1 /*
   2  * Copyright (c) 1997, 2017, 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 "jvm.h"
  27 #include "classfile/classLoader.hpp"
  28 #include "classfile/javaClasses.hpp"
  29 #include "classfile/moduleEntry.hpp"
  30 #include "classfile/systemDictionary.hpp"
  31 #include "classfile/vmSymbols.hpp"
  32 #include "code/codeCache.hpp"
  33 #include "code/scopeDesc.hpp"
  34 #include "compiler/compileBroker.hpp"
  35 #include "compiler/compileTask.hpp"
  36 #include "gc/shared/gcId.hpp"
  37 #include "gc/shared/gcLocker.inline.hpp"
  38 #include "gc/shared/workgroup.hpp"
  39 #include "interpreter/interpreter.hpp"
  40 #include "interpreter/linkResolver.hpp"
  41 #include "interpreter/oopMapCache.hpp"
  42 #include "jvmtifiles/jvmtiEnv.hpp"
  43 #include "logging/log.hpp"
  44 #include "logging/logConfiguration.hpp"
  45 #include "logging/logStream.hpp"
  46 #include "memory/metaspaceShared.hpp"
  47 #include "memory/oopFactory.hpp"
  48 #include "memory/resourceArea.hpp"
  49 #include "memory/universe.inline.hpp"
  50 #include "oops/instanceKlass.hpp"
  51 #include "oops/objArrayOop.hpp"
  52 #include "oops/oop.inline.hpp"
  53 #include "oops/symbol.hpp"
  54 #include "oops/verifyOopClosure.hpp"
  55 #include "prims/jvm_misc.hpp"
  56 #include "prims/jvmtiExport.hpp"
  57 #include "prims/jvmtiThreadState.hpp"
  58 #include "prims/privilegedStack.hpp"
  59 #include "runtime/arguments.hpp"
  60 #include "runtime/atomic.hpp"
  61 #include "runtime/biasedLocking.hpp"
  62 #include "runtime/commandLineFlagConstraintList.hpp"
  63 #include "runtime/commandLineFlagWriteableList.hpp"
  64 #include "runtime/commandLineFlagRangeList.hpp"
  65 #include "runtime/deoptimization.hpp"
  66 #include "runtime/frame.inline.hpp"
  67 #include "runtime/globals.hpp"
  68 #include "runtime/handshake.hpp"
  69 #include "runtime/init.hpp"
  70 #include "runtime/interfaceSupport.hpp"
  71 #include "runtime/java.hpp"
  72 #include "runtime/javaCalls.hpp"
  73 #include "runtime/jniPeriodicChecker.hpp"
  74 #include "runtime/memprofiler.hpp"
  75 #include "runtime/mutexLocker.hpp"
  76 #include "runtime/objectMonitor.hpp"
  77 #include "runtime/orderAccess.inline.hpp"
  78 #include "runtime/osThread.hpp"
  79 #include "runtime/prefetch.inline.hpp"
  80 #include "runtime/safepoint.hpp"
  81 #include "runtime/safepointMechanism.inline.hpp"
  82 #include "runtime/sharedRuntime.hpp"
  83 #include "runtime/statSampler.hpp"
  84 #include "runtime/stubRoutines.hpp"
  85 #include "runtime/sweeper.hpp"
  86 #include "runtime/task.hpp"
  87 #include "runtime/thread.inline.hpp"
  88 #include "runtime/threadCritical.hpp"
  89 #include "runtime/threadSMR.inline.hpp"
  90 #include "runtime/timer.hpp"
  91 #include "runtime/timerTrace.hpp"
  92 #include "runtime/vframe.hpp"
  93 #include "runtime/vframeArray.hpp"
  94 #include "runtime/vframe_hp.hpp"
  95 #include "runtime/vmThread.hpp"
  96 #include "runtime/vm_operations.hpp"
  97 #include "runtime/vm_version.hpp"
  98 #include "services/attachListener.hpp"
  99 #include "services/management.hpp"
 100 #include "services/memTracker.hpp"
 101 #include "services/threadService.hpp"
 102 #include "trace/traceMacros.hpp"
 103 #include "trace/tracing.hpp"
 104 #include "utilities/align.hpp"
 105 #include "utilities/defaultStream.hpp"
 106 #include "utilities/dtrace.hpp"
 107 #include "utilities/events.hpp"
 108 #include "utilities/macros.hpp"
 109 #include "utilities/preserveException.hpp"
 110 #include "utilities/vmError.hpp"
 111 #if INCLUDE_ALL_GCS
 112 #include "gc/cms/concurrentMarkSweepThread.hpp"
 113 #include "gc/g1/concurrentMarkThread.inline.hpp"
 114 #include "gc/parallel/pcTasks.hpp"
 115 #endif // INCLUDE_ALL_GCS
 116 #if INCLUDE_JVMCI
 117 #include "jvmci/jvmciCompiler.hpp"
 118 #include "jvmci/jvmciRuntime.hpp"
 119 #include "logging/logHandle.hpp"
 120 #endif
 121 #ifdef COMPILER1
 122 #include "c1/c1_Compiler.hpp"
 123 #endif
 124 #ifdef COMPILER2
 125 #include "opto/c2compiler.hpp"
 126 #include "opto/idealGraphPrinter.hpp"
 127 #endif
 128 #if INCLUDE_RTM_OPT
 129 #include "runtime/rtmLocking.hpp"
 130 #endif
 131 
 132 // Initialization after module runtime initialization
 133 void universe_post_module_init();  // must happen after call_initPhase2
 134 
 135 #ifdef DTRACE_ENABLED
 136 
 137 // Only bother with this argument setup if dtrace is available
 138 
 139   #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
 140   #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
 141 
 142   #define DTRACE_THREAD_PROBE(probe, javathread)                           \
 143     {                                                                      \
 144       ResourceMark rm(this);                                               \
 145       int len = 0;                                                         \
 146       const char* name = (javathread)->get_thread_name();                  \
 147       len = strlen(name);                                                  \
 148       HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */               \
 149         (char *) name, len,                                                \
 150         java_lang_Thread::thread_id((javathread)->threadObj()),            \
 151         (uintptr_t) (javathread)->osthread()->thread_id(),                 \
 152         java_lang_Thread::is_daemon((javathread)->threadObj()));           \
 153     }
 154 
 155 #else //  ndef DTRACE_ENABLED
 156 
 157   #define DTRACE_THREAD_PROBE(probe, javathread)
 158 
 159 #endif // ndef DTRACE_ENABLED
 160 
 161 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 162 // Current thread is maintained as a thread-local variable
 163 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
 164 #endif
 165 // Class hierarchy
 166 // - Thread
 167 //   - VMThread
 168 //   - WatcherThread
 169 //   - ConcurrentMarkSweepThread
 170 //   - JavaThread
 171 //     - CompilerThread
 172 
 173 // ======= Thread ========
 174 // Support for forcing alignment of thread objects for biased locking
 175 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
 176   if (UseBiasedLocking) {
 177     const int alignment = markOopDesc::biased_lock_alignment;
 178     size_t aligned_size = size + (alignment - sizeof(intptr_t));
 179     void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
 180                                           : AllocateHeap(aligned_size, flags, CURRENT_PC,
 181                                                          AllocFailStrategy::RETURN_NULL);
 182     void* aligned_addr     = align_up(real_malloc_addr, alignment);
 183     assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
 184            ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
 185            "JavaThread alignment code overflowed allocated storage");
 186     if (aligned_addr != real_malloc_addr) {
 187       log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
 188                               p2i(real_malloc_addr),
 189                               p2i(aligned_addr));
 190     }
 191     ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
 192     return aligned_addr;
 193   } else {
 194     return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
 195                        : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
 196   }
 197 }
 198 
 199 void Thread::operator delete(void* p) {
 200   if (UseBiasedLocking) {
 201     FreeHeap(((Thread*) p)->_real_malloc_address);
 202   } else {
 203     FreeHeap(p);
 204   }
 205 }
 206 
 207 void JavaThread::smr_delete() {
 208   if (_on_thread_list) {
 209     ThreadsSMRSupport::smr_delete(this);
 210   } else {
 211     delete this;
 212   }
 213 }
 214 
 215 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
 216 // JavaThread
 217 
 218 
 219 Thread::Thread() {
 220   // stack and get_thread
 221   set_stack_base(NULL);
 222   set_stack_size(0);
 223   set_self_raw_id(0);
 224   set_lgrp_id(-1);
 225   DEBUG_ONLY(clear_suspendible_thread();)
 226 
 227   // allocated data structures
 228   set_osthread(NULL);
 229   set_resource_area(new (mtThread)ResourceArea());
 230   DEBUG_ONLY(_current_resource_mark = NULL;)
 231   set_handle_area(new (mtThread) HandleArea(NULL));
 232   set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
 233   set_active_handles(NULL);
 234   set_free_handle_block(NULL);
 235   set_last_handle_mark(NULL);
 236 
 237   // This initial value ==> never claimed.
 238   _oops_do_parity = 0;
 239   _threads_hazard_ptr = NULL;
 240   _nested_threads_hazard_ptr = NULL;
 241   _nested_threads_hazard_ptr_cnt = 0;
 242 
 243   // the handle mark links itself to last_handle_mark
 244   new HandleMark(this);
 245 
 246   // plain initialization
 247   debug_only(_owned_locks = NULL;)
 248   debug_only(_allow_allocation_count = 0;)
 249   NOT_PRODUCT(_allow_safepoint_count = 0;)
 250   NOT_PRODUCT(_skip_gcalot = false;)
 251   _jvmti_env_iteration_count = 0;
 252   set_allocated_bytes(0);
 253   _vm_operation_started_count = 0;
 254   _vm_operation_completed_count = 0;
 255   _current_pending_monitor = NULL;
 256   _current_pending_monitor_is_from_java = true;
 257   _current_waiting_monitor = NULL;
 258   _num_nested_signal = 0;
 259   omFreeList = NULL;
 260   omFreeCount = 0;
 261   omFreeProvision = 32;
 262   omInUseList = NULL;
 263   omInUseCount = 0;
 264 
 265 #ifdef ASSERT
 266   _visited_for_critical_count = false;
 267 #endif
 268 
 269   _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
 270                          Monitor::_safepoint_check_sometimes);
 271   _suspend_flags = 0;
 272 
 273   // thread-specific hashCode stream generator state - Marsaglia shift-xor form
 274   _hashStateX = os::random();
 275   _hashStateY = 842502087;
 276   _hashStateZ = 0x8767;    // (int)(3579807591LL & 0xffff) ;
 277   _hashStateW = 273326509;
 278 
 279   _OnTrap   = 0;
 280   _schedctl = NULL;
 281   _Stalled  = 0;
 282   _TypeTag  = 0x2BAD;
 283 
 284   // Many of the following fields are effectively final - immutable
 285   // Note that nascent threads can't use the Native Monitor-Mutex
 286   // construct until the _MutexEvent is initialized ...
 287   // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
 288   // we might instead use a stack of ParkEvents that we could provision on-demand.
 289   // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
 290   // and ::Release()
 291   _ParkEvent   = ParkEvent::Allocate(this);
 292   _SleepEvent  = ParkEvent::Allocate(this);
 293   _MutexEvent  = ParkEvent::Allocate(this);
 294   _MuxEvent    = ParkEvent::Allocate(this);
 295 
 296 #ifdef CHECK_UNHANDLED_OOPS
 297   if (CheckUnhandledOops) {
 298     _unhandled_oops = new UnhandledOops(this);
 299   }
 300 #endif // CHECK_UNHANDLED_OOPS
 301 #ifdef ASSERT
 302   if (UseBiasedLocking) {
 303     assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
 304     assert(this == _real_malloc_address ||
 305            this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
 306            "bug in forced alignment of thread objects");
 307   }
 308 #endif // ASSERT
 309 
 310   _oom_during_evac = 0;
 311   _gclab = NULL;
 312 }
 313 
 314 void Thread::set_oom_during_evac(bool oom) {
 315   if (oom) {
 316     _oom_during_evac |= 1;
 317   } else {
 318     _oom_during_evac &= ~1;
 319   }
 320 }
 321 
 322 bool Thread::is_oom_during_evac() const {
 323   return (_oom_during_evac & 1) == 1;
 324 }
 325 
 326 #ifdef ASSERT
 327 void Thread::set_evac_allowed(bool evac_allowed) {
 328   if (evac_allowed) {
 329     _oom_during_evac |= 2;
 330   } else {
 331     _oom_during_evac &= ~2;
 332   }
 333 }
 334 
 335 bool Thread::is_evac_allowed() const {
 336   return (_oom_during_evac & 2) == 2;
 337 }
 338 #endif
 339 
 340 void Thread::initialize_thread_current() {
 341 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 342   assert(_thr_current == NULL, "Thread::current already initialized");
 343   _thr_current = this;
 344 #endif
 345   assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
 346   ThreadLocalStorage::set_thread(this);
 347   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 348 }
 349 
 350 void Thread::clear_thread_current() {
 351   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 352 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 353   _thr_current = NULL;
 354 #endif
 355   ThreadLocalStorage::set_thread(NULL);
 356 }
 357 
 358 void Thread::record_stack_base_and_size() {
 359   set_stack_base(os::current_stack_base());
 360   set_stack_size(os::current_stack_size());
 361   // CR 7190089: on Solaris, primordial thread's stack is adjusted
 362   // in initialize_thread(). Without the adjustment, stack size is
 363   // incorrect if stack is set to unlimited (ulimit -s unlimited).
 364   // So far, only Solaris has real implementation of initialize_thread().
 365   //
 366   // set up any platform-specific state.
 367   os::initialize_thread(this);
 368 
 369   // Set stack limits after thread is initialized.
 370   if (is_Java_thread()) {
 371     ((JavaThread*) this)->set_stack_overflow_limit();
 372     ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
 373   }
 374 #if INCLUDE_NMT
 375   // record thread's native stack, stack grows downward
 376   MemTracker::record_thread_stack(stack_end(), stack_size());
 377 #endif // INCLUDE_NMT
 378   log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
 379     PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
 380     os::current_thread_id(), p2i(stack_base() - stack_size()),
 381     p2i(stack_base()), stack_size()/1024);
 382 }
 383 
 384 
 385 Thread::~Thread() {
 386   EVENT_THREAD_DESTRUCT(this);
 387 
 388   // stack_base can be NULL if the thread is never started or exited before
 389   // record_stack_base_and_size called. Although, we would like to ensure
 390   // that all started threads do call record_stack_base_and_size(), there is
 391   // not proper way to enforce that.
 392 #if INCLUDE_NMT
 393   if (_stack_base != NULL) {
 394     MemTracker::release_thread_stack(stack_end(), stack_size());
 395 #ifdef ASSERT
 396     set_stack_base(NULL);
 397 #endif
 398   }
 399 #endif // INCLUDE_NMT
 400 
 401   // deallocate data structures
 402   delete resource_area();
 403   // since the handle marks are using the handle area, we have to deallocated the root
 404   // handle mark before deallocating the thread's handle area,
 405   assert(last_handle_mark() != NULL, "check we have an element");
 406   delete last_handle_mark();
 407   assert(last_handle_mark() == NULL, "check we have reached the end");
 408 
 409   // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
 410   // We NULL out the fields for good hygiene.
 411   ParkEvent::Release(_ParkEvent); _ParkEvent   = NULL;
 412   ParkEvent::Release(_SleepEvent); _SleepEvent  = NULL;
 413   ParkEvent::Release(_MutexEvent); _MutexEvent  = NULL;
 414   ParkEvent::Release(_MuxEvent); _MuxEvent    = NULL;
 415 
 416   delete handle_area();
 417   delete metadata_handles();
 418 
 419   // SR_handler uses this as a termination indicator -
 420   // needs to happen before os::free_thread()
 421   delete _SR_lock;
 422   _SR_lock = NULL;
 423 
 424   // osthread() can be NULL, if creation of thread failed.
 425   if (osthread() != NULL) os::free_thread(osthread());
 426 
 427   // clear Thread::current if thread is deleting itself.
 428   // Needed to ensure JNI correctly detects non-attached threads.
 429   if (this == Thread::current()) {
 430     clear_thread_current();
 431   }
 432 
 433   CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
 434 }
 435 
 436 // NOTE: dummy function for assertion purpose.
 437 void Thread::run() {
 438   ShouldNotReachHere();
 439 }
 440 
 441 #ifdef ASSERT
 442 // A JavaThread is considered "dangling" if it is not the current
 443 // thread, has been added the Threads list, the system is not at a
 444 // safepoint and the Thread is not "protected".
 445 //
 446 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
 447   assert(!thread->is_Java_thread() || Thread::current() == thread ||
 448          !((JavaThread *) thread)->on_thread_list() ||
 449          SafepointSynchronize::is_at_safepoint() ||
 450          ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
 451          "possibility of dangling Thread pointer");
 452 }
 453 #endif
 454 
 455 ThreadPriority Thread::get_priority(const Thread* const thread) {
 456   ThreadPriority priority;
 457   // Can return an error!
 458   (void)os::get_priority(thread, priority);
 459   assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
 460   return priority;
 461 }
 462 
 463 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
 464   debug_only(check_for_dangling_thread_pointer(thread);)
 465   // Can return an error!
 466   (void)os::set_priority(thread, priority);
 467 }
 468 
 469 
 470 void Thread::start(Thread* thread) {
 471   // Start is different from resume in that its safety is guaranteed by context or
 472   // being called from a Java method synchronized on the Thread object.
 473   if (!DisableStartThread) {
 474     if (thread->is_Java_thread()) {
 475       // Initialize the thread state to RUNNABLE before starting this thread.
 476       // Can not set it after the thread started because we do not know the
 477       // exact thread state at that time. It could be in MONITOR_WAIT or
 478       // in SLEEPING or some other state.
 479       java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
 480                                           java_lang_Thread::RUNNABLE);
 481     }
 482     os::start_thread(thread);
 483   }
 484 }
 485 
 486 // Enqueue a VM_Operation to do the job for us - sometime later
 487 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
 488   VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
 489   VMThread::execute(vm_stop);
 490 }
 491 
 492 
 493 // Check if an external suspend request has completed (or has been
 494 // cancelled). Returns true if the thread is externally suspended and
 495 // false otherwise.
 496 //
 497 // The bits parameter returns information about the code path through
 498 // the routine. Useful for debugging:
 499 //
 500 // set in is_ext_suspend_completed():
 501 // 0x00000001 - routine was entered
 502 // 0x00000010 - routine return false at end
 503 // 0x00000100 - thread exited (return false)
 504 // 0x00000200 - suspend request cancelled (return false)
 505 // 0x00000400 - thread suspended (return true)
 506 // 0x00001000 - thread is in a suspend equivalent state (return true)
 507 // 0x00002000 - thread is native and walkable (return true)
 508 // 0x00004000 - thread is native_trans and walkable (needed retry)
 509 //
 510 // set in wait_for_ext_suspend_completion():
 511 // 0x00010000 - routine was entered
 512 // 0x00020000 - suspend request cancelled before loop (return false)
 513 // 0x00040000 - thread suspended before loop (return true)
 514 // 0x00080000 - suspend request cancelled in loop (return false)
 515 // 0x00100000 - thread suspended in loop (return true)
 516 // 0x00200000 - suspend not completed during retry loop (return false)
 517 
 518 // Helper class for tracing suspend wait debug bits.
 519 //
 520 // 0x00000100 indicates that the target thread exited before it could
 521 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
 522 // 0x00080000 each indicate a cancelled suspend request so they don't
 523 // count as wait failures either.
 524 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
 525 
 526 class TraceSuspendDebugBits : public StackObj {
 527  private:
 528   JavaThread * jt;
 529   bool         is_wait;
 530   bool         called_by_wait;  // meaningful when !is_wait
 531   uint32_t *   bits;
 532 
 533  public:
 534   TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
 535                         uint32_t *_bits) {
 536     jt             = _jt;
 537     is_wait        = _is_wait;
 538     called_by_wait = _called_by_wait;
 539     bits           = _bits;
 540   }
 541 
 542   ~TraceSuspendDebugBits() {
 543     if (!is_wait) {
 544 #if 1
 545       // By default, don't trace bits for is_ext_suspend_completed() calls.
 546       // That trace is very chatty.
 547       return;
 548 #else
 549       if (!called_by_wait) {
 550         // If tracing for is_ext_suspend_completed() is enabled, then only
 551         // trace calls to it from wait_for_ext_suspend_completion()
 552         return;
 553       }
 554 #endif
 555     }
 556 
 557     if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
 558       if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
 559         MutexLocker ml(Threads_lock);  // needed for get_thread_name()
 560         ResourceMark rm;
 561 
 562         tty->print_cr(
 563                       "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
 564                       jt->get_thread_name(), *bits);
 565 
 566         guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
 567       }
 568     }
 569   }
 570 };
 571 #undef DEBUG_FALSE_BITS
 572 
 573 
 574 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
 575                                           uint32_t *bits) {
 576   TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
 577 
 578   bool did_trans_retry = false;  // only do thread_in_native_trans retry once
 579   bool do_trans_retry;           // flag to force the retry
 580 
 581   *bits |= 0x00000001;
 582 
 583   do {
 584     do_trans_retry = false;
 585 
 586     if (is_exiting()) {
 587       // Thread is in the process of exiting. This is always checked
 588       // first to reduce the risk of dereferencing a freed JavaThread.
 589       *bits |= 0x00000100;
 590       return false;
 591     }
 592 
 593     if (!is_external_suspend()) {
 594       // Suspend request is cancelled. This is always checked before
 595       // is_ext_suspended() to reduce the risk of a rogue resume
 596       // confusing the thread that made the suspend request.
