rev 47862 : imported patch 10.07.open.rebase_20171110.dcubed
rev 47863 : imported patch 10.08.open.rebase_20171114.rehn
rev 47864 : imported patch 10.09.open.TLH_hang_fix.rehn
rev 47865 : dholmes CR: Fix indents, trailing spaces and various typos. Add descriptions for the '_cnt', '_max' and '_times" fields, add impl notes to document the type choices.
rev 47866 : robinw CR: Fix some inefficient code, update some comments, fix some indents, and add some 'const' specifiers.

   1 /*
   2  * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "jvm.h"
  27 #include "classfile/classLoader.hpp"
  28 #include "classfile/javaClasses.hpp"
  29 #include "classfile/moduleEntry.hpp"
  30 #include "classfile/systemDictionary.hpp"
  31 #include "classfile/vmSymbols.hpp"
  32 #include "code/codeCache.hpp"
  33 #include "code/scopeDesc.hpp"
  34 #include "compiler/compileBroker.hpp"
  35 #include "compiler/compileTask.hpp"
  36 #include "gc/shared/gcId.hpp"
  37 #include "gc/shared/gcLocker.inline.hpp"
  38 #include "gc/shared/workgroup.hpp"
  39 #include "interpreter/interpreter.hpp"
  40 #include "interpreter/linkResolver.hpp"
  41 #include "interpreter/oopMapCache.hpp"
  42 #include "jvmtifiles/jvmtiEnv.hpp"
  43 #include "logging/log.hpp"
  44 #include "logging/logConfiguration.hpp"
  45 #include "logging/logStream.hpp"
  46 #include "memory/metaspaceShared.hpp"
  47 #include "memory/oopFactory.hpp"
  48 #include "memory/resourceArea.hpp"
  49 #include "memory/universe.inline.hpp"
  50 #include "oops/instanceKlass.hpp"
  51 #include "oops/objArrayOop.hpp"
  52 #include "oops/oop.inline.hpp"
  53 #include "oops/symbol.hpp"
  54 #include "oops/verifyOopClosure.hpp"
  55 #include "prims/jvm_misc.hpp"
  56 #include "prims/jvmtiExport.hpp"
  57 #include "prims/jvmtiThreadState.hpp"
  58 #include "prims/privilegedStack.hpp"
  59 #include "runtime/arguments.hpp"
  60 #include "runtime/atomic.hpp"
  61 #include "runtime/biasedLocking.hpp"
  62 #include "runtime/commandLineFlagConstraintList.hpp"
  63 #include "runtime/commandLineFlagWriteableList.hpp"
  64 #include "runtime/commandLineFlagRangeList.hpp"
  65 #include "runtime/deoptimization.hpp"
  66 #include "runtime/frame.inline.hpp"
  67 #include "runtime/globals.hpp"
  68 #include "runtime/handshake.hpp"
  69 #include "runtime/init.hpp"
  70 #include "runtime/interfaceSupport.hpp"
  71 #include "runtime/java.hpp"
  72 #include "runtime/javaCalls.hpp"
  73 #include "runtime/jniPeriodicChecker.hpp"

  74 #include "runtime/memprofiler.hpp"
  75 #include "runtime/mutexLocker.hpp"
  76 #include "runtime/objectMonitor.hpp"
  77 #include "runtime/orderAccess.inline.hpp"
  78 #include "runtime/osThread.hpp"
  79 #include "runtime/prefetch.inline.hpp"
  80 #include "runtime/safepoint.hpp"
  81 #include "runtime/safepointMechanism.inline.hpp"
  82 #include "runtime/sharedRuntime.hpp"
  83 #include "runtime/statSampler.hpp"
  84 #include "runtime/stubRoutines.hpp"
  85 #include "runtime/sweeper.hpp"
  86 #include "runtime/task.hpp"
  87 #include "runtime/thread.inline.hpp"
  88 #include "runtime/threadCritical.hpp"
  89 #include "runtime/threadSMR.inline.hpp"
  90 #include "runtime/timer.hpp"
  91 #include "runtime/timerTrace.hpp"
  92 #include "runtime/vframe.hpp"
  93 #include "runtime/vframeArray.hpp"
  94 #include "runtime/vframe_hp.hpp"
  95 #include "runtime/vmThread.hpp"
  96 #include "runtime/vm_operations.hpp"
  97 #include "runtime/vm_version.hpp"
  98 #include "services/attachListener.hpp"
  99 #include "services/management.hpp"
 100 #include "services/memTracker.hpp"
 101 #include "services/threadService.hpp"
 102 #include "trace/traceMacros.hpp"
 103 #include "trace/tracing.hpp"
 104 #include "utilities/align.hpp"
 105 #include "utilities/defaultStream.hpp"
 106 #include "utilities/dtrace.hpp"
 107 #include "utilities/events.hpp"
 108 #include "utilities/macros.hpp"
 109 #include "utilities/preserveException.hpp"
 110 #include "utilities/resourceHash.hpp"
 111 #include "utilities/vmError.hpp"
 112 #if INCLUDE_ALL_GCS
 113 #include "gc/cms/concurrentMarkSweepThread.hpp"
 114 #include "gc/g1/concurrentMarkThread.inline.hpp"
 115 #include "gc/parallel/pcTasks.hpp"
 116 #endif // INCLUDE_ALL_GCS
 117 #if INCLUDE_JVMCI
 118 #include "jvmci/jvmciCompiler.hpp"
 119 #include "jvmci/jvmciRuntime.hpp"
 120 #include "logging/logHandle.hpp"
 121 #endif
 122 #ifdef COMPILER1
 123 #include "c1/c1_Compiler.hpp"
 124 #endif
 125 #ifdef COMPILER2
 126 #include "opto/c2compiler.hpp"
 127 #include "opto/idealGraphPrinter.hpp"
 128 #endif
 129 #if INCLUDE_RTM_OPT
 130 #include "runtime/rtmLocking.hpp"
 131 #endif
 132 
 133 // Initialization after module runtime initialization
 134 void universe_post_module_init();  // must happen after call_initPhase2
 135 
 136 #ifdef DTRACE_ENABLED
 137 
 138 // Only bother with this argument setup if dtrace is available
 139 
 140   #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
 141   #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
 142 
 143   #define DTRACE_THREAD_PROBE(probe, javathread)                           \
 144     {                                                                      \
 145       ResourceMark rm(this);                                               \
 146       int len = 0;                                                         \
 147       const char* name = (javathread)->get_thread_name();                  \
 148       len = strlen(name);                                                  \
 149       HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */               \
 150         (char *) name, len,                                                \
 151         java_lang_Thread::thread_id((javathread)->threadObj()),            \
 152         (uintptr_t) (javathread)->osthread()->thread_id(),                 \
 153         java_lang_Thread::is_daemon((javathread)->threadObj()));           \
 154     }
 155 
 156 #else //  ndef DTRACE_ENABLED
 157 
 158   #define DTRACE_THREAD_PROBE(probe, javathread)
 159 
 160 #endif // ndef DTRACE_ENABLED
 161 
 162 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 163 // Current thread is maintained as a thread-local variable
 164 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
 165 #endif
 166 // Class hierarchy
 167 // - Thread
 168 //   - VMThread
 169 //   - WatcherThread
 170 //   - ConcurrentMarkSweepThread
 171 //   - JavaThread
 172 //     - CompilerThread
 173 
 174 // ======= Thread ========
 175 // Support for forcing alignment of thread objects for biased locking
 176 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
 177   if (UseBiasedLocking) {
 178     const int alignment = markOopDesc::biased_lock_alignment;
 179     size_t aligned_size = size + (alignment - sizeof(intptr_t));
 180     void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
 181                                           : AllocateHeap(aligned_size, flags, CURRENT_PC,
 182                                                          AllocFailStrategy::RETURN_NULL);
 183     void* aligned_addr     = align_up(real_malloc_addr, alignment);
 184     assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
 185            ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
 186            "JavaThread alignment code overflowed allocated storage");
 187     if (aligned_addr != real_malloc_addr) {
 188       log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
 189                               p2i(real_malloc_addr),
 190                               p2i(aligned_addr));
 191     }
 192     ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
 193     return aligned_addr;
 194   } else {
 195     return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
 196                        : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
 197   }
 198 }
 199 
 200 void Thread::operator delete(void* p) {
 201   if (UseBiasedLocking) {
 202     FreeHeap(((Thread*) p)->_real_malloc_address);

 203   } else {
 204     FreeHeap(p);
 205   }
 206 }
 207 
 208 void JavaThread::smr_delete() {
 209   if (_on_thread_list) {
 210     Threads::smr_delete(this);
 211   } else {
 212     delete this;
 213   }
 214 }
 215 
 216 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
 217 // JavaThread
 218 
 219 
 220 Thread::Thread() {
 221   // stack and get_thread
 222   set_stack_base(NULL);
 223   set_stack_size(0);
 224   set_self_raw_id(0);
 225   set_lgrp_id(-1);
 226   DEBUG_ONLY(clear_suspendible_thread();)
 227 
 228   // allocated data structures
 229   set_osthread(NULL);
 230   set_resource_area(new (mtThread)ResourceArea());
 231   DEBUG_ONLY(_current_resource_mark = NULL;)
 232   set_handle_area(new (mtThread) HandleArea(NULL));
 233   set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
 234   set_active_handles(NULL);
 235   set_free_handle_block(NULL);
 236   set_last_handle_mark(NULL);
 237 
 238   // This initial value ==> never claimed.
 239   _oops_do_parity = 0;
 240   _threads_hazard_ptr = NULL;
 241   _nested_threads_hazard_ptr = NULL;
 242   _nested_threads_hazard_ptr_cnt = 0;
 243 
 244   // the handle mark links itself to last_handle_mark
 245   new HandleMark(this);
 246 
 247   // plain initialization
 248   debug_only(_owned_locks = NULL;)
 249   debug_only(_allow_allocation_count = 0;)
 250   NOT_PRODUCT(_allow_safepoint_count = 0;)
 251   NOT_PRODUCT(_skip_gcalot = false;)
 252   _jvmti_env_iteration_count = 0;
 253   set_allocated_bytes(0);
 254   _vm_operation_started_count = 0;
 255   _vm_operation_completed_count = 0;
 256   _current_pending_monitor = NULL;
 257   _current_pending_monitor_is_from_java = true;
 258   _current_waiting_monitor = NULL;
 259   _num_nested_signal = 0;
 260   omFreeList = NULL;
 261   omFreeCount = 0;
 262   omFreeProvision = 32;
 263   omInUseList = NULL;
 264   omInUseCount = 0;
 265 
 266 #ifdef ASSERT
 267   _visited_for_critical_count = false;
 268 #endif
 269 
 270   _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
 271                          Monitor::_safepoint_check_sometimes);
 272   _suspend_flags = 0;
 273 
 274   // thread-specific hashCode stream generator state - Marsaglia shift-xor form
 275   _hashStateX = os::random();
 276   _hashStateY = 842502087;
 277   _hashStateZ = 0x8767;    // (int)(3579807591LL & 0xffff) ;
 278   _hashStateW = 273326509;
 279 
 280   _OnTrap   = 0;
 281   _schedctl = NULL;
 282   _Stalled  = 0;
 283   _TypeTag  = 0x2BAD;
 284 
 285   // Many of the following fields are effectively final - immutable
 286   // Note that nascent threads can't use the Native Monitor-Mutex
 287   // construct until the _MutexEvent is initialized ...
 288   // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
 289   // we might instead use a stack of ParkEvents that we could provision on-demand.
 290   // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
 291   // and ::Release()
 292   _ParkEvent   = ParkEvent::Allocate(this);
 293   _SleepEvent  = ParkEvent::Allocate(this);
 294   _MutexEvent  = ParkEvent::Allocate(this);
 295   _MuxEvent    = ParkEvent::Allocate(this);
 296 
 297 #ifdef CHECK_UNHANDLED_OOPS
 298   if (CheckUnhandledOops) {
 299     _unhandled_oops = new UnhandledOops(this);
 300   }
 301 #endif // CHECK_UNHANDLED_OOPS
 302 #ifdef ASSERT
 303   if (UseBiasedLocking) {
 304     assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
 305     assert(this == _real_malloc_address ||
 306            this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
 307            "bug in forced alignment of thread objects");
 308   }
 309 #endif // ASSERT
 310 }
 311 
 312 void Thread::initialize_thread_current() {
 313 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 314   assert(_thr_current == NULL, "Thread::current already initialized");
 315   _thr_current = this;
 316 #endif
 317   assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
 318   ThreadLocalStorage::set_thread(this);
 319   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 320 }
 321 
 322 void Thread::clear_thread_current() {
 323   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 324 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 325   _thr_current = NULL;
 326 #endif
 327   ThreadLocalStorage::set_thread(NULL);
 328 }
 329 
 330 void Thread::record_stack_base_and_size() {
 331   set_stack_base(os::current_stack_base());
 332   set_stack_size(os::current_stack_size());
 333   // CR 7190089: on Solaris, primordial thread's stack is adjusted
 334   // in initialize_thread(). Without the adjustment, stack size is
 335   // incorrect if stack is set to unlimited (ulimit -s unlimited).
 336   // So far, only Solaris has real implementation of initialize_thread().
 337   //
 338   // set up any platform-specific state.
 339   os::initialize_thread(this);
 340 
 341   // Set stack limits after thread is initialized.
 342   if (is_Java_thread()) {
 343     ((JavaThread*) this)->set_stack_overflow_limit();
 344     ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
 345   }
 346 #if INCLUDE_NMT
 347   // record thread's native stack, stack grows downward
 348   MemTracker::record_thread_stack(stack_end(), stack_size());
 349 #endif // INCLUDE_NMT
 350   log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
 351     PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
 352     os::current_thread_id(), p2i(stack_base() - stack_size()),
 353     p2i(stack_base()), stack_size()/1024);
 354 }
 355 
 356 
 357 Thread::~Thread() {
 358   EVENT_THREAD_DESTRUCT(this);
 359 
 360   // stack_base can be NULL if the thread is never started or exited before
 361   // record_stack_base_and_size called. Although, we would like to ensure
 362   // that all started threads do call record_stack_base_and_size(), there is
 363   // not proper way to enforce that.
 364 #if INCLUDE_NMT
 365   if (_stack_base != NULL) {
 366     MemTracker::release_thread_stack(stack_end(), stack_size());
 367 #ifdef ASSERT
 368     set_stack_base(NULL);
 369 #endif
 370   }
 371 #endif // INCLUDE_NMT
 372 
 373   // deallocate data structures
 374   delete resource_area();
 375   // since the handle marks are using the handle area, we have to deallocated the root
 376   // handle mark before deallocating the thread's handle area,
 377   assert(last_handle_mark() != NULL, "check we have an element");
 378   delete last_handle_mark();
 379   assert(last_handle_mark() == NULL, "check we have reached the end");
 380 
 381   // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
 382   // We NULL out the fields for good hygiene.
 383   ParkEvent::Release(_ParkEvent); _ParkEvent   = NULL;
 384   ParkEvent::Release(_SleepEvent); _SleepEvent  = NULL;
 385   ParkEvent::Release(_MutexEvent); _MutexEvent  = NULL;
 386   ParkEvent::Release(_MuxEvent); _MuxEvent    = NULL;
 387 
 388   delete handle_area();
 389   delete metadata_handles();
 390 
 391   // SR_handler uses this as a termination indicator -
 392   // needs to happen before os::free_thread()
 393   delete _SR_lock;
 394   _SR_lock = NULL;
 395 
 396   // osthread() can be NULL, if creation of thread failed.
 397   if (osthread() != NULL) os::free_thread(osthread());
 398 
 399   // clear Thread::current if thread is deleting itself.
 400   // Needed to ensure JNI correctly detects non-attached threads.
 401   if (this == Thread::current()) {
 402     clear_thread_current();
 403   }
 404 
 405   CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
 406 }
 407 
 408 // NOTE: dummy function for assertion purpose.
 409 void Thread::run() {
 410   ShouldNotReachHere();
 411 }
 412 
 413 #ifdef ASSERT
 414 // A JavaThread is considered "dangling" if it is not the current
 415 // thread, has been added the Threads list, the system is not at a
 416 // safepoint and the Thread is not "protected".
 417 //
 418 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
 419   assert(!thread->is_Java_thread() || Thread::current() == thread ||
 420          !((JavaThread *) thread)->on_thread_list() ||
 421          SafepointSynchronize::is_at_safepoint() ||
 422          Threads::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
 423          "possibility of dangling Thread pointer");
 424 }
 425 #endif
 426 
 427 ThreadPriority Thread::get_priority(const Thread* const thread) {
 428   ThreadPriority priority;
 429   // Can return an error!
 430   (void)os::get_priority(thread, priority);
 431   assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
 432   return priority;
 433 }
 434 
 435 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
 436   debug_only(check_for_dangling_thread_pointer(thread);)
 437   // Can return an error!
 438   (void)os::set_priority(thread, priority);
 439 }
 440 
 441 
 442 void Thread::start(Thread* thread) {
 443   // Start is different from resume in that its safety is guaranteed by context or
 444   // being called from a Java method synchronized on the Thread object.
 445   if (!DisableStartThread) {
 446     if (thread->is_Java_thread()) {
 447       // Initialize the thread state to RUNNABLE before starting this thread.
 448       // Can not set it after the thread started because we do not know the
 449       // exact thread state at that time. It could be in MONITOR_WAIT or
 450       // in SLEEPING or some other state.
 451       java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
 452                                           java_lang_Thread::RUNNABLE);
 453     }
 454     os::start_thread(thread);
 455   }
 456 }
 457 
 458 // Enqueue a VM_Operation to do the job for us - sometime later
 459 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
 460   VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
 461   VMThread::execute(vm_stop);
 462 }
 463 
 464 
 465 // Check if an external suspend request has completed (or has been
 466 // cancelled). Returns true if the thread is externally suspended and
 467 // false otherwise.
 468 //
 469 // The bits parameter returns information about the code path through
 470 // the routine. Useful for debugging:
 471 //
 472 // set in is_ext_suspend_completed():
 473 // 0x00000001 - routine was entered
 474 // 0x00000010 - routine return false at end
 475 // 0x00000100 - thread exited (return false)
 476 // 0x00000200 - suspend request cancelled (return false)
 477 // 0x00000400 - thread suspended (return true)
 478 // 0x00001000 - thread is in a suspend equivalent state (return true)
 479 // 0x00002000 - thread is native and walkable (return true)
 480 // 0x00004000 - thread is native_trans and walkable (needed retry)
 481 //
 482 // set in wait_for_ext_suspend_completion():
 483 // 0x00010000 - routine was entered
 484 // 0x00020000 - suspend request cancelled before loop (return false)
 485 // 0x00040000 - thread suspended before loop (return true)
 486 // 0x00080000 - suspend request cancelled in loop (return false)
 487 // 0x00100000 - thread suspended in loop (return true)
 488 // 0x00200000 - suspend not completed during retry loop (return false)
 489 
 490 // Helper class for tracing suspend wait debug bits.
 491 //
 492 // 0x00000100 indicates that the target thread exited before it could
 493 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
 494 // 0x00080000 each indicate a cancelled suspend request so they don't
 495 // count as wait failures either.
 496 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
 497 
 498 class TraceSuspendDebugBits : public StackObj {
 499  private:
 500   JavaThread * jt;
 501   bool         is_wait;
 502   bool         called_by_wait;  // meaningful when !is_wait
 503   uint32_t *   bits;
 504 
 505  public:
 506   TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
 507                         uint32_t *_bits) {
 508     jt             = _jt;
 509     is_wait        = _is_wait;
 510     called_by_wait = _called_by_wait;
 511     bits           = _bits;
 512   }
 513 
 514   ~TraceSuspendDebugBits() {
 515     if (!is_wait) {
 516 #if 1
 517       // By default, don't trace bits for is_ext_suspend_completed() calls.
 518       // That trace is very chatty.
 519       return;
 520 #else
 521       if (!called_by_wait) {
 522         // If tracing for is_ext_suspend_completed() is enabled, then only
 523         // trace calls to it from wait_for_ext_suspend_completion()
 524         return;
 525       }
 526 #endif
 527     }
 528 
 529     if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
 530       if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
 531         MutexLocker ml(Threads_lock);  // needed for get_thread_name()
 532         ResourceMark rm;
 533 
 534         tty->print_cr(
 535                       "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
 536                       jt->get_thread_name(), *bits);
 537 
 538         guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
 539       }
 540     }
 541   }
 542 };
 543 #undef DEBUG_FALSE_BITS
 544 
 545 
 546 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
 547                                           uint32_t *bits) {
 548   TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
 549 
 550   bool did_trans_retry = false;  // only do thread_in_native_trans retry once
 551   bool do_trans_retry;           // flag to force the retry
 552 
 553   *bits |= 0x00000001;
 554 
 555   do {
 556     do_trans_retry = false;
 557 
 558     if (is_exiting()) {
 559       // Thread is in the process of exiting. This is always checked
 560       // first to reduce the risk of dereferencing a freed JavaThread.
 561       *bits |= 0x00000100;
 562       return false;
 563     }
 564 
 565     if (!is_external_suspend()) {
 566       // Suspend request is cancelled. This is always checked before
 567       // is_ext_suspended() to reduce the risk of a rogue resume
 568       // confusing the thread that made the suspend request.
 569       *bits |= 0x00000200;
 570       return false;
 571     }
 572 
 573     if (is_ext_suspended()) {
 574       // thread is suspended
 575       *bits |= 0x00000400;
 576       return true;
 577     }
 578 
 579     // Now that we no longer do hard suspends of threads running
 580     // native code, the target thread can be changing thread state
 581     // while we are in this routine:
 582     //
 583     //   _thread_in_native -> _thread_in_native_trans -> _thread_blocked
 584     //
 585     // We save a copy of the thread state as observed at this moment
 586     // and make our decision about suspend completeness based on the
 587     // copy. This closes the race where the thread state is seen as
 588     // _thread_in_native_trans in the if-thread_blocked check, but is
 589     // seen as _thread_blocked in if-thread_in_native_trans check.
 590     JavaThreadState save_state = thread_state();
 591 
 592     if (save_state == _thread_blocked && is_suspend_equivalent()) {
 593       // If the thread's state is _thread_blocked and this blocking
 594       // condition is known to be equivalent to a suspend, then we can
 595       // consider the thread to be externally suspended. This means that
 596       // the code that sets _thread_blocked has been modified to do
 597       // self-suspension if the blocking condition releases. We also
 598       // used to check for CONDVAR_WAIT here, but that is now covered by
 599       // the _thread_blocked with self-suspension check.
 600       //
 601       // Return true since we wouldn't be here unless there was still an
 602       // external suspend request.
 603       *bits |= 0x00001000;
 604       return true;
 605     } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
 606       // Threads running native code will self-suspend on native==>VM/Java
 607       // transitions. If its stack is walkable (should always be the case
 608       // unless this function is called before the actual java_suspend()
 609       // call), then the wait is done.
 610       *bits |= 0x00002000;
 611       return true;
 612     } else if (!called_by_wait && !did_trans_retry &&
 613                save_state == _thread_in_native_trans &&
 614                frame_anchor()->walkable()) {
 615       // The thread is transitioning from thread_in_native to another
 616       // thread state. check_safepoint_and_suspend_for_native_trans()
 617       // will force the thread to self-suspend. If it hasn't gotten
 618       // there yet we may have caught the thread in-between the native
 619       // code check above and the self-suspend. Lucky us. If we were
 620       // called by wait_for_ext_suspend_completion(), then it
 621       // will be doing the retries so we don't have to.
 622       //
 623       // Since we use the saved thread state in the if-statement above,
 624       // there is a chance that the thread has already transitioned to
 625       // _thread_blocked by the time we get here. In that case, we will
 626       // make a single unnecessary pass through the logic below. This
 627       // doesn't hurt anything since we still do the trans retry.
 628 
 629       *bits |= 0x00004000;
 630 
 631       // Once the thread leaves thread_in_native_trans for another
 632       // thread state, we break out of this retry loop. We shouldn't
 633       // need this flag to prevent us from getting back here, but
 634       // sometimes paranoia is good.
 635       did_trans_retry = true;
 636 
 637       // We wait for the thread to transition to a more usable state.
 638       for (int i = 1; i <= SuspendRetryCount; i++) {
 639         // We used to do an "os::yield_all(i)" call here with the intention
 640         // that yielding would increase on each retry. However, the parameter
 641         // is ignored on Linux which means the yield didn't scale up. Waiting
 642         // on the SR_lock below provides a much more predictable scale up for
 643         // the delay. It also provides a simple/direct point to check for any
 644         // safepoint requests from the VMThread
 645 
 646         // temporarily drops SR_lock while doing wait with safepoint check
 647         // (if we're a JavaThread - the WatcherThread can also call this)
 648         // and increase delay with each retry
 649         SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 650 
 651         // check the actual thread state instead of what we saved above
 652         if (thread_state() != _thread_in_native_trans) {
 653           // the thread has transitioned to another thread state so
 654           // try all the checks (except this one) one more time.
 655           do_trans_retry = true;
 656           break;
 657         }
 658       } // end retry loop
 659 
 660 
 661     }
 662   } while (do_trans_retry);
 663 
 664   *bits |= 0x00000010;
 665   return false;
 666 }
 667 
 668 // Wait for an external suspend request to complete (or be cancelled).
