1 /*
   2  * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/classLoader.hpp"
  27 #include "classfile/javaClasses.hpp"
  28 #include "classfile/systemDictionary.hpp"
  29 #include "classfile/vmSymbols.hpp"
  30 #include "code/scopeDesc.hpp"
  31 #include "compiler/compileBroker.hpp"
  32 #include "interpreter/interpreter.hpp"
  33 #include "interpreter/linkResolver.hpp"
  34 #include "interpreter/oopMapCache.hpp"
  35 #include "jvmtifiles/jvmtiEnv.hpp"
  36 #include "memory/gcLocker.inline.hpp"
  37 #include "memory/metaspaceShared.hpp"
  38 #include "memory/oopFactory.hpp"
  39 #include "memory/universe.inline.hpp"
  40 #include "oops/instanceKlass.hpp"
  41 #include "oops/objArrayOop.hpp"
  42 #include "oops/oop.inline.hpp"
  43 #include "oops/symbol.hpp"
  44 #include "prims/jvm_misc.hpp"
  45 #include "prims/jvmtiExport.hpp"
  46 #include "prims/jvmtiThreadState.hpp"
  47 #include "prims/privilegedStack.hpp"
  48 #include "runtime/arguments.hpp"
  49 #include "runtime/biasedLocking.hpp"
  50 #include "runtime/deoptimization.hpp"
  51 #include "runtime/fprofiler.hpp"
  52 #include "runtime/frame.inline.hpp"
  53 #include "runtime/init.hpp"
  54 #include "runtime/interfaceSupport.hpp"
  55 #include "runtime/java.hpp"
  56 #include "runtime/javaCalls.hpp"
  57 #include "runtime/jniPeriodicChecker.hpp"
  58 #include "runtime/memprofiler.hpp"
  59 #include "runtime/mutexLocker.hpp"
  60 #include "runtime/objectMonitor.hpp"
  61 #include "runtime/orderAccess.inline.hpp"
  62 #include "runtime/osThread.hpp"
  63 #include "runtime/safepoint.hpp"
  64 #include "runtime/sharedRuntime.hpp"
  65 #include "runtime/statSampler.hpp"
  66 #include "runtime/stubRoutines.hpp"
  67 #include "runtime/task.hpp"
  68 #include "runtime/thread.inline.hpp"
  69 #include "runtime/threadCritical.hpp"
  70 #include "runtime/threadLocalStorage.hpp"
  71 #include "runtime/vframe.hpp"
  72 #include "runtime/vframeArray.hpp"
  73 #include "runtime/vframe_hp.hpp"
  74 #include "runtime/vmThread.hpp"
  75 #include "runtime/vm_operations.hpp"
  76 #include "services/attachListener.hpp"
  77 #include "services/management.hpp"
  78 #include "services/memTracker.hpp"
  79 #include "services/threadService.hpp"
  80 #include "trace/tracing.hpp"
  81 #include "trace/traceMacros.hpp"
  82 #include "utilities/defaultStream.hpp"
  83 #include "utilities/dtrace.hpp"
  84 #include "utilities/events.hpp"
  85 #include "utilities/preserveException.hpp"
  86 #include "utilities/macros.hpp"
  87 #ifdef TARGET_OS_FAMILY_linux
  88 # include "os_linux.inline.hpp"
  89 #endif
  90 #ifdef TARGET_OS_FAMILY_solaris
  91 # include "os_solaris.inline.hpp"
  92 #endif
  93 #ifdef TARGET_OS_FAMILY_windows
  94 # include "os_windows.inline.hpp"
  95 #endif
  96 #ifdef TARGET_OS_FAMILY_bsd
  97 # include "os_bsd.inline.hpp"
  98 #endif
  99 #if INCLUDE_ALL_GCS
 100 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
 101 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
 102 #include "gc_implementation/parallelScavenge/pcTasks.hpp"
 103 #endif // INCLUDE_ALL_GCS
 104 #ifdef COMPILER1
 105 #include "c1/c1_Compiler.hpp"
 106 #endif
 107 #ifdef COMPILER2
 108 #include "opto/c2compiler.hpp"
 109 #include "opto/idealGraphPrinter.hpp"
 110 #endif
 111 #if INCLUDE_RTM_OPT
 112 #include "runtime/rtmLocking.hpp"
 113 #endif
 114 
 115 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
 116 
 117 #ifdef DTRACE_ENABLED
 118 
 119 // Only bother with this argument setup if dtrace is available
 120 
 121 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
 122 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
 123 
 124 #define DTRACE_THREAD_PROBE(probe, javathread)                             \
 125   {                                                                        \
 126     ResourceMark rm(this);                                                 \
 127     int len = 0;                                                           \
 128     const char* name = (javathread)->get_thread_name();                    \
 129     len = strlen(name);                                                    \
 130     HOTSPOT_THREAD_PROBE_##probe(  /* probe = start, stop */               \
 131       (char *) name, len,                                                           \
 132       java_lang_Thread::thread_id((javathread)->threadObj()),              \
 133       (uintptr_t) (javathread)->osthread()->thread_id(),                               \
 134       java_lang_Thread::is_daemon((javathread)->threadObj()));             \
 135   }
 136 
 137 #else //  ndef DTRACE_ENABLED
 138 
 139 #define DTRACE_THREAD_PROBE(probe, javathread)
 140 
 141 #endif // ndef DTRACE_ENABLED
 142 
 143 
 144 // Class hierarchy
 145 // - Thread
 146 //   - VMThread
 147 //   - WatcherThread
 148 //   - ConcurrentMarkSweepThread
 149 //   - JavaThread
 150 //     - CompilerThread
 151 
 152 // ======= Thread ========
 153 // Support for forcing alignment of thread objects for biased locking
 154 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
 155   if (UseBiasedLocking) {
 156     const int alignment = markOopDesc::biased_lock_alignment;
 157     size_t aligned_size = size + (alignment - sizeof(intptr_t));
 158     void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
 159                                           : AllocateHeap(aligned_size, flags, CURRENT_PC,
 160                                               AllocFailStrategy::RETURN_NULL);
 161     void* aligned_addr     = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
 162     assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
 163            ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
 164            "JavaThread alignment code overflowed allocated storage");
 165     if (TraceBiasedLocking) {
 166       if (aligned_addr != real_malloc_addr)
 167         tty->print_cr("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
 168                       real_malloc_addr, aligned_addr);
 169     }
 170     ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
 171     return aligned_addr;
 172   } else {
 173     return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
 174                        : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
 175   }
 176 }
 177 
 178 void Thread::operator delete(void* p) {
 179   if (UseBiasedLocking) {
 180     void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
 181     FreeHeap(real_malloc_addr, mtThread);
 182   } else {
 183     FreeHeap(p, mtThread);
 184   }
 185 }
 186 
 187 
 188 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
 189 // JavaThread
 190 
 191 
 192 Thread::Thread() {
 193   // stack and get_thread
 194   set_stack_base(NULL);
 195   set_stack_size(0);
 196   set_self_raw_id(0);
 197   set_lgrp_id(-1);
 198 
 199   // allocated data structures
 200   set_osthread(NULL);
 201   set_resource_area(new (mtThread)ResourceArea());
 202   DEBUG_ONLY(_current_resource_mark = NULL;)
 203   set_handle_area(new (mtThread) HandleArea(NULL));
 204   set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
 205   set_active_handles(NULL);
 206   set_free_handle_block(NULL);
 207   set_last_handle_mark(NULL);
 208 
 209   // This initial value ==> never claimed.
 210   _oops_do_parity = 0;
 211 
 212   // the handle mark links itself to last_handle_mark
 213   new HandleMark(this);
 214 
 215   // plain initialization
 216   debug_only(_owned_locks = NULL;)
 217   debug_only(_allow_allocation_count = 0;)
 218   NOT_PRODUCT(_allow_safepoint_count = 0;)
 219   NOT_PRODUCT(_skip_gcalot = false;)
 220   _jvmti_env_iteration_count = 0;
 221   set_allocated_bytes(0);
 222   _vm_operation_started_count = 0;
 223   _vm_operation_completed_count = 0;
 224   _current_pending_monitor = NULL;
 225   _current_pending_monitor_is_from_java = true;
 226   _current_waiting_monitor = NULL;
 227   _num_nested_signal = 0;
 228   omFreeList = NULL ;
 229   omFreeCount = 0 ;
 230   omFreeProvision = 32 ;
 231   omInUseList = NULL ;
 232   omInUseCount = 0 ;
 233 
 234 #ifdef ASSERT
 235   _visited_for_critical_count = false;
 236 #endif
 237 
 238   _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true);
 239   _suspend_flags = 0;
 240 
 241   // thread-specific hashCode stream generator state - Marsaglia shift-xor form
 242   _hashStateX = os::random() ;
 243   _hashStateY = 842502087 ;
 244   _hashStateZ = 0x8767 ;    // (int)(3579807591LL & 0xffff) ;
 245   _hashStateW = 273326509 ;
 246 
 247   _OnTrap   = 0 ;
 248   _schedctl = NULL ;
 249   _Stalled  = 0 ;
 250   _TypeTag  = 0x2BAD ;
 251 
 252   // Many of the following fields are effectively final - immutable
 253   // Note that nascent threads can't use the Native Monitor-Mutex
 254   // construct until the _MutexEvent is initialized ...
 255   // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
 256   // we might instead use a stack of ParkEvents that we could provision on-demand.
 257   // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
 258   // and ::Release()
 259   _ParkEvent   = ParkEvent::Allocate (this) ;
 260   _SleepEvent  = ParkEvent::Allocate (this) ;
 261   _MutexEvent  = ParkEvent::Allocate (this) ;
 262   _MuxEvent    = ParkEvent::Allocate (this) ;
 263 
 264 #ifdef CHECK_UNHANDLED_OOPS
 265   if (CheckUnhandledOops) {
 266     _unhandled_oops = new UnhandledOops(this);
 267   }
 268 #endif // CHECK_UNHANDLED_OOPS
 269 #ifdef ASSERT
 270   if (UseBiasedLocking) {
 271     assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
 272     assert(this == _real_malloc_address ||
 273            this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
 274            "bug in forced alignment of thread objects");
 275   }
 276 #endif /* ASSERT */
 277 }
 278 
 279 void Thread::initialize_thread_local_storage() {
 280   // Note: Make sure this method only calls
 281   // non-blocking operations. Otherwise, it might not work
 282   // with the thread-startup/safepoint interaction.
 283 
 284   // During Java thread startup, safepoint code should allow this
 285   // method to complete because it may need to allocate memory to
 286   // store information for the new thread.
 287 
 288   // initialize structure dependent on thread local storage
 289   ThreadLocalStorage::set_thread(this);
 290 }
 291 
 292 void Thread::record_stack_base_and_size() {
 293   set_stack_base(os::current_stack_base());
 294   set_stack_size(os::current_stack_size());
 295   if (is_Java_thread()) {
 296     ((JavaThread*) this)->set_stack_overflow_limit();
 297   }
 298   // CR 7190089: on Solaris, primordial thread's stack is adjusted
 299   // in initialize_thread(). Without the adjustment, stack size is
 300   // incorrect if stack is set to unlimited (ulimit -s unlimited).
 301   // So far, only Solaris has real implementation of initialize_thread().
 302   //
 303   // set up any platform-specific state.
 304   os::initialize_thread(this);
 305 
 306 #if INCLUDE_NMT
 307   // record thread's native stack, stack grows downward
 308   address stack_low_addr = stack_base() - stack_size();
 309   MemTracker::record_thread_stack(stack_low_addr, stack_size(), this,
 310       CURRENT_PC);
 311 #endif // INCLUDE_NMT
 312 }
 313 
 314 
 315 Thread::~Thread() {
 316   // Reclaim the objectmonitors from the omFreeList of the moribund thread.
 317   ObjectSynchronizer::omFlush (this) ;
 318 
 319   EVENT_THREAD_DESTRUCT(this);
 320 
 321   // stack_base can be NULL if the thread is never started or exited before
 322   // record_stack_base_and_size called. Although, we would like to ensure
 323   // that all started threads do call record_stack_base_and_size(), there is
 324   // not proper way to enforce that.
 325 #if INCLUDE_NMT
 326   if (_stack_base != NULL) {
 327     address low_stack_addr = stack_base() - stack_size();
 328     MemTracker::release_thread_stack(low_stack_addr, stack_size(), this);
 329 #ifdef ASSERT
 330     set_stack_base(NULL);
 331 #endif
 332   }
 333 #endif // INCLUDE_NMT
 334 
 335   // deallocate data structures
 336   delete resource_area();
 337   // since the handle marks are using the handle area, we have to deallocated the root
 338   // handle mark before deallocating the thread's handle area,
 339   assert(last_handle_mark() != NULL, "check we have an element");
 340   delete last_handle_mark();
 341   assert(last_handle_mark() == NULL, "check we have reached the end");
 342 
 343   // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
 344   // We NULL out the fields for good hygiene.
 345   ParkEvent::Release (_ParkEvent)   ; _ParkEvent   = NULL ;
 346   ParkEvent::Release (_SleepEvent)  ; _SleepEvent  = NULL ;
 347   ParkEvent::Release (_MutexEvent)  ; _MutexEvent  = NULL ;
 348   ParkEvent::Release (_MuxEvent)    ; _MuxEvent    = NULL ;
 349 
 350   delete handle_area();
 351   delete metadata_handles();
 352 
 353   // osthread() can be NULL, if creation of thread failed.
 354   if (osthread() != NULL) os::free_thread(osthread());
 355 
 356   delete _SR_lock;
 357 
 358   // clear thread local storage if the Thread is deleting itself
 359   if (this == Thread::current()) {
 360     ThreadLocalStorage::set_thread(NULL);
 361   } else {
 362     // In the case where we're not the current thread, invalidate all the
 363     // caches in case some code tries to get the current thread or the
 364     // thread that was destroyed, and gets stale information.
 365     ThreadLocalStorage::invalidate_all();
 366   }
 367   CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
 368 }
 369 
 370 // NOTE: dummy function for assertion purpose.
 371 void Thread::run() {
 372   ShouldNotReachHere();
 373 }
 374 
 375 #ifdef ASSERT
 376 // Private method to check for dangling thread pointer
 377 void check_for_dangling_thread_pointer(Thread *thread) {
 378  assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
 379          "possibility of dangling Thread pointer");
 380 }
 381 #endif
 382 
 383 
 384 #ifndef PRODUCT
 385 // Tracing method for basic thread operations
 386 void Thread::trace(const char* msg, const Thread* const thread) {
 387   if (!TraceThreadEvents) return;
 388   ResourceMark rm;
 389   ThreadCritical tc;
 390   const char *name = "non-Java thread";
 391   int prio = -1;
 392   if (thread->is_Java_thread()
 393       && !thread->is_Compiler_thread()) {
 394     // The Threads_lock must be held to get information about
 395     // this thread but may not be in some situations when
 396     // tracing  thread events.
 397     bool release_Threads_lock = false;
 398     if (!Threads_lock->owned_by_self()) {
 399       Threads_lock->lock();
 400       release_Threads_lock = true;
 401     }
 402     JavaThread* jt = (JavaThread *)thread;
 403     name = (char *)jt->get_thread_name();
 404     oop thread_oop = jt->threadObj();
 405     if (thread_oop != NULL) {
 406       prio = java_lang_Thread::priority(thread_oop);
 407     }
 408     if (release_Threads_lock) {
 409       Threads_lock->unlock();
 410     }
 411   }
 412   tty->print_cr("Thread::%s " INTPTR_FORMAT " [%lx] %s (prio: %d)", msg, thread, thread->osthread()->thread_id(), name, prio);
 413 }
 414 #endif
 415 
 416 
 417 ThreadPriority Thread::get_priority(const Thread* const thread) {
 418   trace("get priority", thread);
 419   ThreadPriority priority;
 420   // Can return an error!
 421   (void)os::get_priority(thread, priority);
 422   assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
 423   return priority;
 424 }
 425 
 426 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
 427   trace("set priority", thread);
 428   debug_only(check_for_dangling_thread_pointer(thread);)
 429   // Can return an error!
 430   (void)os::set_priority(thread, priority);
 431 }
 432 
 433 
 434 void Thread::start(Thread* thread) {
 435   trace("start", thread);
 436   // Start is different from resume in that its safety is guaranteed by context or
 437   // being called from a Java method synchronized on the Thread object.
 438   if (!DisableStartThread) {
 439     if (thread->is_Java_thread()) {
 440       // Initialize the thread state to RUNNABLE before starting this thread.
 441       // Can not set it after the thread started because we do not know the
 442       // exact thread state at that time. It could be in MONITOR_WAIT or
 443       // in SLEEPING or some other state.
 444       java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
 445                                           java_lang_Thread::RUNNABLE);
 446     }
 447     os::start_thread(thread);
 448   }
 449 }
 450 
 451 // Enqueue a VM_Operation to do the job for us - sometime later
 452 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
 453   VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
 454   VMThread::execute(vm_stop);
 455 }
 456 
 457 
 458 //
 459 // Check if an external suspend request has completed (or has been
 460 // cancelled). Returns true if the thread is externally suspended and
 461 // false otherwise.
 462 //
 463 // The bits parameter returns information about the code path through
 464 // the routine. Useful for debugging:
 465 //
 466 // set in is_ext_suspend_completed():
 467 // 0x00000001 - routine was entered
 468 // 0x00000010 - routine return false at end
 469 // 0x00000100 - thread exited (return false)
 470 // 0x00000200 - suspend request cancelled (return false)
 471 // 0x00000400 - thread suspended (return true)
 472 // 0x00001000 - thread is in a suspend equivalent state (return true)
 473 // 0x00002000 - thread is native and walkable (return true)
 474 // 0x00004000 - thread is native_trans and walkable (needed retry)
 475 //
 476 // set in wait_for_ext_suspend_completion():
 477 // 0x00010000 - routine was entered
 478 // 0x00020000 - suspend request cancelled before loop (return false)
 479 // 0x00040000 - thread suspended before loop (return true)
 480 // 0x00080000 - suspend request cancelled in loop (return false)
 481 // 0x00100000 - thread suspended in loop (return true)
 482 // 0x00200000 - suspend not completed during retry loop (return false)
 483 //
 484 
 485 // Helper class for tracing suspend wait debug bits.
 486 //
 487 // 0x00000100 indicates that the target thread exited before it could
 488 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
 489 // 0x00080000 each indicate a cancelled suspend request so they don't
 490 // count as wait failures either.
 491 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
 492 
 493 class TraceSuspendDebugBits : public StackObj {
 494  private:
 495   JavaThread * jt;
 496   bool         is_wait;
 497   bool         called_by_wait;  // meaningful when !is_wait
 498   uint32_t *   bits;
 499 
 500  public:
 501   TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
 502                         uint32_t *_bits) {
 503     jt             = _jt;
 504     is_wait        = _is_wait;
 505     called_by_wait = _called_by_wait;
 506     bits           = _bits;
 507   }
 508 
 509   ~TraceSuspendDebugBits() {
 510     if (!is_wait) {
 511 #if 1
 512       // By default, don't trace bits for is_ext_suspend_completed() calls.
 513       // That trace is very chatty.
 514       return;
 515 #else
 516       if (!called_by_wait) {
 517         // If tracing for is_ext_suspend_completed() is enabled, then only
 518         // trace calls to it from wait_for_ext_suspend_completion()
 519         return;
 520       }
 521 #endif
 522     }
 523 
 524     if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
 525       if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
 526         MutexLocker ml(Threads_lock);  // needed for get_thread_name()
 527         ResourceMark rm;
 528 
 529         tty->print_cr(
 530             "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
 531             jt->get_thread_name(), *bits);
 532 
 533         guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
 534       }
 535     }
 536   }
 537 };
 538 #undef DEBUG_FALSE_BITS
 539 
 540 
 541 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, uint32_t *bits) {
 542   TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
 543 
 544   bool did_trans_retry = false;  // only do thread_in_native_trans retry once
 545   bool do_trans_retry;           // flag to force the retry
 546 
 547   *bits |= 0x00000001;
 548 
 549   do {
 550     do_trans_retry = false;
 551 
 552     if (is_exiting()) {
 553       // Thread is in the process of exiting. This is always checked
 554       // first to reduce the risk of dereferencing a freed JavaThread.
 555       *bits |= 0x00000100;
 556       return false;
 557     }
 558 
 559     if (!is_external_suspend()) {
 560       // Suspend request is cancelled. This is always checked before
 561       // is_ext_suspended() to reduce the risk of a rogue resume
 562       // confusing the thread that made the suspend request.
