1 /*
   2  * Copyright (c) 1997, 2016, 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/moduleEntry.hpp"
  29 #include "classfile/systemDictionary.hpp"
  30 #include "classfile/vmSymbols.hpp"
  31 #include "code/codeCache.hpp"
  32 #include "code/codeCacheExtensions.hpp"
  33 #include "code/scopeDesc.hpp"
  34 #include "compiler/compileBroker.hpp"
  35 #include "compiler/compileTask.hpp"
  36 #include "gc/shared/gcId.hpp"
  37 #include "gc/shared/gcLocker.inline.hpp"
  38 #include "gc/shared/referencePendingListLocker.hpp"
  39 #include "gc/shared/workgroup.hpp"
  40 #include "interpreter/interpreter.hpp"
  41 #include "interpreter/linkResolver.hpp"
  42 #include "interpreter/oopMapCache.hpp"
  43 #include "jvmtifiles/jvmtiEnv.hpp"
  44 #include "logging/log.hpp"
  45 #include "logging/logConfiguration.hpp"
  46 #include "memory/metaspaceShared.hpp"
  47 #include "memory/oopFactory.hpp"
  48 #include "memory/resourceArea.hpp"
  49 #include "memory/universe.inline.hpp"
  50 #include "oops/instanceKlass.hpp"
  51 #include "oops/objArrayOop.hpp"
  52 #include "oops/oop.inline.hpp"
  53 #include "oops/symbol.hpp"
  54 #include "oops/verifyOopClosure.hpp"
  55 #include "prims/jvm_misc.hpp"
  56 #include "prims/jvmtiExport.hpp"
  57 #include "prims/jvmtiThreadState.hpp"
  58 #include "prims/privilegedStack.hpp"
  59 #include "runtime/arguments.hpp"
  60 #include "runtime/atomic.inline.hpp"
  61 #include "runtime/biasedLocking.hpp"
  62 #include "runtime/commandLineFlagConstraintList.hpp"
  63 #include "runtime/commandLineFlagRangeList.hpp"
  64 #include "runtime/deoptimization.hpp"
  65 #include "runtime/fprofiler.hpp"
  66 #include "runtime/frame.inline.hpp"
  67 #include "runtime/globals.hpp"
  68 #include "runtime/init.hpp"
  69 #include "runtime/interfaceSupport.hpp"
  70 #include "runtime/java.hpp"
  71 #include "runtime/javaCalls.hpp"
  72 #include "runtime/jniPeriodicChecker.hpp"
  73 #include "runtime/timerTrace.hpp"
  74 #include "runtime/memprofiler.hpp"
  75 #include "runtime/mutexLocker.hpp"
  76 #include "runtime/objectMonitor.hpp"
  77 #include "runtime/orderAccess.inline.hpp"
  78 #include "runtime/osThread.hpp"
  79 #include "runtime/safepoint.hpp"
  80 #include "runtime/sharedRuntime.hpp"
  81 #include "runtime/statSampler.hpp"
  82 #include "runtime/stubRoutines.hpp"
  83 #include "runtime/sweeper.hpp"
  84 #include "runtime/task.hpp"
  85 #include "runtime/thread.inline.hpp"
  86 #include "runtime/threadCritical.hpp"
  87 #include "runtime/vframe.hpp"
  88 #include "runtime/vframeArray.hpp"
  89 #include "runtime/vframe_hp.hpp"
  90 #include "runtime/vmThread.hpp"
  91 #include "runtime/vm_operations.hpp"
  92 #include "runtime/vm_version.hpp"
  93 #include "services/attachListener.hpp"
  94 #include "services/management.hpp"
  95 #include "services/memTracker.hpp"
  96 #include "services/threadService.hpp"
  97 #include "trace/traceMacros.hpp"
  98 #include "trace/tracing.hpp"
  99 #include "utilities/defaultStream.hpp"
 100 #include "utilities/dtrace.hpp"
 101 #include "utilities/events.hpp"
 102 #include "utilities/macros.hpp"
 103 #include "utilities/preserveException.hpp"
 104 #if INCLUDE_ALL_GCS
 105 #include "gc/cms/concurrentMarkSweepThread.hpp"
 106 #include "gc/g1/concurrentMarkThread.inline.hpp"
 107 #include "gc/parallel/pcTasks.hpp"
 108 #endif // INCLUDE_ALL_GCS
 109 #if INCLUDE_JVMCI
 110 #include "jvmci/jvmciCompiler.hpp"
 111 #include "jvmci/jvmciRuntime.hpp"
 112 #endif
 113 #ifdef COMPILER1
 114 #include "c1/c1_Compiler.hpp"
 115 #endif
 116 #ifdef COMPILER2
 117 #include "opto/c2compiler.hpp"
 118 #include "opto/idealGraphPrinter.hpp"
 119 #endif
 120 #if INCLUDE_RTM_OPT
 121 #include "runtime/rtmLocking.hpp"
 122 #endif
 123 
 124 // Initialization after module runtime initialization
 125 void universe_post_module_init();  // must happen after call_initPhase2
 126 
 127 #ifdef DTRACE_ENABLED
 128 
 129 // Only bother with this argument setup if dtrace is available
 130 
 131   #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
 132   #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
 133 
 134   #define DTRACE_THREAD_PROBE(probe, javathread)                           \
 135     {                                                                      \
 136       ResourceMark rm(this);                                               \
 137       int len = 0;                                                         \
 138       const char* name = (javathread)->get_thread_name();                  \
 139       len = strlen(name);                                                  \
 140       HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */               \
 141         (char *) name, len,                                                \
 142         java_lang_Thread::thread_id((javathread)->threadObj()),            \
 143         (uintptr_t) (javathread)->osthread()->thread_id(),                 \
 144         java_lang_Thread::is_daemon((javathread)->threadObj()));           \
 145     }
 146 
 147 #else //  ndef DTRACE_ENABLED
 148 
 149   #define DTRACE_THREAD_PROBE(probe, javathread)
 150 
 151 #endif // ndef DTRACE_ENABLED
 152 
 153 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 154 // Current thread is maintained as a thread-local variable
 155 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
 156 #endif
 157 // Class hierarchy
 158 // - Thread
 159 //   - VMThread
 160 //   - WatcherThread
 161 //   - ConcurrentMarkSweepThread
 162 //   - JavaThread
 163 //     - CompilerThread
 164 
 165 // ======= Thread ========
 166 // Support for forcing alignment of thread objects for biased locking
 167 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
 168   if (UseBiasedLocking) {
 169     const int alignment = markOopDesc::biased_lock_alignment;
 170     size_t aligned_size = size + (alignment - sizeof(intptr_t));
 171     void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
 172                                           : AllocateHeap(aligned_size, flags, CURRENT_PC,
 173                                                          AllocFailStrategy::RETURN_NULL);
 174     void* aligned_addr     = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
 175     assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
 176            ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
 177            "JavaThread alignment code overflowed allocated storage");
 178     if (aligned_addr != real_malloc_addr) {
 179       log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
 180                               p2i(real_malloc_addr),
 181                               p2i(aligned_addr));
 182     }
 183     ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
 184     return aligned_addr;
 185   } else {
 186     return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
 187                        : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
 188   }
 189 }
 190 
 191 void Thread::operator delete(void* p) {
 192   if (UseBiasedLocking) {
 193     void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
 194     FreeHeap(real_malloc_addr);
 195   } else {
 196     FreeHeap(p);
 197   }
 198 }
 199 
 200 
 201 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
 202 // JavaThread
 203 
 204 
 205 Thread::Thread() {
 206   // stack and get_thread
 207   set_stack_base(NULL);
 208   set_stack_size(0);
 209   set_self_raw_id(0);
 210   set_lgrp_id(-1);
 211   DEBUG_ONLY(clear_suspendible_thread();)
 212 
 213   // allocated data structures
 214   set_osthread(NULL);
 215   set_resource_area(new (mtThread)ResourceArea());
 216   DEBUG_ONLY(_current_resource_mark = NULL;)
 217   set_handle_area(new (mtThread) HandleArea(NULL));
 218   set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
 219   set_active_handles(NULL);
 220   set_free_handle_block(NULL);
 221   set_last_handle_mark(NULL);
 222 
 223   // This initial value ==> never claimed.
 224   _oops_do_parity = 0;
 225 
 226   // the handle mark links itself to last_handle_mark
 227   new HandleMark(this);
 228 
 229   // plain initialization
 230   debug_only(_owned_locks = NULL;)
 231   debug_only(_allow_allocation_count = 0;)
 232   NOT_PRODUCT(_allow_safepoint_count = 0;)
 233   NOT_PRODUCT(_skip_gcalot = false;)
 234   _jvmti_env_iteration_count = 0;
 235   set_allocated_bytes(0);
 236   _vm_operation_started_count = 0;
 237   _vm_operation_completed_count = 0;
 238   _current_pending_monitor = NULL;
 239   _current_pending_monitor_is_from_java = true;
 240   _current_waiting_monitor = NULL;
 241   _num_nested_signal = 0;
 242   omFreeList = NULL;
 243   omFreeCount = 0;
 244   omFreeProvision = 32;
 245   omInUseList = NULL;
 246   omInUseCount = 0;
 247 
 248 #ifdef ASSERT
 249   _visited_for_critical_count = false;
 250 #endif
 251 
 252   _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
 253                          Monitor::_safepoint_check_sometimes);
 254   _suspend_flags = 0;
 255 
 256   // thread-specific hashCode stream generator state - Marsaglia shift-xor form
 257   _hashStateX = os::random();
 258   _hashStateY = 842502087;
 259   _hashStateZ = 0x8767;    // (int)(3579807591LL & 0xffff) ;
 260   _hashStateW = 273326509;
 261 
 262   _OnTrap   = 0;
 263   _schedctl = NULL;
 264   _Stalled  = 0;
 265   _TypeTag  = 0x2BAD;
 266 
 267   // Many of the following fields are effectively final - immutable
 268   // Note that nascent threads can't use the Native Monitor-Mutex
 269   // construct until the _MutexEvent is initialized ...
 270   // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
 271   // we might instead use a stack of ParkEvents that we could provision on-demand.
 272   // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
 273   // and ::Release()
 274   _ParkEvent   = ParkEvent::Allocate(this);
 275   _SleepEvent  = ParkEvent::Allocate(this);
 276   _MutexEvent  = ParkEvent::Allocate(this);
 277   _MuxEvent    = ParkEvent::Allocate(this);
 278 
 279 #ifdef CHECK_UNHANDLED_OOPS
 280   if (CheckUnhandledOops) {
 281     _unhandled_oops = new UnhandledOops(this);
 282   }
 283 #endif // CHECK_UNHANDLED_OOPS
 284 #ifdef ASSERT
 285   if (UseBiasedLocking) {
 286     assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
 287     assert(this == _real_malloc_address ||
 288            this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
 289            "bug in forced alignment of thread objects");
 290   }
 291 #endif // ASSERT
 292 }
 293 
 294 void Thread::initialize_thread_current() {
 295 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 296   assert(_thr_current == NULL, "Thread::current already initialized");
 297   _thr_current = this;
 298 #endif
 299   assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
 300   ThreadLocalStorage::set_thread(this);
 301   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 302 }
 303 
 304 void Thread::clear_thread_current() {
 305   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 306 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 307   _thr_current = NULL;
 308 #endif
 309   ThreadLocalStorage::set_thread(NULL);
 310 }
 311 
 312 void Thread::record_stack_base_and_size() {
 313   set_stack_base(os::current_stack_base());
 314   set_stack_size(os::current_stack_size());
 315   // CR 7190089: on Solaris, primordial thread's stack is adjusted
 316   // in initialize_thread(). Without the adjustment, stack size is
 317   // incorrect if stack is set to unlimited (ulimit -s unlimited).
 318   // So far, only Solaris has real implementation of initialize_thread().
 319   //
 320   // set up any platform-specific state.
 321   os::initialize_thread(this);
 322 
 323   // Set stack limits after thread is initialized.
 324   if (is_Java_thread()) {
 325     ((JavaThread*) this)->set_stack_overflow_limit();
 326     ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
 327   }
 328 #if INCLUDE_NMT
 329   // record thread's native stack, stack grows downward
 330   MemTracker::record_thread_stack(stack_end(), stack_size());
 331 #endif // INCLUDE_NMT
 332   log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
 333     PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
 334     os::current_thread_id(), p2i(stack_base() - stack_size()),
 335     p2i(stack_base()), stack_size()/1024);
 336 }
 337 
 338 
 339 Thread::~Thread() {
 340   // Reclaim the objectmonitors from the omFreeList of the moribund thread.
 341   ObjectSynchronizer::omFlush(this);
 342 
 343   EVENT_THREAD_DESTRUCT(this);
 344 
 345   // stack_base can be NULL if the thread is never started or exited before
 346   // record_stack_base_and_size called. Although, we would like to ensure
 347   // that all started threads do call record_stack_base_and_size(), there is
 348   // not proper way to enforce that.
 349 #if INCLUDE_NMT
 350   if (_stack_base != NULL) {
 351     MemTracker::release_thread_stack(stack_end(), stack_size());
 352 #ifdef ASSERT
 353     set_stack_base(NULL);
 354 #endif
 355   }
 356 #endif // INCLUDE_NMT
 357 
 358   // deallocate data structures
 359   delete resource_area();
 360   // since the handle marks are using the handle area, we have to deallocated the root
 361   // handle mark before deallocating the thread's handle area,
 362   assert(last_handle_mark() != NULL, "check we have an element");
 363   delete last_handle_mark();
 364   assert(last_handle_mark() == NULL, "check we have reached the end");
 365 
 366   // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
 367   // We NULL out the fields for good hygiene.
 368   ParkEvent::Release(_ParkEvent); _ParkEvent   = NULL;
 369   ParkEvent::Release(_SleepEvent); _SleepEvent  = NULL;
 370   ParkEvent::Release(_MutexEvent); _MutexEvent  = NULL;
 371   ParkEvent::Release(_MuxEvent); _MuxEvent    = NULL;
 372 
 373   delete handle_area();
 374   delete metadata_handles();
 375 
 376   // osthread() can be NULL, if creation of thread failed.
 377   if (osthread() != NULL) os::free_thread(osthread());
 378 
 379   delete _SR_lock;
 380 
 381   // clear Thread::current if thread is deleting itself.
 382   // Needed to ensure JNI correctly detects non-attached threads.
 383   if (this == Thread::current()) {
 384     clear_thread_current();
 385   }
 386 
 387   CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
 388 }
 389 
 390 // NOTE: dummy function for assertion purpose.
 391 void Thread::run() {
 392   ShouldNotReachHere();
 393 }
 394 
 395 #ifdef ASSERT
 396 // Private method to check for dangling thread pointer
 397 void check_for_dangling_thread_pointer(Thread *thread) {
 398   assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
 399          "possibility of dangling Thread pointer");
 400 }
 401 #endif
 402 
 403 ThreadPriority Thread::get_priority(const Thread* const thread) {
 404   ThreadPriority priority;
 405   // Can return an error!
 406   (void)os::get_priority(thread, priority);
 407   assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
 408   return priority;
 409 }
 410 
 411 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
 412   debug_only(check_for_dangling_thread_pointer(thread);)
 413   // Can return an error!
 414   (void)os::set_priority(thread, priority);
 415 }
 416 
 417 
 418 void Thread::start(Thread* thread) {
 419   // Start is different from resume in that its safety is guaranteed by context or
 420   // being called from a Java method synchronized on the Thread object.
 421   if (!DisableStartThread) {
 422     if (thread->is_Java_thread()) {
 423       // Initialize the thread state to RUNNABLE before starting this thread.
 424       // Can not set it after the thread started because we do not know the
 425       // exact thread state at that time. It could be in MONITOR_WAIT or
 426       // in SLEEPING or some other state.
 427       java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
 428                                           java_lang_Thread::RUNNABLE);
 429     }
 430     os::start_thread(thread);
 431   }
 432 }
 433 
 434 // Enqueue a VM_Operation to do the job for us - sometime later
 435 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
 436   VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
 437   VMThread::execute(vm_stop);
 438 }
 439 
 440 
 441 // Check if an external suspend request has completed (or has been
 442 // cancelled). Returns true if the thread is externally suspended and
 443 // false otherwise.
 444 //
 445 // The bits parameter returns information about the code path through
 446 // the routine. Useful for debugging:
 447 //
 448 // set in is_ext_suspend_completed():
 449 // 0x00000001 - routine was entered
 450 // 0x00000010 - routine return false at end
 451 // 0x00000100 - thread exited (return false)
 452 // 0x00000200 - suspend request cancelled (return false)
 453 // 0x00000400 - thread suspended (return true)
 454 // 0x00001000 - thread is in a suspend equivalent state (return true)
 455 // 0x00002000 - thread is native and walkable (return true)
 456 // 0x00004000 - thread is native_trans and walkable (needed retry)
 457 //
 458 // set in wait_for_ext_suspend_completion():
 459 // 0x00010000 - routine was entered
 460 // 0x00020000 - suspend request cancelled before loop (return false)
 461 // 0x00040000 - thread suspended before loop (return true)
 462 // 0x00080000 - suspend request cancelled in loop (return false)
 463 // 0x00100000 - thread suspended in loop (return true)
 464 // 0x00200000 - suspend not completed during retry loop (return false)
 465 
 466 // Helper class for tracing suspend wait debug bits.
 467 //
 468 // 0x00000100 indicates that the target thread exited before it could
 469 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
 470 // 0x00080000 each indicate a cancelled suspend request so they don't
 471 // count as wait failures either.
 472 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
 473 
 474 class TraceSuspendDebugBits : public StackObj {
 475  private:
 476   JavaThread * jt;
 477   bool         is_wait;
 478   bool         called_by_wait;  // meaningful when !is_wait
 479   uint32_t *   bits;
 480 
 481  public:
 482   TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
 483                         uint32_t *_bits) {
 484     jt             = _jt;
 485     is_wait        = _is_wait;
 486     called_by_wait = _called_by_wait;
 487     bits           = _bits;
 488   }
 489 
 490   ~TraceSuspendDebugBits() {
 491     if (!is_wait) {
 492 #if 1
 493       // By default, don't trace bits for is_ext_suspend_completed() calls.
 494       // That trace is very chatty.