 669 // Returns true if the thread is externally suspended and false otherwise.
 670 //
 671 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
 672                                                  uint32_t *bits) {
 673   TraceSuspendDebugBits tsdb(this, true /* is_wait */,
 674                              false /* !called_by_wait */, bits);
 675 
 676   // local flag copies to minimize SR_lock hold time
 677   bool is_suspended;
 678   bool pending;
 679   uint32_t reset_bits;
 680 
 681   // set a marker so is_ext_suspend_completed() knows we are the caller
 682   *bits |= 0x00010000;
 683 
 684   // We use reset_bits to reinitialize the bits value at the top of
 685   // each retry loop. This allows the caller to make use of any
 686   // unused bits for their own marking purposes.
 687   reset_bits = *bits;
 688 
 689   {
 690     MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
 691     is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 692                                             delay, bits);
 693     pending = is_external_suspend();
 694   }
 695   // must release SR_lock to allow suspension to complete
 696 
 697   if (!pending) {
 698     // A cancelled suspend request is the only false return from
 699     // is_ext_suspend_completed() that keeps us from entering the
 700     // retry loop.
 701     *bits |= 0x00020000;
 702     return false;
 703   }
 704 
 705   if (is_suspended) {
 706     *bits |= 0x00040000;
 707     return true;
 708   }
 709 
 710   for (int i = 1; i <= retries; i++) {
 711     *bits = reset_bits;  // reinit to only track last retry
 712 
 713     // We used to do an "os::yield_all(i)" call here with the intention
 714     // that yielding would increase on each retry. However, the parameter
 715     // is ignored on Linux which means the yield didn't scale up. Waiting
 716     // on the SR_lock below provides a much more predictable scale up for
 717     // the delay. It also provides a simple/direct point to check for any
 718     // safepoint requests from the VMThread
 719 
 720     {
 721       MutexLocker ml(SR_lock());
 722       // wait with safepoint check (if we're a JavaThread - the WatcherThread
 723       // can also call this)  and increase delay with each retry
 724       SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 725 
 726       is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 727                                               delay, bits);
 728 
 729       // It is possible for the external suspend request to be cancelled
 730       // (by a resume) before the actual suspend operation is completed.
 731       // Refresh our local copy to see if we still need to wait.
 732       pending = is_external_suspend();
 733     }
 734 
 735     if (!pending) {
 736       // A cancelled suspend request is the only false return from
 737       // is_ext_suspend_completed() that keeps us from staying in the
 738       // retry loop.
 739       *bits |= 0x00080000;
 740       return false;
 741     }
 742 
 743     if (is_suspended) {
 744       *bits |= 0x00100000;
 745       return true;
 746     }
 747   } // end retry loop
 748 
 749   // thread did not suspend after all our retries
 750   *bits |= 0x00200000;
 751   return false;
 752 }
 753 
 754 // Called from API entry points which perform stack walking. If the
 755 // associated JavaThread is the current thread, then wait_for_suspend
 756 // is not used. Otherwise, it determines if we should wait for the
 757 // "other" thread to complete external suspension. (NOTE: in future
 758 // releases the suspension mechanism should be reimplemented so this
 759 // is not necessary.)
 760 //
 761 bool
 762 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
 763   if (this != JavaThread::current()) {
 764     // "other" threads require special handling.
 765     if (wait_for_suspend) {
 766       // We are allowed to wait for the external suspend to complete
 767       // so give the other thread a chance to get suspended.
 768       if (!wait_for_ext_suspend_completion(SuspendRetryCount,
 769                                            SuspendRetryDelay, bits)) {
 770         // Didn't make it so let the caller know.
 771         return false;
 772       }
 773     }
 774     // We aren't allowed to wait for the external suspend to complete
 775     // so if the other thread isn't externally suspended we need to
 776     // let the caller know.
 777     else if (!is_ext_suspend_completed_with_lock(bits)) {
 778       return false;
 779     }
 780   }
 781 
 782   return true;
 783 }
 784 
 785 #ifndef PRODUCT
 786 void JavaThread::record_jump(address target, address instr, const char* file,
 787                              int line) {
 788 
 789   // This should not need to be atomic as the only way for simultaneous
 790   // updates is via interrupts. Even then this should be rare or non-existent
 791   // and we don't care that much anyway.
 792 
 793   int index = _jmp_ring_index;
 794   _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
 795   _jmp_ring[index]._target = (intptr_t) target;
 796   _jmp_ring[index]._instruction = (intptr_t) instr;
 797   _jmp_ring[index]._file = file;
 798   _jmp_ring[index]._line = line;
 799 }
 800 #endif // PRODUCT
 801 
 802 void Thread::interrupt(Thread* thread) {
 803   debug_only(check_for_dangling_thread_pointer(thread);)
 804   os::interrupt(thread);
 805 }
 806 
 807 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
 808   debug_only(check_for_dangling_thread_pointer(thread);)
 809   // Note:  If clear_interrupted==false, this simply fetches and
 810   // returns the value of the field osthread()->interrupted().
 811   return os::is_interrupted(thread, clear_interrupted);
 812 }
 813 
 814 
 815 // GC Support
 816 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
 817   int thread_parity = _oops_do_parity;
 818   if (thread_parity != strong_roots_parity) {
 819     jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
 820     if (res == thread_parity) {
 821       return true;
 822     } else {
 823       guarantee(res == strong_roots_parity, "Or else what?");
 824       return false;
 825     }
 826   }
 827   return false;
 828 }
 829 
 830 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
 831   active_handles()->oops_do(f);
 832   // Do oop for ThreadShadow
 833   f->do_oop((oop*)&_pending_exception);
 834   handle_area()->oops_do(f);
 835 
 836   if (MonitorInUseLists) {
 837     // When using thread local monitor lists, we scan them here,
 838     // and the remaining global monitors in ObjectSynchronizer::oops_do().
 839     ObjectSynchronizer::thread_local_used_oops_do(this, f);
 840   }
 841 }
 842 
 843 void Thread::metadata_handles_do(void f(Metadata*)) {
 844   // Only walk the Handles in Thread.
 845   if (metadata_handles() != NULL) {
 846     for (int i = 0; i< metadata_handles()->length(); i++) {
 847       f(metadata_handles()->at(i));
 848     }
 849   }
 850 }
 851 
 852 void Thread::print_on(outputStream* st) const {
 853   // get_priority assumes osthread initialized
 854   if (osthread() != NULL) {
 855     int os_prio;
 856     if (os::get_native_priority(this, &os_prio) == OS_OK) {
 857       st->print("os_prio=%d ", os_prio);
 858     }
 859     st->print("tid=" INTPTR_FORMAT " ", p2i(this));
 860     ext().print_on(st);
 861     osthread()->print_on(st);
 862   }
 863   if (_threads_hazard_ptr != NULL) {
 864     st->print("_threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
 865   }
 866   if (_nested_threads_hazard_ptr != NULL) {
 867     print_nested_threads_hazard_ptrs_on(st);
 868   }
 869   st->print(" ");
 870   debug_only(if (WizardMode) print_owned_locks_on(st);)
 871 }
 872 
 873 void Thread::print_nested_threads_hazard_ptrs_on(outputStream* st) const {
 874   assert(_nested_threads_hazard_ptr != NULL, "must be set to print");
 875 
 876   if (EnableThreadSMRStatistics) {
 877     st->print(", _nested_threads_hazard_ptr_cnt=%u", _nested_threads_hazard_ptr_cnt);
 878   }
 879   st->print(", _nested_threads_hazard_ptrs=");
 880   for (NestedThreadsList* node = _nested_threads_hazard_ptr; node != NULL;
 881        node = node->next()) {
 882     if (node != _nested_threads_hazard_ptr) {
 883       // First node does not need a comma-space separator.
 884       st->print(", ");
 885     }
 886     st->print(INTPTR_FORMAT, p2i(node->t_list()));
 887   }
 888 }
 889 
 890 // Thread::print_on_error() is called by fatal error handler. Don't use
 891 // any lock or allocate memory.
 892 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
 893   assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
 894 
 895   if (is_VM_thread())                 { st->print("VMThread"); }
 896   else if (is_GC_task_thread())       { st->print("GCTaskThread"); }
 897   else if (is_Watcher_thread())       { st->print("WatcherThread"); }
 898   else if (is_ConcurrentGC_thread())  { st->print("ConcurrentGCThread"); }
 899   else                                { st->print("Thread"); }
 900 
 901   if (is_Named_thread()) {
 902     st->print(" \"%s\"", name());
 903   }
 904 
 905   st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
 906             p2i(stack_end()), p2i(stack_base()));
 907 
 908   if (osthread()) {
 909     st->print(" [id=%d]", osthread()->thread_id());
 910   }
 911 
 912   if (_threads_hazard_ptr != NULL) {
 913     st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
 914   }
 915   if (_nested_threads_hazard_ptr != NULL) {
 916     print_nested_threads_hazard_ptrs_on(st);
 917   }
 918 }
 919 
 920 void Thread::print_value_on(outputStream* st) const {
 921   if (is_Named_thread()) {
 922     st->print(" \"%s\" ", name());
 923   }
 924   st->print(INTPTR_FORMAT, p2i(this));   // print address
 925 }
 926 
 927 #ifdef ASSERT
 928 void Thread::print_owned_locks_on(outputStream* st) const {
 929   Monitor *cur = _owned_locks;
 930   if (cur == NULL) {
 931     st->print(" (no locks) ");
 932   } else {
 933     st->print_cr(" Locks owned:");
 934     while (cur) {
 935       cur->print_on(st);
 936       cur = cur->next();
 937     }
 938   }
 939 }
 940 
 941 static int ref_use_count  = 0;
 942 
 943 bool Thread::owns_locks_but_compiled_lock() const {
 944   for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 945     if (cur != Compile_lock) return true;
 946   }
 947   return false;
 948 }
 949 
 950 
 951 #endif
 952 
 953 #ifndef PRODUCT
 954 
 955 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially
 956 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
 957 // no threads which allow_vm_block's are held
 958 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
 959   // Check if current thread is allowed to block at a safepoint
 960   if (!(_allow_safepoint_count == 0)) {
 961     fatal("Possible safepoint reached by thread that does not allow it");
 962   }
 963   if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
 964     fatal("LEAF method calling lock?");
 965   }
 966 
 967 #ifdef ASSERT
 968   if (potential_vm_operation && is_Java_thread()
 969       && !Universe::is_bootstrapping()) {
 970     // Make sure we do not hold any locks that the VM thread also uses.
 971     // This could potentially lead to deadlocks
 972     for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 973       // Threads_lock is special, since the safepoint synchronization will not start before this is
 974       // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
 975       // since it is used to transfer control between JavaThreads and the VMThread
 976       // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
 977       if ((cur->allow_vm_block() &&
 978            cur != Threads_lock &&
 979            cur != Compile_lock &&               // Temporary: should not be necessary when we get separate compilation
 980            cur != VMOperationRequest_lock &&
 981            cur != VMOperationQueue_lock) ||
 982            cur->rank() == Mutex::special) {
 983         fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
 984       }
 985     }
 986   }
 987 
 988   if (GCALotAtAllSafepoints) {
 989     // We could enter a safepoint here and thus have a gc
 990     InterfaceSupport::check_gc_alot();
 991   }
 992 #endif
 993 }
 994 #endif
 995 
 996 bool Thread::is_in_stack(address adr) const {
 997   assert(Thread::current() == this, "is_in_stack can only be called from current thread");
 998   address end = os::current_stack_pointer();
 999   // Allow non Java threads to call this without stack_base
1000   if (_stack_base == NULL) return true;
1001   if (stack_base() >= adr && adr >= end) return true;
1002 
1003   return false;
1004 }
1005 
1006 bool Thread::is_in_usable_stack(address adr) const {
1007   size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1008   size_t usable_stack_size = _stack_size - stack_guard_size;
1009 
1010   return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1011 }
1012 
1013 
1014 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1015 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1016 // used for compilation in the future. If that change is made, the need for these methods
1017 // should be revisited, and they should be removed if possible.
1018 
1019 bool Thread::is_lock_owned(address adr) const {
1020   return on_local_stack(adr);
1021 }
1022 
1023 bool Thread::set_as_starting_thread() {
1024   // NOTE: this must be called inside the main thread.
1025   return os::create_main_thread((JavaThread*)this);
1026 }
1027 
1028 static void initialize_class(Symbol* class_name, TRAPS) {
1029   Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1030   InstanceKlass::cast(klass)->initialize(CHECK);
1031 }
1032 
1033 
1034 // Creates the initial ThreadGroup
1035 static Handle create_initial_thread_group(TRAPS) {
1036   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
1037   InstanceKlass* ik = InstanceKlass::cast(k);
1038 
1039   Handle system_instance = ik->allocate_instance_handle(CHECK_NH);
1040   {
1041     JavaValue result(T_VOID);
1042     JavaCalls::call_special(&result,
1043                             system_instance,
1044                             ik,
1045                             vmSymbols::object_initializer_name(),
1046                             vmSymbols::void_method_signature(),
1047                             CHECK_NH);
1048   }
1049   Universe::set_system_thread_group(system_instance());
1050 
1051   Handle main_instance = ik->allocate_instance_handle(CHECK_NH);
1052   {
1053     JavaValue result(T_VOID);
1054     Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1055     JavaCalls::call_special(&result,
1056                             main_instance,
1057                             ik,
1058                             vmSymbols::object_initializer_name(),
1059                             vmSymbols::threadgroup_string_void_signature(),
1060                             system_instance,
1061                             string,
1062                             CHECK_NH);
1063   }
1064   return main_instance;
1065 }
1066 
1067 // Creates the initial Thread
1068 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1069                                  TRAPS) {
1070   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
1071   InstanceKlass* ik = InstanceKlass::cast(k);
1072   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1073 
1074   java_lang_Thread::set_thread(thread_oop(), thread);
1075   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1076   thread->set_threadObj(thread_oop());
1077 
1078   Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1079 
1080   JavaValue result(T_VOID);
1081   JavaCalls::call_special(&result, thread_oop,
1082                           ik,
1083                           vmSymbols::object_initializer_name(),
1084                           vmSymbols::threadgroup_string_void_signature(),
1085                           thread_group,
1086                           string,
1087                           CHECK_NULL);
1088   return thread_oop();
1089 }
1090 
1091 char java_runtime_name[128] = "";
1092 char java_runtime_version[128] = "";
1093 
1094 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1095 static const char* get_java_runtime_name(TRAPS) {
1096   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1097                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1098   fieldDescriptor fd;
1099   bool found = k != NULL &&
1100                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1101                                                         vmSymbols::string_signature(), &fd);
1102   if (found) {
1103     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1104     if (name_oop == NULL) {
1105       return NULL;
1106     }
1107     const char* name = java_lang_String::as_utf8_string(name_oop,
1108                                                         java_runtime_name,
1109                                                         sizeof(java_runtime_name));
1110     return name;
1111   } else {
1112     return NULL;
1113   }
1114 }
1115 
1116 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1117 static const char* get_java_runtime_version(TRAPS) {
1118   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1119                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1120   fieldDescriptor fd;
1121   bool found = k != NULL &&
1122                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1123                                                         vmSymbols::string_signature(), &fd);
1124   if (found) {
1125     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1126     if (name_oop == NULL) {
1127       return NULL;
1128     }
1129     const char* name = java_lang_String::as_utf8_string(name_oop,
1130                                                         java_runtime_version,
1131                                                         sizeof(java_runtime_version));
1132     return name;
1133   } else {
1134     return NULL;
1135   }
1136 }
1137 
1138 // General purpose hook into Java code, run once when the VM is initialized.
1139 // The Java library method itself may be changed independently from the VM.
1140 static void call_postVMInitHook(TRAPS) {
1141   Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1142   if (klass != NULL) {
1143     JavaValue result(T_VOID);
1144     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1145                            vmSymbols::void_method_signature(),
1146                            CHECK);
1147   }
1148 }
1149 
1150 static void reset_vm_info_property(TRAPS) {
1151   // the vm info string
1152   ResourceMark rm(THREAD);
1153   const char *vm_info = VM_Version::vm_info_string();
1154 
1155   // java.lang.System class
1156   Klass* klass =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1157 
1158   // setProperty arguments
1159   Handle key_str    = java_lang_String::create_from_str("java.vm.info", CHECK);
1160   Handle value_str  = java_lang_String::create_from_str(vm_info, CHECK);
1161 
1162   // return value
1163   JavaValue r(T_OBJECT);
1164 
1165   // public static String setProperty(String key, String value);
1166   JavaCalls::call_static(&r,
1167                          klass,
1168                          vmSymbols::setProperty_name(),
1169                          vmSymbols::string_string_string_signature(),
1170                          key_str,
1171                          value_str,
1172                          CHECK);
1173 }
1174 
1175 
1176 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1177                                     bool daemon, TRAPS) {
1178   assert(thread_group.not_null(), "thread group should be specified");
1179   assert(threadObj() == NULL, "should only create Java thread object once");
1180 
1181   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1182   InstanceKlass* ik = InstanceKlass::cast(k);
1183   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1184 
1185   java_lang_Thread::set_thread(thread_oop(), this);
1186   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1187   set_threadObj(thread_oop());
1188 
1189   JavaValue result(T_VOID);
1190   if (thread_name != NULL) {
1191     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1192     // Thread gets assigned specified name and null target
1193     JavaCalls::call_special(&result,
1194                             thread_oop,
1195                             ik,
1196                             vmSymbols::object_initializer_name(),
1197                             vmSymbols::threadgroup_string_void_signature(),
1198                             thread_group, // Argument 1
1199                             name,         // Argument 2
1200                             THREAD);
1201   } else {
1202     // Thread gets assigned name "Thread-nnn" and null target
1203     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1204     JavaCalls::call_special(&result,
1205                             thread_oop,
1206                             ik,
1207                             vmSymbols::object_initializer_name(),
1208                             vmSymbols::threadgroup_runnable_void_signature(),
1209                             thread_group, // Argument 1
1210                             Handle(),     // Argument 2
1211                             THREAD);
1212   }
1213 
1214 
1215   if (daemon) {
1216     java_lang_Thread::set_daemon(thread_oop());
1217   }
1218 
1219   if (HAS_PENDING_EXCEPTION) {
1220     return;
1221   }
1222 
1223   Klass* group =  SystemDictionary::ThreadGroup_klass();
1224   Handle threadObj(THREAD, this->threadObj());
1225 
1226   JavaCalls::call_special(&result,
1227                           thread_group,
1228                           group,
1229                           vmSymbols::add_method_name(),
1230                           vmSymbols::thread_void_signature(),
1231                           threadObj,          // Arg 1
1232                           THREAD);
1233 }
1234 
1235 // NamedThread --  non-JavaThread subclasses with multiple
1236 // uniquely named instances should derive from this.
1237 NamedThread::NamedThread() : Thread() {
1238   _name = NULL;
1239   _processed_thread = NULL;
1240   _gc_id = GCId::undefined();
1241 }
1242 
1243 NamedThread::~NamedThread() {
1244   if (_name != NULL) {
1245     FREE_C_HEAP_ARRAY(char, _name);
1246     _name = NULL;
1247   }
1248 }
1249 
1250 void NamedThread::set_name(const char* format, ...) {
1251   guarantee(_name == NULL, "Only get to set name once.");
1252   _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1253   guarantee(_name != NULL, "alloc failure");
1254   va_list ap;
1255   va_start(ap, format);
1256   jio_vsnprintf(_name, max_name_len, format, ap);
1257   va_end(ap);
1258 }
1259 
1260 void NamedThread::initialize_named_thread() {
1261   set_native_thread_name(name());
1262 }
1263 
1264 void NamedThread::print_on(outputStream* st) const {
1265   st->print("\"%s\" ", name());
1266   Thread::print_on(st);
1267   st->cr();
1268 }
1269 
1270 
1271 // ======= WatcherThread ========
1272 
1273 // The watcher thread exists to simulate timer interrupts.  It should
1274 // be replaced by an abstraction over whatever native support for
1275 // timer interrupts exists on the platform.
1276 
1277 WatcherThread* WatcherThread::_watcher_thread   = NULL;
1278 bool WatcherThread::_startable = false;
1279 volatile bool  WatcherThread::_should_terminate = false;
1280 
1281 WatcherThread::WatcherThread() : Thread() {
1282   assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1283   if (os::create_thread(this, os::watcher_thread)) {
1284     _watcher_thread = this;
1285 
1286     // Set the watcher thread to the highest OS priority which should not be
1287     // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1288     // is created. The only normal thread using this priority is the reference
1289     // handler thread, which runs for very short intervals only.
1290     // If the VMThread's priority is not lower than the WatcherThread profiling
1291     // will be inaccurate.
1292     os::set_priority(this, MaxPriority);
1293     if (!DisableStartThread) {
1294       os::start_thread(this);
1295     }
1296   }
1297 }
1298 
1299 int WatcherThread::sleep() const {
1300   // The WatcherThread does not participate in the safepoint protocol
1301   // for the PeriodicTask_lock because it is not a JavaThread.
1302   MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1303 
1304   if (_should_terminate) {
1305     // check for termination before we do any housekeeping or wait
1306     return 0;  // we did not sleep.
1307   }
1308 
1309   // remaining will be zero if there are no tasks,
1310   // causing the WatcherThread to sleep until a task is
1311   // enrolled
1312   int remaining = PeriodicTask::time_to_wait();
1313   int time_slept = 0;
1314 
1315   // we expect this to timeout - we only ever get unparked when
1316   // we should terminate or when a new task has been enrolled
1317   OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1318 
1319   jlong time_before_loop = os::javaTimeNanos();
1320 
1321   while (true) {
1322     bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1323                                             remaining);
1324     jlong now = os::javaTimeNanos();
1325 
1326     if (remaining == 0) {
1327       // if we didn't have any tasks we could have waited for a long time
1328       // consider the time_slept zero and reset time_before_loop
1329       time_slept = 0;
1330       time_before_loop = now;
1331     } else {
1332       // need to recalculate since we might have new tasks in _tasks
1333       time_slept = (int) ((now - time_before_loop) / 1000000);
1334     }
1335 
1336     // Change to task list or spurious wakeup of some kind
1337     if (timedout || _should_terminate) {
1338       break;
1339     }
1340 
1341     remaining = PeriodicTask::time_to_wait();
1342     if (remaining == 0) {
1343       // Last task was just disenrolled so loop around and wait until
1344       // another task gets enrolled
1345       continue;
1346     }
1347 
1348     remaining -= time_slept;
1349     if (remaining <= 0) {
1350       break;
1351     }
1352   }
1353 
1354   return time_slept;
1355 }
1356 
1357 void WatcherThread::run() {
1358   assert(this == watcher_thread(), "just checking");
1359 
1360   this->record_stack_base_and_size();
1361   this->set_native_thread_name(this->name());
1362   this->set_active_handles(JNIHandleBlock::allocate_block());
1363   while (true) {
1364     assert(watcher_thread() == Thread::current(), "thread consistency check");
1365     assert(watcher_thread() == this, "thread consistency check");
1366 
1367     // Calculate how long it'll be until the next PeriodicTask work
1368     // should be done, and sleep that amount of time.
1369     int time_waited = sleep();
1370 
1371     if (VMError::is_error_reported()) {
1372       // A fatal error has happened, the error handler(VMError::report_and_die)
1373       // should abort JVM after creating an error log file. However in some
1374       // rare cases, the error handler itself might deadlock. Here periodically
1375       // check for error reporting timeouts, and if it happens, just proceed to
1376       // abort the VM.
1377 
1378       // This code is in WatcherThread because WatcherThread wakes up
1379       // periodically so the fatal error handler doesn't need to do anything;
1380       // also because the WatcherThread is less likely to crash than other
1381       // threads.
1382 
1383       for (;;) {
1384         // Note: we use naked sleep in this loop because we want to avoid using
1385         // any kind of VM infrastructure which may be broken at this point.
1386         if (VMError::check_timeout()) {
1387           // We hit error reporting timeout. Error reporting was interrupted and
1388           // will be wrapping things up now (closing files etc). Give it some more
1389           // time, then quit the VM.
1390           os::naked_short_sleep(200);
1391           // Print a message to stderr.
1392           fdStream err(defaultStream::output_fd());
1393           err.print_raw_cr("# [ timer expired, abort... ]");
1394           // skip atexit/vm_exit/vm_abort hooks
1395           os::die();
1396         }
1397 
1398         // Wait a second, then recheck for timeout.
1399         os::naked_short_sleep(999);
1400       }
1401     }
1402 
1403     if (_should_terminate) {
1404       // check for termination before posting the next tick
1405       break;
1406     }
1407 
1408     PeriodicTask::real_time_tick(time_waited);
1409   }
1410 
1411   // Signal that it is terminated
1412   {
1413     MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1414     _watcher_thread = NULL;
1415     Terminator_lock->notify();
1416   }
1417 }
1418 
1419 void WatcherThread::start() {
1420   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1421 
1422   if (watcher_thread() == NULL && _startable) {
1423     _should_terminate = false;
1424     // Create the single instance of WatcherThread
1425     new WatcherThread();
1426   }
1427 }
1428 
1429 void WatcherThread::make_startable() {
1430   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1431   _startable = true;
1432 }
1433 
1434 void WatcherThread::stop() {
1435   {
1436     // Follow normal safepoint aware lock enter protocol since the
1437     // WatcherThread is stopped by another JavaThread.
