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 #ifdef KERNEL
 966 static void set_jkernel_boot_classloader_hook(TRAPS) {
 967   klassOop k = SystemDictionary::sun_jkernel_DownloadManager_klass();
 968   instanceKlassHandle klass (THREAD, k);
 969 
 970   if (k == NULL) {
 971     // sun.jkernel.DownloadManager may not present in the JDK; just return
 972     return;
 973   }
 974 
 975   JavaValue result(T_VOID);
 976   JavaCalls::call_static(&result, klass, vmSymbols::setBootClassLoaderHook_name(),
 977                                          vmSymbols::void_method_signature(), CHECK);
 978 }
 979 #endif // KERNEL
 980 
 981 // General purpose hook into Java code, run once when the VM is initialized.
 982 // The Java library method itself may be changed independently from the VM.
 983 static void call_postVMInitHook(TRAPS) {
 984   klassOop k = SystemDictionary::sun_misc_PostVMInitHook_klass();
 985   instanceKlassHandle klass (THREAD, k);
 986   if (klass.not_null()) {
 987     JavaValue result(T_VOID);
 988     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
 989                                            vmSymbols::void_method_signature(),
 990                                            CHECK);
 991   }
 992 }
 993 
 994 static void reset_vm_info_property(TRAPS) {
 995   // the vm info string
 996   ResourceMark rm(THREAD);
 997   const char *vm_info = VM_Version::vm_info_string();
 998 
 999   // java.lang.System class
1000   klassOop k =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1001   instanceKlassHandle klass (THREAD, k);
1002 
1003   // setProperty arguments
1004   Handle key_str    = java_lang_String::create_from_str("java.vm.info", CHECK);
1005   Handle value_str  = java_lang_String::create_from_str(vm_info, CHECK);
1006 
1007   // return value
1008   JavaValue r(T_OBJECT);
1009 
1010   // public static String setProperty(String key, String value);
1011   JavaCalls::call_static(&r,
1012                          klass,
1013                          vmSymbols::setProperty_name(),
1014                          vmSymbols::string_string_string_signature(),
1015                          key_str,
1016                          value_str,
1017                          CHECK);
1018 }
1019 
1020 
1021 void JavaThread::allocate_threadObj(Handle thread_group, char* thread_name, bool daemon, TRAPS) {
1022   assert(thread_group.not_null(), "thread group should be specified");
1023   assert(threadObj() == NULL, "should only create Java thread object once");
1024 
1025   klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1026   instanceKlassHandle klass (THREAD, k);
1027   instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1028 
1029   java_lang_Thread::set_thread(thread_oop(), this);
1030   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1031   set_threadObj(thread_oop());
1032 
1033   JavaValue result(T_VOID);
1034   if (thread_name != NULL) {
1035     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1036     // Thread gets assigned specified name and null target
1037     JavaCalls::call_special(&result,
1038                             thread_oop,
1039                             klass,
1040                             vmSymbols::object_initializer_name(),
1041                             vmSymbols::threadgroup_string_void_signature(),
1042                             thread_group, // Argument 1
1043                             name,         // Argument 2
1044                             THREAD);
1045   } else {
1046     // Thread gets assigned name "Thread-nnn" and null target
1047     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1048     JavaCalls::call_special(&result,
1049                             thread_oop,
1050                             klass,
1051                             vmSymbols::object_initializer_name(),
1052                             vmSymbols::threadgroup_runnable_void_signature(),
1053                             thread_group, // Argument 1
1054                             Handle(),     // Argument 2
1055                             THREAD);
1056   }
1057 
1058 
1059   if (daemon) {
1060       java_lang_Thread::set_daemon(thread_oop());
1061   }
1062 
1063   if (HAS_PENDING_EXCEPTION) {
1064     return;
1065   }
1066 
1067   KlassHandle group(this, SystemDictionary::ThreadGroup_klass());
1068   Handle threadObj(this, this->threadObj());
1069 
1070   JavaCalls::call_special(&result,
1071                          thread_group,
1072                          group,
1073                          vmSymbols::add_method_name(),
1074                          vmSymbols::thread_void_signature(),
1075                          threadObj,          // Arg 1
1076                          THREAD);
1077 
1078 
1079 }
1080 
1081 // NamedThread --  non-JavaThread subclasses with multiple
1082 // uniquely named instances should derive from this.
1083 NamedThread::NamedThread() : Thread() {
1084   _name = NULL;
1085   _processed_thread = NULL;
1086 }
1087 
1088 NamedThread::~NamedThread() {
1089   if (_name != NULL) {
1090     FREE_C_HEAP_ARRAY(char, _name);
1091     _name = NULL;
1092   }
1093 }
1094 
1095 void NamedThread::set_name(const char* format, ...) {
1096   guarantee(_name == NULL, "Only get to set name once.");
1097   _name = NEW_C_HEAP_ARRAY(char, max_name_len);
1098   guarantee(_name != NULL, "alloc failure");
1099   va_list ap;
1100   va_start(ap, format);
1101   jio_vsnprintf(_name, max_name_len, format, ap);
1102   va_end(ap);
1103 }
1104 
1105 // ======= WatcherThread ========
1106 
1107 // The watcher thread exists to simulate timer interrupts.  It should
1108 // be replaced by an abstraction over whatever native support for
1109 // timer interrupts exists on the platform.
1110 
1111 WatcherThread* WatcherThread::_watcher_thread   = NULL;
1112 volatile bool  WatcherThread::_should_terminate = false;
1113 
1114 WatcherThread::WatcherThread() : Thread() {
1115   assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1116   if (os::create_thread(this, os::watcher_thread)) {
1117     _watcher_thread = this;
1118 
1119     // Set the watcher thread to the highest OS priority which should not be
1120     // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1121     // is created. The only normal thread using this priority is the reference
1122     // handler thread, which runs for very short intervals only.
1123     // If the VMThread's priority is not lower than the WatcherThread profiling
1124     // will be inaccurate.
1125     os::set_priority(this, MaxPriority);
1126     if (!DisableStartThread) {
1127       os::start_thread(this);
1128     }
1129   }
1130 }
1131 
1132 void WatcherThread::run() {
1133   assert(this == watcher_thread(), "just checking");
1134 
1135   this->record_stack_base_and_size();
1136   this->initialize_thread_local_storage();
1137   this->set_active_handles(JNIHandleBlock::allocate_block());
1138   while(!_should_terminate) {
1139     assert(watcher_thread() == Thread::current(),  "thread consistency check");
1140     assert(watcher_thread() == this,  "thread consistency check");
1141 
1142     // Calculate how long it'll be until the next PeriodicTask work
1143     // should be done, and sleep that amount of time.
1144     size_t time_to_wait = PeriodicTask::time_to_wait();
1145 
1146     // we expect this to timeout - we only ever get unparked when
1147     // we should terminate
1148     {
1149       OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1150 
1151       jlong prev_time = os::javaTimeNanos();
1152       for (;;) {
1153         int res= _SleepEvent->park(time_to_wait);
1154         if (res == OS_TIMEOUT || _should_terminate)
1155           break;
1156         // spurious wakeup of some kind
1157         jlong now = os::javaTimeNanos();
1158         time_to_wait -= (now - prev_time) / 1000000;
1159         if (time_to_wait <= 0)
1160           break;
1161         prev_time = now;
1162       }
1163     }
1164 
1165     if (is_error_reported()) {
1166       // A fatal error has happened, the error handler(VMError::report_and_die)
1167       // should abort JVM after creating an error log file. However in some
1168       // rare cases, the error handler itself might deadlock. Here we try to
1169       // kill JVM if the fatal error handler fails to abort in 2 minutes.
1170       //
1171       // This code is in WatcherThread because WatcherThread wakes up
1172       // periodically so the fatal error handler doesn't need to do anything;
1173       // also because the WatcherThread is less likely to crash than other
1174       // threads.
1175 
1176       for (;;) {
1177         if (!ShowMessageBoxOnError
1178          && (OnError == NULL || OnError[0] == '\0')
1179          && Arguments::abort_hook() == NULL) {
1180              os::sleep(this, 2 * 60 * 1000, false);
1181              fdStream err(defaultStream::output_fd());
1182              err.print_raw_cr("# [ timer expired, abort... ]");
1183              // skip atexit/vm_exit/vm_abort hooks
1184              os::die();
1185         }
1186 
1187         // Wake up 5 seconds later, the fatal handler may reset OnError or
1188         // ShowMessageBoxOnError when it is ready to abort.
1189         os::sleep(this, 5 * 1000, false);
1190       }
1191     }
1192 
1193     PeriodicTask::real_time_tick(time_to_wait);
1194 
1195     // If we have no more tasks left due to dynamic disenrollment,
1196     // shut down the thread since we don't currently support dynamic enrollment
1197     if (PeriodicTask::num_tasks() == 0) {
1198       _should_terminate = true;
1199     }
1200   }
1201 
1202   // Signal that it is terminated
1203   {
1204     MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1205     _watcher_thread = NULL;
1206     Terminator_lock->notify();
1207   }
1208 
1209   // Thread destructor usually does this..
1210   ThreadLocalStorage::set_thread(NULL);
1211 }
1212 
1213 void WatcherThread::start() {
1214   if (watcher_thread() == NULL) {
1215     _should_terminate = false;
1216     // Create the single instance of WatcherThread
1217     new WatcherThread();
1218   }
1219 }
1220 
1221 void WatcherThread::stop() {
1222   // it is ok to take late safepoints here, if needed
1223   MutexLocker mu(Terminator_lock);
1224   _should_terminate = true;
1225   OrderAccess::fence();  // ensure WatcherThread sees update in main loop
1226 
1227   Thread* watcher = watcher_thread();
1228   if (watcher != NULL)
1229     watcher->_SleepEvent->unpark();
1230 
1231   while(watcher_thread() != NULL) {
1232     // This wait should make safepoint checks, wait without a timeout,
1233     // and wait as a suspend-equivalent condition.
1234     //
1235     // Note: If the FlatProfiler is running, then this thread is waiting
1236     // for the WatcherThread to terminate and the WatcherThread, via the
1237     // FlatProfiler task, is waiting for the external suspend request on
1238     // this thread to complete. wait_for_ext_suspend_completion() will
1239     // eventually timeout, but that takes time. Making this wait a
1240     // suspend-equivalent condition solves that timeout problem.
1241     //
1242     Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1243                           Mutex::_as_suspend_equivalent_flag);
1244   }
1245 }
1246 
1247 void WatcherThread::print_on(outputStream* st) const {
1248   st->print("\"%s\" ", name());
1249   Thread::print_on(st);
1250   st->cr();
1251 }
1252 
1253 // ======= JavaThread ========
1254 
1255 // A JavaThread is a normal Java thread
1256 
1257 void JavaThread::initialize() {
1258   // Initialize fields
1259 
1260   // Set the claimed par_id to -1 (ie not claiming any par_ids)
1261   set_claimed_par_id(-1);
1262 
1263   set_saved_exception_pc(NULL);
1264   set_threadObj(NULL);
1265   _anchor.clear();
1266   set_entry_point(NULL);
1267   set_jni_functions(jni_functions());
1268   set_callee_target(NULL);
1269   set_vm_result(NULL);
1270   set_vm_result_2(NULL);
1271   set_vframe_array_head(NULL);
1272   set_vframe_array_last(NULL);
1273   set_deferred_locals(NULL);
1274   set_deopt_mark(NULL);
1275   set_deopt_nmethod(NULL);
1276   clear_must_deopt_id();
1277   set_monitor_chunks(NULL);
1278   set_next(NULL);
1279   set_thread_state(_thread_new);
1280   _terminated = _not_terminated;
1281   _privileged_stack_top = NULL;
1282   _array_for_gc = NULL;
1283   _suspend_equivalent = false;
1284   _in_deopt_handler = 0;
1285   _doing_unsafe_access = false;
1286   _stack_guard_state = stack_guard_unused;
1287   _exception_oop = NULL;
1288   _exception_pc  = 0;
1289   _exception_handler_pc = 0;
1290   _exception_stack_size = 0;
1291   _is_method_handle_return = 0;
1292   _jvmti_thread_state= NULL;
1293   _should_post_on_exceptions_flag = JNI_FALSE;
1294   _jvmti_get_loaded_classes_closure = NULL;
1295   _interp_only_mode    = 0;
1296   _special_runtime_exit_condition = _no_async_condition;
1297   _pending_async_exception = NULL;
1298   _is_compiling = false;
1299   _thread_stat = NULL;
1300   _thread_stat = new ThreadStatistics();
1301   _blocked_on_compilation = false;
1302   _jni_active_critical = 0;
1303   _do_not_unlock_if_synchronized = false;
1304   _cached_monitor_info = NULL;
1305   _parker = Parker::Allocate(this) ;
1306 
1307 #ifndef PRODUCT
1308   _jmp_ring_index = 0;
1309   for (int ji = 0 ; ji < jump_ring_buffer_size ; ji++ ) {
1310     record_jump(NULL, NULL, NULL, 0);
1311   }
1312 #endif /* PRODUCT */
1313 
1314   set_thread_profiler(NULL);
1315   if (FlatProfiler::is_active()) {
1316     // This is where we would decide to either give each thread it's own profiler
1317     // or use one global one from FlatProfiler,
1318     // or up to some count of the number of profiled threads, etc.
1319     ThreadProfiler* pp = new ThreadProfiler();
1320     pp->engage();
1321     set_thread_profiler(pp);
1322   }
1323 
1324   // Setup safepoint state info for this thread
1325   ThreadSafepointState::create(this);
1326 
1327   debug_only(_java_call_counter = 0);
1328 
1329   // JVMTI PopFrame support
1330   _popframe_condition = popframe_inactive;
1331   _popframe_preserved_args = NULL;
1332   _popframe_preserved_args_size = 0;
1333 
1334   pd_initialize();
1335 }
1336 
1337 #ifndef SERIALGC
1338 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1339 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1340 #endif // !SERIALGC
1341 
1342 JavaThread::JavaThread(bool is_attaching) :
1343   Thread()
1344 #ifndef SERIALGC
1345   , _satb_mark_queue(&_satb_mark_queue_set),
1346   _dirty_card_queue(&_dirty_card_queue_set)
1347 #endif // !SERIALGC
1348 {
1349   initialize();
1350   _is_attaching = is_attaching;
1351   assert(_deferred_card_mark.is_empty(), "Default MemRegion ctor");
1352 }
1353 
1354 bool JavaThread::reguard_stack(address cur_sp) {
1355   if (_stack_guard_state != stack_guard_yellow_disabled) {
1356     return true; // Stack already guarded or guard pages not needed.
1357   }
1358 
1359   if (register_stack_overflow()) {
1360     // For those architectures which have separate register and
1361     // memory stacks, we must check the register stack to see if
1362     // it has overflowed.
1363     return false;
1364   }
1365 
1366   // Java code never executes within the yellow zone: the latter is only
1367   // there to provoke an exception during stack banging.  If java code
1368   // is executing there, either StackShadowPages should be larger, or
1369   // some exception code in c1, c2 or the interpreter isn't unwinding
1370   // when it should.
