1 /*
   2  * Copyright (c) 1997, 2011, 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 "jvmtifiles/jvmtiEnv.hpp"
  35 #include "memory/oopFactory.hpp"
  36 #include "memory/universe.inline.hpp"
  37 #include "oops/instanceKlass.hpp"
  38 #include "oops/objArrayOop.hpp"
  39 #include "oops/oop.inline.hpp"
  40 #include "oops/symbol.hpp"
  41 #include "prims/jvm_misc.hpp"
  42 #include "prims/jvmtiExport.hpp"
  43 #include "prims/jvmtiThreadState.hpp"
  44 #include "prims/privilegedStack.hpp"
  45 #include "runtime/aprofiler.hpp"
  46 #include "runtime/arguments.hpp"
  47 #include "runtime/biasedLocking.hpp"
  48 #include "runtime/deoptimization.hpp"
  49 #include "runtime/fprofiler.hpp"
  50 #include "runtime/frame.inline.hpp"
  51 #include "runtime/init.hpp"
  52 #include "runtime/interfaceSupport.hpp"
  53 #include "runtime/java.hpp"
  54 #include "runtime/javaCalls.hpp"
  55 #include "runtime/jniPeriodicChecker.hpp"
  56 #include "runtime/memprofiler.hpp"
  57 #include "runtime/mutexLocker.hpp"
  58 #include "runtime/objectMonitor.hpp"
  59 #include "runtime/osThread.hpp"
  60 #include "runtime/safepoint.hpp"
  61 #include "runtime/sharedRuntime.hpp"
  62 #include "runtime/statSampler.hpp"
  63 #include "runtime/stubRoutines.hpp"
  64 #include "runtime/task.hpp"
  65 #include "runtime/threadCritical.hpp"
  66 #include "runtime/threadLocalStorage.hpp"
  67 #include "runtime/vframe.hpp"
  68 #include "runtime/vframeArray.hpp"
  69 #include "runtime/vframe_hp.hpp"
  70 #include "runtime/vmThread.hpp"
  71 #include "runtime/vm_operations.hpp"
  72 #include "services/attachListener.hpp"
  73 #include "services/management.hpp"
  74 #include "services/threadService.hpp"
  75 #include "utilities/defaultStream.hpp"
  76 #include "utilities/dtrace.hpp"
  77 #include "utilities/events.hpp"
  78 #include "utilities/preserveException.hpp"
  79 #ifdef TARGET_OS_FAMILY_linux
  80 # include "os_linux.inline.hpp"
  81 # include "thread_linux.inline.hpp"
  82 #endif
  83 #ifdef TARGET_OS_FAMILY_solaris
  84 # include "os_solaris.inline.hpp"
  85 # include "thread_solaris.inline.hpp"
  86 #endif
  87 #ifdef TARGET_OS_FAMILY_windows
  88 # include "os_windows.inline.hpp"
  89 # include "thread_windows.inline.hpp"
  90 #endif
  91 #ifndef SERIALGC
  92 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
  93 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
  94 #include "gc_implementation/parallelScavenge/pcTasks.hpp"
  95 #endif
  96 #ifdef COMPILER1
  97 #include "c1/c1_Compiler.hpp"
  98 #endif
  99 #ifdef COMPILER2
 100 #include "opto/c2compiler.hpp"
 101 #include "opto/idealGraphPrinter.hpp"
 102 #endif
 103 
 104 #ifdef DTRACE_ENABLED
 105 
 106 // Only bother with this argument setup if dtrace is available
 107 
 108 HS_DTRACE_PROBE_DECL(hotspot, vm__init__begin);
 109 HS_DTRACE_PROBE_DECL(hotspot, vm__init__end);
 110 HS_DTRACE_PROBE_DECL5(hotspot, thread__start, char*, intptr_t,
 111   intptr_t, intptr_t, bool);
 112 HS_DTRACE_PROBE_DECL5(hotspot, thread__stop, char*, intptr_t,
 113   intptr_t, intptr_t, bool);
 114 
 115 #define DTRACE_THREAD_PROBE(probe, javathread)                             \
 116   {                                                                        \
 117     ResourceMark rm(this);                                                 \
 118     int len = 0;                                                           \
 119     const char* name = (javathread)->get_thread_name();                    \
 120     len = strlen(name);                                                    \
 121     HS_DTRACE_PROBE5(hotspot, thread__##probe,                             \
 122       name, len,                                                           \
 123       java_lang_Thread::thread_id((javathread)->threadObj()),              \
 124       (javathread)->osthread()->thread_id(),                               \
 125       java_lang_Thread::is_daemon((javathread)->threadObj()));             \
 126   }
 127 
 128 #else //  ndef DTRACE_ENABLED
 129 
 130 #define DTRACE_THREAD_PROBE(probe, javathread)
 131 
 132 #endif // ndef DTRACE_ENABLED
 133 
 134 // Class hierarchy
 135 // - Thread
 136 //   - VMThread
 137 //   - WatcherThread
 138 //   - ConcurrentMarkSweepThread
 139 //   - JavaThread
 140 //     - CompilerThread
 141 
 142 // ======= Thread ========
 143 
 144 // Support for forcing alignment of thread objects for biased locking
 145 void* Thread::operator new(size_t size) {
 146   if (UseBiasedLocking) {
 147     const int alignment = markOopDesc::biased_lock_alignment;
 148     size_t aligned_size = size + (alignment - sizeof(intptr_t));
 149     void* real_malloc_addr = CHeapObj::operator new(aligned_size);
 150     void* aligned_addr     = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
 151     assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
 152            ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
 153            "JavaThread alignment code overflowed allocated storage");
 154     if (TraceBiasedLocking) {
 155       if (aligned_addr != real_malloc_addr)
 156         tty->print_cr("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
 157                       real_malloc_addr, aligned_addr);
 158     }
 159     ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
 160     return aligned_addr;
 161   } else {
 162     return CHeapObj::operator new(size);
 163   }
 164 }
 165 
 166 void Thread::operator delete(void* p) {
 167   if (UseBiasedLocking) {
 168     void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
 169     CHeapObj::operator delete(real_malloc_addr);
 170   } else {
 171     CHeapObj::operator delete(p);
 172   }
 173 }
 174 
 175 
 176 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
 177 // JavaThread
 178 
 179 
 180 Thread::Thread() {
 181   // stack and get_thread
 182   set_stack_base(NULL);
 183   set_stack_size(0);
 184   set_self_raw_id(0);
 185   set_lgrp_id(-1);
 186 
 187   // allocated data structures
 188   set_osthread(NULL);
 189   set_resource_area(new ResourceArea());
 190   set_handle_area(new HandleArea(NULL));
 191   set_active_handles(NULL);
 192   set_free_handle_block(NULL);
 193   set_last_handle_mark(NULL);
 194 
 195   // This initial value ==> never claimed.
 196   _oops_do_parity = 0;
 197 
 198   // the handle mark links itself to last_handle_mark
 199   new HandleMark(this);
 200 
 201   // plain initialization
 202   debug_only(_owned_locks = NULL;)
 203   debug_only(_allow_allocation_count = 0;)
 204   NOT_PRODUCT(_allow_safepoint_count = 0;)
 205   NOT_PRODUCT(_skip_gcalot = false;)
 206   CHECK_UNHANDLED_OOPS_ONLY(_gc_locked_out_count = 0;)
 207   _jvmti_env_iteration_count = 0;
 208   set_allocated_bytes(0);
 209   _vm_operation_started_count = 0;
 210   _vm_operation_completed_count = 0;
 211   _current_pending_monitor = NULL;
 212   _current_pending_monitor_is_from_java = true;
 213   _current_waiting_monitor = NULL;
 214   _num_nested_signal = 0;
 215   omFreeList = NULL ;
 216   omFreeCount = 0 ;
 217   omFreeProvision = 32 ;
 218   omInUseList = NULL ;
 219   omInUseCount = 0 ;
 220 
 221   _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true);
 222   _suspend_flags = 0;
 223 
 224   // thread-specific hashCode stream generator state - Marsaglia shift-xor form
 225   _hashStateX = os::random() ;
 226   _hashStateY = 842502087 ;
 227   _hashStateZ = 0x8767 ;    // (int)(3579807591LL & 0xffff) ;
 228   _hashStateW = 273326509 ;
 229 
 230   _OnTrap   = 0 ;
 231   _schedctl = NULL ;
 232   _Stalled  = 0 ;
 233   _TypeTag  = 0x2BAD ;
 234 
 235   // Many of the following fields are effectively final - immutable
 236   // Note that nascent threads can't use the Native Monitor-Mutex
 237   // construct until the _MutexEvent is initialized ...
 238   // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
 239   // we might instead use a stack of ParkEvents that we could provision on-demand.
 240   // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
 241   // and ::Release()
 242   _ParkEvent   = ParkEvent::Allocate (this) ;
 243   _SleepEvent  = ParkEvent::Allocate (this) ;
 244   _MutexEvent  = ParkEvent::Allocate (this) ;
 245   _MuxEvent    = ParkEvent::Allocate (this) ;
 246 
 247 #ifdef CHECK_UNHANDLED_OOPS
 248   if (CheckUnhandledOops) {
 249     _unhandled_oops = new UnhandledOops(this);
 250   }
 251 #endif // CHECK_UNHANDLED_OOPS
 252 #ifdef ASSERT
 253   if (UseBiasedLocking) {
 254     assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
 255     assert(this == _real_malloc_address ||
 256            this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
 257            "bug in forced alignment of thread objects");
 258   }
 259 #endif /* ASSERT */
 260 }
 261 
 262 void Thread::initialize_thread_local_storage() {
 263   // Note: Make sure this method only calls
 264   // non-blocking operations. Otherwise, it might not work
 265   // with the thread-startup/safepoint interaction.
 266 
 267   // During Java thread startup, safepoint code should allow this
 268   // method to complete because it may need to allocate memory to
 269   // store information for the new thread.
 270 
 271   // initialize structure dependent on thread local storage
 272   ThreadLocalStorage::set_thread(this);
 273 
 274   // set up any platform-specific state.
 275   os::initialize_thread();
 276 
 277 }
 278 
 279 void Thread::record_stack_base_and_size() {
 280   set_stack_base(os::current_stack_base());
 281   set_stack_size(os::current_stack_size());
 282 }
 283 
 284 
 285 Thread::~Thread() {
 286   // Reclaim the objectmonitors from the omFreeList of the moribund thread.
 287   ObjectSynchronizer::omFlush (this) ;
 288 
 289   // deallocate data structures
 290   delete resource_area();
 291   // since the handle marks are using the handle area, we have to deallocated the root
 292   // handle mark before deallocating the thread's handle area,
 293   assert(last_handle_mark() != NULL, "check we have an element");
 294   delete last_handle_mark();
 295   assert(last_handle_mark() == NULL, "check we have reached the end");
 296 
 297   // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
 298   // We NULL out the fields for good hygiene.
 299   ParkEvent::Release (_ParkEvent)   ; _ParkEvent   = NULL ;
 300   ParkEvent::Release (_SleepEvent)  ; _SleepEvent  = NULL ;
 301   ParkEvent::Release (_MutexEvent)  ; _MutexEvent  = NULL ;
 302   ParkEvent::Release (_MuxEvent)    ; _MuxEvent    = NULL ;
 303 
 304   delete handle_area();
 305 
 306   // osthread() can be NULL, if creation of thread failed.
 307   if (osthread() != NULL) os::free_thread(osthread());
 308 
 309   delete _SR_lock;
 310 
 311   // clear thread local storage if the Thread is deleting itself
 312   if (this == Thread::current()) {
 313     ThreadLocalStorage::set_thread(NULL);
 314   } else {
 315     // In the case where we're not the current thread, invalidate all the
 316     // caches in case some code tries to get the current thread or the
 317     // thread that was destroyed, and gets stale information.
 318     ThreadLocalStorage::invalidate_all();
 319   }
 320   CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
 321 }
 322 
 323 // NOTE: dummy function for assertion purpose.
 324 void Thread::run() {
 325   ShouldNotReachHere();
 326 }
 327 
 328 #ifdef ASSERT
 329 // Private method to check for dangling thread pointer
 330 void check_for_dangling_thread_pointer(Thread *thread) {
 331  assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
 332          "possibility of dangling Thread pointer");
 333 }
 334 #endif
 335 
 336 
 337 #ifndef PRODUCT
 338 // Tracing method for basic thread operations
 339 void Thread::trace(const char* msg, const Thread* const thread) {
 340   if (!TraceThreadEvents) return;
 341   ResourceMark rm;
 342   ThreadCritical tc;
 343   const char *name = "non-Java thread";
 344   int prio = -1;
 345   if (thread->is_Java_thread()
 346       && !thread->is_Compiler_thread()) {
 347     // The Threads_lock must be held to get information about
 348     // this thread but may not be in some situations when
 349     // tracing  thread events.
 350     bool release_Threads_lock = false;
 351     if (!Threads_lock->owned_by_self()) {
 352       Threads_lock->lock();
 353       release_Threads_lock = true;
 354     }
 355     JavaThread* jt = (JavaThread *)thread;
 356     name = (char *)jt->get_thread_name();
 357     oop thread_oop = jt->threadObj();
 358     if (thread_oop != NULL) {
 359       prio = java_lang_Thread::priority(thread_oop);
 360     }
 361     if (release_Threads_lock) {
 362       Threads_lock->unlock();
 363     }
 364   }
 365   tty->print_cr("Thread::%s " INTPTR_FORMAT " [%lx] %s (prio: %d)", msg, thread, thread->osthread()->thread_id(), name, prio);
 366 }
 367 #endif
 368 
 369 
 370 ThreadPriority Thread::get_priority(const Thread* const thread) {
 371   trace("get priority", thread);
 372   ThreadPriority priority;
 373   // Can return an error!
 374   (void)os::get_priority(thread, priority);
 375   assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
 376   return priority;
 377 }
 378 
 379 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
 380   trace("set priority", thread);
 381   debug_only(check_for_dangling_thread_pointer(thread);)
 382   // Can return an error!
 383   (void)os::set_priority(thread, priority);
 384 }
 385 
 386 
 387 void Thread::start(Thread* thread) {
 388   trace("start", thread);
 389   // Start is different from resume in that its safety is guaranteed by context or
 390   // being called from a Java method synchronized on the Thread object.
 391   if (!DisableStartThread) {
 392     if (thread->is_Java_thread()) {
 393       // Initialize the thread state to RUNNABLE before starting this thread.
 394       // Can not set it after the thread started because we do not know the
 395       // exact thread state at that time. It could be in MONITOR_WAIT or
 396       // in SLEEPING or some other state.
 397       java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
 398                                           java_lang_Thread::RUNNABLE);
 399     }
 400     os::start_thread(thread);
 401   }
 402 }
 403 
 404 // Enqueue a VM_Operation to do the job for us - sometime later
 405 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
 406   VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
 407   VMThread::execute(vm_stop);
 408 }
 409 
 410 
 411 //
 412 // Check if an external suspend request has completed (or has been
 413 // cancelled). Returns true if the thread is externally suspended and
 414 // false otherwise.
 415 //
 416 // The bits parameter returns information about the code path through
 417 // the routine. Useful for debugging:
 418 //
 419 // set in is_ext_suspend_completed():
 420 // 0x00000001 - routine was entered
 421 // 0x00000010 - routine return false at end
 422 // 0x00000100 - thread exited (return false)
 423 // 0x00000200 - suspend request cancelled (return false)
 424 // 0x00000400 - thread suspended (return true)
 425 // 0x00001000 - thread is in a suspend equivalent state (return true)
 426 // 0x00002000 - thread is native and walkable (return true)
 427 // 0x00004000 - thread is native_trans and walkable (needed retry)
 428 //
 429 // set in wait_for_ext_suspend_completion():
 430 // 0x00010000 - routine was entered
 431 // 0x00020000 - suspend request cancelled before loop (return false)
 432 // 0x00040000 - thread suspended before loop (return true)
 433 // 0x00080000 - suspend request cancelled in loop (return false)
 434 // 0x00100000 - thread suspended in loop (return true)
 435 // 0x00200000 - suspend not completed during retry loop (return false)
 436 //
 437 
 438 // Helper class for tracing suspend wait debug bits.
 439 //
 440 // 0x00000100 indicates that the target thread exited before it could
 441 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
 442 // 0x00080000 each indicate a cancelled suspend request so they don't
 443 // count as wait failures either.
 444 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
 445 
 446 class TraceSuspendDebugBits : public StackObj {
 447  private:
 448   JavaThread * jt;
 449   bool         is_wait;
 450   bool         called_by_wait;  // meaningful when !is_wait
 451   uint32_t *   bits;
 452 
 453  public:
 454   TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
 455                         uint32_t *_bits) {
 456     jt             = _jt;
 457     is_wait        = _is_wait;
 458     called_by_wait = _called_by_wait;
 459     bits           = _bits;
 460   }
 461 
 462   ~TraceSuspendDebugBits() {
 463     if (!is_wait) {
 464 #if 1
 465       // By default, don't trace bits for is_ext_suspend_completed() calls.
 466       // That trace is very chatty.
 467       return;
 468 #else
 469       if (!called_by_wait) {
 470         // If tracing for is_ext_suspend_completed() is enabled, then only
 471         // trace calls to it from wait_for_ext_suspend_completion()
 472         return;
 473       }
 474 #endif
 475     }
 476 
 477     if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
 478       if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
 479         MutexLocker ml(Threads_lock);  // needed for get_thread_name()
 480         ResourceMark rm;
 481 
 482         tty->print_cr(
 483             "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
 484             jt->get_thread_name(), *bits);
 485 
 486         guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
 487       }
 488     }
 489   }
 490 };
 491 #undef DEBUG_FALSE_BITS
 492 
 493 
 494 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, uint32_t *bits) {
 495   TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
 496 
 497   bool did_trans_retry = false;  // only do thread_in_native_trans retry once
 498   bool do_trans_retry;           // flag to force the retry
 499 
 500   *bits |= 0x00000001;
 501 
 502   do {
 503     do_trans_retry = false;
 504 
 505     if (is_exiting()) {
 506       // Thread is in the process of exiting. This is always checked
 507       // first to reduce the risk of dereferencing a freed JavaThread.
 508       *bits |= 0x00000100;
 509       return false;
 510     }
 511 
 512     if (!is_external_suspend()) {
 513       // Suspend request is cancelled. This is always checked before
 514       // is_ext_suspended() to reduce the risk of a rogue resume
 515       // confusing the thread that made the suspend request.
 516       *bits |= 0x00000200;
 517       return false;
 518     }
 519 
 520     if (is_ext_suspended()) {
 521       // thread is suspended
 522       *bits |= 0x00000400;
 523       return true;
 524     }
 525 
 526     // Now that we no longer do hard suspends of threads running
 527     // native code, the target thread can be changing thread state
 528     // while we are in this routine:
 529     //
 530     //   _thread_in_native -> _thread_in_native_trans -> _thread_blocked
 531     //
 532     // We save a copy of the thread state as observed at this moment
 533     // and make our decision about suspend completeness based on the
 534     // copy. This closes the race where the thread state is seen as
 535     // _thread_in_native_trans in the if-thread_blocked check, but is
 536     // seen as _thread_blocked in if-thread_in_native_trans check.
