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/systemDictionary.hpp"
  29 #include "classfile/vmSymbols.hpp"
  30 #include "code/codeCache.hpp"
  31 #include "code/codeCacheExtensions.hpp"
  32 #include "code/scopeDesc.hpp"
  33 #include "compiler/compileBroker.hpp"
  34 #include "compiler/compileTask.hpp"
  35 #include "gc/shared/gcId.hpp"
  36 #include "gc/shared/gcLocker.inline.hpp"
  37 #include "gc/shared/workgroup.hpp"
  38 #include "interpreter/interpreter.hpp"
  39 #include "interpreter/linkResolver.hpp"
  40 #include "interpreter/oopMapCache.hpp"
  41 #include "jvmtifiles/jvmtiEnv.hpp"
  42 #include "logging/log.hpp"
  43 #include "logging/logConfiguration.hpp"
  44 #include "memory/metaspaceShared.hpp"
  45 #include "memory/oopFactory.hpp"
  46 #include "memory/resourceArea.hpp"
  47 #include "memory/universe.inline.hpp"
  48 #include "oops/instanceKlass.hpp"
  49 #include "oops/objArrayOop.hpp"
  50 #include "oops/oop.inline.hpp"
  51 #include "oops/symbol.hpp"
  52 #include "oops/verifyOopClosure.hpp"
  53 #include "prims/jvm_misc.hpp"
  54 #include "prims/jvmtiExport.hpp"
  55 #include "prims/jvmtiThreadState.hpp"
  56 #include "prims/privilegedStack.hpp"
  57 #include "runtime/arguments.hpp"
  58 #include "runtime/atomic.inline.hpp"
  59 #include "runtime/biasedLocking.hpp"
  60 #include "runtime/commandLineFlagConstraintList.hpp"
  61 #include "runtime/commandLineFlagRangeList.hpp"
  62 #include "runtime/deoptimization.hpp"
  63 #include "runtime/fprofiler.hpp"
  64 #include "runtime/frame.inline.hpp"
  65 #include "runtime/globals.hpp"
  66 #include "runtime/init.hpp"
  67 #include "runtime/interfaceSupport.hpp"
  68 #include "runtime/java.hpp"
  69 #include "runtime/javaCalls.hpp"
  70 #include "runtime/jniPeriodicChecker.hpp"
  71 #include "runtime/logTimer.hpp"
  72 #include "runtime/memprofiler.hpp"
  73 #include "runtime/mutexLocker.hpp"
  74 #include "runtime/objectMonitor.hpp"
  75 #include "runtime/orderAccess.inline.hpp"
  76 #include "runtime/osThread.hpp"
  77 #include "runtime/safepoint.hpp"
  78 #include "runtime/sharedRuntime.hpp"
  79 #include "runtime/statSampler.hpp"
  80 #include "runtime/stubRoutines.hpp"
  81 #include "runtime/sweeper.hpp"
  82 #include "runtime/task.hpp"
  83 #include "runtime/thread.inline.hpp"
  84 #include "runtime/threadCritical.hpp"
  85 #include "runtime/vframe.hpp"
  86 #include "runtime/vframeArray.hpp"
  87 #include "runtime/vframe_hp.hpp"
  88 #include "runtime/vmThread.hpp"
  89 #include "runtime/vm_operations.hpp"
  90 #include "runtime/vm_version.hpp"
  91 #include "services/attachListener.hpp"
  92 #include "services/management.hpp"
  93 #include "services/memTracker.hpp"
  94 #include "services/threadService.hpp"
  95 #include "trace/traceMacros.hpp"
  96 #include "trace/tracing.hpp"
  97 #include "utilities/defaultStream.hpp"
  98 #include "utilities/dtrace.hpp"
  99 #include "utilities/events.hpp"
 100 #include "utilities/macros.hpp"
 101 #include "utilities/preserveException.hpp"
 102 #if INCLUDE_ALL_GCS
 103 #include "gc/cms/concurrentMarkSweepThread.hpp"
 104 #include "gc/g1/concurrentMarkThread.inline.hpp"
 105 #include "gc/parallel/pcTasks.hpp"
 106 #endif // INCLUDE_ALL_GCS
 107 #if INCLUDE_JVMCI
 108 #include "jvmci/jvmciCompiler.hpp"
 109 #include "jvmci/jvmciRuntime.hpp"
 110 #endif
 111 #ifdef COMPILER1
 112 #include "c1/c1_Compiler.hpp"
 113 #endif
 114 #ifdef COMPILER2
 115 #include "opto/c2compiler.hpp"
 116 #include "opto/idealGraphPrinter.hpp"
 117 #endif
 118 #if INCLUDE_RTM_OPT
 119 #include "runtime/rtmLocking.hpp"
 120 #endif
 121 
 122 #ifdef DTRACE_ENABLED
 123 
 124 // Only bother with this argument setup if dtrace is available
 125 
 126   #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
 127   #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
 128 
 129   #define DTRACE_THREAD_PROBE(probe, javathread)                           \
 130     {                                                                      \
 131       ResourceMark rm(this);                                               \
 132       int len = 0;                                                         \
 133       const char* name = (javathread)->get_thread_name();                  \
 134       len = strlen(name);                                                  \
 135       HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */               \
 136         (char *) name, len,                                                \
 137         java_lang_Thread::thread_id((javathread)->threadObj()),            \
 138         (uintptr_t) (javathread)->osthread()->thread_id(),                 \
 139         java_lang_Thread::is_daemon((javathread)->threadObj()));           \
 140     }
 141 
 142 #else //  ndef DTRACE_ENABLED
 143 
 144   #define DTRACE_THREAD_PROBE(probe, javathread)
 145 
 146 #endif // ndef DTRACE_ENABLED
 147 
 148 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 149 // Current thread is maintained as a thread-local variable
 150 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
 151 #endif
 152 
 153 // Class hierarchy
 154 // - Thread
 155 //   - VMThread
 156 //   - WatcherThread
 157 //   - ConcurrentMarkSweepThread
 158 //   - JavaThread
 159 //     - CompilerThread
 160 
 161 // ======= Thread ========
 162 // Support for forcing alignment of thread objects for biased locking
 163 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
 164   if (UseBiasedLocking) {
 165     const int alignment = markOopDesc::biased_lock_alignment;
 166     size_t aligned_size = size + (alignment - sizeof(intptr_t));
 167     void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
 168                                           : AllocateHeap(aligned_size, flags, CURRENT_PC,
 169                                                          AllocFailStrategy::RETURN_NULL);
 170     void* aligned_addr     = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
 171     assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
 172            ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
 173            "JavaThread alignment code overflowed allocated storage");
 174     if (aligned_addr != real_malloc_addr) {
 175       log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
 176                               p2i(real_malloc_addr),
 177                               p2i(aligned_addr));
 178     }
 179     ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
 180     return aligned_addr;
 181   } else {
 182     return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
 183                        : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
 184   }
 185 }
 186 
 187 void Thread::operator delete(void* p) {
 188   if (UseBiasedLocking) {
 189     void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
 190     FreeHeap(real_malloc_addr);
 191   } else {
 192     FreeHeap(p);
 193   }
 194 }
 195 
 196 
 197 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
 198 // JavaThread
 199 
 200 
 201 Thread::Thread() {
 202   // stack and get_thread
 203   set_stack_base(NULL);
 204   set_stack_size(0);
 205   set_self_raw_id(0);
 206   set_lgrp_id(-1);
 207   DEBUG_ONLY(clear_suspendible_thread();)
 208 
 209   // allocated data structures
 210   set_osthread(NULL);
 211   set_resource_area(new (mtThread)ResourceArea());
 212   DEBUG_ONLY(_current_resource_mark = NULL;)
 213   set_handle_area(new (mtThread) HandleArea(NULL));
 214   set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
 215   set_active_handles(NULL);
 216   set_free_handle_block(NULL);
 217   set_last_handle_mark(NULL);
 218 
 219   // This initial value ==> never claimed.
 220   _oops_do_parity = 0;
 221 
 222   // the handle mark links itself to last_handle_mark
 223   new HandleMark(this);
 224 
 225   // plain initialization
 226   debug_only(_owned_locks = NULL;)
 227   debug_only(_allow_allocation_count = 0;)
 228   NOT_PRODUCT(_allow_safepoint_count = 0;)
 229   NOT_PRODUCT(_skip_gcalot = false;)
 230   _jvmti_env_iteration_count = 0;
 231   set_allocated_bytes(0);
 232   _vm_operation_started_count = 0;
 233   _vm_operation_completed_count = 0;
 234   _current_pending_monitor = NULL;
 235   _current_pending_monitor_is_from_java = true;
 236   _current_waiting_monitor = NULL;
 237   _num_nested_signal = 0;
 238   omFreeList = NULL;
 239   omFreeCount = 0;
 240   omFreeProvision = 32;
 241   omInUseList = NULL;
 242   omInUseCount = 0;
 243 
 244 #ifdef ASSERT
 245   _visited_for_critical_count = false;
 246 #endif
 247 
 248   _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
 249                          Monitor::_safepoint_check_sometimes);
 250   _suspend_flags = 0;
 251 
 252   // thread-specific hashCode stream generator state - Marsaglia shift-xor form
 253   _hashStateX = os::random();
 254   _hashStateY = 842502087;
 255   _hashStateZ = 0x8767;    // (int)(3579807591LL & 0xffff) ;
 256   _hashStateW = 273326509;
 257 
 258   _OnTrap   = 0;
 259   _schedctl = NULL;
 260   _Stalled  = 0;
 261   _TypeTag  = 0x2BAD;
 262 
 263   // Many of the following fields are effectively final - immutable
 264   // Note that nascent threads can't use the Native Monitor-Mutex
 265   // construct until the _MutexEvent is initialized ...
 266   // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
 267   // we might instead use a stack of ParkEvents that we could provision on-demand.
 268   // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
 269   // and ::Release()
 270   _ParkEvent   = ParkEvent::Allocate(this);
 271   _SleepEvent  = ParkEvent::Allocate(this);
 272   _MutexEvent  = ParkEvent::Allocate(this);
 273   _MuxEvent    = ParkEvent::Allocate(this);
 274 
 275 #ifdef CHECK_UNHANDLED_OOPS
 276   if (CheckUnhandledOops) {
 277     _unhandled_oops = new UnhandledOops(this);
 278   }
 279 #endif // CHECK_UNHANDLED_OOPS
 280 #ifdef ASSERT
 281   if (UseBiasedLocking) {
 282     assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
 283     assert(this == _real_malloc_address ||
 284            this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
 285            "bug in forced alignment of thread objects");
 286   }
 287 #endif // ASSERT
 288 }
 289 
 290 void Thread::initialize_thread_current() {
 291 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 292   assert(_thr_current == NULL, "Thread::current already initialized");
 293   _thr_current = this;
 294 #endif
 295   assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
 296   ThreadLocalStorage::set_thread(this);
 297   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 298 }
 299 
 300 void Thread::clear_thread_current() {
 301   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 302 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 303   _thr_current = NULL;
 304 #endif
 305   ThreadLocalStorage::set_thread(NULL);
 306 }
 307 
 308 void Thread::record_stack_base_and_size() {
 309   set_stack_base(os::current_stack_base());
 310   set_stack_size(os::current_stack_size());
 311   // CR 7190089: on Solaris, primordial thread's stack is adjusted
 312   // in initialize_thread(). Without the adjustment, stack size is
 313   // incorrect if stack is set to unlimited (ulimit -s unlimited).
 314   // So far, only Solaris has real implementation of initialize_thread().
 315   //
 316   // set up any platform-specific state.
 317   os::initialize_thread(this);
 318 
 319   // Set stack limits after thread is initialized.
 320   if (is_Java_thread()) {
 321     ((JavaThread*) this)->set_stack_overflow_limit();
 322     ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
 323   }
 324 #if INCLUDE_NMT
 325   // record thread's native stack, stack grows downward
 326   MemTracker::record_thread_stack(stack_end(), stack_size());
 327 #endif // INCLUDE_NMT
 328   log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
 329     PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
 330     os::current_thread_id(), p2i(stack_base() - stack_size()),
 331     p2i(stack_base()), stack_size()/1024);
 332 }
 333 
 334 
 335 Thread::~Thread() {
 336   // Reclaim the objectmonitors from the omFreeList of the moribund thread.
 337   ObjectSynchronizer::omFlush(this);
 338 
 339   EVENT_THREAD_DESTRUCT(this);
 340 
 341   // stack_base can be NULL if the thread is never started or exited before
 342   // record_stack_base_and_size called. Although, we would like to ensure
 343   // that all started threads do call record_stack_base_and_size(), there is
 344   // not proper way to enforce that.
 345 #if INCLUDE_NMT
 346   if (_stack_base != NULL) {
 347     MemTracker::release_thread_stack(stack_end(), stack_size());
 348 #ifdef ASSERT
 349     set_stack_base(NULL);
 350 #endif
 351   }
 352 #endif // INCLUDE_NMT
 353 
 354   // deallocate data structures
 355   delete resource_area();
 356   // since the handle marks are using the handle area, we have to deallocated the root
 357   // handle mark before deallocating the thread's handle area,
 358   assert(last_handle_mark() != NULL, "check we have an element");
 359   delete last_handle_mark();
 360   assert(last_handle_mark() == NULL, "check we have reached the end");
 361 
 362   // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
 363   // We NULL out the fields for good hygiene.
 364   ParkEvent::Release(_ParkEvent); _ParkEvent   = NULL;
 365   ParkEvent::Release(_SleepEvent); _SleepEvent  = NULL;
 366   ParkEvent::Release(_MutexEvent); _MutexEvent  = NULL;
 367   ParkEvent::Release(_MuxEvent); _MuxEvent    = NULL;
 368 
 369   delete handle_area();
 370   delete metadata_handles();
 371 
 372   // osthread() can be NULL, if creation of thread failed.
 373   if (osthread() != NULL) os::free_thread(osthread());
 374 
 375   delete _SR_lock;
 376 
 377   // clear Thread::current if thread is deleting itself.
 378   // Needed to ensure JNI correctly detects non-attached threads.
 379   if (this == Thread::current()) {
 380     clear_thread_current();
 381   }
 382 
 383   CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
 384 }
 385 
 386 // NOTE: dummy function for assertion purpose.
 387 void Thread::run() {
 388   ShouldNotReachHere();
 389 }
 390 
 391 #ifdef ASSERT
 392 // Private method to check for dangling thread pointer
 393 void check_for_dangling_thread_pointer(Thread *thread) {
 394   assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
 395          "possibility of dangling Thread pointer");
 396 }
 397 #endif
 398 
 399 ThreadPriority Thread::get_priority(const Thread* const thread) {
 400   ThreadPriority priority;
 401   // Can return an error!
 402   (void)os::get_priority(thread, priority);
 403   assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
 404   return priority;
 405 }
 406 
 407 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
 408   debug_only(check_for_dangling_thread_pointer(thread);)
 409   // Can return an error!
 410   (void)os::set_priority(thread, priority);
 411 }
 412 
 413 
 414 void Thread::start(Thread* thread) {
 415   // Start is different from resume in that its safety is guaranteed by context or
 416   // being called from a Java method synchronized on the Thread object.
 417   if (!DisableStartThread) {
 418     if (thread->is_Java_thread()) {
 419       // Initialize the thread state to RUNNABLE before starting this thread.
 420       // Can not set it after the thread started because we do not know the
 421       // exact thread state at that time. It could be in MONITOR_WAIT or
 422       // in SLEEPING or some other state.
 423       java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
 424                                           java_lang_Thread::RUNNABLE);
 425     }
 426     os::start_thread(thread);
 427   }
 428 }
 429 
 430 // Enqueue a VM_Operation to do the job for us - sometime later
 431 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
 432   VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
 433   VMThread::execute(vm_stop);
 434 }
 435 
 436 
 437 // Check if an external suspend request has completed (or has been
 438 // cancelled). Returns true if the thread is externally suspended and
 439 // false otherwise.
 440 //
 441 // The bits parameter returns information about the code path through
 442 // the routine. Useful for debugging:
 443 //
 444 // set in is_ext_suspend_completed():
 445 // 0x00000001 - routine was entered
 446 // 0x00000010 - routine return false at end
 447 // 0x00000100 - thread exited (return false)
 448 // 0x00000200 - suspend request cancelled (return false)
 449 // 0x00000400 - thread suspended (return true)
 450 // 0x00001000 - thread is in a suspend equivalent state (return true)
 451 // 0x00002000 - thread is native and walkable (return true)
 452 // 0x00004000 - thread is native_trans and walkable (needed retry)
 453 //
 454 // set in wait_for_ext_suspend_completion():
 455 // 0x00010000 - routine was entered
 456 // 0x00020000 - suspend request cancelled before loop (return false)
 457 // 0x00040000 - thread suspended before loop (return true)
 458 // 0x00080000 - suspend request cancelled in loop (return false)
 459 // 0x00100000 - thread suspended in loop (return true)
 460 // 0x00200000 - suspend not completed during retry loop (return false)
 461 
 462 // Helper class for tracing suspend wait debug bits.
 463 //
 464 // 0x00000100 indicates that the target thread exited before it could
 465 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
 466 // 0x00080000 each indicate a cancelled suspend request so they don't
 467 // count as wait failures either.
 468 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
 469 
 470 class TraceSuspendDebugBits : public StackObj {
 471  private:
 472   JavaThread * jt;
 473   bool         is_wait;
 474   bool         called_by_wait;  // meaningful when !is_wait
 475   uint32_t *   bits;
 476 
 477  public:
 478   TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
 479                         uint32_t *_bits) {
 480     jt             = _jt;
 481     is_wait        = _is_wait;
 482     called_by_wait = _called_by_wait;
 483     bits           = _bits;
 484   }
 485 
 486   ~TraceSuspendDebugBits() {
 487     if (!is_wait) {
 488 #if 1
 489       // By default, don't trace bits for is_ext_suspend_completed() calls.
 490       // That trace is very chatty.
 491       return;
 492 #else
 493       if (!called_by_wait) {
 494         // If tracing for is_ext_suspend_completed() is enabled, then only
 495         // trace calls to it from wait_for_ext_suspend_completion()
 496         return;
 497       }
 498 #endif
 499     }
 500 
 501     if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
 502       if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
 503         MutexLocker ml(Threads_lock);  // needed for get_thread_name()
 504         ResourceMark rm;
 505 
 506         tty->print_cr(
 507                       "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
 508                       jt->get_thread_name(), *bits);
 509 
 510         guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
 511       }
 512     }
 513   }
 514 };
 515 #undef DEBUG_FALSE_BITS
 516 
 517 
 518 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
 519                                           uint32_t *bits) {
 520   TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
 521 
 522   bool did_trans_retry = false;  // only do thread_in_native_trans retry once
 523   bool do_trans_retry;           // flag to force the retry
 524 
 525   *bits |= 0x00000001;
 526 
 527   do {
 528     do_trans_retry = false;
 529 
 530     if (is_exiting()) {
 531       // Thread is in the process of exiting. This is always checked
 532       // first to reduce the risk of dereferencing a freed JavaThread.
 533       *bits |= 0x00000100;
 534       return false;
 535     }
 536 
 537     if (!is_external_suspend()) {
 538       // Suspend request is cancelled. This is always checked before
 539       // is_ext_suspended() to reduce the risk of a rogue resume
 540       // confusing the thread that made the suspend request.
 541       *bits |= 0x00000200;
 542       return false;
 543     }
 544 
 545     if (is_ext_suspended()) {
 546       // thread is suspended
 547       *bits |= 0x00000400;
 548       return true;
 549     }
 550 
 551     // Now that we no longer do hard suspends of threads running
 552     // native code, the target thread can be changing thread state
 553     // while we are in this routine:
 554     //
 555     //   _thread_in_native -> _thread_in_native_trans -> _thread_blocked
 556     //
 557     // We save a copy of the thread state as observed at this moment
 558     // and make our decision about suspend completeness based on the
 559     // copy. This closes the race where the thread state is seen as
 560     // _thread_in_native_trans in the if-thread_blocked check, but is
 561     // seen as _thread_blocked in if-thread_in_native_trans check.
