1 /*
   2  * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/classLoader.hpp"
  27 #include "classfile/javaClasses.hpp"
  28 #include "classfile/systemDictionary.hpp"
  29 #include "classfile/vmSymbols.hpp"
  30 #include "code/codeCache.hpp"
  31 #include "code/scopeDesc.hpp"
  32 #include "compiler/compileBroker.hpp"
  33 #include "interpreter/interpreter.hpp"
  34 #include "interpreter/linkResolver.hpp"
  35 #include "interpreter/oopMapCache.hpp"
  36 #include "jvmtifiles/jvmtiEnv.hpp"
  37 #include "memory/gcLocker.inline.hpp"
  38 #include "memory/metaspaceShared.hpp"
  39 #include "memory/oopFactory.hpp"
  40 #include "memory/universe.inline.hpp"
  41 #include "oops/instanceKlass.hpp"
  42 #include "oops/objArrayOop.hpp"
  43 #include "oops/oop.inline.hpp"
  44 #include "oops/symbol.hpp"
  45 #include "prims/jvm_misc.hpp"
  46 #include "prims/jvmtiExport.hpp"
  47 #include "prims/jvmtiThreadState.hpp"
  48 #include "prims/privilegedStack.hpp"
  49 #include "runtime/arguments.hpp"
  50 #include "runtime/atomic.inline.hpp"
  51 #include "runtime/biasedLocking.hpp"
  52 #include "runtime/deoptimization.hpp"
  53 #include "runtime/fprofiler.hpp"
  54 #include "runtime/frame.inline.hpp"
  55 #include "runtime/init.hpp"
  56 #include "runtime/interfaceSupport.hpp"
  57 #include "runtime/java.hpp"
  58 #include "runtime/javaCalls.hpp"
  59 #include "runtime/jniPeriodicChecker.hpp"
  60 #include "runtime/memprofiler.hpp"
  61 #include "runtime/mutexLocker.hpp"
  62 #include "runtime/objectMonitor.hpp"
  63 #include "runtime/orderAccess.inline.hpp"
  64 #include "runtime/osThread.hpp"
  65 #include "runtime/safepoint.hpp"
  66 #include "runtime/sharedRuntime.hpp"
  67 #include "runtime/statSampler.hpp"
  68 #include "runtime/stubRoutines.hpp"
  69 #include "runtime/task.hpp"
  70 #include "runtime/thread.inline.hpp"
  71 #include "runtime/threadCritical.hpp"
  72 #include "runtime/threadLocalStorage.hpp"
  73 #include "runtime/vframe.hpp"
  74 #include "runtime/vframeArray.hpp"
  75 #include "runtime/vframe_hp.hpp"
  76 #include "runtime/vmThread.hpp"
  77 #include "runtime/vm_operations.hpp"
  78 #include "runtime/vm_version.hpp"
  79 #include "services/attachListener.hpp"
  80 #include "services/management.hpp"
  81 #include "services/memTracker.hpp"
  82 #include "services/threadService.hpp"
  83 #include "trace/tracing.hpp"
  84 #include "trace/traceMacros.hpp"
  85 #include "utilities/defaultStream.hpp"
  86 #include "utilities/dtrace.hpp"
  87 #include "utilities/events.hpp"
  88 #include "utilities/preserveException.hpp"
  89 #include "utilities/macros.hpp"
  90 #if INCLUDE_ALL_GCS
  91 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
  92 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
  93 #include "gc_implementation/parallelScavenge/pcTasks.hpp"
  94 #endif // INCLUDE_ALL_GCS
  95 #ifdef COMPILER1
  96 #include "c1/c1_Compiler.hpp"
  97 #endif
  98 #ifdef COMPILER2
  99 #include "opto/c2compiler.hpp"
 100 #include "opto/idealGraphPrinter.hpp"
 101 #endif
 102 #if INCLUDE_RTM_OPT
 103 #include "runtime/rtmLocking.hpp"
 104 #endif
 105 
 106 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
 107 
 108 #ifdef DTRACE_ENABLED
 109 
 110 // Only bother with this argument setup if dtrace is available
 111 
 112   #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
 113   #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
 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       HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */               \
 122         (char *) name, len,                                                \
 123         java_lang_Thread::thread_id((javathread)->threadObj()),            \
 124         (uintptr_t) (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 
 135 // Class hierarchy
 136 // - Thread
 137 //   - VMThread
 138 //   - WatcherThread
 139 //   - ConcurrentMarkSweepThread
 140 //   - JavaThread
 141 //     - CompilerThread
 142 
 143 // ======= Thread ========
 144 // Support for forcing alignment of thread objects for biased locking
 145 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
 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 = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
 150                                           : AllocateHeap(aligned_size, flags, CURRENT_PC,
 151                                                          AllocFailStrategy::RETURN_NULL);
 152     void* aligned_addr     = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
 153     assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
 154            ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
 155            "JavaThread alignment code overflowed allocated storage");
 156     if (TraceBiasedLocking) {
 157       if (aligned_addr != real_malloc_addr) {
 158         tty->print_cr("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
 159                       real_malloc_addr, aligned_addr);
 160       }
 161     }
 162     ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
 163     return aligned_addr;
 164   } else {
 165     return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
 166                        : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
 167   }
 168 }
 169 
 170 void Thread::operator delete(void* p) {
 171   if (UseBiasedLocking) {
 172     void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
 173     FreeHeap(real_malloc_addr, mtThread);
 174   } else {
 175     FreeHeap(p, mtThread);
 176   }
 177 }
 178 
 179 
 180 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
 181 // JavaThread
 182 
 183 
 184 Thread::Thread() {
 185   // stack and get_thread
 186   set_stack_base(NULL);
 187   set_stack_size(0);
 188   set_self_raw_id(0);
 189   set_lgrp_id(-1);
 190 
 191   // allocated data structures
 192   set_osthread(NULL);
 193   set_resource_area(new (mtThread)ResourceArea());
 194   DEBUG_ONLY(_current_resource_mark = NULL;)
 195   set_handle_area(new (mtThread) HandleArea(NULL));
 196   set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
 197   set_active_handles(NULL);
 198   set_free_handle_block(NULL);
 199   set_last_handle_mark(NULL);
 200 
 201   // This initial value ==> never claimed.
 202   _oops_do_parity = 0;
 203 
 204   // the handle mark links itself to last_handle_mark
 205   new HandleMark(this);
 206 
 207   // plain initialization
 208   debug_only(_owned_locks = NULL;)
 209   debug_only(_allow_allocation_count = 0;)
 210   NOT_PRODUCT(_allow_safepoint_count = 0;)
 211   NOT_PRODUCT(_skip_gcalot = false;)
 212   _jvmti_env_iteration_count = 0;
 213   set_allocated_bytes(0);
 214   _vm_operation_started_count = 0;
 215   _vm_operation_completed_count = 0;
 216   _current_pending_monitor = NULL;
 217   _current_pending_monitor_is_from_java = true;
 218   _current_waiting_monitor = NULL;
 219   _num_nested_signal = 0;
 220   omFreeList = NULL;
 221   omFreeCount = 0;
 222   omFreeProvision = 32;
 223   omInUseList = NULL;
 224   omInUseCount = 0;
 225 
 226 #ifdef ASSERT
 227   _visited_for_critical_count = false;
 228 #endif
 229 
 230   _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true);
 231   _suspend_flags = 0;
 232 
 233   // thread-specific hashCode stream generator state - Marsaglia shift-xor form
 234   _hashStateX = os::random();
 235   _hashStateY = 842502087;
 236   _hashStateZ = 0x8767;    // (int)(3579807591LL & 0xffff) ;
 237   _hashStateW = 273326509;
 238 
 239   _OnTrap   = 0;
 240   _schedctl = NULL;
 241   _Stalled  = 0;
 242   _TypeTag  = 0x2BAD;
 243 
 244   // Many of the following fields are effectively final - immutable
 245   // Note that nascent threads can't use the Native Monitor-Mutex
 246   // construct until the _MutexEvent is initialized ...
 247   // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
 248   // we might instead use a stack of ParkEvents that we could provision on-demand.
 249   // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
 250   // and ::Release()
 251   _ParkEvent   = ParkEvent::Allocate(this);
 252   _SleepEvent  = ParkEvent::Allocate(this);
 253   _MutexEvent  = ParkEvent::Allocate(this);
 254   _MuxEvent    = ParkEvent::Allocate(this);
 255 
 256 #ifdef CHECK_UNHANDLED_OOPS
 257   if (CheckUnhandledOops) {
 258     _unhandled_oops = new UnhandledOops(this);
 259   }
 260 #endif // CHECK_UNHANDLED_OOPS
 261 #ifdef ASSERT
 262   if (UseBiasedLocking) {
 263     assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
 264     assert(this == _real_malloc_address ||
 265            this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
 266            "bug in forced alignment of thread objects");
 267   }
 268 #endif // ASSERT
 269 }
 270 
 271 void Thread::initialize_thread_local_storage() {
 272   // Note: Make sure this method only calls
 273   // non-blocking operations. Otherwise, it might not work
 274   // with the thread-startup/safepoint interaction.
 275 
 276   // During Java thread startup, safepoint code should allow this
 277   // method to complete because it may need to allocate memory to
 278   // store information for the new thread.
 279 
 280   // initialize structure dependent on thread local storage
 281   ThreadLocalStorage::set_thread(this);
 282 }
 283 
 284 void Thread::record_stack_base_and_size() {
 285   set_stack_base(os::current_stack_base());
 286   set_stack_size(os::current_stack_size());
 287   if (is_Java_thread()) {
 288     ((JavaThread*) this)->set_stack_overflow_limit();
 289   }
 290   // CR 7190089: on Solaris, primordial thread's stack is adjusted
 291   // in initialize_thread(). Without the adjustment, stack size is
 292   // incorrect if stack is set to unlimited (ulimit -s unlimited).
 293   // So far, only Solaris has real implementation of initialize_thread().
 294   //
 295   // set up any platform-specific state.
 296   os::initialize_thread(this);
 297 
 298 #if INCLUDE_NMT
 299   // record thread's native stack, stack grows downward
 300   address stack_low_addr = stack_base() - stack_size();
 301   MemTracker::record_thread_stack(stack_low_addr, stack_size());
 302 #endif // INCLUDE_NMT
 303 }
 304 
 305 
 306 Thread::~Thread() {
 307   // Reclaim the objectmonitors from the omFreeList of the moribund thread.
 308   ObjectSynchronizer::omFlush(this);
 309 
 310   EVENT_THREAD_DESTRUCT(this);
 311 
 312   // stack_base can be NULL if the thread is never started or exited before
 313   // record_stack_base_and_size called. Although, we would like to ensure
 314   // that all started threads do call record_stack_base_and_size(), there is
 315   // not proper way to enforce that.
 316 #if INCLUDE_NMT
 317   if (_stack_base != NULL) {
 318     address low_stack_addr = stack_base() - stack_size();
 319     MemTracker::release_thread_stack(low_stack_addr, stack_size());
 320 #ifdef ASSERT
 321     set_stack_base(NULL);
 322 #endif
 323   }
 324 #endif // INCLUDE_NMT
 325 
 326   // deallocate data structures
 327   delete resource_area();
 328   // since the handle marks are using the handle area, we have to deallocated the root
 329   // handle mark before deallocating the thread's handle area,
 330   assert(last_handle_mark() != NULL, "check we have an element");
 331   delete last_handle_mark();
 332   assert(last_handle_mark() == NULL, "check we have reached the end");
 333 
 334   // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
 335   // We NULL out the fields for good hygiene.
 336   ParkEvent::Release(_ParkEvent); _ParkEvent   = NULL;
 337   ParkEvent::Release(_SleepEvent); _SleepEvent  = NULL;
 338   ParkEvent::Release(_MutexEvent); _MutexEvent  = NULL;
 339   ParkEvent::Release(_MuxEvent); _MuxEvent    = NULL;
 340 
 341   delete handle_area();
 342   delete metadata_handles();
 343 
 344   // osthread() can be NULL, if creation of thread failed.
 345   if (osthread() != NULL) os::free_thread(osthread());
 346 
 347   delete _SR_lock;
 348 
 349   // clear thread local storage if the Thread is deleting itself
 350   if (this == Thread::current()) {
 351     ThreadLocalStorage::set_thread(NULL);
 352   } else {
 353     // In the case where we're not the current thread, invalidate all the
 354     // caches in case some code tries to get the current thread or the
 355     // thread that was destroyed, and gets stale information.
 356     ThreadLocalStorage::invalidate_all();
 357   }
 358   CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
 359 }
 360 
 361 // NOTE: dummy function for assertion purpose.
 362 void Thread::run() {
 363   ShouldNotReachHere();
 364 }
 365 
 366 #ifdef ASSERT
 367 // Private method to check for dangling thread pointer
 368 void check_for_dangling_thread_pointer(Thread *thread) {
 369   assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
 370          "possibility of dangling Thread pointer");
 371 }
 372 #endif
 373 
 374 
 375 #ifndef PRODUCT
 376 // Tracing method for basic thread operations
 377 void Thread::trace(const char* msg, const Thread* const thread) {
 378   if (!TraceThreadEvents) return;
 379   ResourceMark rm;
 380   ThreadCritical tc;
 381   const char *name = "non-Java thread";
 382   int prio = -1;
 383   if (thread->is_Java_thread()
 384       && !thread->is_Compiler_thread()) {
 385     // The Threads_lock must be held to get information about
 386     // this thread but may not be in some situations when
 387     // tracing  thread events.
 388     bool release_Threads_lock = false;
 389     if (!Threads_lock->owned_by_self()) {
 390       Threads_lock->lock();
 391       release_Threads_lock = true;
 392     }
 393     JavaThread* jt = (JavaThread *)thread;
 394     name = (char *)jt->get_thread_name();
 395     oop thread_oop = jt->threadObj();
 396     if (thread_oop != NULL) {
 397       prio = java_lang_Thread::priority(thread_oop);
 398     }
 399     if (release_Threads_lock) {
 400       Threads_lock->unlock();
 401     }
 402   }
 403   tty->print_cr("Thread::%s " INTPTR_FORMAT " [%lx] %s (prio: %d)", msg, thread, thread->osthread()->thread_id(), name, prio);
 404 }
 405 #endif
 406 
 407 
 408 ThreadPriority Thread::get_priority(const Thread* const thread) {
 409   trace("get priority", thread);
 410   ThreadPriority priority;
 411   // Can return an error!
 412   (void)os::get_priority(thread, priority);
 413   assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
 414   return priority;
 415 }
 416 
 417 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
 418   trace("set priority", thread);
 419   debug_only(check_for_dangling_thread_pointer(thread);)
 420   // Can return an error!
 421   (void)os::set_priority(thread, priority);
 422 }
 423 
 424 
 425 void Thread::start(Thread* thread) {
 426   trace("start", thread);
 427   // Start is different from resume in that its safety is guaranteed by context or
 428   // being called from a Java method synchronized on the Thread object.
 429   if (!DisableStartThread) {
 430     if (thread->is_Java_thread()) {
 431       // Initialize the thread state to RUNNABLE before starting this thread.
 432       // Can not set it after the thread started because we do not know the
 433       // exact thread state at that time. It could be in MONITOR_WAIT or
 434       // in SLEEPING or some other state.
 435       java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
 436                                           java_lang_Thread::RUNNABLE);
 437     }
 438     os::start_thread(thread);
 439   }
 440 }
 441 
 442 // Enqueue a VM_Operation to do the job for us - sometime later
 443 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
 444   VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
 445   VMThread::execute(vm_stop);
 446 }
 447 
 448 
 449 // Check if an external suspend request has completed (or has been
 450 // cancelled). Returns true if the thread is externally suspended and
 451 // false otherwise.
 452 //
 453 // The bits parameter returns information about the code path through
 454 // the routine. Useful for debugging:
 455 //
 456 // set in is_ext_suspend_completed():
 457 // 0x00000001 - routine was entered
 458 // 0x00000010 - routine return false at end
 459 // 0x00000100 - thread exited (return false)
 460 // 0x00000200 - suspend request cancelled (return false)
 461 // 0x00000400 - thread suspended (return true)
 462 // 0x00001000 - thread is in a suspend equivalent state (return true)
 463 // 0x00002000 - thread is native and walkable (return true)
 464 // 0x00004000 - thread is native_trans and walkable (needed retry)
 465 //
 466 // set in wait_for_ext_suspend_completion():
 467 // 0x00010000 - routine was entered
 468 // 0x00020000 - suspend request cancelled before loop (return false)
 469 // 0x00040000 - thread suspended before loop (return true)
 470 // 0x00080000 - suspend request cancelled in loop (return false)
 471 // 0x00100000 - thread suspended in loop (return true)
 472 // 0x00200000 - suspend not completed during retry loop (return false)
 473 
 474 // Helper class for tracing suspend wait debug bits.
 475 //
 476 // 0x00000100 indicates that the target thread exited before it could
 477 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
 478 // 0x00080000 each indicate a cancelled suspend request so they don't
 479 // count as wait failures either.
 480 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
 481 
 482 class TraceSuspendDebugBits : public StackObj {
 483  private:
 484   JavaThread * jt;
 485   bool         is_wait;
 486   bool         called_by_wait;  // meaningful when !is_wait
 487   uint32_t *   bits;
 488 
 489  public:
 490   TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
 491                         uint32_t *_bits) {
 492     jt             = _jt;
 493     is_wait        = _is_wait;
 494     called_by_wait = _called_by_wait;
 495     bits           = _bits;
 496   }
 497 
 498   ~TraceSuspendDebugBits() {
 499     if (!is_wait) {
 500 #if 1
 501       // By default, don't trace bits for is_ext_suspend_completed() calls.
 502       // That trace is very chatty.
 503       return;
 504 #else
 505       if (!called_by_wait) {
 506         // If tracing for is_ext_suspend_completed() is enabled, then only
 507         // trace calls to it from wait_for_ext_suspend_completion()
 508         return;
 509       }
 510 #endif
 511     }
 512 
 513     if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
 514       if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
 515         MutexLocker ml(Threads_lock);  // needed for get_thread_name()
 516         ResourceMark rm;
 517 
 518         tty->print_cr(
 519                       "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
 520                       jt->get_thread_name(), *bits);
 521 
 522         guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
 523       }
 524     }
 525   }
 526 };
 527 #undef DEBUG_FALSE_BITS
 528 
 529 
 530 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
 531                                           uint32_t *bits) {
 532   TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
 533 
 534   bool did_trans_retry = false;  // only do thread_in_native_trans retry once
 535   bool do_trans_retry;           // flag to force the retry
 536 
 537   *bits |= 0x00000001;
 538 
 539   do {
 540     do_trans_retry = false;
 541 
 542     if (is_exiting()) {
 543       // Thread is in the process of exiting. This is always checked
 544       // first to reduce the risk of dereferencing a freed JavaThread.
 545       *bits |= 0x00000100;
 546       return false;
 547     }
 548 
 549     if (!is_external_suspend()) {
 550       // Suspend request is cancelled. This is always checked before
 551       // is_ext_suspended() to reduce the risk of a rogue resume
 552       // confusing the thread that made the suspend request.
 553       *bits |= 0x00000200;
 554       return false;
 555     }
 556 
 557     if (is_ext_suspended()) {
 558       // thread is suspended
 559       *bits |= 0x00000400;
 560       return true;
 561     }
 562 
 563     // Now that we no longer do hard suspends of threads running
 564     // native code, the target thread can be changing thread state
 565     // while we are in this routine:
 566     //
 567     //   _thread_in_native -> _thread_in_native_trans -> _thread_blocked
 568     //
 569     // We save a copy of the thread state as observed at this moment
 570     // and make our decision about suspend completeness based on the
 571     // copy. This closes the race where the thread state is seen as
 572     // _thread_in_native_trans in the if-thread_blocked check, but is
 573     // seen as _thread_blocked in if-thread_in_native_trans check.