1371   guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages");
1372 
1373   enable_stack_yellow_zone();
1374   return true;
1375 }
1376 
1377 bool JavaThread::reguard_stack(void) {
1378   return reguard_stack(os::current_stack_pointer());
1379 }
1380 
1381 
1382 void JavaThread::block_if_vm_exited() {
1383   if (_terminated == _vm_exited) {
1384     // _vm_exited is set at safepoint, and Threads_lock is never released
1385     // we will block here forever
1386     Threads_lock->lock_without_safepoint_check();
1387     ShouldNotReachHere();
1388   }
1389 }
1390 
1391 
1392 // Remove this ifdef when C1 is ported to the compiler interface.
1393 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1394 
1395 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1396   Thread()
1397 #ifndef SERIALGC
1398   , _satb_mark_queue(&_satb_mark_queue_set),
1399   _dirty_card_queue(&_dirty_card_queue_set)
1400 #endif // !SERIALGC
1401 {
1402   if (TraceThreadEvents) {
1403     tty->print_cr("creating thread %p", this);
1404   }
1405   initialize();
1406   _is_attaching = false;
1407   set_entry_point(entry_point);
1408   // Create the native thread itself.
1409   // %note runtime_23
1410   os::ThreadType thr_type = os::java_thread;
1411   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1412                                                      os::java_thread;
1413   os::create_thread(this, thr_type, stack_sz);
1414 
1415   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1416   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1417   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1418   // the exception consists of creating the exception object & initializing it, initialization
1419   // will leave the VM via a JavaCall and then all locks must be unlocked).
1420   //
1421   // The thread is still suspended when we reach here. Thread must be explicit started
1422   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1423   // by calling Threads:add. The reason why this is not done here, is because the thread
1424   // object must be fully initialized (take a look at JVM_Start)
1425 }
1426 
1427 JavaThread::~JavaThread() {
1428   if (TraceThreadEvents) {
1429       tty->print_cr("terminate thread %p", this);
1430   }
1431 
1432   // JSR166 -- return the parker to the free list
1433   Parker::Release(_parker);
1434   _parker = NULL ;
1435 
1436   // Free any remaining  previous UnrollBlock
1437   vframeArray* old_array = vframe_array_last();
1438 
1439   if (old_array != NULL) {
1440     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1441     old_array->set_unroll_block(NULL);
1442     delete old_info;
1443     delete old_array;
1444   }
1445 
1446   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1447   if (deferred != NULL) {
1448     // This can only happen if thread is destroyed before deoptimization occurs.
1449     assert(deferred->length() != 0, "empty array!");
1450     do {
1451       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1452       deferred->remove_at(0);
1453       // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1454       delete dlv;
1455     } while (deferred->length() != 0);
1456     delete deferred;
1457   }
1458 
1459   // All Java related clean up happens in exit
1460   ThreadSafepointState::destroy(this);
1461   if (_thread_profiler != NULL) delete _thread_profiler;
1462   if (_thread_stat != NULL) delete _thread_stat;
1463 }
1464 
1465 
1466 // The first routine called by a new Java thread
1467 void JavaThread::run() {
1468   // initialize thread-local alloc buffer related fields
1469   this->initialize_tlab();
1470 
1471   // used to test validitity of stack trace backs
1472   this->record_base_of_stack_pointer();
1473 
1474   // Record real stack base and size.
1475   this->record_stack_base_and_size();
1476 
1477   // Initialize thread local storage; set before calling MutexLocker
1478   this->initialize_thread_local_storage();
1479 
1480   this->create_stack_guard_pages();
1481 
1482   this->cache_global_variables();
1483 
1484   // Thread is now sufficient initialized to be handled by the safepoint code as being
1485   // in the VM. Change thread state from _thread_new to _thread_in_vm
1486   ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1487 
1488   assert(JavaThread::current() == this, "sanity check");
1489   assert(!Thread::current()->owns_locks(), "sanity check");
1490 
1491   DTRACE_THREAD_PROBE(start, this);
1492 
1493   // This operation might block. We call that after all safepoint checks for a new thread has
1494   // been completed.
1495   this->set_active_handles(JNIHandleBlock::allocate_block());
1496 
1497   if (JvmtiExport::should_post_thread_life()) {
1498     JvmtiExport::post_thread_start(this);
1499   }
1500 
1501   // We call another function to do the rest so we are sure that the stack addresses used
1502   // from there will be lower than the stack base just computed
1503   thread_main_inner();
1504 
1505   // Note, thread is no longer valid at this point!
1506 }
1507 
1508 
1509 void JavaThread::thread_main_inner() {
1510   assert(JavaThread::current() == this, "sanity check");
1511   assert(this->threadObj() != NULL, "just checking");
1512 
1513   // Execute thread entry point unless this thread has a pending exception
1514   // or has been stopped before starting.
1515   // Note: Due to JVM_StopThread we can have pending exceptions already!
1516   if (!this->has_pending_exception() &&
1517       !java_lang_Thread::is_stillborn(this->threadObj())) {
1518     HandleMark hm(this);
1519     this->entry_point()(this, this);
1520   }
1521 
1522   DTRACE_THREAD_PROBE(stop, this);
1523 
1524   this->exit(false);
1525   delete this;
1526 }
1527 
1528 
1529 static void ensure_join(JavaThread* thread) {
1530   // We do not need to grap the Threads_lock, since we are operating on ourself.
1531   Handle threadObj(thread, thread->threadObj());
1532   assert(threadObj.not_null(), "java thread object must exist");
1533   ObjectLocker lock(threadObj, thread);
1534   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1535   thread->clear_pending_exception();
1536   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1537   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1538   // Clear the native thread instance - this makes isAlive return false and allows the join()
1539   // to complete once we've done the notify_all below
1540   java_lang_Thread::set_thread(threadObj(), NULL);
1541   lock.notify_all(thread);
1542   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1543   thread->clear_pending_exception();
1544 }
1545 
1546 
1547 // For any new cleanup additions, please check to see if they need to be applied to
1548 // cleanup_failed_attach_current_thread as well.
1549 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1550   assert(this == JavaThread::current(),  "thread consistency check");
1551   if (!InitializeJavaLangSystem) return;
1552 
1553   HandleMark hm(this);
1554   Handle uncaught_exception(this, this->pending_exception());
1555   this->clear_pending_exception();
1556   Handle threadObj(this, this->threadObj());
1557   assert(threadObj.not_null(), "Java thread object should be created");
1558 
1559   if (get_thread_profiler() != NULL) {
1560     get_thread_profiler()->disengage();
1561     ResourceMark rm;
1562     get_thread_profiler()->print(get_thread_name());
1563   }
1564 
1565 
1566   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1567   {
1568     EXCEPTION_MARK;
1569 
1570     CLEAR_PENDING_EXCEPTION;
1571   }
1572   // FIXIT: The is_null check is only so it works better on JDK1.2 VM's. This
1573   // has to be fixed by a runtime query method
1574   if (!destroy_vm || JDK_Version::is_jdk12x_version()) {
1575     // JSR-166: change call from from ThreadGroup.uncaughtException to
1576     // java.lang.Thread.dispatchUncaughtException
1577     if (uncaught_exception.not_null()) {
1578       Handle group(this, java_lang_Thread::threadGroup(threadObj()));
1579       Events::log("uncaught exception INTPTR_FORMAT " " INTPTR_FORMAT " " INTPTR_FORMAT",
1580         (address)uncaught_exception(), (address)threadObj(), (address)group());
1581       {
1582         EXCEPTION_MARK;
1583         // Check if the method Thread.dispatchUncaughtException() exists. If so
1584         // call it.  Otherwise we have an older library without the JSR-166 changes,
1585         // so call ThreadGroup.uncaughtException()
1586         KlassHandle recvrKlass(THREAD, threadObj->klass());
1587         CallInfo callinfo;
1588         KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1589         LinkResolver::resolve_virtual_call(callinfo, threadObj, recvrKlass, thread_klass,
1590                                            vmSymbols::dispatchUncaughtException_name(),
1591                                            vmSymbols::throwable_void_signature(),
1592                                            KlassHandle(), false, false, THREAD);
1593         CLEAR_PENDING_EXCEPTION;
1594         methodHandle method = callinfo.selected_method();
1595         if (method.not_null()) {
1596           JavaValue result(T_VOID);
1597           JavaCalls::call_virtual(&result,
1598                                   threadObj, thread_klass,
1599                                   vmSymbols::dispatchUncaughtException_name(),
1600                                   vmSymbols::throwable_void_signature(),
1601                                   uncaught_exception,
1602                                   THREAD);
1603         } else {
1604           KlassHandle thread_group(THREAD, SystemDictionary::ThreadGroup_klass());
1605           JavaValue result(T_VOID);
1606           JavaCalls::call_virtual(&result,
1607                                   group, thread_group,
1608                                   vmSymbols::uncaughtException_name(),
1609                                   vmSymbols::thread_throwable_void_signature(),
1610                                   threadObj,           // Arg 1
1611                                   uncaught_exception,  // Arg 2
1612                                   THREAD);
1613         }
1614         CLEAR_PENDING_EXCEPTION;
1615       }
1616     }
1617 
1618     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1619     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1620     // is deprecated anyhow.
1621     { int count = 3;
1622       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1623         EXCEPTION_MARK;
1624         JavaValue result(T_VOID);
1625         KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1626         JavaCalls::call_virtual(&result,
1627                               threadObj, thread_klass,
1628                               vmSymbols::exit_method_name(),
1629                               vmSymbols::void_method_signature(),
1630                               THREAD);
1631         CLEAR_PENDING_EXCEPTION;
1632       }
1633     }
1634 
1635     // notify JVMTI
1636     if (JvmtiExport::should_post_thread_life()) {
1637       JvmtiExport::post_thread_end(this);
1638     }
1639 
1640     // We have notified the agents that we are exiting, before we go on,
1641     // we must check for a pending external suspend request and honor it
1642     // in order to not surprise the thread that made the suspend request.
1643     while (true) {
1644       {
1645         MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1646         if (!is_external_suspend()) {
1647           set_terminated(_thread_exiting);
1648           ThreadService::current_thread_exiting(this);
1649           break;
1650         }
1651         // Implied else:
1652         // Things get a little tricky here. We have a pending external
1653         // suspend request, but we are holding the SR_lock so we
1654         // can't just self-suspend. So we temporarily drop the lock
1655         // and then self-suspend.
1656       }
1657 
1658       ThreadBlockInVM tbivm(this);
1659       java_suspend_self();
1660 
1661       // We're done with this suspend request, but we have to loop around
1662       // and check again. Eventually we will get SR_lock without a pending
1663       // external suspend request and will be able to mark ourselves as
1664       // exiting.
1665     }
1666     // no more external suspends are allowed at this point
1667   } else {
1668     // before_exit() has already posted JVMTI THREAD_END events
1669   }
1670 
1671   // Notify waiters on thread object. This has to be done after exit() is called
1672   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1673   // group should have the destroyed bit set before waiters are notified).
1674   ensure_join(this);
1675   assert(!this->has_pending_exception(), "ensure_join should have cleared");
1676 
1677   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1678   // held by this thread must be released.  A detach operation must only
1679   // get here if there are no Java frames on the stack.  Therefore, any
1680   // owned monitors at this point MUST be JNI-acquired monitors which are
1681   // pre-inflated and in the monitor cache.
1682   //
1683   // ensure_join() ignores IllegalThreadStateExceptions, and so does this.
1684   if (exit_type == jni_detach && JNIDetachReleasesMonitors) {
1685     assert(!this->has_last_Java_frame(), "detaching with Java frames?");
1686     ObjectSynchronizer::release_monitors_owned_by_thread(this);
1687     assert(!this->has_pending_exception(), "release_monitors should have cleared");
1688   }
1689 
1690   // These things needs to be done while we are still a Java Thread. Make sure that thread
1691   // is in a consistent state, in case GC happens
1692   assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1693 
1694   if (active_handles() != NULL) {
1695     JNIHandleBlock* block = active_handles();
1696     set_active_handles(NULL);
1697     JNIHandleBlock::release_block(block);
1698   }
1699 
1700   if (free_handle_block() != NULL) {
1701     JNIHandleBlock* block = free_handle_block();
1702     set_free_handle_block(NULL);
1703     JNIHandleBlock::release_block(block);
1704   }
1705 
1706   // These have to be removed while this is still a valid thread.
1707   remove_stack_guard_pages();
1708 
1709   if (UseTLAB) {
1710     tlab().make_parsable(true);  // retire TLAB
1711   }
1712 
1713   if (JvmtiEnv::environments_might_exist()) {
1714     JvmtiExport::cleanup_thread(this);
1715   }
1716 
1717 #ifndef SERIALGC
1718   // We must flush G1-related buffers before removing a thread from
1719   // the list of active threads.
1720   if (UseG1GC) {
1721     flush_barrier_queues();
1722   }
1723 #endif
1724 
1725   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1726   Threads::remove(this);
1727 }
1728 
1729 #ifndef SERIALGC
1730 // Flush G1-related queues.
1731 void JavaThread::flush_barrier_queues() {
1732   satb_mark_queue().flush();
1733   dirty_card_queue().flush();
1734 }
1735 
1736 void JavaThread::initialize_queues() {
1737   assert(!SafepointSynchronize::is_at_safepoint(),
1738          "we should not be at a safepoint");
1739 
1740   ObjPtrQueue& satb_queue = satb_mark_queue();
1741   SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1742   // The SATB queue should have been constructed with its active
1743   // field set to false.
1744   assert(!satb_queue.is_active(), "SATB queue should not be active");
1745   assert(satb_queue.is_empty(), "SATB queue should be empty");
1746   // If we are creating the thread during a marking cycle, we should
1747   // set the active field of the SATB queue to true.
1748   if (satb_queue_set.is_active()) {
1749     satb_queue.set_active(true);
1750   }
1751 
1752   DirtyCardQueue& dirty_queue = dirty_card_queue();
1753   // The dirty card queue should have been constructed with its
1754   // active field set to true.
1755   assert(dirty_queue.is_active(), "dirty card queue should be active");
1756 }
1757 #endif // !SERIALGC
1758 
1759 void JavaThread::cleanup_failed_attach_current_thread() {
1760   if (get_thread_profiler() != NULL) {
1761     get_thread_profiler()->disengage();
1762     ResourceMark rm;
1763     get_thread_profiler()->print(get_thread_name());
1764   }
1765 
1766   if (active_handles() != NULL) {
1767     JNIHandleBlock* block = active_handles();
1768     set_active_handles(NULL);
1769     JNIHandleBlock::release_block(block);
1770   }
1771 
1772   if (free_handle_block() != NULL) {
1773     JNIHandleBlock* block = free_handle_block();
1774     set_free_handle_block(NULL);
1775     JNIHandleBlock::release_block(block);
1776   }
1777 
1778   // These have to be removed while this is still a valid thread.