 562     JavaThreadState save_state = thread_state();
 563 
 564     if (save_state == _thread_blocked && is_suspend_equivalent()) {
 565       // If the thread's state is _thread_blocked and this blocking
 566       // condition is known to be equivalent to a suspend, then we can
 567       // consider the thread to be externally suspended. This means that
 568       // the code that sets _thread_blocked has been modified to do
 569       // self-suspension if the blocking condition releases. We also
 570       // used to check for CONDVAR_WAIT here, but that is now covered by
 571       // the _thread_blocked with self-suspension check.
 572       //
 573       // Return true since we wouldn't be here unless there was still an
 574       // external suspend request.
 575       *bits |= 0x00001000;
 576       return true;
 577     } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
 578       // Threads running native code will self-suspend on native==>VM/Java
 579       // transitions. If its stack is walkable (should always be the case
 580       // unless this function is called before the actual java_suspend()
 581       // call), then the wait is done.
 582       *bits |= 0x00002000;
 583       return true;
 584     } else if (!called_by_wait && !did_trans_retry &&
 585                save_state == _thread_in_native_trans &&
 586                frame_anchor()->walkable()) {
 587       // The thread is transitioning from thread_in_native to another
 588       // thread state. check_safepoint_and_suspend_for_native_trans()
 589       // will force the thread to self-suspend. If it hasn't gotten
 590       // there yet we may have caught the thread in-between the native
 591       // code check above and the self-suspend. Lucky us. If we were
 592       // called by wait_for_ext_suspend_completion(), then it
 593       // will be doing the retries so we don't have to.
 594       //
 595       // Since we use the saved thread state in the if-statement above,
 596       // there is a chance that the thread has already transitioned to
 597       // _thread_blocked by the time we get here. In that case, we will
 598       // make a single unnecessary pass through the logic below. This
 599       // doesn't hurt anything since we still do the trans retry.
 600 
 601       *bits |= 0x00004000;
 602 
 603       // Once the thread leaves thread_in_native_trans for another
 604       // thread state, we break out of this retry loop. We shouldn't
 605       // need this flag to prevent us from getting back here, but
 606       // sometimes paranoia is good.
 607       did_trans_retry = true;
 608 
 609       // We wait for the thread to transition to a more usable state.
 610       for (int i = 1; i <= SuspendRetryCount; i++) {
 611         // We used to do an "os::yield_all(i)" call here with the intention
 612         // that yielding would increase on each retry. However, the parameter
 613         // is ignored on Linux which means the yield didn't scale up. Waiting
 614         // on the SR_lock below provides a much more predictable scale up for
 615         // the delay. It also provides a simple/direct point to check for any
 616         // safepoint requests from the VMThread
 617 
 618         // temporarily drops SR_lock while doing wait with safepoint check
 619         // (if we're a JavaThread - the WatcherThread can also call this)
 620         // and increase delay with each retry
 621         SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 622 
 623         // check the actual thread state instead of what we saved above
 624         if (thread_state() != _thread_in_native_trans) {
 625           // the thread has transitioned to another thread state so
 626           // try all the checks (except this one) one more time.
 627           do_trans_retry = true;
 628           break;
 629         }
 630       } // end retry loop
 631 
 632 
 633     }
 634   } while (do_trans_retry);
 635 
 636   *bits |= 0x00000010;
 637   return false;
 638 }
 639 
 640 // Wait for an external suspend request to complete (or be cancelled).
 641 // Returns true if the thread is externally suspended and false otherwise.
 642 //
 643 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
 644                                                  uint32_t *bits) {
 645   TraceSuspendDebugBits tsdb(this, true /* is_wait */,
 646                              false /* !called_by_wait */, bits);
 647 
 648   // local flag copies to minimize SR_lock hold time
 649   bool is_suspended;
 650   bool pending;
 651   uint32_t reset_bits;
 652 
 653   // set a marker so is_ext_suspend_completed() knows we are the caller
 654   *bits |= 0x00010000;
 655 
 656   // We use reset_bits to reinitialize the bits value at the top of
 657   // each retry loop. This allows the caller to make use of any
 658   // unused bits for their own marking purposes.
 659   reset_bits = *bits;
 660 
 661   {
 662     MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
 663     is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 664                                             delay, bits);
 665     pending = is_external_suspend();
 666   }
 667   // must release SR_lock to allow suspension to complete
 668 
 669   if (!pending) {
 670     // A cancelled suspend request is the only false return from
 671     // is_ext_suspend_completed() that keeps us from entering the
 672     // retry loop.
 673     *bits |= 0x00020000;
 674     return false;
 675   }
 676 
 677   if (is_suspended) {
 678     *bits |= 0x00040000;
 679     return true;
 680   }
 681 
 682   for (int i = 1; i <= retries; i++) {
 683     *bits = reset_bits;  // reinit to only track last retry
 684 
 685     // We used to do an "os::yield_all(i)" call here with the intention
 686     // that yielding would increase on each retry. However, the parameter
 687     // is ignored on Linux which means the yield didn't scale up. Waiting
 688     // on the SR_lock below provides a much more predictable scale up for
 689     // the delay. It also provides a simple/direct point to check for any
 690     // safepoint requests from the VMThread
 691 
 692     {
 693       MutexLocker ml(SR_lock());
 694       // wait with safepoint check (if we're a JavaThread - the WatcherThread
 695       // can also call this)  and increase delay with each retry
 696       SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 697 
 698       is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 699                                               delay, bits);
 700 
 701       // It is possible for the external suspend request to be cancelled
 702       // (by a resume) before the actual suspend operation is completed.
 703       // Refresh our local copy to see if we still need to wait.
 704       pending = is_external_suspend();
 705     }
 706 
 707     if (!pending) {
 708       // A cancelled suspend request is the only false return from
 709       // is_ext_suspend_completed() that keeps us from staying in the
 710       // retry loop.
 711       *bits |= 0x00080000;
 712       return false;
 713     }
 714 
 715     if (is_suspended) {
 716       *bits |= 0x00100000;
 717       return true;
 718     }
 719   } // end retry loop
 720 
 721   // thread did not suspend after all our retries
 722   *bits |= 0x00200000;
 723   return false;
 724 }
 725 
 726 #ifndef PRODUCT
 727 void JavaThread::record_jump(address target, address instr, const char* file,
 728                              int line) {
 729 
 730   // This should not need to be atomic as the only way for simultaneous
 731   // updates is via interrupts. Even then this should be rare or non-existent
 732   // and we don't care that much anyway.
 733 
 734   int index = _jmp_ring_index;
 735   _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
 736   _jmp_ring[index]._target = (intptr_t) target;
 737   _jmp_ring[index]._instruction = (intptr_t) instr;
 738   _jmp_ring[index]._file = file;
 739   _jmp_ring[index]._line = line;
 740 }
 741 #endif // PRODUCT
 742 
 743 // Called by flat profiler
 744 // Callers have already called wait_for_ext_suspend_completion
 745 // The assertion for that is currently too complex to put here:
 746 bool JavaThread::profile_last_Java_frame(frame* _fr) {
 747   bool gotframe = false;
 748   // self suspension saves needed state.
 749   if (has_last_Java_frame() && _anchor.walkable()) {
 750     *_fr = pd_last_frame();
 751     gotframe = true;
 752   }
 753   return gotframe;
 754 }
 755 
 756 void Thread::interrupt(Thread* thread) {
 757   debug_only(check_for_dangling_thread_pointer(thread);)
 758   os::interrupt(thread);
 759 }
 760 
 761 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
 762   debug_only(check_for_dangling_thread_pointer(thread);)
 763   // Note:  If clear_interrupted==false, this simply fetches and
 764   // returns the value of the field osthread()->interrupted().
 765   return os::is_interrupted(thread, clear_interrupted);
 766 }
 767 
 768 
 769 // GC Support
 770 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
 771   jint thread_parity = _oops_do_parity;
 772   if (thread_parity != strong_roots_parity) {
 773     jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
 774     if (res == thread_parity) {
 775       return true;
 776     } else {
 777       guarantee(res == strong_roots_parity, "Or else what?");
 778       return false;
 779     }
 780   }
 781   return false;
 782 }
 783 
 784 void Thread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
 785   active_handles()->oops_do(f);
 786   // Do oop for ThreadShadow
 787   f->do_oop((oop*)&_pending_exception);
 788   handle_area()->oops_do(f);
 789 }
 790 
 791 void Thread::nmethods_do(CodeBlobClosure* cf) {
 792   // no nmethods in a generic thread...
 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   if (is_VM_thread())                 st->print("VMThread");
 822   else if (is_Compiler_thread())      st->print("CompilerThread");
 823   else if (is_Java_thread())          st->print("JavaThread");
 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   st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
 830             p2i(stack_end()), p2i(stack_base()));
 831 
 832   if (osthread()) {
 833     st->print(" [id=%d]", osthread()->thread_id());
 834   }
 835 }
 836 
 837 #ifdef ASSERT
 838 void Thread::print_owned_locks_on(outputStream* st) const {
 839   Monitor *cur = _owned_locks;
 840   if (cur == NULL) {
 841     st->print(" (no locks) ");
 842   } else {
 843     st->print_cr(" Locks owned:");
 844     while (cur) {
 845       cur->print_on(st);
 846       cur = cur->next();
 847     }
 848   }
 849 }
 850 
 851 static int ref_use_count  = 0;
 852 
 853 bool Thread::owns_locks_but_compiled_lock() const {
 854   for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 855     if (cur != Compile_lock) return true;
 856   }
 857   return false;
 858 }
 859 
 860 
 861 #endif
 862 
 863 #ifndef PRODUCT
 864 
 865 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
 866 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
 867 // no threads which allow_vm_block's are held
 868 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
 869   // Check if current thread is allowed to block at a safepoint
 870   if (!(_allow_safepoint_count == 0)) {
 871     fatal("Possible safepoint reached by thread that does not allow it");
 872   }
 873   if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
 874     fatal("LEAF method calling lock?");
 875   }
 876 
 877 #ifdef ASSERT
 878   if (potential_vm_operation && is_Java_thread()
 879       && !Universe::is_bootstrapping()) {
 880     // Make sure we do not hold any locks that the VM thread also uses.
 881     // This could potentially lead to deadlocks
 882     for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 883       // Threads_lock is special, since the safepoint synchronization will not start before this is
 884       // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
 885       // since it is used to transfer control between JavaThreads and the VMThread
 886       // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
 887       if ((cur->allow_vm_block() &&
 888            cur != Threads_lock &&
 889            cur != Compile_lock &&               // Temporary: should not be necessary when we get separate compilation
 890            cur != VMOperationRequest_lock &&
 891            cur != VMOperationQueue_lock) ||
 892            cur->rank() == Mutex::special) {
 893         fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
 894       }
 895     }
 896   }
 897 
 898   if (GCALotAtAllSafepoints) {
 899     // We could enter a safepoint here and thus have a gc
 900     InterfaceSupport::check_gc_alot();
 901   }
 902 #endif
 903 }
 904 #endif
 905 
 906 bool Thread::is_in_stack(address adr) const {
 907   assert(Thread::current() == this, "is_in_stack can only be called from current thread");
 908   address end = os::current_stack_pointer();
 909   // Allow non Java threads to call this without stack_base
 910   if (_stack_base == NULL) return true;
 911   if (stack_base() >= adr && adr >= end) return true;
 912 
 913   return false;
 914 }
 915 
 916 bool Thread::is_in_usable_stack(address adr) const {
 917   size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
 918   size_t usable_stack_size = _stack_size - stack_guard_size;
 919 
 920   return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
 921 }
 922 
 923 
 924 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
 925 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
 926 // used for compilation in the future. If that change is made, the need for these methods
 927 // should be revisited, and they should be removed if possible.
 928 
 929 bool Thread::is_lock_owned(address adr) const {
 930   return on_local_stack(adr);
 931 }
 932 
 933 bool Thread::set_as_starting_thread() {
 934   // NOTE: this must be called inside the main thread.
 935   return os::create_main_thread((JavaThread*)this);
 936 }
 937 
 938 static void initialize_class(Symbol* class_name, TRAPS) {
 939   Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
 940   InstanceKlass::cast(klass)->initialize(CHECK);
 941 }
 942 
 943 
 944 // Creates the initial ThreadGroup
 945 static Handle create_initial_thread_group(TRAPS) {
 946   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
 947   instanceKlassHandle klass (THREAD, k);
 948 
 949   Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
 950   {
 951     JavaValue result(T_VOID);
 952     JavaCalls::call_special(&result,
 953                             system_instance,
 954                             klass,
 955                             vmSymbols::object_initializer_name(),
 956                             vmSymbols::void_method_signature(),
 957                             CHECK_NH);
 958   }
 959   Universe::set_system_thread_group(system_instance());
 960 
 961   Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
 962   {
 963     JavaValue result(T_VOID);
 964     Handle string = java_lang_String::create_from_str("main", CHECK_NH);
 965     JavaCalls::call_special(&result,
 966                             main_instance,
 967                             klass,
 968                             vmSymbols::object_initializer_name(),
 969                             vmSymbols::threadgroup_string_void_signature(),
 970                             system_instance,
 971                             string,
 972                             CHECK_NH);
 973   }
 974   return main_instance;
 975 }
 976 
 977 // Creates the initial Thread
 978 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
 979                                  TRAPS) {
 980   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
 981   instanceKlassHandle klass (THREAD, k);
 982   instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
 983 
 984   java_lang_Thread::set_thread(thread_oop(), thread);
 985   java_lang_Thread::set_priority(thread_oop(), NormPriority);
 986   thread->set_threadObj(thread_oop());
 987 
 988   Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
 989 
 990   JavaValue result(T_VOID);
 991   JavaCalls::call_special(&result, thread_oop,
 992                           klass,
 993                           vmSymbols::object_initializer_name(),
 994                           vmSymbols::threadgroup_string_void_signature(),
 995                           thread_group,
 996                           string,
 997                           CHECK_NULL);
 998   return thread_oop();
 999 }
1000 
1001 static void call_initializeSystemClass(TRAPS) {
1002   Klass* k =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1003   instanceKlassHandle klass (THREAD, k);
1004 
1005   JavaValue result(T_VOID);
1006   JavaCalls::call_static(&result, klass, vmSymbols::initializeSystemClass_name(),
1007                          vmSymbols::void_method_signature(), CHECK);
1008 }
1009 
1010 char java_runtime_name[128] = "";
1011 char java_runtime_version[128] = "";
1012 
1013 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1014 static const char* get_java_runtime_name(TRAPS) {
1015   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1016                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1017   fieldDescriptor fd;
1018   bool found = k != NULL &&
1019                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1020                                                         vmSymbols::string_signature(), &fd);
1021   if (found) {
1022     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1023     if (name_oop == NULL) {
1024       return NULL;
1025     }
1026     const char* name = java_lang_String::as_utf8_string(name_oop,
1027                                                         java_runtime_name,
1028                                                         sizeof(java_runtime_name));
1029     return name;
1030   } else {
1031     return NULL;
1032   }
1033 }
1034 
1035 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1036 static const char* get_java_runtime_version(TRAPS) {
1037   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1038                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1039   fieldDescriptor fd;
1040   bool found = k != NULL &&
1041                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1042                                                         vmSymbols::string_signature(), &fd);
1043   if (found) {
1044     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1045     if (name_oop == NULL) {
1046       return NULL;
1047     }
1048     const char* name = java_lang_String::as_utf8_string(name_oop,
1049                                                         java_runtime_version,
1050                                                         sizeof(java_runtime_version));
1051     return name;
1052   } else {
1053     return NULL;
1054   }
1055 }
1056 
1057 // General purpose hook into Java code, run once when the VM is initialized.
1058 // The Java library method itself may be changed independently from the VM.
1059 static void call_postVMInitHook(TRAPS) {
1060   Klass* k = SystemDictionary::resolve_or_null(vmSymbols::sun_misc_PostVMInitHook(), THREAD);
1061   instanceKlassHandle klass (THREAD, k);
1062   if (klass.not_null()) {
1063     JavaValue result(T_VOID);
1064     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1065                            vmSymbols::void_method_signature(),
1066                            CHECK);
1067   }
1068 }
1069 
1070 static void reset_vm_info_property(TRAPS) {
1071   // the vm info string
1072   ResourceMark rm(THREAD);
1073   const char *vm_info = VM_Version::vm_info_string();
1074 
1075   // java.lang.System class
1076   Klass* k =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1077   instanceKlassHandle klass (THREAD, k);
1078 
1079   // setProperty arguments
1080   Handle key_str    = java_lang_String::create_from_str("java.vm.info", CHECK);
1081   Handle value_str  = java_lang_String::create_from_str(vm_info, CHECK);
1082 
1083   // return value
1084   JavaValue r(T_OBJECT);
1085 
1086   // public static String setProperty(String key, String value);
1087   JavaCalls::call_static(&r,
1088                          klass,
1089                          vmSymbols::setProperty_name(),
1090                          vmSymbols::string_string_string_signature(),
1091                          key_str,
1092                          value_str,
1093                          CHECK);
1094 }
1095 
1096 
1097 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1098                                     bool daemon, TRAPS) {
1099   assert(thread_group.not_null(), "thread group should be specified");
1100   assert(threadObj() == NULL, "should only create Java thread object once");
1101 
1102   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1103   instanceKlassHandle klass (THREAD, k);
1104   instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1105 
1106   java_lang_Thread::set_thread(thread_oop(), this);
1107   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1108   set_threadObj(thread_oop());
1109 
1110   JavaValue result(T_VOID);
1111   if (thread_name != NULL) {
1112     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1113     // Thread gets assigned specified name and null target
1114     JavaCalls::call_special(&result,
1115                             thread_oop,
1116                             klass,
1117                             vmSymbols::object_initializer_name(),
1118                             vmSymbols::threadgroup_string_void_signature(),
1119                             thread_group, // Argument 1
1120                             name,         // Argument 2
1121                             THREAD);
1122   } else {
1123     // Thread gets assigned name "Thread-nnn" and null target
1124     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1125     JavaCalls::call_special(&result,
1126                             thread_oop,
1127                             klass,
1128                             vmSymbols::object_initializer_name(),
1129                             vmSymbols::threadgroup_runnable_void_signature(),
1130                             thread_group, // Argument 1
1131                             Handle(),     // Argument 2
1132                             THREAD);
1133   }
1134 
1135 
1136   if (daemon) {
1137     java_lang_Thread::set_daemon(thread_oop());
1138   }
1139 
1140   if (HAS_PENDING_EXCEPTION) {
1141     return;
1142   }
1143 
1144   KlassHandle group(THREAD, SystemDictionary::ThreadGroup_klass());
1145   Handle threadObj(THREAD, this->threadObj());
1146 
1147   JavaCalls::call_special(&result,
1148                           thread_group,
1149                           group,
1150                           vmSymbols::add_method_name(),
1151                           vmSymbols::thread_void_signature(),
1152                           threadObj,          // Arg 1
1153                           THREAD);
1154 }
1155 
1156 // NamedThread --  non-JavaThread subclasses with multiple
1157 // uniquely named instances should derive from this.
1158 NamedThread::NamedThread() : Thread() {
1159   _name = NULL;
1160   _processed_thread = NULL;
1161   _gc_id = GCId::undefined();
1162 }
1163 
1164 NamedThread::~NamedThread() {
1165   if (_name != NULL) {
1166     FREE_C_HEAP_ARRAY(char, _name);
1167     _name = NULL;
1168   }
1169 }
1170 
1171 void NamedThread::set_name(const char* format, ...) {
1172   guarantee(_name == NULL, "Only get to set name once.");
1173   _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1174   guarantee(_name != NULL, "alloc failure");
1175   va_list ap;
1176   va_start(ap, format);
1177   jio_vsnprintf(_name, max_name_len, format, ap);
1178   va_end(ap);
1179 }
1180 
1181 void NamedThread::initialize_named_thread() {
1182   set_native_thread_name(name());
1183 }
1184 
1185 void NamedThread::print_on(outputStream* st) const {
1186   st->print("\"%s\" ", name());
1187   Thread::print_on(st);
1188   st->cr();
1189 }
1190 
1191 
1192 // ======= WatcherThread ========
1193 
1194 // The watcher thread exists to simulate timer interrupts.  It should
1195 // be replaced by an abstraction over whatever native support for
1196 // timer interrupts exists on the platform.