 574     JavaThreadState save_state = thread_state();
 575 
 576     if (save_state == _thread_blocked && is_suspend_equivalent()) {
 577       // If the thread's state is _thread_blocked and this blocking
 578       // condition is known to be equivalent to a suspend, then we can
 579       // consider the thread to be externally suspended. This means that
 580       // the code that sets _thread_blocked has been modified to do
 581       // self-suspension if the blocking condition releases. We also
 582       // used to check for CONDVAR_WAIT here, but that is now covered by
 583       // the _thread_blocked with self-suspension check.
 584       //
 585       // Return true since we wouldn't be here unless there was still an
 586       // external suspend request.
 587       *bits |= 0x00001000;
 588       return true;
 589     } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
 590       // Threads running native code will self-suspend on native==>VM/Java
 591       // transitions. If its stack is walkable (should always be the case
 592       // unless this function is called before the actual java_suspend()
 593       // call), then the wait is done.
 594       *bits |= 0x00002000;
 595       return true;
 596     } else if (!called_by_wait && !did_trans_retry &&
 597                save_state == _thread_in_native_trans &&
 598                frame_anchor()->walkable()) {
 599       // The thread is transitioning from thread_in_native to another
 600       // thread state. check_safepoint_and_suspend_for_native_trans()
 601       // will force the thread to self-suspend. If it hasn't gotten
 602       // there yet we may have caught the thread in-between the native
 603       // code check above and the self-suspend. Lucky us. If we were
 604       // called by wait_for_ext_suspend_completion(), then it
 605       // will be doing the retries so we don't have to.
 606       //
 607       // Since we use the saved thread state in the if-statement above,
 608       // there is a chance that the thread has already transitioned to
 609       // _thread_blocked by the time we get here. In that case, we will
 610       // make a single unnecessary pass through the logic below. This
 611       // doesn't hurt anything since we still do the trans retry.
 612 
 613       *bits |= 0x00004000;
 614 
 615       // Once the thread leaves thread_in_native_trans for another
 616       // thread state, we break out of this retry loop. We shouldn't
 617       // need this flag to prevent us from getting back here, but
 618       // sometimes paranoia is good.
 619       did_trans_retry = true;
 620 
 621       // We wait for the thread to transition to a more usable state.
 622       for (int i = 1; i <= SuspendRetryCount; i++) {
 623         // We used to do an "os::yield_all(i)" call here with the intention
 624         // that yielding would increase on each retry. However, the parameter
 625         // is ignored on Linux which means the yield didn't scale up. Waiting
 626         // on the SR_lock below provides a much more predictable scale up for
 627         // the delay. It also provides a simple/direct point to check for any
 628         // safepoint requests from the VMThread
 629 
 630         // temporarily drops SR_lock while doing wait with safepoint check
 631         // (if we're a JavaThread - the WatcherThread can also call this)
 632         // and increase delay with each retry
 633         SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 634 
 635         // check the actual thread state instead of what we saved above
 636         if (thread_state() != _thread_in_native_trans) {
 637           // the thread has transitioned to another thread state so
 638           // try all the checks (except this one) one more time.
 639           do_trans_retry = true;
 640           break;
 641         }
 642       } // end retry loop
 643 
 644 
 645     }
 646   } while (do_trans_retry);
 647 
 648   *bits |= 0x00000010;
 649   return false;
 650 }
 651 
 652 // Wait for an external suspend request to complete (or be cancelled).
 653 // Returns true if the thread is externally suspended and false otherwise.
 654 //
 655 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
 656                                                  uint32_t *bits) {
 657   TraceSuspendDebugBits tsdb(this, true /* is_wait */,
 658                              false /* !called_by_wait */, bits);
 659 
 660   // local flag copies to minimize SR_lock hold time
 661   bool is_suspended;
 662   bool pending;
 663   uint32_t reset_bits;
 664 
 665   // set a marker so is_ext_suspend_completed() knows we are the caller
 666   *bits |= 0x00010000;
 667 
 668   // We use reset_bits to reinitialize the bits value at the top of
 669   // each retry loop. This allows the caller to make use of any
 670   // unused bits for their own marking purposes.
 671   reset_bits = *bits;
 672 
 673   {
 674     MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
 675     is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 676                                             delay, bits);
 677     pending = is_external_suspend();
 678   }
 679   // must release SR_lock to allow suspension to complete
 680 
 681   if (!pending) {
 682     // A cancelled suspend request is the only false return from
 683     // is_ext_suspend_completed() that keeps us from entering the
 684     // retry loop.
 685     *bits |= 0x00020000;
 686     return false;
 687   }
 688 
 689   if (is_suspended) {
 690     *bits |= 0x00040000;
 691     return true;
 692   }
 693 
 694   for (int i = 1; i <= retries; i++) {
 695     *bits = reset_bits;  // reinit to only track last retry
 696 
 697     // We used to do an "os::yield_all(i)" call here with the intention
 698     // that yielding would increase on each retry. However, the parameter
 699     // is ignored on Linux which means the yield didn't scale up. Waiting
 700     // on the SR_lock below provides a much more predictable scale up for
 701     // the delay. It also provides a simple/direct point to check for any
 702     // safepoint requests from the VMThread
 703 
 704     {
 705       MutexLocker ml(SR_lock());
 706       // wait with safepoint check (if we're a JavaThread - the WatcherThread
 707       // can also call this)  and increase delay with each retry
 708       SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 709 
 710       is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 711                                               delay, bits);
 712 
 713       // It is possible for the external suspend request to be cancelled
 714       // (by a resume) before the actual suspend operation is completed.
 715       // Refresh our local copy to see if we still need to wait.
 716       pending = is_external_suspend();
 717     }
 718 
 719     if (!pending) {
 720       // A cancelled suspend request is the only false return from
 721       // is_ext_suspend_completed() that keeps us from staying in the
 722       // retry loop.
 723       *bits |= 0x00080000;
 724       return false;
 725     }
 726 
 727     if (is_suspended) {
 728       *bits |= 0x00100000;
 729       return true;
 730     }
 731   } // end retry loop
 732 
 733   // thread did not suspend after all our retries
 734   *bits |= 0x00200000;
 735   return false;
 736 }
 737 
 738 #ifndef PRODUCT
 739 void JavaThread::record_jump(address target, address instr, const char* file,
 740                              int line) {
 741 
 742   // This should not need to be atomic as the only way for simultaneous
 743   // updates is via interrupts. Even then this should be rare or non-existent
 744   // and we don't care that much anyway.
 745 
 746   int index = _jmp_ring_index;
 747   _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
 748   _jmp_ring[index]._target = (intptr_t) target;
 749   _jmp_ring[index]._instruction = (intptr_t) instr;
 750   _jmp_ring[index]._file = file;
 751   _jmp_ring[index]._line = line;
 752 }
 753 #endif // PRODUCT
 754 
 755 // Called by flat profiler
 756 // Callers have already called wait_for_ext_suspend_completion
 757 // The assertion for that is currently too complex to put here:
 758 bool JavaThread::profile_last_Java_frame(frame* _fr) {
 759   bool gotframe = false;
 760   // self suspension saves needed state.
 761   if (has_last_Java_frame() && _anchor.walkable()) {
 762     *_fr = pd_last_frame();
 763     gotframe = true;
 764   }
 765   return gotframe;
 766 }
 767 
 768 void Thread::interrupt(Thread* thread) {
 769   trace("interrupt", thread);
 770   debug_only(check_for_dangling_thread_pointer(thread);)
 771   os::interrupt(thread);
 772 }
 773 
 774 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
 775   trace("is_interrupted", thread);
 776   debug_only(check_for_dangling_thread_pointer(thread);)
 777   // Note:  If clear_interrupted==false, this simply fetches and
 778   // returns the value of the field osthread()->interrupted().
 779   return os::is_interrupted(thread, clear_interrupted);
 780 }
 781 
 782 
 783 // GC Support
 784 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
 785   jint thread_parity = _oops_do_parity;
 786   if (thread_parity != strong_roots_parity) {
 787     jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
 788     if (res == thread_parity) {
 789       return true;
 790     } else {
 791       guarantee(res == strong_roots_parity, "Or else what?");
 792       assert(SharedHeap::heap()->workers()->active_workers() > 0,
 793              "Should only fail when parallel.");
 794       return false;
 795     }
 796   }
 797   assert(SharedHeap::heap()->workers()->active_workers() > 0,
 798          "Should only fail when parallel.");
 799   return false;
 800 }
 801 
 802 void Thread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
 803   active_handles()->oops_do(f);
 804   // Do oop for ThreadShadow
 805   f->do_oop((oop*)&_pending_exception);
 806   handle_area()->oops_do(f);
 807 }
 808 
 809 void Thread::nmethods_do(CodeBlobClosure* cf) {
 810   // no nmethods in a generic thread...
 811 }
 812 
 813 void Thread::metadata_do(void f(Metadata*)) {
 814   if (metadata_handles() != NULL) {
 815     for (int i = 0; i< metadata_handles()->length(); i++) {
 816       f(metadata_handles()->at(i));
 817     }
 818   }
 819 }
 820 
 821 void Thread::print_on(outputStream* st) const {
 822   // get_priority assumes osthread initialized
 823   if (osthread() != NULL) {
 824     int os_prio;
 825     if (os::get_native_priority(this, &os_prio) == OS_OK) {
 826       st->print("os_prio=%d ", os_prio);
 827     }
 828     st->print("tid=" INTPTR_FORMAT " ", this);
 829     ext().print_on(st);
 830     osthread()->print_on(st);
 831   }
 832   debug_only(if (WizardMode) print_owned_locks_on(st);)
 833 }
 834 
 835 // Thread::print_on_error() is called by fatal error handler. Don't use
 836 // any lock or allocate memory.
 837 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
 838   if (is_VM_thread())                 st->print("VMThread");
 839   else if (is_Compiler_thread())      st->print("CompilerThread");
 840   else if (is_Java_thread())          st->print("JavaThread");
 841   else if (is_GC_task_thread())       st->print("GCTaskThread");
 842   else if (is_Watcher_thread())       st->print("WatcherThread");
 843   else if (is_ConcurrentGC_thread())  st->print("ConcurrentGCThread");
 844   else                                st->print("Thread");
 845 
 846   st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
 847             _stack_base - _stack_size, _stack_base);
 848 
 849   if (osthread()) {
 850     st->print(" [id=%d]", osthread()->thread_id());
 851   }
 852 }
 853 
 854 #ifdef ASSERT
 855 void Thread::print_owned_locks_on(outputStream* st) const {
 856   Monitor *cur = _owned_locks;
 857   if (cur == NULL) {
 858     st->print(" (no locks) ");
 859   } else {
 860     st->print_cr(" Locks owned:");
 861     while (cur) {
 862       cur->print_on(st);
 863       cur = cur->next();
 864     }
 865   }
 866 }
 867 
 868 static int ref_use_count  = 0;
 869 
 870 bool Thread::owns_locks_but_compiled_lock() const {
 871   for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 872     if (cur != Compile_lock) return true;
 873   }
 874   return false;
 875 }
 876 
 877 
 878 #endif
 879 
 880 #ifndef PRODUCT
 881 
 882 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
 883 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
 884 // no threads which allow_vm_block's are held
 885 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
 886   // Check if current thread is allowed to block at a safepoint
 887   if (!(_allow_safepoint_count == 0)) {
 888     fatal("Possible safepoint reached by thread that does not allow it");
 889   }
 890   if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
 891     fatal("LEAF method calling lock?");
 892   }
 893 
 894 #ifdef ASSERT
 895   if (potential_vm_operation && is_Java_thread()
 896       && !Universe::is_bootstrapping()) {
 897     // Make sure we do not hold any locks that the VM thread also uses.
 898     // This could potentially lead to deadlocks
 899     for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 900       // Threads_lock is special, since the safepoint synchronization will not start before this is
 901       // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
 902       // since it is used to transfer control between JavaThreads and the VMThread
 903       // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
 904       if ((cur->allow_vm_block() &&
 905            cur != Threads_lock &&
 906            cur != Compile_lock &&               // Temporary: should not be necessary when we get separate compilation
 907            cur != VMOperationRequest_lock &&
 908            cur != VMOperationQueue_lock) ||
 909            cur->rank() == Mutex::special) {
 910         fatal(err_msg("Thread holding lock at safepoint that vm can block on: %s", cur->name()));
 911       }
 912     }
 913   }
 914 
 915   if (GCALotAtAllSafepoints) {
 916     // We could enter a safepoint here and thus have a gc
 917     InterfaceSupport::check_gc_alot();
 918   }
 919 #endif
 920 }
 921 #endif
 922 
 923 bool Thread::is_in_stack(address adr) const {
 924   assert(Thread::current() == this, "is_in_stack can only be called from current thread");
 925   address end = os::current_stack_pointer();
 926   // Allow non Java threads to call this without stack_base
 927   if (_stack_base == NULL) return true;
 928   if (stack_base() >= adr && adr >= end) return true;
 929 
 930   return false;
 931 }
 932 
 933 
 934 bool Thread::is_in_usable_stack(address adr) const {
 935   size_t stack_guard_size = os::uses_stack_guard_pages() ? (StackYellowPages + StackRedPages) * os::vm_page_size() : 0;
 936   size_t usable_stack_size = _stack_size - stack_guard_size;
 937 
 938   return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
 939 }
 940 
 941 
 942 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
 943 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
 944 // used for compilation in the future. If that change is made, the need for these methods
 945 // should be revisited, and they should be removed if possible.
 946 
 947 bool Thread::is_lock_owned(address adr) const {
 948   return on_local_stack(adr);
 949 }
 950 
 951 bool Thread::set_as_starting_thread() {
 952   // NOTE: this must be called inside the main thread.
 953   return os::create_main_thread((JavaThread*)this);
 954 }
 955 
 956 static void initialize_class(Symbol* class_name, TRAPS) {
 957   Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
 958   InstanceKlass::cast(klass)->initialize(CHECK);
 959 }
 960 
 961 
 962 // Creates the initial ThreadGroup
 963 static Handle create_initial_thread_group(TRAPS) {
 964   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
 965   instanceKlassHandle klass (THREAD, k);
 966 
 967   Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
 968   {
 969     JavaValue result(T_VOID);
 970     JavaCalls::call_special(&result,
 971                             system_instance,
 972                             klass,
 973                             vmSymbols::object_initializer_name(),
 974                             vmSymbols::void_method_signature(),
 975                             CHECK_NH);
 976   }
 977   Universe::set_system_thread_group(system_instance());
 978 
 979   Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
 980   {
 981     JavaValue result(T_VOID);
 982     Handle string = java_lang_String::create_from_str("main", CHECK_NH);
 983     JavaCalls::call_special(&result,
 984                             main_instance,
 985                             klass,
 986                             vmSymbols::object_initializer_name(),
 987                             vmSymbols::threadgroup_string_void_signature(),
 988                             system_instance,
 989                             string,
 990                             CHECK_NH);
 991   }
 992   return main_instance;
 993 }
 994 
 995 // Creates the initial Thread
 996 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
 997                                  TRAPS) {
 998   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
 999   instanceKlassHandle klass (THREAD, k);
1000   instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
1001 
1002   java_lang_Thread::set_thread(thread_oop(), thread);
1003   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1004   thread->set_threadObj(thread_oop());
1005 
1006   Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1007 
1008   JavaValue result(T_VOID);
1009   JavaCalls::call_special(&result, thread_oop,
1010                           klass,
1011                           vmSymbols::object_initializer_name(),
1012                           vmSymbols::threadgroup_string_void_signature(),
1013                           thread_group,
1014                           string,
1015                           CHECK_NULL);
1016   return thread_oop();
1017 }
1018 
1019 static void call_initializeSystemClass(TRAPS) {
1020   Klass* k =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1021   instanceKlassHandle klass (THREAD, k);
1022 
1023   JavaValue result(T_VOID);
1024   JavaCalls::call_static(&result, klass, vmSymbols::initializeSystemClass_name(),
1025                          vmSymbols::void_method_signature(), CHECK);
1026 }
1027 
1028 char java_runtime_name[128] = "";
1029 char java_runtime_version[128] = "";
1030 
1031 // extract the JRE name from sun.misc.Version.java_runtime_name
1032 static const char* get_java_runtime_name(TRAPS) {
1033   Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(),
1034                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1035   fieldDescriptor fd;
1036   bool found = k != NULL &&
1037                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1038                                                         vmSymbols::string_signature(), &fd);
1039   if (found) {
1040     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1041     if (name_oop == NULL) {
1042       return NULL;
1043     }
1044     const char* name = java_lang_String::as_utf8_string(name_oop,
1045                                                         java_runtime_name,
1046                                                         sizeof(java_runtime_name));
1047     return name;
1048   } else {
1049     return NULL;
1050   }
1051 }
1052 
1053 // extract the JRE version from sun.misc.Version.java_runtime_version
1054 static const char* get_java_runtime_version(TRAPS) {
1055   Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(),
1056                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1057   fieldDescriptor fd;
1058   bool found = k != NULL &&
1059                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1060                                                         vmSymbols::string_signature(), &fd);
1061   if (found) {
1062     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1063     if (name_oop == NULL) {
1064       return NULL;
1065     }
1066     const char* name = java_lang_String::as_utf8_string(name_oop,
1067                                                         java_runtime_version,
1068                                                         sizeof(java_runtime_version));
1069     return name;
1070   } else {
1071     return NULL;
1072   }
1073 }
1074 
1075 // General purpose hook into Java code, run once when the VM is initialized.
1076 // The Java library method itself may be changed independently from the VM.
1077 static void call_postVMInitHook(TRAPS) {
1078   Klass* k = SystemDictionary::resolve_or_null(vmSymbols::sun_misc_PostVMInitHook(), THREAD);
1079   instanceKlassHandle klass (THREAD, k);
1080   if (klass.not_null()) {
1081     JavaValue result(T_VOID);
1082     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1083                            vmSymbols::void_method_signature(),
1084                            CHECK);
1085   }
1086 }
1087 
1088 static void reset_vm_info_property(TRAPS) {
1089   // the vm info string
1090   ResourceMark rm(THREAD);
1091   const char *vm_info = VM_Version::vm_info_string();
1092 
1093   // java.lang.System class
1094   Klass* k =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1095   instanceKlassHandle klass (THREAD, k);
1096 
1097   // setProperty arguments
1098   Handle key_str    = java_lang_String::create_from_str("java.vm.info", CHECK);
1099   Handle value_str  = java_lang_String::create_from_str(vm_info, CHECK);
1100 
1101   // return value
1102   JavaValue r(T_OBJECT);
1103 
1104   // public static String setProperty(String key, String value);
1105   JavaCalls::call_static(&r,
1106                          klass,
1107                          vmSymbols::setProperty_name(),
1108                          vmSymbols::string_string_string_signature(),
1109                          key_str,
1110                          value_str,
1111                          CHECK);
1112 }
1113 
1114 
1115 void JavaThread::allocate_threadObj(Handle thread_group, char* thread_name,
1116                                     bool daemon, TRAPS) {
1117   assert(thread_group.not_null(), "thread group should be specified");
1118   assert(threadObj() == NULL, "should only create Java thread object once");
1119 
1120   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1121   instanceKlassHandle klass (THREAD, k);
1122   instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1123 
1124   java_lang_Thread::set_thread(thread_oop(), this);
1125   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1126   set_threadObj(thread_oop());
1127 
1128   JavaValue result(T_VOID);
1129   if (thread_name != NULL) {
1130     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1131     // Thread gets assigned specified name and null target
1132     JavaCalls::call_special(&result,
1133                             thread_oop,
1134                             klass,
1135                             vmSymbols::object_initializer_name(),
1136                             vmSymbols::threadgroup_string_void_signature(),
1137                             thread_group, // Argument 1
1138                             name,         // Argument 2
1139                             THREAD);
1140   } else {
1141     // Thread gets assigned name "Thread-nnn" and null target
1142     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1143     JavaCalls::call_special(&result,
1144                             thread_oop,
1145                             klass,
1146                             vmSymbols::object_initializer_name(),
1147                             vmSymbols::threadgroup_runnable_void_signature(),
1148                             thread_group, // Argument 1
1149                             Handle(),     // Argument 2
1150                             THREAD);
1151   }
1152 
1153 
1154   if (daemon) {
1155     java_lang_Thread::set_daemon(thread_oop());
1156   }
1157 
1158   if (HAS_PENDING_EXCEPTION) {
1159     return;
1160   }
1161 
1162   KlassHandle group(this, SystemDictionary::ThreadGroup_klass());
1163   Handle threadObj(this, this->threadObj());
1164 
1165   JavaCalls::call_special(&result,
1166                           thread_group,
1167                           group,
1168                           vmSymbols::add_method_name(),
1169                           vmSymbols::thread_void_signature(),
1170                           threadObj,          // Arg 1
1171                           THREAD);
1172 
1173 
1174 }
1175 
1176 // NamedThread --  non-JavaThread subclasses with multiple
1177 // uniquely named instances should derive from this.