1779   remove_stack_guard_pages();
1780 
1781   if (UseTLAB) {
1782     tlab().make_parsable(true);  // retire TLAB, if any
1783   }
1784 
1785 #ifndef SERIALGC
1786   if (UseG1GC) {
1787     flush_barrier_queues();
1788   }
1789 #endif
1790 
1791   Threads::remove(this);
1792   delete this;
1793 }
1794 
1795 
1796 
1797 
1798 JavaThread* JavaThread::active() {
1799   Thread* thread = ThreadLocalStorage::thread();
1800   assert(thread != NULL, "just checking");
1801   if (thread->is_Java_thread()) {
1802     return (JavaThread*) thread;
1803   } else {
1804     assert(thread->is_VM_thread(), "this must be a vm thread");
1805     VM_Operation* op = ((VMThread*) thread)->vm_operation();
1806     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
1807     assert(ret->is_Java_thread(), "must be a Java thread");
1808     return ret;
1809   }
1810 }
1811 
1812 bool JavaThread::is_lock_owned(address adr) const {
1813   if (Thread::is_lock_owned(adr)) return true;
1814 
1815   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
1816     if (chunk->contains(adr)) return true;
1817   }
1818 
1819   return false;
1820 }
1821 
1822 
1823 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
1824   chunk->set_next(monitor_chunks());
1825   set_monitor_chunks(chunk);
1826 }
1827 
1828 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
1829   guarantee(monitor_chunks() != NULL, "must be non empty");
1830   if (monitor_chunks() == chunk) {
1831     set_monitor_chunks(chunk->next());
1832   } else {
1833     MonitorChunk* prev = monitor_chunks();
1834     while (prev->next() != chunk) prev = prev->next();
1835     prev->set_next(chunk->next());
1836   }
1837 }
1838 
1839 // JVM support.
1840 
1841 // Note: this function shouldn't block if it's called in
1842 // _thread_in_native_trans state (such as from
1843 // check_special_condition_for_native_trans()).
1844 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
1845 
1846   if (has_last_Java_frame() && has_async_condition()) {
1847     // If we are at a polling page safepoint (not a poll return)
1848     // then we must defer async exception because live registers
1849     // will be clobbered by the exception path. Poll return is
1850     // ok because the call we a returning from already collides
1851     // with exception handling registers and so there is no issue.
1852     // (The exception handling path kills call result registers but
1853     //  this is ok since the exception kills the result anyway).
1854 
1855     if (is_at_poll_safepoint()) {
1856       // if the code we are returning to has deoptimized we must defer
1857       // the exception otherwise live registers get clobbered on the
1858       // exception path before deoptimization is able to retrieve them.
1859       //
1860       RegisterMap map(this, false);
1861       frame caller_fr = last_frame().sender(&map);
1862       assert(caller_fr.is_compiled_frame(), "what?");
1863       if (caller_fr.is_deoptimized_frame()) {
1864         if (TraceExceptions) {
1865           ResourceMark rm;
1866           tty->print_cr("deferred async exception at compiled safepoint");
1867         }
1868         return;
1869       }
1870     }
1871   }
1872 
1873   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
1874   if (condition == _no_async_condition) {
1875     // Conditions have changed since has_special_runtime_exit_condition()
1876     // was called:
1877     // - if we were here only because of an external suspend request,
1878     //   then that was taken care of above (or cancelled) so we are done
1879     // - if we were here because of another async request, then it has
1880     //   been cleared between the has_special_runtime_exit_condition()
1881     //   and now so again we are done
1882     return;
1883   }
1884 
1885   // Check for pending async. exception
1886   if (_pending_async_exception != NULL) {
1887     // Only overwrite an already pending exception, if it is not a threadDeath.
1888     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
1889 
1890       // We cannot call Exceptions::_throw(...) here because we cannot block
1891       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
1892 
1893       if (TraceExceptions) {
1894         ResourceMark rm;
1895         tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this);
1896         if (has_last_Java_frame() ) {
1897           frame f = last_frame();
1898           tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp());
1899         }
1900         tty->print_cr(" of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name());
1901       }
1902       _pending_async_exception = NULL;
1903       clear_has_async_exception();
1904     }
1905   }
1906 
1907   if (check_unsafe_error &&
1908       condition == _async_unsafe_access_error && !has_pending_exception()) {
1909     condition = _no_async_condition;  // done
1910     switch (thread_state()) {
1911     case _thread_in_vm:
1912       {
1913         JavaThread* THREAD = this;
1914         THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
1915       }
1916     case _thread_in_native:
1917       {
1918         ThreadInVMfromNative tiv(this);
1919         JavaThread* THREAD = this;
1920         THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
1921       }
1922     case _thread_in_Java:
1923       {
1924         ThreadInVMfromJava tiv(this);
1925         JavaThread* THREAD = this;
1926         THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
1927       }
1928     default:
1929       ShouldNotReachHere();
1930     }
1931   }
1932 
1933   assert(condition == _no_async_condition || has_pending_exception() ||
1934          (!check_unsafe_error && condition == _async_unsafe_access_error),
1935          "must have handled the async condition, if no exception");
1936 }
1937 
1938 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
1939   //
1940   // Check for pending external suspend. Internal suspend requests do
1941   // not use handle_special_runtime_exit_condition().
1942   // If JNIEnv proxies are allowed, don't self-suspend if the target
1943   // thread is not the current thread. In older versions of jdbx, jdbx
1944   // threads could call into the VM with another thread's JNIEnv so we
1945   // can be here operating on behalf of a suspended thread (4432884).
1946   bool do_self_suspend = is_external_suspend_with_lock();
1947   if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
1948     //
1949     // Because thread is external suspended the safepoint code will count
1950     // thread as at a safepoint. This can be odd because we can be here
1951     // as _thread_in_Java which would normally transition to _thread_blocked
1952     // at a safepoint. We would like to mark the thread as _thread_blocked
1953     // before calling java_suspend_self like all other callers of it but
1954     // we must then observe proper safepoint protocol. (We can't leave
1955     // _thread_blocked with a safepoint in progress). However we can be
1956     // here as _thread_in_native_trans so we can't use a normal transition
1957     // constructor/destructor pair because they assert on that type of
1958     // transition. We could do something like:
1959     //
1960     // JavaThreadState state = thread_state();
1961     // set_thread_state(_thread_in_vm);
1962     // {
1963     //   ThreadBlockInVM tbivm(this);
1964     //   java_suspend_self()
1965     // }
1966     // set_thread_state(_thread_in_vm_trans);
1967     // if (safepoint) block;
1968     // set_thread_state(state);
1969     //
1970     // but that is pretty messy. Instead we just go with the way the
1971     // code has worked before and note that this is the only path to
1972     // java_suspend_self that doesn't put the thread in _thread_blocked
1973     // mode.
1974 
1975     frame_anchor()->make_walkable(this);
1976     java_suspend_self();
1977 
1978     // We might be here for reasons in addition to the self-suspend request
1979     // so check for other async requests.
1980   }
1981 
1982   if (check_asyncs) {
1983     check_and_handle_async_exceptions();
1984   }
1985 }
1986 
1987 void JavaThread::send_thread_stop(oop java_throwable)  {
1988   assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
1989   assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
1990   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
1991 
1992   // Do not throw asynchronous exceptions against the compiler thread
1993   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
1994   if (is_Compiler_thread()) return;
1995 
1996   {
1997     // Actually throw the Throwable against the target Thread - however
1998     // only if there is no thread death exception installed already.
1999     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2000       // If the topmost frame is a runtime stub, then we are calling into
2001       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2002       // must deoptimize the caller before continuing, as the compiled  exception handler table
2003       // may not be valid
2004       if (has_last_Java_frame()) {
2005         frame f = last_frame();
2006         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2007           // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2008           RegisterMap reg_map(this, UseBiasedLocking);
2009           frame compiled_frame = f.sender(&reg_map);
2010           if (compiled_frame.can_be_deoptimized()) {
2011             Deoptimization::deoptimize(this, compiled_frame, &reg_map);
2012           }
2013         }
2014       }
2015 
2016       // Set async. pending exception in thread.
2017       set_pending_async_exception(java_throwable);
2018 
2019       if (TraceExceptions) {
2020        ResourceMark rm;
2021        tty->print_cr("Pending Async. exception installed of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name());
2022       }
2023       // for AbortVMOnException flag
2024       NOT_PRODUCT(Exceptions::debug_check_abort(instanceKlass::cast(_pending_async_exception->klass())->external_name()));
2025     }
2026   }
2027 
2028 
2029   // Interrupt thread so it will wake up from a potential wait()
2030   Thread::interrupt(this);
2031 }
2032 
2033 // External suspension mechanism.
2034 //
2035 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2036 // to any VM_locks and it is at a transition
2037 // Self-suspension will happen on the transition out of the vm.
2038 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2039 //
2040 // Guarantees on return:
2041 //   + Target thread will not execute any new bytecode (that's why we need to
2042 //     force a safepoint)
2043 //   + Target thread will not enter any new monitors
2044 //
2045 void JavaThread::java_suspend() {
2046   { MutexLocker mu(Threads_lock);
2047     if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2048        return;
2049     }
2050   }
2051 
2052   { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2053     if (!is_external_suspend()) {
2054       // a racing resume has cancelled us; bail out now
2055       return;
2056     }
2057 
2058     // suspend is done
2059     uint32_t debug_bits = 0;
2060     // Warning: is_ext_suspend_completed() may temporarily drop the
2061     // SR_lock to allow the thread to reach a stable thread state if
2062     // it is currently in a transient thread state.
2063     if (is_ext_suspend_completed(false /* !called_by_wait */,
2064                                  SuspendRetryDelay, &debug_bits) ) {
2065       return;
2066     }
2067   }
2068 
2069   VM_ForceSafepoint vm_suspend;
2070   VMThread::execute(&vm_suspend);
2071 }
2072 
2073 // Part II of external suspension.
2074 // A JavaThread self suspends when it detects a pending external suspend
2075 // request. This is usually on transitions. It is also done in places
2076 // where continuing to the next transition would surprise the caller,
2077 // e.g., monitor entry.
2078 //
2079 // Returns the number of times that the thread self-suspended.
2080 //
2081 // Note: DO NOT call java_suspend_self() when you just want to block current
2082 //       thread. java_suspend_self() is the second stage of cooperative
2083 //       suspension for external suspend requests and should only be used
2084 //       to complete an external suspend request.
2085 //
2086 int JavaThread::java_suspend_self() {
2087   int ret = 0;
2088 
2089   // we are in the process of exiting so don't suspend
2090   if (is_exiting()) {
2091      clear_external_suspend();
2092      return ret;
2093   }
2094 
2095   assert(_anchor.walkable() ||
2096     (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2097     "must have walkable stack");
2098 
2099   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2100 
2101   assert(!this->is_ext_suspended(),
2102     "a thread trying to self-suspend should not already be suspended");
2103 
2104   if (this->is_suspend_equivalent()) {
2105     // If we are self-suspending as a result of the lifting of a
2106     // suspend equivalent condition, then the suspend_equivalent
2107     // flag is not cleared until we set the ext_suspended flag so
2108     // that wait_for_ext_suspend_completion() returns consistent
2109     // results.
2110     this->clear_suspend_equivalent();
2111   }
2112 
2113   // A racing resume may have cancelled us before we grabbed SR_lock
2114   // above. Or another external suspend request could be waiting for us
2115   // by the time we return from SR_lock()->wait(). The thread
2116   // that requested the suspension may already be trying to walk our
2117   // stack and if we return now, we can change the stack out from under
2118   // it. This would be a "bad thing (TM)" and cause the stack walker
2119   // to crash. We stay self-suspended until there are no more pending
2120   // external suspend requests.
2121   while (is_external_suspend()) {
2122     ret++;
2123     this->set_ext_suspended();
2124 
2125     // _ext_suspended flag is cleared by java_resume()
2126     while (is_ext_suspended()) {
2127       this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2128     }
2129   }
2130 
2131   return ret;
2132 }
2133 
2134 #ifdef ASSERT
2135 // verify the JavaThread has not yet been published in the Threads::list, and
2136 // hence doesn't need protection from concurrent access at this stage
2137 void JavaThread::verify_not_published() {
2138   if (!Threads_lock->owned_by_self()) {
2139    MutexLockerEx ml(Threads_lock,  Mutex::_no_safepoint_check_flag);
2140    assert( !Threads::includes(this),
2141            "java thread shouldn't have been published yet!");
2142   }
2143   else {
2144    assert( !Threads::includes(this),
2145            "java thread shouldn't have been published yet!");
2146   }
2147 }
2148 #endif
2149 
2150 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2151 // progress or when _suspend_flags is non-zero.
2152 // Current thread needs to self-suspend if there is a suspend request and/or
2153 // block if a safepoint is in progress.
2154 // Async exception ISN'T checked.
2155 // Note only the ThreadInVMfromNative transition can call this function
2156 // directly and when thread state is _thread_in_native_trans
2157 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2158   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2159 
2160   JavaThread *curJT = JavaThread::current();
2161   bool do_self_suspend = thread->is_external_suspend();
2162 
2163   assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2164 
2165   // If JNIEnv proxies are allowed, don't self-suspend if the target
2166   // thread is not the current thread. In older versions of jdbx, jdbx
2167   // threads could call into the VM with another thread's JNIEnv so we
2168   // can be here operating on behalf of a suspended thread (4432884).
2169   if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2170     JavaThreadState state = thread->thread_state();
2171 
2172     // We mark this thread_blocked state as a suspend-equivalent so
2173     // that a caller to is_ext_suspend_completed() won't be confused.
2174     // The suspend-equivalent state is cleared by java_suspend_self().
2175     thread->set_suspend_equivalent();
2176 
2177     // If the safepoint code sees the _thread_in_native_trans state, it will
2178     // wait until the thread changes to other thread state. There is no
2179     // guarantee on how soon we can obtain the SR_lock and complete the
2180     // self-suspend request. It would be a bad idea to let safepoint wait for
2181     // too long. Temporarily change the state to _thread_blocked to
2182     // let the VM thread know that this thread is ready for GC. The problem
2183     // of changing thread state is that safepoint could happen just after
2184     // java_suspend_self() returns after being resumed, and VM thread will
2185     // see the _thread_blocked state. We must check for safepoint
2186     // after restoring the state and make sure we won't leave while a safepoint
2187     // is in progress.
2188     thread->set_thread_state(_thread_blocked);
2189     thread->java_suspend_self();
2190     thread->set_thread_state(state);
2191     // Make sure new state is seen by VM thread
2192     if (os::is_MP()) {
2193       if (UseMembar) {
2194         // Force a fence between the write above and read below
2195         OrderAccess::fence();
2196       } else {
2197         // Must use this rather than serialization page in particular on Windows
2198         InterfaceSupport::serialize_memory(thread);
2199       }
2200     }
2201   }
2202 
2203   if (SafepointSynchronize::do_call_back()) {
2204     // If we are safepointing, then block the caller which may not be
2205     // the same as the target thread (see above).
2206     SafepointSynchronize::block(curJT);
2207   }
2208 
2209   if (thread->is_deopt_suspend()) {
2210     thread->clear_deopt_suspend();
2211     RegisterMap map(thread, false);
2212     frame f = thread->last_frame();
2213     while ( f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2214       f = f.sender(&map);
2215     }
2216     if (f.id() == thread->must_deopt_id()) {
2217       thread->clear_must_deopt_id();
2218       f.deoptimize(thread);
2219     } else {
2220       fatal("missed deoptimization!");
2221     }
2222   }
2223 }
2224 
2225 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2226 // progress or when _suspend_flags is non-zero.
2227 // Current thread needs to self-suspend if there is a suspend request and/or
2228 // block if a safepoint is in progress.
2229 // Also check for pending async exception (not including unsafe access error).
2230 // Note only the native==>VM/Java barriers can call this function and when
2231 // thread state is _thread_in_native_trans.