1438     MutexLocker ml(PeriodicTask_lock);
1439     _should_terminate = true;
1440 
1441     WatcherThread* watcher = watcher_thread();
1442     if (watcher != NULL) {
1443       // unpark the WatcherThread so it can see that it should terminate
1444       watcher->unpark();
1445     }
1446   }
1447 
1448   MutexLocker mu(Terminator_lock);
1449 
1450   while (watcher_thread() != NULL) {
1451     // This wait should make safepoint checks, wait without a timeout,
1452     // and wait as a suspend-equivalent condition.
1453     Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1454                           Mutex::_as_suspend_equivalent_flag);
1455   }
1456 }
1457 
1458 void WatcherThread::unpark() {
1459   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1460   PeriodicTask_lock->notify();
1461 }
1462 
1463 void WatcherThread::print_on(outputStream* st) const {
1464   st->print("\"%s\" ", name());
1465   Thread::print_on(st);
1466   st->cr();
1467 }
1468 
1469 // ======= JavaThread ========
1470 
1471 #if INCLUDE_JVMCI
1472 
1473 jlong* JavaThread::_jvmci_old_thread_counters;
1474 
1475 bool jvmci_counters_include(JavaThread* thread) {
1476   oop threadObj = thread->threadObj();
1477   return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1478 }
1479 
1480 void JavaThread::collect_counters(typeArrayOop array) {
1481   if (JVMCICounterSize > 0) {
1482     // dcubed - Looks like the Threads_lock is for stable access
1483     // to _jvmci_old_thread_counters and _jvmci_counters.
1484     MutexLocker tl(Threads_lock);
1485     JavaThreadIteratorWithHandle jtiwh;
1486     for (int i = 0; i < array->length(); i++) {
1487       array->long_at_put(i, _jvmci_old_thread_counters[i]);
1488     }
1489     for (; JavaThread *tp = jtiwh.next(); ) {
1490       if (jvmci_counters_include(tp)) {
1491         for (int i = 0; i < array->length(); i++) {
1492           array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1493         }
1494       }
1495     }
1496   }
1497 }
1498 
1499 #endif // INCLUDE_JVMCI
1500 
1501 // A JavaThread is a normal Java thread
1502 
1503 void JavaThread::initialize() {
1504   // Initialize fields
1505 
1506   set_saved_exception_pc(NULL);
1507   set_threadObj(NULL);
1508   _anchor.clear();
1509   set_entry_point(NULL);
1510   set_jni_functions(jni_functions());
1511   set_callee_target(NULL);
1512   set_vm_result(NULL);
1513   set_vm_result_2(NULL);
1514   set_vframe_array_head(NULL);
1515   set_vframe_array_last(NULL);
1516   set_deferred_locals(NULL);
1517   set_deopt_mark(NULL);
1518   set_deopt_compiled_method(NULL);
1519   clear_must_deopt_id();
1520   set_monitor_chunks(NULL);
1521   set_next(NULL);
1522   _on_thread_list = false;
1523   set_thread_state(_thread_new);
1524   _terminated = _not_terminated;
1525   _privileged_stack_top = NULL;
1526   _array_for_gc = NULL;
1527   _suspend_equivalent = false;
1528   _in_deopt_handler = 0;
1529   _doing_unsafe_access = false;
1530   _stack_guard_state = stack_guard_unused;
1531 #if INCLUDE_JVMCI
1532   _pending_monitorenter = false;
1533   _pending_deoptimization = -1;
1534   _pending_failed_speculation = NULL;
1535   _pending_transfer_to_interpreter = false;
1536   _adjusting_comp_level = false;
1537   _jvmci._alternate_call_target = NULL;
1538   assert(_jvmci._implicit_exception_pc == NULL, "must be");
1539   if (JVMCICounterSize > 0) {
1540     _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1541     memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1542   } else {
1543     _jvmci_counters = NULL;
1544   }
1545 #endif // INCLUDE_JVMCI
1546   _reserved_stack_activation = NULL;  // stack base not known yet
1547   (void)const_cast<oop&>(_exception_oop = oop(NULL));
1548   _exception_pc  = 0;
1549   _exception_handler_pc = 0;
1550   _is_method_handle_return = 0;
1551   _jvmti_thread_state= NULL;
1552   _should_post_on_exceptions_flag = JNI_FALSE;
1553   _jvmti_get_loaded_classes_closure = NULL;
1554   _interp_only_mode    = 0;
1555   _special_runtime_exit_condition = _no_async_condition;
1556   _pending_async_exception = NULL;
1557   _thread_stat = NULL;
1558   _thread_stat = new ThreadStatistics();
1559   _blocked_on_compilation = false;
1560   _jni_active_critical = 0;
1561   _pending_jni_exception_check_fn = NULL;
1562   _do_not_unlock_if_synchronized = false;
1563   _cached_monitor_info = NULL;
1564   _parker = Parker::Allocate(this);
1565 
1566 #ifndef PRODUCT
1567   _jmp_ring_index = 0;
1568   for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1569     record_jump(NULL, NULL, NULL, 0);
1570   }
1571 #endif // PRODUCT
1572 
1573   // Setup safepoint state info for this thread
1574   ThreadSafepointState::create(this);
1575 
1576   debug_only(_java_call_counter = 0);
1577 
1578   // JVMTI PopFrame support
1579   _popframe_condition = popframe_inactive;
1580   _popframe_preserved_args = NULL;
1581   _popframe_preserved_args_size = 0;
1582   _frames_to_pop_failed_realloc = 0;
1583 
1584   if (SafepointMechanism::uses_thread_local_poll()) {
1585     SafepointMechanism::initialize_header(this);
1586   }
1587 
1588   pd_initialize();
1589 }
1590 
1591 #if INCLUDE_ALL_GCS
1592 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1593 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1594 #endif // INCLUDE_ALL_GCS
1595 
1596 JavaThread::JavaThread(bool is_attaching_via_jni) :
1597                        Thread()
1598 #if INCLUDE_ALL_GCS
1599                        , _satb_mark_queue(&_satb_mark_queue_set),
1600                        _dirty_card_queue(&_dirty_card_queue_set)
1601 #endif // INCLUDE_ALL_GCS
1602 {
1603   initialize();
1604   if (is_attaching_via_jni) {
1605     _jni_attach_state = _attaching_via_jni;
1606   } else {
1607     _jni_attach_state = _not_attaching_via_jni;
1608   }
1609   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1610 }
1611 
1612 bool JavaThread::reguard_stack(address cur_sp) {
1613   if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1614       && _stack_guard_state != stack_guard_reserved_disabled) {
1615     return true; // Stack already guarded or guard pages not needed.
1616   }
1617 
1618   if (register_stack_overflow()) {
1619     // For those architectures which have separate register and
1620     // memory stacks, we must check the register stack to see if
1621     // it has overflowed.
1622     return false;
1623   }
1624 
1625   // Java code never executes within the yellow zone: the latter is only
1626   // there to provoke an exception during stack banging.  If java code
1627   // is executing there, either StackShadowPages should be larger, or
1628   // some exception code in c1, c2 or the interpreter isn't unwinding
1629   // when it should.
1630   guarantee(cur_sp > stack_reserved_zone_base(),
1631             "not enough space to reguard - increase StackShadowPages");
1632   if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1633     enable_stack_yellow_reserved_zone();
1634     if (reserved_stack_activation() != stack_base()) {
1635       set_reserved_stack_activation(stack_base());
1636     }
1637   } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1638     set_reserved_stack_activation(stack_base());
1639     enable_stack_reserved_zone();
1640   }
1641   return true;
1642 }
1643 
1644 bool JavaThread::reguard_stack(void) {
1645   return reguard_stack(os::current_stack_pointer());
1646 }
1647 
1648 
1649 void JavaThread::block_if_vm_exited() {
1650   if (_terminated == _vm_exited) {
1651     // _vm_exited is set at safepoint, and Threads_lock is never released
1652     // we will block here forever
1653     Threads_lock->lock_without_safepoint_check();
1654     ShouldNotReachHere();
1655   }
1656 }
1657 
1658 
1659 // Remove this ifdef when C1 is ported to the compiler interface.
1660 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1661 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1662 
1663 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1664                        Thread()
1665 #if INCLUDE_ALL_GCS
1666                        , _satb_mark_queue(&_satb_mark_queue_set),
1667                        _dirty_card_queue(&_dirty_card_queue_set)
1668 #endif // INCLUDE_ALL_GCS
1669 {
1670   initialize();
1671   _jni_attach_state = _not_attaching_via_jni;
1672   set_entry_point(entry_point);
1673   // Create the native thread itself.
1674   // %note runtime_23
1675   os::ThreadType thr_type = os::java_thread;
1676   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1677                                                      os::java_thread;
1678   os::create_thread(this, thr_type, stack_sz);
1679   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1680   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1681   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1682   // the exception consists of creating the exception object & initializing it, initialization
1683   // will leave the VM via a JavaCall and then all locks must be unlocked).
1684   //
1685   // The thread is still suspended when we reach here. Thread must be explicit started
1686   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1687   // by calling Threads:add. The reason why this is not done here, is because the thread
1688   // object must be fully initialized (take a look at JVM_Start)
1689 }
1690 
1691 JavaThread::~JavaThread() {
1692 
1693   // JSR166 -- return the parker to the free list
1694   Parker::Release(_parker);
1695   _parker = NULL;
1696 
1697   // Free any remaining  previous UnrollBlock
1698   vframeArray* old_array = vframe_array_last();
1699 
1700   if (old_array != NULL) {
1701     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1702     old_array->set_unroll_block(NULL);
1703     delete old_info;
1704     delete old_array;
1705   }
1706 
1707   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1708   if (deferred != NULL) {
1709     // This can only happen if thread is destroyed before deoptimization occurs.
1710     assert(deferred->length() != 0, "empty array!");
1711     do {
1712       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1713       deferred->remove_at(0);
1714       // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1715       delete dlv;
1716     } while (deferred->length() != 0);
1717     delete deferred;
1718   }
1719 
1720   // All Java related clean up happens in exit
1721   ThreadSafepointState::destroy(this);
1722   if (_thread_stat != NULL) delete _thread_stat;
1723 
1724 #if INCLUDE_JVMCI
1725   if (JVMCICounterSize > 0) {
1726     if (jvmci_counters_include(this)) {
1727       for (int i = 0; i < JVMCICounterSize; i++) {
1728         _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1729       }
1730     }
1731     FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1732   }
1733 #endif // INCLUDE_JVMCI
1734 }
1735 
1736 
1737 // The first routine called by a new Java thread
1738 void JavaThread::run() {
1739   // initialize thread-local alloc buffer related fields
1740   this->initialize_tlab();
1741 
1742   // used to test validity of stack trace backs
1743   this->record_base_of_stack_pointer();
1744 
1745   // Record real stack base and size.
1746   this->record_stack_base_and_size();
1747 
1748   this->create_stack_guard_pages();
1749 
1750   this->cache_global_variables();
1751 
1752   // Thread is now sufficient initialized to be handled by the safepoint code as being
1753   // in the VM. Change thread state from _thread_new to _thread_in_vm
1754   ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1755 
1756   assert(JavaThread::current() == this, "sanity check");
1757   assert(!Thread::current()->owns_locks(), "sanity check");
1758 
1759   DTRACE_THREAD_PROBE(start, this);
1760 
1761   // This operation might block. We call that after all safepoint checks for a new thread has
1762   // been completed.
1763   this->set_active_handles(JNIHandleBlock::allocate_block());
1764 
1765   if (JvmtiExport::should_post_thread_life()) {
1766     JvmtiExport::post_thread_start(this);
1767   }
1768 
1769   EventThreadStart event;
1770   if (event.should_commit()) {
1771     event.set_thread(THREAD_TRACE_ID(this));
1772     event.commit();
1773   }
1774 
1775   // We call another function to do the rest so we are sure that the stack addresses used
1776   // from there will be lower than the stack base just computed
1777   thread_main_inner();
1778 
1779   // Note, thread is no longer valid at this point!
1780 }
1781 
1782 
1783 void JavaThread::thread_main_inner() {
1784   assert(JavaThread::current() == this, "sanity check");
1785   assert(this->threadObj() != NULL, "just checking");
1786 
1787   // Execute thread entry point unless this thread has a pending exception
1788   // or has been stopped before starting.
1789   // Note: Due to JVM_StopThread we can have pending exceptions already!
1790   if (!this->has_pending_exception() &&
1791       !java_lang_Thread::is_stillborn(this->threadObj())) {
1792     {
1793       ResourceMark rm(this);
1794       this->set_native_thread_name(this->get_thread_name());
1795     }
1796     HandleMark hm(this);
1797     this->entry_point()(this, this);
1798   }
1799 
1800   DTRACE_THREAD_PROBE(stop, this);
1801 
1802   this->exit(false);
1803   this->smr_delete();
1804 }
1805 
1806 
1807 static void ensure_join(JavaThread* thread) {
1808   // We do not need to grab the Threads_lock, since we are operating on ourself.
1809   Handle threadObj(thread, thread->threadObj());
1810   assert(threadObj.not_null(), "java thread object must exist");
1811   ObjectLocker lock(threadObj, thread);
1812   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1813   thread->clear_pending_exception();
1814   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1815   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1816   // Clear the native thread instance - this makes isAlive return false and allows the join()
1817   // to complete once we've done the notify_all below
1818   java_lang_Thread::set_thread(threadObj(), NULL);
1819   lock.notify_all(thread);
1820   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1821   thread->clear_pending_exception();
1822 }
1823 
1824 
1825 // For any new cleanup additions, please check to see if they need to be applied to
1826 // cleanup_failed_attach_current_thread as well.
1827 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1828   assert(this == JavaThread::current(), "thread consistency check");
1829 
1830   elapsedTimer _timer_exit_phase1;
1831   elapsedTimer _timer_exit_phase2;
1832   elapsedTimer _timer_exit_phase3;
1833   elapsedTimer _timer_exit_phase4;
1834 
1835   if (log_is_enabled(Debug, os, thread, timer)) {
1836     _timer_exit_phase1.start();
1837   }
1838 
1839   HandleMark hm(this);
1840   Handle uncaught_exception(this, this->pending_exception());
1841   this->clear_pending_exception();
1842   Handle threadObj(this, this->threadObj());
1843   assert(threadObj.not_null(), "Java thread object should be created");
1844 
1845   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1846   {
1847     EXCEPTION_MARK;
1848 
1849     CLEAR_PENDING_EXCEPTION;
1850   }
1851   if (!destroy_vm) {
1852     if (uncaught_exception.not_null()) {
1853       EXCEPTION_MARK;
1854       // Call method Thread.dispatchUncaughtException().
1855       Klass* thread_klass = SystemDictionary::Thread_klass();
1856       JavaValue result(T_VOID);
1857       JavaCalls::call_virtual(&result,
1858                               threadObj, thread_klass,
1859                               vmSymbols::dispatchUncaughtException_name(),
1860                               vmSymbols::throwable_void_signature(),
1861                               uncaught_exception,
1862                               THREAD);
1863       if (HAS_PENDING_EXCEPTION) {
1864         ResourceMark rm(this);
1865         jio_fprintf(defaultStream::error_stream(),
1866                     "\nException: %s thrown from the UncaughtExceptionHandler"
1867                     " in thread \"%s\"\n",
1868                     pending_exception()->klass()->external_name(),
1869                     get_thread_name());
1870         CLEAR_PENDING_EXCEPTION;
1871       }
1872     }
1873 
1874     // Called before the java thread exit since we want to read info
1875     // from java_lang_Thread object
1876     EventThreadEnd event;
1877     if (event.should_commit()) {
1878       event.set_thread(THREAD_TRACE_ID(this));
1879       event.commit();
1880     }
1881 
1882     // Call after last event on thread
1883     EVENT_THREAD_EXIT(this);
1884 
1885     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1886     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1887     // is deprecated anyhow.
1888     if (!is_Compiler_thread()) {
1889       int count = 3;
1890       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1891         EXCEPTION_MARK;
1892         JavaValue result(T_VOID);
1893         Klass* thread_klass = SystemDictionary::Thread_klass();
1894         JavaCalls::call_virtual(&result,
1895                                 threadObj, thread_klass,
1896                                 vmSymbols::exit_method_name(),
1897                                 vmSymbols::void_method_signature(),
1898                                 THREAD);
1899         CLEAR_PENDING_EXCEPTION;
1900       }
1901     }
1902     // notify JVMTI
1903     if (JvmtiExport::should_post_thread_life()) {
1904       JvmtiExport::post_thread_end(this);
1905     }
1906 
1907     // We have notified the agents that we are exiting, before we go on,
1908     // we must check for a pending external suspend request and honor it
1909     // in order to not surprise the thread that made the suspend request.
1910     while (true) {
1911       {
1912         MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1913         if (!is_external_suspend()) {
1914           set_terminated(_thread_exiting);
1915           ThreadService::current_thread_exiting(this);
1916           break;
1917         }
1918         // Implied else:
1919         // Things get a little tricky here. We have a pending external
1920         // suspend request, but we are holding the SR_lock so we
1921         // can't just self-suspend. So we temporarily drop the lock
1922         // and then self-suspend.
1923       }
1924 
1925       ThreadBlockInVM tbivm(this);
1926       java_suspend_self();
1927 
1928       // We're done with this suspend request, but we have to loop around
1929       // and check again. Eventually we will get SR_lock without a pending
1930       // external suspend request and will be able to mark ourselves as
1931       // exiting.
1932     }
1933     // no more external suspends are allowed at this point
1934   } else {
1935     // before_exit() has already posted JVMTI THREAD_END events
1936   }
1937 
1938   if (log_is_enabled(Debug, os, thread, timer)) {
1939     _timer_exit_phase1.stop();
1940     _timer_exit_phase2.start();
1941   }
1942   // Notify waiters on thread object. This has to be done after exit() is called
1943   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1944   // group should have the destroyed bit set before waiters are notified).
1945   ensure_join(this);
1946   assert(!this->has_pending_exception(), "ensure_join should have cleared");
1947 
1948   if (log_is_enabled(Debug, os, thread, timer)) {
1949     _timer_exit_phase2.stop();
1950     _timer_exit_phase3.start();
1951   }
1952   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1953   // held by this thread must be released. The spec does not distinguish
1954   // between JNI-acquired and regular Java monitors. We can only see
1955   // regular Java monitors here if monitor enter-exit matching is broken.
1956   //
1957   // Optionally release any monitors for regular JavaThread exits. This
1958   // is provided as a work around for any bugs in monitor enter-exit
1959   // matching. This can be expensive so it is not enabled by default.
1960   //
1961   // ensure_join() ignores IllegalThreadStateExceptions, and so does
1962   // ObjectSynchronizer::release_monitors_owned_by_thread().
1963   if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1964     // Sanity check even though JNI DetachCurrentThread() would have
1965     // returned JNI_ERR if there was a Java frame. JavaThread exit
1966     // should be done executing Java code by the time we get here.
1967     assert(!this->has_last_Java_frame(),
1968            "should not have a Java frame when detaching or exiting");
1969     ObjectSynchronizer::release_monitors_owned_by_thread(this);
1970     assert(!this->has_pending_exception(), "release_monitors should have cleared");
1971   }
1972 
1973   // These things needs to be done while we are still a Java Thread. Make sure that thread
1974   // is in a consistent state, in case GC happens
1975   assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1976 
1977   if (active_handles() != NULL) {
1978     JNIHandleBlock* block = active_handles();
1979     set_active_handles(NULL);
1980     JNIHandleBlock::release_block(block);
1981   }
1982 
1983   if (free_handle_block() != NULL) {
1984     JNIHandleBlock* block = free_handle_block();
1985     set_free_handle_block(NULL);
1986     JNIHandleBlock::release_block(block);
1987   }
1988 
1989   // These have to be removed while this is still a valid thread.
1990   remove_stack_guard_pages();
1991 
1992   if (UseTLAB) {
1993     tlab().make_parsable(true);  // retire TLAB
1994   }
1995 
1996   if (JvmtiEnv::environments_might_exist()) {
1997     JvmtiExport::cleanup_thread(this);
1998   }
1999 
2000   // We must flush any deferred card marks before removing a thread from
2001   // the list of active threads.
2002   Universe::heap()->flush_deferred_store_barrier(this);
2003   assert(deferred_card_mark().is_empty(), "Should have been flushed");
2004 
2005 #if INCLUDE_ALL_GCS
2006   // We must flush the G1-related buffers before removing a thread
2007   // from the list of active threads. We must do this after any deferred
2008   // card marks have been flushed (above) so that any entries that are
2009   // added to the thread's dirty card queue as a result are not lost.
2010   if (UseG1GC) {
2011     flush_barrier_queues();
2012   }
2013 #endif // INCLUDE_ALL_GCS
2014 
2015   log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2016     exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2017     os::current_thread_id());
2018 
2019   if (log_is_enabled(Debug, os, thread, timer)) {
2020     _timer_exit_phase3.stop();
2021     _timer_exit_phase4.start();
2022   }
2023   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2024   Threads::remove(this);
2025 
2026   if (log_is_enabled(Debug, os, thread, timer)) {
2027     _timer_exit_phase4.stop();
2028     ResourceMark rm(this);
2029     log_debug(os, thread, timer)("name='%s'"
2030                                  ", exit-phase1=" JLONG_FORMAT
2031                                  ", exit-phase2=" JLONG_FORMAT
2032                                  ", exit-phase3=" JLONG_FORMAT
2033                                  ", exit-phase4=" JLONG_FORMAT,
2034                                  get_thread_name(),
2035                                  _timer_exit_phase1.milliseconds(),
2036                                  _timer_exit_phase2.milliseconds(),
2037                                  _timer_exit_phase3.milliseconds(),
2038                                  _timer_exit_phase4.milliseconds());
2039   }
2040 }
2041 
2042 #if INCLUDE_ALL_GCS
2043 // Flush G1-related queues.
2044 void JavaThread::flush_barrier_queues() {
2045   satb_mark_queue().flush();
2046   dirty_card_queue().flush();
2047 }
2048 
2049 void JavaThread::initialize_queues() {
2050   assert(!SafepointSynchronize::is_at_safepoint(),
2051          "we should not be at a safepoint");
2052 
2053   SATBMarkQueue& satb_queue = satb_mark_queue();
2054   SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
2055   // The SATB queue should have been constructed with its active
2056   // field set to false.
2057   assert(!satb_queue.is_active(), "SATB queue should not be active");
2058   assert(satb_queue.is_empty(), "SATB queue should be empty");
2059   // If we are creating the thread during a marking cycle, we should
2060   // set the active field of the SATB queue to true.
2061   if (satb_queue_set.is_active()) {
2062     satb_queue.set_active(true);
2063   }
2064 
2065   DirtyCardQueue& dirty_queue = dirty_card_queue();
2066   // The dirty card queue should have been constructed with its
2067   // active field set to true.
2068   assert(dirty_queue.is_active(), "dirty card queue should be active");
2069 }
2070 #endif // INCLUDE_ALL_GCS
2071 
2072 void JavaThread::cleanup_failed_attach_current_thread() {
2073   if (active_handles() != NULL) {
2074     JNIHandleBlock* block = active_handles();
2075     set_active_handles(NULL);
2076     JNIHandleBlock::release_block(block);
2077   }
2078 
2079   if (free_handle_block() != NULL) {
2080     JNIHandleBlock* block = free_handle_block();
2081     set_free_handle_block(NULL);
2082     JNIHandleBlock::release_block(block);
2083   }
2084 
2085   // These have to be removed while this is still a valid thread.
2086   remove_stack_guard_pages();
2087 
2088   if (UseTLAB) {
2089     tlab().make_parsable(true);  // retire TLAB, if any
2090   }
2091 
2092 #if INCLUDE_ALL_GCS
2093   if (UseG1GC) {
2094     flush_barrier_queues();
2095   }
2096 #endif // INCLUDE_ALL_GCS
2097 
2098   Threads::remove(this);
2099   this->smr_delete();
2100 }
2101 
2102 
2103 
2104 
2105 JavaThread* JavaThread::active() {
2106   Thread* thread = Thread::current();
2107   if (thread->is_Java_thread()) {
2108     return (JavaThread*) thread;
2109   } else {
2110     assert(thread->is_VM_thread(), "this must be a vm thread");
2111     VM_Operation* op = ((VMThread*) thread)->vm_operation();
2112     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2113     assert(ret->is_Java_thread(), "must be a Java thread");
2114     return ret;
2115   }
2116 }
2117 
2118 bool JavaThread::is_lock_owned(address adr) const {
2119   if (Thread::is_lock_owned(adr)) return true;
2120 
2121   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2122     if (chunk->contains(adr)) return true;
2123   }
2124 
2125   return false;
2126 }
2127 
2128 
2129 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2130   chunk->set_next(monitor_chunks());
2131   set_monitor_chunks(chunk);
2132 }
2133 
2134 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2135   guarantee(monitor_chunks() != NULL, "must be non empty");
2136   if (monitor_chunks() == chunk) {
2137     set_monitor_chunks(chunk->next());
2138   } else {
2139     MonitorChunk* prev = monitor_chunks();
2140     while (prev->next() != chunk) prev = prev->next();
2141     prev->set_next(chunk->next());
2142   }
2143 }
2144 
2145 // JVM support.