 563       *bits |= 0x00000200;
 564       return false;
 565     }
 566 
 567     if (is_ext_suspended()) {
 568       // thread is suspended
 569       *bits |= 0x00000400;
 570       return true;
 571     }
 572 
 573     // Now that we no longer do hard suspends of threads running
 574     // native code, the target thread can be changing thread state
 575     // while we are in this routine:
 576     //
 577     //   _thread_in_native -> _thread_in_native_trans -> _thread_blocked
 578     //
 579     // We save a copy of the thread state as observed at this moment
 580     // and make our decision about suspend completeness based on the
 581     // copy. This closes the race where the thread state is seen as
 582     // _thread_in_native_trans in the if-thread_blocked check, but is
 583     // seen as _thread_blocked in if-thread_in_native_trans check.
 584     JavaThreadState save_state = thread_state();
 585 
 586     if (save_state == _thread_blocked && is_suspend_equivalent()) {
 587       // If the thread's state is _thread_blocked and this blocking
 588       // condition is known to be equivalent to a suspend, then we can
 589       // consider the thread to be externally suspended. This means that
 590       // the code that sets _thread_blocked has been modified to do
 591       // self-suspension if the blocking condition releases. We also
 592       // used to check for CONDVAR_WAIT here, but that is now covered by
 593       // the _thread_blocked with self-suspension check.
 594       //
 595       // Return true since we wouldn't be here unless there was still an
 596       // external suspend request.
 597       *bits |= 0x00001000;
 598       return true;
 599     } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
 600       // Threads running native code will self-suspend on native==>VM/Java
 601       // transitions. If its stack is walkable (should always be the case
 602       // unless this function is called before the actual java_suspend()
 603       // call), then the wait is done.
 604       *bits |= 0x00002000;
 605       return true;
 606     } else if (!called_by_wait && !did_trans_retry &&
 607                save_state == _thread_in_native_trans &&
 608                frame_anchor()->walkable()) {
 609       // The thread is transitioning from thread_in_native to another
 610       // thread state. check_safepoint_and_suspend_for_native_trans()
 611       // will force the thread to self-suspend. If it hasn't gotten
 612       // there yet we may have caught the thread in-between the native
 613       // code check above and the self-suspend. Lucky us. If we were
 614       // called by wait_for_ext_suspend_completion(), then it
 615       // will be doing the retries so we don't have to.
 616       //
 617       // Since we use the saved thread state in the if-statement above,
 618       // there is a chance that the thread has already transitioned to
 619       // _thread_blocked by the time we get here. In that case, we will
 620       // make a single unnecessary pass through the logic below. This
 621       // doesn't hurt anything since we still do the trans retry.
 622 
 623       *bits |= 0x00004000;
 624 
 625       // Once the thread leaves thread_in_native_trans for another
 626       // thread state, we break out of this retry loop. We shouldn't
 627       // need this flag to prevent us from getting back here, but
 628       // sometimes paranoia is good.
 629       did_trans_retry = true;
 630 
 631       // We wait for the thread to transition to a more usable state.
 632       for (int i = 1; i <= SuspendRetryCount; i++) {
 633         // We used to do an "os::yield_all(i)" call here with the intention
 634         // that yielding would increase on each retry. However, the parameter
 635         // is ignored on Linux which means the yield didn't scale up. Waiting
 636         // on the SR_lock below provides a much more predictable scale up for
 637         // the delay. It also provides a simple/direct point to check for any
 638         // safepoint requests from the VMThread
 639 
 640         // temporarily drops SR_lock while doing wait with safepoint check
 641         // (if we're a JavaThread - the WatcherThread can also call this)
 642         // and increase delay with each retry
 643         SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 644 
 645         // check the actual thread state instead of what we saved above
 646         if (thread_state() != _thread_in_native_trans) {
 647           // the thread has transitioned to another thread state so
 648           // try all the checks (except this one) one more time.
 649           do_trans_retry = true;
 650           break;
 651         }
 652       } // end retry loop
 653 
 654 
 655     }
 656   } while (do_trans_retry);
 657 
 658   *bits |= 0x00000010;
 659   return false;
 660 }
 661 
 662 //
 663 // Wait for an external suspend request to complete (or be cancelled).
 664 // Returns true if the thread is externally suspended and false otherwise.
 665 //
 666 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
 667        uint32_t *bits) {
 668   TraceSuspendDebugBits tsdb(this, true /* is_wait */,
 669                              false /* !called_by_wait */, bits);
 670 
 671   // local flag copies to minimize SR_lock hold time
 672   bool is_suspended;
 673   bool pending;
 674   uint32_t reset_bits;
 675 
 676   // set a marker so is_ext_suspend_completed() knows we are the caller
 677   *bits |= 0x00010000;
 678 
 679   // We use reset_bits to reinitialize the bits value at the top of
 680   // each retry loop. This allows the caller to make use of any
 681   // unused bits for their own marking purposes.
 682   reset_bits = *bits;
 683 
 684   {
 685     MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
 686     is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 687                                             delay, bits);
 688     pending = is_external_suspend();
 689   }
 690   // must release SR_lock to allow suspension to complete
 691 
 692   if (!pending) {
 693     // A cancelled suspend request is the only false return from
 694     // is_ext_suspend_completed() that keeps us from entering the
 695     // retry loop.
 696     *bits |= 0x00020000;
 697     return false;
 698   }
 699 
 700   if (is_suspended) {
 701     *bits |= 0x00040000;
 702     return true;
 703   }
 704 
 705   for (int i = 1; i <= retries; i++) {
 706     *bits = reset_bits;  // reinit to only track last retry
 707 
 708     // We used to do an "os::yield_all(i)" call here with the intention
 709     // that yielding would increase on each retry. However, the parameter
 710     // is ignored on Linux which means the yield didn't scale up. Waiting
 711     // on the SR_lock below provides a much more predictable scale up for
 712     // the delay. It also provides a simple/direct point to check for any
 713     // safepoint requests from the VMThread
 714 
 715     {
 716       MutexLocker ml(SR_lock());
 717       // wait with safepoint check (if we're a JavaThread - the WatcherThread
 718       // can also call this)  and increase delay with each retry
 719       SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 720 
 721       is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 722                                               delay, bits);
 723 
 724       // It is possible for the external suspend request to be cancelled
 725       // (by a resume) before the actual suspend operation is completed.
 726       // Refresh our local copy to see if we still need to wait.
 727       pending = is_external_suspend();
 728     }
 729 
 730     if (!pending) {
 731       // A cancelled suspend request is the only false return from
 732       // is_ext_suspend_completed() that keeps us from staying in the
 733       // retry loop.
 734       *bits |= 0x00080000;
 735       return false;
 736     }
 737 
 738     if (is_suspended) {
 739       *bits |= 0x00100000;
 740       return true;
 741     }
 742   } // end retry loop
 743 
 744   // thread did not suspend after all our retries
 745   *bits |= 0x00200000;
 746   return false;
 747 }
 748 
 749 #ifndef PRODUCT
 750 void JavaThread::record_jump(address target, address instr, const char* file, int line) {
 751 
 752   // This should not need to be atomic as the only way for simultaneous
 753   // updates is via interrupts. Even then this should be rare or non-existent
 754   // and we don't care that much anyway.
 755 
 756   int index = _jmp_ring_index;
 757   _jmp_ring_index = (index + 1 ) & (jump_ring_buffer_size - 1);
 758   _jmp_ring[index]._target = (intptr_t) target;
 759   _jmp_ring[index]._instruction = (intptr_t) instr;
 760   _jmp_ring[index]._file = file;
 761   _jmp_ring[index]._line = line;
 762 }
 763 #endif /* PRODUCT */
 764 
 765 // Called by flat profiler
 766 // Callers have already called wait_for_ext_suspend_completion
 767 // The assertion for that is currently too complex to put here:
 768 bool JavaThread::profile_last_Java_frame(frame* _fr) {
 769   bool gotframe = false;
 770   // self suspension saves needed state.
 771   if (has_last_Java_frame() && _anchor.walkable()) {
 772      *_fr = pd_last_frame();
 773      gotframe = true;
 774   }
 775   return gotframe;
 776 }
 777 
 778 void Thread::interrupt(Thread* thread) {
 779   trace("interrupt", thread);
 780   debug_only(check_for_dangling_thread_pointer(thread);)
 781   os::interrupt(thread);
 782 }
 783 
 784 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
 785   trace("is_interrupted", thread);
 786   debug_only(check_for_dangling_thread_pointer(thread);)
 787   // Note:  If clear_interrupted==false, this simply fetches and
 788   // returns the value of the field osthread()->interrupted().
 789   return os::is_interrupted(thread, clear_interrupted);
 790 }
 791 
 792 
 793 // GC Support
 794 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
 795   jint thread_parity = _oops_do_parity;
 796   if (thread_parity != strong_roots_parity) {
 797     jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
 798     if (res == thread_parity) {
 799       return true;
 800     } else {
 801       guarantee(res == strong_roots_parity, "Or else what?");
 802       assert(SharedHeap::heap()->workers()->active_workers() > 0,
 803          "Should only fail when parallel.");
 804       return false;
 805     }
 806   }
 807   assert(SharedHeap::heap()->workers()->active_workers() > 0,
 808          "Should only fail when parallel.");
 809   return false;
 810 }
 811 
 812 void Thread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
 813   active_handles()->oops_do(f);
 814   // Do oop for ThreadShadow
 815   f->do_oop((oop*)&_pending_exception);
 816   handle_area()->oops_do(f);
 817 }
 818 
 819 void Thread::nmethods_do(CodeBlobClosure* cf) {
 820   // no nmethods in a generic thread...
 821 }
 822 
 823 void Thread::metadata_do(void f(Metadata*)) {
 824   if (metadata_handles() != NULL) {
 825     for (int i = 0; i< metadata_handles()->length(); i++) {
 826       f(metadata_handles()->at(i));
 827     }
 828   }
 829 }
 830 
 831 void Thread::print_on(outputStream* st) const {
 832   // get_priority assumes osthread initialized
 833   if (osthread() != NULL) {
 834     int os_prio;
 835     if (os::get_native_priority(this, &os_prio) == OS_OK) {
 836       st->print("os_prio=%d ", os_prio);
 837     }
 838     st->print("tid=" INTPTR_FORMAT " ", this);
 839     osthread()->print_on(st);
 840   }
 841   debug_only(if (WizardMode) print_owned_locks_on(st);)
 842 }
 843 
 844 // Thread::print_on_error() is called by fatal error handler. Don't use
 845 // any lock or allocate memory.
 846 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
 847   if      (is_VM_thread())                  st->print("VMThread");
 848   else if (is_Compiler_thread())            st->print("CompilerThread");
 849   else if (is_Java_thread())                st->print("JavaThread");
 850   else if (is_GC_task_thread())             st->print("GCTaskThread");
 851   else if (is_Watcher_thread())             st->print("WatcherThread");
 852   else if (is_ConcurrentGC_thread())        st->print("ConcurrentGCThread");
 853   else st->print("Thread");
 854 
 855   st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
 856             _stack_base - _stack_size, _stack_base);
 857 
 858   if (osthread()) {
 859     st->print(" [id=%d]", osthread()->thread_id());
 860   }
 861 }
 862 
 863 #ifdef ASSERT
 864 void Thread::print_owned_locks_on(outputStream* st) const {
 865   Monitor *cur = _owned_locks;
 866   if (cur == NULL) {
 867     st->print(" (no locks) ");
 868   } else {
 869     st->print_cr(" Locks owned:");
 870     while(cur) {
 871       cur->print_on(st);
 872       cur = cur->next();
 873     }
 874   }
 875 }
 876 
 877 static int ref_use_count  = 0;
 878 
 879 bool Thread::owns_locks_but_compiled_lock() const {
 880   for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 881     if (cur != Compile_lock) return true;
 882   }
 883   return false;
 884 }
 885 
 886 
 887 #endif
 888 
 889 #ifndef PRODUCT
 890 
 891 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
 892 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
 893 // no threads which allow_vm_block's are held
 894 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
 895     // Check if current thread is allowed to block at a safepoint
 896     if (!(_allow_safepoint_count == 0))
 897       fatal("Possible safepoint reached by thread that does not allow it");
 898     if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
 899       fatal("LEAF method calling lock?");
 900     }
 901 
 902 #ifdef ASSERT
 903     if (potential_vm_operation && is_Java_thread()
 904         && !Universe::is_bootstrapping()) {
 905       // Make sure we do not hold any locks that the VM thread also uses.
 906       // This could potentially lead to deadlocks
 907       for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 908         // Threads_lock is special, since the safepoint synchronization will not start before this is
 909         // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
 910         // since it is used to transfer control between JavaThreads and the VMThread
 911         // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
 912         if ( (cur->allow_vm_block() &&
 913               cur != Threads_lock &&
 914               cur != Compile_lock &&               // Temporary: should not be necessary when we get separate compilation
 915               cur != VMOperationRequest_lock &&
 916               cur != VMOperationQueue_lock) ||
 917               cur->rank() == Mutex::special) {
 918           fatal(err_msg("Thread holding lock at safepoint that vm can block on: %s", cur->name()));
 919         }
 920       }
 921     }
 922 
 923     if (GCALotAtAllSafepoints) {
 924       // We could enter a safepoint here and thus have a gc
 925       InterfaceSupport::check_gc_alot();
 926     }
 927 #endif
 928 }
 929 #endif
 930 
 931 bool Thread::is_in_stack(address adr) const {
 932   assert(Thread::current() == this, "is_in_stack can only be called from current thread");
 933   address end = os::current_stack_pointer();
 934   // Allow non Java threads to call this without stack_base
 935   if (_stack_base == NULL) return true;
 936   if (stack_base() >= adr && adr >= end) return true;
 937 
 938   return false;
 939 }
 940 
 941 
 942 bool Thread::is_in_usable_stack(address adr) const {
 943   size_t stack_guard_size = os::uses_stack_guard_pages() ? (StackYellowPages + StackRedPages) * os::vm_page_size() : 0;
 944   size_t usable_stack_size = _stack_size - stack_guard_size;
 945 
 946   return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
 947 }
 948 
 949 
 950 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
 951 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
 952 // used for compilation in the future. If that change is made, the need for these methods
 953 // should be revisited, and they should be removed if possible.
 954 
 955 bool Thread::is_lock_owned(address adr) const {
 956   return on_local_stack(adr);
 957 }
 958 
 959 bool Thread::set_as_starting_thread() {
 960  // NOTE: this must be called inside the main thread.
 961   return os::create_main_thread((JavaThread*)this);
 962 }
 963 
 964 static void initialize_class(Symbol* class_name, TRAPS) {
 965   Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
 966   InstanceKlass::cast(klass)->initialize(CHECK);
 967 }
 968 
 969 
 970 // Creates the initial ThreadGroup
 971 static Handle create_initial_thread_group(TRAPS) {
 972   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
 973   instanceKlassHandle klass (THREAD, k);
 974 
 975   Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
 976   {
 977     JavaValue result(T_VOID);
 978     JavaCalls::call_special(&result,
 979                             system_instance,
 980                             klass,
 981                             vmSymbols::object_initializer_name(),
 982                             vmSymbols::void_method_signature(),
 983                             CHECK_NH);
 984   }
 985   Universe::set_system_thread_group(system_instance());
 986 
 987   Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
 988   {
 989     JavaValue result(T_VOID);
 990     Handle string = java_lang_String::create_from_str("main", CHECK_NH);
 991     JavaCalls::call_special(&result,
 992                             main_instance,
 993                             klass,
 994                             vmSymbols::object_initializer_name(),
 995                             vmSymbols::threadgroup_string_void_signature(),
 996                             system_instance,
 997                             string,
 998                             CHECK_NH);
 999   }
1000   return main_instance;
1001 }
1002 
1003 // Creates the initial Thread
1004 static oop create_initial_thread(Handle thread_group, JavaThread* thread, TRAPS) {
1005   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
1006   instanceKlassHandle klass (THREAD, k);
1007   instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
1008 
1009   java_lang_Thread::set_thread(thread_oop(), thread);
1010   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1011   thread->set_threadObj(thread_oop());
1012 
1013   Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1014 
1015   JavaValue result(T_VOID);
1016   JavaCalls::call_special(&result, thread_oop,
1017                                    klass,
1018                                    vmSymbols::object_initializer_name(),
1019                                    vmSymbols::threadgroup_string_void_signature(),
1020                                    thread_group,
1021                                    string,
1022                                    CHECK_NULL);
1023   return thread_oop();
1024 }
1025 
1026 static void call_initializeSystemClass(TRAPS) {
1027   Klass* k =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1028   instanceKlassHandle klass (THREAD, k);
1029 
1030   JavaValue result(T_VOID);
1031   JavaCalls::call_static(&result, klass, vmSymbols::initializeSystemClass_name(),
1032                                          vmSymbols::void_method_signature(), CHECK);
1033 }
1034 
1035 char java_runtime_name[128] = "";
1036 char java_runtime_version[128] = "";
1037 
1038 // extract the JRE name from sun.misc.Version.java_runtime_name
1039 static const char* get_java_runtime_name(TRAPS) {
1040   Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(),
1041                                       Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1042   fieldDescriptor fd;
1043   bool found = k != NULL &&
1044                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1045                                                         vmSymbols::string_signature(), &fd);
1046   if (found) {
1047     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1048     if (name_oop == NULL)
1049       return NULL;
1050     const char* name = java_lang_String::as_utf8_string(name_oop,
1051                                                         java_runtime_name,
1052                                                         sizeof(java_runtime_name));
1053     return name;
1054   } else {
1055     return NULL;
1056   }
1057 }
1058 
1059 // extract the JRE version from sun.misc.Version.java_runtime_version
1060 static const char* get_java_runtime_version(TRAPS) {
1061   Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(),
1062                                       Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1063   fieldDescriptor fd;
1064   bool found = k != NULL &&
1065                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1066                                                         vmSymbols::string_signature(), &fd);
1067   if (found) {
1068     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1069     if (name_oop == NULL)
1070       return NULL;
1071     const char* name = java_lang_String::as_utf8_string(name_oop,
1072                                                         java_runtime_version,
1073                                                         sizeof(java_runtime_version));
1074     return name;
1075   } else {
1076     return NULL;
1077   }
1078 }
1079 
1080 // General purpose hook into Java code, run once when the VM is initialized.
1081 // The Java library method itself may be changed independently from the VM.
1082 static void call_postVMInitHook(TRAPS) {
1083   Klass* k = SystemDictionary::resolve_or_null(vmSymbols::sun_misc_PostVMInitHook(), THREAD);
1084   instanceKlassHandle klass (THREAD, k);
1085   if (klass.not_null()) {
1086     JavaValue result(T_VOID);
1087     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1088                                            vmSymbols::void_method_signature(),
1089                                            CHECK);
1090   }
1091 }
1092 
1093 static void reset_vm_info_property(TRAPS) {
1094   // the vm info string
1095   ResourceMark rm(THREAD);
1096   const char *vm_info = VM_Version::vm_info_string();
1097 
1098   // java.lang.System class
1099   Klass* k =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1100   instanceKlassHandle klass (THREAD, k);
1101 
1102   // setProperty arguments
1103   Handle key_str    = java_lang_String::create_from_str("java.vm.info", CHECK);
1104   Handle value_str  = java_lang_String::create_from_str(vm_info, CHECK);
1105 
1106   // return value
1107   JavaValue r(T_OBJECT);
1108 
1109   // public static String setProperty(String key, String value);
1110   JavaCalls::call_static(&r,
1111                          klass,
1112                          vmSymbols::setProperty_name(),
1113                          vmSymbols::string_string_string_signature(),
1114                          key_str,
1115                          value_str,
1116                          CHECK);
1117 }
1118 
1119 
1120 void JavaThread::allocate_threadObj(Handle thread_group, char* thread_name, bool daemon, TRAPS) {
1121   assert(thread_group.not_null(), "thread group should be specified");
1122   assert(threadObj() == NULL, "should only create Java thread object once");
1123 
1124   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1125   instanceKlassHandle klass (THREAD, k);
1126   instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1127 
1128   java_lang_Thread::set_thread(thread_oop(), this);
1129   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1130   set_threadObj(thread_oop());
1131 
1132   JavaValue result(T_VOID);
1133   if (thread_name != NULL) {
1134     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1135     // Thread gets assigned specified name and null target
1136     JavaCalls::call_special(&result,
1137                             thread_oop,
1138                             klass,
1139                             vmSymbols::object_initializer_name(),
1140                             vmSymbols::threadgroup_string_void_signature(),
1141                             thread_group, // Argument 1
1142                             name,         // Argument 2
1143                             THREAD);
1144   } else {
1145     // Thread gets assigned name "Thread-nnn" and null target
1146     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1147     JavaCalls::call_special(&result,
1148                             thread_oop,
1149                             klass,
1150                             vmSymbols::object_initializer_name(),
1151                             vmSymbols::threadgroup_runnable_void_signature(),
1152                             thread_group, // Argument 1
1153                             Handle(),     // Argument 2
1154                             THREAD);
1155   }
1156 
1157 
1158   if (daemon) {
1159       java_lang_Thread::set_daemon(thread_oop());
1160   }
1161 
1162   if (HAS_PENDING_EXCEPTION) {
1163     return;
1164   }
1165 
1166   KlassHandle group(this, SystemDictionary::ThreadGroup_klass());
1167   Handle threadObj(this, this->threadObj());
1168 
1169   JavaCalls::call_special(&result,
1170                          thread_group,
1171                          group,
1172                          vmSymbols::add_method_name(),
1173                          vmSymbols::thread_void_signature(),
1174                          threadObj,          // Arg 1
1175                          THREAD);
1176 
1177 
1178 }
1179 
1180 // NamedThread --  non-JavaThread subclasses with multiple
1181 // uniquely named instances should derive from this.