 597       *bits |= 0x00000200;
 598       return false;
 599     }
 600 
 601     if (is_ext_suspended()) {
 602       // thread is suspended
 603       *bits |= 0x00000400;
 604       return true;
 605     }
 606 
 607     // Now that we no longer do hard suspends of threads running
 608     // native code, the target thread can be changing thread state
 609     // while we are in this routine:
 610     //
 611     //   _thread_in_native -> _thread_in_native_trans -> _thread_blocked
 612     //
 613     // We save a copy of the thread state as observed at this moment
 614     // and make our decision about suspend completeness based on the
 615     // copy. This closes the race where the thread state is seen as
 616     // _thread_in_native_trans in the if-thread_blocked check, but is
 617     // seen as _thread_blocked in if-thread_in_native_trans check.
 618     JavaThreadState save_state = thread_state();
 619 
 620     if (save_state == _thread_blocked && is_suspend_equivalent()) {
 621       // If the thread's state is _thread_blocked and this blocking
 622       // condition is known to be equivalent to a suspend, then we can
 623       // consider the thread to be externally suspended. This means that
 624       // the code that sets _thread_blocked has been modified to do
 625       // self-suspension if the blocking condition releases. We also
 626       // used to check for CONDVAR_WAIT here, but that is now covered by
 627       // the _thread_blocked with self-suspension check.
 628       //
 629       // Return true since we wouldn't be here unless there was still an
 630       // external suspend request.
 631       *bits |= 0x00001000;
 632       return true;
 633     } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
 634       // Threads running native code will self-suspend on native==>VM/Java
 635       // transitions. If its stack is walkable (should always be the case
 636       // unless this function is called before the actual java_suspend()
 637       // call), then the wait is done.
 638       *bits |= 0x00002000;
 639       return true;
 640     } else if (!called_by_wait && !did_trans_retry &&
 641                save_state == _thread_in_native_trans &&
 642                frame_anchor()->walkable()) {
 643       // The thread is transitioning from thread_in_native to another
 644       // thread state. check_safepoint_and_suspend_for_native_trans()
 645       // will force the thread to self-suspend. If it hasn't gotten
 646       // there yet we may have caught the thread in-between the native
 647       // code check above and the self-suspend. Lucky us. If we were
 648       // called by wait_for_ext_suspend_completion(), then it
 649       // will be doing the retries so we don't have to.
 650       //
 651       // Since we use the saved thread state in the if-statement above,
 652       // there is a chance that the thread has already transitioned to
 653       // _thread_blocked by the time we get here. In that case, we will
 654       // make a single unnecessary pass through the logic below. This
 655       // doesn't hurt anything since we still do the trans retry.
 656 
 657       *bits |= 0x00004000;
 658 
 659       // Once the thread leaves thread_in_native_trans for another
 660       // thread state, we break out of this retry loop. We shouldn't
 661       // need this flag to prevent us from getting back here, but
 662       // sometimes paranoia is good.
 663       did_trans_retry = true;
 664 
 665       // We wait for the thread to transition to a more usable state.
 666       for (int i = 1; i <= SuspendRetryCount; i++) {
 667         // We used to do an "os::yield_all(i)" call here with the intention
 668         // that yielding would increase on each retry. However, the parameter
 669         // is ignored on Linux which means the yield didn't scale up. Waiting
 670         // on the SR_lock below provides a much more predictable scale up for
 671         // the delay. It also provides a simple/direct point to check for any
 672         // safepoint requests from the VMThread
 673 
 674         // temporarily drops SR_lock while doing wait with safepoint check
 675         // (if we're a JavaThread - the WatcherThread can also call this)
 676         // and increase delay with each retry
 677         SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 678 
 679         // check the actual thread state instead of what we saved above
 680         if (thread_state() != _thread_in_native_trans) {
 681           // the thread has transitioned to another thread state so
 682           // try all the checks (except this one) one more time.
 683           do_trans_retry = true;
 684           break;
 685         }
 686       } // end retry loop
 687 
 688 
 689     }
 690   } while (do_trans_retry);
 691 
 692   *bits |= 0x00000010;
 693   return false;
 694 }
 695 
 696 // Wait for an external suspend request to complete (or be cancelled).
 697 // Returns true if the thread is externally suspended and false otherwise.
 698 //
 699 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
 700                                                  uint32_t *bits) {
 701   TraceSuspendDebugBits tsdb(this, true /* is_wait */,
 702                              false /* !called_by_wait */, bits);
 703 
 704   // local flag copies to minimize SR_lock hold time
 705   bool is_suspended;
 706   bool pending;
 707   uint32_t reset_bits;
 708 
 709   // set a marker so is_ext_suspend_completed() knows we are the caller
 710   *bits |= 0x00010000;
 711 
 712   // We use reset_bits to reinitialize the bits value at the top of
 713   // each retry loop. This allows the caller to make use of any
 714   // unused bits for their own marking purposes.
 715   reset_bits = *bits;
 716 
 717   {
 718     MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
 719     is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 720                                             delay, bits);
 721     pending = is_external_suspend();
 722   }
 723   // must release SR_lock to allow suspension to complete
 724 
 725   if (!pending) {
 726     // A cancelled suspend request is the only false return from
 727     // is_ext_suspend_completed() that keeps us from entering the
 728     // retry loop.
 729     *bits |= 0x00020000;
 730     return false;
 731   }
 732 
 733   if (is_suspended) {
 734     *bits |= 0x00040000;
 735     return true;
 736   }
 737 
 738   for (int i = 1; i <= retries; i++) {
 739     *bits = reset_bits;  // reinit to only track last retry
 740 
 741     // We used to do an "os::yield_all(i)" call here with the intention
 742     // that yielding would increase on each retry. However, the parameter
 743     // is ignored on Linux which means the yield didn't scale up. Waiting
 744     // on the SR_lock below provides a much more predictable scale up for
 745     // the delay. It also provides a simple/direct point to check for any
 746     // safepoint requests from the VMThread
 747 
 748     {
 749       MutexLocker ml(SR_lock());
 750       // wait with safepoint check (if we're a JavaThread - the WatcherThread
 751       // can also call this)  and increase delay with each retry
 752       SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 753 
 754       is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 755                                               delay, bits);
 756 
 757       // It is possible for the external suspend request to be cancelled
 758       // (by a resume) before the actual suspend operation is completed.
 759       // Refresh our local copy to see if we still need to wait.
 760       pending = is_external_suspend();
 761     }
 762 
 763     if (!pending) {
 764       // A cancelled suspend request is the only false return from
 765       // is_ext_suspend_completed() that keeps us from staying in the
 766       // retry loop.
 767       *bits |= 0x00080000;
 768       return false;
 769     }
 770 
 771     if (is_suspended) {
 772       *bits |= 0x00100000;
 773       return true;
 774     }
 775   } // end retry loop
 776 
 777   // thread did not suspend after all our retries
 778   *bits |= 0x00200000;
 779   return false;
 780 }
 781 
 782 // Called from API entry points which perform stack walking. If the
 783 // associated JavaThread is the current thread, then wait_for_suspend
 784 // is not used. Otherwise, it determines if we should wait for the
 785 // "other" thread to complete external suspension. (NOTE: in future
 786 // releases the suspension mechanism should be reimplemented so this
 787 // is not necessary.)
 788 //
 789 bool
 790 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
 791   if (this != JavaThread::current()) {
 792     // "other" threads require special handling.
 793     if (wait_for_suspend) {
 794       // We are allowed to wait for the external suspend to complete
 795       // so give the other thread a chance to get suspended.
 796       if (!wait_for_ext_suspend_completion(SuspendRetryCount,
 797                                            SuspendRetryDelay, bits)) {
 798         // Didn't make it so let the caller know.
 799         return false;
 800       }
 801     }
 802     // We aren't allowed to wait for the external suspend to complete
 803     // so if the other thread isn't externally suspended we need to
 804     // let the caller know.
 805     else if (!is_ext_suspend_completed_with_lock(bits)) {
 806       return false;
 807     }
 808   }
 809 
 810   return true;
 811 }
 812 
 813 #ifndef PRODUCT
 814 void JavaThread::record_jump(address target, address instr, const char* file,
 815                              int line) {
 816 
 817   // This should not need to be atomic as the only way for simultaneous
 818   // updates is via interrupts. Even then this should be rare or non-existent
 819   // and we don't care that much anyway.
 820 
 821   int index = _jmp_ring_index;
 822   _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
 823   _jmp_ring[index]._target = (intptr_t) target;
 824   _jmp_ring[index]._instruction = (intptr_t) instr;
 825   _jmp_ring[index]._file = file;
 826   _jmp_ring[index]._line = line;
 827 }
 828 #endif // PRODUCT
 829 
 830 void Thread::interrupt(Thread* thread) {
 831   debug_only(check_for_dangling_thread_pointer(thread);)
 832   os::interrupt(thread);
 833 }
 834 
 835 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
 836   debug_only(check_for_dangling_thread_pointer(thread);)
 837   // Note:  If clear_interrupted==false, this simply fetches and
 838   // returns the value of the field osthread()->interrupted().
 839   return os::is_interrupted(thread, clear_interrupted);
 840 }
 841 
 842 
 843 // GC Support
 844 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
 845   int thread_parity = _oops_do_parity;
 846   if (thread_parity != strong_roots_parity) {
 847     jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
 848     if (res == thread_parity) {
 849       return true;
 850     } else {
 851       guarantee(res == strong_roots_parity, "Or else what?");
 852       return false;
 853     }
 854   }
 855   return false;
 856 }
 857 
 858 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
 859   active_handles()->oops_do(f);
 860   // Do oop for ThreadShadow
 861   f->do_oop((oop*)&_pending_exception);
 862   handle_area()->oops_do(f);
 863 
 864   if (MonitorInUseLists) {
 865     // When using thread local monitor lists, we scan them here,
 866     // and the remaining global monitors in ObjectSynchronizer::oops_do().
 867     VM_Operation* op = VMThread::vm_operation();
 868     if (op != NULL && op->deflates_idle_monitors()) {
 869       DeflateMonitorCounters counters; // Dummy for now.
 870       ObjectSynchronizer::deflate_thread_local_monitors(this, &counters, f);
 871     } else {
 872       ObjectSynchronizer::thread_local_used_oops_do(this, f);
 873     }
 874   }
 875 }
 876 
 877 void Thread::metadata_handles_do(void f(Metadata*)) {
 878   // Only walk the Handles in Thread.
 879   if (metadata_handles() != NULL) {
 880     for (int i = 0; i< metadata_handles()->length(); i++) {
 881       f(metadata_handles()->at(i));
 882     }
 883   }
 884 }
 885 
 886 void Thread::print_on(outputStream* st) const {
 887   // get_priority assumes osthread initialized
 888   if (osthread() != NULL) {
 889     int os_prio;
 890     if (os::get_native_priority(this, &os_prio) == OS_OK) {
 891       st->print("os_prio=%d ", os_prio);
 892     }
 893     st->print("tid=" INTPTR_FORMAT " ", p2i(this));
 894     ext().print_on(st);
 895     osthread()->print_on(st);
 896   }
 897   if (_threads_hazard_ptr != NULL) {
 898     st->print("_threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
 899   }
 900   if (_nested_threads_hazard_ptr != NULL) {
 901     print_nested_threads_hazard_ptrs_on(st);
 902   }
 903   st->print(" ");
 904   debug_only(if (WizardMode) print_owned_locks_on(st);)
 905 }
 906 
 907 void Thread::print_nested_threads_hazard_ptrs_on(outputStream* st) const {
 908   assert(_nested_threads_hazard_ptr != NULL, "must be set to print");
 909 
 910   if (EnableThreadSMRStatistics) {
 911     st->print(", _nested_threads_hazard_ptr_cnt=%u", _nested_threads_hazard_ptr_cnt);
 912   }
 913   st->print(", _nested_threads_hazard_ptrs=");
 914   for (NestedThreadsList* node = _nested_threads_hazard_ptr; node != NULL;
 915        node = node->next()) {
 916     if (node != _nested_threads_hazard_ptr) {
 917       // First node does not need a comma-space separator.
 918       st->print(", ");
 919     }
 920     st->print(INTPTR_FORMAT, p2i(node->t_list()));
 921   }
 922 }
 923 
 924 // Thread::print_on_error() is called by fatal error handler. Don't use
 925 // any lock or allocate memory.
 926 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
 927   assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
 928 
 929   if (is_VM_thread())                 { st->print("VMThread"); }
 930   else if (is_GC_task_thread())       { st->print("GCTaskThread"); }
 931   else if (is_Watcher_thread())       { st->print("WatcherThread"); }
 932   else if (is_ConcurrentGC_thread())  { st->print("ConcurrentGCThread"); }
 933   else                                { st->print("Thread"); }
 934 
 935   if (is_Named_thread()) {
 936     st->print(" \"%s\"", name());
 937   }
 938 
 939   st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
 940             p2i(stack_end()), p2i(stack_base()));
 941 
 942   if (osthread()) {
 943     st->print(" [id=%d]", osthread()->thread_id());
 944   }
 945 
 946   if (_threads_hazard_ptr != NULL) {
 947     st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
 948   }
 949   if (_nested_threads_hazard_ptr != NULL) {
 950     print_nested_threads_hazard_ptrs_on(st);
 951   }
 952 }
 953 
 954 void Thread::print_value_on(outputStream* st) const {
 955   if (is_Named_thread()) {
 956     st->print(" \"%s\" ", name());
 957   }
 958   st->print(INTPTR_FORMAT, p2i(this));   // print address
 959 }
 960 
 961 #ifdef ASSERT
 962 void Thread::print_owned_locks_on(outputStream* st) const {
 963   Monitor *cur = _owned_locks;
 964   if (cur == NULL) {
 965     st->print(" (no locks) ");
 966   } else {
 967     st->print_cr(" Locks owned:");
 968     while (cur) {
 969       cur->print_on(st);
 970       cur = cur->next();
 971     }
 972   }
 973 }
 974 
 975 static int ref_use_count  = 0;
 976 
 977 bool Thread::owns_locks_but_compiled_lock() const {
 978   for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 979     if (cur != Compile_lock) return true;
 980   }
 981   return false;
 982 }
 983 
 984 
 985 #endif
 986 
 987 #ifndef PRODUCT
 988 
 989 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially
 990 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
 991 // no threads which allow_vm_block's are held
 992 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
 993   // Check if current thread is allowed to block at a safepoint
 994   if (!(_allow_safepoint_count == 0)) {
 995     fatal("Possible safepoint reached by thread that does not allow it");
 996   }
 997   if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
 998     fatal("LEAF method calling lock?");
 999   }
1000 
1001 #ifdef ASSERT
1002   if (potential_vm_operation && is_Java_thread()
1003       && !Universe::is_bootstrapping()) {
1004     // Make sure we do not hold any locks that the VM thread also uses.
1005     // This could potentially lead to deadlocks
1006     for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
1007       // Threads_lock is special, since the safepoint synchronization will not start before this is
1008       // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
1009       // since it is used to transfer control between JavaThreads and the VMThread
1010       // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
1011       if ((cur->allow_vm_block() &&
1012            cur != Threads_lock &&
1013            cur != Compile_lock &&               // Temporary: should not be necessary when we get separate compilation
1014            cur != VMOperationRequest_lock &&
1015            cur != VMOperationQueue_lock) ||
1016            cur->rank() == Mutex::special) {
1017         fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
1018       }
1019     }
1020   }
1021 
1022   if (GCALotAtAllSafepoints) {
1023     // We could enter a safepoint here and thus have a gc
1024     InterfaceSupport::check_gc_alot();
1025   }
1026 #endif
1027 }
1028 #endif
1029 
1030 bool Thread::is_in_stack(address adr) const {
1031   assert(Thread::current() == this, "is_in_stack can only be called from current thread");
1032   address end = os::current_stack_pointer();
1033   // Allow non Java threads to call this without stack_base
1034   if (_stack_base == NULL) return true;
1035   if (stack_base() >= adr && adr >= end) return true;
1036 
1037   return false;
1038 }
1039 
1040 bool Thread::is_in_usable_stack(address adr) const {
1041   size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1042   size_t usable_stack_size = _stack_size - stack_guard_size;
1043 
1044   return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1045 }
1046 
1047 
1048 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1049 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1050 // used for compilation in the future. If that change is made, the need for these methods
1051 // should be revisited, and they should be removed if possible.
1052 
1053 bool Thread::is_lock_owned(address adr) const {
1054   return on_local_stack(adr);
1055 }
1056 
1057 bool Thread::set_as_starting_thread() {
1058   // NOTE: this must be called inside the main thread.
1059   return os::create_main_thread((JavaThread*)this);
1060 }
1061 
1062 static void initialize_class(Symbol* class_name, TRAPS) {
1063   Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1064   InstanceKlass::cast(klass)->initialize(CHECK);
1065 }
1066 
1067 
1068 // Creates the initial ThreadGroup
1069 static Handle create_initial_thread_group(TRAPS) {
1070   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
1071   InstanceKlass* ik = InstanceKlass::cast(k);
1072 
1073   Handle system_instance = ik->allocate_instance_handle(CHECK_NH);
1074   {
1075     JavaValue result(T_VOID);
1076     JavaCalls::call_special(&result,
1077                             system_instance,
1078                             ik,
1079                             vmSymbols::object_initializer_name(),
1080                             vmSymbols::void_method_signature(),
1081                             CHECK_NH);
1082   }
1083   Universe::set_system_thread_group(system_instance());
1084 
1085   Handle main_instance = ik->allocate_instance_handle(CHECK_NH);
1086   {
1087     JavaValue result(T_VOID);
1088     Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1089     JavaCalls::call_special(&result,
1090                             main_instance,
1091                             ik,
1092                             vmSymbols::object_initializer_name(),
1093                             vmSymbols::threadgroup_string_void_signature(),
1094                             system_instance,
1095                             string,
1096                             CHECK_NH);
1097   }
1098   return main_instance;
1099 }
1100 
1101 // Creates the initial Thread
1102 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1103                                  TRAPS) {
1104   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
1105   InstanceKlass* ik = InstanceKlass::cast(k);
1106   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1107 
1108   java_lang_Thread::set_thread(thread_oop(), thread);
1109   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1110   thread->set_threadObj(thread_oop());
1111 
1112   Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1113 
1114   JavaValue result(T_VOID);
1115   JavaCalls::call_special(&result, thread_oop,
1116                           ik,
1117                           vmSymbols::object_initializer_name(),
1118                           vmSymbols::threadgroup_string_void_signature(),
1119                           thread_group,
1120                           string,
1121                           CHECK_NULL);
1122   return thread_oop();
1123 }
1124 
1125 char java_runtime_name[128] = "";
1126 char java_runtime_version[128] = "";
1127 
1128 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1129 static const char* get_java_runtime_name(TRAPS) {
1130   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1131                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1132   fieldDescriptor fd;
1133   bool found = k != NULL &&
1134                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1135                                                         vmSymbols::string_signature(), &fd);
1136   if (found) {
1137     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1138     if (name_oop == NULL) {
1139       return NULL;
1140     }
1141     const char* name = java_lang_String::as_utf8_string(name_oop,
1142                                                         java_runtime_name,
1143                                                         sizeof(java_runtime_name));
1144     return name;
1145   } else {
1146     return NULL;
1147   }
1148 }
1149 
1150 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1151 static const char* get_java_runtime_version(TRAPS) {
1152   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1153                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1154   fieldDescriptor fd;
1155   bool found = k != NULL &&
1156                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1157                                                         vmSymbols::string_signature(), &fd);
1158   if (found) {
1159     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1160     if (name_oop == NULL) {
1161       return NULL;
1162     }
1163     const char* name = java_lang_String::as_utf8_string(name_oop,
1164                                                         java_runtime_version,
1165                                                         sizeof(java_runtime_version));
1166     return name;
1167   } else {
1168     return NULL;
1169   }
1170 }
1171 
1172 // General purpose hook into Java code, run once when the VM is initialized.
1173 // The Java library method itself may be changed independently from the VM.
1174 static void call_postVMInitHook(TRAPS) {
1175   Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1176   if (klass != NULL) {
1177     JavaValue result(T_VOID);
1178     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1179                            vmSymbols::void_method_signature(),
1180                            CHECK);
1181   }
1182 }
1183 
1184 static void reset_vm_info_property(TRAPS) {
1185   // the vm info string
1186   ResourceMark rm(THREAD);
1187   const char *vm_info = VM_Version::vm_info_string();
1188 
1189   // java.lang.System class
1190   Klass* klass =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1191 
1192   // setProperty arguments
1193   Handle key_str    = java_lang_String::create_from_str("java.vm.info", CHECK);
1194   Handle value_str  = java_lang_String::create_from_str(vm_info, CHECK);
1195 
1196   // return value
1197   JavaValue r(T_OBJECT);
1198 
1199   // public static String setProperty(String key, String value);
1200   JavaCalls::call_static(&r,
1201                          klass,
1202                          vmSymbols::setProperty_name(),
1203                          vmSymbols::string_string_string_signature(),
1204                          key_str,
1205                          value_str,
1206                          CHECK);
1207 }
1208 
1209 
1210 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1211                                     bool daemon, TRAPS) {
1212   assert(thread_group.not_null(), "thread group should be specified");
1213   assert(threadObj() == NULL, "should only create Java thread object once");
1214 
1215   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1216   InstanceKlass* ik = InstanceKlass::cast(k);
1217   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1218 
1219   java_lang_Thread::set_thread(thread_oop(), this);
1220   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1221   set_threadObj(thread_oop());
1222 
1223   JavaValue result(T_VOID);
1224   if (thread_name != NULL) {
1225     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1226     // Thread gets assigned specified name and null target
1227     JavaCalls::call_special(&result,
1228                             thread_oop,
1229                             ik,
1230                             vmSymbols::object_initializer_name(),
1231                             vmSymbols::threadgroup_string_void_signature(),
1232                             thread_group, // Argument 1
1233                             name,         // Argument 2
1234                             THREAD);
1235   } else {
1236     // Thread gets assigned name "Thread-nnn" and null target
1237     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1238     JavaCalls::call_special(&result,
1239                             thread_oop,
1240                             ik,
1241                             vmSymbols::object_initializer_name(),
1242                             vmSymbols::threadgroup_runnable_void_signature(),
1243                             thread_group, // Argument 1
1244                             Handle(),     // Argument 2
1245                             THREAD);
1246   }
1247 
1248 
1249   if (daemon) {
1250     java_lang_Thread::set_daemon(thread_oop());
1251   }
1252 
1253   if (HAS_PENDING_EXCEPTION) {
1254     return;
1255   }
1256 
1257   Klass* group =  SystemDictionary::ThreadGroup_klass();
1258   Handle threadObj(THREAD, this->threadObj());
1259 
1260   JavaCalls::call_special(&result,
1261                           thread_group,
1262                           group,
1263                           vmSymbols::add_method_name(),
1264                           vmSymbols::thread_void_signature(),
1265                           threadObj,          // Arg 1
1266                           THREAD);
1267 }
1268 
1269 // NamedThread --  non-JavaThread subclasses with multiple
1270 // uniquely named instances should derive from this.