 495       return;
 496 #else
 497       if (!called_by_wait) {
 498         // If tracing for is_ext_suspend_completed() is enabled, then only
 499         // trace calls to it from wait_for_ext_suspend_completion()
 500         return;
 501       }
 502 #endif
 503     }
 504 
 505     if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
 506       if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
 507         MutexLocker ml(Threads_lock);  // needed for get_thread_name()
 508         ResourceMark rm;
 509 
 510         tty->print_cr(
 511                       "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
 512                       jt->get_thread_name(), *bits);
 513 
 514         guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
 515       }
 516     }
 517   }
 518 };
 519 #undef DEBUG_FALSE_BITS
 520 
 521 
 522 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
 523                                           uint32_t *bits) {
 524   TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
 525 
 526   bool did_trans_retry = false;  // only do thread_in_native_trans retry once
 527   bool do_trans_retry;           // flag to force the retry
 528 
 529   *bits |= 0x00000001;
 530 
 531   do {
 532     do_trans_retry = false;
 533 
 534     if (is_exiting()) {
 535       // Thread is in the process of exiting. This is always checked
 536       // first to reduce the risk of dereferencing a freed JavaThread.
 537       *bits |= 0x00000100;
 538       return false;
 539     }
 540 
 541     if (!is_external_suspend()) {
 542       // Suspend request is cancelled. This is always checked before
 543       // is_ext_suspended() to reduce the risk of a rogue resume
 544       // confusing the thread that made the suspend request.
 545       *bits |= 0x00000200;
 546       return false;
 547     }
 548 
 549     if (is_ext_suspended()) {
 550       // thread is suspended
 551       *bits |= 0x00000400;
 552       return true;
 553     }
 554 
 555     // Now that we no longer do hard suspends of threads running
 556     // native code, the target thread can be changing thread state
 557     // while we are in this routine:
 558     //
 559     //   _thread_in_native -> _thread_in_native_trans -> _thread_blocked
 560     //
 561     // We save a copy of the thread state as observed at this moment
 562     // and make our decision about suspend completeness based on the
 563     // copy. This closes the race where the thread state is seen as
 564     // _thread_in_native_trans in the if-thread_blocked check, but is
 565     // seen as _thread_blocked in if-thread_in_native_trans check.
 566     JavaThreadState save_state = thread_state();
 567 
 568     if (save_state == _thread_blocked && is_suspend_equivalent()) {
 569       // If the thread's state is _thread_blocked and this blocking
 570       // condition is known to be equivalent to a suspend, then we can
 571       // consider the thread to be externally suspended. This means that
 572       // the code that sets _thread_blocked has been modified to do
 573       // self-suspension if the blocking condition releases. We also
 574       // used to check for CONDVAR_WAIT here, but that is now covered by
 575       // the _thread_blocked with self-suspension check.
 576       //
 577       // Return true since we wouldn't be here unless there was still an
 578       // external suspend request.
 579       *bits |= 0x00001000;
 580       return true;
 581     } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
 582       // Threads running native code will self-suspend on native==>VM/Java
 583       // transitions. If its stack is walkable (should always be the case
 584       // unless this function is called before the actual java_suspend()
 585       // call), then the wait is done.
 586       *bits |= 0x00002000;
 587       return true;
 588     } else if (!called_by_wait && !did_trans_retry &&
 589                save_state == _thread_in_native_trans &&
 590                frame_anchor()->walkable()) {
 591       // The thread is transitioning from thread_in_native to another
 592       // thread state. check_safepoint_and_suspend_for_native_trans()
 593       // will force the thread to self-suspend. If it hasn't gotten
 594       // there yet we may have caught the thread in-between the native
 595       // code check above and the self-suspend. Lucky us. If we were
 596       // called by wait_for_ext_suspend_completion(), then it
 597       // will be doing the retries so we don't have to.
 598       //
 599       // Since we use the saved thread state in the if-statement above,
 600       // there is a chance that the thread has already transitioned to
 601       // _thread_blocked by the time we get here. In that case, we will
 602       // make a single unnecessary pass through the logic below. This
 603       // doesn't hurt anything since we still do the trans retry.
 604 
 605       *bits |= 0x00004000;
 606 
 607       // Once the thread leaves thread_in_native_trans for another
 608       // thread state, we break out of this retry loop. We shouldn't
 609       // need this flag to prevent us from getting back here, but
 610       // sometimes paranoia is good.
 611       did_trans_retry = true;
 612 
 613       // We wait for the thread to transition to a more usable state.
 614       for (int i = 1; i <= SuspendRetryCount; i++) {
 615         // We used to do an "os::yield_all(i)" call here with the intention
 616         // that yielding would increase on each retry. However, the parameter
 617         // is ignored on Linux which means the yield didn't scale up. Waiting
 618         // on the SR_lock below provides a much more predictable scale up for
 619         // the delay. It also provides a simple/direct point to check for any
 620         // safepoint requests from the VMThread
 621 
 622         // temporarily drops SR_lock while doing wait with safepoint check
 623         // (if we're a JavaThread - the WatcherThread can also call this)
 624         // and increase delay with each retry
 625         SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 626 
 627         // check the actual thread state instead of what we saved above
 628         if (thread_state() != _thread_in_native_trans) {
 629           // the thread has transitioned to another thread state so
 630           // try all the checks (except this one) one more time.
 631           do_trans_retry = true;
 632           break;
 633         }
 634       } // end retry loop
 635 
 636 
 637     }
 638   } while (do_trans_retry);
 639 
 640   *bits |= 0x00000010;
 641   return false;
 642 }
 643 
 644 // Wait for an external suspend request to complete (or be cancelled).
 645 // Returns true if the thread is externally suspended and false otherwise.
 646 //
 647 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
 648                                                  uint32_t *bits) {
 649   TraceSuspendDebugBits tsdb(this, true /* is_wait */,
 650                              false /* !called_by_wait */, bits);
 651 
 652   // local flag copies to minimize SR_lock hold time
 653   bool is_suspended;
 654   bool pending;
 655   uint32_t reset_bits;
 656 
 657   // set a marker so is_ext_suspend_completed() knows we are the caller
 658   *bits |= 0x00010000;
 659 
 660   // We use reset_bits to reinitialize the bits value at the top of
 661   // each retry loop. This allows the caller to make use of any
 662   // unused bits for their own marking purposes.
 663   reset_bits = *bits;
 664 
 665   {
 666     MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
 667     is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 668                                             delay, bits);
 669     pending = is_external_suspend();
 670   }
 671   // must release SR_lock to allow suspension to complete
 672 
 673   if (!pending) {
 674     // A cancelled suspend request is the only false return from
 675     // is_ext_suspend_completed() that keeps us from entering the
 676     // retry loop.
 677     *bits |= 0x00020000;
 678     return false;
 679   }
 680 
 681   if (is_suspended) {
 682     *bits |= 0x00040000;
 683     return true;
 684   }
 685 
 686   for (int i = 1; i <= retries; i++) {
 687     *bits = reset_bits;  // reinit to only track last retry
 688 
 689     // We used to do an "os::yield_all(i)" call here with the intention
 690     // that yielding would increase on each retry. However, the parameter
 691     // is ignored on Linux which means the yield didn't scale up. Waiting
 692     // on the SR_lock below provides a much more predictable scale up for
 693     // the delay. It also provides a simple/direct point to check for any
 694     // safepoint requests from the VMThread
 695 
 696     {
 697       MutexLocker ml(SR_lock());
 698       // wait with safepoint check (if we're a JavaThread - the WatcherThread
 699       // can also call this)  and increase delay with each retry
 700       SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 701 
 702       is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 703                                               delay, bits);
 704 
 705       // It is possible for the external suspend request to be cancelled
 706       // (by a resume) before the actual suspend operation is completed.
 707       // Refresh our local copy to see if we still need to wait.
 708       pending = is_external_suspend();
 709     }
 710 
 711     if (!pending) {
 712       // A cancelled suspend request is the only false return from
 713       // is_ext_suspend_completed() that keeps us from staying in the
 714       // retry loop.
 715       *bits |= 0x00080000;
 716       return false;
 717     }
 718 
 719     if (is_suspended) {
 720       *bits |= 0x00100000;
 721       return true;
 722     }
 723   } // end retry loop
 724 
 725   // thread did not suspend after all our retries
 726   *bits |= 0x00200000;
 727   return false;
 728 }
 729 
 730 #ifndef PRODUCT
 731 void JavaThread::record_jump(address target, address instr, const char* file,
 732                              int line) {
 733 
 734   // This should not need to be atomic as the only way for simultaneous
 735   // updates is via interrupts. Even then this should be rare or non-existent
 736   // and we don't care that much anyway.
 737 
 738   int index = _jmp_ring_index;
 739   _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
 740   _jmp_ring[index]._target = (intptr_t) target;
 741   _jmp_ring[index]._instruction = (intptr_t) instr;
 742   _jmp_ring[index]._file = file;
 743   _jmp_ring[index]._line = line;
 744 }
 745 #endif // PRODUCT
 746 
 747 // Called by flat profiler
 748 // Callers have already called wait_for_ext_suspend_completion
 749 // The assertion for that is currently too complex to put here:
 750 bool JavaThread::profile_last_Java_frame(frame* _fr) {
 751   bool gotframe = false;
 752   // self suspension saves needed state.
 753   if (has_last_Java_frame() && _anchor.walkable()) {
 754     *_fr = pd_last_frame();
 755     gotframe = true;
 756   }
 757   return gotframe;
 758 }
 759 
 760 void Thread::interrupt(Thread* thread) {
 761   debug_only(check_for_dangling_thread_pointer(thread);)
 762   os::interrupt(thread);
 763 }
 764 
 765 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
 766   debug_only(check_for_dangling_thread_pointer(thread);)
 767   // Note:  If clear_interrupted==false, this simply fetches and
 768   // returns the value of the field osthread()->interrupted().
 769   return os::is_interrupted(thread, clear_interrupted);
 770 }
 771 
 772 
 773 // GC Support
 774 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
 775   jint thread_parity = _oops_do_parity;
 776   if (thread_parity != strong_roots_parity) {
 777     jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
 778     if (res == thread_parity) {
 779       return true;
 780     } else {
 781       guarantee(res == strong_roots_parity, "Or else what?");
 782       return false;
 783     }
 784   }
 785   return false;
 786 }
 787 
 788 void Thread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
 789   active_handles()->oops_do(f);
 790   // Do oop for ThreadShadow
 791   f->do_oop((oop*)&_pending_exception);
 792   handle_area()->oops_do(f);
 793 }
 794 
 795 void Thread::metadata_handles_do(void f(Metadata*)) {
 796   // Only walk the Handles in Thread.
 797   if (metadata_handles() != NULL) {
 798     for (int i = 0; i< metadata_handles()->length(); i++) {
 799       f(metadata_handles()->at(i));
 800     }
 801   }
 802 }
 803 
 804 void Thread::print_on(outputStream* st) const {
 805   // get_priority assumes osthread initialized
 806   if (osthread() != NULL) {
 807     int os_prio;
 808     if (os::get_native_priority(this, &os_prio) == OS_OK) {
 809       st->print("os_prio=%d ", os_prio);
 810     }
 811     st->print("tid=" INTPTR_FORMAT " ", p2i(this));
 812     ext().print_on(st);
 813     osthread()->print_on(st);
 814   }
 815   debug_only(if (WizardMode) print_owned_locks_on(st);)
 816 }
 817 
 818 // Thread::print_on_error() is called by fatal error handler. Don't use
 819 // any lock or allocate memory.
 820 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
 821   assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
 822 
 823   if (is_VM_thread())                 { st->print("VMThread"); }
 824   else if (is_GC_task_thread())       { st->print("GCTaskThread"); }
 825   else if (is_Watcher_thread())       { st->print("WatcherThread"); }
 826   else if (is_ConcurrentGC_thread())  { st->print("ConcurrentGCThread"); }
 827   else                                { st->print("Thread"); }
 828 
 829   if (is_Named_thread()) {
 830     st->print(" \"%s\"", name());
 831   }
 832 
 833   st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
 834             p2i(stack_end()), p2i(stack_base()));
 835 
 836   if (osthread()) {
 837     st->print(" [id=%d]", osthread()->thread_id());
 838   }
 839 }
 840 
 841 #ifdef ASSERT
 842 void Thread::print_owned_locks_on(outputStream* st) const {
 843   Monitor *cur = _owned_locks;
 844   if (cur == NULL) {
 845     st->print(" (no locks) ");
 846   } else {
 847     st->print_cr(" Locks owned:");
 848     while (cur) {
 849       cur->print_on(st);
 850       cur = cur->next();
 851     }
 852   }
 853 }
 854 
 855 static int ref_use_count  = 0;
 856 
 857 bool Thread::owns_locks_but_compiled_lock() const {
 858   for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 859     if (cur != Compile_lock) return true;
 860   }
 861   return false;
 862 }
 863 
 864 
 865 #endif
 866 
 867 #ifndef PRODUCT
 868 
 869 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
 870 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
 871 // no threads which allow_vm_block's are held
 872 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
 873   // Check if current thread is allowed to block at a safepoint
 874   if (!(_allow_safepoint_count == 0)) {
 875     fatal("Possible safepoint reached by thread that does not allow it");
 876   }
 877   if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
 878     fatal("LEAF method calling lock?");
 879   }
 880 
 881 #ifdef ASSERT
 882   if (potential_vm_operation && is_Java_thread()
 883       && !Universe::is_bootstrapping()) {
 884     // Make sure we do not hold any locks that the VM thread also uses.
 885     // This could potentially lead to deadlocks
 886     for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 887       // Threads_lock is special, since the safepoint synchronization will not start before this is
 888       // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
 889       // since it is used to transfer control between JavaThreads and the VMThread
 890       // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
 891       if ((cur->allow_vm_block() &&
 892            cur != Threads_lock &&
 893            cur != Compile_lock &&               // Temporary: should not be necessary when we get separate compilation
 894            cur != VMOperationRequest_lock &&
 895            cur != VMOperationQueue_lock) ||
 896            cur->rank() == Mutex::special) {
 897         fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
 898       }
 899     }
 900   }
 901 
 902   if (GCALotAtAllSafepoints) {
 903     // We could enter a safepoint here and thus have a gc
 904     InterfaceSupport::check_gc_alot();
 905   }
 906 #endif
 907 }
 908 #endif
 909 
 910 bool Thread::is_in_stack(address adr) const {
 911   assert(Thread::current() == this, "is_in_stack can only be called from current thread");
 912   address end = os::current_stack_pointer();
 913   // Allow non Java threads to call this without stack_base
 914   if (_stack_base == NULL) return true;
 915   if (stack_base() >= adr && adr >= end) return true;
 916 
 917   return false;
 918 }
 919 
 920 bool Thread::is_in_usable_stack(address adr) const {
 921   size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
 922   size_t usable_stack_size = _stack_size - stack_guard_size;
 923 
 924   return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
 925 }
 926 
 927 
 928 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
 929 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
 930 // used for compilation in the future. If that change is made, the need for these methods
 931 // should be revisited, and they should be removed if possible.
 932 
 933 bool Thread::is_lock_owned(address adr) const {
 934   return on_local_stack(adr);
 935 }
 936 
 937 bool Thread::set_as_starting_thread() {
 938   // NOTE: this must be called inside the main thread.
 939   return os::create_main_thread((JavaThread*)this);
 940 }
 941 
 942 static void initialize_class(Symbol* class_name, TRAPS) {
 943   Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
 944   InstanceKlass::cast(klass)->initialize(CHECK);
 945 }
 946 
 947 
 948 // Creates the initial ThreadGroup
 949 static Handle create_initial_thread_group(TRAPS) {
 950   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
 951   instanceKlassHandle klass (THREAD, k);
 952 
 953   Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
 954   {
 955     JavaValue result(T_VOID);
 956     JavaCalls::call_special(&result,
 957                             system_instance,
 958                             klass,
 959                             vmSymbols::object_initializer_name(),
 960                             vmSymbols::void_method_signature(),
 961                             CHECK_NH);
 962   }
 963   Universe::set_system_thread_group(system_instance());
 964 
 965   Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
 966   {
 967     JavaValue result(T_VOID);
 968     Handle string = java_lang_String::create_from_str("main", CHECK_NH);
 969     JavaCalls::call_special(&result,
 970                             main_instance,
 971                             klass,
 972                             vmSymbols::object_initializer_name(),
 973                             vmSymbols::threadgroup_string_void_signature(),
 974                             system_instance,
 975                             string,
 976                             CHECK_NH);
 977   }
 978   return main_instance;
 979 }
 980 
 981 // Creates the initial Thread
 982 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
 983                                  TRAPS) {
 984   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
 985   instanceKlassHandle klass (THREAD, k);
 986   instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
 987 
 988   java_lang_Thread::set_thread(thread_oop(), thread);
 989   java_lang_Thread::set_priority(thread_oop(), NormPriority);
 990   thread->set_threadObj(thread_oop());
 991 
 992   Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
 993 
 994   JavaValue result(T_VOID);
 995   JavaCalls::call_special(&result, thread_oop,
 996                           klass,
 997                           vmSymbols::object_initializer_name(),
 998                           vmSymbols::threadgroup_string_void_signature(),
 999                           thread_group,
1000                           string,
1001                           CHECK_NULL);
1002   return thread_oop();
1003 }
1004 
1005 char java_runtime_name[128] = "";
1006 char java_runtime_version[128] = "";
1007 
1008 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1009 static const char* get_java_runtime_name(TRAPS) {
1010   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
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 java.lang.VersionProps.java_runtime_version
1031 static const char* get_java_runtime_version(TRAPS) {
1032   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
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::jdk_internal_vm_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_saved_exception_pc(NULL);
1424   set_threadObj(NULL);
1425   _anchor.clear();
1426   set_entry_point(NULL);
1427   set_jni_functions(jni_functions());
1428   set_callee_target(NULL);
1429   set_vm_result(NULL);
1430   set_vm_result_2(NULL);
1431   set_vframe_array_head(NULL);
1432   set_vframe_array_last(NULL);
1433   set_deferred_locals(NULL);
1434   set_deopt_mark(NULL);
1435   set_deopt_nmethod(NULL);
1436   clear_must_deopt_id();
1437   set_monitor_chunks(NULL);
1438   set_next(NULL);
1439   set_thread_state(_thread_new);
1440   _terminated = _not_terminated;
1441   _privileged_stack_top = NULL;
1442   _array_for_gc = NULL;
1443   _suspend_equivalent = false;
1444   _in_deopt_handler = 0;
1445   _doing_unsafe_access = false;
1446   _stack_guard_state = stack_guard_unused;
1447 #if INCLUDE_JVMCI
1448   _pending_monitorenter = false;
1449   _pending_deoptimization = -1;
1450   _pending_failed_speculation = NULL;
1451   _pending_transfer_to_interpreter = false;
1452   _jvmci._alternate_call_target = NULL;
1453   assert(_jvmci._implicit_exception_pc == NULL, "must be");
1454   if (JVMCICounterSize > 0) {
1455     _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1456     memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1457   } else {
1458     _jvmci_counters = NULL;
1459   }
1460 #endif // INCLUDE_JVMCI
1461   _reserved_stack_activation = NULL;  // stack base not known yet
1462   (void)const_cast<oop&>(_exception_oop = oop(NULL));
1463   _exception_pc  = 0;
1464   _exception_handler_pc = 0;
1465   _is_method_handle_return = 0;
1466   _jvmti_thread_state= NULL;
1467   _should_post_on_exceptions_flag = JNI_FALSE;
1468   _jvmti_get_loaded_classes_closure = NULL;
1469   _interp_only_mode    = 0;
1470   _special_runtime_exit_condition = _no_async_condition;
1471   _pending_async_exception = NULL;
1472   _thread_stat = NULL;
1473   _thread_stat = new ThreadStatistics();
1474   _blocked_on_compilation = false;
1475   _jni_active_critical = 0;
1476   _pending_jni_exception_check_fn = NULL;
1477   _do_not_unlock_if_synchronized = false;
1478   _cached_monitor_info = NULL;
1479   _parker = Parker::Allocate(this);
1480 
1481 #ifndef PRODUCT
1482   _jmp_ring_index = 0;
1483   for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1484     record_jump(NULL, NULL, NULL, 0);
1485   }
1486 #endif // PRODUCT
1487 
1488   set_thread_profiler(NULL);
1489   if (FlatProfiler::is_active()) {
1490     // This is where we would decide to either give each thread it's own profiler
1491     // or use one global one from FlatProfiler,
1492     // or up to some count of the number of profiled threads, etc.
