframe* start_vf = last_java_vframe(&reg_map);
3063   int count = 0;
3064   for (vframe* f = start_vf; f; f = f->sender()) {
3065     if (f->is_java_frame()) {
3066       javaVFrame* jvf = javaVFrame::cast(f);
3067       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3068 
3069       // Print out lock information
3070       if (JavaMonitorsInStackTrace) {
3071         jvf->print_lock_info_on(st, count);
3072       }
3073     } else {
3074       // Ignore non-Java frames
3075     }
3076 
3077     // Bail-out case for too deep stacks
3078     count++;
3079     if (MaxJavaStackTraceDepth == count) return;
3080   }
3081 }
3082 
3083 
3084 // JVMTI PopFrame support
3085 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3086   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3087   if (in_bytes(size_in_bytes) != 0) {
3088     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3089     _popframe_preserved_args_size = in_bytes(size_in_bytes);
3090     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3091   }
3092 }
3093 
3094 void* JavaThread::popframe_preserved_args() {
3095   return _popframe_preserved_args;
3096 }
3097 
3098 ByteSize JavaThread::popframe_preserved_args_size() {
3099   return in_ByteSize(_popframe_preserved_args_size);
3100 }
3101 
3102 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3103   int sz = in_bytes(popframe_preserved_args_size());
3104   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3105   return in_WordSize(sz / wordSize);
3106 }
3107 
3108 void JavaThread::popframe_free_preserved_args() {
3109   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3110   FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3111   _popframe_preserved_args = NULL;
3112   _popframe_preserved_args_size = 0;
3113 }
3114 
3115 #ifndef PRODUCT
3116 
3117 void JavaThread::trace_frames() {
3118   tty->print_cr("[Describe stack]");
3119   int frame_no = 1;
3120   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3121     tty->print("  %d. ", frame_no++);
3122     fst.current()->print_value_on(tty, this);
3123     tty->cr();
3124   }
3125 }
3126 
3127 class PrintAndVerifyOopClosure: public OopClosure {
3128  protected:
3129   template <class T> inline void do_oop_work(T* p) {
3130     oop obj = oopDesc::load_decode_heap_oop(p);
3131     if (obj == NULL) return;
3132     tty->print(INTPTR_FORMAT ": ", p2i(p));
3133     if (obj->is_oop_or_null()) {
3134       if (obj->is_objArray()) {
3135         tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3136       } else {
3137         obj->print();
3138       }
3139     } else {
3140       tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3141     }
3142     tty->cr();
3143   }
3144  public:
3145   virtual void do_oop(oop* p) { do_oop_work(p); }
3146   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
3147 };
3148 
3149 
3150 static void oops_print(frame* f, const RegisterMap *map) {
3151   PrintAndVerifyOopClosure print;
3152   f->print_value();
3153   f->oops_do(&print, NULL, NULL, (RegisterMap*)map);
3154 }
3155 
3156 // Print our all the locations that contain oops and whether they are
3157 // valid or not.  This useful when trying to find the oldest frame
3158 // where an oop has gone bad since the frame walk is from youngest to
3159 // oldest.
3160 void JavaThread::trace_oops() {
3161   tty->print_cr("[Trace oops]");
3162   frames_do(oops_print);
3163 }
3164 
3165 
3166 #ifdef ASSERT
3167 // Print or validate the layout of stack frames
3168 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3169   ResourceMark rm;
3170   PRESERVE_EXCEPTION_MARK;
3171   FrameValues values;
3172   int frame_no = 0;
3173   for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3174     fst.current()->describe(values, ++frame_no);
3175     if (depth == frame_no) break;
3176   }
3177   if (validate_only) {
3178     values.validate();
3179   } else {
3180     tty->print_cr("[Describe stack layout]");
3181     values.print(this);
3182   }
3183 }
3184 #endif
3185 
3186 void JavaThread::trace_stack_from(vframe* start_vf) {
3187   ResourceMark rm;
3188   int vframe_no = 1;
3189   for (vframe* f = start_vf; f; f = f->sender()) {
3190     if (f->is_java_frame()) {
3191       javaVFrame::cast(f)->print_activation(vframe_no++);
3192     } else {
3193       f->print();
3194     }
3195     if (vframe_no > StackPrintLimit) {
3196       tty->print_cr("...<more frames>...");
3197       return;
3198     }
3199   }
3200 }
3201 
3202 
3203 void JavaThread::trace_stack() {
3204   if (!has_last_Java_frame()) return;
3205   ResourceMark rm;
3206   HandleMark   hm;
3207   RegisterMap reg_map(this);
3208   trace_stack_from(last_java_vframe(&reg_map));
3209 }
3210 
3211 
3212 #endif // PRODUCT
3213 
3214 
3215 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3216   assert(reg_map != NULL, "a map must be given");
3217   frame f = last_frame();
3218   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3219     if (vf->is_java_frame()) return javaVFrame::cast(vf);
3220   }
3221   return NULL;
3222 }
3223 
3224 
3225 Klass* JavaThread::security_get_caller_class(int depth) {
3226   vframeStream vfst(this);
3227   vfst.security_get_caller_frame(depth);
3228   if (!vfst.at_end()) {
3229     return vfst.method()->method_holder();
3230   }
3231   return NULL;
3232 }
3233 
3234 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3235   assert(thread->is_Compiler_thread(), "must be compiler thread");
3236   CompileBroker::compiler_thread_loop();
3237 }
3238 
3239 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3240   NMethodSweeper::sweeper_loop();
3241 }
3242 
3243 // Create a CompilerThread
3244 CompilerThread::CompilerThread(CompileQueue* queue,
3245                                CompilerCounters* counters)
3246                                : JavaThread(&compiler_thread_entry) {
3247   _env   = NULL;
3248   _log   = NULL;
3249   _task  = NULL;
3250   _queue = queue;
3251   _counters = counters;
3252   _buffer_blob = NULL;
3253   _compiler = NULL;
3254 
3255 #ifndef PRODUCT
3256   _ideal_graph_printer = NULL;
3257 #endif
3258 }
3259 
3260 bool CompilerThread::can_call_java() const {
3261   return _compiler != NULL && _compiler->is_jvmci();
3262 }
3263 
3264 // Create sweeper thread
3265 CodeCacheSweeperThread::CodeCacheSweeperThread()
3266 : JavaThread(&sweeper_thread_entry) {
3267   _scanned_nmethod = NULL;
3268 }
3269 void CodeCacheSweeperThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
3270   JavaThread::oops_do(f, cld_f, cf);
3271   if (_scanned_nmethod != NULL && cf != NULL) {
3272     // Safepoints can occur when the sweeper is scanning an nmethod so
3273     // process it here to make sure it isn't unloaded in the middle of
3274     // a scan.