1271 NamedThread::NamedThread() : Thread() {
1272   _name = NULL;
1273   _processed_thread = NULL;
1274   _gc_id = GCId::undefined();
1275 }
1276 
1277 NamedThread::~NamedThread() {
1278   if (_name != NULL) {
1279     FREE_C_HEAP_ARRAY(char, _name);
1280     _name = NULL;
1281   }
1282 }
1283 
1284 void NamedThread::set_name(const char* format, ...) {
1285   guarantee(_name == NULL, "Only get to set name once.");
1286   _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1287   guarantee(_name != NULL, "alloc failure");
1288   va_list ap;
1289   va_start(ap, format);
1290   jio_vsnprintf(_name, max_name_len, format, ap);
1291   va_end(ap);
1292 }
1293 
1294 void NamedThread::initialize_named_thread() {
1295   set_native_thread_name(name());
1296 }
1297 
1298 void NamedThread::print_on(outputStream* st) const {
1299   st->print("\"%s\" ", name());
1300   Thread::print_on(st);
1301   st->cr();
1302 }
1303 
1304 
1305 // ======= WatcherThread ========
1306 
1307 // The watcher thread exists to simulate timer interrupts.  It should
1308 // be replaced by an abstraction over whatever native support for
1309 // timer interrupts exists on the platform.
1310 
1311 WatcherThread* WatcherThread::_watcher_thread   = NULL;
1312 bool WatcherThread::_startable = false;
1313 volatile bool  WatcherThread::_should_terminate = false;
1314 
1315 WatcherThread::WatcherThread() : Thread() {
1316   assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1317   if (os::create_thread(this, os::watcher_thread)) {
1318     _watcher_thread = this;
1319 
1320     // Set the watcher thread to the highest OS priority which should not be
1321     // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1322     // is created. The only normal thread using this priority is the reference
1323     // handler thread, which runs for very short intervals only.
1324     // If the VMThread's priority is not lower than the WatcherThread profiling
1325     // will be inaccurate.
1326     os::set_priority(this, MaxPriority);
1327     if (!DisableStartThread) {
1328       os::start_thread(this);
1329     }
1330   }
1331 }
1332 
1333 int WatcherThread::sleep() const {
1334   // The WatcherThread does not participate in the safepoint protocol
1335   // for the PeriodicTask_lock because it is not a JavaThread.
1336   MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1337 
1338   if (_should_terminate) {
1339     // check for termination before we do any housekeeping or wait
1340     return 0;  // we did not sleep.
1341   }
1342 
1343   // remaining will be zero if there are no tasks,
1344   // causing the WatcherThread to sleep until a task is
1345   // enrolled
1346   int remaining = PeriodicTask::time_to_wait();
1347   int time_slept = 0;
1348 
1349   // we expect this to timeout - we only ever get unparked when
1350   // we should terminate or when a new task has been enrolled
1351   OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1352 
1353   jlong time_before_loop = os::javaTimeNanos();
1354 
1355   while (true) {
1356     bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1357                                             remaining);
1358     jlong now = os::javaTimeNanos();
1359 
1360     if (remaining == 0) {
1361       // if we didn't have any tasks we could have waited for a long time
1362       // consider the time_slept zero and reset time_before_loop
1363       time_slept = 0;
1364       time_before_loop = now;
1365     } else {
1366       // need to recalculate since we might have new tasks in _tasks
1367       time_slept = (int) ((now - time_before_loop) / 1000000);
1368     }
1369 
1370     // Change to task list or spurious wakeup of some kind
1371     if (timedout || _should_terminate) {
1372       break;
1373     }
1374 
1375     remaining = PeriodicTask::time_to_wait();
1376     if (remaining == 0) {
1377       // Last task was just disenrolled so loop around and wait until
1378       // another task gets enrolled
1379       continue;
1380     }
1381 
1382     remaining -= time_slept;
1383     if (remaining <= 0) {
1384       break;
1385     }
1386   }
1387 
1388   return time_slept;
1389 }
1390 
1391 void WatcherThread::run() {
1392   assert(this == watcher_thread(), "just checking");
1393 
1394   this->record_stack_base_and_size();
1395   this->set_native_thread_name(this->name());
1396   this->set_active_handles(JNIHandleBlock::allocate_block());
1397   while (true) {
1398     assert(watcher_thread() == Thread::current(), "thread consistency check");
1399     assert(watcher_thread() == this, "thread consistency check");
1400 
1401     // Calculate how long it'll be until the next PeriodicTask work
1402     // should be done, and sleep that amount of time.
1403     int time_waited = sleep();
1404 
1405     if (VMError::is_error_reported()) {
1406       // A fatal error has happened, the error handler(VMError::report_and_die)
1407       // should abort JVM after creating an error log file. However in some
1408       // rare cases, the error handler itself might deadlock. Here periodically
1409       // check for error reporting timeouts, and if it happens, just proceed to
1410       // abort the VM.
1411 
1412       // This code is in WatcherThread because WatcherThread wakes up
1413       // periodically so the fatal error handler doesn't need to do anything;
1414       // also because the WatcherThread is less likely to crash than other
1415       // threads.
1416 
1417       for (;;) {
1418         // Note: we use naked sleep in this loop because we want to avoid using
1419         // any kind of VM infrastructure which may be broken at this point.
1420         if (VMError::check_timeout()) {
1421           // We hit error reporting timeout. Error reporting was interrupted and
1422           // will be wrapping things up now (closing files etc). Give it some more
1423           // time, then quit the VM.
1424           os::naked_short_sleep(200);
1425           // Print a message to stderr.
1426           fdStream err(defaultStream::output_fd());
1427           err.print_raw_cr("# [ timer expired, abort... ]");
1428           // skip atexit/vm_exit/vm_abort hooks
1429           os::die();
1430         }
1431 
1432         // Wait a second, then recheck for timeout.
1433         os::naked_short_sleep(999);
1434       }
1435     }
1436 
1437     if (_should_terminate) {
1438       // check for termination before posting the next tick
1439       break;
1440     }
1441 
1442     PeriodicTask::real_time_tick(time_waited);
1443   }
1444 
1445   // Signal that it is terminated
1446   {
1447     MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1448     _watcher_thread = NULL;
1449     Terminator_lock->notify();
1450   }
1451 }
1452 
1453 void WatcherThread::start() {
1454   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1455 
1456   if (watcher_thread() == NULL && _startable) {
1457     _should_terminate = false;
1458     // Create the single instance of WatcherThread
1459     new WatcherThread();
1460   }
1461 }
1462 
1463 void WatcherThread::make_startable() {
1464   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1465   _startable = true;
1466 }
1467 
1468 void WatcherThread::stop() {
1469   {
1470     // Follow normal safepoint aware lock enter protocol since the
1471     // WatcherThread is stopped by another JavaThread.
1472     MutexLocker ml(PeriodicTask_lock);
1473     _should_terminate = true;
1474 
1475     WatcherThread* watcher = watcher_thread();
1476     if (watcher != NULL) {
1477       // unpark the WatcherThread so it can see that it should terminate
1478       watcher->unpark();
1479     }
1480   }
1481 
1482   MutexLocker mu(Terminator_lock);
1483 
1484   while (watcher_thread() != NULL) {
1485     // This wait should make safepoint checks, wait without a timeout,
1486     // and wait as a suspend-equivalent condition.
1487     Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1488                           Mutex::_as_suspend_equivalent_flag);
1489   }
1490 }
1491 
1492 void WatcherThread::unpark() {
1493   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1494   PeriodicTask_lock->notify();
1495 }
1496 
1497 void WatcherThread::print_on(outputStream* st) const {
1498   st->print("\"%s\" ", name());
1499   Thread::print_on(st);
1500   st->cr();
1501 }
1502 
1503 // ======= JavaThread ========
1504 
1505 #if INCLUDE_JVMCI
1506 
1507 jlong* JavaThread::_jvmci_old_thread_counters;
1508 
1509 bool jvmci_counters_include(JavaThread* thread) {
1510   oop threadObj = thread->threadObj();
1511   return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1512 }
1513 
1514 void JavaThread::collect_counters(typeArrayOop array) {
1515   if (JVMCICounterSize > 0) {
1516     MutexLocker tl(Threads_lock);
1517     JavaThreadIteratorWithHandle jtiwh;
1518     for (int i = 0; i < array->length(); i++) {
1519       array->long_at_put(i, _jvmci_old_thread_counters[i]);
1520     }
1521     for (; JavaThread *tp = jtiwh.next(); ) {
1522       if (jvmci_counters_include(tp)) {
1523         for (int i = 0; i < array->length(); i++) {
1524           array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1525         }
1526       }
1527     }
1528   }
1529 }
1530 
1531 #endif // INCLUDE_JVMCI
1532 
1533 // A JavaThread is a normal Java thread
1534 
1535 void JavaThread::initialize() {
1536   // Initialize fields
1537 
1538   set_saved_exception_pc(NULL);
1539   set_threadObj(NULL);
1540   _anchor.clear();
1541   set_entry_point(NULL);
1542   set_jni_functions(jni_functions());
1543   set_callee_target(NULL);
1544   set_vm_result(NULL);
1545   set_vm_result_2(NULL);
1546   set_vframe_array_head(NULL);
1547   set_vframe_array_last(NULL);
1548   set_deferred_locals(NULL);
1549   set_deopt_mark(NULL);
1550   set_deopt_compiled_method(NULL);
1551   clear_must_deopt_id();
1552   set_monitor_chunks(NULL);
1553   set_next(NULL);
1554   _on_thread_list = false;
1555   set_thread_state(_thread_new);
1556   _terminated = _not_terminated;
1557   _privileged_stack_top = NULL;
1558   _array_for_gc = NULL;
1559   _suspend_equivalent = false;
1560   _in_deopt_handler = 0;
1561   _doing_unsafe_access = false;
1562   _stack_guard_state = stack_guard_unused;
1563 #if INCLUDE_JVMCI
1564   _pending_monitorenter = false;
1565   _pending_deoptimization = -1;
1566   _pending_failed_speculation = NULL;
1567   _pending_transfer_to_interpreter = false;
1568   _adjusting_comp_level = false;
1569   _jvmci._alternate_call_target = NULL;
1570   assert(_jvmci._implicit_exception_pc == NULL, "must be");
1571   if (JVMCICounterSize > 0) {
1572     _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1573     memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1574   } else {
1575     _jvmci_counters = NULL;
1576   }
1577 #endif // INCLUDE_JVMCI
1578   _reserved_stack_activation = NULL;  // stack base not known yet
1579   (void)const_cast<oop&>(_exception_oop = oop(NULL));
1580   _exception_pc  = 0;
1581   _exception_handler_pc = 0;
1582   _is_method_handle_return = 0;
1583   _jvmti_thread_state= NULL;
1584   _should_post_on_exceptions_flag = JNI_FALSE;
1585   _jvmti_get_loaded_classes_closure = NULL;
1586   _interp_only_mode    = 0;
1587   _special_runtime_exit_condition = _no_async_condition;
1588   _pending_async_exception = NULL;
1589   _thread_stat = NULL;
1590   _thread_stat = new ThreadStatistics();
1591   _blocked_on_compilation = false;
1592   _jni_active_critical = 0;
1593   _pending_jni_exception_check_fn = NULL;
1594   _do_not_unlock_if_synchronized = false;
1595   _cached_monitor_info = NULL;
1596   _parker = Parker::Allocate(this);
1597 
1598 #ifndef PRODUCT
1599   _jmp_ring_index = 0;
1600   for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1601     record_jump(NULL, NULL, NULL, 0);
1602   }
1603 #endif // PRODUCT
1604 
1605   // Setup safepoint state info for this thread
1606   ThreadSafepointState::create(this);
1607 
1608   debug_only(_java_call_counter = 0);
1609 
1610   // JVMTI PopFrame support
1611   _popframe_condition = popframe_inactive;
1612   _popframe_preserved_args = NULL;
1613   _popframe_preserved_args_size = 0;
1614   _frames_to_pop_failed_realloc = 0;
1615 
1616   if (SafepointMechanism::uses_thread_local_poll()) {
1617     SafepointMechanism::initialize_header(this);
1618   }
1619 
1620   pd_initialize();
1621 }
1622 
1623 #if INCLUDE_ALL_GCS
1624 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1625 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1626 char JavaThread::_gc_state_global = 0;
1627 #endif // INCLUDE_ALL_GCS
1628 
1629 JavaThread::JavaThread(bool is_attaching_via_jni) :
1630                        Thread()
1631 #if INCLUDE_ALL_GCS
1632                        , _satb_mark_queue(&_satb_mark_queue_set),
1633                        _dirty_card_queue(&_dirty_card_queue_set),
1634                        _gc_state(_gc_state_global)
1635 #endif // INCLUDE_ALL_GCS
1636 {
1637   initialize();
1638   if (is_attaching_via_jni) {
1639     _jni_attach_state = _attaching_via_jni;
1640   } else {
1641     _jni_attach_state = _not_attaching_via_jni;
1642   }
1643   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1644 }
1645 
1646 bool JavaThread::reguard_stack(address cur_sp) {
1647   if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1648       && _stack_guard_state != stack_guard_reserved_disabled) {
1649     return true; // Stack already guarded or guard pages not needed.
1650   }
1651 
1652   if (register_stack_overflow()) {
1653     // For those architectures which have separate register and
1654     // memory stacks, we must check the register stack to see if
1655     // it has overflowed.
1656     return false;
1657   }
1658 
1659   // Java code never executes within the yellow zone: the latter is only
1660   // there to provoke an exception during stack banging.  If java code
1661   // is executing there, either StackShadowPages should be larger, or
1662   // some exception code in c1, c2 or the interpreter isn't unwinding
1663   // when it should.
1664   guarantee(cur_sp > stack_reserved_zone_base(),
1665             "not enough space to reguard - increase StackShadowPages");
1666   if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1667     enable_stack_yellow_reserved_zone();
1668     if (reserved_stack_activation() != stack_base()) {
1669       set_reserved_stack_activation(stack_base());
1670     }
1671   } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1672     set_reserved_stack_activation(stack_base());
1673     enable_stack_reserved_zone();
1674   }
1675   return true;
1676 }
1677 
1678 bool JavaThread::reguard_stack(void) {
1679   return reguard_stack(os::current_stack_pointer());
1680 }
1681 
1682 
1683 void JavaThread::block_if_vm_exited() {
1684   if (_terminated == _vm_exited) {
1685     // _vm_exited is set at safepoint, and Threads_lock is never released
1686     // we will block here forever
1687     Threads_lock->lock_without_safepoint_check();
1688     ShouldNotReachHere();
1689   }
1690 }
1691 
1692 
1693 // Remove this ifdef when C1 is ported to the compiler interface.
1694 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1695 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1696 
1697 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1698                        Thread()
1699 #if INCLUDE_ALL_GCS
1700                        , _satb_mark_queue(&_satb_mark_queue_set),
1701                        _dirty_card_queue(&_dirty_card_queue_set),
1702                        _gc_state(_gc_state_global)
1703 #endif // INCLUDE_ALL_GCS
1704 {
1705   initialize();
1706   _jni_attach_state = _not_attaching_via_jni;
1707   set_entry_point(entry_point);
1708   // Create the native thread itself.
1709   // %note runtime_23
1710   os::ThreadType thr_type = os::java_thread;
1711   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1712                                                      os::java_thread;
1713   os::create_thread(this, thr_type, stack_sz);
1714   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1715   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1716   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1717   // the exception consists of creating the exception object & initializing it, initialization
1718   // will leave the VM via a JavaCall and then all locks must be unlocked).
1719   //
1720   // The thread is still suspended when we reach here. Thread must be explicit started
1721   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1722   // by calling Threads:add. The reason why this is not done here, is because the thread
1723   // object must be fully initialized (take a look at JVM_Start)
1724 }
1725 
1726 JavaThread::~JavaThread() {
1727 
1728   // JSR166 -- return the parker to the free list
1729   Parker::Release(_parker);
1730   _parker = NULL;
1731 
1732   // Free any remaining  previous UnrollBlock
1733   vframeArray* old_array = vframe_array_last();
1734 
1735   if (old_array != NULL) {
1736     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1737     old_array->set_unroll_block(NULL);
1738     delete old_info;
1739     delete old_array;
1740   }
1741 
1742   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1743   if (deferred != NULL) {
1744     // This can only happen if thread is destroyed before deoptimization occurs.
1745     assert(deferred->length() != 0, "empty array!");
1746     do {
1747       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1748       deferred->remove_at(0);
1749       // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1750       delete dlv;
1751     } while (deferred->length() != 0);
1752     delete deferred;
1753   }
1754 
1755   // All Java related clean up happens in exit
1756   ThreadSafepointState::destroy(this);
1757   if (_thread_stat != NULL) delete _thread_stat;
1758 
1759 #if INCLUDE_JVMCI
1760   if (JVMCICounterSize > 0) {
1761     if (jvmci_counters_include(this)) {
1762       for (int i = 0; i < JVMCICounterSize; i++) {
1763         _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1764       }
1765     }
1766     FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1767   }
1768 #endif // INCLUDE_JVMCI
1769 }
1770 
1771 
1772 // The first routine called by a new Java thread
1773 void JavaThread::run() {
1774   // initialize thread-local alloc buffer related fields
1775   this->initialize_tlab();
1776 
1777   // used to test validity of stack trace backs
1778   this->record_base_of_stack_pointer();
1779 
1780   // Record real stack base and size.
1781   this->record_stack_base_and_size();
1782 
1783   this->create_stack_guard_pages();
1784 
1785   this->cache_global_variables();
1786 
1787   // Thread is now sufficient initialized to be handled by the safepoint code as being
1788   // in the VM. Change thread state from _thread_new to _thread_in_vm
1789   ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1790 
1791   assert(JavaThread::current() == this, "sanity check");
1792   assert(!Thread::current()->owns_locks(), "sanity check");
1793 
1794   DTRACE_THREAD_PROBE(start, this);
1795 
1796   // This operation might block. We call that after all safepoint checks for a new thread has
1797   // been completed.
1798   this->set_active_handles(JNIHandleBlock::allocate_block());
1799 
1800   if (JvmtiExport::should_post_thread_life()) {
1801     JvmtiExport::post_thread_start(this);
1802   }
1803 
1804   EventThreadStart event;
1805   if (event.should_commit()) {
1806     event.set_thread(THREAD_TRACE_ID(this));
1807     event.commit();
1808   }
1809 
1810   // We call another function to do the rest so we are sure that the stack addresses used
1811   // from there will be lower than the stack base just computed
1812   thread_main_inner();
1813 
1814   // Note, thread is no longer valid at this point!
1815 }
1816 
1817 
1818 void JavaThread::thread_main_inner() {
1819   assert(JavaThread::current() == this, "sanity check");
1820   assert(this->threadObj() != NULL, "just checking");
1821 
1822   // Execute thread entry point unless this thread has a pending exception
1823   // or has been stopped before starting.
1824   // Note: Due to JVM_StopThread we can have pending exceptions already!
1825   if (!this->has_pending_exception() &&
1826       !java_lang_Thread::is_stillborn(this->threadObj())) {
1827     {
1828       ResourceMark rm(this);
1829       this->set_native_thread_name(this->get_thread_name());
1830     }
1831     HandleMark hm(this);
1832     this->entry_point()(this, this);
1833   }
1834 
1835   DTRACE_THREAD_PROBE(stop, this);
1836 
1837   this->exit(false);
1838   this->smr_delete();
1839 }
1840 
1841 
1842 static void ensure_join(JavaThread* thread) {
1843   // We do not need to grab the Threads_lock, since we are operating on ourself.
1844   Handle threadObj(thread, thread->threadObj());
1845   assert(threadObj.not_null(), "java thread object must exist");
1846   ObjectLocker lock(threadObj, thread);
1847   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1848   thread->clear_pending_exception();
1849   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1850   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1851   // Clear the native thread instance - this makes isAlive return false and allows the join()
1852   // to complete once we've done the notify_all below
1853   java_lang_Thread::set_thread(threadObj(), NULL);
1854   lock.notify_all(thread);
1855   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1856   thread->clear_pending_exception();
1857 }
1858 
1859 
1860 // For any new cleanup additions, please check to see if they need to be applied to
1861 // cleanup_failed_attach_current_thread as well.