1493     ThreadProfiler* pp = new ThreadProfiler();
1494     pp->engage();
1495     set_thread_profiler(pp);
1496   }
1497 
1498   // Setup safepoint state info for this thread
1499   ThreadSafepointState::create(this);
1500 
1501   debug_only(_java_call_counter = 0);
1502 
1503   // JVMTI PopFrame support
1504   _popframe_condition = popframe_inactive;
1505   _popframe_preserved_args = NULL;
1506   _popframe_preserved_args_size = 0;
1507   _frames_to_pop_failed_realloc = 0;
1508 
1509   pd_initialize();
1510 }
1511 
1512 #if INCLUDE_ALL_GCS
1513 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1514 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1515 #endif // INCLUDE_ALL_GCS
1516 
1517 JavaThread::JavaThread(bool is_attaching_via_jni) :
1518                        Thread()
1519 #if INCLUDE_ALL_GCS
1520                        , _satb_mark_queue(&_satb_mark_queue_set),
1521                        _dirty_card_queue(&_dirty_card_queue_set)
1522 #endif // INCLUDE_ALL_GCS
1523 {
1524   initialize();
1525   if (is_attaching_via_jni) {
1526     _jni_attach_state = _attaching_via_jni;
1527   } else {
1528     _jni_attach_state = _not_attaching_via_jni;
1529   }
1530   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1531 }
1532 
1533 bool JavaThread::reguard_stack(address cur_sp) {
1534   if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1535       && _stack_guard_state != stack_guard_reserved_disabled) {
1536     return true; // Stack already guarded or guard pages not needed.
1537   }
1538 
1539   if (register_stack_overflow()) {
1540     // For those architectures which have separate register and
1541     // memory stacks, we must check the register stack to see if
1542     // it has overflowed.
1543     return false;
1544   }
1545 
1546   // Java code never executes within the yellow zone: the latter is only
1547   // there to provoke an exception during stack banging.  If java code
1548   // is executing there, either StackShadowPages should be larger, or
1549   // some exception code in c1, c2 or the interpreter isn't unwinding
1550   // when it should.
1551   guarantee(cur_sp > stack_reserved_zone_base(),
1552             "not enough space to reguard - increase StackShadowPages");
1553   if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1554     enable_stack_yellow_reserved_zone();
1555     if (reserved_stack_activation() != stack_base()) {
1556       set_reserved_stack_activation(stack_base());
1557     }
1558   } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1559     set_reserved_stack_activation(stack_base());
1560     enable_stack_reserved_zone();
1561   }
1562   return true;
1563 }
1564 
1565 bool JavaThread::reguard_stack(void) {
1566   return reguard_stack(os::current_stack_pointer());
1567 }
1568 
1569 
1570 void JavaThread::block_if_vm_exited() {
1571   if (_terminated == _vm_exited) {
1572     // _vm_exited is set at safepoint, and Threads_lock is never released
1573     // we will block here forever
1574     Threads_lock->lock_without_safepoint_check();
1575     ShouldNotReachHere();
1576   }
1577 }
1578 
1579 
1580 // Remove this ifdef when C1 is ported to the compiler interface.
1581 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1582 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1583 
1584 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1585                        Thread()
1586 #if INCLUDE_ALL_GCS
1587                        , _satb_mark_queue(&_satb_mark_queue_set),
1588                        _dirty_card_queue(&_dirty_card_queue_set)
1589 #endif // INCLUDE_ALL_GCS
1590 {
1591   initialize();
1592   _jni_attach_state = _not_attaching_via_jni;
1593   set_entry_point(entry_point);
1594   // Create the native thread itself.
1595   // %note runtime_23
1596   os::ThreadType thr_type = os::java_thread;
1597   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1598                                                      os::java_thread;
1599   os::create_thread(this, thr_type, stack_sz);
1600   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1601   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1602   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1603   // the exception consists of creating the exception object & initializing it, initialization
1604   // will leave the VM via a JavaCall and then all locks must be unlocked).
1605   //
1606   // The thread is still suspended when we reach here. Thread must be explicit started
1607   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1608   // by calling Threads:add. The reason why this is not done here, is because the thread
1609   // object must be fully initialized (take a look at JVM_Start)
1610 }
1611 
1612 JavaThread::~JavaThread() {
1613 
1614   // JSR166 -- return the parker to the free list
1615   Parker::Release(_parker);
1616   _parker = NULL;
1617 
1618   // Free any remaining  previous UnrollBlock
1619   vframeArray* old_array = vframe_array_last();
1620 
1621   if (old_array != NULL) {
1622     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1623     old_array->set_unroll_block(NULL);
1624     delete old_info;
1625     delete old_array;
1626   }
1627 
1628   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1629   if (deferred != NULL) {
1630     // This can only happen if thread is destroyed before deoptimization occurs.
1631     assert(deferred->length() != 0, "empty array!");
1632     do {
1633       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1634       deferred->remove_at(0);
1635       // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1636       delete dlv;
1637     } while (deferred->length() != 0);
1638     delete deferred;
1639   }
1640 
1641   // All Java related clean up happens in exit
1642   ThreadSafepointState::destroy(this);
1643   if (_thread_profiler != NULL) delete _thread_profiler;
1644   if (_thread_stat != NULL) delete _thread_stat;
1645 
1646 #if INCLUDE_JVMCI
1647   if (JVMCICounterSize > 0) {
1648     if (jvmci_counters_include(this)) {
1649       for (int i = 0; i < JVMCICounterSize; i++) {
1650         _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1651       }
1652     }
1653     FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1654   }
1655 #endif // INCLUDE_JVMCI
1656 }
1657 
1658 
1659 // The first routine called by a new Java thread
1660 void JavaThread::run() {
1661   // initialize thread-local alloc buffer related fields
1662   this->initialize_tlab();
1663 
1664   // used to test validity of stack trace backs
1665   this->record_base_of_stack_pointer();
1666 
1667   // Record real stack base and size.
1668   this->record_stack_base_and_size();
1669 
1670   this->create_stack_guard_pages();
1671 
1672   this->cache_global_variables();
1673 
1674   // Thread is now sufficient initialized to be handled by the safepoint code as being
1675   // in the VM. Change thread state from _thread_new to _thread_in_vm
1676   ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1677 
1678   assert(JavaThread::current() == this, "sanity check");
1679   assert(!Thread::current()->owns_locks(), "sanity check");
1680 
1681   DTRACE_THREAD_PROBE(start, this);
1682 
1683   // This operation might block. We call that after all safepoint checks for a new thread has
1684   // been completed.
1685   this->set_active_handles(JNIHandleBlock::allocate_block());
1686 
1687   if (JvmtiExport::should_post_thread_life()) {
1688     JvmtiExport::post_thread_start(this);
1689   }
1690 
1691   EventThreadStart event;
1692   if (event.should_commit()) {
1693     event.set_thread(THREAD_TRACE_ID(this));
1694     event.commit();
1695   }
1696 
1697   // We call another function to do the rest so we are sure that the stack addresses used
1698   // from there will be lower than the stack base just computed
1699   thread_main_inner();
1700 
1701   // Note, thread is no longer valid at this point!
1702 }
1703 
1704 
1705 void JavaThread::thread_main_inner() {
1706   assert(JavaThread::current() == this, "sanity check");
1707   assert(this->threadObj() != NULL, "just checking");
1708 
1709   // Execute thread entry point unless this thread has a pending exception
1710   // or has been stopped before starting.
1711   // Note: Due to JVM_StopThread we can have pending exceptions already!
1712   if (!this->has_pending_exception() &&
1713       !java_lang_Thread::is_stillborn(this->threadObj())) {
1714     {
1715       ResourceMark rm(this);
1716       this->set_native_thread_name(this->get_thread_name());
1717     }
1718     HandleMark hm(this);
1719     this->entry_point()(this, this);
1720   }
1721 
1722   DTRACE_THREAD_PROBE(stop, this);
1723 
1724   this->exit(false);
1725   delete this;
1726 }
1727 
1728 
1729 static void ensure_join(JavaThread* thread) {
1730   // We do not need to grap the Threads_lock, since we are operating on ourself.
1731   Handle threadObj(thread, thread->threadObj());
1732   assert(threadObj.not_null(), "java thread object must exist");
1733   ObjectLocker lock(threadObj, thread);
1734   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1735   thread->clear_pending_exception();
1736   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1737   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1738   // Clear the native thread instance - this makes isAlive return false and allows the join()
1739   // to complete once we've done the notify_all below
1740   java_lang_Thread::set_thread(threadObj(), NULL);
1741   lock.notify_all(thread);
1742   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1743   thread->clear_pending_exception();
1744 }
1745 
1746 
1747 // For any new cleanup additions, please check to see if they need to be applied to
1748 // cleanup_failed_attach_current_thread as well.
1749 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1750   assert(this == JavaThread::current(), "thread consistency check");
1751 
1752   HandleMark hm(this);
1753   Handle uncaught_exception(this, this->pending_exception());
1754   this->clear_pending_exception();
1755   Handle threadObj(this, this->threadObj());
1756   assert(threadObj.not_null(), "Java thread object should be created");
1757 
1758   if (get_thread_profiler() != NULL) {
1759     get_thread_profiler()->disengage();
1760     ResourceMark rm;
1761     get_thread_profiler()->print(get_thread_name());
1762   }
1763 
1764 
1765   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1766   {
1767     EXCEPTION_MARK;
1768 
1769     CLEAR_PENDING_EXCEPTION;
1770   }
1771   if (!destroy_vm) {
1772     if (uncaught_exception.not_null()) {
1773       EXCEPTION_MARK;
1774       // Call method Thread.dispatchUncaughtException().
1775       KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1776       JavaValue result(T_VOID);
1777       JavaCalls::call_virtual(&result,
1778                               threadObj, thread_klass,
1779                               vmSymbols::dispatchUncaughtException_name(),
1780                               vmSymbols::throwable_void_signature(),
1781                               uncaught_exception,
1782                               THREAD);
1783       if (HAS_PENDING_EXCEPTION) {
1784         ResourceMark rm(this);
1785         jio_fprintf(defaultStream::error_stream(),
1786                     "\nException: %s thrown from the UncaughtExceptionHandler"
1787                     " in thread \"%s\"\n",
1788                     pending_exception()->klass()->external_name(),
1789                     get_thread_name());
1790         CLEAR_PENDING_EXCEPTION;
1791       }
1792     }
1793 
1794     // Called before the java thread exit since we want to read info
1795     // from java_lang_Thread object
1796     EventThreadEnd event;
1797     if (event.should_commit()) {
1798       event.set_thread(THREAD_TRACE_ID(this));
1799       event.commit();
1800     }
1801 
1802     // Call after last event on thread
1803     EVENT_THREAD_EXIT(this);
1804 
1805     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1806     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1807     // is deprecated anyhow.
1808     if (!is_Compiler_thread()) {
1809       int count = 3;
1810       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1811         EXCEPTION_MARK;
1812         JavaValue result(T_VOID);
1813         KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1814         JavaCalls::call_virtual(&result,
1815                                 threadObj, thread_klass,
1816                                 vmSymbols::exit_method_name(),
1817                                 vmSymbols::void_method_signature(),
1818                                 THREAD);
1819         CLEAR_PENDING_EXCEPTION;
1820       }
1821     }
1822     // notify JVMTI
1823     if (JvmtiExport::should_post_thread_life()) {
1824       JvmtiExport::post_thread_end(this);
1825     }
1826 
1827     // We have notified the agents that we are exiting, before we go on,
1828     // we must check for a pending external suspend request and honor it
1829     // in order to not surprise the thread that made the suspend request.
1830     while (true) {
1831       {
1832         MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1833         if (!is_external_suspend()) {
1834           set_terminated(_thread_exiting);
1835           ThreadService::current_thread_exiting(this);
1836           break;
1837         }
1838         // Implied else:
1839         // Things get a little tricky here. We have a pending external
1840         // suspend request, but we are holding the SR_lock so we
1841         // can't just self-suspend. So we temporarily drop the lock
1842         // and then self-suspend.
1843       }
1844 
1845       ThreadBlockInVM tbivm(this);
1846       java_suspend_self();
1847 
1848       // We're done with this suspend request, but we have to loop around
1849       // and check again. Eventually we will get SR_lock without a pending
1850       // external suspend request and will be able to mark ourselves as
1851       // exiting.
1852     }
1853     // no more external suspends are allowed at this point
1854   } else {
1855     // before_exit() has already posted JVMTI THREAD_END events
1856   }
1857 
1858   // Notify waiters on thread object. This has to be done after exit() is called
1859   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1860   // group should have the destroyed bit set before waiters are notified).
1861   ensure_join(this);
1862   assert(!this->has_pending_exception(), "ensure_join should have cleared");
1863 
1864   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1865   // held by this thread must be released. The spec does not distinguish
1866   // between JNI-acquired and regular Java monitors. We can only see
1867   // regular Java monitors here if monitor enter-exit matching is broken.
1868   //
1869   // Optionally release any monitors for regular JavaThread exits. This
1870   // is provided as a work around for any bugs in monitor enter-exit
1871   // matching. This can be expensive so it is not enabled by default.
1872   //
1873   // ensure_join() ignores IllegalThreadStateExceptions, and so does
1874   // ObjectSynchronizer::release_monitors_owned_by_thread().
1875   if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1876     // Sanity check even though JNI DetachCurrentThread() would have
1877     // returned JNI_ERR if there was a Java frame. JavaThread exit
1878     // should be done executing Java code by the time we get here.
1879     assert(!this->has_last_Java_frame(),
1880            "should not have a Java frame when detaching or exiting");
1881     ObjectSynchronizer::release_monitors_owned_by_thread(this);
1882     assert(!this->has_pending_exception(), "release_monitors should have cleared");
1883   }
1884 
1885   // These things needs to be done while we are still a Java Thread. Make sure that thread
1886   // is in a consistent state, in case GC happens
1887   assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1888 
1889   if (active_handles() != NULL) {
1890     JNIHandleBlock* block = active_handles();
1891     set_active_handles(NULL);
1892     JNIHandleBlock::release_block(block);
1893   }
1894 
1895   if (free_handle_block() != NULL) {
1896     JNIHandleBlock* block = free_handle_block();
1897     set_free_handle_block(NULL);
1898     JNIHandleBlock::release_block(block);
1899   }
1900 
1901   // These have to be removed while this is still a valid thread.
1902   remove_stack_guard_pages();
1903 
1904   if (UseTLAB) {
1905     tlab().make_parsable(true);  // retire TLAB
1906   }
1907 
1908   if (JvmtiEnv::environments_might_exist()) {
1909     JvmtiExport::cleanup_thread(this);
1910   }
1911 
1912   // We must flush any deferred card marks before removing a thread from
1913   // the list of active threads.
1914   Universe::heap()->flush_deferred_store_barrier(this);
1915   assert(deferred_card_mark().is_empty(), "Should have been flushed");
1916 
1917 #if INCLUDE_ALL_GCS
1918   // We must flush the G1-related buffers before removing a thread
1919   // from the list of active threads. We must do this after any deferred
1920   // card marks have been flushed (above) so that any entries that are
1921   // added to the thread's dirty card queue as a result are not lost.
1922   if (UseG1GC) {
1923     flush_barrier_queues();
1924   }
1925 #endif // INCLUDE_ALL_GCS
1926 
1927   log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
1928     exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
1929     os::current_thread_id());
1930 
1931   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1932   Threads::remove(this);
1933 }
1934 
1935 #if INCLUDE_ALL_GCS
1936 // Flush G1-related queues.
1937 void JavaThread::flush_barrier_queues() {
1938   satb_mark_queue().flush();
1939   dirty_card_queue().flush();
1940 }
1941 
1942 void JavaThread::initialize_queues() {
1943   assert(!SafepointSynchronize::is_at_safepoint(),
1944          "we should not be at a safepoint");
1945 
1946   SATBMarkQueue& satb_queue = satb_mark_queue();
1947   SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1948   // The SATB queue should have been constructed with its active
1949   // field set to false.
1950   assert(!satb_queue.is_active(), "SATB queue should not be active");
1951   assert(satb_queue.is_empty(), "SATB queue should be empty");
1952   // If we are creating the thread during a marking cycle, we should
1953   // set the active field of the SATB queue to true.
1954   if (satb_queue_set.is_active()) {
1955     satb_queue.set_active(true);
1956   }
1957 
1958   DirtyCardQueue& dirty_queue = dirty_card_queue();
1959   // The dirty card queue should have been constructed with its
1960   // active field set to true.