3275     cf->do_code_blob(_scanned_nmethod);
3276   }
3277 }
3278 
3279 
3280 // ======= Threads ========
3281 
3282 // The Threads class links together all active threads, and provides
3283 // operations over all threads.  It is protected by its own Mutex
3284 // lock, which is also used in other contexts to protect thread
3285 // operations from having the thread being operated on from exiting
3286 // and going away unexpectedly (e.g., safepoint synchronization)
3287 
3288 JavaThread* Threads::_thread_list = NULL;
3289 int         Threads::_number_of_threads = 0;
3290 int         Threads::_number_of_non_daemon_threads = 0;
3291 int         Threads::_return_code = 0;
3292 int         Threads::_thread_claim_parity = 0;
3293 size_t      JavaThread::_stack_size_at_create = 0;
3294 #ifdef ASSERT
3295 bool        Threads::_vm_complete = false;
3296 #endif
3297 
3298 // All JavaThreads
3299 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3300 
3301 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3302 void Threads::threads_do(ThreadClosure* tc) {
3303   assert_locked_or_safepoint(Threads_lock);
3304   // ALL_JAVA_THREADS iterates through all JavaThreads
3305   ALL_JAVA_THREADS(p) {
3306     tc->do_thread(p);
3307   }
3308   // Someday we could have a table or list of all non-JavaThreads.
3309   // For now, just manually iterate through them.
3310   tc->do_thread(VMThread::vm_thread());
3311   Universe::heap()->gc_threads_do(tc);
3312   WatcherThread *wt = WatcherThread::watcher_thread();
3313   // Strictly speaking, the following NULL check isn't sufficient to make sure
3314   // the data for WatcherThread is still valid upon being examined. However,
3315   // considering that WatchThread terminates when the VM is on the way to
3316   // exit at safepoint, the chance of the above is extremely small. The right
3317   // way to prevent termination of WatcherThread would be to acquire
3318   // Terminator_lock, but we can't do that without violating the lock rank
3319   // checking in some cases.
3320   if (wt != NULL) {
3321     tc->do_thread(wt);
3322   }
3323 
3324   // If CompilerThreads ever become non-JavaThreads, add them here
3325 }
3326 
3327 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3328   TraceTime timer("Initialize java.lang classes", TraceStartupTime);
3329 
3330   if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3331     create_vm_init_libraries();
3332   }
3333 
3334   initialize_class(vmSymbols::java_lang_String(), CHECK);
3335 
3336   // Inject CompactStrings value after the static initializers for String ran.
3337   java_lang_String::set_compact_strings(CompactStrings);
3338 
3339   // Initialize java_lang.System (needed before creating the thread)
3340   initialize_class(vmSymbols::java_lang_System(), CHECK);
3341   // The VM creates & returns objects of this class. Make sure it's initialized.
3342   initialize_class(vmSymbols::java_lang_Class(), CHECK);
3343   initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3344   Handle thread_group = create_initial_thread_group(CHECK);
3345   Universe::set_main_thread_group(thread_group());
3346   initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3347   oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3348   main_thread->set_threadObj(thread_object);
3349   // Set thread status to running since main thread has
3350   // been started and running.
3351   java_lang_Thread::set_thread_status(thread_object,
3352                                       java_lang_Thread::RUNNABLE);
3353 
3354   // The VM preresolves methods to these classes. Make sure that they get initialized
3355   initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3356   initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3357   call_initializeSystemClass(CHECK);
3358 
3359   // get the Java runtime name after java.lang.System is initialized
3360   JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3361   JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3362 
3363   // an instance of OutOfMemory exception has been allocated earlier
3364   initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3365   initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3366   initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3367   initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3368   initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3369   initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3370   initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3371   initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3372 }
3373 
3374 void Threads::initialize_jsr292_core_classes(TRAPS) {
3375   initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3376   initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3377   initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3378 }
3379 
3380 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3381   extern void JDK_Version_init();
3382 
3383   // Preinitialize version info.
3384   VM_Version::early_initialize();
3385 
3386   // Check version
3387   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3388 
3389   // Initialize the output stream module
3390   ostream_init();
3391 
3392   // Process java launcher properties.
3393   Arguments::process_sun_java_launcher_properties(args);
3394 
3395   // Initialize the os module before using TLS
3396   os::init();
3397 
3398   // Record VM creation timing statistics
3399   TraceVmCreationTime create_vm_timer;
3400   create_vm_timer.start();
3401 
3402   // Initialize system properties.
3403   Arguments::init_system_properties();
3404 
3405   // So that JDK version can be used as a discriminator when parsing arguments
3406   JDK_Version_init();
3407 
3408   // Update/Initialize System properties after JDK version number is known
3409   Arguments::init_version_specific_system_properties();
3410 
3411   // Make sure to initialize log configuration *before* parsing arguments
3412   LogConfiguration::initialize(create_vm_timer.begin_time());
3413 
3414   // Parse arguments
3415   jint parse_result = Arguments::parse(args);
3416   if (parse_result != JNI_OK) return parse_result;
3417 
3418   os::init_before_ergo();
3419 
3420   jint ergo_result = Arguments::apply_ergo();
3421   if (ergo_result != JNI_OK) return ergo_result;
3422 
3423   // Final check of all ranges after ergonomics which may change values.
3424   if (!CommandLineFlagRangeList::check_ranges()) {
3425     return JNI_EINVAL;
3426   }
3427 
3428   // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3429   bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3430   if (!constraint_result) {
3431     return JNI_EINVAL;
3432   }
3433 
3434   if (PauseAtStartup) {
3435     os::pause();
3436   }
3437 
3438   HOTSPOT_VM_INIT_BEGIN();
3439 
3440   // Timing (must come after argument parsing)
3441   TraceTime timer("Create VM", TraceStartupTime);
3442 
3443   // Initialize the os module after parsing the args
3444   jint os_init_2_result = os::init_2();
3445   if (os_init_2_result != JNI_OK) return os_init_2_result;
3446 
3447   jint adjust_after_os_result = Arguments::adjust_after_os();
3448   if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3449 
3450   // Initialize library-based TLS
3451   ThreadLocalStorage::init();
3452 
3453   // Initialize output stream logging
3454   ostream_init_log();
3455 
3456   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3457   // Must be before create_vm_init_agents()
3458   if (Arguments::init_libraries_at_startup()) {
3459     convert_vm_init_libraries_to_agents();
3460   }
3461 
3462   // Launch -agentlib/-agentpath and converted -Xrun agents
3463   if (Arguments::init_agents_at_startup()) {
3464     create_vm_init_agents();
3465   }
3466 
3467   // Initialize Threads state
3468   _thread_list = NULL;
3469   _number_of_threads = 0;
3470   _number_of_non_daemon_threads = 0;
3471 
3472   // Initialize global data structures and create system classes in heap
3473   vm_init_globals();
3474 
3475 #if INCLUDE_JVMCI
3476   if (JVMCICounterSize > 0) {
3477     JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3478     memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3479   } else {
3480     JavaThread::_jvmci_old_thread_counters = NULL;
3481   }
3482 #endif // INCLUDE_JVMCI
3483 
3484   // Attach the main thread to this os thread
3485   JavaThread* main_thread = new JavaThread();
3486   main_thread->set_thread_state(_thread_in_vm);
3487   main_thread->initialize_thread_current();
3488   // must do this before set_active_handles
3489   main_thread->record_stack_base_and_size();
3490   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3491 
3492   if (!main_thread->set_as_starting_thread()) {
3493     vm_shutdown_during_initialization(
3494                                       "Failed necessary internal allocation. Out of swap space");
3495     delete main_thread;
3496     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3497     return JNI_ENOMEM;
3498   }
3499 
3500   // Enable guard page *after* os::create_main_thread(), otherwise it would
3501   // crash Linux VM, see notes in os_linux.cpp.