2146 
2147 // Note: this function shouldn't block if it's called in
2148 // _thread_in_native_trans state (such as from
2149 // check_special_condition_for_native_trans()).
2150 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2151 
2152   if (has_last_Java_frame() && has_async_condition()) {
2153     // If we are at a polling page safepoint (not a poll return)
2154     // then we must defer async exception because live registers
2155     // will be clobbered by the exception path. Poll return is
2156     // ok because the call we a returning from already collides
2157     // with exception handling registers and so there is no issue.
2158     // (The exception handling path kills call result registers but
2159     //  this is ok since the exception kills the result anyway).
2160 
2161     if (is_at_poll_safepoint()) {
2162       // if the code we are returning to has deoptimized we must defer
2163       // the exception otherwise live registers get clobbered on the
2164       // exception path before deoptimization is able to retrieve them.
2165       //
2166       RegisterMap map(this, false);
2167       frame caller_fr = last_frame().sender(&map);
2168       assert(caller_fr.is_compiled_frame(), "what?");
2169       if (caller_fr.is_deoptimized_frame()) {
2170         log_info(exceptions)("deferred async exception at compiled safepoint");
2171         return;
2172       }
2173     }
2174   }
2175 
2176   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2177   if (condition == _no_async_condition) {
2178     // Conditions have changed since has_special_runtime_exit_condition()
2179     // was called:
2180     // - if we were here only because of an external suspend request,
2181     //   then that was taken care of above (or cancelled) so we are done
2182     // - if we were here because of another async request, then it has
2183     //   been cleared between the has_special_runtime_exit_condition()
2184     //   and now so again we are done
2185     return;
2186   }
2187 
2188   // Check for pending async. exception
2189   if (_pending_async_exception != NULL) {
2190     // Only overwrite an already pending exception, if it is not a threadDeath.
2191     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2192 
2193       // We cannot call Exceptions::_throw(...) here because we cannot block
2194       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2195 
2196       LogTarget(Info, exceptions) lt;
2197       if (lt.is_enabled()) {
2198         ResourceMark rm;
2199         LogStream ls(lt);
2200         ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2201           if (has_last_Java_frame()) {
2202             frame f = last_frame();
2203            ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2204           }
2205         ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2206       }
2207       _pending_async_exception = NULL;
2208       clear_has_async_exception();
2209     }
2210   }
2211 
2212   if (check_unsafe_error &&
2213       condition == _async_unsafe_access_error && !has_pending_exception()) {
2214     condition = _no_async_condition;  // done
2215     switch (thread_state()) {
2216     case _thread_in_vm: {
2217       JavaThread* THREAD = this;
2218       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2219     }
2220     case _thread_in_native: {
2221       ThreadInVMfromNative tiv(this);
2222       JavaThread* THREAD = this;
2223       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2224     }
2225     case _thread_in_Java: {
2226       ThreadInVMfromJava tiv(this);
2227       JavaThread* THREAD = this;
2228       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2229     }
2230     default:
2231       ShouldNotReachHere();
2232     }
2233   }
2234 
2235   assert(condition == _no_async_condition || has_pending_exception() ||
2236          (!check_unsafe_error && condition == _async_unsafe_access_error),
2237          "must have handled the async condition, if no exception");
2238 }
2239 
2240 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2241   //
2242   // Check for pending external suspend. Internal suspend requests do
2243   // not use handle_special_runtime_exit_condition().
2244   // If JNIEnv proxies are allowed, don't self-suspend if the target
2245   // thread is not the current thread. In older versions of jdbx, jdbx
2246   // threads could call into the VM with another thread's JNIEnv so we
2247   // can be here operating on behalf of a suspended thread (4432884).
2248   bool do_self_suspend = is_external_suspend_with_lock();
2249   if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2250     //
2251     // Because thread is external suspended the safepoint code will count
2252     // thread as at a safepoint. This can be odd because we can be here
2253     // as _thread_in_Java which would normally transition to _thread_blocked
2254     // at a safepoint. We would like to mark the thread as _thread_blocked
2255     // before calling java_suspend_self like all other callers of it but
2256     // we must then observe proper safepoint protocol. (We can't leave
2257     // _thread_blocked with a safepoint in progress). However we can be
2258     // here as _thread_in_native_trans so we can't use a normal transition
2259     // constructor/destructor pair because they assert on that type of
2260     // transition. We could do something like:
2261     //
2262     // JavaThreadState state = thread_state();
2263     // set_thread_state(_thread_in_vm);
2264     // {
2265     //   ThreadBlockInVM tbivm(this);
2266     //   java_suspend_self()
2267     // }
2268     // set_thread_state(_thread_in_vm_trans);
2269     // if (safepoint) block;
2270     // set_thread_state(state);
2271     //
2272     // but that is pretty messy. Instead we just go with the way the
2273     // code has worked before and note that this is the only path to
2274     // java_suspend_self that doesn't put the thread in _thread_blocked
2275     // mode.
2276 
2277     frame_anchor()->make_walkable(this);
2278     java_suspend_self();
2279 
2280     // We might be here for reasons in addition to the self-suspend request
2281     // so check for other async requests.
2282   }
2283 
2284   if (check_asyncs) {
2285     check_and_handle_async_exceptions();
2286   }
2287 #if INCLUDE_TRACE
2288   if (is_trace_suspend()) {
2289     TRACE_SUSPEND_THREAD(this);
2290   }
2291 #endif
2292 }
2293 
2294 void JavaThread::send_thread_stop(oop java_throwable)  {
2295   assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2296   assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2297   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2298 
2299   // Do not throw asynchronous exceptions against the compiler thread
2300   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2301   if (!can_call_java()) return;
2302 
2303   {
2304     // Actually throw the Throwable against the target Thread - however
2305     // only if there is no thread death exception installed already.
2306     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2307       // If the topmost frame is a runtime stub, then we are calling into
2308       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2309       // must deoptimize the caller before continuing, as the compiled  exception handler table
2310       // may not be valid
2311       if (has_last_Java_frame()) {
2312         frame f = last_frame();
2313         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2314           // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2315           RegisterMap reg_map(this, UseBiasedLocking);
2316           frame compiled_frame = f.sender(&reg_map);
2317           if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2318             Deoptimization::deoptimize(this, compiled_frame, &reg_map);
2319           }
2320         }
2321       }
2322 
2323       // Set async. pending exception in thread.
2324       set_pending_async_exception(java_throwable);
2325 
2326       if (log_is_enabled(Info, exceptions)) {
2327          ResourceMark rm;
2328         log_info(exceptions)("Pending Async. exception installed of type: %s",
2329                              InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2330       }
2331       // for AbortVMOnException flag
2332       Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2333     }
2334   }
2335 
2336 
2337   // Interrupt thread so it will wake up from a potential wait()
2338   Thread::interrupt(this);
2339 }
2340 
2341 // External suspension mechanism.
2342 //
2343 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2344 // to any VM_locks and it is at a transition
2345 // Self-suspension will happen on the transition out of the vm.
2346 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2347 //
2348 // Guarantees on return:
2349 //   + Target thread will not execute any new bytecode (that's why we need to
2350 //     force a safepoint)
2351 //   + Target thread will not enter any new monitors
2352 //
2353 void JavaThread::java_suspend() {
2354   ThreadsListHandle tlh;
2355   if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2356     return;
2357   }

2358 
2359   { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2360     if (!is_external_suspend()) {
2361       // a racing resume has cancelled us; bail out now
2362       return;
2363     }
2364 
2365     // suspend is done
2366     uint32_t debug_bits = 0;
2367     // Warning: is_ext_suspend_completed() may temporarily drop the
2368     // SR_lock to allow the thread to reach a stable thread state if
2369     // it is currently in a transient thread state.
2370     if (is_ext_suspend_completed(false /* !called_by_wait */,
2371                                  SuspendRetryDelay, &debug_bits)) {
2372       return;
2373     }
2374   }
2375 
2376   VM_ThreadSuspend vm_suspend;
2377   VMThread::execute(&vm_suspend);
2378 }
2379 
2380 // Part II of external suspension.
2381 // A JavaThread self suspends when it detects a pending external suspend
2382 // request. This is usually on transitions. It is also done in places
2383 // where continuing to the next transition would surprise the caller,
2384 // e.g., monitor entry.
2385 //
2386 // Returns the number of times that the thread self-suspended.
2387 //
2388 // Note: DO NOT call java_suspend_self() when you just want to block current
2389 //       thread. java_suspend_self() is the second stage of cooperative
2390 //       suspension for external suspend requests and should only be used
2391 //       to complete an external suspend request.
2392 //
2393 int JavaThread::java_suspend_self() {
2394   int ret = 0;
2395 
2396   // we are in the process of exiting so don't suspend
2397   if (is_exiting()) {
2398     clear_external_suspend();
2399     return ret;
2400   }
2401 
2402   assert(_anchor.walkable() ||
2403          (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2404          "must have walkable stack");
2405 
2406   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2407 
2408   assert(!this->is_ext_suspended(),
2409          "a thread trying to self-suspend should not already be suspended");
2410 
2411   if (this->is_suspend_equivalent()) {
2412     // If we are self-suspending as a result of the lifting of a
2413     // suspend equivalent condition, then the suspend_equivalent
2414     // flag is not cleared until we set the ext_suspended flag so
2415     // that wait_for_ext_suspend_completion() returns consistent
2416     // results.
2417     this->clear_suspend_equivalent();
2418   }
2419 
2420   // A racing resume may have cancelled us before we grabbed SR_lock
2421   // above. Or another external suspend request could be waiting for us
2422   // by the time we return from SR_lock()->wait(). The thread
2423   // that requested the suspension may already be trying to walk our
2424   // stack and if we return now, we can change the stack out from under
2425   // it. This would be a "bad thing (TM)" and cause the stack walker
2426   // to crash. We stay self-suspended until there are no more pending
2427   // external suspend requests.
2428   while (is_external_suspend()) {
2429     ret++;
2430     this->set_ext_suspended();
2431 
2432     // _ext_suspended flag is cleared by java_resume()
2433     while (is_ext_suspended()) {
2434       this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2435     }
2436   }
2437 
2438   return ret;
2439 }
2440 
2441 #ifdef ASSERT
2442 // verify the JavaThread has not yet been published in the Threads::list, and
2443 // hence doesn't need protection from concurrent access at this stage
2444 void JavaThread::verify_not_published() {
2445   ThreadsListHandle tlh;
2446   assert(!tlh.includes(this), "JavaThread shouldn't have been published yet!");






2447 }
2448 #endif
2449 
2450 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2451 // progress or when _suspend_flags is non-zero.
2452 // Current thread needs to self-suspend if there is a suspend request and/or
2453 // block if a safepoint is in progress.
2454 // Async exception ISN'T checked.
2455 // Note only the ThreadInVMfromNative transition can call this function
2456 // directly and when thread state is _thread_in_native_trans
2457 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2458   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2459 
2460   JavaThread *curJT = JavaThread::current();
2461   bool do_self_suspend = thread->is_external_suspend();
2462 
2463   assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2464 
2465   // If JNIEnv proxies are allowed, don't self-suspend if the target
2466   // thread is not the current thread. In older versions of jdbx, jdbx
2467   // threads could call into the VM with another thread's JNIEnv so we
2468   // can be here operating on behalf of a suspended thread (4432884).
2469   if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2470     JavaThreadState state = thread->thread_state();
2471 
2472     // We mark this thread_blocked state as a suspend-equivalent so
2473     // that a caller to is_ext_suspend_completed() won't be confused.
2474     // The suspend-equivalent state is cleared by java_suspend_self().
2475     thread->set_suspend_equivalent();
2476 
2477     // If the safepoint code sees the _thread_in_native_trans state, it will
2478     // wait until the thread changes to other thread state. There is no
2479     // guarantee on how soon we can obtain the SR_lock and complete the
2480     // self-suspend request. It would be a bad idea to let safepoint wait for
2481     // too long. Temporarily change the state to _thread_blocked to
2482     // let the VM thread know that this thread is ready for GC. The problem
2483     // of changing thread state is that safepoint could happen just after
2484     // java_suspend_self() returns after being resumed, and VM thread will
2485     // see the _thread_blocked state. We must check for safepoint
2486     // after restoring the state and make sure we won't leave while a safepoint
2487     // is in progress.
2488     thread->set_thread_state(_thread_blocked);
2489     thread->java_suspend_self();
2490     thread->set_thread_state(state);
2491 
2492     InterfaceSupport::serialize_thread_state_with_handler(thread);
2493   }
2494 
2495   SafepointMechanism::block_if_requested(curJT);
2496 
2497   if (thread->is_deopt_suspend()) {
2498     thread->clear_deopt_suspend();
2499     RegisterMap map(thread, false);
2500     frame f = thread->last_frame();
2501     while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2502       f = f.sender(&map);
2503     }
2504     if (f.id() == thread->must_deopt_id()) {
2505       thread->clear_must_deopt_id();
2506       f.deoptimize(thread);
2507     } else {
2508       fatal("missed deoptimization!");
2509     }
2510   }
2511 #if INCLUDE_TRACE
2512   if (thread->is_trace_suspend()) {
2513     TRACE_SUSPEND_THREAD(thread);
2514   }
2515 #endif
2516 }
2517 
2518 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2519 // progress or when _suspend_flags is non-zero.
2520 // Current thread needs to self-suspend if there is a suspend request and/or
2521 // block if a safepoint is in progress.
2522 // Also check for pending async exception (not including unsafe access error).
2523 // Note only the native==>VM/Java barriers can call this function and when
2524 // thread state is _thread_in_native_trans.
2525 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2526   check_safepoint_and_suspend_for_native_trans(thread);
2527 
2528   if (thread->has_async_exception()) {
2529     // We are in _thread_in_native_trans state, don't handle unsafe
2530     // access error since that may block.
2531     thread->check_and_handle_async_exceptions(false);
2532   }
2533 }
2534 
2535 // This is a variant of the normal
2536 // check_special_condition_for_native_trans with slightly different
2537 // semantics for use by critical native wrappers.  It does all the
2538 // normal checks but also performs the transition back into
2539 // thread_in_Java state.  This is required so that critical natives
2540 // can potentially block and perform a GC if they are the last thread
2541 // exiting the GCLocker.
2542 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2543   check_special_condition_for_native_trans(thread);
2544 
2545   // Finish the transition
2546   thread->set_thread_state(_thread_in_Java);
2547 
2548   if (thread->do_critical_native_unlock()) {
2549     ThreadInVMfromJavaNoAsyncException tiv(thread);
2550     GCLocker::unlock_critical(thread);
2551     thread->clear_critical_native_unlock();
2552   }
2553 }
2554 
2555 // We need to guarantee the Threads_lock here, since resumes are not
2556 // allowed during safepoint synchronization
2557 // Can only resume from an external suspension
2558 void JavaThread::java_resume() {
2559   assert_locked_or_safepoint(Threads_lock);
2560 
2561   // Sanity check: thread is gone, has started exiting or the thread
2562   // was not externally suspended.
2563   ThreadsListHandle tlh;
2564   if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2565     return;
2566   }
2567 
2568   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2569 
2570   clear_external_suspend();
2571 
2572   if (is_ext_suspended()) {
2573     clear_ext_suspended();
2574     SR_lock()->notify_all();
2575   }
2576 }
2577 
2578 size_t JavaThread::_stack_red_zone_size = 0;
2579 size_t JavaThread::_stack_yellow_zone_size = 0;
2580 size_t JavaThread::_stack_reserved_zone_size = 0;
2581 size_t JavaThread::_stack_shadow_zone_size = 0;
2582 
2583 void JavaThread::create_stack_guard_pages() {
2584   if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; }
2585   address low_addr = stack_end();
2586   size_t len = stack_guard_zone_size();
2587 
2588   assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2589   assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2590 
2591   int must_commit = os::must_commit_stack_guard_pages();
2592   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2593 
2594   if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2595     log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2596     return;
2597   }
2598 
2599   if (os::guard_memory((char *) low_addr, len)) {
2600     _stack_guard_state = stack_guard_enabled;
2601   } else {
2602     log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2603       PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2604     if (os::uncommit_memory((char *) low_addr, len)) {
2605       log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2606     }
2607     return;
2608   }
2609 
2610   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2611     PTR_FORMAT "-" PTR_FORMAT ".",
2612     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2613 }
2614 
2615 void JavaThread::remove_stack_guard_pages() {
2616   assert(Thread::current() == this, "from different thread");
2617   if (_stack_guard_state == stack_guard_unused) return;
2618   address low_addr = stack_end();
2619   size_t len = stack_guard_zone_size();
2620 
2621   if (os::must_commit_stack_guard_pages()) {
2622     if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2623       _stack_guard_state = stack_guard_unused;
2624     } else {
2625       log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2626         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2627       return;
2628     }
2629   } else {
2630     if (_stack_guard_state == stack_guard_unused) return;
2631     if (os::unguard_memory((char *) low_addr, len)) {
2632       _stack_guard_state = stack_guard_unused;
2633     } else {
2634       log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2635         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2636       return;
2637     }
2638   }
2639 
2640   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2641     PTR_FORMAT "-" PTR_FORMAT ".",
2642     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2643 }
2644 
2645 void JavaThread::enable_stack_reserved_zone() {
2646   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2647   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2648 
2649   // The base notation is from the stack's point of view, growing downward.
2650   // We need to adjust it to work correctly with guard_memory()
2651   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2652 
2653   guarantee(base < stack_base(),"Error calculating stack reserved zone");
2654   guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2655 
2656   if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2657     _stack_guard_state = stack_guard_enabled;
2658   } else {
2659     warning("Attempt to guard stack reserved zone failed.");
2660   }
2661   enable_register_stack_guard();
2662 }
2663 
2664 void JavaThread::disable_stack_reserved_zone() {
2665   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2666   assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2667 
2668   // Simply return if called for a thread that does not use guard pages.
2669   if (_stack_guard_state == stack_guard_unused) return;
2670 
2671   // The base notation is from the stack's point of view, growing downward.
2672   // We need to adjust it to work correctly with guard_memory()
2673   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2674 
2675   if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2676     _stack_guard_state = stack_guard_reserved_disabled;
2677   } else {
2678     warning("Attempt to unguard stack reserved zone failed.");
2679   }
2680   disable_register_stack_guard();
2681 }
2682 
2683 void JavaThread::enable_stack_yellow_reserved_zone() {
2684   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2685   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2686 
2687   // The base notation is from the stacks point of view, growing downward.
2688   // We need to adjust it to work correctly with guard_memory()
2689   address base = stack_red_zone_base();
2690 
2691   guarantee(base < stack_base(), "Error calculating stack yellow zone");
2692   guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2693 
2694   if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2695     _stack_guard_state = stack_guard_enabled;
2696   } else {
2697     warning("Attempt to guard stack yellow zone failed.");
2698   }
2699   enable_register_stack_guard();
2700 }
2701 
2702 void JavaThread::disable_stack_yellow_reserved_zone() {
2703   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2704   assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2705 
2706   // Simply return if called for a thread that does not use guard pages.
2707   if (_stack_guard_state == stack_guard_unused) return;
2708 
2709   // The base notation is from the stacks point of view, growing downward.
2710   // We need to adjust it to work correctly with guard_memory()
2711   address base = stack_red_zone_base();
2712 
2713   if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2714     _stack_guard_state = stack_guard_yellow_reserved_disabled;
2715   } else {
2716     warning("Attempt to unguard stack yellow zone failed.");
2717   }
2718   disable_register_stack_guard();
2719 }
2720 
2721 void JavaThread::enable_stack_red_zone() {
2722   // The base notation is from the stacks point of view, growing downward.
2723   // We need to adjust it to work correctly with guard_memory()
2724   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2725   address base = stack_red_zone_base() - stack_red_zone_size();
2726 
2727   guarantee(base < stack_base(), "Error calculating stack red zone");
2728   guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2729 
2730   if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2731     warning("Attempt to guard stack red zone failed.");
2732   }
2733 }
2734 
2735 void JavaThread::disable_stack_red_zone() {
2736   // The base notation is from the stacks point of view, growing downward.
2737   // We need to adjust it to work correctly with guard_memory()
2738   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2739   address base = stack_red_zone_base() - stack_red_zone_size();
2740   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2741     warning("Attempt to unguard stack red zone failed.");
2742   }
2743 }
2744 
2745 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2746   // ignore is there is no stack
2747   if (!has_last_Java_frame()) return;
2748   // traverse the stack frames. Starts from top frame.
2749   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2750     frame* fr = fst.current();
2751     f(fr, fst.register_map());
2752   }
2753 }
2754 
2755 
2756 #ifndef PRODUCT
2757 // Deoptimization
2758 // Function for testing deoptimization
2759 void JavaThread::deoptimize() {
2760   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2761   StackFrameStream fst(this, UseBiasedLocking);
2762   bool deopt = false;           // Dump stack only if a deopt actually happens.
2763   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2764   // Iterate over all frames in the thread and deoptimize
2765   for (; !fst.is_done(); fst.next()) {
2766     if (fst.current()->can_be_deoptimized()) {
2767 
2768       if (only_at) {
2769         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
2770         // consists of comma or carriage return separated numbers so
2771         // search for the current bci in that string.
2772         address pc = fst.current()->pc();
2773         nmethod* nm =  (nmethod*) fst.current()->cb();
2774         ScopeDesc* sd = nm->scope_desc_at(pc);
2775         char buffer[8];
2776         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2777         size_t len = strlen(buffer);
2778         const char * found = strstr(DeoptimizeOnlyAt, buffer);
2779         while (found != NULL) {
2780           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2781               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2782             // Check that the bci found is bracketed by terminators.
2783             break;
2784           }
2785           found = strstr(found + 1, buffer);
2786         }
2787         if (!found) {
2788           continue;
2789         }
2790       }
2791 
2792       if (DebugDeoptimization && !deopt) {
2793         deopt = true; // One-time only print before deopt
2794         tty->print_cr("[BEFORE Deoptimization]");
2795         trace_frames();
2796         trace_stack();
2797       }
2798       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2799     }
2800   }
2801 
2802   if (DebugDeoptimization && deopt) {
2803     tty->print_cr("[AFTER Deoptimization]");
2804     trace_frames();
2805   }
2806 }
2807 
2808 
2809 // Make zombies
2810 void JavaThread::make_zombies() {
2811   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2812     if (fst.current()->can_be_deoptimized()) {
2813       // it is a Java nmethod
2814       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2815       nm->make_not_entrant();
2816     }
2817   }
2818 }
2819 #endif // PRODUCT
2820 
2821 
2822 void JavaThread::deoptimized_wrt_marked_nmethods() {
2823   if (!has_last_Java_frame()) return;
2824   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2825   StackFrameStream fst(this, UseBiasedLocking);
2826   for (; !fst.is_done(); fst.next()) {
2827     if (fst.current()->should_be_deoptimized()) {
2828       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2829     }
2830   }
2831 }
2832 
2833 
2834 // If the caller is a NamedThread, then remember, in the current scope,
2835 // the given JavaThread in its _processed_thread field.
2836 class RememberProcessedThread: public StackObj {
2837   NamedThread* _cur_thr;
2838  public:
2839   RememberProcessedThread(JavaThread* jthr) {
2840     Thread* thread = Thread::current();
2841     if (thread->is_Named_thread()) {
2842       _cur_thr = (NamedThread *)thread;
2843       _cur_thr->set_processed_thread(jthr);
2844     } else {
2845       _cur_thr = NULL;
2846     }
2847   }
2848 
2849   ~RememberProcessedThread() {
2850     if (_cur_thr) {
2851       _cur_thr->set_processed_thread(NULL);
2852     }
2853   }
2854 };
2855 
2856 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2857   // Verify that the deferred card marks have been flushed.
2858   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2859 
2860   // Traverse the GCHandles
2861   Thread::oops_do(f, cf);
2862 
2863   JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2864 
2865   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2866          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2867 
2868   if (has_last_Java_frame()) {
2869     // Record JavaThread to GC thread
2870     RememberProcessedThread rpt(this);
2871 
2872     // Traverse the privileged stack
2873     if (_privileged_stack_top != NULL) {
2874       _privileged_stack_top->oops_do(f);
2875     }
2876 
2877     // traverse the registered growable array
2878     if (_array_for_gc != NULL) {
2879       for (int index = 0; index < _array_for_gc->length(); index++) {
2880         f->do_oop(_array_for_gc->adr_at(index));
2881       }
2882     }
2883 
2884     // Traverse the monitor chunks
2885     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2886       chunk->oops_do(f);
2887     }
2888 
2889     // Traverse the execution stack
2890     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2891       fst.current()->oops_do(f, cf, fst.register_map());
2892     }
2893   }
2894 
2895   // callee_target is never live across a gc point so NULL it here should
2896   // it still contain a methdOop.