1197 
1198 WatcherThread* WatcherThread::_watcher_thread   = NULL;
1199 bool WatcherThread::_startable = false;
1200 volatile bool  WatcherThread::_should_terminate = false;
1201 
1202 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) {
1203   assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1204   if (os::create_thread(this, os::watcher_thread)) {
1205     _watcher_thread = this;
1206 
1207     // Set the watcher thread to the highest OS priority which should not be
1208     // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1209     // is created. The only normal thread using this priority is the reference
1210     // handler thread, which runs for very short intervals only.
1211     // If the VMThread's priority is not lower than the WatcherThread profiling
1212     // will be inaccurate.
1213     os::set_priority(this, MaxPriority);
1214     if (!DisableStartThread) {
1215       os::start_thread(this);
1216     }
1217   }
1218 }
1219 
1220 int WatcherThread::sleep() const {
1221   // The WatcherThread does not participate in the safepoint protocol
1222   // for the PeriodicTask_lock because it is not a JavaThread.
1223   MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1224 
1225   if (_should_terminate) {
1226     // check for termination before we do any housekeeping or wait
1227     return 0;  // we did not sleep.
1228   }
1229 
1230   // remaining will be zero if there are no tasks,
1231   // causing the WatcherThread to sleep until a task is
1232   // enrolled
1233   int remaining = PeriodicTask::time_to_wait();
1234   int time_slept = 0;
1235 
1236   // we expect this to timeout - we only ever get unparked when
1237   // we should terminate or when a new task has been enrolled
1238   OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1239 
1240   jlong time_before_loop = os::javaTimeNanos();
1241 
1242   while (true) {
1243     bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1244                                             remaining);
1245     jlong now = os::javaTimeNanos();
1246 
1247     if (remaining == 0) {
1248       // if we didn't have any tasks we could have waited for a long time
1249       // consider the time_slept zero and reset time_before_loop
1250       time_slept = 0;
1251       time_before_loop = now;
1252     } else {
1253       // need to recalculate since we might have new tasks in _tasks
1254       time_slept = (int) ((now - time_before_loop) / 1000000);
1255     }
1256 
1257     // Change to task list or spurious wakeup of some kind
1258     if (timedout || _should_terminate) {
1259       break;
1260     }
1261 
1262     remaining = PeriodicTask::time_to_wait();
1263     if (remaining == 0) {
1264       // Last task was just disenrolled so loop around and wait until
1265       // another task gets enrolled
1266       continue;
1267     }
1268 
1269     remaining -= time_slept;
1270     if (remaining <= 0) {
1271       break;
1272     }
1273   }
1274 
1275   return time_slept;
1276 }
1277 
1278 void WatcherThread::run() {
1279   assert(this == watcher_thread(), "just checking");
1280 
1281   this->record_stack_base_and_size();
1282   this->set_native_thread_name(this->name());
1283   this->set_active_handles(JNIHandleBlock::allocate_block());
1284   while (true) {
1285     assert(watcher_thread() == Thread::current(), "thread consistency check");
1286     assert(watcher_thread() == this, "thread consistency check");
1287 
1288     // Calculate how long it'll be until the next PeriodicTask work
1289     // should be done, and sleep that amount of time.
1290     int time_waited = sleep();
1291 
1292     if (is_error_reported()) {
1293       // A fatal error has happened, the error handler(VMError::report_and_die)
1294       // should abort JVM after creating an error log file. However in some
1295       // rare cases, the error handler itself might deadlock. Here we try to
1296       // kill JVM if the fatal error handler fails to abort in 2 minutes.
1297       //
1298       // This code is in WatcherThread because WatcherThread wakes up
1299       // periodically so the fatal error handler doesn't need to do anything;
1300       // also because the WatcherThread is less likely to crash than other
1301       // threads.
1302 
1303       for (;;) {
1304         if (!ShowMessageBoxOnError
1305             && (OnError == NULL || OnError[0] == '\0')
1306             && Arguments::abort_hook() == NULL) {
1307           os::sleep(this, (jlong)ErrorLogTimeout * 1000, false); // in seconds
1308           fdStream err(defaultStream::output_fd());
1309           err.print_raw_cr("# [ timer expired, abort... ]");
1310           // skip atexit/vm_exit/vm_abort hooks
1311           os::die();
1312         }
1313 
1314         // Wake up 5 seconds later, the fatal handler may reset OnError or
1315         // ShowMessageBoxOnError when it is ready to abort.
1316         os::sleep(this, 5 * 1000, false);
1317       }
1318     }
1319 
1320     if (_should_terminate) {
1321       // check for termination before posting the next tick
1322       break;
1323     }
1324 
1325     PeriodicTask::real_time_tick(time_waited);
1326   }
1327 
1328   // Signal that it is terminated
1329   {
1330     MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1331     _watcher_thread = NULL;
1332     Terminator_lock->notify();
1333   }
1334 }
1335 
1336 void WatcherThread::start() {
1337   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1338 
1339   if (watcher_thread() == NULL && _startable) {
1340     _should_terminate = false;
1341     // Create the single instance of WatcherThread
1342     new WatcherThread();
1343   }
1344 }
1345 
1346 void WatcherThread::make_startable() {
1347   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1348   _startable = true;
1349 }
1350 
1351 void WatcherThread::stop() {
1352   {
1353     // Follow normal safepoint aware lock enter protocol since the
1354     // WatcherThread is stopped by another JavaThread.
1355     MutexLocker ml(PeriodicTask_lock);
1356     _should_terminate = true;
1357 
1358     WatcherThread* watcher = watcher_thread();
1359     if (watcher != NULL) {
1360       // unpark the WatcherThread so it can see that it should terminate
1361       watcher->unpark();
1362     }
1363   }
1364 
1365   MutexLocker mu(Terminator_lock);
1366 
1367   while (watcher_thread() != NULL) {
1368     // This wait should make safepoint checks, wait without a timeout,
1369     // and wait as a suspend-equivalent condition.
1370     //
1371     // Note: If the FlatProfiler is running, then this thread is waiting
1372     // for the WatcherThread to terminate and the WatcherThread, via the
1373     // FlatProfiler task, is waiting for the external suspend request on
1374     // this thread to complete. wait_for_ext_suspend_completion() will
1375     // eventually timeout, but that takes time. Making this wait a
1376     // suspend-equivalent condition solves that timeout problem.
1377     //
1378     Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1379                           Mutex::_as_suspend_equivalent_flag);
1380   }
1381 }
1382 
1383 void WatcherThread::unpark() {
1384   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1385   PeriodicTask_lock->notify();
1386 }
1387 
1388 void WatcherThread::print_on(outputStream* st) const {
1389   st->print("\"%s\" ", name());
1390   Thread::print_on(st);
1391   st->cr();
1392 }
1393 
1394 // ======= JavaThread ========
1395 
1396 #if INCLUDE_JVMCI
1397 
1398 jlong* JavaThread::_jvmci_old_thread_counters;
1399 
1400 bool jvmci_counters_include(JavaThread* thread) {
1401   oop threadObj = thread->threadObj();
1402   return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1403 }
1404 
1405 void JavaThread::collect_counters(typeArrayOop array) {
1406   if (JVMCICounterSize > 0) {
1407     MutexLocker tl(Threads_lock);
1408     for (int i = 0; i < array->length(); i++) {
1409       array->long_at_put(i, _jvmci_old_thread_counters[i]);
1410     }
1411     for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) {
1412       if (jvmci_counters_include(tp)) {
1413         for (int i = 0; i < array->length(); i++) {
1414           array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1415         }
1416       }
1417     }
1418   }
1419 }
1420 
1421 #endif // INCLUDE_JVMCI
1422 
1423 // A JavaThread is a normal Java thread
1424 
1425 void JavaThread::initialize() {
1426   // Initialize fields
1427 
1428   set_saved_exception_pc(NULL);
1429   set_threadObj(NULL);
1430   _anchor.clear();
1431   set_entry_point(NULL);
1432   set_jni_functions(jni_functions());
1433   set_callee_target(NULL);
1434   set_vm_result(NULL);
1435   set_vm_result_2(NULL);
1436   set_vframe_array_head(NULL);
1437   set_vframe_array_last(NULL);
1438   set_deferred_locals(NULL);
1439   set_deopt_mark(NULL);
1440   set_deopt_nmethod(NULL);
1441   clear_must_deopt_id();
1442   set_monitor_chunks(NULL);
1443   set_next(NULL);
1444   set_thread_state(_thread_new);
1445   _terminated = _not_terminated;
1446   _privileged_stack_top = NULL;
1447   _array_for_gc = NULL;
1448   _suspend_equivalent = false;
1449   _in_deopt_handler = 0;
1450   _doing_unsafe_access = false;
1451   _stack_guard_state = stack_guard_unused;
1452 #if INCLUDE_JVMCI
1453   _pending_monitorenter = false;
1454   _pending_deoptimization = -1;
1455   _pending_failed_speculation = NULL;
1456   _pending_transfer_to_interpreter = false;
1457   _jvmci._alternate_call_target = NULL;
1458   assert(_jvmci._implicit_exception_pc == NULL, "must be");
1459   if (JVMCICounterSize > 0) {
1460     _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1461     memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1462   } else {
1463     _jvmci_counters = NULL;
1464   }
1465 #endif // INCLUDE_JVMCI
1466   _reserved_stack_activation = NULL;  // stack base not known yet
1467   (void)const_cast<oop&>(_exception_oop = oop(NULL));
1468   _exception_pc  = 0;
1469   _exception_handler_pc = 0;
1470   _is_method_handle_return = 0;
1471   _jvmti_thread_state= NULL;
1472   _should_post_on_exceptions_flag = JNI_FALSE;
1473   _jvmti_get_loaded_classes_closure = NULL;
1474   _interp_only_mode    = 0;
1475   _special_runtime_exit_condition = _no_async_condition;
1476   _pending_async_exception = NULL;
1477   _thread_stat = NULL;
1478   _thread_stat = new ThreadStatistics();
1479   _blocked_on_compilation = false;
1480   _jni_active_critical = 0;
1481   _pending_jni_exception_check_fn = NULL;
1482   _do_not_unlock_if_synchronized = false;
1483   _cached_monitor_info = NULL;
1484   _parker = Parker::Allocate(this);
1485 
1486 #ifndef PRODUCT
1487   _jmp_ring_index = 0;
1488   for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1489     record_jump(NULL, NULL, NULL, 0);
1490   }
1491 #endif // PRODUCT
1492 
1493   set_thread_profiler(NULL);
1494   if (FlatProfiler::is_active()) {
1495     // This is where we would decide to either give each thread it's own profiler
1496     // or use one global one from FlatProfiler,
1497     // or up to some count of the number of profiled threads, etc.
1498     ThreadProfiler* pp = new ThreadProfiler();
1499     pp->engage();
1500     set_thread_profiler(pp);
1501   }
1502 
1503   // Setup safepoint state info for this thread
1504   ThreadSafepointState::create(this);
1505 
1506   debug_only(_java_call_counter = 0);
1507 
1508   // JVMTI PopFrame support
1509   _popframe_condition = popframe_inactive;
1510   _popframe_preserved_args = NULL;
1511   _popframe_preserved_args_size = 0;
1512   _frames_to_pop_failed_realloc = 0;
1513 
1514   pd_initialize();
1515 }
1516 
1517 #if INCLUDE_ALL_GCS
1518 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1519 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1520 #endif // INCLUDE_ALL_GCS
1521 
1522 JavaThread::JavaThread(bool is_attaching_via_jni) :
1523                        Thread()
1524 #if INCLUDE_ALL_GCS
1525                        , _satb_mark_queue(&_satb_mark_queue_set),
1526                        _dirty_card_queue(&_dirty_card_queue_set)
1527 #endif // INCLUDE_ALL_GCS
1528 {
1529   initialize();
1530   if (is_attaching_via_jni) {
1531     _jni_attach_state = _attaching_via_jni;
1532   } else {
1533     _jni_attach_state = _not_attaching_via_jni;
1534   }
1535   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1536 }
1537 
1538 bool JavaThread::reguard_stack(address cur_sp) {
1539   if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1540       && _stack_guard_state != stack_guard_reserved_disabled) {
1541     return true; // Stack already guarded or guard pages not needed.
1542   }
1543 
1544   if (register_stack_overflow()) {
1545     // For those architectures which have separate register and
1546     // memory stacks, we must check the register stack to see if
1547     // it has overflowed.
1548     return false;
1549   }
1550 
1551   // Java code never executes within the yellow zone: the latter is only
1552   // there to provoke an exception during stack banging.  If java code
1553   // is executing there, either StackShadowPages should be larger, or
1554   // some exception code in c1, c2 or the interpreter isn't unwinding
1555   // when it should.
1556   guarantee(cur_sp > stack_reserved_zone_base(),
1557             "not enough space to reguard - increase StackShadowPages");
1558   if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1559     enable_stack_yellow_reserved_zone();
1560     if (reserved_stack_activation() != stack_base()) {
1561       set_reserved_stack_activation(stack_base());
1562     }
1563   } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1564     set_reserved_stack_activation(stack_base());
1565     enable_stack_reserved_zone();
1566   }
1567   return true;
1568 }
1569 
1570 bool JavaThread::reguard_stack(void) {
1571   return reguard_stack(os::current_stack_pointer());
1572 }
1573 
1574 
1575 void JavaThread::block_if_vm_exited() {
1576   if (_terminated == _vm_exited) {
1577     // _vm_exited is set at safepoint, and Threads_lock is never released
1578     // we will block here forever
1579     Threads_lock->lock_without_safepoint_check();
1580     ShouldNotReachHere();
1581   }
1582 }
1583 
1584 
1585 // Remove this ifdef when C1 is ported to the compiler interface.
1586 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1587 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1588 
1589 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1590                        Thread()
1591 #if INCLUDE_ALL_GCS
1592                        , _satb_mark_queue(&_satb_mark_queue_set),
1593                        _dirty_card_queue(&_dirty_card_queue_set)
1594 #endif // INCLUDE_ALL_GCS
1595 {
1596   initialize();
1597   _jni_attach_state = _not_attaching_via_jni;
1598   set_entry_point(entry_point);
1599   // Create the native thread itself.
1600   // %note runtime_23
1601   os::ThreadType thr_type = os::java_thread;
1602   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1603                                                      os::java_thread;
1604   os::create_thread(this, thr_type, stack_sz);
1605   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1606   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1607   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1608   // the exception consists of creating the exception object & initializing it, initialization
1609   // will leave the VM via a JavaCall and then all locks must be unlocked).
1610   //
1611   // The thread is still suspended when we reach here. Thread must be explicit started
1612   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1613   // by calling Threads:add. The reason why this is not done here, is because the thread
1614   // object must be fully initialized (take a look at JVM_Start)
1615 }
1616 
1617 JavaThread::~JavaThread() {
1618 
1619   // JSR166 -- return the parker to the free list
1620   Parker::Release(_parker);
1621   _parker = NULL;
1622 
1623   // Free any remaining  previous UnrollBlock
1624   vframeArray* old_array = vframe_array_last();
1625 
1626   if (old_array != NULL) {
1627     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1628     old_array->set_unroll_block(NULL);
1629     delete old_info;
1630     delete old_array;
1631   }
1632 
1633   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1634   if (deferred != NULL) {
1635     // This can only happen if thread is destroyed before deoptimization occurs.
1636     assert(deferred->length() != 0, "empty array!");
1637     do {
1638       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1639       deferred->remove_at(0);
1640       // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1641       delete dlv;
1642     } while (deferred->length() != 0);
1643     delete deferred;
1644   }
1645 
1646   // All Java related clean up happens in exit
1647   ThreadSafepointState::destroy(this);
1648   if (_thread_profiler != NULL) delete _thread_profiler;
1649   if (_thread_stat != NULL) delete _thread_stat;
1650 
1651 #if INCLUDE_JVMCI
1652   if (JVMCICounterSize > 0) {
1653     if (jvmci_counters_include(this)) {
1654       for (int i = 0; i < JVMCICounterSize; i++) {
1655         _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1656       }
1657     }
1658     FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1659   }
1660 #endif // INCLUDE_JVMCI
1661 }
1662 
1663 
1664 // The first routine called by a new Java thread
1665 void JavaThread::run() {
1666   // initialize thread-local alloc buffer related fields
1667   this->initialize_tlab();
1668 
1669   // used to test validity of stack trace backs
1670   this->record_base_of_stack_pointer();
1671 
1672   // Record real stack base and size.
1673   this->record_stack_base_and_size();
1674 
1675   this->create_stack_guard_pages();
1676 
1677   this->cache_global_variables();
1678 
1679   // Thread is now sufficient initialized to be handled by the safepoint code as being
1680   // in the VM. Change thread state from _thread_new to _thread_in_vm
1681   ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1682 
1683   assert(JavaThread::current() == this, "sanity check");
1684   assert(!Thread::current()->owns_locks(), "sanity check");
1685 
1686   DTRACE_THREAD_PROBE(start, this);
1687 
1688   // This operation might block. We call that after all safepoint checks for a new thread has
1689   // been completed.
1690   this->set_active_handles(JNIHandleBlock::allocate_block());
1691 
1692   if (JvmtiExport::should_post_thread_life()) {
1693     JvmtiExport::post_thread_start(this);
1694   }
1695 
1696   EventThreadStart event;
1697   if (event.should_commit()) {
1698     event.set_thread(THREAD_TRACE_ID(this));
1699     event.commit();
1700   }
1701 
1702   // We call another function to do the rest so we are sure that the stack addresses used
1703   // from there will be lower than the stack base just computed
1704   thread_main_inner();
1705 
1706   // Note, thread is no longer valid at this point!
1707 }
1708 
1709 
1710 void JavaThread::thread_main_inner() {
1711   assert(JavaThread::current() == this, "sanity check");
1712   assert(this->threadObj() != NULL, "just checking");
1713 
1714   // Execute thread entry point unless this thread has a pending exception
1715   // or has been stopped before starting.
1716   // Note: Due to JVM_StopThread we can have pending exceptions already!
1717   if (!this->has_pending_exception() &&
1718       !java_lang_Thread::is_stillborn(this->threadObj())) {
1719     {
1720       ResourceMark rm(this);
1721       this->set_native_thread_name(this->get_thread_name());
1722     }
1723     HandleMark hm(this);
1724     this->entry_point()(this, this);
1725   }
1726 
1727   DTRACE_THREAD_PROBE(stop, this);
1728 
1729   this->exit(false);
1730   delete this;
1731 }
1732 
1733 
1734 static void ensure_join(JavaThread* thread) {
1735   // We do not need to grap the Threads_lock, since we are operating on ourself.
1736   Handle threadObj(thread, thread->threadObj());
1737   assert(threadObj.not_null(), "java thread object must exist");
1738   ObjectLocker lock(threadObj, thread);
1739   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1740   thread->clear_pending_exception();
1741   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1742   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1743   // Clear the native thread instance - this makes isAlive return false and allows the join()
1744   // to complete once we've done the notify_all below
1745   java_lang_Thread::set_thread(threadObj(), NULL);
1746   lock.notify_all(thread);
1747   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1748   thread->clear_pending_exception();
1749 }
1750 
1751 
1752 // For any new cleanup additions, please check to see if they need to be applied to
1753 // cleanup_failed_attach_current_thread as well.
1754 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1755   assert(this == JavaThread::current(), "thread consistency check");
1756 
1757   HandleMark hm(this);
1758   Handle uncaught_exception(this, this->pending_exception());
1759   this->clear_pending_exception();
1760   Handle threadObj(this, this->threadObj());
1761   assert(threadObj.not_null(), "Java thread object should be created");
1762 
1763   if (get_thread_profiler() != NULL) {
1764     get_thread_profiler()->disengage();
1765     ResourceMark rm;
1766     get_thread_profiler()->print(get_thread_name());
1767   }
1768 
1769 
1770   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1771   {
1772     EXCEPTION_MARK;
1773 
1774     CLEAR_PENDING_EXCEPTION;
1775   }
1776   if (!destroy_vm) {
1777     if (uncaught_exception.not_null()) {
1778       EXCEPTION_MARK;
1779       // Call method Thread.dispatchUncaughtException().