3502   main_thread->create_stack_guard_pages();
3503 
3504   // Initialize Java-Level synchronization subsystem
3505   ObjectMonitor::Initialize();
3506 
3507   // Initialize global modules
3508   jint status = init_globals();
3509   if (status != JNI_OK) {
3510     delete main_thread;
3511     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3512     return status;
3513   }
3514 
3515   // Should be done after the heap is fully created
3516   main_thread->cache_global_variables();
3517 
3518   HandleMark hm;
3519 
3520   { MutexLocker mu(Threads_lock);
3521     Threads::add(main_thread);
3522   }
3523 
3524   // Any JVMTI raw monitors entered in onload will transition into
3525   // real raw monitor. VM is setup enough here for raw monitor enter.
3526   JvmtiExport::transition_pending_onload_raw_monitors();
3527 
3528   // Create the VMThread
3529   { TraceTime timer("Start VMThread", TraceStartupTime);
3530     VMThread::create();
3531     Thread* vmthread = VMThread::vm_thread();
3532 
3533     if (!os::create_thread(vmthread, os::vm_thread)) {
3534       vm_exit_during_initialization("Cannot create VM thread. "
3535                                     "Out of system resources.");
3536     }
3537 
3538     // Wait for the VM thread to become ready, and VMThread::run to initialize
3539     // Monitors can have spurious returns, must always check another state flag
3540     {
3541       MutexLocker ml(Notify_lock);
3542       os::start_thread(vmthread);
3543       while (vmthread->active_handles() == NULL) {
3544         Notify_lock->wait();
3545       }
3546     }
3547   }
3548 
3549   assert(Universe::is_fully_initialized(), "not initialized");
3550   if (VerifyDuringStartup) {
3551     // Make sure we're starting with a clean slate.
3552     VM_Verify verify_op;
3553     VMThread::execute(&verify_op);
3554   }
3555 
3556   Thread* THREAD = Thread::current();
3557 
3558   // At this point, the Universe is initialized, but we have not executed
3559   // any byte code.  Now is a good time (the only time) to dump out the
3560   // internal state of the JVM for sharing.
3561   if (DumpSharedSpaces) {
3562     MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3563     ShouldNotReachHere();
3564   }
3565 
3566   // Always call even when there are not JVMTI environments yet, since environments
3567   // may be attached late and JVMTI must track phases of VM execution
3568   JvmtiExport::enter_start_phase();
3569 
3570   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3571   JvmtiExport::post_vm_start();
3572 
3573   initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3574 
3575   // We need this for ClassDataSharing - the initial vm.info property is set
3576   // with the default value of CDS "sharing" which may be reset through
3577   // command line options.
3578   reset_vm_info_property(CHECK_JNI_ERR);
3579 
3580   quicken_jni_functions();
3581 
3582   // Must be run after init_ft which initializes ft_enabled
3583   if (TRACE_INITIALIZE() != JNI_OK) {
3584     vm_exit_during_initialization("Failed to initialize tracing backend");
3585   }
3586 
3587   // Set flag that basic initialization has completed. Used by exceptions and various
3588   // debug stuff, that does not work until all basic classes have been initialized.
3589   set_init_completed();
3590 
3591   LogConfiguration::post_initialize();
3592   Metaspace::post_initialize();
3593 
3594   HOTSPOT_VM_INIT_END();
3595 
3596   // record VM initialization completion time
3597 #if INCLUDE_MANAGEMENT
3598   Management::record_vm_init_completed();
3599 #endif // INCLUDE_MANAGEMENT
3600 
3601   // Compute system loader. Note that this has to occur after set_init_completed, since
3602   // valid exceptions may be thrown in the process.
3603   // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
3604   // set_init_completed has just been called, causing exceptions not to be shortcut
3605   // anymore. We call vm_exit_during_initialization directly instead.
3606   SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR));
3607 
3608 #if INCLUDE_ALL_GCS
3609   // Support for ConcurrentMarkSweep. This should be cleaned up
3610   // and better encapsulated. The ugly nested if test would go away
3611   // once things are properly refactored. XXX YSR
3612   if (UseConcMarkSweepGC || UseG1GC) {
3613     if (UseConcMarkSweepGC) {
3614       ConcurrentMarkSweepThread::makeSurrogateLockerThread(CHECK_JNI_ERR);
3615     } else {
3616       ConcurrentMarkThread::makeSurrogateLockerThread(CHECK_JNI_ERR);
3617     }
3618   }
3619 #endif // INCLUDE_ALL_GCS
3620 
3621   // Always call even when there are not JVMTI environments yet, since environments
3622   // may be attached late and JVMTI must track phases of VM execution
3623   JvmtiExport::enter_live_phase();
3624 
3625   // Signal Dispatcher needs to be started before VMInit event is posted
3626   os::signal_init();
3627 
3628   // Start Attach Listener if +StartAttachListener or it can't be started lazily
3629   if (!DisableAttachMechanism) {
3630     AttachListener::vm_start();
3631     if (StartAttachListener || AttachListener::init_at_startup()) {
3632       AttachListener::init();
3633     }
3634   }
3635 
3636   // Launch -Xrun agents
3637   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3638   // back-end can launch with -Xdebug -Xrunjdwp.
3639   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3640     create_vm_init_libraries();
3641   }
3642 
3643   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3644   JvmtiExport::post_vm_initialized();
3645 
3646   if (TRACE_START() != JNI_OK) {
3647     vm_exit_during_initialization("Failed to start tracing backend.");
3648   }
3649 
3650   if (CleanChunkPoolAsync) {
3651     Chunk::start_chunk_pool_cleaner_task();
3652   }
3653 
3654 #if INCLUDE_JVMCI
3655   if (EnableJVMCI) {
3656     const char* jvmciCompiler = Arguments::PropertyList_get_value(Arguments::system_properties(), "jvmci.compiler");
3657     if (jvmciCompiler != NULL) {
3658       JVMCIRuntime::save_compiler(jvmciCompiler);
3659     }
3660     JVMCIRuntime::maybe_print_flags(CHECK_JNI_ERR);
3661   }
3662 #endif // INCLUDE_JVMCI
3663 
3664   // initialize compiler(s)
3665 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI
3666   CompileBroker::compilation_init(CHECK_JNI_ERR);
3667 #endif
3668 
3669   // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3670   // It is done after compilers are initialized, because otherwise compilations of
3671   // signature polymorphic MH intrinsics can be missed
3672   // (see SystemDictionary::find_method_handle_intrinsic).
3673   initialize_jsr292_core_classes(CHECK_JNI_ERR);
3674 
3675 #if INCLUDE_MANAGEMENT
3676   Management::initialize(THREAD);
3677 
3678   if (HAS_PENDING_EXCEPTION) {
3679     // management agent fails to start possibly due to
3680     // configuration problem and is responsible for printing
3681     // stack trace if appropriate. Simply exit VM.