2897 
2898   set_callee_target(NULL);
2899 
2900   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2901   // If we have deferred set_locals there might be oops waiting to be
2902   // written
2903   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2904   if (list != NULL) {
2905     for (int i = 0; i < list->length(); i++) {
2906       list->at(i)->oops_do(f);
2907     }
2908   }
2909 
2910   // Traverse instance variables at the end since the GC may be moving things
2911   // around using this function
2912   f->do_oop((oop*) &_threadObj);
2913   f->do_oop((oop*) &_vm_result);
2914   f->do_oop((oop*) &_exception_oop);
2915   f->do_oop((oop*) &_pending_async_exception);
2916 
2917   if (jvmti_thread_state() != NULL) {
2918     jvmti_thread_state()->oops_do(f);
2919   }
2920 }
2921 
2922 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2923   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2924          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2925 
2926   if (has_last_Java_frame()) {
2927     // Traverse the execution stack
2928     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2929       fst.current()->nmethods_do(cf);
2930     }
2931   }
2932 }
2933 
2934 void JavaThread::metadata_do(void f(Metadata*)) {
2935   if (has_last_Java_frame()) {
2936     // Traverse the execution stack to call f() on the methods in the stack
2937     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2938       fst.current()->metadata_do(f);
2939     }
2940   } else if (is_Compiler_thread()) {
2941     // need to walk ciMetadata in current compile tasks to keep alive.
2942     CompilerThread* ct = (CompilerThread*)this;
2943     if (ct->env() != NULL) {
2944       ct->env()->metadata_do(f);
2945     }
2946     if (ct->task() != NULL) {
2947       ct->task()->metadata_do(f);
2948     }
2949   }
2950 }
2951 
2952 // Printing
2953 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2954   switch (_thread_state) {
2955   case _thread_uninitialized:     return "_thread_uninitialized";
2956   case _thread_new:               return "_thread_new";
2957   case _thread_new_trans:         return "_thread_new_trans";
2958   case _thread_in_native:         return "_thread_in_native";
2959   case _thread_in_native_trans:   return "_thread_in_native_trans";
2960   case _thread_in_vm:             return "_thread_in_vm";
2961   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
2962   case _thread_in_Java:           return "_thread_in_Java";
2963   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
2964   case _thread_blocked:           return "_thread_blocked";
2965   case _thread_blocked_trans:     return "_thread_blocked_trans";
2966   default:                        return "unknown thread state";
2967   }
2968 }
2969 
2970 #ifndef PRODUCT
2971 void JavaThread::print_thread_state_on(outputStream *st) const {
2972   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
2973 };
2974 void JavaThread::print_thread_state() const {
2975   print_thread_state_on(tty);
2976 }
2977 #endif // PRODUCT
2978 
2979 // Called by Threads::print() for VM_PrintThreads operation
2980 void JavaThread::print_on(outputStream *st) const {
2981   st->print_raw("\"");
2982   st->print_raw(get_thread_name());
2983   st->print_raw("\" ");
2984   oop thread_oop = threadObj();
2985   if (thread_oop != NULL) {
2986     st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2987     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
2988     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2989   }
2990   Thread::print_on(st);
2991   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2992   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2993   if (thread_oop != NULL) {
2994     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2995   }
2996 #ifndef PRODUCT
2997   print_thread_state_on(st);
2998   _safepoint_state->print_on(st);
2999 #endif // PRODUCT
3000   if (is_Compiler_thread()) {
3001     CompilerThread* ct = (CompilerThread*)this;
3002     if (ct->task() != NULL) {
3003       st->print("   Compiling: ");
3004       ct->task()->print(st, NULL, true, false);
3005     } else {
3006       st->print("   No compile task");
3007     }
3008     st->cr();
3009   }
3010 }
3011 
3012 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
3013   st->print("%s", get_thread_name_string(buf, buflen));
3014 }
3015 
3016 // Called by fatal error handler. The difference between this and
3017 // JavaThread::print() is that we can't grab lock or allocate memory.
3018 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
3019   st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
3020   oop thread_obj = threadObj();
3021   if (thread_obj != NULL) {
3022     if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
3023   }
3024   st->print(" [");
3025   st->print("%s", _get_thread_state_name(_thread_state));
3026   if (osthread()) {
3027     st->print(", id=%d", osthread()->thread_id());
3028   }
3029   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
3030             p2i(stack_end()), p2i(stack_base()));
3031   st->print("]");
3032 
3033   if (_threads_hazard_ptr != NULL) {
3034     st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
3035   }
3036   if (_nested_threads_hazard_ptr != NULL) {
3037     print_nested_threads_hazard_ptrs_on(st);
3038   }
3039   return;
3040 }
3041 
3042 // Verification
3043 
3044 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3045 
3046 void JavaThread::verify() {
3047   // Verify oops in the thread.
3048   oops_do(&VerifyOopClosure::verify_oop, NULL);
3049 
3050   // Verify the stack frames.
3051   frames_do(frame_verify);
3052 }
3053 
3054 // CR 6300358 (sub-CR 2137150)
3055 // Most callers of this method assume that it can't return NULL but a
3056 // thread may not have a name whilst it is in the process of attaching to
3057 // the VM - see CR 6412693, and there are places where a JavaThread can be
3058 // seen prior to having it's threadObj set (eg JNI attaching threads and
3059 // if vm exit occurs during initialization). These cases can all be accounted
3060 // for such that this method never returns NULL.
3061 const char* JavaThread::get_thread_name() const {
3062 #ifdef ASSERT
3063   // early safepoints can hit while current thread does not yet have TLS
3064   if (!SafepointSynchronize::is_at_safepoint()) {
3065     Thread *cur = Thread::current();
3066     if (!(cur->is_Java_thread() && cur == this)) {
3067       // Current JavaThreads are allowed to get their own name without
3068       // the Threads_lock.
3069       assert_locked_or_safepoint(Threads_lock);
3070     }
3071   }
3072 #endif // ASSERT
3073   return get_thread_name_string();
3074 }
3075 
3076 // Returns a non-NULL representation of this thread's name, or a suitable
3077 // descriptive string if there is no set name
3078 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3079   const char* name_str;
3080   oop thread_obj = threadObj();
3081   if (thread_obj != NULL) {
3082     oop name = java_lang_Thread::name(thread_obj);
3083     if (name != NULL) {
3084       if (buf == NULL) {
3085         name_str = java_lang_String::as_utf8_string(name);
3086       } else {
3087         name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3088       }
3089     } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3090       name_str = "<no-name - thread is attaching>";
3091     } else {
3092       name_str = Thread::name();
3093     }
3094   } else {
3095     name_str = Thread::name();
3096   }
3097   assert(name_str != NULL, "unexpected NULL thread name");
3098   return name_str;
3099 }
3100 
3101 
3102 const char* JavaThread::get_threadgroup_name() const {
3103   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3104   oop thread_obj = threadObj();
3105   if (thread_obj != NULL) {
3106     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3107     if (thread_group != NULL) {
3108       // ThreadGroup.name can be null
3109       return java_lang_ThreadGroup::name(thread_group);
3110     }
3111   }
3112   return NULL;
3113 }
3114 
3115 const char* JavaThread::get_parent_name() const {
3116   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3117   oop thread_obj = threadObj();
3118   if (thread_obj != NULL) {
3119     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3120     if (thread_group != NULL) {
3121       oop parent = java_lang_ThreadGroup::parent(thread_group);
3122       if (parent != NULL) {
3123         // ThreadGroup.name can be null
3124         return java_lang_ThreadGroup::name(parent);
3125       }
3126     }
3127   }
3128   return NULL;
3129 }
3130 
3131 ThreadPriority JavaThread::java_priority() const {
3132   oop thr_oop = threadObj();
3133   if (thr_oop == NULL) return NormPriority; // Bootstrapping
3134   ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3135   assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3136   return priority;
3137 }
3138 
3139 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3140 
3141   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3142   // Link Java Thread object <-> C++ Thread
3143 
3144   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3145   // and put it into a new Handle.  The Handle "thread_oop" can then
3146   // be used to pass the C++ thread object to other methods.
3147 
3148   // Set the Java level thread object (jthread) field of the
3149   // new thread (a JavaThread *) to C++ thread object using the
3150   // "thread_oop" handle.
3151 
3152   // Set the thread field (a JavaThread *) of the
3153   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3154 
3155   Handle thread_oop(Thread::current(),
3156                     JNIHandles::resolve_non_null(jni_thread));
3157   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3158          "must be initialized");
3159   set_threadObj(thread_oop());
3160   java_lang_Thread::set_thread(thread_oop(), this);
3161 
3162   if (prio == NoPriority) {
3163     prio = java_lang_Thread::priority(thread_oop());
3164     assert(prio != NoPriority, "A valid priority should be present");
3165   }
3166 
3167   // Push the Java priority down to the native thread; needs Threads_lock
3168   Thread::set_priority(this, prio);
3169 
3170   prepare_ext();
3171 
3172   // Add the new thread to the Threads list and set it in motion.
3173   // We must have threads lock in order to call Threads::add.
3174   // It is crucial that we do not block before the thread is
3175   // added to the Threads list for if a GC happens, then the java_thread oop
3176   // will not be visited by GC.
3177   Threads::add(this);
3178 }
3179 
3180 oop JavaThread::current_park_blocker() {
3181   // Support for JSR-166 locks
3182   oop thread_oop = threadObj();
3183   if (thread_oop != NULL &&
3184       JDK_Version::current().supports_thread_park_blocker()) {
3185     return java_lang_Thread::park_blocker(thread_oop);
3186   }
3187   return NULL;
3188 }
3189 
3190 
3191 void JavaThread::print_stack_on(outputStream* st) {
3192   if (!has_last_Java_frame()) return;
3193   ResourceMark rm;
3194   HandleMark   hm;
3195 
3196   RegisterMap reg_map(this);
3197   vframe* start_vf = last_java_vframe(&reg_map);
3198   int count = 0;
3199   for (vframe* f = start_vf; f; f = f->sender()) {
3200     if (f->is_java_frame()) {
3201       javaVFrame* jvf = javaVFrame::cast(f);
3202       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3203 
3204       // Print out lock information
3205       if (JavaMonitorsInStackTrace) {
3206         jvf->print_lock_info_on(st, count);
3207       }
3208     } else {
3209       // Ignore non-Java frames
3210     }
3211 
3212     // Bail-out case for too deep stacks
3213     count++;
3214     if (MaxJavaStackTraceDepth == count) return;
3215   }
3216 }
3217 
3218 
3219 // JVMTI PopFrame support
3220 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3221   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3222   if (in_bytes(size_in_bytes) != 0) {
3223     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3224     _popframe_preserved_args_size = in_bytes(size_in_bytes);
3225     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3226   }
3227 }
3228 
3229 void* JavaThread::popframe_preserved_args() {
3230   return _popframe_preserved_args;
3231 }
3232 
3233 ByteSize JavaThread::popframe_preserved_args_size() {
3234   return in_ByteSize(_popframe_preserved_args_size);
3235 }
3236 
3237 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3238   int sz = in_bytes(popframe_preserved_args_size());
3239   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3240   return in_WordSize(sz / wordSize);
3241 }
3242 
3243 void JavaThread::popframe_free_preserved_args() {
3244   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3245   FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3246   _popframe_preserved_args = NULL;
3247   _popframe_preserved_args_size = 0;
3248 }
3249 
3250 #ifndef PRODUCT
3251 
3252 void JavaThread::trace_frames() {
3253   tty->print_cr("[Describe stack]");
3254   int frame_no = 1;
3255   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3256     tty->print("  %d. ", frame_no++);
3257     fst.current()->print_value_on(tty, this);
3258     tty->cr();
3259   }
3260 }
3261 
3262 class PrintAndVerifyOopClosure: public OopClosure {
3263  protected:
3264   template <class T> inline void do_oop_work(T* p) {
3265     oop obj = oopDesc::load_decode_heap_oop(p);
3266     if (obj == NULL) return;
3267     tty->print(INTPTR_FORMAT ": ", p2i(p));
3268     if (oopDesc::is_oop_or_null(obj)) {
3269       if (obj->is_objArray()) {
3270         tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3271       } else {
3272         obj->print();
3273       }
3274     } else {
3275       tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3276     }
3277     tty->cr();
3278   }
3279  public:
3280   virtual void do_oop(oop* p) { do_oop_work(p); }
3281   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
3282 };
3283 
3284 
3285 static void oops_print(frame* f, const RegisterMap *map) {
3286   PrintAndVerifyOopClosure print;
3287   f->print_value();
3288   f->oops_do(&print, NULL, (RegisterMap*)map);
3289 }
3290 
3291 // Print our all the locations that contain oops and whether they are
3292 // valid or not.  This useful when trying to find the oldest frame
3293 // where an oop has gone bad since the frame walk is from youngest to
3294 // oldest.
3295 void JavaThread::trace_oops() {
3296   tty->print_cr("[Trace oops]");
3297   frames_do(oops_print);
3298 }
3299 
3300 
3301 #ifdef ASSERT
3302 // Print or validate the layout of stack frames
3303 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3304   ResourceMark rm;
3305   PRESERVE_EXCEPTION_MARK;
3306   FrameValues values;
3307   int frame_no = 0;
3308   for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3309     fst.current()->describe(values, ++frame_no);
3310     if (depth == frame_no) break;
3311   }
3312   if (validate_only) {
3313     values.validate();
3314   } else {
3315     tty->print_cr("[Describe stack layout]");
3316     values.print(this);
3317   }
3318 }
3319 #endif
3320 
3321 void JavaThread::trace_stack_from(vframe* start_vf) {
3322   ResourceMark rm;
3323   int vframe_no = 1;
3324   for (vframe* f = start_vf; f; f = f->sender()) {
3325     if (f->is_java_frame()) {
3326       javaVFrame::cast(f)->print_activation(vframe_no++);
3327     } else {
3328       f->print();
3329     }
3330     if (vframe_no > StackPrintLimit) {
3331       tty->print_cr("...<more frames>...");
3332       return;
3333     }
3334   }
3335 }
3336 
3337 
3338 void JavaThread::trace_stack() {
3339   if (!has_last_Java_frame()) return;
3340   ResourceMark rm;
3341   HandleMark   hm;
3342   RegisterMap reg_map(this);
3343   trace_stack_from(last_java_vframe(&reg_map));
3344 }
3345 
3346 
3347 #endif // PRODUCT
3348 
3349 
3350 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3351   assert(reg_map != NULL, "a map must be given");
3352   frame f = last_frame();
3353   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3354     if (vf->is_java_frame()) return javaVFrame::cast(vf);
3355   }
3356   return NULL;
3357 }
3358 
3359 
3360 Klass* JavaThread::security_get_caller_class(int depth) {
3361   vframeStream vfst(this);
3362   vfst.security_get_caller_frame(depth);
3363   if (!vfst.at_end()) {
3364     return vfst.method()->method_holder();
3365   }
3366   return NULL;
3367 }
3368 
3369 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3370   assert(thread->is_Compiler_thread(), "must be compiler thread");
3371   CompileBroker::compiler_thread_loop();
3372 }
3373 
3374 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3375   NMethodSweeper::sweeper_loop();
3376 }
3377 
3378 // Create a CompilerThread
3379 CompilerThread::CompilerThread(CompileQueue* queue,
3380                                CompilerCounters* counters)
3381                                : JavaThread(&compiler_thread_entry) {
3382   _env   = NULL;
3383   _log   = NULL;
3384   _task  = NULL;
3385   _queue = queue;
3386   _counters = counters;
3387   _buffer_blob = NULL;
3388   _compiler = NULL;
3389 
3390   // Compiler uses resource area for compilation, let's bias it to mtCompiler
3391   resource_area()->bias_to(mtCompiler);
3392 
3393 #ifndef PRODUCT
3394   _ideal_graph_printer = NULL;
3395 #endif
3396 }
3397 
3398 bool CompilerThread::can_call_java() const {
3399   return _compiler != NULL && _compiler->is_jvmci();
3400 }
3401 
3402 // Create sweeper thread
3403 CodeCacheSweeperThread::CodeCacheSweeperThread()
3404 : JavaThread(&sweeper_thread_entry) {
3405   _scanned_compiled_method = NULL;
3406 }
3407 
3408 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3409   JavaThread::oops_do(f, cf);
3410   if (_scanned_compiled_method != NULL && cf != NULL) {
3411     // Safepoints can occur when the sweeper is scanning an nmethod so
3412     // process it here to make sure it isn't unloaded in the middle of
3413     // a scan.
3414     cf->do_code_blob(_scanned_compiled_method);
3415   }
3416 }
3417 
3418 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3419   JavaThread::nmethods_do(cf);
3420   if (_scanned_compiled_method != NULL && cf != NULL) {
3421     // Safepoints can occur when the sweeper is scanning an nmethod so
3422     // process it here to make sure it isn't unloaded in the middle of
3423     // a scan.
3424     cf->do_code_blob(_scanned_compiled_method);
3425   }
3426 }
3427 
3428 
3429 // ======= Threads ========
3430 
3431 // The Threads class links together all active threads, and provides
3432 // operations over all threads. It is protected by the Threads_lock,
3433 // which is also used in other global contexts like safepointing.
3434 // ThreadsListHandles are used to safely perform operations on one
3435 // or more threads without the risk of the thread exiting during the
3436 // operation.
3437 //
3438 // Note: The Threads_lock is currently more widely used than we
3439 // would like. We are actively migrating Threads_lock uses to other
3440 // mechanisms in order to reduce Threads_lock contention.
3441 
3442 JavaThread*           Threads::_thread_list = NULL;
3443 int                   Threads::_number_of_threads = 0;
3444 int                   Threads::_number_of_non_daemon_threads = 0;
3445 int                   Threads::_return_code = 0;
3446 int                   Threads::_thread_claim_parity = 0;
3447 size_t                JavaThread::_stack_size_at_create = 0;
3448 // Safe Memory Reclamation (SMR) support:
3449 Monitor*              Threads::_smr_delete_lock =
3450                           new Monitor(Monitor::special, "smr_delete_lock",
3451                                       false /* allow_vm_block */,
3452                                       Monitor::_safepoint_check_never);
3453 // The '_cnt', '_max' and '_times" fields are enabled via
3454 // -XX:+EnableThreadSMRStatistics:
3455 
3456 // # of parallel threads in _smr_delete_lock->wait().
3457 // Impl note: Hard to imagine > 64K waiting threads so this could be 16-bit,
3458 // but there is no nice 16-bit _FORMAT support.
3459 uint                  Threads::_smr_delete_lock_wait_cnt = 0;
3460 
3461 // Max # of parallel threads in _smr_delete_lock->wait().
3462 // Impl note: See _smr_delete_lock_wait_cnt note.
3463 uint                  Threads::_smr_delete_lock_wait_max = 0;
3464 
3465 // Flag to indicate when an _smr_delete_lock->notify() is needed.
3466 // Impl note: See _smr_delete_lock_wait_cnt note.
3467 volatile uint         Threads::_smr_delete_notify = 0;
3468 
3469 // # of threads deleted over VM lifetime.
3470 // Impl note: Atomically incremented over VM lifetime so use unsigned for more
3471 // range. Unsigned 64-bit would be more future proof, but 64-bit atomic inc
3472 // isn't available everywhere (or is it?).
3473 volatile uint         Threads::_smr_deleted_thread_cnt = 0;
3474 
3475 // Max time in millis to delete a thread.
3476 // Impl note: 16-bit might be too small on an overloaded machine. Use
3477 // unsigned since this is a time value. Set via Atomic::cmpxchg() in a
3478 // loop for correctness.
3479 volatile uint         Threads::_smr_deleted_thread_time_max = 0;
3480 
3481 // Cumulative time in millis to delete threads.
3482 // Impl note: Atomically added to over VM lifetime so use unsigned for more
3483 // range. Unsigned 64-bit would be more future proof, but 64-bit atomic inc
3484 // isn't available everywhere (or is it?).
3485 volatile uint         Threads::_smr_deleted_thread_times = 0;
3486 
3487 ThreadsList* volatile Threads::_smr_java_thread_list = new ThreadsList(0);
3488 
3489 // # of ThreadsLists allocated over VM lifetime.
3490 // Impl note: We allocate a new ThreadsList for every thread create and
3491 // every thread delete so we need a bigger type than the
3492 // _smr_deleted_thread_cnt field.
3493 uint64_t              Threads::_smr_java_thread_list_alloc_cnt = 1;
3494 
3495 // # of ThreadsLists freed over VM lifetime.
3496 // Impl note: See _smr_java_thread_list_alloc_cnt note.
3497 uint64_t              Threads::_smr_java_thread_list_free_cnt = 0;
3498 
3499 // Max size ThreadsList allocated.
3500 // Impl note: Max # of threads alive at one time should fit in unsigned 32-bit.
3501 uint                  Threads::_smr_java_thread_list_max = 0;
3502 
3503 // Max # of nested ThreadsLists for a thread.
3504 // Impl note: Hard to imagine > 64K nested ThreadsLists so this could be
3505 // 16-bit, but there is no nice 16-bit _FORMAT support.
3506 uint                  Threads::_smr_nested_thread_list_max = 0;
3507 
3508 // # of ThreadsListHandles deleted over VM lifetime.
3509 // Impl note: Atomically incremented over VM lifetime so use unsigned for
3510 // more range. There will be fewer ThreadsListHandles than threads so
3511 // unsigned 32-bit should be fine.
3512 volatile uint         Threads::_smr_tlh_cnt = 0;
3513 
3514 // Max time in millis to delete a ThreadsListHandle.
3515 // Impl note: 16-bit might be too small on an overloaded machine. Use
3516 // unsigned since this is a time value. Set via Atomic::cmpxchg() in a
3517 // loop for correctness.
3518 volatile uint         Threads::_smr_tlh_time_max = 0;
3519 
3520 // Cumulative time in millis to delete ThreadsListHandles.
3521 // Impl note: Atomically added to over VM lifetime so use unsigned for more
3522 // range. Unsigned 64-bit would be more future proof, but 64-bit atomic inc
3523 // isn't available everywhere (or is it?).
3524 volatile uint         Threads::_smr_tlh_times = 0;
3525 
3526 ThreadsList*          Threads::_smr_to_delete_list = NULL;
3527 
3528 // # of parallel ThreadsLists on the to-delete list.
3529 // Impl note: Hard to imagine > 64K ThreadsLists needing to be deleted so
3530 // this could be 16-bit, but there is no nice 16-bit _FORMAT support.
3531 uint                  Threads::_smr_to_delete_list_cnt = 0;
3532 
3533 // Max # of parallel ThreadsLists on the to-delete list.
3534 // Impl note: See _smr_to_delete_list_cnt note.
3535 uint                  Threads::_smr_to_delete_list_max = 0;
3536 
3537 #ifdef ASSERT
3538 bool                  Threads::_vm_complete = false;
3539 #endif
3540 
3541 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3542   Prefetch::read((void*)addr, prefetch_interval);
3543   return *addr;
3544 }
3545 
3546 // Possibly the ugliest for loop the world has seen. C++ does not allow
3547 // multiple types in the declaration section of the for loop. In this case
3548 // we are only dealing with pointers and hence can cast them. It looks ugly
3549 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3550 #define DO_JAVA_THREADS(LIST, X)                                                                                          \
3551     for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes,                           \
3552              *MACRO_list = (JavaThread*)(LIST),                                                                           \
3553              **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(),  \
3554              **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(),                                     \
3555              *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval);                 \
3556          MACRO_current_p != MACRO_end;                                                                                    \
3557          MACRO_current_p++,                                                                                               \
3558              X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3559 
3560 // All JavaThreads
3561 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(get_smr_java_thread_list(), X)
3562 
3563 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3564 void Threads::threads_do(ThreadClosure* tc) {
3565   assert_locked_or_safepoint(Threads_lock);
3566   // ALL_JAVA_THREADS iterates through all JavaThreads
3567   ALL_JAVA_THREADS(p) {
3568     tc->do_thread(p);
3569   }
3570   // Someday we could have a table or list of all non-JavaThreads.
3571   // For now, just manually iterate through them.
3572   tc->do_thread(VMThread::vm_thread());
3573   Universe::heap()->gc_threads_do(tc);
3574   WatcherThread *wt = WatcherThread::watcher_thread();
3575   // Strictly speaking, the following NULL check isn't sufficient to make sure
3576   // the data for WatcherThread is still valid upon being examined. However,
3577   // considering that WatchThread terminates when the VM is on the way to
3578   // exit at safepoint, the chance of the above is extremely small. The right
3579   // way to prevent termination of WatcherThread would be to acquire
3580   // Terminator_lock, but we can't do that without violating the lock rank
3581   // checking in some cases.
3582   if (wt != NULL) {
3583     tc->do_thread(wt);
3584   }
3585 
3586   // If CompilerThreads ever become non-JavaThreads, add them here
3587 }
3588 
3589 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3590   int cp = Threads::thread_claim_parity();
3591   ALL_JAVA_THREADS(p) {
3592     if (p->claim_oops_do(is_par, cp)) {
3593       tc->do_thread(p);
3594     }
3595   }
3596   VMThread* vmt = VMThread::vm_thread();
3597   if (vmt->claim_oops_do(is_par, cp)) {
3598     tc->do_thread(vmt);
3599   }
3600 }
3601 
3602 // The system initialization in the library has three phases.
3603 //
3604 // Phase 1: java.lang.System class initialization
3605 //     java.lang.System is a primordial class loaded and initialized
3606 //     by the VM early during startup.  java.lang.System.<clinit>
3607 //     only does registerNatives and keeps the rest of the class
3608 //     initialization work later until thread initialization completes.
3609 //
3610 //     System.initPhase1 initializes the system properties, the static
3611 //     fields in, out, and err. Set up java signal handlers, OS-specific
3612 //     system settings, and thread group of the main thread.