1862 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1863   assert(this == JavaThread::current(), "thread consistency check");
1864 
1865   elapsedTimer _timer_exit_phase1;
1866   elapsedTimer _timer_exit_phase2;
1867   elapsedTimer _timer_exit_phase3;
1868   elapsedTimer _timer_exit_phase4;
1869 
1870   if (log_is_enabled(Debug, os, thread, timer)) {
1871     _timer_exit_phase1.start();
1872   }
1873 
1874   HandleMark hm(this);
1875   Handle uncaught_exception(this, this->pending_exception());
1876   this->clear_pending_exception();
1877   Handle threadObj(this, this->threadObj());
1878   assert(threadObj.not_null(), "Java thread object should be created");
1879 
1880   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1881   {
1882     EXCEPTION_MARK;
1883 
1884     CLEAR_PENDING_EXCEPTION;
1885   }
1886   if (!destroy_vm) {
1887     if (uncaught_exception.not_null()) {
1888       EXCEPTION_MARK;
1889       // Call method Thread.dispatchUncaughtException().
1890       Klass* thread_klass = SystemDictionary::Thread_klass();
1891       JavaValue result(T_VOID);
1892       JavaCalls::call_virtual(&result,
1893                               threadObj, thread_klass,
1894                               vmSymbols::dispatchUncaughtException_name(),
1895                               vmSymbols::throwable_void_signature(),
1896                               uncaught_exception,
1897                               THREAD);
1898       if (HAS_PENDING_EXCEPTION) {
1899         ResourceMark rm(this);
1900         jio_fprintf(defaultStream::error_stream(),
1901                     "\nException: %s thrown from the UncaughtExceptionHandler"
1902                     " in thread \"%s\"\n",
1903                     pending_exception()->klass()->external_name(),
1904                     get_thread_name());
1905         CLEAR_PENDING_EXCEPTION;
1906       }
1907     }
1908 
1909     // Called before the java thread exit since we want to read info
1910     // from java_lang_Thread object
1911     EventThreadEnd event;
1912     if (event.should_commit()) {
1913       event.set_thread(THREAD_TRACE_ID(this));
1914       event.commit();
1915     }
1916 
1917     // Call after last event on thread
1918     EVENT_THREAD_EXIT(this);
1919 
1920     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1921     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1922     // is deprecated anyhow.
1923     if (!is_Compiler_thread()) {
1924       int count = 3;
1925       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1926         EXCEPTION_MARK;
1927         JavaValue result(T_VOID);
1928         Klass* thread_klass = SystemDictionary::Thread_klass();
1929         JavaCalls::call_virtual(&result,
1930                                 threadObj, thread_klass,
1931                                 vmSymbols::exit_method_name(),
1932                                 vmSymbols::void_method_signature(),
1933                                 THREAD);
1934         CLEAR_PENDING_EXCEPTION;
1935       }
1936     }
1937     // notify JVMTI
1938     if (JvmtiExport::should_post_thread_life()) {
1939       JvmtiExport::post_thread_end(this);
1940     }
1941 
1942     // We have notified the agents that we are exiting, before we go on,
1943     // we must check for a pending external suspend request and honor it
1944     // in order to not surprise the thread that made the suspend request.
1945     while (true) {
1946       {
1947         MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1948         if (!is_external_suspend()) {
1949           set_terminated(_thread_exiting);
1950           ThreadService::current_thread_exiting(this);
1951           break;
1952         }
1953         // Implied else:
1954         // Things get a little tricky here. We have a pending external
1955         // suspend request, but we are holding the SR_lock so we
1956         // can't just self-suspend. So we temporarily drop the lock
1957         // and then self-suspend.
1958       }
1959 
1960       ThreadBlockInVM tbivm(this);
1961       java_suspend_self();
1962 
1963       // We're done with this suspend request, but we have to loop around
1964       // and check again. Eventually we will get SR_lock without a pending
1965       // external suspend request and will be able to mark ourselves as
1966       // exiting.
1967     }
1968     // no more external suspends are allowed at this point
1969   } else {
1970     // before_exit() has already posted JVMTI THREAD_END events
1971   }
1972 
1973   if (log_is_enabled(Debug, os, thread, timer)) {
1974     _timer_exit_phase1.stop();
1975     _timer_exit_phase2.start();
1976   }
1977   // Notify waiters on thread object. This has to be done after exit() is called
1978   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1979   // group should have the destroyed bit set before waiters are notified).
1980   ensure_join(this);
1981   assert(!this->has_pending_exception(), "ensure_join should have cleared");
1982 
1983   if (log_is_enabled(Debug, os, thread, timer)) {
1984     _timer_exit_phase2.stop();
1985     _timer_exit_phase3.start();
1986   }
1987   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1988   // held by this thread must be released. The spec does not distinguish
1989   // between JNI-acquired and regular Java monitors. We can only see
1990   // regular Java monitors here if monitor enter-exit matching is broken.
1991   //
1992   // Optionally release any monitors for regular JavaThread exits. This
1993   // is provided as a work around for any bugs in monitor enter-exit
1994   // matching. This can be expensive so it is not enabled by default.
1995   //
1996   // ensure_join() ignores IllegalThreadStateExceptions, and so does
1997   // ObjectSynchronizer::release_monitors_owned_by_thread().
1998   if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1999     // Sanity check even though JNI DetachCurrentThread() would have
2000     // returned JNI_ERR if there was a Java frame. JavaThread exit
2001     // should be done executing Java code by the time we get here.
2002     assert(!this->has_last_Java_frame(),
2003            "should not have a Java frame when detaching or exiting");
2004     ObjectSynchronizer::release_monitors_owned_by_thread(this);
2005     assert(!this->has_pending_exception(), "release_monitors should have cleared");
2006   }
2007 
2008   // These things needs to be done while we are still a Java Thread. Make sure that thread
2009   // is in a consistent state, in case GC happens
2010   assert(_privileged_stack_top == NULL, "must be NULL when we get here");
2011 
2012   if (active_handles() != NULL) {
2013     JNIHandleBlock* block = active_handles();
2014     set_active_handles(NULL);
2015     JNIHandleBlock::release_block(block);
2016   }
2017 
2018   if (free_handle_block() != NULL) {
2019     JNIHandleBlock* block = free_handle_block();
2020     set_free_handle_block(NULL);
2021     JNIHandleBlock::release_block(block);
2022   }
2023 
2024   // These have to be removed while this is still a valid thread.
2025   remove_stack_guard_pages();
2026 
2027   if (UseTLAB) {
2028     tlab().make_parsable(true);  // retire TLAB
2029   }
2030 
2031   if (JvmtiEnv::environments_might_exist()) {
2032     JvmtiExport::cleanup_thread(this);
2033   }
2034 
2035   // We must flush any deferred card marks before removing a thread from
2036   // the list of active threads.
2037   Universe::heap()->flush_deferred_store_barrier(this);
2038   assert(deferred_card_mark().is_empty(), "Should have been flushed");
2039 
2040 #if INCLUDE_ALL_GCS
2041   // We must flush the G1-related buffers before removing a thread
2042   // from the list of active threads. We must do this after any deferred
2043   // card marks have been flushed (above) so that any entries that are
2044   // added to the thread's dirty card queue as a result are not lost.
2045   if (UseG1GC || (UseShenandoahGC && (ShenandoahSATBBarrier || ShenandoahKeepAliveBarrier || ShenandoahStoreValEnqueueBarrier))) {
2046     flush_barrier_queues();
2047   }
2048   if (UseShenandoahGC && gclab() != NULL) {
2049     ShenandoahHeap::heap()->finalize_mutator_gclab(this);
2050   }
2051 #endif // INCLUDE_ALL_GCS
2052 
2053   log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2054     exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2055     os::current_thread_id());
2056 
2057   if (log_is_enabled(Debug, os, thread, timer)) {
2058     _timer_exit_phase3.stop();
2059     _timer_exit_phase4.start();
2060   }
2061   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2062   Threads::remove(this);
2063 
2064   if (log_is_enabled(Debug, os, thread, timer)) {
2065     _timer_exit_phase4.stop();
2066     ResourceMark rm(this);
2067     log_debug(os, thread, timer)("name='%s'"
2068                                  ", exit-phase1=" JLONG_FORMAT
2069                                  ", exit-phase2=" JLONG_FORMAT
2070                                  ", exit-phase3=" JLONG_FORMAT
2071                                  ", exit-phase4=" JLONG_FORMAT,
2072                                  get_thread_name(),
2073                                  _timer_exit_phase1.milliseconds(),
2074                                  _timer_exit_phase2.milliseconds(),
2075                                  _timer_exit_phase3.milliseconds(),
2076                                  _timer_exit_phase4.milliseconds());
2077   }
2078 }
2079 
2080 #if INCLUDE_ALL_GCS
2081 // Flush G1-related queues.
2082 void JavaThread::flush_barrier_queues() {
2083   satb_mark_queue().flush();
2084   dirty_card_queue().flush();
2085 }
2086 
2087 void JavaThread::initialize_queues() {
2088   assert(!SafepointSynchronize::is_at_safepoint(),
2089          "we should not be at a safepoint");
2090 
2091   SATBMarkQueue& satb_queue = satb_mark_queue();
2092   SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
2093   // The SATB queue should have been constructed with its active
2094   // field set to false.
2095   assert(!satb_queue.is_active(), "SATB queue should not be active");
2096   assert(satb_queue.is_empty(), "SATB queue should be empty");
2097   // If we are creating the thread during a marking cycle, we should
2098   // set the active field of the SATB queue to true.
2099   if (satb_queue_set.is_active()) {
2100     satb_queue.set_active(true);
2101   }
2102 
2103   DirtyCardQueue& dirty_queue = dirty_card_queue();
2104   // The dirty card queue should have been constructed with its
2105   // active field set to true.
2106   assert(dirty_queue.is_active(), "dirty card queue should be active");
2107 
2108   _gc_state = _gc_state_global;
2109 
2110   if (UseShenandoahGC) {
2111     ShenandoahHeap::heap()->initialize_gclab(this);
2112   }
2113 }
2114 #endif // INCLUDE_ALL_GCS
2115 
2116 void JavaThread::cleanup_failed_attach_current_thread() {
2117   if (active_handles() != NULL) {
2118     JNIHandleBlock* block = active_handles();
2119     set_active_handles(NULL);
2120     JNIHandleBlock::release_block(block);
2121   }
2122 
2123   if (free_handle_block() != NULL) {
2124     JNIHandleBlock* block = free_handle_block();
2125     set_free_handle_block(NULL);
2126     JNIHandleBlock::release_block(block);
2127   }
2128 
2129   // These have to be removed while this is still a valid thread.
2130   remove_stack_guard_pages();
2131 
2132   if (UseTLAB) {
2133     tlab().make_parsable(true);  // retire TLAB, if any
2134   }
2135 
2136 #if INCLUDE_ALL_GCS
2137   if (UseG1GC || (UseShenandoahGC && (ShenandoahSATBBarrier || ShenandoahKeepAliveBarrier || ShenandoahStoreValEnqueueBarrier))) {
2138     flush_barrier_queues();
2139   }
2140   if (UseShenandoahGC && gclab() != NULL) {
2141     gclab()->flush_and_retire_stats(ShenandoahHeap::heap()->mutator_gclab_stats());
2142   }
2143 #endif // INCLUDE_ALL_GCS
2144 
2145   Threads::remove(this);
2146   this->smr_delete();
2147 }
2148 
2149 
2150 
2151 
2152 JavaThread* JavaThread::active() {
2153   Thread* thread = Thread::current();
2154   if (thread->is_Java_thread()) {
2155     return (JavaThread*) thread;
2156   } else {
2157     assert(thread->is_VM_thread(), "this must be a vm thread");
2158     VM_Operation* op = ((VMThread*) thread)->vm_operation();
2159     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2160     assert(ret->is_Java_thread(), "must be a Java thread");
2161     return ret;
2162   }
2163 }
2164 
2165 bool JavaThread::is_lock_owned(address adr) const {
2166   if (Thread::is_lock_owned(adr)) return true;
2167 
2168   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2169     if (chunk->contains(adr)) return true;
2170   }
2171 
2172   return false;
2173 }
2174 
2175 
2176 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2177   chunk->set_next(monitor_chunks());
2178   set_monitor_chunks(chunk);
2179 }
2180 
2181 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2182   guarantee(monitor_chunks() != NULL, "must be non empty");
2183   if (monitor_chunks() == chunk) {
2184     set_monitor_chunks(chunk->next());
2185   } else {
2186     MonitorChunk* prev = monitor_chunks();
2187     while (prev->next() != chunk) prev = prev->next();
2188     prev->set_next(chunk->next());
2189   }
2190 }
2191 
2192 // JVM support.
2193 
2194 // Note: this function shouldn't block if it's called in
2195 // _thread_in_native_trans state (such as from
2196 // check_special_condition_for_native_trans()).
2197 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2198 
2199   if (has_last_Java_frame() && has_async_condition()) {
2200     // If we are at a polling page safepoint (not a poll return)
2201     // then we must defer async exception because live registers
2202     // will be clobbered by the exception path. Poll return is
2203     // ok because the call we a returning from already collides
2204     // with exception handling registers and so there is no issue.
2205     // (The exception handling path kills call result registers but
2206     //  this is ok since the exception kills the result anyway).
2207 
2208     if (is_at_poll_safepoint()) {
2209       // if the code we are returning to has deoptimized we must defer
2210       // the exception otherwise live registers get clobbered on the
2211       // exception path before deoptimization is able to retrieve them.
2212       //
2213       RegisterMap map(this, false);
2214       frame caller_fr = last_frame().sender(&map);
2215       assert(caller_fr.is_compiled_frame(), "what?");
2216       if (caller_fr.is_deoptimized_frame()) {
2217         log_info(exceptions)("deferred async exception at compiled safepoint");
2218         return;
2219       }
2220     }
2221   }
2222 
2223   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2224   if (condition == _no_async_condition) {
2225     // Conditions have changed since has_special_runtime_exit_condition()
2226     // was called:
2227     // - if we were here only because of an external suspend request,
2228     //   then that was taken care of above (or cancelled) so we are done
2229     // - if we were here because of another async request, then it has
2230     //   been cleared between the has_special_runtime_exit_condition()
2231     //   and now so again we are done
2232     return;
2233   }
2234 
2235   // Check for pending async. exception
2236   if (_pending_async_exception != NULL) {
2237     // Only overwrite an already pending exception, if it is not a threadDeath.
2238     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2239 
2240       // We cannot call Exceptions::_throw(...) here because we cannot block
2241       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2242 
2243       LogTarget(Info, exceptions) lt;
2244       if (lt.is_enabled()) {
2245         ResourceMark rm;
2246         LogStream ls(lt);
2247         ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2248           if (has_last_Java_frame()) {
2249             frame f = last_frame();
2250            ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2251           }
2252         ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2253       }
2254       _pending_async_exception = NULL;
2255       clear_has_async_exception();
2256     }
2257   }
2258 
2259   if (check_unsafe_error &&
2260       condition == _async_unsafe_access_error && !has_pending_exception()) {
2261     condition = _no_async_condition;  // done
2262     switch (thread_state()) {
2263     case _thread_in_vm: {
2264       JavaThread* THREAD = this;
2265       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2266     }
2267     case _thread_in_native: {
2268       ThreadInVMfromNative tiv(this);
2269       JavaThread* THREAD = this;
2270       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2271     }
2272     case _thread_in_Java: {
2273       ThreadInVMfromJava tiv(this);
2274       JavaThread* THREAD = this;
2275       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2276     }
2277     default:
2278       ShouldNotReachHere();
2279     }
2280   }
2281 
2282   assert(condition == _no_async_condition || has_pending_exception() ||
2283          (!check_unsafe_error && condition == _async_unsafe_access_error),
2284          "must have handled the async condition, if no exception");
2285 }
2286 
2287 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2288   //
2289   // Check for pending external suspend. Internal suspend requests do
2290   // not use handle_special_runtime_exit_condition().
2291   // If JNIEnv proxies are allowed, don't self-suspend if the target
2292   // thread is not the current thread. In older versions of jdbx, jdbx
2293   // threads could call into the VM with another thread's JNIEnv so we
2294   // can be here operating on behalf of a suspended thread (4432884).
2295   bool do_self_suspend = is_external_suspend_with_lock();
2296   if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2297     //
2298     // Because thread is external suspended the safepoint code will count
2299     // thread as at a safepoint. This can be odd because we can be here
2300     // as _thread_in_Java which would normally transition to _thread_blocked
2301     // at a safepoint. We would like to mark the thread as _thread_blocked
2302     // before calling java_suspend_self like all other callers of it but
2303     // we must then observe proper safepoint protocol. (We can't leave
2304     // _thread_blocked with a safepoint in progress). However we can be
2305     // here as _thread_in_native_trans so we can't use a normal transition
2306     // constructor/destructor pair because they assert on that type of
2307     // transition. We could do something like:
2308     //
2309     // JavaThreadState state = thread_state();
2310     // set_thread_state(_thread_in_vm);
2311     // {
2312     //   ThreadBlockInVM tbivm(this);
2313     //   java_suspend_self()
2314     // }
2315     // set_thread_state(_thread_in_vm_trans);
2316     // if (safepoint) block;
2317     // set_thread_state(state);
2318     //
2319     // but that is pretty messy. Instead we just go with the way the
2320     // code has worked before and note that this is the only path to
2321     // java_suspend_self that doesn't put the thread in _thread_blocked
2322     // mode.
2323 
2324     frame_anchor()->make_walkable(this);
2325     java_suspend_self();
2326 
2327     // We might be here for reasons in addition to the self-suspend request
2328     // so check for other async requests.
2329   }
2330 
2331   if (check_asyncs) {
2332     check_and_handle_async_exceptions();
2333   }
2334 #if INCLUDE_TRACE
2335   if (is_trace_suspend()) {
2336     TRACE_SUSPEND_THREAD(this);
2337   }
2338 #endif
2339 }
2340 
2341 void JavaThread::send_thread_stop(oop java_throwable)  {
2342   assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2343   assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2344   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2345 
2346   // Do not throw asynchronous exceptions against the compiler thread
2347   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2348   if (!can_call_java()) return;
2349 
2350   {
2351     // Actually throw the Throwable against the target Thread - however
2352     // only if there is no thread death exception installed already.
2353     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2354       // If the topmost frame is a runtime stub, then we are calling into
2355       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2356       // must deoptimize the caller before continuing, as the compiled  exception handler table
2357       // may not be valid
2358       if (has_last_Java_frame()) {
2359         frame f = last_frame();
2360         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2361           // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2362           RegisterMap reg_map(this, UseBiasedLocking);
2363           frame compiled_frame = f.sender(&reg_map);
2364           if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2365             Deoptimization::deoptimize(this, compiled_frame, &reg_map);
2366           }
2367         }
2368       }
2369 
2370       // Set async. pending exception in thread.
2371       set_pending_async_exception(java_throwable);
2372 
2373       if (log_is_enabled(Info, exceptions)) {
2374          ResourceMark rm;
2375         log_info(exceptions)("Pending Async. exception installed of type: %s",
2376                              InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2377       }
2378       // for AbortVMOnException flag
2379       Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2380     }
2381   }
2382 
2383 
2384   // Interrupt thread so it will wake up from a potential wait()
2385   Thread::interrupt(this);
2386 }
2387 
2388 // External suspension mechanism.
2389 //
2390 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2391 // to any VM_locks and it is at a transition
2392 // Self-suspension will happen on the transition out of the vm.
2393 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2394 //
2395 // Guarantees on return:
2396 //   + Target thread will not execute any new bytecode (that's why we need to
2397 //     force a safepoint)
2398 //   + Target thread will not enter any new monitors
2399 //
2400 void JavaThread::java_suspend() {
2401   ThreadsListHandle tlh;
2402   if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2403     return;
2404   }
2405 
2406   { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2407     if (!is_external_suspend()) {
2408       // a racing resume has cancelled us; bail out now
2409       return;
2410     }
2411 
2412     // suspend is done
2413     uint32_t debug_bits = 0;
2414     // Warning: is_ext_suspend_completed() may temporarily drop the
2415     // SR_lock to allow the thread to reach a stable thread state if
2416     // it is currently in a transient thread state.
2417     if (is_ext_suspend_completed(false /* !called_by_wait */,
2418                                  SuspendRetryDelay, &debug_bits)) {
2419       return;
2420     }
2421   }
2422 
2423   VM_ThreadSuspend vm_suspend;
2424   VMThread::execute(&vm_suspend);
2425 }
2426 
2427 // Part II of external suspension.
2428 // A JavaThread self suspends when it detects a pending external suspend
2429 // request. This is usually on transitions. It is also done in places
2430 // where continuing to the next transition would surprise the caller,
2431 // e.g., monitor entry.
2432 //
2433 // Returns the number of times that the thread self-suspended.
2434 //
2435 // Note: DO NOT call java_suspend_self() when you just want to block current
2436 //       thread. java_suspend_self() is the second stage of cooperative
2437 //       suspension for external suspend requests and should only be used
2438 //       to complete an external suspend request.
2439 //
2440 int JavaThread::java_suspend_self() {
2441   int ret = 0;
2442 
2443   // we are in the process of exiting so don't suspend
2444   if (is_exiting()) {
2445     clear_external_suspend();
2446     return ret;
2447   }
2448 
2449   assert(_anchor.walkable() ||
2450          (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2451          "must have walkable stack");
2452 
2453   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2454 
2455   assert(!this->is_ext_suspended(),
2456          "a thread trying to self-suspend should not already be suspended");
2457 
2458   if (this->is_suspend_equivalent()) {
2459     // If we are self-suspending as a result of the lifting of a
2460     // suspend equivalent condition, then the suspend_equivalent
2461     // flag is not cleared until we set the ext_suspended flag so
2462     // that wait_for_ext_suspend_completion() returns consistent
2463     // results.
2464     this->clear_suspend_equivalent();
2465   }
2466 
2467   // A racing resume may have cancelled us before we grabbed SR_lock
2468   // above. Or another external suspend request could be waiting for us
2469   // by the time we return from SR_lock()->wait(). The thread
2470   // that requested the suspension may already be trying to walk our
2471   // stack and if we return now, we can change the stack out from under
2472   // it. This would be a "bad thing (TM)" and cause the stack walker
2473   // to crash. We stay self-suspended until there are no more pending
2474   // external suspend requests.
