1 /*
   2  * Copyright (c) 1997, 2014, 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/scopeDesc.hpp"
  31 #include "compiler/compileBroker.hpp"
  32 #include "interpreter/interpreter.hpp"
  33 #include "interpreter/linkResolver.hpp"
  34 #include "interpreter/oopMapCache.hpp"
  35 #include "jvmtifiles/jvmtiEnv.hpp"
  36 #include "memory/gcLocker.inline.hpp"
  37 #include "memory/metaspaceShared.hpp"
  38 #include "memory/oopFactory.hpp"
  39 #include "memory/universe.inline.hpp"
  40 #include "oops/instanceKlass.hpp"
  41 #include "oops/objArrayOop.hpp"
  42 #include "oops/oop.inline.hpp"
  43 #include "oops/symbol.hpp"
  44 #include "prims/jvm_misc.hpp"
  45 #include "prims/jvmtiExport.hpp"
  46 #include "prims/jvmtiThreadState.hpp"
  47 #include "prims/privilegedStack.hpp"
  48 #include "runtime/arguments.hpp"
  49 #include "runtime/biasedLocking.hpp"
  50 #include "runtime/deoptimization.hpp"
  51 #include "runtime/fprofiler.hpp"
  52 #include "runtime/frame.inline.hpp"
  53 #include "runtime/init.hpp"
  54 #include "runtime/interfaceSupport.hpp"
  55 #include "runtime/java.hpp"
  56 #include "runtime/javaCalls.hpp"
  57 #include "runtime/jniPeriodicChecker.hpp"
  58 #include "runtime/memprofiler.hpp"
  59 #include "runtime/mutexLocker.hpp"
  60 #include "runtime/objectMonitor.hpp"
  61 #include "runtime/osThread.hpp"
  62 #include "runtime/safepoint.hpp"
  63 #include "runtime/sharedRuntime.hpp"
  64 #include "runtime/statSampler.hpp"
  65 #include "runtime/stubRoutines.hpp"
  66 #include "runtime/task.hpp"
  67 #include "runtime/thread.inline.hpp"
  68 #include "runtime/threadCritical.hpp"
  69 #include "runtime/threadLocalStorage.hpp"
  70 #include "runtime/vframe.hpp"
  71 #include "runtime/vframeArray.hpp"
  72 #include "runtime/vframe_hp.hpp"
  73 #include "runtime/vmThread.hpp"
  74 #include "runtime/vm_operations.hpp"
  75 #include "services/attachListener.hpp"
  76 #include "services/management.hpp"
  77 #include "services/memTracker.hpp"
  78 #include "services/threadService.hpp"
  79 #include "trace/tracing.hpp"
  80 #include "trace/traceMacros.hpp"
  81 #include "utilities/defaultStream.hpp"
  82 #include "utilities/dtrace.hpp"
  83 #include "utilities/events.hpp"
  84 #include "utilities/preserveException.hpp"
  85 #include "utilities/macros.hpp"
  86 #ifdef TARGET_OS_FAMILY_linux
  87 # include "os_linux.inline.hpp"
  88 #endif
  89 #ifdef TARGET_OS_FAMILY_solaris
  90 # include "os_solaris.inline.hpp"
  91 #endif
  92 #ifdef TARGET_OS_FAMILY_windows
  93 # include "os_windows.inline.hpp"
  94 #endif
  95 #ifdef TARGET_OS_FAMILY_bsd
  96 # include "os_bsd.inline.hpp"
  97 #endif
  98 #if INCLUDE_ALL_GCS
  99 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
 100 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
 101 #include "gc_implementation/parallelScavenge/pcTasks.hpp"
 102 #endif // INCLUDE_ALL_GCS
 103 #ifdef COMPILER1
 104 #include "c1/c1_Compiler.hpp"
 105 #endif
 106 #ifdef COMPILER2
 107 #include "opto/c2compiler.hpp"
 108 #include "opto/idealGraphPrinter.hpp"
 109 #endif
 110 
 111 #ifdef DTRACE_ENABLED
 112 
 113 // Only bother with this argument setup if dtrace is available
 114 
 115 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
 116 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
 117 
 118 #define DTRACE_THREAD_PROBE(probe, javathread)                             \
 119   {                                                                        \
 120     ResourceMark rm(this);                                                 \
 121     int len = 0;                                                           \
 122     const char* name = (javathread)->get_thread_name();                    \
 123     len = strlen(name);                                                    \
 124     HOTSPOT_THREAD_PROBE_##probe(  /* probe = start, stop */               \
 125       (char *) name, len,                                                           \
 126       java_lang_Thread::thread_id((javathread)->threadObj()),              \
 127       (uintptr_t) (javathread)->osthread()->thread_id(),                               \
 128       java_lang_Thread::is_daemon((javathread)->threadObj()));             \
 129   }
 130 
 131 #else //  ndef DTRACE_ENABLED
 132 
 133 #define DTRACE_THREAD_PROBE(probe, javathread)
 134 
 135 #endif // ndef DTRACE_ENABLED
 136 
 137 
 138 // Class hierarchy
 139 // - Thread
 140 //   - VMThread
 141 //   - WatcherThread
 142 //   - ConcurrentMarkSweepThread
 143 //   - JavaThread
 144 //     - CompilerThread
 145 
 146 // ======= Thread ========
 147 // Support for forcing alignment of thread objects for biased locking
 148 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
 149   if (UseBiasedLocking) {
 150     const int alignment = markOopDesc::biased_lock_alignment;
 151     size_t aligned_size = size + (alignment - sizeof(intptr_t));
 152     void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
 153                                           : AllocateHeap(aligned_size, flags, CURRENT_PC,
 154                                               AllocFailStrategy::RETURN_NULL);
 155     void* aligned_addr     = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
 156     assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
 157            ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
 158            "JavaThread alignment code overflowed allocated storage");
 159     if (TraceBiasedLocking) {
 160       if (aligned_addr != real_malloc_addr)
 161         tty->print_cr("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
 162                       real_malloc_addr, aligned_addr);
 163     }
 164     ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
 165     return aligned_addr;
 166   } else {
 167     return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
 168                        : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
 169   }
 170 }
 171 
 172 void Thread::operator delete(void* p) {
 173   if (UseBiasedLocking) {
 174     void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
 175     FreeHeap(real_malloc_addr, mtThread);
 176   } else {
 177     FreeHeap(p, mtThread);
 178   }
 179 }
 180 
 181 
 182 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
 183 // JavaThread
 184 
 185 
 186 Thread::Thread() {
 187   // stack and get_thread
 188   set_stack_base(NULL);
 189   set_stack_size(0);
 190   set_self_raw_id(0);
 191   set_lgrp_id(-1);
 192 
 193   // allocated data structures
 194   set_osthread(NULL);
 195   set_resource_area(new (mtThread)ResourceArea());
 196   DEBUG_ONLY(_current_resource_mark = NULL;)
 197   set_handle_area(new (mtThread) HandleArea(NULL));
 198   set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
 199   set_active_handles(NULL);
 200   set_free_handle_block(NULL);
 201   set_last_handle_mark(NULL);
 202 
 203   // This initial value ==> never claimed.
 204   _oops_do_parity = 0;
 205 
 206   // the handle mark links itself to last_handle_mark
 207   new HandleMark(this);
 208 
 209   // plain initialization
 210   debug_only(_owned_locks = NULL;)
 211   debug_only(_allow_allocation_count = 0;)
 212   NOT_PRODUCT(_allow_safepoint_count = 0;)
 213   NOT_PRODUCT(_skip_gcalot = false;)
 214   CHECK_UNHANDLED_OOPS_ONLY(_gc_locked_out_count = 0;)
 215   _jvmti_env_iteration_count = 0;
 216   set_allocated_bytes(0);
 217   _vm_operation_started_count = 0;
 218   _vm_operation_completed_count = 0;
 219   _current_pending_monitor = NULL;
 220   _current_pending_monitor_is_from_java = true;
 221   _current_waiting_monitor = NULL;
 222   _num_nested_signal = 0;
 223   omFreeList = NULL ;
 224   omFreeCount = 0 ;
 225   omFreeProvision = 32 ;
 226   omInUseList = NULL ;
 227   omInUseCount = 0 ;
 228 
 229 #ifdef ASSERT
 230   _visited_for_critical_count = false;
 231 #endif
 232 
 233   _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true);
 234   _suspend_flags = 0;
 235 
 236   // thread-specific hashCode stream generator state - Marsaglia shift-xor form
 237   _hashStateX = os::random() ;
 238   _hashStateY = 842502087 ;
 239   _hashStateZ = 0x8767 ;    // (int)(3579807591LL & 0xffff) ;
 240   _hashStateW = 273326509 ;
 241 
 242   _OnTrap   = 0 ;
 243   _schedctl = NULL ;
 244   _Stalled  = 0 ;
 245   _TypeTag  = 0x2BAD ;
 246 
 247   // Many of the following fields are effectively final - immutable
 248   // Note that nascent threads can't use the Native Monitor-Mutex
 249   // construct until the _MutexEvent is initialized ...
 250   // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
 251   // we might instead use a stack of ParkEvents that we could provision on-demand.
 252   // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
 253   // and ::Release()
 254   _ParkEvent   = ParkEvent::Allocate (this) ;
 255   _SleepEvent  = ParkEvent::Allocate (this) ;
 256   _MutexEvent  = ParkEvent::Allocate (this) ;
 257   _MuxEvent    = ParkEvent::Allocate (this) ;
 258 
 259 #ifdef CHECK_UNHANDLED_OOPS
 260   if (CheckUnhandledOops) {
 261     _unhandled_oops = new UnhandledOops(this);
 262   }
 263 #endif // CHECK_UNHANDLED_OOPS
 264 #ifdef ASSERT
 265   if (UseBiasedLocking) {
 266     assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
 267     assert(this == _real_malloc_address ||
 268            this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
 269            "bug in forced alignment of thread objects");
 270   }
 271 #endif /* ASSERT */
 272 }
 273 
 274 void Thread::initialize_thread_local_storage() {
 275   // Note: Make sure this method only calls
 276   // non-blocking operations. Otherwise, it might not work
 277   // with the thread-startup/safepoint interaction.
 278 
 279   // During Java thread startup, safepoint code should allow this
 280   // method to complete because it may need to allocate memory to
 281   // store information for the new thread.
 282 
 283   // initialize structure dependent on thread local storage
 284   ThreadLocalStorage::set_thread(this);
 285 }
 286 
 287 void Thread::record_stack_base_and_size() {
 288   set_stack_base(os::current_stack_base());
 289   set_stack_size(os::current_stack_size());
 290   // CR 7190089: on Solaris, primordial thread's stack is adjusted
 291   // in initialize_thread(). Without the adjustment, stack size is
 292   // incorrect if stack is set to unlimited (ulimit -s unlimited).
 293   // So far, only Solaris has real implementation of initialize_thread().
 294   //
 295   // set up any platform-specific state.
 296   os::initialize_thread(this);
 297 
 298 #if INCLUDE_NMT
 299   // record thread's native stack, stack grows downward
 300   address stack_low_addr = stack_base() - stack_size();
 301   MemTracker::record_thread_stack(stack_low_addr, stack_size(), this,
 302       CURRENT_PC);
 303 #endif // INCLUDE_NMT
 304 }
 305 
 306 
 307 Thread::~Thread() {
 308   // Reclaim the objectmonitors from the omFreeList of the moribund thread.
 309   ObjectSynchronizer::omFlush (this) ;
 310 
 311   EVENT_THREAD_DESTRUCT(this);
 312 
 313   // stack_base can be NULL if the thread is never started or exited before
 314   // record_stack_base_and_size called. Although, we would like to ensure
 315   // that all started threads do call record_stack_base_and_size(), there is
 316   // not proper way to enforce that.
 317 #if INCLUDE_NMT
 318   if (_stack_base != NULL) {
 319     address low_stack_addr = stack_base() - stack_size();
 320     MemTracker::release_thread_stack(low_stack_addr, stack_size(), this);
 321 #ifdef ASSERT
 322     set_stack_base(NULL);
 323 #endif
 324   }
 325 #endif // INCLUDE_NMT
 326 
 327   // deallocate data structures
 328   delete resource_area();
 329   // since the handle marks are using the handle area, we have to deallocated the root
 330   // handle mark before deallocating the thread's handle area,
 331   assert(last_handle_mark() != NULL, "check we have an element");
 332   delete last_handle_mark();
 333   assert(last_handle_mark() == NULL, "check we have reached the end");
 334 
 335   // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
 336   // We NULL out the fields for good hygiene.
 337   ParkEvent::Release (_ParkEvent)   ; _ParkEvent   = NULL ;
 338   ParkEvent::Release (_SleepEvent)  ; _SleepEvent  = NULL ;
 339   ParkEvent::Release (_MutexEvent)  ; _MutexEvent  = NULL ;
 340   ParkEvent::Release (_MuxEvent)    ; _MuxEvent    = NULL ;
 341 
 342   delete handle_area();
 343   delete metadata_handles();
 344 
 345   // osthread() can be NULL, if creation of thread failed.
 346   if (osthread() != NULL) os::free_thread(osthread());
 347 
 348   delete _SR_lock;
 349 
 350   // clear thread local storage if the Thread is deleting itself
 351   if (this == Thread::current()) {
 352     ThreadLocalStorage::set_thread(NULL);
 353   } else {
 354     // In the case where we're not the current thread, invalidate all the
 355     // caches in case some code tries to get the current thread or the
 356     // thread that was destroyed, and gets stale information.
 357     ThreadLocalStorage::invalidate_all();
 358   }
 359   CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
 360 }
 361 
 362 // NOTE: dummy function for assertion purpose.
 363 void Thread::run() {
 364   ShouldNotReachHere();
 365 }
 366 
 367 #ifdef ASSERT
 368 // Private method to check for dangling thread pointer
 369 void check_for_dangling_thread_pointer(Thread *thread) {
 370  assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
 371          "possibility of dangling Thread pointer");
 372 }
 373 #endif
 374 
 375 
 376 #ifndef PRODUCT
 377 // Tracing method for basic thread operations
 378 void Thread::trace(const char* msg, const Thread* const thread) {
 379   if (!TraceThreadEvents) return;
 380   ResourceMark rm;
 381   ThreadCritical tc;
 382   const char *name = "non-Java thread";
 383   int prio = -1;
 384   if (thread->is_Java_thread()
 385       && !thread->is_Compiler_thread()) {
 386     // The Threads_lock must be held to get information about
 387     // this thread but may not be in some situations when
 388     // tracing  thread events.
 389     bool release_Threads_lock = false;
 390     if (!Threads_lock->owned_by_self()) {
 391       Threads_lock->lock();
 392       release_Threads_lock = true;
 393     }
 394     JavaThread* jt = (JavaThread *)thread;
 395     name = (char *)jt->get_thread_name();
 396     oop thread_oop = jt->threadObj();
 397     if (thread_oop != NULL) {
 398       prio = java_lang_Thread::priority(thread_oop);
 399     }
 400     if (release_Threads_lock) {
 401       Threads_lock->unlock();
 402     }
 403   }
 404   tty->print_cr("Thread::%s " INTPTR_FORMAT " [%lx] %s (prio: %d)", msg, thread, thread->osthread()->thread_id(), name, prio);
 405 }
 406 #endif
 407 
 408 
 409 ThreadPriority Thread::get_priority(const Thread* const thread) {
 410   trace("get priority", thread);
 411   ThreadPriority priority;
 412   // Can return an error!
 413   (void)os::get_priority(thread, priority);
 414   assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
 415   return priority;
 416 }
 417 
 418 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
 419   trace("set priority", thread);
 420   debug_only(check_for_dangling_thread_pointer(thread);)
 421   // Can return an error!
 422   (void)os::set_priority(thread, priority);
 423 }
 424 
 425 
 426 void Thread::start(Thread* thread) {
 427   trace("start", thread);
 428   // Start is different from resume in that its safety is guaranteed by context or
 429   // being called from a Java method synchronized on the Thread object.
 430   if (!DisableStartThread) {
 431     if (thread->is_Java_thread()) {
 432       // Initialize the thread state to RUNNABLE before starting this thread.
 433       // Can not set it after the thread started because we do not know the
 434       // exact thread state at that time. It could be in MONITOR_WAIT or
 435       // in SLEEPING or some other state.
 436       java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
 437                                           java_lang_Thread::RUNNABLE);
 438     }
 439     os::start_thread(thread);
 440   }
 441 }
 442 
 443 // Enqueue a VM_Operation to do the job for us - sometime later
 444 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
 445   VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
 446   VMThread::execute(vm_stop);
 447 }
 448 
 449 
 450 //
 451 // Check if an external suspend request has completed (or has been
 452 // cancelled). Returns true if the thread is externally suspended and
 453 // false otherwise.
 454 //
 455 // The bits parameter returns information about the code path through
 456 // the routine. Useful for debugging:
 457 //
 458 // set in is_ext_suspend_completed():
 459 // 0x00000001 - routine was entered
 460 // 0x00000010 - routine return false at end
 461 // 0x00000100 - thread exited (return false)
 462 // 0x00000200 - suspend request cancelled (return false)
 463 // 0x00000400 - thread suspended (return true)
 464 // 0x00001000 - thread is in a suspend equivalent state (return true)
 465 // 0x00002000 - thread is native and walkable (return true)
 466 // 0x00004000 - thread is native_trans and walkable (needed retry)
 467 //
 468 // set in wait_for_ext_suspend_completion():
 469 // 0x00010000 - routine was entered
 470 // 0x00020000 - suspend request cancelled before loop (return false)
 471 // 0x00040000 - thread suspended before loop (return true)
 472 // 0x00080000 - suspend request cancelled in loop (return false)
 473 // 0x00100000 - thread suspended in loop (return true)
 474 // 0x00200000 - suspend not completed during retry loop (return false)
 475 //
 476 
 477 // Helper class for tracing suspend wait debug bits.
 478 //
 479 // 0x00000100 indicates that the target thread exited before it could
 480 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
 481 // 0x00080000 each indicate a cancelled suspend request so they don't
 482 // count as wait failures either.
 483 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
 484 
 485 class TraceSuspendDebugBits : public StackObj {
 486  private:
 487   JavaThread * jt;
 488   bool         is_wait;
 489   bool         called_by_wait;  // meaningful when !is_wait
 490   uint32_t *   bits;
 491 
 492  public:
 493   TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
 494                         uint32_t *_bits) {
 495     jt             = _jt;
 496     is_wait        = _is_wait;
 497     called_by_wait = _called_by_wait;
 498     bits           = _bits;
 499   }
 500 
 501   ~TraceSuspendDebugBits() {
 502     if (!is_wait) {
 503 #if 1
 504       // By default, don't trace bits for is_ext_suspend_completed() calls.
 505       // That trace is very chatty.
 506       return;
 507 #else
 508       if (!called_by_wait) {
 509         // If tracing for is_ext_suspend_completed() is enabled, then only
 510         // trace calls to it from wait_for_ext_suspend_completion()
 511         return;
 512       }
 513 #endif
 514     }
 515 
 516     if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
 517       if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
 518         MutexLocker ml(Threads_lock);  // needed for get_thread_name()
 519         ResourceMark rm;
 520 
 521         tty->print_cr(
 522             "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
 523             jt->get_thread_name(), *bits);
 524 
 525         guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
 526       }
 527     }
 528   }
 529 };
 530 #undef DEBUG_FALSE_BITS
 531 
 532 
 533 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, uint32_t *bits) {
 534   TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
 535 
 536   bool did_trans_retry = false;  // only do thread_in_native_trans retry once
 537   bool do_trans_retry;           // flag to force the retry
 538 
 539   *bits |= 0x00000001;
 540 
 541   do {
 542     do_trans_retry = false;
 543 
 544     if (is_exiting()) {
 545       // Thread is in the process of exiting. This is always checked
 546       // first to reduce the risk of dereferencing a freed JavaThread.
 547       *bits |= 0x00000100;
 548       return false;
 549     }
 550 
 551     if (!is_external_suspend()) {
 552       // Suspend request is cancelled. This is always checked before
 553       // is_ext_suspended() to reduce the risk of a rogue resume
 554       // confusing the thread that made the suspend request.
 555       *bits |= 0x00000200;
 556       return false;
 557     }
 558 
 559     if (is_ext_suspended()) {
 560       // thread is suspended
 561       *bits |= 0x00000400;
 562       return true;
 563     }
 564 
 565     // Now that we no longer do hard suspends of threads running
 566     // native code, the target thread can be changing thread state
 567     // while we are in this routine:
 568     //
 569     //   _thread_in_native -> _thread_in_native_trans -> _thread_blocked
 570     //
 571     // We save a copy of the thread state as observed at this moment
 572     // and make our decision about suspend completeness based on the
 573     // copy. This closes the race where the thread state is seen as
 574     // _thread_in_native_trans in the if-thread_blocked check, but is
 575     // seen as _thread_blocked in if-thread_in_native_trans check.