2232 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2233   check_safepoint_and_suspend_for_native_trans(thread);
2234 
2235   if (thread->has_async_exception()) {
2236     // We are in _thread_in_native_trans state, don't handle unsafe
2237     // access error since that may block.
2238     thread->check_and_handle_async_exceptions(false);
2239   }
2240 }
2241 
2242 // We need to guarantee the Threads_lock here, since resumes are not
2243 // allowed during safepoint synchronization
2244 // Can only resume from an external suspension
2245 void JavaThread::java_resume() {
2246   assert_locked_or_safepoint(Threads_lock);
2247 
2248   // Sanity check: thread is gone, has started exiting or the thread
2249   // was not externally suspended.
2250   if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2251     return;
2252   }
2253 
2254   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2255 
2256   clear_external_suspend();
2257 
2258   if (is_ext_suspended()) {
2259     clear_ext_suspended();
2260     SR_lock()->notify_all();
2261   }
2262 }
2263 
2264 void JavaThread::create_stack_guard_pages() {
2265   if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return;
2266   address low_addr = stack_base() - stack_size();
2267   size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2268 
2269   int allocate = os::allocate_stack_guard_pages();
2270   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2271 
2272   if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) {
2273     warning("Attempt to allocate stack guard pages failed.");
2274     return;
2275   }
2276 
2277   if (os::guard_memory((char *) low_addr, len)) {
2278     _stack_guard_state = stack_guard_enabled;
2279   } else {
2280     warning("Attempt to protect stack guard pages failed.");
2281     if (os::uncommit_memory((char *) low_addr, len)) {
2282       warning("Attempt to deallocate stack guard pages failed.");
2283     }
2284   }
2285 }
2286 
2287 void JavaThread::remove_stack_guard_pages() {
2288   if (_stack_guard_state == stack_guard_unused) return;
2289   address low_addr = stack_base() - stack_size();
2290   size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2291 
2292   if (os::allocate_stack_guard_pages()) {
2293     if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2294       _stack_guard_state = stack_guard_unused;
2295     } else {
2296       warning("Attempt to deallocate stack guard pages failed.");
2297     }
2298   } else {
2299     if (_stack_guard_state == stack_guard_unused) return;
2300     if (os::unguard_memory((char *) low_addr, len)) {
2301       _stack_guard_state = stack_guard_unused;
2302     } else {
2303         warning("Attempt to unprotect stack guard pages failed.");
2304     }
2305   }
2306 }
2307 
2308 void JavaThread::enable_stack_yellow_zone() {
2309   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2310   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2311 
2312   // The base notation is from the stacks point of view, growing downward.
2313   // We need to adjust it to work correctly with guard_memory()
2314   address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2315 
2316   guarantee(base < stack_base(),"Error calculating stack yellow zone");
2317   guarantee(base < os::current_stack_pointer(),"Error calculating stack yellow zone");
2318 
2319   if (os::guard_memory((char *) base, stack_yellow_zone_size())) {
2320     _stack_guard_state = stack_guard_enabled;
2321   } else {
2322     warning("Attempt to guard stack yellow zone failed.");
2323   }
2324   enable_register_stack_guard();
2325 }
2326 
2327 void JavaThread::disable_stack_yellow_zone() {
2328   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2329   assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled");
2330 
2331   // Simply return if called for a thread that does not use guard pages.
2332   if (_stack_guard_state == stack_guard_unused) return;
2333 
2334   // The base notation is from the stacks point of view, growing downward.
2335   // We need to adjust it to work correctly with guard_memory()
2336   address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2337 
2338   if (os::unguard_memory((char *)base, stack_yellow_zone_size())) {
2339     _stack_guard_state = stack_guard_yellow_disabled;
2340   } else {
2341     warning("Attempt to unguard stack yellow zone failed.");
2342   }
2343   disable_register_stack_guard();
2344 }
2345 
2346 void JavaThread::enable_stack_red_zone() {
2347   // The base notation is from the stacks point of view, growing downward.
2348   // We need to adjust it to work correctly with guard_memory()
2349   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2350   address base = stack_red_zone_base() - stack_red_zone_size();
2351 
2352   guarantee(base < stack_base(),"Error calculating stack red zone");
2353   guarantee(base < os::current_stack_pointer(),"Error calculating stack red zone");
2354 
2355   if(!os::guard_memory((char *) base, stack_red_zone_size())) {
2356     warning("Attempt to guard stack red zone failed.");
2357   }
2358 }
2359 
2360 void JavaThread::disable_stack_red_zone() {
2361   // The base notation is from the stacks point of view, growing downward.
2362   // We need to adjust it to work correctly with guard_memory()
2363   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2364   address base = stack_red_zone_base() - stack_red_zone_size();
2365   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2366     warning("Attempt to unguard stack red zone failed.");
2367   }
2368 }
2369 
2370 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2371   // ignore is there is no stack
2372   if (!has_last_Java_frame()) return;
2373   // traverse the stack frames. Starts from top frame.
2374   for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2375     frame* fr = fst.current();
2376     f(fr, fst.register_map());
2377   }
2378 }
2379 
2380 
2381 #ifndef PRODUCT
2382 // Deoptimization
2383 // Function for testing deoptimization
2384 void JavaThread::deoptimize() {
2385   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2386   StackFrameStream fst(this, UseBiasedLocking);
2387   bool deopt = false;           // Dump stack only if a deopt actually happens.
2388   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2389   // Iterate over all frames in the thread and deoptimize
2390   for(; !fst.is_done(); fst.next()) {
2391     if(fst.current()->can_be_deoptimized()) {
2392 
2393       if (only_at) {
2394         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
2395         // consists of comma or carriage return separated numbers so
2396         // search for the current bci in that string.
2397         address pc = fst.current()->pc();
2398         nmethod* nm =  (nmethod*) fst.current()->cb();
2399         ScopeDesc* sd = nm->scope_desc_at( pc);
2400         char buffer[8];
2401         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2402         size_t len = strlen(buffer);
2403         const char * found = strstr(DeoptimizeOnlyAt, buffer);
2404         while (found != NULL) {
2405           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2406               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2407             // Check that the bci found is bracketed by terminators.
2408             break;
2409           }
2410           found = strstr(found + 1, buffer);
2411         }
2412         if (!found) {
2413           continue;
2414         }
2415       }
2416 
2417       if (DebugDeoptimization && !deopt) {
2418         deopt = true; // One-time only print before deopt
2419         tty->print_cr("[BEFORE Deoptimization]");
2420         trace_frames();
2421         trace_stack();
2422       }
2423       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2424     }
2425   }
2426 
2427   if (DebugDeoptimization && deopt) {
2428     tty->print_cr("[AFTER Deoptimization]");
2429     trace_frames();
2430   }
2431 }
2432 
2433 
2434 // Make zombies
2435 void JavaThread::make_zombies() {
2436   for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2437     if (fst.current()->can_be_deoptimized()) {
2438       // it is a Java nmethod
2439       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2440       nm->make_not_entrant();
2441     }
2442   }
2443 }
2444 #endif // PRODUCT
2445 
2446 
2447 void JavaThread::deoptimized_wrt_marked_nmethods() {
2448   if (!has_last_Java_frame()) return;
2449   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2450   StackFrameStream fst(this, UseBiasedLocking);
2451   for(; !fst.is_done(); fst.next()) {
2452     if (fst.current()->should_be_deoptimized()) {
2453       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2454     }
2455   }
2456 }
2457 
2458 
2459 // GC support
2460 static void frame_gc_epilogue(frame* f, const RegisterMap* map) { f->gc_epilogue(); }
2461 
2462 void JavaThread::gc_epilogue() {
2463   frames_do(frame_gc_epilogue);
2464 }
2465 
2466 
2467 static void frame_gc_prologue(frame* f, const RegisterMap* map) { f->gc_prologue(); }
2468 
2469 void JavaThread::gc_prologue() {
2470   frames_do(frame_gc_prologue);
2471 }
2472 
2473 // If the caller is a NamedThread, then remember, in the current scope,
2474 // the given JavaThread in its _processed_thread field.
2475 class RememberProcessedThread: public StackObj {
2476   NamedThread* _cur_thr;
2477 public:
2478   RememberProcessedThread(JavaThread* jthr) {
2479     Thread* thread = Thread::current();
2480     if (thread->is_Named_thread()) {
2481       _cur_thr = (NamedThread *)thread;
2482       _cur_thr->set_processed_thread(jthr);
2483     } else {
2484       _cur_thr = NULL;
2485     }
2486   }
2487 
2488   ~RememberProcessedThread() {
2489     if (_cur_thr) {
2490       _cur_thr->set_processed_thread(NULL);
2491     }
2492   }
2493 };
2494 
2495 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2496   // Verify that the deferred card marks have been flushed.
2497   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2498 
2499   // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2500   // since there may be more than one thread using each ThreadProfiler.
2501 
2502   // Traverse the GCHandles
2503   Thread::oops_do(f, cf);
2504 
2505   assert( (!has_last_Java_frame() && java_call_counter() == 0) ||
2506           (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2507 
2508   if (has_last_Java_frame()) {
2509     // Record JavaThread to GC thread
2510     RememberProcessedThread rpt(this);
2511 
2512     // Traverse the privileged stack
2513     if (_privileged_stack_top != NULL) {
2514       _privileged_stack_top->oops_do(f);
2515     }
2516 
2517     // traverse the registered growable array
2518     if (_array_for_gc != NULL) {
2519       for (int index = 0; index < _array_for_gc->length(); index++) {
2520         f->do_oop(_array_for_gc->adr_at(index));
2521       }
2522     }
2523 
2524     // Traverse the monitor chunks
2525     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2526       chunk->oops_do(f);
2527     }
2528 
2529     // Traverse the execution stack
2530     for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2531       fst.current()->oops_do(f, cf, fst.register_map());
2532     }
2533   }
2534 
2535   // callee_target is never live across a gc point so NULL it here should
2536   // it still contain a methdOop.
2537 
2538   set_callee_target(NULL);
2539 
2540   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2541   // If we have deferred set_locals there might be oops waiting to be
2542   // written
2543   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2544   if (list != NULL) {
2545     for (int i = 0; i < list->length(); i++) {
2546       list->at(i)->oops_do(f);
2547     }
2548   }
2549 
2550   // Traverse instance variables at the end since the GC may be moving things
2551   // around using this function
2552   f->do_oop((oop*) &_threadObj);
2553   f->do_oop((oop*) &_vm_result);
2554   f->do_oop((oop*) &_vm_result_2);
2555   f->do_oop((oop*) &_exception_oop);
2556   f->do_oop((oop*) &_pending_async_exception);
2557 
2558   if (jvmti_thread_state() != NULL) {
2559     jvmti_thread_state()->oops_do(f);
2560   }
2561 }
2562 
2563 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2564   Thread::nmethods_do(cf);  // (super method is a no-op)
2565 
2566   assert( (!has_last_Java_frame() && java_call_counter() == 0) ||
2567           (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2568 
2569   if (has_last_Java_frame()) {
2570     // Traverse the execution stack
2571     for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2572       fst.current()->nmethods_do(cf);
2573     }
2574   }
2575 }
2576 
2577 // Printing
2578 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2579   switch (_thread_state) {
2580   case _thread_uninitialized:     return "_thread_uninitialized";
2581   case _thread_new:               return "_thread_new";
2582   case _thread_new_trans:         return "_thread_new_trans";
2583   case _thread_in_native:         return "_thread_in_native";
2584   case _thread_in_native_trans:   return "_thread_in_native_trans";
2585   case _thread_in_vm:             return "_thread_in_vm";
2586   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
2587   case _thread_in_Java:           return "_thread_in_Java";
2588   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
2589   case _thread_blocked:           return "_thread_blocked";
2590   case _thread_blocked_trans:     return "_thread_blocked_trans";
2591   default:                        return "unknown thread state";
2592   }
2593 }
2594 
2595 #ifndef PRODUCT
2596 void JavaThread::print_thread_state_on(outputStream *st) const {
2597   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
2598 };
2599 void JavaThread::print_thread_state() const {
2600   print_thread_state_on(tty);
2601 };
2602 #endif // PRODUCT
2603 
2604 // Called by Threads::print() for VM_PrintThreads operation
2605 void JavaThread::print_on(outputStream *st) const {
2606   st->print("\"%s\" ", get_thread_name());
2607   oop thread_oop = threadObj();
2608   if (thread_oop != NULL && java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
2609   Thread::print_on(st);
2610   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2611   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2612   if (thread_oop != NULL && JDK_Version::is_gte_jdk15x_version()) {
2613     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2614   }
2615 #ifndef PRODUCT
2616   print_thread_state_on(st);
2617   _safepoint_state->print_on(st);
2618 #endif // PRODUCT
2619 }
2620 
2621 // Called by fatal error handler. The difference between this and
2622 // JavaThread::print() is that we can't grab lock or allocate memory.
2623 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2624   st->print("JavaThread \"%s\"",  get_thread_name_string(buf, buflen));
2625   oop thread_obj = threadObj();
2626   if (thread_obj != NULL) {
2627      if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2628   }
2629   st->print(" [");
2630   st->print("%s", _get_thread_state_name(_thread_state));
2631   if (osthread()) {
2632     st->print(", id=%d", osthread()->thread_id());
2633   }
2634   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2635             _stack_base - _stack_size, _stack_base);
2636   st->print("]");
2637   return;
2638 }
2639 
2640 // Verification
2641 
2642 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2643 
2644 void JavaThread::verify() {
2645   // Verify oops in the thread.
2646   oops_do(&VerifyOopClosure::verify_oop, NULL);
2647 
2648   // Verify the stack frames.
2649   frames_do(frame_verify);
2650 }
2651 
2652 // CR 6300358 (sub-CR 2137150)
2653 // Most callers of this method assume that it can't return NULL but a
2654 // thread may not have a name whilst it is in the process of attaching to
2655 // the VM - see CR 6412693, and there are places where a JavaThread can be
2656 // seen prior to having it's threadObj set (eg JNI attaching threads and
2657 // if vm exit occurs during initialization). These cases can all be accounted
2658 // for such that this method never returns NULL.
2659 const char* JavaThread::get_thread_name() const {
2660 #ifdef ASSERT
2661   // early safepoints can hit while current thread does not yet have TLS
2662   if (!SafepointSynchronize::is_at_safepoint()) {
2663     Thread *cur = Thread::current();
2664     if (!(cur->is_Java_thread() && cur == this)) {
2665       // Current JavaThreads are allowed to get their own name without
2666       // the Threads_lock.