3682     vm_exit(1);
3683   }
3684 #endif // INCLUDE_MANAGEMENT
3685 
3686   if (Arguments::has_profile())       FlatProfiler::engage(main_thread, true);
3687   if (MemProfiling)                   MemProfiler::engage();
3688   StatSampler::engage();
3689   if (CheckJNICalls)                  JniPeriodicChecker::engage();
3690 
3691   BiasedLocking::init();
3692 
3693 #if INCLUDE_RTM_OPT
3694   RTMLockingCounters::init();
3695 #endif
3696 
3697   if (JDK_Version::current().post_vm_init_hook_enabled()) {
3698     call_postVMInitHook(THREAD);
3699     // The Java side of PostVMInitHook.run must deal with all
3700     // exceptions and provide means of diagnosis.
3701     if (HAS_PENDING_EXCEPTION) {
3702       CLEAR_PENDING_EXCEPTION;
3703     }
3704   }
3705 
3706   {
3707     MutexLocker ml(PeriodicTask_lock);
3708     // Make sure the WatcherThread can be started by WatcherThread::start()
3709     // or by dynamic enrollment.
3710     WatcherThread::make_startable();
3711     // Start up the WatcherThread if there are any periodic tasks
3712     // NOTE:  All PeriodicTasks should be registered by now. If they
3713     //   aren't, late joiners might appear to start slowly (we might
3714     //   take a while to process their first tick).
3715     if (PeriodicTask::num_tasks() > 0) {
3716       WatcherThread::start();
3717     }
3718   }
3719 
3720   CodeCacheExtensions::complete_step(CodeCacheExtensionsSteps::CreateVM);
3721 
3722   create_vm_timer.end();
3723 #ifdef ASSERT
3724   _vm_complete = true;
3725 #endif
3726   return JNI_OK;
3727 }
3728 
3729 // type for the Agent_OnLoad and JVM_OnLoad entry points
3730 extern "C" {
3731   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3732 }
3733 // Find a command line agent library and return its entry point for
3734 //         -agentlib:  -agentpath:   -Xrun
3735 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3736 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3737                                     const char *on_load_symbols[],
3738                                     size_t num_symbol_entries) {
3739   OnLoadEntry_t on_load_entry = NULL;
3740   void *library = NULL;
3741 
3742   if (!agent->valid()) {
3743     char buffer[JVM_MAXPATHLEN];
3744     char ebuf[1024] = "";
3745     const char *name = agent->name();
3746     const char *msg = "Could not find agent library ";
3747 
3748     // First check to see if agent is statically linked into executable
3749     if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3750       library = agent->os_lib();
3751     } else if (agent->is_absolute_path()) {
3752       library = os::dll_load(name, ebuf, sizeof ebuf);
3753       if (library == NULL) {
3754         const char *sub_msg = " in absolute path, with error: ";
3755         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3756         char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3757         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3758         // If we can't find the agent, exit.
3759         vm_exit_during_initialization(buf, NULL);
3760         FREE_C_HEAP_ARRAY(char, buf);
3761       }
3762     } else {
3763       // Try to load the agent from the standard dll directory
3764       if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3765                              name)) {
3766         library = os::dll_load(buffer, ebuf, sizeof ebuf);
3767       }
3768       if (library == NULL) { // Try the local directory
3769         char ns[1] = {0};
3770         if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3771           library = os::dll_load(buffer, ebuf, sizeof ebuf);
3772         }
3773         if (library == NULL) {
3774           const char *sub_msg = " on the library path, with error: ";
3775           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3776           char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3777           jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3778           // If we can't find the agent, exit.
3779           vm_exit_during_initialization(buf, NULL);
3780           FREE_C_HEAP_ARRAY(char, buf);
3781         }
3782       }
3783     }
3784     agent->set_os_lib(library);
3785     agent->set_valid();
3786   }
3787 
3788   // Find the OnLoad function.
3789   on_load_entry =
3790     CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3791                                                           false,
3792                                                           on_load_symbols,
3793                                                           num_symbol_entries));
3794   return on_load_entry;
3795 }
3796 
3797 // Find the JVM_OnLoad entry point
3798 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3799   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3800   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3801 }
3802 
3803 // Find the Agent_OnLoad entry point
3804 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3805   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3806   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3807 }
3808 
3809 // For backwards compatibility with -Xrun
3810 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3811 // treated like -agentpath:
3812 // Must be called before agent libraries are created
3813 void Threads::convert_vm_init_libraries_to_agents() {
3814   AgentLibrary* agent;
3815   AgentLibrary* next;
3816 
3817   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3818     next = agent->next();  // cache the next agent now as this agent may get moved off this list
3819     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3820 
3821     // If there is an JVM_OnLoad function it will get called later,
3822     // otherwise see if there is an Agent_OnLoad
3823     if (on_load_entry == NULL) {
3824       on_load_entry = lookup_agent_on_load(agent);
3825       if (on_load_entry != NULL) {
3826         // switch it to the agent list -- so that Agent_OnLoad will be called,
3827         // JVM_OnLoad won't be attempted and Agent_OnUnload will
3828         Arguments::convert_library_to_agent(agent);
3829       } else {
3830         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3831       }
3832     }
3833   }
3834 }
3835 
3836 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
3837 // Invokes Agent_OnLoad
3838 // Called very early -- before JavaThreads exist
3839 void Threads::create_vm_init_agents() {
3840   extern struct JavaVM_ main_vm;
3841   AgentLibrary* agent;
3842 
3843   JvmtiExport::enter_onload_phase();
3844 
3845   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3846     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
3847 
3848     if (on_load_entry != NULL) {
3849       // Invoke the Agent_OnLoad function
3850       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3851       if (err != JNI_OK) {
3852         vm_exit_during_initialization("agent library failed to init", agent->name());
3853       }
3854     } else {
3855       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3856     }
3857   }
3858   JvmtiExport::enter_primordial_phase();
3859 }
3860 
3861 extern "C" {
3862   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3863 }
3864 
3865 void Threads::shutdown_vm_agents() {
3866   // Send any Agent_OnUnload notifications
3867   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3868   size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
3869   extern struct JavaVM_ main_vm;
3870   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3871 
3872     // Find the Agent_OnUnload function.
3873     Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3874                                                    os::find_agent_function(agent,
3875                                                    false,
3876                                                    on_unload_symbols,
3877                                                    num_symbol_entries));
3878 
3879     // Invoke the Agent_OnUnload function
3880     if (unload_entry != NULL) {
3881       JavaThread* thread = JavaThread::current();
3882       ThreadToNativeFromVM ttn(thread);
3883       HandleMark hm(thread);
3884       (*unload_entry)(&main_vm);
3885     }
3886   }
3887 }
3888 
3889 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
3890 // Invokes JVM_OnLoad
3891 void Threads::create_vm_init_libraries() {
3892   extern struct JavaVM_ main_vm;
3893   AgentLibrary* agent;
3894 
3895   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
3896     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3897 
3898     if (on_load_entry != NULL) {
3899       // Invoke the JVM_OnLoad function
3900       JavaThread* thread = JavaThread::current();
3901       ThreadToNativeFromVM ttn(thread);
3902       HandleMark hm(thread);
3903       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3904       if (err != JNI_OK) {
3905         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
3906       }
3907     } else {
3908       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
3909     }
3910   }
3911 }
3912 
3913 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
3914   assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
3915 
3916   JavaThread* java_thread = NULL;
3917   // Sequential search for now.  Need to do better optimization later.