1178 NamedThread::NamedThread() : Thread() {
1179   _name = NULL;
1180   _processed_thread = NULL;
1181 }
1182 
1183 NamedThread::~NamedThread() {
1184   if (_name != NULL) {
1185     FREE_C_HEAP_ARRAY(char, _name, mtThread);
1186     _name = NULL;
1187   }
1188 }
1189 
1190 void NamedThread::set_name(const char* format, ...) {
1191   guarantee(_name == NULL, "Only get to set name once.");
1192   _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1193   guarantee(_name != NULL, "alloc failure");
1194   va_list ap;
1195   va_start(ap, format);
1196   jio_vsnprintf(_name, max_name_len, format, ap);
1197   va_end(ap);
1198 }
1199 
1200 void NamedThread::print_on(outputStream* st) const {
1201   st->print("\"%s\" ", name());
1202   Thread::print_on(st);
1203   st->cr();
1204 }
1205 
1206 
1207 // ======= WatcherThread ========
1208 
1209 // The watcher thread exists to simulate timer interrupts.  It should
1210 // be replaced by an abstraction over whatever native support for
1211 // timer interrupts exists on the platform.
1212 
1213 WatcherThread* WatcherThread::_watcher_thread   = NULL;
1214 bool WatcherThread::_startable = false;
1215 volatile bool  WatcherThread::_should_terminate = false;
1216 
1217 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) {
1218   assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1219   if (os::create_thread(this, os::watcher_thread)) {
1220     _watcher_thread = this;
1221 
1222     // Set the watcher thread to the highest OS priority which should not be
1223     // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1224     // is created. The only normal thread using this priority is the reference
1225     // handler thread, which runs for very short intervals only.
1226     // If the VMThread's priority is not lower than the WatcherThread profiling
1227     // will be inaccurate.
1228     os::set_priority(this, MaxPriority);
1229     if (!DisableStartThread) {
1230       os::start_thread(this);
1231     }
1232   }
1233 }
1234 
1235 int WatcherThread::sleep() const {
1236   MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1237 
1238   // remaining will be zero if there are no tasks,
1239   // causing the WatcherThread to sleep until a task is
1240   // enrolled
1241   int remaining = PeriodicTask::time_to_wait();
1242   int time_slept = 0;
1243 
1244   // we expect this to timeout - we only ever get unparked when
1245   // we should terminate or when a new task has been enrolled
1246   OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1247 
1248   jlong time_before_loop = os::javaTimeNanos();
1249 
1250   for (;;) {
1251     bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, remaining);
1252     jlong now = os::javaTimeNanos();
1253 
1254     if (remaining == 0) {
1255       // if we didn't have any tasks we could have waited for a long time
1256       // consider the time_slept zero and reset time_before_loop
1257       time_slept = 0;
1258       time_before_loop = now;
1259     } else {
1260       // need to recalculate since we might have new tasks in _tasks
1261       time_slept = (int) ((now - time_before_loop) / 1000000);
1262     }
1263 
1264     // Change to task list or spurious wakeup of some kind
1265     if (timedout || _should_terminate) {
1266       break;
1267     }
1268 
1269     remaining = PeriodicTask::time_to_wait();
1270     if (remaining == 0) {
1271       // Last task was just disenrolled so loop around and wait until
1272       // another task gets enrolled
1273       continue;
1274     }
1275 
1276     remaining -= time_slept;
1277     if (remaining <= 0) {
1278       break;
1279     }
1280   }
1281 
1282   return time_slept;
1283 }
1284 
1285 void WatcherThread::run() {
1286   assert(this == watcher_thread(), "just checking");
1287 
1288   this->record_stack_base_and_size();
1289   this->initialize_thread_local_storage();
1290   this->set_active_handles(JNIHandleBlock::allocate_block());
1291   while (!_should_terminate) {
1292     assert(watcher_thread() == Thread::current(), "thread consistency check");
1293     assert(watcher_thread() == this, "thread consistency check");
1294 
1295     // Calculate how long it'll be until the next PeriodicTask work
1296     // should be done, and sleep that amount of time.
1297     int time_waited = sleep();
1298 
1299     if (is_error_reported()) {
1300       // A fatal error has happened, the error handler(VMError::report_and_die)
1301       // should abort JVM after creating an error log file. However in some
1302       // rare cases, the error handler itself might deadlock. Here we try to
1303       // kill JVM if the fatal error handler fails to abort in 2 minutes.
1304       //
1305       // This code is in WatcherThread because WatcherThread wakes up
1306       // periodically so the fatal error handler doesn't need to do anything;
1307       // also because the WatcherThread is less likely to crash than other
1308       // threads.
1309 
1310       for (;;) {
1311         if (!ShowMessageBoxOnError
1312             && (OnError == NULL || OnError[0] == '\0')
1313             && Arguments::abort_hook() == NULL) {
1314           os::sleep(this, 2 * 60 * 1000, false);
1315           fdStream err(defaultStream::output_fd());
1316           err.print_raw_cr("# [ timer expired, abort... ]");
1317           // skip atexit/vm_exit/vm_abort hooks
1318           os::die();
1319         }
1320 
1321         // Wake up 5 seconds later, the fatal handler may reset OnError or
1322         // ShowMessageBoxOnError when it is ready to abort.
1323         os::sleep(this, 5 * 1000, false);
1324       }
1325     }
1326 
1327     PeriodicTask::real_time_tick(time_waited);
1328   }
1329 
1330   // Signal that it is terminated
1331   {
1332     MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1333     _watcher_thread = NULL;
1334     Terminator_lock->notify();
1335   }
1336 
1337   // Thread destructor usually does this..
1338   ThreadLocalStorage::set_thread(NULL);
1339 }
1340 
1341 void WatcherThread::start() {
1342   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1343 
1344   if (watcher_thread() == NULL && _startable) {
1345     _should_terminate = false;
1346     // Create the single instance of WatcherThread
1347     new WatcherThread();
1348   }
1349 }
1350 
1351 void WatcherThread::make_startable() {
1352   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1353   _startable = true;
1354 }
1355 
1356 void WatcherThread::stop() {
1357   // Get the PeriodicTask_lock if we can. If we cannot, then the
1358   // WatcherThread is using it and we don't want to block on that lock
1359   // here because that might cause a safepoint deadlock depending on
1360   // what the current WatcherThread tasks are doing.
1361   bool have_lock = PeriodicTask_lock->try_lock();
1362 
1363   _should_terminate = true;
1364   OrderAccess::fence();  // ensure WatcherThread sees update in main loop
1365 
1366   if (have_lock) {
1367     WatcherThread* watcher = watcher_thread();
1368     if (watcher != NULL) {
1369       // If we managed to get the lock, then we should unpark the
1370       // WatcherThread so that it can see we want it to stop.
1371       watcher->unpark();
1372     }
1373 
1374     PeriodicTask_lock->unlock();
1375   }
1376 
1377   // it is ok to take late safepoints here, if needed
1378   MutexLocker mu(Terminator_lock);
1379 
1380   while (watcher_thread() != NULL) {
1381     // This wait should make safepoint checks, wait without a timeout,
1382     // and wait as a suspend-equivalent condition.
1383     //
1384     // Note: If the FlatProfiler is running, then this thread is waiting
1385     // for the WatcherThread to terminate and the WatcherThread, via the
1386     // FlatProfiler task, is waiting for the external suspend request on
1387     // this thread to complete. wait_for_ext_suspend_completion() will
1388     // eventually timeout, but that takes time. Making this wait a
1389     // suspend-equivalent condition solves that timeout problem.
1390     //
1391     Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1392                           Mutex::_as_suspend_equivalent_flag);
1393   }
1394 }
1395 
1396 void WatcherThread::unpark() {
1397   MutexLockerEx ml(PeriodicTask_lock->owned_by_self()
1398                    ? NULL
1399                    : PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1400   PeriodicTask_lock->notify();
1401 }
1402 
1403 void WatcherThread::print_on(outputStream* st) const {
1404   st->print("\"%s\" ", name());
1405   Thread::print_on(st);
1406   st->cr();
1407 }
1408 
1409 // ======= JavaThread ========
1410 
1411 // A JavaThread is a normal Java thread
1412 
1413 void JavaThread::initialize() {
1414   // Initialize fields
1415 
1416   // Set the claimed par_id to UINT_MAX (ie not claiming any par_ids)
1417   set_claimed_par_id(UINT_MAX);
1418 
1419   set_saved_exception_pc(NULL);
1420   set_threadObj(NULL);
1421   _anchor.clear();
1422   set_entry_point(NULL);
1423   set_jni_functions(jni_functions());
1424   set_callee_target(NULL);
1425   set_vm_result(NULL);
1426   set_vm_result_2(NULL);
1427   set_vframe_array_head(NULL);
1428   set_vframe_array_last(NULL);
1429   set_deferred_locals(NULL);
1430   set_deopt_mark(NULL);
1431   set_deopt_nmethod(NULL);
1432   clear_must_deopt_id();
1433   set_monitor_chunks(NULL);
1434   set_next(NULL);
1435   set_thread_state(_thread_new);
1436   _terminated = _not_terminated;
1437   _privileged_stack_top = NULL;
1438   _array_for_gc = NULL;
1439   _suspend_equivalent = false;
1440   _in_deopt_handler = 0;
1441   _doing_unsafe_access = false;
1442   _stack_guard_state = stack_guard_unused;
1443   (void)const_cast<oop&>(_exception_oop = oop(NULL));
1444   _exception_pc  = 0;
1445   _exception_handler_pc = 0;
1446   _is_method_handle_return = 0;
1447   _jvmti_thread_state= NULL;
1448   _should_post_on_exceptions_flag = JNI_FALSE;
1449   _jvmti_get_loaded_classes_closure = NULL;
1450   _interp_only_mode    = 0;
1451   _special_runtime_exit_condition = _no_async_condition;
1452   _pending_async_exception = NULL;
1453   _thread_stat = NULL;
1454   _thread_stat = new ThreadStatistics();
1455   _blocked_on_compilation = false;
1456   _jni_active_critical = 0;
1457   _pending_jni_exception_check_fn = NULL;
1458   _do_not_unlock_if_synchronized = false;
1459   _cached_monitor_info = NULL;
1460   _parker = Parker::Allocate(this);
1461 
1462 #ifndef PRODUCT
1463   _jmp_ring_index = 0;
1464   for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1465     record_jump(NULL, NULL, NULL, 0);
1466   }
1467 #endif // PRODUCT
1468 
1469   set_thread_profiler(NULL);
1470   if (FlatProfiler::is_active()) {
1471     // This is where we would decide to either give each thread it's own profiler
1472     // or use one global one from FlatProfiler,
1473     // or up to some count of the number of profiled threads, etc.
1474     ThreadProfiler* pp = new ThreadProfiler();
1475     pp->engage();
1476     set_thread_profiler(pp);
1477   }
1478 
1479   // Setup safepoint state info for this thread
1480   ThreadSafepointState::create(this);
1481 
1482   debug_only(_java_call_counter = 0);
1483 
1484   // JVMTI PopFrame support
1485   _popframe_condition = popframe_inactive;
1486   _popframe_preserved_args = NULL;
1487   _popframe_preserved_args_size = 0;
1488 
1489   pd_initialize();
1490 }
1491 
1492 #if INCLUDE_ALL_GCS
1493 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1494 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1495 #endif // INCLUDE_ALL_GCS
1496 
1497 JavaThread::JavaThread(bool is_attaching_via_jni) :
1498                        Thread()
1499 #if INCLUDE_ALL_GCS
1500                        , _satb_mark_queue(&_satb_mark_queue_set),
1501                        _dirty_card_queue(&_dirty_card_queue_set)
1502 #endif // INCLUDE_ALL_GCS
1503 {
1504   initialize();
1505   if (is_attaching_via_jni) {
1506     _jni_attach_state = _attaching_via_jni;
1507   } else {
1508     _jni_attach_state = _not_attaching_via_jni;
1509   }
1510   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1511 }
1512 
1513 bool JavaThread::reguard_stack(address cur_sp) {
1514   if (_stack_guard_state != stack_guard_yellow_disabled) {
1515     return true; // Stack already guarded or guard pages not needed.
1516   }
1517 
1518   if (register_stack_overflow()) {
1519     // For those architectures which have separate register and
1520     // memory stacks, we must check the register stack to see if
1521     // it has overflowed.
1522     return false;
1523   }
1524 
1525   // Java code never executes within the yellow zone: the latter is only
1526   // there to provoke an exception during stack banging.  If java code
1527   // is executing there, either StackShadowPages should be larger, or
1528   // some exception code in c1, c2 or the interpreter isn't unwinding
1529   // when it should.
1530   guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages");
1531 
1532   enable_stack_yellow_zone();
1533   return true;
1534 }
1535 
1536 bool JavaThread::reguard_stack(void) {
1537   return reguard_stack(os::current_stack_pointer());
1538 }
1539 
1540 
1541 void JavaThread::block_if_vm_exited() {
1542   if (_terminated == _vm_exited) {
1543     // _vm_exited is set at safepoint, and Threads_lock is never released
1544     // we will block here forever
1545     Threads_lock->lock_without_safepoint_check();
1546     ShouldNotReachHere();
1547   }
1548 }
1549 
1550 
1551 // Remove this ifdef when C1 is ported to the compiler interface.
1552 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1553 
1554 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1555                        Thread()
1556 #if INCLUDE_ALL_GCS
1557                        , _satb_mark_queue(&_satb_mark_queue_set),
1558                        _dirty_card_queue(&_dirty_card_queue_set)
1559 #endif // INCLUDE_ALL_GCS
1560 {
1561   if (TraceThreadEvents) {
1562     tty->print_cr("creating thread %p", this);
1563   }
1564   initialize();
1565   _jni_attach_state = _not_attaching_via_jni;
1566   set_entry_point(entry_point);
1567   // Create the native thread itself.
1568   // %note runtime_23
1569   os::ThreadType thr_type = os::java_thread;
1570   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1571                                                      os::java_thread;
1572   os::create_thread(this, thr_type, stack_sz);
1573   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1574   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1575   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1576   // the exception consists of creating the exception object & initializing it, initialization
1577   // will leave the VM via a JavaCall and then all locks must be unlocked).
1578   //
1579   // The thread is still suspended when we reach here. Thread must be explicit started
1580   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1581   // by calling Threads:add. The reason why this is not done here, is because the thread
1582   // object must be fully initialized (take a look at JVM_Start)
1583 }
1584 
1585 JavaThread::~JavaThread() {
1586   if (TraceThreadEvents) {
1587     tty->print_cr("terminate thread %p", this);
1588   }
1589 
1590   // JSR166 -- return the parker to the free list
1591   Parker::Release(_parker);
1592   _parker = NULL;
1593 
1594   // Free any remaining  previous UnrollBlock
1595   vframeArray* old_array = vframe_array_last();
1596 
1597   if (old_array != NULL) {
1598     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1599     old_array->set_unroll_block(NULL);
1600     delete old_info;
1601     delete old_array;
1602   }
1603 
1604   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1605   if (deferred != NULL) {
1606     // This can only happen if thread is destroyed before deoptimization occurs.
1607     assert(deferred->length() != 0, "empty array!");
1608     do {
1609       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1610       deferred->remove_at(0);
1611       // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1612       delete dlv;
1613     } while (deferred->length() != 0);
1614     delete deferred;
1615   }
1616 
1617   // All Java related clean up happens in exit
1618   ThreadSafepointState::destroy(this);
1619   if (_thread_profiler != NULL) delete _thread_profiler;
1620   if (_thread_stat != NULL) delete _thread_stat;
1621 }
1622 
1623 
1624 // The first routine called by a new Java thread
1625 void JavaThread::run() {
1626   // initialize thread-local alloc buffer related fields
1627   this->initialize_tlab();
1628 
1629   // used to test validity of stack trace backs
1630   this->record_base_of_stack_pointer();
1631 
1632   // Record real stack base and size.
1633   this->record_stack_base_and_size();
1634 
1635   // Initialize thread local storage; set before calling MutexLocker
1636   this->initialize_thread_local_storage();
1637 
1638   this->create_stack_guard_pages();
1639 
1640   this->cache_global_variables();
1641 
1642   // Thread is now sufficient initialized to be handled by the safepoint code as being
1643   // in the VM. Change thread state from _thread_new to _thread_in_vm
1644   ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1645 
1646   assert(JavaThread::current() == this, "sanity check");
1647   assert(!Thread::current()->owns_locks(), "sanity check");
1648 
1649   DTRACE_THREAD_PROBE(start, this);
1650 
1651   // This operation might block. We call that after all safepoint checks for a new thread has
1652   // been completed.
1653   this->set_active_handles(JNIHandleBlock::allocate_block());
1654 
1655   if (JvmtiExport::should_post_thread_life()) {
1656     JvmtiExport::post_thread_start(this);
1657   }
1658 
1659   EventThreadStart event;
1660   if (event.should_commit()) {
1661     event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj()));
1662     event.commit();
1663   }
1664 
1665   // We call another function to do the rest so we are sure that the stack addresses used
1666   // from there will be lower than the stack base just computed
1667   thread_main_inner();
1668 
1669   // Note, thread is no longer valid at this point!
1670 }
1671 
1672 
1673 void JavaThread::thread_main_inner() {
1674   assert(JavaThread::current() == this, "sanity check");
1675   assert(this->threadObj() != NULL, "just checking");
1676 
1677   // Execute thread entry point unless this thread has a pending exception
1678   // or has been stopped before starting.
1679   // Note: Due to JVM_StopThread we can have pending exceptions already!
1680   if (!this->has_pending_exception() &&
1681       !java_lang_Thread::is_stillborn(this->threadObj())) {
1682     {
1683       ResourceMark rm(this);
1684       this->set_native_thread_name(this->get_thread_name());
1685     }
1686     HandleMark hm(this);
1687     this->entry_point()(this, this);
1688   }
1689 
1690   DTRACE_THREAD_PROBE(stop, this);
1691 
1692   this->exit(false);
1693   delete this;
1694 }
1695 
1696 
1697 static void ensure_join(JavaThread* thread) {
1698   // We do not need to grap the Threads_lock, since we are operating on ourself.
1699   Handle threadObj(thread, thread->threadObj());
1700   assert(threadObj.not_null(), "java thread object must exist");
1701   ObjectLocker lock(threadObj, thread);
1702   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1703   thread->clear_pending_exception();
1704   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1705   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1706   // Clear the native thread instance - this makes isAlive return false and allows the join()
1707   // to complete once we've done the notify_all below
1708   java_lang_Thread::set_thread(threadObj(), NULL);
1709   lock.notify_all(thread);
1710   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1711   thread->clear_pending_exception();
1712 }
1713 
1714 
1715 // For any new cleanup additions, please check to see if they need to be applied to
1716 // cleanup_failed_attach_current_thread as well.