1780       KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1781       JavaValue result(T_VOID);
1782       JavaCalls::call_virtual(&result,
1783                               threadObj, thread_klass,
1784                               vmSymbols::dispatchUncaughtException_name(),
1785                               vmSymbols::throwable_void_signature(),
1786                               uncaught_exception,
1787                               THREAD);
1788       if (HAS_PENDING_EXCEPTION) {
1789         ResourceMark rm(this);
1790         jio_fprintf(defaultStream::error_stream(),
1791                     "\nException: %s thrown from the UncaughtExceptionHandler"
1792                     " in thread \"%s\"\n",
1793                     pending_exception()->klass()->external_name(),
1794                     get_thread_name());
1795         CLEAR_PENDING_EXCEPTION;
1796       }
1797     }
1798 
1799     // Called before the java thread exit since we want to read info
1800     // from java_lang_Thread object
1801     EventThreadEnd event;
1802     if (event.should_commit()) {
1803       event.set_thread(THREAD_TRACE_ID(this));
1804       event.commit();
1805     }
1806 
1807     // Call after last event on thread
1808     EVENT_THREAD_EXIT(this);
1809 
1810     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1811     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1812     // is deprecated anyhow.
1813     if (!is_Compiler_thread()) {
1814       int count = 3;
1815       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1816         EXCEPTION_MARK;
1817         JavaValue result(T_VOID);
1818         KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1819         JavaCalls::call_virtual(&result,
1820                                 threadObj, thread_klass,
1821                                 vmSymbols::exit_method_name(),
1822                                 vmSymbols::void_method_signature(),
1823                                 THREAD);
1824         CLEAR_PENDING_EXCEPTION;
1825       }
1826     }
1827     // notify JVMTI
1828     if (JvmtiExport::should_post_thread_life()) {
1829       JvmtiExport::post_thread_end(this);
1830     }
1831 
1832     // We have notified the agents that we are exiting, before we go on,
1833     // we must check for a pending external suspend request and honor it
1834     // in order to not surprise the thread that made the suspend request.
1835     while (true) {
1836       {
1837         MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1838         if (!is_external_suspend()) {
1839           set_terminated(_thread_exiting);
1840           ThreadService::current_thread_exiting(this);
1841           break;
1842         }
1843         // Implied else:
1844         // Things get a little tricky here. We have a pending external
1845         // suspend request, but we are holding the SR_lock so we
1846         // can't just self-suspend. So we temporarily drop the lock
1847         // and then self-suspend.
1848       }
1849 
1850       ThreadBlockInVM tbivm(this);
1851       java_suspend_self();
1852 
1853       // We're done with this suspend request, but we have to loop around
1854       // and check again. Eventually we will get SR_lock without a pending
1855       // external suspend request and will be able to mark ourselves as
1856       // exiting.
1857     }
1858     // no more external suspends are allowed at this point
1859   } else {
1860     // before_exit() has already posted JVMTI THREAD_END events
1861   }
1862 
1863   // Notify waiters on thread object. This has to be done after exit() is called
1864   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1865   // group should have the destroyed bit set before waiters are notified).
1866   ensure_join(this);
1867   assert(!this->has_pending_exception(), "ensure_join should have cleared");
1868 
1869   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1870   // held by this thread must be released. The spec does not distinguish
1871   // between JNI-acquired and regular Java monitors. We can only see
1872   // regular Java monitors here if monitor enter-exit matching is broken.
1873   //
1874   // Optionally release any monitors for regular JavaThread exits. This
1875   // is provided as a work around for any bugs in monitor enter-exit
1876   // matching. This can be expensive so it is not enabled by default.
1877   //
1878   // ensure_join() ignores IllegalThreadStateExceptions, and so does
1879   // ObjectSynchronizer::release_monitors_owned_by_thread().
1880   if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1881     // Sanity check even though JNI DetachCurrentThread() would have
1882     // returned JNI_ERR if there was a Java frame. JavaThread exit
1883     // should be done executing Java code by the time we get here.
1884     assert(!this->has_last_Java_frame(),
1885            "should not have a Java frame when detaching or exiting");
1886     ObjectSynchronizer::release_monitors_owned_by_thread(this);
1887     assert(!this->has_pending_exception(), "release_monitors should have cleared");
1888   }
1889 
1890   // These things needs to be done while we are still a Java Thread. Make sure that thread
1891   // is in a consistent state, in case GC happens
1892   assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1893 
1894   if (active_handles() != NULL) {
1895     JNIHandleBlock* block = active_handles();
1896     set_active_handles(NULL);
1897     JNIHandleBlock::release_block(block);
1898   }
1899 
1900   if (free_handle_block() != NULL) {
1901     JNIHandleBlock* block = free_handle_block();
1902     set_free_handle_block(NULL);
1903     JNIHandleBlock::release_block(block);
1904   }
1905 
1906   // These have to be removed while this is still a valid thread.
1907   remove_stack_guard_pages();
1908 
1909   if (UseTLAB) {
1910     tlab().make_parsable(true);  // retire TLAB
1911   }
1912 
1913   if (JvmtiEnv::environments_might_exist()) {
1914     JvmtiExport::cleanup_thread(this);
1915   }
1916 
1917   // We must flush any deferred card marks before removing a thread from
1918   // the list of active threads.
1919   Universe::heap()->flush_deferred_store_barrier(this);
1920   assert(deferred_card_mark().is_empty(), "Should have been flushed");
1921 
1922 #if INCLUDE_ALL_GCS
1923   // We must flush the G1-related buffers before removing a thread
1924   // from the list of active threads. We must do this after any deferred
1925   // card marks have been flushed (above) so that any entries that are
1926   // added to the thread's dirty card queue as a result are not lost.
1927   if (UseG1GC) {
1928     flush_barrier_queues();
1929   }
1930 #endif // INCLUDE_ALL_GCS
1931 
1932   log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
1933     exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
1934     os::current_thread_id());
1935 
1936   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1937   Threads::remove(this);
1938 }
1939 
1940 #if INCLUDE_ALL_GCS
1941 // Flush G1-related queues.
1942 void JavaThread::flush_barrier_queues() {
1943   satb_mark_queue().flush();
1944   dirty_card_queue().flush();
1945 }
1946 
1947 void JavaThread::initialize_queues() {
1948   assert(!SafepointSynchronize::is_at_safepoint(),
1949          "we should not be at a safepoint");
1950 
1951   SATBMarkQueue& satb_queue = satb_mark_queue();
1952   SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1953   // The SATB queue should have been constructed with its active
1954   // field set to false.
1955   assert(!satb_queue.is_active(), "SATB queue should not be active");
1956   assert(satb_queue.is_empty(), "SATB queue should be empty");
1957   // If we are creating the thread during a marking cycle, we should
1958   // set the active field of the SATB queue to true.
1959   if (satb_queue_set.is_active()) {
1960     satb_queue.set_active(true);
1961   }
1962 
1963   DirtyCardQueue& dirty_queue = dirty_card_queue();
1964   // The dirty card queue should have been constructed with its
1965   // active field set to true.
1966   assert(dirty_queue.is_active(), "dirty card queue should be active");
1967 }
1968 #endif // INCLUDE_ALL_GCS
1969 
1970 void JavaThread::cleanup_failed_attach_current_thread() {
1971   if (get_thread_profiler() != NULL) {
1972     get_thread_profiler()->disengage();
1973     ResourceMark rm;
1974     get_thread_profiler()->print(get_thread_name());
1975   }
1976 
1977   if (active_handles() != NULL) {
1978     JNIHandleBlock* block = active_handles();
1979     set_active_handles(NULL);
1980     JNIHandleBlock::release_block(block);
1981   }
1982 
1983   if (free_handle_block() != NULL) {
1984     JNIHandleBlock* block = free_handle_block();
1985     set_free_handle_block(NULL);
1986     JNIHandleBlock::release_block(block);
1987   }
1988 
1989   // These have to be removed while this is still a valid thread.
1990   remove_stack_guard_pages();
1991 
1992   if (UseTLAB) {
1993     tlab().make_parsable(true);  // retire TLAB, if any
1994   }
1995 
1996 #if INCLUDE_ALL_GCS
1997   if (UseG1GC) {
1998     flush_barrier_queues();
1999   }
2000 #endif // INCLUDE_ALL_GCS
2001 
2002   Threads::remove(this);
2003   delete this;
2004 }
2005 
2006 
2007 
2008 
2009 JavaThread* JavaThread::active() {
2010   Thread* thread = Thread::current();
2011   if (thread->is_Java_thread()) {
2012     return (JavaThread*) thread;
2013   } else {
2014     assert(thread->is_VM_thread(), "this must be a vm thread");
2015     VM_Operation* op = ((VMThread*) thread)->vm_operation();
2016     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2017     assert(ret->is_Java_thread(), "must be a Java thread");
2018     return ret;
2019   }
2020 }
2021 
2022 bool JavaThread::is_lock_owned(address adr) const {
2023   if (Thread::is_lock_owned(adr)) return true;
2024 
2025   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2026     if (chunk->contains(adr)) return true;
2027   }
2028 
2029   return false;
2030 }
2031 
2032 
2033 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2034   chunk->set_next(monitor_chunks());
2035   set_monitor_chunks(chunk);
2036 }
2037 
2038 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2039   guarantee(monitor_chunks() != NULL, "must be non empty");
2040   if (monitor_chunks() == chunk) {
2041     set_monitor_chunks(chunk->next());
2042   } else {
2043     MonitorChunk* prev = monitor_chunks();
2044     while (prev->next() != chunk) prev = prev->next();
2045     prev->set_next(chunk->next());
2046   }
2047 }
2048 
2049 // JVM support.
2050 
2051 // Note: this function shouldn't block if it's called in
2052 // _thread_in_native_trans state (such as from
2053 // check_special_condition_for_native_trans()).
2054 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2055 
2056   if (has_last_Java_frame() && has_async_condition()) {
2057     // If we are at a polling page safepoint (not a poll return)
2058     // then we must defer async exception because live registers
2059     // will be clobbered by the exception path. Poll return is
2060     // ok because the call we a returning from already collides
2061     // with exception handling registers and so there is no issue.
2062     // (The exception handling path kills call result registers but
2063     //  this is ok since the exception kills the result anyway).
2064 
2065     if (is_at_poll_safepoint()) {
2066       // if the code we are returning to has deoptimized we must defer
2067       // the exception otherwise live registers get clobbered on the
2068       // exception path before deoptimization is able to retrieve them.
2069       //
2070       RegisterMap map(this, false);
2071       frame caller_fr = last_frame().sender(&map);
2072       assert(caller_fr.is_compiled_frame(), "what?");
2073       if (caller_fr.is_deoptimized_frame()) {
2074         log_info(exceptions)("deferred async exception at compiled safepoint");
2075         return;
2076       }
2077     }
2078   }
2079 
2080   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2081   if (condition == _no_async_condition) {
2082     // Conditions have changed since has_special_runtime_exit_condition()
2083     // was called:
2084     // - if we were here only because of an external suspend request,
2085     //   then that was taken care of above (or cancelled) so we are done
2086     // - if we were here because of another async request, then it has
2087     //   been cleared between the has_special_runtime_exit_condition()
2088     //   and now so again we are done
2089     return;
2090   }
2091 
2092   // Check for pending async. exception
2093   if (_pending_async_exception != NULL) {
2094     // Only overwrite an already pending exception, if it is not a threadDeath.
2095     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2096 
2097       // We cannot call Exceptions::_throw(...) here because we cannot block
2098       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2099 
2100       if (log_is_enabled(Info, exceptions)) {
2101         ResourceMark rm;
2102         outputStream* logstream = LogHandle(exceptions)::info_stream();
2103         logstream->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2104           if (has_last_Java_frame()) {
2105             frame f = last_frame();
2106            logstream->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2107           }
2108         logstream->print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2109       }
2110       _pending_async_exception = NULL;
2111       clear_has_async_exception();
2112     }
2113   }
2114 
2115   if (check_unsafe_error &&
2116       condition == _async_unsafe_access_error && !has_pending_exception()) {
2117     condition = _no_async_condition;  // done
2118     switch (thread_state()) {
2119     case _thread_in_vm: {
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_native: {
2124       ThreadInVMfromNative tiv(this);
2125       JavaThread* THREAD = this;
2126       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2127     }
2128     case _thread_in_Java: {
2129       ThreadInVMfromJava tiv(this);
2130       JavaThread* THREAD = this;
2131       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2132     }
2133     default:
2134       ShouldNotReachHere();
2135     }
2136   }
2137 
2138   assert(condition == _no_async_condition || has_pending_exception() ||
2139          (!check_unsafe_error && condition == _async_unsafe_access_error),
2140          "must have handled the async condition, if no exception");
2141 }
2142 
2143 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2144   //
2145   // Check for pending external suspend. Internal suspend requests do
2146   // not use handle_special_runtime_exit_condition().
2147   // If JNIEnv proxies are allowed, don't self-suspend if the target
2148   // thread is not the current thread. In older versions of jdbx, jdbx
2149   // threads could call into the VM with another thread's JNIEnv so we
2150   // can be here operating on behalf of a suspended thread (4432884).
2151   bool do_self_suspend = is_external_suspend_with_lock();
2152   if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2153     //
2154     // Because thread is external suspended the safepoint code will count
2155     // thread as at a safepoint. This can be odd because we can be here
2156     // as _thread_in_Java which would normally transition to _thread_blocked
2157     // at a safepoint. We would like to mark the thread as _thread_blocked
2158     // before calling java_suspend_self like all other callers of it but
2159     // we must then observe proper safepoint protocol. (We can't leave
2160     // _thread_blocked with a safepoint in progress). However we can be
2161     // here as _thread_in_native_trans so we can't use a normal transition
2162     // constructor/destructor pair because they assert on that type of
2163     // transition. We could do something like:
2164     //
2165     // JavaThreadState state = thread_state();
2166     // set_thread_state(_thread_in_vm);
2167     // {
2168     //   ThreadBlockInVM tbivm(this);
2169     //   java_suspend_self()
2170     // }
2171     // set_thread_state(_thread_in_vm_trans);
2172     // if (safepoint) block;
2173     // set_thread_state(state);
2174     //
2175     // but that is pretty messy. Instead we just go with the way the
2176     // code has worked before and note that this is the only path to
2177     // java_suspend_self that doesn't put the thread in _thread_blocked
2178     // mode.
2179 
2180     frame_anchor()->make_walkable(this);
2181     java_suspend_self();
2182 
2183     // We might be here for reasons in addition to the self-suspend request
2184     // so check for other async requests.
2185   }
2186 
2187   if (check_asyncs) {
2188     check_and_handle_async_exceptions();
2189   }
2190 }
2191 
2192 void JavaThread::send_thread_stop(oop java_throwable)  {
2193   assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2194   assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2195   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2196 
2197   // Do not throw asynchronous exceptions against the compiler thread
2198   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2199   if (!can_call_java()) return;
2200 
2201   {
2202     // Actually throw the Throwable against the target Thread - however
2203     // only if there is no thread death exception installed already.
2204     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2205       // If the topmost frame is a runtime stub, then we are calling into
2206       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2207       // must deoptimize the caller before continuing, as the compiled  exception handler table
2208       // may not be valid
2209       if (has_last_Java_frame()) {
2210         frame f = last_frame();
2211         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2212           // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2213           RegisterMap reg_map(this, UseBiasedLocking);
2214           frame compiled_frame = f.sender(&reg_map);
2215           if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2216             Deoptimization::deoptimize(this, compiled_frame, &reg_map);
2217           }
2218         }
2219       }
2220 
2221       // Set async. pending exception in thread.
2222       set_pending_async_exception(java_throwable);
2223 
2224       if (log_is_enabled(Info, exceptions)) {
2225          ResourceMark rm;
2226         log_info(exceptions)("Pending Async. exception installed of type: %s",
2227                              InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2228       }
2229       // for AbortVMOnException flag
2230       Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2231     }
2232   }
2233 
2234 
2235   // Interrupt thread so it will wake up from a potential wait()
2236   Thread::interrupt(this);
2237 }
2238 
2239 // External suspension mechanism.
2240 //
2241 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2242 // to any VM_locks and it is at a transition
2243 // Self-suspension will happen on the transition out of the vm.
2244 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2245 //
2246 // Guarantees on return:
2247 //   + Target thread will not execute any new bytecode (that's why we need to
2248 //     force a safepoint)
2249 //   + Target thread will not enter any new monitors
2250 //
2251 void JavaThread::java_suspend() {
2252   { MutexLocker mu(Threads_lock);
2253     if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2254       return;
2255     }
2256   }
2257 
2258   { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2259     if (!is_external_suspend()) {
2260       // a racing resume has cancelled us; bail out now
2261       return;
2262     }
2263 
2264     // suspend is done
2265     uint32_t debug_bits = 0;
2266     // Warning: is_ext_suspend_completed() may temporarily drop the
2267     // SR_lock to allow the thread to reach a stable thread state if
2268     // it is currently in a transient thread state.
2269     if (is_ext_suspend_completed(false /* !called_by_wait */,
2270                                  SuspendRetryDelay, &debug_bits)) {
2271       return;
2272     }
2273   }
2274 
2275   VM_ForceSafepoint vm_suspend;
2276   VMThread::execute(&vm_suspend);
2277 }
2278 
2279 // Part II of external suspension.
2280 // A JavaThread self suspends when it detects a pending external suspend
2281 // request. This is usually on transitions. It is also done in places
2282 // where continuing to the next transition would surprise the caller,
2283 // e.g., monitor entry.
2284 //
2285 // Returns the number of times that the thread self-suspended.
2286 //
2287 // Note: DO NOT call java_suspend_self() when you just want to block current
2288 //       thread. java_suspend_self() is the second stage of cooperative
2289 //       suspension for external suspend requests and should only be used
2290 //       to complete an external suspend request.
2291 //
2292 int JavaThread::java_suspend_self() {
2293   int ret = 0;
2294 
2295   // we are in the process of exiting so don't suspend
2296   if (is_exiting()) {
2297     clear_external_suspend();
2298     return ret;
2299   }
2300 
2301   assert(_anchor.walkable() ||
2302          (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2303          "must have walkable stack");
2304 
2305   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2306 
2307   assert(!this->is_ext_suspended(),
2308          "a thread trying to self-suspend should not already be suspended");
2309 
2310   if (this->is_suspend_equivalent()) {
2311     // If we are self-suspending as a result of the lifting of a
2312     // suspend equivalent condition, then the suspend_equivalent
2313     // flag is not cleared until we set the ext_suspended flag so
2314     // that wait_for_ext_suspend_completion() returns consistent
2315     // results.
2316     this->clear_suspend_equivalent();
2317   }
2318 
2319   // A racing resume may have cancelled us before we grabbed SR_lock
2320   // above. Or another external suspend request could be waiting for us
2321   // by the time we return from SR_lock()->wait(). The thread
2322   // that requested the suspension may already be trying to walk our
2323   // stack and if we return now, we can change the stack out from under
2324   // it. This would be a "bad thing (TM)" and cause the stack walker
2325   // to crash. We stay self-suspended until there are no more pending
2326   // external suspend requests.
2327   while (is_external_suspend()) {
2328     ret++;
2329     this->set_ext_suspended();
2330 
2331     // _ext_suspended flag is cleared by java_resume()
2332     while (is_ext_suspended()) {
2333       this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2334     }
2335   }
2336 
2337   return ret;
2338 }
2339 
2340 #ifdef ASSERT
2341 // verify the JavaThread has not yet been published in the Threads::list, and
2342 // hence doesn't need protection from concurrent access at this stage
2343 void JavaThread::verify_not_published() {
2344   if (!Threads_lock->owned_by_self()) {
2345     MutexLockerEx ml(Threads_lock,  Mutex::_no_safepoint_check_flag);
2346     assert(!Threads::includes(this),
2347            "java thread shouldn't have been published yet!");
2348   } else {
2349     assert(!Threads::includes(this),
2350            "java thread shouldn't have been published yet!");
2351   }
2352 }
2353 #endif
2354 
2355 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2356 // progress or when _suspend_flags is non-zero.
2357 // Current thread needs to self-suspend if there is a suspend request and/or
2358 // block if a safepoint is in progress.
2359 // Async exception ISN'T checked.
2360 // Note only the ThreadInVMfromNative transition can call this function
2361 // directly and when thread state is _thread_in_native_trans
2362 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2363   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2364 
2365   JavaThread *curJT = JavaThread::current();
2366   bool do_self_suspend = thread->is_external_suspend();
2367 
2368   assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2369 
2370   // If JNIEnv proxies are allowed, don't self-suspend if the target
2371   // thread is not the current thread. In older versions of jdbx, jdbx
2372   // threads could call into the VM with another thread's JNIEnv so we
2373   // can be here operating on behalf of a suspended thread (4432884).