3918   for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
3919     oop tobj = thread->threadObj();
3920     if (!thread->is_exiting() &&
3921         tobj != NULL &&
3922         java_tid == java_lang_Thread::thread_id(tobj)) {
3923       java_thread = thread;
3924       break;
3925     }
3926   }
3927   return java_thread;
3928 }
3929 
3930 
3931 // Last thread running calls java.lang.Shutdown.shutdown()
3932 void JavaThread::invoke_shutdown_hooks() {
3933   HandleMark hm(this);
3934 
3935   // We could get here with a pending exception, if so clear it now.
3936   if (this->has_pending_exception()) {
3937     this->clear_pending_exception();
3938   }
3939 
3940   EXCEPTION_MARK;
3941   Klass* k =
3942     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
3943                                       THREAD);
3944   if (k != NULL) {
3945     // SystemDictionary::resolve_or_null will return null if there was
3946     // an exception.  If we cannot load the Shutdown class, just don't
3947     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
3948     // and finalizers (if runFinalizersOnExit is set) won't be run.
3949     // Note that if a shutdown hook was registered or runFinalizersOnExit
3950     // was called, the Shutdown class would have already been loaded
3951     // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
3952     instanceKlassHandle shutdown_klass (THREAD, k);
3953     JavaValue result(T_VOID);
3954     JavaCalls::call_static(&result,
3955                            shutdown_klass,
3956                            vmSymbols::shutdown_method_name(),
3957                            vmSymbols::void_method_signature(),
3958                            THREAD);
3959   }
3960   CLEAR_PENDING_EXCEPTION;
3961 }
3962 
3963 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
3964 // the program falls off the end of main(). Another VM exit path is through
3965 // vm_exit() when the program calls System.exit() to return a value or when
3966 // there is a serious error in VM. The two shutdown paths are not exactly
3967 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
3968 // and VM_Exit op at VM level.
3969 //
3970 // Shutdown sequence:
3971 //   + Shutdown native memory tracking if it is on
3972 //   + Wait until we are the last non-daemon thread to execute
3973 //     <-- every thing is still working at this moment -->
3974 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
3975 //        shutdown hooks, run finalizers if finalization-on-exit
3976 //   + Call before_exit(), prepare for VM exit
3977 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
3978 //        currently the only user of this mechanism is File.deleteOnExit())
3979 //      > stop flat profiler, StatSampler, watcher thread, CMS threads,
3980 //        post thread end and vm death events to JVMTI,
3981 //        stop signal thread
3982 //   + Call JavaThread::exit(), it will:
3983 //      > release JNI handle blocks, remove stack guard pages
3984 //      > remove this thread from Threads list
3985 //     <-- no more Java code from this thread after this point -->
3986 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
3987 //     the compiler threads at safepoint
3988 //     <-- do not use anything that could get blocked by Safepoint -->
3989 //   + Disable tracing at JNI/JVM barriers
3990 //   + Set _vm_exited flag for threads that are still running native code
3991 //   + Delete this thread
3992 //   + Call exit_globals()
3993 //      > deletes tty
3994 //      > deletes PerfMemory resources
3995 //   + Return to caller
3996 
3997 bool Threads::destroy_vm() {
3998   JavaThread* thread = JavaThread::current();
3999 
4000 #ifdef ASSERT
4001   _vm_complete = false;
4002 #endif
4003   // Wait until we are the last non-daemon thread to execute
4004   { MutexLocker nu(Threads_lock);
4005     while (Threads::number_of_non_daemon_threads() > 1)
4006       // This wait should make safepoint checks, wait without a timeout,
4007       // and wait as a suspend-equivalent condition.
4008       //
4009       // Note: If the FlatProfiler is running and this thread is waiting
4010       // for another non-daemon thread to finish, then the FlatProfiler
4011       // is waiting for the external suspend request on this thread to
4012       // complete. wait_for_ext_suspend_completion() will eventually
4013       // timeout, but that takes time. Making this wait a suspend-
4014       // equivalent condition solves that timeout problem.
4015       //
4016       Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4017                          Mutex::_as_suspend_equivalent_flag);
4018   }
4019 
4020   // Hang forever on exit if we are reporting an error.
4021   if (ShowMessageBoxOnError && is_error_reported()) {
4022     os::infinite_sleep();
4023   }
4024   os::wait_for_keypress_at_exit();
4025 
4026   // run Java level shutdown hooks
4027   thread->invoke_shutdown_hooks();
4028 
4029   before_exit(thread);
4030 
4031   thread->exit(true);
4032 
4033   // Stop VM thread.
4034   {
4035     // 4945125 The vm thread comes to a safepoint during exit.
4036     // GC vm_operations can get caught at the safepoint, and the
4037     // heap is unparseable if they are caught. Grab the Heap_lock
4038     // to prevent this. The GC vm_operations will not be able to
4039     // queue until after the vm thread is dead. After this point,
4040     // we'll never emerge out of the safepoint before the VM exits.
4041 
4042     MutexLocker ml(Heap_lock);
4043 
4044     VMThread::wait_for_vm_thread_exit();
4045     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4046     VMThread::destroy();
4047   }
4048 
4049   // clean up ideal graph printers
4050 #if defined(COMPILER2) && !defined(PRODUCT)
4051   IdealGraphPrinter::clean_up();
4052 #endif
4053 
4054   // Now, all Java threads are gone except daemon threads. Daemon threads
4055   // running Java code or in VM are stopped by the Safepoint. However,
4056   // daemon threads executing native code are still running.  But they
4057   // will be stopped at native=>Java/VM barriers. Note that we can't
4058   // simply kill or suspend them, as it is inherently deadlock-prone.
4059 
4060   VM_Exit::set_vm_exited();
4061 
4062   notify_vm_shutdown();
4063 
4064   delete thread;
4065 
4066 #if INCLUDE_JVMCI
4067   if (JVMCICounterSize > 0) {
4068     FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4069   }
4070 #endif
4071 
4072   // exit_globals() will delete tty
4073   exit_globals();
4074 
4075   LogConfiguration::finalize();
4076 
4077   return true;
4078 }
4079 
4080 
4081 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4082   if (version == JNI_VERSION_1_1) return JNI_TRUE;
4083   return is_supported_jni_version(version);
4084 }
4085 
4086 
4087 jboolean Threads::is_supported_jni_version(jint version) {
4088   if (version == JNI_VERSION_1_2) return JNI_TRUE;
4089   if (version == JNI_VERSION_1_4) return JNI_TRUE;
4090   if (version == JNI_VERSION_1_6) return JNI_TRUE;
4091   if (version == JNI_VERSION_1_8) return JNI_TRUE;
4092   return JNI_FALSE;
4093 }
4094 
4095 
4096 void Threads::add(JavaThread* p, bool force_daemon) {
4097   // The threads lock must be owned at this point
4098   assert_locked_or_safepoint(Threads_lock);
4099 
4100   // See the comment for this method in thread.hpp for its purpose and
4101   // why it is called here.
4102   p->initialize_queues();
4103   p->set_next(_thread_list);
4104   _thread_list = p;
4105   _number_of_threads++;
4106   oop threadObj = p->threadObj();
4107   bool daemon = true;
4108   // Bootstrapping problem: threadObj can be null for initial
4109   // JavaThread (or for threads attached via JNI)
4110   if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4111     _number_of_non_daemon_threads++;
4112     daemon = false;
4113   }
4114 
4115   ThreadService::add_thread(p, daemon);
4116 
4117   // Possible GC point.