 576     JavaThreadState save_state = thread_state();
 577 
 578     if (save_state == _thread_blocked && is_suspend_equivalent()) {
 579       // If the thread's state is _thread_blocked and this blocking
 580       // condition is known to be equivalent to a suspend, then we can
 581       // consider the thread to be externally suspended. This means that
 582       // the code that sets _thread_blocked has been modified to do
 583       // self-suspension if the blocking condition releases. We also
 584       // used to check for CONDVAR_WAIT here, but that is now covered by
 585       // the _thread_blocked with self-suspension check.
 586       //
 587       // Return true since we wouldn't be here unless there was still an
 588       // external suspend request.
 589       *bits |= 0x00001000;
 590       return true;
 591     } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
 592       // Threads running native code will self-suspend on native==>VM/Java
 593       // transitions. If its stack is walkable (should always be the case
 594       // unless this function is called before the actual java_suspend()
 595       // call), then the wait is done.
 596       *bits |= 0x00002000;
 597       return true;
 598     } else if (!called_by_wait && !did_trans_retry &&
 599                save_state == _thread_in_native_trans &&
 600                frame_anchor()->walkable()) {
 601       // The thread is transitioning from thread_in_native to another
 602       // thread state. check_safepoint_and_suspend_for_native_trans()
 603       // will force the thread to self-suspend. If it hasn't gotten
 604       // there yet we may have caught the thread in-between the native
 605       // code check above and the self-suspend. Lucky us. If we were
 606       // called by wait_for_ext_suspend_completion(), then it
 607       // will be doing the retries so we don't have to.
 608       //
 609       // Since we use the saved thread state in the if-statement above,
 610       // there is a chance that the thread has already transitioned to
 611       // _thread_blocked by the time we get here. In that case, we will
 612       // make a single unnecessary pass through the logic below. This
 613       // doesn't hurt anything since we still do the trans retry.
 614 
 615       *bits |= 0x00004000;
 616 
 617       // Once the thread leaves thread_in_native_trans for another
 618       // thread state, we break out of this retry loop. We shouldn't
 619       // need this flag to prevent us from getting back here, but
 620       // sometimes paranoia is good.
 621       did_trans_retry = true;
 622 
 623       // We wait for the thread to transition to a more usable state.
 624       for (int i = 1; i <= SuspendRetryCount; i++) {
 625         // We used to do an "os::yield_all(i)" call here with the intention
 626         // that yielding would increase on each retry. However, the parameter
 627         // is ignored on Linux which means the yield didn't scale up. Waiting
 628         // on the SR_lock below provides a much more predictable scale up for
 629         // the delay. It also provides a simple/direct point to check for any
 630         // safepoint requests from the VMThread
 631 
 632         // temporarily drops SR_lock while doing wait with safepoint check
 633         // (if we're a JavaThread - the WatcherThread can also call this)
 634         // and increase delay with each retry
 635         SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 636 
 637         // check the actual thread state instead of what we saved above
 638         if (thread_state() != _thread_in_native_trans) {
 639           // the thread has transitioned to another thread state so
 640           // try all the checks (except this one) one more time.
 641           do_trans_retry = true;
 642           break;
 643         }
 644       } // end retry loop
 645 
 646 
 647     }
 648   } while (do_trans_retry);
 649 
 650   *bits |= 0x00000010;
 651   return false;
 652 }
 653 
 654 //
 655 // Wait for an external suspend request to complete (or be cancelled).
 656 // Returns true if the thread is externally suspended and false otherwise.
 657 //
 658 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
 659        uint32_t *bits) {
 660   TraceSuspendDebugBits tsdb(this, true /* is_wait */,
 661                              false /* !called_by_wait */, bits);
 662 
 663   // local flag copies to minimize SR_lock hold time
 664   bool is_suspended;
 665   bool pending;
 666   uint32_t reset_bits;
 667 
 668   // set a marker so is_ext_suspend_completed() knows we are the caller
 669   *bits |= 0x00010000;
 670 
 671   // We use reset_bits to reinitialize the bits value at the top of
 672   // each retry loop. This allows the caller to make use of any
 673   // unused bits for their own marking purposes.
 674   reset_bits = *bits;
 675 
 676   {
 677     MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
 678     is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 679                                             delay, bits);
 680     pending = is_external_suspend();
 681   }
 682   // must release SR_lock to allow suspension to complete
 683 
 684   if (!pending) {
 685     // A cancelled suspend request is the only false return from
 686     // is_ext_suspend_completed() that keeps us from entering the
 687     // retry loop.
 688     *bits |= 0x00020000;
 689     return false;
 690   }
 691 
 692   if (is_suspended) {
 693     *bits |= 0x00040000;
 694     return true;
 695   }
 696 
 697   for (int i = 1; i <= retries; i++) {
 698     *bits = reset_bits;  // reinit to only track last retry
 699 
 700     // We used to do an "os::yield_all(i)" call here with the intention
 701     // that yielding would increase on each retry. However, the parameter
 702     // is ignored on Linux which means the yield didn't scale up. Waiting
 703     // on the SR_lock below provides a much more predictable scale up for
 704     // the delay. It also provides a simple/direct point to check for any
 705     // safepoint requests from the VMThread
 706 
 707     {
 708       MutexLocker ml(SR_lock());
 709       // wait with safepoint check (if we're a JavaThread - the WatcherThread
 710       // can also call this)  and increase delay with each retry
 711       SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 712 
 713       is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 714                                               delay, bits);
 715 
 716       // It is possible for the external suspend request to be cancelled
 717       // (by a resume) before the actual suspend operation is completed.
 718       // Refresh our local copy to see if we still need to wait.
 719       pending = is_external_suspend();
 720     }
 721 
 722     if (!pending) {
 723       // A cancelled suspend request is the only false return from
 724       // is_ext_suspend_completed() that keeps us from staying in the
 725       // retry loop.
 726       *bits |= 0x00080000;
 727       return false;
 728     }
 729 
 730     if (is_suspended) {
 731       *bits |= 0x00100000;
 732       return true;
 733     }
 734   } // end retry loop
 735 
 736   // thread did not suspend after all our retries
 737   *bits |= 0x00200000;
 738   return false;
 739 }
 740 
 741 #ifndef PRODUCT
 742 void JavaThread::record_jump(address target, address instr, const char* file, int line) {
 743 
 744   // This should not need to be atomic as the only way for simultaneous
 745   // updates is via interrupts. Even then this should be rare or non-existent
 746   // and we don't care that much anyway.
 747 
 748   int index = _jmp_ring_index;
 749   _jmp_ring_index = (index + 1 ) & (jump_ring_buffer_size - 1);
 750   _jmp_ring[index]._target = (intptr_t) target;
 751   _jmp_ring[index]._instruction = (intptr_t) instr;
 752   _jmp_ring[index]._file = file;
 753   _jmp_ring[index]._line = line;
 754 }
 755 #endif /* PRODUCT */
 756 
 757 // Called by flat profiler
 758 // Callers have already called wait_for_ext_suspend_completion
 759 // The assertion for that is currently too complex to put here:
 760 bool JavaThread::profile_last_Java_frame(frame* _fr) {
 761   bool gotframe = false;
 762   // self suspension saves needed state.
 763   if (has_last_Java_frame() && _anchor.walkable()) {
 764      *_fr = pd_last_frame();
 765      gotframe = true;
 766   }
 767   return gotframe;
 768 }
 769 
 770 void Thread::interrupt(Thread* thread) {
 771   trace("interrupt", thread);
 772   debug_only(check_for_dangling_thread_pointer(thread);)
 773   os::interrupt(thread);
 774 }
 775 
 776 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
 777   trace("is_interrupted", thread);
 778   debug_only(check_for_dangling_thread_pointer(thread);)
 779   // Note:  If clear_interrupted==false, this simply fetches and
 780   // returns the value of the field osthread()->interrupted().
 781   return os::is_interrupted(thread, clear_interrupted);
 782 }
 783 
 784 
 785 // GC Support
 786 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
 787   jint thread_parity = _oops_do_parity;
 788   if (thread_parity != strong_roots_parity) {
 789     jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
 790     if (res == thread_parity) {
 791       return true;
 792     } else {
 793       guarantee(res == strong_roots_parity, "Or else what?");
 794       assert(SharedHeap::heap()->workers()->active_workers() > 0,
 795          "Should only fail when parallel.");
 796       return false;
 797     }
 798   }
 799   assert(SharedHeap::heap()->workers()->active_workers() > 0,
 800          "Should only fail when parallel.");
 801   return false;
 802 }
 803 
 804 void Thread::oops_do(OopClosure* f, CLDToOopClosure* cld_f, CodeBlobClosure* cf) {
 805   active_handles()->oops_do(f);
 806   // Do oop for ThreadShadow
 807   f->do_oop((oop*)&_pending_exception);
 808   handle_area()->oops_do(f);
 809 }
 810 
 811 void Thread::nmethods_do(CodeBlobClosure* cf) {
 812   // no nmethods in a generic thread...
 813 }
 814 
 815 void Thread::metadata_do(void f(Metadata*)) {
 816   if (metadata_handles() != NULL) {
 817     for (int i = 0; i< metadata_handles()->length(); i++) {
 818       f(metadata_handles()->at(i));
 819     }
 820   }
 821 }
 822 
 823 void Thread::print_on(outputStream* st) const {
 824   // get_priority assumes osthread initialized
 825   if (osthread() != NULL) {
 826     int os_prio;
 827     if (os::get_native_priority(this, &os_prio) == OS_OK) {
 828       st->print("os_prio=%d ", os_prio);
 829     }
 830     st->print("tid=" INTPTR_FORMAT " ", this);
 831     osthread()->print_on(st);
 832   }
 833   debug_only(if (WizardMode) print_owned_locks_on(st);)
 834 }
 835 
 836 // Thread::print_on_error() is called by fatal error handler. Don't use
 837 // any lock or allocate memory.
 838 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
 839   if      (is_VM_thread())                  st->print("VMThread");
 840   else if (is_Compiler_thread())            st->print("CompilerThread");
 841   else if (is_Java_thread())                st->print("JavaThread");
 842   else if (is_GC_task_thread())             st->print("GCTaskThread");
 843   else if (is_Watcher_thread())             st->print("WatcherThread");
 844   else if (is_ConcurrentGC_thread())        st->print("ConcurrentGCThread");
 845   else st->print("Thread");
 846 
 847   st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
 848             _stack_base - _stack_size, _stack_base);
 849 
 850   if (osthread()) {
 851     st->print(" [id=%d]", osthread()->thread_id());
 852   }
 853 }
 854 
 855 #ifdef ASSERT
 856 void Thread::print_owned_locks_on(outputStream* st) const {
 857   Monitor *cur = _owned_locks;
 858   if (cur == NULL) {
 859     st->print(" (no locks) ");
 860   } else {
 861     st->print_cr(" Locks owned:");
 862     while(cur) {
 863       cur->print_on(st);
 864       cur = cur->next();
 865     }
 866   }
 867 }
 868 
 869 static int ref_use_count  = 0;
 870 
 871 bool Thread::owns_locks_but_compiled_lock() const {
 872   for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 873     if (cur != Compile_lock) return true;
 874   }
 875   return false;
 876 }
 877 
 878 
 879 #endif
 880 
 881 #ifndef PRODUCT
 882 
 883 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
 884 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
 885 // no threads which allow_vm_block's are held
 886 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
 887     // Check if current thread is allowed to block at a safepoint
 888     if (!(_allow_safepoint_count == 0))
 889       fatal("Possible safepoint reached by thread that does not allow it");
 890     if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
 891       fatal("LEAF method calling lock?");
 892     }
 893 
 894 #ifdef ASSERT
 895     if (potential_vm_operation && is_Java_thread()
 896         && !Universe::is_bootstrapping()) {
 897       // Make sure we do not hold any locks that the VM thread also uses.
 898       // This could potentially lead to deadlocks
 899       for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 900         // Threads_lock is special, since the safepoint synchronization will not start before this is
 901         // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
 902         // since it is used to transfer control between JavaThreads and the VMThread
 903         // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
 904         if ( (cur->allow_vm_block() &&
 905               cur != Threads_lock &&
 906               cur != Compile_lock &&               // Temporary: should not be necessary when we get separate compilation
 907               cur != VMOperationRequest_lock &&
 908               cur != VMOperationQueue_lock) ||
 909               cur->rank() == Mutex::special) {
 910           warning("Thread holding lock at safepoint that vm can block on: %s", cur->name());
 911         }
 912       }
 913     }
 914 
 915     if (GCALotAtAllSafepoints) {
 916       // We could enter a safepoint here and thus have a gc
 917       InterfaceSupport::check_gc_alot();
 918     }
 919 #endif
 920 }
 921 #endif
 922 
 923 bool Thread::is_in_stack(address adr) const {
 924   assert(Thread::current() == this, "is_in_stack can only be called from current thread");
 925   address end = os::current_stack_pointer();
 926   // Allow non Java threads to call this without stack_base
 927   if (_stack_base == NULL) return true;
 928   if (stack_base() >= adr && adr >= end) return true;
 929 
 930   return false;
 931 }
 932 
 933 
 934 bool Thread::is_in_usable_stack(address adr) const {
 935   size_t stack_guard_size = os::uses_stack_guard_pages() ? (StackYellowPages + StackRedPages) * os::vm_page_size() : 0;
 936   size_t usable_stack_size = _stack_size - stack_guard_size;
 937 
 938   return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
 939 }
 940 
 941 
 942 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
 943 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
 944 // used for compilation in the future. If that change is made, the need for these methods
 945 // should be revisited, and they should be removed if possible.
 946 
 947 bool Thread::is_lock_owned(address adr) const {
 948   return on_local_stack(adr);
 949 }
 950 
 951 bool Thread::set_as_starting_thread() {
 952  // NOTE: this must be called inside the main thread.
 953   return os::create_main_thread((JavaThread*)this);
 954 }
 955 
 956 static void initialize_class(Symbol* class_name, TRAPS) {
 957   Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
 958   InstanceKlass::cast(klass)->initialize(CHECK);
 959 }
 960 
 961 
 962 // Creates the initial ThreadGroup
 963 static Handle create_initial_thread_group(TRAPS) {
 964   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
 965   instanceKlassHandle klass (THREAD, k);
 966 
 967   Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
 968   {
 969     JavaValue result(T_VOID);
 970     JavaCalls::call_special(&result,
 971                             system_instance,
 972                             klass,
 973                             vmSymbols::object_initializer_name(),
 974                             vmSymbols::void_method_signature(),
 975                             CHECK_NH);
 976   }
 977   Universe::set_system_thread_group(system_instance());
 978 
 979   Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
 980   {
 981     JavaValue result(T_VOID);
 982     Handle string = java_lang_String::create_from_str("main", CHECK_NH);
 983     JavaCalls::call_special(&result,
 984                             main_instance,
 985                             klass,
 986                             vmSymbols::object_initializer_name(),
 987                             vmSymbols::threadgroup_string_void_signature(),
 988                             system_instance,
 989                             string,
 990                             CHECK_NH);
 991   }
 992   return main_instance;
 993 }
 994 
 995 // Creates the initial Thread
 996 static oop create_initial_thread(Handle thread_group, JavaThread* thread, TRAPS) {
 997   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
 998   instanceKlassHandle klass (THREAD, k);
 999   instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
1000 
1001   java_lang_Thread::set_thread(thread_oop(), thread);
1002   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1003   thread->set_threadObj(thread_oop());
1004 
1005   Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1006 
1007   JavaValue result(T_VOID);
1008   JavaCalls::call_special(&result, thread_oop,
1009                                    klass,
1010                                    vmSymbols::object_initializer_name(),
1011                                    vmSymbols::threadgroup_string_void_signature(),
1012                                    thread_group,
1013                                    string,
1014                                    CHECK_NULL);
1015   return thread_oop();
1016 }
1017 
1018 static void call_initializeSystemClass(TRAPS) {
1019   Klass* k =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1020   instanceKlassHandle klass (THREAD, k);
1021 
1022   JavaValue result(T_VOID);
1023   JavaCalls::call_static(&result, klass, vmSymbols::initializeSystemClass_name(),
1024                                          vmSymbols::void_method_signature(), CHECK);
1025 }
1026 
1027 char java_runtime_name[128] = "";
1028 char java_runtime_version[128] = "";
1029 
1030 // extract the JRE name from sun.misc.Version.java_runtime_name
1031 static const char* get_java_runtime_name(TRAPS) {
1032   Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(),
1033                                       Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1034   fieldDescriptor fd;
1035   bool found = k != NULL &&
1036                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1037                                                         vmSymbols::string_signature(), &fd);
1038   if (found) {
1039     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1040     if (name_oop == NULL)
1041       return NULL;
1042     const char* name = java_lang_String::as_utf8_string(name_oop,
1043                                                         java_runtime_name,
1044                                                         sizeof(java_runtime_name));
1045     return name;
1046   } else {
1047     return NULL;
1048   }
1049 }
1050 
1051 // extract the JRE version from sun.misc.Version.java_runtime_version
1052 static const char* get_java_runtime_version(TRAPS) {
1053   Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(),
1054                                       Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1055   fieldDescriptor fd;
1056   bool found = k != NULL &&
1057                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1058                                                         vmSymbols::string_signature(), &fd);
1059   if (found) {
1060     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1061     if (name_oop == NULL)
1062       return NULL;
1063     const char* name = java_lang_String::as_utf8_string(name_oop,
1064                                                         java_runtime_version,
1065                                                         sizeof(java_runtime_version));
1066     return name;
1067   } else {
1068     return NULL;
1069   }
1070 }
1071 
1072 // General purpose hook into Java code, run once when the VM is initialized.
1073 // The Java library method itself may be changed independently from the VM.
1074 static void call_postVMInitHook(TRAPS) {
1075   Klass* k = SystemDictionary::resolve_or_null(vmSymbols::sun_misc_PostVMInitHook(), THREAD);
1076   instanceKlassHandle klass (THREAD, k);
1077   if (klass.not_null()) {
1078     JavaValue result(T_VOID);
1079     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1080                                            vmSymbols::void_method_signature(),
1081                                            CHECK);
1082   }
1083 }
1084 
1085 static void reset_vm_info_property(TRAPS) {
1086   // the vm info string
1087   ResourceMark rm(THREAD);
1088   const char *vm_info = VM_Version::vm_info_string();
1089 
1090   // java.lang.System class
1091   Klass* k =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1092   instanceKlassHandle klass (THREAD, k);
1093 
1094   // setProperty arguments
1095   Handle key_str    = java_lang_String::create_from_str("java.vm.info", CHECK);
1096   Handle value_str  = java_lang_String::create_from_str(vm_info, CHECK);
1097 
1098   // return value
1099   JavaValue r(T_OBJECT);
1100 
1101   // public static String setProperty(String key, String value);
1102   JavaCalls::call_static(&r,
1103                          klass,
1104                          vmSymbols::setProperty_name(),
1105                          vmSymbols::string_string_string_signature(),
1106                          key_str,
1107                          value_str,
1108                          CHECK);
1109 }
1110 
1111 
1112 void JavaThread::allocate_threadObj(Handle thread_group, char* thread_name, bool daemon, TRAPS) {
1113   assert(thread_group.not_null(), "thread group should be specified");
1114   assert(threadObj() == NULL, "should only create Java thread object once");
1115 
1116   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1117   instanceKlassHandle klass (THREAD, k);
1118   instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1119 
1120   java_lang_Thread::set_thread(thread_oop(), this);
1121   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1122   set_threadObj(thread_oop());
1123 
1124   JavaValue result(T_VOID);
1125   if (thread_name != NULL) {
1126     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1127     // Thread gets assigned specified name and null target
1128     JavaCalls::call_special(&result,
1129                             thread_oop,
1130                             klass,
1131                             vmSymbols::object_initializer_name(),
1132                             vmSymbols::threadgroup_string_void_signature(),
1133                             thread_group, // Argument 1
1134                             name,         // Argument 2
1135                             THREAD);
1136   } else {
1137     // Thread gets assigned name "Thread-nnn" and null target
1138     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1139     JavaCalls::call_special(&result,
1140                             thread_oop,
1141                             klass,
1142                             vmSymbols::object_initializer_name(),
1143                             vmSymbols::threadgroup_runnable_void_signature(),
1144                             thread_group, // Argument 1
1145                             Handle(),     // Argument 2
1146                             THREAD);
1147   }
1148 
1149 
1150   if (daemon) {
1151       java_lang_Thread::set_daemon(thread_oop());
1152   }
1153 
1154   if (HAS_PENDING_EXCEPTION) {
1155     return;
1156   }
1157 
1158   KlassHandle group(this, SystemDictionary::ThreadGroup_klass());
1159   Handle threadObj(this, this->threadObj());
1160 
1161   JavaCalls::call_special(&result,
1162                          thread_group,
1163                          group,
1164                          vmSymbols::add_method_name(),
1165                          vmSymbols::thread_void_signature(),
1166                          threadObj,          // Arg 1
1167                          THREAD);
1168 
1169 
1170 }
1171 
1172 // NamedThread --  non-JavaThread subclasses with multiple
1173 // uniquely named instances should derive from this.