1182 NamedThread::NamedThread() : Thread() {
1183   _name = NULL;
1184   _processed_thread = NULL;
1185 }
1186 
1187 NamedThread::~NamedThread() {
1188   if (_name != NULL) {
1189     FREE_C_HEAP_ARRAY(char, _name, mtThread);
1190     _name = NULL;
1191   }
1192 }
1193 
1194 void NamedThread::set_name(const char* format, ...) {
1195   guarantee(_name == NULL, "Only get to set name once.");
1196   _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1197   guarantee(_name != NULL, "alloc failure");
1198   va_list ap;
1199   va_start(ap, format);
1200   jio_vsnprintf(_name, max_name_len, format, ap);
1201   va_end(ap);
1202 }
1203 
1204 void NamedThread::print_on(outputStream* st) const {
1205   st->print("\"%s\" ", name());
1206   Thread::print_on(st);
1207   st->cr();
1208 }
1209 
1210 
1211 // ======= WatcherThread ========
1212 
1213 // The watcher thread exists to simulate timer interrupts.  It should
1214 // be replaced by an abstraction over whatever native support for
1215 // timer interrupts exists on the platform.
1216 
1217 WatcherThread* WatcherThread::_watcher_thread   = NULL;
1218 bool WatcherThread::_startable = false;
1219 volatile bool  WatcherThread::_should_terminate = false;
1220 
1221 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) {
1222   assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1223   if (os::create_thread(this, os::watcher_thread)) {
1224     _watcher_thread = this;
1225 
1226     // Set the watcher thread to the highest OS priority which should not be
1227     // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1228     // is created. The only normal thread using this priority is the reference
1229     // handler thread, which runs for very short intervals only.
1230     // If the VMThread's priority is not lower than the WatcherThread profiling
1231     // will be inaccurate.
1232     os::set_priority(this, MaxPriority);
1233     if (!DisableStartThread) {
1234       os::start_thread(this);
1235     }
1236   }
1237 }
1238 
1239 int WatcherThread::sleep() const {
1240   MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1241 
1242   // remaining will be zero if there are no tasks,
1243   // causing the WatcherThread to sleep until a task is
1244   // enrolled
1245   int remaining = PeriodicTask::time_to_wait();
1246   int time_slept = 0;
1247 
1248   // we expect this to timeout - we only ever get unparked when
1249   // we should terminate or when a new task has been enrolled
1250   OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1251 
1252   jlong time_before_loop = os::javaTimeNanos();
1253 
1254   for (;;) {
1255     bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, remaining);
1256     jlong now = os::javaTimeNanos();
1257 
1258     if (remaining == 0) {
1259         // if we didn't have any tasks we could have waited for a long time
1260         // consider the time_slept zero and reset time_before_loop
1261         time_slept = 0;
1262         time_before_loop = now;
1263     } else {
1264         // need to recalculate since we might have new tasks in _tasks
1265         time_slept = (int) ((now - time_before_loop) / 1000000);
1266     }
1267 
1268     // Change to task list or spurious wakeup of some kind
1269     if (timedout || _should_terminate) {
1270         break;
1271     }
1272 
1273     remaining = PeriodicTask::time_to_wait();
1274     if (remaining == 0) {
1275         // Last task was just disenrolled so loop around and wait until
1276         // another task gets enrolled
1277         continue;
1278     }
1279 
1280     remaining -= time_slept;
1281     if (remaining <= 0)
1282       break;
1283   }
1284 
1285   return time_slept;
1286 }
1287 
1288 void WatcherThread::run() {
1289   assert(this == watcher_thread(), "just checking");
1290 
1291   this->record_stack_base_and_size();
1292   this->initialize_thread_local_storage();
1293   this->set_active_handles(JNIHandleBlock::allocate_block());
1294   while(!_should_terminate) {
1295     assert(watcher_thread() == Thread::current(),  "thread consistency check");
1296     assert(watcher_thread() == this,  "thread consistency check");
1297 
1298     // Calculate how long it'll be until the next PeriodicTask work
1299     // should be done, and sleep that amount of time.
1300     int time_waited = sleep();
1301 
1302     if (is_error_reported()) {
1303       // A fatal error has happened, the error handler(VMError::report_and_die)
1304       // should abort JVM after creating an error log file. However in some
1305       // rare cases, the error handler itself might deadlock. Here we try to
1306       // kill JVM if the fatal error handler fails to abort in 2 minutes.
1307       //
1308       // This code is in WatcherThread because WatcherThread wakes up
1309       // periodically so the fatal error handler doesn't need to do anything;
1310       // also because the WatcherThread is less likely to crash than other
1311       // threads.
1312 
1313       for (;;) {
1314         if (!ShowMessageBoxOnError
1315          && (OnError == NULL || OnError[0] == '\0')
1316          && Arguments::abort_hook() == NULL) {
1317              os::sleep(this, 2 * 60 * 1000, false);
1318              fdStream err(defaultStream::output_fd());
1319              err.print_raw_cr("# [ timer expired, abort... ]");
1320              // skip atexit/vm_exit/vm_abort hooks
1321              os::die();
1322         }
1323 
1324         // Wake up 5 seconds later, the fatal handler may reset OnError or
1325         // ShowMessageBoxOnError when it is ready to abort.
1326         os::sleep(this, 5 * 1000, false);
1327       }
1328     }
1329 
1330     PeriodicTask::real_time_tick(time_waited);
1331   }
1332 
1333   // Signal that it is terminated
1334   {
1335     MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1336     _watcher_thread = NULL;
1337     Terminator_lock->notify();
1338   }
1339 
1340   // Thread destructor usually does this..
1341   ThreadLocalStorage::set_thread(NULL);
1342 }
1343 
1344 void WatcherThread::start() {
1345   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1346 
1347   if (watcher_thread() == NULL && _startable) {
1348     _should_terminate = false;
1349     // Create the single instance of WatcherThread
1350     new WatcherThread();
1351   }
1352 }
1353 
1354 void WatcherThread::make_startable() {
1355   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1356   _startable = true;
1357 }
1358 
1359 void WatcherThread::stop() {
1360   {
1361     MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1362     _should_terminate = true;
1363     OrderAccess::fence();  // ensure WatcherThread sees update in main loop
1364 
1365     WatcherThread* watcher = watcher_thread();
1366     if (watcher != NULL)
1367       watcher->unpark();
1368   }
1369 
1370   // it is ok to take late safepoints here, if needed
1371   MutexLocker mu(Terminator_lock);
1372 
1373   while(watcher_thread() != NULL) {
1374     // This wait should make safepoint checks, wait without a timeout,
1375     // and wait as a suspend-equivalent condition.
1376     //
1377     // Note: If the FlatProfiler is running, then this thread is waiting
1378     // for the WatcherThread to terminate and the WatcherThread, via the
1379     // FlatProfiler task, is waiting for the external suspend request on
1380     // this thread to complete. wait_for_ext_suspend_completion() will
1381     // eventually timeout, but that takes time. Making this wait a
1382     // suspend-equivalent condition solves that timeout problem.
1383     //
1384     Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1385                           Mutex::_as_suspend_equivalent_flag);
1386   }
1387 }
1388 
1389 void WatcherThread::unpark() {
1390   MutexLockerEx ml(PeriodicTask_lock->owned_by_self() ? NULL : PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1391   PeriodicTask_lock->notify();
1392 }
1393 
1394 void WatcherThread::print_on(outputStream* st) const {
1395   st->print("\"%s\" ", name());
1396   Thread::print_on(st);
1397   st->cr();
1398 }
1399 
1400 // ======= JavaThread ========
1401 
1402 // A JavaThread is a normal Java thread
1403 
1404 void JavaThread::initialize() {
1405   // Initialize fields
1406 
1407   // Set the claimed par_id to UINT_MAX (ie not claiming any par_ids)
1408   set_claimed_par_id(UINT_MAX);
1409 
1410   set_saved_exception_pc(NULL);
1411   set_threadObj(NULL);
1412   _anchor.clear();
1413   set_entry_point(NULL);
1414   set_jni_functions(jni_functions());
1415   set_callee_target(NULL);
1416   set_vm_result(NULL);
1417   set_vm_result_2(NULL);
1418   set_vframe_array_head(NULL);
1419   set_vframe_array_last(NULL);
1420   set_deferred_locals(NULL);
1421   set_deopt_mark(NULL);
1422   set_deopt_nmethod(NULL);
1423   clear_must_deopt_id();
1424   set_monitor_chunks(NULL);
1425   set_next(NULL);
1426   set_thread_state(_thread_new);
1427 #if INCLUDE_NMT
1428   set_recorder(NULL);
1429 #endif
1430   _terminated = _not_terminated;
1431   _privileged_stack_top = NULL;
1432   _array_for_gc = NULL;
1433   _suspend_equivalent = false;
1434   _in_deopt_handler = 0;
1435   _doing_unsafe_access = false;
1436   _stack_guard_state = stack_guard_unused;
1437   (void)const_cast<oop&>(_exception_oop = NULL);
1438   _exception_pc  = 0;
1439   _exception_handler_pc = 0;
1440   _is_method_handle_return = 0;
1441   _jvmti_thread_state= NULL;
1442   _should_post_on_exceptions_flag = JNI_FALSE;
1443   _jvmti_get_loaded_classes_closure = NULL;
1444   _interp_only_mode    = 0;
1445   _special_runtime_exit_condition = _no_async_condition;
1446   _pending_async_exception = NULL;
1447   _thread_stat = NULL;
1448   _thread_stat = new ThreadStatistics();
1449   _blocked_on_compilation = false;
1450   _jni_active_critical = 0;
1451   _do_not_unlock_if_synchronized = false;
1452   _cached_monitor_info = NULL;
1453   _parker = Parker::Allocate(this) ;
1454 
1455 #ifndef PRODUCT
1456   _jmp_ring_index = 0;
1457   for (int ji = 0 ; ji < jump_ring_buffer_size ; ji++ ) {
1458     record_jump(NULL, NULL, NULL, 0);
1459   }
1460 #endif /* PRODUCT */
1461 
1462   set_thread_profiler(NULL);
1463   if (FlatProfiler::is_active()) {
1464     // This is where we would decide to either give each thread it's own profiler
1465     // or use one global one from FlatProfiler,
1466     // or up to some count of the number of profiled threads, etc.
1467     ThreadProfiler* pp = new ThreadProfiler();
1468     pp->engage();
1469     set_thread_profiler(pp);
1470   }
1471 
1472   // Setup safepoint state info for this thread
1473   ThreadSafepointState::create(this);
1474 
1475   debug_only(_java_call_counter = 0);
1476 
1477   // JVMTI PopFrame support
1478   _popframe_condition = popframe_inactive;
1479   _popframe_preserved_args = NULL;
1480   _popframe_preserved_args_size = 0;
1481 
1482   pd_initialize();
1483 }
1484 
1485 #if INCLUDE_ALL_GCS
1486 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1487 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1488 #endif // INCLUDE_ALL_GCS
1489 
1490 JavaThread::JavaThread(bool is_attaching_via_jni) :
1491   Thread()
1492 #if INCLUDE_ALL_GCS
1493   , _satb_mark_queue(&_satb_mark_queue_set),
1494   _dirty_card_queue(&_dirty_card_queue_set)
1495 #endif // INCLUDE_ALL_GCS
1496 {
1497   initialize();
1498   if (is_attaching_via_jni) {
1499     _jni_attach_state = _attaching_via_jni;
1500   } else {
1501     _jni_attach_state = _not_attaching_via_jni;
1502   }
1503   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1504   _safepoint_visible = false;
1505 }
1506 
1507 bool JavaThread::reguard_stack(address cur_sp) {
1508   if (_stack_guard_state != stack_guard_yellow_disabled) {
1509     return true; // Stack already guarded or guard pages not needed.
1510   }
1511 
1512   if (register_stack_overflow()) {
1513     // For those architectures which have separate register and
1514     // memory stacks, we must check the register stack to see if
1515     // it has overflowed.
1516     return false;
1517   }
1518 
1519   // Java code never executes within the yellow zone: the latter is only
1520   // there to provoke an exception during stack banging.  If java code
1521   // is executing there, either StackShadowPages should be larger, or
1522   // some exception code in c1, c2 or the interpreter isn't unwinding
1523   // when it should.
1524   guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages");
1525 
1526   enable_stack_yellow_zone();
1527   return true;
1528 }
1529 
1530 bool JavaThread::reguard_stack(void) {
1531   return reguard_stack(os::current_stack_pointer());
1532 }
1533 
1534 
1535 void JavaThread::block_if_vm_exited() {
1536   if (_terminated == _vm_exited) {
1537     // _vm_exited is set at safepoint, and Threads_lock is never released
1538     // we will block here forever
1539     Threads_lock->lock_without_safepoint_check();
1540     ShouldNotReachHere();
1541   }
1542 }
1543 
1544 
1545 // Remove this ifdef when C1 is ported to the compiler interface.
1546 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1547 
1548 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1549   Thread()
1550 #if INCLUDE_ALL_GCS
1551   , _satb_mark_queue(&_satb_mark_queue_set),
1552   _dirty_card_queue(&_dirty_card_queue_set)
1553 #endif // INCLUDE_ALL_GCS
1554 {
1555   if (TraceThreadEvents) {
1556     tty->print_cr("creating thread %p", this);
1557   }
1558   initialize();
1559   _jni_attach_state = _not_attaching_via_jni;
1560   set_entry_point(entry_point);
1561   // Create the native thread itself.
1562   // %note runtime_23
1563   os::ThreadType thr_type = os::java_thread;
1564   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1565                                                      os::java_thread;
1566   os::create_thread(this, thr_type, stack_sz);
1567   _safepoint_visible = false;
1568   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1569   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1570   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1571   // the exception consists of creating the exception object & initializing it, initialization
1572   // will leave the VM via a JavaCall and then all locks must be unlocked).
1573   //
1574   // The thread is still suspended when we reach here. Thread must be explicit started
1575   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1576   // by calling Threads:add. The reason why this is not done here, is because the thread
1577   // object must be fully initialized (take a look at JVM_Start)
1578 }
1579 
1580 JavaThread::~JavaThread() {
1581   if (TraceThreadEvents) {
1582       tty->print_cr("terminate thread %p", this);
1583   }
1584 
1585   // By now, this thread should already be invisible to safepoint,
1586   // and its per-thread recorder also collected.
1587   assert(!is_safepoint_visible(), "wrong state");
1588 #if INCLUDE_NMT
1589   assert(get_recorder() == NULL, "Already collected");
1590 #endif // INCLUDE_NMT
1591 
1592   // JSR166 -- return the parker to the free list
1593   Parker::Release(_parker);
1594   _parker = NULL ;
1595 
1596   // Free any remaining  previous UnrollBlock
1597   vframeArray* old_array = vframe_array_last();
1598 
1599   if (old_array != NULL) {
1600     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1601     old_array->set_unroll_block(NULL);
1602     delete old_info;
1603     delete old_array;
1604   }
1605 
1606   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1607   if (deferred != NULL) {
1608     // This can only happen if thread is destroyed before deoptimization occurs.
1609     assert(deferred->length() != 0, "empty array!");
1610     do {
1611       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1612       deferred->remove_at(0);
1613       // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1614       delete dlv;
1615     } while (deferred->length() != 0);
1616     delete deferred;
1617   }
1618 
1619   // All Java related clean up happens in exit
1620   ThreadSafepointState::destroy(this);
1621   if (_thread_profiler != NULL) delete _thread_profiler;
1622   if (_thread_stat != NULL) delete _thread_stat;
1623 }
1624 
1625 
1626 // The first routine called by a new Java thread
1627 void JavaThread::run() {
1628   // initialize thread-local alloc buffer related fields
1629   this->initialize_tlab();
1630 
1631   // used to test validity of stack trace backs
1632   this->record_base_of_stack_pointer();
1633 
1634   // Record real stack base and size.
1635   this->record_stack_base_and_size();
1636 
1637   // Initialize thread local storage; set before calling MutexLocker
1638   this->initialize_thread_local_storage();
1639 
1640   this->create_stack_guard_pages();
1641 
1642   this->cache_global_variables();
1643 
1644   // Thread is now sufficient initialized to be handled by the safepoint code as being
1645   // in the VM. Change thread state from _thread_new to _thread_in_vm
1646   ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1647 
1648   assert(JavaThread::current() == this, "sanity check");
1649   assert(!Thread::current()->owns_locks(), "sanity check");
1650 
1651   DTRACE_THREAD_PROBE(start, this);
1652 
1653   // This operation might block. We call that after all safepoint checks for a new thread has
1654   // been completed.
1655   this->set_active_handles(JNIHandleBlock::allocate_block());
1656 
1657   if (JvmtiExport::should_post_thread_life()) {
1658     JvmtiExport::post_thread_start(this);
1659   }
1660 
1661   EventThreadStart event;
1662   if (event.should_commit()) {
1663      event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj()));
1664      event.commit();
1665   }
1666 
1667   // We call another function to do the rest so we are sure that the stack addresses used
1668   // from there will be lower than the stack base just computed
1669   thread_main_inner();
1670 
1671   // Note, thread is no longer valid at this point!
1672 }
1673 
1674 
1675 void JavaThread::thread_main_inner() {
1676   assert(JavaThread::current() == this, "sanity check");
1677   assert(this->threadObj() != NULL, "just checking");
1678 
1679   // Execute thread entry point unless this thread has a pending exception
1680   // or has been stopped before starting.
1681   // Note: Due to JVM_StopThread we can have pending exceptions already!
1682   if (!this->has_pending_exception() &&
1683       !java_lang_Thread::is_stillborn(this->threadObj())) {
1684     {
1685       ResourceMark rm(this);
1686       this->set_native_thread_name(this->get_thread_name());
1687     }
1688     HandleMark hm(this);
1689     this->entry_point()(this, this);
1690   }
1691 
1692   DTRACE_THREAD_PROBE(stop, this);
1693 
1694   this->exit(false);
1695   delete this;
1696 }
1697 
1698 
1699 static void ensure_join(JavaThread* thread) {
1700   // We do not need to grap the Threads_lock, since we are operating on ourself.
1701   Handle threadObj(thread, thread->threadObj());
1702   assert(threadObj.not_null(), "java thread object must exist");
1703   ObjectLocker lock(threadObj, thread);
1704   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1705   thread->clear_pending_exception();
1706   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1707   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1708   // Clear the native thread instance - this makes isAlive return false and allows the join()
1709   // to complete once we've done the notify_all below
1710   java_lang_Thread::set_thread(threadObj(), NULL);
1711   lock.notify_all(thread);
1712   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1713   thread->clear_pending_exception();
1714 }
1715 
1716 
1717 // For any new cleanup additions, please check to see if they need to be applied to
1718 // cleanup_failed_attach_current_thread as well.