4118   Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4119 }
4120 
4121 void Threads::remove(JavaThread* p) {
4122   // Extra scope needed for Thread_lock, so we can check
4123   // that we do not remove thread without safepoint code notice
4124   { MutexLocker ml(Threads_lock);
4125 
4126     assert(includes(p), "p must be present");
4127 
4128     JavaThread* current = _thread_list;
4129     JavaThread* prev    = NULL;
4130 
4131     while (current != p) {
4132       prev    = current;
4133       current = current->next();
4134     }
4135 
4136     if (prev) {
4137       prev->set_next(current->next());
4138     } else {
4139       _thread_list = p->next();
4140     }
4141     _number_of_threads--;
4142     oop threadObj = p->threadObj();
4143     bool daemon = true;
4144     if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4145       _number_of_non_daemon_threads--;
4146       daemon = false;
4147 
4148       // Only one thread left, do a notify on the Threads_lock so a thread waiting
4149       // on destroy_vm will wake up.
4150       if (number_of_non_daemon_threads() == 1) {
4151         Threads_lock->notify_all();
4152       }
4153     }
4154     ThreadService::remove_thread(p, daemon);
4155 
4156     // Make sure that safepoint code disregard this thread. This is needed since
4157     // the thread might mess around with locks after this point. This can cause it
4158     // to do callbacks into the safepoint code. However, the safepoint code is not aware
4159     // of this thread since it is removed from the queue.
4160     p->set_terminated_value();
4161   } // unlock Threads_lock
4162 
4163   // Since Events::log uses a lock, we grab it outside the Threads_lock
4164   Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4165 }
4166 
4167 // Threads_lock must be held when this is called (or must be called during a safepoint)
4168 bool Threads::includes(JavaThread* p) {
4169   assert(Threads_lock->is_locked(), "sanity check");
4170   ALL_JAVA_THREADS(q) {
4171     if (q == p) {
4172       return true;
4173     }
4174   }
4175   return false;
4176 }
4177 
4178 // Operations on the Threads list for GC.  These are not explicitly locked,
4179 // but the garbage collector must provide a safe context for them to run.
4180 // In particular, these things should never be called when the Threads_lock
4181 // is held by some other thread. (Note: the Safepoint abstraction also
4182 // uses the Threads_lock to guarantee this property. It also makes sure that
4183 // all threads gets blocked when exiting or starting).
4184 
4185 void Threads::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
4186   ALL_JAVA_THREADS(p) {
4187     p->oops_do(f, cld_f, cf);
4188   }
4189   VMThread::vm_thread()->oops_do(f, cld_f, cf);
4190 }
4191 
4192 void Threads::change_thread_claim_parity() {
4193   // Set the new claim parity.
4194   assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4195          "Not in range.");
4196   _thread_claim_parity++;
4197   if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4198   assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4199          "Not in range.");
4200 }
4201 
4202 #ifdef ASSERT
4203 void Threads::assert_all_threads_claimed() {
4204   ALL_JAVA_THREADS(p) {
4205     const int thread_parity = p->oops_do_parity();
4206     assert((thread_parity == _thread_claim_parity),
4207            "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4208   }
4209 }
4210 #endif // ASSERT
4211 
4212 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
4213   int cp = Threads::thread_claim_parity();
4214   ALL_JAVA_THREADS(p) {
4215     if (p->claim_oops_do(is_par, cp)) {
4216       p->oops_do(f, cld_f, cf);
4217     }
4218   }
4219   VMThread* vmt = VMThread::vm_thread();
4220   if (vmt->claim_oops_do(is_par, cp)) {
4221     vmt->oops_do(f, cld_f, cf);
4222   }
4223 }
4224 
4225 #if INCLUDE_ALL_GCS
4226 // Used by ParallelScavenge
4227 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4228   ALL_JAVA_THREADS(p) {
4229     q->enqueue(new ThreadRootsTask(p));
4230   }
4231   q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4232 }
4233 
4234 // Used by Parallel Old
4235 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4236   ALL_JAVA_THREADS(p) {
4237     q->enqueue(new ThreadRootsMarkingTask(p));
4238   }
4239   q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4240 }
4241 #endif // INCLUDE_ALL_GCS
4242 
4243 void Threads::nmethods_do(CodeBlobClosure* cf) {
4244   ALL_JAVA_THREADS(p) {
4245     p->nmethods_do(cf);
4246   }
4247   VMThread::vm_thread()->nmethods_do(cf);
4248 }
4249 
4250 void Threads::metadata_do(void f(Metadata*)) {
4251   ALL_JAVA_THREADS(p) {
4252     p->metadata_do(f);
4253   }
4254 }
4255 
4256 class ThreadHandlesClosure : public ThreadClosure {
4257   void (*_f)(Metadata*);
4258  public:
4259   ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4260   virtual void do_thread(Thread* thread) {
4261     thread->metadata_handles_do(_f);
4262   }
4263 };
4264 
4265 void Threads::metadata_handles_do(void f(Metadata*)) {
4266   // Only walk the Handles in Thread.
4267   ThreadHandlesClosure handles_closure(f);
4268   threads_do(&handles_closure);
4269 }
4270 
4271 void Threads::deoptimized_wrt_marked_nmethods() {
4272   ALL_JAVA_THREADS(p) {
4273     p->deoptimized_wrt_marked_nmethods();
4274   }
4275 }
4276 
4277 
4278 // Get count Java threads that are waiting to enter the specified monitor.
4279 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4280                                                          address monitor,
4281                                                          bool doLock) {
4282   assert(doLock || SafepointSynchronize::is_at_safepoint(),
4283          "must grab Threads_lock or be at safepoint");
4284   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4285 
4286   int i = 0;
4287   {
4288     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4289     ALL_JAVA_THREADS(p) {
4290       if (!p->can_call_java()) continue;
4291 
4292       address pending = (address)p->current_pending_monitor();
4293       if (pending == monitor) {             // found a match
4294         if (i < count) result->append(p);   // save the first count matches
4295         i++;
4296       }
4297     }
4298   }
4299   return result;
4300 }
4301 
4302 
4303 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4304                                                       bool doLock) {
4305   assert(doLock ||
4306          Threads_lock->owned_by_self() ||
4307          SafepointSynchronize::is_at_safepoint(),
4308          "must grab Threads_lock or be at safepoint");
4309 
4310   // NULL owner means not locked so we can skip the search
4311   if (owner == NULL) return NULL;
4312 
4313   {
4314     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4315     ALL_JAVA_THREADS(p) {
4316       // first, see if owner is the address of a Java thread
4317       if (owner == (address)p) return p;
4318     }
4319   }
4320   // Cannot assert on lack of success here since this function may be
4321   // used by code that is trying to report useful problem information
4322   // like deadlock detection.
4323   if (UseHeavyMonitors) return NULL;
4324 
4325   // If we didn't find a matching Java thread and we didn't force use of
4326   // heavyweight monitors, then the owner is the stack address of the
4327   // Lock Word in the owning Java thread's stack.