2667       assert_locked_or_safepoint(Threads_lock);
2668     }
2669   }
2670 #endif // ASSERT
2671     return get_thread_name_string();
2672 }
2673 
2674 // Returns a non-NULL representation of this thread's name, or a suitable
2675 // descriptive string if there is no set name
2676 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2677   const char* name_str;
2678   oop thread_obj = threadObj();
2679   if (thread_obj != NULL) {
2680     typeArrayOop name = java_lang_Thread::name(thread_obj);
2681     if (name != NULL) {
2682       if (buf == NULL) {
2683         name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2684       }
2685       else {
2686         name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length(), buf, buflen);
2687       }
2688     }
2689     else if (is_attaching()) { // workaround for 6412693 - see 6404306
2690       name_str = "<no-name - thread is attaching>";
2691     }
2692     else {
2693       name_str = Thread::name();
2694     }
2695   }
2696   else {
2697     name_str = Thread::name();
2698   }
2699   assert(name_str != NULL, "unexpected NULL thread name");
2700   return name_str;
2701 }
2702 
2703 
2704 const char* JavaThread::get_threadgroup_name() const {
2705   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2706   oop thread_obj = threadObj();
2707   if (thread_obj != NULL) {
2708     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2709     if (thread_group != NULL) {
2710       typeArrayOop name = java_lang_ThreadGroup::name(thread_group);
2711       // ThreadGroup.name can be null
2712       if (name != NULL) {
2713         const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2714         return str;
2715       }
2716     }
2717   }
2718   return NULL;
2719 }
2720 
2721 const char* JavaThread::get_parent_name() const {
2722   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2723   oop thread_obj = threadObj();
2724   if (thread_obj != NULL) {
2725     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2726     if (thread_group != NULL) {
2727       oop parent = java_lang_ThreadGroup::parent(thread_group);
2728       if (parent != NULL) {
2729         typeArrayOop name = java_lang_ThreadGroup::name(parent);
2730         // ThreadGroup.name can be null
2731         if (name != NULL) {
2732           const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2733           return str;
2734         }
2735       }
2736     }
2737   }
2738   return NULL;
2739 }
2740 
2741 ThreadPriority JavaThread::java_priority() const {
2742   oop thr_oop = threadObj();
2743   if (thr_oop == NULL) return NormPriority; // Bootstrapping
2744   ThreadPriority priority = java_lang_Thread::priority(thr_oop);
2745   assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
2746   return priority;
2747 }
2748 
2749 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
2750 
2751   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
2752   // Link Java Thread object <-> C++ Thread
2753 
2754   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
2755   // and put it into a new Handle.  The Handle "thread_oop" can then
2756   // be used to pass the C++ thread object to other methods.
2757 
2758   // Set the Java level thread object (jthread) field of the
2759   // new thread (a JavaThread *) to C++ thread object using the
2760   // "thread_oop" handle.
2761 
2762   // Set the thread field (a JavaThread *) of the
2763   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
2764 
2765   Handle thread_oop(Thread::current(),
2766                     JNIHandles::resolve_non_null(jni_thread));
2767   assert(instanceKlass::cast(thread_oop->klass())->is_linked(),
2768     "must be initialized");
2769   set_threadObj(thread_oop());
2770   java_lang_Thread::set_thread(thread_oop(), this);
2771 
2772   if (prio == NoPriority) {
2773     prio = java_lang_Thread::priority(thread_oop());
2774     assert(prio != NoPriority, "A valid priority should be present");
2775   }
2776 
2777   // Push the Java priority down to the native thread; needs Threads_lock
2778   Thread::set_priority(this, prio);
2779 
2780   // Add the new thread to the Threads list and set it in motion.
2781   // We must have threads lock in order to call Threads::add.
2782   // It is crucial that we do not block before the thread is
2783   // added to the Threads list for if a GC happens, then the java_thread oop
2784   // will not be visited by GC.
2785   Threads::add(this);
2786 }
2787 
2788 oop JavaThread::current_park_blocker() {
2789   // Support for JSR-166 locks
2790   oop thread_oop = threadObj();
2791   if (thread_oop != NULL &&
2792       JDK_Version::current().supports_thread_park_blocker()) {
2793     return java_lang_Thread::park_blocker(thread_oop);
2794   }
2795   return NULL;
2796 }
2797 
2798 
2799 void JavaThread::print_stack_on(outputStream* st) {
2800   if (!has_last_Java_frame()) return;
2801   ResourceMark rm;
2802   HandleMark   hm;
2803 
2804   RegisterMap reg_map(this);
2805   vframe* start_vf = last_java_vframe(&reg_map);
2806   int count = 0;
2807   for (vframe* f = start_vf; f; f = f->sender() ) {
2808     if (f->is_java_frame()) {
2809       javaVFrame* jvf = javaVFrame::cast(f);
2810       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
2811 
2812       // Print out lock information
2813       if (JavaMonitorsInStackTrace) {
2814         jvf->print_lock_info_on(st, count);
2815       }
2816     } else {
2817       // Ignore non-Java frames
2818     }
2819 
2820     // Bail-out case for too deep stacks
2821     count++;
2822     if (MaxJavaStackTraceDepth == count) return;
2823   }
2824 }
2825 
2826 
2827 // JVMTI PopFrame support
2828 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
2829   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
2830   if (in_bytes(size_in_bytes) != 0) {
2831     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes));
2832     _popframe_preserved_args_size = in_bytes(size_in_bytes);
2833     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
2834   }
2835 }
2836 
2837 void* JavaThread::popframe_preserved_args() {
2838   return _popframe_preserved_args;
2839 }
2840 
2841 ByteSize JavaThread::popframe_preserved_args_size() {
2842   return in_ByteSize(_popframe_preserved_args_size);
2843 }
2844 
2845 WordSize JavaThread::popframe_preserved_args_size_in_words() {
2846   int sz = in_bytes(popframe_preserved_args_size());
2847   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
2848   return in_WordSize(sz / wordSize);
2849 }
2850 
2851 void JavaThread::popframe_free_preserved_args() {
2852   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
2853   FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
2854   _popframe_preserved_args = NULL;
2855   _popframe_preserved_args_size = 0;
2856 }
2857 
2858 #ifndef PRODUCT
2859 
2860 void JavaThread::trace_frames() {
2861   tty->print_cr("[Describe stack]");
2862   int frame_no = 1;
2863   for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2864     tty->print("  %d. ", frame_no++);
2865     fst.current()->print_value_on(tty,this);
2866     tty->cr();
2867   }
2868 }
2869 
2870 
2871 void JavaThread::trace_stack_from(vframe* start_vf) {
2872   ResourceMark rm;
2873   int vframe_no = 1;
2874   for (vframe* f = start_vf; f; f = f->sender() ) {
2875     if (f->is_java_frame()) {
2876       javaVFrame::cast(f)->print_activation(vframe_no++);
2877     } else {
2878       f->print();
2879     }
2880     if (vframe_no > StackPrintLimit) {
2881       tty->print_cr("...<more frames>...");
2882       return;
2883     }
2884   }
2885 }
2886 
2887 
2888 void JavaThread::trace_stack() {
2889   if (!has_last_Java_frame()) return;
2890   ResourceMark rm;
2891   HandleMark   hm;
2892   RegisterMap reg_map(this);
2893   trace_stack_from(last_java_vframe(&reg_map));
2894 }
2895 
2896 
2897 #endif // PRODUCT
2898 
2899 
2900 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
2901   assert(reg_map != NULL, "a map must be given");
2902   frame f = last_frame();
2903   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender() ) {
2904     if (vf->is_java_frame()) return javaVFrame::cast(vf);
2905   }
2906   return NULL;
2907 }
2908 
2909 
2910 klassOop JavaThread::security_get_caller_class(int depth) {
2911   vframeStream vfst(this);
2912   vfst.security_get_caller_frame(depth);
2913   if (!vfst.at_end()) {
2914     return vfst.method()->method_holder();
2915   }
2916   return NULL;
2917 }
2918 
2919 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
2920   assert(thread->is_Compiler_thread(), "must be compiler thread");
2921   CompileBroker::compiler_thread_loop();
2922 }
2923 
2924 // Create a CompilerThread
2925 CompilerThread::CompilerThread(CompileQueue* queue, CompilerCounters* counters)
2926 : JavaThread(&compiler_thread_entry) {
2927   _env   = NULL;
2928   _log   = NULL;
2929   _task  = NULL;
2930   _queue = queue;
2931   _counters = counters;
2932   _buffer_blob = NULL;
2933 
2934 #ifndef PRODUCT
2935   _ideal_graph_printer = NULL;
2936 #endif
2937 }
2938 
2939 
2940 // ======= Threads ========
2941 
2942 // The Threads class links together all active threads, and provides
2943 // operations over all threads.  It is protected by its own Mutex
2944 // lock, which is also used in other contexts to protect thread
2945 // operations from having the thread being operated on from exiting
2946 // and going away unexpectedly (e.g., safepoint synchronization)
2947 
2948 JavaThread* Threads::_thread_list = NULL;
2949 int         Threads::_number_of_threads = 0;
2950 int         Threads::_number_of_non_daemon_threads = 0;
2951 int         Threads::_return_code = 0;
2952 size_t      JavaThread::_stack_size_at_create = 0;
2953 
2954 // All JavaThreads
2955 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
2956 
2957 void os_stream();
2958 
2959 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
2960 void Threads::threads_do(ThreadClosure* tc) {
2961   assert_locked_or_safepoint(Threads_lock);
2962   // ALL_JAVA_THREADS iterates through all JavaThreads
2963   ALL_JAVA_THREADS(p) {
2964     tc->do_thread(p);
2965   }
2966   // Someday we could have a table or list of all non-JavaThreads.
2967   // For now, just manually iterate through them.
2968   tc->do_thread(VMThread::vm_thread());
2969   Universe::heap()->gc_threads_do(tc);
2970   WatcherThread *wt = WatcherThread::watcher_thread();
2971   // Strictly speaking, the following NULL check isn't sufficient to make sure
2972   // the data for WatcherThread is still valid upon being examined. However,
2973   // considering that WatchThread terminates when the VM is on the way to
2974   // exit at safepoint, the chance of the above is extremely small. The right
2975   // way to prevent termination of WatcherThread would be to acquire
2976   // Terminator_lock, but we can't do that without violating the lock rank
2977   // checking in some cases.
2978   if (wt != NULL)
2979     tc->do_thread(wt);
2980 
2981   // If CompilerThreads ever become non-JavaThreads, add them here
2982 }
2983 
2984 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
2985 
2986   extern void JDK_Version_init();
2987 
2988   // Check version
2989   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
2990 
2991   // Initialize the output stream module
2992   ostream_init();
2993 
2994   // Process java launcher properties.
2995   Arguments::process_sun_java_launcher_properties(args);
2996 
2997   // Initialize the os module before using TLS
2998   os::init();
2999 
3000   // Initialize system properties.
3001   Arguments::init_system_properties();
3002 
3003   // So that JDK version can be used as a discrimintor when parsing arguments
3004   JDK_Version_init();
3005 
3006   // Update/Initialize System properties after JDK version number is known
3007   Arguments::init_version_specific_system_properties();
3008 
3009   // Parse arguments
3010   jint parse_result = Arguments::parse(args);
3011   if (parse_result != JNI_OK) return parse_result;
3012 
3013   if (PauseAtStartup) {
3014     os::pause();
3015   }
3016 
3017   HS_DTRACE_PROBE(hotspot, vm__init__begin);
3018 
3019   // Record VM creation timing statistics
3020   TraceVmCreationTime create_vm_timer;
3021   create_vm_timer.start();
3022 
3023   // Timing (must come after argument parsing)
3024   TraceTime timer("Create VM", TraceStartupTime);
3025 
3026   // Initialize the os module after parsing the args
3027   jint os_init_2_result = os::init_2();
3028   if (os_init_2_result != JNI_OK) return os_init_2_result;
3029 
3030   // Initialize output stream logging
3031   ostream_init_log();
3032 
3033   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3034   // Must be before create_vm_init_agents()
3035   if (Arguments::init_libraries_at_startup()) {
3036     convert_vm_init_libraries_to_agents();
3037   }
3038 
3039   // Launch -agentlib/-agentpath and converted -Xrun agents
3040   if (Arguments::init_agents_at_startup()) {
3041     create_vm_init_agents();
3042   }
3043 
3044   // Initialize Threads state
3045   _thread_list = NULL;
3046   _number_of_threads = 0;
3047   _number_of_non_daemon_threads = 0;
3048 
3049   // Initialize TLS
3050   ThreadLocalStorage::init();
3051 
3052   // Initialize global data structures and create system classes in heap
3053   vm_init_globals();
3054 
3055   // Attach the main thread to this os thread
3056   JavaThread* main_thread = new JavaThread();
3057   main_thread->set_thread_state(_thread_in_vm);
3058   // must do this before set_active_handles and initialize_thread_local_storage
3059   // Note: on solaris initialize_thread_local_storage() will (indirectly)
3060   // change the stack size recorded here to one based on the java thread
3061   // stacksize. This adjusted size is what is used to figure the placement
3062   // of the guard pages.
3063   main_thread->record_stack_base_and_size();
3064   main_thread->initialize_thread_local_storage();
3065 
3066   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3067 
3068   if (!main_thread->set_as_starting_thread()) {
3069     vm_shutdown_during_initialization(
3070       "Failed necessary internal allocation. Out of swap space");
3071     delete main_thread;
3072     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3073     return JNI_ENOMEM;
3074   }
3075 
3076   // Enable guard page *after* os::create_main_thread(), otherwise it would
3077   // crash Linux VM, see notes in os_linux.cpp.
3078   main_thread->create_stack_guard_pages();
3079 
3080   // Initialize Java-Level synchronization subsystem
3081   ObjectMonitor::Initialize() ;
3082 
3083   // Initialize global modules
3084   jint status = init_globals();
3085   if (status != JNI_OK) {
3086     delete main_thread;
3087     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3088     return status;
3089   }
3090 
3091   // Should be done after the heap is fully created
3092   main_thread->cache_global_variables();
3093 
3094   HandleMark hm;
3095 
3096   { MutexLocker mu(Threads_lock);
3097     Threads::add(main_thread);
3098   }
3099 
3100   // Any JVMTI raw monitors entered in onload will transition into
3101   // real raw monitor. VM is setup enough here for raw monitor enter.
3102   JvmtiExport::transition_pending_onload_raw_monitors();
3103 
3104   if (VerifyBeforeGC &&
3105       Universe::heap()->total_collections() >= VerifyGCStartAt) {
3106     Universe::heap()->prepare_for_verify();
3107     Universe::verify();   // make sure we're starting with a clean slate
3108   }
3109 
3110   // Create the VMThread
3111   { TraceTime timer("Start VMThread", TraceStartupTime);
3112     VMThread::create();
3113     Thread* vmthread = VMThread::vm_thread();
3114 
3115     if (!os::create_thread(vmthread, os::vm_thread))
3116       vm_exit_during_initialization("Cannot create VM thread. Out of system resources.");
3117 
3118     // Wait for the VM thread to become ready, and VMThread::run to initialize
3119     // Monitors can have spurious returns, must always check another state flag
3120     {
3121       MutexLocker ml(Notify_lock);
3122       os::start_thread(vmthread);
3123       while (vmthread->active_handles() == NULL) {
3124         Notify_lock->wait();
3125       }
3126     }
3127   }
3128 
3129   assert (Universe::is_fully_initialized(), "not initialized");
3130   EXCEPTION_MARK;
3131 
3132   // At this point, the Universe is initialized, but we have not executed
3133   // any byte code.  Now is a good time (the only time) to dump out the
3134   // internal state of the JVM for sharing.