1717 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1718   assert(this == JavaThread::current(), "thread consistency check");
1719 
1720   HandleMark hm(this);
1721   Handle uncaught_exception(this, this->pending_exception());
1722   this->clear_pending_exception();
1723   Handle threadObj(this, this->threadObj());
1724   assert(threadObj.not_null(), "Java thread object should be created");
1725 
1726   if (get_thread_profiler() != NULL) {
1727     get_thread_profiler()->disengage();
1728     ResourceMark rm;
1729     get_thread_profiler()->print(get_thread_name());
1730   }
1731 
1732 
1733   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1734   {
1735     EXCEPTION_MARK;
1736 
1737     CLEAR_PENDING_EXCEPTION;
1738   }
1739   if (!destroy_vm) {
1740     if (uncaught_exception.not_null()) {
1741       EXCEPTION_MARK;
1742       // Call method Thread.dispatchUncaughtException().
1743       KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1744       JavaValue result(T_VOID);
1745       JavaCalls::call_virtual(&result,
1746                               threadObj, thread_klass,
1747                               vmSymbols::dispatchUncaughtException_name(),
1748                               vmSymbols::throwable_void_signature(),
1749                               uncaught_exception,
1750                               THREAD);
1751       if (HAS_PENDING_EXCEPTION) {
1752         ResourceMark rm(this);
1753         jio_fprintf(defaultStream::error_stream(),
1754                     "\nException: %s thrown from the UncaughtExceptionHandler"
1755                     " in thread \"%s\"\n",
1756                     pending_exception()->klass()->external_name(),
1757                     get_thread_name());
1758         CLEAR_PENDING_EXCEPTION;
1759       }
1760     }
1761 
1762     // Called before the java thread exit since we want to read info
1763     // from java_lang_Thread object
1764     EventThreadEnd event;
1765     if (event.should_commit()) {
1766       event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj()));
1767       event.commit();
1768     }
1769 
1770     // Call after last event on thread
1771     EVENT_THREAD_EXIT(this);
1772 
1773     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1774     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1775     // is deprecated anyhow.
1776     if (!is_Compiler_thread()) {
1777       int count = 3;
1778       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1779         EXCEPTION_MARK;
1780         JavaValue result(T_VOID);
1781         KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1782         JavaCalls::call_virtual(&result,
1783                                 threadObj, thread_klass,
1784                                 vmSymbols::exit_method_name(),
1785                                 vmSymbols::void_method_signature(),
1786                                 THREAD);
1787         CLEAR_PENDING_EXCEPTION;
1788       }
1789     }
1790     // notify JVMTI
1791     if (JvmtiExport::should_post_thread_life()) {
1792       JvmtiExport::post_thread_end(this);
1793     }
1794 
1795     // We have notified the agents that we are exiting, before we go on,
1796     // we must check for a pending external suspend request and honor it
1797     // in order to not surprise the thread that made the suspend request.
1798     while (true) {
1799       {
1800         MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1801         if (!is_external_suspend()) {
1802           set_terminated(_thread_exiting);
1803           ThreadService::current_thread_exiting(this);
1804           break;
1805         }
1806         // Implied else:
1807         // Things get a little tricky here. We have a pending external
1808         // suspend request, but we are holding the SR_lock so we
1809         // can't just self-suspend. So we temporarily drop the lock
1810         // and then self-suspend.
1811       }
1812 
1813       ThreadBlockInVM tbivm(this);
1814       java_suspend_self();
1815 
1816       // We're done with this suspend request, but we have to loop around
1817       // and check again. Eventually we will get SR_lock without a pending
1818       // external suspend request and will be able to mark ourselves as
1819       // exiting.
1820     }
1821     // no more external suspends are allowed at this point
1822   } else {
1823     // before_exit() has already posted JVMTI THREAD_END events
1824   }
1825 
1826   // Notify waiters on thread object. This has to be done after exit() is called
1827   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1828   // group should have the destroyed bit set before waiters are notified).
1829   ensure_join(this);
1830   assert(!this->has_pending_exception(), "ensure_join should have cleared");
1831 
1832   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1833   // held by this thread must be released.  A detach operation must only
1834   // get here if there are no Java frames on the stack.  Therefore, any
1835   // owned monitors at this point MUST be JNI-acquired monitors which are
1836   // pre-inflated and in the monitor cache.
1837   //
1838   // ensure_join() ignores IllegalThreadStateExceptions, and so does this.
1839   if (exit_type == jni_detach && JNIDetachReleasesMonitors) {
1840     assert(!this->has_last_Java_frame(), "detaching with Java frames?");
1841     ObjectSynchronizer::release_monitors_owned_by_thread(this);
1842     assert(!this->has_pending_exception(), "release_monitors should have cleared");
1843   }
1844 
1845   // These things needs to be done while we are still a Java Thread. Make sure that thread
1846   // is in a consistent state, in case GC happens
1847   assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1848 
1849   if (active_handles() != NULL) {
1850     JNIHandleBlock* block = active_handles();
1851     set_active_handles(NULL);
1852     JNIHandleBlock::release_block(block);
1853   }
1854 
1855   if (free_handle_block() != NULL) {
1856     JNIHandleBlock* block = free_handle_block();
1857     set_free_handle_block(NULL);
1858     JNIHandleBlock::release_block(block);
1859   }
1860 
1861   // These have to be removed while this is still a valid thread.
1862   remove_stack_guard_pages();
1863 
1864   if (UseTLAB) {
1865     tlab().make_parsable(true);  // retire TLAB
1866   }
1867 
1868   if (JvmtiEnv::environments_might_exist()) {
1869     JvmtiExport::cleanup_thread(this);
1870   }
1871 
1872   // We must flush any deferred card marks before removing a thread from
1873   // the list of active threads.
1874   Universe::heap()->flush_deferred_store_barrier(this);
1875   assert(deferred_card_mark().is_empty(), "Should have been flushed");
1876 
1877 #if INCLUDE_ALL_GCS
1878   // We must flush the G1-related buffers before removing a thread
1879   // from the list of active threads. We must do this after any deferred
1880   // card marks have been flushed (above) so that any entries that are
1881   // added to the thread's dirty card queue as a result are not lost.
1882   if (UseG1GC) {
1883     flush_barrier_queues();
1884   }
1885 #endif // INCLUDE_ALL_GCS
1886 
1887   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1888   Threads::remove(this);
1889 }
1890 
1891 #if INCLUDE_ALL_GCS
1892 // Flush G1-related queues.
1893 void JavaThread::flush_barrier_queues() {
1894   satb_mark_queue().flush();
1895   dirty_card_queue().flush();
1896 }
1897 
1898 void JavaThread::initialize_queues() {
1899   assert(!SafepointSynchronize::is_at_safepoint(),
1900          "we should not be at a safepoint");
1901 
1902   ObjPtrQueue& satb_queue = satb_mark_queue();
1903   SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1904   // The SATB queue should have been constructed with its active
1905   // field set to false.
1906   assert(!satb_queue.is_active(), "SATB queue should not be active");
1907   assert(satb_queue.is_empty(), "SATB queue should be empty");
1908   // If we are creating the thread during a marking cycle, we should
1909   // set the active field of the SATB queue to true.
1910   if (satb_queue_set.is_active()) {
1911     satb_queue.set_active(true);
1912   }
1913 
1914   DirtyCardQueue& dirty_queue = dirty_card_queue();
1915   // The dirty card queue should have been constructed with its
1916   // active field set to true.
1917   assert(dirty_queue.is_active(), "dirty card queue should be active");
1918 }
1919 #endif // INCLUDE_ALL_GCS
1920 
1921 void JavaThread::cleanup_failed_attach_current_thread() {
1922   if (get_thread_profiler() != NULL) {
1923     get_thread_profiler()->disengage();
1924     ResourceMark rm;
1925     get_thread_profiler()->print(get_thread_name());
1926   }
1927 
1928   if (active_handles() != NULL) {
1929     JNIHandleBlock* block = active_handles();
1930     set_active_handles(NULL);
1931     JNIHandleBlock::release_block(block);
1932   }
1933 
1934   if (free_handle_block() != NULL) {
1935     JNIHandleBlock* block = free_handle_block();
1936     set_free_handle_block(NULL);
1937     JNIHandleBlock::release_block(block);
1938   }
1939 
1940   // These have to be removed while this is still a valid thread.
1941   remove_stack_guard_pages();
1942 
1943   if (UseTLAB) {
1944     tlab().make_parsable(true);  // retire TLAB, if any
1945   }
1946 
1947 #if INCLUDE_ALL_GCS
1948   if (UseG1GC) {
1949     flush_barrier_queues();
1950   }
1951 #endif // INCLUDE_ALL_GCS
1952 
1953   Threads::remove(this);
1954   delete this;
1955 }
1956 
1957 
1958 
1959 
1960 JavaThread* JavaThread::active() {
1961   Thread* thread = ThreadLocalStorage::thread();
1962   assert(thread != NULL, "just checking");
1963   if (thread->is_Java_thread()) {
1964     return (JavaThread*) thread;
1965   } else {
1966     assert(thread->is_VM_thread(), "this must be a vm thread");
1967     VM_Operation* op = ((VMThread*) thread)->vm_operation();
1968     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
1969     assert(ret->is_Java_thread(), "must be a Java thread");
1970     return ret;
1971   }
1972 }
1973 
1974 bool JavaThread::is_lock_owned(address adr) const {
1975   if (Thread::is_lock_owned(adr)) return true;
1976 
1977   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
1978     if (chunk->contains(adr)) return true;
1979   }
1980 
1981   return false;
1982 }
1983 
1984 
1985 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
1986   chunk->set_next(monitor_chunks());
1987   set_monitor_chunks(chunk);
1988 }
1989 
1990 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
1991   guarantee(monitor_chunks() != NULL, "must be non empty");
1992   if (monitor_chunks() == chunk) {
1993     set_monitor_chunks(chunk->next());
1994   } else {
1995     MonitorChunk* prev = monitor_chunks();
1996     while (prev->next() != chunk) prev = prev->next();
1997     prev->set_next(chunk->next());
1998   }
1999 }
2000 
2001 // JVM support.
2002 
2003 // Note: this function shouldn't block if it's called in
2004 // _thread_in_native_trans state (such as from
2005 // check_special_condition_for_native_trans()).
2006 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2007 
2008   if (has_last_Java_frame() && has_async_condition()) {
2009     // If we are at a polling page safepoint (not a poll return)
2010     // then we must defer async exception because live registers
2011     // will be clobbered by the exception path. Poll return is
2012     // ok because the call we a returning from already collides
2013     // with exception handling registers and so there is no issue.
2014     // (The exception handling path kills call result registers but
2015     //  this is ok since the exception kills the result anyway).
2016 
2017     if (is_at_poll_safepoint()) {
2018       // if the code we are returning to has deoptimized we must defer
2019       // the exception otherwise live registers get clobbered on the
2020       // exception path before deoptimization is able to retrieve them.
2021       //
2022       RegisterMap map(this, false);
2023       frame caller_fr = last_frame().sender(&map);
2024       assert(caller_fr.is_compiled_frame(), "what?");
2025       if (caller_fr.is_deoptimized_frame()) {
2026         if (TraceExceptions) {
2027           ResourceMark rm;
2028           tty->print_cr("deferred async exception at compiled safepoint");
2029         }
2030         return;
2031       }
2032     }
2033   }
2034 
2035   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2036   if (condition == _no_async_condition) {
2037     // Conditions have changed since has_special_runtime_exit_condition()
2038     // was called:
2039     // - if we were here only because of an external suspend request,
2040     //   then that was taken care of above (or cancelled) so we are done
2041     // - if we were here because of another async request, then it has
2042     //   been cleared between the has_special_runtime_exit_condition()
2043     //   and now so again we are done
2044     return;
2045   }
2046 
2047   // Check for pending async. exception
2048   if (_pending_async_exception != NULL) {
2049     // Only overwrite an already pending exception, if it is not a threadDeath.
2050     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2051 
2052       // We cannot call Exceptions::_throw(...) here because we cannot block
2053       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2054 
2055       if (TraceExceptions) {
2056         ResourceMark rm;
2057         tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this);
2058         if (has_last_Java_frame()) {
2059           frame f = last_frame();
2060           tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp());
2061         }
2062         tty->print_cr(" of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2063       }
2064       _pending_async_exception = NULL;
2065       clear_has_async_exception();
2066     }
2067   }
2068 
2069   if (check_unsafe_error &&
2070       condition == _async_unsafe_access_error && !has_pending_exception()) {
2071     condition = _no_async_condition;  // done
2072     switch (thread_state()) {
2073     case _thread_in_vm: {
2074       JavaThread* THREAD = this;
2075       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2076     }
2077     case _thread_in_native: {
2078       ThreadInVMfromNative tiv(this);
2079       JavaThread* THREAD = this;
2080       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2081     }
2082     case _thread_in_Java: {
2083       ThreadInVMfromJava tiv(this);
2084       JavaThread* THREAD = this;
2085       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2086     }
2087     default:
2088       ShouldNotReachHere();
2089     }
2090   }
2091 
2092   assert(condition == _no_async_condition || has_pending_exception() ||
2093          (!check_unsafe_error && condition == _async_unsafe_access_error),
2094          "must have handled the async condition, if no exception");
2095 }
2096 
2097 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2098   //
2099   // Check for pending external suspend. Internal suspend requests do
2100   // not use handle_special_runtime_exit_condition().
2101   // If JNIEnv proxies are allowed, don't self-suspend if the target
2102   // thread is not the current thread. In older versions of jdbx, jdbx
2103   // threads could call into the VM with another thread's JNIEnv so we
2104   // can be here operating on behalf of a suspended thread (4432884).
2105   bool do_self_suspend = is_external_suspend_with_lock();
2106   if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2107     //
2108     // Because thread is external suspended the safepoint code will count
2109     // thread as at a safepoint. This can be odd because we can be here
2110     // as _thread_in_Java which would normally transition to _thread_blocked
2111     // at a safepoint. We would like to mark the thread as _thread_blocked
2112     // before calling java_suspend_self like all other callers of it but
2113     // we must then observe proper safepoint protocol. (We can't leave
2114     // _thread_blocked with a safepoint in progress). However we can be
2115     // here as _thread_in_native_trans so we can't use a normal transition
2116     // constructor/destructor pair because they assert on that type of
2117     // transition. We could do something like:
2118     //
2119     // JavaThreadState state = thread_state();
2120     // set_thread_state(_thread_in_vm);
2121     // {
2122     //   ThreadBlockInVM tbivm(this);
2123     //   java_suspend_self()
2124     // }
2125     // set_thread_state(_thread_in_vm_trans);
2126     // if (safepoint) block;
2127     // set_thread_state(state);
2128     //
2129     // but that is pretty messy. Instead we just go with the way the
2130     // code has worked before and note that this is the only path to
2131     // java_suspend_self that doesn't put the thread in _thread_blocked
2132     // mode.
2133 
2134     frame_anchor()->make_walkable(this);
2135     java_suspend_self();
2136 
2137     // We might be here for reasons in addition to the self-suspend request
2138     // so check for other async requests.
2139   }
2140 
2141   if (check_asyncs) {
2142     check_and_handle_async_exceptions();
2143   }
2144 }
2145 
2146 void JavaThread::send_thread_stop(oop java_throwable)  {
2147   assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2148   assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2149   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2150 
2151   // Do not throw asynchronous exceptions against the compiler thread
2152   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2153   if (is_Compiler_thread()) return;
2154 
2155   {
2156     // Actually throw the Throwable against the target Thread - however
2157     // only if there is no thread death exception installed already.
2158     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2159       // If the topmost frame is a runtime stub, then we are calling into
2160       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2161       // must deoptimize the caller before continuing, as the compiled  exception handler table
2162       // may not be valid
2163       if (has_last_Java_frame()) {
2164         frame f = last_frame();
2165         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2166           // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2167           RegisterMap reg_map(this, UseBiasedLocking);
2168           frame compiled_frame = f.sender(&reg_map);
2169           if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2170             Deoptimization::deoptimize(this, compiled_frame, &reg_map);
2171           }
2172         }
2173       }
2174 
2175       // Set async. pending exception in thread.
2176       set_pending_async_exception(java_throwable);
2177 
2178       if (TraceExceptions) {
2179         ResourceMark rm;
2180         tty->print_cr("Pending Async. exception installed of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2181       }
2182       // for AbortVMOnException flag
2183       NOT_PRODUCT(Exceptions::debug_check_abort(InstanceKlass::cast(_pending_async_exception->klass())->external_name()));
2184     }
2185   }
2186 
2187 
2188   // Interrupt thread so it will wake up from a potential wait()
2189   Thread::interrupt(this);
2190 }
2191 
2192 // External suspension mechanism.
2193 //
2194 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2195 // to any VM_locks and it is at a transition
2196 // Self-suspension will happen on the transition out of the vm.
2197 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2198 //
2199 // Guarantees on return:
2200 //   + Target thread will not execute any new bytecode (that's why we need to
2201 //     force a safepoint)
2202 //   + Target thread will not enter any new monitors
2203 //
2204 void JavaThread::java_suspend() {
2205   { MutexLocker mu(Threads_lock);
2206     if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2207       return;
2208     }
2209   }
2210 
2211   { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2212     if (!is_external_suspend()) {
2213       // a racing resume has cancelled us; bail out now
2214       return;
2215     }
2216 
2217     // suspend is done
2218     uint32_t debug_bits = 0;
2219     // Warning: is_ext_suspend_completed() may temporarily drop the
2220     // SR_lock to allow the thread to reach a stable thread state if
2221     // it is currently in a transient thread state.
2222     if (is_ext_suspend_completed(false /* !called_by_wait */,
2223                                  SuspendRetryDelay, &debug_bits)) {
2224       return;
2225     }
2226   }
2227 
2228   VM_ForceSafepoint vm_suspend;
2229   VMThread::execute(&vm_suspend);
2230 }
2231 
2232 // Part II of external suspension.
2233 // A JavaThread self suspends when it detects a pending external suspend
2234 // request. This is usually on transitions. It is also done in places
2235 // where continuing to the next transition would surprise the caller,
2236 // e.g., monitor entry.
2237 //
2238 // Returns the number of times that the thread self-suspended.
2239 //
2240 // Note: DO NOT call java_suspend_self() when you just want to block current
2241 //       thread. java_suspend_self() is the second stage of cooperative
2242 //       suspension for external suspend requests and should only be used
2243 //       to complete an external suspend request.
2244 //
2245 int JavaThread::java_suspend_self() {
2246   int ret = 0;
2247 
2248   // we are in the process of exiting so don't suspend
2249   if (is_exiting()) {
2250     clear_external_suspend();
2251     return ret;
2252   }
2253 
2254   assert(_anchor.walkable() ||
2255          (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2256          "must have walkable stack");
2257 
2258   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2259 
2260   assert(!this->is_ext_suspended(),
2261          "a thread trying to self-suspend should not already be suspended");
2262 
2263   if (this->is_suspend_equivalent()) {
2264     // If we are self-suspending as a result of the lifting of a
2265     // suspend equivalent condition, then the suspend_equivalent
2266     // flag is not cleared until we set the ext_suspended flag so
2267     // that wait_for_ext_suspend_completion() returns consistent
2268     // results.
2269     this->clear_suspend_equivalent();
2270   }
2271 
2272   // A racing resume may have cancelled us before we grabbed SR_lock
2273   // above. Or another external suspend request could be waiting for us
2274   // by the time we return from SR_lock()->wait(). The thread
2275   // that requested the suspension may already be trying to walk our
2276   // stack and if we return now, we can change the stack out from under
2277   // it. This would be a "bad thing (TM)" and cause the stack walker
2278   // to crash. We stay self-suspended until there are no more pending
2279   // external suspend requests.