4328   //
4329   JavaThread* the_owner = NULL;
4330   {
4331     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4332     ALL_JAVA_THREADS(q) {
4333       if (q->is_lock_owned(owner)) {
4334         the_owner = q;
4335         break;
4336       }
4337     }
4338   }
4339   // cannot assert on lack of success here; see above comment
4340   return the_owner;
4341 }
4342 
4343 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4344 void Threads::print_on(outputStream* st, bool print_stacks,
4345                        bool internal_format, bool print_concurrent_locks) {
4346   char buf[32];
4347   st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4348 
4349   st->print_cr("Full thread dump %s (%s %s):",
4350                Abstract_VM_Version::vm_name(),
4351                Abstract_VM_Version::vm_release(),
4352                Abstract_VM_Version::vm_info_string());
4353   st->cr();
4354 
4355 #if INCLUDE_SERVICES
4356   // Dump concurrent locks
4357   ConcurrentLocksDump concurrent_locks;
4358   if (print_concurrent_locks) {
4359     concurrent_locks.dump_at_safepoint();
4360   }
4361 #endif // INCLUDE_SERVICES
4362 
4363   ALL_JAVA_THREADS(p) {
4364     ResourceMark rm;
4365     p->print_on(st);
4366     if (print_stacks) {
4367       if (internal_format) {
4368         p->trace_stack();
4369       } else {
4370         p->print_stack_on(st);
4371       }
4372     }
4373     st->cr();
4374 #if INCLUDE_SERVICES
4375     if (print_concurrent_locks) {
4376       concurrent_locks.print_locks_on(p, st);
4377     }
4378 #endif // INCLUDE_SERVICES
4379   }
4380 
4381   VMThread::vm_thread()->print_on(st);
4382   st->cr();
4383   Universe::heap()->print_gc_threads_on(st);
4384   WatcherThread* wt = WatcherThread::watcher_thread();
4385   if (wt != NULL) {
4386     wt->print_on(st);
4387     st->cr();
4388   }
4389   CompileBroker::print_compiler_threads_on(st);
4390   st->flush();
4391 }
4392 
4393 // Threads::print_on_error() is called by fatal error handler. It's possible
4394 // that VM is not at safepoint and/or current thread is inside signal handler.
4395 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4396 // memory (even in resource area), it might deadlock the error handler.
4397 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4398                              int buflen) {
4399   bool found_current = false;
4400   st->print_cr("Java Threads: ( => current thread )");
4401   ALL_JAVA_THREADS(thread) {
4402     bool is_current = (current == thread);
4403     found_current = found_current || is_current;
4404 
4405     st->print("%s", is_current ? "=>" : "  ");
4406 
4407     st->print(PTR_FORMAT, p2i(thread));
4408     st->print(" ");
4409     thread->print_on_error(st, buf, buflen);
4410     st->cr();
4411   }
4412   st->cr();
4413 
4414   st->print_cr("Other Threads:");
4415   if (VMThread::vm_thread()) {
4416     bool is_current = (current == VMThread::vm_thread());
4417     found_current = found_current || is_current;
4418     st->print("%s", current == VMThread::vm_thread() ? "=>" : "  ");
4419 
4420     st->print(PTR_FORMAT, p2i(VMThread::vm_thread()));
4421     st->print(" ");
4422     VMThread::vm_thread()->print_on_error(st, buf, buflen);
4423     st->cr();
4424   }
4425   WatcherThread* wt = WatcherThread::watcher_thread();
4426   if (wt != NULL) {
4427     bool is_current = (current == wt);
4428     found_current = found_current || is_current;
4429     st->print("%s", is_current ? "=>" : "  ");
4430 
4431     st->print(PTR_FORMAT, p2i(wt));
4432     st->print(" ");
4433     wt->print_on_error(st, buf, buflen);
4434     st->cr();
4435   }
4436   if (!found_current) {
4437     st->cr();
4438     st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4439     current->print_on_error(st, buf, buflen);
4440     st->cr();
4441   }
4442 }
4443 
4444 // Internal SpinLock and Mutex
4445 // Based on ParkEvent
4446 
4447 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4448 //
4449 // We employ SpinLocks _only for low-contention, fixed-length
4450 // short-duration critical sections where we're concerned
4451 // about native mutex_t or HotSpot Mutex:: latency.
4452 // The mux construct provides a spin-then-block mutual exclusion
4453 // mechanism.
4454 //
4455 // Testing has shown that contention on the ListLock guarding gFreeList
4456 // is common.  If we implement ListLock as a simple SpinLock it's common
4457 // for the JVM to devolve to yielding with little progress.  This is true
4458 // despite the fact that the critical sections protected by ListLock are
4459 // extremely short.
4460 //
4461 // TODO-FIXME: ListLock should be of type SpinLock.
4462 // We should make this a 1st-class type, integrated into the lock
4463 // hierarchy as leaf-locks.  Critically, the SpinLock structure
4464 // should have sufficient padding to avoid false-sharing and excessive
4465 // cache-coherency traffic.
4466 
4467 
4468 typedef volatile int SpinLockT;
4469 
4470 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4471   if (Atomic::cmpxchg (1, adr, 0) == 0) {
4472     return;   // normal fast-path return
4473   }
4474 
4475   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4476   TEVENT(SpinAcquire - ctx);
4477   int ctr = 0;
4478   int Yields = 0;
4479   for (;;) {
4480     while (*adr != 0) {
4481       ++ctr;
4482       if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4483         if (Yields > 5) {
4484           os::naked_short_sleep(1);
4485         } else {
4486           os::naked_yield();
4487           ++Yields;
4488         }
4489       } else {
4490         SpinPause();
4491       }
4492     }
4493     if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4494   }
4495 }
4496 
4497 void Thread::SpinRelease(volatile int * adr) {
4498   assert(*adr != 0, "invariant");
4499   OrderAccess::fence();      // guarantee at least release consistency.
4500   // Roach-motel semantics.
4501   // It's safe if subsequent LDs and STs float "up" into the critical section,
4502   // but prior LDs and STs within the critical section can't be allowed
4503   // to reorder or float past the ST that releases the lock.
4504   // Loads and stores in the critical section - which appear in program
4505   // order before the store that releases the lock - must also appear
4506   // before the store that releases the lock in memory visibility order.
4507   // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4508   // the ST of 0 into the lock-word which releases the lock, so fence
4509   // more than covers this on all platforms.
4510   *adr = 0;
4511 }
4512 
4513 // muxAcquire and muxRelease:
4514 //
4515 // *  muxAcquire and muxRelease support a single-word lock-word construct.
4516 //    The LSB of the word is set IFF the lock is held.
4517 //    The remainder of the word points to the head of a singly-linked list
4518 //    of threads blocked on the lock.
4519 //
4520 // *  The current implementation of muxAcquire-muxRelease uses its own
4521 //    dedicated Thread._MuxEvent instance.  If we're interested in
4522 //    minimizing the peak number of extant ParkEvent instances then
4523 //    we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4524 //    as certain invariants were satisfied.  Specifically, care would need
4525 //    to be taken with regards to consuming unpark() "permits".
4526 //    A safe rule of thumb is that a thread would never call muxAcquire()
4527 //    if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4528 //    park().  Otherwise the _ParkEvent park() operation in muxAcquire() could
4529 //    consume an unpark() permit intended for monitorenter, for instance.