1174 NamedThread::NamedThread() : Thread() {
1175   _name = NULL;
1176   _processed_thread = NULL;
1177 }
1178 
1179 NamedThread::~NamedThread() {
1180   if (_name != NULL) {
1181     FREE_C_HEAP_ARRAY(char, _name, mtThread);
1182     _name = NULL;
1183   }
1184 }
1185 
1186 void NamedThread::set_name(const char* format, ...) {
1187   guarantee(_name == NULL, "Only get to set name once.");
1188   _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1189   guarantee(_name != NULL, "alloc failure");
1190   va_list ap;
1191   va_start(ap, format);
1192   jio_vsnprintf(_name, max_name_len, format, ap);
1193   va_end(ap);
1194 }
1195 
1196 // ======= WatcherThread ========
1197 
1198 // The watcher thread exists to simulate timer interrupts.  It should
1199 // be replaced by an abstraction over whatever native support for
1200 // timer interrupts exists on the platform.
1201 
1202 WatcherThread* WatcherThread::_watcher_thread   = NULL;
1203 bool WatcherThread::_startable = false;
1204 volatile bool  WatcherThread::_should_terminate = false;
1205 
1206 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) {
1207   assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1208   if (os::create_thread(this, os::watcher_thread)) {
1209     _watcher_thread = this;
1210 
1211     // Set the watcher thread to the highest OS priority which should not be
1212     // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1213     // is created. The only normal thread using this priority is the reference
1214     // handler thread, which runs for very short intervals only.
1215     // If the VMThread's priority is not lower than the WatcherThread profiling
1216     // will be inaccurate.
1217     os::set_priority(this, MaxPriority);
1218     if (!DisableStartThread) {
1219       os::start_thread(this);
1220     }
1221   }
1222 }
1223 
1224 int WatcherThread::sleep() const {
1225   MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1226 
1227   // remaining will be zero if there are no tasks,
1228   // causing the WatcherThread to sleep until a task is
1229   // enrolled
1230   int remaining = PeriodicTask::time_to_wait();
1231   int time_slept = 0;
1232 
1233   // we expect this to timeout - we only ever get unparked when
1234   // we should terminate or when a new task has been enrolled
1235   OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1236 
1237   jlong time_before_loop = os::javaTimeNanos();
1238 
1239   for (;;) {
1240     bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, remaining);
1241     jlong now = os::javaTimeNanos();
1242 
1243     if (remaining == 0) {
1244         // if we didn't have any tasks we could have waited for a long time
1245         // consider the time_slept zero and reset time_before_loop
1246         time_slept = 0;
1247         time_before_loop = now;
1248     } else {
1249         // need to recalculate since we might have new tasks in _tasks
1250         time_slept = (int) ((now - time_before_loop) / 1000000);
1251     }
1252 
1253     // Change to task list or spurious wakeup of some kind
1254     if (timedout || _should_terminate) {
1255         break;
1256     }
1257 
1258     remaining = PeriodicTask::time_to_wait();
1259     if (remaining == 0) {
1260         // Last task was just disenrolled so loop around and wait until
1261         // another task gets enrolled
1262         continue;
1263     }
1264 
1265     remaining -= time_slept;
1266     if (remaining <= 0)
1267       break;
1268   }
1269 
1270   return time_slept;
1271 }
1272 
1273 void WatcherThread::run() {
1274   assert(this == watcher_thread(), "just checking");
1275 
1276   this->record_stack_base_and_size();
1277   this->initialize_thread_local_storage();
1278   this->set_active_handles(JNIHandleBlock::allocate_block());
1279   while(!_should_terminate) {
1280     assert(watcher_thread() == Thread::current(),  "thread consistency check");
1281     assert(watcher_thread() == this,  "thread consistency check");
1282 
1283     // Calculate how long it'll be until the next PeriodicTask work
1284     // should be done, and sleep that amount of time.
1285     int time_waited = sleep();
1286 
1287     if (is_error_reported()) {
1288       // A fatal error has happened, the error handler(VMError::report_and_die)
1289       // should abort JVM after creating an error log file. However in some
1290       // rare cases, the error handler itself might deadlock. Here we try to
1291       // kill JVM if the fatal error handler fails to abort in 2 minutes.
1292       //
1293       // This code is in WatcherThread because WatcherThread wakes up
1294       // periodically so the fatal error handler doesn't need to do anything;
1295       // also because the WatcherThread is less likely to crash than other
1296       // threads.
1297 
1298       for (;;) {
1299         if (!ShowMessageBoxOnError
1300          && (OnError == NULL || OnError[0] == '\0')
1301          && Arguments::abort_hook() == NULL) {
1302              os::sleep(this, 2 * 60 * 1000, false);
1303              fdStream err(defaultStream::output_fd());
1304              err.print_raw_cr("# [ timer expired, abort... ]");
1305              // skip atexit/vm_exit/vm_abort hooks
1306              os::die();
1307         }
1308 
1309         // Wake up 5 seconds later, the fatal handler may reset OnError or
1310         // ShowMessageBoxOnError when it is ready to abort.
1311         os::sleep(this, 5 * 1000, false);
1312       }
1313     }
1314 
1315     PeriodicTask::real_time_tick(time_waited);
1316   }
1317 
1318   // Signal that it is terminated
1319   {
1320     MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1321     _watcher_thread = NULL;
1322     Terminator_lock->notify();
1323   }
1324 
1325   // Thread destructor usually does this..
1326   ThreadLocalStorage::set_thread(NULL);
1327 }
1328 
1329 void WatcherThread::start() {
1330   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1331 
1332   if (watcher_thread() == NULL && _startable) {
1333     _should_terminate = false;
1334     // Create the single instance of WatcherThread
1335     new WatcherThread();
1336   }
1337 }
1338 
1339 void WatcherThread::make_startable() {
1340   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1341   _startable = true;
1342 }
1343 
1344 void WatcherThread::stop() {
1345   {
1346     MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1347     _should_terminate = true;
1348     OrderAccess::fence();  // ensure WatcherThread sees update in main loop
1349 
1350     WatcherThread* watcher = watcher_thread();
1351     if (watcher != NULL)
1352       watcher->unpark();
1353   }
1354 
1355   // it is ok to take late safepoints here, if needed
1356   MutexLocker mu(Terminator_lock);
1357 
1358   while(watcher_thread() != NULL) {
1359     // This wait should make safepoint checks, wait without a timeout,
1360     // and wait as a suspend-equivalent condition.
1361     //
1362     // Note: If the FlatProfiler is running, then this thread is waiting
1363     // for the WatcherThread to terminate and the WatcherThread, via the
1364     // FlatProfiler task, is waiting for the external suspend request on
1365     // this thread to complete. wait_for_ext_suspend_completion() will
1366     // eventually timeout, but that takes time. Making this wait a
1367     // suspend-equivalent condition solves that timeout problem.
1368     //
1369     Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1370                           Mutex::_as_suspend_equivalent_flag);
1371   }
1372 }
1373 
1374 void WatcherThread::unpark() {
1375   MutexLockerEx ml(PeriodicTask_lock->owned_by_self() ? NULL : PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1376   PeriodicTask_lock->notify();
1377 }
1378 
1379 void WatcherThread::print_on(outputStream* st) const {
1380   st->print("\"%s\" ", name());
1381   Thread::print_on(st);
1382   st->cr();
1383 }
1384 
1385 // ======= JavaThread ========
1386 
1387 // A JavaThread is a normal Java thread
1388 
1389 void JavaThread::initialize() {
1390   // Initialize fields
1391 
1392   // Set the claimed par_id to -1 (ie not claiming any par_ids)
1393   set_claimed_par_id(-1);
1394 
1395   set_saved_exception_pc(NULL);
1396   set_threadObj(NULL);
1397   _anchor.clear();
1398   set_entry_point(NULL);
1399   set_jni_functions(jni_functions());
1400   set_callee_target(NULL);
1401   set_vm_result(NULL);
1402   set_vm_result_2(NULL);
1403   set_vframe_array_head(NULL);
1404   set_vframe_array_last(NULL);
1405   set_deferred_locals(NULL);
1406   set_deopt_mark(NULL);
1407   set_deopt_nmethod(NULL);
1408   clear_must_deopt_id();
1409   set_monitor_chunks(NULL);
1410   set_next(NULL);
1411   set_thread_state(_thread_new);
1412 #if INCLUDE_NMT
1413   set_recorder(NULL);
1414 #endif
1415   _terminated = _not_terminated;
1416   _privileged_stack_top = NULL;
1417   _array_for_gc = NULL;
1418   _suspend_equivalent = false;
1419   _in_deopt_handler = 0;
1420   _doing_unsafe_access = false;
1421   _stack_guard_state = stack_guard_unused;
1422   (void)const_cast<oop&>(_exception_oop = NULL);
1423   _exception_pc  = 0;
1424   _exception_handler_pc = 0;
1425   _is_method_handle_return = 0;
1426   _jvmti_thread_state= NULL;
1427   _should_post_on_exceptions_flag = JNI_FALSE;
1428   _jvmti_get_loaded_classes_closure = NULL;
1429   _interp_only_mode    = 0;
1430   _special_runtime_exit_condition = _no_async_condition;
1431   _pending_async_exception = NULL;
1432   _thread_stat = NULL;
1433   _thread_stat = new ThreadStatistics();
1434   _blocked_on_compilation = false;
1435   _jni_active_critical = 0;
1436   _do_not_unlock_if_synchronized = false;
1437   _cached_monitor_info = NULL;
1438   _parker = Parker::Allocate(this) ;
1439 
1440 #ifndef PRODUCT
1441   _jmp_ring_index = 0;
1442   for (int ji = 0 ; ji < jump_ring_buffer_size ; ji++ ) {
1443     record_jump(NULL, NULL, NULL, 0);
1444   }
1445 #endif /* PRODUCT */
1446 
1447   set_thread_profiler(NULL);
1448   if (FlatProfiler::is_active()) {
1449     // This is where we would decide to either give each thread it's own profiler
1450     // or use one global one from FlatProfiler,
1451     // or up to some count of the number of profiled threads, etc.
1452     ThreadProfiler* pp = new ThreadProfiler();
1453     pp->engage();
1454     set_thread_profiler(pp);
1455   }
1456 
1457   // Setup safepoint state info for this thread
1458   ThreadSafepointState::create(this);
1459 
1460   debug_only(_java_call_counter = 0);
1461 
1462   // JVMTI PopFrame support
1463   _popframe_condition = popframe_inactive;
1464   _popframe_preserved_args = NULL;
1465   _popframe_preserved_args_size = 0;
1466 
1467   pd_initialize();
1468 }
1469 
1470 #if INCLUDE_ALL_GCS
1471 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1472 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1473 #endif // INCLUDE_ALL_GCS
1474 
1475 JavaThread::JavaThread(bool is_attaching_via_jni) :
1476   Thread()
1477 #if INCLUDE_ALL_GCS
1478   , _satb_mark_queue(&_satb_mark_queue_set),
1479   _dirty_card_queue(&_dirty_card_queue_set)
1480 #endif // INCLUDE_ALL_GCS
1481 {
1482   initialize();
1483   if (is_attaching_via_jni) {
1484     _jni_attach_state = _attaching_via_jni;
1485   } else {
1486     _jni_attach_state = _not_attaching_via_jni;
1487   }
1488   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1489   _safepoint_visible = false;
1490 }
1491 
1492 bool JavaThread::reguard_stack(address cur_sp) {
1493   if (_stack_guard_state != stack_guard_yellow_disabled) {
1494     return true; // Stack already guarded or guard pages not needed.
1495   }
1496 
1497   if (register_stack_overflow()) {
1498     // For those architectures which have separate register and
1499     // memory stacks, we must check the register stack to see if
1500     // it has overflowed.
1501     return false;
1502   }
1503 
1504   // Java code never executes within the yellow zone: the latter is only
1505   // there to provoke an exception during stack banging.  If java code
1506   // is executing there, either StackShadowPages should be larger, or
1507   // some exception code in c1, c2 or the interpreter isn't unwinding
1508   // when it should.
1509   guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages");
1510 
1511   enable_stack_yellow_zone();
1512   return true;
1513 }
1514 
1515 bool JavaThread::reguard_stack(void) {
1516   return reguard_stack(os::current_stack_pointer());
1517 }
1518 
1519 
1520 void JavaThread::block_if_vm_exited() {
1521   if (_terminated == _vm_exited) {
1522     // _vm_exited is set at safepoint, and Threads_lock is never released
1523     // we will block here forever
1524     Threads_lock->lock_without_safepoint_check();
1525     ShouldNotReachHere();
1526   }
1527 }
1528 
1529 
1530 // Remove this ifdef when C1 is ported to the compiler interface.
1531 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1532 
1533 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1534   Thread()
1535 #if INCLUDE_ALL_GCS
1536   , _satb_mark_queue(&_satb_mark_queue_set),
1537   _dirty_card_queue(&_dirty_card_queue_set)
1538 #endif // INCLUDE_ALL_GCS
1539 {
1540   if (TraceThreadEvents) {
1541     tty->print_cr("creating thread %p", this);
1542   }
1543   initialize();
1544   _jni_attach_state = _not_attaching_via_jni;
1545   set_entry_point(entry_point);
1546   // Create the native thread itself.
1547   // %note runtime_23
1548   os::ThreadType thr_type = os::java_thread;
1549   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1550                                                      os::java_thread;
1551   os::create_thread(this, thr_type, stack_sz);
1552   _safepoint_visible = false;
1553   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1554   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1555   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1556   // the exception consists of creating the exception object & initializing it, initialization
1557   // will leave the VM via a JavaCall and then all locks must be unlocked).
1558   //
1559   // The thread is still suspended when we reach here. Thread must be explicit started
1560   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1561   // by calling Threads:add. The reason why this is not done here, is because the thread
1562   // object must be fully initialized (take a look at JVM_Start)
1563 }
1564 
1565 JavaThread::~JavaThread() {
1566   if (TraceThreadEvents) {
1567       tty->print_cr("terminate thread %p", this);
1568   }
1569 
1570   // By now, this thread should already be invisible to safepoint,
1571   // and its per-thread recorder also collected.
1572   assert(!is_safepoint_visible(), "wrong state");
1573 #if INCLUDE_NMT
1574   assert(get_recorder() == NULL, "Already collected");
1575 #endif // INCLUDE_NMT
1576 
1577   // JSR166 -- return the parker to the free list
1578   Parker::Release(_parker);
1579   _parker = NULL ;
1580 
1581   // Free any remaining  previous UnrollBlock
1582   vframeArray* old_array = vframe_array_last();
1583 
1584   if (old_array != NULL) {
1585     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1586     old_array->set_unroll_block(NULL);
1587     delete old_info;
1588     delete old_array;
1589   }
1590 
1591   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1592   if (deferred != NULL) {
1593     // This can only happen if thread is destroyed before deoptimization occurs.
1594     assert(deferred->length() != 0, "empty array!");
1595     do {
1596       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1597       deferred->remove_at(0);
1598       // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1599       delete dlv;
1600     } while (deferred->length() != 0);
1601     delete deferred;
1602   }
1603 
1604   // All Java related clean up happens in exit
1605   ThreadSafepointState::destroy(this);
1606   if (_thread_profiler != NULL) delete _thread_profiler;
1607   if (_thread_stat != NULL) delete _thread_stat;
1608 }
1609 
1610 
1611 // The first routine called by a new Java thread
1612 void JavaThread::run() {
1613   // initialize thread-local alloc buffer related fields
1614   this->initialize_tlab();
1615 
1616   // used to test validity of stack trace backs
1617   this->record_base_of_stack_pointer();
1618 
1619   // Record real stack base and size.
1620   this->record_stack_base_and_size();
1621 
1622   // Initialize thread local storage; set before calling MutexLocker
1623   this->initialize_thread_local_storage();
1624 
1625   this->create_stack_guard_pages();
1626 
1627   this->cache_global_variables();
1628 
1629   // Thread is now sufficient initialized to be handled by the safepoint code as being
1630   // in the VM. Change thread state from _thread_new to _thread_in_vm
1631   ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1632 
1633   assert(JavaThread::current() == this, "sanity check");
1634   assert(!Thread::current()->owns_locks(), "sanity check");
1635 
1636   DTRACE_THREAD_PROBE(start, this);
1637 
1638   // This operation might block. We call that after all safepoint checks for a new thread has
1639   // been completed.
1640   this->set_active_handles(JNIHandleBlock::allocate_block());
1641 
1642   if (JvmtiExport::should_post_thread_life()) {
1643     JvmtiExport::post_thread_start(this);
1644   }
1645 
1646   EventThreadStart event;
1647   if (event.should_commit()) {
1648      event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj()));
1649      event.commit();
1650   }
1651 
1652   // We call another function to do the rest so we are sure that the stack addresses used
1653   // from there will be lower than the stack base just computed
1654   thread_main_inner();
1655 
1656   // Note, thread is no longer valid at this point!
1657 }
1658 
1659 
1660 void JavaThread::thread_main_inner() {
1661   assert(JavaThread::current() == this, "sanity check");
1662   assert(this->threadObj() != NULL, "just checking");
1663 
1664   // Execute thread entry point unless this thread has a pending exception
1665   // or has been stopped before starting.
1666   // Note: Due to JVM_StopThread we can have pending exceptions already!
1667   if (!this->has_pending_exception() &&
1668       !java_lang_Thread::is_stillborn(this->threadObj())) {
1669     {
1670       ResourceMark rm(this);
1671       this->set_native_thread_name(this->get_thread_name());
1672     }
1673     HandleMark hm(this);
1674     this->entry_point()(this, this);
1675   }
1676 
1677   DTRACE_THREAD_PROBE(stop, this);
1678 
1679   this->exit(false);
1680   delete this;
1681 }
1682 
1683 
1684 static void ensure_join(JavaThread* thread) {
1685   // We do not need to grap the Threads_lock, since we are operating on ourself.
1686   Handle threadObj(thread, thread->threadObj());
1687   assert(threadObj.not_null(), "java thread object must exist");
1688   ObjectLocker lock(threadObj, thread);
1689   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1690   thread->clear_pending_exception();
1691   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1692   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1693   // Clear the native thread instance - this makes isAlive return false and allows the join()
1694   // to complete once we've done the notify_all below
1695   java_lang_Thread::set_thread(threadObj(), NULL);
1696   lock.notify_all(thread);
1697   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1698   thread->clear_pending_exception();
1699 }
1700 
1701 
1702 // For any new cleanup additions, please check to see if they need to be applied to
1703 // cleanup_failed_attach_current_thread as well.
