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