 537     JavaThreadState save_state = thread_state();
 538 
 539     if (save_state == _thread_blocked && is_suspend_equivalent()) {
 540       // If the thread's state is _thread_blocked and this blocking
 541       // condition is known to be equivalent to a suspend, then we can
 542       // consider the thread to be externally suspended. This means that
 543       // the code that sets _thread_blocked has been modified to do
 544       // self-suspension if the blocking condition releases. We also
 545       // used to check for CONDVAR_WAIT here, but that is now covered by
 546       // the _thread_blocked with self-suspension check.
 547       //
 548       // Return true since we wouldn't be here unless there was still an
 549       // external suspend request.
 550       *bits |= 0x00001000;
 551       return true;
 552     } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
 553       // Threads running native code will self-suspend on native==>VM/Java
 554       // transitions. If its stack is walkable (should always be the case
 555       // unless this function is called before the actual java_suspend()
 556       // call), then the wait is done.
 557       *bits |= 0x00002000;
 558       return true;
 559     } else if (!called_by_wait && !did_trans_retry &&
 560                save_state == _thread_in_native_trans &&
 561                frame_anchor()->walkable()) {
 562       // The thread is transitioning from thread_in_native to another
 563       // thread state. check_safepoint_and_suspend_for_native_trans()
 564       // will force the thread to self-suspend. If it hasn't gotten
 565       // there yet we may have caught the thread in-between the native
 566       // code check above and the self-suspend. Lucky us. If we were
 567       // called by wait_for_ext_suspend_completion(), then it
 568       // will be doing the retries so we don't have to.
 569       //
 570       // Since we use the saved thread state in the if-statement above,
 571       // there is a chance that the thread has already transitioned to
 572       // _thread_blocked by the time we get here. In that case, we will
 573       // make a single unnecessary pass through the logic below. This
 574       // doesn't hurt anything since we still do the trans retry.
 575 
 576       *bits |= 0x00004000;
 577 
 578       // Once the thread leaves thread_in_native_trans for another
 579       // thread state, we break out of this retry loop. We shouldn't
 580       // need this flag to prevent us from getting back here, but
 581       // sometimes paranoia is good.
 582       did_trans_retry = true;
 583 
 584       // We wait for the thread to transition to a more usable state.
 585       for (int i = 1; i <= SuspendRetryCount; i++) {
 586         // We used to do an "os::yield_all(i)" call here with the intention
 587         // that yielding would increase on each retry. However, the parameter
 588         // is ignored on Linux which means the yield didn't scale up. Waiting
 589         // on the SR_lock below provides a much more predictable scale up for
 590         // the delay. It also provides a simple/direct point to check for any
 591         // safepoint requests from the VMThread
 592 
 593         // temporarily drops SR_lock while doing wait with safepoint check
 594         // (if we're a JavaThread - the WatcherThread can also call this)
 595         // and increase delay with each retry
 596         SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 597 
 598         // check the actual thread state instead of what we saved above
 599         if (thread_state() != _thread_in_native_trans) {
 600           // the thread has transitioned to another thread state so
 601           // try all the checks (except this one) one more time.
 602           do_trans_retry = true;
 603           break;
 604         }
 605       } // end retry loop
 606 
 607 
 608     }
 609   } while (do_trans_retry);
 610 
 611   *bits |= 0x00000010;
 612   return false;
 613 }
 614 
 615 //
 616 // Wait for an external suspend request to complete (or be cancelled).
 617 // Returns true if the thread is externally suspended and false otherwise.
 618 //
 619 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
 620        uint32_t *bits) {
 621   TraceSuspendDebugBits tsdb(this, true /* is_wait */,
 622                              false /* !called_by_wait */, bits);
 623 
 624   // local flag copies to minimize SR_lock hold time
 625   bool is_suspended;
 626   bool pending;
 627   uint32_t reset_bits;
 628 
 629   // set a marker so is_ext_suspend_completed() knows we are the caller
 630   *bits |= 0x00010000;
 631 
 632   // We use reset_bits to reinitialize the bits value at the top of
 633   // each retry loop. This allows the caller to make use of any
 634   // unused bits for their own marking purposes.
 635   reset_bits = *bits;
 636 
 637   {
 638     MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
 639     is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 640                                             delay, bits);
 641     pending = is_external_suspend();
 642   }
 643   // must release SR_lock to allow suspension to complete
 644 
 645   if (!pending) {
 646     // A cancelled suspend request is the only false return from
 647     // is_ext_suspend_completed() that keeps us from entering the
 648     // retry loop.
 649     *bits |= 0x00020000;
 650     return false;
 651   }
 652 
 653   if (is_suspended) {
 654     *bits |= 0x00040000;
 655     return true;
 656   }
 657 
 658   for (int i = 1; i <= retries; i++) {
 659     *bits = reset_bits;  // reinit to only track last retry
 660 
 661     // We used to do an "os::yield_all(i)" call here with the intention
 662     // that yielding would increase on each retry. However, the parameter
 663     // is ignored on Linux which means the yield didn't scale up. Waiting
 664     // on the SR_lock below provides a much more predictable scale up for
 665     // the delay. It also provides a simple/direct point to check for any
 666     // safepoint requests from the VMThread
 667 
 668     {
 669       MutexLocker ml(SR_lock());
 670       // wait with safepoint check (if we're a JavaThread - the WatcherThread
 671       // can also call this)  and increase delay with each retry
 672       SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 673 
 674       is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 675                                               delay, bits);
 676 
 677       // It is possible for the external suspend request to be cancelled
 678       // (by a resume) before the actual suspend operation is completed.
 679       // Refresh our local copy to see if we still need to wait.
 680       pending = is_external_suspend();
 681     }
 682 
 683     if (!pending) {
 684       // A cancelled suspend request is the only false return from
 685       // is_ext_suspend_completed() that keeps us from staying in the
 686       // retry loop.
 687       *bits |= 0x00080000;
 688       return false;
 689     }
 690 
 691     if (is_suspended) {
 692       *bits |= 0x00100000;
 693       return true;
 694     }
 695   } // end retry loop
 696 
 697   // thread did not suspend after all our retries
 698   *bits |= 0x00200000;
 699   return false;
 700 }
 701 
 702 #ifndef PRODUCT
 703 void JavaThread::record_jump(address target, address instr, const char* file, int line) {
 704 
 705   // This should not need to be atomic as the only way for simultaneous
 706   // updates is via interrupts. Even then this should be rare or non-existant
 707   // and we don't care that much anyway.
 708 
 709   int index = _jmp_ring_index;
 710   _jmp_ring_index = (index + 1 ) & (jump_ring_buffer_size - 1);
 711   _jmp_ring[index]._target = (intptr_t) target;
 712   _jmp_ring[index]._instruction = (intptr_t) instr;
 713   _jmp_ring[index]._file = file;
 714   _jmp_ring[index]._line = line;
 715 }
 716 #endif /* PRODUCT */
 717 
 718 // Called by flat profiler
 719 // Callers have already called wait_for_ext_suspend_completion
 720 // The assertion for that is currently too complex to put here:
 721 bool JavaThread::profile_last_Java_frame(frame* _fr) {
 722   bool gotframe = false;
 723   // self suspension saves needed state.
 724   if (has_last_Java_frame() && _anchor.walkable()) {
 725      *_fr = pd_last_frame();
 726      gotframe = true;
 727   }
 728   return gotframe;
 729 }
 730 
 731 void Thread::interrupt(Thread* thread) {
 732   trace("interrupt", thread);
 733   debug_only(check_for_dangling_thread_pointer(thread);)
 734   os::interrupt(thread);
 735 }
 736 
 737 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
 738   trace("is_interrupted", thread);
 739   debug_only(check_for_dangling_thread_pointer(thread);)
 740   // Note:  If clear_interrupted==false, this simply fetches and
 741   // returns the value of the field osthread()->interrupted().
 742   return os::is_interrupted(thread, clear_interrupted);
 743 }
 744 
 745 
 746 // GC Support
 747 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
 748   jint thread_parity = _oops_do_parity;
 749   if (thread_parity != strong_roots_parity) {
 750     jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
 751     if (res == thread_parity) return true;
 752     else {
 753       guarantee(res == strong_roots_parity, "Or else what?");
 754       assert(SharedHeap::heap()->n_par_threads() > 0,
 755              "Should only fail when parallel.");
 756       return false;
 757     }
 758   }
 759   assert(SharedHeap::heap()->n_par_threads() > 0,
 760          "Should only fail when parallel.");
 761   return false;
 762 }
 763 
 764 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
 765   active_handles()->oops_do(f);
 766   // Do oop for ThreadShadow
 767   f->do_oop((oop*)&_pending_exception);
 768   handle_area()->oops_do(f);
 769 }
 770 
 771 void Thread::nmethods_do(CodeBlobClosure* cf) {
 772   // no nmethods in a generic thread...
 773 }
 774 
 775 void Thread::print_on(outputStream* st) const {
 776   // get_priority assumes osthread initialized
 777   if (osthread() != NULL) {
 778     st->print("prio=%d tid=" INTPTR_FORMAT " ", get_priority(this), this);
 779     osthread()->print_on(st);
 780   }
 781   debug_only(if (WizardMode) print_owned_locks_on(st);)
 782 }
 783 
 784 // Thread::print_on_error() is called by fatal error handler. Don't use
 785 // any lock or allocate memory.
 786 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
 787   if      (is_VM_thread())                  st->print("VMThread");
 788   else if (is_Compiler_thread())            st->print("CompilerThread");
 789   else if (is_Java_thread())                st->print("JavaThread");
 790   else if (is_GC_task_thread())             st->print("GCTaskThread");
 791   else if (is_Watcher_thread())             st->print("WatcherThread");
 792   else if (is_ConcurrentGC_thread())        st->print("ConcurrentGCThread");
 793   else st->print("Thread");
 794 
 795   st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
 796             _stack_base - _stack_size, _stack_base);
 797 
 798   if (osthread()) {
 799     st->print(" [id=%d]", osthread()->thread_id());
 800   }
 801 }
 802 
 803 #ifdef ASSERT
 804 void Thread::print_owned_locks_on(outputStream* st) const {
 805   Monitor *cur = _owned_locks;
 806   if (cur == NULL) {
 807     st->print(" (no locks) ");
 808   } else {
 809     st->print_cr(" Locks owned:");
 810     while(cur) {
 811       cur->print_on(st);
 812       cur = cur->next();
 813     }
 814   }
 815 }
 816 
 817 static int ref_use_count  = 0;
 818 
 819 bool Thread::owns_locks_but_compiled_lock() const {
 820   for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 821     if (cur != Compile_lock) return true;
 822   }
 823   return false;
 824 }
 825 
 826 
 827 #endif
 828 
 829 #ifndef PRODUCT
 830 
 831 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
 832 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
 833 // no threads which allow_vm_block's are held
 834 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
 835     // Check if current thread is allowed to block at a safepoint
 836     if (!(_allow_safepoint_count == 0))
 837       fatal("Possible safepoint reached by thread that does not allow it");
 838     if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
 839       fatal("LEAF method calling lock?");
 840     }
 841 
 842 #ifdef ASSERT
 843     if (potential_vm_operation && is_Java_thread()
 844         && !Universe::is_bootstrapping()) {
 845       // Make sure we do not hold any locks that the VM thread also uses.
 846       // This could potentially lead to deadlocks
 847       for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 848         // Threads_lock is special, since the safepoint synchronization will not start before this is
 849         // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
 850         // since it is used to transfer control between JavaThreads and the VMThread
 851         // Do not *exclude* any locks unless you are absolutly sure it is correct. Ask someone else first!
 852         if ( (cur->allow_vm_block() &&
 853               cur != Threads_lock &&
 854               cur != Compile_lock &&               // Temporary: should not be necessary when we get spearate compilation
 855               cur != VMOperationRequest_lock &&
 856               cur != VMOperationQueue_lock) ||
 857               cur->rank() == Mutex::special) {
 858           warning("Thread holding lock at safepoint that vm can block on: %s", cur->name());
 859         }
 860       }
 861     }
 862 
 863     if (GCALotAtAllSafepoints) {
 864       // We could enter a safepoint here and thus have a gc
 865       InterfaceSupport::check_gc_alot();
 866     }
 867 #endif
 868 }
 869 #endif
 870 
 871 bool Thread::is_in_stack(address adr) const {
 872   assert(Thread::current() == this, "is_in_stack can only be called from current thread");
 873   address end = os::current_stack_pointer();
 874   if (stack_base() >= adr && adr >= end) return true;
 875 
 876   return false;
 877 }
 878 
 879 
 880 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
 881 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
 882 // used for compilation in the future. If that change is made, the need for these methods
 883 // should be revisited, and they should be removed if possible.
 884 
 885 bool Thread::is_lock_owned(address adr) const {
 886   return on_local_stack(adr);
 887 }
 888 
 889 bool Thread::set_as_starting_thread() {
 890  // NOTE: this must be called inside the main thread.
 891   return os::create_main_thread((JavaThread*)this);
 892 }
 893 
 894 static void initialize_class(Symbol* class_name, TRAPS) {
 895   klassOop klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
 896   instanceKlass::cast(klass)->initialize(CHECK);
 897 }
 898 
 899 
 900 // Creates the initial ThreadGroup
 901 static Handle create_initial_thread_group(TRAPS) {
 902   klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
 903   instanceKlassHandle klass (THREAD, k);
 904 
 905   Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
 906   {
 907     JavaValue result(T_VOID);
 908     JavaCalls::call_special(&result,
 909                             system_instance,
 910                             klass,
 911                             vmSymbols::object_initializer_name(),
 912                             vmSymbols::void_method_signature(),
 913                             CHECK_NH);
 914   }
 915   Universe::set_system_thread_group(system_instance());
 916 
 917   Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
 918   {
 919     JavaValue result(T_VOID);
 920     Handle string = java_lang_String::create_from_str("main", CHECK_NH);
 921     JavaCalls::call_special(&result,
 922                             main_instance,
 923                             klass,
 924                             vmSymbols::object_initializer_name(),
 925                             vmSymbols::threadgroup_string_void_signature(),
 926                             system_instance,
 927                             string,
 928                             CHECK_NH);
 929   }
 930   return main_instance;
 931 }
 932 
 933 // Creates the initial Thread
 934 static oop create_initial_thread(Handle thread_group, JavaThread* thread, TRAPS) {
 935   klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
 936   instanceKlassHandle klass (THREAD, k);
 937   instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
 938 
 939   java_lang_Thread::set_thread(thread_oop(), thread);
 940   java_lang_Thread::set_priority(thread_oop(), NormPriority);
 941   thread->set_threadObj(thread_oop());
 942 
 943   Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
 944 
 945   JavaValue result(T_VOID);
 946   JavaCalls::call_special(&result, thread_oop,
 947                                    klass,
 948                                    vmSymbols::object_initializer_name(),
 949                                    vmSymbols::threadgroup_string_void_signature(),
 950                                    thread_group,
 951                                    string,
 952                                    CHECK_NULL);
 953   return thread_oop();
 954 }
 955 
 956 static void call_initializeSystemClass(TRAPS) {
 957   klassOop k =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
 958   instanceKlassHandle klass (THREAD, k);
 959 
 960   JavaValue result(T_VOID);
 961   JavaCalls::call_static(&result, klass, vmSymbols::initializeSystemClass_name(),
 962                                          vmSymbols::void_method_signature(), CHECK);
 963 }
 964 
 965 // General purpose hook into Java code, run once when the VM is initialized.
 966 // The Java library method itself may be changed independently from the VM.
 967 static void call_postVMInitHook(TRAPS) {
 968   klassOop k = SystemDictionary::sun_misc_PostVMInitHook_klass();
 969   instanceKlassHandle klass (THREAD, k);
 970   if (klass.not_null()) {
 971     JavaValue result(T_VOID);
 972     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
 973                                            vmSymbols::void_method_signature(),
 974                                            CHECK);
 975   }
 976 }
 977 
 978 static void reset_vm_info_property(TRAPS) {
 979   // the vm info string
 980   ResourceMark rm(THREAD);
 981   const char *vm_info = VM_Version::vm_info_string();
 982 
 983   // java.lang.System class
 984   klassOop k =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
 985   instanceKlassHandle klass (THREAD, k);
 986 
 987   // setProperty arguments
 988   Handle key_str    = java_lang_String::create_from_str("java.vm.info", CHECK);
 989   Handle value_str  = java_lang_String::create_from_str(vm_info, CHECK);
 990 
 991   // return value
 992   JavaValue r(T_OBJECT);
 993 
 994   // public static String setProperty(String key, String value);
 995   JavaCalls::call_static(&r,
 996                          klass,
 997                          vmSymbols::setProperty_name(),
 998                          vmSymbols::string_string_string_signature(),
 999                          key_str,
1000                          value_str,
1001                          CHECK);
1002 }
1003 
1004 
1005 void JavaThread::allocate_threadObj(Handle thread_group, char* thread_name, bool daemon, TRAPS) {
1006   assert(thread_group.not_null(), "thread group should be specified");
1007   assert(threadObj() == NULL, "should only create Java thread object once");
1008 
1009   klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1010   instanceKlassHandle klass (THREAD, k);
1011   instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1012 
1013   java_lang_Thread::set_thread(thread_oop(), this);
1014   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1015   set_threadObj(thread_oop());
1016 
1017   JavaValue result(T_VOID);
1018   if (thread_name != NULL) {
1019     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1020     // Thread gets assigned specified name and null target
1021     JavaCalls::call_special(&result,
1022                             thread_oop,
1023                             klass,
1024                             vmSymbols::object_initializer_name(),
1025                             vmSymbols::threadgroup_string_void_signature(),
1026                             thread_group, // Argument 1
1027                             name,         // Argument 2
1028                             THREAD);
1029   } else {
1030     // Thread gets assigned name "Thread-nnn" and null target
1031     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1032     JavaCalls::call_special(&result,
1033                             thread_oop,
1034                             klass,
1035                             vmSymbols::object_initializer_name(),
1036                             vmSymbols::threadgroup_runnable_void_signature(),
1037                             thread_group, // Argument 1
1038                             Handle(),     // Argument 2
1039                             THREAD);
1040   }
1041 
1042 
1043   if (daemon) {
1044       java_lang_Thread::set_daemon(thread_oop());
1045   }
1046 
1047   if (HAS_PENDING_EXCEPTION) {
1048     return;
1049   }
1050 
1051   KlassHandle group(this, SystemDictionary::ThreadGroup_klass());
1052   Handle threadObj(this, this->threadObj());
1053 
1054   JavaCalls::call_special(&result,
1055                          thread_group,
1056                          group,
1057                          vmSymbols::add_method_name(),
1058                          vmSymbols::thread_void_signature(),
1059                          threadObj,          // Arg 1
1060                          THREAD);
1061 
1062 
1063 }
1064 
1065 // NamedThread --  non-JavaThread subclasses with multiple
1066 // uniquely named instances should derive from this.
1067 NamedThread::NamedThread() : Thread() {
1068   _name = NULL;
1069   _processed_thread = NULL;
1070 }
1071 
1072 NamedThread::~NamedThread() {
1073   if (_name != NULL) {
1074     FREE_C_HEAP_ARRAY(char, _name);
1075     _name = NULL;
1076   }
1077 }
1078 
1079 void NamedThread::set_name(const char* format, ...) {
1080   guarantee(_name == NULL, "Only get to set name once.");
1081   _name = NEW_C_HEAP_ARRAY(char, max_name_len);
1082   guarantee(_name != NULL, "alloc failure");
1083   va_list ap;
1084   va_start(ap, format);
1085   jio_vsnprintf(_name, max_name_len, format, ap);
1086   va_end(ap);
1087 }
1088 
1089 // ======= WatcherThread ========
1090 
1091 // The watcher thread exists to simulate timer interrupts.  It should
1092 // be replaced by an abstraction over whatever native support for
1093 // timer interrupts exists on the platform.