1704 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1705   assert(this == JavaThread::current(),  "thread consistency check");
1706 
1707   HandleMark hm(this);
1708   Handle uncaught_exception(this, this->pending_exception());
1709   this->clear_pending_exception();
1710   Handle threadObj(this, this->threadObj());
1711   assert(threadObj.not_null(), "Java thread object should be created");
1712 
1713   if (get_thread_profiler() != NULL) {
1714     get_thread_profiler()->disengage();
1715     ResourceMark rm;
1716     get_thread_profiler()->print(get_thread_name());
1717   }
1718 
1719 
1720   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1721   {
1722     EXCEPTION_MARK;
1723 
1724     CLEAR_PENDING_EXCEPTION;
1725   }
1726   // FIXIT: The is_null check is only so it works better on JDK1.2 VM's. This
1727   // has to be fixed by a runtime query method
1728   if (!destroy_vm || JDK_Version::is_jdk12x_version()) {
1729     // JSR-166: change call from from ThreadGroup.uncaughtException to
1730     // java.lang.Thread.dispatchUncaughtException
1731     if (uncaught_exception.not_null()) {
1732       Handle group(this, java_lang_Thread::threadGroup(threadObj()));
1733       {
1734         EXCEPTION_MARK;
1735         // Check if the method Thread.dispatchUncaughtException() exists. If so
1736         // call it.  Otherwise we have an older library without the JSR-166 changes,
1737         // so call ThreadGroup.uncaughtException()
1738         KlassHandle recvrKlass(THREAD, threadObj->klass());
1739         CallInfo callinfo;
1740         KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1741         LinkResolver::resolve_virtual_call(callinfo, threadObj, recvrKlass, thread_klass,
1742                                            vmSymbols::dispatchUncaughtException_name(),
1743                                            vmSymbols::throwable_void_signature(),
1744                                            KlassHandle(), false, false, THREAD);
1745         CLEAR_PENDING_EXCEPTION;
1746         methodHandle method = callinfo.selected_method();
1747         if (method.not_null()) {
1748           JavaValue result(T_VOID);
1749           JavaCalls::call_virtual(&result,
1750                                   threadObj, thread_klass,
1751                                   vmSymbols::dispatchUncaughtException_name(),
1752                                   vmSymbols::throwable_void_signature(),
1753                                   uncaught_exception,
1754                                   THREAD);
1755         } else {
1756           KlassHandle thread_group(THREAD, SystemDictionary::ThreadGroup_klass());
1757           JavaValue result(T_VOID);
1758           JavaCalls::call_virtual(&result,
1759                                   group, thread_group,
1760                                   vmSymbols::uncaughtException_name(),
1761                                   vmSymbols::thread_throwable_void_signature(),
1762                                   threadObj,           // Arg 1
1763                                   uncaught_exception,  // Arg 2
1764                                   THREAD);
1765         }
1766         if (HAS_PENDING_EXCEPTION) {
1767           ResourceMark rm(this);
1768           jio_fprintf(defaultStream::error_stream(),
1769                 "\nException: %s thrown from the UncaughtExceptionHandler"
1770                 " in thread \"%s\"\n",
1771                 pending_exception()->klass()->external_name(),
1772                 get_thread_name());
1773           CLEAR_PENDING_EXCEPTION;
1774         }
1775       }
1776     }
1777 
1778     // Called before the java thread exit since we want to read info
1779     // from java_lang_Thread object
1780     EventThreadEnd event;
1781     if (event.should_commit()) {
1782         event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj()));
1783         event.commit();
1784     }
1785 
1786     // Call after last event on thread
1787     EVENT_THREAD_EXIT(this);
1788 
1789     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1790     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1791     // is deprecated anyhow.
1792     if (!is_Compiler_thread()) {
1793       int count = 3;
1794       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1795         EXCEPTION_MARK;
1796         JavaValue result(T_VOID);
1797         KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1798         JavaCalls::call_virtual(&result,
1799                               threadObj, thread_klass,
1800                               vmSymbols::exit_method_name(),
1801                               vmSymbols::void_method_signature(),
1802                               THREAD);
1803         CLEAR_PENDING_EXCEPTION;
1804       }
1805     }
1806     // notify JVMTI
1807     if (JvmtiExport::should_post_thread_life()) {
1808       JvmtiExport::post_thread_end(this);
1809     }
1810 
1811     // We have notified the agents that we are exiting, before we go on,
1812     // we must check for a pending external suspend request and honor it
1813     // in order to not surprise the thread that made the suspend request.
1814     while (true) {
1815       {
1816         MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1817         if (!is_external_suspend()) {
1818           set_terminated(_thread_exiting);
1819           ThreadService::current_thread_exiting(this);
1820           break;
1821         }
1822         // Implied else:
1823         // Things get a little tricky here. We have a pending external
1824         // suspend request, but we are holding the SR_lock so we
1825         // can't just self-suspend. So we temporarily drop the lock
1826         // and then self-suspend.
1827       }
1828 
1829       ThreadBlockInVM tbivm(this);
1830       java_suspend_self();
1831 
1832       // We're done with this suspend request, but we have to loop around
1833       // and check again. Eventually we will get SR_lock without a pending
1834       // external suspend request and will be able to mark ourselves as
1835       // exiting.
1836     }
1837     // no more external suspends are allowed at this point
1838   } else {
1839     // before_exit() has already posted JVMTI THREAD_END events
1840   }
1841 
1842   // Notify waiters on thread object. This has to be done after exit() is called
1843   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1844   // group should have the destroyed bit set before waiters are notified).
1845   ensure_join(this);
1846   assert(!this->has_pending_exception(), "ensure_join should have cleared");
1847 
1848   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1849   // held by this thread must be released.  A detach operation must only
1850   // get here if there are no Java frames on the stack.  Therefore, any
1851   // owned monitors at this point MUST be JNI-acquired monitors which are
1852   // pre-inflated and in the monitor cache.
1853   //
1854   // ensure_join() ignores IllegalThreadStateExceptions, and so does this.
1855   if (exit_type == jni_detach && JNIDetachReleasesMonitors) {
1856     assert(!this->has_last_Java_frame(), "detaching with Java frames?");
1857     ObjectSynchronizer::release_monitors_owned_by_thread(this);
1858     assert(!this->has_pending_exception(), "release_monitors should have cleared");
1859   }
1860 
1861   // These things needs to be done while we are still a Java Thread. Make sure that thread
1862   // is in a consistent state, in case GC happens
1863   assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1864 
1865   if (active_handles() != NULL) {
1866     JNIHandleBlock* block = active_handles();
1867     set_active_handles(NULL);
1868     JNIHandleBlock::release_block(block);
1869   }
1870 
1871   if (free_handle_block() != NULL) {
1872     JNIHandleBlock* block = free_handle_block();
1873     set_free_handle_block(NULL);
1874     JNIHandleBlock::release_block(block);
1875   }
1876 
1877   // These have to be removed while this is still a valid thread.
1878   remove_stack_guard_pages();
1879 
1880   if (UseTLAB) {
1881     tlab().make_parsable(true);  // retire TLAB
1882   }
1883 
1884   if (JvmtiEnv::environments_might_exist()) {
1885     JvmtiExport::cleanup_thread(this);
1886   }
1887 
1888   // We must flush any deferred card marks before removing a thread from
1889   // the list of active threads.
1890   Universe::heap()->flush_deferred_store_barrier(this);
1891   assert(deferred_card_mark().is_empty(), "Should have been flushed");
1892 
1893 #if INCLUDE_ALL_GCS
1894   // We must flush the G1-related buffers before removing a thread
1895   // from the list of active threads. We must do this after any deferred
1896   // card marks have been flushed (above) so that any entries that are
1897   // added to the thread's dirty card queue as a result are not lost.
1898   if (UseG1GC) {
1899     flush_barrier_queues();
1900   }
1901 #endif // INCLUDE_ALL_GCS
1902 
1903   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1904   Threads::remove(this);
1905 }
1906 
1907 #if INCLUDE_ALL_GCS
1908 // Flush G1-related queues.
1909 void JavaThread::flush_barrier_queues() {
1910   satb_mark_queue().flush();
1911   dirty_card_queue().flush();
1912 }
1913 
1914 void JavaThread::initialize_queues() {
1915   assert(!SafepointSynchronize::is_at_safepoint(),
1916          "we should not be at a safepoint");
1917 
1918   ObjPtrQueue& satb_queue = satb_mark_queue();
1919   SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1920   // The SATB queue should have been constructed with its active
1921   // field set to false.
1922   assert(!satb_queue.is_active(), "SATB queue should not be active");
1923   assert(satb_queue.is_empty(), "SATB queue should be empty");
1924   // If we are creating the thread during a marking cycle, we should
1925   // set the active field of the SATB queue to true.
1926   if (satb_queue_set.is_active()) {
1927     satb_queue.set_active(true);
1928   }
1929 
1930   DirtyCardQueue& dirty_queue = dirty_card_queue();
1931   // The dirty card queue should have been constructed with its
1932   // active field set to true.
1933   assert(dirty_queue.is_active(), "dirty card queue should be active");
1934 }
1935 #endif // INCLUDE_ALL_GCS
1936 
1937 void JavaThread::cleanup_failed_attach_current_thread() {
1938   if (get_thread_profiler() != NULL) {
1939     get_thread_profiler()->disengage();
1940     ResourceMark rm;
1941     get_thread_profiler()->print(get_thread_name());
1942   }
1943 
1944   if (active_handles() != NULL) {
1945     JNIHandleBlock* block = active_handles();
1946     set_active_handles(NULL);
1947     JNIHandleBlock::release_block(block);
1948   }
1949 
1950   if (free_handle_block() != NULL) {
1951     JNIHandleBlock* block = free_handle_block();
1952     set_free_handle_block(NULL);
1953     JNIHandleBlock::release_block(block);
1954   }
1955 
1956   // These have to be removed while this is still a valid thread.
1957   remove_stack_guard_pages();
1958 
1959   if (UseTLAB) {
1960     tlab().make_parsable(true);  // retire TLAB, if any
1961   }
1962 
1963 #if INCLUDE_ALL_GCS
1964   if (UseG1GC) {
1965     flush_barrier_queues();
1966   }
1967 #endif // INCLUDE_ALL_GCS
1968 
1969   Threads::remove(this);
1970   delete this;
1971 }
1972 
1973 
1974 
1975 
1976 JavaThread* JavaThread::active() {
1977   Thread* thread = ThreadLocalStorage::thread();
1978   assert(thread != NULL, "just checking");
1979   if (thread->is_Java_thread()) {
1980     return (JavaThread*) thread;
1981   } else {
1982     assert(thread->is_VM_thread(), "this must be a vm thread");
1983     VM_Operation* op = ((VMThread*) thread)->vm_operation();
1984     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
1985     assert(ret->is_Java_thread(), "must be a Java thread");
1986     return ret;
1987   }
1988 }
1989 
1990 bool JavaThread::is_lock_owned(address adr) const {
1991   if (Thread::is_lock_owned(adr)) return true;
1992 
1993   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
1994     if (chunk->contains(adr)) return true;
1995   }
1996 
1997   return false;
1998 }
1999 
2000 
2001 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2002   chunk->set_next(monitor_chunks());
2003   set_monitor_chunks(chunk);
2004 }
2005 
2006 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2007   guarantee(monitor_chunks() != NULL, "must be non empty");
2008   if (monitor_chunks() == chunk) {
2009     set_monitor_chunks(chunk->next());
2010   } else {
2011     MonitorChunk* prev = monitor_chunks();
2012     while (prev->next() != chunk) prev = prev->next();
2013     prev->set_next(chunk->next());
2014   }
2015 }
2016 
2017 // JVM support.
2018 
2019 // Note: this function shouldn't block if it's called in
2020 // _thread_in_native_trans state (such as from
2021 // check_special_condition_for_native_trans()).
2022 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2023 
2024   if (has_last_Java_frame() && has_async_condition()) {
2025     // If we are at a polling page safepoint (not a poll return)
2026     // then we must defer async exception because live registers
2027     // will be clobbered by the exception path. Poll return is
2028     // ok because the call we a returning from already collides
2029     // with exception handling registers and so there is no issue.
2030     // (The exception handling path kills call result registers but
2031     //  this is ok since the exception kills the result anyway).
2032 
2033     if (is_at_poll_safepoint()) {
2034       // if the code we are returning to has deoptimized we must defer
2035       // the exception otherwise live registers get clobbered on the
2036       // exception path before deoptimization is able to retrieve them.
2037       //
2038       RegisterMap map(this, false);
2039       frame caller_fr = last_frame().sender(&map);
2040       assert(caller_fr.is_compiled_frame(), "what?");
2041       if (caller_fr.is_deoptimized_frame()) {
2042         if (TraceExceptions) {
2043           ResourceMark rm;
2044           tty->print_cr("deferred async exception at compiled safepoint");
2045         }
2046         return;
2047       }
2048     }
2049   }
2050 
2051   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2052   if (condition == _no_async_condition) {
2053     // Conditions have changed since has_special_runtime_exit_condition()
2054     // was called:
2055     // - if we were here only because of an external suspend request,
2056     //   then that was taken care of above (or cancelled) so we are done
2057     // - if we were here because of another async request, then it has
2058     //   been cleared between the has_special_runtime_exit_condition()
2059     //   and now so again we are done
2060     return;
2061   }
2062 
2063   // Check for pending async. exception
2064   if (_pending_async_exception != NULL) {
2065     // Only overwrite an already pending exception, if it is not a threadDeath.
2066     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2067 
2068       // We cannot call Exceptions::_throw(...) here because we cannot block
2069       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2070 
2071       if (TraceExceptions) {
2072         ResourceMark rm;
2073         tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this);
2074         if (has_last_Java_frame() ) {
2075           frame f = last_frame();
2076           tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp());
2077         }
2078         tty->print_cr(" of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2079       }
2080       _pending_async_exception = NULL;
2081       clear_has_async_exception();
2082     }
2083   }
2084 
2085   if (check_unsafe_error &&
2086       condition == _async_unsafe_access_error && !has_pending_exception()) {
2087     condition = _no_async_condition;  // done
2088     switch (thread_state()) {
2089     case _thread_in_vm:
2090       {
2091         JavaThread* THREAD = this;
2092         THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2093       }
2094     case _thread_in_native:
2095       {
2096         ThreadInVMfromNative tiv(this);
2097         JavaThread* THREAD = this;
2098         THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2099       }
2100     case _thread_in_Java:
2101       {
2102         ThreadInVMfromJava tiv(this);
2103         JavaThread* THREAD = this;
2104         THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2105       }
2106     default:
2107       ShouldNotReachHere();
2108     }
2109   }
2110 
2111   assert(condition == _no_async_condition || has_pending_exception() ||
2112          (!check_unsafe_error && condition == _async_unsafe_access_error),
2113          "must have handled the async condition, if no exception");
2114 }
2115 
2116 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2117   //
2118   // Check for pending external suspend. Internal suspend requests do
2119   // not use handle_special_runtime_exit_condition().
2120   // If JNIEnv proxies are allowed, don't self-suspend if the target
2121   // thread is not the current thread. In older versions of jdbx, jdbx
2122   // threads could call into the VM with another thread's JNIEnv so we
2123   // can be here operating on behalf of a suspended thread (4432884).
2124   bool do_self_suspend = is_external_suspend_with_lock();
2125   if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2126     //
2127     // Because thread is external suspended the safepoint code will count
2128     // thread as at a safepoint. This can be odd because we can be here
2129     // as _thread_in_Java which would normally transition to _thread_blocked
2130     // at a safepoint. We would like to mark the thread as _thread_blocked
2131     // before calling java_suspend_self like all other callers of it but
2132     // we must then observe proper safepoint protocol. (We can't leave
2133     // _thread_blocked with a safepoint in progress). However we can be
2134     // here as _thread_in_native_trans so we can't use a normal transition
2135     // constructor/destructor pair because they assert on that type of
2136     // transition. We could do something like:
2137     //
2138     // JavaThreadState state = thread_state();
2139     // set_thread_state(_thread_in_vm);
2140     // {
2141     //   ThreadBlockInVM tbivm(this);
2142     //   java_suspend_self()
2143     // }
2144     // set_thread_state(_thread_in_vm_trans);
2145     // if (safepoint) block;
2146     // set_thread_state(state);
2147     //
2148     // but that is pretty messy. Instead we just go with the way the
2149     // code has worked before and note that this is the only path to
2150     // java_suspend_self that doesn't put the thread in _thread_blocked
2151     // mode.
2152 
2153     frame_anchor()->make_walkable(this);
2154     java_suspend_self();
2155 
2156     // We might be here for reasons in addition to the self-suspend request
2157     // so check for other async requests.
2158   }
2159 
2160   if (check_asyncs) {
2161     check_and_handle_async_exceptions();
2162   }
2163 }
2164 
2165 void JavaThread::send_thread_stop(oop java_throwable)  {
2166   assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2167   assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2168   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2169 
2170   // Do not throw asynchronous exceptions against the compiler thread
2171   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2172   if (is_Compiler_thread()) return;
2173 
2174   {
2175     // Actually throw the Throwable against the target Thread - however
2176     // only if there is no thread death exception installed already.
2177     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2178       // If the topmost frame is a runtime stub, then we are calling into
2179       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2180       // must deoptimize the caller before continuing, as the compiled  exception handler table
2181       // may not be valid
2182       if (has_last_Java_frame()) {
2183         frame f = last_frame();
2184         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2185           // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2186           RegisterMap reg_map(this, UseBiasedLocking);
2187           frame compiled_frame = f.sender(&reg_map);
2188           if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2189             Deoptimization::deoptimize(this, compiled_frame, &reg_map);
2190           }
2191         }
2192       }
2193 
2194       // Set async. pending exception in thread.
2195       set_pending_async_exception(java_throwable);
2196 
2197       if (TraceExceptions) {
2198        ResourceMark rm;
2199        tty->print_cr("Pending Async. exception installed of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2200       }
2201       // for AbortVMOnException flag
2202       NOT_PRODUCT(Exceptions::debug_check_abort(InstanceKlass::cast(_pending_async_exception->klass())->external_name()));
2203     }
2204   }
2205 
2206 
2207   // Interrupt thread so it will wake up from a potential wait()
2208   Thread::interrupt(this);
2209 }
2210 
2211 // External suspension mechanism.
2212 //
2213 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2214 // to any VM_locks and it is at a transition
2215 // Self-suspension will happen on the transition out of the vm.
2216 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2217 //
2218 // Guarantees on return:
2219 //   + Target thread will not execute any new bytecode (that's why we need to
2220 //     force a safepoint)
2221 //   + Target thread will not enter any new monitors
2222 //
2223 void JavaThread::java_suspend() {
2224   { MutexLocker mu(Threads_lock);
2225     if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2226        return;
2227     }
2228   }
2229 
2230   { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2231     if (!is_external_suspend()) {
2232       // a racing resume has cancelled us; bail out now
2233       return;
2234     }
2235 
2236     // suspend is done
2237     uint32_t debug_bits = 0;
2238     // Warning: is_ext_suspend_completed() may temporarily drop the
2239     // SR_lock to allow the thread to reach a stable thread state if
2240     // it is currently in a transient thread state.
2241     if (is_ext_suspend_completed(false /* !called_by_wait */,
2242                                  SuspendRetryDelay, &debug_bits) ) {
2243       return;
2244     }
2245   }
2246 
2247   VM_ForceSafepoint vm_suspend;
2248   VMThread::execute(&vm_suspend);
2249 }
2250 
2251 // Part II of external suspension.
2252 // A JavaThread self suspends when it detects a pending external suspend
2253 // request. This is usually on transitions. It is also done in places
2254 // where continuing to the next transition would surprise the caller,
2255 // e.g., monitor entry.
2256 //
2257 // Returns the number of times that the thread self-suspended.
2258 //
2259 // Note: DO NOT call java_suspend_self() when you just want to block current
2260 //       thread. java_suspend_self() is the second stage of cooperative
2261 //       suspension for external suspend requests and should only be used
2262 //       to complete an external suspend request.
2263 //
2264 int JavaThread::java_suspend_self() {
2265   int ret = 0;
2266 
2267   // we are in the process of exiting so don't suspend
2268   if (is_exiting()) {
2269      clear_external_suspend();
2270      return ret;
2271   }
2272 
2273   assert(_anchor.walkable() ||
2274     (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2275     "must have walkable stack");
2276 
2277   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2278 
2279   assert(!this->is_ext_suspended(),
2280     "a thread trying to self-suspend should not already be suspended");
2281 
2282   if (this->is_suspend_equivalent()) {
2283     // If we are self-suspending as a result of the lifting of a
2284     // suspend equivalent condition, then the suspend_equivalent
2285     // flag is not cleared until we set the ext_suspended flag so
2286     // that wait_for_ext_suspend_completion() returns consistent
2287     // results.
2288     this->clear_suspend_equivalent();
2289   }
2290 
2291   // A racing resume may have cancelled us before we grabbed SR_lock
2292   // above. Or another external suspend request could be waiting for us
2293   // by the time we return from SR_lock()->wait(). The thread
2294   // that requested the suspension may already be trying to walk our
2295   // stack and if we return now, we can change the stack out from under
2296   // it. This would be a "bad thing (TM)" and cause the stack walker
2297   // to crash. We stay self-suspended until there are no more pending
2298   // external suspend requests.