2374   if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2375     JavaThreadState state = thread->thread_state();
2376 
2377     // We mark this thread_blocked state as a suspend-equivalent so
2378     // that a caller to is_ext_suspend_completed() won't be confused.
2379     // The suspend-equivalent state is cleared by java_suspend_self().
2380     thread->set_suspend_equivalent();
2381 
2382     // If the safepoint code sees the _thread_in_native_trans state, it will
2383     // wait until the thread changes to other thread state. There is no
2384     // guarantee on how soon we can obtain the SR_lock and complete the
2385     // self-suspend request. It would be a bad idea to let safepoint wait for
2386     // too long. Temporarily change the state to _thread_blocked to
2387     // let the VM thread know that this thread is ready for GC. The problem
2388     // of changing thread state is that safepoint could happen just after
2389     // java_suspend_self() returns after being resumed, and VM thread will
2390     // see the _thread_blocked state. We must check for safepoint
2391     // after restoring the state and make sure we won't leave while a safepoint
2392     // is in progress.
2393     thread->set_thread_state(_thread_blocked);
2394     thread->java_suspend_self();
2395     thread->set_thread_state(state);
2396     // Make sure new state is seen by VM thread
2397     if (os::is_MP()) {
2398       if (UseMembar) {
2399         // Force a fence between the write above and read below
2400         OrderAccess::fence();
2401       } else {
2402         // Must use this rather than serialization page in particular on Windows
2403         InterfaceSupport::serialize_memory(thread);
2404       }
2405     }
2406   }
2407 
2408   if (SafepointSynchronize::do_call_back()) {
2409     // If we are safepointing, then block the caller which may not be
2410     // the same as the target thread (see above).
2411     SafepointSynchronize::block(curJT);
2412   }
2413 
2414   if (thread->is_deopt_suspend()) {
2415     thread->clear_deopt_suspend();
2416     RegisterMap map(thread, false);
2417     frame f = thread->last_frame();
2418     while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2419       f = f.sender(&map);
2420     }
2421     if (f.id() == thread->must_deopt_id()) {
2422       thread->clear_must_deopt_id();
2423       f.deoptimize(thread);
2424     } else {
2425       fatal("missed deoptimization!");
2426     }
2427   }
2428 }
2429 
2430 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2431 // progress or when _suspend_flags is non-zero.
2432 // Current thread needs to self-suspend if there is a suspend request and/or
2433 // block if a safepoint is in progress.
2434 // Also check for pending async exception (not including unsafe access error).
2435 // Note only the native==>VM/Java barriers can call this function and when
2436 // thread state is _thread_in_native_trans.
2437 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2438   check_safepoint_and_suspend_for_native_trans(thread);
2439 
2440   if (thread->has_async_exception()) {
2441     // We are in _thread_in_native_trans state, don't handle unsafe
2442     // access error since that may block.
2443     thread->check_and_handle_async_exceptions(false);
2444   }
2445 }
2446 
2447 // This is a variant of the normal
2448 // check_special_condition_for_native_trans with slightly different
2449 // semantics for use by critical native wrappers.  It does all the
2450 // normal checks but also performs the transition back into
2451 // thread_in_Java state.  This is required so that critical natives
2452 // can potentially block and perform a GC if they are the last thread
2453 // exiting the GCLocker.
2454 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2455   check_special_condition_for_native_trans(thread);
2456 
2457   // Finish the transition
2458   thread->set_thread_state(_thread_in_Java);
2459 
2460   if (thread->do_critical_native_unlock()) {
2461     ThreadInVMfromJavaNoAsyncException tiv(thread);
2462     GCLocker::unlock_critical(thread);
2463     thread->clear_critical_native_unlock();
2464   }
2465 }
2466 
2467 // We need to guarantee the Threads_lock here, since resumes are not
2468 // allowed during safepoint synchronization
2469 // Can only resume from an external suspension
2470 void JavaThread::java_resume() {
2471   assert_locked_or_safepoint(Threads_lock);
2472 
2473   // Sanity check: thread is gone, has started exiting or the thread
2474   // was not externally suspended.
2475   if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2476     return;
2477   }
2478 
2479   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2480 
2481   clear_external_suspend();
2482 
2483   if (is_ext_suspended()) {
2484     clear_ext_suspended();
2485     SR_lock()->notify_all();
2486   }
2487 }
2488 
2489 size_t JavaThread::_stack_red_zone_size = 0;
2490 size_t JavaThread::_stack_yellow_zone_size = 0;
2491 size_t JavaThread::_stack_reserved_zone_size = 0;
2492 size_t JavaThread::_stack_shadow_zone_size = 0;
2493 
2494 void JavaThread::create_stack_guard_pages() {
2495   if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; }
2496   address low_addr = stack_end();
2497   size_t len = stack_guard_zone_size();
2498 
2499   int allocate = os::allocate_stack_guard_pages();
2500   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2501 
2502   if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) {
2503     log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2504     return;
2505   }
2506 
2507   if (os::guard_memory((char *) low_addr, len)) {
2508     _stack_guard_state = stack_guard_enabled;
2509   } else {
2510     log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2511       PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2512     if (os::uncommit_memory((char *) low_addr, len)) {
2513       log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2514     }
2515     return;
2516   }
2517 
2518   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2519     PTR_FORMAT "-" PTR_FORMAT ".",
2520     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2521 
2522 }
2523 
2524 void JavaThread::remove_stack_guard_pages() {
2525   assert(Thread::current() == this, "from different thread");
2526   if (_stack_guard_state == stack_guard_unused) return;
2527   address low_addr = stack_end();
2528   size_t len = stack_guard_zone_size();
2529 
2530   if (os::allocate_stack_guard_pages()) {
2531     if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2532       _stack_guard_state = stack_guard_unused;
2533     } else {
2534       log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2535         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2536       return;
2537     }
2538   } else {
2539     if (_stack_guard_state == stack_guard_unused) return;
2540     if (os::unguard_memory((char *) low_addr, len)) {
2541       _stack_guard_state = stack_guard_unused;
2542     } else {
2543       log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2544         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2545       return;
2546     }
2547   }
2548 
2549   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2550     PTR_FORMAT "-" PTR_FORMAT ".",
2551     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2552 
2553 }
2554 
2555 void JavaThread::enable_stack_reserved_zone() {
2556   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2557   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2558 
2559   // The base notation is from the stack's point of view, growing downward.
2560   // We need to adjust it to work correctly with guard_memory()
2561   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2562 
2563   guarantee(base < stack_base(),"Error calculating stack reserved zone");
2564   guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2565 
2566   if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2567     _stack_guard_state = stack_guard_enabled;
2568   } else {
2569     warning("Attempt to guard stack reserved zone failed.");
2570   }
2571   enable_register_stack_guard();
2572 }
2573 
2574 void JavaThread::disable_stack_reserved_zone() {
2575   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2576   assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2577 
2578   // Simply return if called for a thread that does not use guard pages.
2579   if (_stack_guard_state == stack_guard_unused) return;
2580 
2581   // The base notation is from the stack's point of view, growing downward.
2582   // We need to adjust it to work correctly with guard_memory()
2583   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2584 
2585   if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2586     _stack_guard_state = stack_guard_reserved_disabled;
2587   } else {
2588     warning("Attempt to unguard stack reserved zone failed.");
2589   }
2590   disable_register_stack_guard();
2591 }
2592 
2593 void JavaThread::enable_stack_yellow_reserved_zone() {
2594   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2595   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2596 
2597   // The base notation is from the stacks point of view, growing downward.
2598   // We need to adjust it to work correctly with guard_memory()
2599   address base = stack_red_zone_base();
2600 
2601   guarantee(base < stack_base(), "Error calculating stack yellow zone");
2602   guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2603 
2604   if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2605     _stack_guard_state = stack_guard_enabled;
2606   } else {
2607     warning("Attempt to guard stack yellow zone failed.");
2608   }
2609   enable_register_stack_guard();
2610 }
2611 
2612 void JavaThread::disable_stack_yellow_reserved_zone() {
2613   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2614   assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2615 
2616   // Simply return if called for a thread that does not use guard pages.
2617   if (_stack_guard_state == stack_guard_unused) return;
2618 
2619   // The base notation is from the stacks point of view, growing downward.
2620   // We need to adjust it to work correctly with guard_memory()
2621   address base = stack_red_zone_base();
2622 
2623   if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2624     _stack_guard_state = stack_guard_yellow_reserved_disabled;
2625   } else {
2626     warning("Attempt to unguard stack yellow zone failed.");
2627   }
2628   disable_register_stack_guard();
2629 }
2630 
2631 void JavaThread::enable_stack_red_zone() {
2632   // The base notation is from the stacks point of view, growing downward.
2633   // We need to adjust it to work correctly with guard_memory()
2634   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2635   address base = stack_red_zone_base() - stack_red_zone_size();
2636 
2637   guarantee(base < stack_base(), "Error calculating stack red zone");
2638   guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2639 
2640   if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2641     warning("Attempt to guard stack red zone failed.");
2642   }
2643 }
2644 
2645 void JavaThread::disable_stack_red_zone() {
2646   // The base notation is from the stacks point of view, growing downward.
2647   // We need to adjust it to work correctly with guard_memory()
2648   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2649   address base = stack_red_zone_base() - stack_red_zone_size();
2650   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2651     warning("Attempt to unguard stack red zone failed.");
2652   }
2653 }
2654 
2655 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2656   // ignore is there is no stack
2657   if (!has_last_Java_frame()) return;
2658   // traverse the stack frames. Starts from top frame.
2659   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2660     frame* fr = fst.current();
2661     f(fr, fst.register_map());
2662   }
2663 }
2664 
2665 
2666 #ifndef PRODUCT
2667 // Deoptimization
2668 // Function for testing deoptimization
2669 void JavaThread::deoptimize() {
2670   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2671   StackFrameStream fst(this, UseBiasedLocking);
2672   bool deopt = false;           // Dump stack only if a deopt actually happens.
2673   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2674   // Iterate over all frames in the thread and deoptimize
2675   for (; !fst.is_done(); fst.next()) {
2676     if (fst.current()->can_be_deoptimized()) {
2677 
2678       if (only_at) {
2679         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
2680         // consists of comma or carriage return separated numbers so
2681         // search for the current bci in that string.
2682         address pc = fst.current()->pc();
2683         nmethod* nm =  (nmethod*) fst.current()->cb();
2684         ScopeDesc* sd = nm->scope_desc_at(pc);
2685         char buffer[8];
2686         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2687         size_t len = strlen(buffer);
2688         const char * found = strstr(DeoptimizeOnlyAt, buffer);
2689         while (found != NULL) {
2690           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2691               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2692             // Check that the bci found is bracketed by terminators.
2693             break;
2694           }
2695           found = strstr(found + 1, buffer);
2696         }
2697         if (!found) {
2698           continue;
2699         }
2700       }
2701 
2702       if (DebugDeoptimization && !deopt) {
2703         deopt = true; // One-time only print before deopt
2704         tty->print_cr("[BEFORE Deoptimization]");
2705         trace_frames();
2706         trace_stack();
2707       }
2708       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2709     }
2710   }
2711 
2712   if (DebugDeoptimization && deopt) {
2713     tty->print_cr("[AFTER Deoptimization]");
2714     trace_frames();
2715   }
2716 }
2717 
2718 
2719 // Make zombies
2720 void JavaThread::make_zombies() {
2721   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2722     if (fst.current()->can_be_deoptimized()) {
2723       // it is a Java nmethod
2724       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2725       nm->make_not_entrant();
2726     }
2727   }
2728 }
2729 #endif // PRODUCT
2730 
2731 
2732 void JavaThread::deoptimized_wrt_marked_nmethods() {
2733   if (!has_last_Java_frame()) return;
2734   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2735   StackFrameStream fst(this, UseBiasedLocking);
2736   for (; !fst.is_done(); fst.next()) {
2737     if (fst.current()->should_be_deoptimized()) {
2738       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2739     }
2740   }
2741 }
2742 
2743 
2744 // If the caller is a NamedThread, then remember, in the current scope,
2745 // the given JavaThread in its _processed_thread field.
2746 class RememberProcessedThread: public StackObj {
2747   NamedThread* _cur_thr;
2748  public:
2749   RememberProcessedThread(JavaThread* jthr) {
2750     Thread* thread = Thread::current();
2751     if (thread->is_Named_thread()) {
2752       _cur_thr = (NamedThread *)thread;
2753       _cur_thr->set_processed_thread(jthr);
2754     } else {
2755       _cur_thr = NULL;
2756     }
2757   }
2758 
2759   ~RememberProcessedThread() {
2760     if (_cur_thr) {
2761       _cur_thr->set_processed_thread(NULL);
2762     }
2763   }
2764 };
2765 
2766 void JavaThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
2767   // Verify that the deferred card marks have been flushed.
2768   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2769 
2770   // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2771   // since there may be more than one thread using each ThreadProfiler.
2772 
2773   // Traverse the GCHandles
2774   Thread::oops_do(f, cld_f, cf);
2775 
2776   JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2777 
2778   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2779          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2780 
2781   if (has_last_Java_frame()) {
2782     // Record JavaThread to GC thread
2783     RememberProcessedThread rpt(this);
2784 
2785     // Traverse the privileged stack
2786     if (_privileged_stack_top != NULL) {
2787       _privileged_stack_top->oops_do(f);
2788     }
2789 
2790     // traverse the registered growable array
2791     if (_array_for_gc != NULL) {
2792       for (int index = 0; index < _array_for_gc->length(); index++) {
2793         f->do_oop(_array_for_gc->adr_at(index));
2794       }
2795     }
2796 
2797     // Traverse the monitor chunks
2798     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2799       chunk->oops_do(f);
2800     }
2801 
2802     // Traverse the execution stack
2803     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2804       fst.current()->oops_do(f, cld_f, cf, fst.register_map());
2805     }
2806   }
2807 
2808   // callee_target is never live across a gc point so NULL it here should
2809   // it still contain a methdOop.
2810 
2811   set_callee_target(NULL);
2812 
2813   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2814   // If we have deferred set_locals there might be oops waiting to be
2815   // written
2816   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2817   if (list != NULL) {
2818     for (int i = 0; i < list->length(); i++) {
2819       list->at(i)->oops_do(f);
2820     }
2821   }
2822 
2823   // Traverse instance variables at the end since the GC may be moving things
2824   // around using this function
2825   f->do_oop((oop*) &_threadObj);
2826   f->do_oop((oop*) &_vm_result);
2827   f->do_oop((oop*) &_exception_oop);
2828   f->do_oop((oop*) &_pending_async_exception);
2829 
2830   if (jvmti_thread_state() != NULL) {
2831     jvmti_thread_state()->oops_do(f);
2832   }
2833 }
2834 
2835 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2836   Thread::nmethods_do(cf);  // (super method is a no-op)
2837 
2838   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2839          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2840 
2841   if (has_last_Java_frame()) {
2842     // Traverse the execution stack
2843     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2844       fst.current()->nmethods_do(cf);
2845     }
2846   }
2847 }
2848 
2849 void JavaThread::metadata_do(void f(Metadata*)) {
2850   if (has_last_Java_frame()) {
2851     // Traverse the execution stack to call f() on the methods in the stack
2852     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2853       fst.current()->metadata_do(f);
2854     }
2855   } else if (is_Compiler_thread()) {
2856     // need to walk ciMetadata in current compile tasks to keep alive.
2857     CompilerThread* ct = (CompilerThread*)this;
2858     if (ct->env() != NULL) {
2859       ct->env()->metadata_do(f);
2860     }
2861     if (ct->task() != NULL) {
2862       ct->task()->metadata_do(f);
2863     }
2864   }
2865 }
2866 
2867 // Printing
2868 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2869   switch (_thread_state) {
2870   case _thread_uninitialized:     return "_thread_uninitialized";
2871   case _thread_new:               return "_thread_new";
2872   case _thread_new_trans:         return "_thread_new_trans";
2873   case _thread_in_native:         return "_thread_in_native";
2874   case _thread_in_native_trans:   return "_thread_in_native_trans";
2875   case _thread_in_vm:             return "_thread_in_vm";
2876   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
2877   case _thread_in_Java:           return "_thread_in_Java";
2878   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
2879   case _thread_blocked:           return "_thread_blocked";
2880   case _thread_blocked_trans:     return "_thread_blocked_trans";
2881   default:                        return "unknown thread state";
2882   }
2883 }
2884 
2885 #ifndef PRODUCT
2886 void JavaThread::print_thread_state_on(outputStream *st) const {
2887   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
2888 };
2889 void JavaThread::print_thread_state() const {
2890   print_thread_state_on(tty);
2891 }
2892 #endif // PRODUCT
2893 
2894 // Called by Threads::print() for VM_PrintThreads operation
2895 void JavaThread::print_on(outputStream *st) const {
2896   st->print("\"%s\" ", get_thread_name());
2897   oop thread_oop = threadObj();
2898   if (thread_oop != NULL) {
2899     st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop));
2900     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
2901     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2902   }
2903   Thread::print_on(st);
2904   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2905   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2906   if (thread_oop != NULL) {
2907     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2908   }
2909 #ifndef PRODUCT
2910   print_thread_state_on(st);
2911   _safepoint_state->print_on(st);
2912 #endif // PRODUCT
2913   if (is_Compiler_thread()) {
2914     CompilerThread* ct = (CompilerThread*)this;
2915     if (ct->task() != NULL) {
2916       st->print("   Compiling: ");
2917       ct->task()->print(st, NULL, true, false);
2918     } else {
2919       st->print("   No compile task");
2920     }
2921     st->cr();
2922   }
2923 }
2924 
2925 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2926   st->print("%s", get_thread_name_string(buf, buflen));
2927 }
2928 
2929 // Called by fatal error handler. The difference between this and
2930 // JavaThread::print() is that we can't grab lock or allocate memory.
2931 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2932   st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2933   oop thread_obj = threadObj();
2934   if (thread_obj != NULL) {
2935     if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2936   }
2937   st->print(" [");
2938   st->print("%s", _get_thread_state_name(_thread_state));
2939   if (osthread()) {
2940     st->print(", id=%d", osthread()->thread_id());
2941   }
2942   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2943             p2i(stack_end()), p2i(stack_base()));
2944   st->print("]");
2945   return;
2946 }
2947 
2948 // Verification
2949 
2950 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2951 
2952 void JavaThread::verify() {
2953   // Verify oops in the thread.
2954   oops_do(&VerifyOopClosure::verify_oop, NULL, NULL);
2955 
2956   // Verify the stack frames.
2957   frames_do(frame_verify);
2958 }
2959 
2960 // CR 6300358 (sub-CR 2137150)
2961 // Most callers of this method assume that it can't return NULL but a
2962 // thread may not have a name whilst it is in the process of attaching to
2963 // the VM - see CR 6412693, and there are places where a JavaThread can be
2964 // seen prior to having it's threadObj set (eg JNI attaching threads and
2965 // if vm exit occurs during initialization). These cases can all be accounted
2966 // for such that this method never returns NULL.
2967 const char* JavaThread::get_thread_name() const {
2968 #ifdef ASSERT
2969   // early safepoints can hit while current thread does not yet have TLS
2970   if (!SafepointSynchronize::is_at_safepoint()) {
2971     Thread *cur = Thread::current();
2972     if (!(cur->is_Java_thread() && cur == this)) {
2973       // Current JavaThreads are allowed to get their own name without
2974       // the Threads_lock.