1961   assert(dirty_queue.is_active(), "dirty card queue should be active");
1962 }
1963 #endif // INCLUDE_ALL_GCS
1964 
1965 void JavaThread::cleanup_failed_attach_current_thread() {
1966   if (get_thread_profiler() != NULL) {
1967     get_thread_profiler()->disengage();
1968     ResourceMark rm;
1969     get_thread_profiler()->print(get_thread_name());
1970   }
1971 
1972   if (active_handles() != NULL) {
1973     JNIHandleBlock* block = active_handles();
1974     set_active_handles(NULL);
1975     JNIHandleBlock::release_block(block);
1976   }
1977 
1978   if (free_handle_block() != NULL) {
1979     JNIHandleBlock* block = free_handle_block();
1980     set_free_handle_block(NULL);
1981     JNIHandleBlock::release_block(block);
1982   }
1983 
1984   // These have to be removed while this is still a valid thread.
1985   remove_stack_guard_pages();
1986 
1987   if (UseTLAB) {
1988     tlab().make_parsable(true);  // retire TLAB, if any
1989   }
1990 
1991 #if INCLUDE_ALL_GCS
1992   if (UseG1GC) {
1993     flush_barrier_queues();
1994   }
1995 #endif // INCLUDE_ALL_GCS
1996 
1997   Threads::remove(this);
1998   delete this;
1999 }
2000 
2001 
2002 
2003 
2004 JavaThread* JavaThread::active() {
2005   Thread* thread = Thread::current();
2006   if (thread->is_Java_thread()) {
2007     return (JavaThread*) thread;
2008   } else {
2009     assert(thread->is_VM_thread(), "this must be a vm thread");
2010     VM_Operation* op = ((VMThread*) thread)->vm_operation();
2011     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2012     assert(ret->is_Java_thread(), "must be a Java thread");
2013     return ret;
2014   }
2015 }
2016 
2017 bool JavaThread::is_lock_owned(address adr) const {
2018   if (Thread::is_lock_owned(adr)) return true;
2019 
2020   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2021     if (chunk->contains(adr)) return true;
2022   }
2023 
2024   return false;
2025 }
2026 
2027 
2028 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2029   chunk->set_next(monitor_chunks());
2030   set_monitor_chunks(chunk);
2031 }
2032 
2033 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2034   guarantee(monitor_chunks() != NULL, "must be non empty");
2035   if (monitor_chunks() == chunk) {
2036     set_monitor_chunks(chunk->next());
2037   } else {
2038     MonitorChunk* prev = monitor_chunks();
2039     while (prev->next() != chunk) prev = prev->next();
2040     prev->set_next(chunk->next());
2041   }
2042 }
2043 
2044 // JVM support.
2045 
2046 // Note: this function shouldn't block if it's called in
2047 // _thread_in_native_trans state (such as from
2048 // check_special_condition_for_native_trans()).
2049 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2050 
2051   if (has_last_Java_frame() && has_async_condition()) {
2052     // If we are at a polling page safepoint (not a poll return)
2053     // then we must defer async exception because live registers
2054     // will be clobbered by the exception path. Poll return is
2055     // ok because the call we a returning from already collides
2056     // with exception handling registers and so there is no issue.
2057     // (The exception handling path kills call result registers but
2058     //  this is ok since the exception kills the result anyway).
2059 
2060     if (is_at_poll_safepoint()) {
2061       // if the code we are returning to has deoptimized we must defer
2062       // the exception otherwise live registers get clobbered on the
2063       // exception path before deoptimization is able to retrieve them.
2064       //
2065       RegisterMap map(this, false);
2066       frame caller_fr = last_frame().sender(&map);
2067       assert(caller_fr.is_compiled_frame(), "what?");
2068       if (caller_fr.is_deoptimized_frame()) {
2069         log_info(exceptions)("deferred async exception at compiled safepoint");
2070         return;
2071       }
2072     }
2073   }
2074 
2075   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2076   if (condition == _no_async_condition) {
2077     // Conditions have changed since has_special_runtime_exit_condition()
2078     // was called:
2079     // - if we were here only because of an external suspend request,
2080     //   then that was taken care of above (or cancelled) so we are done
2081     // - if we were here because of another async request, then it has
2082     //   been cleared between the has_special_runtime_exit_condition()
2083     //   and now so again we are done
2084     return;
2085   }
2086 
2087   // Check for pending async. exception
2088   if (_pending_async_exception != NULL) {
2089     // Only overwrite an already pending exception, if it is not a threadDeath.
2090     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2091 
2092       // We cannot call Exceptions::_throw(...) here because we cannot block
2093       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2094 
2095       if (log_is_enabled(Info, exceptions)) {
2096         ResourceMark rm;
2097         outputStream* logstream = Log(exceptions)::info_stream();
2098         logstream->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2099           if (has_last_Java_frame()) {
2100             frame f = last_frame();
2101            logstream->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2102           }
2103         logstream->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 (log_is_enabled(Info, exceptions)) {
2220          ResourceMark rm;
2221         log_info(exceptions)("Pending Async. exception installed of type: %s",
2222                              InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2223       }
2224       // for AbortVMOnException flag
2225       Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2226     }
2227   }
2228 
2229 
2230   // Interrupt thread so it will wake up from a potential wait()
2231   Thread::interrupt(this);
2232 }
2233 
2234 // External suspension mechanism.
2235 //
2236 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2237 // to any VM_locks and it is at a transition
2238 // Self-suspension will happen on the transition out of the vm.
2239 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2240 //
2241 // Guarantees on return:
2242 //   + Target thread will not execute any new bytecode (that's why we need to
2243 //     force a safepoint)
2244 //   + Target thread will not enter any new monitors
2245 //
2246 void JavaThread::java_suspend() {
2247   { MutexLocker mu(Threads_lock);
2248     if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2249       return;
2250     }
2251   }
2252 
2253   { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2254     if (!is_external_suspend()) {
2255       // a racing resume has cancelled us; bail out now
2256       return;
2257     }
2258 
2259     // suspend is done
2260     uint32_t debug_bits = 0;
2261     // Warning: is_ext_suspend_completed() may temporarily drop the
2262     // SR_lock to allow the thread to reach a stable thread state if
2263     // it is currently in a transient thread state.
2264     if (is_ext_suspend_completed(false /* !called_by_wait */,
2265                                  SuspendRetryDelay, &debug_bits)) {
2266       return;
2267     }
2268   }
2269 
2270   VM_ForceSafepoint vm_suspend;
2271   VMThread::execute(&vm_suspend);
2272 }
2273 
2274 // Part II of external suspension.
2275 // A JavaThread self suspends when it detects a pending external suspend
2276 // request. This is usually on transitions. It is also done in places
2277 // where continuing to the next transition would surprise the caller,
2278 // e.g., monitor entry.
2279 //
2280 // Returns the number of times that the thread self-suspended.
2281 //
2282 // Note: DO NOT call java_suspend_self() when you just want to block current
2283 //       thread. java_suspend_self() is the second stage of cooperative
2284 //       suspension for external suspend requests and should only be used
2285 //       to complete an external suspend request.
2286 //
2287 int JavaThread::java_suspend_self() {
2288   int ret = 0;
2289 
2290   // we are in the process of exiting so don't suspend
2291   if (is_exiting()) {
2292     clear_external_suspend();
2293     return ret;
2294   }
2295 
2296   assert(_anchor.walkable() ||
2297          (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2298          "must have walkable stack");
2299 
2300   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2301 
2302   assert(!this->is_ext_suspended(),
2303          "a thread trying to self-suspend should not already be suspended");
2304 
2305   if (this->is_suspend_equivalent()) {
2306     // If we are self-suspending as a result of the lifting of a
2307     // suspend equivalent condition, then the suspend_equivalent
2308     // flag is not cleared until we set the ext_suspended flag so
2309     // that wait_for_ext_suspend_completion() returns consistent
2310     // results.
2311     this->clear_suspend_equivalent();
2312   }
2313 
2314   // A racing resume may have cancelled us before we grabbed SR_lock
2315   // above. Or another external suspend request could be waiting for us
2316   // by the time we return from SR_lock()->wait(). The thread
2317   // that requested the suspension may already be trying to walk our
2318   // stack and if we return now, we can change the stack out from under
2319   // it. This would be a "bad thing (TM)" and cause the stack walker
2320   // to crash. We stay self-suspended until there are no more pending
2321   // external suspend requests.
2322   while (is_external_suspend()) {
2323     ret++;
2324     this->set_ext_suspended();
2325 
2326     // _ext_suspended flag is cleared by java_resume()
2327     while (is_ext_suspended()) {
2328       this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2329     }
2330   }
2331 
2332   return ret;
2333 }
2334 
2335 #ifdef ASSERT
2336 // verify the JavaThread has not yet been published in the Threads::list, and
2337 // hence doesn't need protection from concurrent access at this stage
2338 void JavaThread::verify_not_published() {
2339   if (!Threads_lock->owned_by_self()) {
2340     MutexLockerEx ml(Threads_lock,  Mutex::_no_safepoint_check_flag);
2341     assert(!Threads::includes(this),
2342            "java thread shouldn't have been published yet!");
2343   } else {
2344     assert(!Threads::includes(this),
2345            "java thread shouldn't have been published yet!");
2346   }
2347 }
2348 #endif
2349 
2350 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2351 // progress or when _suspend_flags is non-zero.
2352 // Current thread needs to self-suspend if there is a suspend request and/or
2353 // block if a safepoint is in progress.
2354 // Async exception ISN'T checked.
2355 // Note only the ThreadInVMfromNative transition can call this function
2356 // directly and when thread state is _thread_in_native_trans
2357 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2358   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2359 
2360   JavaThread *curJT = JavaThread::current();
2361   bool do_self_suspend = thread->is_external_suspend();
2362 
2363   assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2364 
2365   // If JNIEnv proxies are allowed, don't self-suspend if the target
2366   // thread is not the current thread. In older versions of jdbx, jdbx
2367   // threads could call into the VM with another thread's JNIEnv so we
2368   // can be here operating on behalf of a suspended thread (4432884).
2369   if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2370     JavaThreadState state = thread->thread_state();
2371 
2372     // We mark this thread_blocked state as a suspend-equivalent so
2373     // that a caller to is_ext_suspend_completed() won't be confused.
2374     // The suspend-equivalent state is cleared by java_suspend_self().
2375     thread->set_suspend_equivalent();
2376 
2377     // If the safepoint code sees the _thread_in_native_trans state, it will
2378     // wait until the thread changes to other thread state. There is no
2379     // guarantee on how soon we can obtain the SR_lock and complete the
2380     // self-suspend request. It would be a bad idea to let safepoint wait for
2381     // too long. Temporarily change the state to _thread_blocked to
2382     // let the VM thread know that this thread is ready for GC. The problem
2383     // of changing thread state is that safepoint could happen just after
2384     // java_suspend_self() returns after being resumed, and VM thread will
2385     // see the _thread_blocked state. We must check for safepoint
2386     // after restoring the state and make sure we won't leave while a safepoint
2387     // is in progress.
2388     thread->set_thread_state(_thread_blocked);
2389     thread->java_suspend_self();
2390     thread->set_thread_state(state);
2391     // Make sure new state is seen by VM thread
2392     if (os::is_MP()) {
2393       if (UseMembar) {
2394         // Force a fence between the write above and read below
2395         OrderAccess::fence();
2396       } else {
2397         // Must use this rather than serialization page in particular on Windows
2398         InterfaceSupport::serialize_memory(thread);
2399       }
2400     }
2401   }
2402 
2403   if (SafepointSynchronize::do_call_back()) {
2404     // If we are safepointing, then block the caller which may not be
2405     // the same as the target thread (see above).
2406     SafepointSynchronize::block(curJT);
2407   }
2408 
2409   if (thread->is_deopt_suspend()) {
2410     thread->clear_deopt_suspend();
2411     RegisterMap map(thread, false);
2412     frame f = thread->last_frame();
2413     while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2414       f = f.sender(&map);
2415     }
2416     if (f.id() == thread->must_deopt_id()) {
2417       thread->clear_must_deopt_id();
2418       f.deoptimize(thread);
2419     } else {
2420       fatal("missed deoptimization!");
2421     }
2422   }
2423 }
2424 
2425 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2426 // progress or when _suspend_flags is non-zero.
2427 // Current thread needs to self-suspend if there is a suspend request and/or
2428 // block if a safepoint is in progress.
2429 // Also check for pending async exception (not including unsafe access error).
2430 // Note only the native==>VM/Java barriers can call this function and when
2431 // thread state is _thread_in_native_trans.
2432 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2433   check_safepoint_and_suspend_for_native_trans(thread);
2434 
2435   if (thread->has_async_exception()) {
2436     // We are in _thread_in_native_trans state, don't handle unsafe
2437     // access error since that may block.
2438     thread->check_and_handle_async_exceptions(false);
2439   }
2440 }
2441 
2442 // This is a variant of the normal
2443 // check_special_condition_for_native_trans with slightly different
2444 // semantics for use by critical native wrappers.  It does all the
2445 // normal checks but also performs the transition back into
2446 // thread_in_Java state.  This is required so that critical natives
2447 // can potentially block and perform a GC if they are the last thread
2448 // exiting the GCLocker.
2449 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2450   check_special_condition_for_native_trans(thread);
2451 
2452   // Finish the transition
2453   thread->set_thread_state(_thread_in_Java);
2454 
2455   if (thread->do_critical_native_unlock()) {
2456     ThreadInVMfromJavaNoAsyncException tiv(thread);
2457     GCLocker::unlock_critical(thread);
2458     thread->clear_critical_native_unlock();
2459   }
2460 }
2461 
2462 // We need to guarantee the Threads_lock here, since resumes are not
2463 // allowed during safepoint synchronization
2464 // Can only resume from an external suspension
2465 void JavaThread::java_resume() {
2466   assert_locked_or_safepoint(Threads_lock);
2467 
2468   // Sanity check: thread is gone, has started exiting or the thread
2469   // was not externally suspended.
2470   if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2471     return;
2472   }
2473 
2474   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2475 
2476   clear_external_suspend();
2477 
2478   if (is_ext_suspended()) {
2479     clear_ext_suspended();
2480     SR_lock()->notify_all();
2481   }
2482 }
2483 
2484 size_t JavaThread::_stack_red_zone_size = 0;
2485 size_t JavaThread::_stack_yellow_zone_size = 0;
2486 size_t JavaThread::_stack_reserved_zone_size = 0;
2487 size_t JavaThread::_stack_shadow_zone_size = 0;
2488 
2489 void JavaThread::create_stack_guard_pages() {
2490   if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; }
2491   address low_addr = stack_end();
2492   size_t len = stack_guard_zone_size();
2493 
2494   int allocate = os::allocate_stack_guard_pages();
2495   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2496 
2497   if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) {
2498     log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2499     return;
2500   }
2501 
2502   if (os::guard_memory((char *) low_addr, len)) {
2503     _stack_guard_state = stack_guard_enabled;
2504   } else {
2505     log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2506       PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2507     if (os::uncommit_memory((char *) low_addr, len)) {
2508       log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2509     }
2510     return;
2511   }
2512 
2513   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2514     PTR_FORMAT "-" PTR_FORMAT ".",
2515     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2516 
2517 }
2518 
2519 void JavaThread::remove_stack_guard_pages() {
2520   assert(Thread::current() == this, "from different thread");
2521   if (_stack_guard_state == stack_guard_unused) return;
2522   address low_addr = stack_end();
2523   size_t len = stack_guard_zone_size();
2524 
2525   if (os::allocate_stack_guard_pages()) {
2526     if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2527       _stack_guard_state = stack_guard_unused;
2528     } else {
2529       log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2530         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2531       return;
2532     }
2533   } else {
2534     if (_stack_guard_state == stack_guard_unused) return;
2535     if (os::unguard_memory((char *) low_addr, len)) {
2536       _stack_guard_state = stack_guard_unused;
2537     } else {
2538       log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2539         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2540       return;
2541     }
2542   }
2543 
2544   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2545     PTR_FORMAT "-" PTR_FORMAT ".",
2546     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2547 
2548 }
2549 
2550 void JavaThread::enable_stack_reserved_zone() {
2551   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2552   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
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   guarantee(base < stack_base(),"Error calculating stack reserved zone");
2559   guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2560 
2561   if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2562     _stack_guard_state = stack_guard_enabled;
2563   } else {
2564     warning("Attempt to guard stack reserved zone failed.");
2565   }
2566   enable_register_stack_guard();
2567 }
2568 
2569 void JavaThread::disable_stack_reserved_zone() {
2570   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2571   assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2572 
2573   // Simply return if called for a thread that does not use guard pages.
2574   if (_stack_guard_state == stack_guard_unused) return;
2575 
2576   // The base notation is from the stack's point of view, growing downward.
2577   // We need to adjust it to work correctly with guard_memory()
2578   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2579 
2580   if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2581     _stack_guard_state = stack_guard_reserved_disabled;
2582   } else {
2583     warning("Attempt to unguard stack reserved zone failed.");
2584   }
2585   disable_register_stack_guard();
2586 }
2587 
2588 void JavaThread::enable_stack_yellow_reserved_zone() {
2589   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2590   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
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_red_zone_base();
2595 
2596   guarantee(base < stack_base(), "Error calculating stack yellow zone");
2597   guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2598 
2599   if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2600     _stack_guard_state = stack_guard_enabled;
2601   } else {
2602     warning("Attempt to guard stack yellow zone failed.");
2603   }
2604   enable_register_stack_guard();
2605 }
2606 
2607 void JavaThread::disable_stack_yellow_reserved_zone() {
2608   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2609   assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2610 
2611   // Simply return if called for a thread that does not use guard pages.
2612   if (_stack_guard_state == stack_guard_unused) return;
2613 
2614   // The base notation is from the stacks point of view, growing downward.
2615   // We need to adjust it to work correctly with guard_memory()
2616   address base = stack_red_zone_base();
2617 
2618   if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2619     _stack_guard_state = stack_guard_yellow_reserved_disabled;
2620   } else {
2621     warning("Attempt to unguard stack yellow zone failed.");
2622   }
2623   disable_register_stack_guard();
2624 }
2625 
2626 void JavaThread::enable_stack_red_zone() {
2627   // The base notation is from the stacks point of view, growing downward.
2628   // We need to adjust it to work correctly with guard_memory()
2629   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2630   address base = stack_red_zone_base() - stack_red_zone_size();
2631 
2632   guarantee(base < stack_base(), "Error calculating stack red zone");
2633   guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2634 
2635   if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2636     warning("Attempt to guard stack red zone failed.");
2637   }
2638 }
2639 
2640 void JavaThread::disable_stack_red_zone() {
2641   // The base notation is from the stacks point of view, growing downward.