3135 
3136   if (DumpSharedSpaces) {
3137     Universe::heap()->preload_and_dump(CHECK_0);
3138     ShouldNotReachHere();
3139   }
3140 
3141   // Always call even when there are not JVMTI environments yet, since environments
3142   // may be attached late and JVMTI must track phases of VM execution
3143   JvmtiExport::enter_start_phase();
3144 
3145   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3146   JvmtiExport::post_vm_start();
3147 
3148   {
3149     TraceTime timer("Initialize java.lang classes", TraceStartupTime);
3150 
3151     if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3152       create_vm_init_libraries();
3153     }
3154 
3155     if (InitializeJavaLangString) {
3156       initialize_class(vmSymbols::java_lang_String(), CHECK_0);
3157     } else {
3158       warning("java.lang.String not initialized");
3159     }
3160 
3161     if (AggressiveOpts) {
3162       {
3163         // Forcibly initialize java/util/HashMap and mutate the private
3164         // static final "frontCacheEnabled" field before we start creating instances
3165 #ifdef ASSERT
3166         klassOop tmp_k = SystemDictionary::find(vmSymbols::java_util_HashMap(), Handle(), Handle(), CHECK_0);
3167         assert(tmp_k == NULL, "java/util/HashMap should not be loaded yet");
3168 #endif
3169         klassOop k_o = SystemDictionary::resolve_or_null(vmSymbols::java_util_HashMap(), Handle(), Handle(), CHECK_0);
3170         KlassHandle k = KlassHandle(THREAD, k_o);
3171         guarantee(k.not_null(), "Must find java/util/HashMap");
3172         instanceKlassHandle ik = instanceKlassHandle(THREAD, k());
3173         ik->initialize(CHECK_0);
3174         fieldDescriptor fd;
3175         // Possible we might not find this field; if so, don't break
3176         if (ik->find_local_field(vmSymbols::frontCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) {
3177           k()->bool_field_put(fd.offset(), true);
3178         }
3179       }
3180 
3181       if (UseStringCache) {
3182         // Forcibly initialize java/lang/StringValue and mutate the private
3183         // static final "stringCacheEnabled" field before we start creating instances
3184         klassOop k_o = SystemDictionary::resolve_or_null(vmSymbols::java_lang_StringValue(), Handle(), Handle(), CHECK_0);
3185         // Possible that StringValue isn't present: if so, silently don't break
3186         if (k_o != NULL) {
3187           KlassHandle k = KlassHandle(THREAD, k_o);
3188           instanceKlassHandle ik = instanceKlassHandle(THREAD, k());
3189           ik->initialize(CHECK_0);
3190           fieldDescriptor fd;
3191           // Possible we might not find this field: if so, silently don't break
3192           if (ik->find_local_field(vmSymbols::stringCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) {
3193             k()->bool_field_put(fd.offset(), true);
3194           }
3195         }
3196       }
3197     }
3198 
3199     // Initialize java_lang.System (needed before creating the thread)
3200     if (InitializeJavaLangSystem) {
3201       initialize_class(vmSymbols::java_lang_System(), CHECK_0);
3202       initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK_0);
3203       Handle thread_group = create_initial_thread_group(CHECK_0);
3204       Universe::set_main_thread_group(thread_group());
3205       initialize_class(vmSymbols::java_lang_Thread(), CHECK_0);
3206       oop thread_object = create_initial_thread(thread_group, main_thread, CHECK_0);
3207       main_thread->set_threadObj(thread_object);
3208       // Set thread status to running since main thread has
3209       // been started and running.
3210       java_lang_Thread::set_thread_status(thread_object,
3211                                           java_lang_Thread::RUNNABLE);
3212 
3213       // The VM preresolve methods to these classes. Make sure that get initialized
3214       initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK_0);
3215       initialize_class(vmSymbols::java_lang_ref_Finalizer(),  CHECK_0);
3216       // The VM creates & returns objects of this class. Make sure it's initialized.
3217       initialize_class(vmSymbols::java_lang_Class(), CHECK_0);
3218       call_initializeSystemClass(CHECK_0);
3219     } else {
3220       warning("java.lang.System not initialized");
3221     }
3222 
3223     // an instance of OutOfMemory exception has been allocated earlier
3224     if (InitializeJavaLangExceptionsErrors) {
3225       initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK_0);
3226       initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK_0);
3227       initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK_0);
3228       initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK_0);
3229       initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK_0);
3230       initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK_0);
3231       initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK_0);
3232     } else {
3233       warning("java.lang.OutOfMemoryError has not been initialized");
3234       warning("java.lang.NullPointerException has not been initialized");
3235       warning("java.lang.ClassCastException has not been initialized");
3236       warning("java.lang.ArrayStoreException has not been initialized");
3237       warning("java.lang.ArithmeticException has not been initialized");
3238       warning("java.lang.StackOverflowError has not been initialized");
3239     }
3240     }
3241 
3242   // See        : bugid 4211085.
3243   // Background : the static initializer of java.lang.Compiler tries to read
3244   //              property"java.compiler" and read & write property "java.vm.info".
3245   //              When a security manager is installed through the command line
3246   //              option "-Djava.security.manager", the above properties are not
3247   //              readable and the static initializer for java.lang.Compiler fails
3248   //              resulting in a NoClassDefFoundError.  This can happen in any
3249   //              user code which calls methods in java.lang.Compiler.
3250   // Hack :       the hack is to pre-load and initialize this class, so that only
3251   //              system domains are on the stack when the properties are read.
3252   //              Currently even the AWT code has calls to methods in java.lang.Compiler.
3253   //              On the classic VM, java.lang.Compiler is loaded very early to load the JIT.
3254   // Future Fix : the best fix is to grant everyone permissions to read "java.compiler" and
3255   //              read and write"java.vm.info" in the default policy file. See bugid 4211383
3256   //              Once that is done, we should remove this hack.
3257   initialize_class(vmSymbols::java_lang_Compiler(), CHECK_0);
3258 
3259   // More hackery - the static initializer of java.lang.Compiler adds the string "nojit" to
3260   // the java.vm.info property if no jit gets loaded through java.lang.Compiler (the hotspot
3261   // compiler does not get loaded through java.lang.Compiler).  "java -version" with the
3262   // hotspot vm says "nojit" all the time which is confusing.  So, we reset it here.
3263   // This should also be taken out as soon as 4211383 gets fixed.
3264   reset_vm_info_property(CHECK_0);
3265 
3266   quicken_jni_functions();
3267 
3268   // Set flag that basic initialization has completed. Used by exceptions and various
3269   // debug stuff, that does not work until all basic classes have been initialized.
3270   set_init_completed();
3271 
3272   HS_DTRACE_PROBE(hotspot, vm__init__end);
3273 
3274   // record VM initialization completion time
3275   Management::record_vm_init_completed();
3276 
3277   // Compute system loader. Note that this has to occur after set_init_completed, since
3278   // valid exceptions may be thrown in the process.
3279   // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
3280   // set_init_completed has just been called, causing exceptions not to be shortcut
3281   // anymore. We call vm_exit_during_initialization directly instead.
3282   SystemDictionary::compute_java_system_loader(THREAD);
3283   if (HAS_PENDING_EXCEPTION) {
3284     vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
3285   }
3286 
3287 #ifdef KERNEL
3288   if (JDK_Version::is_gte_jdk17x_version()) {
3289     set_jkernel_boot_classloader_hook(THREAD);
3290   }
3291 #endif // KERNEL
3292 
3293 #ifndef SERIALGC
3294   // Support for ConcurrentMarkSweep. This should be cleaned up
3295   // and better encapsulated. The ugly nested if test would go away
3296   // once things are properly refactored. XXX YSR
3297   if (UseConcMarkSweepGC || UseG1GC) {
3298     if (UseConcMarkSweepGC) {
3299       ConcurrentMarkSweepThread::makeSurrogateLockerThread(THREAD);
3300     } else {
3301       ConcurrentMarkThread::makeSurrogateLockerThread(THREAD);
3302     }
3303     if (HAS_PENDING_EXCEPTION) {
3304       vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
3305     }
3306   }
3307 #endif // SERIALGC
3308 
3309   // Always call even when there are not JVMTI environments yet, since environments
3310   // may be attached late and JVMTI must track phases of VM execution
3311   JvmtiExport::enter_live_phase();
3312 
3313   // Signal Dispatcher needs to be started before VMInit event is posted
3314   os::signal_init();
3315 
3316   // Start Attach Listener if +StartAttachListener or it can't be started lazily
3317   if (!DisableAttachMechanism) {
3318     if (StartAttachListener || AttachListener::init_at_startup()) {
3319       AttachListener::init();
3320     }
3321   }
3322 
3323   // Launch -Xrun agents
3324   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3325   // back-end can launch with -Xdebug -Xrunjdwp.
3326   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3327     create_vm_init_libraries();
3328   }
3329 
3330   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3331   JvmtiExport::post_vm_initialized();
3332 
3333   Chunk::start_chunk_pool_cleaner_task();
3334 
3335   // initialize compiler(s)
3336   CompileBroker::compilation_init();
3337 
3338   Management::initialize(THREAD);
3339   if (HAS_PENDING_EXCEPTION) {
3340     // management agent fails to start possibly due to
3341     // configuration problem and is responsible for printing
3342     // stack trace if appropriate. Simply exit VM.
3343     vm_exit(1);
3344   }
3345 
3346   if (Arguments::has_profile())       FlatProfiler::engage(main_thread, true);
3347   if (Arguments::has_alloc_profile()) AllocationProfiler::engage();
3348   if (MemProfiling)                   MemProfiler::engage();
3349   StatSampler::engage();
3350   if (CheckJNICalls)                  JniPeriodicChecker::engage();
3351 
3352   BiasedLocking::init();
3353 
3354   if (JDK_Version::current().post_vm_init_hook_enabled()) {
3355     call_postVMInitHook(THREAD);
3356     // The Java side of PostVMInitHook.run must deal with all
3357     // exceptions and provide means of diagnosis.
3358     if (HAS_PENDING_EXCEPTION) {
3359       CLEAR_PENDING_EXCEPTION;
3360     }
3361   }
3362 
3363   // Start up the WatcherThread if there are any periodic tasks
3364   // NOTE:  All PeriodicTasks should be registered by now. If they
3365   //   aren't, late joiners might appear to start slowly (we might
3366   //   take a while to process their first tick).
3367   if (PeriodicTask::num_tasks() > 0) {
3368     WatcherThread::start();
3369   }
3370 
3371   // Give os specific code one last chance to start
3372   os::init_3();
3373 
3374   create_vm_timer.end();
3375   return JNI_OK;
3376 }
3377 
3378 // type for the Agent_OnLoad and JVM_OnLoad entry points
3379 extern "C" {
3380   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3381 }
3382 // Find a command line agent library and return its entry point for
3383 //         -agentlib:  -agentpath:   -Xrun
3384 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3385 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, const char *on_load_symbols[], size_t num_symbol_entries) {
3386   OnLoadEntry_t on_load_entry = NULL;
3387   void *library = agent->os_lib();  // check if we have looked it up before
3388 
3389   if (library == NULL) {
3390     char buffer[JVM_MAXPATHLEN];
3391     char ebuf[1024];
3392     const char *name = agent->name();
3393     const char *msg = "Could not find agent library ";
3394 
3395     if (agent->is_absolute_path()) {
3396       library = os::dll_load(name, ebuf, sizeof ebuf);
3397       if (library == NULL) {
3398         const char *sub_msg = " in absolute path, with error: ";
3399         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3400         char *buf = NEW_C_HEAP_ARRAY(char, len);
3401         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3402         // If we can't find the agent, exit.
3403         vm_exit_during_initialization(buf, NULL);
3404         FREE_C_HEAP_ARRAY(char, buf);
3405       }
3406     } else {
3407       // Try to load the agent from the standard dll directory
3408       os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(), name);
3409       library = os::dll_load(buffer, ebuf, sizeof ebuf);
3410 #ifdef KERNEL
3411       // Download instrument dll
3412       if (library == NULL && strcmp(name, "instrument") == 0) {
3413         char *props = Arguments::get_kernel_properties();
3414         char *home  = Arguments::get_java_home();
3415         const char *fmt   = "%s/bin/java %s -Dkernel.background.download=false"
3416                       " sun.jkernel.DownloadManager -download client_jvm";
3417         size_t length = strlen(props) + strlen(home) + strlen(fmt) + 1;
3418         char *cmd = NEW_C_HEAP_ARRAY(char, length);
3419         jio_snprintf(cmd, length, fmt, home, props);
3420         int status = os::fork_and_exec(cmd);
3421         FreeHeap(props);
3422         if (status == -1) {
3423           warning(cmd);
3424           vm_exit_during_initialization("fork_and_exec failed: %s",
3425                                          strerror(errno));
3426         }
3427         FREE_C_HEAP_ARRAY(char, cmd);
3428         // when this comes back the instrument.dll should be where it belongs.
3429         library = os::dll_load(buffer, ebuf, sizeof ebuf);
3430       }
3431 #endif // KERNEL
3432       if (library == NULL) { // Try the local directory
3433         char ns[1] = {0};
3434         os::dll_build_name(buffer, sizeof(buffer), ns, name);
3435         library = os::dll_load(buffer, ebuf, sizeof ebuf);
3436         if (library == NULL) {
3437           const char *sub_msg = " on the library path, with error: ";
3438           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3439           char *buf = NEW_C_HEAP_ARRAY(char, len);
3440           jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3441           // If we can't find the agent, exit.
3442           vm_exit_during_initialization(buf, NULL);
3443           FREE_C_HEAP_ARRAY(char, buf);
3444         }
3445       }
3446     }
3447     agent->set_os_lib(library);
3448   }
3449 
3450   // Find the OnLoad function.
3451   for (size_t symbol_index = 0; symbol_index < num_symbol_entries; symbol_index++) {
3452     on_load_entry = CAST_TO_FN_PTR(OnLoadEntry_t, os::dll_lookup(library, on_load_symbols[symbol_index]));
3453     if (on_load_entry != NULL) break;
3454   }
3455   return on_load_entry;
3456 }
3457 
3458 // Find the JVM_OnLoad entry point
3459 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3460   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3461   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3462 }
3463 
3464 // Find the Agent_OnLoad entry point
3465 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3466   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3467   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3468 }
3469 
3470 // For backwards compatibility with -Xrun
3471 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3472 // treated like -agentpath:
3473 // Must be called before agent libraries are created
3474 void Threads::convert_vm_init_libraries_to_agents() {
3475   AgentLibrary* agent;
3476   AgentLibrary* next;
3477 
3478   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3479     next = agent->next();  // cache the next agent now as this agent may get moved off this list
3480     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3481 
3482     // If there is an JVM_OnLoad function it will get called later,
3483     // otherwise see if there is an Agent_OnLoad
3484     if (on_load_entry == NULL) {
3485       on_load_entry = lookup_agent_on_load(agent);
3486       if (on_load_entry != NULL) {
3487         // switch it to the agent list -- so that Agent_OnLoad will be called,
3488         // JVM_OnLoad won't be attempted and Agent_OnUnload will
3489         Arguments::convert_library_to_agent(agent);
3490       } else {
3491         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3492       }
3493     }
3494   }
3495 }
3496 
3497 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
3498 // Invokes Agent_OnLoad
3499 // Called very early -- before JavaThreads exist
3500 void Threads::create_vm_init_agents() {
3501   extern struct JavaVM_ main_vm;
3502   AgentLibrary* agent;
3503 
3504   JvmtiExport::enter_onload_phase();
3505   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3506     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
3507 
3508     if (on_load_entry != NULL) {
3509       // Invoke the Agent_OnLoad function
3510       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3511       if (err != JNI_OK) {
3512         vm_exit_during_initialization("agent library failed to init", agent->name());
3513       }
3514     } else {
3515       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3516     }
3517   }
3518   JvmtiExport::enter_primordial_phase();
3519 }
3520 
3521 extern "C" {
3522   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3523 }
3524 
3525 void Threads::shutdown_vm_agents() {
3526   // Send any Agent_OnUnload notifications
3527   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3528   extern struct JavaVM_ main_vm;
3529   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3530 
3531     // Find the Agent_OnUnload function.