2299   while (is_external_suspend()) {
2300     ret++;
2301     this->set_ext_suspended();
2302 
2303     // _ext_suspended flag is cleared by java_resume()
2304     while (is_ext_suspended()) {
2305       this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2306     }
2307   }
2308 
2309   return ret;
2310 }
2311 
2312 #ifdef ASSERT
2313 // verify the JavaThread has not yet been published in the Threads::list, and
2314 // hence doesn't need protection from concurrent access at this stage
2315 void JavaThread::verify_not_published() {
2316   if (!Threads_lock->owned_by_self()) {
2317    MutexLockerEx ml(Threads_lock,  Mutex::_no_safepoint_check_flag);
2318    assert( !Threads::includes(this),
2319            "java thread shouldn't have been published yet!");
2320   }
2321   else {
2322    assert( !Threads::includes(this),
2323            "java thread shouldn't have been published yet!");
2324   }
2325 }
2326 #endif
2327 
2328 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2329 // progress or when _suspend_flags is non-zero.
2330 // Current thread needs to self-suspend if there is a suspend request and/or
2331 // block if a safepoint is in progress.
2332 // Async exception ISN'T checked.
2333 // Note only the ThreadInVMfromNative transition can call this function
2334 // directly and when thread state is _thread_in_native_trans
2335 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2336   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2337 
2338   JavaThread *curJT = JavaThread::current();
2339   bool do_self_suspend = thread->is_external_suspend();
2340 
2341   assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2342 
2343   // If JNIEnv proxies are allowed, don't self-suspend if the target
2344   // thread is not the current thread. In older versions of jdbx, jdbx
2345   // threads could call into the VM with another thread's JNIEnv so we
2346   // can be here operating on behalf of a suspended thread (4432884).
2347   if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2348     JavaThreadState state = thread->thread_state();
2349 
2350     // We mark this thread_blocked state as a suspend-equivalent so
2351     // that a caller to is_ext_suspend_completed() won't be confused.
2352     // The suspend-equivalent state is cleared by java_suspend_self().
2353     thread->set_suspend_equivalent();
2354 
2355     // If the safepoint code sees the _thread_in_native_trans state, it will
2356     // wait until the thread changes to other thread state. There is no
2357     // guarantee on how soon we can obtain the SR_lock and complete the
2358     // self-suspend request. It would be a bad idea to let safepoint wait for
2359     // too long. Temporarily change the state to _thread_blocked to
2360     // let the VM thread know that this thread is ready for GC. The problem
2361     // of changing thread state is that safepoint could happen just after
2362     // java_suspend_self() returns after being resumed, and VM thread will
2363     // see the _thread_blocked state. We must check for safepoint
2364     // after restoring the state and make sure we won't leave while a safepoint
2365     // is in progress.
2366     thread->set_thread_state(_thread_blocked);
2367     thread->java_suspend_self();
2368     thread->set_thread_state(state);
2369     // Make sure new state is seen by VM thread
2370     if (os::is_MP()) {
2371       if (UseMembar) {
2372         // Force a fence between the write above and read below
2373         OrderAccess::fence();
2374       } else {
2375         // Must use this rather than serialization page in particular on Windows
2376         InterfaceSupport::serialize_memory(thread);
2377       }
2378     }
2379   }
2380 
2381   if (SafepointSynchronize::do_call_back()) {
2382     // If we are safepointing, then block the caller which may not be
2383     // the same as the target thread (see above).
2384     SafepointSynchronize::block(curJT);
2385   }
2386 
2387   if (thread->is_deopt_suspend()) {
2388     thread->clear_deopt_suspend();
2389     RegisterMap map(thread, false);
2390     frame f = thread->last_frame();
2391     while ( f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2392       f = f.sender(&map);
2393     }
2394     if (f.id() == thread->must_deopt_id()) {
2395       thread->clear_must_deopt_id();
2396       f.deoptimize(thread);
2397     } else {
2398       fatal("missed deoptimization!");
2399     }
2400   }
2401 }
2402 
2403 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2404 // progress or when _suspend_flags is non-zero.
2405 // Current thread needs to self-suspend if there is a suspend request and/or
2406 // block if a safepoint is in progress.
2407 // Also check for pending async exception (not including unsafe access error).
2408 // Note only the native==>VM/Java barriers can call this function and when
2409 // thread state is _thread_in_native_trans.
2410 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2411   check_safepoint_and_suspend_for_native_trans(thread);
2412 
2413   if (thread->has_async_exception()) {
2414     // We are in _thread_in_native_trans state, don't handle unsafe
2415     // access error since that may block.
2416     thread->check_and_handle_async_exceptions(false);
2417   }
2418 }
2419 
2420 // This is a variant of the normal
2421 // check_special_condition_for_native_trans with slightly different
2422 // semantics for use by critical native wrappers.  It does all the
2423 // normal checks but also performs the transition back into
2424 // thread_in_Java state.  This is required so that critical natives
2425 // can potentially block and perform a GC if they are the last thread
2426 // exiting the GC_locker.
2427 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2428   check_special_condition_for_native_trans(thread);
2429 
2430   // Finish the transition
2431   thread->set_thread_state(_thread_in_Java);
2432 
2433   if (thread->do_critical_native_unlock()) {
2434     ThreadInVMfromJavaNoAsyncException tiv(thread);
2435     GC_locker::unlock_critical(thread);
2436     thread->clear_critical_native_unlock();
2437   }
2438 }
2439 
2440 // We need to guarantee the Threads_lock here, since resumes are not
2441 // allowed during safepoint synchronization
2442 // Can only resume from an external suspension
2443 void JavaThread::java_resume() {
2444   assert_locked_or_safepoint(Threads_lock);
2445 
2446   // Sanity check: thread is gone, has started exiting or the thread
2447   // was not externally suspended.
2448   if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2449     return;
2450   }
2451 
2452   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2453 
2454   clear_external_suspend();
2455 
2456   if (is_ext_suspended()) {
2457     clear_ext_suspended();
2458     SR_lock()->notify_all();
2459   }
2460 }
2461 
2462 void JavaThread::create_stack_guard_pages() {
2463   if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return;
2464   address low_addr = stack_base() - stack_size();
2465   size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2466 
2467   int allocate = os::allocate_stack_guard_pages();
2468   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2469 
2470   if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) {
2471     warning("Attempt to allocate stack guard pages failed.");
2472     return;
2473   }
2474 
2475   if (os::guard_memory((char *) low_addr, len)) {
2476     _stack_guard_state = stack_guard_enabled;
2477   } else {
2478     warning("Attempt to protect stack guard pages failed.");
2479     if (os::uncommit_memory((char *) low_addr, len)) {
2480       warning("Attempt to deallocate stack guard pages failed.");
2481     }
2482   }
2483 }
2484 
2485 void JavaThread::remove_stack_guard_pages() {
2486   assert(Thread::current() == this, "from different thread");
2487   if (_stack_guard_state == stack_guard_unused) return;
2488   address low_addr = stack_base() - stack_size();
2489   size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2490 
2491   if (os::allocate_stack_guard_pages()) {
2492     if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2493       _stack_guard_state = stack_guard_unused;
2494     } else {
2495       warning("Attempt to deallocate stack guard pages failed.");
2496     }
2497   } else {
2498     if (_stack_guard_state == stack_guard_unused) return;
2499     if (os::unguard_memory((char *) low_addr, len)) {
2500       _stack_guard_state = stack_guard_unused;
2501     } else {
2502         warning("Attempt to unprotect stack guard pages failed.");
2503     }
2504   }
2505 }
2506 
2507 void JavaThread::enable_stack_yellow_zone() {
2508   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2509   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2510 
2511   // The base notation is from the stacks point of view, growing downward.
2512   // We need to adjust it to work correctly with guard_memory()
2513   address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2514 
2515   guarantee(base < stack_base(),"Error calculating stack yellow zone");
2516   guarantee(base < os::current_stack_pointer(),"Error calculating stack yellow zone");
2517 
2518   if (os::guard_memory((char *) base, stack_yellow_zone_size())) {
2519     _stack_guard_state = stack_guard_enabled;
2520   } else {
2521     warning("Attempt to guard stack yellow zone failed.");
2522   }
2523   enable_register_stack_guard();
2524 }
2525 
2526 void JavaThread::disable_stack_yellow_zone() {
2527   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2528   assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled");
2529 
2530   // Simply return if called for a thread that does not use guard pages.
2531   if (_stack_guard_state == stack_guard_unused) return;
2532 
2533   // The base notation is from the stacks point of view, growing downward.
2534   // We need to adjust it to work correctly with guard_memory()
2535   address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2536 
2537   if (os::unguard_memory((char *)base, stack_yellow_zone_size())) {
2538     _stack_guard_state = stack_guard_yellow_disabled;
2539   } else {
2540     warning("Attempt to unguard stack yellow zone failed.");
2541   }
2542   disable_register_stack_guard();
2543 }
2544 
2545 void JavaThread::enable_stack_red_zone() {
2546   // The base notation is from the stacks point of view, growing downward.
2547   // We need to adjust it to work correctly with guard_memory()
2548   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2549   address base = stack_red_zone_base() - stack_red_zone_size();
2550 
2551   guarantee(base < stack_base(),"Error calculating stack red zone");
2552   guarantee(base < os::current_stack_pointer(),"Error calculating stack red zone");
2553 
2554   if(!os::guard_memory((char *) base, stack_red_zone_size())) {
2555     warning("Attempt to guard stack red zone failed.");
2556   }
2557 }
2558 
2559 void JavaThread::disable_stack_red_zone() {
2560   // The base notation is from the stacks point of view, growing downward.
2561   // We need to adjust it to work correctly with guard_memory()
2562   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2563   address base = stack_red_zone_base() - stack_red_zone_size();
2564   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2565     warning("Attempt to unguard stack red zone failed.");
2566   }
2567 }
2568 
2569 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2570   // ignore is there is no stack
2571   if (!has_last_Java_frame()) return;
2572   // traverse the stack frames. Starts from top frame.
2573   for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2574     frame* fr = fst.current();
2575     f(fr, fst.register_map());
2576   }
2577 }
2578 
2579 
2580 #ifndef PRODUCT
2581 // Deoptimization
2582 // Function for testing deoptimization
2583 void JavaThread::deoptimize() {
2584   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2585   StackFrameStream fst(this, UseBiasedLocking);
2586   bool deopt = false;           // Dump stack only if a deopt actually happens.
2587   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2588   // Iterate over all frames in the thread and deoptimize
2589   for(; !fst.is_done(); fst.next()) {
2590     if(fst.current()->can_be_deoptimized()) {
2591 
2592       if (only_at) {
2593         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
2594         // consists of comma or carriage return separated numbers so
2595         // search for the current bci in that string.
2596         address pc = fst.current()->pc();
2597         nmethod* nm =  (nmethod*) fst.current()->cb();
2598         ScopeDesc* sd = nm->scope_desc_at( pc);
2599         char buffer[8];
2600         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2601         size_t len = strlen(buffer);
2602         const char * found = strstr(DeoptimizeOnlyAt, buffer);
2603         while (found != NULL) {
2604           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2605               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2606             // Check that the bci found is bracketed by terminators.
2607             break;
2608           }
2609           found = strstr(found + 1, buffer);
2610         }
2611         if (!found) {
2612           continue;
2613         }
2614       }
2615 
2616       if (DebugDeoptimization && !deopt) {
2617         deopt = true; // One-time only print before deopt
2618         tty->print_cr("[BEFORE Deoptimization]");
2619         trace_frames();
2620         trace_stack();
2621       }
2622       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2623     }
2624   }
2625 
2626   if (DebugDeoptimization && deopt) {
2627     tty->print_cr("[AFTER Deoptimization]");
2628     trace_frames();
2629   }
2630 }
2631 
2632 
2633 // Make zombies
2634 void JavaThread::make_zombies() {
2635   for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2636     if (fst.current()->can_be_deoptimized()) {
2637       // it is a Java nmethod
2638       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2639       nm->make_not_entrant();
2640     }
2641   }
2642 }
2643 #endif // PRODUCT
2644 
2645 
2646 void JavaThread::deoptimized_wrt_marked_nmethods() {
2647   if (!has_last_Java_frame()) return;
2648   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2649   StackFrameStream fst(this, UseBiasedLocking);
2650   for(; !fst.is_done(); fst.next()) {
2651     if (fst.current()->should_be_deoptimized()) {
2652       if (LogCompilation && xtty != NULL) {
2653         nmethod* nm = fst.current()->cb()->as_nmethod_or_null();
2654         xtty->elem("deoptimized thread='" UINTX_FORMAT "' compile_id='%d'",
2655                    this->name(), nm != NULL ? nm->compile_id() : -1);
2656       }
2657 
2658       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2659     }
2660   }
2661 }
2662 
2663 
2664 // GC support
2665 static void frame_gc_epilogue(frame* f, const RegisterMap* map) { f->gc_epilogue(); }
2666 
2667 void JavaThread::gc_epilogue() {
2668   frames_do(frame_gc_epilogue);
2669 }
2670 
2671 
2672 static void frame_gc_prologue(frame* f, const RegisterMap* map) { f->gc_prologue(); }
2673 
2674 void JavaThread::gc_prologue() {
2675   frames_do(frame_gc_prologue);
2676 }
2677 
2678 // If the caller is a NamedThread, then remember, in the current scope,
2679 // the given JavaThread in its _processed_thread field.
2680 class RememberProcessedThread: public StackObj {
2681   NamedThread* _cur_thr;
2682 public:
2683   RememberProcessedThread(JavaThread* jthr) {
2684     Thread* thread = Thread::current();
2685     if (thread->is_Named_thread()) {
2686       _cur_thr = (NamedThread *)thread;
2687       _cur_thr->set_processed_thread(jthr);
2688     } else {
2689       _cur_thr = NULL;
2690     }
2691   }
2692 
2693   ~RememberProcessedThread() {
2694     if (_cur_thr) {
2695       _cur_thr->set_processed_thread(NULL);
2696     }
2697   }
2698 };
2699 
2700 void JavaThread::oops_do(OopClosure* f, CLDToOopClosure* cld_f, CodeBlobClosure* cf) {
2701   // Verify that the deferred card marks have been flushed.
2702   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2703 
2704   // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2705   // since there may be more than one thread using each ThreadProfiler.
2706 
2707   // Traverse the GCHandles
2708   Thread::oops_do(f, cld_f, cf);
2709 
2710   assert( (!has_last_Java_frame() && java_call_counter() == 0) ||
2711           (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2712 
2713   if (has_last_Java_frame()) {
2714     // Record JavaThread to GC thread
2715     RememberProcessedThread rpt(this);
2716 
2717     // Traverse the privileged stack
2718     if (_privileged_stack_top != NULL) {
2719       _privileged_stack_top->oops_do(f);
2720     }
2721 
2722     // traverse the registered growable array
2723     if (_array_for_gc != NULL) {
2724       for (int index = 0; index < _array_for_gc->length(); index++) {
2725         f->do_oop(_array_for_gc->adr_at(index));
2726       }
2727     }
2728 
2729     // Traverse the monitor chunks
2730     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2731       chunk->oops_do(f);
2732     }
2733 
2734     // Traverse the execution stack
2735     for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2736       fst.current()->oops_do(f, cld_f, cf, fst.register_map());
2737     }
2738   }
2739 
2740   // callee_target is never live across a gc point so NULL it here should
2741   // it still contain a methdOop.
2742 
2743   set_callee_target(NULL);
2744 
2745   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2746   // If we have deferred set_locals there might be oops waiting to be
2747   // written
2748   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2749   if (list != NULL) {
2750     for (int i = 0; i < list->length(); i++) {
2751       list->at(i)->oops_do(f);
2752     }
2753   }
2754 
2755   // Traverse instance variables at the end since the GC may be moving things
2756   // around using this function
2757   f->do_oop((oop*) &_threadObj);
2758   f->do_oop((oop*) &_vm_result);
2759   f->do_oop((oop*) &_exception_oop);
2760   f->do_oop((oop*) &_pending_async_exception);
2761 
2762   if (jvmti_thread_state() != NULL) {
2763     jvmti_thread_state()->oops_do(f);
2764   }
2765 }
2766 
2767 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2768   Thread::nmethods_do(cf);  // (super method is a no-op)
2769 
2770   assert( (!has_last_Java_frame() && java_call_counter() == 0) ||
2771           (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2772 
2773   if (has_last_Java_frame()) {
2774     // Traverse the execution stack
2775     for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2776       fst.current()->nmethods_do(cf);
2777     }
2778   }
2779 }
2780 
2781 void JavaThread::metadata_do(void f(Metadata*)) {
2782   Thread::metadata_do(f);
2783   if (has_last_Java_frame()) {
2784     // Traverse the execution stack to call f() on the methods in the stack
2785     for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2786       fst.current()->metadata_do(f);
2787     }
2788   } else if (is_Compiler_thread()) {
2789     // need to walk ciMetadata in current compile tasks to keep alive.
2790     CompilerThread* ct = (CompilerThread*)this;
2791     if (ct->env() != NULL) {
2792       ct->env()->metadata_do(f);
2793     }
2794   }
2795 }
2796 
2797 // Printing
2798 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2799   switch (_thread_state) {
2800   case _thread_uninitialized:     return "_thread_uninitialized";
2801   case _thread_new:               return "_thread_new";
2802   case _thread_new_trans:         return "_thread_new_trans";
2803   case _thread_in_native:         return "_thread_in_native";
2804   case _thread_in_native_trans:   return "_thread_in_native_trans";
2805   case _thread_in_vm:             return "_thread_in_vm";
2806   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
2807   case _thread_in_Java:           return "_thread_in_Java";
2808   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
2809   case _thread_blocked:           return "_thread_blocked";
2810   case _thread_blocked_trans:     return "_thread_blocked_trans";
2811   default:                        return "unknown thread state";
2812   }
2813 }
2814 
2815 #ifndef PRODUCT
2816 void JavaThread::print_thread_state_on(outputStream *st) const {
2817   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
2818 };
2819 void JavaThread::print_thread_state() const {
2820   print_thread_state_on(tty);
2821 };
2822 #endif // PRODUCT
2823 
2824 // Called by Threads::print() for VM_PrintThreads operation
2825 void JavaThread::print_on(outputStream *st) const {
2826   st->print("\"%s\" ", get_thread_name());
2827   oop thread_oop = threadObj();
2828   if (thread_oop != NULL) {
2829     st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop));
2830     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
2831     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2832   }
2833   Thread::print_on(st);
2834   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2835   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2836   if (thread_oop != NULL && JDK_Version::is_gte_jdk15x_version()) {
2837     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2838   }
2839 #ifndef PRODUCT
2840   print_thread_state_on(st);
2841   _safepoint_state->print_on(st);
2842 #endif // PRODUCT
2843 }
2844 
2845 // Called by fatal error handler. The difference between this and
2846 // JavaThread::print() is that we can't grab lock or allocate memory.
2847 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2848   st->print("JavaThread \"%s\"",  get_thread_name_string(buf, buflen));
2849   oop thread_obj = threadObj();
2850   if (thread_obj != NULL) {
2851      if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2852   }
2853   st->print(" [");
2854   st->print("%s", _get_thread_state_name(_thread_state));
2855   if (osthread()) {
2856     st->print(", id=%d", osthread()->thread_id());
2857   }
2858   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2859             _stack_base - _stack_size, _stack_base);
2860   st->print("]");
2861   return;
2862 }
2863 
2864 // Verification
2865 
2866 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2867 
2868 void JavaThread::verify() {
2869   // Verify oops in the thread.
2870   oops_do(&VerifyOopClosure::verify_oop, NULL, NULL);
2871 
2872   // Verify the stack frames.
2873   frames_do(frame_verify);
2874 }
2875 
2876 // CR 6300358 (sub-CR 2137150)
2877 // Most callers of this method assume that it can't return NULL but a
2878 // thread may not have a name whilst it is in the process of attaching to
2879 // the VM - see CR 6412693, and there are places where a JavaThread can be
2880 // seen prior to having it's threadObj set (eg JNI attaching threads and
2881 // if vm exit occurs during initialization). These cases can all be accounted
2882 // for such that this method never returns NULL.
2883 const char* JavaThread::get_thread_name() const {
2884 #ifdef ASSERT
2885   // early safepoints can hit while current thread does not yet have TLS
2886   if (!SafepointSynchronize::is_at_safepoint()) {
2887     Thread *cur = Thread::current();
2888     if (!(cur->is_Java_thread() && cur == this)) {
2889       // Current JavaThreads are allowed to get their own name without
2890       // the Threads_lock.