2642   // We need to adjust it to work correctly with guard_memory()
2643   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2644   address base = stack_red_zone_base() - stack_red_zone_size();
2645   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2646     warning("Attempt to unguard stack red zone failed.");
2647   }
2648 }
2649 
2650 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2651   // ignore is there is no stack
2652   if (!has_last_Java_frame()) return;
2653   // traverse the stack frames. Starts from top frame.
2654   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2655     frame* fr = fst.current();
2656     f(fr, fst.register_map());
2657   }
2658 }
2659 
2660 
2661 #ifndef PRODUCT
2662 // Deoptimization
2663 // Function for testing deoptimization
2664 void JavaThread::deoptimize() {
2665   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2666   StackFrameStream fst(this, UseBiasedLocking);
2667   bool deopt = false;           // Dump stack only if a deopt actually happens.
2668   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2669   // Iterate over all frames in the thread and deoptimize
2670   for (; !fst.is_done(); fst.next()) {
2671     if (fst.current()->can_be_deoptimized()) {
2672 
2673       if (only_at) {
2674         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
2675         // consists of comma or carriage return separated numbers so
2676         // search for the current bci in that string.
2677         address pc = fst.current()->pc();
2678         nmethod* nm =  (nmethod*) fst.current()->cb();
2679         ScopeDesc* sd = nm->scope_desc_at(pc);
2680         char buffer[8];
2681         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2682         size_t len = strlen(buffer);
2683         const char * found = strstr(DeoptimizeOnlyAt, buffer);
2684         while (found != NULL) {
2685           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2686               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2687             // Check that the bci found is bracketed by terminators.
2688             break;
2689           }
2690           found = strstr(found + 1, buffer);
2691         }
2692         if (!found) {
2693           continue;
2694         }
2695       }
2696 
2697       if (DebugDeoptimization && !deopt) {
2698         deopt = true; // One-time only print before deopt
2699         tty->print_cr("[BEFORE Deoptimization]");
2700         trace_frames();
2701         trace_stack();
2702       }
2703       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2704     }
2705   }
2706 
2707   if (DebugDeoptimization && deopt) {
2708     tty->print_cr("[AFTER Deoptimization]");
2709     trace_frames();
2710   }
2711 }
2712 
2713 
2714 // Make zombies
2715 void JavaThread::make_zombies() {
2716   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2717     if (fst.current()->can_be_deoptimized()) {
2718       // it is a Java nmethod
2719       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2720       nm->make_not_entrant();
2721     }
2722   }
2723 }
2724 #endif // PRODUCT
2725 
2726 
2727 void JavaThread::deoptimized_wrt_marked_nmethods() {
2728   if (!has_last_Java_frame()) return;
2729   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2730   StackFrameStream fst(this, UseBiasedLocking);
2731   for (; !fst.is_done(); fst.next()) {
2732     if (fst.current()->should_be_deoptimized()) {
2733       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2734     }
2735   }
2736 }
2737 
2738 
2739 // If the caller is a NamedThread, then remember, in the current scope,
2740 // the given JavaThread in its _processed_thread field.
2741 class RememberProcessedThread: public StackObj {
2742   NamedThread* _cur_thr;
2743  public:
2744   RememberProcessedThread(JavaThread* jthr) {
2745     Thread* thread = Thread::current();
2746     if (thread->is_Named_thread()) {
2747       _cur_thr = (NamedThread *)thread;
2748       _cur_thr->set_processed_thread(jthr);
2749     } else {
2750       _cur_thr = NULL;
2751     }
2752   }
2753 
2754   ~RememberProcessedThread() {
2755     if (_cur_thr) {
2756       _cur_thr->set_processed_thread(NULL);
2757     }
2758   }
2759 };
2760 
2761 void JavaThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
2762   // Verify that the deferred card marks have been flushed.
2763   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2764 
2765   // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2766   // since there may be more than one thread using each ThreadProfiler.
2767 
2768   // Traverse the GCHandles
2769   Thread::oops_do(f, cld_f, cf);
2770 
2771   JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2772 
2773   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2774          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2775 
2776   if (has_last_Java_frame()) {
2777     // Record JavaThread to GC thread
2778     RememberProcessedThread rpt(this);
2779 
2780     // Traverse the privileged stack
2781     if (_privileged_stack_top != NULL) {
2782       _privileged_stack_top->oops_do(f);
2783     }
2784 
2785     // traverse the registered growable array
2786     if (_array_for_gc != NULL) {
2787       for (int index = 0; index < _array_for_gc->length(); index++) {
2788         f->do_oop(_array_for_gc->adr_at(index));
2789       }
2790     }
2791 
2792     // Traverse the monitor chunks
2793     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2794       chunk->oops_do(f);
2795     }
2796 
2797     // Traverse the execution stack
2798     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2799       fst.current()->oops_do(f, cld_f, cf, fst.register_map());
2800     }
2801   }
2802 
2803   // callee_target is never live across a gc point so NULL it here should
2804   // it still contain a methdOop.
2805 
2806   set_callee_target(NULL);
2807 
2808   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2809   // If we have deferred set_locals there might be oops waiting to be
2810   // written
2811   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2812   if (list != NULL) {
2813     for (int i = 0; i < list->length(); i++) {
2814       list->at(i)->oops_do(f);
2815     }
2816   }
2817 
2818   // Traverse instance variables at the end since the GC may be moving things
2819   // around using this function
2820   f->do_oop((oop*) &_threadObj);
2821   f->do_oop((oop*) &_vm_result);
2822   f->do_oop((oop*) &_exception_oop);
2823   f->do_oop((oop*) &_pending_async_exception);
2824 
2825   if (jvmti_thread_state() != NULL) {
2826     jvmti_thread_state()->oops_do(f);
2827   }
2828 }
2829 
2830 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2831   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2832          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2833 
2834   if (has_last_Java_frame()) {
2835     // Traverse the execution stack
2836     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2837       fst.current()->nmethods_do(cf);
2838     }
2839   }
2840 }
2841 
2842 void JavaThread::metadata_do(void f(Metadata*)) {
2843   if (has_last_Java_frame()) {
2844     // Traverse the execution stack to call f() on the methods in the stack
2845     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2846       fst.current()->metadata_do(f);
2847     }
2848   } else if (is_Compiler_thread()) {
2849     // need to walk ciMetadata in current compile tasks to keep alive.
2850     CompilerThread* ct = (CompilerThread*)this;
2851     if (ct->env() != NULL) {
2852       ct->env()->metadata_do(f);
2853     }
2854     if (ct->task() != NULL) {
2855       ct->task()->metadata_do(f);
2856     }
2857   }
2858 }
2859 
2860 // Printing
2861 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2862   switch (_thread_state) {
2863   case _thread_uninitialized:     return "_thread_uninitialized";
2864   case _thread_new:               return "_thread_new";
2865   case _thread_new_trans:         return "_thread_new_trans";
2866   case _thread_in_native:         return "_thread_in_native";
2867   case _thread_in_native_trans:   return "_thread_in_native_trans";
2868   case _thread_in_vm:             return "_thread_in_vm";
2869   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
2870   case _thread_in_Java:           return "_thread_in_Java";
2871   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
2872   case _thread_blocked:           return "_thread_blocked";
2873   case _thread_blocked_trans:     return "_thread_blocked_trans";
2874   default:                        return "unknown thread state";
2875   }
2876 }
2877 
2878 #ifndef PRODUCT
2879 void JavaThread::print_thread_state_on(outputStream *st) const {
2880   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
2881 };
2882 void JavaThread::print_thread_state() const {
2883   print_thread_state_on(tty);
2884 }
2885 #endif // PRODUCT
2886 
2887 // Called by Threads::print() for VM_PrintThreads operation
2888 void JavaThread::print_on(outputStream *st) const {
2889   st->print_raw("\"");
2890   st->print_raw(get_thread_name());
2891   st->print_raw("\" ");
2892   oop thread_oop = threadObj();
2893   if (thread_oop != NULL) {
2894     st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop));
2895     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
2896     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2897   }
2898   Thread::print_on(st);
2899   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2900   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2901   if (thread_oop != NULL) {
2902     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2903   }
2904 #ifndef PRODUCT
2905   print_thread_state_on(st);
2906   _safepoint_state->print_on(st);
2907 #endif // PRODUCT
2908   if (is_Compiler_thread()) {
2909     CompilerThread* ct = (CompilerThread*)this;
2910     if (ct->task() != NULL) {
2911       st->print("   Compiling: ");
2912       ct->task()->print(st, NULL, true, false);
2913     } else {
2914       st->print("   No compile task");
2915     }
2916     st->cr();
2917   }
2918 }
2919 
2920 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2921   st->print("%s", get_thread_name_string(buf, buflen));
2922 }
2923 
2924 // Called by fatal error handler. The difference between this and
2925 // JavaThread::print() is that we can't grab lock or allocate memory.
2926 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2927   st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2928   oop thread_obj = threadObj();
2929   if (thread_obj != NULL) {
2930     if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2931   }
2932   st->print(" [");
2933   st->print("%s", _get_thread_state_name(_thread_state));
2934   if (osthread()) {
2935     st->print(", id=%d", osthread()->thread_id());
2936   }
2937   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2938             p2i(stack_end()), p2i(stack_base()));
2939   st->print("]");
2940   return;
2941 }
2942 
2943 // Verification
2944 
2945 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2946 
2947 void JavaThread::verify() {
2948   // Verify oops in the thread.
2949   oops_do(&VerifyOopClosure::verify_oop, NULL, NULL);
2950 
2951   // Verify the stack frames.
2952   frames_do(frame_verify);
2953 }
2954 
2955 // CR 6300358 (sub-CR 2137150)
2956 // Most callers of this method assume that it can't return NULL but a
2957 // thread may not have a name whilst it is in the process of attaching to
2958 // the VM - see CR 6412693, and there are places where a JavaThread can be
2959 // seen prior to having it's threadObj set (eg JNI attaching threads and
2960 // if vm exit occurs during initialization). These cases can all be accounted
2961 // for such that this method never returns NULL.
2962 const char* JavaThread::get_thread_name() const {
2963 #ifdef ASSERT
2964   // early safepoints can hit while current thread does not yet have TLS
2965   if (!SafepointSynchronize::is_at_safepoint()) {
2966     Thread *cur = Thread::current();
2967     if (!(cur->is_Java_thread() && cur == this)) {
2968       // Current JavaThreads are allowed to get their own name without
2969       // the Threads_lock.
2970       assert_locked_or_safepoint(Threads_lock);
2971     }
2972   }
2973 #endif // ASSERT
2974   return get_thread_name_string();
2975 }
2976 
2977 // Returns a non-NULL representation of this thread's name, or a suitable
2978 // descriptive string if there is no set name
2979 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2980   const char* name_str;
2981   oop thread_obj = threadObj();
2982   if (thread_obj != NULL) {
2983     oop name = java_lang_Thread::name(thread_obj);
2984     if (name != NULL) {
2985       if (buf == NULL) {
2986         name_str = java_lang_String::as_utf8_string(name);
2987       } else {
2988         name_str = java_lang_String::as_utf8_string(name, buf, buflen);
2989       }
2990     } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
2991       name_str = "<no-name - thread is attaching>";
2992     } else {
2993       name_str = Thread::name();
2994     }
2995   } else {
2996     name_str = Thread::name();
2997   }
2998   assert(name_str != NULL, "unexpected NULL thread name");
2999   return name_str;
3000 }
3001 
3002 
3003 const char* JavaThread::get_threadgroup_name() const {
3004   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3005   oop thread_obj = threadObj();
3006   if (thread_obj != NULL) {
3007     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3008     if (thread_group != NULL) {
3009       // ThreadGroup.name can be null
3010       return java_lang_ThreadGroup::name(thread_group);
3011     }
3012   }
3013   return NULL;
3014 }
3015 
3016 const char* JavaThread::get_parent_name() const {
3017   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3018   oop thread_obj = threadObj();
3019   if (thread_obj != NULL) {
3020     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3021     if (thread_group != NULL) {
3022       oop parent = java_lang_ThreadGroup::parent(thread_group);
3023       if (parent != NULL) {
3024         // ThreadGroup.name can be null
3025         return java_lang_ThreadGroup::name(parent);
3026       }
3027     }
3028   }
3029   return NULL;
3030 }
3031 
3032 ThreadPriority JavaThread::java_priority() const {
3033   oop thr_oop = threadObj();
3034   if (thr_oop == NULL) return NormPriority; // Bootstrapping
3035   ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3036   assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3037   return priority;
3038 }
3039 
3040 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3041 
3042   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3043   // Link Java Thread object <-> C++ Thread
3044 
3045   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3046   // and put it into a new Handle.  The Handle "thread_oop" can then
3047   // be used to pass the C++ thread object to other methods.
3048 
3049   // Set the Java level thread object (jthread) field of the
3050   // new thread (a JavaThread *) to C++ thread object using the
3051   // "thread_oop" handle.
3052 
3053   // Set the thread field (a JavaThread *) of the
3054   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3055 
3056   Handle thread_oop(Thread::current(),
3057                     JNIHandles::resolve_non_null(jni_thread));
3058   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3059          "must be initialized");
3060   set_threadObj(thread_oop());
3061   java_lang_Thread::set_thread(thread_oop(), this);
3062 
3063   if (prio == NoPriority) {
3064     prio = java_lang_Thread::priority(thread_oop());
3065     assert(prio != NoPriority, "A valid priority should be present");
3066   }
3067 
3068   // Push the Java priority down to the native thread; needs Threads_lock
3069   Thread::set_priority(this, prio);
3070 
3071   prepare_ext();
3072 
3073   // Add the new thread to the Threads list and set it in motion.
3074   // We must have threads lock in order to call Threads::add.
3075   // It is crucial that we do not block before the thread is
3076   // added to the Threads list for if a GC happens, then the java_thread oop
3077   // will not be visited by GC.
3078   Threads::add(this);
3079 }
3080 
3081 oop JavaThread::current_park_blocker() {
3082   // Support for JSR-166 locks
3083   oop thread_oop = threadObj();
3084   if (thread_oop != NULL &&
3085       JDK_Version::current().supports_thread_park_blocker()) {
3086     return java_lang_Thread::park_blocker(thread_oop);
3087   }
3088   return NULL;
3089 }
3090 
3091 
3092 void JavaThread::print_stack_on(outputStream* st) {
3093   if (!has_last_Java_frame()) return;
3094   ResourceMark rm;
3095   HandleMark   hm;
3096 
3097   RegisterMap reg_map(this);
3098   vframe* start_vf = last_java_vframe(&reg_map);
3099   int count = 0;
3100   for (vframe* f = start_vf; f; f = f->sender()) {
3101     if (f->is_java_frame()) {
3102       javaVFrame* jvf = javaVFrame::cast(f);
3103       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3104 
3105       // Print out lock information
3106       if (JavaMonitorsInStackTrace) {
3107         jvf->print_lock_info_on(st, count);
3108       }
3109     } else {
3110       // Ignore non-Java frames
3111     }
3112 
3113     // Bail-out case for too deep stacks
3114     count++;
3115     if (MaxJavaStackTraceDepth == count) return;
3116   }
3117 }
3118 
3119 
3120 // JVMTI PopFrame support
3121 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3122   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3123   if (in_bytes(size_in_bytes) != 0) {
3124     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3125     _popframe_preserved_args_size = in_bytes(size_in_bytes);
3126     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3127   }
3128 }
3129 
3130 void* JavaThread::popframe_preserved_args() {
3131   return _popframe_preserved_args;
3132 }
3133 
3134 ByteSize JavaThread::popframe_preserved_args_size() {
3135   return in_ByteSize(_popframe_preserved_args_size);
3136 }
3137 
3138 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3139   int sz = in_bytes(popframe_preserved_args_size());
3140   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3141   return in_WordSize(sz / wordSize);
3142 }
3143 
3144 void JavaThread::popframe_free_preserved_args() {
3145   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3146   FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3147   _popframe_preserved_args = NULL;
3148   _popframe_preserved_args_size = 0;
3149 }
3150 
3151 #ifndef PRODUCT
3152 
3153 void JavaThread::trace_frames() {
3154   tty->print_cr("[Describe stack]");
3155   int frame_no = 1;
3156   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3157     tty->print("  %d. ", frame_no++);
3158     fst.current()->print_value_on(tty, this);
3159     tty->cr();
3160   }
3161 }
3162 
3163 class PrintAndVerifyOopClosure: public OopClosure {
3164  protected:
3165   template <class T> inline void do_oop_work(T* p) {
3166     oop obj = oopDesc::load_decode_heap_oop(p);
3167     if (obj == NULL) return;
3168     tty->print(INTPTR_FORMAT ": ", p2i(p));
3169     if (obj->is_oop_or_null()) {
3170       if (obj->is_objArray()) {
3171         tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3172       } else {
3173         obj->print();
3174       }
3175     } else {
3176       tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3177     }
3178     tty->cr();
3179   }
3180  public:
3181   virtual void do_oop(oop* p) { do_oop_work(p); }
3182   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
3183 };
3184 
3185 
3186 static void oops_print(frame* f, const RegisterMap *map) {
3187   PrintAndVerifyOopClosure print;
3188   f->print_value();
3189   f->oops_do(&print, NULL, NULL, (RegisterMap*)map);
3190 }
3191 
3192 // Print our all the locations that contain oops and whether they are
3193 // valid or not.  This useful when trying to find the oldest frame
3194 // where an oop has gone bad since the frame walk is from youngest to
3195 // oldest.