3613 static void call_initPhase1(TRAPS) {
3614   Klass* klass =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3615   JavaValue result(T_VOID);
3616   JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3617                                          vmSymbols::void_method_signature(), CHECK);
3618 }
3619 
3620 // Phase 2. Module system initialization
3621 //     This will initialize the module system.  Only java.base classes
3622 //     can be loaded until phase 2 completes.
3623 //
3624 //     Call System.initPhase2 after the compiler initialization and jsr292
3625 //     classes get initialized because module initialization runs a lot of java
3626 //     code, that for performance reasons, should be compiled.  Also, this will
3627 //     enable the startup code to use lambda and other language features in this
3628 //     phase and onward.
3629 //
3630 //     After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3631 static void call_initPhase2(TRAPS) {
3632   TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3633 
3634   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3635 
3636   JavaValue result(T_INT);
3637   JavaCallArguments args;
3638   args.push_int(DisplayVMOutputToStderr);
3639   args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3640   JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3641                                          vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3642   if (result.get_jint() != JNI_OK) {
3643     vm_exit_during_initialization(); // no message or exception
3644   }
3645 
3646   universe_post_module_init();
3647 }
3648 
3649 // Phase 3. final setup - set security manager, system class loader and TCCL
3650 //
3651 //     This will instantiate and set the security manager, set the system class
3652 //     loader as well as the thread context class loader.  The security manager
3653 //     and system class loader may be a custom class loaded from -Xbootclasspath/a,
3654 //     other modules or the application's classpath.
3655 static void call_initPhase3(TRAPS) {
3656   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3657   JavaValue result(T_VOID);
3658   JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3659                                          vmSymbols::void_method_signature(), CHECK);
3660 }
3661 
3662 // Safe Memory Reclamation (SMR) support:
3663 //
3664 
3665 // Acquire a stable ThreadsList.
3666 //
3667 ThreadsList *Threads::acquire_stable_list(Thread *self, bool is_ThreadsListSetter) {
3668   assert(self != NULL, "sanity check");
3669   // acquire_stable_list_nested_path() will grab the Threads_lock
3670   // so let's make sure the ThreadsListHandle is in a safe place.
3671   // ThreadsListSetter cannot make this check on this code path.
3672   debug_only(if (!is_ThreadsListSetter && StrictSafepointChecks) self->check_for_valid_safepoint_state(/* potential_vm_operation */ false);)
3673 
3674   if (self->get_threads_hazard_ptr() == NULL) {
3675     // The typical case is first.
3676     return acquire_stable_list_fast_path(self);
3677   }
3678 
3679   // The nested case is rare.
3680   return acquire_stable_list_nested_path(self);
3681 }
3682 
3683 // Fast path (and lock free) way to acquire a stable ThreadsList.
3684 //
3685 ThreadsList *Threads::acquire_stable_list_fast_path(Thread *self) {
3686   assert(self != NULL, "sanity check");
3687   assert(self->get_threads_hazard_ptr() == NULL, "sanity check");
3688   assert(self->get_nested_threads_hazard_ptr() == NULL,
3689          "cannot have a nested hazard ptr with a NULL regular hazard ptr");
3690 
3691   ThreadsList* threads;
3692 
3693   // Stable recording of a hazard ptr for SMR. This code does not use
3694   // locks so its use of the _smr_java_thread_list & _threads_hazard_ptr
3695   // fields is racy relative to code that uses those fields with locks.
3696   // OrderAccess and Atomic functions are used to deal with those races.
3697   //
3698   while (true) {
3699     threads = get_smr_java_thread_list();
3700 
3701     // Publish a tagged hazard ptr to denote that the hazard ptr is not
3702     // yet verified as being stable. Due to the fence after the hazard
3703     // ptr write, it will be sequentially consistent w.r.t. the
3704     // sequentially consistent writes of the ThreadsList, even on
3705     // non-multiple copy atomic machines where stores can be observed
3706     // in different order from different observer threads.
3707     ThreadsList* unverified_threads = Thread::tag_hazard_ptr(threads);
3708     self->set_threads_hazard_ptr(unverified_threads);
3709 
3710     // If _smr_java_thread_list has changed, we have lost a race with
3711     // Threads::add() or Threads::remove() and have to try again.
3712     if (get_smr_java_thread_list() != threads) {
3713       continue;
3714     }
3715 
3716     // We try to remove the tag which will verify the hazard ptr as
3717     // being stable. This exchange can race with a scanning thread
3718     // which might invalidate the tagged hazard ptr to keep it from
3719     // being followed to access JavaThread ptrs. If we lose the race,
3720     // we simply retry. If we win the race, then the stable hazard
3721     // ptr is officially published.
3722     if (self->cmpxchg_threads_hazard_ptr(threads, unverified_threads) == unverified_threads) {
3723       break;
3724     }
3725   }
3726 
3727   // A stable hazard ptr has been published letting other threads know
3728   // that the ThreadsList and the JavaThreads reachable from this list
3729   // are protected and hence they should not be deleted until everyone
3730   // agrees it is safe to do so.
3731 
3732   return threads;
3733 }
3734 
3735 // Acquire a nested stable ThreadsList; this is rare so it uses
3736 // Threads_lock.
3737 //
3738 ThreadsList *Threads::acquire_stable_list_nested_path(Thread *self) {
3739   assert(self != NULL, "sanity check");
3740   assert(self->get_threads_hazard_ptr() != NULL,
3741          "cannot have a NULL regular hazard ptr when acquiring a nested hazard ptr");
3742 
3743   // The thread already has a hazard ptr (ThreadsList ref) so we need
3744   // to create a nested ThreadsListHandle with the current ThreadsList
3745   // since it might be different than our current hazard ptr. The need
3746   // for a nested ThreadsListHandle is rare so we do this while holding
3747   // the Threads_lock so we don't race with the scanning code; the code
3748   // is so much simpler this way.
3749 
3750   NestedThreadsList* node;
3751   {
3752     // Only grab the Threads_lock if we don't already own it.
3753     MutexLockerEx ml(Threads_lock->owned_by_self() ? NULL : Threads_lock);
3754     node = new NestedThreadsList(get_smr_java_thread_list());
3755     // We insert at the front of the list to match up with the delete
3756     // in release_stable_list().
3757     node->set_next(self->get_nested_threads_hazard_ptr());
3758     self->set_nested_threads_hazard_ptr(node);
3759     if (EnableThreadSMRStatistics) {
3760       self->inc_nested_threads_hazard_ptr_cnt();
3761       if (self->nested_threads_hazard_ptr_cnt() > _smr_nested_thread_list_max) {
3762         _smr_nested_thread_list_max = self->nested_threads_hazard_ptr_cnt();
3763       }
3764     }
3765   }
3766   log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::acquire_stable_list: add NestedThreadsList node containing ThreadsList=" INTPTR_FORMAT, os::current_thread_id(), p2i(node->t_list()));
3767 
3768   return node->t_list();
3769 }
3770 
3771 // Release a stable ThreadsList.
3772 //
3773 void Threads::release_stable_list(Thread *self) {
3774   assert(self != NULL, "sanity check");
3775   // release_stable_list_nested_path() will grab the Threads_lock
3776   // so let's make sure the ThreadsListHandle is in a safe place.
3777   debug_only(if (StrictSafepointChecks) self->check_for_valid_safepoint_state(/* potential_vm_operation */ false);)
3778 
3779   if (self->get_nested_threads_hazard_ptr() == NULL) {
3780     // The typical case is first.
3781     release_stable_list_fast_path(self);
3782     return;
3783   }
3784 
3785   // The nested case is rare.
3786   release_stable_list_nested_path(self);
3787 }
3788 
3789 // Fast path way to release a stable ThreadsList. The release portion
3790 // is lock-free, but the wake up portion is not.
3791 //
3792 void Threads::release_stable_list_fast_path(Thread *self) {
3793   assert(self != NULL, "sanity check");
3794   assert(self->get_threads_hazard_ptr() != NULL, "sanity check");
3795   assert(self->get_nested_threads_hazard_ptr() == NULL,
3796          "cannot have a nested hazard ptr when releasing a regular hazard ptr");
3797 
3798   // After releasing the hazard ptr, other threads may go ahead and
3799   // free up some memory temporarily used by a ThreadsList snapshot.
3800   self->set_threads_hazard_ptr(NULL);
3801 
3802   // We use double-check locking to reduce traffic on the system
3803   // wide smr_delete_lock.
3804   if (Threads::smr_delete_notify()) {
3805     // An exiting thread might be waiting in smr_delete(); we need to
3806     // check with smr_delete_lock to be sure.
3807     release_stable_list_wake_up((char *) "regular hazard ptr");
3808   }
3809 }
3810 
3811 // Release a nested stable ThreadsList; this is rare so it uses
3812 // Threads_lock.
3813 //
3814 void Threads::release_stable_list_nested_path(Thread *self) {
3815   assert(self != NULL, "sanity check");
3816   assert(self->get_nested_threads_hazard_ptr() != NULL, "sanity check");
3817   assert(self->get_threads_hazard_ptr() != NULL,
3818          "must have a regular hazard ptr to have nested hazard ptrs");
3819 
3820   // We have a nested ThreadsListHandle so we have to release it first.
3821   // The need for a nested ThreadsListHandle is rare so we do this while
3822   // holding the Threads_lock so we don't race with the scanning code;
3823   // the code is so much simpler this way.
3824 
3825   NestedThreadsList *node;
3826   {
3827     // Only grab the Threads_lock if we don't already own it.
3828     MutexLockerEx ml(Threads_lock->owned_by_self() ? NULL : Threads_lock);
3829     // We remove from the front of the list to match up with the insert
3830     // in acquire_stable_list().
3831     node = self->get_nested_threads_hazard_ptr();
3832     self->set_nested_threads_hazard_ptr(node->next());
3833     if (EnableThreadSMRStatistics) {
3834       self->dec_nested_threads_hazard_ptr_cnt();
3835     }
3836   }
3837 
3838   // An exiting thread might be waiting in smr_delete(); we need to
3839   // check with smr_delete_lock to be sure.
3840   release_stable_list_wake_up((char *) "nested hazard ptr");
3841 
3842   log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::release_stable_list: delete NestedThreadsList node containing ThreadsList=" INTPTR_FORMAT, os::current_thread_id(), p2i(node->t_list()));
3843 
3844   delete node;
3845 }
3846 
3847 // Wake up portion of the release stable ThreadsList protocol;
3848 // uses the smr_delete_lock().
3849 //
3850 void Threads::release_stable_list_wake_up(char *log_str) {
3851   assert(log_str != NULL, "sanity check");
3852 
3853   // Note: smr_delete_lock is held in smr_delete() for the entire
3854   // hazard ptr search so that we do not lose this notify() if
3855   // the exiting thread has to wait. That code path also holds
3856   // Threads_lock (which was grabbed before smr_delete_lock) so that
3857   // threads_do() can be called. This means the system can't start a
3858   // safepoint which means this thread can't take too long to get to
3859   // a safepoint because of being blocked on smr_delete_lock.
3860   //
3861   MonitorLockerEx ml(Threads::smr_delete_lock(), Monitor::_no_safepoint_check_flag);
3862   if (Threads::smr_delete_notify()) {
3863     // Notify any exiting JavaThreads that are waiting in smr_delete()
3864     // that we've released a ThreadsList.
3865     ml.notify_all();
3866     log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::release_stable_list notified %s", os::current_thread_id(), log_str);
3867   }
3868 }
3869 
3870 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3871   TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3872 
3873   if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3874     create_vm_init_libraries();
3875   }
3876 
3877   initialize_class(vmSymbols::java_lang_String(), CHECK);
3878 
3879   // Inject CompactStrings value after the static initializers for String ran.
3880   java_lang_String::set_compact_strings(CompactStrings);
3881 
3882   // Initialize java_lang.System (needed before creating the thread)
3883   initialize_class(vmSymbols::java_lang_System(), CHECK);
3884   // The VM creates & returns objects of this class. Make sure it's initialized.
3885   initialize_class(vmSymbols::java_lang_Class(), CHECK);
3886   initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3887   Handle thread_group = create_initial_thread_group(CHECK);
3888   Universe::set_main_thread_group(thread_group());
3889   initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3890   oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3891   main_thread->set_threadObj(thread_object);
3892   // Set thread status to running since main thread has
3893   // been started and running.
3894   java_lang_Thread::set_thread_status(thread_object,
3895                                       java_lang_Thread::RUNNABLE);
3896 
3897   // The VM creates objects of this class.
3898   initialize_class(vmSymbols::java_lang_Module(), CHECK);
3899 
3900   // The VM preresolves methods to these classes. Make sure that they get initialized
3901   initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3902   initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3903 
3904   // Phase 1 of the system initialization in the library, java.lang.System class initialization
3905   call_initPhase1(CHECK);
3906 
3907   // get the Java runtime name after java.lang.System is initialized
3908   JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3909   JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3910 
3911   // an instance of OutOfMemory exception has been allocated earlier
3912   initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3913   initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3914   initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3915   initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3916   initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3917   initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3918   initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3919   initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3920 }
3921 
3922 void Threads::initialize_jsr292_core_classes(TRAPS) {
3923   TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3924 
3925   initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3926   initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3927   initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3928   initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3929 }
3930 
3931 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3932   extern void JDK_Version_init();
3933 
3934   // Preinitialize version info.
3935   VM_Version::early_initialize();
3936 
3937   // Check version
3938   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3939 
3940   // Initialize library-based TLS
3941   ThreadLocalStorage::init();
3942 
3943   // Initialize the output stream module
3944   ostream_init();
3945 
3946   // Process java launcher properties.
3947   Arguments::process_sun_java_launcher_properties(args);
3948 
3949   // Initialize the os module
3950   os::init();
3951 
3952   // Record VM creation timing statistics
3953   TraceVmCreationTime create_vm_timer;
3954   create_vm_timer.start();
3955 
3956   // Initialize system properties.
3957   Arguments::init_system_properties();
3958 
3959   // So that JDK version can be used as a discriminator when parsing arguments
3960   JDK_Version_init();
3961 
3962   // Update/Initialize System properties after JDK version number is known
3963   Arguments::init_version_specific_system_properties();
3964 
3965   // Make sure to initialize log configuration *before* parsing arguments
3966   LogConfiguration::initialize(create_vm_timer.begin_time());
3967 
3968   // Parse arguments
3969   // Note: this internally calls os::init_container_support()
3970   jint parse_result = Arguments::parse(args);
3971   if (parse_result != JNI_OK) return parse_result;
3972 
3973   os::init_before_ergo();
3974 
3975   jint ergo_result = Arguments::apply_ergo();
3976   if (ergo_result != JNI_OK) return ergo_result;
3977 
3978   // Final check of all ranges after ergonomics which may change values.
3979   if (!CommandLineFlagRangeList::check_ranges()) {
3980     return JNI_EINVAL;
3981   }
3982 
3983   // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3984   bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3985   if (!constraint_result) {
3986     return JNI_EINVAL;
3987   }
3988 
3989   CommandLineFlagWriteableList::mark_startup();
3990 
3991   if (PauseAtStartup) {
3992     os::pause();
3993   }
3994 
3995   HOTSPOT_VM_INIT_BEGIN();
3996 
3997   // Timing (must come after argument parsing)
3998   TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3999 
4000   SafepointMechanism::initialize();
4001 
4002   // Initialize the os module after parsing the args
4003   jint os_init_2_result = os::init_2();
4004   if (os_init_2_result != JNI_OK) return os_init_2_result;
4005 
4006   jint adjust_after_os_result = Arguments::adjust_after_os();
4007   if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
4008 
4009   // Initialize output stream logging
4010   ostream_init_log();
4011 
4012   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
4013   // Must be before create_vm_init_agents()
4014   if (Arguments::init_libraries_at_startup()) {
4015     convert_vm_init_libraries_to_agents();
4016   }
4017 
4018   // Launch -agentlib/-agentpath and converted -Xrun agents
4019   if (Arguments::init_agents_at_startup()) {
4020     create_vm_init_agents();
4021   }
4022 
4023   // Initialize Threads state
4024   _thread_list = NULL;
4025   _number_of_threads = 0;
4026   _number_of_non_daemon_threads = 0;
4027 
4028   // Initialize global data structures and create system classes in heap
4029   vm_init_globals();
4030 
4031 #if INCLUDE_JVMCI
4032   if (JVMCICounterSize > 0) {
4033     JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
4034     memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
4035   } else {
4036     JavaThread::_jvmci_old_thread_counters = NULL;
4037   }
4038 #endif // INCLUDE_JVMCI
4039 
4040   // Attach the main thread to this os thread
4041   JavaThread* main_thread = new JavaThread();
4042   main_thread->set_thread_state(_thread_in_vm);
4043   main_thread->initialize_thread_current();
4044   // must do this before set_active_handles
4045   main_thread->record_stack_base_and_size();
4046   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
4047 
4048   if (!main_thread->set_as_starting_thread()) {
4049     vm_shutdown_during_initialization(
4050                                       "Failed necessary internal allocation. Out of swap space");
4051     main_thread->smr_delete();
4052     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
4053     return JNI_ENOMEM;
4054   }
4055 
4056   // Enable guard page *after* os::create_main_thread(), otherwise it would
4057   // crash Linux VM, see notes in os_linux.cpp.
4058   main_thread->create_stack_guard_pages();
4059 
4060   // Initialize Java-Level synchronization subsystem
4061   ObjectMonitor::Initialize();
4062 
4063   // Initialize global modules
4064   jint status = init_globals();
4065   if (status != JNI_OK) {
4066     main_thread->smr_delete();
4067     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
4068     return status;
4069   }
4070 
4071   if (TRACE_INITIALIZE() != JNI_OK) {
4072     vm_exit_during_initialization("Failed to initialize tracing backend");
4073   }
4074 
4075   // Should be done after the heap is fully created
4076   main_thread->cache_global_variables();
4077 
4078   HandleMark hm;
4079 
4080   { MutexLocker mu(Threads_lock);
4081     Threads::add(main_thread);
4082   }
4083 
4084   // Any JVMTI raw monitors entered in onload will transition into
4085   // real raw monitor. VM is setup enough here for raw monitor enter.
4086   JvmtiExport::transition_pending_onload_raw_monitors();
4087 
4088   // Create the VMThread
4089   { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
4090 
4091   VMThread::create();
4092     Thread* vmthread = VMThread::vm_thread();
4093 
4094     if (!os::create_thread(vmthread, os::vm_thread)) {
4095       vm_exit_during_initialization("Cannot create VM thread. "
4096                                     "Out of system resources.");
4097     }
4098 
4099     // Wait for the VM thread to become ready, and VMThread::run to initialize
4100     // Monitors can have spurious returns, must always check another state flag
4101     {
4102       MutexLocker ml(Notify_lock);
4103       os::start_thread(vmthread);
4104       while (vmthread->active_handles() == NULL) {
4105         Notify_lock->wait();
4106       }
4107     }
4108   }
4109 
4110   assert(Universe::is_fully_initialized(), "not initialized");
4111   if (VerifyDuringStartup) {
4112     // Make sure we're starting with a clean slate.
4113     VM_Verify verify_op;
4114     VMThread::execute(&verify_op);
4115   }
4116 
4117   Thread* THREAD = Thread::current();
4118 
4119   // Always call even when there are not JVMTI environments yet, since environments
4120   // may be attached late and JVMTI must track phases of VM execution
4121   JvmtiExport::enter_early_start_phase();
4122 
4123   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
4124   JvmtiExport::post_early_vm_start();
4125 
4126   initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
4127 
4128   // We need this for ClassDataSharing - the initial vm.info property is set
4129   // with the default value of CDS "sharing" which may be reset through
4130   // command line options.
4131   reset_vm_info_property(CHECK_JNI_ERR);
4132 
4133   quicken_jni_functions();
4134 
4135   // No more stub generation allowed after that point.
4136   StubCodeDesc::freeze();
4137 
4138   // Set flag that basic initialization has completed. Used by exceptions and various
4139   // debug stuff, that does not work until all basic classes have been initialized.
4140   set_init_completed();
4141 
4142   LogConfiguration::post_initialize();
4143   Metaspace::post_initialize();
4144 
4145   HOTSPOT_VM_INIT_END();
4146 
4147   // record VM initialization completion time
4148 #if INCLUDE_MANAGEMENT
4149   Management::record_vm_init_completed();
4150 #endif // INCLUDE_MANAGEMENT
4151 
4152   // Signal Dispatcher needs to be started before VMInit event is posted
4153   os::signal_init(CHECK_JNI_ERR);
4154 
4155   // Start Attach Listener if +StartAttachListener or it can't be started lazily
4156   if (!DisableAttachMechanism) {
4157     AttachListener::vm_start();
4158     if (StartAttachListener || AttachListener::init_at_startup()) {
4159       AttachListener::init();
4160     }
4161   }
4162 
4163   // Launch -Xrun agents
4164   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
4165   // back-end can launch with -Xdebug -Xrunjdwp.
4166   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
4167     create_vm_init_libraries();
4168   }
4169 
4170   if (CleanChunkPoolAsync) {
4171     Chunk::start_chunk_pool_cleaner_task();
4172   }
4173 
4174   // initialize compiler(s)
4175 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
4176   CompileBroker::compilation_init(CHECK_JNI_ERR);
4177 #endif
4178 
4179   // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
4180   // It is done after compilers are initialized, because otherwise compilations of
4181   // signature polymorphic MH intrinsics can be missed
4182   // (see SystemDictionary::find_method_handle_intrinsic).
4183   initialize_jsr292_core_classes(CHECK_JNI_ERR);
4184 
4185   // This will initialize the module system.  Only java.base classes can be
4186   // loaded until phase 2 completes
4187   call_initPhase2(CHECK_JNI_ERR);
4188 
4189   // Always call even when there are not JVMTI environments yet, since environments
4190   // may be attached late and JVMTI must track phases of VM execution
4191   JvmtiExport::enter_start_phase();
4192 
4193   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
4194   JvmtiExport::post_vm_start();
4195 
4196   // Final system initialization including security manager and system class loader
4197   call_initPhase3(CHECK_JNI_ERR);
4198 
4199   // cache the system and platform class loaders
4200   SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
4201 
4202 #if INCLUDE_JVMCI
4203   if (EnableJVMCI) {
4204     // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled.
4205     // The JVMCI Java initialization code will read this flag and
4206     // do the printing if it's set.
4207     bool init = JVMCIPrintProperties;
4208 
4209     if (!init) {
4210       // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
4211       // compilations via JVMCI will not actually block until JVMCI is initialized.
4212       init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
4213     }
4214 
4215     if (init) {
4216       JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
4217     }
4218   }
4219 #endif
4220 
4221   // Always call even when there are not JVMTI environments yet, since environments
4222   // may be attached late and JVMTI must track phases of VM execution
4223   JvmtiExport::enter_live_phase();
4224 
4225   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
4226   JvmtiExport::post_vm_initialized();
4227 
4228   if (TRACE_START() != JNI_OK) {
4229     vm_exit_during_initialization("Failed to start tracing backend.");
4230   }
4231 
4232 #if INCLUDE_MANAGEMENT
4233   Management::initialize(THREAD);
4234 
4235   if (HAS_PENDING_EXCEPTION) {
4236     // management agent fails to start possibly due to
4237     // configuration problem and is responsible for printing
4238     // stack trace if appropriate. Simply exit VM.
4239     vm_exit(1);
4240   }
4241 #endif // INCLUDE_MANAGEMENT
4242 
4243   if (MemProfiling)                   MemProfiler::engage();
4244   StatSampler::engage();
4245   if (CheckJNICalls)                  JniPeriodicChecker::engage();
4246 
4247   BiasedLocking::init();
4248 
4249 #if INCLUDE_RTM_OPT
4250   RTMLockingCounters::init();
4251 #endif
4252 
4253   if (JDK_Version::current().post_vm_init_hook_enabled()) {
4254     call_postVMInitHook(THREAD);
4255     // The Java side of PostVMInitHook.run must deal with all
4256     // exceptions and provide means of diagnosis.
4257     if (HAS_PENDING_EXCEPTION) {
4258       CLEAR_PENDING_EXCEPTION;
4259     }
4260   }
4261 
4262   {
4263     MutexLocker ml(PeriodicTask_lock);
4264     // Make sure the WatcherThread can be started by WatcherThread::start()
4265     // or by dynamic enrollment.
4266     WatcherThread::make_startable();
4267     // Start up the WatcherThread if there are any periodic tasks
4268     // NOTE:  All PeriodicTasks should be registered by now. If they
4269     //   aren't, late joiners might appear to start slowly (we might
4270     //   take a while to process their first tick).