1094 
1095 WatcherThread* WatcherThread::_watcher_thread   = NULL;
1096 volatile bool  WatcherThread::_should_terminate = false;
1097 
1098 WatcherThread::WatcherThread() : Thread() {
1099   assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1100   if (os::create_thread(this, os::watcher_thread)) {
1101     _watcher_thread = this;
1102 
1103     // Set the watcher thread to the highest OS priority which should not be
1104     // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1105     // is created. The only normal thread using this priority is the reference
1106     // handler thread, which runs for very short intervals only.
1107     // If the VMThread's priority is not lower than the WatcherThread profiling
1108     // will be inaccurate.
1109     os::set_priority(this, MaxPriority);
1110     if (!DisableStartThread) {
1111       os::start_thread(this);
1112     }
1113   }
1114 }
1115 
1116 void WatcherThread::run() {
1117   assert(this == watcher_thread(), "just checking");
1118 
1119   this->record_stack_base_and_size();
1120   this->initialize_thread_local_storage();
1121   this->set_active_handles(JNIHandleBlock::allocate_block());
1122   while(!_should_terminate) {
1123     assert(watcher_thread() == Thread::current(),  "thread consistency check");
1124     assert(watcher_thread() == this,  "thread consistency check");
1125 
1126     // Calculate how long it'll be until the next PeriodicTask work
1127     // should be done, and sleep that amount of time.
1128     size_t time_to_wait = PeriodicTask::time_to_wait();
1129 
1130     // we expect this to timeout - we only ever get unparked when
1131     // we should terminate
1132     {
1133       OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1134 
1135       jlong prev_time = os::javaTimeNanos();
1136       for (;;) {
1137         int res= _SleepEvent->park(time_to_wait);
1138         if (res == OS_TIMEOUT || _should_terminate)
1139           break;
1140         // spurious wakeup of some kind
1141         jlong now = os::javaTimeNanos();
1142         time_to_wait -= (now - prev_time) / 1000000;
1143         if (time_to_wait <= 0)
1144           break;
1145         prev_time = now;
1146       }
1147     }
1148 
1149     if (is_error_reported()) {
1150       // A fatal error has happened, the error handler(VMError::report_and_die)
1151       // should abort JVM after creating an error log file. However in some
1152       // rare cases, the error handler itself might deadlock. Here we try to
1153       // kill JVM if the fatal error handler fails to abort in 2 minutes.
1154       //
1155       // This code is in WatcherThread because WatcherThread wakes up
1156       // periodically so the fatal error handler doesn't need to do anything;
1157       // also because the WatcherThread is less likely to crash than other
1158       // threads.
1159 
1160       for (;;) {
1161         if (!ShowMessageBoxOnError
1162          && (OnError == NULL || OnError[0] == '\0')
1163          && Arguments::abort_hook() == NULL) {
1164              os::sleep(this, 2 * 60 * 1000, false);
1165              fdStream err(defaultStream::output_fd());
1166              err.print_raw_cr("# [ timer expired, abort... ]");
1167              // skip atexit/vm_exit/vm_abort hooks
1168              os::die();
1169         }
1170 
1171         // Wake up 5 seconds later, the fatal handler may reset OnError or
1172         // ShowMessageBoxOnError when it is ready to abort.
1173         os::sleep(this, 5 * 1000, false);
1174       }
1175     }
1176 
1177     PeriodicTask::real_time_tick(time_to_wait);
1178 
1179     // If we have no more tasks left due to dynamic disenrollment,
1180     // shut down the thread since we don't currently support dynamic enrollment
1181     if (PeriodicTask::num_tasks() == 0) {
1182       _should_terminate = true;
1183     }
1184   }
1185 
1186   // Signal that it is terminated
1187   {
1188     MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1189     _watcher_thread = NULL;
1190     Terminator_lock->notify();
1191   }
1192 
1193   // Thread destructor usually does this..
1194   ThreadLocalStorage::set_thread(NULL);
1195 }
1196 
1197 void WatcherThread::start() {
1198   if (watcher_thread() == NULL) {
1199     _should_terminate = false;
1200     // Create the single instance of WatcherThread
1201     new WatcherThread();
1202   }
1203 }
1204 
1205 void WatcherThread::stop() {
1206   // it is ok to take late safepoints here, if needed
1207   MutexLocker mu(Terminator_lock);
1208   _should_terminate = true;
1209   OrderAccess::fence();  // ensure WatcherThread sees update in main loop
1210 
1211   Thread* watcher = watcher_thread();
1212   if (watcher != NULL)
1213     watcher->_SleepEvent->unpark();
1214 
1215   while(watcher_thread() != NULL) {
1216     // This wait should make safepoint checks, wait without a timeout,
1217     // and wait as a suspend-equivalent condition.
1218     //
1219     // Note: If the FlatProfiler is running, then this thread is waiting
1220     // for the WatcherThread to terminate and the WatcherThread, via the
1221     // FlatProfiler task, is waiting for the external suspend request on
1222     // this thread to complete. wait_for_ext_suspend_completion() will
1223     // eventually timeout, but that takes time. Making this wait a
1224     // suspend-equivalent condition solves that timeout problem.
1225     //
1226     Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1227                           Mutex::_as_suspend_equivalent_flag);
1228   }
1229 }
1230 
1231 void WatcherThread::print_on(outputStream* st) const {
1232   st->print("\"%s\" ", name());
1233   Thread::print_on(st);
1234   st->cr();
1235 }
1236 
1237 // ======= JavaThread ========
1238 
1239 // A JavaThread is a normal Java thread
1240 
1241 void JavaThread::initialize() {
1242   // Initialize fields
1243 
1244   // Set the claimed par_id to -1 (ie not claiming any par_ids)
1245   set_claimed_par_id(-1);
1246 
1247   set_saved_exception_pc(NULL);
1248   set_threadObj(NULL);
1249   _anchor.clear();
1250   set_entry_point(NULL);
1251   set_jni_functions(jni_functions());
1252   set_callee_target(NULL);
1253   set_vm_result(NULL);
1254   set_vm_result_2(NULL);
1255   set_vframe_array_head(NULL);
1256   set_vframe_array_last(NULL);
1257   set_deferred_locals(NULL);
1258   set_deopt_mark(NULL);
1259   set_deopt_nmethod(NULL);
1260   clear_must_deopt_id();
1261   set_monitor_chunks(NULL);
1262   set_next(NULL);
1263   set_thread_state(_thread_new);
1264   _terminated = _not_terminated;
1265   _privileged_stack_top = NULL;
1266   _array_for_gc = NULL;
1267   _suspend_equivalent = false;
1268   _in_deopt_handler = 0;
1269   _doing_unsafe_access = false;
1270   _stack_guard_state = stack_guard_unused;
1271   _exception_oop = NULL;
1272   _exception_pc  = 0;
1273   _exception_handler_pc = 0;
1274   _exception_stack_size = 0;
1275   _is_method_handle_return = 0;
1276   _jvmti_thread_state= NULL;
1277   _should_post_on_exceptions_flag = JNI_FALSE;
1278   _jvmti_get_loaded_classes_closure = NULL;
1279   _interp_only_mode    = 0;
1280   _special_runtime_exit_condition = _no_async_condition;
1281   _pending_async_exception = NULL;
1282   _is_compiling = false;
1283   _thread_stat = NULL;
1284   _thread_stat = new ThreadStatistics();
1285   _blocked_on_compilation = false;
1286   _jni_active_critical = 0;
1287   _do_not_unlock_if_synchronized = false;
1288   _cached_monitor_info = NULL;
1289   _parker = Parker::Allocate(this) ;
1290 
1291 #ifndef PRODUCT
1292   _jmp_ring_index = 0;
1293   for (int ji = 0 ; ji < jump_ring_buffer_size ; ji++ ) {
1294     record_jump(NULL, NULL, NULL, 0);
1295   }
1296 #endif /* PRODUCT */
1297 
1298   set_thread_profiler(NULL);
1299   if (FlatProfiler::is_active()) {
1300     // This is where we would decide to either give each thread it's own profiler
1301     // or use one global one from FlatProfiler,
1302     // or up to some count of the number of profiled threads, etc.
1303     ThreadProfiler* pp = new ThreadProfiler();
1304     pp->engage();
1305     set_thread_profiler(pp);
1306   }
1307 
1308   // Setup safepoint state info for this thread
1309   ThreadSafepointState::create(this);
1310 
1311   debug_only(_java_call_counter = 0);
1312 
1313   // JVMTI PopFrame support
1314   _popframe_condition = popframe_inactive;
1315   _popframe_preserved_args = NULL;
1316   _popframe_preserved_args_size = 0;
1317 
1318   pd_initialize();
1319 }
1320 
1321 #ifndef SERIALGC
1322 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1323 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1324 #endif // !SERIALGC
1325 
1326 JavaThread::JavaThread(bool is_attaching) :
1327   Thread()
1328 #ifndef SERIALGC
1329   , _satb_mark_queue(&_satb_mark_queue_set),
1330   _dirty_card_queue(&_dirty_card_queue_set)
1331 #endif // !SERIALGC
1332 {
1333   initialize();
1334   _is_attaching = is_attaching;
1335   assert(_deferred_card_mark.is_empty(), "Default MemRegion ctor");
1336 }
1337 
1338 bool JavaThread::reguard_stack(address cur_sp) {
1339   if (_stack_guard_state != stack_guard_yellow_disabled) {
1340     return true; // Stack already guarded or guard pages not needed.
1341   }
1342 
1343   if (register_stack_overflow()) {
1344     // For those architectures which have separate register and
1345     // memory stacks, we must check the register stack to see if
1346     // it has overflowed.
1347     return false;
1348   }
1349 
1350   // Java code never executes within the yellow zone: the latter is only
1351   // there to provoke an exception during stack banging.  If java code
1352   // is executing there, either StackShadowPages should be larger, or
1353   // some exception code in c1, c2 or the interpreter isn't unwinding
1354   // when it should.
1355   guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages");
1356 
1357   enable_stack_yellow_zone();
1358   return true;
1359 }
1360 
1361 bool JavaThread::reguard_stack(void) {
1362   return reguard_stack(os::current_stack_pointer());
1363 }
1364 
1365 
1366 void JavaThread::block_if_vm_exited() {
1367   if (_terminated == _vm_exited) {
1368     // _vm_exited is set at safepoint, and Threads_lock is never released
1369     // we will block here forever
1370     Threads_lock->lock_without_safepoint_check();
1371     ShouldNotReachHere();
1372   }
1373 }
1374 
1375 
1376 // Remove this ifdef when C1 is ported to the compiler interface.
1377 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1378 
1379 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1380   Thread()
1381 #ifndef SERIALGC
1382   , _satb_mark_queue(&_satb_mark_queue_set),
1383   _dirty_card_queue(&_dirty_card_queue_set)
1384 #endif // !SERIALGC
1385 {
1386   if (TraceThreadEvents) {
1387     tty->print_cr("creating thread %p", this);
1388   }
1389   initialize();
1390   _is_attaching = false;
1391   set_entry_point(entry_point);
1392   // Create the native thread itself.
1393   // %note runtime_23
1394   os::ThreadType thr_type = os::java_thread;
1395   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1396                                                      os::java_thread;
1397   os::create_thread(this, thr_type, stack_sz);
1398 
1399   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1400   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1401   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1402   // the exception consists of creating the exception object & initializing it, initialization
1403   // will leave the VM via a JavaCall and then all locks must be unlocked).
1404   //
1405   // The thread is still suspended when we reach here. Thread must be explicit started
1406   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1407   // by calling Threads:add. The reason why this is not done here, is because the thread
1408   // object must be fully initialized (take a look at JVM_Start)
1409 }
1410 
1411 JavaThread::~JavaThread() {
1412   if (TraceThreadEvents) {
1413       tty->print_cr("terminate thread %p", this);
1414   }
1415 
1416   // JSR166 -- return the parker to the free list
1417   Parker::Release(_parker);
1418   _parker = NULL ;
1419 
1420   // Free any remaining  previous UnrollBlock
1421   vframeArray* old_array = vframe_array_last();
1422 
1423   if (old_array != NULL) {
1424     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1425     old_array->set_unroll_block(NULL);
1426     delete old_info;
1427     delete old_array;
1428   }
1429 
1430   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1431   if (deferred != NULL) {
1432     // This can only happen if thread is destroyed before deoptimization occurs.
1433     assert(deferred->length() != 0, "empty array!");
1434     do {
1435       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1436       deferred->remove_at(0);
1437       // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1438       delete dlv;
1439     } while (deferred->length() != 0);
1440     delete deferred;
1441   }
1442 
1443   // All Java related clean up happens in exit
1444   ThreadSafepointState::destroy(this);
1445   if (_thread_profiler != NULL) delete _thread_profiler;
1446   if (_thread_stat != NULL) delete _thread_stat;
1447 }
1448 
1449 
1450 // The first routine called by a new Java thread
1451 void JavaThread::run() {
1452   // initialize thread-local alloc buffer related fields
1453   this->initialize_tlab();
1454 
1455   // used to test validitity of stack trace backs
1456   this->record_base_of_stack_pointer();
1457 
1458   // Record real stack base and size.
1459   this->record_stack_base_and_size();
1460 
1461   // Initialize thread local storage; set before calling MutexLocker
1462   this->initialize_thread_local_storage();
1463 
1464   this->create_stack_guard_pages();
1465 
1466   this->cache_global_variables();
1467 
1468   // Thread is now sufficient initialized to be handled by the safepoint code as being
1469   // in the VM. Change thread state from _thread_new to _thread_in_vm
1470   ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1471 
1472   assert(JavaThread::current() == this, "sanity check");
1473   assert(!Thread::current()->owns_locks(), "sanity check");
1474 
1475   DTRACE_THREAD_PROBE(start, this);
1476 
1477   // This operation might block. We call that after all safepoint checks for a new thread has
1478   // been completed.
1479   this->set_active_handles(JNIHandleBlock::allocate_block());
1480 
1481   if (JvmtiExport::should_post_thread_life()) {
1482     JvmtiExport::post_thread_start(this);
1483   }
1484 
1485   // We call another function to do the rest so we are sure that the stack addresses used
1486   // from there will be lower than the stack base just computed
1487   thread_main_inner();
1488 
1489   // Note, thread is no longer valid at this point!
1490 }
1491 
1492 
1493 void JavaThread::thread_main_inner() {
1494   assert(JavaThread::current() == this, "sanity check");
1495   assert(this->threadObj() != NULL, "just checking");
1496 
1497   // Execute thread entry point unless this thread has a pending exception
1498   // or has been stopped before starting.
1499   // Note: Due to JVM_StopThread we can have pending exceptions already!
1500   if (!this->has_pending_exception() &&
1501       !java_lang_Thread::is_stillborn(this->threadObj())) {
1502     HandleMark hm(this);
1503     this->entry_point()(this, this);
1504   }
1505 
1506   DTRACE_THREAD_PROBE(stop, this);
1507 
1508   this->exit(false);
1509   delete this;
1510 }
1511 
1512 
1513 static void ensure_join(JavaThread* thread) {
1514   // We do not need to grap the Threads_lock, since we are operating on ourself.
1515   Handle threadObj(thread, thread->threadObj());
1516   assert(threadObj.not_null(), "java thread object must exist");
1517   ObjectLocker lock(threadObj, thread);
1518   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1519   thread->clear_pending_exception();
1520   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1521   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1522   // Clear the native thread instance - this makes isAlive return false and allows the join()
1523   // to complete once we've done the notify_all below
1524   java_lang_Thread::set_thread(threadObj(), NULL);
1525   lock.notify_all(thread);
1526   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1527   thread->clear_pending_exception();
1528 }
1529 
1530 
1531 // For any new cleanup additions, please check to see if they need to be applied to
1532 // cleanup_failed_attach_current_thread as well.
1533 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1534   assert(this == JavaThread::current(),  "thread consistency check");
1535   if (!InitializeJavaLangSystem) return;
1536 
1537   HandleMark hm(this);
1538   Handle uncaught_exception(this, this->pending_exception());
1539   this->clear_pending_exception();
1540   Handle threadObj(this, this->threadObj());
1541   assert(threadObj.not_null(), "Java thread object should be created");
1542 
1543   if (get_thread_profiler() != NULL) {
1544     get_thread_profiler()->disengage();
1545     ResourceMark rm;
1546     get_thread_profiler()->print(get_thread_name());
1547   }
1548 
1549 
1550   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1551   {
1552     EXCEPTION_MARK;
1553 
1554     CLEAR_PENDING_EXCEPTION;
1555   }
1556   // FIXIT: The is_null check is only so it works better on JDK1.2 VM's. This
1557   // has to be fixed by a runtime query method
1558   if (!destroy_vm || JDK_Version::is_jdk12x_version()) {
1559     // JSR-166: change call from from ThreadGroup.uncaughtException to
1560     // java.lang.Thread.dispatchUncaughtException
1561     if (uncaught_exception.not_null()) {
1562       Handle group(this, java_lang_Thread::threadGroup(threadObj()));
1563       Events::log("uncaught exception INTPTR_FORMAT " " INTPTR_FORMAT " " INTPTR_FORMAT",
1564         (address)uncaught_exception(), (address)threadObj(), (address)group());
1565       {
1566         EXCEPTION_MARK;
1567         // Check if the method Thread.dispatchUncaughtException() exists. If so
1568         // call it.  Otherwise we have an older library without the JSR-166 changes,
1569         // so call ThreadGroup.uncaughtException()
1570         KlassHandle recvrKlass(THREAD, threadObj->klass());
1571         CallInfo callinfo;
1572         KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1573         LinkResolver::resolve_virtual_call(callinfo, threadObj, recvrKlass, thread_klass,
1574                                            vmSymbols::dispatchUncaughtException_name(),
1575                                            vmSymbols::throwable_void_signature(),
1576                                            KlassHandle(), false, false, THREAD);
1577         CLEAR_PENDING_EXCEPTION;
1578         methodHandle method = callinfo.selected_method();
1579         if (method.not_null()) {
1580           JavaValue result(T_VOID);
1581           JavaCalls::call_virtual(&result,
1582                                   threadObj, thread_klass,
1583                                   vmSymbols::dispatchUncaughtException_name(),
1584                                   vmSymbols::throwable_void_signature(),
1585                                   uncaught_exception,
1586                                   THREAD);
1587         } else {
1588           KlassHandle thread_group(THREAD, SystemDictionary::ThreadGroup_klass());
1589           JavaValue result(T_VOID);
1590           JavaCalls::call_virtual(&result,
1591                                   group, thread_group,
1592                                   vmSymbols::uncaughtException_name(),
1593                                   vmSymbols::thread_throwable_void_signature(),
1594                                   threadObj,           // Arg 1
1595                                   uncaught_exception,  // Arg 2
1596                                   THREAD);
1597         }
1598         CLEAR_PENDING_EXCEPTION;
1599       }
1600     }
1601 
1602     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1603     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1604     // is deprecated anyhow.