2975       assert_locked_or_safepoint(Threads_lock);
2976     }
2977   }
2978 #endif // ASSERT
2979   return get_thread_name_string();
2980 }
2981 
2982 // Returns a non-NULL representation of this thread's name, or a suitable
2983 // descriptive string if there is no set name
2984 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2985   const char* name_str;
2986   oop thread_obj = threadObj();
2987   if (thread_obj != NULL) {
2988     oop name = java_lang_Thread::name(thread_obj);
2989     if (name != NULL) {
2990       if (buf == NULL) {
2991         name_str = java_lang_String::as_utf8_string(name);
2992       } else {
2993         name_str = java_lang_String::as_utf8_string(name, buf, buflen);
2994       }
2995     } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
2996       name_str = "<no-name - thread is attaching>";
2997     } else {
2998       name_str = Thread::name();
2999     }
3000   } else {
3001     name_str = Thread::name();
3002   }
3003   assert(name_str != NULL, "unexpected NULL thread name");
3004   return name_str;
3005 }
3006 
3007 
3008 const char* JavaThread::get_threadgroup_name() const {
3009   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3010   oop thread_obj = threadObj();
3011   if (thread_obj != NULL) {
3012     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3013     if (thread_group != NULL) {
3014       // ThreadGroup.name can be null
3015       return java_lang_ThreadGroup::name(thread_group);
3016     }
3017   }
3018   return NULL;
3019 }
3020 
3021 const char* JavaThread::get_parent_name() const {
3022   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3023   oop thread_obj = threadObj();
3024   if (thread_obj != NULL) {
3025     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3026     if (thread_group != NULL) {
3027       oop parent = java_lang_ThreadGroup::parent(thread_group);
3028       if (parent != NULL) {
3029         // ThreadGroup.name can be null
3030         return java_lang_ThreadGroup::name(parent);
3031       }
3032     }
3033   }
3034   return NULL;
3035 }
3036 
3037 ThreadPriority JavaThread::java_priority() const {
3038   oop thr_oop = threadObj();
3039   if (thr_oop == NULL) return NormPriority; // Bootstrapping
3040   ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3041   assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3042   return priority;
3043 }
3044 
3045 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3046 
3047   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3048   // Link Java Thread object <-> C++ Thread
3049 
3050   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3051   // and put it into a new Handle.  The Handle "thread_oop" can then
3052   // be used to pass the C++ thread object to other methods.
3053 
3054   // Set the Java level thread object (jthread) field of the
3055   // new thread (a JavaThread *) to C++ thread object using the
3056   // "thread_oop" handle.
3057 
3058   // Set the thread field (a JavaThread *) of the
3059   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3060 
3061   Handle thread_oop(Thread::current(),
3062                     JNIHandles::resolve_non_null(jni_thread));
3063   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3064          "must be initialized");
3065   set_threadObj(thread_oop());
3066   java_lang_Thread::set_thread(thread_oop(), this);
3067 
3068   if (prio == NoPriority) {
3069     prio = java_lang_Thread::priority(thread_oop());
3070     assert(prio != NoPriority, "A valid priority should be present");
3071   }
3072 
3073   // Push the Java priority down to the native thread; needs Threads_lock
3074   Thread::set_priority(this, prio);
3075 
3076   prepare_ext();
3077 
3078   // Add the new thread to the Threads list and set it in motion.
3079   // We must have threads lock in order to call Threads::add.
3080   // It is crucial that we do not block before the thread is
3081   // added to the Threads list for if a GC happens, then the java_thread oop
3082   // will not be visited by GC.
3083   Threads::add(this);
3084 }
3085 
3086 oop JavaThread::current_park_blocker() {
3087   // Support for JSR-166 locks
3088   oop thread_oop = threadObj();
3089   if (thread_oop != NULL &&
3090       JDK_Version::current().supports_thread_park_blocker()) {
3091     return java_lang_Thread::park_blocker(thread_oop);
3092   }
3093   return NULL;
3094 }
3095 
3096 
3097 void JavaThread::print_stack_on(outputStream* st) {
3098   if (!has_last_Java_frame()) return;
3099   ResourceMark rm;
3100   HandleMark   hm;
3101 
3102   RegisterMap reg_map(this);
3103   vframe* start_vf = last_java_vframe(&reg_map);
3104   int count = 0;
3105   for (vframe* f = start_vf; f; f = f->sender()) {
3106     if (f->is_java_frame()) {
3107       javaVFrame* jvf = javaVFrame::cast(f);
3108       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3109 
3110       // Print out lock information
3111       if (JavaMonitorsInStackTrace) {
3112         jvf->print_lock_info_on(st, count);
3113       }
3114     } else {
3115       // Ignore non-Java frames
3116     }
3117 
3118     // Bail-out case for too deep stacks
3119     count++;
3120     if (MaxJavaStackTraceDepth == count) return;
3121   }
3122 }
3123 
3124 
3125 // JVMTI PopFrame support
3126 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3127   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3128   if (in_bytes(size_in_bytes) != 0) {
3129     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3130     _popframe_preserved_args_size = in_bytes(size_in_bytes);
3131     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3132   }
3133 }
3134 
3135 void* JavaThread::popframe_preserved_args() {
3136   return _popframe_preserved_args;
3137 }
3138 
3139 ByteSize JavaThread::popframe_preserved_args_size() {
3140   return in_ByteSize(_popframe_preserved_args_size);
3141 }
3142 
3143 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3144   int sz = in_bytes(popframe_preserved_args_size());
3145   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3146   return in_WordSize(sz / wordSize);
3147 }
3148 
3149 void JavaThread::popframe_free_preserved_args() {
3150   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3151   FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3152   _popframe_preserved_args = NULL;
3153   _popframe_preserved_args_size = 0;
3154 }
3155 
3156 #ifndef PRODUCT
3157 
3158 void JavaThread::trace_frames() {
3159   tty->print_cr("[Describe stack]");
3160   int frame_no = 1;
3161   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3162     tty->print("  %d. ", frame_no++);
3163     fst.current()->print_value_on(tty, this);
3164     tty->cr();
3165   }
3166 }
3167 
3168 class PrintAndVerifyOopClosure: public OopClosure {
3169  protected:
3170   template <class T> inline void do_oop_work(T* p) {
3171     oop obj = oopDesc::load_decode_heap_oop(p);
3172     if (obj == NULL) return;
3173     tty->print(INTPTR_FORMAT ": ", p2i(p));
3174     if (obj->is_oop_or_null()) {
3175       if (obj->is_objArray()) {
3176         tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3177       } else {
3178         obj->print();
3179       }
3180     } else {
3181       tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3182     }
3183     tty->cr();
3184   }
3185  public:
3186   virtual void do_oop(oop* p) { do_oop_work(p); }
3187   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
3188 };
3189 
3190 
3191 static void oops_print(frame* f, const RegisterMap *map) {
3192   PrintAndVerifyOopClosure print;
3193   f->print_value();
3194   f->oops_do(&print, NULL, NULL, (RegisterMap*)map);
3195 }
3196 
3197 // Print our all the locations that contain oops and whether they are
3198 // valid or not.  This useful when trying to find the oldest frame
3199 // where an oop has gone bad since the frame walk is from youngest to
3200 // oldest.
3201 void JavaThread::trace_oops() {
3202   tty->print_cr("[Trace oops]");
3203   frames_do(oops_print);
3204 }
3205 
3206 
3207 #ifdef ASSERT
3208 // Print or validate the layout of stack frames
3209 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3210   ResourceMark rm;
3211   PRESERVE_EXCEPTION_MARK;
3212   FrameValues values;
3213   int frame_no = 0;
3214   for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3215     fst.current()->describe(values, ++frame_no);
3216     if (depth == frame_no) break;
3217   }
3218   if (validate_only) {
3219     values.validate();
3220   } else {
3221     tty->print_cr("[Describe stack layout]");
3222     values.print(this);
3223   }
3224 }
3225 #endif
3226 
3227 void JavaThread::trace_stack_from(vframe* start_vf) {
3228   ResourceMark rm;
3229   int vframe_no = 1;
3230   for (vframe* f = start_vf; f; f = f->sender()) {
3231     if (f->is_java_frame()) {
3232       javaVFrame::cast(f)->print_activation(vframe_no++);
3233     } else {
3234       f->print();
3235     }
3236     if (vframe_no > StackPrintLimit) {
3237       tty->print_cr("...<more frames>...");
3238       return;
3239     }
3240   }
3241 }
3242 
3243 
3244 void JavaThread::trace_stack() {
3245   if (!has_last_Java_frame()) return;
3246   ResourceMark rm;
3247   HandleMark   hm;
3248   RegisterMap reg_map(this);
3249   trace_stack_from(last_java_vframe(&reg_map));
3250 }
3251 
3252 
3253 #endif // PRODUCT
3254 
3255 
3256 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3257   assert(reg_map != NULL, "a map must be given");
3258   frame f = last_frame();
3259   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3260     if (vf->is_java_frame()) return javaVFrame::cast(vf);
3261   }
3262   return NULL;
3263 }
3264 
3265 
3266 Klass* JavaThread::security_get_caller_class(int depth) {
3267   vframeStream vfst(this);
3268   vfst.security_get_caller_frame(depth);
3269   if (!vfst.at_end()) {
3270     return vfst.method()->method_holder();
3271   }
3272   return NULL;
3273 }
3274 
3275 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3276   assert(thread->is_Compiler_thread(), "must be compiler thread");
3277   CompileBroker::compiler_thread_loop();
3278 }
3279 
3280 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3281   NMethodSweeper::sweeper_loop();
3282 }
3283 
3284 // Create a CompilerThread
3285 CompilerThread::CompilerThread(CompileQueue* queue,
3286                                CompilerCounters* counters)
3287                                : JavaThread(&compiler_thread_entry) {
3288   _env   = NULL;
3289   _log   = NULL;
3290   _task  = NULL;
3291   _queue = queue;
3292   _counters = counters;
3293   _buffer_blob = NULL;
3294   _compiler = NULL;
3295 
3296 #ifndef PRODUCT
3297   _ideal_graph_printer = NULL;
3298 #endif
3299 }
3300 
3301 bool CompilerThread::can_call_java() const {
3302   return _compiler != NULL && _compiler->is_jvmci();
3303 }
3304 
3305 // Create sweeper thread
3306 CodeCacheSweeperThread::CodeCacheSweeperThread()
3307 : JavaThread(&sweeper_thread_entry) {
3308   _scanned_nmethod = NULL;
3309 }
3310 void CodeCacheSweeperThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
3311   JavaThread::oops_do(f, cld_f, cf);
3312   if (_scanned_nmethod != NULL && cf != NULL) {
3313     // Safepoints can occur when the sweeper is scanning an nmethod so
3314     // process it here to make sure it isn't unloaded in the middle of
3315     // a scan.
3316     cf->do_code_blob(_scanned_nmethod);
3317   }
3318 }
3319 
3320 
3321 // ======= Threads ========
3322 
3323 // The Threads class links together all active threads, and provides
3324 // operations over all threads.  It is protected by its own Mutex
3325 // lock, which is also used in other contexts to protect thread
3326 // operations from having the thread being operated on from exiting
3327 // and going away unexpectedly (e.g., safepoint synchronization)
3328 
3329 JavaThread* Threads::_thread_list = NULL;
3330 int         Threads::_number_of_threads = 0;
3331 int         Threads::_number_of_non_daemon_threads = 0;
3332 int         Threads::_return_code = 0;
3333 int         Threads::_thread_claim_parity = 0;
3334 size_t      JavaThread::_stack_size_at_create = 0;
3335 #ifdef ASSERT
3336 bool        Threads::_vm_complete = false;
3337 #endif
3338 
3339 // All JavaThreads
3340 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3341 
3342 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3343 void Threads::threads_do(ThreadClosure* tc) {
3344   assert_locked_or_safepoint(Threads_lock);
3345   // ALL_JAVA_THREADS iterates through all JavaThreads
3346   ALL_JAVA_THREADS(p) {
3347     tc->do_thread(p);
3348   }
3349   // Someday we could have a table or list of all non-JavaThreads.
3350   // For now, just manually iterate through them.
3351   tc->do_thread(VMThread::vm_thread());
3352   Universe::heap()->gc_threads_do(tc);
3353   WatcherThread *wt = WatcherThread::watcher_thread();
3354   // Strictly speaking, the following NULL check isn't sufficient to make sure
3355   // the data for WatcherThread is still valid upon being examined. However,
3356   // considering that WatchThread terminates when the VM is on the way to
3357   // exit at safepoint, the chance of the above is extremely small. The right
3358   // way to prevent termination of WatcherThread would be to acquire
3359   // Terminator_lock, but we can't do that without violating the lock rank
3360   // checking in some cases.
3361   if (wt != NULL) {
3362     tc->do_thread(wt);
3363   }
3364 
3365   // If CompilerThreads ever become non-JavaThreads, add them here
3366 }
3367 
3368 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3369   TraceStartupTime timer("Initialize java.lang classes");
3370 
3371   if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3372     create_vm_init_libraries();
3373   }
3374 
3375   initialize_class(vmSymbols::java_lang_String(), CHECK);
3376 
3377   // Inject CompactStrings value after the static initializers for String ran.
3378   java_lang_String::set_compact_strings(CompactStrings);
3379 
3380   // Initialize java_lang.System (needed before creating the thread)
3381   initialize_class(vmSymbols::java_lang_System(), CHECK);
3382   // The VM creates & returns objects of this class. Make sure it's initialized.
3383   initialize_class(vmSymbols::java_lang_Class(), CHECK);
3384   initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3385   Handle thread_group = create_initial_thread_group(CHECK);
3386   Universe::set_main_thread_group(thread_group());
3387   initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3388   oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3389   main_thread->set_threadObj(thread_object);
3390   // Set thread status to running since main thread has
3391   // been started and running.
3392   java_lang_Thread::set_thread_status(thread_object,
3393                                       java_lang_Thread::RUNNABLE);
3394 
3395   // The VM preresolves methods to these classes. Make sure that they get initialized
3396   initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3397   initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3398   call_initializeSystemClass(CHECK);
3399 
3400   // get the Java runtime name after java.lang.System is initialized
3401   JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3402   JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3403 
3404   // an instance of OutOfMemory exception has been allocated earlier
3405   initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3406   initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3407   initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3408   initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3409   initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3410   initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3411   initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3412   initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3413 }
3414 
3415 void Threads::initialize_jsr292_core_classes(TRAPS) {
3416   TraceStartupTime timer("Initialize java.lang.invoke classes");
3417 
3418   initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3419   initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3420   initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3421 }
3422 
3423 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3424   extern void JDK_Version_init();
3425 
3426   // Preinitialize version info.
3427   VM_Version::early_initialize();
3428 
3429   // Check version
3430   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3431 
3432   // Initialize library-based TLS
3433   ThreadLocalStorage::init();
3434 
3435   // Initialize the output stream module
3436   ostream_init();
3437 
3438   // Process java launcher properties.
3439   Arguments::process_sun_java_launcher_properties(args);
3440 
3441   // Initialize the os module
3442   os::init();
3443 
3444   // Record VM creation timing statistics
3445   TraceVmCreationTime create_vm_timer;
3446   create_vm_timer.start();
3447 
3448   // Initialize system properties.
3449   Arguments::init_system_properties();
3450 
3451   // So that JDK version can be used as a discriminator when parsing arguments
3452   JDK_Version_init();
3453 
3454   // Update/Initialize System properties after JDK version number is known
3455   Arguments::init_version_specific_system_properties();
3456 
3457   // Make sure to initialize log configuration *before* parsing arguments
3458   LogConfiguration::initialize(create_vm_timer.begin_time());
3459 
3460   // Parse arguments
3461   jint parse_result = Arguments::parse(args);
3462   if (parse_result != JNI_OK) return parse_result;
3463 
3464   os::init_before_ergo();
3465 
3466   jint ergo_result = Arguments::apply_ergo();
3467   if (ergo_result != JNI_OK) return ergo_result;
3468 
3469   // Final check of all ranges after ergonomics which may change values.
3470   if (!CommandLineFlagRangeList::check_ranges()) {
3471     return JNI_EINVAL;
3472   }
3473 
3474   // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3475   bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3476   if (!constraint_result) {
3477     return JNI_EINVAL;
3478   }
3479 
3480   if (PauseAtStartup) {
3481     os::pause();
3482   }
3483 
3484   HOTSPOT_VM_INIT_BEGIN();
3485 
3486   // Timing (must come after argument parsing)
3487   TraceStartupTime timer("Create VM");
3488 
3489   // Initialize the os module after parsing the args
3490   jint os_init_2_result = os::init_2();
3491   if (os_init_2_result != JNI_OK) return os_init_2_result;
3492 
3493   jint adjust_after_os_result = Arguments::adjust_after_os();
3494   if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3495 
3496   // Initialize output stream logging
3497   ostream_init_log();
3498 
3499   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3500   // Must be before create_vm_init_agents()
3501   if (Arguments::init_libraries_at_startup()) {
3502     convert_vm_init_libraries_to_agents();
3503   }
3504 
3505   // Launch -agentlib/-agentpath and converted -Xrun agents
3506   if (Arguments::init_agents_at_startup()) {
3507     create_vm_init_agents();
3508   }
3509 
3510   // Initialize Threads state
3511   _thread_list = NULL;
3512   _number_of_threads = 0;
3513   _number_of_non_daemon_threads = 0;
3514 
3515   // Initialize global data structures and create system classes in heap
3516   vm_init_globals();
3517 
3518 #if INCLUDE_JVMCI
3519   if (JVMCICounterSize > 0) {
3520     JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3521     memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3522   } else {
3523     JavaThread::_jvmci_old_thread_counters = NULL;
3524   }
3525 #endif // INCLUDE_JVMCI
3526 
3527   // Attach the main thread to this os thread
3528   JavaThread* main_thread = new JavaThread();
3529   main_thread->set_thread_state(_thread_in_vm);
3530   main_thread->initialize_thread_current();
3531   // must do this before set_active_handles
3532   main_thread->record_stack_base_and_size();
3533   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3534 
3535   if (!main_thread->set_as_starting_thread()) {
3536     vm_shutdown_during_initialization(
3537                                       "Failed necessary internal allocation. Out of swap space");
3538     delete main_thread;
3539     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3540     return JNI_ENOMEM;
3541   }
3542 
3543   // Enable guard page *after* os::create_main_thread(), otherwise it would
3544   // crash Linux VM, see notes in os_linux.cpp.
3545   main_thread->create_stack_guard_pages();
3546 
3547   // Initialize Java-Level synchronization subsystem
3548   ObjectMonitor::Initialize();
3549 
3550   // Initialize global modules
3551   jint status = init_globals();
3552   if (status != JNI_OK) {
3553     delete main_thread;
3554     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3555     return status;
3556   }
3557 
3558   if (TRACE_INITIALIZE() != JNI_OK) {
3559     vm_exit_during_initialization("Failed to initialize tracing backend");
3560   }
3561 
3562   // Should be done after the heap is fully created
3563   main_thread->cache_global_variables();
3564 
3565   HandleMark hm;
3566 
3567   { MutexLocker mu(Threads_lock);
3568     Threads::add(main_thread);
3569   }
3570 
3571   // Any JVMTI raw monitors entered in onload will transition into
3572   // real raw monitor. VM is setup enough here for raw monitor enter.
3573   JvmtiExport::transition_pending_onload_raw_monitors();
3574 
3575   // Create the VMThread
3576   { TraceStartupTime timer("Start VMThread");
3577 
3578   VMThread::create();
3579     Thread* vmthread = VMThread::vm_thread();
3580 
3581     if (!os::create_thread(vmthread, os::vm_thread)) {
3582       vm_exit_during_initialization("Cannot create VM thread. "
3583                                     "Out of system resources.");
3584     }
3585 
3586     // Wait for the VM thread to become ready, and VMThread::run to initialize
3587     // Monitors can have spurious returns, must always check another state flag
3588     {
3589       MutexLocker ml(Notify_lock);
3590       os::start_thread(vmthread);
3591       while (vmthread->active_handles() == NULL) {
3592         Notify_lock->wait();
3593       }
3594     }
3595   }
3596 
3597   assert(Universe::is_fully_initialized(), "not initialized");
3598   if (VerifyDuringStartup) {
3599     // Make sure we're starting with a clean slate.
3600     VM_Verify verify_op;
3601     VMThread::execute(&verify_op);
3602   }
3603 
3604   Thread* THREAD = Thread::current();
3605 
3606   // At this point, the Universe is initialized, but we have not executed
3607   // any byte code.  Now is a good time (the only time) to dump out the
3608   // internal state of the JVM for sharing.