4271     if (PeriodicTask::num_tasks() > 0) {
4272       WatcherThread::start();
4273     }
4274   }
4275 
4276   create_vm_timer.end();
4277 #ifdef ASSERT
4278   _vm_complete = true;
4279 #endif
4280 
4281   if (DumpSharedSpaces) {
4282     MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
4283     ShouldNotReachHere();
4284   }
4285 
4286   return JNI_OK;
4287 }
4288 
4289 // type for the Agent_OnLoad and JVM_OnLoad entry points
4290 extern "C" {
4291   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
4292 }
4293 // Find a command line agent library and return its entry point for
4294 //         -agentlib:  -agentpath:   -Xrun
4295 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
4296 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
4297                                     const char *on_load_symbols[],
4298                                     size_t num_symbol_entries) {
4299   OnLoadEntry_t on_load_entry = NULL;
4300   void *library = NULL;
4301 
4302   if (!agent->valid()) {
4303     char buffer[JVM_MAXPATHLEN];
4304     char ebuf[1024] = "";
4305     const char *name = agent->name();
4306     const char *msg = "Could not find agent library ";
4307 
4308     // First check to see if agent is statically linked into executable
4309     if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
4310       library = agent->os_lib();
4311     } else if (agent->is_absolute_path()) {
4312       library = os::dll_load(name, ebuf, sizeof ebuf);
4313       if (library == NULL) {
4314         const char *sub_msg = " in absolute path, with error: ";
4315         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4316         char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4317         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4318         // If we can't find the agent, exit.
4319         vm_exit_during_initialization(buf, NULL);
4320         FREE_C_HEAP_ARRAY(char, buf);
4321       }
4322     } else {
4323       // Try to load the agent from the standard dll directory
4324       if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4325                              name)) {
4326         library = os::dll_load(buffer, ebuf, sizeof ebuf);
4327       }
4328       if (library == NULL) { // Try the library path directory.
4329         if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4330           library = os::dll_load(buffer, ebuf, sizeof ebuf);
4331         }
4332         if (library == NULL) {
4333           const char *sub_msg = " on the library path, with error: ";
4334           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4335           char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4336           jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4337           // If we can't find the agent, exit.
4338           vm_exit_during_initialization(buf, NULL);
4339           FREE_C_HEAP_ARRAY(char, buf);
4340         }
4341       }
4342     }
4343     agent->set_os_lib(library);
4344     agent->set_valid();
4345   }
4346 
4347   // Find the OnLoad function.
4348   on_load_entry =
4349     CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4350                                                           false,
4351                                                           on_load_symbols,
4352                                                           num_symbol_entries));
4353   return on_load_entry;
4354 }
4355 
4356 // Find the JVM_OnLoad entry point
4357 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4358   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4359   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4360 }
4361 
4362 // Find the Agent_OnLoad entry point
4363 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4364   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4365   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4366 }
4367 
4368 // For backwards compatibility with -Xrun
4369 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4370 // treated like -agentpath:
4371 // Must be called before agent libraries are created
4372 void Threads::convert_vm_init_libraries_to_agents() {
4373   AgentLibrary* agent;
4374   AgentLibrary* next;
4375 
4376   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4377     next = agent->next();  // cache the next agent now as this agent may get moved off this list
4378     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4379 
4380     // If there is an JVM_OnLoad function it will get called later,
4381     // otherwise see if there is an Agent_OnLoad
4382     if (on_load_entry == NULL) {
4383       on_load_entry = lookup_agent_on_load(agent);
4384       if (on_load_entry != NULL) {
4385         // switch it to the agent list -- so that Agent_OnLoad will be called,
4386         // JVM_OnLoad won't be attempted and Agent_OnUnload will
4387         Arguments::convert_library_to_agent(agent);
4388       } else {
4389         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4390       }
4391     }
4392   }
4393 }
4394 
4395 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
4396 // Invokes Agent_OnLoad
4397 // Called very early -- before JavaThreads exist
4398 void Threads::create_vm_init_agents() {
4399   extern struct JavaVM_ main_vm;
4400   AgentLibrary* agent;
4401 
4402   JvmtiExport::enter_onload_phase();
4403 
4404   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4405     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
4406 
4407     if (on_load_entry != NULL) {
4408       // Invoke the Agent_OnLoad function
4409       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4410       if (err != JNI_OK) {
4411         vm_exit_during_initialization("agent library failed to init", agent->name());
4412       }
4413     } else {
4414       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4415     }
4416   }
4417   JvmtiExport::enter_primordial_phase();
4418 }
4419 
4420 extern "C" {
4421   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4422 }
4423 
4424 void Threads::shutdown_vm_agents() {
4425   // Send any Agent_OnUnload notifications
4426   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4427   size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4428   extern struct JavaVM_ main_vm;
4429   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4430 
4431     // Find the Agent_OnUnload function.
4432     Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4433                                                    os::find_agent_function(agent,
4434                                                    false,
4435                                                    on_unload_symbols,
4436                                                    num_symbol_entries));
4437 
4438     // Invoke the Agent_OnUnload function
4439     if (unload_entry != NULL) {
4440       JavaThread* thread = JavaThread::current();
4441       ThreadToNativeFromVM ttn(thread);
4442       HandleMark hm(thread);
4443       (*unload_entry)(&main_vm);
4444     }
4445   }
4446 }
4447 
4448 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4449 // Invokes JVM_OnLoad
4450 void Threads::create_vm_init_libraries() {
4451   extern struct JavaVM_ main_vm;
4452   AgentLibrary* agent;
4453 
4454   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4455     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4456 
4457     if (on_load_entry != NULL) {
4458       // Invoke the JVM_OnLoad function
4459       JavaThread* thread = JavaThread::current();
4460       ThreadToNativeFromVM ttn(thread);
4461       HandleMark hm(thread);
4462       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4463       if (err != JNI_OK) {
4464         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4465       }
4466     } else {
4467       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4468     }
4469   }
4470 }
4471 


4472 















4473 // Last thread running calls java.lang.Shutdown.shutdown()
4474 void JavaThread::invoke_shutdown_hooks() {
4475   HandleMark hm(this);
4476 
4477   // We could get here with a pending exception, if so clear it now.
4478   if (this->has_pending_exception()) {
4479     this->clear_pending_exception();
4480   }
4481 
4482   EXCEPTION_MARK;
4483   Klass* shutdown_klass =
4484     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4485                                       THREAD);
4486   if (shutdown_klass != NULL) {
4487     // SystemDictionary::resolve_or_null will return null if there was
4488     // an exception.  If we cannot load the Shutdown class, just don't
4489     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
4490     // and finalizers (if runFinalizersOnExit is set) won't be run.
4491     // Note that if a shutdown hook was registered or runFinalizersOnExit
4492     // was called, the Shutdown class would have already been loaded
4493     // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4494     JavaValue result(T_VOID);
4495     JavaCalls::call_static(&result,
4496                            shutdown_klass,
4497                            vmSymbols::shutdown_method_name(),
4498                            vmSymbols::void_method_signature(),
4499                            THREAD);
4500   }
4501   CLEAR_PENDING_EXCEPTION;
4502 }
4503 
4504 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4505 // the program falls off the end of main(). Another VM exit path is through
4506 // vm_exit() when the program calls System.exit() to return a value or when
4507 // there is a serious error in VM. The two shutdown paths are not exactly
4508 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4509 // and VM_Exit op at VM level.
4510 //
4511 // Shutdown sequence:
4512 //   + Shutdown native memory tracking if it is on
4513 //   + Wait until we are the last non-daemon thread to execute
4514 //     <-- every thing is still working at this moment -->
4515 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4516 //        shutdown hooks, run finalizers if finalization-on-exit
4517 //   + Call before_exit(), prepare for VM exit
4518 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4519 //        currently the only user of this mechanism is File.deleteOnExit())
4520 //      > stop StatSampler, watcher thread, CMS threads,
4521 //        post thread end and vm death events to JVMTI,
4522 //        stop signal thread
4523 //   + Call JavaThread::exit(), it will:
4524 //      > release JNI handle blocks, remove stack guard pages
4525 //      > remove this thread from Threads list
4526 //     <-- no more Java code from this thread after this point -->
4527 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4528 //     the compiler threads at safepoint
4529 //     <-- do not use anything that could get blocked by Safepoint -->
4530 //   + Disable tracing at JNI/JVM barriers
4531 //   + Set _vm_exited flag for threads that are still running native code
4532 //   + Delete this thread
4533 //   + Call exit_globals()
4534 //      > deletes tty
4535 //      > deletes PerfMemory resources
4536 //   + Return to caller
4537 
4538 bool Threads::destroy_vm() {
4539   JavaThread* thread = JavaThread::current();
4540 
4541 #ifdef ASSERT
4542   _vm_complete = false;
4543 #endif
4544   // Wait until we are the last non-daemon thread to execute
4545   { MutexLocker nu(Threads_lock);
4546     while (Threads::number_of_non_daemon_threads() > 1)
4547       // This wait should make safepoint checks, wait without a timeout,
4548       // and wait as a suspend-equivalent condition.
4549       Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4550                          Mutex::_as_suspend_equivalent_flag);
4551   }
4552 
4553   // Hang forever on exit if we are reporting an error.
4554   if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4555     os::infinite_sleep();
4556   }
4557   os::wait_for_keypress_at_exit();
4558 
4559   // run Java level shutdown hooks
4560   thread->invoke_shutdown_hooks();
4561 
4562   before_exit(thread);
4563 
4564   thread->exit(true);
4565 
4566   // Stop VM thread.
4567   {
4568     // 4945125 The vm thread comes to a safepoint during exit.
4569     // GC vm_operations can get caught at the safepoint, and the
4570     // heap is unparseable if they are caught. Grab the Heap_lock
4571     // to prevent this. The GC vm_operations will not be able to
4572     // queue until after the vm thread is dead. After this point,
4573     // we'll never emerge out of the safepoint before the VM exits.
4574 
4575     MutexLocker ml(Heap_lock);
4576 
4577     VMThread::wait_for_vm_thread_exit();
4578     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4579     VMThread::destroy();
4580   }
4581 
4582   // clean up ideal graph printers
4583 #if defined(COMPILER2) && !defined(PRODUCT)
4584   IdealGraphPrinter::clean_up();
4585 #endif
4586 
4587   // Now, all Java threads are gone except daemon threads. Daemon threads
4588   // running Java code or in VM are stopped by the Safepoint. However,
4589   // daemon threads executing native code are still running.  But they
4590   // will be stopped at native=>Java/VM barriers. Note that we can't
4591   // simply kill or suspend them, as it is inherently deadlock-prone.
4592 
4593   VM_Exit::set_vm_exited();
4594 
4595   notify_vm_shutdown();
4596 
4597   // We are after VM_Exit::set_vm_exited() so we can't call
4598   // thread->smr_delete() or we will block on the Threads_lock.
4599   // Deleting the shutdown thread here is safe because another
4600   // JavaThread cannot have an active ThreadsListHandle for
4601   // this JavaThread.
4602   delete thread;
4603 
4604 #if INCLUDE_JVMCI
4605   if (JVMCICounterSize > 0) {
4606     FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4607   }
4608 #endif
4609 
4610   // exit_globals() will delete tty
4611   exit_globals();
4612 
4613   LogConfiguration::finalize();
4614 
4615   return true;
4616 }
4617 
4618 
4619 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4620   if (version == JNI_VERSION_1_1) return JNI_TRUE;
4621   return is_supported_jni_version(version);
4622 }
4623 
4624 
4625 jboolean Threads::is_supported_jni_version(jint version) {
4626   if (version == JNI_VERSION_1_2) return JNI_TRUE;
4627   if (version == JNI_VERSION_1_4) return JNI_TRUE;
4628   if (version == JNI_VERSION_1_6) return JNI_TRUE;
4629   if (version == JNI_VERSION_1_8) return JNI_TRUE;
4630   if (version == JNI_VERSION_9) return JNI_TRUE;
4631   if (version == JNI_VERSION_10) return JNI_TRUE;
4632   return JNI_FALSE;
4633 }
4634 
4635 // Hash table of pointers found by a scan. Used for collecting hazard
4636 // pointers (ThreadsList references). Also used for collecting JavaThreads
4637 // that are indirectly referenced by hazard ptrs. An instance of this
4638 // class only contains one type of pointer.
4639 //
4640 class ThreadScanHashtable : public CHeapObj<mtThread> {
4641  private:
4642   static bool ptr_equals(void * const& s1, void * const& s2) {
4643     return s1 == s2;
4644   }
4645 
4646   static unsigned int ptr_hash(void * const& s1) {
4647     return (unsigned int)(((uint32_t)(uintptr_t)s1) * 2654435761u);
4648   }
4649 
4650   int _table_size;
4651   // ResourceHashtable SIZE is specified at compile time so our
4652   // dynamic _table_size is unused for now; 1031 is the first prime
4653   // after 1024.
4654   typedef ResourceHashtable<void *, int, &ThreadScanHashtable::ptr_hash,
4655                             &ThreadScanHashtable::ptr_equals, 1031,
4656                             ResourceObj::C_HEAP, mtThread> PtrTable;
4657   PtrTable * _ptrs;
4658 
4659  public:
4660   // ResourceHashtable is passed to various functions and populated in
4661   // different places so we allocate it using C_HEAP to make it immune
4662   // from any ResourceMarks that happen to be in the code paths.
4663   ThreadScanHashtable(int table_size) : _table_size(table_size), _ptrs(new (ResourceObj::C_HEAP, mtThread) PtrTable()) {}
4664 
4665   ~ThreadScanHashtable() { delete _ptrs; }
4666 
4667   bool has_entry(void *pointer) {
4668     int *val_ptr = _ptrs->get(pointer);
4669     return val_ptr != NULL && *val_ptr == 1;
4670   }
4671 
4672   void add_entry(void *pointer) {
4673     _ptrs->put(pointer, 1);
4674   }
4675 };
4676 
4677 // Closure to gather JavaThreads indirectly referenced by hazard ptrs
4678 // (ThreadsList references) into a hash table. This closure handles part 2
4679 // of the dance - adding all the JavaThreads referenced by the hazard
4680 // pointer (ThreadsList reference) to the hash table.
4681 //
4682 class AddThreadHazardPointerThreadClosure : public ThreadClosure {
4683  private:
4684   ThreadScanHashtable *_table;
4685 
4686  public:
4687   AddThreadHazardPointerThreadClosure(ThreadScanHashtable *table) : _table(table) {}
4688 
4689   virtual void do_thread(Thread *thread) {
4690     if (!_table->has_entry((void*)thread)) {
4691       // The same JavaThread might be on more than one ThreadsList or
4692       // more than one thread might be using the same ThreadsList. In
4693       // either case, we only need a single entry for a JavaThread.
4694       _table->add_entry((void*)thread);
4695     }
4696   }
4697 };
4698 
4699 // Closure to gather JavaThreads indirectly referenced by hazard ptrs
4700 // (ThreadsList references) into a hash table. This closure handles part 1
4701 // of the dance - hazard ptr chain walking and dispatch to another
4702 // closure.
4703 //
4704 class ScanHazardPtrGatherProtectedThreadsClosure : public ThreadClosure {
4705  private:
4706   ThreadScanHashtable *_table;
4707  public:
4708   ScanHazardPtrGatherProtectedThreadsClosure(ThreadScanHashtable *table) : _table(table) {}
4709 
4710   virtual void do_thread(Thread *thread) {
4711     assert_locked_or_safepoint(Threads_lock);
4712 
4713     if (thread == NULL) return;
4714 
4715     // This code races with Threads::acquire_stable_list() which is
4716     // lock-free so we have to handle some special situations.
4717     //
4718     ThreadsList *current_list = NULL;
4719     while (true) {
4720       current_list = thread->get_threads_hazard_ptr();
4721       // No hazard ptr so nothing more to do.
4722       if (current_list == NULL) {
4723         assert(thread->get_nested_threads_hazard_ptr() == NULL,
4724                "cannot have a nested hazard ptr with a NULL regular hazard ptr");
4725         return;
4726       }
4727 
4728       // If the hazard ptr is verified as stable (since it is not tagged),
4729       // then it is safe to use.
4730       if (!Thread::is_hazard_ptr_tagged(current_list)) break;
4731 
4732       // The hazard ptr is tagged as not yet verified as being stable
4733       // so we are racing with acquire_stable_list(). This exchange
4734       // attempts to invalidate the hazard ptr. If we win the race,
4735       // then we can ignore this unstable hazard ptr and the other
4736       // thread will retry the attempt to publish a stable hazard ptr.
4737       // If we lose the race, then we retry our attempt to look at the
4738       // hazard ptr.
4739       if (thread->cmpxchg_threads_hazard_ptr(NULL, current_list) == current_list) return;
4740     }
4741 
4742     // The current JavaThread has a hazard ptr (ThreadsList reference)
4743     // which might be _smr_java_thread_list or it might be an older
4744     // ThreadsList that has been removed but not freed. In either case,
4745     // the hazard ptr is protecting all the JavaThreads on that
4746     // ThreadsList.
4747     AddThreadHazardPointerThreadClosure add_cl(_table);
4748     current_list->threads_do(&add_cl);
4749 
4750     // Any NestedThreadsLists are also protecting JavaThreads so
4751     // gather those also; the ThreadsLists may be different.
4752     for (NestedThreadsList* node = thread->get_nested_threads_hazard_ptr();
4753          node != NULL; node = node->next()) {
4754       node->t_list()->threads_do(&add_cl);
4755     }
4756   }
4757 };
4758 
4759 // Closure to print JavaThreads that have a hazard ptr (ThreadsList
4760 // reference) that contains an indirect reference to a specific JavaThread.
4761 //
4762 class ScanHazardPtrPrintMatchingThreadsClosure : public ThreadClosure {
4763  private:
4764   JavaThread *_thread;
4765  public:
4766   ScanHazardPtrPrintMatchingThreadsClosure(JavaThread *thread) : _thread(thread) {}
4767 
4768   virtual void do_thread(Thread *thread) {
4769     assert_locked_or_safepoint(Threads_lock);
4770 
4771     if (thread == NULL) return;
4772     ThreadsList *current_list = thread->get_threads_hazard_ptr();
4773     if (current_list == NULL) {
4774       assert(thread->get_nested_threads_hazard_ptr() == NULL,
4775              "cannot have a nested hazard ptr with a NULL regular hazard ptr");
4776       return;
4777     }
4778     // If the hazard ptr is unverified, then ignore it.
4779     if (Thread::is_hazard_ptr_tagged(current_list)) return;
4780 
4781     // The current JavaThread has a hazard ptr (ThreadsList reference)
4782     // which might be _smr_java_thread_list or it might be an older
4783     // ThreadsList that has been removed but not freed. In either case,
4784     // the hazard ptr is protecting all the JavaThreads on that
4785     // ThreadsList, but we only care about matching a specific JavaThread.
4786     DO_JAVA_THREADS(current_list, p) {
4787       if (p == _thread) {
4788         log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_delete: thread1=" INTPTR_FORMAT " has a hazard pointer for thread2=" INTPTR_FORMAT, os::current_thread_id(), p2i(thread), p2i(_thread));
4789         break;
4790       }
4791     }
4792 
4793     // Any NestedThreadsLists are also protecting JavaThreads so
4794     // check those also; the ThreadsLists may be different.
4795     for (NestedThreadsList* node = thread->get_nested_threads_hazard_ptr();
4796          node != NULL; node = node->next()) {
4797       DO_JAVA_THREADS(node->t_list(), p) {
4798         if (p == _thread) {
4799           log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_delete: thread1=" INTPTR_FORMAT " has a nested hazard pointer for thread2=" INTPTR_FORMAT, os::current_thread_id(), p2i(thread), p2i(_thread));
4800           return;
4801         }
4802       }
4803     }
4804   }
4805 };
4806 
4807 // Return true if the specified JavaThread is protected by a hazard
4808 // pointer (ThreadsList reference). Otherwise, returns false.
4809 //
4810 bool Threads::is_a_protected_JavaThread(JavaThread *thread) {
4811   assert_locked_or_safepoint(Threads_lock);
4812 
4813   // Hash table size should be first power of two higher than twice
4814   // the length of the Threads list.
4815   int hash_table_size = MIN2(_number_of_threads, 32) << 1;
4816   hash_table_size--;
4817   hash_table_size |= hash_table_size >> 1;
4818   hash_table_size |= hash_table_size >> 2;
4819   hash_table_size |= hash_table_size >> 4;
4820   hash_table_size |= hash_table_size >> 8;
4821   hash_table_size |= hash_table_size >> 16;
4822   hash_table_size++;
4823 
4824   // Gather a hash table of the JavaThreads indirectly referenced by
4825   // hazard ptrs.
4826   ThreadScanHashtable *scan_table = new ThreadScanHashtable(hash_table_size);
4827   ScanHazardPtrGatherProtectedThreadsClosure scan_cl(scan_table);
4828   Threads::threads_do(&scan_cl);
4829 
4830   bool thread_is_protected = false;
4831   if (scan_table->has_entry((void*)thread)) {
4832     thread_is_protected = true;
4833   }
4834   delete scan_table;
4835   return thread_is_protected;
4836 }
4837 
4838 // Safely delete a JavaThread when it is no longer in use by a
4839 // ThreadsListHandle.
4840 //
4841 void Threads::smr_delete(JavaThread *thread) {
4842   assert(!Threads_lock->owned_by_self(), "sanity");
4843 
4844   bool has_logged_once = false;
4845   elapsedTimer timer;
4846   if (EnableThreadSMRStatistics) {
4847     timer.start();
4848   }
4849 
4850   while (true) {
4851     {
4852       // No safepoint check because this JavaThread is not on the
4853       // Threads list.
4854       MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
4855       // Cannot use a MonitorLockerEx helper here because we have
4856       // to drop the Threads_lock first if we wait.
4857       Threads::smr_delete_lock()->lock_without_safepoint_check();
4858       // Set the smr_delete_notify flag after we grab smr_delete_lock
4859       // and before we scan hazard ptrs because we're doing
4860       // double-check locking in release_stable_list().
4861       Threads::set_smr_delete_notify();
4862 
4863       if (!is_a_protected_JavaThread(thread)) {
4864         // This is the common case.
4865         Threads::clear_smr_delete_notify();
4866         Threads::smr_delete_lock()->unlock();
4867         break;
4868       }
4869       if (!has_logged_once) {
4870         has_logged_once = true;
4871         log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_delete: thread=" INTPTR_FORMAT " is not deleted.", os::current_thread_id(), p2i(thread));
4872         if (log_is_enabled(Debug, os, thread)) {
4873           ScanHazardPtrPrintMatchingThreadsClosure scan_cl(thread);
4874           Threads::threads_do(&scan_cl);
4875         }
4876       }
4877     } // We have to drop the Threads_lock to wait or delete the thread
4878 
4879     if (EnableThreadSMRStatistics) {
4880       _smr_delete_lock_wait_cnt++;
4881       if (_smr_delete_lock_wait_cnt > _smr_delete_lock_wait_max) {
4882         _smr_delete_lock_wait_max = _smr_delete_lock_wait_cnt;
4883       }
4884     }
4885     // Wait for a release_stable_list() call before we check again. No
4886     // safepoint check, no timeout, and not as suspend equivalent flag
4887     // because this JavaThread is not on the Threads list.
4888     Threads::smr_delete_lock()->wait(Mutex::_no_safepoint_check_flag, 0,
4889                                      !Mutex::_as_suspend_equivalent_flag);
4890     if (EnableThreadSMRStatistics) {
4891       _smr_delete_lock_wait_cnt--;
4892     }
4893 
4894     Threads::clear_smr_delete_notify();
4895     Threads::smr_delete_lock()->unlock();
4896     // Retry the whole scenario.
4897   }
4898 
4899   if (ThreadLocalHandshakes) {
4900     // The thread is about to be deleted so cancel any handshake.
4901     thread->cancel_handshake();
4902   }
4903 
4904   delete thread;
4905   if (EnableThreadSMRStatistics) {
4906     timer.stop();
4907     uint millis = (uint)timer.milliseconds();
4908     Threads::inc_smr_deleted_thread_cnt();
4909     Threads::add_smr_deleted_thread_times(millis);
4910     Threads::update_smr_deleted_thread_time_max(millis);
4911   }
4912 
4913   log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_delete: thread=" INTPTR_FORMAT " is deleted.", os::current_thread_id(), p2i(thread));
4914 }
4915 
4916 bool Threads::smr_delete_notify() {
4917   // Use load_acquire() in order to see any updates to _smr_delete_notify
4918   // earlier than when smr_delete_lock is grabbed.
4919   return (OrderAccess::load_acquire(&_smr_delete_notify) != 0);
4920 }
4921 
4922 // set_smr_delete_notify() and clear_smr_delete_notify() are called
4923 // under the protection of the smr_delete_lock, but we also use an
4924 // Atomic operation to ensure the memory update is seen earlier than
4925 // when the smr_delete_lock is dropped.
4926 //
4927 void Threads::set_smr_delete_notify() {
4928   Atomic::inc(&_smr_delete_notify);
4929 }
4930 
4931 void Threads::clear_smr_delete_notify() {
4932   Atomic::dec(&_smr_delete_notify);
4933 }
4934 
4935 // Closure to gather hazard ptrs (ThreadsList references) into a hash table.
4936 //
4937 class ScanHazardPtrGatherThreadsListClosure : public ThreadClosure {
4938  private:
4939   ThreadScanHashtable *_table;
4940  public:
4941   ScanHazardPtrGatherThreadsListClosure(ThreadScanHashtable *table) : _table(table) {}
4942 
4943   virtual void do_thread(Thread* thread) {
4944     assert_locked_or_safepoint(Threads_lock);
4945 
4946     if (thread == NULL) return;
4947     ThreadsList *threads = thread->get_threads_hazard_ptr();
4948     if (threads == NULL) {
4949       assert(thread->get_nested_threads_hazard_ptr() == NULL,
4950              "cannot have a nested hazard ptr with a NULL regular hazard ptr");
4951       return;
4952     }
4953     // In this closure we always ignore the tag that might mark this
4954     // hazard ptr as not yet verified. If we happen to catch an
4955     // unverified hazard ptr that is subsequently discarded (not
4956     // published), then the only side effect is that we might keep a
4957     // to-be-deleted ThreadsList alive a little longer.