1719 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1720   assert(this == JavaThread::current(),  "thread consistency check");
1721 
1722   HandleMark hm(this);
1723   Handle uncaught_exception(this, this->pending_exception());
1724   this->clear_pending_exception();
1725   Handle threadObj(this, this->threadObj());
1726   assert(threadObj.not_null(), "Java thread object should be created");
1727 
1728   if (get_thread_profiler() != NULL) {
1729     get_thread_profiler()->disengage();
1730     ResourceMark rm;
1731     get_thread_profiler()->print(get_thread_name());
1732   }
1733 
1734 
1735   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1736   {
1737     EXCEPTION_MARK;
1738 
1739     CLEAR_PENDING_EXCEPTION;
1740   }
1741   // FIXIT: The is_null check is only so it works better on JDK1.2 VM's. This
1742   // has to be fixed by a runtime query method
1743   if (!destroy_vm || JDK_Version::is_jdk12x_version()) {
1744     // JSR-166: change call from from ThreadGroup.uncaughtException to
1745     // java.lang.Thread.dispatchUncaughtException
1746     if (uncaught_exception.not_null()) {
1747       Handle group(this, java_lang_Thread::threadGroup(threadObj()));
1748       {
1749         EXCEPTION_MARK;
1750         // Check if the method Thread.dispatchUncaughtException() exists. If so
1751         // call it.  Otherwise we have an older library without the JSR-166 changes,
1752         // so call ThreadGroup.uncaughtException()
1753         KlassHandle recvrKlass(THREAD, threadObj->klass());
1754         CallInfo callinfo;
1755         KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1756         LinkResolver::resolve_virtual_call(callinfo, threadObj, recvrKlass, thread_klass,
1757                                            vmSymbols::dispatchUncaughtException_name(),
1758                                            vmSymbols::throwable_void_signature(),
1759                                            KlassHandle(), false, false, THREAD);
1760         CLEAR_PENDING_EXCEPTION;
1761         methodHandle method = callinfo.selected_method();
1762         if (method.not_null()) {
1763           JavaValue result(T_VOID);
1764           JavaCalls::call_virtual(&result,
1765                                   threadObj, thread_klass,
1766                                   vmSymbols::dispatchUncaughtException_name(),
1767                                   vmSymbols::throwable_void_signature(),
1768                                   uncaught_exception,
1769                                   THREAD);
1770         } else {
1771           KlassHandle thread_group(THREAD, SystemDictionary::ThreadGroup_klass());
1772           JavaValue result(T_VOID);
1773           JavaCalls::call_virtual(&result,
1774                                   group, thread_group,
1775                                   vmSymbols::uncaughtException_name(),
1776                                   vmSymbols::thread_throwable_void_signature(),
1777                                   threadObj,           // Arg 1
1778                                   uncaught_exception,  // Arg 2
1779                                   THREAD);
1780         }
1781         if (HAS_PENDING_EXCEPTION) {
1782           ResourceMark rm(this);
1783           jio_fprintf(defaultStream::error_stream(),
1784                 "\nException: %s thrown from the UncaughtExceptionHandler"
1785                 " in thread \"%s\"\n",
1786                 pending_exception()->klass()->external_name(),
1787                 get_thread_name());
1788           CLEAR_PENDING_EXCEPTION;
1789         }
1790       }
1791     }
1792 
1793     // Called before the java thread exit since we want to read info
1794     // from java_lang_Thread object
1795     EventThreadEnd event;
1796     if (event.should_commit()) {
1797         event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj()));
1798         event.commit();
1799     }
1800 
1801     // Call after last event on thread
1802     EVENT_THREAD_EXIT(this);
1803 
1804     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1805     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1806     // is deprecated anyhow.
1807     if (!is_Compiler_thread()) {
1808       int count = 3;
1809       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1810         EXCEPTION_MARK;
1811         JavaValue result(T_VOID);
1812         KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1813         JavaCalls::call_virtual(&result,
1814                               threadObj, thread_klass,
1815                               vmSymbols::exit_method_name(),
1816                               vmSymbols::void_method_signature(),
1817                               THREAD);
1818         CLEAR_PENDING_EXCEPTION;
1819       }
1820     }
1821     // notify JVMTI
1822     if (JvmtiExport::should_post_thread_life()) {
1823       JvmtiExport::post_thread_end(this);
1824     }
1825 
1826     // We have notified the agents that we are exiting, before we go on,
1827     // we must check for a pending external suspend request and honor it
1828     // in order to not surprise the thread that made the suspend request.
1829     while (true) {
1830       {
1831         MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1832         if (!is_external_suspend()) {
1833           set_terminated(_thread_exiting);
1834           ThreadService::current_thread_exiting(this);
1835           break;
1836         }
1837         // Implied else:
1838         // Things get a little tricky here. We have a pending external
1839         // suspend request, but we are holding the SR_lock so we
1840         // can't just self-suspend. So we temporarily drop the lock
1841         // and then self-suspend.
1842       }
1843 
1844       ThreadBlockInVM tbivm(this);
1845       java_suspend_self();
1846 
1847       // We're done with this suspend request, but we have to loop around
1848       // and check again. Eventually we will get SR_lock without a pending
1849       // external suspend request and will be able to mark ourselves as
1850       // exiting.
1851     }
1852     // no more external suspends are allowed at this point
1853   } else {
1854     // before_exit() has already posted JVMTI THREAD_END events
1855   }
1856 
1857   // Notify waiters on thread object. This has to be done after exit() is called
1858   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1859   // group should have the destroyed bit set before waiters are notified).
1860   ensure_join(this);
1861   assert(!this->has_pending_exception(), "ensure_join should have cleared");
1862 
1863   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1864   // held by this thread must be released.  A detach operation must only
1865   // get here if there are no Java frames on the stack.  Therefore, any
1866   // owned monitors at this point MUST be JNI-acquired monitors which are
1867   // pre-inflated and in the monitor cache.
1868   //
1869   // ensure_join() ignores IllegalThreadStateExceptions, and so does this.
1870   if (exit_type == jni_detach && JNIDetachReleasesMonitors) {
1871     assert(!this->has_last_Java_frame(), "detaching with Java frames?");
1872     ObjectSynchronizer::release_monitors_owned_by_thread(this);
1873     assert(!this->has_pending_exception(), "release_monitors should have cleared");
1874   }
1875 
1876   // These things needs to be done while we are still a Java Thread. Make sure that thread
1877   // is in a consistent state, in case GC happens
1878   assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1879 
1880   if (active_handles() != NULL) {
1881     JNIHandleBlock* block = active_handles();
1882     set_active_handles(NULL);
1883     JNIHandleBlock::release_block(block);
1884   }
1885 
1886   if (free_handle_block() != NULL) {
1887     JNIHandleBlock* block = free_handle_block();
1888     set_free_handle_block(NULL);
1889     JNIHandleBlock::release_block(block);
1890   }
1891 
1892   // These have to be removed while this is still a valid thread.
1893   remove_stack_guard_pages();
1894 
1895   if (UseTLAB) {
1896     tlab().make_parsable(true);  // retire TLAB
1897   }
1898 
1899   if (JvmtiEnv::environments_might_exist()) {
1900     JvmtiExport::cleanup_thread(this);
1901   }
1902 
1903   // We must flush any deferred card marks before removing a thread from
1904   // the list of active threads.
1905   Universe::heap()->flush_deferred_store_barrier(this);
1906   assert(deferred_card_mark().is_empty(), "Should have been flushed");
1907 
1908 #if INCLUDE_ALL_GCS
1909   // We must flush the G1-related buffers before removing a thread
1910   // from the list of active threads. We must do this after any deferred
1911   // card marks have been flushed (above) so that any entries that are
1912   // added to the thread's dirty card queue as a result are not lost.
1913   if (UseG1GC) {
1914     flush_barrier_queues();
1915   }
1916 #endif // INCLUDE_ALL_GCS
1917 
1918   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1919   Threads::remove(this);
1920 }
1921 
1922 #if INCLUDE_ALL_GCS
1923 // Flush G1-related queues.
1924 void JavaThread::flush_barrier_queues() {
1925   satb_mark_queue().flush();
1926   dirty_card_queue().flush();
1927 }
1928 
1929 void JavaThread::initialize_queues() {
1930   assert(!SafepointSynchronize::is_at_safepoint(),
1931          "we should not be at a safepoint");
1932 
1933   ObjPtrQueue& satb_queue = satb_mark_queue();
1934   SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1935   // The SATB queue should have been constructed with its active
1936   // field set to false.
1937   assert(!satb_queue.is_active(), "SATB queue should not be active");
1938   assert(satb_queue.is_empty(), "SATB queue should be empty");
1939   // If we are creating the thread during a marking cycle, we should
1940   // set the active field of the SATB queue to true.
1941   if (satb_queue_set.is_active()) {
1942     satb_queue.set_active(true);
1943   }
1944 
1945   DirtyCardQueue& dirty_queue = dirty_card_queue();
1946   // The dirty card queue should have been constructed with its
1947   // active field set to true.
1948   assert(dirty_queue.is_active(), "dirty card queue should be active");
1949 }
1950 #endif // INCLUDE_ALL_GCS
1951 
1952 void JavaThread::cleanup_failed_attach_current_thread() {
1953   if (get_thread_profiler() != NULL) {
1954     get_thread_profiler()->disengage();
1955     ResourceMark rm;
1956     get_thread_profiler()->print(get_thread_name());
1957   }
1958 
1959   if (active_handles() != NULL) {
1960     JNIHandleBlock* block = active_handles();
1961     set_active_handles(NULL);
1962     JNIHandleBlock::release_block(block);
1963   }
1964 
1965   if (free_handle_block() != NULL) {
1966     JNIHandleBlock* block = free_handle_block();
1967     set_free_handle_block(NULL);
1968     JNIHandleBlock::release_block(block);
1969   }
1970 
1971   // These have to be removed while this is still a valid thread.
1972   remove_stack_guard_pages();
1973 
1974   if (UseTLAB) {
1975     tlab().make_parsable(true);  // retire TLAB, if any
1976   }
1977 
1978 #if INCLUDE_ALL_GCS
1979   if (UseG1GC) {
1980     flush_barrier_queues();
1981   }
1982 #endif // INCLUDE_ALL_GCS
1983 
1984   Threads::remove(this);
1985   delete this;
1986 }
1987 
1988 
1989 
1990 
1991 JavaThread* JavaThread::active() {
1992   Thread* thread = ThreadLocalStorage::thread();
1993   assert(thread != NULL, "just checking");
1994   if (thread->is_Java_thread()) {
1995     return (JavaThread*) thread;
1996   } else {
1997     assert(thread->is_VM_thread(), "this must be a vm thread");
1998     VM_Operation* op = ((VMThread*) thread)->vm_operation();
1999     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2000     assert(ret->is_Java_thread(), "must be a Java thread");
2001     return ret;
2002   }
2003 }
2004 
2005 bool JavaThread::is_lock_owned(address adr) const {
2006   if (Thread::is_lock_owned(adr)) return true;
2007 
2008   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2009     if (chunk->contains(adr)) return true;
2010   }
2011 
2012   return false;
2013 }
2014 
2015 
2016 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2017   chunk->set_next(monitor_chunks());
2018   set_monitor_chunks(chunk);
2019 }
2020 
2021 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2022   guarantee(monitor_chunks() != NULL, "must be non empty");
2023   if (monitor_chunks() == chunk) {
2024     set_monitor_chunks(chunk->next());
2025   } else {
2026     MonitorChunk* prev = monitor_chunks();
2027     while (prev->next() != chunk) prev = prev->next();
2028     prev->set_next(chunk->next());
2029   }
2030 }
2031 
2032 // JVM support.
2033 
2034 // Note: this function shouldn't block if it's called in
2035 // _thread_in_native_trans state (such as from
2036 // check_special_condition_for_native_trans()).
2037 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2038 
2039   if (has_last_Java_frame() && has_async_condition()) {
2040     // If we are at a polling page safepoint (not a poll return)
2041     // then we must defer async exception because live registers
2042     // will be clobbered by the exception path. Poll return is
2043     // ok because the call we a returning from already collides
2044     // with exception handling registers and so there is no issue.
2045     // (The exception handling path kills call result registers but
2046     //  this is ok since the exception kills the result anyway).
2047 
2048     if (is_at_poll_safepoint()) {
2049       // if the code we are returning to has deoptimized we must defer
2050       // the exception otherwise live registers get clobbered on the
2051       // exception path before deoptimization is able to retrieve them.
2052       //
2053       RegisterMap map(this, false);
2054       frame caller_fr = last_frame().sender(&map);
2055       assert(caller_fr.is_compiled_frame(), "what?");
2056       if (caller_fr.is_deoptimized_frame()) {
2057         if (TraceExceptions) {
2058           ResourceMark rm;
2059           tty->print_cr("deferred async exception at compiled safepoint");
2060         }
2061         return;
2062       }
2063     }
2064   }
2065 
2066   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2067   if (condition == _no_async_condition) {
2068     // Conditions have changed since has_special_runtime_exit_condition()
2069     // was called:
2070     // - if we were here only because of an external suspend request,
2071     //   then that was taken care of above (or cancelled) so we are done
2072     // - if we were here because of another async request, then it has
2073     //   been cleared between the has_special_runtime_exit_condition()
2074     //   and now so again we are done
2075     return;
2076   }
2077 
2078   // Check for pending async. exception
2079   if (_pending_async_exception != NULL) {
2080     // Only overwrite an already pending exception, if it is not a threadDeath.
2081     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2082 
2083       // We cannot call Exceptions::_throw(...) here because we cannot block
2084       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2085 
2086       if (TraceExceptions) {
2087         ResourceMark rm;
2088         tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this);
2089         if (has_last_Java_frame() ) {
2090           frame f = last_frame();
2091           tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp());
2092         }
2093         tty->print_cr(" of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2094       }
2095       _pending_async_exception = NULL;
2096       clear_has_async_exception();
2097     }
2098   }
2099 
2100   if (check_unsafe_error &&
2101       condition == _async_unsafe_access_error && !has_pending_exception()) {
2102     condition = _no_async_condition;  // done
2103     switch (thread_state()) {
2104     case _thread_in_vm:
2105       {
2106         JavaThread* THREAD = this;
2107         THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2108       }
2109     case _thread_in_native:
2110       {
2111         ThreadInVMfromNative tiv(this);
2112         JavaThread* THREAD = this;
2113         THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2114       }
2115     case _thread_in_Java:
2116       {
2117         ThreadInVMfromJava tiv(this);
2118         JavaThread* THREAD = this;
2119         THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2120       }
2121     default:
2122       ShouldNotReachHere();
2123     }
2124   }
2125 
2126   assert(condition == _no_async_condition || has_pending_exception() ||
2127          (!check_unsafe_error && condition == _async_unsafe_access_error),
2128          "must have handled the async condition, if no exception");
2129 }
2130 
2131 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2132   //
2133   // Check for pending external suspend. Internal suspend requests do
2134   // not use handle_special_runtime_exit_condition().
2135   // If JNIEnv proxies are allowed, don't self-suspend if the target
2136   // thread is not the current thread. In older versions of jdbx, jdbx
2137   // threads could call into the VM with another thread's JNIEnv so we
2138   // can be here operating on behalf of a suspended thread (4432884).
2139   bool do_self_suspend = is_external_suspend_with_lock();
2140   if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2141     //
2142     // Because thread is external suspended the safepoint code will count
2143     // thread as at a safepoint. This can be odd because we can be here
2144     // as _thread_in_Java which would normally transition to _thread_blocked
2145     // at a safepoint. We would like to mark the thread as _thread_blocked
2146     // before calling java_suspend_self like all other callers of it but
2147     // we must then observe proper safepoint protocol. (We can't leave
2148     // _thread_blocked with a safepoint in progress). However we can be
2149     // here as _thread_in_native_trans so we can't use a normal transition
2150     // constructor/destructor pair because they assert on that type of
2151     // transition. We could do something like:
2152     //
2153     // JavaThreadState state = thread_state();
2154     // set_thread_state(_thread_in_vm);
2155     // {
2156     //   ThreadBlockInVM tbivm(this);
2157     //   java_suspend_self()
2158     // }
2159     // set_thread_state(_thread_in_vm_trans);
2160     // if (safepoint) block;
2161     // set_thread_state(state);
2162     //
2163     // but that is pretty messy. Instead we just go with the way the
2164     // code has worked before and note that this is the only path to
2165     // java_suspend_self that doesn't put the thread in _thread_blocked
2166     // mode.
2167 
2168     frame_anchor()->make_walkable(this);
2169     java_suspend_self();
2170 
2171     // We might be here for reasons in addition to the self-suspend request
2172     // so check for other async requests.
2173   }
2174 
2175   if (check_asyncs) {
2176     check_and_handle_async_exceptions();
2177   }
2178 }
2179 
2180 void JavaThread::send_thread_stop(oop java_throwable)  {
2181   assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2182   assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2183   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2184 
2185   // Do not throw asynchronous exceptions against the compiler thread
2186   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2187   if (is_Compiler_thread()) return;
2188 
2189   {
2190     // Actually throw the Throwable against the target Thread - however
2191     // only if there is no thread death exception installed already.
2192     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2193       // If the topmost frame is a runtime stub, then we are calling into
2194       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2195       // must deoptimize the caller before continuing, as the compiled  exception handler table
2196       // may not be valid
2197       if (has_last_Java_frame()) {
2198         frame f = last_frame();
2199         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2200           // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2201           RegisterMap reg_map(this, UseBiasedLocking);
2202           frame compiled_frame = f.sender(&reg_map);
2203           if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2204             Deoptimization::deoptimize(this, compiled_frame, &reg_map);
2205           }
2206         }
2207       }
2208 
2209       // Set async. pending exception in thread.
2210       set_pending_async_exception(java_throwable);
2211 
2212       if (TraceExceptions) {
2213        ResourceMark rm;
2214        tty->print_cr("Pending Async. exception installed of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2215       }
2216       // for AbortVMOnException flag
2217       NOT_PRODUCT(Exceptions::debug_check_abort(InstanceKlass::cast(_pending_async_exception->klass())->external_name()));
2218     }
2219   }
2220 
2221 
2222   // Interrupt thread so it will wake up from a potential wait()
2223   Thread::interrupt(this);
2224 }
2225 
2226 // External suspension mechanism.
2227 //
2228 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2229 // to any VM_locks and it is at a transition
2230 // Self-suspension will happen on the transition out of the vm.
2231 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2232 //
2233 // Guarantees on return:
2234 //   + Target thread will not execute any new bytecode (that's why we need to
2235 //     force a safepoint)
2236 //   + Target thread will not enter any new monitors
2237 //
2238 void JavaThread::java_suspend() {
2239   { MutexLocker mu(Threads_lock);
2240     if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2241        return;
2242     }
2243   }
2244 
2245   { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2246     if (!is_external_suspend()) {
2247       // a racing resume has cancelled us; bail out now
2248       return;
2249     }
2250 
2251     // suspend is done
2252     uint32_t debug_bits = 0;
2253     // Warning: is_ext_suspend_completed() may temporarily drop the
2254     // SR_lock to allow the thread to reach a stable thread state if
2255     // it is currently in a transient thread state.
2256     if (is_ext_suspend_completed(false /* !called_by_wait */,
2257                                  SuspendRetryDelay, &debug_bits) ) {
2258       return;
2259     }
2260   }
2261 
2262   VM_ForceSafepoint vm_suspend;
2263   VMThread::execute(&vm_suspend);
2264 }
2265 
2266 // Part II of external suspension.
2267 // A JavaThread self suspends when it detects a pending external suspend
2268 // request. This is usually on transitions. It is also done in places
2269 // where continuing to the next transition would surprise the caller,
2270 // e.g., monitor entry.
2271 //
2272 // Returns the number of times that the thread self-suspended.
2273 //
2274 // Note: DO NOT call java_suspend_self() when you just want to block current
2275 //       thread. java_suspend_self() is the second stage of cooperative
2276 //       suspension for external suspend requests and should only be used
2277 //       to complete an external suspend request.
2278 //
2279 int JavaThread::java_suspend_self() {
2280   int ret = 0;
2281 
2282   // we are in the process of exiting so don't suspend
2283   if (is_exiting()) {
2284      clear_external_suspend();
2285      return ret;
2286   }
2287 
2288   assert(_anchor.walkable() ||
2289     (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2290     "must have walkable stack");
2291 
2292   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2293 
2294   assert(!this->is_ext_suspended(),
2295     "a thread trying to self-suspend should not already be suspended");
2296 
2297   if (this->is_suspend_equivalent()) {
2298     // If we are self-suspending as a result of the lifting of a
2299     // suspend equivalent condition, then the suspend_equivalent
2300     // flag is not cleared until we set the ext_suspended flag so
2301     // that wait_for_ext_suspend_completion() returns consistent
2302     // results.