2280   while (is_external_suspend()) {
2281     ret++;
2282     this->set_ext_suspended();
2283 
2284     // _ext_suspended flag is cleared by java_resume()
2285     while (is_ext_suspended()) {
2286       this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2287     }
2288   }
2289 
2290   return ret;
2291 }
2292 
2293 #ifdef ASSERT
2294 // verify the JavaThread has not yet been published in the Threads::list, and
2295 // hence doesn't need protection from concurrent access at this stage
2296 void JavaThread::verify_not_published() {
2297   if (!Threads_lock->owned_by_self()) {
2298     MutexLockerEx ml(Threads_lock,  Mutex::_no_safepoint_check_flag);
2299     assert(!Threads::includes(this),
2300            "java thread shouldn't have been published yet!");
2301   } else {
2302     assert(!Threads::includes(this),
2303            "java thread shouldn't have been published yet!");
2304   }
2305 }
2306 #endif
2307 
2308 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2309 // progress or when _suspend_flags is non-zero.
2310 // Current thread needs to self-suspend if there is a suspend request and/or
2311 // block if a safepoint is in progress.
2312 // Async exception ISN'T checked.
2313 // Note only the ThreadInVMfromNative transition can call this function
2314 // directly and when thread state is _thread_in_native_trans
2315 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2316   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2317 
2318   JavaThread *curJT = JavaThread::current();
2319   bool do_self_suspend = thread->is_external_suspend();
2320 
2321   assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2322 
2323   // If JNIEnv proxies are allowed, don't self-suspend if the target
2324   // thread is not the current thread. In older versions of jdbx, jdbx
2325   // threads could call into the VM with another thread's JNIEnv so we
2326   // can be here operating on behalf of a suspended thread (4432884).
2327   if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2328     JavaThreadState state = thread->thread_state();
2329 
2330     // We mark this thread_blocked state as a suspend-equivalent so
2331     // that a caller to is_ext_suspend_completed() won't be confused.
2332     // The suspend-equivalent state is cleared by java_suspend_self().
2333     thread->set_suspend_equivalent();
2334 
2335     // If the safepoint code sees the _thread_in_native_trans state, it will
2336     // wait until the thread changes to other thread state. There is no
2337     // guarantee on how soon we can obtain the SR_lock and complete the
2338     // self-suspend request. It would be a bad idea to let safepoint wait for
2339     // too long. Temporarily change the state to _thread_blocked to
2340     // let the VM thread know that this thread is ready for GC. The problem
2341     // of changing thread state is that safepoint could happen just after
2342     // java_suspend_self() returns after being resumed, and VM thread will
2343     // see the _thread_blocked state. We must check for safepoint
2344     // after restoring the state and make sure we won't leave while a safepoint
2345     // is in progress.
2346     thread->set_thread_state(_thread_blocked);
2347     thread->java_suspend_self();
2348     thread->set_thread_state(state);
2349     // Make sure new state is seen by VM thread
2350     if (os::is_MP()) {
2351       if (UseMembar) {
2352         // Force a fence between the write above and read below
2353         OrderAccess::fence();
2354       } else {
2355         // Must use this rather than serialization page in particular on Windows
2356         InterfaceSupport::serialize_memory(thread);
2357       }
2358     }
2359   }
2360 
2361   if (SafepointSynchronize::do_call_back()) {
2362     // If we are safepointing, then block the caller which may not be
2363     // the same as the target thread (see above).
2364     SafepointSynchronize::block(curJT);
2365   }
2366 
2367   if (thread->is_deopt_suspend()) {
2368     thread->clear_deopt_suspend();
2369     RegisterMap map(thread, false);
2370     frame f = thread->last_frame();
2371     while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2372       f = f.sender(&map);
2373     }
2374     if (f.id() == thread->must_deopt_id()) {
2375       thread->clear_must_deopt_id();
2376       f.deoptimize(thread);
2377     } else {
2378       fatal("missed deoptimization!");
2379     }
2380   }
2381 }
2382 
2383 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2384 // progress or when _suspend_flags is non-zero.
2385 // Current thread needs to self-suspend if there is a suspend request and/or
2386 // block if a safepoint is in progress.
2387 // Also check for pending async exception (not including unsafe access error).
2388 // Note only the native==>VM/Java barriers can call this function and when
2389 // thread state is _thread_in_native_trans.
2390 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2391   check_safepoint_and_suspend_for_native_trans(thread);
2392 
2393   if (thread->has_async_exception()) {
2394     // We are in _thread_in_native_trans state, don't handle unsafe
2395     // access error since that may block.
2396     thread->check_and_handle_async_exceptions(false);
2397   }
2398 }
2399 
2400 // This is a variant of the normal
2401 // check_special_condition_for_native_trans with slightly different
2402 // semantics for use by critical native wrappers.  It does all the
2403 // normal checks but also performs the transition back into
2404 // thread_in_Java state.  This is required so that critical natives
2405 // can potentially block and perform a GC if they are the last thread
2406 // exiting the GC_locker.
2407 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2408   check_special_condition_for_native_trans(thread);
2409 
2410   // Finish the transition
2411   thread->set_thread_state(_thread_in_Java);
2412 
2413   if (thread->do_critical_native_unlock()) {
2414     ThreadInVMfromJavaNoAsyncException tiv(thread);
2415     GC_locker::unlock_critical(thread);
2416     thread->clear_critical_native_unlock();
2417   }
2418 }
2419 
2420 // We need to guarantee the Threads_lock here, since resumes are not
2421 // allowed during safepoint synchronization
2422 // Can only resume from an external suspension
2423 void JavaThread::java_resume() {
2424   assert_locked_or_safepoint(Threads_lock);
2425 
2426   // Sanity check: thread is gone, has started exiting or the thread
2427   // was not externally suspended.
2428   if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2429     return;
2430   }
2431 
2432   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2433 
2434   clear_external_suspend();
2435 
2436   if (is_ext_suspended()) {
2437     clear_ext_suspended();
2438     SR_lock()->notify_all();
2439   }
2440 }
2441 
2442 void JavaThread::create_stack_guard_pages() {
2443   if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return;
2444   address low_addr = stack_base() - stack_size();
2445   size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2446 
2447   int allocate = os::allocate_stack_guard_pages();
2448   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2449 
2450   if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) {
2451     warning("Attempt to allocate stack guard pages failed.");
2452     return;
2453   }
2454 
2455   if (os::guard_memory((char *) low_addr, len)) {
2456     _stack_guard_state = stack_guard_enabled;
2457   } else {
2458     warning("Attempt to protect stack guard pages failed.");
2459     if (os::uncommit_memory((char *) low_addr, len)) {
2460       warning("Attempt to deallocate stack guard pages failed.");
2461     }
2462   }
2463 }
2464 
2465 void JavaThread::remove_stack_guard_pages() {
2466   assert(Thread::current() == this, "from different thread");
2467   if (_stack_guard_state == stack_guard_unused) return;
2468   address low_addr = stack_base() - stack_size();
2469   size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2470 
2471   if (os::allocate_stack_guard_pages()) {
2472     if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2473       _stack_guard_state = stack_guard_unused;
2474     } else {
2475       warning("Attempt to deallocate stack guard pages failed.");
2476     }
2477   } else {
2478     if (_stack_guard_state == stack_guard_unused) return;
2479     if (os::unguard_memory((char *) low_addr, len)) {
2480       _stack_guard_state = stack_guard_unused;
2481     } else {
2482       warning("Attempt to unprotect stack guard pages failed.");
2483     }
2484   }
2485 }
2486 
2487 void JavaThread::enable_stack_yellow_zone() {
2488   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2489   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2490 
2491   // The base notation is from the stacks point of view, growing downward.
2492   // We need to adjust it to work correctly with guard_memory()
2493   address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2494 
2495   guarantee(base < stack_base(), "Error calculating stack yellow zone");
2496   guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2497 
2498   if (os::guard_memory((char *) base, stack_yellow_zone_size())) {
2499     _stack_guard_state = stack_guard_enabled;
2500   } else {
2501     warning("Attempt to guard stack yellow zone failed.");
2502   }
2503   enable_register_stack_guard();
2504 }
2505 
2506 void JavaThread::disable_stack_yellow_zone() {
2507   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2508   assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled");
2509 
2510   // Simply return if called for a thread that does not use guard pages.
2511   if (_stack_guard_state == stack_guard_unused) return;
2512 
2513   // The base notation is from the stacks point of view, growing downward.
2514   // We need to adjust it to work correctly with guard_memory()
2515   address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2516 
2517   if (os::unguard_memory((char *)base, stack_yellow_zone_size())) {
2518     _stack_guard_state = stack_guard_yellow_disabled;
2519   } else {
2520     warning("Attempt to unguard stack yellow zone failed.");
2521   }
2522   disable_register_stack_guard();
2523 }
2524 
2525 void JavaThread::enable_stack_red_zone() {
2526   // The base notation is from the stacks point of view, growing downward.
2527   // We need to adjust it to work correctly with guard_memory()
2528   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2529   address base = stack_red_zone_base() - stack_red_zone_size();
2530 
2531   guarantee(base < stack_base(), "Error calculating stack red zone");
2532   guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2533 
2534   if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2535     warning("Attempt to guard stack red zone failed.");
2536   }
2537 }
2538 
2539 void JavaThread::disable_stack_red_zone() {
2540   // The base notation is from the stacks point of view, growing downward.
2541   // We need to adjust it to work correctly with guard_memory()
2542   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2543   address base = stack_red_zone_base() - stack_red_zone_size();
2544   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2545     warning("Attempt to unguard stack red zone failed.");
2546   }
2547 }
2548 
2549 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2550   // ignore is there is no stack
2551   if (!has_last_Java_frame()) return;
2552   // traverse the stack frames. Starts from top frame.
2553   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2554     frame* fr = fst.current();
2555     f(fr, fst.register_map());
2556   }
2557 }
2558 
2559 
2560 #ifndef PRODUCT
2561 // Deoptimization
2562 // Function for testing deoptimization
2563 void JavaThread::deoptimize() {
2564   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2565   StackFrameStream fst(this, UseBiasedLocking);
2566   bool deopt = false;           // Dump stack only if a deopt actually happens.
2567   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2568   // Iterate over all frames in the thread and deoptimize
2569   for (; !fst.is_done(); fst.next()) {
2570     if (fst.current()->can_be_deoptimized()) {
2571 
2572       if (only_at) {
2573         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
2574         // consists of comma or carriage return separated numbers so
2575         // search for the current bci in that string.
2576         address pc = fst.current()->pc();
2577         nmethod* nm =  (nmethod*) fst.current()->cb();
2578         ScopeDesc* sd = nm->scope_desc_at(pc);
2579         char buffer[8];
2580         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2581         size_t len = strlen(buffer);
2582         const char * found = strstr(DeoptimizeOnlyAt, buffer);
2583         while (found != NULL) {
2584           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2585               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2586             // Check that the bci found is bracketed by terminators.
2587             break;
2588           }
2589           found = strstr(found + 1, buffer);
2590         }
2591         if (!found) {
2592           continue;
2593         }
2594       }
2595 
2596       if (DebugDeoptimization && !deopt) {
2597         deopt = true; // One-time only print before deopt
2598         tty->print_cr("[BEFORE Deoptimization]");
2599         trace_frames();
2600         trace_stack();
2601       }
2602       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2603     }
2604   }
2605 
2606   if (DebugDeoptimization && deopt) {
2607     tty->print_cr("[AFTER Deoptimization]");
2608     trace_frames();
2609   }
2610 }
2611 
2612 
2613 // Make zombies
2614 void JavaThread::make_zombies() {
2615   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2616     if (fst.current()->can_be_deoptimized()) {
2617       // it is a Java nmethod
2618       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2619       nm->make_not_entrant();
2620     }
2621   }
2622 }
2623 #endif // PRODUCT
2624 
2625 
2626 void JavaThread::deoptimized_wrt_marked_nmethods() {
2627   if (!has_last_Java_frame()) return;
2628   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2629   StackFrameStream fst(this, UseBiasedLocking);
2630   for (; !fst.is_done(); fst.next()) {
2631     if (fst.current()->should_be_deoptimized()) {
2632       if (LogCompilation && xtty != NULL) {
2633         nmethod* nm = fst.current()->cb()->as_nmethod_or_null();
2634         xtty->elem("deoptimized thread='" UINTX_FORMAT "' compile_id='%d'",
2635                    this->name(), nm != NULL ? nm->compile_id() : -1);
2636       }
2637 
2638       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2639     }
2640   }
2641 }
2642 
2643 
2644 // If the caller is a NamedThread, then remember, in the current scope,
2645 // the given JavaThread in its _processed_thread field.
2646 class RememberProcessedThread: public StackObj {
2647   NamedThread* _cur_thr;
2648  public:
2649   RememberProcessedThread(JavaThread* jthr) {
2650     Thread* thread = Thread::current();
2651     if (thread->is_Named_thread()) {
2652       _cur_thr = (NamedThread *)thread;
2653       _cur_thr->set_processed_thread(jthr);
2654     } else {
2655       _cur_thr = NULL;
2656     }
2657   }
2658 
2659   ~RememberProcessedThread() {
2660     if (_cur_thr) {
2661       _cur_thr->set_processed_thread(NULL);
2662     }
2663   }
2664 };
2665 
2666 void JavaThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
2667   // Verify that the deferred card marks have been flushed.
2668   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2669 
2670   // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2671   // since there may be more than one thread using each ThreadProfiler.
2672 
2673   // Traverse the GCHandles
2674   Thread::oops_do(f, cld_f, cf);
2675 
2676   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2677          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2678 
2679   if (has_last_Java_frame()) {
2680     // Record JavaThread to GC thread
2681     RememberProcessedThread rpt(this);
2682 
2683     // Traverse the privileged stack
2684     if (_privileged_stack_top != NULL) {
2685       _privileged_stack_top->oops_do(f);
2686     }
2687 
2688     // traverse the registered growable array
2689     if (_array_for_gc != NULL) {
2690       for (int index = 0; index < _array_for_gc->length(); index++) {
2691         f->do_oop(_array_for_gc->adr_at(index));
2692       }
2693     }
2694 
2695     // Traverse the monitor chunks
2696     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2697       chunk->oops_do(f);
2698     }
2699 
2700     // Traverse the execution stack
2701     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2702       fst.current()->oops_do(f, cld_f, cf, fst.register_map());
2703     }
2704   }
2705 
2706   // callee_target is never live across a gc point so NULL it here should
2707   // it still contain a methdOop.
2708 
2709   set_callee_target(NULL);
2710 
2711   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2712   // If we have deferred set_locals there might be oops waiting to be
2713   // written
2714   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2715   if (list != NULL) {
2716     for (int i = 0; i < list->length(); i++) {
2717       list->at(i)->oops_do(f);
2718     }
2719   }
2720 
2721   // Traverse instance variables at the end since the GC may be moving things
2722   // around using this function
2723   f->do_oop((oop*) &_threadObj);
2724   f->do_oop((oop*) &_vm_result);
2725   f->do_oop((oop*) &_exception_oop);
2726   f->do_oop((oop*) &_pending_async_exception);
2727 
2728   if (jvmti_thread_state() != NULL) {
2729     jvmti_thread_state()->oops_do(f);
2730   }
2731 }
2732 
2733 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2734   Thread::nmethods_do(cf);  // (super method is a no-op)
2735 
2736   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2737          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2738 
2739   if (has_last_Java_frame()) {
2740     // Traverse the execution stack
2741     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2742       fst.current()->nmethods_do(cf);
2743     }
2744   }
2745 }
2746 
2747 void JavaThread::metadata_do(void f(Metadata*)) {
2748   Thread::metadata_do(f);
2749   if (has_last_Java_frame()) {
2750     // Traverse the execution stack to call f() on the methods in the stack
2751     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2752       fst.current()->metadata_do(f);
2753     }
2754   } else if (is_Compiler_thread()) {
2755     // need to walk ciMetadata in current compile tasks to keep alive.
2756     CompilerThread* ct = (CompilerThread*)this;
2757     if (ct->env() != NULL) {
2758       ct->env()->metadata_do(f);
2759     }
2760   }
2761 }
2762 
2763 // Printing
2764 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2765   switch (_thread_state) {
2766   case _thread_uninitialized:     return "_thread_uninitialized";
2767   case _thread_new:               return "_thread_new";
2768   case _thread_new_trans:         return "_thread_new_trans";
2769   case _thread_in_native:         return "_thread_in_native";
2770   case _thread_in_native_trans:   return "_thread_in_native_trans";
2771   case _thread_in_vm:             return "_thread_in_vm";
2772   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
2773   case _thread_in_Java:           return "_thread_in_Java";
2774   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
2775   case _thread_blocked:           return "_thread_blocked";
2776   case _thread_blocked_trans:     return "_thread_blocked_trans";
2777   default:                        return "unknown thread state";
2778   }
2779 }
2780 
2781 #ifndef PRODUCT
2782 void JavaThread::print_thread_state_on(outputStream *st) const {
2783   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
2784 };
2785 void JavaThread::print_thread_state() const {
2786   print_thread_state_on(tty);
2787 }
2788 #endif // PRODUCT
2789 
2790 // Called by Threads::print() for VM_PrintThreads operation
2791 void JavaThread::print_on(outputStream *st) const {
2792   st->print("\"%s\" ", get_thread_name());
2793   oop thread_oop = threadObj();
2794   if (thread_oop != NULL) {
2795     st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop));
2796     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
2797     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2798   }
2799   Thread::print_on(st);
2800   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2801   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2802   if (thread_oop != NULL) {
2803     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2804   }
2805 #ifndef PRODUCT
2806   print_thread_state_on(st);
2807   _safepoint_state->print_on(st);
2808 #endif // PRODUCT
2809 }
2810 
2811 // Called by fatal error handler. The difference between this and
2812 // JavaThread::print() is that we can't grab lock or allocate memory.
2813 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2814   st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2815   oop thread_obj = threadObj();
2816   if (thread_obj != NULL) {
2817     if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2818   }
2819   st->print(" [");
2820   st->print("%s", _get_thread_state_name(_thread_state));
2821   if (osthread()) {
2822     st->print(", id=%d", osthread()->thread_id());
2823   }
2824   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2825             _stack_base - _stack_size, _stack_base);
2826   st->print("]");
2827   return;
2828 }
2829 
2830 // Verification
2831 
2832 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2833 
2834 void JavaThread::verify() {
2835   // Verify oops in the thread.
2836   oops_do(&VerifyOopClosure::verify_oop, NULL, NULL);
2837 
2838   // Verify the stack frames.
2839   frames_do(frame_verify);
2840 }
2841 
2842 // CR 6300358 (sub-CR 2137150)
2843 // Most callers of this method assume that it can't return NULL but a
2844 // thread may not have a name whilst it is in the process of attaching to
2845 // the VM - see CR 6412693, and there are places where a JavaThread can be
2846 // seen prior to having it's threadObj set (eg JNI attaching threads and
2847 // if vm exit occurs during initialization). These cases can all be accounted
2848 // for such that this method never returns NULL.
2849 const char* JavaThread::get_thread_name() const {
2850 #ifdef ASSERT
2851   // early safepoints can hit while current thread does not yet have TLS
2852   if (!SafepointSynchronize::is_at_safepoint()) {
2853     Thread *cur = Thread::current();
2854     if (!(cur->is_Java_thread() && cur == this)) {
2855       // Current JavaThreads are allowed to get their own name without
2856       // the Threads_lock.