3609   if (DumpSharedSpaces) {
3610     MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3611     ShouldNotReachHere();
3612   }
3613 
3614   // Always call even when there are not JVMTI environments yet, since environments
3615   // may be attached late and JVMTI must track phases of VM execution
3616   JvmtiExport::enter_start_phase();
3617 
3618   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3619   JvmtiExport::post_vm_start();
3620 
3621   initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3622 
3623   // We need this for ClassDataSharing - the initial vm.info property is set
3624   // with the default value of CDS "sharing" which may be reset through
3625   // command line options.
3626   reset_vm_info_property(CHECK_JNI_ERR);
3627 
3628   quicken_jni_functions();
3629 
3630   // No more stub generation allowed after that point.
3631   StubCodeDesc::freeze();
3632 
3633   // Set flag that basic initialization has completed. Used by exceptions and various
3634   // debug stuff, that does not work until all basic classes have been initialized.
3635   set_init_completed();
3636 
3637   LogConfiguration::post_initialize();
3638   Metaspace::post_initialize();
3639 
3640   HOTSPOT_VM_INIT_END();
3641 
3642   // record VM initialization completion time
3643 #if INCLUDE_MANAGEMENT
3644   Management::record_vm_init_completed();
3645 #endif // INCLUDE_MANAGEMENT
3646 
3647   // Compute system loader. Note that this has to occur after set_init_completed, since
3648   // valid exceptions may be thrown in the process.
3649   // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
3650   // set_init_completed has just been called, causing exceptions not to be shortcut
3651   // anymore. We call vm_exit_during_initialization directly instead.
3652   SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR));
3653 
3654 #if INCLUDE_ALL_GCS
3655   // Support for ConcurrentMarkSweep. This should be cleaned up
3656   // and better encapsulated. The ugly nested if test would go away
3657   // once things are properly refactored. XXX YSR
3658   if (UseConcMarkSweepGC || UseG1GC) {
3659     if (UseConcMarkSweepGC) {
3660       ConcurrentMarkSweepThread::makeSurrogateLockerThread(CHECK_JNI_ERR);
3661     } else {
3662       ConcurrentMarkThread::makeSurrogateLockerThread(CHECK_JNI_ERR);
3663     }
3664   }
3665 #endif // INCLUDE_ALL_GCS
3666 
3667   // Always call even when there are not JVMTI environments yet, since environments
3668   // may be attached late and JVMTI must track phases of VM execution
3669   JvmtiExport::enter_live_phase();
3670 
3671   // Signal Dispatcher needs to be started before VMInit event is posted
3672   os::signal_init();
3673 
3674   // Start Attach Listener if +StartAttachListener or it can't be started lazily
3675   if (!DisableAttachMechanism) {
3676     AttachListener::vm_start();
3677     if (StartAttachListener || AttachListener::init_at_startup()) {
3678       AttachListener::init();
3679     }
3680   }
3681 
3682   // Launch -Xrun agents
3683   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3684   // back-end can launch with -Xdebug -Xrunjdwp.
3685   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3686     create_vm_init_libraries();
3687   }
3688 
3689   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3690   JvmtiExport::post_vm_initialized();
3691 
3692   if (TRACE_START() != JNI_OK) {
3693     vm_exit_during_initialization("Failed to start tracing backend.");
3694   }
3695 
3696   if (CleanChunkPoolAsync) {
3697     Chunk::start_chunk_pool_cleaner_task();
3698   }
3699 
3700 #if INCLUDE_JVMCI
3701   if (EnableJVMCI) {
3702     const char* jvmciCompiler = Arguments::PropertyList_get_value(Arguments::system_properties(), "jvmci.compiler");
3703     if (jvmciCompiler != NULL) {
3704       JVMCIRuntime::save_compiler(jvmciCompiler);
3705     }
3706   }
3707 #endif // INCLUDE_JVMCI
3708 
3709   // initialize compiler(s)
3710 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI
3711   CompileBroker::compilation_init(CHECK_JNI_ERR);
3712 #endif
3713 
3714   // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3715   // It is done after compilers are initialized, because otherwise compilations of
3716   // signature polymorphic MH intrinsics can be missed
3717   // (see SystemDictionary::find_method_handle_intrinsic).
3718   initialize_jsr292_core_classes(CHECK_JNI_ERR);
3719 
3720 #if INCLUDE_MANAGEMENT
3721   Management::initialize(THREAD);
3722 
3723   if (HAS_PENDING_EXCEPTION) {
3724     // management agent fails to start possibly due to
3725     // configuration problem and is responsible for printing
3726     // stack trace if appropriate. Simply exit VM.
3727     vm_exit(1);
3728   }
3729 #endif // INCLUDE_MANAGEMENT
3730 
3731   if (Arguments::has_profile())       FlatProfiler::engage(main_thread, true);
3732   if (MemProfiling)                   MemProfiler::engage();
3733   StatSampler::engage();
3734   if (CheckJNICalls)                  JniPeriodicChecker::engage();
3735 
3736   BiasedLocking::init();
3737 
3738 #if INCLUDE_RTM_OPT
3739   RTMLockingCounters::init();
3740 #endif
3741 
3742   if (JDK_Version::current().post_vm_init_hook_enabled()) {
3743     call_postVMInitHook(THREAD);
3744     // The Java side of PostVMInitHook.run must deal with all
3745     // exceptions and provide means of diagnosis.
3746     if (HAS_PENDING_EXCEPTION) {
3747       CLEAR_PENDING_EXCEPTION;
3748     }
3749   }
3750 
3751   {
3752     MutexLocker ml(PeriodicTask_lock);
3753     // Make sure the WatcherThread can be started by WatcherThread::start()
3754     // or by dynamic enrollment.
3755     WatcherThread::make_startable();
3756     // Start up the WatcherThread if there are any periodic tasks
3757     // NOTE:  All PeriodicTasks should be registered by now. If they
3758     //   aren't, late joiners might appear to start slowly (we might
3759     //   take a while to process their first tick).
3760     if (PeriodicTask::num_tasks() > 0) {
3761       WatcherThread::start();
3762     }
3763   }
3764 
3765   CodeCacheExtensions::complete_step(CodeCacheExtensionsSteps::CreateVM);
3766 
3767   create_vm_timer.end();
3768 #ifdef ASSERT
3769   _vm_complete = true;
3770 #endif
3771   return JNI_OK;
3772 }
3773 
3774 // type for the Agent_OnLoad and JVM_OnLoad entry points
3775 extern "C" {
3776   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3777 }
3778 // Find a command line agent library and return its entry point for
3779 //         -agentlib:  -agentpath:   -Xrun
3780 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3781 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3782                                     const char *on_load_symbols[],
3783                                     size_t num_symbol_entries) {
3784   OnLoadEntry_t on_load_entry = NULL;
3785   void *library = NULL;
3786 
3787   if (!agent->valid()) {
3788     char buffer[JVM_MAXPATHLEN];
3789     char ebuf[1024] = "";
3790     const char *name = agent->name();
3791     const char *msg = "Could not find agent library ";
3792 
3793     // First check to see if agent is statically linked into executable
3794     if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3795       library = agent->os_lib();
3796     } else if (agent->is_absolute_path()) {
3797       library = os::dll_load(name, ebuf, sizeof ebuf);
3798       if (library == NULL) {
3799         const char *sub_msg = " in absolute path, with error: ";
3800         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3801         char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3802         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3803         // If we can't find the agent, exit.
3804         vm_exit_during_initialization(buf, NULL);
3805         FREE_C_HEAP_ARRAY(char, buf);
3806       }
3807     } else {
3808       // Try to load the agent from the standard dll directory
3809       if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3810                              name)) {
3811         library = os::dll_load(buffer, ebuf, sizeof ebuf);
3812       }
3813       if (library == NULL) { // Try the local directory
3814         char ns[1] = {0};
3815         if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3816           library = os::dll_load(buffer, ebuf, sizeof ebuf);
3817         }
3818         if (library == NULL) {
3819           const char *sub_msg = " on the library path, with error: ";
3820           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3821           char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3822           jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3823           // If we can't find the agent, exit.
3824           vm_exit_during_initialization(buf, NULL);
3825           FREE_C_HEAP_ARRAY(char, buf);
3826         }
3827       }
3828     }
3829     agent->set_os_lib(library);
3830     agent->set_valid();
3831   }
3832 
3833   // Find the OnLoad function.
3834   on_load_entry =
3835     CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3836                                                           false,
3837                                                           on_load_symbols,
3838                                                           num_symbol_entries));
3839   return on_load_entry;
3840 }
3841 
3842 // Find the JVM_OnLoad entry point
3843 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3844   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3845   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3846 }
3847 
3848 // Find the Agent_OnLoad entry point
3849 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3850   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3851   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3852 }
3853 
3854 // For backwards compatibility with -Xrun
3855 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3856 // treated like -agentpath:
3857 // Must be called before agent libraries are created
3858 void Threads::convert_vm_init_libraries_to_agents() {
3859   AgentLibrary* agent;
3860   AgentLibrary* next;
3861 
3862   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3863     next = agent->next();  // cache the next agent now as this agent may get moved off this list
3864     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3865 
3866     // If there is an JVM_OnLoad function it will get called later,
3867     // otherwise see if there is an Agent_OnLoad
3868     if (on_load_entry == NULL) {
3869       on_load_entry = lookup_agent_on_load(agent);
3870       if (on_load_entry != NULL) {
3871         // switch it to the agent list -- so that Agent_OnLoad will be called,
3872         // JVM_OnLoad won't be attempted and Agent_OnUnload will
3873         Arguments::convert_library_to_agent(agent);
3874       } else {
3875         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3876       }
3877     }
3878   }
3879 }
3880 
3881 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
3882 // Invokes Agent_OnLoad
3883 // Called very early -- before JavaThreads exist
3884 void Threads::create_vm_init_agents() {
3885   extern struct JavaVM_ main_vm;
3886   AgentLibrary* agent;
3887 
3888   JvmtiExport::enter_onload_phase();
3889 
3890   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3891     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
3892 
3893     if (on_load_entry != NULL) {
3894       // Invoke the Agent_OnLoad function
3895       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3896       if (err != JNI_OK) {
3897         vm_exit_during_initialization("agent library failed to init", agent->name());
3898       }
3899     } else {
3900       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3901     }
3902   }
3903   JvmtiExport::enter_primordial_phase();
3904 }
3905 
3906 extern "C" {
3907   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3908 }
3909 
3910 void Threads::shutdown_vm_agents() {
3911   // Send any Agent_OnUnload notifications
3912   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3913   size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
3914   extern struct JavaVM_ main_vm;
3915   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3916 
3917     // Find the Agent_OnUnload function.
3918     Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3919                                                    os::find_agent_function(agent,
3920                                                    false,
3921                                                    on_unload_symbols,
3922                                                    num_symbol_entries));
3923 
3924     // Invoke the Agent_OnUnload function
3925     if (unload_entry != NULL) {
3926       JavaThread* thread = JavaThread::current();
3927       ThreadToNativeFromVM ttn(thread);
3928       HandleMark hm(thread);
3929       (*unload_entry)(&main_vm);
3930     }
3931   }
3932 }
3933 
3934 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
3935 // Invokes JVM_OnLoad
3936 void Threads::create_vm_init_libraries() {
3937   extern struct JavaVM_ main_vm;
3938   AgentLibrary* agent;
3939 
3940   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
3941     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3942 
3943     if (on_load_entry != NULL) {
3944       // Invoke the JVM_OnLoad function
3945       JavaThread* thread = JavaThread::current();
3946       ThreadToNativeFromVM ttn(thread);
3947       HandleMark hm(thread);
3948       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3949       if (err != JNI_OK) {
3950         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
3951       }
3952     } else {
3953       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
3954     }
3955   }
3956 }
3957 
3958 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
3959   assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
3960 
3961   JavaThread* java_thread = NULL;
3962   // Sequential search for now.  Need to do better optimization later.
3963   for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
3964     oop tobj = thread->threadObj();
3965     if (!thread->is_exiting() &&
3966         tobj != NULL &&
3967         java_tid == java_lang_Thread::thread_id(tobj)) {
3968       java_thread = thread;
3969       break;
3970     }
3971   }
3972   return java_thread;
3973 }
3974 
3975 
3976 // Last thread running calls java.lang.Shutdown.shutdown()
3977 void JavaThread::invoke_shutdown_hooks() {
3978   HandleMark hm(this);
3979 
3980   // We could get here with a pending exception, if so clear it now.
3981   if (this->has_pending_exception()) {
3982     this->clear_pending_exception();
3983   }
3984 
3985   EXCEPTION_MARK;
3986   Klass* k =
3987     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
3988                                       THREAD);
3989   if (k != NULL) {
3990     // SystemDictionary::resolve_or_null will return null if there was
3991     // an exception.  If we cannot load the Shutdown class, just don't
3992     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
3993     // and finalizers (if runFinalizersOnExit is set) won't be run.
3994     // Note that if a shutdown hook was registered or runFinalizersOnExit
3995     // was called, the Shutdown class would have already been loaded
3996     // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
3997     instanceKlassHandle shutdown_klass (THREAD, k);
3998     JavaValue result(T_VOID);
3999     JavaCalls::call_static(&result,
4000                            shutdown_klass,
4001                            vmSymbols::shutdown_method_name(),
4002                            vmSymbols::void_method_signature(),
4003                            THREAD);
4004   }
4005   CLEAR_PENDING_EXCEPTION;
4006 }
4007 
4008 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4009 // the program falls off the end of main(). Another VM exit path is through
4010 // vm_exit() when the program calls System.exit() to return a value or when
4011 // there is a serious error in VM. The two shutdown paths are not exactly
4012 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4013 // and VM_Exit op at VM level.
4014 //
4015 // Shutdown sequence:
4016 //   + Shutdown native memory tracking if it is on
4017 //   + Wait until we are the last non-daemon thread to execute
4018 //     <-- every thing is still working at this moment -->
4019 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4020 //        shutdown hooks, run finalizers if finalization-on-exit
4021 //   + Call before_exit(), prepare for VM exit
4022 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4023 //        currently the only user of this mechanism is File.deleteOnExit())
4024 //      > stop flat profiler, StatSampler, watcher thread, CMS threads,
4025 //        post thread end and vm death events to JVMTI,
4026 //        stop signal thread
4027 //   + Call JavaThread::exit(), it will:
4028 //      > release JNI handle blocks, remove stack guard pages
4029 //      > remove this thread from Threads list
4030 //     <-- no more Java code from this thread after this point -->
4031 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4032 //     the compiler threads at safepoint
4033 //     <-- do not use anything that could get blocked by Safepoint -->
4034 //   + Disable tracing at JNI/JVM barriers
4035 //   + Set _vm_exited flag for threads that are still running native code
4036 //   + Delete this thread
4037 //   + Call exit_globals()
4038 //      > deletes tty
4039 //      > deletes PerfMemory resources
4040 //   + Return to caller
4041 
4042 bool Threads::destroy_vm() {
4043   JavaThread* thread = JavaThread::current();
4044 
4045 #ifdef ASSERT
4046   _vm_complete = false;
4047 #endif
4048   // Wait until we are the last non-daemon thread to execute
4049   { MutexLocker nu(Threads_lock);
4050     while (Threads::number_of_non_daemon_threads() > 1)
4051       // This wait should make safepoint checks, wait without a timeout,
4052       // and wait as a suspend-equivalent condition.
4053       //
4054       // Note: If the FlatProfiler is running and this thread is waiting
4055       // for another non-daemon thread to finish, then the FlatProfiler
4056       // is waiting for the external suspend request on this thread to
4057       // complete. wait_for_ext_suspend_completion() will eventually
4058       // timeout, but that takes time. Making this wait a suspend-
4059       // equivalent condition solves that timeout problem.
4060       //
4061       Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4062                          Mutex::_as_suspend_equivalent_flag);
4063   }
4064 
4065   // Hang forever on exit if we are reporting an error.
4066   if (ShowMessageBoxOnError && is_error_reported()) {
4067     os::infinite_sleep();
4068   }
4069   os::wait_for_keypress_at_exit();
4070 
4071   // run Java level shutdown hooks
4072   thread->invoke_shutdown_hooks();
4073 
4074   before_exit(thread);
4075 
4076   thread->exit(true);
4077 
4078   // Stop VM thread.
4079   {
4080     // 4945125 The vm thread comes to a safepoint during exit.
4081     // GC vm_operations can get caught at the safepoint, and the
4082     // heap is unparseable if they are caught. Grab the Heap_lock
4083     // to prevent this. The GC vm_operations will not be able to
4084     // queue until after the vm thread is dead. After this point,
4085     // we'll never emerge out of the safepoint before the VM exits.
4086 
4087     MutexLocker ml(Heap_lock);
4088 
4089     VMThread::wait_for_vm_thread_exit();
4090     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4091     VMThread::destroy();
4092   }
4093 
4094   // clean up ideal graph printers
4095 #if defined(COMPILER2) && !defined(PRODUCT)
4096   IdealGraphPrinter::clean_up();
4097 #endif
4098 
4099   // Now, all Java threads are gone except daemon threads. Daemon threads
4100   // running Java code or in VM are stopped by the Safepoint. However,
4101   // daemon threads executing native code are still running.  But they
4102   // will be stopped at native=>Java/VM barriers. Note that we can't
4103   // simply kill or suspend them, as it is inherently deadlock-prone.
4104 
4105   VM_Exit::set_vm_exited();
4106 
4107   notify_vm_shutdown();
4108 
4109   delete thread;
4110 
4111 #if INCLUDE_JVMCI
4112   if (JVMCICounterSize > 0) {
4113     FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4114   }
4115 #endif
4116 
4117   // exit_globals() will delete tty
4118   exit_globals();
4119 
4120   LogConfiguration::finalize();
4121 
4122   return true;
4123 }
4124 
4125 
4126 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4127   if (version == JNI_VERSION_1_1) return JNI_TRUE;
4128   return is_supported_jni_version(version);
4129 }
4130 
4131 
4132 jboolean Threads::is_supported_jni_version(jint version) {
4133   if (version == JNI_VERSION_1_2) return JNI_TRUE;
4134   if (version == JNI_VERSION_1_4) return JNI_TRUE;
4135   if (version == JNI_VERSION_1_6) return JNI_TRUE;
4136   if (version == JNI_VERSION_1_8) return JNI_TRUE;
4137   if (version == JNI_VERSION_9) return JNI_TRUE;
4138   return JNI_FALSE;
4139 }
4140 
4141 
4142 void Threads::add(JavaThread* p, bool force_daemon) {
4143   // The threads lock must be owned at this point
4144   assert_locked_or_safepoint(Threads_lock);
4145 
4146   // See the comment for this method in thread.hpp for its purpose and
4147   // why it is called here.
4148   p->initialize_queues();
4149   p->set_next(_thread_list);
4150   _thread_list = p;
4151   _number_of_threads++;
4152   oop threadObj = p->threadObj();
4153   bool daemon = true;
4154   // Bootstrapping problem: threadObj can be null for initial
4155   // JavaThread (or for threads attached via JNI)
4156   if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4157     _number_of_non_daemon_threads++;
4158     daemon = false;
4159   }
4160 
4161   ThreadService::add_thread(p, daemon);
4162 
4163   // Possible GC point.
4164   Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4165 }
4166 
4167 void Threads::remove(JavaThread* p) {
4168   // Extra scope needed for Thread_lock, so we can check
4169   // that we do not remove thread without safepoint code notice
4170   { MutexLocker ml(Threads_lock);
4171 
4172     assert(includes(p), "p must be present");
4173 
4174     JavaThread* current = _thread_list;
4175     JavaThread* prev    = NULL;
4176 
4177     while (current != p) {
4178       prev    = current;
4179       current = current->next();
4180     }
4181 
4182     if (prev) {
4183       prev->set_next(current->next());
4184     } else {
4185       _thread_list = p->next();
4186     }
4187     _number_of_threads--;
4188     oop threadObj = p->threadObj();
4189     bool daemon = true;
4190     if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4191       _number_of_non_daemon_threads--;
4192       daemon = false;
4193 
4194       // Only one thread left, do a notify on the Threads_lock so a thread waiting
4195       // on destroy_vm will wake up.
4196       if (number_of_non_daemon_threads() == 1) {
4197         Threads_lock->notify_all();
4198       }
4199     }
4200     ThreadService::remove_thread(p, daemon);
4201 
4202     // Make sure that safepoint code disregard this thread. This is needed since
4203     // the thread might mess around with locks after this point. This can cause it
4204     // to do callbacks into the safepoint code. However, the safepoint code is not aware
4205     // of this thread since it is removed from the queue.