2475   while (is_external_suspend()) {
2476     ret++;
2477     this->set_ext_suspended();
2478 
2479     // _ext_suspended flag is cleared by java_resume()
2480     while (is_ext_suspended()) {
2481       this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2482     }
2483   }
2484 
2485   return ret;
2486 }
2487 
2488 #ifdef ASSERT
2489 // verify the JavaThread has not yet been published in the Threads::list, and
2490 // hence doesn't need protection from concurrent access at this stage
2491 void JavaThread::verify_not_published() {
2492   ThreadsListHandle tlh;
2493   assert(!tlh.includes(this), "JavaThread shouldn't have been published yet!");
2494 }
2495 #endif
2496 
2497 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2498 // progress or when _suspend_flags is non-zero.
2499 // Current thread needs to self-suspend if there is a suspend request and/or
2500 // block if a safepoint is in progress.
2501 // Async exception ISN'T checked.
2502 // Note only the ThreadInVMfromNative transition can call this function
2503 // directly and when thread state is _thread_in_native_trans
2504 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2505   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2506 
2507   JavaThread *curJT = JavaThread::current();
2508   bool do_self_suspend = thread->is_external_suspend();
2509 
2510   assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2511 
2512   // If JNIEnv proxies are allowed, don't self-suspend if the target
2513   // thread is not the current thread. In older versions of jdbx, jdbx
2514   // threads could call into the VM with another thread's JNIEnv so we
2515   // can be here operating on behalf of a suspended thread (4432884).
2516   if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2517     JavaThreadState state = thread->thread_state();
2518 
2519     // We mark this thread_blocked state as a suspend-equivalent so
2520     // that a caller to is_ext_suspend_completed() won't be confused.
2521     // The suspend-equivalent state is cleared by java_suspend_self().
2522     thread->set_suspend_equivalent();
2523 
2524     // If the safepoint code sees the _thread_in_native_trans state, it will
2525     // wait until the thread changes to other thread state. There is no
2526     // guarantee on how soon we can obtain the SR_lock and complete the
2527     // self-suspend request. It would be a bad idea to let safepoint wait for
2528     // too long. Temporarily change the state to _thread_blocked to
2529     // let the VM thread know that this thread is ready for GC. The problem
2530     // of changing thread state is that safepoint could happen just after
2531     // java_suspend_self() returns after being resumed, and VM thread will
2532     // see the _thread_blocked state. We must check for safepoint
2533     // after restoring the state and make sure we won't leave while a safepoint
2534     // is in progress.
2535     thread->set_thread_state(_thread_blocked);
2536     thread->java_suspend_self();
2537     thread->set_thread_state(state);
2538 
2539     InterfaceSupport::serialize_thread_state_with_handler(thread);
2540   }
2541 
2542   SafepointMechanism::block_if_requested(curJT);
2543 
2544   if (thread->is_deopt_suspend()) {
2545     thread->clear_deopt_suspend();
2546     RegisterMap map(thread, false);
2547     frame f = thread->last_frame();
2548     while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2549       f = f.sender(&map);
2550     }
2551     if (f.id() == thread->must_deopt_id()) {
2552       thread->clear_must_deopt_id();
2553       f.deoptimize(thread);
2554     } else {
2555       fatal("missed deoptimization!");
2556     }
2557   }
2558 #if INCLUDE_TRACE
2559   if (thread->is_trace_suspend()) {
2560     TRACE_SUSPEND_THREAD(thread);
2561   }
2562 #endif
2563 }
2564 
2565 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2566 // progress or when _suspend_flags is non-zero.
2567 // Current thread needs to self-suspend if there is a suspend request and/or
2568 // block if a safepoint is in progress.
2569 // Also check for pending async exception (not including unsafe access error).
2570 // Note only the native==>VM/Java barriers can call this function and when
2571 // thread state is _thread_in_native_trans.
2572 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2573   check_safepoint_and_suspend_for_native_trans(thread);
2574 
2575   if (thread->has_async_exception()) {
2576     // We are in _thread_in_native_trans state, don't handle unsafe
2577     // access error since that may block.
2578     thread->check_and_handle_async_exceptions(false);
2579   }
2580 }
2581 
2582 // This is a variant of the normal
2583 // check_special_condition_for_native_trans with slightly different
2584 // semantics for use by critical native wrappers.  It does all the
2585 // normal checks but also performs the transition back into
2586 // thread_in_Java state.  This is required so that critical natives
2587 // can potentially block and perform a GC if they are the last thread
2588 // exiting the GCLocker.
2589 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2590   check_special_condition_for_native_trans(thread);
2591 
2592   // Finish the transition
2593   thread->set_thread_state(_thread_in_Java);
2594 
2595   if (thread->do_critical_native_unlock()) {
2596     ThreadInVMfromJavaNoAsyncException tiv(thread);
2597     GCLocker::unlock_critical(thread);
2598     thread->clear_critical_native_unlock();
2599   }
2600 }
2601 
2602 // We need to guarantee the Threads_lock here, since resumes are not
2603 // allowed during safepoint synchronization
2604 // Can only resume from an external suspension
2605 void JavaThread::java_resume() {
2606   assert_locked_or_safepoint(Threads_lock);
2607 
2608   // Sanity check: thread is gone, has started exiting or the thread
2609   // was not externally suspended.
2610   ThreadsListHandle tlh;
2611   if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2612     return;
2613   }
2614 
2615   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2616 
2617   clear_external_suspend();
2618 
2619   if (is_ext_suspended()) {
2620     clear_ext_suspended();
2621     SR_lock()->notify_all();
2622   }
2623 }
2624 
2625 size_t JavaThread::_stack_red_zone_size = 0;
2626 size_t JavaThread::_stack_yellow_zone_size = 0;
2627 size_t JavaThread::_stack_reserved_zone_size = 0;
2628 size_t JavaThread::_stack_shadow_zone_size = 0;
2629 
2630 void JavaThread::create_stack_guard_pages() {
2631   if (!os::uses_stack_guard_pages() ||
2632       _stack_guard_state != stack_guard_unused ||
2633       (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2634       log_info(os, thread)("Stack guard page creation for thread "
2635                            UINTX_FORMAT " disabled", os::current_thread_id());
2636     return;
2637   }
2638   address low_addr = stack_end();
2639   size_t len = stack_guard_zone_size();
2640 
2641   assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2642   assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2643 
2644   int must_commit = os::must_commit_stack_guard_pages();
2645   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2646 
2647   if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2648     log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2649     return;
2650   }
2651 
2652   if (os::guard_memory((char *) low_addr, len)) {
2653     _stack_guard_state = stack_guard_enabled;
2654   } else {
2655     log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2656       PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2657     if (os::uncommit_memory((char *) low_addr, len)) {
2658       log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2659     }
2660     return;
2661   }
2662 
2663   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2664     PTR_FORMAT "-" PTR_FORMAT ".",
2665     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2666 }
2667 
2668 void JavaThread::remove_stack_guard_pages() {
2669   assert(Thread::current() == this, "from different thread");
2670   if (_stack_guard_state == stack_guard_unused) return;
2671   address low_addr = stack_end();
2672   size_t len = stack_guard_zone_size();
2673 
2674   if (os::must_commit_stack_guard_pages()) {
2675     if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2676       _stack_guard_state = stack_guard_unused;
2677     } else {
2678       log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2679         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2680       return;
2681     }
2682   } else {
2683     if (_stack_guard_state == stack_guard_unused) return;
2684     if (os::unguard_memory((char *) low_addr, len)) {
2685       _stack_guard_state = stack_guard_unused;
2686     } else {
2687       log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2688         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2689       return;
2690     }
2691   }
2692 
2693   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2694     PTR_FORMAT "-" PTR_FORMAT ".",
2695     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2696 }
2697 
2698 void JavaThread::enable_stack_reserved_zone() {
2699   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2700   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2701 
2702   // The base notation is from the stack's point of view, growing downward.
2703   // We need to adjust it to work correctly with guard_memory()
2704   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2705 
2706   guarantee(base < stack_base(),"Error calculating stack reserved zone");
2707   guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2708 
2709   if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2710     _stack_guard_state = stack_guard_enabled;
2711   } else {
2712     warning("Attempt to guard stack reserved zone failed.");
2713   }
2714   enable_register_stack_guard();
2715 }
2716 
2717 void JavaThread::disable_stack_reserved_zone() {
2718   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2719   assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2720 
2721   // Simply return if called for a thread that does not use guard pages.
2722   if (_stack_guard_state == stack_guard_unused) return;
2723 
2724   // The base notation is from the stack's point of view, growing downward.
2725   // We need to adjust it to work correctly with guard_memory()
2726   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2727 
2728   if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2729     _stack_guard_state = stack_guard_reserved_disabled;
2730   } else {
2731     warning("Attempt to unguard stack reserved zone failed.");
2732   }
2733   disable_register_stack_guard();
2734 }
2735 
2736 void JavaThread::enable_stack_yellow_reserved_zone() {
2737   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2738   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2739 
2740   // The base notation is from the stacks point of view, growing downward.
2741   // We need to adjust it to work correctly with guard_memory()
2742   address base = stack_red_zone_base();
2743 
2744   guarantee(base < stack_base(), "Error calculating stack yellow zone");
2745   guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2746 
2747   if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2748     _stack_guard_state = stack_guard_enabled;
2749   } else {
2750     warning("Attempt to guard stack yellow zone failed.");
2751   }
2752   enable_register_stack_guard();
2753 }
2754 
2755 void JavaThread::disable_stack_yellow_reserved_zone() {
2756   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2757   assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2758 
2759   // Simply return if called for a thread that does not use guard pages.
2760   if (_stack_guard_state == stack_guard_unused) return;
2761 
2762   // The base notation is from the stacks point of view, growing downward.
2763   // We need to adjust it to work correctly with guard_memory()
2764   address base = stack_red_zone_base();
2765 
2766   if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2767     _stack_guard_state = stack_guard_yellow_reserved_disabled;
2768   } else {
2769     warning("Attempt to unguard stack yellow zone failed.");
2770   }
2771   disable_register_stack_guard();
2772 }
2773 
2774 void JavaThread::enable_stack_red_zone() {
2775   // The base notation is from the stacks point of view, growing downward.
2776   // We need to adjust it to work correctly with guard_memory()
2777   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2778   address base = stack_red_zone_base() - stack_red_zone_size();
2779 
2780   guarantee(base < stack_base(), "Error calculating stack red zone");
2781   guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2782 
2783   if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2784     warning("Attempt to guard stack red zone failed.");
2785   }
2786 }
2787 
2788 void JavaThread::disable_stack_red_zone() {
2789   // The base notation is from the stacks point of view, growing downward.
2790   // We need to adjust it to work correctly with guard_memory()
2791   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2792   address base = stack_red_zone_base() - stack_red_zone_size();
2793   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2794     warning("Attempt to unguard stack red zone failed.");
2795   }
2796 }
2797 
2798 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2799   // ignore is there is no stack
2800   if (!has_last_Java_frame()) return;
2801   // traverse the stack frames. Starts from top frame.
2802   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2803     frame* fr = fst.current();
2804     f(fr, fst.register_map());
2805   }
2806 }
2807 
2808 
2809 #ifndef PRODUCT
2810 // Deoptimization
2811 // Function for testing deoptimization
2812 void JavaThread::deoptimize() {
2813   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2814   StackFrameStream fst(this, UseBiasedLocking);
2815   bool deopt = false;           // Dump stack only if a deopt actually happens.
2816   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2817   // Iterate over all frames in the thread and deoptimize
2818   for (; !fst.is_done(); fst.next()) {
2819     if (fst.current()->can_be_deoptimized()) {
2820 
2821       if (only_at) {
2822         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
2823         // consists of comma or carriage return separated numbers so
2824         // search for the current bci in that string.
2825         address pc = fst.current()->pc();
2826         nmethod* nm =  (nmethod*) fst.current()->cb();
2827         ScopeDesc* sd = nm->scope_desc_at(pc);
2828         char buffer[8];
2829         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2830         size_t len = strlen(buffer);
2831         const char * found = strstr(DeoptimizeOnlyAt, buffer);
2832         while (found != NULL) {
2833           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2834               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2835             // Check that the bci found is bracketed by terminators.
2836             break;
2837           }
2838           found = strstr(found + 1, buffer);
2839         }
2840         if (!found) {
2841           continue;
2842         }
2843       }
2844 
2845       if (DebugDeoptimization && !deopt) {
2846         deopt = true; // One-time only print before deopt
2847         tty->print_cr("[BEFORE Deoptimization]");
2848         trace_frames();
2849         trace_stack();
2850       }
2851       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2852     }
2853   }
2854 
2855   if (DebugDeoptimization && deopt) {
2856     tty->print_cr("[AFTER Deoptimization]");
2857     trace_frames();
2858   }
2859 }
2860 
2861 
2862 // Make zombies
2863 void JavaThread::make_zombies() {
2864   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2865     if (fst.current()->can_be_deoptimized()) {
2866       // it is a Java nmethod
2867       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2868       nm->make_not_entrant();
2869     }
2870   }
2871 }
2872 #endif // PRODUCT
2873 
2874 
2875 void JavaThread::deoptimized_wrt_marked_nmethods() {
2876   if (!has_last_Java_frame()) return;
2877   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2878   StackFrameStream fst(this, UseBiasedLocking);
2879   for (; !fst.is_done(); fst.next()) {
2880     if (fst.current()->should_be_deoptimized()) {
2881       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2882     }
2883   }
2884 }
2885 
2886 
2887 // If the caller is a NamedThread, then remember, in the current scope,
2888 // the given JavaThread in its _processed_thread field.
2889 class RememberProcessedThread: public StackObj {
2890   NamedThread* _cur_thr;
2891  public:
2892   RememberProcessedThread(JavaThread* jthr) {
2893     Thread* thread = Thread::current();
2894     if (thread->is_Named_thread()) {
2895       _cur_thr = (NamedThread *)thread;
2896       _cur_thr->set_processed_thread(jthr);
2897     } else {
2898       _cur_thr = NULL;
2899     }
2900   }
2901 
2902   ~RememberProcessedThread() {
2903     if (_cur_thr) {
2904       _cur_thr->set_processed_thread(NULL);
2905     }
2906   }
2907 };
2908 
2909 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2910   // Verify that the deferred card marks have been flushed.
2911   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2912 
2913   // Traverse the GCHandles
2914   Thread::oops_do(f, cf);
2915 
2916   JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2917 
2918   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2919          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2920 
2921   if (has_last_Java_frame()) {
2922     // Record JavaThread to GC thread
2923     RememberProcessedThread rpt(this);
2924 
2925     // Traverse the privileged stack
2926     if (_privileged_stack_top != NULL) {
2927       _privileged_stack_top->oops_do(f);
2928     }
2929 
2930     // traverse the registered growable array
2931     if (_array_for_gc != NULL) {
2932       for (int index = 0; index < _array_for_gc->length(); index++) {
2933         f->do_oop(_array_for_gc->adr_at(index));
2934       }
2935     }
2936 
2937     // Traverse the monitor chunks
2938     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2939       chunk->oops_do(f);
2940     }
2941 
2942     // Traverse the execution stack
2943     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2944       fst.current()->oops_do(f, cf, fst.register_map());
2945     }
2946   }
2947 
2948   // callee_target is never live across a gc point so NULL it here should
2949   // it still contain a methdOop.
2950 
2951   set_callee_target(NULL);
2952 
2953   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2954   // If we have deferred set_locals there might be oops waiting to be
2955   // written
2956   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2957   if (list != NULL) {
2958     for (int i = 0; i < list->length(); i++) {
2959       list->at(i)->oops_do(f);
2960     }
2961   }
2962 
2963   // Traverse instance variables at the end since the GC may be moving things
2964   // around using this function
2965   f->do_oop((oop*) &_threadObj);
2966   f->do_oop((oop*) &_vm_result);
2967   f->do_oop((oop*) &_exception_oop);
2968   f->do_oop((oop*) &_pending_async_exception);
2969 
2970   if (jvmti_thread_state() != NULL) {
2971     jvmti_thread_state()->oops_do(f);
2972   }
2973 }
2974 
2975 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2976   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2977          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2978 
2979   if (has_last_Java_frame()) {
2980     // Traverse the execution stack
2981     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2982       fst.current()->nmethods_do(cf);
2983     }
2984   }
2985 }
2986 
2987 void JavaThread::metadata_do(void f(Metadata*)) {
2988   if (has_last_Java_frame()) {
2989     // Traverse the execution stack to call f() on the methods in the stack
2990     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2991       fst.current()->metadata_do(f);
2992     }
2993   } else if (is_Compiler_thread()) {
2994     // need to walk ciMetadata in current compile tasks to keep alive.
2995     CompilerThread* ct = (CompilerThread*)this;
2996     if (ct->env() != NULL) {
2997       ct->env()->metadata_do(f);
2998     }
2999     CompileTask* task = ct->task();
3000     if (task != NULL) {
3001       task->metadata_do(f);
3002     }
3003   }
3004 }
3005 
3006 // Printing
3007 const char* _get_thread_state_name(JavaThreadState _thread_state) {
3008   switch (_thread_state) {
3009   case _thread_uninitialized:     return "_thread_uninitialized";
3010   case _thread_new:               return "_thread_new";
3011   case _thread_new_trans:         return "_thread_new_trans";
3012   case _thread_in_native:         return "_thread_in_native";
3013   case _thread_in_native_trans:   return "_thread_in_native_trans";
3014   case _thread_in_vm:             return "_thread_in_vm";
3015   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
3016   case _thread_in_Java:           return "_thread_in_Java";
3017   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
3018   case _thread_blocked:           return "_thread_blocked";
3019   case _thread_blocked_trans:     return "_thread_blocked_trans";
3020   default:                        return "unknown thread state";
3021   }
3022 }
3023 
3024 #ifndef PRODUCT
3025 void JavaThread::print_thread_state_on(outputStream *st) const {
3026   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
3027 };
3028 void JavaThread::print_thread_state() const {
3029   print_thread_state_on(tty);
3030 }
3031 #endif // PRODUCT
3032 
3033 // Called by Threads::print() for VM_PrintThreads operation
3034 void JavaThread::print_on(outputStream *st) const {
3035   st->print_raw("\"");
3036   st->print_raw(get_thread_name());
3037   st->print_raw("\" ");
3038   oop thread_oop = threadObj();
3039   if (thread_oop != NULL) {
3040     st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
3041     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
3042     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
3043   }
3044   Thread::print_on(st);
3045   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
3046   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
3047   if (thread_oop != NULL) {
3048     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
3049   }
3050 #ifndef PRODUCT
3051   print_thread_state_on(st);
3052   _safepoint_state->print_on(st);
3053 #endif // PRODUCT
3054   if (is_Compiler_thread()) {
3055     CompileTask *task = ((CompilerThread*)this)->task();
3056     if (task != NULL) {
3057       st->print("   Compiling: ");
3058       task->print(st, NULL, true, false);
3059     } else {
3060       st->print("   No compile task");
3061     }
3062     st->cr();
3063   }
3064 }
3065 
3066 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
3067   st->print("%s", get_thread_name_string(buf, buflen));
3068 }
3069 
3070 // Called by fatal error handler. The difference between this and
3071 // JavaThread::print() is that we can't grab lock or allocate memory.
3072 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
3073   st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
3074   oop thread_obj = threadObj();
3075   if (thread_obj != NULL) {
3076     if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
3077   }
3078   st->print(" [");
3079   st->print("%s", _get_thread_state_name(_thread_state));
3080   if (osthread()) {
3081     st->print(", id=%d", osthread()->thread_id());
3082   }
3083   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
3084             p2i(stack_end()), p2i(stack_base()));
3085   st->print("]");
3086 
3087   if (_threads_hazard_ptr != NULL) {
3088     st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
3089   }
3090   if (_nested_threads_hazard_ptr != NULL) {
3091     print_nested_threads_hazard_ptrs_on(st);
3092   }
3093   return;
3094 }
3095 
3096 // Verification
3097 
3098 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3099 
3100 void JavaThread::verify() {
3101   // Verify oops in the thread.
3102   oops_do(&VerifyOopClosure::verify_oop, NULL);
3103 
3104   // Verify the stack frames.
3105   frames_do(frame_verify);
3106 }
3107 
3108 // CR 6300358 (sub-CR 2137150)
3109 // Most callers of this method assume that it can't return NULL but a
3110 // thread may not have a name whilst it is in the process of attaching to
3111 // the VM - see CR 6412693, and there are places where a JavaThread can be
3112 // seen prior to having it's threadObj set (eg JNI attaching threads and
3113 // if vm exit occurs during initialization). These cases can all be accounted
3114 // for such that this method never returns NULL.
3115 const char* JavaThread::get_thread_name() const {
3116 #ifdef ASSERT
3117   // early safepoints can hit while current thread does not yet have TLS
3118   if (!SafepointSynchronize::is_at_safepoint()) {
3119     Thread *cur = Thread::current();
3120     if (!(cur->is_Java_thread() && cur == this)) {
3121       // Current JavaThreads are allowed to get their own name without
3122       // the Threads_lock.