2303     this->clear_suspend_equivalent();
2304   }
2305 
2306   // A racing resume may have cancelled us before we grabbed SR_lock
2307   // above. Or another external suspend request could be waiting for us
2308   // by the time we return from SR_lock()->wait(). The thread
2309   // that requested the suspension may already be trying to walk our
2310   // stack and if we return now, we can change the stack out from under
2311   // it. This would be a "bad thing (TM)" and cause the stack walker
2312   // to crash. We stay self-suspended until there are no more pending
2313   // external suspend requests.
2314   while (is_external_suspend()) {
2315     ret++;
2316     this->set_ext_suspended();
2317 
2318     // _ext_suspended flag is cleared by java_resume()
2319     while (is_ext_suspended()) {
2320       this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2321     }
2322   }
2323 
2324   return ret;
2325 }
2326 
2327 #ifdef ASSERT
2328 // verify the JavaThread has not yet been published in the Threads::list, and
2329 // hence doesn't need protection from concurrent access at this stage
2330 void JavaThread::verify_not_published() {
2331   if (!Threads_lock->owned_by_self()) {
2332    MutexLockerEx ml(Threads_lock,  Mutex::_no_safepoint_check_flag);
2333    assert( !Threads::includes(this),
2334            "java thread shouldn't have been published yet!");
2335   }
2336   else {
2337    assert( !Threads::includes(this),
2338            "java thread shouldn't have been published yet!");
2339   }
2340 }
2341 #endif
2342 
2343 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2344 // progress or when _suspend_flags is non-zero.
2345 // Current thread needs to self-suspend if there is a suspend request and/or
2346 // block if a safepoint is in progress.
2347 // Async exception ISN'T checked.
2348 // Note only the ThreadInVMfromNative transition can call this function
2349 // directly and when thread state is _thread_in_native_trans
2350 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2351   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2352 
2353   JavaThread *curJT = JavaThread::current();
2354   bool do_self_suspend = thread->is_external_suspend();
2355 
2356   assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2357 
2358   // If JNIEnv proxies are allowed, don't self-suspend if the target
2359   // thread is not the current thread. In older versions of jdbx, jdbx
2360   // threads could call into the VM with another thread's JNIEnv so we
2361   // can be here operating on behalf of a suspended thread (4432884).
2362   if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2363     JavaThreadState state = thread->thread_state();
2364 
2365     // We mark this thread_blocked state as a suspend-equivalent so
2366     // that a caller to is_ext_suspend_completed() won't be confused.
2367     // The suspend-equivalent state is cleared by java_suspend_self().
2368     thread->set_suspend_equivalent();
2369 
2370     // If the safepoint code sees the _thread_in_native_trans state, it will
2371     // wait until the thread changes to other thread state. There is no
2372     // guarantee on how soon we can obtain the SR_lock and complete the
2373     // self-suspend request. It would be a bad idea to let safepoint wait for
2374     // too long. Temporarily change the state to _thread_blocked to
2375     // let the VM thread know that this thread is ready for GC. The problem
2376     // of changing thread state is that safepoint could happen just after
2377     // java_suspend_self() returns after being resumed, and VM thread will
2378     // see the _thread_blocked state. We must check for safepoint
2379     // after restoring the state and make sure we won't leave while a safepoint
2380     // is in progress.
2381     thread->set_thread_state(_thread_blocked);
2382     thread->java_suspend_self();
2383     thread->set_thread_state(state);
2384     // Make sure new state is seen by VM thread
2385     if (os::is_MP()) {
2386       if (UseMembar) {
2387         // Force a fence between the write above and read below
2388         OrderAccess::fence();
2389       } else {
2390         // Must use this rather than serialization page in particular on Windows
2391         InterfaceSupport::serialize_memory(thread);
2392       }
2393     }
2394   }
2395 
2396   if (SafepointSynchronize::do_call_back()) {
2397     // If we are safepointing, then block the caller which may not be
2398     // the same as the target thread (see above).
2399     SafepointSynchronize::block(curJT);
2400   }
2401 
2402   if (thread->is_deopt_suspend()) {
2403     thread->clear_deopt_suspend();
2404     RegisterMap map(thread, false);
2405     frame f = thread->last_frame();
2406     while ( f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2407       f = f.sender(&map);
2408     }
2409     if (f.id() == thread->must_deopt_id()) {
2410       thread->clear_must_deopt_id();
2411       f.deoptimize(thread);
2412     } else {
2413       fatal("missed deoptimization!");
2414     }
2415   }
2416 }
2417 
2418 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2419 // progress or when _suspend_flags is non-zero.
2420 // Current thread needs to self-suspend if there is a suspend request and/or
2421 // block if a safepoint is in progress.
2422 // Also check for pending async exception (not including unsafe access error).
2423 // Note only the native==>VM/Java barriers can call this function and when
2424 // thread state is _thread_in_native_trans.
2425 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2426   check_safepoint_and_suspend_for_native_trans(thread);
2427 
2428   if (thread->has_async_exception()) {
2429     // We are in _thread_in_native_trans state, don't handle unsafe
2430     // access error since that may block.
2431     thread->check_and_handle_async_exceptions(false);
2432   }
2433 }
2434 
2435 // This is a variant of the normal
2436 // check_special_condition_for_native_trans with slightly different
2437 // semantics for use by critical native wrappers.  It does all the
2438 // normal checks but also performs the transition back into
2439 // thread_in_Java state.  This is required so that critical natives
2440 // can potentially block and perform a GC if they are the last thread
2441 // exiting the GC_locker.
2442 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2443   check_special_condition_for_native_trans(thread);
2444 
2445   // Finish the transition
2446   thread->set_thread_state(_thread_in_Java);
2447 
2448   if (thread->do_critical_native_unlock()) {
2449     ThreadInVMfromJavaNoAsyncException tiv(thread);
2450     GC_locker::unlock_critical(thread);
2451     thread->clear_critical_native_unlock();
2452   }
2453 }
2454 
2455 // We need to guarantee the Threads_lock here, since resumes are not
2456 // allowed during safepoint synchronization
2457 // Can only resume from an external suspension
2458 void JavaThread::java_resume() {
2459   assert_locked_or_safepoint(Threads_lock);
2460 
2461   // Sanity check: thread is gone, has started exiting or the thread
2462   // was not externally suspended.
2463   if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2464     return;
2465   }
2466 
2467   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2468 
2469   clear_external_suspend();
2470 
2471   if (is_ext_suspended()) {
2472     clear_ext_suspended();
2473     SR_lock()->notify_all();
2474   }
2475 }
2476 
2477 void JavaThread::create_stack_guard_pages() {
2478   if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return;
2479   address low_addr = stack_base() - stack_size();
2480   size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2481 
2482   int allocate = os::allocate_stack_guard_pages();
2483   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2484 
2485   if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) {
2486     warning("Attempt to allocate stack guard pages failed.");
2487     return;
2488   }
2489 
2490   if (os::guard_memory((char *) low_addr, len)) {
2491     _stack_guard_state = stack_guard_enabled;
2492   } else {
2493     warning("Attempt to protect stack guard pages failed.");
2494     if (os::uncommit_memory((char *) low_addr, len)) {
2495       warning("Attempt to deallocate stack guard pages failed.");
2496     }
2497   }
2498 }
2499 
2500 void JavaThread::remove_stack_guard_pages() {
2501   assert(Thread::current() == this, "from different thread");
2502   if (_stack_guard_state == stack_guard_unused) return;
2503   address low_addr = stack_base() - stack_size();
2504   size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2505 
2506   if (os::allocate_stack_guard_pages()) {
2507     if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2508       _stack_guard_state = stack_guard_unused;
2509     } else {
2510       warning("Attempt to deallocate stack guard pages failed.");
2511     }
2512   } else {
2513     if (_stack_guard_state == stack_guard_unused) return;
2514     if (os::unguard_memory((char *) low_addr, len)) {
2515       _stack_guard_state = stack_guard_unused;
2516     } else {
2517         warning("Attempt to unprotect stack guard pages failed.");
2518     }
2519   }
2520 }
2521 
2522 void JavaThread::enable_stack_yellow_zone() {
2523   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2524   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2525 
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   address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2529 
2530   guarantee(base < stack_base(),"Error calculating stack yellow zone");
2531   guarantee(base < os::current_stack_pointer(),"Error calculating stack yellow zone");
2532 
2533   if (os::guard_memory((char *) base, stack_yellow_zone_size())) {
2534     _stack_guard_state = stack_guard_enabled;
2535   } else {
2536     warning("Attempt to guard stack yellow zone failed.");
2537   }
2538   enable_register_stack_guard();
2539 }
2540 
2541 void JavaThread::disable_stack_yellow_zone() {
2542   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2543   assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled");
2544 
2545   // Simply return if called for a thread that does not use guard pages.
2546   if (_stack_guard_state == stack_guard_unused) return;
2547 
2548   // The base notation is from the stacks point of view, growing downward.
2549   // We need to adjust it to work correctly with guard_memory()
2550   address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2551 
2552   if (os::unguard_memory((char *)base, stack_yellow_zone_size())) {
2553     _stack_guard_state = stack_guard_yellow_disabled;
2554   } else {
2555     warning("Attempt to unguard stack yellow zone failed.");
2556   }
2557   disable_register_stack_guard();
2558 }
2559 
2560 void JavaThread::enable_stack_red_zone() {
2561   // The base notation is from the stacks point of view, growing downward.
2562   // We need to adjust it to work correctly with guard_memory()
2563   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2564   address base = stack_red_zone_base() - stack_red_zone_size();
2565 
2566   guarantee(base < stack_base(),"Error calculating stack red zone");
2567   guarantee(base < os::current_stack_pointer(),"Error calculating stack red zone");
2568 
2569   if(!os::guard_memory((char *) base, stack_red_zone_size())) {
2570     warning("Attempt to guard stack red zone failed.");
2571   }
2572 }
2573 
2574 void JavaThread::disable_stack_red_zone() {
2575   // The base notation is from the stacks point of view, growing downward.
2576   // We need to adjust it to work correctly with guard_memory()
2577   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2578   address base = stack_red_zone_base() - stack_red_zone_size();
2579   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2580     warning("Attempt to unguard stack red zone failed.");
2581   }
2582 }
2583 
2584 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2585   // ignore is there is no stack
2586   if (!has_last_Java_frame()) return;
2587   // traverse the stack frames. Starts from top frame.
2588   for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2589     frame* fr = fst.current();
2590     f(fr, fst.register_map());
2591   }
2592 }
2593 
2594 
2595 #ifndef PRODUCT
2596 // Deoptimization
2597 // Function for testing deoptimization
2598 void JavaThread::deoptimize() {
2599   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2600   StackFrameStream fst(this, UseBiasedLocking);
2601   bool deopt = false;           // Dump stack only if a deopt actually happens.
2602   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2603   // Iterate over all frames in the thread and deoptimize
2604   for(; !fst.is_done(); fst.next()) {
2605     if(fst.current()->can_be_deoptimized()) {
2606 
2607       if (only_at) {
2608         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
2609         // consists of comma or carriage return separated numbers so
2610         // search for the current bci in that string.
2611         address pc = fst.current()->pc();
2612         nmethod* nm =  (nmethod*) fst.current()->cb();
2613         ScopeDesc* sd = nm->scope_desc_at( pc);
2614         char buffer[8];
2615         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2616         size_t len = strlen(buffer);
2617         const char * found = strstr(DeoptimizeOnlyAt, buffer);
2618         while (found != NULL) {
2619           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2620               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2621             // Check that the bci found is bracketed by terminators.
2622             break;
2623           }
2624           found = strstr(found + 1, buffer);
2625         }
2626         if (!found) {
2627           continue;
2628         }
2629       }
2630 
2631       if (DebugDeoptimization && !deopt) {
2632         deopt = true; // One-time only print before deopt
2633         tty->print_cr("[BEFORE Deoptimization]");
2634         trace_frames();
2635         trace_stack();
2636       }
2637       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2638     }
2639   }
2640 
2641   if (DebugDeoptimization && deopt) {
2642     tty->print_cr("[AFTER Deoptimization]");
2643     trace_frames();
2644   }
2645 }
2646 
2647 
2648 // Make zombies
2649 void JavaThread::make_zombies() {
2650   for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2651     if (fst.current()->can_be_deoptimized()) {
2652       // it is a Java nmethod
2653       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2654       nm->make_not_entrant();
2655     }
2656   }
2657 }
2658 #endif // PRODUCT
2659 
2660 
2661 void JavaThread::deoptimized_wrt_marked_nmethods() {
2662   if (!has_last_Java_frame()) return;
2663   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2664   StackFrameStream fst(this, UseBiasedLocking);
2665   for(; !fst.is_done(); fst.next()) {
2666     if (fst.current()->should_be_deoptimized()) {
2667       if (LogCompilation && xtty != NULL) {
2668         nmethod* nm = fst.current()->cb()->as_nmethod_or_null();
2669         xtty->elem("deoptimized thread='" UINTX_FORMAT "' compile_id='%d'",
2670                    this->name(), nm != NULL ? nm->compile_id() : -1);
2671       }
2672 
2673       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2674     }
2675   }
2676 }
2677 
2678 
2679 // GC support
2680 static void frame_gc_epilogue(frame* f, const RegisterMap* map) { f->gc_epilogue(); }
2681 
2682 void JavaThread::gc_epilogue() {
2683   frames_do(frame_gc_epilogue);
2684 }
2685 
2686 
2687 static void frame_gc_prologue(frame* f, const RegisterMap* map) { f->gc_prologue(); }
2688 
2689 void JavaThread::gc_prologue() {
2690   frames_do(frame_gc_prologue);
2691 }
2692 
2693 // If the caller is a NamedThread, then remember, in the current scope,
2694 // the given JavaThread in its _processed_thread field.
2695 class RememberProcessedThread: public StackObj {
2696   NamedThread* _cur_thr;
2697 public:
2698   RememberProcessedThread(JavaThread* jthr) {
2699     Thread* thread = Thread::current();
2700     if (thread->is_Named_thread()) {
2701       _cur_thr = (NamedThread *)thread;
2702       _cur_thr->set_processed_thread(jthr);
2703     } else {
2704       _cur_thr = NULL;
2705     }
2706   }
2707 
2708   ~RememberProcessedThread() {
2709     if (_cur_thr) {
2710       _cur_thr->set_processed_thread(NULL);
2711     }
2712   }
2713 };
2714 
2715 void JavaThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
2716   // Verify that the deferred card marks have been flushed.
2717   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2718 
2719   // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2720   // since there may be more than one thread using each ThreadProfiler.
2721 
2722   // Traverse the GCHandles
2723   Thread::oops_do(f, cld_f, cf);
2724 
2725   assert( (!has_last_Java_frame() && java_call_counter() == 0) ||
2726           (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2727 
2728   if (has_last_Java_frame()) {
2729     // Record JavaThread to GC thread
2730     RememberProcessedThread rpt(this);
2731 
2732     // Traverse the privileged stack
2733     if (_privileged_stack_top != NULL) {
2734       _privileged_stack_top->oops_do(f);
2735     }
2736 
2737     // traverse the registered growable array
2738     if (_array_for_gc != NULL) {
2739       for (int index = 0; index < _array_for_gc->length(); index++) {
2740         f->do_oop(_array_for_gc->adr_at(index));
2741       }
2742     }
2743 
2744     // Traverse the monitor chunks
2745     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2746       chunk->oops_do(f);
2747     }
2748 
2749     // Traverse the execution stack
2750     for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2751       fst.current()->oops_do(f, cld_f, cf, fst.register_map());
2752     }
2753   }
2754 
2755   // callee_target is never live across a gc point so NULL it here should
2756   // it still contain a methdOop.
2757 
2758   set_callee_target(NULL);
2759 
2760   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2761   // If we have deferred set_locals there might be oops waiting to be
2762   // written
2763   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2764   if (list != NULL) {
2765     for (int i = 0; i < list->length(); i++) {
2766       list->at(i)->oops_do(f);
2767     }
2768   }
2769 
2770   // Traverse instance variables at the end since the GC may be moving things
2771   // around using this function
2772   f->do_oop((oop*) &_threadObj);
2773   f->do_oop((oop*) &_vm_result);
2774   f->do_oop((oop*) &_exception_oop);
2775   f->do_oop((oop*) &_pending_async_exception);
2776 
2777   if (jvmti_thread_state() != NULL) {
2778     jvmti_thread_state()->oops_do(f);
2779   }
2780 }
2781 
2782 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2783   Thread::nmethods_do(cf);  // (super method is a no-op)
2784 
2785   assert( (!has_last_Java_frame() && java_call_counter() == 0) ||
2786           (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2787 
2788   if (has_last_Java_frame()) {
2789     // Traverse the execution stack
2790     for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2791       fst.current()->nmethods_do(cf);
2792     }
2793   }
2794 }
2795 
2796 void JavaThread::metadata_do(void f(Metadata*)) {
2797   Thread::metadata_do(f);
2798   if (has_last_Java_frame()) {
2799     // Traverse the execution stack to call f() on the methods in the stack
2800     for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2801       fst.current()->metadata_do(f);
2802     }
2803   } else if (is_Compiler_thread()) {
2804     // need to walk ciMetadata in current compile tasks to keep alive.
2805     CompilerThread* ct = (CompilerThread*)this;
2806     if (ct->env() != NULL) {
2807       ct->env()->metadata_do(f);
2808     }
2809   }
2810 }
2811 
2812 // Printing
2813 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2814   switch (_thread_state) {
2815   case _thread_uninitialized:     return "_thread_uninitialized";
2816   case _thread_new:               return "_thread_new";
2817   case _thread_new_trans:         return "_thread_new_trans";
2818   case _thread_in_native:         return "_thread_in_native";
2819   case _thread_in_native_trans:   return "_thread_in_native_trans";
2820   case _thread_in_vm:             return "_thread_in_vm";
2821   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
2822   case _thread_in_Java:           return "_thread_in_Java";
2823   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
2824   case _thread_blocked:           return "_thread_blocked";
2825   case _thread_blocked_trans:     return "_thread_blocked_trans";
2826   default:                        return "unknown thread state";
2827   }
2828 }
2829 
2830 #ifndef PRODUCT
2831 void JavaThread::print_thread_state_on(outputStream *st) const {
2832   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
2833 };
2834 void JavaThread::print_thread_state() const {
2835   print_thread_state_on(tty);
2836 };
2837 #endif // PRODUCT
2838 
2839 // Called by Threads::print() for VM_PrintThreads operation
2840 void JavaThread::print_on(outputStream *st) const {
2841   st->print("\"%s\" ", get_thread_name());
2842   oop thread_oop = threadObj();
2843   if (thread_oop != NULL) {
2844     st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop));
2845     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
2846     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2847   }
2848   Thread::print_on(st);
2849   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2850   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2851   if (thread_oop != NULL && JDK_Version::is_gte_jdk15x_version()) {
2852     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2853   }
2854 #ifndef PRODUCT
2855   print_thread_state_on(st);
2856   _safepoint_state->print_on(st);
2857 #endif // PRODUCT
2858 }
2859 
2860 // Called by fatal error handler. The difference between this and
2861 // JavaThread::print() is that we can't grab lock or allocate memory.
2862 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2863   st->print("JavaThread \"%s\"",  get_thread_name_string(buf, buflen));
2864   oop thread_obj = threadObj();
2865   if (thread_obj != NULL) {
2866      if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2867   }
2868   st->print(" [");
2869   st->print("%s", _get_thread_state_name(_thread_state));
2870   if (osthread()) {
2871     st->print(", id=%d", osthread()->thread_id());
2872   }
2873   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2874             _stack_base - _stack_size, _stack_base);
2875   st->print("]");
2876   return;
2877 }
2878 
2879 // Verification
2880 
2881 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2882 
2883 void JavaThread::verify() {
2884   // Verify oops in the thread.
2885   oops_do(&VerifyOopClosure::verify_oop, NULL, NULL);
2886 
2887   // Verify the stack frames.
2888   frames_do(frame_verify);
2889 }
2890 
2891 // CR 6300358 (sub-CR 2137150)
2892 // Most callers of this method assume that it can't return NULL but a
2893 // thread may not have a name whilst it is in the process of attaching to
2894 // the VM - see CR 6412693, and there are places where a JavaThread can be
2895 // seen prior to having it's threadObj set (eg JNI attaching threads and
2896 // if vm exit occurs during initialization). These cases can all be accounted
2897 // for such that this method never returns NULL.
2898 const char* JavaThread::get_thread_name() const {
2899 #ifdef ASSERT
2900   // early safepoints can hit while current thread does not yet have TLS
2901   if (!SafepointSynchronize::is_at_safepoint()) {
2902     Thread *cur = Thread::current();
2903     if (!(cur->is_Java_thread() && cur == this)) {
2904       // Current JavaThreads are allowed to get their own name without
2905       // the Threads_lock.