3196 void JavaThread::trace_oops() {
3197   tty->print_cr("[Trace oops]");
3198   frames_do(oops_print);
3199 }
3200 
3201 
3202 #ifdef ASSERT
3203 // Print or validate the layout of stack frames
3204 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3205   ResourceMark rm;
3206   PRESERVE_EXCEPTION_MARK;
3207   FrameValues values;
3208   int frame_no = 0;
3209   for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3210     fst.current()->describe(values, ++frame_no);
3211     if (depth == frame_no) break;
3212   }
3213   if (validate_only) {
3214     values.validate();
3215   } else {
3216     tty->print_cr("[Describe stack layout]");
3217     values.print(this);
3218   }
3219 }
3220 #endif
3221 
3222 void JavaThread::trace_stack_from(vframe* start_vf) {
3223   ResourceMark rm;
3224   int vframe_no = 1;
3225   for (vframe* f = start_vf; f; f = f->sender()) {
3226     if (f->is_java_frame()) {
3227       javaVFrame::cast(f)->print_activation(vframe_no++);
3228     } else {
3229       f->print();
3230     }
3231     if (vframe_no > StackPrintLimit) {
3232       tty->print_cr("...<more frames>...");
3233       return;
3234     }
3235   }
3236 }
3237 
3238 
3239 void JavaThread::trace_stack() {
3240   if (!has_last_Java_frame()) return;
3241   ResourceMark rm;
3242   HandleMark   hm;
3243   RegisterMap reg_map(this);
3244   trace_stack_from(last_java_vframe(&reg_map));
3245 }
3246 
3247 
3248 #endif // PRODUCT
3249 
3250 
3251 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3252   assert(reg_map != NULL, "a map must be given");
3253   frame f = last_frame();
3254   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3255     if (vf->is_java_frame()) return javaVFrame::cast(vf);
3256   }
3257   return NULL;
3258 }
3259 
3260 
3261 Klass* JavaThread::security_get_caller_class(int depth) {
3262   vframeStream vfst(this);
3263   vfst.security_get_caller_frame(depth);
3264   if (!vfst.at_end()) {
3265     return vfst.method()->method_holder();
3266   }
3267   return NULL;
3268 }
3269 
3270 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3271   assert(thread->is_Compiler_thread(), "must be compiler thread");
3272   CompileBroker::compiler_thread_loop();
3273 }
3274 
3275 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3276   NMethodSweeper::sweeper_loop();
3277 }
3278 
3279 // Create a CompilerThread
3280 CompilerThread::CompilerThread(CompileQueue* queue,
3281                                CompilerCounters* counters)
3282                                : JavaThread(&compiler_thread_entry) {
3283   _env   = NULL;
3284   _log   = NULL;
3285   _task  = NULL;
3286   _queue = queue;
3287   _counters = counters;
3288   _buffer_blob = NULL;
3289   _compiler = NULL;
3290 
3291 #ifndef PRODUCT
3292   _ideal_graph_printer = NULL;
3293 #endif
3294 }
3295 
3296 bool CompilerThread::can_call_java() const {
3297   return _compiler != NULL && _compiler->is_jvmci();
3298 }
3299 
3300 // Create sweeper thread
3301 CodeCacheSweeperThread::CodeCacheSweeperThread()
3302 : JavaThread(&sweeper_thread_entry) {
3303   _scanned_nmethod = NULL;
3304 }
3305 
3306 void CodeCacheSweeperThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
3307   JavaThread::oops_do(f, cld_f, cf);
3308   if (_scanned_nmethod != NULL && cf != NULL) {
3309     // Safepoints can occur when the sweeper is scanning an nmethod so
3310     // process it here to make sure it isn't unloaded in the middle of
3311     // a scan.
3312     cf->do_code_blob(_scanned_nmethod);
3313   }
3314 }
3315 
3316 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3317   JavaThread::nmethods_do(cf);
3318   if (_scanned_nmethod != NULL && cf != NULL) {
3319     // Safepoints can occur when the sweeper is scanning an nmethod so
3320     // process it here to make sure it isn't unloaded in the middle of
3321     // a scan.
3322     cf->do_code_blob(_scanned_nmethod);
3323   }
3324 }
3325 
3326 
3327 // ======= Threads ========
3328 
3329 // The Threads class links together all active threads, and provides
3330 // operations over all threads.  It is protected by its own Mutex
3331 // lock, which is also used in other contexts to protect thread
3332 // operations from having the thread being operated on from exiting
3333 // and going away unexpectedly (e.g., safepoint synchronization)
3334 
3335 JavaThread* Threads::_thread_list = NULL;
3336 int         Threads::_number_of_threads = 0;
3337 int         Threads::_number_of_non_daemon_threads = 0;
3338 int         Threads::_return_code = 0;
3339 int         Threads::_thread_claim_parity = 0;
3340 size_t      JavaThread::_stack_size_at_create = 0;
3341 #ifdef ASSERT
3342 bool        Threads::_vm_complete = false;
3343 #endif
3344 
3345 // All JavaThreads
3346 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3347 
3348 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3349 void Threads::threads_do(ThreadClosure* tc) {
3350   assert_locked_or_safepoint(Threads_lock);
3351   // ALL_JAVA_THREADS iterates through all JavaThreads
3352   ALL_JAVA_THREADS(p) {
3353     tc->do_thread(p);
3354   }
3355   // Someday we could have a table or list of all non-JavaThreads.
3356   // For now, just manually iterate through them.
3357   tc->do_thread(VMThread::vm_thread());
3358   Universe::heap()->gc_threads_do(tc);
3359   WatcherThread *wt = WatcherThread::watcher_thread();
3360   // Strictly speaking, the following NULL check isn't sufficient to make sure
3361   // the data for WatcherThread is still valid upon being examined. However,
3362   // considering that WatchThread terminates when the VM is on the way to
3363   // exit at safepoint, the chance of the above is extremely small. The right
3364   // way to prevent termination of WatcherThread would be to acquire
3365   // Terminator_lock, but we can't do that without violating the lock rank
3366   // checking in some cases.
3367   if (wt != NULL) {
3368     tc->do_thread(wt);
3369   }
3370 
3371   // If CompilerThreads ever become non-JavaThreads, add them here
3372 }
3373 
3374 // The system initialization in the library has three phases.
3375 //
3376 // Phase 1: java.lang.System class initialization
3377 //     java.lang.System is a primordial class loaded and initialized
3378 //     by the VM early during startup.  java.lang.System.<clinit>
3379 //     only does registerNatives and keeps the rest of the class
3380 //     initialization work later until thread initialization completes.
3381 //
3382 //     System.initPhase1 initializes the system properties, the static
3383 //     fields in, out, and err. Set up java signal handlers, OS-specific
3384 //     system settings, and thread group of the main thread.
3385 static void call_initPhase1(TRAPS) {
3386   Klass* k =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3387   instanceKlassHandle klass (THREAD, k);
3388 
3389   JavaValue result(T_VOID);
3390   JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3391                                          vmSymbols::void_method_signature(), CHECK);
3392 }
3393 
3394 // Phase 2. Module system initialization
3395 //     This will initialize the module system.  Only java.base classes
3396 //     can be loaded until phase 2 completes.
3397 //
3398 //     Call System.initPhase2 after the compiler initialization and jsr292
3399 //     classes get initialized because module initialization runs a lot of java
3400 //     code, that for performance reasons, should be compiled.  Also, this will
3401 //     enable the startup code to use lambda and other language features in this
3402 //     phase and onward.
3403 //
3404 //     After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3405 static void call_initPhase2(TRAPS) {
3406   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3407   instanceKlassHandle klass (THREAD, k);
3408 
3409   JavaValue result(T_VOID);
3410   JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3411                                          vmSymbols::void_method_signature(), CHECK);
3412   universe_post_module_init();
3413 }
3414 
3415 // Phase 3. final setup - set security manager, system class loader and TCCL
3416 //
3417 //     This will instantiate and set the security manager, set the system class
3418 //     loader as well as the thread context class loader.  The security manager
3419 //     and system class loader may be a custom class loaded from -Xbootclasspath/a,
3420 //     other modules or the application's classpath.
3421 static void call_initPhase3(TRAPS) {
3422   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3423   instanceKlassHandle klass (THREAD, k);
3424 
3425   JavaValue result(T_VOID);
3426   JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3427                                          vmSymbols::void_method_signature(), CHECK);
3428 }
3429 
3430 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3431   TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3432 
3433   if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3434     create_vm_init_libraries();
3435   }
3436 
3437   initialize_class(vmSymbols::java_lang_String(), CHECK);
3438 
3439   // Inject CompactStrings value after the static initializers for String ran.
3440   java_lang_String::set_compact_strings(CompactStrings);
3441 
3442   // Initialize java_lang.System (needed before creating the thread)
3443   initialize_class(vmSymbols::java_lang_System(), CHECK);
3444   // The VM creates & returns objects of this class. Make sure it's initialized.
3445   initialize_class(vmSymbols::java_lang_Class(), CHECK);
3446   initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3447   Handle thread_group = create_initial_thread_group(CHECK);
3448   Universe::set_main_thread_group(thread_group());
3449   initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3450   oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3451   main_thread->set_threadObj(thread_object);
3452   // Set thread status to running since main thread has
3453   // been started and running.
3454   java_lang_Thread::set_thread_status(thread_object,
3455                                       java_lang_Thread::RUNNABLE);
3456 
3457   // The VM creates objects of this class.
3458   initialize_class(vmSymbols::java_lang_reflect_Module(), CHECK);
3459 
3460   // The VM preresolves methods to these classes. Make sure that they get initialized
3461   initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3462   initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3463 
3464   // Phase 1 of the system initialization in the library, java.lang.System class initialization
3465   call_initPhase1(CHECK);
3466 
3467   // get the Java runtime name after java.lang.System is initialized
3468   JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3469   JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3470 
3471   // an instance of OutOfMemory exception has been allocated earlier
3472   initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3473   initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3474   initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3475   initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3476   initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3477   initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3478   initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3479   initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3480 }
3481 
3482 void Threads::initialize_jsr292_core_classes(TRAPS) {
3483   TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3484 
3485   initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3486   initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3487   initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3488 }
3489 
3490 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3491   extern void JDK_Version_init();
3492 
3493   // Preinitialize version info.
3494   VM_Version::early_initialize();
3495 
3496   // Check version
3497   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3498 
3499   // Initialize library-based TLS
3500   ThreadLocalStorage::init();
3501 
3502   // Initialize the output stream module
3503   ostream_init();
3504 
3505   // Process java launcher properties.
3506   Arguments::process_sun_java_launcher_properties(args);
3507 
3508   // Initialize the os module
3509   os::init();
3510 
3511   // Record VM creation timing statistics
3512   TraceVmCreationTime create_vm_timer;
3513   create_vm_timer.start();
3514 
3515   // Initialize system properties.
3516   Arguments::init_system_properties();
3517 
3518   // So that JDK version can be used as a discriminator when parsing arguments
3519   JDK_Version_init();
3520 
3521   // Update/Initialize System properties after JDK version number is known
3522   Arguments::init_version_specific_system_properties();
3523 
3524   // Make sure to initialize log configuration *before* parsing arguments
3525   LogConfiguration::initialize(create_vm_timer.begin_time());
3526 
3527   // Parse arguments
3528   jint parse_result = Arguments::parse(args);
3529   if (parse_result != JNI_OK) return parse_result;
3530 
3531   os::init_before_ergo();
3532 
3533   jint ergo_result = Arguments::apply_ergo();
3534   if (ergo_result != JNI_OK) return ergo_result;
3535 
3536   // Final check of all ranges after ergonomics which may change values.
3537   if (!CommandLineFlagRangeList::check_ranges()) {
3538     return JNI_EINVAL;
3539   }
3540 
3541   // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3542   bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3543   if (!constraint_result) {
3544     return JNI_EINVAL;
3545   }
3546 
3547   if (PauseAtStartup) {
3548     os::pause();
3549   }
3550 
3551   HOTSPOT_VM_INIT_BEGIN();
3552 
3553   // Timing (must come after argument parsing)
3554   TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3555 
3556   // Initialize the os module after parsing the args
3557   jint os_init_2_result = os::init_2();
3558   if (os_init_2_result != JNI_OK) return os_init_2_result;
3559 
3560   jint adjust_after_os_result = Arguments::adjust_after_os();
3561   if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3562 
3563   // Initialize output stream logging
3564   ostream_init_log();
3565 
3566   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3567   // Must be before create_vm_init_agents()
3568   if (Arguments::init_libraries_at_startup()) {
3569     convert_vm_init_libraries_to_agents();
3570   }
3571 
3572   // Launch -agentlib/-agentpath and converted -Xrun agents
3573   if (Arguments::init_agents_at_startup()) {
3574     create_vm_init_agents();
3575   }
3576 
3577   // Initialize Threads state
3578   _thread_list = NULL;
3579   _number_of_threads = 0;
3580   _number_of_non_daemon_threads = 0;
3581 
3582   // Initialize global data structures and create system classes in heap
3583   vm_init_globals();
3584 
3585 #if INCLUDE_JVMCI
3586   if (JVMCICounterSize > 0) {
3587     JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3588     memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3589   } else {
3590     JavaThread::_jvmci_old_thread_counters = NULL;
3591   }
3592 #endif // INCLUDE_JVMCI
3593 
3594   // Attach the main thread to this os thread
3595   JavaThread* main_thread = new JavaThread();
3596   main_thread->set_thread_state(_thread_in_vm);
3597   main_thread->initialize_thread_current();
3598   // must do this before set_active_handles
3599   main_thread->record_stack_base_and_size();
3600   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3601 
3602   if (!main_thread->set_as_starting_thread()) {
3603     vm_shutdown_during_initialization(
3604                                       "Failed necessary internal allocation. Out of swap space");
3605     delete main_thread;
3606     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3607     return JNI_ENOMEM;
3608   }
3609 
3610   // Enable guard page *after* os::create_main_thread(), otherwise it would
3611   // crash Linux VM, see notes in os_linux.cpp.
3612   main_thread->create_stack_guard_pages();
3613 
3614   // Initialize Java-Level synchronization subsystem
3615   ObjectMonitor::Initialize();
3616 
3617   // Initialize global modules
3618   jint status = init_globals();
3619   if (status != JNI_OK) {
3620     delete main_thread;
3621     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3622     return status;
3623   }
3624 
3625   if (TRACE_INITIALIZE() != JNI_OK) {
3626     vm_exit_during_initialization("Failed to initialize tracing backend");
3627   }
3628 
3629   // Should be done after the heap is fully created
3630   main_thread->cache_global_variables();
3631 
3632   HandleMark hm;
3633 
3634   { MutexLocker mu(Threads_lock);
3635     Threads::add(main_thread);
3636   }
3637 
3638   // Any JVMTI raw monitors entered in onload will transition into
3639   // real raw monitor. VM is setup enough here for raw monitor enter.
3640   JvmtiExport::transition_pending_onload_raw_monitors();
3641 
3642   // Create the VMThread
3643   { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3644 
3645   VMThread::create();
3646     Thread* vmthread = VMThread::vm_thread();
3647 
3648     if (!os::create_thread(vmthread, os::vm_thread)) {
3649       vm_exit_during_initialization("Cannot create VM thread. "
3650                                     "Out of system resources.");
3651     }
3652 
3653     // Wait for the VM thread to become ready, and VMThread::run to initialize
3654     // Monitors can have spurious returns, must always check another state flag
3655     {
3656       MutexLocker ml(Notify_lock);
3657       os::start_thread(vmthread);
3658       while (vmthread->active_handles() == NULL) {
3659         Notify_lock->wait();
3660       }
3661     }
3662   }
3663 
3664   assert(Universe::is_fully_initialized(), "not initialized");
3665   if (VerifyDuringStartup) {
3666     // Make sure we're starting with a clean slate.
3667     VM_Verify verify_op;
3668     VMThread::execute(&verify_op);
3669   }
3670 
3671   Thread* THREAD = Thread::current();
3672 
3673   // At this point, the Universe is initialized, but we have not executed
3674   // any byte code.  Now is a good time (the only time) to dump out the
3675   // internal state of the JVM for sharing.
3676   if (DumpSharedSpaces) {
3677     MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3678     ShouldNotReachHere();
3679   }
3680 
3681   // Always call even when there are not JVMTI environments yet, since environments
3682   // may be attached late and JVMTI must track phases of VM execution
3683   JvmtiExport::enter_early_start_phase();
3684 
3685   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3686   JvmtiExport::post_early_vm_start();
3687 
3688   initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3689 
3690   // We need this for ClassDataSharing - the initial vm.info property is set
3691   // with the default value of CDS "sharing" which may be reset through
3692   // command line options.
3693   reset_vm_info_property(CHECK_JNI_ERR);
3694 
3695   quicken_jni_functions();
3696 
3697   // No more stub generation allowed after that point.
3698   StubCodeDesc::freeze();
3699 
3700   // Set flag that basic initialization has completed. Used by exceptions and various
3701   // debug stuff, that does not work until all basic classes have been initialized.
3702   set_init_completed();
3703 
3704   LogConfiguration::post_initialize();
3705   Metaspace::post_initialize();
3706 
3707   HOTSPOT_VM_INIT_END();
3708 
3709   // record VM initialization completion time
3710 #if INCLUDE_MANAGEMENT
3711   Management::record_vm_init_completed();
3712 #endif // INCLUDE_MANAGEMENT
3713 
3714   // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
3715   // set_init_completed has just been called, causing exceptions not to be shortcut
3716   // anymore. We call vm_exit_during_initialization directly instead.
3717 
3718   // Initialize reference pending list locker
3719   bool needs_locker_thread = Universe::heap()->needs_reference_pending_list_locker_thread();
3720   ReferencePendingListLocker::initialize(needs_locker_thread, CHECK_JNI_ERR);
3721 
3722   // Signal Dispatcher needs to be started before VMInit event is posted
3723   os::signal_init();
3724 
3725   // Start Attach Listener if +StartAttachListener or it can't be started lazily
3726   if (!DisableAttachMechanism) {
3727     AttachListener::vm_start();
3728     if (StartAttachListener || AttachListener::init_at_startup()) {
3729       AttachListener::init();
3730     }
3731   }
3732 
3733   // Launch -Xrun agents
3734   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3735   // back-end can launch with -Xdebug -Xrunjdwp.
3736   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3737     create_vm_init_libraries();
3738   }
3739 
3740   if (CleanChunkPoolAsync) {
3741     Chunk::start_chunk_pool_cleaner_task();
3742   }
3743 
3744   // initialize compiler(s)
3745 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI
3746   CompileBroker::compilation_init(CHECK_JNI_ERR);
3747 #endif
3748 
3749   // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3750   // It is done after compilers are initialized, because otherwise compilations of
3751   // signature polymorphic MH intrinsics can be missed
3752   // (see SystemDictionary::find_method_handle_intrinsic).
3753   initialize_jsr292_core_classes(CHECK_JNI_ERR);
3754 
3755   // This will initialize the module system.  Only java.base classes can be
3756   // loaded until phase 2 completes
3757   call_initPhase2(CHECK_JNI_ERR);
3758 
3759   // Always call even when there are not JVMTI environments yet, since environments
3760   // may be attached late and JVMTI must track phases of VM execution
3761   JvmtiExport::enter_start_phase();
3762 
3763   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3764   JvmtiExport::post_vm_start();
3765 
3766   // Final system initialization including security manager and system class loader
3767   call_initPhase3(CHECK_JNI_ERR);
3768 
3769   // cache the system class loader
3770   SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR));
3771 
3772   // Always call even when there are not JVMTI environments yet, since environments
3773   // may be attached late and JVMTI must track phases of VM execution
3774   JvmtiExport::enter_live_phase();
3775 
3776   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3777   JvmtiExport::post_vm_initialized();
3778 
3779   if (TRACE_START() != JNI_OK) {
3780     vm_exit_during_initialization("Failed to start tracing backend.");
3781   }
3782 
3783 #if INCLUDE_MANAGEMENT
3784   Management::initialize(THREAD);
3785 
3786   if (HAS_PENDING_EXCEPTION) {
3787     // management agent fails to start possibly due to
3788     // configuration problem and is responsible for printing
3789     // stack trace if appropriate. Simply exit VM.