2857       assert_locked_or_safepoint(Threads_lock);
2858     }
2859   }
2860 #endif // ASSERT
2861   return get_thread_name_string();
2862 }
2863 
2864 // Returns a non-NULL representation of this thread's name, or a suitable
2865 // descriptive string if there is no set name
2866 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2867   const char* name_str;
2868   oop thread_obj = threadObj();
2869   if (thread_obj != NULL) {
2870     typeArrayOop name = java_lang_Thread::name(thread_obj);
2871     if (name != NULL) {
2872       if (buf == NULL) {
2873         name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR),
2874                                     name->length());
2875       } else {
2876         name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR),
2877                                     name->length(), buf, buflen);
2878       }
2879     } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
2880       name_str = "<no-name - thread is attaching>";
2881     } else {
2882       name_str = Thread::name();
2883     }
2884   } else {
2885     name_str = Thread::name();
2886   }
2887   assert(name_str != NULL, "unexpected NULL thread name");
2888   return name_str;
2889 }
2890 
2891 
2892 const char* JavaThread::get_threadgroup_name() const {
2893   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2894   oop thread_obj = threadObj();
2895   if (thread_obj != NULL) {
2896     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2897     if (thread_group != NULL) {
2898       typeArrayOop name = java_lang_ThreadGroup::name(thread_group);
2899       // ThreadGroup.name can be null
2900       if (name != NULL) {
2901         const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2902         return str;
2903       }
2904     }
2905   }
2906   return NULL;
2907 }
2908 
2909 const char* JavaThread::get_parent_name() const {
2910   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2911   oop thread_obj = threadObj();
2912   if (thread_obj != NULL) {
2913     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2914     if (thread_group != NULL) {
2915       oop parent = java_lang_ThreadGroup::parent(thread_group);
2916       if (parent != NULL) {
2917         typeArrayOop name = java_lang_ThreadGroup::name(parent);
2918         // ThreadGroup.name can be null
2919         if (name != NULL) {
2920           const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2921           return str;
2922         }
2923       }
2924     }
2925   }
2926   return NULL;
2927 }
2928 
2929 ThreadPriority JavaThread::java_priority() const {
2930   oop thr_oop = threadObj();
2931   if (thr_oop == NULL) return NormPriority; // Bootstrapping
2932   ThreadPriority priority = java_lang_Thread::priority(thr_oop);
2933   assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
2934   return priority;
2935 }
2936 
2937 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
2938 
2939   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
2940   // Link Java Thread object <-> C++ Thread
2941 
2942   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
2943   // and put it into a new Handle.  The Handle "thread_oop" can then
2944   // be used to pass the C++ thread object to other methods.
2945 
2946   // Set the Java level thread object (jthread) field of the
2947   // new thread (a JavaThread *) to C++ thread object using the
2948   // "thread_oop" handle.
2949 
2950   // Set the thread field (a JavaThread *) of the
2951   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
2952 
2953   Handle thread_oop(Thread::current(),
2954                     JNIHandles::resolve_non_null(jni_thread));
2955   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
2956          "must be initialized");
2957   set_threadObj(thread_oop());
2958   java_lang_Thread::set_thread(thread_oop(), this);
2959 
2960   if (prio == NoPriority) {
2961     prio = java_lang_Thread::priority(thread_oop());
2962     assert(prio != NoPriority, "A valid priority should be present");
2963   }
2964 
2965   // Push the Java priority down to the native thread; needs Threads_lock
2966   Thread::set_priority(this, prio);
2967 
2968   prepare_ext();
2969 
2970   // Add the new thread to the Threads list and set it in motion.
2971   // We must have threads lock in order to call Threads::add.
2972   // It is crucial that we do not block before the thread is
2973   // added to the Threads list for if a GC happens, then the java_thread oop
2974   // will not be visited by GC.
2975   Threads::add(this);
2976 }
2977 
2978 oop JavaThread::current_park_blocker() {
2979   // Support for JSR-166 locks
2980   oop thread_oop = threadObj();
2981   if (thread_oop != NULL &&
2982       JDK_Version::current().supports_thread_park_blocker()) {
2983     return java_lang_Thread::park_blocker(thread_oop);
2984   }
2985   return NULL;
2986 }
2987 
2988 
2989 void JavaThread::print_stack_on(outputStream* st) {
2990   if (!has_last_Java_frame()) return;
2991   ResourceMark rm;
2992   HandleMark   hm;
2993 
2994   RegisterMap reg_map(this);
2995   vframe* start_vf = last_java_vframe(&reg_map);
2996   int count = 0;
2997   for (vframe* f = start_vf; f; f = f->sender()) {
2998     if (f->is_java_frame()) {
2999       javaVFrame* jvf = javaVFrame::cast(f);
3000       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3001 
3002       // Print out lock information
3003       if (JavaMonitorsInStackTrace) {
3004         jvf->print_lock_info_on(st, count);
3005       }
3006     } else {
3007       // Ignore non-Java frames
3008     }
3009 
3010     // Bail-out case for too deep stacks
3011     count++;
3012     if (MaxJavaStackTraceDepth == count) return;
3013   }
3014 }
3015 
3016 
3017 // JVMTI PopFrame support
3018 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3019   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3020   if (in_bytes(size_in_bytes) != 0) {
3021     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3022     _popframe_preserved_args_size = in_bytes(size_in_bytes);
3023     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3024   }
3025 }
3026 
3027 void* JavaThread::popframe_preserved_args() {
3028   return _popframe_preserved_args;
3029 }
3030 
3031 ByteSize JavaThread::popframe_preserved_args_size() {
3032   return in_ByteSize(_popframe_preserved_args_size);
3033 }
3034 
3035 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3036   int sz = in_bytes(popframe_preserved_args_size());
3037   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3038   return in_WordSize(sz / wordSize);
3039 }
3040 
3041 void JavaThread::popframe_free_preserved_args() {
3042   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3043   FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args, mtThread);
3044   _popframe_preserved_args = NULL;
3045   _popframe_preserved_args_size = 0;
3046 }
3047 
3048 #ifndef PRODUCT
3049 
3050 void JavaThread::trace_frames() {
3051   tty->print_cr("[Describe stack]");
3052   int frame_no = 1;
3053   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3054     tty->print("  %d. ", frame_no++);
3055     fst.current()->print_value_on(tty, this);
3056     tty->cr();
3057   }
3058 }
3059 
3060 class PrintAndVerifyOopClosure: public OopClosure {
3061  protected:
3062   template <class T> inline void do_oop_work(T* p) {
3063     oop obj = oopDesc::load_decode_heap_oop(p);
3064     if (obj == NULL) return;
3065     tty->print(INTPTR_FORMAT ": ", p);
3066     if (obj->is_oop_or_null()) {
3067       if (obj->is_objArray()) {
3068         tty->print_cr("valid objArray: " INTPTR_FORMAT, (oopDesc*) obj);
3069       } else {
3070         obj->print();
3071       }
3072     } else {
3073       tty->print_cr("invalid oop: " INTPTR_FORMAT, (oopDesc*) obj);
3074     }
3075     tty->cr();
3076   }
3077  public:
3078   virtual void do_oop(oop* p) { do_oop_work(p); }
3079   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
3080 };
3081 
3082 
3083 static void oops_print(frame* f, const RegisterMap *map) {
3084   PrintAndVerifyOopClosure print;
3085   f->print_value();
3086   f->oops_do(&print, NULL, NULL, (RegisterMap*)map);
3087 }
3088 
3089 // Print our all the locations that contain oops and whether they are
3090 // valid or not.  This useful when trying to find the oldest frame
3091 // where an oop has gone bad since the frame walk is from youngest to
3092 // oldest.
3093 void JavaThread::trace_oops() {
3094   tty->print_cr("[Trace oops]");
3095   frames_do(oops_print);
3096 }
3097 
3098 
3099 #ifdef ASSERT
3100 // Print or validate the layout of stack frames
3101 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3102   ResourceMark rm;
3103   PRESERVE_EXCEPTION_MARK;
3104   FrameValues values;
3105   int frame_no = 0;
3106   for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3107     fst.current()->describe(values, ++frame_no);
3108     if (depth == frame_no) break;
3109   }
3110   if (validate_only) {
3111     values.validate();
3112   } else {
3113     tty->print_cr("[Describe stack layout]");
3114     values.print(this);
3115   }
3116 }
3117 #endif
3118 
3119 void JavaThread::trace_stack_from(vframe* start_vf) {
3120   ResourceMark rm;
3121   int vframe_no = 1;
3122   for (vframe* f = start_vf; f; f = f->sender()) {
3123     if (f->is_java_frame()) {
3124       javaVFrame::cast(f)->print_activation(vframe_no++);
3125     } else {
3126       f->print();
3127     }
3128     if (vframe_no > StackPrintLimit) {
3129       tty->print_cr("...<more frames>...");
3130       return;
3131     }
3132   }
3133 }
3134 
3135 
3136 void JavaThread::trace_stack() {
3137   if (!has_last_Java_frame()) return;
3138   ResourceMark rm;
3139   HandleMark   hm;
3140   RegisterMap reg_map(this);
3141   trace_stack_from(last_java_vframe(&reg_map));
3142 }
3143 
3144 
3145 #endif // PRODUCT
3146 
3147 
3148 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3149   assert(reg_map != NULL, "a map must be given");
3150   frame f = last_frame();
3151   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3152     if (vf->is_java_frame()) return javaVFrame::cast(vf);
3153   }
3154   return NULL;
3155 }
3156 
3157 
3158 Klass* JavaThread::security_get_caller_class(int depth) {
3159   vframeStream vfst(this);
3160   vfst.security_get_caller_frame(depth);
3161   if (!vfst.at_end()) {
3162     return vfst.method()->method_holder();
3163   }
3164   return NULL;
3165 }
3166 
3167 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3168   assert(thread->is_Compiler_thread(), "must be compiler thread");
3169   CompileBroker::compiler_thread_loop();
3170 }
3171 
3172 // Create a CompilerThread
3173 CompilerThread::CompilerThread(CompileQueue* queue,
3174                                CompilerCounters* counters)
3175                                : JavaThread(&compiler_thread_entry) {
3176   _env   = NULL;
3177   _log   = NULL;
3178   _task  = NULL;
3179   _queue = queue;
3180   _counters = counters;
3181   _buffer_blob = NULL;
3182   _scanned_nmethod = NULL;
3183   _compiler = NULL;
3184 
3185 #ifndef PRODUCT
3186   _ideal_graph_printer = NULL;
3187 #endif
3188 }
3189 
3190 void CompilerThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
3191   JavaThread::oops_do(f, cld_f, cf);
3192   if (_scanned_nmethod != NULL && cf != NULL) {
3193     // Safepoints can occur when the sweeper is scanning an nmethod so
3194     // process it here to make sure it isn't unloaded in the middle of
3195     // a scan.
3196     cf->do_code_blob(_scanned_nmethod);
3197   }
3198 }
3199 
3200 
3201 // ======= Threads ========
3202 
3203 // The Threads class links together all active threads, and provides
3204 // operations over all threads.  It is protected by its own Mutex
3205 // lock, which is also used in other contexts to protect thread
3206 // operations from having the thread being operated on from exiting
3207 // and going away unexpectedly (e.g., safepoint synchronization)
3208 
3209 JavaThread* Threads::_thread_list = NULL;
3210 int         Threads::_number_of_threads = 0;
3211 int         Threads::_number_of_non_daemon_threads = 0;
3212 int         Threads::_return_code = 0;
3213 size_t      JavaThread::_stack_size_at_create = 0;
3214 #ifdef ASSERT
3215 bool        Threads::_vm_complete = false;
3216 #endif
3217 
3218 // All JavaThreads
3219 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3220 
3221 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3222 void Threads::threads_do(ThreadClosure* tc) {
3223   assert_locked_or_safepoint(Threads_lock);
3224   // ALL_JAVA_THREADS iterates through all JavaThreads
3225   ALL_JAVA_THREADS(p) {
3226     tc->do_thread(p);
3227   }
3228   // Someday we could have a table or list of all non-JavaThreads.
3229   // For now, just manually iterate through them.
3230   tc->do_thread(VMThread::vm_thread());
3231   Universe::heap()->gc_threads_do(tc);
3232   WatcherThread *wt = WatcherThread::watcher_thread();
3233   // Strictly speaking, the following NULL check isn't sufficient to make sure
3234   // the data for WatcherThread is still valid upon being examined. However,
3235   // considering that WatchThread terminates when the VM is on the way to
3236   // exit at safepoint, the chance of the above is extremely small. The right
3237   // way to prevent termination of WatcherThread would be to acquire
3238   // Terminator_lock, but we can't do that without violating the lock rank
3239   // checking in some cases.
3240   if (wt != NULL) {
3241     tc->do_thread(wt);
3242   }
3243 
3244   // If CompilerThreads ever become non-JavaThreads, add them here
3245 }
3246 
3247 
3248 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3249   TraceTime timer("Initialize java.lang classes", TraceStartupTime);
3250 
3251   if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3252     create_vm_init_libraries();
3253   }
3254 
3255   initialize_class(vmSymbols::java_lang_String(), CHECK);
3256 
3257   // Initialize java_lang.System (needed before creating the thread)
3258   initialize_class(vmSymbols::java_lang_System(), CHECK);
3259   initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3260   Handle thread_group = create_initial_thread_group(CHECK);
3261   Universe::set_main_thread_group(thread_group());
3262   initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3263   oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3264   main_thread->set_threadObj(thread_object);
3265   // Set thread status to running since main thread has
3266   // been started and running.
3267   java_lang_Thread::set_thread_status(thread_object,
3268                                       java_lang_Thread::RUNNABLE);
3269 
3270   // The VM creates & returns objects of this class. Make sure it's initialized.
3271   initialize_class(vmSymbols::java_lang_Class(), CHECK);
3272 
3273   // The VM preresolves methods to these classes. Make sure that they get initialized
3274   initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3275   initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3276   call_initializeSystemClass(CHECK);
3277 
3278   // get the Java runtime name after java.lang.System is initialized
3279   JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3280   JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3281 
3282   // an instance of OutOfMemory exception has been allocated earlier
3283   initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3284   initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3285   initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3286   initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3287   initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3288   initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3289   initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3290   initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3291 }
3292 
3293 void Threads::initialize_jsr292_core_classes(TRAPS) {
3294   initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3295   initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3296   initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3297 }
3298 
3299 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3300   extern void JDK_Version_init();
3301 
3302   // Check version
3303   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3304 
3305   // Initialize the output stream module
3306   ostream_init();
3307 
3308   // Process java launcher properties.
3309   Arguments::process_sun_java_launcher_properties(args);
3310 
3311   // Initialize the os module before using TLS
3312   os::init();
3313 
3314   // Initialize system properties.
3315   Arguments::init_system_properties();
3316 
3317   // So that JDK version can be used as a discriminator when parsing arguments
3318   JDK_Version_init();
3319 
3320   // Update/Initialize System properties after JDK version number is known
3321   Arguments::init_version_specific_system_properties();
3322 
3323   // Parse arguments
3324   jint parse_result = Arguments::parse(args);
3325   if (parse_result != JNI_OK) return parse_result;
3326 
3327   os::init_before_ergo();
3328 
3329   jint ergo_result = Arguments::apply_ergo();
3330   if (ergo_result != JNI_OK) return ergo_result;
3331 
3332   if (PauseAtStartup) {
3333     os::pause();
3334   }
3335 
3336   HOTSPOT_VM_INIT_BEGIN();
3337 
3338   // Record VM creation timing statistics
3339   TraceVmCreationTime create_vm_timer;
3340   create_vm_timer.start();
3341 
3342   // Timing (must come after argument parsing)
3343   TraceTime timer("Create VM", TraceStartupTime);
3344 
3345   // Initialize the os module after parsing the args
3346   jint os_init_2_result = os::init_2();
3347   if (os_init_2_result != JNI_OK) return os_init_2_result;
3348 
3349   jint adjust_after_os_result = Arguments::adjust_after_os();
3350   if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3351 
3352   // initialize TLS
3353   ThreadLocalStorage::init();
3354 
3355   // Initialize output stream logging
3356   ostream_init_log();
3357 
3358   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3359   // Must be before create_vm_init_agents()
3360   if (Arguments::init_libraries_at_startup()) {
3361     convert_vm_init_libraries_to_agents();
3362   }
3363 
3364   // Launch -agentlib/-agentpath and converted -Xrun agents
3365   if (Arguments::init_agents_at_startup()) {
3366     create_vm_init_agents();
3367   }
3368 
3369   // Initialize Threads state
3370   _thread_list = NULL;
3371   _number_of_threads = 0;
3372   _number_of_non_daemon_threads = 0;
3373 
3374   // Initialize global data structures and create system classes in heap
3375   vm_init_globals();
3376 
3377   // Attach the main thread to this os thread
3378   JavaThread* main_thread = new JavaThread();
3379   main_thread->set_thread_state(_thread_in_vm);
3380   // must do this before set_active_handles and initialize_thread_local_storage
3381   // Note: on solaris initialize_thread_local_storage() will (indirectly)
3382   // change the stack size recorded here to one based on the java thread
3383   // stacksize. This adjusted size is what is used to figure the placement
3384   // of the guard pages.
3385   main_thread->record_stack_base_and_size();
3386   main_thread->initialize_thread_local_storage();
3387 
3388   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3389 
3390   if (!main_thread->set_as_starting_thread()) {
3391     vm_shutdown_during_initialization(
3392                                       "Failed necessary internal allocation. Out of swap space");
3393     delete main_thread;
3394     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3395     return JNI_ENOMEM;
3396   }
3397 
3398   // Enable guard page *after* os::create_main_thread(), otherwise it would
3399   // crash Linux VM, see notes in os_linux.cpp.
3400   main_thread->create_stack_guard_pages();
3401 
3402   // Initialize Java-Level synchronization subsystem
3403   ObjectMonitor::Initialize();
3404 
3405   // Initialize global modules
3406   jint status = init_globals();
3407   if (status != JNI_OK) {
3408     delete main_thread;
3409     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3410     return status;
3411   }
3412 
3413   // Should be done after the heap is fully created
3414   main_thread->cache_global_variables();
3415 
3416   HandleMark hm;
3417 
3418   { MutexLocker mu(Threads_lock);
3419     Threads::add(main_thread);
3420   }
3421 
3422   // Any JVMTI raw monitors entered in onload will transition into
3423   // real raw monitor. VM is setup enough here for raw monitor enter.
3424   JvmtiExport::transition_pending_onload_raw_monitors();
3425 
3426   // Create the VMThread
3427   { TraceTime timer("Start VMThread", TraceStartupTime);
3428     VMThread::create();
3429     Thread* vmthread = VMThread::vm_thread();
3430 
3431     if (!os::create_thread(vmthread, os::vm_thread)) {
3432       vm_exit_during_initialization("Cannot create VM thread. "
3433                                     "Out of system resources.");
3434     }
3435 
3436     // Wait for the VM thread to become ready, and VMThread::run to initialize
3437     // Monitors can have spurious returns, must always check another state flag
3438     {
3439       MutexLocker ml(Notify_lock);
3440       os::start_thread(vmthread);
3441       while (vmthread->active_handles() == NULL) {
3442         Notify_lock->wait();
3443       }
3444     }
3445   }
3446 
3447   assert(Universe::is_fully_initialized(), "not initialized");
3448   if (VerifyDuringStartup) {
3449     // Make sure we're starting with a clean slate.
3450     VM_Verify verify_op;
3451     VMThread::execute(&verify_op);
3452   }
3453 
3454   Thread* THREAD = Thread::current();
3455 
3456   // At this point, the Universe is initialized, but we have not executed
3457   // any byte code.  Now is a good time (the only time) to dump out the
3458   // internal state of the JVM for sharing.
3459   if (DumpSharedSpaces) {
3460     MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3461     ShouldNotReachHere();
3462   }
3463 
3464   // Always call even when there are not JVMTI environments yet, since environments
3465   // may be attached late and JVMTI must track phases of VM execution
3466   JvmtiExport::enter_start_phase();
3467 
3468   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3469   JvmtiExport::post_vm_start();
3470 
3471   initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3472 
3473   // We need this for ClassDataSharing - the initial vm.info property is set
3474   // with the default value of CDS "sharing" which may be reset through
3475   // command line options.