2906       assert_locked_or_safepoint(Threads_lock);
2907     }
2908   }
2909 #endif // ASSERT
2910     return get_thread_name_string();
2911 }
2912 
2913 // Returns a non-NULL representation of this thread's name, or a suitable
2914 // descriptive string if there is no set name
2915 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2916   const char* name_str;
2917   oop thread_obj = threadObj();
2918   if (thread_obj != NULL) {
2919     typeArrayOop name = java_lang_Thread::name(thread_obj);
2920     if (name != NULL) {
2921       if (buf == NULL) {
2922         name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2923       }
2924       else {
2925         name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length(), buf, buflen);
2926       }
2927     }
2928     else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
2929       name_str = "<no-name - thread is attaching>";
2930     }
2931     else {
2932       name_str = Thread::name();
2933     }
2934   }
2935   else {
2936     name_str = Thread::name();
2937   }
2938   assert(name_str != NULL, "unexpected NULL thread name");
2939   return name_str;
2940 }
2941 
2942 
2943 const char* JavaThread::get_threadgroup_name() const {
2944   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2945   oop thread_obj = threadObj();
2946   if (thread_obj != NULL) {
2947     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2948     if (thread_group != NULL) {
2949       typeArrayOop name = java_lang_ThreadGroup::name(thread_group);
2950       // ThreadGroup.name can be null
2951       if (name != NULL) {
2952         const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2953         return str;
2954       }
2955     }
2956   }
2957   return NULL;
2958 }
2959 
2960 const char* JavaThread::get_parent_name() const {
2961   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2962   oop thread_obj = threadObj();
2963   if (thread_obj != NULL) {
2964     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2965     if (thread_group != NULL) {
2966       oop parent = java_lang_ThreadGroup::parent(thread_group);
2967       if (parent != NULL) {
2968         typeArrayOop name = java_lang_ThreadGroup::name(parent);
2969         // ThreadGroup.name can be null
2970         if (name != NULL) {
2971           const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2972           return str;
2973         }
2974       }
2975     }
2976   }
2977   return NULL;
2978 }
2979 
2980 ThreadPriority JavaThread::java_priority() const {
2981   oop thr_oop = threadObj();
2982   if (thr_oop == NULL) return NormPriority; // Bootstrapping
2983   ThreadPriority priority = java_lang_Thread::priority(thr_oop);
2984   assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
2985   return priority;
2986 }
2987 
2988 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
2989 
2990   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
2991   // Link Java Thread object <-> C++ Thread
2992 
2993   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
2994   // and put it into a new Handle.  The Handle "thread_oop" can then
2995   // be used to pass the C++ thread object to other methods.
2996 
2997   // Set the Java level thread object (jthread) field of the
2998   // new thread (a JavaThread *) to C++ thread object using the
2999   // "thread_oop" handle.
3000 
3001   // Set the thread field (a JavaThread *) of the
3002   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3003 
3004   Handle thread_oop(Thread::current(),
3005                     JNIHandles::resolve_non_null(jni_thread));
3006   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3007     "must be initialized");
3008   set_threadObj(thread_oop());
3009   java_lang_Thread::set_thread(thread_oop(), this);
3010 
3011   if (prio == NoPriority) {
3012     prio = java_lang_Thread::priority(thread_oop());
3013     assert(prio != NoPriority, "A valid priority should be present");
3014   }
3015 
3016   // Push the Java priority down to the native thread; needs Threads_lock
3017   Thread::set_priority(this, prio);
3018 
3019   // Add the new thread to the Threads list and set it in motion.
3020   // We must have threads lock in order to call Threads::add.
3021   // It is crucial that we do not block before the thread is
3022   // added to the Threads list for if a GC happens, then the java_thread oop
3023   // will not be visited by GC.
3024   Threads::add(this);
3025 }
3026 
3027 oop JavaThread::current_park_blocker() {
3028   // Support for JSR-166 locks
3029   oop thread_oop = threadObj();
3030   if (thread_oop != NULL &&
3031       JDK_Version::current().supports_thread_park_blocker()) {
3032     return java_lang_Thread::park_blocker(thread_oop);
3033   }
3034   return NULL;
3035 }
3036 
3037 
3038 void JavaThread::print_stack_on(outputStream* st) {
3039   if (!has_last_Java_frame()) return;
3040   ResourceMark rm;
3041   HandleMark   hm;
3042 
3043   RegisterMap reg_map(this);
3044   vframe* start_vf = last_java_vframe(&reg_map);
3045   int count = 0;
3046   for (vframe* f = start_vf; f; f = f->sender() ) {
3047     if (f->is_java_frame()) {
3048       javaVFrame* jvf = javaVFrame::cast(f);
3049       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3050 
3051       // Print out lock information
3052       if (JavaMonitorsInStackTrace) {
3053         jvf->print_lock_info_on(st, count);
3054       }
3055     } else {
3056       // Ignore non-Java frames
3057     }
3058 
3059     // Bail-out case for too deep stacks
3060     count++;
3061     if (MaxJavaStackTraceDepth == count) return;
3062   }
3063 }
3064 
3065 
3066 // JVMTI PopFrame support
3067 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3068   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3069   if (in_bytes(size_in_bytes) != 0) {
3070     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3071     _popframe_preserved_args_size = in_bytes(size_in_bytes);
3072     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3073   }
3074 }
3075 
3076 void* JavaThread::popframe_preserved_args() {
3077   return _popframe_preserved_args;
3078 }
3079 
3080 ByteSize JavaThread::popframe_preserved_args_size() {
3081   return in_ByteSize(_popframe_preserved_args_size);
3082 }
3083 
3084 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3085   int sz = in_bytes(popframe_preserved_args_size());
3086   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3087   return in_WordSize(sz / wordSize);
3088 }
3089 
3090 void JavaThread::popframe_free_preserved_args() {
3091   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3092   FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args, mtThread);
3093   _popframe_preserved_args = NULL;
3094   _popframe_preserved_args_size = 0;
3095 }
3096 
3097 #ifndef PRODUCT
3098 
3099 void JavaThread::trace_frames() {
3100   tty->print_cr("[Describe stack]");
3101   int frame_no = 1;
3102   for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3103     tty->print("  %d. ", frame_no++);
3104     fst.current()->print_value_on(tty,this);
3105     tty->cr();
3106   }
3107 }
3108 
3109 class PrintAndVerifyOopClosure: public OopClosure {
3110  protected:
3111   template <class T> inline void do_oop_work(T* p) {
3112     oop obj = oopDesc::load_decode_heap_oop(p);
3113     if (obj == NULL) return;
3114     tty->print(INTPTR_FORMAT ": ", p);
3115     if (obj->is_oop_or_null()) {
3116       if (obj->is_objArray()) {
3117         tty->print_cr("valid objArray: " INTPTR_FORMAT, (oopDesc*) obj);
3118       } else {
3119         obj->print();
3120       }
3121     } else {
3122       tty->print_cr("invalid oop: " INTPTR_FORMAT, (oopDesc*) obj);
3123     }
3124     tty->cr();
3125   }
3126  public:
3127   virtual void do_oop(oop* p) { do_oop_work(p); }
3128   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
3129 };
3130 
3131 
3132 static void oops_print(frame* f, const RegisterMap *map) {
3133   PrintAndVerifyOopClosure print;
3134   f->print_value();
3135   f->oops_do(&print, NULL, NULL, (RegisterMap*)map);
3136 }
3137 
3138 // Print our all the locations that contain oops and whether they are
3139 // valid or not.  This useful when trying to find the oldest frame
3140 // where an oop has gone bad since the frame walk is from youngest to
3141 // oldest.
3142 void JavaThread::trace_oops() {
3143   tty->print_cr("[Trace oops]");
3144   frames_do(oops_print);
3145 }
3146 
3147 
3148 #ifdef ASSERT
3149 // Print or validate the layout of stack frames
3150 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3151   ResourceMark rm;
3152   PRESERVE_EXCEPTION_MARK;
3153   FrameValues values;
3154   int frame_no = 0;
3155   for(StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3156     fst.current()->describe(values, ++frame_no);
3157     if (depth == frame_no) break;
3158   }
3159   if (validate_only) {
3160     values.validate();
3161   } else {
3162     tty->print_cr("[Describe stack layout]");
3163     values.print(this);
3164   }
3165 }
3166 #endif
3167 
3168 void JavaThread::trace_stack_from(vframe* start_vf) {
3169   ResourceMark rm;
3170   int vframe_no = 1;
3171   for (vframe* f = start_vf; f; f = f->sender() ) {
3172     if (f->is_java_frame()) {
3173       javaVFrame::cast(f)->print_activation(vframe_no++);
3174     } else {
3175       f->print();
3176     }
3177     if (vframe_no > StackPrintLimit) {
3178       tty->print_cr("...<more frames>...");
3179       return;
3180     }
3181   }
3182 }
3183 
3184 
3185 void JavaThread::trace_stack() {
3186   if (!has_last_Java_frame()) return;
3187   ResourceMark rm;
3188   HandleMark   hm;
3189   RegisterMap reg_map(this);
3190   trace_stack_from(last_java_vframe(&reg_map));
3191 }
3192 
3193 
3194 #endif // PRODUCT
3195 
3196 
3197 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3198   assert(reg_map != NULL, "a map must be given");
3199   frame f = last_frame();
3200   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender() ) {
3201     if (vf->is_java_frame()) return javaVFrame::cast(vf);
3202   }
3203   return NULL;
3204 }
3205 
3206 
3207 Klass* JavaThread::security_get_caller_class(int depth) {
3208   vframeStream vfst(this);
3209   vfst.security_get_caller_frame(depth);
3210   if (!vfst.at_end()) {
3211     return vfst.method()->method_holder();
3212   }
3213   return NULL;
3214 }
3215 
3216 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3217   assert(thread->is_Compiler_thread(), "must be compiler thread");
3218   CompileBroker::compiler_thread_loop();
3219 }
3220 
3221 // Create a CompilerThread
3222 CompilerThread::CompilerThread(CompileQueue* queue, CompilerCounters* counters)
3223 : JavaThread(&compiler_thread_entry) {
3224   _env   = NULL;
3225   _log   = NULL;
3226   _task  = NULL;
3227   _queue = queue;
3228   _counters = counters;
3229   _buffer_blob = NULL;
3230   _scanned_nmethod = NULL;
3231   _compiler = NULL;
3232 
3233 #ifndef PRODUCT
3234   _ideal_graph_printer = NULL;
3235 #endif
3236 }
3237 
3238 void CompilerThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
3239   JavaThread::oops_do(f, cld_f, cf);
3240   if (_scanned_nmethod != NULL && cf != NULL) {
3241     // Safepoints can occur when the sweeper is scanning an nmethod so
3242     // process it here to make sure it isn't unloaded in the middle of
3243     // a scan.
3244     cf->do_code_blob(_scanned_nmethod);
3245   }
3246 }
3247 
3248 
3249 // ======= Threads ========
3250 
3251 // The Threads class links together all active threads, and provides
3252 // operations over all threads.  It is protected by its own Mutex
3253 // lock, which is also used in other contexts to protect thread
3254 // operations from having the thread being operated on from exiting
3255 // and going away unexpectedly (e.g., safepoint synchronization)
3256 
3257 JavaThread* Threads::_thread_list = NULL;
3258 int         Threads::_number_of_threads = 0;
3259 int         Threads::_number_of_non_daemon_threads = 0;
3260 int         Threads::_return_code = 0;
3261 size_t      JavaThread::_stack_size_at_create = 0;
3262 #ifdef ASSERT
3263 bool        Threads::_vm_complete = false;
3264 #endif
3265 
3266 // All JavaThreads
3267 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3268 
3269 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3270 void Threads::threads_do(ThreadClosure* tc) {
3271   assert_locked_or_safepoint(Threads_lock);
3272   // ALL_JAVA_THREADS iterates through all JavaThreads
3273   ALL_JAVA_THREADS(p) {
3274     tc->do_thread(p);
3275   }
3276   // Someday we could have a table or list of all non-JavaThreads.
3277   // For now, just manually iterate through them.
3278   tc->do_thread(VMThread::vm_thread());
3279   Universe::heap()->gc_threads_do(tc);
3280   WatcherThread *wt = WatcherThread::watcher_thread();
3281   // Strictly speaking, the following NULL check isn't sufficient to make sure
3282   // the data for WatcherThread is still valid upon being examined. However,
3283   // considering that WatchThread terminates when the VM is on the way to
3284   // exit at safepoint, the chance of the above is extremely small. The right
3285   // way to prevent termination of WatcherThread would be to acquire
3286   // Terminator_lock, but we can't do that without violating the lock rank
3287   // checking in some cases.
3288   if (wt != NULL)
3289     tc->do_thread(wt);
3290 
3291   // If CompilerThreads ever become non-JavaThreads, add them here
3292 }
3293 
3294 
3295 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3296   TraceTime timer("Initialize java.lang classes", TraceStartupTime);
3297 
3298   if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3299     create_vm_init_libraries();
3300   }
3301 
3302   initialize_class(vmSymbols::java_lang_String(), CHECK);
3303 
3304   // Initialize java_lang.System (needed before creating the thread)
3305   initialize_class(vmSymbols::java_lang_System(), CHECK);
3306   initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3307   Handle thread_group = create_initial_thread_group(CHECK);
3308   Universe::set_main_thread_group(thread_group());
3309   initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3310   oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3311   main_thread->set_threadObj(thread_object);
3312   // Set thread status to running since main thread has
3313   // been started and running.
3314   java_lang_Thread::set_thread_status(thread_object,
3315                                       java_lang_Thread::RUNNABLE);
3316 
3317   // The VM creates & returns objects of this class. Make sure it's initialized.
3318   initialize_class(vmSymbols::java_lang_Class(), CHECK);
3319 
3320   // The VM preresolves methods to these classes. Make sure that they get initialized
3321   initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3322   initialize_class(vmSymbols::java_lang_ref_Finalizer(),  CHECK);
3323   call_initializeSystemClass(CHECK);
3324 
3325   // get the Java runtime name after java.lang.System is initialized
3326   JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3327   JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3328 
3329   // an instance of OutOfMemory exception has been allocated earlier
3330   initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3331   initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3332   initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3333   initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3334   initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3335   initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3336   initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3337   initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3338 }
3339 
3340 void Threads::initialize_jsr292_core_classes(TRAPS) {
3341   initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3342   initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3343   initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3344 }
3345 
3346 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3347 
3348   extern void JDK_Version_init();
3349 
3350   // Check version
3351   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3352 
3353   // Initialize the output stream module
3354   ostream_init();
3355 
3356   // Process java launcher properties.
3357   Arguments::process_sun_java_launcher_properties(args);
3358 
3359   // Initialize the os module before using TLS
3360   os::init();
3361 
3362   // Initialize system properties.
3363   Arguments::init_system_properties();
3364 
3365   // So that JDK version can be used as a discriminator when parsing arguments
3366   JDK_Version_init();
3367 
3368   // Update/Initialize System properties after JDK version number is known
3369   Arguments::init_version_specific_system_properties();
3370 
3371   // Parse arguments
3372   jint parse_result = Arguments::parse(args);
3373   if (parse_result != JNI_OK) return parse_result;
3374 
3375   os::init_before_ergo();
3376 
3377   jint ergo_result = Arguments::apply_ergo();
3378   if (ergo_result != JNI_OK) return ergo_result;
3379 
3380   if (PauseAtStartup) {
3381     os::pause();
3382   }
3383 
3384   HOTSPOT_VM_INIT_BEGIN();
3385 
3386   // Record VM creation timing statistics
3387   TraceVmCreationTime create_vm_timer;
3388   create_vm_timer.start();
3389 
3390   // Timing (must come after argument parsing)
3391   TraceTime timer("Create VM", TraceStartupTime);
3392 
3393   // Initialize the os module after parsing the args
3394   jint os_init_2_result = os::init_2();
3395   if (os_init_2_result != JNI_OK) return os_init_2_result;
3396 
3397   jint adjust_after_os_result = Arguments::adjust_after_os();
3398   if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3399 
3400   // initialize TLS
3401   ThreadLocalStorage::init();
3402 
3403   // Bootstrap native memory tracking, so it can start recording memory
3404   // activities before worker thread is started. This is the first phase
3405   // of bootstrapping, VM is currently running in single-thread mode.
3406   MemTracker::bootstrap_single_thread();
3407 
3408   // Initialize output stream logging
3409   ostream_init_log();
3410 
3411   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3412   // Must be before create_vm_init_agents()
3413   if (Arguments::init_libraries_at_startup()) {
3414     convert_vm_init_libraries_to_agents();
3415   }
3416 
3417   // Launch -agentlib/-agentpath and converted -Xrun agents
3418   if (Arguments::init_agents_at_startup()) {
3419     create_vm_init_agents();
3420   }
3421 
3422   // Initialize Threads state
3423   _thread_list = NULL;
3424   _number_of_threads = 0;
3425   _number_of_non_daemon_threads = 0;
3426 
3427   // Initialize global data structures and create system classes in heap
3428   vm_init_globals();
3429 
3430   // Attach the main thread to this os thread
3431   JavaThread* main_thread = new JavaThread();
3432   main_thread->set_thread_state(_thread_in_vm);
3433   // must do this before set_active_handles and initialize_thread_local_storage
3434   // Note: on solaris initialize_thread_local_storage() will (indirectly)
3435   // change the stack size recorded here to one based on the java thread
3436   // stacksize. This adjusted size is what is used to figure the placement
3437   // of the guard pages.
3438   main_thread->record_stack_base_and_size();
3439   main_thread->initialize_thread_local_storage();
3440 
3441   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3442 
3443   if (!main_thread->set_as_starting_thread()) {
3444     vm_shutdown_during_initialization(
3445       "Failed necessary internal allocation. Out of swap space");
3446     delete main_thread;
3447     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3448     return JNI_ENOMEM;
3449   }
3450 
3451   // Enable guard page *after* os::create_main_thread(), otherwise it would
3452   // crash Linux VM, see notes in os_linux.cpp.
3453   main_thread->create_stack_guard_pages();
3454 
3455   // Initialize Java-Level synchronization subsystem
3456   ObjectMonitor::Initialize() ;
3457 
3458   // Second phase of bootstrapping, VM is about entering multi-thread mode
3459   MemTracker::bootstrap_multi_thread();
3460 
3461   // Initialize global modules
3462   jint status = init_globals();
3463   if (status != JNI_OK) {
3464     delete main_thread;
3465     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3466     return status;
3467   }
3468 
3469   // Should be done after the heap is fully created
3470   main_thread->cache_global_variables();
3471 
3472   HandleMark hm;
3473 
3474   { MutexLocker mu(Threads_lock);
3475     Threads::add(main_thread);
3476   }
3477 
3478   // Any JVMTI raw monitors entered in onload will transition into
3479   // real raw monitor. VM is setup enough here for raw monitor enter.
3480   JvmtiExport::transition_pending_onload_raw_monitors();
3481 
3482   // Fully start NMT
3483   MemTracker::start();
3484 
3485   // Create the VMThread
3486   { TraceTime timer("Start VMThread", TraceStartupTime);
3487     VMThread::create();
3488     Thread* vmthread = VMThread::vm_thread();
3489 
3490     if (!os::create_thread(vmthread, os::vm_thread))
3491       vm_exit_during_initialization("Cannot create VM thread. Out of system resources.");
3492 
3493     // Wait for the VM thread to become ready, and VMThread::run to initialize
3494     // Monitors can have spurious returns, must always check another state flag
3495     {
3496       MutexLocker ml(Notify_lock);
3497       os::start_thread(vmthread);
3498       while (vmthread->active_handles() == NULL) {
3499         Notify_lock->wait();
3500       }
3501     }
3502   }
3503 
3504   assert (Universe::is_fully_initialized(), "not initialized");
3505   if (VerifyDuringStartup) {
3506     // Make sure we're starting with a clean slate.
3507     VM_Verify verify_op;
3508     VMThread::execute(&verify_op);
3509   }
3510 
3511   Thread* THREAD = Thread::current();
3512 
3513   // At this point, the Universe is initialized, but we have not executed
3514   // any byte code.  Now is a good time (the only time) to dump out the
3515   // internal state of the JVM for sharing.