3790     vm_exit(1);
3791   }
3792 #endif // INCLUDE_MANAGEMENT
3793 
3794   if (Arguments::has_profile())       FlatProfiler::engage(main_thread, true);
3795   if (MemProfiling)                   MemProfiler::engage();
3796   StatSampler::engage();
3797   if (CheckJNICalls)                  JniPeriodicChecker::engage();
3798 
3799   BiasedLocking::init();
3800 
3801 #if INCLUDE_RTM_OPT
3802   RTMLockingCounters::init();
3803 #endif
3804 
3805   if (JDK_Version::current().post_vm_init_hook_enabled()) {
3806     call_postVMInitHook(THREAD);
3807     // The Java side of PostVMInitHook.run must deal with all
3808     // exceptions and provide means of diagnosis.
3809     if (HAS_PENDING_EXCEPTION) {
3810       CLEAR_PENDING_EXCEPTION;
3811     }
3812   }
3813 
3814   {
3815     MutexLocker ml(PeriodicTask_lock);
3816     // Make sure the WatcherThread can be started by WatcherThread::start()
3817     // or by dynamic enrollment.
3818     WatcherThread::make_startable();
3819     // Start up the WatcherThread if there are any periodic tasks
3820     // NOTE:  All PeriodicTasks should be registered by now. If they
3821     //   aren't, late joiners might appear to start slowly (we might
3822     //   take a while to process their first tick).
3823     if (PeriodicTask::num_tasks() > 0) {
3824       WatcherThread::start();
3825     }
3826   }
3827 
3828   CodeCacheExtensions::complete_step(CodeCacheExtensionsSteps::CreateVM);
3829 
3830   create_vm_timer.end();
3831 #ifdef ASSERT
3832   _vm_complete = true;
3833 #endif
3834   return JNI_OK;
3835 }
3836 
3837 // type for the Agent_OnLoad and JVM_OnLoad entry points
3838 extern "C" {
3839   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3840 }
3841 // Find a command line agent library and return its entry point for
3842 //         -agentlib:  -agentpath:   -Xrun
3843 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3844 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3845                                     const char *on_load_symbols[],
3846                                     size_t num_symbol_entries) {
3847   OnLoadEntry_t on_load_entry = NULL;
3848   void *library = NULL;
3849 
3850   if (!agent->valid()) {
3851     char buffer[JVM_MAXPATHLEN];
3852     char ebuf[1024] = "";
3853     const char *name = agent->name();
3854     const char *msg = "Could not find agent library ";
3855 
3856     // First check to see if agent is statically linked into executable
3857     if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3858       library = agent->os_lib();
3859     } else if (agent->is_absolute_path()) {
3860       library = os::dll_load(name, ebuf, sizeof ebuf);
3861       if (library == NULL) {
3862         const char *sub_msg = " in absolute path, with error: ";
3863         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3864         char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3865         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3866         // If we can't find the agent, exit.
3867         vm_exit_during_initialization(buf, NULL);
3868         FREE_C_HEAP_ARRAY(char, buf);
3869       }
3870     } else {
3871       // Try to load the agent from the standard dll directory
3872       if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3873                              name)) {
3874         library = os::dll_load(buffer, ebuf, sizeof ebuf);
3875       }
3876       if (library == NULL) { // Try the local directory
3877         char ns[1] = {0};
3878         if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3879           library = os::dll_load(buffer, ebuf, sizeof ebuf);
3880         }
3881         if (library == NULL) {
3882           const char *sub_msg = " on the library path, with error: ";
3883           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3884           char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3885           jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3886           // If we can't find the agent, exit.
3887           vm_exit_during_initialization(buf, NULL);
3888           FREE_C_HEAP_ARRAY(char, buf);
3889         }
3890       }
3891     }
3892     agent->set_os_lib(library);
3893     agent->set_valid();
3894   }
3895 
3896   // Find the OnLoad function.
3897   on_load_entry =
3898     CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3899                                                           false,
3900                                                           on_load_symbols,
3901                                                           num_symbol_entries));
3902   return on_load_entry;
3903 }
3904 
3905 // Find the JVM_OnLoad entry point
3906 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3907   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3908   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3909 }
3910 
3911 // Find the Agent_OnLoad entry point
3912 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3913   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3914   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3915 }
3916 
3917 // For backwards compatibility with -Xrun
3918 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3919 // treated like -agentpath:
3920 // Must be called before agent libraries are created
3921 void Threads::convert_vm_init_libraries_to_agents() {
3922   AgentLibrary* agent;
3923   AgentLibrary* next;
3924 
3925   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3926     next = agent->next();  // cache the next agent now as this agent may get moved off this list
3927     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3928 
3929     // If there is an JVM_OnLoad function it will get called later,
3930     // otherwise see if there is an Agent_OnLoad
3931     if (on_load_entry == NULL) {
3932       on_load_entry = lookup_agent_on_load(agent);
3933       if (on_load_entry != NULL) {
3934         // switch it to the agent list -- so that Agent_OnLoad will be called,
3935         // JVM_OnLoad won't be attempted and Agent_OnUnload will
3936         Arguments::convert_library_to_agent(agent);
3937       } else {
3938         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3939       }
3940     }
3941   }
3942 }
3943 
3944 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
3945 // Invokes Agent_OnLoad
3946 // Called very early -- before JavaThreads exist
3947 void Threads::create_vm_init_agents() {
3948   extern struct JavaVM_ main_vm;
3949   AgentLibrary* agent;
3950 
3951   JvmtiExport::enter_onload_phase();
3952 
3953   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3954     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
3955 
3956     if (on_load_entry != NULL) {
3957       // Invoke the Agent_OnLoad function
3958       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3959       if (err != JNI_OK) {
3960         vm_exit_during_initialization("agent library failed to init", agent->name());
3961       }
3962     } else {
3963       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3964     }
3965   }
3966   JvmtiExport::enter_primordial_phase();
3967 }
3968 
3969 extern "C" {
3970   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3971 }
3972 
3973 void Threads::shutdown_vm_agents() {
3974   // Send any Agent_OnUnload notifications
3975   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3976   size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
3977   extern struct JavaVM_ main_vm;
3978   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3979 
3980     // Find the Agent_OnUnload function.
3981     Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3982                                                    os::find_agent_function(agent,
3983                                                    false,
3984                                                    on_unload_symbols,
3985                                                    num_symbol_entries));
3986 
3987     // Invoke the Agent_OnUnload function
3988     if (unload_entry != NULL) {
3989       JavaThread* thread = JavaThread::current();
3990       ThreadToNativeFromVM ttn(thread);
3991       HandleMark hm(thread);
3992       (*unload_entry)(&main_vm);
3993     }
3994   }
3995 }
3996 
3997 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
3998 // Invokes JVM_OnLoad
3999 void Threads::create_vm_init_libraries() {
4000   extern struct JavaVM_ main_vm;
4001   AgentLibrary* agent;
4002 
4003   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4004     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4005 
4006     if (on_load_entry != NULL) {
4007       // Invoke the JVM_OnLoad function
4008       JavaThread* thread = JavaThread::current();
4009       ThreadToNativeFromVM ttn(thread);
4010       HandleMark hm(thread);
4011       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4012       if (err != JNI_OK) {
4013         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4014       }
4015     } else {
4016       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4017     }
4018   }
4019 }
4020 
4021 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
4022   assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
4023 
4024   JavaThread* java_thread = NULL;
4025   // Sequential search for now.  Need to do better optimization later.
4026   for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
4027     oop tobj = thread->threadObj();
4028     if (!thread->is_exiting() &&
4029         tobj != NULL &&
4030         java_tid == java_lang_Thread::thread_id(tobj)) {
4031       java_thread = thread;
4032       break;
4033     }
4034   }
4035   return java_thread;
4036 }
4037 
4038 
4039 // Last thread running calls java.lang.Shutdown.shutdown()
4040 void JavaThread::invoke_shutdown_hooks() {
4041   HandleMark hm(this);
4042 
4043   // We could get here with a pending exception, if so clear it now.
4044   if (this->has_pending_exception()) {
4045     this->clear_pending_exception();
4046   }
4047 
4048   EXCEPTION_MARK;
4049   Klass* k =
4050     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4051                                       THREAD);
4052   if (k != NULL) {
4053     // SystemDictionary::resolve_or_null will return null if there was
4054     // an exception.  If we cannot load the Shutdown class, just don't
4055     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
4056     // and finalizers (if runFinalizersOnExit is set) won't be run.
4057     // Note that if a shutdown hook was registered or runFinalizersOnExit
4058     // was called, the Shutdown class would have already been loaded
4059     // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4060     instanceKlassHandle shutdown_klass (THREAD, k);
4061     JavaValue result(T_VOID);
4062     JavaCalls::call_static(&result,
4063                            shutdown_klass,
4064                            vmSymbols::shutdown_method_name(),
4065                            vmSymbols::void_method_signature(),
4066                            THREAD);
4067   }
4068   CLEAR_PENDING_EXCEPTION;
4069 }
4070 
4071 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4072 // the program falls off the end of main(). Another VM exit path is through
4073 // vm_exit() when the program calls System.exit() to return a value or when
4074 // there is a serious error in VM. The two shutdown paths are not exactly
4075 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4076 // and VM_Exit op at VM level.
4077 //
4078 // Shutdown sequence:
4079 //   + Shutdown native memory tracking if it is on
4080 //   + Wait until we are the last non-daemon thread to execute
4081 //     <-- every thing is still working at this moment -->
4082 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4083 //        shutdown hooks, run finalizers if finalization-on-exit
4084 //   + Call before_exit(), prepare for VM exit
4085 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4086 //        currently the only user of this mechanism is File.deleteOnExit())
4087 //      > stop flat profiler, StatSampler, watcher thread, CMS threads,
4088 //        post thread end and vm death events to JVMTI,
4089 //        stop signal thread
4090 //   + Call JavaThread::exit(), it will:
4091 //      > release JNI handle blocks, remove stack guard pages
4092 //      > remove this thread from Threads list
4093 //     <-- no more Java code from this thread after this point -->
4094 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4095 //     the compiler threads at safepoint
4096 //     <-- do not use anything that could get blocked by Safepoint -->
4097 //   + Disable tracing at JNI/JVM barriers
4098 //   + Set _vm_exited flag for threads that are still running native code
4099 //   + Delete this thread
4100 //   + Call exit_globals()
4101 //      > deletes tty
4102 //      > deletes PerfMemory resources
4103 //   + Return to caller
4104 
4105 bool Threads::destroy_vm() {
4106   JavaThread* thread = JavaThread::current();
4107 
4108 #ifdef ASSERT
4109   _vm_complete = false;
4110 #endif
4111   // Wait until we are the last non-daemon thread to execute
4112   { MutexLocker nu(Threads_lock);
4113     while (Threads::number_of_non_daemon_threads() > 1)
4114       // This wait should make safepoint checks, wait without a timeout,
4115       // and wait as a suspend-equivalent condition.
4116       //
4117       // Note: If the FlatProfiler is running and this thread is waiting
4118       // for another non-daemon thread to finish, then the FlatProfiler
4119       // is waiting for the external suspend request on this thread to
4120       // complete. wait_for_ext_suspend_completion() will eventually
4121       // timeout, but that takes time. Making this wait a suspend-
4122       // equivalent condition solves that timeout problem.
4123       //
4124       Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4125                          Mutex::_as_suspend_equivalent_flag);
4126   }
4127 
4128   // Hang forever on exit if we are reporting an error.
4129   if (ShowMessageBoxOnError && is_error_reported()) {
4130     os::infinite_sleep();
4131   }
4132   os::wait_for_keypress_at_exit();
4133 
4134   // run Java level shutdown hooks
4135   thread->invoke_shutdown_hooks();
4136 
4137   before_exit(thread);
4138 
4139   thread->exit(true);
4140 
4141   // Stop VM thread.
4142   {
4143     // 4945125 The vm thread comes to a safepoint during exit.
4144     // GC vm_operations can get caught at the safepoint, and the
4145     // heap is unparseable if they are caught. Grab the Heap_lock
4146     // to prevent this. The GC vm_operations will not be able to
4147     // queue until after the vm thread is dead. After this point,
4148     // we'll never emerge out of the safepoint before the VM exits.
4149 
4150     MutexLocker ml(Heap_lock);
4151 
4152     VMThread::wait_for_vm_thread_exit();
4153     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4154     VMThread::destroy();
4155   }
4156 
4157   // clean up ideal graph printers
4158 #if defined(COMPILER2) && !defined(PRODUCT)
4159   IdealGraphPrinter::clean_up();
4160 #endif
4161 
4162   // Now, all Java threads are gone except daemon threads. Daemon threads
4163   // running Java code or in VM are stopped by the Safepoint. However,
4164   // daemon threads executing native code are still running.  But they
4165   // will be stopped at native=>Java/VM barriers. Note that we can't
4166   // simply kill or suspend them, as it is inherently deadlock-prone.
4167 
4168   VM_Exit::set_vm_exited();
4169 
4170   notify_vm_shutdown();
4171 
4172   delete thread;
4173 
4174 #if INCLUDE_JVMCI
4175   if (JVMCICounterSize > 0) {
4176     FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4177   }
4178 #endif
4179 
4180   // exit_globals() will delete tty
4181   exit_globals();
4182 
4183   LogConfiguration::finalize();
4184 
4185   return true;
4186 }
4187 
4188 
4189 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4190   if (version == JNI_VERSION_1_1) return JNI_TRUE;
4191   return is_supported_jni_version(version);
4192 }
4193 
4194 
4195 jboolean Threads::is_supported_jni_version(jint version) {
4196   if (version == JNI_VERSION_1_2) return JNI_TRUE;
4197   if (version == JNI_VERSION_1_4) return JNI_TRUE;
4198   if (version == JNI_VERSION_1_6) return JNI_TRUE;
4199   if (version == JNI_VERSION_1_8) return JNI_TRUE;
4200   if (version == JNI_VERSION_9) return JNI_TRUE;
4201   return JNI_FALSE;
4202 }
4203 
4204 
4205 void Threads::add(JavaThread* p, bool force_daemon) {
4206   // The threads lock must be owned at this point
4207   assert_locked_or_safepoint(Threads_lock);
4208 
4209   // See the comment for this method in thread.hpp for its purpose and
4210   // why it is called here.
4211   p->initialize_queues();
4212   p->set_next(_thread_list);
4213   _thread_list = p;
4214   _number_of_threads++;
4215   oop threadObj = p->threadObj();
4216   bool daemon = true;
4217   // Bootstrapping problem: threadObj can be null for initial
4218   // JavaThread (or for threads attached via JNI)
4219   if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4220     _number_of_non_daemon_threads++;
4221     daemon = false;
4222   }
4223 
4224   ThreadService::add_thread(p, daemon);
4225 
4226   // Possible GC point.
4227   Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4228 }
4229 
4230 void Threads::remove(JavaThread* p) {
4231   // Extra scope needed for Thread_lock, so we can check
4232   // that we do not remove thread without safepoint code notice
4233   { MutexLocker ml(Threads_lock);
4234 
4235     assert(includes(p), "p must be present");
4236 
4237     JavaThread* current = _thread_list;
4238     JavaThread* prev    = NULL;
4239 
4240     while (current != p) {
4241       prev    = current;
4242       current = current->next();
4243     }
4244 
4245     if (prev) {
4246       prev->set_next(current->next());
4247     } else {
4248       _thread_list = p->next();
4249     }
4250     _number_of_threads--;
4251     oop threadObj = p->threadObj();
4252     bool daemon = true;
4253     if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4254       _number_of_non_daemon_threads--;
4255       daemon = false;
4256 
4257       // Only one thread left, do a notify on the Threads_lock so a thread waiting
4258       // on destroy_vm will wake up.
4259       if (number_of_non_daemon_threads() == 1) {
4260         Threads_lock->notify_all();
4261       }
4262     }
4263     ThreadService::remove_thread(p, daemon);
4264 
4265     // Make sure that safepoint code disregard this thread. This is needed since
4266     // the thread might mess around with locks after this point. This can cause it
4267     // to do callbacks into the safepoint code. However, the safepoint code is not aware
4268     // of this thread since it is removed from the queue.
4269     p->set_terminated_value();
4270   } // unlock Threads_lock
4271 
4272   // Since Events::log uses a lock, we grab it outside the Threads_lock
4273   Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4274 }
4275 
4276 // Threads_lock must be held when this is called (or must be called during a safepoint)
4277 bool Threads::includes(JavaThread* p) {
4278   assert(Threads_lock->is_locked(), "sanity check");
4279   ALL_JAVA_THREADS(q) {
4280     if (q == p) {
4281       return true;
4282     }
4283   }
4284   return false;
4285 }
4286 
4287 // Operations on the Threads list for GC.  These are not explicitly locked,
4288 // but the garbage collector must provide a safe context for them to run.
4289 // In particular, these things should never be called when the Threads_lock
4290 // is held by some other thread. (Note: the Safepoint abstraction also
4291 // uses the Threads_lock to guarantee this property. It also makes sure that
4292 // all threads gets blocked when exiting or starting).
4293 
4294 void Threads::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
4295   ALL_JAVA_THREADS(p) {
4296     p->oops_do(f, cld_f, cf);
4297   }
4298   VMThread::vm_thread()->oops_do(f, cld_f, cf);
4299 }
4300 
4301 void Threads::change_thread_claim_parity() {
4302   // Set the new claim parity.