3123       assert_locked_or_safepoint(Threads_lock);
3124     }
3125   }
3126 #endif // ASSERT
3127   return get_thread_name_string();
3128 }
3129 
3130 // Returns a non-NULL representation of this thread's name, or a suitable
3131 // descriptive string if there is no set name
3132 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3133   const char* name_str;
3134   oop thread_obj = threadObj();
3135   if (thread_obj != NULL) {
3136     oop name = java_lang_Thread::name(thread_obj);
3137     if (name != NULL) {
3138       if (buf == NULL) {
3139         name_str = java_lang_String::as_utf8_string(name);
3140       } else {
3141         name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3142       }
3143     } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3144       name_str = "<no-name - thread is attaching>";
3145     } else {
3146       name_str = Thread::name();
3147     }
3148   } else {
3149     name_str = Thread::name();
3150   }
3151   assert(name_str != NULL, "unexpected NULL thread name");
3152   return name_str;
3153 }
3154 
3155 
3156 const char* JavaThread::get_threadgroup_name() const {
3157   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3158   oop thread_obj = threadObj();
3159   if (thread_obj != NULL) {
3160     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3161     if (thread_group != NULL) {
3162       // ThreadGroup.name can be null
3163       return java_lang_ThreadGroup::name(thread_group);
3164     }
3165   }
3166   return NULL;
3167 }
3168 
3169 const char* JavaThread::get_parent_name() const {
3170   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3171   oop thread_obj = threadObj();
3172   if (thread_obj != NULL) {
3173     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3174     if (thread_group != NULL) {
3175       oop parent = java_lang_ThreadGroup::parent(thread_group);
3176       if (parent != NULL) {
3177         // ThreadGroup.name can be null
3178         return java_lang_ThreadGroup::name(parent);
3179       }
3180     }
3181   }
3182   return NULL;
3183 }
3184 
3185 ThreadPriority JavaThread::java_priority() const {
3186   oop thr_oop = threadObj();
3187   if (thr_oop == NULL) return NormPriority; // Bootstrapping
3188   ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3189   assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3190   return priority;
3191 }
3192 
3193 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3194 
3195   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3196   // Link Java Thread object <-> C++ Thread
3197 
3198   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3199   // and put it into a new Handle.  The Handle "thread_oop" can then
3200   // be used to pass the C++ thread object to other methods.
3201 
3202   // Set the Java level thread object (jthread) field of the
3203   // new thread (a JavaThread *) to C++ thread object using the
3204   // "thread_oop" handle.
3205 
3206   // Set the thread field (a JavaThread *) of the
3207   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3208 
3209   Handle thread_oop(Thread::current(),
3210                     JNIHandles::resolve_non_null(jni_thread));
3211   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3212          "must be initialized");
3213   set_threadObj(thread_oop());
3214   java_lang_Thread::set_thread(thread_oop(), this);
3215 
3216   if (prio == NoPriority) {
3217     prio = java_lang_Thread::priority(thread_oop());
3218     assert(prio != NoPriority, "A valid priority should be present");
3219   }
3220 
3221   // Push the Java priority down to the native thread; needs Threads_lock
3222   Thread::set_priority(this, prio);
3223 
3224   prepare_ext();
3225 
3226   // Add the new thread to the Threads list and set it in motion.
3227   // We must have threads lock in order to call Threads::add.
3228   // It is crucial that we do not block before the thread is
3229   // added to the Threads list for if a GC happens, then the java_thread oop
3230   // will not be visited by GC.
3231   Threads::add(this);
3232 }
3233 
3234 oop JavaThread::current_park_blocker() {
3235   // Support for JSR-166 locks
3236   oop thread_oop = threadObj();
3237   if (thread_oop != NULL &&
3238       JDK_Version::current().supports_thread_park_blocker()) {
3239     return java_lang_Thread::park_blocker(thread_oop);
3240   }
3241   return NULL;
3242 }
3243 
3244 
3245 void JavaThread::print_stack_on(outputStream* st) {
3246   if (!has_last_Java_frame()) return;
3247   ResourceMark rm;
3248   HandleMark   hm;
3249 
3250   RegisterMap reg_map(this);
3251   vframe* start_vf = last_java_vframe(&reg_map);
3252   int count = 0;
3253   for (vframe* f = start_vf; f; f = f->sender()) {
3254     if (f->is_java_frame()) {
3255       javaVFrame* jvf = javaVFrame::cast(f);
3256       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3257 
3258       // Print out lock information
3259       if (JavaMonitorsInStackTrace) {
3260         jvf->print_lock_info_on(st, count);
3261       }
3262     } else {
3263       // Ignore non-Java frames
3264     }
3265 
3266     // Bail-out case for too deep stacks
3267     count++;
3268     if (MaxJavaStackTraceDepth == count) return;
3269   }
3270 }
3271 
3272 
3273 // JVMTI PopFrame support
3274 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3275   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3276   if (in_bytes(size_in_bytes) != 0) {
3277     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3278     _popframe_preserved_args_size = in_bytes(size_in_bytes);
3279     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3280   }
3281 }
3282 
3283 void* JavaThread::popframe_preserved_args() {
3284   return _popframe_preserved_args;
3285 }
3286 
3287 ByteSize JavaThread::popframe_preserved_args_size() {
3288   return in_ByteSize(_popframe_preserved_args_size);
3289 }
3290 
3291 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3292   int sz = in_bytes(popframe_preserved_args_size());
3293   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3294   return in_WordSize(sz / wordSize);
3295 }
3296 
3297 void JavaThread::popframe_free_preserved_args() {
3298   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3299   FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3300   _popframe_preserved_args = NULL;
3301   _popframe_preserved_args_size = 0;
3302 }
3303 
3304 #ifndef PRODUCT
3305 
3306 void JavaThread::trace_frames() {
3307   tty->print_cr("[Describe stack]");
3308   int frame_no = 1;
3309   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3310     tty->print("  %d. ", frame_no++);
3311     fst.current()->print_value_on(tty, this);
3312     tty->cr();
3313   }
3314 }
3315 
3316 class PrintAndVerifyOopClosure: public OopClosure {
3317  protected:
3318   template <class T> inline void do_oop_work(T* p) {
3319     oop obj = oopDesc::load_decode_heap_oop(p);
3320     if (obj == NULL) return;
3321     tty->print(INTPTR_FORMAT ": ", p2i(p));
3322     if (oopDesc::is_oop_or_null(obj)) {
3323       if (obj->is_objArray()) {
3324         tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3325       } else {
3326         obj->print();
3327       }
3328     } else {
3329       tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3330     }
3331     tty->cr();
3332   }
3333  public:
3334   virtual void do_oop(oop* p) { do_oop_work(p); }
3335   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
3336 };
3337 
3338 
3339 static void oops_print(frame* f, const RegisterMap *map) {
3340   PrintAndVerifyOopClosure print;
3341   f->print_value();
3342   f->oops_do(&print, NULL, (RegisterMap*)map);
3343 }
3344 
3345 // Print our all the locations that contain oops and whether they are
3346 // valid or not.  This useful when trying to find the oldest frame
3347 // where an oop has gone bad since the frame walk is from youngest to
3348 // oldest.
3349 void JavaThread::trace_oops() {
3350   tty->print_cr("[Trace oops]");
3351   frames_do(oops_print);
3352 }
3353 
3354 
3355 #ifdef ASSERT
3356 // Print or validate the layout of stack frames
3357 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3358   ResourceMark rm;
3359   PRESERVE_EXCEPTION_MARK;
3360   FrameValues values;
3361   int frame_no = 0;
3362   for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3363     fst.current()->describe(values, ++frame_no);
3364     if (depth == frame_no) break;
3365   }
3366   if (validate_only) {
3367     values.validate();
3368   } else {
3369     tty->print_cr("[Describe stack layout]");
3370     values.print(this);
3371   }
3372 }
3373 #endif
3374 
3375 void JavaThread::trace_stack_from(vframe* start_vf) {
3376   ResourceMark rm;
3377   int vframe_no = 1;
3378   for (vframe* f = start_vf; f; f = f->sender()) {
3379     if (f->is_java_frame()) {
3380       javaVFrame::cast(f)->print_activation(vframe_no++);
3381     } else {
3382       f->print();
3383     }
3384     if (vframe_no > StackPrintLimit) {
3385       tty->print_cr("...<more frames>...");
3386       return;
3387     }
3388   }
3389 }
3390 
3391 
3392 void JavaThread::trace_stack() {
3393   if (!has_last_Java_frame()) return;
3394   ResourceMark rm;
3395   HandleMark   hm;
3396   RegisterMap reg_map(this);
3397   trace_stack_from(last_java_vframe(&reg_map));
3398 }
3399 
3400 
3401 #endif // PRODUCT
3402 
3403 
3404 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3405   assert(reg_map != NULL, "a map must be given");
3406   frame f = last_frame();
3407   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3408     if (vf->is_java_frame()) return javaVFrame::cast(vf);
3409   }
3410   return NULL;
3411 }
3412 
3413 
3414 Klass* JavaThread::security_get_caller_class(int depth) {
3415   vframeStream vfst(this);
3416   vfst.security_get_caller_frame(depth);
3417   if (!vfst.at_end()) {
3418     return vfst.method()->method_holder();
3419   }
3420   return NULL;
3421 }
3422 
3423 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3424   assert(thread->is_Compiler_thread(), "must be compiler thread");
3425   CompileBroker::compiler_thread_loop();
3426 }
3427 
3428 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3429   NMethodSweeper::sweeper_loop();
3430 }
3431 
3432 // Create a CompilerThread
3433 CompilerThread::CompilerThread(CompileQueue* queue,
3434                                CompilerCounters* counters)
3435                                : JavaThread(&compiler_thread_entry) {
3436   _env   = NULL;
3437   _log   = NULL;
3438   _task  = NULL;
3439   _queue = queue;
3440   _counters = counters;
3441   _buffer_blob = NULL;
3442   _compiler = NULL;
3443 
3444   // Compiler uses resource area for compilation, let's bias it to mtCompiler
3445   resource_area()->bias_to(mtCompiler);
3446 
3447 #ifndef PRODUCT
3448   _ideal_graph_printer = NULL;
3449 #endif
3450 }
3451 
3452 bool CompilerThread::can_call_java() const {
3453   return _compiler != NULL && _compiler->is_jvmci();
3454 }
3455 
3456 // Create sweeper thread
3457 CodeCacheSweeperThread::CodeCacheSweeperThread()
3458 : JavaThread(&sweeper_thread_entry) {
3459   _scanned_compiled_method = NULL;
3460 }
3461 
3462 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3463   JavaThread::oops_do(f, cf);
3464   if (_scanned_compiled_method != NULL && cf != NULL) {
3465     // Safepoints can occur when the sweeper is scanning an nmethod so
3466     // process it here to make sure it isn't unloaded in the middle of
3467     // a scan.
3468     cf->do_code_blob(_scanned_compiled_method);
3469   }
3470 }
3471 
3472 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3473   JavaThread::nmethods_do(cf);
3474   if (_scanned_compiled_method != NULL && cf != NULL) {
3475     // Safepoints can occur when the sweeper is scanning an nmethod so
3476     // process it here to make sure it isn't unloaded in the middle of
3477     // a scan.
3478     cf->do_code_blob(_scanned_compiled_method);
3479   }
3480 }
3481 
3482 
3483 // ======= Threads ========
3484 
3485 // The Threads class links together all active threads, and provides
3486 // operations over all threads. It is protected by the Threads_lock,
3487 // which is also used in other global contexts like safepointing.
3488 // ThreadsListHandles are used to safely perform operations on one
3489 // or more threads without the risk of the thread exiting during the
3490 // operation.
3491 //
3492 // Note: The Threads_lock is currently more widely used than we
3493 // would like. We are actively migrating Threads_lock uses to other
3494 // mechanisms in order to reduce Threads_lock contention.
3495 
3496 JavaThread* Threads::_thread_list = NULL;
3497 int         Threads::_number_of_threads = 0;
3498 int         Threads::_number_of_non_daemon_threads = 0;
3499 int         Threads::_return_code = 0;
3500 int         Threads::_thread_claim_parity = 0;
3501 size_t      JavaThread::_stack_size_at_create = 0;
3502 
3503 #ifdef ASSERT
3504 bool        Threads::_vm_complete = false;
3505 #endif
3506 
3507 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3508   Prefetch::read((void*)addr, prefetch_interval);
3509   return *addr;
3510 }
3511 
3512 // Possibly the ugliest for loop the world has seen. C++ does not allow
3513 // multiple types in the declaration section of the for loop. In this case
3514 // we are only dealing with pointers and hence can cast them. It looks ugly
3515 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3516 #define DO_JAVA_THREADS(LIST, X)                                                                                          \
3517     for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes,                           \
3518              *MACRO_list = (JavaThread*)(LIST),                                                                           \
3519              **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(),  \
3520              **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(),                                     \
3521              *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval);                 \
3522          MACRO_current_p != MACRO_end;                                                                                    \
3523          MACRO_current_p++,                                                                                               \
3524              X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3525 
3526 // All JavaThreads
3527 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3528 
3529 void Threads::java_threads_do(ThreadClosure* tc) {
3530   assert_locked_or_safepoint(Threads_lock);
3531   ALL_JAVA_THREADS(p) {
3532     tc->do_thread(p);
3533   }
3534 }
3535 
3536 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3537 void Threads::threads_do(ThreadClosure* tc) {
3538   assert_locked_or_safepoint(Threads_lock);
3539   // ALL_JAVA_THREADS iterates through all JavaThreads
3540   ALL_JAVA_THREADS(p) {
3541     tc->do_thread(p);
3542   }
3543   // Someday we could have a table or list of all non-JavaThreads.
3544   // For now, just manually iterate through them.
3545   tc->do_thread(VMThread::vm_thread());
3546   Universe::heap()->gc_threads_do(tc);
3547   WatcherThread *wt = WatcherThread::watcher_thread();
3548   // Strictly speaking, the following NULL check isn't sufficient to make sure
3549   // the data for WatcherThread is still valid upon being examined. However,
3550   // considering that WatchThread terminates when the VM is on the way to
3551   // exit at safepoint, the chance of the above is extremely small. The right
3552   // way to prevent termination of WatcherThread would be to acquire
3553   // Terminator_lock, but we can't do that without violating the lock rank
3554   // checking in some cases.
3555   if (wt != NULL) {
3556     tc->do_thread(wt);
3557   }
3558 
3559   // If CompilerThreads ever become non-JavaThreads, add them here
3560 }
3561 
3562 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3563   int cp = Threads::thread_claim_parity();
3564   ALL_JAVA_THREADS(p) {
3565     if (p->claim_oops_do(is_par, cp)) {
3566       tc->do_thread(p);
3567     }
3568   }
3569   VMThread* vmt = VMThread::vm_thread();
3570   if (vmt->claim_oops_do(is_par, cp)) {
3571     tc->do_thread(vmt);
3572   }
3573 }
3574 
3575 // The system initialization in the library has three phases.
3576 //
3577 // Phase 1: java.lang.System class initialization
3578 //     java.lang.System is a primordial class loaded and initialized
3579 //     by the VM early during startup.  java.lang.System.<clinit>
3580 //     only does registerNatives and keeps the rest of the class
3581 //     initialization work later until thread initialization completes.
3582 //
3583 //     System.initPhase1 initializes the system properties, the static
3584 //     fields in, out, and err. Set up java signal handlers, OS-specific
3585 //     system settings, and thread group of the main thread.
3586 static void call_initPhase1(TRAPS) {
3587   Klass* klass =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3588   JavaValue result(T_VOID);
3589   JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3590                                          vmSymbols::void_method_signature(), CHECK);
3591 }
3592 
3593 // Phase 2. Module system initialization
3594 //     This will initialize the module system.  Only java.base classes
3595 //     can be loaded until phase 2 completes.
3596 //
3597 //     Call System.initPhase2 after the compiler initialization and jsr292
3598 //     classes get initialized because module initialization runs a lot of java
3599 //     code, that for performance reasons, should be compiled.  Also, this will
3600 //     enable the startup code to use lambda and other language features in this
3601 //     phase and onward.
3602 //
3603 //     After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3604 static void call_initPhase2(TRAPS) {
3605   TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3606 
3607   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3608 
3609   JavaValue result(T_INT);
3610   JavaCallArguments args;
3611   args.push_int(DisplayVMOutputToStderr);
3612   args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3613   JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3614                                          vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3615   if (result.get_jint() != JNI_OK) {
3616     vm_exit_during_initialization(); // no message or exception
3617   }
3618 
3619   universe_post_module_init();
3620 }
3621 
3622 // Phase 3. final setup - set security manager, system class loader and TCCL
3623 //
3624 //     This will instantiate and set the security manager, set the system class
3625 //     loader as well as the thread context class loader.  The security manager
3626 //     and system class loader may be a custom class loaded from -Xbootclasspath/a,
3627 //     other modules or the application's classpath.
3628 static void call_initPhase3(TRAPS) {
3629   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3630   JavaValue result(T_VOID);
3631   JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3632                                          vmSymbols::void_method_signature(), CHECK);
3633 }
3634 
3635 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3636   TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3637 
3638   if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3639     create_vm_init_libraries();
3640   }
3641 
3642   initialize_class(vmSymbols::java_lang_String(), CHECK);
3643 
3644   // Inject CompactStrings value after the static initializers for String ran.
3645   java_lang_String::set_compact_strings(CompactStrings);
3646 
3647   // Initialize java_lang.System (needed before creating the thread)
3648   initialize_class(vmSymbols::java_lang_System(), CHECK);
3649   // The VM creates & returns objects of this class. Make sure it's initialized.
3650   initialize_class(vmSymbols::java_lang_Class(), CHECK);
3651   initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3652   Handle thread_group = create_initial_thread_group(CHECK);
3653   Universe::set_main_thread_group(thread_group());
3654   initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3655   oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3656   main_thread->set_threadObj(thread_object);
3657   // Set thread status to running since main thread has
3658   // been started and running.
3659   java_lang_Thread::set_thread_status(thread_object,
3660                                       java_lang_Thread::RUNNABLE);
3661 
3662   // The VM creates objects of this class.
3663   initialize_class(vmSymbols::java_lang_Module(), CHECK);
3664 
3665   // The VM preresolves methods to these classes. Make sure that they get initialized
3666   initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3667   initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3668 
3669   // Phase 1 of the system initialization in the library, java.lang.System class initialization
3670   call_initPhase1(CHECK);
3671 
3672   // get the Java runtime name after java.lang.System is initialized
3673   JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3674   JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3675 
3676   // an instance of OutOfMemory exception has been allocated earlier
3677   initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3678   initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3679   initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3680   initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3681   initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3682   initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3683   initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3684   initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3685 }
3686 
3687 void Threads::initialize_jsr292_core_classes(TRAPS) {
3688   TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3689 
3690   initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3691   initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3692   initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3693   initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3694 }
3695 
3696 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3697   extern void JDK_Version_init();
3698 
3699   // Preinitialize version info.
3700   VM_Version::early_initialize();
3701 
3702   // Check version
3703   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3704 
3705   // Initialize library-based TLS
3706   ThreadLocalStorage::init();
3707 
3708   // Initialize the output stream module
3709   ostream_init();
3710 
3711   // Process java launcher properties.
3712   Arguments::process_sun_java_launcher_properties(args);
3713 
3714   // Initialize the os module
3715   os::init();
3716 
3717   // Record VM creation timing statistics
3718   TraceVmCreationTime create_vm_timer;
3719   create_vm_timer.start();
3720 
3721   // Initialize system properties.
3722   Arguments::init_system_properties();
3723 
3724   // So that JDK version can be used as a discriminator when parsing arguments
3725   JDK_Version_init();
3726 
3727   // Update/Initialize System properties after JDK version number is known
3728   Arguments::init_version_specific_system_properties();
3729 
3730   // Make sure to initialize log configuration *before* parsing arguments
3731   LogConfiguration::initialize(create_vm_timer.begin_time());
3732 
3733   // Parse arguments
3734   // Note: this internally calls os::init_container_support()
3735   jint parse_result = Arguments::parse(args);
3736   if (parse_result != JNI_OK) return parse_result;
3737 
3738   os::init_before_ergo();
3739 
3740   jint ergo_result = Arguments::apply_ergo();
3741   if (ergo_result != JNI_OK) return ergo_result;
3742 
3743   // Final check of all ranges after ergonomics which may change values.
3744   if (!CommandLineFlagRangeList::check_ranges()) {
3745     return JNI_EINVAL;
3746   }
3747 
3748   // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3749   bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3750   if (!constraint_result) {
3751     return JNI_EINVAL;
3752   }
3753 
3754   CommandLineFlagWriteableList::mark_startup();
3755 
3756   if (PauseAtStartup) {
3757     os::pause();
3758   }
3759 
3760   HOTSPOT_VM_INIT_BEGIN();
3761 
3762   // Timing (must come after argument parsing)
3763   TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3764 
3765   // Initialize the os module after parsing the args
3766   jint os_init_2_result = os::init_2();
3767   if (os_init_2_result != JNI_OK) return os_init_2_result;
3768 
3769   SafepointMechanism::initialize();
3770 
3771   jint adjust_after_os_result = Arguments::adjust_after_os();
3772   if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3773 
3774   // Initialize output stream logging
3775   ostream_init_log();
3776 
3777   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3778   // Must be before create_vm_init_agents()
3779   if (Arguments::init_libraries_at_startup()) {
3780     convert_vm_init_libraries_to_agents();
3781   }
3782 
3783   // Launch -agentlib/-agentpath and converted -Xrun agents
3784   if (Arguments::init_agents_at_startup()) {
3785     create_vm_init_agents();
3786   }
3787 
3788   // Initialize Threads state
3789   _thread_list = NULL;
3790   _number_of_threads = 0;
3791   _number_of_non_daemon_threads = 0;
3792 
3793   // Initialize global data structures and create system classes in heap
3794   vm_init_globals();
3795 
3796 #if INCLUDE_JVMCI
3797   if (JVMCICounterSize > 0) {
3798     JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3799     memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3800   } else {
3801     JavaThread::_jvmci_old_thread_counters = NULL;
3802   }
3803 #endif // INCLUDE_JVMCI
3804 
3805   // Attach the main thread to this os thread
3806   JavaThread* main_thread = new JavaThread();
3807   main_thread->set_thread_state(_thread_in_vm);
3808   main_thread->initialize_thread_current();
3809   // must do this before set_active_handles
3810   main_thread->record_stack_base_and_size();
3811   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3812 
3813   if (!main_thread->set_as_starting_thread()) {
3814     vm_shutdown_during_initialization(
3815                                       "Failed necessary internal allocation. Out of swap space");
3816     main_thread->smr_delete();
3817     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3818     return JNI_ENOMEM;
3819   }
3820 
3821   // Enable guard page *after* os::create_main_thread(), otherwise it would
3822   // crash Linux VM, see notes in os_linux.cpp.