3532     for (uint symbol_index = 0; symbol_index < ARRAY_SIZE(on_unload_symbols); symbol_index++) {
3533       Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3534                os::dll_lookup(agent->os_lib(), on_unload_symbols[symbol_index]));
3535 
3536       // Invoke the Agent_OnUnload function
3537       if (unload_entry != NULL) {
3538         JavaThread* thread = JavaThread::current();
3539         ThreadToNativeFromVM ttn(thread);
3540         HandleMark hm(thread);
3541         (*unload_entry)(&main_vm);
3542         break;
3543       }
3544     }
3545   }
3546 }
3547 
3548 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
3549 // Invokes JVM_OnLoad
3550 void Threads::create_vm_init_libraries() {
3551   extern struct JavaVM_ main_vm;
3552   AgentLibrary* agent;
3553 
3554   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
3555     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3556 
3557     if (on_load_entry != NULL) {
3558       // Invoke the JVM_OnLoad function
3559       JavaThread* thread = JavaThread::current();
3560       ThreadToNativeFromVM ttn(thread);
3561       HandleMark hm(thread);
3562       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3563       if (err != JNI_OK) {
3564         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
3565       }
3566     } else {
3567       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
3568     }
3569   }
3570 }
3571 
3572 // Last thread running calls java.lang.Shutdown.shutdown()
3573 void JavaThread::invoke_shutdown_hooks() {
3574   HandleMark hm(this);
3575 
3576   // We could get here with a pending exception, if so clear it now.
3577   if (this->has_pending_exception()) {
3578     this->clear_pending_exception();
3579   }
3580 
3581   EXCEPTION_MARK;
3582   klassOop k =
3583     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
3584                                       THREAD);
3585   if (k != NULL) {
3586     // SystemDictionary::resolve_or_null will return null if there was
3587     // an exception.  If we cannot load the Shutdown class, just don't
3588     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
3589     // and finalizers (if runFinalizersOnExit is set) won't be run.
3590     // Note that if a shutdown hook was registered or runFinalizersOnExit
3591     // was called, the Shutdown class would have already been loaded
3592     // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
3593     instanceKlassHandle shutdown_klass (THREAD, k);
3594     JavaValue result(T_VOID);
3595     JavaCalls::call_static(&result,
3596                            shutdown_klass,
3597                            vmSymbols::shutdown_method_name(),
3598                            vmSymbols::void_method_signature(),
3599                            THREAD);
3600   }
3601   CLEAR_PENDING_EXCEPTION;
3602 }
3603 
3604 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
3605 // the program falls off the end of main(). Another VM exit path is through
3606 // vm_exit() when the program calls System.exit() to return a value or when
3607 // there is a serious error in VM. The two shutdown paths are not exactly
3608 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
3609 // and VM_Exit op at VM level.
3610 //
3611 // Shutdown sequence:
3612 //   + Wait until we are the last non-daemon thread to execute
3613 //     <-- every thing is still working at this moment -->
3614 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
3615 //        shutdown hooks, run finalizers if finalization-on-exit
3616 //   + Call before_exit(), prepare for VM exit
3617 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
3618 //        currently the only user of this mechanism is File.deleteOnExit())
3619 //      > stop flat profiler, StatSampler, watcher thread, CMS threads,
3620 //        post thread end and vm death events to JVMTI,
3621 //        stop signal thread
3622 //   + Call JavaThread::exit(), it will:
3623 //      > release JNI handle blocks, remove stack guard pages
3624 //      > remove this thread from Threads list
3625 //     <-- no more Java code from this thread after this point -->
3626 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
3627 //     the compiler threads at safepoint
3628 //     <-- do not use anything that could get blocked by Safepoint -->
3629 //   + Disable tracing at JNI/JVM barriers
3630 //   + Set _vm_exited flag for threads that are still running native code
3631 //   + Delete this thread
3632 //   + Call exit_globals()
3633 //      > deletes tty
3634 //      > deletes PerfMemory resources
3635 //   + Return to caller
3636 
3637 bool Threads::destroy_vm() {
3638   JavaThread* thread = JavaThread::current();
3639 
3640   // Wait until we are the last non-daemon thread to execute
3641   { MutexLocker nu(Threads_lock);
3642     while (Threads::number_of_non_daemon_threads() > 1 )
3643       // This wait should make safepoint checks, wait without a timeout,
3644       // and wait as a suspend-equivalent condition.
3645       //
3646       // Note: If the FlatProfiler is running and this thread is waiting
3647       // for another non-daemon thread to finish, then the FlatProfiler
3648       // is waiting for the external suspend request on this thread to
3649       // complete. wait_for_ext_suspend_completion() will eventually
3650       // timeout, but that takes time. Making this wait a suspend-
3651       // equivalent condition solves that timeout problem.
3652       //
3653       Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
3654                          Mutex::_as_suspend_equivalent_flag);
3655   }
3656 
3657   // Hang forever on exit if we are reporting an error.
3658   if (ShowMessageBoxOnError && is_error_reported()) {
3659     os::infinite_sleep();
3660   }
3661 
3662   if (JDK_Version::is_jdk12x_version()) {
3663     // We are the last thread running, so check if finalizers should be run.
3664     // For 1.3 or later this is done in thread->invoke_shutdown_hooks()
3665     HandleMark rm(thread);
3666     Universe::run_finalizers_on_exit();
3667   } else {
3668     // run Java level shutdown hooks
3669     thread->invoke_shutdown_hooks();
3670   }
3671 
3672   before_exit(thread);
3673 
3674   thread->exit(true);
3675 
3676   // Stop VM thread.
3677   {
3678     // 4945125 The vm thread comes to a safepoint during exit.
3679     // GC vm_operations can get caught at the safepoint, and the
3680     // heap is unparseable if they are caught. Grab the Heap_lock
3681     // to prevent this. The GC vm_operations will not be able to
3682     // queue until after the vm thread is dead.
3683     MutexLocker ml(Heap_lock);
3684 
3685     VMThread::wait_for_vm_thread_exit();
3686     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
3687     VMThread::destroy();
3688   }
3689 
3690   // clean up ideal graph printers
3691 #if defined(COMPILER2) && !defined(PRODUCT)
3692   IdealGraphPrinter::clean_up();
3693 #endif
3694 
3695   // Now, all Java threads are gone except daemon threads. Daemon threads
3696   // running Java code or in VM are stopped by the Safepoint. However,
3697   // daemon threads executing native code are still running.  But they
3698   // will be stopped at native=>Java/VM barriers. Note that we can't
3699   // simply kill or suspend them, as it is inherently deadlock-prone.
3700 
3701 #ifndef PRODUCT
3702   // disable function tracing at JNI/JVM barriers
3703   TraceJNICalls = false;
3704   TraceJVMCalls = false;
3705   TraceRuntimeCalls = false;
3706 #endif
3707 
3708   VM_Exit::set_vm_exited();
3709 
3710   notify_vm_shutdown();
3711 
3712   delete thread;
3713 
3714   // exit_globals() will delete tty
3715   exit_globals();
3716 
3717   return true;
3718 }
3719 
3720 
3721 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
3722   if (version == JNI_VERSION_1_1) return JNI_TRUE;
3723   return is_supported_jni_version(version);
3724 }
3725 
3726 
3727 jboolean Threads::is_supported_jni_version(jint version) {
3728   if (version == JNI_VERSION_1_2) return JNI_TRUE;
3729   if (version == JNI_VERSION_1_4) return JNI_TRUE;
3730   if (version == JNI_VERSION_1_6) return JNI_TRUE;
3731   return JNI_FALSE;
3732 }
3733 
3734 
3735 void Threads::add(JavaThread* p, bool force_daemon) {
3736   // The threads lock must be owned at this point
3737   assert_locked_or_safepoint(Threads_lock);
3738 
3739   // See the comment for this method in thread.hpp for its purpose and
3740   // why it is called here.
3741   p->initialize_queues();
3742   p->set_next(_thread_list);
3743   _thread_list = p;
3744   _number_of_threads++;
3745   oop threadObj = p->threadObj();
3746   bool daemon = true;
3747   // Bootstrapping problem: threadObj can be null for initial
3748   // JavaThread (or for threads attached via JNI)
3749   if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
3750     _number_of_non_daemon_threads++;
3751     daemon = false;
3752   }
3753 
3754   ThreadService::add_thread(p, daemon);
3755 
3756   // Possible GC point.
3757   Events::log("Thread added: " INTPTR_FORMAT, p);
3758 }
3759 
3760 void Threads::remove(JavaThread* p) {
3761   // Extra scope needed for Thread_lock, so we can check
3762   // that we do not remove thread without safepoint code notice
3763   { MutexLocker ml(Threads_lock);
3764 
3765     assert(includes(p), "p must be present");
3766 
3767     JavaThread* current = _thread_list;
3768     JavaThread* prev    = NULL;
3769 
3770     while (current != p) {
3771       prev    = current;
3772       current = current->next();
3773     }
3774 
3775     if (prev) {
3776       prev->set_next(current->next());
3777     } else {
3778       _thread_list = p->next();
3779     }
3780     _number_of_threads--;
3781     oop threadObj = p->threadObj();
3782     bool daemon = true;
3783     if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
3784       _number_of_non_daemon_threads--;
3785       daemon = false;
3786 
3787       // Only one thread left, do a notify on the Threads_lock so a thread waiting
3788       // on destroy_vm will wake up.
3789       if (number_of_non_daemon_threads() == 1)
3790         Threads_lock->notify_all();
3791     }
3792     ThreadService::remove_thread(p, daemon);
3793 
3794     // Make sure that safepoint code disregard this thread. This is needed since
3795     // the thread might mess around with locks after this point. This can cause it
3796     // to do callbacks into the safepoint code. However, the safepoint code is not aware
3797     // of this thread since it is removed from the queue.
3798     p->set_terminated_value();
3799   } // unlock Threads_lock
3800 
3801   // Since Events::log uses a lock, we grab it outside the Threads_lock
3802   Events::log("Thread exited: " INTPTR_FORMAT, p);
3803 }
3804 
3805 // Threads_lock must be held when this is called (or must be called during a safepoint)
3806 bool Threads::includes(JavaThread* p) {
3807   assert(Threads_lock->is_locked(), "sanity check");
3808   ALL_JAVA_THREADS(q) {
3809     if (q == p ) {
3810       return true;
3811     }
3812   }
3813   return false;
3814 }
3815 
3816 // Operations on the Threads list for GC.  These are not explicitly locked,
3817 // but the garbage collector must provide a safe context for them to run.
3818 // In particular, these things should never be called when the Threads_lock
3819 // is held by some other thread. (Note: the Safepoint abstraction also
3820 // uses the Threads_lock to gurantee this property. It also makes sure that
3821 // all threads gets blocked when exiting or starting).
3822 
3823 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3824   ALL_JAVA_THREADS(p) {
3825     p->oops_do(f, cf);
3826   }
3827   VMThread::vm_thread()->oops_do(f, cf);
3828 }
3829 
3830 void Threads::possibly_parallel_oops_do(OopClosure* f, CodeBlobClosure* cf) {
3831   // Introduce a mechanism allowing parallel threads to claim threads as
3832   // root groups.  Overhead should be small enough to use all the time,
3833   // even in sequential code.
3834   SharedHeap* sh = SharedHeap::heap();
3835   bool is_par = (sh->n_par_threads() > 0);
3836   int cp = SharedHeap::heap()->strong_roots_parity();
3837   ALL_JAVA_THREADS(p) {
3838     if (p->claim_oops_do(is_par, cp)) {
3839       p->oops_do(f, cf);
3840     }
3841   }
3842   VMThread* vmt = VMThread::vm_thread();
3843   if (vmt->claim_oops_do(is_par, cp))
3844     vmt->oops_do(f, cf);
3845 }
3846 
3847 #ifndef SERIALGC
3848 // Used by ParallelScavenge
3849 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
3850   ALL_JAVA_THREADS(p) {
3851     q->enqueue(new ThreadRootsTask(p));
3852   }
3853   q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
3854 }
3855 
3856 // Used by Parallel Old
3857 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
3858   ALL_JAVA_THREADS(p) {
3859     q->enqueue(new ThreadRootsMarkingTask(p));
3860   }
3861   q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
3862 }
3863 #endif // SERIALGC
3864 
3865 void Threads::nmethods_do(CodeBlobClosure* cf) {
3866   ALL_JAVA_THREADS(p) {
3867     p->nmethods_do(cf);
3868   }
3869   VMThread::vm_thread()->nmethods_do(cf);
3870 }
3871 
3872 void Threads::gc_epilogue() {
3873   ALL_JAVA_THREADS(p) {
3874     p->gc_epilogue();
3875   }
3876 }
3877 
3878 void Threads::gc_prologue() {
3879   ALL_JAVA_THREADS(p) {
3880     p->gc_prologue();
3881   }
3882 }
3883 
3884 void Threads::deoptimized_wrt_marked_nmethods() {
3885   ALL_JAVA_THREADS(p) {
3886     p->deoptimized_wrt_marked_nmethods();
3887   }
3888 }
3889 
3890 
3891 // Get count Java threads that are waiting to enter the specified monitor.
3892 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
3893   address monitor, bool doLock) {
3894   assert(doLock || SafepointSynchronize::is_at_safepoint(),
3895     "must grab Threads_lock or be at safepoint");
3896   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
3897 
3898   int i = 0;
3899   {
3900     MutexLockerEx ml(doLock ? Threads_lock : NULL);
3901     ALL_JAVA_THREADS(p) {
3902       if (p->is_Compiler_thread()) continue;
3903 
3904       address pending = (address)p->current_pending_monitor();
3905       if (pending == monitor) {             // found a match
3906         if (i < count) result->append(p);   // save the first count matches
3907         i++;
3908       }
3909     }
3910   }
3911   return result;
3912 }
3913 
3914 
3915 JavaThread *Threads::owning_thread_from_monitor_owner(address owner, bool doLock) {
3916   assert(doLock ||
3917          Threads_lock->owned_by_self() ||
3918          SafepointSynchronize::is_at_safepoint(),
3919          "must grab Threads_lock or be at safepoint");
3920 
3921   // NULL owner means not locked so we can skip the search
3922   if (owner == NULL) return NULL;
3923 
3924   {
3925     MutexLockerEx ml(doLock ? Threads_lock : NULL);
3926     ALL_JAVA_THREADS(p) {
3927       // first, see if owner is the address of a Java thread
3928       if (owner == (address)p) return p;
3929     }
3930   }
3931   assert(UseHeavyMonitors == false, "Did not find owning Java thread with UseHeavyMonitors enabled");
3932   if (UseHeavyMonitors) return NULL;
3933 
3934   //
3935   // If we didn't find a matching Java thread and we didn't force use of
3936   // heavyweight monitors, then the owner is the stack address of the
3937   // Lock Word in the owning Java thread's stack.