4303   assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4304          "Not in range.");
4305   _thread_claim_parity++;
4306   if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4307   assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4308          "Not in range.");
4309 }
4310 
4311 #ifdef ASSERT
4312 void Threads::assert_all_threads_claimed() {
4313   ALL_JAVA_THREADS(p) {
4314     const int thread_parity = p->oops_do_parity();
4315     assert((thread_parity == _thread_claim_parity),
4316            "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4317   }
4318 }
4319 #endif // ASSERT
4320 
4321 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
4322   int cp = Threads::thread_claim_parity();
4323   ALL_JAVA_THREADS(p) {
4324     if (p->claim_oops_do(is_par, cp)) {
4325       p->oops_do(f, cld_f, cf);
4326     }
4327   }
4328   VMThread* vmt = VMThread::vm_thread();
4329   if (vmt->claim_oops_do(is_par, cp)) {
4330     vmt->oops_do(f, cld_f, cf);
4331   }
4332 }
4333 
4334 #if INCLUDE_ALL_GCS
4335 // Used by ParallelScavenge
4336 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4337   ALL_JAVA_THREADS(p) {
4338     q->enqueue(new ThreadRootsTask(p));
4339   }
4340   q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4341 }
4342 
4343 // Used by Parallel Old
4344 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4345   ALL_JAVA_THREADS(p) {
4346     q->enqueue(new ThreadRootsMarkingTask(p));
4347   }
4348   q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4349 }
4350 #endif // INCLUDE_ALL_GCS
4351 
4352 void Threads::nmethods_do(CodeBlobClosure* cf) {
4353   ALL_JAVA_THREADS(p) {
4354     // This is used by the code cache sweeper to mark nmethods that are active
4355     // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4356     // marking CodeCacheSweeperThread::_scanned_nmethod as active.
4357     if(!p->is_Code_cache_sweeper_thread()) {
4358       p->nmethods_do(cf);
4359     }
4360   }
4361 }
4362 
4363 void Threads::metadata_do(void f(Metadata*)) {
4364   ALL_JAVA_THREADS(p) {
4365     p->metadata_do(f);
4366   }
4367 }
4368 
4369 class ThreadHandlesClosure : public ThreadClosure {
4370   void (*_f)(Metadata*);
4371  public:
4372   ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4373   virtual void do_thread(Thread* thread) {
4374     thread->metadata_handles_do(_f);
4375   }
4376 };
4377 
4378 void Threads::metadata_handles_do(void f(Metadata*)) {
4379   // Only walk the Handles in Thread.
4380   ThreadHandlesClosure handles_closure(f);
4381   threads_do(&handles_closure);
4382 }
4383 
4384 void Threads::deoptimized_wrt_marked_nmethods() {
4385   ALL_JAVA_THREADS(p) {
4386     p->deoptimized_wrt_marked_nmethods();
4387   }
4388 }
4389 
4390 
4391 // Get count Java threads that are waiting to enter the specified monitor.
4392 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4393                                                          address monitor,
4394                                                          bool doLock) {
4395   assert(doLock || SafepointSynchronize::is_at_safepoint(),
4396          "must grab Threads_lock or be at safepoint");
4397   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4398 
4399   int i = 0;
4400   {
4401     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4402     ALL_JAVA_THREADS(p) {
4403       if (!p->can_call_java()) continue;
4404 
4405       address pending = (address)p->current_pending_monitor();
4406       if (pending == monitor) {             // found a match
4407         if (i < count) result->append(p);   // save the first count matches
4408         i++;
4409       }
4410     }
4411   }
4412   return result;
4413 }
4414 
4415 
4416 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4417                                                       bool doLock) {
4418   assert(doLock ||
4419          Threads_lock->owned_by_self() ||
4420          SafepointSynchronize::is_at_safepoint(),
4421          "must grab Threads_lock or be at safepoint");
4422 
4423   // NULL owner means not locked so we can skip the search
4424   if (owner == NULL) return NULL;
4425 
4426   {
4427     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4428     ALL_JAVA_THREADS(p) {
4429       // first, see if owner is the address of a Java thread
4430       if (owner == (address)p) return p;
4431     }
4432   }
4433   // Cannot assert on lack of success here since this function may be
4434   // used by code that is trying to report useful problem information
4435   // like deadlock detection.
4436   if (UseHeavyMonitors) return NULL;
4437 
4438   // If we didn't find a matching Java thread and we didn't force use of
4439   // heavyweight monitors, then the owner is the stack address of the
4440   // Lock Word in the owning Java thread's stack.
4441   //
4442   JavaThread* the_owner = NULL;
4443   {
4444     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4445     ALL_JAVA_THREADS(q) {
4446       if (q->is_lock_owned(owner)) {
4447         the_owner = q;
4448         break;
4449       }
4450     }
4451   }
4452   // cannot assert on lack of success here; see above comment
4453   return the_owner;
4454 }
4455 
4456 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4457 void Threads::print_on(outputStream* st, bool print_stacks,
4458                        bool internal_format, bool print_concurrent_locks) {
4459   char buf[32];
4460   st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4461 
4462   st->print_cr("Full thread dump %s (%s %s):",
4463                Abstract_VM_Version::vm_name(),
4464                Abstract_VM_Version::vm_release(),
4465                Abstract_VM_Version::vm_info_string());
4466   st->cr();
4467 
4468 #if INCLUDE_SERVICES
4469   // Dump concurrent locks
4470   ConcurrentLocksDump concurrent_locks;
4471   if (print_concurrent_locks) {
4472     concurrent_locks.dump_at_safepoint();
4473   }
4474 #endif // INCLUDE_SERVICES
4475 
4476   ALL_JAVA_THREADS(p) {
4477     ResourceMark rm;
4478     p->print_on(st);
4479     if (print_stacks) {
4480       if (internal_format) {
4481         p->trace_stack();
4482       } else {
4483         p->print_stack_on(st);
4484       }
4485     }
4486     st->cr();
4487 #if INCLUDE_SERVICES
4488     if (print_concurrent_locks) {
4489       concurrent_locks.print_locks_on(p, st);
4490     }
4491 #endif // INCLUDE_SERVICES
4492   }
4493 
4494   VMThread::vm_thread()->print_on(st);
4495   st->cr();
4496   Universe::heap()->print_gc_threads_on(st);
4497   WatcherThread* wt = WatcherThread::watcher_thread();
4498   if (wt != NULL) {
4499     wt->print_on(st);
4500     st->cr();
4501   }
4502   st->flush();
4503 }
4504 
4505 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4506                              int buflen, bool* found_current) {
4507   if (this_thread != NULL) {
4508     bool is_current = (current == this_thread);
4509     *found_current = *found_current || is_current;
4510     st->print("%s", is_current ? "=>" : "  ");
4511 
4512     st->print(PTR_FORMAT, p2i(this_thread));
4513     st->print(" ");
4514     this_thread->print_on_error(st, buf, buflen);
4515     st->cr();
4516   }
4517 }
4518 
4519 class PrintOnErrorClosure : public ThreadClosure {
4520   outputStream* _st;
4521   Thread* _current;
4522   char* _buf;
4523   int _buflen;
4524   bool* _found_current;
4525  public:
4526   PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4527                       int buflen, bool* found_current) :
4528    _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4529 
4530   virtual void do_thread(Thread* thread) {
4531     Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4532   }
4533 };
4534 
4535 // Threads::print_on_error() is called by fatal error handler. It's possible
4536 // that VM is not at safepoint and/or current thread is inside signal handler.
4537 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4538 // memory (even in resource area), it might deadlock the error handler.
4539 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4540                              int buflen) {
4541   bool found_current = false;
4542   st->print_cr("Java Threads: ( => current thread )");
4543   ALL_JAVA_THREADS(thread) {
4544     print_on_error(thread, st, current, buf, buflen, &found_current);
4545   }
4546   st->cr();
4547 
4548   st->print_cr("Other Threads:");
4549   print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4550   print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4551 
4552   PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4553   Universe::heap()->gc_threads_do(&print_closure);
4554 
4555   if (!found_current) {
4556     st->cr();
4557     st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4558     current->print_on_error(st, buf, buflen);
4559     st->cr();
4560   }
4561   st->cr();
4562   st->print_cr("Threads with active compile tasks:");
4563   print_threads_compiling(st, buf, buflen);
4564 }
4565 
4566 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4567   ALL_JAVA_THREADS(thread) {
4568     if (thread->is_Compiler_thread()) {
4569       CompilerThread* ct = (CompilerThread*) thread;
4570       if (ct->task() != NULL) {
4571         thread->print_name_on_error(st, buf, buflen);
4572         ct->task()->print(st, NULL, true, true);
4573       }
4574     }
4575   }
4576 }
4577 
4578 
4579 // Internal SpinLock and Mutex
4580 // Based on ParkEvent
4581 
4582 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4583 //
4584 // We employ SpinLocks _only for low-contention, fixed-length
4585 // short-duration critical sections where we're concerned
4586 // about native mutex_t or HotSpot Mutex:: latency.
4587 // The mux construct provides a spin-then-block mutual exclusion
4588 // mechanism.
4589 //
4590 // Testing has shown that contention on the ListLock guarding gFreeList
4591 // is common.  If we implement ListLock as a simple SpinLock it's common
4592 // for the JVM to devolve to yielding with little progress.  This is true
4593 // despite the fact that the critical sections protected by ListLock are
4594 // extremely short.
4595 //
4596 // TODO-FIXME: ListLock should be of type SpinLock.
4597 // We should make this a 1st-class type, integrated into the lock
4598 // hierarchy as leaf-locks.  Critically, the SpinLock structure
4599 // should have sufficient padding to avoid false-sharing and excessive
4600 // cache-coherency traffic.
4601 
4602 
4603 typedef volatile int SpinLockT;
4604 
4605 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4606   if (Atomic::cmpxchg (1, adr, 0) == 0) {
4607     return;   // normal fast-path return
4608   }
4609 
4610   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4611   TEVENT(SpinAcquire - ctx);
4612   int ctr = 0;
4613   int Yields = 0;
4614   for (;;) {
4615     while (*adr != 0) {
4616       ++ctr;
4617       if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4618         if (Yields > 5) {
4619           os::naked_short_sleep(1);
4620         } else {
4621           os::naked_yield();
4622           ++Yields;
4623         }
4624       } else {
4625         SpinPause();
4626       }
4627     }
4628     if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4629   }
4630 }
4631 
4632 void Thread::SpinRelease(volatile int * adr) {
4633   assert(*adr != 0, "invariant");
4634   OrderAccess::fence();      // guarantee at least release consistency.
4635   // Roach-motel semantics.
4636   // It's safe if subsequent LDs and STs float "up" into the critical section,
4637   // but prior LDs and STs within the critical section can't be allowed
4638   // to reorder or float past the ST that releases the lock.
4639   // Loads and stores in the critical section - which appear in program
4640   // order before the store that releases the lock - must also appear
4641   // before the store that releases the lock in memory visibility order.
4642   // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4643   // the ST of 0 into the lock-word which releases the lock, so fence
4644   // more than covers this on all platforms.
4645   *adr = 0;
4646 }
4647 
4648 // muxAcquire and muxRelease:
4649 //
4650 // *  muxAcquire and muxRelease support a single-word lock-word construct.
4651 //    The LSB of the word is set IFF the lock is held.
4652 //    The remainder of the word points to the head of a singly-linked list
4653 //    of threads blocked on the lock.
4654 //
4655 // *  The current implementation of muxAcquire-muxRelease uses its own
4656 //    dedicated Thread._MuxEvent instance.  If we're interested in
4657 //    minimizing the peak number of extant ParkEvent instances then
4658 //    we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4659 //    as certain invariants were satisfied.  Specifically, care would need
4660 //    to be taken with regards to consuming unpark() "permits".
4661 //    A safe rule of thumb is that a thread would never call muxAcquire()
4662 //    if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4663 //    park().  Otherwise the _ParkEvent park() operation in muxAcquire() could
4664 //    consume an unpark() permit intended for monitorenter, for instance.
4665 //    One way around this would be to widen the restricted-range semaphore
4666 //    implemented in park().  Another alternative would be to provide
4667 //    multiple instances of the PlatformEvent() for each thread.  One
4668 //    instance would be dedicated to muxAcquire-muxRelease, for instance.
4669 //
4670 // *  Usage:
4671 //    -- Only as leaf locks
4672 //    -- for short-term locking only as muxAcquire does not perform
4673 //       thread state transitions.
4674 //
4675 // Alternatives:
4676 // *  We could implement muxAcquire and muxRelease with MCS or CLH locks
4677 //    but with parking or spin-then-park instead of pure spinning.
4678 // *  Use Taura-Oyama-Yonenzawa locks.
4679 // *  It's possible to construct a 1-0 lock if we encode the lockword as
4680 //    (List,LockByte).  Acquire will CAS the full lockword while Release
4681 //    will STB 0 into the LockByte.  The 1-0 scheme admits stranding, so
4682 //    acquiring threads use timers (ParkTimed) to detect and recover from
4683 //    the stranding window.  Thread/Node structures must be aligned on 256-byte
4684 //    boundaries by using placement-new.
4685 // *  Augment MCS with advisory back-link fields maintained with CAS().
4686 //    Pictorially:  LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4687 //    The validity of the backlinks must be ratified before we trust the value.
4688 //    If the backlinks are invalid the exiting thread must back-track through the
4689 //    the forward links, which are always trustworthy.
4690 // *  Add a successor indication.  The LockWord is currently encoded as
4691 //    (List, LOCKBIT:1).  We could also add a SUCCBIT or an explicit _succ variable
4692 //    to provide the usual futile-wakeup optimization.
4693 //    See RTStt for details.
4694 // *  Consider schedctl.sc_nopreempt to cover the critical section.
4695 //
4696 
4697 
4698 typedef volatile intptr_t MutexT;      // Mux Lock-word
4699 enum MuxBits { LOCKBIT = 1 };
4700 
4701 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4702   intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4703   if (w == 0) return;
4704   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4705     return;
4706   }
4707 
4708   TEVENT(muxAcquire - Contention);
4709   ParkEvent * const Self = Thread::current()->_MuxEvent;
4710   assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4711   for (;;) {
4712     int its = (os::is_MP() ? 100 : 0) + 1;
4713 
4714     // Optional spin phase: spin-then-park strategy
4715     while (--its >= 0) {
4716       w = *Lock;
4717       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4718         return;
4719       }
4720     }
4721 
4722     Self->reset();
4723     Self->OnList = intptr_t(Lock);
4724     // The following fence() isn't _strictly necessary as the subsequent
4725     // CAS() both serializes execution and ratifies the fetched *Lock value.
4726     OrderAccess::fence();
4727     for (;;) {
4728       w = *Lock;
4729       if ((w & LOCKBIT) == 0) {
4730         if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4731           Self->OnList = 0;   // hygiene - allows stronger asserts
4732           return;
4733         }
4734         continue;      // Interference -- *Lock changed -- Just retry
4735       }
4736       assert(w & LOCKBIT, "invariant");
4737       Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4738       if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4739     }
4740 
4741     while (Self->OnList != 0) {
4742       Self->park();
4743     }
4744   }
4745 }
4746 
4747 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4748   intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4749   if (w == 0) return;
4750   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4751     return;
4752   }
4753 
4754   TEVENT(muxAcquire - Contention);
4755   ParkEvent * ReleaseAfter = NULL;
4756   if (ev == NULL) {
4757     ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4758   }
4759   assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4760   for (;;) {
4761     guarantee(ev->OnList == 0, "invariant");
4762     int its = (os::is_MP() ? 100 : 0) + 1;
4763 
4764     // Optional spin phase: spin-then-park strategy
4765     while (--its >= 0) {
4766       w = *Lock;
4767       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4768         if (ReleaseAfter != NULL) {
4769           ParkEvent::Release(ReleaseAfter);
4770         }
4771         return;
4772       }
4773     }
4774 
4775     ev->reset();
4776     ev->OnList = intptr_t(Lock);
4777     // The following fence() isn't _strictly necessary as the subsequent
4778     // CAS() both serializes execution and ratifies the fetched *Lock value.
4779     OrderAccess::fence();
4780     for (;;) {
4781       w = *Lock;
4782       if ((w & LOCKBIT) == 0) {
4783         if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4784           ev->OnList = 0;
4785           // We call ::Release while holding the outer lock, thus
4786           // artificially lengthening the critical section.
4787           // Consider deferring the ::Release() until the subsequent unlock(),
4788           // after we've dropped the outer lock.
4789           if (ReleaseAfter != NULL) {
4790             ParkEvent::Release(ReleaseAfter);
4791           }
4792           return;
4793         }
4794         continue;      // Interference -- *Lock changed -- Just retry
4795       }
4796       assert(w & LOCKBIT, "invariant");
4797       ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4798       if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4799     }
4800 
4801     while (ev->OnList != 0) {
4802       ev->park();
4803     }
4804   }
4805 }
4806 
4807 // Release() must extract a successor from the list and then wake that thread.
4808 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4809 // similar to that used by ParkEvent::Allocate() and ::Release().  DMR-based
4810 // Release() would :
4811 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4812 // (B) Extract a successor from the private list "in-hand"
4813 // (C) attempt to CAS() the residual back into *Lock over null.
4814 //     If there were any newly arrived threads and the CAS() would fail.
4815 //     In that case Release() would detach the RATs, re-merge the list in-hand
4816 //     with the RATs and repeat as needed.  Alternately, Release() might
4817 //     detach and extract a successor, but then pass the residual list to the wakee.
4818 //     The wakee would be responsible for reattaching and remerging before it
4819 //     competed for the lock.
4820 //
4821 // Both "pop" and DMR are immune from ABA corruption -- there can be
4822 // multiple concurrent pushers, but only one popper or detacher.
4823 // This implementation pops from the head of the list.  This is unfair,
4824 // but tends to provide excellent throughput as hot threads remain hot.
4825 // (We wake recently run threads first).
4826 //
4827 // All paths through muxRelease() will execute a CAS.
4828 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4829 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4830 // executed within the critical section are complete and globally visible before the
4831 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4832 void Thread::muxRelease(volatile intptr_t * Lock)  {
4833   for (;;) {
4834     const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4835     assert(w & LOCKBIT, "invariant");
4836     if (w == LOCKBIT) return;
4837     ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4838     assert(List != NULL, "invariant");
4839     assert(List->OnList == intptr_t(Lock), "invariant");
4840     ParkEvent * const nxt = List->ListNext;
4841     guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4842 
4843     // The following CAS() releases the lock and pops the head element.
4844     // The CAS() also ratifies the previously fetched lock-word value.
4845     if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4846       continue;
4847     }
4848     List->OnList = 0;
4849     OrderAccess::fence();
4850     List->unpark();
4851     return;
4852   }
4853 }
4854 
4855 
4856 void Threads::verify() {
4857   ALL_JAVA_THREADS(p) {
4858     p->verify();
4859   }
4860   VMThread* thread = VMThread::vm_thread();
4861   if (thread != NULL) thread->verify();
4862 }