1605     { int count = 3;
1606       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1607         EXCEPTION_MARK;
1608         JavaValue result(T_VOID);
1609         KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1610         JavaCalls::call_virtual(&result,
1611                               threadObj, thread_klass,
1612                               vmSymbols::exit_method_name(),
1613                               vmSymbols::void_method_signature(),
1614                               THREAD);
1615         CLEAR_PENDING_EXCEPTION;
1616       }
1617     }
1618 
1619     // notify JVMTI
1620     if (JvmtiExport::should_post_thread_life()) {
1621       JvmtiExport::post_thread_end(this);
1622     }
1623 
1624     // We have notified the agents that we are exiting, before we go on,
1625     // we must check for a pending external suspend request and honor it
1626     // in order to not surprise the thread that made the suspend request.
1627     while (true) {
1628       {
1629         MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1630         if (!is_external_suspend()) {
1631           set_terminated(_thread_exiting);
1632           ThreadService::current_thread_exiting(this);
1633           break;
1634         }
1635         // Implied else:
1636         // Things get a little tricky here. We have a pending external
1637         // suspend request, but we are holding the SR_lock so we
1638         // can't just self-suspend. So we temporarily drop the lock
1639         // and then self-suspend.
1640       }
1641 
1642       ThreadBlockInVM tbivm(this);
1643       java_suspend_self();
1644 
1645       // We're done with this suspend request, but we have to loop around
1646       // and check again. Eventually we will get SR_lock without a pending
1647       // external suspend request and will be able to mark ourselves as
1648       // exiting.
1649     }
1650     // no more external suspends are allowed at this point
1651   } else {
1652     // before_exit() has already posted JVMTI THREAD_END events
1653   }
1654 
1655   // Notify waiters on thread object. This has to be done after exit() is called
1656   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1657   // group should have the destroyed bit set before waiters are notified).
1658   ensure_join(this);
1659   assert(!this->has_pending_exception(), "ensure_join should have cleared");
1660 
1661   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1662   // held by this thread must be released.  A detach operation must only
1663   // get here if there are no Java frames on the stack.  Therefore, any
1664   // owned monitors at this point MUST be JNI-acquired monitors which are
1665   // pre-inflated and in the monitor cache.
1666   //
1667   // ensure_join() ignores IllegalThreadStateExceptions, and so does this.
1668   if (exit_type == jni_detach && JNIDetachReleasesMonitors) {
1669     assert(!this->has_last_Java_frame(), "detaching with Java frames?");
1670     ObjectSynchronizer::release_monitors_owned_by_thread(this);
1671     assert(!this->has_pending_exception(), "release_monitors should have cleared");
1672   }
1673 
1674   // These things needs to be done while we are still a Java Thread. Make sure that thread
1675   // is in a consistent state, in case GC happens
1676   assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1677 
1678   if (active_handles() != NULL) {
1679     JNIHandleBlock* block = active_handles();
1680     set_active_handles(NULL);
1681     JNIHandleBlock::release_block(block);
1682   }
1683 
1684   if (free_handle_block() != NULL) {
1685     JNIHandleBlock* block = free_handle_block();
1686     set_free_handle_block(NULL);
1687     JNIHandleBlock::release_block(block);
1688   }
1689 
1690   // These have to be removed while this is still a valid thread.
1691   remove_stack_guard_pages();
1692 
1693   if (UseTLAB) {
1694     tlab().make_parsable(true);  // retire TLAB
1695   }
1696 
1697   if (JvmtiEnv::environments_might_exist()) {
1698     JvmtiExport::cleanup_thread(this);
1699   }
1700 
1701 #ifndef SERIALGC
1702   // We must flush G1-related buffers before removing a thread from
1703   // the list of active threads.
1704   if (UseG1GC) {
1705     flush_barrier_queues();
1706   }
1707 #endif
1708 
1709   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1710   Threads::remove(this);
1711 }
1712 
1713 #ifndef SERIALGC
1714 // Flush G1-related queues.
1715 void JavaThread::flush_barrier_queues() {
1716   satb_mark_queue().flush();
1717   dirty_card_queue().flush();
1718 }
1719 
1720 void JavaThread::initialize_queues() {
1721   assert(!SafepointSynchronize::is_at_safepoint(),
1722          "we should not be at a safepoint");
1723 
1724   ObjPtrQueue& satb_queue = satb_mark_queue();
1725   SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1726   // The SATB queue should have been constructed with its active
1727   // field set to false.
1728   assert(!satb_queue.is_active(), "SATB queue should not be active");
1729   assert(satb_queue.is_empty(), "SATB queue should be empty");
1730   // If we are creating the thread during a marking cycle, we should
1731   // set the active field of the SATB queue to true.
1732   if (satb_queue_set.is_active()) {
1733     satb_queue.set_active(true);
1734   }
1735 
1736   DirtyCardQueue& dirty_queue = dirty_card_queue();
1737   // The dirty card queue should have been constructed with its
1738   // active field set to true.
1739   assert(dirty_queue.is_active(), "dirty card queue should be active");
1740 }
1741 #endif // !SERIALGC
1742 
1743 void JavaThread::cleanup_failed_attach_current_thread() {
1744   if (get_thread_profiler() != NULL) {
1745     get_thread_profiler()->disengage();
1746     ResourceMark rm;
1747     get_thread_profiler()->print(get_thread_name());
1748   }
1749 
1750   if (active_handles() != NULL) {
1751     JNIHandleBlock* block = active_handles();
1752     set_active_handles(NULL);
1753     JNIHandleBlock::release_block(block);
1754   }
1755 
1756   if (free_handle_block() != NULL) {
1757     JNIHandleBlock* block = free_handle_block();
1758     set_free_handle_block(NULL);
1759     JNIHandleBlock::release_block(block);
1760   }
1761 
1762   // These have to be removed while this is still a valid thread.
1763   remove_stack_guard_pages();
1764 
1765   if (UseTLAB) {
1766     tlab().make_parsable(true);  // retire TLAB, if any
1767   }
1768 
1769 #ifndef SERIALGC
1770   if (UseG1GC) {
1771     flush_barrier_queues();
1772   }
1773 #endif
1774 
1775   Threads::remove(this);
1776   delete this;
1777 }
1778 
1779 
1780 
1781 
1782 JavaThread* JavaThread::active() {
1783   Thread* thread = ThreadLocalStorage::thread();
1784   assert(thread != NULL, "just checking");
1785   if (thread->is_Java_thread()) {
1786     return (JavaThread*) thread;
1787   } else {
1788     assert(thread->is_VM_thread(), "this must be a vm thread");
1789     VM_Operation* op = ((VMThread*) thread)->vm_operation();
1790     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
1791     assert(ret->is_Java_thread(), "must be a Java thread");
1792     return ret;
1793   }
1794 }
1795 
1796 bool JavaThread::is_lock_owned(address adr) const {
1797   if (Thread::is_lock_owned(adr)) return true;
1798 
1799   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
1800     if (chunk->contains(adr)) return true;
1801   }
1802 
1803   return false;
1804 }
1805 
1806 
1807 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
1808   chunk->set_next(monitor_chunks());
1809   set_monitor_chunks(chunk);
1810 }
1811 
1812 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
1813   guarantee(monitor_chunks() != NULL, "must be non empty");
1814   if (monitor_chunks() == chunk) {
1815     set_monitor_chunks(chunk->next());
1816   } else {
1817     MonitorChunk* prev = monitor_chunks();
1818     while (prev->next() != chunk) prev = prev->next();
1819     prev->set_next(chunk->next());
1820   }
1821 }
1822 
1823 // JVM support.
1824 
1825 // Note: this function shouldn't block if it's called in
1826 // _thread_in_native_trans state (such as from
1827 // check_special_condition_for_native_trans()).
1828 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
1829 
1830   if (has_last_Java_frame() && has_async_condition()) {
1831     // If we are at a polling page safepoint (not a poll return)
1832     // then we must defer async exception because live registers
1833     // will be clobbered by the exception path. Poll return is
1834     // ok because the call we a returning from already collides
1835     // with exception handling registers and so there is no issue.
1836     // (The exception handling path kills call result registers but
1837     //  this is ok since the exception kills the result anyway).
1838 
1839     if (is_at_poll_safepoint()) {
1840       // if the code we are returning to has deoptimized we must defer
1841       // the exception otherwise live registers get clobbered on the
1842       // exception path before deoptimization is able to retrieve them.
1843       //
1844       RegisterMap map(this, false);
1845       frame caller_fr = last_frame().sender(&map);
1846       assert(caller_fr.is_compiled_frame(), "what?");
1847       if (caller_fr.is_deoptimized_frame()) {
1848         if (TraceExceptions) {
1849           ResourceMark rm;
1850           tty->print_cr("deferred async exception at compiled safepoint");
1851         }
1852         return;
1853       }
1854     }
1855   }
1856 
1857   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
1858   if (condition == _no_async_condition) {
1859     // Conditions have changed since has_special_runtime_exit_condition()
1860     // was called:
1861     // - if we were here only because of an external suspend request,
1862     //   then that was taken care of above (or cancelled) so we are done
1863     // - if we were here because of another async request, then it has
1864     //   been cleared between the has_special_runtime_exit_condition()
1865     //   and now so again we are done
1866     return;
1867   }
1868 
1869   // Check for pending async. exception
1870   if (_pending_async_exception != NULL) {
1871     // Only overwrite an already pending exception, if it is not a threadDeath.
1872     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
1873 
1874       // We cannot call Exceptions::_throw(...) here because we cannot block
1875       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
1876 
1877       if (TraceExceptions) {
1878         ResourceMark rm;
1879         tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this);
1880         if (has_last_Java_frame() ) {
1881           frame f = last_frame();
1882           tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp());
1883         }
1884         tty->print_cr(" of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name());
1885       }
1886       _pending_async_exception = NULL;
1887       clear_has_async_exception();
1888     }
1889   }
1890 
1891   if (check_unsafe_error &&
1892       condition == _async_unsafe_access_error && !has_pending_exception()) {
1893     condition = _no_async_condition;  // done
1894     switch (thread_state()) {
1895     case _thread_in_vm:
1896       {
1897         JavaThread* THREAD = this;
1898         THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
1899       }
1900     case _thread_in_native:
1901       {
1902         ThreadInVMfromNative tiv(this);
1903         JavaThread* THREAD = this;
1904         THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
1905       }
1906     case _thread_in_Java:
1907       {
1908         ThreadInVMfromJava tiv(this);
1909         JavaThread* THREAD = this;
1910         THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
1911       }
1912     default:
1913       ShouldNotReachHere();
1914     }
1915   }
1916 
1917   assert(condition == _no_async_condition || has_pending_exception() ||
1918          (!check_unsafe_error && condition == _async_unsafe_access_error),
1919          "must have handled the async condition, if no exception");
1920 }
1921 
1922 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
1923   //
1924   // Check for pending external suspend. Internal suspend requests do
1925   // not use handle_special_runtime_exit_condition().
1926   // If JNIEnv proxies are allowed, don't self-suspend if the target
1927   // thread is not the current thread. In older versions of jdbx, jdbx
1928   // threads could call into the VM with another thread's JNIEnv so we
1929   // can be here operating on behalf of a suspended thread (4432884).
1930   bool do_self_suspend = is_external_suspend_with_lock();
1931   if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
1932     //
1933     // Because thread is external suspended the safepoint code will count
1934     // thread as at a safepoint. This can be odd because we can be here
1935     // as _thread_in_Java which would normally transition to _thread_blocked
1936     // at a safepoint. We would like to mark the thread as _thread_blocked
1937     // before calling java_suspend_self like all other callers of it but
1938     // we must then observe proper safepoint protocol. (We can't leave
1939     // _thread_blocked with a safepoint in progress). However we can be
1940     // here as _thread_in_native_trans so we can't use a normal transition
1941     // constructor/destructor pair because they assert on that type of
1942     // transition. We could do something like:
1943     //
1944     // JavaThreadState state = thread_state();
1945     // set_thread_state(_thread_in_vm);
1946     // {
1947     //   ThreadBlockInVM tbivm(this);
1948     //   java_suspend_self()
1949     // }
1950     // set_thread_state(_thread_in_vm_trans);
1951     // if (safepoint) block;
1952     // set_thread_state(state);
1953     //
1954     // but that is pretty messy. Instead we just go with the way the
1955     // code has worked before and note that this is the only path to
1956     // java_suspend_self that doesn't put the thread in _thread_blocked
1957     // mode.
1958 
1959     frame_anchor()->make_walkable(this);
1960     java_suspend_self();
1961 
1962     // We might be here for reasons in addition to the self-suspend request
1963     // so check for other async requests.
1964   }
1965 
1966   if (check_asyncs) {
1967     check_and_handle_async_exceptions();
1968   }
1969 }
1970 
1971 void JavaThread::send_thread_stop(oop java_throwable)  {
1972   assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
1973   assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
1974   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
1975 
1976   // Do not throw asynchronous exceptions against the compiler thread
1977   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
1978   if (is_Compiler_thread()) return;
1979 
1980   {
1981     // Actually throw the Throwable against the target Thread - however
1982     // only if there is no thread death exception installed already.
1983     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
1984       // If the topmost frame is a runtime stub, then we are calling into
1985       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
1986       // must deoptimize the caller before continuing, as the compiled  exception handler table
1987       // may not be valid
1988       if (has_last_Java_frame()) {
1989         frame f = last_frame();
1990         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
1991           // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
1992           RegisterMap reg_map(this, UseBiasedLocking);
1993           frame compiled_frame = f.sender(&reg_map);
1994           if (compiled_frame.can_be_deoptimized()) {
1995             Deoptimization::deoptimize(this, compiled_frame, &reg_map);
1996           }
1997         }
1998       }
1999 
2000       // Set async. pending exception in thread.
2001       set_pending_async_exception(java_throwable);
2002 
2003       if (TraceExceptions) {
2004        ResourceMark rm;
2005        tty->print_cr("Pending Async. exception installed of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name());
2006       }
2007       // for AbortVMOnException flag
2008       NOT_PRODUCT(Exceptions::debug_check_abort(instanceKlass::cast(_pending_async_exception->klass())->external_name()));
2009     }
2010   }
2011 
2012 
2013   // Interrupt thread so it will wake up from a potential wait()
2014   Thread::interrupt(this);
2015 }
2016 
2017 // External suspension mechanism.
2018 //
2019 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2020 // to any VM_locks and it is at a transition
2021 // Self-suspension will happen on the transition out of the vm.
2022 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2023 //
2024 // Guarantees on return:
2025 //   + Target thread will not execute any new bytecode (that's why we need to
2026 //     force a safepoint)
2027 //   + Target thread will not enter any new monitors
2028 //
2029 void JavaThread::java_suspend() {
2030   { MutexLocker mu(Threads_lock);
2031     if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2032        return;
2033     }
2034   }
2035 
2036   { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2037     if (!is_external_suspend()) {
2038       // a racing resume has cancelled us; bail out now
2039       return;
2040     }
2041 
2042     // suspend is done
2043     uint32_t debug_bits = 0;
2044     // Warning: is_ext_suspend_completed() may temporarily drop the
2045     // SR_lock to allow the thread to reach a stable thread state if
2046     // it is currently in a transient thread state.
2047     if (is_ext_suspend_completed(false /* !called_by_wait */,
2048                                  SuspendRetryDelay, &debug_bits) ) {
2049       return;
2050     }
2051   }
2052 
2053   VM_ForceSafepoint vm_suspend;
2054   VMThread::execute(&vm_suspend);
2055 }
2056 
2057 // Part II of external suspension.
2058 // A JavaThread self suspends when it detects a pending external suspend
2059 // request. This is usually on transitions. It is also done in places
2060 // where continuing to the next transition would surprise the caller,
2061 // e.g., monitor entry.
2062 //
2063 // Returns the number of times that the thread self-suspended.
2064 //
2065 // Note: DO NOT call java_suspend_self() when you just want to block current
2066 //       thread. java_suspend_self() is the second stage of cooperative
2067 //       suspension for external suspend requests and should only be used
2068 //       to complete an external suspend request.
2069 //
2070 int JavaThread::java_suspend_self() {
2071   int ret = 0;
2072 
2073   // we are in the process of exiting so don't suspend
2074   if (is_exiting()) {
2075      clear_external_suspend();
2076      return ret;
2077   }
2078 
2079   assert(_anchor.walkable() ||
2080     (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2081     "must have walkable stack");
2082 
2083   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2084 
2085   assert(!this->is_ext_suspended(),
2086     "a thread trying to self-suspend should not already be suspended");
2087 
2088   if (this->is_suspend_equivalent()) {
2089     // If we are self-suspending as a result of the lifting of a
2090     // suspend equivalent condition, then the suspend_equivalent
2091     // flag is not cleared until we set the ext_suspended flag so
2092     // that wait_for_ext_suspend_completion() returns consistent
2093     // results.
2094     this->clear_suspend_equivalent();
2095   }
2096 
2097   // A racing resume may have cancelled us before we grabbed SR_lock
2098   // above. Or another external suspend request could be waiting for us
2099   // by the time we return from SR_lock()->wait(). The thread
2100   // that requested the suspension may already be trying to walk our
2101   // stack and if we return now, we can change the stack out from under
2102   // it. This would be a "bad thing (TM)" and cause the stack walker
2103   // to crash. We stay self-suspended until there are no more pending
2104   // external suspend requests.
2105   while (is_external_suspend()) {
2106     ret++;
2107     this->set_ext_suspended();
2108 
2109     // _ext_suspended flag is cleared by java_resume()
2110     while (is_ext_suspended()) {
2111       this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2112     }
2113   }
2114 
2115   return ret;
2116 }
2117 
2118 #ifdef ASSERT
2119 // verify the JavaThread has not yet been published in the Threads::list, and
2120 // hence doesn't need protection from concurrent access at this stage
2121 void JavaThread::verify_not_published() {
2122   if (!Threads_lock->owned_by_self()) {
2123    MutexLockerEx ml(Threads_lock,  Mutex::_no_safepoint_check_flag);
2124    assert( !Threads::includes(this),
2125            "java thread shouldn't have been published yet!");
2126   }
2127   else {
2128    assert( !Threads::includes(this),
2129            "java thread shouldn't have been published yet!");
2130   }
2131 }
2132 #endif
2133 
2134 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2135 // progress or when _suspend_flags is non-zero.
2136 // Current thread needs to self-suspend if there is a suspend request and/or
2137 // block if a safepoint is in progress.
2138 // Async exception ISN'T checked.
2139 // Note only the ThreadInVMfromNative transition can call this function
2140 // directly and when thread state is _thread_in_native_trans
2141 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2142   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2143 
2144   JavaThread *curJT = JavaThread::current();
2145   bool do_self_suspend = thread->is_external_suspend();
2146 
2147   assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2148 
2149   // If JNIEnv proxies are allowed, don't self-suspend if the target
2150   // thread is not the current thread. In older versions of jdbx, jdbx
2151   // threads could call into the VM with another thread's JNIEnv so we
2152   // can be here operating on behalf of a suspended thread (4432884).
2153   if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2154     JavaThreadState state = thread->thread_state();
2155 
2156     // We mark this thread_blocked state as a suspend-equivalent so
2157     // that a caller to is_ext_suspend_completed() won't be confused.
2158     // The suspend-equivalent state is cleared by java_suspend_self().
2159     thread->set_suspend_equivalent();
2160 
2161     // If the safepoint code sees the _thread_in_native_trans state, it will
2162     // wait until the thread changes to other thread state. There is no
2163     // guarantee on how soon we can obtain the SR_lock and complete the
2164     // self-suspend request. It would be a bad idea to let safepoint wait for
2165     // too long. Temporarily change the state to _thread_blocked to
2166     // let the VM thread know that this thread is ready for GC. The problem
2167     // of changing thread state is that safepoint could happen just after
2168     // java_suspend_self() returns after being resumed, and VM thread will
2169     // see the _thread_blocked state. We must check for safepoint
2170     // after restoring the state and make sure we won't leave while a safepoint
2171     // is in progress.