3476   reset_vm_info_property(CHECK_JNI_ERR);
3477 
3478   quicken_jni_functions();
3479 
3480   // Must be run after init_ft which initializes ft_enabled
3481   if (TRACE_INITIALIZE() != JNI_OK) {
3482     vm_exit_during_initialization("Failed to initialize tracing backend");
3483   }
3484 
3485   // Set flag that basic initialization has completed. Used by exceptions and various
3486   // debug stuff, that does not work until all basic classes have been initialized.
3487   set_init_completed();
3488 
3489   Metaspace::post_initialize();
3490 
3491   HOTSPOT_VM_INIT_END();
3492 
3493   // record VM initialization completion time
3494 #if INCLUDE_MANAGEMENT
3495   Management::record_vm_init_completed();
3496 #endif // INCLUDE_MANAGEMENT
3497 
3498   // Compute system loader. Note that this has to occur after set_init_completed, since
3499   // valid exceptions may be thrown in the process.
3500   // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
3501   // set_init_completed has just been called, causing exceptions not to be shortcut
3502   // anymore. We call vm_exit_during_initialization directly instead.
3503   SystemDictionary::compute_java_system_loader(CHECK_JNI_ERR);
3504 
3505 #if INCLUDE_ALL_GCS
3506   // Support for ConcurrentMarkSweep. This should be cleaned up
3507   // and better encapsulated. The ugly nested if test would go away
3508   // once things are properly refactored. XXX YSR
3509   if (UseConcMarkSweepGC || UseG1GC) {
3510     if (UseConcMarkSweepGC) {
3511       ConcurrentMarkSweepThread::makeSurrogateLockerThread(CHECK_JNI_ERR);
3512     } else {
3513       ConcurrentMarkThread::makeSurrogateLockerThread(CHECK_JNI_ERR);
3514     }
3515   }
3516 #endif // INCLUDE_ALL_GCS
3517 
3518   // Always call even when there are not JVMTI environments yet, since environments
3519   // may be attached late and JVMTI must track phases of VM execution
3520   JvmtiExport::enter_live_phase();
3521 
3522   // Signal Dispatcher needs to be started before VMInit event is posted
3523   os::signal_init();
3524 
3525   // Start Attach Listener if +StartAttachListener or it can't be started lazily
3526   if (!DisableAttachMechanism) {
3527     AttachListener::vm_start();
3528     if (StartAttachListener || AttachListener::init_at_startup()) {
3529       AttachListener::init();
3530     }
3531   }
3532 
3533   // Launch -Xrun agents
3534   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3535   // back-end can launch with -Xdebug -Xrunjdwp.
3536   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3537     create_vm_init_libraries();
3538   }
3539 
3540   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3541   JvmtiExport::post_vm_initialized();
3542 
3543   if (TRACE_START() != JNI_OK) {
3544     vm_exit_during_initialization("Failed to start tracing backend.");
3545   }
3546 
3547   if (CleanChunkPoolAsync) {
3548     Chunk::start_chunk_pool_cleaner_task();
3549   }
3550 
3551   // initialize compiler(s)
3552 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK)
3553   CompileBroker::compilation_init();
3554 #endif
3555 
3556   // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3557   // It is done after compilers are initialized, because otherwise compilations of
3558   // signature polymorphic MH intrinsics can be missed
3559   // (see SystemDictionary::find_method_handle_intrinsic).
3560   initialize_jsr292_core_classes(CHECK_JNI_ERR);
3561 
3562 #if INCLUDE_MANAGEMENT
3563   Management::initialize(THREAD);
3564 
3565   if (HAS_PENDING_EXCEPTION) {
3566     // management agent fails to start possibly due to
3567     // configuration problem and is responsible for printing
3568     // stack trace if appropriate. Simply exit VM.
3569     vm_exit(1);
3570   }
3571 #endif // INCLUDE_MANAGEMENT
3572 
3573   if (Arguments::has_profile())       FlatProfiler::engage(main_thread, true);
3574   if (MemProfiling)                   MemProfiler::engage();
3575   StatSampler::engage();
3576   if (CheckJNICalls)                  JniPeriodicChecker::engage();
3577 
3578   BiasedLocking::init();
3579 
3580 #if INCLUDE_RTM_OPT
3581   RTMLockingCounters::init();
3582 #endif
3583 
3584   if (JDK_Version::current().post_vm_init_hook_enabled()) {
3585     call_postVMInitHook(THREAD);
3586     // The Java side of PostVMInitHook.run must deal with all
3587     // exceptions and provide means of diagnosis.
3588     if (HAS_PENDING_EXCEPTION) {
3589       CLEAR_PENDING_EXCEPTION;
3590     }
3591   }
3592 
3593   {
3594     MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
3595     // Make sure the watcher thread can be started by WatcherThread::start()
3596     // or by dynamic enrollment.
3597     WatcherThread::make_startable();
3598     // Start up the WatcherThread if there are any periodic tasks
3599     // NOTE:  All PeriodicTasks should be registered by now. If they
3600     //   aren't, late joiners might appear to start slowly (we might
3601     //   take a while to process their first tick).
3602     if (PeriodicTask::num_tasks() > 0) {
3603       WatcherThread::start();
3604     }
3605   }
3606 
3607   // Give os specific code one last chance to start
3608   os::init_3();
3609 
3610   create_vm_timer.end();
3611 #ifdef ASSERT
3612   _vm_complete = true;
3613 #endif
3614   return JNI_OK;
3615 }
3616 
3617 // type for the Agent_OnLoad and JVM_OnLoad entry points
3618 extern "C" {
3619   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3620 }
3621 // Find a command line agent library and return its entry point for
3622 //         -agentlib:  -agentpath:   -Xrun
3623 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3624 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3625                                     const char *on_load_symbols[],
3626                                     size_t num_symbol_entries) {
3627   OnLoadEntry_t on_load_entry = NULL;
3628   void *library = NULL;
3629 
3630   if (!agent->valid()) {
3631     char buffer[JVM_MAXPATHLEN];
3632     char ebuf[1024];
3633     const char *name = agent->name();
3634     const char *msg = "Could not find agent library ";
3635 
3636     // First check to see if agent is statically linked into executable
3637     if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3638       library = agent->os_lib();
3639     } else if (agent->is_absolute_path()) {
3640       library = os::dll_load(name, ebuf, sizeof ebuf);
3641       if (library == NULL) {
3642         const char *sub_msg = " in absolute path, with error: ";
3643         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3644         char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3645         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3646         // If we can't find the agent, exit.
3647         vm_exit_during_initialization(buf, NULL);
3648         FREE_C_HEAP_ARRAY(char, buf, mtThread);
3649       }
3650     } else {
3651       // Try to load the agent from the standard dll directory
3652       if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3653                              name)) {
3654         library = os::dll_load(buffer, ebuf, sizeof ebuf);
3655       }
3656       if (library == NULL) { // Try the local directory
3657         char ns[1] = {0};
3658         if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3659           library = os::dll_load(buffer, ebuf, sizeof ebuf);
3660         }
3661         if (library == NULL) {
3662           const char *sub_msg = " on the library path, with error: ";
3663           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3664           char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3665           jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3666           // If we can't find the agent, exit.
3667           vm_exit_during_initialization(buf, NULL);
3668           FREE_C_HEAP_ARRAY(char, buf, mtThread);
3669         }
3670       }
3671     }
3672     agent->set_os_lib(library);
3673     agent->set_valid();
3674   }
3675 
3676   // Find the OnLoad function.
3677   on_load_entry =
3678     CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3679                                                           false,
3680                                                           on_load_symbols,
3681                                                           num_symbol_entries));
3682   return on_load_entry;
3683 }
3684 
3685 // Find the JVM_OnLoad entry point
3686 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3687   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3688   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3689 }
3690 
3691 // Find the Agent_OnLoad entry point
3692 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3693   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3694   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3695 }
3696 
3697 // For backwards compatibility with -Xrun
3698 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3699 // treated like -agentpath:
3700 // Must be called before agent libraries are created
3701 void Threads::convert_vm_init_libraries_to_agents() {
3702   AgentLibrary* agent;
3703   AgentLibrary* next;
3704 
3705   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3706     next = agent->next();  // cache the next agent now as this agent may get moved off this list
3707     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3708 
3709     // If there is an JVM_OnLoad function it will get called later,
3710     // otherwise see if there is an Agent_OnLoad
3711     if (on_load_entry == NULL) {
3712       on_load_entry = lookup_agent_on_load(agent);
3713       if (on_load_entry != NULL) {
3714         // switch it to the agent list -- so that Agent_OnLoad will be called,
3715         // JVM_OnLoad won't be attempted and Agent_OnUnload will
3716         Arguments::convert_library_to_agent(agent);
3717       } else {
3718         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3719       }
3720     }
3721   }
3722 }
3723 
3724 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
3725 // Invokes Agent_OnLoad
3726 // Called very early -- before JavaThreads exist
3727 void Threads::create_vm_init_agents() {
3728   extern struct JavaVM_ main_vm;
3729   AgentLibrary* agent;
3730 
3731   JvmtiExport::enter_onload_phase();
3732 
3733   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3734     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
3735 
3736     if (on_load_entry != NULL) {
3737       // Invoke the Agent_OnLoad function
3738       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3739       if (err != JNI_OK) {
3740         vm_exit_during_initialization("agent library failed to init", agent->name());
3741       }
3742     } else {
3743       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3744     }
3745   }
3746   JvmtiExport::enter_primordial_phase();
3747 }
3748 
3749 extern "C" {
3750   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3751 }
3752 
3753 void Threads::shutdown_vm_agents() {
3754   // Send any Agent_OnUnload notifications
3755   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3756   size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
3757   extern struct JavaVM_ main_vm;
3758   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3759 
3760     // Find the Agent_OnUnload function.
3761     Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3762                                                    os::find_agent_function(agent,
3763                                                    false,
3764                                                    on_unload_symbols,
3765                                                    num_symbol_entries));
3766 
3767     // Invoke the Agent_OnUnload function
3768     if (unload_entry != NULL) {
3769       JavaThread* thread = JavaThread::current();
3770       ThreadToNativeFromVM ttn(thread);
3771       HandleMark hm(thread);
3772       (*unload_entry)(&main_vm);
3773     }
3774   }
3775 }
3776 
3777 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
3778 // Invokes JVM_OnLoad
3779 void Threads::create_vm_init_libraries() {
3780   extern struct JavaVM_ main_vm;
3781   AgentLibrary* agent;
3782 
3783   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
3784     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3785 
3786     if (on_load_entry != NULL) {
3787       // Invoke the JVM_OnLoad function
3788       JavaThread* thread = JavaThread::current();
3789       ThreadToNativeFromVM ttn(thread);
3790       HandleMark hm(thread);
3791       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3792       if (err != JNI_OK) {
3793         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
3794       }
3795     } else {
3796       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
3797     }
3798   }
3799 }
3800 
3801 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
3802   assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
3803 
3804   JavaThread* java_thread = NULL;
3805   // Sequential search for now.  Need to do better optimization later.
3806   for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
3807     oop tobj = thread->threadObj();
3808     if (!thread->is_exiting() &&
3809         tobj != NULL &&
3810         java_tid == java_lang_Thread::thread_id(tobj)) {
3811       java_thread = thread;
3812       break;
3813     }
3814   }
3815   return java_thread;
3816 }
3817 
3818 
3819 // Last thread running calls java.lang.Shutdown.shutdown()
3820 void JavaThread::invoke_shutdown_hooks() {
3821   HandleMark hm(this);
3822 
3823   // We could get here with a pending exception, if so clear it now.
3824   if (this->has_pending_exception()) {
3825     this->clear_pending_exception();
3826   }
3827 
3828   EXCEPTION_MARK;
3829   Klass* k =
3830     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
3831                                       THREAD);
3832   if (k != NULL) {
3833     // SystemDictionary::resolve_or_null will return null if there was
3834     // an exception.  If we cannot load the Shutdown class, just don't
3835     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
3836     // and finalizers (if runFinalizersOnExit is set) won't be run.
3837     // Note that if a shutdown hook was registered or runFinalizersOnExit
3838     // was called, the Shutdown class would have already been loaded
3839     // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
3840     instanceKlassHandle shutdown_klass (THREAD, k);
3841     JavaValue result(T_VOID);
3842     JavaCalls::call_static(&result,
3843                            shutdown_klass,
3844                            vmSymbols::shutdown_method_name(),
3845                            vmSymbols::void_method_signature(),
3846                            THREAD);
3847   }
3848   CLEAR_PENDING_EXCEPTION;
3849 }
3850 
3851 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
3852 // the program falls off the end of main(). Another VM exit path is through
3853 // vm_exit() when the program calls System.exit() to return a value or when
3854 // there is a serious error in VM. The two shutdown paths are not exactly
3855 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
3856 // and VM_Exit op at VM level.
3857 //
3858 // Shutdown sequence:
3859 //   + Shutdown native memory tracking if it is on
3860 //   + Wait until we are the last non-daemon thread to execute
3861 //     <-- every thing is still working at this moment -->
3862 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
3863 //        shutdown hooks, run finalizers if finalization-on-exit
3864 //   + Call before_exit(), prepare for VM exit
3865 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
3866 //        currently the only user of this mechanism is File.deleteOnExit())
3867 //      > stop flat profiler, StatSampler, watcher thread, CMS threads,
3868 //        post thread end and vm death events to JVMTI,
3869 //        stop signal thread
3870 //   + Call JavaThread::exit(), it will:
3871 //      > release JNI handle blocks, remove stack guard pages
3872 //      > remove this thread from Threads list
3873 //     <-- no more Java code from this thread after this point -->
3874 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
3875 //     the compiler threads at safepoint
3876 //     <-- do not use anything that could get blocked by Safepoint -->
3877 //   + Disable tracing at JNI/JVM barriers
3878 //   + Set _vm_exited flag for threads that are still running native code
3879 //   + Delete this thread
3880 //   + Call exit_globals()
3881 //      > deletes tty
3882 //      > deletes PerfMemory resources
3883 //   + Return to caller
3884 
3885 bool Threads::destroy_vm() {
3886   JavaThread* thread = JavaThread::current();
3887 
3888 #ifdef ASSERT
3889   _vm_complete = false;
3890 #endif
3891   // Wait until we are the last non-daemon thread to execute
3892   { MutexLocker nu(Threads_lock);
3893     while (Threads::number_of_non_daemon_threads() > 1)
3894       // This wait should make safepoint checks, wait without a timeout,
3895       // and wait as a suspend-equivalent condition.
3896       //
3897       // Note: If the FlatProfiler is running and this thread is waiting
3898       // for another non-daemon thread to finish, then the FlatProfiler
3899       // is waiting for the external suspend request on this thread to
3900       // complete. wait_for_ext_suspend_completion() will eventually
3901       // timeout, but that takes time. Making this wait a suspend-
3902       // equivalent condition solves that timeout problem.
3903       //
3904       Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
3905                          Mutex::_as_suspend_equivalent_flag);
3906   }
3907 
3908   // Hang forever on exit if we are reporting an error.
3909   if (ShowMessageBoxOnError && is_error_reported()) {
3910     os::infinite_sleep();
3911   }
3912   os::wait_for_keypress_at_exit();
3913 
3914   // run Java level shutdown hooks
3915   thread->invoke_shutdown_hooks();
3916 
3917   before_exit(thread);
3918 
3919   thread->exit(true);
3920 
3921   // Stop VM thread.
3922   {
3923     // 4945125 The vm thread comes to a safepoint during exit.
3924     // GC vm_operations can get caught at the safepoint, and the
3925     // heap is unparseable if they are caught. Grab the Heap_lock
3926     // to prevent this. The GC vm_operations will not be able to
3927     // queue until after the vm thread is dead. After this point,
3928     // we'll never emerge out of the safepoint before the VM exits.
3929 
3930     MutexLocker ml(Heap_lock);
3931 
3932     VMThread::wait_for_vm_thread_exit();
3933     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
3934     VMThread::destroy();
3935   }
3936 
3937   // clean up ideal graph printers
3938 #if defined(COMPILER2) && !defined(PRODUCT)
3939   IdealGraphPrinter::clean_up();
3940 #endif
3941 
3942   // Now, all Java threads are gone except daemon threads. Daemon threads
3943   // running Java code or in VM are stopped by the Safepoint. However,
3944   // daemon threads executing native code are still running.  But they
3945   // will be stopped at native=>Java/VM barriers. Note that we can't
3946   // simply kill or suspend them, as it is inherently deadlock-prone.
3947 
3948 #ifndef PRODUCT
3949   // disable function tracing at JNI/JVM barriers
3950   TraceJNICalls = false;
3951   TraceJVMCalls = false;
3952   TraceRuntimeCalls = false;
3953 #endif
3954 
3955   VM_Exit::set_vm_exited();
3956 
3957   notify_vm_shutdown();
3958 
3959   delete thread;
3960 
3961   // exit_globals() will delete tty
3962   exit_globals();
3963 
3964   return true;
3965 }
3966 
3967 
3968 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
3969   if (version == JNI_VERSION_1_1) return JNI_TRUE;
3970   return is_supported_jni_version(version);
3971 }
3972 
3973 
3974 jboolean Threads::is_supported_jni_version(jint version) {
3975   if (version == JNI_VERSION_1_2) return JNI_TRUE;
3976   if (version == JNI_VERSION_1_4) return JNI_TRUE;
3977   if (version == JNI_VERSION_1_6) return JNI_TRUE;
3978   if (version == JNI_VERSION_1_8) return JNI_TRUE;
3979   return JNI_FALSE;
3980 }
3981 
3982 
3983 void Threads::add(JavaThread* p, bool force_daemon) {
3984   // The threads lock must be owned at this point
3985   assert_locked_or_safepoint(Threads_lock);
3986 
3987   // See the comment for this method in thread.hpp for its purpose and
3988   // why it is called here.
3989   p->initialize_queues();
3990   p->set_next(_thread_list);
3991   _thread_list = p;
3992   _number_of_threads++;
3993   oop threadObj = p->threadObj();
3994   bool daemon = true;
3995   // Bootstrapping problem: threadObj can be null for initial
3996   // JavaThread (or for threads attached via JNI)
3997   if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
3998     _number_of_non_daemon_threads++;
3999     daemon = false;
4000   }
4001 
4002   ThreadService::add_thread(p, daemon);
4003 
4004   // Possible GC point.
4005   Events::log(p, "Thread added: " INTPTR_FORMAT, p);
4006 }
4007 
4008 void Threads::remove(JavaThread* p) {
4009   // Extra scope needed for Thread_lock, so we can check
4010   // that we do not remove thread without safepoint code notice
4011   { MutexLocker ml(Threads_lock);
4012 
4013     assert(includes(p), "p must be present");
4014 
4015     JavaThread* current = _thread_list;
4016     JavaThread* prev    = NULL;
4017 
4018     while (current != p) {
4019       prev    = current;
4020       current = current->next();
4021     }
4022 
4023     if (prev) {
4024       prev->set_next(current->next());
4025     } else {
4026       _thread_list = p->next();
4027     }
4028     _number_of_threads--;
4029     oop threadObj = p->threadObj();
4030     bool daemon = true;
4031     if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4032       _number_of_non_daemon_threads--;
4033       daemon = false;
4034 
4035       // Only one thread left, do a notify on the Threads_lock so a thread waiting
4036       // on destroy_vm will wake up.
4037       if (number_of_non_daemon_threads() == 1) {
4038         Threads_lock->notify_all();
4039       }
4040     }
4041     ThreadService::remove_thread(p, daemon);
4042 
4043     // Make sure that safepoint code disregard this thread. This is needed since
4044     // the thread might mess around with locks after this point. This can cause it
4045     // to do callbacks into the safepoint code. However, the safepoint code is not aware
4046     // of this thread since it is removed from the queue.