3516   if (DumpSharedSpaces) {
3517     MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3518     ShouldNotReachHere();
3519   }
3520 
3521   // Always call even when there are not JVMTI environments yet, since environments
3522   // may be attached late and JVMTI must track phases of VM execution
3523   JvmtiExport::enter_start_phase();
3524 
3525   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3526   JvmtiExport::post_vm_start();
3527 
3528   initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3529 
3530   // We need this for ClassDataSharing - the initial vm.info property is set
3531   // with the default value of CDS "sharing" which may be reset through
3532   // command line options.
3533   reset_vm_info_property(CHECK_JNI_ERR);
3534 
3535   quicken_jni_functions();
3536 
3537   // Must be run after init_ft which initializes ft_enabled
3538   if (TRACE_INITIALIZE() != JNI_OK) {
3539     vm_exit_during_initialization("Failed to initialize tracing backend");
3540   }
3541 
3542   // Set flag that basic initialization has completed. Used by exceptions and various
3543   // debug stuff, that does not work until all basic classes have been initialized.
3544   set_init_completed();
3545 
3546   Metaspace::post_initialize();
3547 
3548   HOTSPOT_VM_INIT_END();
3549 
3550   // record VM initialization completion time
3551 #if INCLUDE_MANAGEMENT
3552   Management::record_vm_init_completed();
3553 #endif // INCLUDE_MANAGEMENT
3554 
3555   // Compute system loader. Note that this has to occur after set_init_completed, since
3556   // valid exceptions may be thrown in the process.
3557   // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
3558   // set_init_completed has just been called, causing exceptions not to be shortcut
3559   // anymore. We call vm_exit_during_initialization directly instead.
3560   SystemDictionary::compute_java_system_loader(CHECK_JNI_ERR);
3561 
3562 #if INCLUDE_ALL_GCS
3563   // Support for ConcurrentMarkSweep. This should be cleaned up
3564   // and better encapsulated. The ugly nested if test would go away
3565   // once things are properly refactored. XXX YSR
3566   if (UseConcMarkSweepGC || UseG1GC) {
3567     if (UseConcMarkSweepGC) {
3568       ConcurrentMarkSweepThread::makeSurrogateLockerThread(CHECK_JNI_ERR);
3569     } else {
3570       ConcurrentMarkThread::makeSurrogateLockerThread(CHECK_JNI_ERR);
3571     }
3572   }
3573 #endif // INCLUDE_ALL_GCS
3574 
3575   // Always call even when there are not JVMTI environments yet, since environments
3576   // may be attached late and JVMTI must track phases of VM execution
3577   JvmtiExport::enter_live_phase();
3578 
3579   // Signal Dispatcher needs to be started before VMInit event is posted
3580   os::signal_init();
3581 
3582   // Start Attach Listener if +StartAttachListener or it can't be started lazily
3583   if (!DisableAttachMechanism) {
3584     AttachListener::vm_start();
3585     if (StartAttachListener || AttachListener::init_at_startup()) {
3586       AttachListener::init();
3587     }
3588   }
3589 
3590   // Launch -Xrun agents
3591   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3592   // back-end can launch with -Xdebug -Xrunjdwp.
3593   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3594     create_vm_init_libraries();
3595   }
3596 
3597   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3598   JvmtiExport::post_vm_initialized();
3599 
3600   if (TRACE_START() != JNI_OK) {
3601     vm_exit_during_initialization("Failed to start tracing backend.");
3602   }
3603 
3604   if (CleanChunkPoolAsync) {
3605     Chunk::start_chunk_pool_cleaner_task();
3606   }
3607 
3608   // initialize compiler(s)
3609 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK)
3610   CompileBroker::compilation_init();
3611 #endif
3612 
3613   // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3614   // It is done after compilers are initialized, because otherwise compilations of
3615   // signature polymorphic MH intrinsics can be missed
3616   // (see SystemDictionary::find_method_handle_intrinsic).
3617   initialize_jsr292_core_classes(CHECK_JNI_ERR);
3618 
3619 #if INCLUDE_MANAGEMENT
3620   Management::initialize(THREAD);
3621 
3622   if (HAS_PENDING_EXCEPTION) {
3623     // management agent fails to start possibly due to
3624     // configuration problem and is responsible for printing
3625     // stack trace if appropriate. Simply exit VM.
3626     vm_exit(1);
3627   }
3628 #endif // INCLUDE_MANAGEMENT
3629 
3630   if (Arguments::has_profile())       FlatProfiler::engage(main_thread, true);
3631   if (MemProfiling)                   MemProfiler::engage();
3632   StatSampler::engage();
3633   if (CheckJNICalls)                  JniPeriodicChecker::engage();
3634 
3635   BiasedLocking::init();
3636 
3637 #if INCLUDE_RTM_OPT
3638   RTMLockingCounters::init();
3639 #endif
3640 
3641   if (JDK_Version::current().post_vm_init_hook_enabled()) {
3642     call_postVMInitHook(THREAD);
3643     // The Java side of PostVMInitHook.run must deal with all
3644     // exceptions and provide means of diagnosis.
3645     if (HAS_PENDING_EXCEPTION) {
3646       CLEAR_PENDING_EXCEPTION;
3647     }
3648   }
3649 
3650   {
3651       MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
3652       // Make sure the watcher thread can be started by WatcherThread::start()
3653       // or by dynamic enrollment.
3654       WatcherThread::make_startable();
3655       // Start up the WatcherThread if there are any periodic tasks
3656       // NOTE:  All PeriodicTasks should be registered by now. If they
3657       //   aren't, late joiners might appear to start slowly (we might
3658       //   take a while to process their first tick).
3659       if (PeriodicTask::num_tasks() > 0) {
3660           WatcherThread::start();
3661       }
3662   }
3663 
3664   // Give os specific code one last chance to start
3665   os::init_3();
3666 
3667   create_vm_timer.end();
3668 #ifdef ASSERT
3669   _vm_complete = true;
3670 #endif
3671   return JNI_OK;
3672 }
3673 
3674 // type for the Agent_OnLoad and JVM_OnLoad entry points
3675 extern "C" {
3676   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3677 }
3678 // Find a command line agent library and return its entry point for
3679 //         -agentlib:  -agentpath:   -Xrun
3680 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3681 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, const char *on_load_symbols[], size_t num_symbol_entries) {
3682   OnLoadEntry_t on_load_entry = NULL;
3683   void *library = NULL;
3684 
3685   if (!agent->valid()) {
3686     char buffer[JVM_MAXPATHLEN];
3687     char ebuf[1024];
3688     const char *name = agent->name();
3689     const char *msg = "Could not find agent library ";
3690 
3691     // First check to see if agent is statically linked into executable
3692     if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3693       library = agent->os_lib();
3694     } else if (agent->is_absolute_path()) {
3695       library = os::dll_load(name, ebuf, sizeof ebuf);
3696       if (library == NULL) {
3697         const char *sub_msg = " in absolute path, with error: ";
3698         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3699         char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3700         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3701         // If we can't find the agent, exit.
3702         vm_exit_during_initialization(buf, NULL);
3703         FREE_C_HEAP_ARRAY(char, buf, mtThread);
3704       }
3705     } else {
3706       // Try to load the agent from the standard dll directory
3707       if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3708                              name)) {
3709         library = os::dll_load(buffer, ebuf, sizeof ebuf);
3710       }
3711       if (library == NULL) { // Try the local directory
3712         char ns[1] = {0};
3713         if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3714           library = os::dll_load(buffer, ebuf, sizeof ebuf);
3715         }
3716         if (library == NULL) {
3717           const char *sub_msg = " on the library path, with error: ";
3718           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3719           char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3720           jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3721           // If we can't find the agent, exit.
3722           vm_exit_during_initialization(buf, NULL);
3723           FREE_C_HEAP_ARRAY(char, buf, mtThread);
3724         }
3725       }
3726     }
3727     agent->set_os_lib(library);
3728     agent->set_valid();
3729   }
3730 
3731   // Find the OnLoad function.
3732   on_load_entry =
3733     CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3734                                                           false,
3735                                                           on_load_symbols,
3736                                                           num_symbol_entries));
3737   return on_load_entry;
3738 }
3739 
3740 // Find the JVM_OnLoad entry point
3741 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3742   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3743   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3744 }
3745 
3746 // Find the Agent_OnLoad entry point
3747 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3748   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3749   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3750 }
3751 
3752 // For backwards compatibility with -Xrun
3753 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3754 // treated like -agentpath:
3755 // Must be called before agent libraries are created
3756 void Threads::convert_vm_init_libraries_to_agents() {
3757   AgentLibrary* agent;
3758   AgentLibrary* next;
3759 
3760   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3761     next = agent->next();  // cache the next agent now as this agent may get moved off this list
3762     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3763 
3764     // If there is an JVM_OnLoad function it will get called later,
3765     // otherwise see if there is an Agent_OnLoad
3766     if (on_load_entry == NULL) {
3767       on_load_entry = lookup_agent_on_load(agent);
3768       if (on_load_entry != NULL) {
3769         // switch it to the agent list -- so that Agent_OnLoad will be called,
3770         // JVM_OnLoad won't be attempted and Agent_OnUnload will
3771         Arguments::convert_library_to_agent(agent);
3772       } else {
3773         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3774       }
3775     }
3776   }
3777 }
3778 
3779 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
3780 // Invokes Agent_OnLoad
3781 // Called very early -- before JavaThreads exist
3782 void Threads::create_vm_init_agents() {
3783   extern struct JavaVM_ main_vm;
3784   AgentLibrary* agent;
3785 
3786   JvmtiExport::enter_onload_phase();
3787 
3788   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3789     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
3790 
3791     if (on_load_entry != NULL) {
3792       // Invoke the Agent_OnLoad function
3793       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3794       if (err != JNI_OK) {
3795         vm_exit_during_initialization("agent library failed to init", agent->name());
3796       }
3797     } else {
3798       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3799     }
3800   }
3801   JvmtiExport::enter_primordial_phase();
3802 }
3803 
3804 extern "C" {
3805   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3806 }
3807 
3808 void Threads::shutdown_vm_agents() {
3809   // Send any Agent_OnUnload notifications
3810   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3811   size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
3812   extern struct JavaVM_ main_vm;
3813   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3814 
3815     // Find the Agent_OnUnload function.
3816     Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3817       os::find_agent_function(agent,
3818       false,
3819       on_unload_symbols,
3820       num_symbol_entries));
3821 
3822     // Invoke the Agent_OnUnload function
3823     if (unload_entry != NULL) {
3824       JavaThread* thread = JavaThread::current();
3825       ThreadToNativeFromVM ttn(thread);
3826       HandleMark hm(thread);
3827       (*unload_entry)(&main_vm);
3828     }
3829   }
3830 }
3831 
3832 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
3833 // Invokes JVM_OnLoad
3834 void Threads::create_vm_init_libraries() {
3835   extern struct JavaVM_ main_vm;
3836   AgentLibrary* agent;
3837 
3838   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
3839     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3840 
3841     if (on_load_entry != NULL) {
3842       // Invoke the JVM_OnLoad function
3843       JavaThread* thread = JavaThread::current();
3844       ThreadToNativeFromVM ttn(thread);
3845       HandleMark hm(thread);
3846       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3847       if (err != JNI_OK) {
3848         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
3849       }
3850     } else {
3851       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
3852     }
3853   }
3854 }
3855 
3856 // Last thread running calls java.lang.Shutdown.shutdown()
3857 void JavaThread::invoke_shutdown_hooks() {
3858   HandleMark hm(this);
3859 
3860   // We could get here with a pending exception, if so clear it now.
3861   if (this->has_pending_exception()) {
3862     this->clear_pending_exception();
3863   }
3864 
3865   EXCEPTION_MARK;
3866   Klass* k =
3867     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
3868                                       THREAD);
3869   if (k != NULL) {
3870     // SystemDictionary::resolve_or_null will return null if there was
3871     // an exception.  If we cannot load the Shutdown class, just don't
3872     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
3873     // and finalizers (if runFinalizersOnExit is set) won't be run.
3874     // Note that if a shutdown hook was registered or runFinalizersOnExit
3875     // was called, the Shutdown class would have already been loaded
3876     // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
3877     instanceKlassHandle shutdown_klass (THREAD, k);
3878     JavaValue result(T_VOID);
3879     JavaCalls::call_static(&result,
3880                            shutdown_klass,
3881                            vmSymbols::shutdown_method_name(),
3882                            vmSymbols::void_method_signature(),
3883                            THREAD);
3884   }
3885   CLEAR_PENDING_EXCEPTION;
3886 }
3887 
3888 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
3889 // the program falls off the end of main(). Another VM exit path is through
3890 // vm_exit() when the program calls System.exit() to return a value or when
3891 // there is a serious error in VM. The two shutdown paths are not exactly
3892 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
3893 // and VM_Exit op at VM level.
3894 //
3895 // Shutdown sequence:
3896 //   + Shutdown native memory tracking if it is on
3897 //   + Wait until we are the last non-daemon thread to execute
3898 //     <-- every thing is still working at this moment -->
3899 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
3900 //        shutdown hooks, run finalizers if finalization-on-exit
3901 //   + Call before_exit(), prepare for VM exit
3902 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
3903 //        currently the only user of this mechanism is File.deleteOnExit())
3904 //      > stop flat profiler, StatSampler, watcher thread, CMS threads,
3905 //        post thread end and vm death events to JVMTI,
3906 //        stop signal thread
3907 //   + Call JavaThread::exit(), it will:
3908 //      > release JNI handle blocks, remove stack guard pages
3909 //      > remove this thread from Threads list
3910 //     <-- no more Java code from this thread after this point -->
3911 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
3912 //     the compiler threads at safepoint
3913 //     <-- do not use anything that could get blocked by Safepoint -->
3914 //   + Disable tracing at JNI/JVM barriers
3915 //   + Set _vm_exited flag for threads that are still running native code
3916 //   + Delete this thread
3917 //   + Call exit_globals()
3918 //      > deletes tty
3919 //      > deletes PerfMemory resources
3920 //   + Return to caller
3921 
3922 bool Threads::destroy_vm() {
3923   JavaThread* thread = JavaThread::current();
3924 
3925 #ifdef ASSERT
3926   _vm_complete = false;
3927 #endif
3928   // Wait until we are the last non-daemon thread to execute
3929   { MutexLocker nu(Threads_lock);
3930     while (Threads::number_of_non_daemon_threads() > 1 )
3931       // This wait should make safepoint checks, wait without a timeout,
3932       // and wait as a suspend-equivalent condition.
3933       //
3934       // Note: If the FlatProfiler is running and this thread is waiting
3935       // for another non-daemon thread to finish, then the FlatProfiler
3936       // is waiting for the external suspend request on this thread to
3937       // complete. wait_for_ext_suspend_completion() will eventually
3938       // timeout, but that takes time. Making this wait a suspend-
3939       // equivalent condition solves that timeout problem.
3940       //
3941       Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
3942                          Mutex::_as_suspend_equivalent_flag);
3943   }
3944 
3945   // Hang forever on exit if we are reporting an error.
3946   if (ShowMessageBoxOnError && is_error_reported()) {
3947     os::infinite_sleep();
3948   }
3949   os::wait_for_keypress_at_exit();
3950 
3951   if (JDK_Version::is_jdk12x_version()) {
3952     // We are the last thread running, so check if finalizers should be run.
3953     // For 1.3 or later this is done in thread->invoke_shutdown_hooks()
3954     HandleMark rm(thread);
3955     Universe::run_finalizers_on_exit();
3956   } else {
3957     // run Java level shutdown hooks
3958     thread->invoke_shutdown_hooks();
3959   }
3960 
3961   before_exit(thread);
3962 
3963   thread->exit(true);
3964 
3965   // Stop VM thread.
3966   {
3967     // 4945125 The vm thread comes to a safepoint during exit.
3968     // GC vm_operations can get caught at the safepoint, and the
3969     // heap is unparseable if they are caught. Grab the Heap_lock
3970     // to prevent this. The GC vm_operations will not be able to
3971     // queue until after the vm thread is dead. After this point,
3972     // we'll never emerge out of the safepoint before the VM exits.
3973 
3974     MutexLocker ml(Heap_lock);
3975 
3976     VMThread::wait_for_vm_thread_exit();
3977     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
3978     VMThread::destroy();
3979   }
3980 
3981   // clean up ideal graph printers
3982 #if defined(COMPILER2) && !defined(PRODUCT)
3983   IdealGraphPrinter::clean_up();
3984 #endif
3985 
3986   // Now, all Java threads are gone except daemon threads. Daemon threads
3987   // running Java code or in VM are stopped by the Safepoint. However,
3988   // daemon threads executing native code are still running.  But they
3989   // will be stopped at native=>Java/VM barriers. Note that we can't
3990   // simply kill or suspend them, as it is inherently deadlock-prone.
3991 
3992 #ifndef PRODUCT
3993   // disable function tracing at JNI/JVM barriers
3994   TraceJNICalls = false;
3995   TraceJVMCalls = false;
3996   TraceRuntimeCalls = false;
3997 #endif
3998 
3999   VM_Exit::set_vm_exited();
4000 
4001   notify_vm_shutdown();
4002 
4003   delete thread;
4004 
4005   // exit_globals() will delete tty
4006   exit_globals();
4007 
4008   return true;
4009 }
4010 
4011 
4012 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4013   if (version == JNI_VERSION_1_1) return JNI_TRUE;
4014   return is_supported_jni_version(version);
4015 }
4016 
4017 
4018 jboolean Threads::is_supported_jni_version(jint version) {
4019   if (version == JNI_VERSION_1_2) return JNI_TRUE;
4020   if (version == JNI_VERSION_1_4) return JNI_TRUE;
4021   if (version == JNI_VERSION_1_6) return JNI_TRUE;
4022   if (version == JNI_VERSION_1_8) return JNI_TRUE;
4023   return JNI_FALSE;
4024 }
4025 
4026 
4027 void Threads::add(JavaThread* p, bool force_daemon) {
4028   // The threads lock must be owned at this point
4029   assert_locked_or_safepoint(Threads_lock);
4030 
4031   // See the comment for this method in thread.hpp for its purpose and
4032   // why it is called here.
4033   p->initialize_queues();
4034   p->set_next(_thread_list);
4035   _thread_list = p;
4036   _number_of_threads++;
4037   oop threadObj = p->threadObj();
4038   bool daemon = true;
4039   // Bootstrapping problem: threadObj can be null for initial
4040   // JavaThread (or for threads attached via JNI)
4041   if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4042     _number_of_non_daemon_threads++;
4043     daemon = false;
4044   }
4045 
4046   p->set_safepoint_visible(true);
4047 
4048   ThreadService::add_thread(p, daemon);
4049 
4050   // Possible GC point.
4051   Events::log(p, "Thread added: " INTPTR_FORMAT, p);
4052 }
4053 
4054 void Threads::remove(JavaThread* p) {
4055   // Extra scope needed for Thread_lock, so we can check
4056   // that we do not remove thread without safepoint code notice
4057   { MutexLocker ml(Threads_lock);
4058 
4059     assert(includes(p), "p must be present");
4060 
4061     JavaThread* current = _thread_list;
4062     JavaThread* prev    = NULL;
4063 
4064     while (current != p) {
4065       prev    = current;
4066       current = current->next();
4067     }
4068 
4069     if (prev) {
4070       prev->set_next(current->next());
4071     } else {
4072       _thread_list = p->next();
4073     }
4074     _number_of_threads--;
4075     oop threadObj = p->threadObj();
4076     bool daemon = true;
4077     if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4078       _number_of_non_daemon_threads--;
4079       daemon = false;
4080 
4081       // Only one thread left, do a notify on the Threads_lock so a thread waiting
4082       // on destroy_vm will wake up.
4083       if (number_of_non_daemon_threads() == 1)
4084         Threads_lock->notify_all();
4085     }
4086     ThreadService::remove_thread(p, daemon);
4087 
4088     // Make sure that safepoint code disregard this thread. This is needed since
4089     // the thread might mess around with locks after this point. This can cause it
4090     // to do callbacks into the safepoint code. However, the safepoint code is not aware
4091     // of this thread since it is removed from the queue.
4092     p->set_terminated_value();
4093 
4094     // Now, this thread is not visible to safepoint
4095     p->set_safepoint_visible(false);
4096     // once the thread becomes safepoint invisible, we can not use its per-thread
4097     // recorder. And Threads::do_threads() no longer walks this thread, so we have
4098     // to release its per-thread recorder here.