2172     thread->set_thread_state(_thread_blocked);
2173     thread->java_suspend_self();
2174     thread->set_thread_state(state);
2175     // Make sure new state is seen by VM thread
2176     if (os::is_MP()) {
2177       if (UseMembar) {
2178         // Force a fence between the write above and read below
2179         OrderAccess::fence();
2180       } else {
2181         // Must use this rather than serialization page in particular on Windows
2182         InterfaceSupport::serialize_memory(thread);
2183       }
2184     }
2185   }
2186 
2187   if (SafepointSynchronize::do_call_back()) {
2188     // If we are safepointing, then block the caller which may not be
2189     // the same as the target thread (see above).
2190     SafepointSynchronize::block(curJT);
2191   }
2192 
2193   if (thread->is_deopt_suspend()) {
2194     thread->clear_deopt_suspend();
2195     RegisterMap map(thread, false);
2196     frame f = thread->last_frame();
2197     while ( f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2198       f = f.sender(&map);
2199     }
2200     if (f.id() == thread->must_deopt_id()) {
2201       thread->clear_must_deopt_id();
2202       f.deoptimize(thread);
2203     } else {
2204       fatal("missed deoptimization!");
2205     }
2206   }
2207 }
2208 
2209 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2210 // progress or when _suspend_flags is non-zero.
2211 // Current thread needs to self-suspend if there is a suspend request and/or
2212 // block if a safepoint is in progress.
2213 // Also check for pending async exception (not including unsafe access error).
2214 // Note only the native==>VM/Java barriers can call this function and when
2215 // thread state is _thread_in_native_trans.
2216 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2217   check_safepoint_and_suspend_for_native_trans(thread);
2218 
2219   if (thread->has_async_exception()) {
2220     // We are in _thread_in_native_trans state, don't handle unsafe
2221     // access error since that may block.
2222     thread->check_and_handle_async_exceptions(false);
2223   }
2224 }
2225 
2226 // We need to guarantee the Threads_lock here, since resumes are not
2227 // allowed during safepoint synchronization
2228 // Can only resume from an external suspension
2229 void JavaThread::java_resume() {
2230   assert_locked_or_safepoint(Threads_lock);
2231 
2232   // Sanity check: thread is gone, has started exiting or the thread
2233   // was not externally suspended.
2234   if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2235     return;
2236   }
2237 
2238   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2239 
2240   clear_external_suspend();
2241 
2242   if (is_ext_suspended()) {
2243     clear_ext_suspended();
2244     SR_lock()->notify_all();
2245   }
2246 }
2247 
2248 void JavaThread::create_stack_guard_pages() {
2249   if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return;
2250   address low_addr = stack_base() - stack_size();
2251   size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2252 
2253   int allocate = os::allocate_stack_guard_pages();
2254   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2255 
2256   if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) {
2257     warning("Attempt to allocate stack guard pages failed.");
2258     return;
2259   }
2260 
2261   if (os::guard_memory((char *) low_addr, len)) {
2262     _stack_guard_state = stack_guard_enabled;
2263   } else {
2264     warning("Attempt to protect stack guard pages failed.");
2265     if (os::uncommit_memory((char *) low_addr, len)) {
2266       warning("Attempt to deallocate stack guard pages failed.");
2267     }
2268   }
2269 }
2270 
2271 void JavaThread::remove_stack_guard_pages() {
2272   if (_stack_guard_state == stack_guard_unused) return;
2273   address low_addr = stack_base() - stack_size();
2274   size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2275 
2276   if (os::allocate_stack_guard_pages()) {
2277     if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2278       _stack_guard_state = stack_guard_unused;
2279     } else {
2280       warning("Attempt to deallocate stack guard pages failed.");
2281     }
2282   } else {
2283     if (_stack_guard_state == stack_guard_unused) return;
2284     if (os::unguard_memory((char *) low_addr, len)) {
2285       _stack_guard_state = stack_guard_unused;
2286     } else {
2287         warning("Attempt to unprotect stack guard pages failed.");
2288     }
2289   }
2290 }
2291 
2292 void JavaThread::enable_stack_yellow_zone() {
2293   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2294   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2295 
2296   // The base notation is from the stacks point of view, growing downward.
2297   // We need to adjust it to work correctly with guard_memory()
2298   address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2299 
2300   guarantee(base < stack_base(),"Error calculating stack yellow zone");
2301   guarantee(base < os::current_stack_pointer(),"Error calculating stack yellow zone");
2302 
2303   if (os::guard_memory((char *) base, stack_yellow_zone_size())) {
2304     _stack_guard_state = stack_guard_enabled;
2305   } else {
2306     warning("Attempt to guard stack yellow zone failed.");
2307   }
2308   enable_register_stack_guard();
2309 }
2310 
2311 void JavaThread::disable_stack_yellow_zone() {
2312   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2313   assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled");
2314 
2315   // Simply return if called for a thread that does not use guard pages.
2316   if (_stack_guard_state == stack_guard_unused) return;
2317 
2318   // The base notation is from the stacks point of view, growing downward.
2319   // We need to adjust it to work correctly with guard_memory()
2320   address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2321 
2322   if (os::unguard_memory((char *)base, stack_yellow_zone_size())) {
2323     _stack_guard_state = stack_guard_yellow_disabled;
2324   } else {
2325     warning("Attempt to unguard stack yellow zone failed.");
2326   }
2327   disable_register_stack_guard();
2328 }
2329 
2330 void JavaThread::enable_stack_red_zone() {
2331   // The base notation is from the stacks point of view, growing downward.
2332   // We need to adjust it to work correctly with guard_memory()
2333   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2334   address base = stack_red_zone_base() - stack_red_zone_size();
2335 
2336   guarantee(base < stack_base(),"Error calculating stack red zone");
2337   guarantee(base < os::current_stack_pointer(),"Error calculating stack red zone");
2338 
2339   if(!os::guard_memory((char *) base, stack_red_zone_size())) {
2340     warning("Attempt to guard stack red zone failed.");
2341   }
2342 }
2343 
2344 void JavaThread::disable_stack_red_zone() {
2345   // The base notation is from the stacks point of view, growing downward.
2346   // We need to adjust it to work correctly with guard_memory()
2347   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2348   address base = stack_red_zone_base() - stack_red_zone_size();
2349   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2350     warning("Attempt to unguard stack red zone failed.");
2351   }
2352 }
2353 
2354 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2355   // ignore is there is no stack
2356   if (!has_last_Java_frame()) return;
2357   // traverse the stack frames. Starts from top frame.
2358   for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2359     frame* fr = fst.current();
2360     f(fr, fst.register_map());
2361   }
2362 }
2363 
2364 
2365 #ifndef PRODUCT
2366 // Deoptimization
2367 // Function for testing deoptimization
2368 void JavaThread::deoptimize() {
2369   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2370   StackFrameStream fst(this, UseBiasedLocking);
2371   bool deopt = false;           // Dump stack only if a deopt actually happens.
2372   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2373   // Iterate over all frames in the thread and deoptimize
2374   for(; !fst.is_done(); fst.next()) {
2375     if(fst.current()->can_be_deoptimized()) {
2376 
2377       if (only_at) {
2378         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
2379         // consists of comma or carriage return separated numbers so
2380         // search for the current bci in that string.
2381         address pc = fst.current()->pc();
2382         nmethod* nm =  (nmethod*) fst.current()->cb();
2383         ScopeDesc* sd = nm->scope_desc_at( pc);
2384         char buffer[8];
2385         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2386         size_t len = strlen(buffer);
2387         const char * found = strstr(DeoptimizeOnlyAt, buffer);
2388         while (found != NULL) {
2389           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2390               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2391             // Check that the bci found is bracketed by terminators.
2392             break;
2393           }
2394           found = strstr(found + 1, buffer);
2395         }
2396         if (!found) {
2397           continue;
2398         }
2399       }
2400 
2401       if (DebugDeoptimization && !deopt) {
2402         deopt = true; // One-time only print before deopt
2403         tty->print_cr("[BEFORE Deoptimization]");
2404         trace_frames();
2405         trace_stack();
2406       }
2407       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2408     }
2409   }
2410 
2411   if (DebugDeoptimization && deopt) {
2412     tty->print_cr("[AFTER Deoptimization]");
2413     trace_frames();
2414   }
2415 }
2416 
2417 
2418 // Make zombies
2419 void JavaThread::make_zombies() {
2420   for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2421     if (fst.current()->can_be_deoptimized()) {
2422       // it is a Java nmethod
2423       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2424       nm->make_not_entrant();
2425     }
2426   }
2427 }
2428 #endif // PRODUCT
2429 
2430 
2431 void JavaThread::deoptimized_wrt_marked_nmethods() {
2432   if (!has_last_Java_frame()) return;
2433   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2434   StackFrameStream fst(this, UseBiasedLocking);
2435   for(; !fst.is_done(); fst.next()) {
2436     if (fst.current()->should_be_deoptimized()) {
2437       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2438     }
2439   }
2440 }
2441 
2442 
2443 // GC support
2444 static void frame_gc_epilogue(frame* f, const RegisterMap* map) { f->gc_epilogue(); }
2445 
2446 void JavaThread::gc_epilogue() {
2447   frames_do(frame_gc_epilogue);
2448 }
2449 
2450 
2451 static void frame_gc_prologue(frame* f, const RegisterMap* map) { f->gc_prologue(); }
2452 
2453 void JavaThread::gc_prologue() {
2454   frames_do(frame_gc_prologue);
2455 }
2456 
2457 // If the caller is a NamedThread, then remember, in the current scope,
2458 // the given JavaThread in its _processed_thread field.
2459 class RememberProcessedThread: public StackObj {
2460   NamedThread* _cur_thr;
2461 public:
2462   RememberProcessedThread(JavaThread* jthr) {
2463     Thread* thread = Thread::current();
2464     if (thread->is_Named_thread()) {
2465       _cur_thr = (NamedThread *)thread;
2466       _cur_thr->set_processed_thread(jthr);
2467     } else {
2468       _cur_thr = NULL;
2469     }
2470   }
2471 
2472   ~RememberProcessedThread() {
2473     if (_cur_thr) {
2474       _cur_thr->set_processed_thread(NULL);
2475     }
2476   }
2477 };
2478 
2479 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2480   // Verify that the deferred card marks have been flushed.
2481   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2482 
2483   // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2484   // since there may be more than one thread using each ThreadProfiler.
2485 
2486   // Traverse the GCHandles
2487   Thread::oops_do(f, cf);
2488 
2489   assert( (!has_last_Java_frame() && java_call_counter() == 0) ||
2490           (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2491 
2492   if (has_last_Java_frame()) {
2493     // Record JavaThread to GC thread
2494     RememberProcessedThread rpt(this);
2495 
2496     // Traverse the privileged stack
2497     if (_privileged_stack_top != NULL) {
2498       _privileged_stack_top->oops_do(f);
2499     }
2500 
2501     // traverse the registered growable array
2502     if (_array_for_gc != NULL) {
2503       for (int index = 0; index < _array_for_gc->length(); index++) {
2504         f->do_oop(_array_for_gc->adr_at(index));
2505       }
2506     }
2507 
2508     // Traverse the monitor chunks
2509     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2510       chunk->oops_do(f);
2511     }
2512 
2513     // Traverse the execution stack
2514     for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2515       fst.current()->oops_do(f, cf, fst.register_map());
2516     }
2517   }
2518 
2519   // callee_target is never live across a gc point so NULL it here should
2520   // it still contain a methdOop.
2521 
2522   set_callee_target(NULL);
2523 
2524   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2525   // If we have deferred set_locals there might be oops waiting to be
2526   // written
2527   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2528   if (list != NULL) {
2529     for (int i = 0; i < list->length(); i++) {
2530       list->at(i)->oops_do(f);
2531     }
2532   }
2533 
2534   // Traverse instance variables at the end since the GC may be moving things
2535   // around using this function
2536   f->do_oop((oop*) &_threadObj);
2537   f->do_oop((oop*) &_vm_result);
2538   f->do_oop((oop*) &_vm_result_2);
2539   f->do_oop((oop*) &_exception_oop);
2540   f->do_oop((oop*) &_pending_async_exception);
2541 
2542   if (jvmti_thread_state() != NULL) {
2543     jvmti_thread_state()->oops_do(f);
2544   }
2545 }
2546 
2547 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2548   Thread::nmethods_do(cf);  // (super method is a no-op)
2549 
2550   assert( (!has_last_Java_frame() && java_call_counter() == 0) ||
2551           (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2552 
2553   if (has_last_Java_frame()) {
2554     // Traverse the execution stack
2555     for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2556       fst.current()->nmethods_do(cf);
2557     }
2558   }
2559 }
2560 
2561 // Printing
2562 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2563   switch (_thread_state) {
2564   case _thread_uninitialized:     return "_thread_uninitialized";
2565   case _thread_new:               return "_thread_new";
2566   case _thread_new_trans:         return "_thread_new_trans";
2567   case _thread_in_native:         return "_thread_in_native";
2568   case _thread_in_native_trans:   return "_thread_in_native_trans";
2569   case _thread_in_vm:             return "_thread_in_vm";
2570   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
2571   case _thread_in_Java:           return "_thread_in_Java";
2572   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
2573   case _thread_blocked:           return "_thread_blocked";
2574   case _thread_blocked_trans:     return "_thread_blocked_trans";
2575   default:                        return "unknown thread state";
2576   }
2577 }
2578 
2579 #ifndef PRODUCT
2580 void JavaThread::print_thread_state_on(outputStream *st) const {
2581   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
2582 };
2583 void JavaThread::print_thread_state() const {
2584   print_thread_state_on(tty);
2585 };
2586 #endif // PRODUCT
2587 
2588 // Called by Threads::print() for VM_PrintThreads operation
2589 void JavaThread::print_on(outputStream *st) const {
2590   st->print("\"%s\" ", get_thread_name());
2591   oop thread_oop = threadObj();
2592   if (thread_oop != NULL && java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
2593   Thread::print_on(st);
2594   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2595   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2596   if (thread_oop != NULL && JDK_Version::is_gte_jdk15x_version()) {
2597     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2598   }
2599 #ifndef PRODUCT
2600   print_thread_state_on(st);
2601   _safepoint_state->print_on(st);
2602 #endif // PRODUCT
2603 }
2604 
2605 // Called by fatal error handler. The difference between this and
2606 // JavaThread::print() is that we can't grab lock or allocate memory.
2607 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2608   st->print("JavaThread \"%s\"",  get_thread_name_string(buf, buflen));
2609   oop thread_obj = threadObj();
2610   if (thread_obj != NULL) {
2611      if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2612   }
2613   st->print(" [");
2614   st->print("%s", _get_thread_state_name(_thread_state));
2615   if (osthread()) {
2616     st->print(", id=%d", osthread()->thread_id());
2617   }
2618   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2619             _stack_base - _stack_size, _stack_base);
2620   st->print("]");
2621   return;
2622 }
2623 
2624 // Verification
2625 
2626 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2627 
2628 void JavaThread::verify() {
2629   // Verify oops in the thread.
2630   oops_do(&VerifyOopClosure::verify_oop, NULL);
2631 
2632   // Verify the stack frames.
2633   frames_do(frame_verify);
2634 }
2635 
2636 // CR 6300358 (sub-CR 2137150)
2637 // Most callers of this method assume that it can't return NULL but a
2638 // thread may not have a name whilst it is in the process of attaching to
2639 // the VM - see CR 6412693, and there are places where a JavaThread can be
2640 // seen prior to having it's threadObj set (eg JNI attaching threads and
2641 // if vm exit occurs during initialization). These cases can all be accounted
2642 // for such that this method never returns NULL.
2643 const char* JavaThread::get_thread_name() const {
2644 #ifdef ASSERT
2645   // early safepoints can hit while current thread does not yet have TLS
2646   if (!SafepointSynchronize::is_at_safepoint()) {
2647     Thread *cur = Thread::current();
2648     if (!(cur->is_Java_thread() && cur == this)) {
2649       // Current JavaThreads are allowed to get their own name without
2650       // the Threads_lock.
2651       assert_locked_or_safepoint(Threads_lock);
2652     }
2653   }
2654 #endif // ASSERT
2655     return get_thread_name_string();
2656 }
2657 
2658 // Returns a non-NULL representation of this thread's name, or a suitable
2659 // descriptive string if there is no set name
2660 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2661   const char* name_str;
2662   oop thread_obj = threadObj();
2663   if (thread_obj != NULL) {
2664     typeArrayOop name = java_lang_Thread::name(thread_obj);
2665     if (name != NULL) {
2666       if (buf == NULL) {
2667         name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2668       }
2669       else {
2670         name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length(), buf, buflen);
2671       }
2672     }
2673     else if (is_attaching()) { // workaround for 6412693 - see 6404306
2674       name_str = "<no-name - thread is attaching>";
2675     }
2676     else {
2677       name_str = Thread::name();
2678     }
2679   }
2680   else {
2681     name_str = Thread::name();
2682   }
2683   assert(name_str != NULL, "unexpected NULL thread name");
2684   return name_str;
2685 }
2686 
2687 
2688 const char* JavaThread::get_threadgroup_name() const {
2689   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2690   oop thread_obj = threadObj();
2691   if (thread_obj != NULL) {
2692     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2693     if (thread_group != NULL) {
2694       typeArrayOop name = java_lang_ThreadGroup::name(thread_group);
2695       // ThreadGroup.name can be null
2696       if (name != NULL) {
2697         const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2698         return str;
2699       }
2700     }
2701   }
2702   return NULL;
2703 }
2704 
2705 const char* JavaThread::get_parent_name() const {
2706   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2707   oop thread_obj = threadObj();
2708   if (thread_obj != NULL) {
2709     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2710     if (thread_group != NULL) {
2711       oop parent = java_lang_ThreadGroup::parent(thread_group);
2712       if (parent != NULL) {
2713         typeArrayOop name = java_lang_ThreadGroup::name(parent);
2714         // ThreadGroup.name can be null
2715         if (name != NULL) {
2716           const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2717           return str;
2718         }
2719       }
2720     }
2721   }
2722   return NULL;
2723 }
2724 
2725 ThreadPriority JavaThread::java_priority() const {
2726   oop thr_oop = threadObj();
2727   if (thr_oop == NULL) return NormPriority; // Bootstrapping
2728   ThreadPriority priority = java_lang_Thread::priority(thr_oop);
2729   assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
2730   return priority;
2731 }
2732 
2733 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
2734 
2735   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
2736   // Link Java Thread object <-> C++ Thread
2737 
2738   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
2739   // and put it into a new Handle.  The Handle "thread_oop" can then
2740   // be used to pass the C++ thread object to other methods.
2741 
2742   // Set the Java level thread object (jthread) field of the
2743   // new thread (a JavaThread *) to C++ thread object using the
2744   // "thread_oop" handle.
2745 
2746   // Set the thread field (a JavaThread *) of the
2747   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
2748 
2749   Handle thread_oop(Thread::current(),
2750                     JNIHandles::resolve_non_null(jni_thread));
2751   assert(instanceKlass::cast(thread_oop->klass())->is_linked(),
2752     "must be initialized");
2753   set_threadObj(thread_oop());
2754   java_lang_Thread::set_thread(thread_oop(), this);
2755 
2756   if (prio == NoPriority) {
2757     prio = java_lang_Thread::priority(thread_oop());
2758     assert(prio != NoPriority, "A valid priority should be present");
2759   }
2760 
2761   // Push the Java priority down to the native thread; needs Threads_lock
2762   Thread::set_priority(this, prio);
2763 
2764   // Add the new thread to the Threads list and set it in motion.