3823   main_thread->create_stack_guard_pages();
3824 
3825   // Initialize Java-Level synchronization subsystem
3826   ObjectMonitor::Initialize();
3827 
3828   // Initialize global modules
3829   jint status = init_globals();
3830   if (status != JNI_OK) {
3831     main_thread->smr_delete();
3832     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3833     return status;
3834   }
3835 
3836   if (TRACE_INITIALIZE() != JNI_OK) {
3837     vm_exit_during_initialization("Failed to initialize tracing backend");
3838   }
3839 
3840   // Should be done after the heap is fully created
3841   main_thread->cache_global_variables();
3842 
3843   HandleMark hm;
3844 
3845   { MutexLocker mu(Threads_lock);
3846     Threads::add(main_thread);
3847   }
3848 
3849   // Any JVMTI raw monitors entered in onload will transition into
3850   // real raw monitor. VM is setup enough here for raw monitor enter.
3851   JvmtiExport::transition_pending_onload_raw_monitors();
3852 
3853   // Create the VMThread
3854   { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3855 
3856   VMThread::create();
3857     Thread* vmthread = VMThread::vm_thread();
3858 
3859     if (!os::create_thread(vmthread, os::vm_thread)) {
3860       vm_exit_during_initialization("Cannot create VM thread. "
3861                                     "Out of system resources.");
3862     }
3863 
3864     // Wait for the VM thread to become ready, and VMThread::run to initialize
3865     // Monitors can have spurious returns, must always check another state flag
3866     {
3867       MutexLocker ml(Notify_lock);
3868       os::start_thread(vmthread);
3869       while (vmthread->active_handles() == NULL) {
3870         Notify_lock->wait();
3871       }
3872     }
3873   }
3874 
3875   assert(Universe::is_fully_initialized(), "not initialized");
3876   if (VerifyDuringStartup) {
3877     // Make sure we're starting with a clean slate.
3878     VM_Verify verify_op;
3879     VMThread::execute(&verify_op);
3880   }
3881 
3882   Thread* THREAD = Thread::current();
3883 
3884   // Always call even when there are not JVMTI environments yet, since environments
3885   // may be attached late and JVMTI must track phases of VM execution
3886   JvmtiExport::enter_early_start_phase();
3887 
3888   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3889   JvmtiExport::post_early_vm_start();
3890 
3891   initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3892 
3893   // We need this for ClassDataSharing - the initial vm.info property is set
3894   // with the default value of CDS "sharing" which may be reset through
3895   // command line options.
3896   reset_vm_info_property(CHECK_JNI_ERR);
3897 
3898   quicken_jni_functions();
3899 
3900   // No more stub generation allowed after that point.
3901   StubCodeDesc::freeze();
3902 
3903   // Set flag that basic initialization has completed. Used by exceptions and various
3904   // debug stuff, that does not work until all basic classes have been initialized.
3905   set_init_completed();
3906 
3907   LogConfiguration::post_initialize();
3908   Metaspace::post_initialize();
3909 
3910   HOTSPOT_VM_INIT_END();
3911 
3912   // record VM initialization completion time
3913 #if INCLUDE_MANAGEMENT
3914   Management::record_vm_init_completed();
3915 #endif // INCLUDE_MANAGEMENT
3916 
3917   // Signal Dispatcher needs to be started before VMInit event is posted
3918   os::signal_init(CHECK_JNI_ERR);
3919 
3920   // Start Attach Listener if +StartAttachListener or it can't be started lazily
3921   if (!DisableAttachMechanism) {
3922     AttachListener::vm_start();
3923     if (StartAttachListener || AttachListener::init_at_startup()) {
3924       AttachListener::init();
3925     }
3926   }
3927 
3928   // Launch -Xrun agents
3929   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3930   // back-end can launch with -Xdebug -Xrunjdwp.
3931   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3932     create_vm_init_libraries();
3933   }
3934 
3935   if (CleanChunkPoolAsync) {
3936     Chunk::start_chunk_pool_cleaner_task();
3937   }
3938 
3939   // initialize compiler(s)
3940 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3941   CompileBroker::compilation_init(CHECK_JNI_ERR);
3942 #endif
3943 
3944   // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3945   // It is done after compilers are initialized, because otherwise compilations of
3946   // signature polymorphic MH intrinsics can be missed
3947   // (see SystemDictionary::find_method_handle_intrinsic).
3948   initialize_jsr292_core_classes(CHECK_JNI_ERR);
3949 
3950   // This will initialize the module system.  Only java.base classes can be
3951   // loaded until phase 2 completes
3952   call_initPhase2(CHECK_JNI_ERR);
3953 
3954   // Always call even when there are not JVMTI environments yet, since environments
3955   // may be attached late and JVMTI must track phases of VM execution
3956   JvmtiExport::enter_start_phase();
3957 
3958   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3959   JvmtiExport::post_vm_start();
3960 
3961   // Final system initialization including security manager and system class loader
3962   call_initPhase3(CHECK_JNI_ERR);
3963 
3964   // cache the system and platform class loaders
3965   SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3966 
3967 #if INCLUDE_JVMCI
3968   if (EnableJVMCI) {
3969     // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled.
3970     // The JVMCI Java initialization code will read this flag and
3971     // do the printing if it's set.
3972     bool init = JVMCIPrintProperties;
3973 
3974     if (!init) {
3975       // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3976       // compilations via JVMCI will not actually block until JVMCI is initialized.
3977       init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3978     }
3979 
3980     if (init) {
3981       JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3982     }
3983   }
3984 #endif
3985 
3986   // Always call even when there are not JVMTI environments yet, since environments
3987   // may be attached late and JVMTI must track phases of VM execution
3988   JvmtiExport::enter_live_phase();
3989 
3990   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3991   JvmtiExport::post_vm_initialized();
3992 
3993   if (TRACE_START() != JNI_OK) {
3994     vm_exit_during_initialization("Failed to start tracing backend.");
3995   }
3996 
3997 #if INCLUDE_MANAGEMENT
3998   Management::initialize(THREAD);
3999 
4000   if (HAS_PENDING_EXCEPTION) {
4001     // management agent fails to start possibly due to
4002     // configuration problem and is responsible for printing
4003     // stack trace if appropriate. Simply exit VM.
4004     vm_exit(1);
4005   }
4006 #endif // INCLUDE_MANAGEMENT
4007 
4008   if (MemProfiling)                   MemProfiler::engage();
4009   StatSampler::engage();
4010   if (CheckJNICalls)                  JniPeriodicChecker::engage();
4011 
4012   BiasedLocking::init();
4013 
4014 #if INCLUDE_RTM_OPT
4015   RTMLockingCounters::init();
4016 #endif
4017 
4018   if (JDK_Version::current().post_vm_init_hook_enabled()) {
4019     call_postVMInitHook(THREAD);
4020     // The Java side of PostVMInitHook.run must deal with all
4021     // exceptions and provide means of diagnosis.
4022     if (HAS_PENDING_EXCEPTION) {
4023       CLEAR_PENDING_EXCEPTION;
4024     }
4025   }
4026 
4027   {
4028     MutexLocker ml(PeriodicTask_lock);
4029     // Make sure the WatcherThread can be started by WatcherThread::start()
4030     // or by dynamic enrollment.
4031     WatcherThread::make_startable();
4032     // Start up the WatcherThread if there are any periodic tasks
4033     // NOTE:  All PeriodicTasks should be registered by now. If they
4034     //   aren't, late joiners might appear to start slowly (we might
4035     //   take a while to process their first tick).
4036     if (PeriodicTask::num_tasks() > 0) {
4037       WatcherThread::start();
4038     }
4039   }
4040 
4041   create_vm_timer.end();
4042 #ifdef ASSERT
4043   _vm_complete = true;
4044 #endif
4045 
4046   if (DumpSharedSpaces) {
4047     MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
4048     ShouldNotReachHere();
4049   }
4050 
4051   return JNI_OK;
4052 }
4053 
4054 // type for the Agent_OnLoad and JVM_OnLoad entry points
4055 extern "C" {
4056   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
4057 }
4058 // Find a command line agent library and return its entry point for
4059 //         -agentlib:  -agentpath:   -Xrun
4060 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
4061 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
4062                                     const char *on_load_symbols[],
4063                                     size_t num_symbol_entries) {
4064   OnLoadEntry_t on_load_entry = NULL;
4065   void *library = NULL;
4066 
4067   if (!agent->valid()) {
4068     char buffer[JVM_MAXPATHLEN];
4069     char ebuf[1024] = "";
4070     const char *name = agent->name();
4071     const char *msg = "Could not find agent library ";
4072 
4073     // First check to see if agent is statically linked into executable
4074     if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
4075       library = agent->os_lib();
4076     } else if (agent->is_absolute_path()) {
4077       library = os::dll_load(name, ebuf, sizeof ebuf);
4078       if (library == NULL) {
4079         const char *sub_msg = " in absolute path, with error: ";
4080         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4081         char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4082         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4083         // If we can't find the agent, exit.
4084         vm_exit_during_initialization(buf, NULL);
4085         FREE_C_HEAP_ARRAY(char, buf);
4086       }
4087     } else {
4088       // Try to load the agent from the standard dll directory
4089       if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4090                              name)) {
4091         library = os::dll_load(buffer, ebuf, sizeof ebuf);
4092       }
4093       if (library == NULL) { // Try the library path directory.
4094         if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4095           library = os::dll_load(buffer, ebuf, sizeof ebuf);
4096         }
4097         if (library == NULL) {
4098           const char *sub_msg = " on the library path, with error: ";
4099           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4100           char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4101           jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4102           // If we can't find the agent, exit.
4103           vm_exit_during_initialization(buf, NULL);
4104           FREE_C_HEAP_ARRAY(char, buf);
4105         }
4106       }
4107     }
4108     agent->set_os_lib(library);
4109     agent->set_valid();
4110   }
4111 
4112   // Find the OnLoad function.
4113   on_load_entry =
4114     CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4115                                                           false,
4116                                                           on_load_symbols,
4117                                                           num_symbol_entries));
4118   return on_load_entry;
4119 }
4120 
4121 // Find the JVM_OnLoad entry point
4122 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4123   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4124   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4125 }
4126 
4127 // Find the Agent_OnLoad entry point
4128 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4129   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4130   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4131 }
4132 
4133 // For backwards compatibility with -Xrun
4134 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4135 // treated like -agentpath:
4136 // Must be called before agent libraries are created
4137 void Threads::convert_vm_init_libraries_to_agents() {
4138   AgentLibrary* agent;
4139   AgentLibrary* next;
4140 
4141   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4142     next = agent->next();  // cache the next agent now as this agent may get moved off this list
4143     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4144 
4145     // If there is an JVM_OnLoad function it will get called later,
4146     // otherwise see if there is an Agent_OnLoad
4147     if (on_load_entry == NULL) {
4148       on_load_entry = lookup_agent_on_load(agent);
4149       if (on_load_entry != NULL) {
4150         // switch it to the agent list -- so that Agent_OnLoad will be called,
4151         // JVM_OnLoad won't be attempted and Agent_OnUnload will
4152         Arguments::convert_library_to_agent(agent);
4153       } else {
4154         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4155       }
4156     }
4157   }
4158 }
4159 
4160 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
4161 // Invokes Agent_OnLoad
4162 // Called very early -- before JavaThreads exist
4163 void Threads::create_vm_init_agents() {
4164   extern struct JavaVM_ main_vm;
4165   AgentLibrary* agent;
4166 
4167   JvmtiExport::enter_onload_phase();
4168 
4169   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4170     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
4171 
4172     if (on_load_entry != NULL) {
4173       // Invoke the Agent_OnLoad function
4174       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4175       if (err != JNI_OK) {
4176         vm_exit_during_initialization("agent library failed to init", agent->name());
4177       }
4178     } else {
4179       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4180     }
4181   }
4182   JvmtiExport::enter_primordial_phase();
4183 }
4184 
4185 extern "C" {
4186   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4187 }
4188 
4189 void Threads::shutdown_vm_agents() {
4190   // Send any Agent_OnUnload notifications
4191   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4192   size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4193   extern struct JavaVM_ main_vm;
4194   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4195 
4196     // Find the Agent_OnUnload function.
4197     Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4198                                                    os::find_agent_function(agent,
4199                                                    false,
4200                                                    on_unload_symbols,
4201                                                    num_symbol_entries));
4202 
4203     // Invoke the Agent_OnUnload function
4204     if (unload_entry != NULL) {
4205       JavaThread* thread = JavaThread::current();
4206       ThreadToNativeFromVM ttn(thread);
4207       HandleMark hm(thread);
4208       (*unload_entry)(&main_vm);
4209     }
4210   }
4211 }
4212 
4213 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4214 // Invokes JVM_OnLoad
4215 void Threads::create_vm_init_libraries() {
4216   extern struct JavaVM_ main_vm;
4217   AgentLibrary* agent;
4218 
4219   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4220     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4221 
4222     if (on_load_entry != NULL) {
4223       // Invoke the JVM_OnLoad function
4224       JavaThread* thread = JavaThread::current();
4225       ThreadToNativeFromVM ttn(thread);
4226       HandleMark hm(thread);
4227       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4228       if (err != JNI_OK) {
4229         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4230       }
4231     } else {
4232       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4233     }
4234   }
4235 }
4236 
4237 
4238 // Last thread running calls java.lang.Shutdown.shutdown()
4239 void JavaThread::invoke_shutdown_hooks() {
4240   HandleMark hm(this);
4241 
4242   // We could get here with a pending exception, if so clear it now.
4243   if (this->has_pending_exception()) {
4244     this->clear_pending_exception();
4245   }
4246 
4247   EXCEPTION_MARK;
4248   Klass* shutdown_klass =
4249     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4250                                       THREAD);
4251   if (shutdown_klass != NULL) {
4252     // SystemDictionary::resolve_or_null will return null if there was
4253     // an exception.  If we cannot load the Shutdown class, just don't
4254     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
4255     // and finalizers (if runFinalizersOnExit is set) won't be run.
4256     // Note that if a shutdown hook was registered or runFinalizersOnExit
4257     // was called, the Shutdown class would have already been loaded
4258     // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4259     JavaValue result(T_VOID);
4260     JavaCalls::call_static(&result,
4261                            shutdown_klass,
4262                            vmSymbols::shutdown_method_name(),
4263                            vmSymbols::void_method_signature(),
4264                            THREAD);
4265   }
4266   CLEAR_PENDING_EXCEPTION;
4267 }
4268 
4269 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4270 // the program falls off the end of main(). Another VM exit path is through
4271 // vm_exit() when the program calls System.exit() to return a value or when
4272 // there is a serious error in VM. The two shutdown paths are not exactly
4273 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4274 // and VM_Exit op at VM level.
4275 //
4276 // Shutdown sequence:
4277 //   + Shutdown native memory tracking if it is on
4278 //   + Wait until we are the last non-daemon thread to execute
4279 //     <-- every thing is still working at this moment -->
4280 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4281 //        shutdown hooks, run finalizers if finalization-on-exit
4282 //   + Call before_exit(), prepare for VM exit
4283 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4284 //        currently the only user of this mechanism is File.deleteOnExit())
4285 //      > stop StatSampler, watcher thread, CMS threads,
4286 //        post thread end and vm death events to JVMTI,
4287 //        stop signal thread
4288 //   + Call JavaThread::exit(), it will:
4289 //      > release JNI handle blocks, remove stack guard pages
4290 //      > remove this thread from Threads list
4291 //     <-- no more Java code from this thread after this point -->
4292 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4293 //     the compiler threads at safepoint
4294 //     <-- do not use anything that could get blocked by Safepoint -->
4295 //   + Disable tracing at JNI/JVM barriers
4296 //   + Set _vm_exited flag for threads that are still running native code
4297 //   + Delete this thread
4298 //   + Call exit_globals()
4299 //      > deletes tty
4300 //      > deletes PerfMemory resources
4301 //   + Return to caller
4302 
4303 bool Threads::destroy_vm() {
4304   JavaThread* thread = JavaThread::current();
4305 
4306 #ifdef ASSERT
4307   _vm_complete = false;
4308 #endif
4309   // Wait until we are the last non-daemon thread to execute
4310   { MutexLocker nu(Threads_lock);
4311     while (Threads::number_of_non_daemon_threads() > 1)
4312       // This wait should make safepoint checks, wait without a timeout,
4313       // and wait as a suspend-equivalent condition.
4314       Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4315                          Mutex::_as_suspend_equivalent_flag);
4316   }
4317 
4318   // Hang forever on exit if we are reporting an error.
4319   if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4320     os::infinite_sleep();
4321   }
4322   os::wait_for_keypress_at_exit();
4323 
4324   // run Java level shutdown hooks
4325   thread->invoke_shutdown_hooks();
4326 
4327   before_exit(thread);
4328 
4329   thread->exit(true);
4330 
4331   // Stop VM thread.
4332   {
4333     // 4945125 The vm thread comes to a safepoint during exit.
4334     // GC vm_operations can get caught at the safepoint, and the
4335     // heap is unparseable if they are caught. Grab the Heap_lock
4336     // to prevent this. The GC vm_operations will not be able to
4337     // queue until after the vm thread is dead. After this point,
4338     // we'll never emerge out of the safepoint before the VM exits.
4339 
4340     MutexLocker ml(Heap_lock);
4341 
4342     VMThread::wait_for_vm_thread_exit();
4343     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4344     VMThread::destroy();
4345   }
4346 
4347   // clean up ideal graph printers
4348 #if defined(COMPILER2) && !defined(PRODUCT)
4349   IdealGraphPrinter::clean_up();
4350 #endif
4351 
4352   // Now, all Java threads are gone except daemon threads. Daemon threads
4353   // running Java code or in VM are stopped by the Safepoint. However,
4354   // daemon threads executing native code are still running.  But they
4355   // will be stopped at native=>Java/VM barriers. Note that we can't
4356   // simply kill or suspend them, as it is inherently deadlock-prone.
4357 
4358   VM_Exit::set_vm_exited();
4359 
4360   notify_vm_shutdown();
4361 
4362   // We are after VM_Exit::set_vm_exited() so we can't call
4363   // thread->smr_delete() or we will block on the Threads_lock.
4364   // Deleting the shutdown thread here is safe because another
4365   // JavaThread cannot have an active ThreadsListHandle for
4366   // this JavaThread.
4367   delete thread;
4368 
4369 #if INCLUDE_JVMCI
4370   if (JVMCICounterSize > 0) {
4371     FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4372   }
4373 #endif
4374 
4375   // exit_globals() will delete tty
4376   exit_globals();
4377 
4378   LogConfiguration::finalize();
4379 
4380   return true;
4381 }
4382 
4383 
4384 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4385   if (version == JNI_VERSION_1_1) return JNI_TRUE;
4386   return is_supported_jni_version(version);
4387 }
4388 
4389 
4390 jboolean Threads::is_supported_jni_version(jint version) {
4391   if (version == JNI_VERSION_1_2) return JNI_TRUE;
4392   if (version == JNI_VERSION_1_4) return JNI_TRUE;
4393   if (version == JNI_VERSION_1_6) return JNI_TRUE;
4394   if (version == JNI_VERSION_1_8) return JNI_TRUE;
4395   if (version == JNI_VERSION_9) return JNI_TRUE;
4396   if (version == JNI_VERSION_10) return JNI_TRUE;
4397   return JNI_FALSE;
4398 }
4399 
4400 
4401 void Threads::add(JavaThread* p, bool force_daemon) {
4402   // The threads lock must be owned at this point
4403   assert_locked_or_safepoint(Threads_lock);
4404 
4405   // See the comment for this method in thread.hpp for its purpose and
4406   // why it is called here.
4407   p->initialize_queues();
4408   p->set_next(_thread_list);
4409   _thread_list = p;
4410 
4411   // Once a JavaThread is added to the Threads list, smr_delete() has
4412   // to be used to delete it. Otherwise we can just delete it directly.
4413   p->set_on_thread_list();
4414 
4415   _number_of_threads++;
4416   oop threadObj = p->threadObj();
4417   bool daemon = true;
4418   // Bootstrapping problem: threadObj can be null for initial
4419   // JavaThread (or for threads attached via JNI)
4420   if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4421     _number_of_non_daemon_threads++;
4422     daemon = false;
4423   }
4424 
4425   ThreadService::add_thread(p, daemon);
4426 
4427   // Maintain fast thread list
4428   ThreadsSMRSupport::add_thread(p);
4429 
4430   // Possible GC point.
4431   Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4432 }
4433 
4434 void Threads::remove(JavaThread* p) {
4435 
4436   // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
4437   ObjectSynchronizer::omFlush(p);
4438 
4439   // Extra scope needed for Thread_lock, so we can check
4440   // that we do not remove thread without safepoint code notice
4441   { MutexLocker ml(Threads_lock);
4442 
4443     assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4444 
4445     // Maintain fast thread list
4446     ThreadsSMRSupport::remove_thread(p);
4447 
4448     JavaThread* current = _thread_list;
4449     JavaThread* prev    = NULL;
4450 
4451     while (current != p) {
4452       prev    = current;
4453       current = current->next();
4454     }
4455 
4456     if (prev) {
4457       prev->set_next(current->next());
4458     } else {
4459       _thread_list = p->next();
4460     }
4461 
4462     _number_of_threads--;
4463     oop threadObj = p->threadObj();
4464     bool daemon = true;
4465     if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4466       _number_of_non_daemon_threads--;
4467       daemon = false;
4468 
4469       // Only one thread left, do a notify on the Threads_lock so a thread waiting
4470       // on destroy_vm will wake up.