4530 //    One way around this would be to widen the restricted-range semaphore
4531 //    implemented in park().  Another alternative would be to provide
4532 //    multiple instances of the PlatformEvent() for each thread.  One
4533 //    instance would be dedicated to muxAcquire-muxRelease, for instance.
4534 //
4535 // *  Usage:
4536 //    -- Only as leaf locks
4537 //    -- for short-term locking only as muxAcquire does not perform
4538 //       thread state transitions.
4539 //
4540 // Alternatives:
4541 // *  We could implement muxAcquire and muxRelease with MCS or CLH locks
4542 //    but with parking or spin-then-park instead of pure spinning.
4543 // *  Use Taura-Oyama-Yonenzawa locks.
4544 // *  It's possible to construct a 1-0 lock if we encode the lockword as
4545 //    (List,LockByte).  Acquire will CAS the full lockword while Release
4546 //    will STB 0 into the LockByte.  The 1-0 scheme admits stranding, so
4547 //    acquiring threads use timers (ParkTimed) to detect and recover from
4548 //    the stranding window.  Thread/Node structures must be aligned on 256-byte
4549 //    boundaries by using placement-new.
4550 // *  Augment MCS with advisory back-link fields maintained with CAS().
4551 //    Pictorially:  LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4552 //    The validity of the backlinks must be ratified before we trust the value.
4553 //    If the backlinks are invalid the exiting thread must back-track through the
4554 //    the forward links, which are always trustworthy.
4555 // *  Add a successor indication.  The LockWord is currently encoded as
4556 //    (List, LOCKBIT:1).  We could also add a SUCCBIT or an explicit _succ variable
4557 //    to provide the usual futile-wakeup optimization.
4558 //    See RTStt for details.
4559 // *  Consider schedctl.sc_nopreempt to cover the critical section.
4560 //
4561 
4562 
4563 typedef volatile intptr_t MutexT;      // Mux Lock-word
4564 enum MuxBits { LOCKBIT = 1 };
4565 
4566 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4567   intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4568   if (w == 0) return;
4569   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4570     return;
4571   }
4572 
4573   TEVENT(muxAcquire - Contention);
4574   ParkEvent * const Self = Thread::current()->_MuxEvent;
4575   assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4576   for (;;) {
4577     int its = (os::is_MP() ? 100 : 0) + 1;
4578 
4579     // Optional spin phase: spin-then-park strategy
4580     while (--its >= 0) {
4581       w = *Lock;
4582       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4583         return;
4584       }
4585     }
4586 
4587     Self->reset();
4588     Self->OnList = intptr_t(Lock);
4589     // The following fence() isn't _strictly necessary as the subsequent
4590     // CAS() both serializes execution and ratifies the fetched *Lock value.
4591     OrderAccess::fence();
4592     for (;;) {
4593       w = *Lock;
4594       if ((w & LOCKBIT) == 0) {
4595         if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4596           Self->OnList = 0;   // hygiene - allows stronger asserts
4597           return;
4598         }
4599         continue;      // Interference -- *Lock changed -- Just retry
4600       }
4601       assert(w & LOCKBIT, "invariant");
4602       Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4603       if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4604     }
4605 
4606     while (Self->OnList != 0) {
4607       Self->park();
4608     }
4609   }
4610 }
4611 
4612 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4613   intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4614   if (w == 0) return;
4615   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4616     return;
4617   }
4618 
4619   TEVENT(muxAcquire - Contention);
4620   ParkEvent * ReleaseAfter = NULL;
4621   if (ev == NULL) {
4622     ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4623   }
4624   assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4625   for (;;) {
4626     guarantee(ev->OnList == 0, "invariant");
4627     int its = (os::is_MP() ? 100 : 0) + 1;
4628 
4629     // Optional spin phase: spin-then-park strategy
4630     while (--its >= 0) {
4631       w = *Lock;
4632       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4633         if (ReleaseAfter != NULL) {
4634           ParkEvent::Release(ReleaseAfter);
4635         }
4636         return;
4637       }
4638     }
4639 
4640     ev->reset();
4641     ev->OnList = intptr_t(Lock);
4642     // The following fence() isn't _strictly necessary as the subsequent
4643     // CAS() both serializes execution and ratifies the fetched *Lock value.
4644     OrderAccess::fence();
4645     for (;;) {
4646       w = *Lock;
4647       if ((w & LOCKBIT) == 0) {
4648         if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4649           ev->OnList = 0;
4650           // We call ::Release while holding the outer lock, thus
4651           // artificially lengthening the critical section.
4652           // Consider deferring the ::Release() until the subsequent unlock(),
4653           // after we've dropped the outer lock.
4654           if (ReleaseAfter != NULL) {
4655             ParkEvent::Release(ReleaseAfter);
4656           }
4657           return;
4658         }
4659         continue;      // Interference -- *Lock changed -- Just retry
4660       }
4661       assert(w & LOCKBIT, "invariant");
4662       ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4663       if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4664     }
4665 
4666     while (ev->OnList != 0) {
4667       ev->park();
4668     }
4669   }
4670 }
4671 
4672 // Release() must extract a successor from the list and then wake that thread.
4673 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4674 // similar to that used by ParkEvent::Allocate() and ::Release().  DMR-based
4675 // Release() would :
4676 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4677 // (B) Extract a successor from the private list "in-hand"
4678 // (C) attempt to CAS() the residual back into *Lock over null.
4679 //     If there were any newly arrived threads and the CAS() would fail.
4680 //     In that case Release() would detach the RATs, re-merge the list in-hand
4681 //     with the RATs and repeat as needed.  Alternately, Release() might
4682 //     detach and extract a successor, but then pass the residual list to the wakee.
4683 //     The wakee would be responsible for reattaching and remerging before it
4684 //     competed for the lock.
4685 //
4686 // Both "pop" and DMR are immune from ABA corruption -- there can be
4687 // multiple concurrent pushers, but only one popper or detacher.
4688 // This implementation pops from the head of the list.  This is unfair,
4689 // but tends to provide excellent throughput as hot threads remain hot.
4690 // (We wake recently run threads first).
4691 //
4692 // All paths through muxRelease() will execute a CAS.
4693 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4694 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4695 // executed within the critical section are complete and globally visible before the
4696 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4697 void Thread::muxRelease(volatile intptr_t * Lock)  {
4698   for (;;) {
4699     const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4700     assert(w & LOCKBIT, "invariant");
4701     if (w == LOCKBIT) return;
4702     ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4703     assert(List != NULL, "invariant");
4704     assert(List->OnList == intptr_t(Lock), "invariant");
4705     ParkEvent * const nxt = List->ListNext;
4706     guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4707 
4708     // The following CAS() releases the lock and pops the head element.
4709     // The CAS() also ratifies the previously fetched lock-word value.
4710     if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4711       continue;
4712     }
4713     List->OnList = 0;
4714     OrderAccess::fence();
4715     List->unpark();
4716     return;
4717   }
4718 }
4719 
4720 
4721 void Threads::verify() {
4722   ALL_JAVA_THREADS(p) {
4723     p->verify();
4724   }
4725   VMThread* thread = VMThread::vm_thread();
4726   if (thread != NULL) thread->verify();
4727 }