2765   // We must have threads lock in order to call Threads::add.
2766   // It is crucial that we do not block before the thread is
2767   // added to the Threads list for if a GC happens, then the java_thread oop
2768   // will not be visited by GC.
2769   Threads::add(this);
2770 }
2771 
2772 oop JavaThread::current_park_blocker() {
2773   // Support for JSR-166 locks
2774   oop thread_oop = threadObj();
2775   if (thread_oop != NULL &&
2776       JDK_Version::current().supports_thread_park_blocker()) {
2777     return java_lang_Thread::park_blocker(thread_oop);
2778   }
2779   return NULL;
2780 }
2781 
2782 
2783 void JavaThread::print_stack_on(outputStream* st) {
2784   if (!has_last_Java_frame()) return;
2785   ResourceMark rm;
2786   HandleMark   hm;
2787 
2788   RegisterMap reg_map(this);
2789   vframe* start_vf = last_java_vframe(&reg_map);
2790   int count = 0;
2791   for (vframe* f = start_vf; f; f = f->sender() ) {
2792     if (f->is_java_frame()) {
2793       javaVFrame* jvf = javaVFrame::cast(f);
2794       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
2795 
2796       // Print out lock information
2797       if (JavaMonitorsInStackTrace) {
2798         jvf->print_lock_info_on(st, count);
2799       }
2800     } else {
2801       // Ignore non-Java frames
2802     }
2803 
2804     // Bail-out case for too deep stacks
2805     count++;
2806     if (MaxJavaStackTraceDepth == count) return;
2807   }
2808 }
2809 
2810 
2811 // JVMTI PopFrame support
2812 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
2813   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
2814   if (in_bytes(size_in_bytes) != 0) {
2815     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes));
2816     _popframe_preserved_args_size = in_bytes(size_in_bytes);
2817     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
2818   }
2819 }
2820 
2821 void* JavaThread::popframe_preserved_args() {
2822   return _popframe_preserved_args;
2823 }
2824 
2825 ByteSize JavaThread::popframe_preserved_args_size() {
2826   return in_ByteSize(_popframe_preserved_args_size);
2827 }
2828 
2829 WordSize JavaThread::popframe_preserved_args_size_in_words() {
2830   int sz = in_bytes(popframe_preserved_args_size());
2831   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
2832   return in_WordSize(sz / wordSize);
2833 }
2834 
2835 void JavaThread::popframe_free_preserved_args() {
2836   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
2837   FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
2838   _popframe_preserved_args = NULL;
2839   _popframe_preserved_args_size = 0;
2840 }
2841 
2842 #ifndef PRODUCT
2843 
2844 void JavaThread::trace_frames() {
2845   tty->print_cr("[Describe stack]");
2846   int frame_no = 1;
2847   for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2848     tty->print("  %d. ", frame_no++);
2849     fst.current()->print_value_on(tty,this);
2850     tty->cr();
2851   }
2852 }
2853 
2854 
2855 void JavaThread::trace_stack_from(vframe* start_vf) {
2856   ResourceMark rm;
2857   int vframe_no = 1;
2858   for (vframe* f = start_vf; f; f = f->sender() ) {
2859     if (f->is_java_frame()) {
2860       javaVFrame::cast(f)->print_activation(vframe_no++);
2861     } else {
2862       f->print();
2863     }
2864     if (vframe_no > StackPrintLimit) {
2865       tty->print_cr("...<more frames>...");
2866       return;
2867     }
2868   }
2869 }
2870 
2871 
2872 void JavaThread::trace_stack() {
2873   if (!has_last_Java_frame()) return;
2874   ResourceMark rm;
2875   HandleMark   hm;
2876   RegisterMap reg_map(this);
2877   trace_stack_from(last_java_vframe(&reg_map));
2878 }
2879 
2880 
2881 #endif // PRODUCT
2882 
2883 
2884 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
2885   assert(reg_map != NULL, "a map must be given");
2886   frame f = last_frame();
2887   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender() ) {
2888     if (vf->is_java_frame()) return javaVFrame::cast(vf);
2889   }
2890   return NULL;
2891 }
2892 
2893 
2894 klassOop JavaThread::security_get_caller_class(int depth) {
2895   vframeStream vfst(this);
2896   vfst.security_get_caller_frame(depth);
2897   if (!vfst.at_end()) {
2898     return vfst.method()->method_holder();
2899   }
2900   return NULL;
2901 }
2902 
2903 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
2904   assert(thread->is_Compiler_thread(), "must be compiler thread");
2905   CompileBroker::compiler_thread_loop();
2906 }
2907 
2908 // Create a CompilerThread
2909 CompilerThread::CompilerThread(CompileQueue* queue, CompilerCounters* counters)
2910 : JavaThread(&compiler_thread_entry) {
2911   _env   = NULL;
2912   _log   = NULL;
2913   _task  = NULL;
2914   _queue = queue;
2915   _counters = counters;
2916   _buffer_blob = NULL;
2917 
2918 #ifndef PRODUCT
2919   _ideal_graph_printer = NULL;
2920 #endif
2921 }
2922 
2923 
2924 // ======= Threads ========
2925 
2926 // The Threads class links together all active threads, and provides
2927 // operations over all threads.  It is protected by its own Mutex
2928 // lock, which is also used in other contexts to protect thread
2929 // operations from having the thread being operated on from exiting
2930 // and going away unexpectedly (e.g., safepoint synchronization)
2931 
2932 JavaThread* Threads::_thread_list = NULL;
2933 int         Threads::_number_of_threads = 0;
2934 int         Threads::_number_of_non_daemon_threads = 0;
2935 int         Threads::_return_code = 0;
2936 size_t      JavaThread::_stack_size_at_create = 0;
2937 
2938 // All JavaThreads
2939 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
2940 
2941 void os_stream();
2942 
2943 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
2944 void Threads::threads_do(ThreadClosure* tc) {
2945   assert_locked_or_safepoint(Threads_lock);
2946   // ALL_JAVA_THREADS iterates through all JavaThreads
2947   ALL_JAVA_THREADS(p) {
2948     tc->do_thread(p);
2949   }
2950   // Someday we could have a table or list of all non-JavaThreads.
2951   // For now, just manually iterate through them.
2952   tc->do_thread(VMThread::vm_thread());
2953   Universe::heap()->gc_threads_do(tc);
2954   WatcherThread *wt = WatcherThread::watcher_thread();
2955   // Strictly speaking, the following NULL check isn't sufficient to make sure
2956   // the data for WatcherThread is still valid upon being examined. However,
2957   // considering that WatchThread terminates when the VM is on the way to
2958   // exit at safepoint, the chance of the above is extremely small. The right
2959   // way to prevent termination of WatcherThread would be to acquire
2960   // Terminator_lock, but we can't do that without violating the lock rank
2961   // checking in some cases.
2962   if (wt != NULL)
2963     tc->do_thread(wt);
2964 
2965   // If CompilerThreads ever become non-JavaThreads, add them here
2966 }
2967 
2968 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
2969 
2970   extern void JDK_Version_init();
2971 
2972   // Check version
2973   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
2974 
2975   // Initialize the output stream module
2976   ostream_init();
2977 
2978   // Process java launcher properties.
2979   Arguments::process_sun_java_launcher_properties(args);
2980 
2981   // Initialize the os module before using TLS
2982   os::init();
2983 
2984   // Initialize system properties.
2985   Arguments::init_system_properties();
2986 
2987   // So that JDK version can be used as a discrimintor when parsing arguments
2988   JDK_Version_init();
2989 
2990   // Update/Initialize System properties after JDK version number is known
2991   Arguments::init_version_specific_system_properties();
2992 
2993   // Parse arguments
2994   jint parse_result = Arguments::parse(args);
2995   if (parse_result != JNI_OK) return parse_result;
2996 
2997   if (PauseAtStartup) {
2998     os::pause();
2999   }
3000 
3001   HS_DTRACE_PROBE(hotspot, vm__init__begin);
3002 
3003   // Record VM creation timing statistics
3004   TraceVmCreationTime create_vm_timer;
3005   create_vm_timer.start();
3006 
3007   // Timing (must come after argument parsing)
3008   TraceTime timer("Create VM", TraceStartupTime);
3009 
3010   // Initialize the os module after parsing the args
3011   jint os_init_2_result = os::init_2();
3012   if (os_init_2_result != JNI_OK) return os_init_2_result;
3013 
3014   // Initialize output stream logging
3015   ostream_init_log();
3016 
3017   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3018   // Must be before create_vm_init_agents()
3019   if (Arguments::init_libraries_at_startup()) {
3020     convert_vm_init_libraries_to_agents();
3021   }
3022 
3023   // Launch -agentlib/-agentpath and converted -Xrun agents
3024   if (Arguments::init_agents_at_startup()) {
3025     create_vm_init_agents();
3026   }
3027 
3028   // Initialize Threads state
3029   _thread_list = NULL;
3030   _number_of_threads = 0;
3031   _number_of_non_daemon_threads = 0;
3032 
3033   // Initialize TLS
3034   ThreadLocalStorage::init();
3035 
3036   // Initialize global data structures and create system classes in heap
3037   vm_init_globals();
3038 
3039   // Attach the main thread to this os thread
3040   JavaThread* main_thread = new JavaThread();
3041   main_thread->set_thread_state(_thread_in_vm);
3042   // must do this before set_active_handles and initialize_thread_local_storage
3043   // Note: on solaris initialize_thread_local_storage() will (indirectly)
3044   // change the stack size recorded here to one based on the java thread
3045   // stacksize. This adjusted size is what is used to figure the placement
3046   // of the guard pages.
3047   main_thread->record_stack_base_and_size();
3048   main_thread->initialize_thread_local_storage();
3049 
3050   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3051 
3052   if (!main_thread->set_as_starting_thread()) {
3053     vm_shutdown_during_initialization(
3054       "Failed necessary internal allocation. Out of swap space");
3055     delete main_thread;
3056     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3057     return JNI_ENOMEM;
3058   }
3059 
3060   // Enable guard page *after* os::create_main_thread(), otherwise it would
3061   // crash Linux VM, see notes in os_linux.cpp.
3062   main_thread->create_stack_guard_pages();
3063 
3064   // Initialize Java-Level synchronization subsystem
3065   ObjectMonitor::Initialize() ;
3066 
3067   // Initialize global modules
3068   jint status = init_globals();
3069   if (status != JNI_OK) {
3070     delete main_thread;
3071     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3072     return status;
3073   }
3074 
3075   // Should be done after the heap is fully created
3076   main_thread->cache_global_variables();
3077 
3078   HandleMark hm;
3079 
3080   { MutexLocker mu(Threads_lock);
3081     Threads::add(main_thread);
3082   }
3083 
3084   // Any JVMTI raw monitors entered in onload will transition into
3085   // real raw monitor. VM is setup enough here for raw monitor enter.
3086   JvmtiExport::transition_pending_onload_raw_monitors();
3087 
3088   if (VerifyBeforeGC &&
3089       Universe::heap()->total_collections() >= VerifyGCStartAt) {
3090     Universe::heap()->prepare_for_verify();
3091     Universe::verify();   // make sure we're starting with a clean slate
3092   }
3093 
3094   // Create the VMThread
3095   { TraceTime timer("Start VMThread", TraceStartupTime);
3096     VMThread::create();
3097     Thread* vmthread = VMThread::vm_thread();
3098 
3099     if (!os::create_thread(vmthread, os::vm_thread))
3100       vm_exit_during_initialization("Cannot create VM thread. Out of system resources.");
3101 
3102     // Wait for the VM thread to become ready, and VMThread::run to initialize
3103     // Monitors can have spurious returns, must always check another state flag
3104     {
3105       MutexLocker ml(Notify_lock);
3106       os::start_thread(vmthread);
3107       while (vmthread->active_handles() == NULL) {
3108         Notify_lock->wait();
3109       }
3110     }
3111   }
3112 
3113   assert (Universe::is_fully_initialized(), "not initialized");
3114   EXCEPTION_MARK;
3115 
3116   // At this point, the Universe is initialized, but we have not executed
3117   // any byte code.  Now is a good time (the only time) to dump out the
3118   // internal state of the JVM for sharing.
3119 
3120   if (DumpSharedSpaces) {
3121     Universe::heap()->preload_and_dump(CHECK_0);
3122     ShouldNotReachHere();
3123   }
3124 
3125   // Always call even when there are not JVMTI environments yet, since environments
3126   // may be attached late and JVMTI must track phases of VM execution
3127   JvmtiExport::enter_start_phase();
3128 
3129   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3130   JvmtiExport::post_vm_start();
3131 
3132   {
3133     TraceTime timer("Initialize java.lang classes", TraceStartupTime);
3134 
3135     if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3136       create_vm_init_libraries();
3137     }
3138 
3139     if (InitializeJavaLangString) {
3140       initialize_class(vmSymbols::java_lang_String(), CHECK_0);
3141     } else {
3142       warning("java.lang.String not initialized");
3143     }
3144 
3145     if (AggressiveOpts) {
3146       {
3147         // Forcibly initialize java/util/HashMap and mutate the private
3148         // static final "frontCacheEnabled" field before we start creating instances
3149 #ifdef ASSERT
3150         klassOop tmp_k = SystemDictionary::find(vmSymbols::java_util_HashMap(), Handle(), Handle(), CHECK_0);
3151         assert(tmp_k == NULL, "java/util/HashMap should not be loaded yet");
3152 #endif
3153         klassOop k_o = SystemDictionary::resolve_or_null(vmSymbols::java_util_HashMap(), Handle(), Handle(), CHECK_0);
3154         KlassHandle k = KlassHandle(THREAD, k_o);
3155         guarantee(k.not_null(), "Must find java/util/HashMap");
3156         instanceKlassHandle ik = instanceKlassHandle(THREAD, k());
3157         ik->initialize(CHECK_0);
3158         fieldDescriptor fd;
3159         // Possible we might not find this field; if so, don't break
3160         if (ik->find_local_field(vmSymbols::frontCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) {
3161           k()->bool_field_put(fd.offset(), true);
3162         }
3163       }
3164 
3165       if (UseStringCache) {
3166         // Forcibly initialize java/lang/StringValue and mutate the private
3167         // static final "stringCacheEnabled" field before we start creating instances
3168         klassOop k_o = SystemDictionary::resolve_or_null(vmSymbols::java_lang_StringValue(), Handle(), Handle(), CHECK_0);
3169         // Possible that StringValue isn't present: if so, silently don't break
3170         if (k_o != NULL) {
3171           KlassHandle k = KlassHandle(THREAD, k_o);
3172           instanceKlassHandle ik = instanceKlassHandle(THREAD, k());
3173           ik->initialize(CHECK_0);
3174           fieldDescriptor fd;
3175           // Possible we might not find this field: if so, silently don't break
3176           if (ik->find_local_field(vmSymbols::stringCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) {
3177             k()->bool_field_put(fd.offset(), true);
3178           }
3179         }
3180       }
3181     }
3182 
3183     // Initialize java_lang.System (needed before creating the thread)
3184     if (InitializeJavaLangSystem) {
3185       initialize_class(vmSymbols::java_lang_System(), CHECK_0);
3186       initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK_0);
3187       Handle thread_group = create_initial_thread_group(CHECK_0);
3188       Universe::set_main_thread_group(thread_group());
3189       initialize_class(vmSymbols::java_lang_Thread(), CHECK_0);
3190       oop thread_object = create_initial_thread(thread_group, main_thread, CHECK_0);
3191       main_thread->set_threadObj(thread_object);
3192       // Set thread status to running since main thread has
3193       // been started and running.
3194       java_lang_Thread::set_thread_status(thread_object,
3195                                           java_lang_Thread::RUNNABLE);
3196 
3197       // The VM preresolve methods to these classes. Make sure that get initialized
3198       initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK_0);
3199       initialize_class(vmSymbols::java_lang_ref_Finalizer(),  CHECK_0);
3200       // The VM creates & returns objects of this class. Make sure it's initialized.
3201       initialize_class(vmSymbols::java_lang_Class(), CHECK_0);
3202       call_initializeSystemClass(CHECK_0);
3203     } else {
3204       warning("java.lang.System not initialized");
3205     }
3206 
3207     // an instance of OutOfMemory exception has been allocated earlier
3208     if (InitializeJavaLangExceptionsErrors) {
3209       initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK_0);
3210       initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK_0);
3211       initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK_0);
3212       initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK_0);
3213       initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK_0);
3214       initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK_0);
3215       initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK_0);
3216     } else {
3217       warning("java.lang.OutOfMemoryError has not been initialized");
3218       warning("java.lang.NullPointerException has not been initialized");
3219       warning("java.lang.ClassCastException has not been initialized");
3220       warning("java.lang.ArrayStoreException has not been initialized");
3221       warning("java.lang.ArithmeticException has not been initialized");
3222       warning("java.lang.StackOverflowError has not been initialized");
3223     }
3224     }
3225 
3226   // See        : bugid 4211085.
3227   // Background : the static initializer of java.lang.Compiler tries to read
3228   //              property"java.compiler" and read & write property "java.vm.info".
3229   //              When a security manager is installed through the command line
3230   //              option "-Djava.security.manager", the above properties are not
3231   //              readable and the static initializer for java.lang.Compiler fails
3232   //              resulting in a NoClassDefFoundError.  This can happen in any
3233   //              user code which calls methods in java.lang.Compiler.
3234   // Hack :       the hack is to pre-load and initialize this class, so that only
3235   //              system domains are on the stack when the properties are read.
3236   //              Currently even the AWT code has calls to methods in java.lang.Compiler.
3237   //              On the classic VM, java.lang.Compiler is loaded very early to load the JIT.
3238   // Future Fix : the best fix is to grant everyone permissions to read "java.compiler" and
3239   //              read and write"java.vm.info" in the default policy file. See bugid 4211383
3240   //              Once that is done, we should remove this hack.
3241   initialize_class(vmSymbols::java_lang_Compiler(), CHECK_0);
3242 
3243   // More hackery - the static initializer of java.lang.Compiler adds the string "nojit" to
3244   // the java.vm.info property if no jit gets loaded through java.lang.Compiler (the hotspot
3245   // compiler does not get loaded through java.lang.Compiler).  "java -version" with the
3246   // hotspot vm says "nojit" all the time which is confusing.  So, we reset it here.
3247   // This should also be taken out as soon as 4211383 gets fixed.
3248   reset_vm_info_property(CHECK_0);
3249 
3250   quicken_jni_functions();
3251 
3252   // Set flag that basic initialization has completed. Used by exceptions and various
3253   // debug stuff, that does not work until all basic classes have been initialized.
3254   set_init_completed();
3255 
3256   HS_DTRACE_PROBE(hotspot, vm__init__end);
3257 
3258   // record VM initialization completion time
3259   Management::record_vm_init_completed();
3260 
3261   // Compute system loader. Note that this has to occur after set_init_completed, since
3262   // valid exceptions may be thrown in the process.
3263   // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
3264   // set_init_completed has just been called, causing exceptions not to be shortcut
3265   // anymore. We call vm_exit_during_initialization directly instead.