4047     p->set_terminated_value();
4048   } // unlock Threads_lock
4049 
4050   // Since Events::log uses a lock, we grab it outside the Threads_lock
4051   Events::log(p, "Thread exited: " INTPTR_FORMAT, p);
4052 }
4053 
4054 // Threads_lock must be held when this is called (or must be called during a safepoint)
4055 bool Threads::includes(JavaThread* p) {
4056   assert(Threads_lock->is_locked(), "sanity check");
4057   ALL_JAVA_THREADS(q) {
4058     if (q == p) {
4059       return true;
4060     }
4061   }
4062   return false;
4063 }
4064 
4065 // Operations on the Threads list for GC.  These are not explicitly locked,
4066 // but the garbage collector must provide a safe context for them to run.
4067 // In particular, these things should never be called when the Threads_lock
4068 // is held by some other thread. (Note: the Safepoint abstraction also
4069 // uses the Threads_lock to guarantee this property. It also makes sure that
4070 // all threads gets blocked when exiting or starting).
4071 
4072 void Threads::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
4073   ALL_JAVA_THREADS(p) {
4074     p->oops_do(f, cld_f, cf);
4075   }
4076   VMThread::vm_thread()->oops_do(f, cld_f, cf);
4077 }
4078 
4079 void Threads::possibly_parallel_oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
4080   // Introduce a mechanism allowing parallel threads to claim threads as
4081   // root groups.  Overhead should be small enough to use all the time,
4082   // even in sequential code.
4083   SharedHeap* sh = SharedHeap::heap();
4084   // Cannot yet substitute active_workers for n_par_threads
4085   // because of G1CollectedHeap::verify() use of
4086   // SharedHeap::process_roots().  n_par_threads == 0 will
4087   // turn off parallelism in process_roots while active_workers
4088   // is being used for parallelism elsewhere.
4089   bool is_par = sh->n_par_threads() > 0;
4090   assert(!is_par ||
4091          (SharedHeap::heap()->n_par_threads() ==
4092          SharedHeap::heap()->workers()->active_workers()), "Mismatch");
4093   int cp = SharedHeap::heap()->strong_roots_parity();
4094   ALL_JAVA_THREADS(p) {
4095     if (p->claim_oops_do(is_par, cp)) {
4096       p->oops_do(f, cld_f, cf);
4097     }
4098   }
4099   VMThread* vmt = VMThread::vm_thread();
4100   if (vmt->claim_oops_do(is_par, cp)) {
4101     vmt->oops_do(f, cld_f, cf);
4102   }
4103 }
4104 
4105 #if INCLUDE_ALL_GCS
4106 // Used by ParallelScavenge
4107 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4108   ALL_JAVA_THREADS(p) {
4109     q->enqueue(new ThreadRootsTask(p));
4110   }
4111   q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4112 }
4113 
4114 // Used by Parallel Old
4115 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4116   ALL_JAVA_THREADS(p) {
4117     q->enqueue(new ThreadRootsMarkingTask(p));
4118   }
4119   q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4120 }
4121 #endif // INCLUDE_ALL_GCS
4122 
4123 void Threads::nmethods_do(CodeBlobClosure* cf) {
4124   ALL_JAVA_THREADS(p) {
4125     p->nmethods_do(cf);
4126   }
4127   VMThread::vm_thread()->nmethods_do(cf);
4128 }
4129 
4130 void Threads::metadata_do(void f(Metadata*)) {
4131   ALL_JAVA_THREADS(p) {
4132     p->metadata_do(f);
4133   }
4134 }
4135 
4136 void Threads::deoptimized_wrt_marked_nmethods() {
4137   ALL_JAVA_THREADS(p) {
4138     p->deoptimized_wrt_marked_nmethods();
4139   }
4140 }
4141 
4142 
4143 // Get count Java threads that are waiting to enter the specified monitor.
4144 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4145                                                          address monitor,
4146                                                          bool doLock) {
4147   assert(doLock || SafepointSynchronize::is_at_safepoint(),
4148          "must grab Threads_lock or be at safepoint");
4149   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4150 
4151   int i = 0;
4152   {
4153     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4154     ALL_JAVA_THREADS(p) {
4155       if (p->is_Compiler_thread()) continue;
4156 
4157       address pending = (address)p->current_pending_monitor();
4158       if (pending == monitor) {             // found a match
4159         if (i < count) result->append(p);   // save the first count matches
4160         i++;
4161       }
4162     }
4163   }
4164   return result;
4165 }
4166 
4167 
4168 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4169                                                       bool doLock) {
4170   assert(doLock ||
4171          Threads_lock->owned_by_self() ||
4172          SafepointSynchronize::is_at_safepoint(),
4173          "must grab Threads_lock or be at safepoint");
4174 
4175   // NULL owner means not locked so we can skip the search
4176   if (owner == NULL) return NULL;
4177 
4178   {
4179     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4180     ALL_JAVA_THREADS(p) {
4181       // first, see if owner is the address of a Java thread
4182       if (owner == (address)p) return p;
4183     }
4184   }
4185   // Cannot assert on lack of success here since this function may be
4186   // used by code that is trying to report useful problem information
4187   // like deadlock detection.
4188   if (UseHeavyMonitors) return NULL;
4189 
4190   // If we didn't find a matching Java thread and we didn't force use of
4191   // heavyweight monitors, then the owner is the stack address of the
4192   // Lock Word in the owning Java thread's stack.
4193   //
4194   JavaThread* the_owner = NULL;
4195   {
4196     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4197     ALL_JAVA_THREADS(q) {
4198       if (q->is_lock_owned(owner)) {
4199         the_owner = q;
4200         break;
4201       }
4202     }
4203   }
4204   // cannot assert on lack of success here; see above comment
4205   return the_owner;
4206 }
4207 
4208 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4209 void Threads::print_on(outputStream* st, bool print_stacks,
4210                        bool internal_format, bool print_concurrent_locks) {
4211   char buf[32];
4212   st->print_cr("%s", os::local_time_string(buf, sizeof(buf)));
4213 
4214   st->print_cr("Full thread dump %s (%s %s):",
4215                Abstract_VM_Version::vm_name(),
4216                Abstract_VM_Version::vm_release(),
4217                Abstract_VM_Version::vm_info_string());
4218   st->cr();
4219 
4220 #if INCLUDE_ALL_GCS
4221   // Dump concurrent locks
4222   ConcurrentLocksDump concurrent_locks;
4223   if (print_concurrent_locks) {
4224     concurrent_locks.dump_at_safepoint();
4225   }
4226 #endif // INCLUDE_ALL_GCS
4227 
4228   ALL_JAVA_THREADS(p) {
4229     ResourceMark rm;
4230     p->print_on(st);
4231     if (print_stacks) {
4232       if (internal_format) {
4233         p->trace_stack();
4234       } else {
4235         p->print_stack_on(st);
4236       }
4237     }
4238     st->cr();
4239 #if INCLUDE_ALL_GCS
4240     if (print_concurrent_locks) {
4241       concurrent_locks.print_locks_on(p, st);
4242     }
4243 #endif // INCLUDE_ALL_GCS
4244   }
4245 
4246   VMThread::vm_thread()->print_on(st);
4247   st->cr();
4248   Universe::heap()->print_gc_threads_on(st);
4249   WatcherThread* wt = WatcherThread::watcher_thread();
4250   if (wt != NULL) {
4251     wt->print_on(st);
4252     st->cr();
4253   }
4254   CompileBroker::print_compiler_threads_on(st);
4255   st->flush();
4256 }
4257 
4258 // Threads::print_on_error() is called by fatal error handler. It's possible
4259 // that VM is not at safepoint and/or current thread is inside signal handler.
4260 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4261 // memory (even in resource area), it might deadlock the error handler.
4262 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4263                              int buflen) {
4264   bool found_current = false;
4265   st->print_cr("Java Threads: ( => current thread )");
4266   ALL_JAVA_THREADS(thread) {
4267     bool is_current = (current == thread);
4268     found_current = found_current || is_current;
4269 
4270     st->print("%s", is_current ? "=>" : "  ");
4271 
4272     st->print(PTR_FORMAT, thread);
4273     st->print(" ");
4274     thread->print_on_error(st, buf, buflen);
4275     st->cr();
4276   }
4277   st->cr();
4278 
4279   st->print_cr("Other Threads:");
4280   if (VMThread::vm_thread()) {
4281     bool is_current = (current == VMThread::vm_thread());
4282     found_current = found_current || is_current;
4283     st->print("%s", current == VMThread::vm_thread() ? "=>" : "  ");
4284 
4285     st->print(PTR_FORMAT, VMThread::vm_thread());
4286     st->print(" ");
4287     VMThread::vm_thread()->print_on_error(st, buf, buflen);
4288     st->cr();
4289   }
4290   WatcherThread* wt = WatcherThread::watcher_thread();
4291   if (wt != NULL) {
4292     bool is_current = (current == wt);
4293     found_current = found_current || is_current;
4294     st->print("%s", is_current ? "=>" : "  ");
4295 
4296     st->print(PTR_FORMAT, wt);
4297     st->print(" ");
4298     wt->print_on_error(st, buf, buflen);
4299     st->cr();
4300   }
4301   if (!found_current) {
4302     st->cr();
4303     st->print("=>" PTR_FORMAT " (exited) ", current);
4304     current->print_on_error(st, buf, buflen);
4305     st->cr();
4306   }
4307 }
4308 
4309 // Internal SpinLock and Mutex
4310 // Based on ParkEvent
4311 
4312 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4313 //
4314 // We employ SpinLocks _only for low-contention, fixed-length
4315 // short-duration critical sections where we're concerned
4316 // about native mutex_t or HotSpot Mutex:: latency.
4317 // The mux construct provides a spin-then-block mutual exclusion
4318 // mechanism.
4319 //
4320 // Testing has shown that contention on the ListLock guarding gFreeList
4321 // is common.  If we implement ListLock as a simple SpinLock it's common
4322 // for the JVM to devolve to yielding with little progress.  This is true
4323 // despite the fact that the critical sections protected by ListLock are
4324 // extremely short.
4325 //
4326 // TODO-FIXME: ListLock should be of type SpinLock.
4327 // We should make this a 1st-class type, integrated into the lock
4328 // hierarchy as leaf-locks.  Critically, the SpinLock structure
4329 // should have sufficient padding to avoid false-sharing and excessive
4330 // cache-coherency traffic.
4331 
4332 
4333 typedef volatile int SpinLockT;
4334 
4335 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4336   if (Atomic::cmpxchg (1, adr, 0) == 0) {
4337     return;   // normal fast-path return
4338   }
4339 
4340   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4341   TEVENT(SpinAcquire - ctx);
4342   int ctr = 0;
4343   int Yields = 0;
4344   for (;;) {
4345     while (*adr != 0) {
4346       ++ctr;
4347       if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4348         if (Yields > 5) {
4349           os::naked_short_sleep(1);
4350         } else {
4351           os::naked_yield();
4352           ++Yields;
4353         }
4354       } else {
4355         SpinPause();
4356       }
4357     }
4358     if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4359   }
4360 }
4361 
4362 void Thread::SpinRelease(volatile int * adr) {
4363   assert(*adr != 0, "invariant");
4364   OrderAccess::fence();      // guarantee at least release consistency.
4365   // Roach-motel semantics.
4366   // It's safe if subsequent LDs and STs float "up" into the critical section,
4367   // but prior LDs and STs within the critical section can't be allowed
4368   // to reorder or float past the ST that releases the lock.
4369   // Loads and stores in the critical section - which appear in program
4370   // order before the store that releases the lock - must also appear
4371   // before the store that releases the lock in memory visibility order.
4372   // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4373   // the ST of 0 into the lock-word which releases the lock, so fence
4374   // more than covers this on all platforms.
4375   *adr = 0;
4376 }
4377 
4378 // muxAcquire and muxRelease:
4379 //
4380 // *  muxAcquire and muxRelease support a single-word lock-word construct.
4381 //    The LSB of the word is set IFF the lock is held.
4382 //    The remainder of the word points to the head of a singly-linked list
4383 //    of threads blocked on the lock.
4384 //
4385 // *  The current implementation of muxAcquire-muxRelease uses its own
4386 //    dedicated Thread._MuxEvent instance.  If we're interested in
4387 //    minimizing the peak number of extant ParkEvent instances then
4388 //    we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4389 //    as certain invariants were satisfied.  Specifically, care would need
4390 //    to be taken with regards to consuming unpark() "permits".
4391 //    A safe rule of thumb is that a thread would never call muxAcquire()
4392 //    if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4393 //    park().  Otherwise the _ParkEvent park() operation in muxAcquire() could
4394 //    consume an unpark() permit intended for monitorenter, for instance.
4395 //    One way around this would be to widen the restricted-range semaphore
4396 //    implemented in park().  Another alternative would be to provide
4397 //    multiple instances of the PlatformEvent() for each thread.  One
4398 //    instance would be dedicated to muxAcquire-muxRelease, for instance.
4399 //
4400 // *  Usage:
4401 //    -- Only as leaf locks
4402 //    -- for short-term locking only as muxAcquire does not perform
4403 //       thread state transitions.
4404 //
4405 // Alternatives:
4406 // *  We could implement muxAcquire and muxRelease with MCS or CLH locks
4407 //    but with parking or spin-then-park instead of pure spinning.
4408 // *  Use Taura-Oyama-Yonenzawa locks.
4409 // *  It's possible to construct a 1-0 lock if we encode the lockword as
4410 //    (List,LockByte).  Acquire will CAS the full lockword while Release
4411 //    will STB 0 into the LockByte.  The 1-0 scheme admits stranding, so
4412 //    acquiring threads use timers (ParkTimed) to detect and recover from
4413 //    the stranding window.  Thread/Node structures must be aligned on 256-byte
4414 //    boundaries by using placement-new.
4415 // *  Augment MCS with advisory back-link fields maintained with CAS().
4416 //    Pictorially:  LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4417 //    The validity of the backlinks must be ratified before we trust the value.
4418 //    If the backlinks are invalid the exiting thread must back-track through the
4419 //    the forward links, which are always trustworthy.
4420 // *  Add a successor indication.  The LockWord is currently encoded as
4421 //    (List, LOCKBIT:1).  We could also add a SUCCBIT or an explicit _succ variable
4422 //    to provide the usual futile-wakeup optimization.
4423 //    See RTStt for details.
4424 // *  Consider schedctl.sc_nopreempt to cover the critical section.
4425 //
4426 
4427 
4428 typedef volatile intptr_t MutexT;      // Mux Lock-word
4429 enum MuxBits { LOCKBIT = 1 };
4430 
4431 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4432   intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4433   if (w == 0) return;
4434   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4435     return;
4436   }
4437 
4438   TEVENT(muxAcquire - Contention);
4439   ParkEvent * const Self = Thread::current()->_MuxEvent;
4440   assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4441   for (;;) {
4442     int its = (os::is_MP() ? 100 : 0) + 1;
4443 
4444     // Optional spin phase: spin-then-park strategy
4445     while (--its >= 0) {
4446       w = *Lock;
4447       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4448         return;
4449       }
4450     }
4451 
4452     Self->reset();
4453     Self->OnList = intptr_t(Lock);
4454     // The following fence() isn't _strictly necessary as the subsequent
4455     // CAS() both serializes execution and ratifies the fetched *Lock value.
4456     OrderAccess::fence();
4457     for (;;) {
4458       w = *Lock;
4459       if ((w & LOCKBIT) == 0) {
4460         if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4461           Self->OnList = 0;   // hygiene - allows stronger asserts
4462           return;
4463         }
4464         continue;      // Interference -- *Lock changed -- Just retry
4465       }
4466       assert(w & LOCKBIT, "invariant");
4467       Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4468       if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4469     }
4470 
4471     while (Self->OnList != 0) {
4472       Self->park();
4473     }
4474   }
4475 }
4476 
4477 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4478   intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4479   if (w == 0) return;
4480   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4481     return;
4482   }
4483 
4484   TEVENT(muxAcquire - Contention);
4485   ParkEvent * ReleaseAfter = NULL;
4486   if (ev == NULL) {
4487     ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4488   }
4489   assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4490   for (;;) {
4491     guarantee(ev->OnList == 0, "invariant");
4492     int its = (os::is_MP() ? 100 : 0) + 1;
4493 
4494     // Optional spin phase: spin-then-park strategy
4495     while (--its >= 0) {
4496       w = *Lock;
4497       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4498         if (ReleaseAfter != NULL) {
4499           ParkEvent::Release(ReleaseAfter);
4500         }
4501         return;
4502       }
4503     }
4504 
4505     ev->reset();
4506     ev->OnList = intptr_t(Lock);
4507     // The following fence() isn't _strictly necessary as the subsequent
4508     // CAS() both serializes execution and ratifies the fetched *Lock value.
4509     OrderAccess::fence();
4510     for (;;) {
4511       w = *Lock;
4512       if ((w & LOCKBIT) == 0) {
4513         if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4514           ev->OnList = 0;
4515           // We call ::Release while holding the outer lock, thus
4516           // artificially lengthening the critical section.
4517           // Consider deferring the ::Release() until the subsequent unlock(),
4518           // after we've dropped the outer lock.
4519           if (ReleaseAfter != NULL) {
4520             ParkEvent::Release(ReleaseAfter);
4521           }
4522           return;
4523         }
4524         continue;      // Interference -- *Lock changed -- Just retry
4525       }
4526       assert(w & LOCKBIT, "invariant");
4527       ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4528       if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4529     }
4530 
4531     while (ev->OnList != 0) {
4532       ev->park();
4533     }
4534   }
4535 }
4536 
4537 // Release() must extract a successor from the list and then wake that thread.
4538 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4539 // similar to that used by ParkEvent::Allocate() and ::Release().  DMR-based
4540 // Release() would :
4541 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4542 // (B) Extract a successor from the private list "in-hand"
4543 // (C) attempt to CAS() the residual back into *Lock over null.
4544 //     If there were any newly arrived threads and the CAS() would fail.
4545 //     In that case Release() would detach the RATs, re-merge the list in-hand
4546 //     with the RATs and repeat as needed.  Alternately, Release() might
4547 //     detach and extract a successor, but then pass the residual list to the wakee.
4548 //     The wakee would be responsible for reattaching and remerging before it
4549 //     competed for the lock.
4550 //
4551 // Both "pop" and DMR are immune from ABA corruption -- there can be
4552 // multiple concurrent pushers, but only one popper or detacher.
4553 // This implementation pops from the head of the list.  This is unfair,
4554 // but tends to provide excellent throughput as hot threads remain hot.
4555 // (We wake recently run threads first).
4556 //
4557 // All paths through muxRelease() will execute a CAS.
4558 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4559 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4560 // executed within the critical section are complete and globally visible before the
4561 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4562 void Thread::muxRelease(volatile intptr_t * Lock)  {
4563   for (;;) {
4564     const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4565     assert(w & LOCKBIT, "invariant");
4566     if (w == LOCKBIT) return;
4567     ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4568     assert(List != NULL, "invariant");
4569     assert(List->OnList == intptr_t(Lock), "invariant");
4570     ParkEvent * const nxt = List->ListNext;
4571     guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4572 
4573     // The following CAS() releases the lock and pops the head element.
4574     // The CAS() also ratifies the previously fetched lock-word value.
4575     if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4576       continue;
4577     }
4578     List->OnList = 0;
4579     OrderAccess::fence();
4580     List->unpark();
4581     return;
4582   }
4583 }
4584 
4585 
4586 void Threads::verify() {
4587   ALL_JAVA_THREADS(p) {
4588     p->verify();
4589   }
4590   VMThread* thread = VMThread::vm_thread();
4591   if (thread != NULL) thread->verify();
4592 }