3938   //
3939   JavaThread* the_owner = NULL;
3940   {
3941     MutexLockerEx ml(doLock ? Threads_lock : NULL);
3942     ALL_JAVA_THREADS(q) {
3943       if (q->is_lock_owned(owner)) {
3944         the_owner = q;
3945         break;
3946       }
3947     }
3948   }
3949   assert(the_owner != NULL, "Did not find owning Java thread for lock word address");
3950   return the_owner;
3951 }
3952 
3953 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
3954 void Threads::print_on(outputStream* st, bool print_stacks, bool internal_format, bool print_concurrent_locks) {
3955   char buf[32];
3956   st->print_cr(os::local_time_string(buf, sizeof(buf)));
3957 
3958   st->print_cr("Full thread dump %s (%s %s):",
3959                 Abstract_VM_Version::vm_name(),
3960                 Abstract_VM_Version::vm_release(),
3961                 Abstract_VM_Version::vm_info_string()
3962                );
3963   st->cr();
3964 
3965 #ifndef SERIALGC
3966   // Dump concurrent locks
3967   ConcurrentLocksDump concurrent_locks;
3968   if (print_concurrent_locks) {
3969     concurrent_locks.dump_at_safepoint();
3970   }
3971 #endif // SERIALGC
3972 
3973   ALL_JAVA_THREADS(p) {
3974     ResourceMark rm;
3975     p->print_on(st);
3976     if (print_stacks) {
3977       if (internal_format) {
3978         p->trace_stack();
3979       } else {
3980         p->print_stack_on(st);
3981       }
3982     }
3983     st->cr();
3984 #ifndef SERIALGC
3985     if (print_concurrent_locks) {
3986       concurrent_locks.print_locks_on(p, st);
3987     }
3988 #endif // SERIALGC
3989   }
3990 
3991   VMThread::vm_thread()->print_on(st);
3992   st->cr();
3993   Universe::heap()->print_gc_threads_on(st);
3994   WatcherThread* wt = WatcherThread::watcher_thread();
3995   if (wt != NULL) wt->print_on(st);
3996   st->cr();
3997   CompileBroker::print_compiler_threads_on(st);
3998   st->flush();
3999 }
4000 
4001 // Threads::print_on_error() is called by fatal error handler. It's possible
4002 // that VM is not at safepoint and/or current thread is inside signal handler.
4003 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4004 // memory (even in resource area), it might deadlock the error handler.
4005 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, int buflen) {
4006   bool found_current = false;
4007   st->print_cr("Java Threads: ( => current thread )");
4008   ALL_JAVA_THREADS(thread) {
4009     bool is_current = (current == thread);
4010     found_current = found_current || is_current;
4011 
4012     st->print("%s", is_current ? "=>" : "  ");
4013 
4014     st->print(PTR_FORMAT, thread);
4015     st->print(" ");
4016     thread->print_on_error(st, buf, buflen);
4017     st->cr();
4018   }
4019   st->cr();
4020 
4021   st->print_cr("Other Threads:");
4022   if (VMThread::vm_thread()) {
4023     bool is_current = (current == VMThread::vm_thread());
4024     found_current = found_current || is_current;
4025     st->print("%s", current == VMThread::vm_thread() ? "=>" : "  ");
4026 
4027     st->print(PTR_FORMAT, VMThread::vm_thread());
4028     st->print(" ");
4029     VMThread::vm_thread()->print_on_error(st, buf, buflen);
4030     st->cr();
4031   }
4032   WatcherThread* wt = WatcherThread::watcher_thread();
4033   if (wt != NULL) {
4034     bool is_current = (current == wt);
4035     found_current = found_current || is_current;
4036     st->print("%s", is_current ? "=>" : "  ");
4037 
4038     st->print(PTR_FORMAT, wt);
4039     st->print(" ");
4040     wt->print_on_error(st, buf, buflen);
4041     st->cr();
4042   }
4043   if (!found_current) {
4044     st->cr();
4045     st->print("=>" PTR_FORMAT " (exited) ", current);
4046     current->print_on_error(st, buf, buflen);
4047     st->cr();
4048   }
4049 }
4050 
4051 // Internal SpinLock and Mutex
4052 // Based on ParkEvent
4053 
4054 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4055 //
4056 // We employ SpinLocks _only for low-contention, fixed-length
4057 // short-duration critical sections where we're concerned
4058 // about native mutex_t or HotSpot Mutex:: latency.
4059 // The mux construct provides a spin-then-block mutual exclusion
4060 // mechanism.
4061 //
4062 // Testing has shown that contention on the ListLock guarding gFreeList
4063 // is common.  If we implement ListLock as a simple SpinLock it's common
4064 // for the JVM to devolve to yielding with little progress.  This is true
4065 // despite the fact that the critical sections protected by ListLock are
4066 // extremely short.
4067 //
4068 // TODO-FIXME: ListLock should be of type SpinLock.
4069 // We should make this a 1st-class type, integrated into the lock
4070 // hierarchy as leaf-locks.  Critically, the SpinLock structure
4071 // should have sufficient padding to avoid false-sharing and excessive
4072 // cache-coherency traffic.
4073 
4074 
4075 typedef volatile int SpinLockT ;
4076 
4077 void Thread::SpinAcquire (volatile int * adr, const char * LockName) {
4078   if (Atomic::cmpxchg (1, adr, 0) == 0) {
4079      return ;   // normal fast-path return
4080   }
4081 
4082   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4083   TEVENT (SpinAcquire - ctx) ;
4084   int ctr = 0 ;
4085   int Yields = 0 ;
4086   for (;;) {
4087      while (*adr != 0) {
4088         ++ctr ;
4089         if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4090            if (Yields > 5) {
4091              // Consider using a simple NakedSleep() instead.
4092              // Then SpinAcquire could be called by non-JVM threads
4093              Thread::current()->_ParkEvent->park(1) ;
4094            } else {
4095              os::NakedYield() ;
4096              ++Yields ;
4097            }
4098         } else {
4099            SpinPause() ;
4100         }
4101      }
4102      if (Atomic::cmpxchg (1, adr, 0) == 0) return ;
4103   }
4104 }
4105 
4106 void Thread::SpinRelease (volatile int * adr) {
4107   assert (*adr != 0, "invariant") ;
4108   OrderAccess::fence() ;      // guarantee at least release consistency.
4109   // Roach-motel semantics.
4110   // It's safe if subsequent LDs and STs float "up" into the critical section,
4111   // but prior LDs and STs within the critical section can't be allowed
4112   // to reorder or float past the ST that releases the lock.
4113   *adr = 0 ;
4114 }
4115 
4116 // muxAcquire and muxRelease:
4117 //
4118 // *  muxAcquire and muxRelease support a single-word lock-word construct.
4119 //    The LSB of the word is set IFF the lock is held.
4120 //    The remainder of the word points to the head of a singly-linked list
4121 //    of threads blocked on the lock.
4122 //
4123 // *  The current implementation of muxAcquire-muxRelease uses its own
4124 //    dedicated Thread._MuxEvent instance.  If we're interested in
4125 //    minimizing the peak number of extant ParkEvent instances then
4126 //    we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4127 //    as certain invariants were satisfied.  Specifically, care would need
4128 //    to be taken with regards to consuming unpark() "permits".
4129 //    A safe rule of thumb is that a thread would never call muxAcquire()
4130 //    if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4131 //    park().  Otherwise the _ParkEvent park() operation in muxAcquire() could
4132 //    consume an unpark() permit intended for monitorenter, for instance.
4133 //    One way around this would be to widen the restricted-range semaphore
4134 //    implemented in park().  Another alternative would be to provide
4135 //    multiple instances of the PlatformEvent() for each thread.  One
4136 //    instance would be dedicated to muxAcquire-muxRelease, for instance.
4137 //
4138 // *  Usage:
4139 //    -- Only as leaf locks
4140 //    -- for short-term locking only as muxAcquire does not perform
4141 //       thread state transitions.
4142 //
4143 // Alternatives:
4144 // *  We could implement muxAcquire and muxRelease with MCS or CLH locks
4145 //    but with parking or spin-then-park instead of pure spinning.
4146 // *  Use Taura-Oyama-Yonenzawa locks.
4147 // *  It's possible to construct a 1-0 lock if we encode the lockword as
4148 //    (List,LockByte).  Acquire will CAS the full lockword while Release
4149 //    will STB 0 into the LockByte.  The 1-0 scheme admits stranding, so
4150 //    acquiring threads use timers (ParkTimed) to detect and recover from
4151 //    the stranding window.  Thread/Node structures must be aligned on 256-byte
4152 //    boundaries by using placement-new.
4153 // *  Augment MCS with advisory back-link fields maintained with CAS().
4154 //    Pictorially:  LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4155 //    The validity of the backlinks must be ratified before we trust the value.
4156 //    If the backlinks are invalid the exiting thread must back-track through the
4157 //    the forward links, which are always trustworthy.
4158 // *  Add a successor indication.  The LockWord is currently encoded as
4159 //    (List, LOCKBIT:1).  We could also add a SUCCBIT or an explicit _succ variable
4160 //    to provide the usual futile-wakeup optimization.
4161 //    See RTStt for details.
4162 // *  Consider schedctl.sc_nopreempt to cover the critical section.
4163 //
4164 
4165 
4166 typedef volatile intptr_t MutexT ;      // Mux Lock-word
4167 enum MuxBits { LOCKBIT = 1 } ;
4168 
4169 void Thread::muxAcquire (volatile intptr_t * Lock, const char * LockName) {
4170   intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ;
4171   if (w == 0) return ;
4172   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4173      return ;
4174   }
4175 
4176   TEVENT (muxAcquire - Contention) ;
4177   ParkEvent * const Self = Thread::current()->_MuxEvent ;
4178   assert ((intptr_t(Self) & LOCKBIT) == 0, "invariant") ;
4179   for (;;) {
4180      int its = (os::is_MP() ? 100 : 0) + 1 ;
4181 
4182      // Optional spin phase: spin-then-park strategy
4183      while (--its >= 0) {
4184        w = *Lock ;
4185        if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4186           return ;
4187        }
4188      }
4189 
4190      Self->reset() ;
4191      Self->OnList = intptr_t(Lock) ;
4192      // The following fence() isn't _strictly necessary as the subsequent
4193      // CAS() both serializes execution and ratifies the fetched *Lock value.
4194      OrderAccess::fence();
4195      for (;;) {
4196         w = *Lock ;
4197         if ((w & LOCKBIT) == 0) {
4198             if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4199                 Self->OnList = 0 ;   // hygiene - allows stronger asserts
4200                 return ;
4201             }
4202             continue ;      // Interference -- *Lock changed -- Just retry
4203         }
4204         assert (w & LOCKBIT, "invariant") ;
4205         Self->ListNext = (ParkEvent *) (w & ~LOCKBIT );
4206         if (Atomic::cmpxchg_ptr (intptr_t(Self)|LOCKBIT, Lock, w) == w) break ;
4207      }
4208 
4209      while (Self->OnList != 0) {
4210         Self->park() ;
4211      }
4212   }
4213 }
4214 
4215 void Thread::muxAcquireW (volatile intptr_t * Lock, ParkEvent * ev) {
4216   intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ;
4217   if (w == 0) return ;
4218   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4219     return ;
4220   }
4221 
4222   TEVENT (muxAcquire - Contention) ;
4223   ParkEvent * ReleaseAfter = NULL ;
4224   if (ev == NULL) {
4225     ev = ReleaseAfter = ParkEvent::Allocate (NULL) ;
4226   }
4227   assert ((intptr_t(ev) & LOCKBIT) == 0, "invariant") ;
4228   for (;;) {
4229     guarantee (ev->OnList == 0, "invariant") ;
4230     int its = (os::is_MP() ? 100 : 0) + 1 ;
4231 
4232     // Optional spin phase: spin-then-park strategy
4233     while (--its >= 0) {
4234       w = *Lock ;
4235       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4236         if (ReleaseAfter != NULL) {
4237           ParkEvent::Release (ReleaseAfter) ;
4238         }
4239         return ;
4240       }
4241     }
4242 
4243     ev->reset() ;
4244     ev->OnList = intptr_t(Lock) ;
4245     // The following fence() isn't _strictly necessary as the subsequent
4246     // CAS() both serializes execution and ratifies the fetched *Lock value.
4247     OrderAccess::fence();
4248     for (;;) {
4249       w = *Lock ;
4250       if ((w & LOCKBIT) == 0) {
4251         if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4252           ev->OnList = 0 ;
4253           // We call ::Release while holding the outer lock, thus
4254           // artificially lengthening the critical section.
4255           // Consider deferring the ::Release() until the subsequent unlock(),
4256           // after we've dropped the outer lock.
4257           if (ReleaseAfter != NULL) {
4258             ParkEvent::Release (ReleaseAfter) ;
4259           }
4260           return ;
4261         }
4262         continue ;      // Interference -- *Lock changed -- Just retry
4263       }
4264       assert (w & LOCKBIT, "invariant") ;
4265       ev->ListNext = (ParkEvent *) (w & ~LOCKBIT );
4266       if (Atomic::cmpxchg_ptr (intptr_t(ev)|LOCKBIT, Lock, w) == w) break ;
4267     }
4268 
4269     while (ev->OnList != 0) {
4270       ev->park() ;
4271     }
4272   }
4273 }
4274 
4275 // Release() must extract a successor from the list and then wake that thread.
4276 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4277 // similar to that used by ParkEvent::Allocate() and ::Release().  DMR-based
4278 // Release() would :
4279 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4280 // (B) Extract a successor from the private list "in-hand"
4281 // (C) attempt to CAS() the residual back into *Lock over null.
4282 //     If there were any newly arrived threads and the CAS() would fail.
4283 //     In that case Release() would detach the RATs, re-merge the list in-hand
4284 //     with the RATs and repeat as needed.  Alternately, Release() might
4285 //     detach and extract a successor, but then pass the residual list to the wakee.
4286 //     The wakee would be responsible for reattaching and remerging before it
4287 //     competed for the lock.
4288 //
4289 // Both "pop" and DMR are immune from ABA corruption -- there can be
4290 // multiple concurrent pushers, but only one popper or detacher.
4291 // This implementation pops from the head of the list.  This is unfair,
4292 // but tends to provide excellent throughput as hot threads remain hot.
4293 // (We wake recently run threads first).
4294 
4295 void Thread::muxRelease (volatile intptr_t * Lock)  {
4296   for (;;) {
4297     const intptr_t w = Atomic::cmpxchg_ptr (0, Lock, LOCKBIT) ;
4298     assert (w & LOCKBIT, "invariant") ;
4299     if (w == LOCKBIT) return ;
4300     ParkEvent * List = (ParkEvent *) (w & ~LOCKBIT) ;
4301     assert (List != NULL, "invariant") ;
4302     assert (List->OnList == intptr_t(Lock), "invariant") ;
4303     ParkEvent * nxt = List->ListNext ;
4304 
4305     // The following CAS() releases the lock and pops the head element.
4306     if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4307       continue ;
4308     }
4309     List->OnList = 0 ;
4310     OrderAccess::fence() ;
4311     List->unpark () ;
4312     return ;
4313   }
4314 }
4315 
4316 
4317 void Threads::verify() {
4318   ALL_JAVA_THREADS(p) {
4319     p->verify();
4320   }
4321   VMThread* thread = VMThread::vm_thread();
4322   if (thread != NULL) thread->verify();
4323 }
--- EOF ---