4206     p->set_terminated_value();
4207   } // unlock Threads_lock
4208 
4209   // Since Events::log uses a lock, we grab it outside the Threads_lock
4210   Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4211 }
4212 
4213 // Threads_lock must be held when this is called (or must be called during a safepoint)
4214 bool Threads::includes(JavaThread* p) {
4215   assert(Threads_lock->is_locked(), "sanity check");
4216   ALL_JAVA_THREADS(q) {
4217     if (q == p) {
4218       return true;
4219     }
4220   }
4221   return false;
4222 }
4223 
4224 // Operations on the Threads list for GC.  These are not explicitly locked,
4225 // but the garbage collector must provide a safe context for them to run.
4226 // In particular, these things should never be called when the Threads_lock
4227 // is held by some other thread. (Note: the Safepoint abstraction also
4228 // uses the Threads_lock to guarantee this property. It also makes sure that
4229 // all threads gets blocked when exiting or starting).
4230 
4231 void Threads::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
4232   ALL_JAVA_THREADS(p) {
4233     p->oops_do(f, cld_f, cf);
4234   }
4235   VMThread::vm_thread()->oops_do(f, cld_f, cf);
4236 }
4237 
4238 void Threads::change_thread_claim_parity() {
4239   // Set the new claim parity.
4240   assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4241          "Not in range.");
4242   _thread_claim_parity++;
4243   if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4244   assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4245          "Not in range.");
4246 }
4247 
4248 #ifdef ASSERT
4249 void Threads::assert_all_threads_claimed() {
4250   ALL_JAVA_THREADS(p) {
4251     const int thread_parity = p->oops_do_parity();
4252     assert((thread_parity == _thread_claim_parity),
4253            "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4254   }
4255 }
4256 #endif // ASSERT
4257 
4258 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
4259   int cp = Threads::thread_claim_parity();
4260   ALL_JAVA_THREADS(p) {
4261     if (p->claim_oops_do(is_par, cp)) {
4262       p->oops_do(f, cld_f, cf);
4263     }
4264   }
4265   VMThread* vmt = VMThread::vm_thread();
4266   if (vmt->claim_oops_do(is_par, cp)) {
4267     vmt->oops_do(f, cld_f, cf);
4268   }
4269 }
4270 
4271 #if INCLUDE_ALL_GCS
4272 // Used by ParallelScavenge
4273 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4274   ALL_JAVA_THREADS(p) {
4275     q->enqueue(new ThreadRootsTask(p));
4276   }
4277   q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4278 }
4279 
4280 // Used by Parallel Old
4281 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4282   ALL_JAVA_THREADS(p) {
4283     q->enqueue(new ThreadRootsMarkingTask(p));
4284   }
4285   q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4286 }
4287 #endif // INCLUDE_ALL_GCS
4288 
4289 void Threads::nmethods_do(CodeBlobClosure* cf) {
4290   ALL_JAVA_THREADS(p) {
4291     p->nmethods_do(cf);
4292   }
4293   VMThread::vm_thread()->nmethods_do(cf);
4294 }
4295 
4296 void Threads::metadata_do(void f(Metadata*)) {
4297   ALL_JAVA_THREADS(p) {
4298     p->metadata_do(f);
4299   }
4300 }
4301 
4302 class ThreadHandlesClosure : public ThreadClosure {
4303   void (*_f)(Metadata*);
4304  public:
4305   ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4306   virtual void do_thread(Thread* thread) {
4307     thread->metadata_handles_do(_f);
4308   }
4309 };
4310 
4311 void Threads::metadata_handles_do(void f(Metadata*)) {
4312   // Only walk the Handles in Thread.
4313   ThreadHandlesClosure handles_closure(f);
4314   threads_do(&handles_closure);
4315 }
4316 
4317 void Threads::deoptimized_wrt_marked_nmethods() {
4318   ALL_JAVA_THREADS(p) {
4319     p->deoptimized_wrt_marked_nmethods();
4320   }
4321 }
4322 
4323 
4324 // Get count Java threads that are waiting to enter the specified monitor.
4325 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4326                                                          address monitor,
4327                                                          bool doLock) {
4328   assert(doLock || SafepointSynchronize::is_at_safepoint(),
4329          "must grab Threads_lock or be at safepoint");
4330   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4331 
4332   int i = 0;
4333   {
4334     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4335     ALL_JAVA_THREADS(p) {
4336       if (!p->can_call_java()) continue;
4337 
4338       address pending = (address)p->current_pending_monitor();
4339       if (pending == monitor) {             // found a match
4340         if (i < count) result->append(p);   // save the first count matches
4341         i++;
4342       }
4343     }
4344   }
4345   return result;
4346 }
4347 
4348 
4349 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4350                                                       bool doLock) {
4351   assert(doLock ||
4352          Threads_lock->owned_by_self() ||
4353          SafepointSynchronize::is_at_safepoint(),
4354          "must grab Threads_lock or be at safepoint");
4355 
4356   // NULL owner means not locked so we can skip the search
4357   if (owner == NULL) return NULL;
4358 
4359   {
4360     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4361     ALL_JAVA_THREADS(p) {
4362       // first, see if owner is the address of a Java thread
4363       if (owner == (address)p) return p;
4364     }
4365   }
4366   // Cannot assert on lack of success here since this function may be
4367   // used by code that is trying to report useful problem information
4368   // like deadlock detection.
4369   if (UseHeavyMonitors) return NULL;
4370 
4371   // If we didn't find a matching Java thread and we didn't force use of
4372   // heavyweight monitors, then the owner is the stack address of the
4373   // Lock Word in the owning Java thread's stack.
4374   //
4375   JavaThread* the_owner = NULL;
4376   {
4377     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4378     ALL_JAVA_THREADS(q) {
4379       if (q->is_lock_owned(owner)) {
4380         the_owner = q;
4381         break;
4382       }
4383     }
4384   }
4385   // cannot assert on lack of success here; see above comment
4386   return the_owner;
4387 }
4388 
4389 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4390 void Threads::print_on(outputStream* st, bool print_stacks,
4391                        bool internal_format, bool print_concurrent_locks) {
4392   char buf[32];
4393   st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4394 
4395   st->print_cr("Full thread dump %s (%s %s):",
4396                Abstract_VM_Version::vm_name(),
4397                Abstract_VM_Version::vm_release(),
4398                Abstract_VM_Version::vm_info_string());
4399   st->cr();
4400 
4401 #if INCLUDE_SERVICES
4402   // Dump concurrent locks
4403   ConcurrentLocksDump concurrent_locks;
4404   if (print_concurrent_locks) {
4405     concurrent_locks.dump_at_safepoint();
4406   }
4407 #endif // INCLUDE_SERVICES
4408 
4409   ALL_JAVA_THREADS(p) {
4410     ResourceMark rm;
4411     p->print_on(st);
4412     if (print_stacks) {
4413       if (internal_format) {
4414         p->trace_stack();
4415       } else {
4416         p->print_stack_on(st);
4417       }
4418     }
4419     st->cr();
4420 #if INCLUDE_SERVICES
4421     if (print_concurrent_locks) {
4422       concurrent_locks.print_locks_on(p, st);
4423     }
4424 #endif // INCLUDE_SERVICES
4425   }
4426 
4427   VMThread::vm_thread()->print_on(st);
4428   st->cr();
4429   Universe::heap()->print_gc_threads_on(st);
4430   WatcherThread* wt = WatcherThread::watcher_thread();
4431   if (wt != NULL) {
4432     wt->print_on(st);
4433     st->cr();
4434   }
4435   st->flush();
4436 }
4437 
4438 // Threads::print_on_error() is called by fatal error handler. It's possible
4439 // that VM is not at safepoint and/or current thread is inside signal handler.
4440 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4441 // memory (even in resource area), it might deadlock the error handler.
4442 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4443                              int buflen) {
4444   bool found_current = false;
4445   st->print_cr("Java Threads: ( => current thread )");
4446   ALL_JAVA_THREADS(thread) {
4447     bool is_current = (current == thread);
4448     found_current = found_current || is_current;
4449 
4450     st->print("%s", is_current ? "=>" : "  ");
4451 
4452     st->print(PTR_FORMAT, p2i(thread));
4453     st->print(" ");
4454     thread->print_on_error(st, buf, buflen);
4455     st->cr();
4456   }
4457   st->cr();
4458 
4459   st->print_cr("Other Threads:");
4460   if (VMThread::vm_thread()) {
4461     bool is_current = (current == VMThread::vm_thread());
4462     found_current = found_current || is_current;
4463     st->print("%s", current == VMThread::vm_thread() ? "=>" : "  ");
4464 
4465     st->print(PTR_FORMAT, p2i(VMThread::vm_thread()));
4466     st->print(" ");
4467     VMThread::vm_thread()->print_on_error(st, buf, buflen);
4468     st->cr();
4469   }
4470   WatcherThread* wt = WatcherThread::watcher_thread();
4471   if (wt != NULL) {
4472     bool is_current = (current == wt);
4473     found_current = found_current || is_current;
4474     st->print("%s", is_current ? "=>" : "  ");
4475 
4476     st->print(PTR_FORMAT, p2i(wt));
4477     st->print(" ");
4478     wt->print_on_error(st, buf, buflen);
4479     st->cr();
4480   }
4481   if (!found_current) {
4482     st->cr();
4483     st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4484     current->print_on_error(st, buf, buflen);
4485     st->cr();
4486   }
4487   st->cr();
4488   st->print_cr("Threads with active compile tasks:");
4489   print_threads_compiling(st, buf, buflen);
4490 }
4491 
4492 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4493   ALL_JAVA_THREADS(thread) {
4494     if (thread->is_Compiler_thread()) {
4495       CompilerThread* ct = (CompilerThread*) thread;
4496       if (ct->task() != NULL) {
4497         thread->print_name_on_error(st, buf, buflen);
4498         ct->task()->print(st, NULL, true, true);
4499       }
4500     }
4501   }
4502 }
4503 
4504 
4505 // Internal SpinLock and Mutex
4506 // Based on ParkEvent
4507 
4508 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4509 //
4510 // We employ SpinLocks _only for low-contention, fixed-length
4511 // short-duration critical sections where we're concerned
4512 // about native mutex_t or HotSpot Mutex:: latency.
4513 // The mux construct provides a spin-then-block mutual exclusion
4514 // mechanism.
4515 //
4516 // Testing has shown that contention on the ListLock guarding gFreeList
4517 // is common.  If we implement ListLock as a simple SpinLock it's common
4518 // for the JVM to devolve to yielding with little progress.  This is true
4519 // despite the fact that the critical sections protected by ListLock are
4520 // extremely short.
4521 //
4522 // TODO-FIXME: ListLock should be of type SpinLock.
4523 // We should make this a 1st-class type, integrated into the lock
4524 // hierarchy as leaf-locks.  Critically, the SpinLock structure
4525 // should have sufficient padding to avoid false-sharing and excessive
4526 // cache-coherency traffic.
4527 
4528 
4529 typedef volatile int SpinLockT;
4530 
4531 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4532   if (Atomic::cmpxchg (1, adr, 0) == 0) {
4533     return;   // normal fast-path return
4534   }
4535 
4536   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4537   TEVENT(SpinAcquire - ctx);
4538   int ctr = 0;
4539   int Yields = 0;
4540   for (;;) {
4541     while (*adr != 0) {
4542       ++ctr;
4543       if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4544         if (Yields > 5) {
4545           os::naked_short_sleep(1);
4546         } else {
4547           os::naked_yield();
4548           ++Yields;
4549         }
4550       } else {
4551         SpinPause();
4552       }
4553     }
4554     if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4555   }
4556 }
4557 
4558 void Thread::SpinRelease(volatile int * adr) {
4559   assert(*adr != 0, "invariant");
4560   OrderAccess::fence();      // guarantee at least release consistency.
4561   // Roach-motel semantics.
4562   // It's safe if subsequent LDs and STs float "up" into the critical section,
4563   // but prior LDs and STs within the critical section can't be allowed
4564   // to reorder or float past the ST that releases the lock.
4565   // Loads and stores in the critical section - which appear in program
4566   // order before the store that releases the lock - must also appear
4567   // before the store that releases the lock in memory visibility order.
4568   // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4569   // the ST of 0 into the lock-word which releases the lock, so fence
4570   // more than covers this on all platforms.
4571   *adr = 0;
4572 }
4573 
4574 // muxAcquire and muxRelease:
4575 //
4576 // *  muxAcquire and muxRelease support a single-word lock-word construct.
4577 //    The LSB of the word is set IFF the lock is held.
4578 //    The remainder of the word points to the head of a singly-linked list
4579 //    of threads blocked on the lock.
4580 //
4581 // *  The current implementation of muxAcquire-muxRelease uses its own
4582 //    dedicated Thread._MuxEvent instance.  If we're interested in
4583 //    minimizing the peak number of extant ParkEvent instances then
4584 //    we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4585 //    as certain invariants were satisfied.  Specifically, care would need
4586 //    to be taken with regards to consuming unpark() "permits".
4587 //    A safe rule of thumb is that a thread would never call muxAcquire()
4588 //    if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4589 //    park().  Otherwise the _ParkEvent park() operation in muxAcquire() could
4590 //    consume an unpark() permit intended for monitorenter, for instance.
4591 //    One way around this would be to widen the restricted-range semaphore
4592 //    implemented in park().  Another alternative would be to provide
4593 //    multiple instances of the PlatformEvent() for each thread.  One
4594 //    instance would be dedicated to muxAcquire-muxRelease, for instance.
4595 //
4596 // *  Usage:
4597 //    -- Only as leaf locks
4598 //    -- for short-term locking only as muxAcquire does not perform
4599 //       thread state transitions.
4600 //
4601 // Alternatives:
4602 // *  We could implement muxAcquire and muxRelease with MCS or CLH locks
4603 //    but with parking or spin-then-park instead of pure spinning.
4604 // *  Use Taura-Oyama-Yonenzawa locks.
4605 // *  It's possible to construct a 1-0 lock if we encode the lockword as
4606 //    (List,LockByte).  Acquire will CAS the full lockword while Release
4607 //    will STB 0 into the LockByte.  The 1-0 scheme admits stranding, so
4608 //    acquiring threads use timers (ParkTimed) to detect and recover from
4609 //    the stranding window.  Thread/Node structures must be aligned on 256-byte
4610 //    boundaries by using placement-new.
4611 // *  Augment MCS with advisory back-link fields maintained with CAS().
4612 //    Pictorially:  LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4613 //    The validity of the backlinks must be ratified before we trust the value.
4614 //    If the backlinks are invalid the exiting thread must back-track through the
4615 //    the forward links, which are always trustworthy.
4616 // *  Add a successor indication.  The LockWord is currently encoded as
4617 //    (List, LOCKBIT:1).  We could also add a SUCCBIT or an explicit _succ variable
4618 //    to provide the usual futile-wakeup optimization.
4619 //    See RTStt for details.
4620 // *  Consider schedctl.sc_nopreempt to cover the critical section.
4621 //
4622 
4623 
4624 typedef volatile intptr_t MutexT;      // Mux Lock-word
4625 enum MuxBits { LOCKBIT = 1 };
4626 
4627 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4628   intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4629   if (w == 0) return;
4630   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4631     return;
4632   }
4633 
4634   TEVENT(muxAcquire - Contention);
4635   ParkEvent * const Self = Thread::current()->_MuxEvent;
4636   assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4637   for (;;) {
4638     int its = (os::is_MP() ? 100 : 0) + 1;
4639 
4640     // Optional spin phase: spin-then-park strategy
4641     while (--its >= 0) {
4642       w = *Lock;
4643       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4644         return;
4645       }
4646     }
4647 
4648     Self->reset();
4649     Self->OnList = intptr_t(Lock);
4650     // The following fence() isn't _strictly necessary as the subsequent
4651     // CAS() both serializes execution and ratifies the fetched *Lock value.
4652     OrderAccess::fence();
4653     for (;;) {
4654       w = *Lock;
4655       if ((w & LOCKBIT) == 0) {
4656         if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4657           Self->OnList = 0;   // hygiene - allows stronger asserts
4658           return;
4659         }
4660         continue;      // Interference -- *Lock changed -- Just retry
4661       }
4662       assert(w & LOCKBIT, "invariant");
4663       Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4664       if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4665     }
4666 
4667     while (Self->OnList != 0) {
4668       Self->park();
4669     }
4670   }
4671 }
4672 
4673 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4674   intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4675   if (w == 0) return;
4676   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4677     return;
4678   }
4679 
4680   TEVENT(muxAcquire - Contention);
4681   ParkEvent * ReleaseAfter = NULL;
4682   if (ev == NULL) {
4683     ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4684   }
4685   assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4686   for (;;) {
4687     guarantee(ev->OnList == 0, "invariant");
4688     int its = (os::is_MP() ? 100 : 0) + 1;
4689 
4690     // Optional spin phase: spin-then-park strategy
4691     while (--its >= 0) {
4692       w = *Lock;
4693       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4694         if (ReleaseAfter != NULL) {
4695           ParkEvent::Release(ReleaseAfter);
4696         }
4697         return;
4698       }
4699     }
4700 
4701     ev->reset();
4702     ev->OnList = intptr_t(Lock);
4703     // The following fence() isn't _strictly necessary as the subsequent
4704     // CAS() both serializes execution and ratifies the fetched *Lock value.
4705     OrderAccess::fence();
4706     for (;;) {
4707       w = *Lock;
4708       if ((w & LOCKBIT) == 0) {
4709         if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4710           ev->OnList = 0;
4711           // We call ::Release while holding the outer lock, thus
4712           // artificially lengthening the critical section.
4713           // Consider deferring the ::Release() until the subsequent unlock(),
4714           // after we've dropped the outer lock.
4715           if (ReleaseAfter != NULL) {
4716             ParkEvent::Release(ReleaseAfter);
4717           }
4718           return;
4719         }
4720         continue;      // Interference -- *Lock changed -- Just retry
4721       }
4722       assert(w & LOCKBIT, "invariant");
4723       ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4724       if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4725     }
4726 
4727     while (ev->OnList != 0) {
4728       ev->park();
4729     }
4730   }
4731 }
4732 
4733 // Release() must extract a successor from the list and then wake that thread.
4734 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4735 // similar to that used by ParkEvent::Allocate() and ::Release().  DMR-based
4736 // Release() would :
4737 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4738 // (B) Extract a successor from the private list "in-hand"
4739 // (C) attempt to CAS() the residual back into *Lock over null.
4740 //     If there were any newly arrived threads and the CAS() would fail.
4741 //     In that case Release() would detach the RATs, re-merge the list in-hand
4742 //     with the RATs and repeat as needed.  Alternately, Release() might
4743 //     detach and extract a successor, but then pass the residual list to the wakee.
4744 //     The wakee would be responsible for reattaching and remerging before it
4745 //     competed for the lock.
4746 //
4747 // Both "pop" and DMR are immune from ABA corruption -- there can be
4748 // multiple concurrent pushers, but only one popper or detacher.
4749 // This implementation pops from the head of the list.  This is unfair,
4750 // but tends to provide excellent throughput as hot threads remain hot.
4751 // (We wake recently run threads first).
4752 //
4753 // All paths through muxRelease() will execute a CAS.
4754 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4755 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4756 // executed within the critical section are complete and globally visible before the
4757 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4758 void Thread::muxRelease(volatile intptr_t * Lock)  {
4759   for (;;) {
4760     const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4761     assert(w & LOCKBIT, "invariant");
4762     if (w == LOCKBIT) return;
4763     ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4764     assert(List != NULL, "invariant");
4765     assert(List->OnList == intptr_t(Lock), "invariant");
4766     ParkEvent * const nxt = List->ListNext;
4767     guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4768 
4769     // The following CAS() releases the lock and pops the head element.
4770     // The CAS() also ratifies the previously fetched lock-word value.
4771     if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4772       continue;
4773     }
4774     List->OnList = 0;
4775     OrderAccess::fence();
4776     List->unpark();
4777     return;
4778   }
4779 }
4780 
4781 
4782 void Threads::verify() {
4783   ALL_JAVA_THREADS(p) {
4784     p->verify();
4785   }
4786   VMThread* thread = VMThread::vm_thread();
4787   if (thread != NULL) thread->verify();
4788 }