3266   SystemDictionary::compute_java_system_loader(THREAD);
3267   if (HAS_PENDING_EXCEPTION) {
3268     vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
3269   }
3270 
3271 #ifndef SERIALGC
3272   // Support for ConcurrentMarkSweep. This should be cleaned up
3273   // and better encapsulated. The ugly nested if test would go away
3274   // once things are properly refactored. XXX YSR
3275   if (UseConcMarkSweepGC || UseG1GC) {
3276     if (UseConcMarkSweepGC) {
3277       ConcurrentMarkSweepThread::makeSurrogateLockerThread(THREAD);
3278     } else {
3279       ConcurrentMarkThread::makeSurrogateLockerThread(THREAD);
3280     }
3281     if (HAS_PENDING_EXCEPTION) {
3282       vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
3283     }
3284   }
3285 #endif // SERIALGC
3286 
3287   // Always call even when there are not JVMTI environments yet, since environments
3288   // may be attached late and JVMTI must track phases of VM execution
3289   JvmtiExport::enter_live_phase();
3290 
3291   // Signal Dispatcher needs to be started before VMInit event is posted
3292   os::signal_init();
3293 
3294   // Start Attach Listener if +StartAttachListener or it can't be started lazily
3295   if (!DisableAttachMechanism) {
3296     if (StartAttachListener || AttachListener::init_at_startup()) {
3297       AttachListener::init();
3298     }
3299   }
3300 
3301   // Launch -Xrun agents
3302   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3303   // back-end can launch with -Xdebug -Xrunjdwp.
3304   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3305     create_vm_init_libraries();
3306   }
3307 
3308   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3309   JvmtiExport::post_vm_initialized();
3310 
3311   Chunk::start_chunk_pool_cleaner_task();
3312 
3313   // initialize compiler(s)
3314   CompileBroker::compilation_init();
3315 
3316   Management::initialize(THREAD);
3317   if (HAS_PENDING_EXCEPTION) {
3318     // management agent fails to start possibly due to
3319     // configuration problem and is responsible for printing
3320     // stack trace if appropriate. Simply exit VM.
3321     vm_exit(1);
3322   }
3323 
3324   if (Arguments::has_profile())       FlatProfiler::engage(main_thread, true);
3325   if (Arguments::has_alloc_profile()) AllocationProfiler::engage();
3326   if (MemProfiling)                   MemProfiler::engage();
3327   StatSampler::engage();
3328   if (CheckJNICalls)                  JniPeriodicChecker::engage();
3329 
3330   BiasedLocking::init();
3331 
3332   if (JDK_Version::current().post_vm_init_hook_enabled()) {
3333     call_postVMInitHook(THREAD);
3334     // The Java side of PostVMInitHook.run must deal with all
3335     // exceptions and provide means of diagnosis.
3336     if (HAS_PENDING_EXCEPTION) {
3337       CLEAR_PENDING_EXCEPTION;
3338     }
3339   }
3340 
3341   // Start up the WatcherThread if there are any periodic tasks
3342   // NOTE:  All PeriodicTasks should be registered by now. If they
3343   //   aren't, late joiners might appear to start slowly (we might
3344   //   take a while to process their first tick).
3345   if (PeriodicTask::num_tasks() > 0) {
3346     WatcherThread::start();
3347   }
3348 
3349   // Give os specific code one last chance to start
3350   os::init_3();
3351 
3352   create_vm_timer.end();
3353   return JNI_OK;
3354 }
3355 
3356 // type for the Agent_OnLoad and JVM_OnLoad entry points
3357 extern "C" {
3358   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3359 }
3360 // Find a command line agent library and return its entry point for
3361 //         -agentlib:  -agentpath:   -Xrun
3362 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3363 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, const char *on_load_symbols[], size_t num_symbol_entries) {
3364   OnLoadEntry_t on_load_entry = NULL;
3365   void *library = agent->os_lib();  // check if we have looked it up before
3366 
3367   if (library == NULL) {
3368     char buffer[JVM_MAXPATHLEN];
3369     char ebuf[1024];
3370     const char *name = agent->name();
3371     const char *msg = "Could not find agent library ";
3372 
3373     if (agent->is_absolute_path()) {
3374       library = os::dll_load(name, ebuf, sizeof ebuf);
3375       if (library == NULL) {
3376         const char *sub_msg = " in absolute path, with error: ";
3377         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3378         char *buf = NEW_C_HEAP_ARRAY(char, len);
3379         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3380         // If we can't find the agent, exit.
3381         vm_exit_during_initialization(buf, NULL);
3382         FREE_C_HEAP_ARRAY(char, buf);
3383       }
3384     } else {
3385       // Try to load the agent from the standard dll directory
3386       os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(), name);
3387       library = os::dll_load(buffer, ebuf, sizeof ebuf);
3388 #ifdef KERNEL
3389       // Download instrument dll
3390       if (library == NULL && strcmp(name, "instrument") == 0) {
3391         char *props = Arguments::get_kernel_properties();
3392         char *home  = Arguments::get_java_home();
3393         const char *fmt   = "%s/bin/java %s -Dkernel.background.download=false"
3394                       " sun.jkernel.DownloadManager -download client_jvm";
3395         size_t length = strlen(props) + strlen(home) + strlen(fmt) + 1;
3396         char *cmd = NEW_C_HEAP_ARRAY(char, length);
3397         jio_snprintf(cmd, length, fmt, home, props);
3398         int status = os::fork_and_exec(cmd);
3399         FreeHeap(props);
3400         if (status == -1) {
3401           warning(cmd);
3402           vm_exit_during_initialization("fork_and_exec failed: %s",
3403                                          strerror(errno));
3404         }
3405         FREE_C_HEAP_ARRAY(char, cmd);
3406         // when this comes back the instrument.dll should be where it belongs.
3407         library = os::dll_load(buffer, ebuf, sizeof ebuf);
3408       }
3409 #endif // KERNEL
3410       if (library == NULL) { // Try the local directory
3411         char ns[1] = {0};
3412         os::dll_build_name(buffer, sizeof(buffer), ns, name);
3413         library = os::dll_load(buffer, ebuf, sizeof ebuf);
3414         if (library == NULL) {
3415           const char *sub_msg = " on the library path, with error: ";
3416           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3417           char *buf = NEW_C_HEAP_ARRAY(char, len);
3418           jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3419           // If we can't find the agent, exit.
3420           vm_exit_during_initialization(buf, NULL);
3421           FREE_C_HEAP_ARRAY(char, buf);
3422         }
3423       }
3424     }
3425     agent->set_os_lib(library);
3426   }
3427 
3428   // Find the OnLoad function.
3429   for (size_t symbol_index = 0; symbol_index < num_symbol_entries; symbol_index++) {
3430     on_load_entry = CAST_TO_FN_PTR(OnLoadEntry_t, os::dll_lookup(library, on_load_symbols[symbol_index]));
3431     if (on_load_entry != NULL) break;
3432   }
3433   return on_load_entry;
3434 }
3435 
3436 // Find the JVM_OnLoad entry point
3437 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3438   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3439   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3440 }
3441 
3442 // Find the Agent_OnLoad entry point
3443 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3444   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3445   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3446 }
3447 
3448 // For backwards compatibility with -Xrun
3449 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3450 // treated like -agentpath:
3451 // Must be called before agent libraries are created
3452 void Threads::convert_vm_init_libraries_to_agents() {
3453   AgentLibrary* agent;
3454   AgentLibrary* next;
3455 
3456   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3457     next = agent->next();  // cache the next agent now as this agent may get moved off this list
3458     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3459 
3460     // If there is an JVM_OnLoad function it will get called later,
3461     // otherwise see if there is an Agent_OnLoad
3462     if (on_load_entry == NULL) {
3463       on_load_entry = lookup_agent_on_load(agent);
3464       if (on_load_entry != NULL) {
3465         // switch it to the agent list -- so that Agent_OnLoad will be called,
3466         // JVM_OnLoad won't be attempted and Agent_OnUnload will
3467         Arguments::convert_library_to_agent(agent);
3468       } else {
3469         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3470       }
3471     }
3472   }
3473 }
3474 
3475 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
3476 // Invokes Agent_OnLoad
3477 // Called very early -- before JavaThreads exist
3478 void Threads::create_vm_init_agents() {
3479   extern struct JavaVM_ main_vm;
3480   AgentLibrary* agent;
3481 
3482   JvmtiExport::enter_onload_phase();
3483   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3484     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
3485 
3486     if (on_load_entry != NULL) {
3487       // Invoke the Agent_OnLoad function
3488       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3489       if (err != JNI_OK) {
3490         vm_exit_during_initialization("agent library failed to init", agent->name());
3491       }
3492     } else {
3493       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3494     }
3495   }
3496   JvmtiExport::enter_primordial_phase();
3497 }
3498 
3499 extern "C" {
3500   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3501 }
3502 
3503 void Threads::shutdown_vm_agents() {
3504   // Send any Agent_OnUnload notifications
3505   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3506   extern struct JavaVM_ main_vm;
3507   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3508 
3509     // Find the Agent_OnUnload function.
3510     for (uint symbol_index = 0; symbol_index < ARRAY_SIZE(on_unload_symbols); symbol_index++) {
3511       Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3512                os::dll_lookup(agent->os_lib(), on_unload_symbols[symbol_index]));
3513 
3514       // Invoke the Agent_OnUnload function
3515       if (unload_entry != NULL) {
3516         JavaThread* thread = JavaThread::current();
3517         ThreadToNativeFromVM ttn(thread);
3518         HandleMark hm(thread);
3519         (*unload_entry)(&main_vm);
3520         break;
3521       }
3522     }
3523   }
3524 }
3525 
3526 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
3527 // Invokes JVM_OnLoad
3528 void Threads::create_vm_init_libraries() {
3529   extern struct JavaVM_ main_vm;
3530   AgentLibrary* agent;
3531 
3532   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
3533     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3534 
3535     if (on_load_entry != NULL) {
3536       // Invoke the JVM_OnLoad function
3537       JavaThread* thread = JavaThread::current();
3538       ThreadToNativeFromVM ttn(thread);
3539       HandleMark hm(thread);
3540       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3541       if (err != JNI_OK) {
3542         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
3543       }
3544     } else {
3545       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
3546     }
3547   }
3548 }
3549 
3550 // Last thread running calls java.lang.Shutdown.shutdown()
3551 void JavaThread::invoke_shutdown_hooks() {
3552   HandleMark hm(this);
3553 
3554   // We could get here with a pending exception, if so clear it now.
3555   if (this->has_pending_exception()) {
3556     this->clear_pending_exception();
3557   }
3558 
3559   EXCEPTION_MARK;
3560   klassOop k =
3561     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
3562                                       THREAD);
3563   if (k != NULL) {
3564     // SystemDictionary::resolve_or_null will return null if there was
3565     // an exception.  If we cannot load the Shutdown class, just don't
3566     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
3567     // and finalizers (if runFinalizersOnExit is set) won't be run.
3568     // Note that if a shutdown hook was registered or runFinalizersOnExit
3569     // was called, the Shutdown class would have already been loaded
3570     // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
3571     instanceKlassHandle shutdown_klass (THREAD, k);
3572     JavaValue result(T_VOID);
3573     JavaCalls::call_static(&result,
3574                            shutdown_klass,
3575                            vmSymbols::shutdown_method_name(),
3576                            vmSymbols::void_method_signature(),
3577                            THREAD);
3578   }
3579   CLEAR_PENDING_EXCEPTION;
3580 }
3581 
3582 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
3583 // the program falls off the end of main(). Another VM exit path is through
3584 // vm_exit() when the program calls System.exit() to return a value or when
3585 // there is a serious error in VM. The two shutdown paths are not exactly
3586 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
3587 // and VM_Exit op at VM level.
3588 //
3589 // Shutdown sequence:
3590 //   + Wait until we are the last non-daemon thread to execute
3591 //     <-- every thing is still working at this moment -->
3592 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
3593 //        shutdown hooks, run finalizers if finalization-on-exit
3594 //   + Call before_exit(), prepare for VM exit
3595 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
3596 //        currently the only user of this mechanism is File.deleteOnExit())
3597 //      > stop flat profiler, StatSampler, watcher thread, CMS threads,
3598 //        post thread end and vm death events to JVMTI,
3599 //        stop signal thread
3600 //   + Call JavaThread::exit(), it will:
3601 //      > release JNI handle blocks, remove stack guard pages
3602 //      > remove this thread from Threads list
3603 //     <-- no more Java code from this thread after this point -->
3604 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
3605 //     the compiler threads at safepoint
3606 //     <-- do not use anything that could get blocked by Safepoint -->
3607 //   + Disable tracing at JNI/JVM barriers
3608 //   + Set _vm_exited flag for threads that are still running native code
3609 //   + Delete this thread
3610 //   + Call exit_globals()
3611 //      > deletes tty
3612 //      > deletes PerfMemory resources
3613 //   + Return to caller
3614 
3615 bool Threads::destroy_vm() {
3616   JavaThread* thread = JavaThread::current();
3617 
3618   // Wait until we are the last non-daemon thread to execute
3619   { MutexLocker nu(Threads_lock);
3620     while (Threads::number_of_non_daemon_threads() > 1 )
3621       // This wait should make safepoint checks, wait without a timeout,
3622       // and wait as a suspend-equivalent condition.
3623       //
3624       // Note: If the FlatProfiler is running and this thread is waiting
3625       // for another non-daemon thread to finish, then the FlatProfiler
3626       // is waiting for the external suspend request on this thread to
3627       // complete. wait_for_ext_suspend_completion() will eventually
3628       // timeout, but that takes time. Making this wait a suspend-
3629       // equivalent condition solves that timeout problem.
3630       //
3631       Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
3632                          Mutex::_as_suspend_equivalent_flag);
3633   }
3634 
3635   // Hang forever on exit if we are reporting an error.
3636   if (ShowMessageBoxOnError && is_error_reported()) {
3637     os::infinite_sleep();
3638   }
3639 
3640   if (JDK_Version::is_jdk12x_version()) {
3641     // We are the last thread running, so check if finalizers should be run.
3642     // For 1.3 or later this is done in thread->invoke_shutdown_hooks()
3643     HandleMark rm(thread);
3644     Universe::run_finalizers_on_exit();
3645   } else {
3646     // run Java level shutdown hooks
3647     thread->invoke_shutdown_hooks();
3648   }
3649 
3650   before_exit(thread);
3651 
3652   thread->exit(true);
3653 
3654   // Stop VM thread.
3655   {
3656     // 4945125 The vm thread comes to a safepoint during exit.
3657     // GC vm_operations can get caught at the safepoint, and the
3658     // heap is unparseable if they are caught. Grab the Heap_lock
3659     // to prevent this. The GC vm_operations will not be able to
3660     // queue until after the vm thread is dead.
3661     MutexLocker ml(Heap_lock);
3662 
3663     VMThread::wait_for_vm_thread_exit();
3664     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
3665     VMThread::destroy();
3666   }
3667 
3668   // clean up ideal graph printers
3669 #if defined(COMPILER2) && !defined(PRODUCT)
3670   IdealGraphPrinter::clean_up();
3671 #endif
3672 
3673   // Now, all Java threads are gone except daemon threads. Daemon threads
3674   // running Java code or in VM are stopped by the Safepoint. However,
3675   // daemon threads executing native code are still running.  But they
3676   // will be stopped at native=>Java/VM barriers. Note that we can't
3677   // simply kill or suspend them, as it is inherently deadlock-prone.
3678 
3679 #ifndef PRODUCT
3680   // disable function tracing at JNI/JVM barriers
3681   TraceJNICalls = false;
3682   TraceJVMCalls = false;
3683   TraceRuntimeCalls = false;
3684 #endif
3685 
3686   VM_Exit::set_vm_exited();
3687 
3688   notify_vm_shutdown();
3689 
3690   delete thread;
3691 
3692   // exit_globals() will delete tty
3693   exit_globals();
3694 
3695   return true;
3696 }
3697 
3698 
3699 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
3700   if (version == JNI_VERSION_1_1) return JNI_TRUE;
3701   return is_supported_jni_version(version);
3702 }
3703 
3704 
3705 jboolean Threads::is_supported_jni_version(jint version) {
3706   if (version == JNI_VERSION_1_2) return JNI_TRUE;
3707   if (version == JNI_VERSION_1_4) return JNI_TRUE;
3708   if (version == JNI_VERSION_1_6) return JNI_TRUE;
3709   return JNI_FALSE;
3710 }
3711 
3712 
3713 void Threads::add(JavaThread* p, bool force_daemon) {
3714   // The threads lock must be owned at this point
3715   assert_locked_or_safepoint(Threads_lock);
3716 
3717   // See the comment for this method in thread.hpp for its purpose and
3718   // why it is called here.
3719   p->initialize_queues();
3720   p->set_next(_thread_list);
3721   _thread_list = p;
3722   _number_of_threads++;
3723   oop threadObj = p->threadObj();
3724   bool daemon = true;
3725   // Bootstrapping problem: threadObj can be null for initial
3726   // JavaThread (or for threads attached via JNI)
3727   if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
3728     _number_of_non_daemon_threads++;
3729     daemon = false;
3730   }
3731 
3732   ThreadService::add_thread(p, daemon);
3733 
3734   // Possible GC point.
3735   Events::log("Thread added: " INTPTR_FORMAT, p);
3736 }
3737 
3738 void Threads::remove(JavaThread* p) {
3739   // Extra scope needed for Thread_lock, so we can check
3740   // that we do not remove thread without safepoint code notice
3741   { MutexLocker ml(Threads_lock);
3742 
3743     assert(includes(p), "p must be present");
3744 
3745     JavaThread* current = _thread_list;
3746     JavaThread* prev    = NULL;
3747 
3748     while (current != p) {
3749       prev    = current;
3750       current = current->next();
3751     }
3752 
3753     if (prev) {
3754       prev->set_next(current->next());
3755     } else {
3756       _thread_list = p->next();
3757     }
3758     _number_of_threads--;
3759     oop threadObj = p->threadObj();
3760     bool daemon = true;
3761     if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
3762       _number_of_non_daemon_threads--;
3763       daemon = false;
3764 
3765       // Only one thread left, do a notify on the Threads_lock so a thread waiting
3766       // on destroy_vm will wake up.
3767       if (number_of_non_daemon_threads() == 1)
3768         Threads_lock->notify_all();
3769     }
3770     ThreadService::remove_thread(p, daemon);
3771 
3772     // Make sure that safepoint code disregard this thread. This is needed since
3773     // the thread might mess around with locks after this point. This can cause it
3774     // to do callbacks into the safepoint code. However, the safepoint code is not aware
3775     // of this thread since it is removed from the queue.
3776     p->set_terminated_value();
3777   } // unlock Threads_lock
3778 
3779   // Since Events::log uses a lock, we grab it outside the Threads_lock
3780   Events::log("Thread exited: " INTPTR_FORMAT, p);
3781 }
3782 
3783 // Threads_lock must be held when this is called (or must be called during a safepoint)
3784 bool Threads::includes(JavaThread* p) {
3785   assert(Threads_lock->is_locked(), "sanity check");
3786   ALL_JAVA_THREADS(q) {
3787     if (q == p ) {
3788       return true;
3789     }
3790   }
3791   return false;
3792 }
3793 
3794 // Operations on the Threads list for GC.  These are not explicitly locked,
3795 // but the garbage collector must provide a safe context for them to run.
3796 // In particular, these things should never be called when the Threads_lock
3797 // is held by some other thread. (Note: the Safepoint abstraction also
3798 // uses the Threads_lock to gurantee this property. It also makes sure that
3799 // all threads gets blocked when exiting or starting).