4471       if (number_of_non_daemon_threads() == 1) {
4472         Threads_lock->notify_all();
4473       }
4474     }
4475     ThreadService::remove_thread(p, daemon);
4476 
4477     // Make sure that safepoint code disregard this thread. This is needed since
4478     // the thread might mess around with locks after this point. This can cause it
4479     // to do callbacks into the safepoint code. However, the safepoint code is not aware
4480     // of this thread since it is removed from the queue.
4481     p->set_terminated_value();
4482   } // unlock Threads_lock
4483 
4484   // Since Events::log uses a lock, we grab it outside the Threads_lock
4485   Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4486 }
4487 
4488 // Operations on the Threads list for GC.  These are not explicitly locked,
4489 // but the garbage collector must provide a safe context for them to run.
4490 // In particular, these things should never be called when the Threads_lock
4491 // is held by some other thread. (Note: the Safepoint abstraction also
4492 // uses the Threads_lock to guarantee this property. It also makes sure that
4493 // all threads gets blocked when exiting or starting).
4494 
4495 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4496   ALL_JAVA_THREADS(p) {
4497     p->oops_do(f, cf);
4498   }
4499   VMThread::vm_thread()->oops_do(f, cf);
4500 }
4501 
4502 void Threads::change_thread_claim_parity() {
4503   // Set the new claim parity.
4504   assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4505          "Not in range.");
4506   _thread_claim_parity++;
4507   if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4508   assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4509          "Not in range.");
4510 }
4511 
4512 #ifdef ASSERT
4513 void Threads::assert_all_threads_claimed() {
4514   ALL_JAVA_THREADS(p) {
4515     const int thread_parity = p->oops_do_parity();
4516     assert((thread_parity == _thread_claim_parity),
4517            "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4518   }
4519   VMThread* vmt = VMThread::vm_thread();
4520   const int thread_parity = vmt->oops_do_parity();
4521   assert((thread_parity == _thread_claim_parity),
4522          "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity);
4523 }
4524 #endif // ASSERT
4525 
4526 class ParallelOopsDoThreadClosure : public ThreadClosure {
4527 private:
4528   OopClosure* _f;
4529   CodeBlobClosure* _cf;
4530   CodeBlobClosure* _nmethods_cl;
4531   ThreadClosure* _thread_cl;
4532 public:
4533   ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf, CodeBlobClosure* nmethods_cl, ThreadClosure* thread_cl) :
4534           _f(f), _cf(cf), _nmethods_cl(nmethods_cl), _thread_cl(thread_cl) {}
4535   void do_thread(Thread* t) {
4536     t->oops_do(_f, _cf);
4537     if (_thread_cl != NULL) {
4538       _thread_cl->do_thread(t);
4539     }
4540     if (_nmethods_cl != NULL && t->is_Java_thread() && !t->is_Code_cache_sweeper_thread()) {
4541       ((JavaThread*)t)->nmethods_do(_nmethods_cl);
4542     }
4543   }
4544 };
4545 
4546 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf, CodeBlobClosure* nmethods_cl,
4547                                         ThreadClosure* thread_cl) {
4548   ParallelOopsDoThreadClosure tc(f, cf, nmethods_cl, thread_cl);
4549   possibly_parallel_threads_do(is_par, &tc);
4550 }
4551 
4552 #if INCLUDE_ALL_GCS
4553 // Used by ParallelScavenge
4554 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4555   ALL_JAVA_THREADS(p) {
4556     q->enqueue(new ThreadRootsTask(p));
4557   }
4558   q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4559 }
4560 
4561 // Used by Parallel Old
4562 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4563   ALL_JAVA_THREADS(p) {
4564     q->enqueue(new ThreadRootsMarkingTask(p));
4565   }
4566   q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4567 }
4568 
4569 void JavaThread::set_gc_state(char in_prog) {
4570   _gc_state = in_prog;
4571 }
4572 
4573 void JavaThread::set_gc_state_all_threads(char in_prog) {
4574   assert_locked_or_safepoint(Threads_lock);
4575   _gc_state_global = in_prog;
4576   ALL_JAVA_THREADS(t) {
4577     t->set_gc_state(in_prog);
4578   }
4579 }
4580 
4581 #endif // INCLUDE_ALL_GCS
4582 
4583 void Threads::nmethods_do(CodeBlobClosure* cf) {
4584   ALL_JAVA_THREADS(p) {
4585     // This is used by the code cache sweeper to mark nmethods that are active
4586     // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4587     // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4588     if(!p->is_Code_cache_sweeper_thread()) {
4589       p->nmethods_do(cf);
4590     }
4591   }
4592 }
4593 
4594 void Threads::metadata_do(void f(Metadata*)) {
4595   ALL_JAVA_THREADS(p) {
4596     p->metadata_do(f);
4597   }
4598 }
4599 
4600 class ThreadHandlesClosure : public ThreadClosure {
4601   void (*_f)(Metadata*);
4602  public:
4603   ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4604   virtual void do_thread(Thread* thread) {
4605     thread->metadata_handles_do(_f);
4606   }
4607 };
4608 
4609 void Threads::metadata_handles_do(void f(Metadata*)) {
4610   // Only walk the Handles in Thread.
4611   ThreadHandlesClosure handles_closure(f);
4612   threads_do(&handles_closure);
4613 }
4614 
4615 void Threads::deoptimized_wrt_marked_nmethods() {
4616   ALL_JAVA_THREADS(p) {
4617     p->deoptimized_wrt_marked_nmethods();
4618   }
4619 }
4620 
4621 
4622 // Get count Java threads that are waiting to enter the specified monitor.
4623 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4624                                                          int count,
4625                                                          address monitor) {
4626   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4627 
4628   int i = 0;
4629   DO_JAVA_THREADS(t_list, p) {
4630     if (!p->can_call_java()) continue;
4631 
4632     address pending = (address)p->current_pending_monitor();
4633     if (pending == monitor) {             // found a match
4634       if (i < count) result->append(p);   // save the first count matches
4635       i++;
4636     }
4637   }
4638 
4639   return result;
4640 }
4641 
4642 
4643 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4644                                                       address owner) {
4645   // NULL owner means not locked so we can skip the search
4646   if (owner == NULL) return NULL;
4647 
4648   DO_JAVA_THREADS(t_list, p) {
4649     // first, see if owner is the address of a Java thread
4650     if (owner == (address)p) return p;
4651   }
4652 
4653   // Cannot assert on lack of success here since this function may be
4654   // used by code that is trying to report useful problem information
4655   // like deadlock detection.
4656   if (UseHeavyMonitors) return NULL;
4657 
4658   // If we didn't find a matching Java thread and we didn't force use of
4659   // heavyweight monitors, then the owner is the stack address of the
4660   // Lock Word in the owning Java thread's stack.
4661   //
4662   JavaThread* the_owner = NULL;
4663   DO_JAVA_THREADS(t_list, q) {
4664     if (q->is_lock_owned(owner)) {
4665       the_owner = q;
4666       break;
4667     }
4668   }
4669 
4670   // cannot assert on lack of success here; see above comment
4671   return the_owner;
4672 }
4673 
4674 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4675 void Threads::print_on(outputStream* st, bool print_stacks,
4676                        bool internal_format, bool print_concurrent_locks) {
4677   char buf[32];
4678   st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4679 
4680   st->print_cr("Full thread dump %s (%s %s):",
4681                Abstract_VM_Version::vm_name(),
4682                Abstract_VM_Version::vm_release(),
4683                Abstract_VM_Version::vm_info_string());
4684   st->cr();
4685 
4686 #if INCLUDE_SERVICES
4687   // Dump concurrent locks
4688   ConcurrentLocksDump concurrent_locks;
4689   if (print_concurrent_locks) {
4690     concurrent_locks.dump_at_safepoint();
4691   }
4692 #endif // INCLUDE_SERVICES
4693 
4694   ThreadsSMRSupport::print_info_on(st);
4695   st->cr();
4696 
4697   ALL_JAVA_THREADS(p) {
4698     ResourceMark rm;
4699     p->print_on(st);
4700     if (print_stacks) {
4701       if (internal_format) {
4702         p->trace_stack();
4703       } else {
4704         p->print_stack_on(st);
4705       }
4706     }
4707     st->cr();
4708 #if INCLUDE_SERVICES
4709     if (print_concurrent_locks) {
4710       concurrent_locks.print_locks_on(p, st);
4711     }
4712 #endif // INCLUDE_SERVICES
4713   }
4714 
4715   VMThread::vm_thread()->print_on(st);
4716   st->cr();
4717   Universe::heap()->print_gc_threads_on(st);
4718   WatcherThread* wt = WatcherThread::watcher_thread();
4719   if (wt != NULL) {
4720     wt->print_on(st);
4721     st->cr();
4722   }
4723 
4724   st->flush();
4725 }
4726 
4727 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4728                              int buflen, bool* found_current) {
4729   if (this_thread != NULL) {
4730     bool is_current = (current == this_thread);
4731     *found_current = *found_current || is_current;
4732     st->print("%s", is_current ? "=>" : "  ");
4733 
4734     st->print(PTR_FORMAT, p2i(this_thread));
4735     st->print(" ");
4736     this_thread->print_on_error(st, buf, buflen);
4737     st->cr();
4738   }
4739 }
4740 
4741 class PrintOnErrorClosure : public ThreadClosure {
4742   outputStream* _st;
4743   Thread* _current;
4744   char* _buf;
4745   int _buflen;
4746   bool* _found_current;
4747  public:
4748   PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4749                       int buflen, bool* found_current) :
4750    _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4751 
4752   virtual void do_thread(Thread* thread) {
4753     Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4754   }
4755 };
4756 
4757 // Threads::print_on_error() is called by fatal error handler. It's possible
4758 // that VM is not at safepoint and/or current thread is inside signal handler.
4759 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4760 // memory (even in resource area), it might deadlock the error handler.
4761 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4762                              int buflen) {
4763   ThreadsSMRSupport::print_info_on(st);
4764   st->cr();
4765 
4766   bool found_current = false;
4767   st->print_cr("Java Threads: ( => current thread )");
4768   ALL_JAVA_THREADS(thread) {
4769     print_on_error(thread, st, current, buf, buflen, &found_current);
4770   }
4771   st->cr();
4772 
4773   st->print_cr("Other Threads:");
4774   print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4775   print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4776 
4777   PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4778   Universe::heap()->gc_threads_do(&print_closure);
4779 
4780   if (!found_current) {
4781     st->cr();
4782     st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4783     current->print_on_error(st, buf, buflen);
4784     st->cr();
4785   }
4786   st->cr();
4787 
4788   st->print_cr("Threads with active compile tasks:");
4789   print_threads_compiling(st, buf, buflen);
4790 }
4791 
4792 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4793   ALL_JAVA_THREADS(thread) {
4794     if (thread->is_Compiler_thread()) {
4795       CompilerThread* ct = (CompilerThread*) thread;
4796 
4797       // Keep task in local variable for NULL check.
4798       // ct->_task might be set to NULL by concurring compiler thread
4799       // because it completed the compilation. The task is never freed,
4800       // though, just returned to a free list.
4801       CompileTask* task = ct->task();
4802       if (task != NULL) {
4803         thread->print_name_on_error(st, buf, buflen);
4804         task->print(st, NULL, true, true);
4805       }
4806     }
4807   }
4808 }
4809 
4810 
4811 // Internal SpinLock and Mutex
4812 // Based on ParkEvent
4813 
4814 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4815 //
4816 // We employ SpinLocks _only for low-contention, fixed-length
4817 // short-duration critical sections where we're concerned
4818 // about native mutex_t or HotSpot Mutex:: latency.
4819 // The mux construct provides a spin-then-block mutual exclusion
4820 // mechanism.
4821 //
4822 // Testing has shown that contention on the ListLock guarding gFreeList
4823 // is common.  If we implement ListLock as a simple SpinLock it's common
4824 // for the JVM to devolve to yielding with little progress.  This is true
4825 // despite the fact that the critical sections protected by ListLock are
4826 // extremely short.
4827 //
4828 // TODO-FIXME: ListLock should be of type SpinLock.
4829 // We should make this a 1st-class type, integrated into the lock
4830 // hierarchy as leaf-locks.  Critically, the SpinLock structure
4831 // should have sufficient padding to avoid false-sharing and excessive
4832 // cache-coherency traffic.
4833 
4834 
4835 typedef volatile int SpinLockT;
4836 
4837 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4838   if (Atomic::cmpxchg (1, adr, 0) == 0) {
4839     return;   // normal fast-path return
4840   }
4841 
4842   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4843   TEVENT(SpinAcquire - ctx);
4844   int ctr = 0;
4845   int Yields = 0;
4846   for (;;) {
4847     while (*adr != 0) {
4848       ++ctr;
4849       if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4850         if (Yields > 5) {
4851           os::naked_short_sleep(1);
4852         } else {
4853           os::naked_yield();
4854           ++Yields;
4855         }
4856       } else {
4857         SpinPause();
4858       }
4859     }
4860     if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4861   }
4862 }
4863 
4864 void Thread::SpinRelease(volatile int * adr) {
4865   assert(*adr != 0, "invariant");
4866   OrderAccess::fence();      // guarantee at least release consistency.
4867   // Roach-motel semantics.
4868   // It's safe if subsequent LDs and STs float "up" into the critical section,
4869   // but prior LDs and STs within the critical section can't be allowed
4870   // to reorder or float past the ST that releases the lock.
4871   // Loads and stores in the critical section - which appear in program
4872   // order before the store that releases the lock - must also appear
4873   // before the store that releases the lock in memory visibility order.
4874   // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4875   // the ST of 0 into the lock-word which releases the lock, so fence
4876   // more than covers this on all platforms.
4877   *adr = 0;
4878 }
4879 
4880 // muxAcquire and muxRelease:
4881 //
4882 // *  muxAcquire and muxRelease support a single-word lock-word construct.
4883 //    The LSB of the word is set IFF the lock is held.
4884 //    The remainder of the word points to the head of a singly-linked list
4885 //    of threads blocked on the lock.
4886 //
4887 // *  The current implementation of muxAcquire-muxRelease uses its own
4888 //    dedicated Thread._MuxEvent instance.  If we're interested in
4889 //    minimizing the peak number of extant ParkEvent instances then
4890 //    we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4891 //    as certain invariants were satisfied.  Specifically, care would need
4892 //    to be taken with regards to consuming unpark() "permits".
4893 //    A safe rule of thumb is that a thread would never call muxAcquire()
4894 //    if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4895 //    park().  Otherwise the _ParkEvent park() operation in muxAcquire() could
4896 //    consume an unpark() permit intended for monitorenter, for instance.
4897 //    One way around this would be to widen the restricted-range semaphore
4898 //    implemented in park().  Another alternative would be to provide
4899 //    multiple instances of the PlatformEvent() for each thread.  One
4900 //    instance would be dedicated to muxAcquire-muxRelease, for instance.
4901 //
4902 // *  Usage:
4903 //    -- Only as leaf locks
4904 //    -- for short-term locking only as muxAcquire does not perform
4905 //       thread state transitions.
4906 //
4907 // Alternatives:
4908 // *  We could implement muxAcquire and muxRelease with MCS or CLH locks
4909 //    but with parking or spin-then-park instead of pure spinning.
4910 // *  Use Taura-Oyama-Yonenzawa locks.
4911 // *  It's possible to construct a 1-0 lock if we encode the lockword as
4912 //    (List,LockByte).  Acquire will CAS the full lockword while Release
4913 //    will STB 0 into the LockByte.  The 1-0 scheme admits stranding, so
4914 //    acquiring threads use timers (ParkTimed) to detect and recover from
4915 //    the stranding window.  Thread/Node structures must be aligned on 256-byte
4916 //    boundaries by using placement-new.
4917 // *  Augment MCS with advisory back-link fields maintained with CAS().
4918 //    Pictorially:  LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4919 //    The validity of the backlinks must be ratified before we trust the value.
4920 //    If the backlinks are invalid the exiting thread must back-track through the
4921 //    the forward links, which are always trustworthy.
4922 // *  Add a successor indication.  The LockWord is currently encoded as
4923 //    (List, LOCKBIT:1).  We could also add a SUCCBIT or an explicit _succ variable
4924 //    to provide the usual futile-wakeup optimization.
4925 //    See RTStt for details.
4926 // *  Consider schedctl.sc_nopreempt to cover the critical section.
4927 //
4928 
4929 
4930 const intptr_t LOCKBIT = 1;
4931 
4932 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4933   intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4934   if (w == 0) return;
4935   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4936     return;
4937   }
4938 
4939   TEVENT(muxAcquire - Contention);
4940   ParkEvent * const Self = Thread::current()->_MuxEvent;
4941   assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4942   for (;;) {
4943     int its = (os::is_MP() ? 100 : 0) + 1;
4944 
4945     // Optional spin phase: spin-then-park strategy
4946     while (--its >= 0) {
4947       w = *Lock;
4948       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4949         return;
4950       }
4951     }
4952 
4953     Self->reset();
4954     Self->OnList = intptr_t(Lock);
4955     // The following fence() isn't _strictly necessary as the subsequent
4956     // CAS() both serializes execution and ratifies the fetched *Lock value.
4957     OrderAccess::fence();
4958     for (;;) {
4959       w = *Lock;
4960       if ((w & LOCKBIT) == 0) {
4961         if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4962           Self->OnList = 0;   // hygiene - allows stronger asserts
4963           return;
4964         }
4965         continue;      // Interference -- *Lock changed -- Just retry
4966       }
4967       assert(w & LOCKBIT, "invariant");
4968       Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4969       if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4970     }
4971 
4972     while (Self->OnList != 0) {
4973       Self->park();
4974     }
4975   }
4976 }
4977 
4978 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4979   intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4980   if (w == 0) return;
4981   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4982     return;
4983   }
4984 
4985   TEVENT(muxAcquire - Contention);
4986   ParkEvent * ReleaseAfter = NULL;
4987   if (ev == NULL) {
4988     ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4989   }
4990   assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4991   for (;;) {
4992     guarantee(ev->OnList == 0, "invariant");
4993     int its = (os::is_MP() ? 100 : 0) + 1;
4994 
4995     // Optional spin phase: spin-then-park strategy
4996     while (--its >= 0) {
4997       w = *Lock;
4998       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4999         if (ReleaseAfter != NULL) {
5000           ParkEvent::Release(ReleaseAfter);
5001         }
5002         return;
5003       }
5004     }
5005 
5006     ev->reset();
5007     ev->OnList = intptr_t(Lock);
5008     // The following fence() isn't _strictly necessary as the subsequent
5009     // CAS() both serializes execution and ratifies the fetched *Lock value.
5010     OrderAccess::fence();
5011     for (;;) {
5012       w = *Lock;
5013       if ((w & LOCKBIT) == 0) {
5014         if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5015           ev->OnList = 0;
5016           // We call ::Release while holding the outer lock, thus
5017           // artificially lengthening the critical section.
5018           // Consider deferring the ::Release() until the subsequent unlock(),
5019           // after we've dropped the outer lock.
5020           if (ReleaseAfter != NULL) {
5021             ParkEvent::Release(ReleaseAfter);
5022           }
5023           return;
5024         }
5025         continue;      // Interference -- *Lock changed -- Just retry
5026       }
5027       assert(w & LOCKBIT, "invariant");
5028       ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
5029       if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
5030     }
5031 
5032     while (ev->OnList != 0) {
5033       ev->park();
5034     }
5035   }
5036 }
5037 
5038 // Release() must extract a successor from the list and then wake that thread.
5039 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
5040 // similar to that used by ParkEvent::Allocate() and ::Release().  DMR-based
5041 // Release() would :
5042 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
5043 // (B) Extract a successor from the private list "in-hand"
5044 // (C) attempt to CAS() the residual back into *Lock over null.
5045 //     If there were any newly arrived threads and the CAS() would fail.
5046 //     In that case Release() would detach the RATs, re-merge the list in-hand
5047 //     with the RATs and repeat as needed.  Alternately, Release() might
5048 //     detach and extract a successor, but then pass the residual list to the wakee.
5049 //     The wakee would be responsible for reattaching and remerging before it
5050 //     competed for the lock.
5051 //
5052 // Both "pop" and DMR are immune from ABA corruption -- there can be
5053 // multiple concurrent pushers, but only one popper or detacher.
5054 // This implementation pops from the head of the list.  This is unfair,
5055 // but tends to provide excellent throughput as hot threads remain hot.
5056 // (We wake recently run threads first).
5057 //
5058 // All paths through muxRelease() will execute a CAS.
5059 // Release consistency -- We depend on the CAS in muxRelease() to provide full
5060 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
5061 // executed within the critical section are complete and globally visible before the
5062 // store (CAS) to the lock-word that releases the lock becomes globally visible.
5063 void Thread::muxRelease(volatile intptr_t * Lock)  {
5064   for (;;) {
5065     const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
5066     assert(w & LOCKBIT, "invariant");
5067     if (w == LOCKBIT) return;
5068     ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
5069     assert(List != NULL, "invariant");
5070     assert(List->OnList == intptr_t(Lock), "invariant");
5071     ParkEvent * const nxt = List->ListNext;
5072     guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
5073 
5074     // The following CAS() releases the lock and pops the head element.
5075     // The CAS() also ratifies the previously fetched lock-word value.
5076     if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
5077       continue;
5078     }
5079     List->OnList = 0;
5080     OrderAccess::fence();
5081     List->unpark();
5082     return;
5083   }
5084 }
5085 
5086 
5087 void Threads::verify() {
5088   ALL_JAVA_THREADS(p) {
5089     p->verify();
5090   }
5091   VMThread* thread = VMThread::vm_thread();
5092   if (thread != NULL) thread->verify();
5093 }