2891       assert_locked_or_safepoint(Threads_lock);
2892     }
2893   }
2894 #endif // ASSERT
2895     return get_thread_name_string();
2896 }
2897 
2898 // Returns a non-NULL representation of this thread's name, or a suitable
2899 // descriptive string if there is no set name
2900 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2901   const char* name_str;
2902   oop thread_obj = threadObj();
2903   if (thread_obj != NULL) {
2904     typeArrayOop name = java_lang_Thread::name(thread_obj);
2905     if (name != NULL) {
2906       if (buf == NULL) {
2907         name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2908       }
2909       else {
2910         name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length(), buf, buflen);
2911       }
2912     }
2913     else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
2914       name_str = "<no-name - thread is attaching>";
2915     }
2916     else {
2917       name_str = Thread::name();
2918     }
2919   }
2920   else {
2921     name_str = Thread::name();
2922   }
2923   assert(name_str != NULL, "unexpected NULL thread name");
2924   return name_str;
2925 }
2926 
2927 
2928 const char* JavaThread::get_threadgroup_name() const {
2929   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2930   oop thread_obj = threadObj();
2931   if (thread_obj != NULL) {
2932     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2933     if (thread_group != NULL) {
2934       typeArrayOop name = java_lang_ThreadGroup::name(thread_group);
2935       // ThreadGroup.name can be null
2936       if (name != NULL) {
2937         const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2938         return str;
2939       }
2940     }
2941   }
2942   return NULL;
2943 }
2944 
2945 const char* JavaThread::get_parent_name() const {
2946   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2947   oop thread_obj = threadObj();
2948   if (thread_obj != NULL) {
2949     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2950     if (thread_group != NULL) {
2951       oop parent = java_lang_ThreadGroup::parent(thread_group);
2952       if (parent != NULL) {
2953         typeArrayOop name = java_lang_ThreadGroup::name(parent);
2954         // ThreadGroup.name can be null
2955         if (name != NULL) {
2956           const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2957           return str;
2958         }
2959       }
2960     }
2961   }
2962   return NULL;
2963 }
2964 
2965 ThreadPriority JavaThread::java_priority() const {
2966   oop thr_oop = threadObj();
2967   if (thr_oop == NULL) return NormPriority; // Bootstrapping
2968   ThreadPriority priority = java_lang_Thread::priority(thr_oop);
2969   assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
2970   return priority;
2971 }
2972 
2973 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
2974 
2975   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
2976   // Link Java Thread object <-> C++ Thread
2977 
2978   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
2979   // and put it into a new Handle.  The Handle "thread_oop" can then
2980   // be used to pass the C++ thread object to other methods.
2981 
2982   // Set the Java level thread object (jthread) field of the
2983   // new thread (a JavaThread *) to C++ thread object using the
2984   // "thread_oop" handle.
2985 
2986   // Set the thread field (a JavaThread *) of the
2987   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
2988 
2989   Handle thread_oop(Thread::current(),
2990                     JNIHandles::resolve_non_null(jni_thread));
2991   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
2992     "must be initialized");
2993   set_threadObj(thread_oop());
2994   java_lang_Thread::set_thread(thread_oop(), this);
2995 
2996   if (prio == NoPriority) {
2997     prio = java_lang_Thread::priority(thread_oop());
2998     assert(prio != NoPriority, "A valid priority should be present");
2999   }
3000 
3001   // Push the Java priority down to the native thread; needs Threads_lock
3002   Thread::set_priority(this, prio);
3003 
3004   // Add the new thread to the Threads list and set it in motion.
3005   // We must have threads lock in order to call Threads::add.
3006   // It is crucial that we do not block before the thread is
3007   // added to the Threads list for if a GC happens, then the java_thread oop
3008   // will not be visited by GC.
3009   Threads::add(this);
3010 }
3011 
3012 oop JavaThread::current_park_blocker() {
3013   // Support for JSR-166 locks
3014   oop thread_oop = threadObj();
3015   if (thread_oop != NULL &&
3016       JDK_Version::current().supports_thread_park_blocker()) {
3017     return java_lang_Thread::park_blocker(thread_oop);
3018   }
3019   return NULL;
3020 }
3021 
3022 
3023 void JavaThread::print_stack_on(outputStream* st) {
3024   if (!has_last_Java_frame()) return;
3025   ResourceMark rm;
3026   HandleMark   hm;
3027 
3028   RegisterMap reg_map(this);
3029   vframe* start_vf = last_java_vframe(&reg_map);
3030   int count = 0;
3031   for (vframe* f = start_vf; f; f = f->sender() ) {
3032     if (f->is_java_frame()) {
3033       javaVFrame* jvf = javaVFrame::cast(f);
3034       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3035 
3036       // Print out lock information
3037       if (JavaMonitorsInStackTrace) {
3038         jvf->print_lock_info_on(st, count);
3039       }
3040     } else {
3041       // Ignore non-Java frames
3042     }
3043 
3044     // Bail-out case for too deep stacks
3045     count++;
3046     if (MaxJavaStackTraceDepth == count) return;
3047   }
3048 }
3049 
3050 
3051 // JVMTI PopFrame support
3052 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3053   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3054   if (in_bytes(size_in_bytes) != 0) {
3055     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3056     _popframe_preserved_args_size = in_bytes(size_in_bytes);
3057     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3058   }
3059 }
3060 
3061 void* JavaThread::popframe_preserved_args() {
3062   return _popframe_preserved_args;
3063 }
3064 
3065 ByteSize JavaThread::popframe_preserved_args_size() {
3066   return in_ByteSize(_popframe_preserved_args_size);
3067 }
3068 
3069 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3070   int sz = in_bytes(popframe_preserved_args_size());
3071   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3072   return in_WordSize(sz / wordSize);
3073 }
3074 
3075 void JavaThread::popframe_free_preserved_args() {
3076   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3077   FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args, mtThread);
3078   _popframe_preserved_args = NULL;
3079   _popframe_preserved_args_size = 0;
3080 }
3081 
3082 #ifndef PRODUCT
3083 
3084 void JavaThread::trace_frames() {
3085   tty->print_cr("[Describe stack]");
3086   int frame_no = 1;
3087   for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3088     tty->print("  %d. ", frame_no++);
3089     fst.current()->print_value_on(tty,this);
3090     tty->cr();
3091   }
3092 }
3093 
3094 class PrintAndVerifyOopClosure: public OopClosure {
3095  protected:
3096   template <class T> inline void do_oop_work(T* p) {
3097     oop obj = oopDesc::load_decode_heap_oop(p);
3098     if (obj == NULL) return;
3099     tty->print(INTPTR_FORMAT ": ", p);
3100     if (obj->is_oop_or_null()) {
3101       if (obj->is_objArray()) {
3102         tty->print_cr("valid objArray: " INTPTR_FORMAT, (oopDesc*) obj);
3103       } else {
3104         obj->print();
3105       }
3106     } else {
3107       tty->print_cr("invalid oop: " INTPTR_FORMAT, (oopDesc*) obj);
3108     }
3109     tty->cr();
3110   }
3111  public:
3112   virtual void do_oop(oop* p) { do_oop_work(p); }
3113   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
3114 };
3115 
3116 
3117 static void oops_print(frame* f, const RegisterMap *map) {
3118   PrintAndVerifyOopClosure print;
3119   f->print_value();
3120   f->oops_do(&print, NULL, NULL, (RegisterMap*)map);
3121 }
3122 
3123 // Print our all the locations that contain oops and whether they are
3124 // valid or not.  This useful when trying to find the oldest frame
3125 // where an oop has gone bad since the frame walk is from youngest to
3126 // oldest.
3127 void JavaThread::trace_oops() {
3128   tty->print_cr("[Trace oops]");
3129   frames_do(oops_print);
3130 }
3131 
3132 
3133 #ifdef ASSERT
3134 // Print or validate the layout of stack frames
3135 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3136   ResourceMark rm;
3137   PRESERVE_EXCEPTION_MARK;
3138   FrameValues values;
3139   int frame_no = 0;
3140   for(StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3141     fst.current()->describe(values, ++frame_no);
3142     if (depth == frame_no) break;
3143   }
3144   if (validate_only) {
3145     values.validate();
3146   } else {
3147     tty->print_cr("[Describe stack layout]");
3148     values.print(this);
3149   }
3150 }
3151 #endif
3152 
3153 void JavaThread::trace_stack_from(vframe* start_vf) {
3154   ResourceMark rm;
3155   int vframe_no = 1;
3156   for (vframe* f = start_vf; f; f = f->sender() ) {
3157     if (f->is_java_frame()) {
3158       javaVFrame::cast(f)->print_activation(vframe_no++);
3159     } else {
3160       f->print();
3161     }
3162     if (vframe_no > StackPrintLimit) {
3163       tty->print_cr("...<more frames>...");
3164       return;
3165     }
3166   }
3167 }
3168 
3169 
3170 void JavaThread::trace_stack() {
3171   if (!has_last_Java_frame()) return;
3172   ResourceMark rm;
3173   HandleMark   hm;
3174   RegisterMap reg_map(this);
3175   trace_stack_from(last_java_vframe(&reg_map));
3176 }
3177 
3178 
3179 #endif // PRODUCT
3180 
3181 
3182 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3183   assert(reg_map != NULL, "a map must be given");
3184   frame f = last_frame();
3185   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender() ) {
3186     if (vf->is_java_frame()) return javaVFrame::cast(vf);
3187   }
3188   return NULL;
3189 }
3190 
3191 
3192 Klass* JavaThread::security_get_caller_class(int depth) {
3193   vframeStream vfst(this);
3194   vfst.security_get_caller_frame(depth);
3195   if (!vfst.at_end()) {
3196     return vfst.method()->method_holder();
3197   }
3198   return NULL;
3199 }
3200 
3201 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3202   assert(thread->is_Compiler_thread(), "must be compiler thread");
3203   CompileBroker::compiler_thread_loop();
3204 }
3205 
3206 // Create a CompilerThread
3207 CompilerThread::CompilerThread(CompileQueue* queue, CompilerCounters* counters)
3208 : JavaThread(&compiler_thread_entry) {
3209   _env   = NULL;
3210   _log   = NULL;
3211   _task  = NULL;
3212   _queue = queue;
3213   _counters = counters;
3214   _buffer_blob = NULL;
3215   _scanned_nmethod = NULL;
3216   _compiler = NULL;
3217 
3218 #ifndef PRODUCT
3219   _ideal_graph_printer = NULL;
3220 #endif
3221 }
3222 
3223 void CompilerThread::oops_do(OopClosure* f, CLDToOopClosure* cld_f, CodeBlobClosure* cf) {
3224   JavaThread::oops_do(f, cld_f, cf);
3225   if (_scanned_nmethod != NULL && cf != NULL) {
3226     // Safepoints can occur when the sweeper is scanning an nmethod so
3227     // process it here to make sure it isn't unloaded in the middle of
3228     // a scan.
3229     cf->do_code_blob(_scanned_nmethod);
3230   }
3231 }
3232 
3233 
3234 // ======= Threads ========
3235 
3236 // The Threads class links together all active threads, and provides
3237 // operations over all threads.  It is protected by its own Mutex
3238 // lock, which is also used in other contexts to protect thread
3239 // operations from having the thread being operated on from exiting
3240 // and going away unexpectedly (e.g., safepoint synchronization)
3241 
3242 JavaThread* Threads::_thread_list = NULL;
3243 int         Threads::_number_of_threads = 0;
3244 int         Threads::_number_of_non_daemon_threads = 0;
3245 int         Threads::_return_code = 0;
3246 size_t      JavaThread::_stack_size_at_create = 0;
3247 #ifdef ASSERT
3248 bool        Threads::_vm_complete = false;
3249 #endif
3250 
3251 // All JavaThreads
3252 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3253 
3254 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3255 void Threads::threads_do(ThreadClosure* tc) {
3256   assert_locked_or_safepoint(Threads_lock);
3257   // ALL_JAVA_THREADS iterates through all JavaThreads
3258   ALL_JAVA_THREADS(p) {
3259     tc->do_thread(p);
3260   }
3261   // Someday we could have a table or list of all non-JavaThreads.
3262   // For now, just manually iterate through them.
3263   tc->do_thread(VMThread::vm_thread());
3264   Universe::heap()->gc_threads_do(tc);
3265   WatcherThread *wt = WatcherThread::watcher_thread();
3266   // Strictly speaking, the following NULL check isn't sufficient to make sure
3267   // the data for WatcherThread is still valid upon being examined. However,
3268   // considering that WatchThread terminates when the VM is on the way to
3269   // exit at safepoint, the chance of the above is extremely small. The right
3270   // way to prevent termination of WatcherThread would be to acquire
3271   // Terminator_lock, but we can't do that without violating the lock rank
3272   // checking in some cases.
3273   if (wt != NULL)
3274     tc->do_thread(wt);
3275 
3276   // If CompilerThreads ever become non-JavaThreads, add them here
3277 }
3278 
3279 
3280 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3281   TraceTime timer("Initialize java.lang classes", TraceStartupTime);
3282 
3283   if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3284     create_vm_init_libraries();
3285   }
3286 
3287   initialize_class(vmSymbols::java_lang_String(), CHECK);
3288 
3289   // Initialize java_lang.System (needed before creating the thread)
3290   initialize_class(vmSymbols::java_lang_System(), CHECK);
3291   initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3292   Handle thread_group = create_initial_thread_group(CHECK);
3293   Universe::set_main_thread_group(thread_group());
3294   initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3295   oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3296   main_thread->set_threadObj(thread_object);
3297   // Set thread status to running since main thread has
3298   // been started and running.
3299   java_lang_Thread::set_thread_status(thread_object,
3300                                       java_lang_Thread::RUNNABLE);
3301 
3302   // The VM creates & returns objects of this class. Make sure it's initialized.
3303   initialize_class(vmSymbols::java_lang_Class(), CHECK);
3304 
3305   // The VM preresolves methods to these classes. Make sure that they get initialized
3306   initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3307   initialize_class(vmSymbols::java_lang_ref_Finalizer(),  CHECK);
3308   call_initializeSystemClass(CHECK);
3309 
3310   // get the Java runtime name after java.lang.System is initialized
3311   JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3312   JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3313 
3314   // an instance of OutOfMemory exception has been allocated earlier
3315   initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3316   initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3317   initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3318   initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3319   initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3320   initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3321   initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3322   initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3323 }
3324 
3325 void Threads::initialize_jsr292_core_classes(TRAPS) {
3326   initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3327   initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3328   initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3329 }
3330 
3331 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3332 
3333   extern void JDK_Version_init();
3334 
3335   // Check version
3336   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3337 
3338   // Initialize the output stream module
3339   ostream_init();
3340 
3341   // Process java launcher properties.
3342   Arguments::process_sun_java_launcher_properties(args);
3343 
3344   // Initialize the os module before using TLS
3345   os::init();
3346 
3347   // Initialize system properties.
3348   Arguments::init_system_properties();
3349 
3350   // So that JDK version can be used as a discriminator when parsing arguments
3351   JDK_Version_init();
3352 
3353   // Update/Initialize System properties after JDK version number is known
3354   Arguments::init_version_specific_system_properties();
3355 
3356   // Parse arguments
3357   jint parse_result = Arguments::parse(args);
3358   if (parse_result != JNI_OK) return parse_result;
3359 
3360   os::init_before_ergo();
3361 
3362   jint ergo_result = Arguments::apply_ergo();
3363   if (ergo_result != JNI_OK) return ergo_result;
3364 
3365   if (PauseAtStartup) {
3366     os::pause();
3367   }
3368 
3369   HOTSPOT_VM_INIT_BEGIN();
3370 
3371   // Record VM creation timing statistics
3372   TraceVmCreationTime create_vm_timer;
3373   create_vm_timer.start();
3374 
3375   // Timing (must come after argument parsing)
3376   TraceTime timer("Create VM", TraceStartupTime);
3377 
3378   // Initialize the os module after parsing the args
3379   jint os_init_2_result = os::init_2();
3380   if (os_init_2_result != JNI_OK) return os_init_2_result;
3381 
3382   jint adjust_after_os_result = Arguments::adjust_after_os();
3383   if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3384 
3385   // initialize TLS
3386   ThreadLocalStorage::init();
3387 
3388   // Bootstrap native memory tracking, so it can start recording memory
3389   // activities before worker thread is started. This is the first phase
3390   // of bootstrapping, VM is currently running in single-thread mode.
3391   MemTracker::bootstrap_single_thread();
3392 
3393   // Initialize output stream logging
3394   ostream_init_log();
3395 
3396   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3397   // Must be before create_vm_init_agents()
3398   if (Arguments::init_libraries_at_startup()) {
3399     convert_vm_init_libraries_to_agents();
3400   }
3401 
3402   // Launch -agentlib/-agentpath and converted -Xrun agents
3403   if (Arguments::init_agents_at_startup()) {
3404     create_vm_init_agents();
3405   }
3406 
3407   // Initialize Threads state
3408   _thread_list = NULL;
3409   _number_of_threads = 0;
3410   _number_of_non_daemon_threads = 0;
3411 
3412   // Initialize global data structures and create system classes in heap
3413   vm_init_globals();
3414 
3415   // Attach the main thread to this os thread
3416   JavaThread* main_thread = new JavaThread();
3417   main_thread->set_thread_state(_thread_in_vm);
3418   // must do this before set_active_handles and initialize_thread_local_storage
3419   // Note: on solaris initialize_thread_local_storage() will (indirectly)
3420   // change the stack size recorded here to one based on the java thread
3421   // stacksize. This adjusted size is what is used to figure the placement
3422   // of the guard pages.
3423   main_thread->record_stack_base_and_size();
3424   main_thread->initialize_thread_local_storage();
3425 
3426   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3427 
3428   if (!main_thread->set_as_starting_thread()) {
3429     vm_shutdown_during_initialization(
3430       "Failed necessary internal allocation. Out of swap space");
3431     delete main_thread;
3432     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3433     return JNI_ENOMEM;
3434   }
3435 
3436   // Enable guard page *after* os::create_main_thread(), otherwise it would
3437   // crash Linux VM, see notes in os_linux.cpp.
3438   main_thread->create_stack_guard_pages();
3439 
3440   // Initialize Java-Level synchronization subsystem
3441   ObjectMonitor::Initialize() ;
3442 
3443   // Second phase of bootstrapping, VM is about entering multi-thread mode
3444   MemTracker::bootstrap_multi_thread();
3445 
3446   // Initialize global modules
3447   jint status = init_globals();
3448   if (status != JNI_OK) {
3449     delete main_thread;
3450     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3451     return status;
3452   }
3453 
3454   // Should be done after the heap is fully created
3455   main_thread->cache_global_variables();
3456 
3457   HandleMark hm;
3458 
3459   { MutexLocker mu(Threads_lock);
3460     Threads::add(main_thread);
3461   }
3462 
3463   // Any JVMTI raw monitors entered in onload will transition into
3464   // real raw monitor. VM is setup enough here for raw monitor enter.
3465   JvmtiExport::transition_pending_onload_raw_monitors();
3466 
3467   // Fully start NMT
3468   MemTracker::start();
3469 
3470   // Create the VMThread
3471   { TraceTime timer("Start VMThread", TraceStartupTime);
3472     VMThread::create();
3473     Thread* vmthread = VMThread::vm_thread();
3474 
3475     if (!os::create_thread(vmthread, os::vm_thread))
3476       vm_exit_during_initialization("Cannot create VM thread. Out of system resources.");
3477 
3478     // Wait for the VM thread to become ready, and VMThread::run to initialize
3479     // Monitors can have spurious returns, must always check another state flag
3480     {
3481       MutexLocker ml(Notify_lock);
3482       os::start_thread(vmthread);
3483       while (vmthread->active_handles() == NULL) {
3484         Notify_lock->wait();
3485       }
3486     }
3487   }
3488 
3489   assert (Universe::is_fully_initialized(), "not initialized");
3490   if (VerifyDuringStartup) {
3491     // Make sure we're starting with a clean slate.
3492     VM_Verify verify_op;
3493     VMThread::execute(&verify_op);
3494   }
3495 
3496   Thread* THREAD = Thread::current();
3497 
3498   // At this point, the Universe is initialized, but we have not executed
3499   // any byte code.  Now is a good time (the only time) to dump out the
3500   // internal state of the JVM for sharing.
3501   if (DumpSharedSpaces) {
3502     MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3503     ShouldNotReachHere();
3504   }
3505 
3506   // Always call even when there are not JVMTI environments yet, since environments
3507   // may be attached late and JVMTI must track phases of VM execution
3508   JvmtiExport::enter_start_phase();
3509 
3510   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3511   JvmtiExport::post_vm_start();
3512 
3513   initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3514 
3515   // We need this for ClassDataSharing - the initial vm.info property is set
3516   // with the default value of CDS "sharing" which may be reset through
3517   // command line options.