3800 
3801 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3802   ALL_JAVA_THREADS(p) {
3803     p->oops_do(f, cf);
3804   }
3805   VMThread::vm_thread()->oops_do(f, cf);
3806 }
3807 
3808 void Threads::possibly_parallel_oops_do(OopClosure* f, CodeBlobClosure* cf) {
3809   // Introduce a mechanism allowing parallel threads to claim threads as
3810   // root groups.  Overhead should be small enough to use all the time,
3811   // even in sequential code.
3812   SharedHeap* sh = SharedHeap::heap();
3813   bool is_par = (sh->n_par_threads() > 0);
3814   int cp = SharedHeap::heap()->strong_roots_parity();
3815   ALL_JAVA_THREADS(p) {
3816     if (p->claim_oops_do(is_par, cp)) {
3817       p->oops_do(f, cf);
3818     }
3819   }
3820   VMThread* vmt = VMThread::vm_thread();
3821   if (vmt->claim_oops_do(is_par, cp))
3822     vmt->oops_do(f, cf);
3823 }
3824 
3825 #ifndef SERIALGC
3826 // Used by ParallelScavenge
3827 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
3828   ALL_JAVA_THREADS(p) {
3829     q->enqueue(new ThreadRootsTask(p));
3830   }
3831   q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
3832 }
3833 
3834 // Used by Parallel Old
3835 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
3836   ALL_JAVA_THREADS(p) {
3837     q->enqueue(new ThreadRootsMarkingTask(p));
3838   }
3839   q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
3840 }
3841 #endif // SERIALGC
3842 
3843 void Threads::nmethods_do(CodeBlobClosure* cf) {
3844   ALL_JAVA_THREADS(p) {
3845     p->nmethods_do(cf);
3846   }
3847   VMThread::vm_thread()->nmethods_do(cf);
3848 }
3849 
3850 void Threads::gc_epilogue() {
3851   ALL_JAVA_THREADS(p) {
3852     p->gc_epilogue();
3853   }
3854 }
3855 
3856 void Threads::gc_prologue() {
3857   ALL_JAVA_THREADS(p) {
3858     p->gc_prologue();
3859   }
3860 }
3861 
3862 void Threads::deoptimized_wrt_marked_nmethods() {
3863   ALL_JAVA_THREADS(p) {
3864     p->deoptimized_wrt_marked_nmethods();
3865   }
3866 }
3867 
3868 
3869 // Get count Java threads that are waiting to enter the specified monitor.
3870 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
3871   address monitor, bool doLock) {
3872   assert(doLock || SafepointSynchronize::is_at_safepoint(),
3873     "must grab Threads_lock or be at safepoint");
3874   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
3875 
3876   int i = 0;
3877   {
3878     MutexLockerEx ml(doLock ? Threads_lock : NULL);
3879     ALL_JAVA_THREADS(p) {
3880       if (p->is_Compiler_thread()) continue;
3881 
3882       address pending = (address)p->current_pending_monitor();
3883       if (pending == monitor) {             // found a match
3884         if (i < count) result->append(p);   // save the first count matches
3885         i++;
3886       }
3887     }
3888   }
3889   return result;
3890 }
3891 
3892 
3893 JavaThread *Threads::owning_thread_from_monitor_owner(address owner, bool doLock) {
3894   assert(doLock ||
3895          Threads_lock->owned_by_self() ||
3896          SafepointSynchronize::is_at_safepoint(),
3897          "must grab Threads_lock or be at safepoint");
3898 
3899   // NULL owner means not locked so we can skip the search
3900   if (owner == NULL) return NULL;
3901 
3902   {
3903     MutexLockerEx ml(doLock ? Threads_lock : NULL);
3904     ALL_JAVA_THREADS(p) {
3905       // first, see if owner is the address of a Java thread
3906       if (owner == (address)p) return p;
3907     }
3908   }
3909   assert(UseHeavyMonitors == false, "Did not find owning Java thread with UseHeavyMonitors enabled");
3910   if (UseHeavyMonitors) return NULL;
3911 
3912   //
3913   // If we didn't find a matching Java thread and we didn't force use of
3914   // heavyweight monitors, then the owner is the stack address of the
3915   // Lock Word in the owning Java thread's stack.
3916   //
3917   JavaThread* the_owner = NULL;
3918   {
3919     MutexLockerEx ml(doLock ? Threads_lock : NULL);
3920     ALL_JAVA_THREADS(q) {
3921       if (q->is_lock_owned(owner)) {
3922         the_owner = q;
3923         break;
3924       }
3925     }
3926   }
3927   assert(the_owner != NULL, "Did not find owning Java thread for lock word address");
3928   return the_owner;
3929 }
3930 
3931 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
3932 void Threads::print_on(outputStream* st, bool print_stacks, bool internal_format, bool print_concurrent_locks) {
3933   char buf[32];
3934   st->print_cr(os::local_time_string(buf, sizeof(buf)));
3935 
3936   st->print_cr("Full thread dump %s (%s %s):",
3937                 Abstract_VM_Version::vm_name(),
3938                 Abstract_VM_Version::vm_release(),
3939                 Abstract_VM_Version::vm_info_string()
3940                );
3941   st->cr();
3942 
3943 #ifndef SERIALGC
3944   // Dump concurrent locks
3945   ConcurrentLocksDump concurrent_locks;
3946   if (print_concurrent_locks) {
3947     concurrent_locks.dump_at_safepoint();
3948   }
3949 #endif // SERIALGC
3950 
3951   ALL_JAVA_THREADS(p) {
3952     ResourceMark rm;
3953     p->print_on(st);
3954     if (print_stacks) {
3955       if (internal_format) {
3956         p->trace_stack();
3957       } else {
3958         p->print_stack_on(st);
3959       }
3960     }
3961     st->cr();
3962 #ifndef SERIALGC
3963     if (print_concurrent_locks) {
3964       concurrent_locks.print_locks_on(p, st);
3965     }
3966 #endif // SERIALGC
3967   }
3968 
3969   VMThread::vm_thread()->print_on(st);
3970   st->cr();
3971   Universe::heap()->print_gc_threads_on(st);
3972   WatcherThread* wt = WatcherThread::watcher_thread();
3973   if (wt != NULL) wt->print_on(st);
3974   st->cr();
3975   CompileBroker::print_compiler_threads_on(st);
3976   st->flush();
3977 }
3978 
3979 // Threads::print_on_error() is called by fatal error handler. It's possible
3980 // that VM is not at safepoint and/or current thread is inside signal handler.
3981 // Don't print stack trace, as the stack may not be walkable. Don't allocate
3982 // memory (even in resource area), it might deadlock the error handler.
3983 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, int buflen) {
3984   bool found_current = false;
3985   st->print_cr("Java Threads: ( => current thread )");
3986   ALL_JAVA_THREADS(thread) {
3987     bool is_current = (current == thread);
3988     found_current = found_current || is_current;
3989 
3990     st->print("%s", is_current ? "=>" : "  ");
3991 
3992     st->print(PTR_FORMAT, thread);
3993     st->print(" ");
3994     thread->print_on_error(st, buf, buflen);
3995     st->cr();
3996   }
3997   st->cr();
3998 
3999   st->print_cr("Other Threads:");
4000   if (VMThread::vm_thread()) {
4001     bool is_current = (current == VMThread::vm_thread());
4002     found_current = found_current || is_current;
4003     st->print("%s", current == VMThread::vm_thread() ? "=>" : "  ");
4004 
4005     st->print(PTR_FORMAT, VMThread::vm_thread());
4006     st->print(" ");
4007     VMThread::vm_thread()->print_on_error(st, buf, buflen);
4008     st->cr();
4009   }
4010   WatcherThread* wt = WatcherThread::watcher_thread();
4011   if (wt != NULL) {
4012     bool is_current = (current == wt);
4013     found_current = found_current || is_current;
4014     st->print("%s", is_current ? "=>" : "  ");
4015 
4016     st->print(PTR_FORMAT, wt);
4017     st->print(" ");
4018     wt->print_on_error(st, buf, buflen);
4019     st->cr();
4020   }
4021   if (!found_current) {
4022     st->cr();
4023     st->print("=>" PTR_FORMAT " (exited) ", current);
4024     current->print_on_error(st, buf, buflen);
4025     st->cr();
4026   }
4027 }
4028 
4029 // Internal SpinLock and Mutex
4030 // Based on ParkEvent
4031 
4032 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4033 //
4034 // We employ SpinLocks _only for low-contention, fixed-length
4035 // short-duration critical sections where we're concerned
4036 // about native mutex_t or HotSpot Mutex:: latency.
4037 // The mux construct provides a spin-then-block mutual exclusion
4038 // mechanism.
4039 //
4040 // Testing has shown that contention on the ListLock guarding gFreeList
4041 // is common.  If we implement ListLock as a simple SpinLock it's common
4042 // for the JVM to devolve to yielding with little progress.  This is true
4043 // despite the fact that the critical sections protected by ListLock are
4044 // extremely short.
4045 //
4046 // TODO-FIXME: ListLock should be of type SpinLock.
4047 // We should make this a 1st-class type, integrated into the lock
4048 // hierarchy as leaf-locks.  Critically, the SpinLock structure
4049 // should have sufficient padding to avoid false-sharing and excessive
4050 // cache-coherency traffic.
4051 
4052 
4053 typedef volatile int SpinLockT ;
4054 
4055 void Thread::SpinAcquire (volatile int * adr, const char * LockName) {
4056   if (Atomic::cmpxchg (1, adr, 0) == 0) {
4057      return ;   // normal fast-path return
4058   }
4059 
4060   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4061   TEVENT (SpinAcquire - ctx) ;
4062   int ctr = 0 ;
4063   int Yields = 0 ;
4064   for (;;) {
4065      while (*adr != 0) {
4066         ++ctr ;
4067         if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4068            if (Yields > 5) {
4069              // Consider using a simple NakedSleep() instead.
4070              // Then SpinAcquire could be called by non-JVM threads
4071              Thread::current()->_ParkEvent->park(1) ;
4072            } else {
4073              os::NakedYield() ;
4074              ++Yields ;
4075            }
4076         } else {
4077            SpinPause() ;
4078         }
4079      }
4080      if (Atomic::cmpxchg (1, adr, 0) == 0) return ;
4081   }
4082 }
4083 
4084 void Thread::SpinRelease (volatile int * adr) {
4085   assert (*adr != 0, "invariant") ;
4086   OrderAccess::fence() ;      // guarantee at least release consistency.
4087   // Roach-motel semantics.
4088   // It's safe if subsequent LDs and STs float "up" into the critical section,
4089   // but prior LDs and STs within the critical section can't be allowed
4090   // to reorder or float past the ST that releases the lock.
4091   *adr = 0 ;
4092 }
4093 
4094 // muxAcquire and muxRelease:
4095 //
4096 // *  muxAcquire and muxRelease support a single-word lock-word construct.
4097 //    The LSB of the word is set IFF the lock is held.
4098 //    The remainder of the word points to the head of a singly-linked list
4099 //    of threads blocked on the lock.
4100 //
4101 // *  The current implementation of muxAcquire-muxRelease uses its own
4102 //    dedicated Thread._MuxEvent instance.  If we're interested in
4103 //    minimizing the peak number of extant ParkEvent instances then
4104 //    we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4105 //    as certain invariants were satisfied.  Specifically, care would need
4106 //    to be taken with regards to consuming unpark() "permits".
4107 //    A safe rule of thumb is that a thread would never call muxAcquire()
4108 //    if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4109 //    park().  Otherwise the _ParkEvent park() operation in muxAcquire() could
4110 //    consume an unpark() permit intended for monitorenter, for instance.
4111 //    One way around this would be to widen the restricted-range semaphore
4112 //    implemented in park().  Another alternative would be to provide
4113 //    multiple instances of the PlatformEvent() for each thread.  One
4114 //    instance would be dedicated to muxAcquire-muxRelease, for instance.
4115 //
4116 // *  Usage:
4117 //    -- Only as leaf locks
4118 //    -- for short-term locking only as muxAcquire does not perform
4119 //       thread state transitions.
4120 //
4121 // Alternatives:
4122 // *  We could implement muxAcquire and muxRelease with MCS or CLH locks
4123 //    but with parking or spin-then-park instead of pure spinning.
4124 // *  Use Taura-Oyama-Yonenzawa locks.
4125 // *  It's possible to construct a 1-0 lock if we encode the lockword as
4126 //    (List,LockByte).  Acquire will CAS the full lockword while Release
4127 //    will STB 0 into the LockByte.  The 1-0 scheme admits stranding, so
4128 //    acquiring threads use timers (ParkTimed) to detect and recover from
4129 //    the stranding window.  Thread/Node structures must be aligned on 256-byte
4130 //    boundaries by using placement-new.
4131 // *  Augment MCS with advisory back-link fields maintained with CAS().
4132 //    Pictorially:  LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4133 //    The validity of the backlinks must be ratified before we trust the value.
4134 //    If the backlinks are invalid the exiting thread must back-track through the
4135 //    the forward links, which are always trustworthy.
4136 // *  Add a successor indication.  The LockWord is currently encoded as
4137 //    (List, LOCKBIT:1).  We could also add a SUCCBIT or an explicit _succ variable
4138 //    to provide the usual futile-wakeup optimization.
4139 //    See RTStt for details.
4140 // *  Consider schedctl.sc_nopreempt to cover the critical section.
4141 //
4142 
4143 
4144 typedef volatile intptr_t MutexT ;      // Mux Lock-word
4145 enum MuxBits { LOCKBIT = 1 } ;
4146 
4147 void Thread::muxAcquire (volatile intptr_t * Lock, const char * LockName) {
4148   intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ;
4149   if (w == 0) return ;
4150   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4151      return ;
4152   }
4153 
4154   TEVENT (muxAcquire - Contention) ;
4155   ParkEvent * const Self = Thread::current()->_MuxEvent ;
4156   assert ((intptr_t(Self) & LOCKBIT) == 0, "invariant") ;
4157   for (;;) {
4158      int its = (os::is_MP() ? 100 : 0) + 1 ;
4159 
4160      // Optional spin phase: spin-then-park strategy
4161      while (--its >= 0) {
4162        w = *Lock ;
4163        if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4164           return ;
4165        }
4166      }
4167 
4168      Self->reset() ;
4169      Self->OnList = intptr_t(Lock) ;
4170      // The following fence() isn't _strictly necessary as the subsequent
4171      // CAS() both serializes execution and ratifies the fetched *Lock value.
4172      OrderAccess::fence();
4173      for (;;) {
4174         w = *Lock ;
4175         if ((w & LOCKBIT) == 0) {
4176             if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4177                 Self->OnList = 0 ;   // hygiene - allows stronger asserts
4178                 return ;
4179             }
4180             continue ;      // Interference -- *Lock changed -- Just retry
4181         }
4182         assert (w & LOCKBIT, "invariant") ;
4183         Self->ListNext = (ParkEvent *) (w & ~LOCKBIT );
4184         if (Atomic::cmpxchg_ptr (intptr_t(Self)|LOCKBIT, Lock, w) == w) break ;
4185      }
4186 
4187      while (Self->OnList != 0) {
4188         Self->park() ;
4189      }
4190   }
4191 }
4192 
4193 void Thread::muxAcquireW (volatile intptr_t * Lock, ParkEvent * ev) {
4194   intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ;
4195   if (w == 0) return ;
4196   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4197     return ;
4198   }
4199 
4200   TEVENT (muxAcquire - Contention) ;
4201   ParkEvent * ReleaseAfter = NULL ;
4202   if (ev == NULL) {
4203     ev = ReleaseAfter = ParkEvent::Allocate (NULL) ;
4204   }
4205   assert ((intptr_t(ev) & LOCKBIT) == 0, "invariant") ;
4206   for (;;) {
4207     guarantee (ev->OnList == 0, "invariant") ;
4208     int its = (os::is_MP() ? 100 : 0) + 1 ;
4209 
4210     // Optional spin phase: spin-then-park strategy
4211     while (--its >= 0) {
4212       w = *Lock ;
4213       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4214         if (ReleaseAfter != NULL) {
4215           ParkEvent::Release (ReleaseAfter) ;
4216         }
4217         return ;
4218       }
4219     }
4220 
4221     ev->reset() ;
4222     ev->OnList = intptr_t(Lock) ;
4223     // The following fence() isn't _strictly necessary as the subsequent
4224     // CAS() both serializes execution and ratifies the fetched *Lock value.
4225     OrderAccess::fence();
4226     for (;;) {
4227       w = *Lock ;
4228       if ((w & LOCKBIT) == 0) {
4229         if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4230           ev->OnList = 0 ;
4231           // We call ::Release while holding the outer lock, thus
4232           // artificially lengthening the critical section.
4233           // Consider deferring the ::Release() until the subsequent unlock(),
4234           // after we've dropped the outer lock.
4235           if (ReleaseAfter != NULL) {
4236             ParkEvent::Release (ReleaseAfter) ;
4237           }
4238           return ;
4239         }
4240         continue ;      // Interference -- *Lock changed -- Just retry
4241       }
4242       assert (w & LOCKBIT, "invariant") ;
4243       ev->ListNext = (ParkEvent *) (w & ~LOCKBIT );
4244       if (Atomic::cmpxchg_ptr (intptr_t(ev)|LOCKBIT, Lock, w) == w) break ;
4245     }
4246 
4247     while (ev->OnList != 0) {
4248       ev->park() ;
4249     }
4250   }
4251 }
4252 
4253 // Release() must extract a successor from the list and then wake that thread.
4254 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4255 // similar to that used by ParkEvent::Allocate() and ::Release().  DMR-based
4256 // Release() would :
4257 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4258 // (B) Extract a successor from the private list "in-hand"
4259 // (C) attempt to CAS() the residual back into *Lock over null.
4260 //     If there were any newly arrived threads and the CAS() would fail.
4261 //     In that case Release() would detach the RATs, re-merge the list in-hand
4262 //     with the RATs and repeat as needed.  Alternately, Release() might
4263 //     detach and extract a successor, but then pass the residual list to the wakee.
4264 //     The wakee would be responsible for reattaching and remerging before it
4265 //     competed for the lock.
4266 //
4267 // Both "pop" and DMR are immune from ABA corruption -- there can be
4268 // multiple concurrent pushers, but only one popper or detacher.
4269 // This implementation pops from the head of the list.  This is unfair,
4270 // but tends to provide excellent throughput as hot threads remain hot.
4271 // (We wake recently run threads first).
4272 
4273 void Thread::muxRelease (volatile intptr_t * Lock)  {
4274   for (;;) {
4275     const intptr_t w = Atomic::cmpxchg_ptr (0, Lock, LOCKBIT) ;
4276     assert (w & LOCKBIT, "invariant") ;
4277     if (w == LOCKBIT) return ;
4278     ParkEvent * List = (ParkEvent *) (w & ~LOCKBIT) ;
4279     assert (List != NULL, "invariant") ;
4280     assert (List->OnList == intptr_t(Lock), "invariant") ;
4281     ParkEvent * nxt = List->ListNext ;
4282 
4283     // The following CAS() releases the lock and pops the head element.
4284     if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4285       continue ;
4286     }
4287     List->OnList = 0 ;
4288     OrderAccess::fence() ;
4289     List->unpark () ;
4290     return ;
4291   }
4292 }
4293 
4294 
4295 void Threads::verify() {
4296   ALL_JAVA_THREADS(p) {
4297     p->verify();
4298   }
4299   VMThread* thread = VMThread::vm_thread();
4300   if (thread != NULL) thread->verify();
4301 }