4099     MemTracker::thread_exiting(p);
4100   } // unlock Threads_lock
4101 
4102   // Since Events::log uses a lock, we grab it outside the Threads_lock
4103   Events::log(p, "Thread exited: " INTPTR_FORMAT, p);
4104 }
4105 
4106 // Threads_lock must be held when this is called (or must be called during a safepoint)
4107 bool Threads::includes(JavaThread* p) {
4108   assert(Threads_lock->is_locked(), "sanity check");
4109   ALL_JAVA_THREADS(q) {
4110     if (q == p ) {
4111       return true;
4112     }
4113   }
4114   return false;
4115 }
4116 
4117 // Operations on the Threads list for GC.  These are not explicitly locked,
4118 // but the garbage collector must provide a safe context for them to run.
4119 // In particular, these things should never be called when the Threads_lock
4120 // is held by some other thread. (Note: the Safepoint abstraction also
4121 // uses the Threads_lock to guarantee this property. It also makes sure that
4122 // all threads gets blocked when exiting or starting).
4123 
4124 void Threads::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
4125   ALL_JAVA_THREADS(p) {
4126     p->oops_do(f, cld_f, cf);
4127   }
4128   VMThread::vm_thread()->oops_do(f, cld_f, cf);
4129 }
4130 
4131 void Threads::possibly_parallel_oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
4132   // Introduce a mechanism allowing parallel threads to claim threads as
4133   // root groups.  Overhead should be small enough to use all the time,
4134   // even in sequential code.
4135   SharedHeap* sh = SharedHeap::heap();
4136   // Cannot yet substitute active_workers for n_par_threads
4137   // because of G1CollectedHeap::verify() use of
4138   // SharedHeap::process_strong_roots().  n_par_threads == 0 will
4139   // turn off parallelism in process_strong_roots while active_workers
4140   // is being used for parallelism elsewhere.
4141   bool is_par = sh->n_par_threads() > 0;
4142   assert(!is_par ||
4143          (SharedHeap::heap()->n_par_threads() ==
4144           SharedHeap::heap()->workers()->active_workers()), "Mismatch");
4145   int cp = SharedHeap::heap()->strong_roots_parity();
4146   ALL_JAVA_THREADS(p) {
4147     if (p->claim_oops_do(is_par, cp)) {
4148       p->oops_do(f, cld_f, cf);
4149     }
4150   }
4151   VMThread* vmt = VMThread::vm_thread();
4152   if (vmt->claim_oops_do(is_par, cp)) {
4153     vmt->oops_do(f, cld_f, cf);
4154   }
4155 }
4156 
4157 #if INCLUDE_ALL_GCS
4158 // Used by ParallelScavenge
4159 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4160   ALL_JAVA_THREADS(p) {
4161     q->enqueue(new ThreadRootsTask(p));
4162   }
4163   q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4164 }
4165 
4166 // Used by Parallel Old
4167 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4168   ALL_JAVA_THREADS(p) {
4169     q->enqueue(new ThreadRootsMarkingTask(p));
4170   }
4171   q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4172 }
4173 #endif // INCLUDE_ALL_GCS
4174 
4175 void Threads::nmethods_do(CodeBlobClosure* cf) {
4176   ALL_JAVA_THREADS(p) {
4177     p->nmethods_do(cf);
4178   }
4179   VMThread::vm_thread()->nmethods_do(cf);
4180 }
4181 
4182 void Threads::metadata_do(void f(Metadata*)) {
4183   ALL_JAVA_THREADS(p) {
4184     p->metadata_do(f);
4185   }
4186 }
4187 
4188 void Threads::gc_epilogue() {
4189   ALL_JAVA_THREADS(p) {
4190     p->gc_epilogue();
4191   }
4192 }
4193 
4194 void Threads::gc_prologue() {
4195   ALL_JAVA_THREADS(p) {
4196     p->gc_prologue();
4197   }
4198 }
4199 
4200 void Threads::deoptimized_wrt_marked_nmethods() {
4201   ALL_JAVA_THREADS(p) {
4202     p->deoptimized_wrt_marked_nmethods();
4203   }
4204 }
4205 
4206 
4207 // Get count Java threads that are waiting to enter the specified monitor.
4208 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4209   address monitor, bool doLock) {
4210   assert(doLock || SafepointSynchronize::is_at_safepoint(),
4211     "must grab Threads_lock or be at safepoint");
4212   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4213 
4214   int i = 0;
4215   {
4216     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4217     ALL_JAVA_THREADS(p) {
4218       if (p->is_Compiler_thread()) continue;
4219 
4220       address pending = (address)p->current_pending_monitor();
4221       if (pending == monitor) {             // found a match
4222         if (i < count) result->append(p);   // save the first count matches
4223         i++;
4224       }
4225     }
4226   }
4227   return result;
4228 }
4229 
4230 
4231 JavaThread *Threads::owning_thread_from_monitor_owner(address owner, bool doLock) {
4232   assert(doLock ||
4233          Threads_lock->owned_by_self() ||
4234          SafepointSynchronize::is_at_safepoint(),
4235          "must grab Threads_lock or be at safepoint");
4236 
4237   // NULL owner means not locked so we can skip the search
4238   if (owner == NULL) return NULL;
4239 
4240   {
4241     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4242     ALL_JAVA_THREADS(p) {
4243       // first, see if owner is the address of a Java thread
4244       if (owner == (address)p) return p;
4245     }
4246   }
4247   // Cannot assert on lack of success here since this function may be
4248   // used by code that is trying to report useful problem information
4249   // like deadlock detection.
4250   if (UseHeavyMonitors) return NULL;
4251 
4252   //
4253   // If we didn't find a matching Java thread and we didn't force use of
4254   // heavyweight monitors, then the owner is the stack address of the
4255   // Lock Word in the owning Java thread's stack.
4256   //
4257   JavaThread* the_owner = NULL;
4258   {
4259     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4260     ALL_JAVA_THREADS(q) {
4261       if (q->is_lock_owned(owner)) {
4262         the_owner = q;
4263         break;
4264       }
4265     }
4266   }
4267   // cannot assert on lack of success here; see above comment
4268   return the_owner;
4269 }
4270 
4271 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4272 void Threads::print_on(outputStream* st, bool print_stacks, bool internal_format, bool print_concurrent_locks) {
4273   char buf[32];
4274   st->print_cr("%s", os::local_time_string(buf, sizeof(buf)));
4275 
4276   st->print_cr("Full thread dump %s (%s %s):",
4277                 Abstract_VM_Version::vm_name(),
4278                 Abstract_VM_Version::vm_release(),
4279                 Abstract_VM_Version::vm_info_string()
4280                );
4281   st->cr();
4282 
4283 #if INCLUDE_ALL_GCS
4284   // Dump concurrent locks
4285   ConcurrentLocksDump concurrent_locks;
4286   if (print_concurrent_locks) {
4287     concurrent_locks.dump_at_safepoint();
4288   }
4289 #endif // INCLUDE_ALL_GCS
4290 
4291   ALL_JAVA_THREADS(p) {
4292     ResourceMark rm;
4293     p->print_on(st);
4294     if (print_stacks) {
4295       if (internal_format) {
4296         p->trace_stack();
4297       } else {
4298         p->print_stack_on(st);
4299       }
4300     }
4301     st->cr();
4302 #if INCLUDE_ALL_GCS
4303     if (print_concurrent_locks) {
4304       concurrent_locks.print_locks_on(p, st);
4305     }
4306 #endif // INCLUDE_ALL_GCS
4307   }
4308 
4309   VMThread::vm_thread()->print_on(st);
4310   st->cr();
4311   Universe::heap()->print_gc_threads_on(st);
4312   WatcherThread* wt = WatcherThread::watcher_thread();
4313   if (wt != NULL) {
4314     wt->print_on(st);
4315     st->cr();
4316   }
4317   CompileBroker::print_compiler_threads_on(st);
4318   st->flush();
4319 }
4320 
4321 // Threads::print_on_error() is called by fatal error handler. It's possible
4322 // that VM is not at safepoint and/or current thread is inside signal handler.
4323 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4324 // memory (even in resource area), it might deadlock the error handler.
4325 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, int buflen) {
4326   bool found_current = false;
4327   st->print_cr("Java Threads: ( => current thread )");
4328   ALL_JAVA_THREADS(thread) {
4329     bool is_current = (current == thread);
4330     found_current = found_current || is_current;
4331 
4332     st->print("%s", is_current ? "=>" : "  ");
4333 
4334     st->print(PTR_FORMAT, thread);
4335     st->print(" ");
4336     thread->print_on_error(st, buf, buflen);
4337     st->cr();
4338   }
4339   st->cr();
4340 
4341   st->print_cr("Other Threads:");
4342   if (VMThread::vm_thread()) {
4343     bool is_current = (current == VMThread::vm_thread());
4344     found_current = found_current || is_current;
4345     st->print("%s", current == VMThread::vm_thread() ? "=>" : "  ");
4346 
4347     st->print(PTR_FORMAT, VMThread::vm_thread());
4348     st->print(" ");
4349     VMThread::vm_thread()->print_on_error(st, buf, buflen);
4350     st->cr();
4351   }
4352   WatcherThread* wt = WatcherThread::watcher_thread();
4353   if (wt != NULL) {
4354     bool is_current = (current == wt);
4355     found_current = found_current || is_current;
4356     st->print("%s", is_current ? "=>" : "  ");
4357 
4358     st->print(PTR_FORMAT, wt);
4359     st->print(" ");
4360     wt->print_on_error(st, buf, buflen);
4361     st->cr();
4362   }
4363   if (!found_current) {
4364     st->cr();
4365     st->print("=>" PTR_FORMAT " (exited) ", current);
4366     current->print_on_error(st, buf, buflen);
4367     st->cr();
4368   }
4369 }
4370 
4371 // Internal SpinLock and Mutex
4372 // Based on ParkEvent
4373 
4374 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4375 //
4376 // We employ SpinLocks _only for low-contention, fixed-length
4377 // short-duration critical sections where we're concerned
4378 // about native mutex_t or HotSpot Mutex:: latency.
4379 // The mux construct provides a spin-then-block mutual exclusion
4380 // mechanism.
4381 //
4382 // Testing has shown that contention on the ListLock guarding gFreeList
4383 // is common.  If we implement ListLock as a simple SpinLock it's common
4384 // for the JVM to devolve to yielding with little progress.  This is true
4385 // despite the fact that the critical sections protected by ListLock are
4386 // extremely short.
4387 //
4388 // TODO-FIXME: ListLock should be of type SpinLock.
4389 // We should make this a 1st-class type, integrated into the lock
4390 // hierarchy as leaf-locks.  Critically, the SpinLock structure
4391 // should have sufficient padding to avoid false-sharing and excessive
4392 // cache-coherency traffic.
4393 
4394 
4395 typedef volatile int SpinLockT ;
4396 
4397 void Thread::SpinAcquire (volatile int * adr, const char * LockName) {
4398   if (Atomic::cmpxchg (1, adr, 0) == 0) {
4399      return ;   // normal fast-path return
4400   }
4401 
4402   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4403   TEVENT (SpinAcquire - ctx) ;
4404   int ctr = 0 ;
4405   int Yields = 0 ;
4406   for (;;) {
4407      while (*adr != 0) {
4408         ++ctr ;
4409         if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4410            if (Yields > 5) {
4411              os::naked_short_sleep(1);
4412            } else {
4413              os::NakedYield() ;
4414              ++Yields ;
4415            }
4416         } else {
4417            SpinPause() ;
4418         }
4419      }
4420      if (Atomic::cmpxchg (1, adr, 0) == 0) return ;
4421   }
4422 }
4423 
4424 void Thread::SpinRelease (volatile int * adr) {
4425   assert (*adr != 0, "invariant") ;
4426   OrderAccess::fence() ;      // guarantee at least release consistency.
4427   // Roach-motel semantics.
4428   // It's safe if subsequent LDs and STs float "up" into the critical section,
4429   // but prior LDs and STs within the critical section can't be allowed
4430   // to reorder or float past the ST that releases the lock.
4431   *adr = 0 ;
4432 }
4433 
4434 // muxAcquire and muxRelease:
4435 //
4436 // *  muxAcquire and muxRelease support a single-word lock-word construct.
4437 //    The LSB of the word is set IFF the lock is held.
4438 //    The remainder of the word points to the head of a singly-linked list
4439 //    of threads blocked on the lock.
4440 //
4441 // *  The current implementation of muxAcquire-muxRelease uses its own
4442 //    dedicated Thread._MuxEvent instance.  If we're interested in
4443 //    minimizing the peak number of extant ParkEvent instances then
4444 //    we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4445 //    as certain invariants were satisfied.  Specifically, care would need
4446 //    to be taken with regards to consuming unpark() "permits".
4447 //    A safe rule of thumb is that a thread would never call muxAcquire()
4448 //    if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4449 //    park().  Otherwise the _ParkEvent park() operation in muxAcquire() could
4450 //    consume an unpark() permit intended for monitorenter, for instance.
4451 //    One way around this would be to widen the restricted-range semaphore
4452 //    implemented in park().  Another alternative would be to provide
4453 //    multiple instances of the PlatformEvent() for each thread.  One
4454 //    instance would be dedicated to muxAcquire-muxRelease, for instance.
4455 //
4456 // *  Usage:
4457 //    -- Only as leaf locks
4458 //    -- for short-term locking only as muxAcquire does not perform
4459 //       thread state transitions.
4460 //
4461 // Alternatives:
4462 // *  We could implement muxAcquire and muxRelease with MCS or CLH locks
4463 //    but with parking or spin-then-park instead of pure spinning.
4464 // *  Use Taura-Oyama-Yonenzawa locks.
4465 // *  It's possible to construct a 1-0 lock if we encode the lockword as
4466 //    (List,LockByte).  Acquire will CAS the full lockword while Release
4467 //    will STB 0 into the LockByte.  The 1-0 scheme admits stranding, so
4468 //    acquiring threads use timers (ParkTimed) to detect and recover from
4469 //    the stranding window.  Thread/Node structures must be aligned on 256-byte
4470 //    boundaries by using placement-new.
4471 // *  Augment MCS with advisory back-link fields maintained with CAS().
4472 //    Pictorially:  LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4473 //    The validity of the backlinks must be ratified before we trust the value.
4474 //    If the backlinks are invalid the exiting thread must back-track through the
4475 //    the forward links, which are always trustworthy.
4476 // *  Add a successor indication.  The LockWord is currently encoded as
4477 //    (List, LOCKBIT:1).  We could also add a SUCCBIT or an explicit _succ variable
4478 //    to provide the usual futile-wakeup optimization.
4479 //    See RTStt for details.
4480 // *  Consider schedctl.sc_nopreempt to cover the critical section.
4481 //
4482 
4483 
4484 typedef volatile intptr_t MutexT ;      // Mux Lock-word
4485 enum MuxBits { LOCKBIT = 1 } ;
4486 
4487 void Thread::muxAcquire (volatile intptr_t * Lock, const char * LockName) {
4488   intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ;
4489   if (w == 0) return ;
4490   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4491      return ;
4492   }
4493 
4494   TEVENT (muxAcquire - Contention) ;
4495   ParkEvent * const Self = Thread::current()->_MuxEvent ;
4496   assert ((intptr_t(Self) & LOCKBIT) == 0, "invariant") ;
4497   for (;;) {
4498      int its = (os::is_MP() ? 100 : 0) + 1 ;
4499 
4500      // Optional spin phase: spin-then-park strategy
4501      while (--its >= 0) {
4502        w = *Lock ;
4503        if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4504           return ;
4505        }
4506      }
4507 
4508      Self->reset() ;
4509      Self->OnList = intptr_t(Lock) ;
4510      // The following fence() isn't _strictly necessary as the subsequent
4511      // CAS() both serializes execution and ratifies the fetched *Lock value.
4512      OrderAccess::fence();
4513      for (;;) {
4514         w = *Lock ;
4515         if ((w & LOCKBIT) == 0) {
4516             if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4517                 Self->OnList = 0 ;   // hygiene - allows stronger asserts
4518                 return ;
4519             }
4520             continue ;      // Interference -- *Lock changed -- Just retry
4521         }
4522         assert (w & LOCKBIT, "invariant") ;
4523         Self->ListNext = (ParkEvent *) (w & ~LOCKBIT );
4524         if (Atomic::cmpxchg_ptr (intptr_t(Self)|LOCKBIT, Lock, w) == w) break ;
4525      }
4526 
4527      while (Self->OnList != 0) {
4528         Self->park() ;
4529      }
4530   }
4531 }
4532 
4533 void Thread::muxAcquireW (volatile intptr_t * Lock, ParkEvent * ev) {
4534   intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ;
4535   if (w == 0) return ;
4536   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4537     return ;
4538   }
4539 
4540   TEVENT (muxAcquire - Contention) ;
4541   ParkEvent * ReleaseAfter = NULL ;
4542   if (ev == NULL) {
4543     ev = ReleaseAfter = ParkEvent::Allocate (NULL) ;
4544   }
4545   assert ((intptr_t(ev) & LOCKBIT) == 0, "invariant") ;
4546   for (;;) {
4547     guarantee (ev->OnList == 0, "invariant") ;
4548     int its = (os::is_MP() ? 100 : 0) + 1 ;
4549 
4550     // Optional spin phase: spin-then-park strategy
4551     while (--its >= 0) {
4552       w = *Lock ;
4553       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4554         if (ReleaseAfter != NULL) {
4555           ParkEvent::Release (ReleaseAfter) ;
4556         }
4557         return ;
4558       }
4559     }
4560 
4561     ev->reset() ;
4562     ev->OnList = intptr_t(Lock) ;
4563     // The following fence() isn't _strictly necessary as the subsequent
4564     // CAS() both serializes execution and ratifies the fetched *Lock value.
4565     OrderAccess::fence();
4566     for (;;) {
4567       w = *Lock ;
4568       if ((w & LOCKBIT) == 0) {
4569         if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4570           ev->OnList = 0 ;
4571           // We call ::Release while holding the outer lock, thus
4572           // artificially lengthening the critical section.
4573           // Consider deferring the ::Release() until the subsequent unlock(),
4574           // after we've dropped the outer lock.
4575           if (ReleaseAfter != NULL) {
4576             ParkEvent::Release (ReleaseAfter) ;
4577           }
4578           return ;
4579         }
4580         continue ;      // Interference -- *Lock changed -- Just retry
4581       }
4582       assert (w & LOCKBIT, "invariant") ;
4583       ev->ListNext = (ParkEvent *) (w & ~LOCKBIT );
4584       if (Atomic::cmpxchg_ptr (intptr_t(ev)|LOCKBIT, Lock, w) == w) break ;
4585     }
4586 
4587     while (ev->OnList != 0) {
4588       ev->park() ;
4589     }
4590   }
4591 }
4592 
4593 // Release() must extract a successor from the list and then wake that thread.
4594 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4595 // similar to that used by ParkEvent::Allocate() and ::Release().  DMR-based
4596 // Release() would :
4597 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4598 // (B) Extract a successor from the private list "in-hand"
4599 // (C) attempt to CAS() the residual back into *Lock over null.
4600 //     If there were any newly arrived threads and the CAS() would fail.
4601 //     In that case Release() would detach the RATs, re-merge the list in-hand
4602 //     with the RATs and repeat as needed.  Alternately, Release() might
4603 //     detach and extract a successor, but then pass the residual list to the wakee.
4604 //     The wakee would be responsible for reattaching and remerging before it
4605 //     competed for the lock.
4606 //
4607 // Both "pop" and DMR are immune from ABA corruption -- there can be
4608 // multiple concurrent pushers, but only one popper or detacher.
4609 // This implementation pops from the head of the list.  This is unfair,
4610 // but tends to provide excellent throughput as hot threads remain hot.
4611 // (We wake recently run threads first).
4612 
4613 void Thread::muxRelease (volatile intptr_t * Lock)  {
4614   for (;;) {
4615     const intptr_t w = Atomic::cmpxchg_ptr (0, Lock, LOCKBIT) ;
4616     assert (w & LOCKBIT, "invariant") ;
4617     if (w == LOCKBIT) return ;
4618     ParkEvent * List = (ParkEvent *) (w & ~LOCKBIT) ;
4619     assert (List != NULL, "invariant") ;
4620     assert (List->OnList == intptr_t(Lock), "invariant") ;
4621     ParkEvent * nxt = List->ListNext ;
4622 
4623     // The following CAS() releases the lock and pops the head element.
4624     if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4625       continue ;
4626     }
4627     List->OnList = 0 ;
4628     OrderAccess::fence() ;
4629     List->unpark () ;
4630     return ;
4631   }
4632 }
4633 
4634 
4635 void Threads::verify() {
4636   ALL_JAVA_THREADS(p) {
4637     p->verify();
4638   }
4639   VMThread* thread = VMThread::vm_thread();
4640   if (thread != NULL) thread->verify();
4641 }