3518   reset_vm_info_property(CHECK_JNI_ERR);
3519 
3520   quicken_jni_functions();
3521 
3522   // Must be run after init_ft which initializes ft_enabled
3523   if (TRACE_INITIALIZE() != JNI_OK) {
3524     vm_exit_during_initialization("Failed to initialize tracing backend");
3525   }
3526 
3527   // Set flag that basic initialization has completed. Used by exceptions and various
3528   // debug stuff, that does not work until all basic classes have been initialized.
3529   set_init_completed();
3530 
3531   HOTSPOT_VM_INIT_END();
3532 
3533   // record VM initialization completion time
3534 #if INCLUDE_MANAGEMENT
3535   Management::record_vm_init_completed();
3536 #endif // INCLUDE_MANAGEMENT
3537 
3538   // Compute system loader. Note that this has to occur after set_init_completed, since
3539   // valid exceptions may be thrown in the process.
3540   // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
3541   // set_init_completed has just been called, causing exceptions not to be shortcut
3542   // anymore. We call vm_exit_during_initialization directly instead.
3543   SystemDictionary::compute_java_system_loader(CHECK_JNI_ERR);
3544 
3545 #if INCLUDE_ALL_GCS
3546   // Support for ConcurrentMarkSweep. This should be cleaned up
3547   // and better encapsulated. The ugly nested if test would go away
3548   // once things are properly refactored. XXX YSR
3549   if (UseConcMarkSweepGC || UseG1GC) {
3550     if (UseConcMarkSweepGC) {
3551       ConcurrentMarkSweepThread::makeSurrogateLockerThread(CHECK_JNI_ERR);
3552     } else {
3553       ConcurrentMarkThread::makeSurrogateLockerThread(CHECK_JNI_ERR);
3554     }
3555   }
3556 #endif // INCLUDE_ALL_GCS
3557 
3558   // Always call even when there are not JVMTI environments yet, since environments
3559   // may be attached late and JVMTI must track phases of VM execution
3560   JvmtiExport::enter_live_phase();
3561 
3562   // Signal Dispatcher needs to be started before VMInit event is posted
3563   os::signal_init();
3564 
3565   // Start Attach Listener if +StartAttachListener or it can't be started lazily
3566   if (!DisableAttachMechanism) {
3567     AttachListener::vm_start();
3568     if (StartAttachListener || AttachListener::init_at_startup()) {
3569       AttachListener::init();
3570     }
3571   }
3572 
3573   // Launch -Xrun agents
3574   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3575   // back-end can launch with -Xdebug -Xrunjdwp.
3576   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3577     create_vm_init_libraries();
3578   }
3579 
3580   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3581   JvmtiExport::post_vm_initialized();
3582 
3583   if (TRACE_START() != JNI_OK) {
3584     vm_exit_during_initialization("Failed to start tracing backend.");
3585   }
3586 
3587   if (CleanChunkPoolAsync) {
3588     Chunk::start_chunk_pool_cleaner_task();
3589   }
3590 
3591   // initialize compiler(s)
3592 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK)
3593   CompileBroker::compilation_init();
3594 #endif
3595 
3596   // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3597   // It is done after compilers are initialized, because otherwise compilations of
3598   // signature polymorphic MH intrinsics can be missed
3599   // (see SystemDictionary::find_method_handle_intrinsic).
3600   if (EnableInvokeDynamic) {
3601     initialize_jsr292_core_classes(CHECK_JNI_ERR);
3602   }
3603 
3604 #if INCLUDE_MANAGEMENT
3605   Management::initialize(THREAD);
3606 
3607   if (HAS_PENDING_EXCEPTION) {
3608     // management agent fails to start possibly due to
3609     // configuration problem and is responsible for printing
3610     // stack trace if appropriate. Simply exit VM.
3611     vm_exit(1);
3612   }
3613 #endif // INCLUDE_MANAGEMENT
3614 
3615   if (Arguments::has_profile())       FlatProfiler::engage(main_thread, true);
3616   if (MemProfiling)                   MemProfiler::engage();
3617   StatSampler::engage();
3618   if (CheckJNICalls)                  JniPeriodicChecker::engage();
3619 
3620   BiasedLocking::init();
3621 
3622   if (JDK_Version::current().post_vm_init_hook_enabled()) {
3623     call_postVMInitHook(THREAD);
3624     // The Java side of PostVMInitHook.run must deal with all
3625     // exceptions and provide means of diagnosis.
3626     if (HAS_PENDING_EXCEPTION) {
3627       CLEAR_PENDING_EXCEPTION;
3628     }
3629   }
3630 
3631   {
3632       MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
3633       // Make sure the watcher thread can be started by WatcherThread::start()
3634       // or by dynamic enrollment.
3635       WatcherThread::make_startable();
3636       // Start up the WatcherThread if there are any periodic tasks
3637       // NOTE:  All PeriodicTasks should be registered by now. If they
3638       //   aren't, late joiners might appear to start slowly (we might
3639       //   take a while to process their first tick).
3640       if (PeriodicTask::num_tasks() > 0) {
3641           WatcherThread::start();
3642       }
3643   }
3644 
3645   // Give os specific code one last chance to start
3646   os::init_3();
3647 
3648   create_vm_timer.end();
3649 #ifdef ASSERT
3650   _vm_complete = true;
3651 #endif
3652   return JNI_OK;
3653 }
3654 
3655 // type for the Agent_OnLoad and JVM_OnLoad entry points
3656 extern "C" {
3657   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3658 }
3659 // Find a command line agent library and return its entry point for
3660 //         -agentlib:  -agentpath:   -Xrun
3661 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3662 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, const char *on_load_symbols[], size_t num_symbol_entries) {
3663   OnLoadEntry_t on_load_entry = NULL;
3664   void *library = NULL;
3665 
3666   if (!agent->valid()) {
3667     char buffer[JVM_MAXPATHLEN];
3668     char ebuf[1024];
3669     const char *name = agent->name();
3670     const char *msg = "Could not find agent library ";
3671 
3672     // First check to see if agent is statically linked into executable
3673     if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3674       library = agent->os_lib();
3675     } else if (agent->is_absolute_path()) {
3676       library = os::dll_load(name, ebuf, sizeof ebuf);
3677       if (library == NULL) {
3678         const char *sub_msg = " in absolute path, with error: ";
3679         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3680         char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3681         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3682         // If we can't find the agent, exit.
3683         vm_exit_during_initialization(buf, NULL);
3684         FREE_C_HEAP_ARRAY(char, buf, mtThread);
3685       }
3686     } else {
3687       // Try to load the agent from the standard dll directory
3688       if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3689                              name)) {
3690         library = os::dll_load(buffer, ebuf, sizeof ebuf);
3691       }
3692       if (library == NULL) { // Try the local directory
3693         char ns[1] = {0};
3694         if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3695           library = os::dll_load(buffer, ebuf, sizeof ebuf);
3696         }
3697         if (library == NULL) {
3698           const char *sub_msg = " on the library path, with error: ";
3699           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3700           char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3701           jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3702           // If we can't find the agent, exit.
3703           vm_exit_during_initialization(buf, NULL);
3704           FREE_C_HEAP_ARRAY(char, buf, mtThread);
3705         }
3706       }
3707     }
3708     agent->set_os_lib(library);
3709     agent->set_valid();
3710   }
3711 
3712   // Find the OnLoad function.
3713   on_load_entry =
3714     CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3715                                                           false,
3716                                                           on_load_symbols,
3717                                                           num_symbol_entries));
3718   return on_load_entry;
3719 }
3720 
3721 // Find the JVM_OnLoad entry point
3722 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3723   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3724   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3725 }
3726 
3727 // Find the Agent_OnLoad entry point
3728 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3729   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3730   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3731 }
3732 
3733 // For backwards compatibility with -Xrun
3734 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3735 // treated like -agentpath:
3736 // Must be called before agent libraries are created
3737 void Threads::convert_vm_init_libraries_to_agents() {
3738   AgentLibrary* agent;
3739   AgentLibrary* next;
3740 
3741   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3742     next = agent->next();  // cache the next agent now as this agent may get moved off this list
3743     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3744 
3745     // If there is an JVM_OnLoad function it will get called later,
3746     // otherwise see if there is an Agent_OnLoad
3747     if (on_load_entry == NULL) {
3748       on_load_entry = lookup_agent_on_load(agent);
3749       if (on_load_entry != NULL) {
3750         // switch it to the agent list -- so that Agent_OnLoad will be called,
3751         // JVM_OnLoad won't be attempted and Agent_OnUnload will
3752         Arguments::convert_library_to_agent(agent);
3753       } else {
3754         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3755       }
3756     }
3757   }
3758 }
3759 
3760 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
3761 // Invokes Agent_OnLoad
3762 // Called very early -- before JavaThreads exist
3763 void Threads::create_vm_init_agents() {
3764   extern struct JavaVM_ main_vm;
3765   AgentLibrary* agent;
3766 
3767   JvmtiExport::enter_onload_phase();
3768 
3769   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3770     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
3771 
3772     if (on_load_entry != NULL) {
3773       // Invoke the Agent_OnLoad function
3774       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3775       if (err != JNI_OK) {
3776         vm_exit_during_initialization("agent library failed to init", agent->name());
3777       }
3778     } else {
3779       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3780     }
3781   }
3782   JvmtiExport::enter_primordial_phase();
3783 }
3784 
3785 extern "C" {
3786   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3787 }
3788 
3789 void Threads::shutdown_vm_agents() {
3790   // Send any Agent_OnUnload notifications
3791   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3792   size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
3793   extern struct JavaVM_ main_vm;
3794   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3795 
3796     // Find the Agent_OnUnload function.
3797     Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3798       os::find_agent_function(agent,
3799       false,
3800       on_unload_symbols,
3801       num_symbol_entries));
3802 
3803     // Invoke the Agent_OnUnload function
3804     if (unload_entry != NULL) {
3805       JavaThread* thread = JavaThread::current();
3806       ThreadToNativeFromVM ttn(thread);
3807       HandleMark hm(thread);
3808       (*unload_entry)(&main_vm);
3809     }
3810   }
3811 }
3812 
3813 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
3814 // Invokes JVM_OnLoad
3815 void Threads::create_vm_init_libraries() {
3816   extern struct JavaVM_ main_vm;
3817   AgentLibrary* agent;
3818 
3819   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
3820     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3821 
3822     if (on_load_entry != NULL) {
3823       // Invoke the JVM_OnLoad function
3824       JavaThread* thread = JavaThread::current();
3825       ThreadToNativeFromVM ttn(thread);
3826       HandleMark hm(thread);
3827       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3828       if (err != JNI_OK) {
3829         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
3830       }
3831     } else {
3832       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
3833     }
3834   }
3835 }
3836 
3837 // Last thread running calls java.lang.Shutdown.shutdown()
3838 void JavaThread::invoke_shutdown_hooks() {
3839   HandleMark hm(this);
3840 
3841   // We could get here with a pending exception, if so clear it now.
3842   if (this->has_pending_exception()) {
3843     this->clear_pending_exception();
3844   }
3845 
3846   EXCEPTION_MARK;
3847   Klass* k =
3848     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
3849                                       THREAD);
3850   if (k != NULL) {
3851     // SystemDictionary::resolve_or_null will return null if there was
3852     // an exception.  If we cannot load the Shutdown class, just don't
3853     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
3854     // and finalizers (if runFinalizersOnExit is set) won't be run.
3855     // Note that if a shutdown hook was registered or runFinalizersOnExit
3856     // was called, the Shutdown class would have already been loaded
3857     // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
3858     instanceKlassHandle shutdown_klass (THREAD, k);
3859     JavaValue result(T_VOID);
3860     JavaCalls::call_static(&result,
3861                            shutdown_klass,
3862                            vmSymbols::shutdown_method_name(),
3863                            vmSymbols::void_method_signature(),
3864                            THREAD);
3865   }
3866   CLEAR_PENDING_EXCEPTION;
3867 }
3868 
3869 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
3870 // the program falls off the end of main(). Another VM exit path is through
3871 // vm_exit() when the program calls System.exit() to return a value or when
3872 // there is a serious error in VM. The two shutdown paths are not exactly
3873 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
3874 // and VM_Exit op at VM level.
3875 //
3876 // Shutdown sequence:
3877 //   + Shutdown native memory tracking if it is on
3878 //   + Wait until we are the last non-daemon thread to execute
3879 //     <-- every thing is still working at this moment -->
3880 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
3881 //        shutdown hooks, run finalizers if finalization-on-exit
3882 //   + Call before_exit(), prepare for VM exit
3883 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
3884 //        currently the only user of this mechanism is File.deleteOnExit())
3885 //      > stop flat profiler, StatSampler, watcher thread, CMS threads,
3886 //        post thread end and vm death events to JVMTI,
3887 //        stop signal thread
3888 //   + Call JavaThread::exit(), it will:
3889 //      > release JNI handle blocks, remove stack guard pages
3890 //      > remove this thread from Threads list
3891 //     <-- no more Java code from this thread after this point -->
3892 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
3893 //     the compiler threads at safepoint
3894 //     <-- do not use anything that could get blocked by Safepoint -->
3895 //   + Disable tracing at JNI/JVM barriers
3896 //   + Set _vm_exited flag for threads that are still running native code
3897 //   + Delete this thread
3898 //   + Call exit_globals()
3899 //      > deletes tty
3900 //      > deletes PerfMemory resources
3901 //   + Return to caller
3902 
3903 bool Threads::destroy_vm() {
3904   JavaThread* thread = JavaThread::current();
3905 
3906 #ifdef ASSERT
3907   _vm_complete = false;
3908 #endif
3909   // Wait until we are the last non-daemon thread to execute
3910   { MutexLocker nu(Threads_lock);
3911     while (Threads::number_of_non_daemon_threads() > 1 )
3912       // This wait should make safepoint checks, wait without a timeout,
3913       // and wait as a suspend-equivalent condition.
3914       //
3915       // Note: If the FlatProfiler is running and this thread is waiting
3916       // for another non-daemon thread to finish, then the FlatProfiler
3917       // is waiting for the external suspend request on this thread to
3918       // complete. wait_for_ext_suspend_completion() will eventually
3919       // timeout, but that takes time. Making this wait a suspend-
3920       // equivalent condition solves that timeout problem.
3921       //
3922       Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
3923                          Mutex::_as_suspend_equivalent_flag);
3924   }
3925 
3926   // Hang forever on exit if we are reporting an error.
3927   if (ShowMessageBoxOnError && is_error_reported()) {
3928     os::infinite_sleep();
3929   }
3930   os::wait_for_keypress_at_exit();
3931 
3932   if (JDK_Version::is_jdk12x_version()) {
3933     // We are the last thread running, so check if finalizers should be run.
3934     // For 1.3 or later this is done in thread->invoke_shutdown_hooks()
3935     HandleMark rm(thread);
3936     Universe::run_finalizers_on_exit();
3937   } else {
3938     // run Java level shutdown hooks
3939     thread->invoke_shutdown_hooks();
3940   }
3941 
3942   before_exit(thread);
3943 
3944   thread->exit(true);
3945 
3946   // Stop VM thread.
3947   {
3948     // 4945125 The vm thread comes to a safepoint during exit.
3949     // GC vm_operations can get caught at the safepoint, and the
3950     // heap is unparseable if they are caught. Grab the Heap_lock
3951     // to prevent this. The GC vm_operations will not be able to
3952     // queue until after the vm thread is dead.
3953     // After this point, we'll never emerge out of the safepoint before
3954     // the VM exits, so concurrent GC threads do not need to be explicitly
3955     // stopped; they remain inactive until the process exits.
3956     // Note: some concurrent G1 threads may be running during a safepoint,
3957     // but these will not be accessing the heap, just some G1-specific side
3958     // data structures that are not accessed by any other threads but them
3959     // after this point in a terminal safepoint.
3960 
3961     MutexLocker ml(Heap_lock);
3962 
3963     VMThread::wait_for_vm_thread_exit();
3964     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
3965     VMThread::destroy();
3966   }
3967 
3968   // clean up ideal graph printers
3969 #if defined(COMPILER2) && !defined(PRODUCT)
3970   IdealGraphPrinter::clean_up();
3971 #endif
3972 
3973   // Now, all Java threads are gone except daemon threads. Daemon threads
3974   // running Java code or in VM are stopped by the Safepoint. However,
3975   // daemon threads executing native code are still running.  But they
3976   // will be stopped at native=>Java/VM barriers. Note that we can't
3977   // simply kill or suspend them, as it is inherently deadlock-prone.
3978 
3979 #ifndef PRODUCT
3980   // disable function tracing at JNI/JVM barriers
3981   TraceJNICalls = false;
3982   TraceJVMCalls = false;
3983   TraceRuntimeCalls = false;
3984 #endif
3985 
3986   VM_Exit::set_vm_exited();
3987 
3988   notify_vm_shutdown();
3989 
3990   delete thread;
3991 
3992   // exit_globals() will delete tty
3993   exit_globals();
3994 
3995   return true;
3996 }
3997 
3998 
3999 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4000   if (version == JNI_VERSION_1_1) return JNI_TRUE;
4001   return is_supported_jni_version(version);
4002 }
4003 
4004 
4005 jboolean Threads::is_supported_jni_version(jint version) {
4006   if (version == JNI_VERSION_1_2) return JNI_TRUE;
4007   if (version == JNI_VERSION_1_4) return JNI_TRUE;
4008   if (version == JNI_VERSION_1_6) return JNI_TRUE;
4009   if (version == JNI_VERSION_1_8) return JNI_TRUE;
4010   return JNI_FALSE;
4011 }
4012 
4013 
4014 void Threads::add(JavaThread* p, bool force_daemon) {
4015   // The threads lock must be owned at this point
4016   assert_locked_or_safepoint(Threads_lock);
4017 
4018   // See the comment for this method in thread.hpp for its purpose and
4019   // why it is called here.
4020   p->initialize_queues();
4021   p->set_next(_thread_list);
4022   _thread_list = p;
4023   _number_of_threads++;
4024   oop threadObj = p->threadObj();
4025   bool daemon = true;
4026   // Bootstrapping problem: threadObj can be null for initial
4027   // JavaThread (or for threads attached via JNI)
4028   if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4029     _number_of_non_daemon_threads++;
4030     daemon = false;
4031   }
4032 
4033   p->set_safepoint_visible(true);
4034 
4035   ThreadService::add_thread(p, daemon);
4036 
4037   // Possible GC point.
4038   Events::log(p, "Thread added: " INTPTR_FORMAT, p);
4039 }
4040 
4041 void Threads::remove(JavaThread* p) {
4042   // Extra scope needed for Thread_lock, so we can check
4043   // that we do not remove thread without safepoint code notice
4044   { MutexLocker ml(Threads_lock);
4045 
4046     assert(includes(p), "p must be present");
4047 
4048     JavaThread* current = _thread_list;
4049     JavaThread* prev    = NULL;
4050 
4051     while (current != p) {
4052       prev    = current;
4053       current = current->next();
4054     }
4055 
4056     if (prev) {
4057       prev->set_next(current->next());
4058     } else {
4059       _thread_list = p->next();
4060     }
4061     _number_of_threads--;
4062     oop threadObj = p->threadObj();
4063     bool daemon = true;
4064     if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4065       _number_of_non_daemon_threads--;
4066       daemon = false;
4067 
4068       // Only one thread left, do a notify on the Threads_lock so a thread waiting
4069       // on destroy_vm will wake up.
4070       if (number_of_non_daemon_threads() == 1)
4071         Threads_lock->notify_all();
4072     }
4073     ThreadService::remove_thread(p, daemon);
4074 
4075     // Make sure that safepoint code disregard this thread. This is needed since
4076     // the thread might mess around with locks after this point. This can cause it
4077     // to do callbacks into the safepoint code. However, the safepoint code is not aware
4078     // of this thread since it is removed from the queue.
4079     p->set_terminated_value();
4080 
4081     // Now, this thread is not visible to safepoint
4082     p->set_safepoint_visible(false);
4083     // once the thread becomes safepoint invisible, we can not use its per-thread
4084     // recorder. And Threads::do_threads() no longer walks this thread, so we have
4085     // to release its per-thread recorder here.
4086     MemTracker::thread_exiting(p);
4087   } // unlock Threads_lock
4088 
4089   // Since Events::log uses a lock, we grab it outside the Threads_lock
4090   Events::log(p, "Thread exited: " INTPTR_FORMAT, p);
4091 }
4092 
4093 // Threads_lock must be held when this is called (or must be called during a safepoint)
4094 bool Threads::includes(JavaThread* p) {
4095   assert(Threads_lock->is_locked(), "sanity check");
4096   ALL_JAVA_THREADS(q) {
4097     if (q == p ) {
4098       return true;
4099     }
4100   }
4101   return false;
4102 }
4103 
4104 // Operations on the Threads list for GC.  These are not explicitly locked,
4105 // but the garbage collector must provide a safe context for them to run.
4106 // In particular, these things should never be called when the Threads_lock
4107 // is held by some other thread. (Note: the Safepoint abstraction also
4108 // uses the Threads_lock to guarantee this property. It also makes sure that
4109 // all threads gets blocked when exiting or starting).
4110 
4111 void Threads::oops_do(OopClosure* f, CLDToOopClosure* cld_f, CodeBlobClosure* cf) {
4112   ALL_JAVA_THREADS(p) {
4113     p->oops_do(f, cld_f, cf);
4114   }
4115   VMThread::vm_thread()->oops_do(f, cld_f, cf);
4116 }
4117 
4118 void Threads::possibly_parallel_oops_do(OopClosure* f, CLDToOopClosure* cld_f, CodeBlobClosure* cf) {
4119   // Introduce a mechanism allowing parallel threads to claim threads as
4120   // root groups.  Overhead should be small enough to use all the time,
4121   // even in sequential code.
4122   SharedHeap* sh = SharedHeap::heap();
4123   // Cannot yet substitute active_workers for n_par_threads
4124   // because of G1CollectedHeap::verify() use of
4125   // SharedHeap::process_strong_roots().  n_par_threads == 0 will
4126   // turn off parallelism in process_strong_roots while active_workers
4127   // is being used for parallelism elsewhere.
4128   bool is_par = sh->n_par_threads() > 0;
4129   assert(!is_par ||
4130          (SharedHeap::heap()->n_par_threads() ==
4131           SharedHeap::heap()->workers()->active_workers()), "Mismatch");
4132   int cp = SharedHeap::heap()->strong_roots_parity();
4133   ALL_JAVA_THREADS(p) {
4134     if (p->claim_oops_do(is_par, cp)) {
4135       p->oops_do(f, cld_f, cf);
4136     }
4137   }
4138   VMThread* vmt = VMThread::vm_thread();
4139   if (vmt->claim_oops_do(is_par, cp)) {
4140     vmt->oops_do(f, cld_f, cf);
4141   }
4142 }
4143 
4144 #if INCLUDE_ALL_GCS
4145 // Used by ParallelScavenge
4146 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4147   ALL_JAVA_THREADS(p) {
4148     q->enqueue(new ThreadRootsTask(p));
4149   }
4150   q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4151 }
4152 
4153 // Used by Parallel Old
4154 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4155   ALL_JAVA_THREADS(p) {
4156     q->enqueue(new ThreadRootsMarkingTask(p));
4157   }
4158   q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4159 }
4160 #endif // INCLUDE_ALL_GCS
4161 
4162 void Threads::nmethods_do(CodeBlobClosure* cf) {
4163   ALL_JAVA_THREADS(p) {
4164     p->nmethods_do(cf);
4165   }
4166   VMThread::vm_thread()->nmethods_do(cf);
4167 }
4168 
4169 void Threads::metadata_do(void f(Metadata*)) {
4170   ALL_JAVA_THREADS(p) {
4171     p->metadata_do(f);
4172   }
4173 }
4174 
4175 void Threads::gc_epilogue() {
4176   ALL_JAVA_THREADS(p) {
4177     p->gc_epilogue();
4178   }
4179 }
4180 
4181 void Threads::gc_prologue() {
4182   ALL_JAVA_THREADS(p) {
4183     p->gc_prologue();
4184   }
4185 }
4186 
4187 void Threads::deoptimized_wrt_marked_nmethods() {
4188   ALL_JAVA_THREADS(p) {
4189     p->deoptimized_wrt_marked_nmethods();
4190   }
4191 }
4192 
4193 
4194 // Get count Java threads that are waiting to enter the specified monitor.
4195 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4196   address monitor, bool doLock) {
4197   assert(doLock || SafepointSynchronize::is_at_safepoint(),
4198     "must grab Threads_lock or be at safepoint");
4199   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4200 
4201   int i = 0;
4202   {
4203     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4204     ALL_JAVA_THREADS(p) {
4205       if (p->is_Compiler_thread()) continue;
4206 
4207       address pending = (address)p->current_pending_monitor();
4208       if (pending == monitor) {             // found a match
4209         if (i < count) result->append(p);   // save the first count matches
4210         i++;
4211       }
4212     }
4213   }
4214   return result;
4215 }
4216 
4217 
4218 JavaThread *Threads::owning_thread_from_monitor_owner(address owner, bool doLock) {
4219   assert(doLock ||
4220          Threads_lock->owned_by_self() ||
4221          SafepointSynchronize::is_at_safepoint(),
4222          "must grab Threads_lock or be at safepoint");
4223 
4224   // NULL owner means not locked so we can skip the search
4225   if (owner == NULL) return NULL;
4226 
4227   {
4228     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4229     ALL_JAVA_THREADS(p) {
4230       // first, see if owner is the address of a Java thread
4231       if (owner == (address)p) return p;
4232     }
4233   }
4234   // Cannot assert on lack of success here since this function may be
4235   // used by code that is trying to report useful problem information
4236   // like deadlock detection.
4237   if (UseHeavyMonitors) return NULL;
4238 
4239   //
4240   // If we didn't find a matching Java thread and we didn't force use of
4241   // heavyweight monitors, then the owner is the stack address of the
4242   // Lock Word in the owning Java thread's stack.
4243   //
4244   JavaThread* the_owner = NULL;
4245   {
4246     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4247     ALL_JAVA_THREADS(q) {
4248       if (q->is_lock_owned(owner)) {
4249         the_owner = q;
4250         break;
4251       }
4252     }
4253   }
4254   // cannot assert on lack of success here; see above comment
4255   return the_owner;
4256 }
4257 
4258 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4259 void Threads::print_on(outputStream* st, bool print_stacks, bool internal_format, bool print_concurrent_locks) {
4260   char buf[32];
4261   st->print_cr(os::local_time_string(buf, sizeof(buf)));
4262 
4263   st->print_cr("Full thread dump %s (%s %s):",
4264                 Abstract_VM_Version::vm_name(),
4265                 Abstract_VM_Version::vm_release(),
4266                 Abstract_VM_Version::vm_info_string()
4267                );
4268   st->cr();
4269 
4270 #if INCLUDE_ALL_GCS
4271   // Dump concurrent locks
4272   ConcurrentLocksDump concurrent_locks;
4273   if (print_concurrent_locks) {
4274     concurrent_locks.dump_at_safepoint();
4275   }
4276 #endif // INCLUDE_ALL_GCS
4277 
4278   ALL_JAVA_THREADS(p) {
4279     ResourceMark rm;
4280     p->print_on(st);
4281     if (print_stacks) {
4282       if (internal_format) {
4283         p->trace_stack();
4284       } else {
4285         p->print_stack_on(st);
4286       }
4287     }
4288     st->cr();
4289 #if INCLUDE_ALL_GCS
4290     if (print_concurrent_locks) {
4291       concurrent_locks.print_locks_on(p, st);
4292     }
4293 #endif // INCLUDE_ALL_GCS
4294   }
4295 
4296   VMThread::vm_thread()->print_on(st);
4297   st->cr();
4298   Universe::heap()->print_gc_threads_on(st);
4299   WatcherThread* wt = WatcherThread::watcher_thread();
4300   if (wt != NULL) {
4301     wt->print_on(st);
4302     st->cr();
4303   }
4304   CompileBroker::print_compiler_threads_on(st);
4305   st->flush();
4306 }
4307 
4308 // Threads::print_on_error() is called by fatal error handler. It's possible
4309 // that VM is not at safepoint and/or current thread is inside signal handler.
4310 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4311 // memory (even in resource area), it might deadlock the error handler.
4312 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, int buflen) {
4313   bool found_current = false;
4314   st->print_cr("Java Threads: ( => current thread )");
4315   ALL_JAVA_THREADS(thread) {
4316     bool is_current = (current == thread);
4317     found_current = found_current || is_current;
4318 
4319     st->print("%s", is_current ? "=>" : "  ");
4320 
4321     st->print(PTR_FORMAT, thread);
4322     st->print(" ");
4323     thread->print_on_error(st, buf, buflen);
4324     st->cr();
4325   }
4326   st->cr();
4327 
4328   st->print_cr("Other Threads:");
4329   if (VMThread::vm_thread()) {
4330     bool is_current = (current == VMThread::vm_thread());
4331     found_current = found_current || is_current;
4332     st->print("%s", current == VMThread::vm_thread() ? "=>" : "  ");
4333 
4334     st->print(PTR_FORMAT, VMThread::vm_thread());
4335     st->print(" ");
4336     VMThread::vm_thread()->print_on_error(st, buf, buflen);
4337     st->cr();
4338   }
4339   WatcherThread* wt = WatcherThread::watcher_thread();
4340   if (wt != NULL) {
4341     bool is_current = (current == wt);
4342     found_current = found_current || is_current;
4343     st->print("%s", is_current ? "=>" : "  ");
4344 
4345     st->print(PTR_FORMAT, wt);
4346     st->print(" ");
4347     wt->print_on_error(st, buf, buflen);
4348     st->cr();
4349   }
4350   if (!found_current) {
4351     st->cr();
4352     st->print("=>" PTR_FORMAT " (exited) ", current);
4353     current->print_on_error(st, buf, buflen);
4354     st->cr();
4355   }
4356 }
4357 
4358 // Internal SpinLock and Mutex
4359 // Based on ParkEvent
4360 
4361 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4362 //
4363 // We employ SpinLocks _only for low-contention, fixed-length
4364 // short-duration critical sections where we're concerned
4365 // about native mutex_t or HotSpot Mutex:: latency.
4366 // The mux construct provides a spin-then-block mutual exclusion
4367 // mechanism.
4368 //
4369 // Testing has shown that contention on the ListLock guarding gFreeList
4370 // is common.  If we implement ListLock as a simple SpinLock it's common
4371 // for the JVM to devolve to yielding with little progress.  This is true
4372 // despite the fact that the critical sections protected by ListLock are
4373 // extremely short.
4374 //
4375 // TODO-FIXME: ListLock should be of type SpinLock.
4376 // We should make this a 1st-class type, integrated into the lock
4377 // hierarchy as leaf-locks.  Critically, the SpinLock structure
4378 // should have sufficient padding to avoid false-sharing and excessive
4379 // cache-coherency traffic.
4380 
4381 
4382 typedef volatile int SpinLockT ;
4383 
4384 void Thread::SpinAcquire (volatile int * adr, const char * LockName) {
4385   if (Atomic::cmpxchg (1, adr, 0) == 0) {
4386      return ;   // normal fast-path return
4387   }
4388 
4389   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4390   TEVENT (SpinAcquire - ctx) ;
4391   int ctr = 0 ;
4392   int Yields = 0 ;
4393   for (;;) {
4394      while (*adr != 0) {
4395         ++ctr ;
4396         if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4397            if (Yields > 5) {
4398              os::naked_short_sleep(1);
4399            } else {
4400              os::NakedYield() ;
4401              ++Yields ;
4402            }
4403         } else {
4404            SpinPause() ;
4405         }
4406      }
4407      if (Atomic::cmpxchg (1, adr, 0) == 0) return ;
4408   }
4409 }
4410 
4411 void Thread::SpinRelease (volatile int * adr) {
4412   assert (*adr != 0, "invariant") ;
4413   OrderAccess::fence() ;      // guarantee at least release consistency.
4414   // Roach-motel semantics.
4415   // It's safe if subsequent LDs and STs float "up" into the critical section,
4416   // but prior LDs and STs within the critical section can't be allowed
4417   // to reorder or float past the ST that releases the lock.
4418   *adr = 0 ;
4419 }
4420 
4421 // muxAcquire and muxRelease:
4422 //
4423 // *  muxAcquire and muxRelease support a single-word lock-word construct.
4424 //    The LSB of the word is set IFF the lock is held.
4425 //    The remainder of the word points to the head of a singly-linked list
4426 //    of threads blocked on the lock.
4427 //
4428 // *  The current implementation of muxAcquire-muxRelease uses its own
4429 //    dedicated Thread._MuxEvent instance.  If we're interested in
4430 //    minimizing the peak number of extant ParkEvent instances then
4431 //    we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4432 //    as certain invariants were satisfied.  Specifically, care would need
4433 //    to be taken with regards to consuming unpark() "permits".
4434 //    A safe rule of thumb is that a thread would never call muxAcquire()
4435 //    if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4436 //    park().  Otherwise the _ParkEvent park() operation in muxAcquire() could
4437 //    consume an unpark() permit intended for monitorenter, for instance.
4438 //    One way around this would be to widen the restricted-range semaphore
4439 //    implemented in park().  Another alternative would be to provide
4440 //    multiple instances of the PlatformEvent() for each thread.  One
4441 //    instance would be dedicated to muxAcquire-muxRelease, for instance.
4442 //
4443 // *  Usage:
4444 //    -- Only as leaf locks
4445 //    -- for short-term locking only as muxAcquire does not perform
4446 //       thread state transitions.
4447 //
4448 // Alternatives:
4449 // *  We could implement muxAcquire and muxRelease with MCS or CLH locks
4450 //    but with parking or spin-then-park instead of pure spinning.
4451 // *  Use Taura-Oyama-Yonenzawa locks.
4452 // *  It's possible to construct a 1-0 lock if we encode the lockword as
4453 //    (List,LockByte).  Acquire will CAS the full lockword while Release
4454 //    will STB 0 into the LockByte.  The 1-0 scheme admits stranding, so
4455 //    acquiring threads use timers (ParkTimed) to detect and recover from
4456 //    the stranding window.  Thread/Node structures must be aligned on 256-byte
4457 //    boundaries by using placement-new.
4458 // *  Augment MCS with advisory back-link fields maintained with CAS().
4459 //    Pictorially:  LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4460 //    The validity of the backlinks must be ratified before we trust the value.
4461 //    If the backlinks are invalid the exiting thread must back-track through the
4462 //    the forward links, which are always trustworthy.
4463 // *  Add a successor indication.  The LockWord is currently encoded as
4464 //    (List, LOCKBIT:1).  We could also add a SUCCBIT or an explicit _succ variable
4465 //    to provide the usual futile-wakeup optimization.
4466 //    See RTStt for details.
4467 // *  Consider schedctl.sc_nopreempt to cover the critical section.
4468 //
4469 
4470 
4471 typedef volatile intptr_t MutexT ;      // Mux Lock-word
4472 enum MuxBits { LOCKBIT = 1 } ;
4473 
4474 void Thread::muxAcquire (volatile intptr_t * Lock, const char * LockName) {
4475   intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ;
4476   if (w == 0) return ;
4477   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4478      return ;
4479   }
4480 
4481   TEVENT (muxAcquire - Contention) ;
4482   ParkEvent * const Self = Thread::current()->_MuxEvent ;
4483   assert ((intptr_t(Self) & LOCKBIT) == 0, "invariant") ;
4484   for (;;) {
4485      int its = (os::is_MP() ? 100 : 0) + 1 ;
4486 
4487      // Optional spin phase: spin-then-park strategy
4488      while (--its >= 0) {
4489        w = *Lock ;
4490        if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4491           return ;
4492        }
4493      }
4494 
4495      Self->reset() ;
4496      Self->OnList = intptr_t(Lock) ;
4497      // The following fence() isn't _strictly necessary as the subsequent
4498      // CAS() both serializes execution and ratifies the fetched *Lock value.
4499      OrderAccess::fence();
4500      for (;;) {
4501         w = *Lock ;
4502         if ((w & LOCKBIT) == 0) {
4503             if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4504                 Self->OnList = 0 ;   // hygiene - allows stronger asserts
4505                 return ;
4506             }
4507             continue ;      // Interference -- *Lock changed -- Just retry
4508         }
4509         assert (w & LOCKBIT, "invariant") ;
4510         Self->ListNext = (ParkEvent *) (w & ~LOCKBIT );
4511         if (Atomic::cmpxchg_ptr (intptr_t(Self)|LOCKBIT, Lock, w) == w) break ;
4512      }
4513 
4514      while (Self->OnList != 0) {
4515         Self->park() ;
4516      }
4517   }
4518 }
4519 
4520 void Thread::muxAcquireW (volatile intptr_t * Lock, ParkEvent * ev) {
4521   intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ;
4522   if (w == 0) return ;
4523   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4524     return ;
4525   }
4526 
4527   TEVENT (muxAcquire - Contention) ;
4528   ParkEvent * ReleaseAfter = NULL ;
4529   if (ev == NULL) {
4530     ev = ReleaseAfter = ParkEvent::Allocate (NULL) ;
4531   }
4532   assert ((intptr_t(ev) & LOCKBIT) == 0, "invariant") ;
4533   for (;;) {
4534     guarantee (ev->OnList == 0, "invariant") ;
4535     int its = (os::is_MP() ? 100 : 0) + 1 ;
4536 
4537     // Optional spin phase: spin-then-park strategy
4538     while (--its >= 0) {
4539       w = *Lock ;
4540       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4541         if (ReleaseAfter != NULL) {
4542           ParkEvent::Release (ReleaseAfter) ;
4543         }
4544         return ;
4545       }
4546     }
4547 
4548     ev->reset() ;
4549     ev->OnList = intptr_t(Lock) ;
4550     // The following fence() isn't _strictly necessary as the subsequent
4551     // CAS() both serializes execution and ratifies the fetched *Lock value.
4552     OrderAccess::fence();
4553     for (;;) {
4554       w = *Lock ;
4555       if ((w & LOCKBIT) == 0) {
4556         if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4557           ev->OnList = 0 ;
4558           // We call ::Release while holding the outer lock, thus
4559           // artificially lengthening the critical section.
4560           // Consider deferring the ::Release() until the subsequent unlock(),
4561           // after we've dropped the outer lock.
4562           if (ReleaseAfter != NULL) {
4563             ParkEvent::Release (ReleaseAfter) ;
4564           }
4565           return ;
4566         }
4567         continue ;      // Interference -- *Lock changed -- Just retry
4568       }
4569       assert (w & LOCKBIT, "invariant") ;
4570       ev->ListNext = (ParkEvent *) (w & ~LOCKBIT );
4571       if (Atomic::cmpxchg_ptr (intptr_t(ev)|LOCKBIT, Lock, w) == w) break ;
4572     }
4573 
4574     while (ev->OnList != 0) {
4575       ev->park() ;
4576     }
4577   }
4578 }
4579 
4580 // Release() must extract a successor from the list and then wake that thread.
4581 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4582 // similar to that used by ParkEvent::Allocate() and ::Release().  DMR-based
4583 // Release() would :
4584 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4585 // (B) Extract a successor from the private list "in-hand"
4586 // (C) attempt to CAS() the residual back into *Lock over null.
4587 //     If there were any newly arrived threads and the CAS() would fail.
4588 //     In that case Release() would detach the RATs, re-merge the list in-hand
4589 //     with the RATs and repeat as needed.  Alternately, Release() might
4590 //     detach and extract a successor, but then pass the residual list to the wakee.
4591 //     The wakee would be responsible for reattaching and remerging before it
4592 //     competed for the lock.
4593 //
4594 // Both "pop" and DMR are immune from ABA corruption -- there can be
4595 // multiple concurrent pushers, but only one popper or detacher.
4596 // This implementation pops from the head of the list.  This is unfair,
4597 // but tends to provide excellent throughput as hot threads remain hot.
4598 // (We wake recently run threads first).
4599 
4600 void Thread::muxRelease (volatile intptr_t * Lock)  {
4601   for (;;) {
4602     const intptr_t w = Atomic::cmpxchg_ptr (0, Lock, LOCKBIT) ;
4603     assert (w & LOCKBIT, "invariant") ;
4604     if (w == LOCKBIT) return ;
4605     ParkEvent * List = (ParkEvent *) (w & ~LOCKBIT) ;
4606     assert (List != NULL, "invariant") ;
4607     assert (List->OnList == intptr_t(Lock), "invariant") ;
4608     ParkEvent * nxt = List->ListNext ;
4609 
4610     // The following CAS() releases the lock and pops the head element.
4611     if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4612       continue ;
4613     }
4614     List->OnList = 0 ;
4615     OrderAccess::fence() ;
4616     List->unpark () ;
4617     return ;
4618   }
4619 }
4620 
4621 
4622 void Threads::verify() {
4623   ALL_JAVA_THREADS(p) {
4624     p->verify();
4625   }
4626   VMThread* thread = VMThread::vm_thread();
4627   if (thread != NULL) thread->verify();
4628 }