4958     threads = Thread::untag_hazard_ptr(threads);
4959     if (!_table->has_entry((void*)threads)) {
4960       _table->add_entry((void*)threads);
4961     }
4962 
4963     // Any NestedThreadsLists are also protecting JavaThreads so
4964     // gather those also; the ThreadsLists may be different.
4965     for (NestedThreadsList* node = thread->get_nested_threads_hazard_ptr();
4966          node != NULL; node = node->next()) {
4967       threads = node->t_list();
4968       if (!_table->has_entry((void*)threads)) {
4969         _table->add_entry((void*)threads);
4970       }
4971     }
4972   }
4973 };
4974 
4975 // Safely free a ThreadsList after a Threads::add() or Threads::remove().
4976 // The specified ThreadsList may not get deleted during this call if it
4977 // is still in-use (referenced by a hazard ptr). Other ThreadsLists
4978 // in the chain may get deleted by this call if they are no longer in-use.
4979 void Threads::smr_free_list(ThreadsList* threads) {
4980   assert_locked_or_safepoint(Threads_lock);
4981 
4982   threads->set_next_list(_smr_to_delete_list);
4983   _smr_to_delete_list = threads;
4984   if (EnableThreadSMRStatistics) {
4985     _smr_to_delete_list_cnt++;
4986     if (_smr_to_delete_list_cnt > _smr_to_delete_list_max) {
4987       _smr_to_delete_list_max = _smr_to_delete_list_cnt;
4988     }
4989   }
4990 
4991   // Hash table size should be first power of two higher than twice the length of the ThreadsList
4992   int hash_table_size = MIN2(_number_of_threads, 32) << 1;
4993   hash_table_size--;
4994   hash_table_size |= hash_table_size >> 1;
4995   hash_table_size |= hash_table_size >> 2;
4996   hash_table_size |= hash_table_size >> 4;
4997   hash_table_size |= hash_table_size >> 8;
4998   hash_table_size |= hash_table_size >> 16;
4999   hash_table_size++;
5000 
5001   // Gather a hash table of the current hazard ptrs:
5002   ThreadScanHashtable *scan_table = new ThreadScanHashtable(hash_table_size);
5003   ScanHazardPtrGatherThreadsListClosure scan_cl(scan_table);
5004   Threads::threads_do(&scan_cl);
5005 
5006   // Walk through the linked list of pending freeable ThreadsLists
5007   // and free the ones that are not referenced from hazard ptrs.
5008   ThreadsList* current = _smr_to_delete_list;
5009   ThreadsList* prev = NULL;
5010   ThreadsList* next = NULL;
5011   bool threads_is_freed = false;
5012   while (current != NULL) {
5013     next = current->next_list();
5014     if (!scan_table->has_entry((void*)current)) {
5015       // This ThreadsList is not referenced by a hazard ptr.
5016       if (prev != NULL) {
5017         prev->set_next_list(next);
5018       }
5019       if (_smr_to_delete_list == current) {
5020         _smr_to_delete_list = next;
5021       }
5022 
5023       log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_free_list: threads=" INTPTR_FORMAT " is freed.", os::current_thread_id(), p2i(current));
5024       if (current == threads) threads_is_freed = true;
5025       delete current;
5026       if (EnableThreadSMRStatistics) {
5027         _smr_java_thread_list_free_cnt++;
5028         _smr_to_delete_list_cnt--;
5029       }
5030     } else {
5031       prev = current;
5032     }
5033     current = next;
5034   }
5035 
5036   if (!threads_is_freed) {
5037     // Only report "is not freed" on the original call to
5038     // smr_free_list() for this ThreadsList.
5039     log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_free_list: threads=" INTPTR_FORMAT " is not freed.", os::current_thread_id(), p2i(threads));
5040   }
5041 
5042   delete scan_table;
5043 }
5044 
5045 // Remove a JavaThread from a ThreadsList. The returned ThreadsList is a
5046 // new copy of the specified ThreadsList with the specified JavaThread
5047 // removed.
5048 ThreadsList *ThreadsList::remove_thread(ThreadsList* list, JavaThread* java_thread) {
5049   assert(list->_length > 0, "sanity");
5050 
5051   uint i = 0;
5052   DO_JAVA_THREADS(list, current) {
5053     if (current == java_thread) {
5054       break;
5055     }
5056     i++;
5057   }
5058   assert(i < list->_length, "did not find JavaThread on the list");
5059   const uint index = i;
5060   const uint new_length = list->_length - 1;
5061   const uint head_length = index;
5062   const uint tail_length = (new_length >= index) ? (new_length - index) : 0;
5063   ThreadsList *const new_list = new ThreadsList(new_length);
5064 
5065   if (head_length > 0) {
5066     Copy::disjoint_words((HeapWord*)list->_threads, (HeapWord*)new_list->_threads, head_length);
5067   }
5068   if (tail_length > 0) {
5069     Copy::disjoint_words((HeapWord*)list->_threads + index + 1, (HeapWord*)new_list->_threads + index, tail_length);
5070   }
5071 
5072   return new_list;
5073 }
5074 
5075 // Add a JavaThread to a ThreadsList. The returned ThreadsList is a
5076 // new copy of the specified ThreadsList with the specified JavaThread
5077 // appended to the end.
5078 ThreadsList *ThreadsList::add_thread(ThreadsList *list, JavaThread *java_thread) {
5079   const uint index = list->_length;
5080   const uint new_length = index + 1;
5081   const uint head_length = index;
5082   ThreadsList *const new_list = new ThreadsList(new_length);
5083 
5084   if (head_length > 0) {
5085     Copy::disjoint_words((HeapWord*)list->_threads, (HeapWord*)new_list->_threads, head_length);
5086   }
5087   *(JavaThread**)(new_list->_threads + index) = java_thread;
5088 
5089   return new_list;
5090 }
5091 
5092 int ThreadsList::find_index_of_JavaThread(JavaThread *target) {
5093   if (target == NULL) {
5094     return -1;
5095   }
5096   for (uint i = 0; i < length(); i++) {
5097     if (target == thread_at(i)) {
5098       return (int)i;
5099     }
5100   }
5101   return -1;
5102 }
5103 
5104 JavaThread* ThreadsList::find_JavaThread_from_java_tid(jlong java_tid) const {
5105   DO_JAVA_THREADS(this, thread) {
5106     oop tobj = thread->threadObj();
5107     // Ignore the thread if it hasn't run yet, has exited
5108     // or is starting to exit.
5109     if (tobj != NULL && !thread->is_exiting() &&
5110         java_tid == java_lang_Thread::thread_id(tobj)) {
5111       // found a match
5112       return thread;
5113     }
5114   }
5115   return NULL;
5116 }
5117 
5118 bool ThreadsList::includes(const JavaThread * const p) const {
5119   if (p == NULL) {
5120     return false;
5121   }
5122   DO_JAVA_THREADS(this, q) {
5123     if (q == p) {
5124       return true;
5125     }
5126   }
5127   return false;
5128 }
5129 
5130 void Threads::add(JavaThread* p, bool force_daemon) {
5131   // The threads lock must be owned at this point
5132   assert_locked_or_safepoint(Threads_lock);
5133 
5134   // See the comment for this method in thread.hpp for its purpose and
5135   // why it is called here.
5136   p->initialize_queues();
5137   p->set_next(_thread_list);
5138   _thread_list = p;
5139 
5140   // Once a JavaThread is added to the Threads list, smr_delete() has
5141   // to be used to delete it. Otherwise we can just delete it directly.
5142   p->set_on_thread_list();
5143 
5144   _number_of_threads++;
5145   oop threadObj = p->threadObj();
5146   bool daemon = true;
5147   // Bootstrapping problem: threadObj can be null for initial
5148   // JavaThread (or for threads attached via JNI)
5149   if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
5150     _number_of_non_daemon_threads++;
5151     daemon = false;
5152   }
5153 
5154   ThreadService::add_thread(p, daemon);
5155 
5156   // Maintain fast thread list
5157   ThreadsList *new_list = ThreadsList::add_thread(get_smr_java_thread_list(), p);
5158   if (EnableThreadSMRStatistics) {
5159     _smr_java_thread_list_alloc_cnt++;
5160     if (new_list->length() > _smr_java_thread_list_max) {
5161       _smr_java_thread_list_max = new_list->length();
5162     }
5163   }
5164   // Initial _smr_java_thread_list will not generate a "Threads::add" mesg.
5165   log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::add: new ThreadsList=" INTPTR_FORMAT, os::current_thread_id(), p2i(new_list));
5166 
5167   ThreadsList *old_list = xchg_smr_java_thread_list(new_list);
5168   smr_free_list(old_list);
5169 
5170   // Possible GC point.
5171   Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
5172 }
5173 
5174 void Threads::remove(JavaThread* p) {
5175 
5176   // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
5177   ObjectSynchronizer::omFlush(p);
5178 
5179   // Extra scope needed for Thread_lock, so we can check
5180   // that we do not remove thread without safepoint code notice
5181   { MutexLocker ml(Threads_lock);
5182 
5183     assert(get_smr_java_thread_list()->includes(p), "p must be present");
5184 
5185     // Maintain fast thread list
5186     ThreadsList *new_list = ThreadsList::remove_thread(get_smr_java_thread_list(), p);
5187     if (EnableThreadSMRStatistics) {
5188       _smr_java_thread_list_alloc_cnt++;
5189       // This list is smaller so no need to check for a "longest" update.
5190     }
5191 
5192     // Final _smr_java_thread_list will not generate a "Threads::remove" mesg.
5193     log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::remove: new ThreadsList=" INTPTR_FORMAT, os::current_thread_id(), p2i(new_list));
5194 
5195     ThreadsList *old_list = xchg_smr_java_thread_list(new_list);
5196     smr_free_list(old_list);
5197 
5198     JavaThread* current = _thread_list;
5199     JavaThread* prev    = NULL;
5200 
5201     while (current != p) {
5202       prev    = current;
5203       current = current->next();
5204     }
5205 
5206     if (prev) {
5207       prev->set_next(current->next());
5208     } else {
5209       _thread_list = p->next();
5210     }
5211 
5212     _number_of_threads--;
5213     oop threadObj = p->threadObj();
5214     bool daemon = true;
5215     if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
5216       _number_of_non_daemon_threads--;
5217       daemon = false;
5218 
5219       // Only one thread left, do a notify on the Threads_lock so a thread waiting
5220       // on destroy_vm will wake up.
5221       if (number_of_non_daemon_threads() == 1) {
5222         Threads_lock->notify_all();
5223       }
5224     }
5225     ThreadService::remove_thread(p, daemon);
5226 
5227     // Make sure that safepoint code disregard this thread. This is needed since
5228     // the thread might mess around with locks after this point. This can cause it
5229     // to do callbacks into the safepoint code. However, the safepoint code is not aware
5230     // of this thread since it is removed from the queue.
5231     p->set_terminated_value();
5232   } // unlock Threads_lock
5233 
5234   // Since Events::log uses a lock, we grab it outside the Threads_lock
5235   Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
5236 }
5237 











5238 // Operations on the Threads list for GC.  These are not explicitly locked,
5239 // but the garbage collector must provide a safe context for them to run.
5240 // In particular, these things should never be called when the Threads_lock
5241 // is held by some other thread. (Note: the Safepoint abstraction also
5242 // uses the Threads_lock to guarantee this property. It also makes sure that
5243 // all threads gets blocked when exiting or starting).
5244 
5245 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
5246   ALL_JAVA_THREADS(p) {
5247     p->oops_do(f, cf);
5248   }
5249   VMThread::vm_thread()->oops_do(f, cf);
5250 }
5251 
5252 void Threads::change_thread_claim_parity() {
5253   // Set the new claim parity.
5254   assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
5255          "Not in range.");
5256   _thread_claim_parity++;
5257   if (_thread_claim_parity == 3) _thread_claim_parity = 1;
5258   assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
5259          "Not in range.");
5260 }
5261 
5262 #ifdef ASSERT
5263 void Threads::assert_all_threads_claimed() {
5264   ALL_JAVA_THREADS(p) {
5265     const int thread_parity = p->oops_do_parity();
5266     assert((thread_parity == _thread_claim_parity),
5267            "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
5268   }
5269   VMThread* vmt = VMThread::vm_thread();
5270   const int thread_parity = vmt->oops_do_parity();
5271   assert((thread_parity == _thread_claim_parity),
5272          "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity);
5273 }
5274 #endif // ASSERT
5275 
5276 class ParallelOopsDoThreadClosure : public ThreadClosure {
5277 private:
5278   OopClosure* _f;
5279   CodeBlobClosure* _cf;
5280 public:
5281   ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
5282   void do_thread(Thread* t) {
5283     t->oops_do(_f, _cf);
5284   }
5285 };
5286 
5287 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
5288   ParallelOopsDoThreadClosure tc(f, cf);
5289   possibly_parallel_threads_do(is_par, &tc);
5290 }
5291 
5292 #if INCLUDE_ALL_GCS
5293 // Used by ParallelScavenge
5294 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
5295   ALL_JAVA_THREADS(p) {
5296     q->enqueue(new ThreadRootsTask(p));
5297   }
5298   q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
5299 }
5300 
5301 // Used by Parallel Old
5302 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
5303   ALL_JAVA_THREADS(p) {
5304     q->enqueue(new ThreadRootsMarkingTask(p));
5305   }
5306   q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
5307 }
5308 #endif // INCLUDE_ALL_GCS
5309 
5310 void Threads::nmethods_do(CodeBlobClosure* cf) {
5311   ALL_JAVA_THREADS(p) {
5312     // This is used by the code cache sweeper to mark nmethods that are active
5313     // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
5314     // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
5315     if(!p->is_Code_cache_sweeper_thread()) {
5316       p->nmethods_do(cf);
5317     }
5318   }
5319 }
5320 
5321 void Threads::metadata_do(void f(Metadata*)) {
5322   ALL_JAVA_THREADS(p) {
5323     p->metadata_do(f);
5324   }
5325 }
5326 
5327 class ThreadHandlesClosure : public ThreadClosure {
5328   void (*_f)(Metadata*);
5329  public:
5330   ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
5331   virtual void do_thread(Thread* thread) {
5332     thread->metadata_handles_do(_f);
5333   }
5334 };
5335 
5336 void Threads::metadata_handles_do(void f(Metadata*)) {
5337   // Only walk the Handles in Thread.
5338   ThreadHandlesClosure handles_closure(f);
5339   threads_do(&handles_closure);
5340 }
5341 
5342 void Threads::deoptimized_wrt_marked_nmethods() {
5343   ALL_JAVA_THREADS(p) {
5344     p->deoptimized_wrt_marked_nmethods();
5345   }
5346 }
5347 
5348 
5349 // Get count Java threads that are waiting to enter the specified monitor.
5350 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
5351                                                          int count,
5352                                                          address monitor) {


5353   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
5354 
5355   int i = 0;
5356   DO_JAVA_THREADS(t_list, p) {


5357     if (!p->can_call_java()) continue;
5358 
5359     address pending = (address)p->current_pending_monitor();
5360     if (pending == monitor) {             // found a match
5361       if (i < count) result->append(p);   // save the first count matches
5362       i++;
5363     }
5364   }
5365 
5366   return result;
5367 }
5368 
5369 
5370 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
5371                                                       address owner) {





5372   // NULL owner means not locked so we can skip the search
5373   if (owner == NULL) return NULL;
5374 
5375   DO_JAVA_THREADS(t_list, p) {


5376     // first, see if owner is the address of a Java thread
5377     if (owner == (address)p) return p;
5378   }
5379 
5380   // Cannot assert on lack of success here since this function may be
5381   // used by code that is trying to report useful problem information
5382   // like deadlock detection.
5383   if (UseHeavyMonitors) return NULL;
5384 
5385   // If we didn't find a matching Java thread and we didn't force use of
5386   // heavyweight monitors, then the owner is the stack address of the
5387   // Lock Word in the owning Java thread's stack.
5388   //
5389   JavaThread* the_owner = NULL;
5390   DO_JAVA_THREADS(t_list, q) {


5391     if (q->is_lock_owned(owner)) {
5392       the_owner = q;
5393       break;
5394     }
5395   }
5396 
5397   // cannot assert on lack of success here; see above comment
5398   return the_owner;
5399 }
5400 
5401 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
5402 void Threads::print_on(outputStream* st, bool print_stacks,
5403                        bool internal_format, bool print_concurrent_locks) {
5404   char buf[32];
5405   st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
5406 
5407   st->print_cr("Full thread dump %s (%s %s):",
5408                Abstract_VM_Version::vm_name(),
5409                Abstract_VM_Version::vm_release(),
5410                Abstract_VM_Version::vm_info_string());
5411   st->cr();
5412 
5413 #if INCLUDE_SERVICES
5414   // Dump concurrent locks
5415   ConcurrentLocksDump concurrent_locks;
5416   if (print_concurrent_locks) {
5417     concurrent_locks.dump_at_safepoint();
5418   }
5419 #endif // INCLUDE_SERVICES
5420 
5421   print_smr_info_on(st);
5422   st->cr();
5423 
5424   ALL_JAVA_THREADS(p) {
5425     ResourceMark rm;
5426     p->print_on(st);
5427     if (print_stacks) {
5428       if (internal_format) {
5429         p->trace_stack();
5430       } else {
5431         p->print_stack_on(st);
5432       }
5433     }
5434     st->cr();
5435 #if INCLUDE_SERVICES
5436     if (print_concurrent_locks) {
5437       concurrent_locks.print_locks_on(p, st);
5438     }
5439 #endif // INCLUDE_SERVICES
5440   }
5441 
5442   VMThread::vm_thread()->print_on(st);
5443   st->cr();
5444   Universe::heap()->print_gc_threads_on(st);
5445   WatcherThread* wt = WatcherThread::watcher_thread();
5446   if (wt != NULL) {
5447     wt->print_on(st);
5448     st->cr();
5449   }
5450 
5451   st->flush();
5452 }
5453 
5454 // Log Threads class SMR info.
5455 void Threads::log_smr_statistics() {
5456   LogTarget(Info, thread, smr) log;
5457   if (log.is_enabled()) {
5458     LogStream out(log);
5459     print_smr_info_on(&out);
5460   }
5461 }
5462 
5463 // Print Threads class SMR info.
5464 void Threads::print_smr_info_on(outputStream* st) {
5465   // Only grab the Threads_lock if we don't already own it
5466   // and if we are not reporting an error.
5467   MutexLockerEx ml((Threads_lock->owned_by_self() || VMError::is_error_reported()) ? NULL : Threads_lock);
5468 
5469   st->print_cr("Threads class SMR info:");
5470   st->print_cr("_smr_java_thread_list=" INTPTR_FORMAT ", length=%u, "
5471                "elements={", p2i(_smr_java_thread_list),
5472                _smr_java_thread_list->length());
5473   print_smr_info_elements_on(st, _smr_java_thread_list);
5474   st->print_cr("}");
5475   if (_smr_to_delete_list != NULL) {
5476     st->print_cr("_smr_to_delete_list=" INTPTR_FORMAT ", length=%u, "
5477                  "elements={", p2i(_smr_to_delete_list),
5478                  _smr_to_delete_list->length());
5479     print_smr_info_elements_on(st, _smr_to_delete_list);
5480     st->print_cr("}");
5481     for (ThreadsList *t_list = _smr_to_delete_list->next_list();
5482          t_list != NULL; t_list = t_list->next_list()) {
5483       st->print("next-> " INTPTR_FORMAT ", length=%u, "
5484                 "elements={", p2i(t_list), t_list->length());
5485       print_smr_info_elements_on(st, t_list);
5486       st->print_cr("}");
5487     }
5488   }
5489   if (!EnableThreadSMRStatistics) {
5490     return;
5491   }
5492   st->print_cr("_smr_java_thread_list_alloc_cnt=" UINT64_FORMAT ","
5493                "_smr_java_thread_list_free_cnt=" UINT64_FORMAT ","
5494                "_smr_java_thread_list_max=%u, "
5495                "_smr_nested_thread_list_max=%u",
5496                _smr_java_thread_list_alloc_cnt,
5497                _smr_java_thread_list_free_cnt,
5498                _smr_java_thread_list_max,
5499                _smr_nested_thread_list_max);
5500   if (_smr_tlh_cnt > 0) {
5501     st->print_cr("_smr_tlh_cnt=%u"
5502                  ", _smr_tlh_times=%u"
5503                  ", avg_smr_tlh_time=%0.2f"
5504                  ", _smr_tlh_time_max=%u",
5505                  _smr_tlh_cnt, _smr_tlh_times,
5506                  ((double) _smr_tlh_times / _smr_tlh_cnt),
5507                  _smr_tlh_time_max);
5508   }
5509   if (_smr_deleted_thread_cnt > 0) {
5510     st->print_cr("_smr_deleted_thread_cnt=%u"
5511                  ", _smr_deleted_thread_times=%u"
5512                  ", avg_smr_deleted_thread_time=%0.2f"
5513                  ", _smr_deleted_thread_time_max=%u",
5514                  _smr_deleted_thread_cnt, _smr_deleted_thread_times,
5515                  ((double) _smr_deleted_thread_times / _smr_deleted_thread_cnt),
5516                  _smr_deleted_thread_time_max);
5517   }
5518   st->print_cr("_smr_delete_lock_wait_cnt=%u, _smr_delete_lock_wait_max=%u",
5519                _smr_delete_lock_wait_cnt, _smr_delete_lock_wait_max);
5520   st->print_cr("_smr_to_delete_list_cnt=%u, _smr_to_delete_list_max=%u",
5521                _smr_to_delete_list_cnt, _smr_to_delete_list_max);
5522 }
5523 
5524 // Print ThreadsList elements (4 per line).
5525 void Threads::print_smr_info_elements_on(outputStream* st,
5526                                          ThreadsList* t_list) {
5527   uint cnt = 0;
5528   JavaThreadIterator jti(t_list);
5529   for (JavaThread *jt = jti.first(); jt != NULL; jt = jti.next()) {
5530     st->print(INTPTR_FORMAT, p2i(jt));
5531     if (cnt < t_list->length() - 1) {
5532       // Separate with comma or comma-space except for the last one.
5533       if (((cnt + 1) % 4) == 0) {
5534         // Four INTPTR_FORMAT fit on an 80 column line so end the
5535         // current line with just a comma.
5536         st->print_cr(",");
5537       } else {
5538         // Not the last one on the current line so use comma-space:
5539         st->print(", ");
5540       }
5541     } else {
5542       // Last one so just end the current line.
5543       st->cr();
5544     }
5545     cnt++;
5546   }
5547 }
5548 
5549 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
5550                              int buflen, bool* found_current) {
5551   if (this_thread != NULL) {
5552     bool is_current = (current == this_thread);
5553     *found_current = *found_current || is_current;
5554     st->print("%s", is_current ? "=>" : "  ");
5555 
5556     st->print(PTR_FORMAT, p2i(this_thread));
5557     st->print(" ");
5558     this_thread->print_on_error(st, buf, buflen);
5559     st->cr();
5560   }
5561 }
5562 
5563 class PrintOnErrorClosure : public ThreadClosure {
5564   outputStream* _st;
5565   Thread* _current;
5566   char* _buf;
5567   int _buflen;
5568   bool* _found_current;
5569  public:
5570   PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
5571                       int buflen, bool* found_current) :
5572    _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
5573 
5574   virtual void do_thread(Thread* thread) {
5575     Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
5576   }
5577 };
5578 
5579 // Threads::print_on_error() is called by fatal error handler. It's possible
5580 // that VM is not at safepoint and/or current thread is inside signal handler.
5581 // Don't print stack trace, as the stack may not be walkable. Don't allocate
5582 // memory (even in resource area), it might deadlock the error handler.
5583 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
5584                              int buflen) {
5585   print_smr_info_on(st);
5586   st->cr();
5587 
5588   bool found_current = false;
5589   st->print_cr("Java Threads: ( => current thread )");
5590   ALL_JAVA_THREADS(thread) {
5591     print_on_error(thread, st, current, buf, buflen, &found_current);
5592   }
5593   st->cr();
5594 
5595   st->print_cr("Other Threads:");
5596   print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
5597   print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
5598 
5599   PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
5600   Universe::heap()->gc_threads_do(&print_closure);
5601 
5602   if (!found_current) {
5603     st->cr();
5604     st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
5605     current->print_on_error(st, buf, buflen);
5606     st->cr();
5607   }
5608   st->cr();
5609 
5610   st->print_cr("Threads with active compile tasks:");
5611   print_threads_compiling(st, buf, buflen);
5612 }
5613 
5614 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
5615   ALL_JAVA_THREADS(thread) {
5616     if (thread->is_Compiler_thread()) {
5617       CompilerThread* ct = (CompilerThread*) thread;
5618       if (ct->task() != NULL) {
5619         thread->print_name_on_error(st, buf, buflen);
5620         ct->task()->print(st, NULL, true, true);
5621       }
5622     }
5623   }
5624 }
5625 
5626 
5627 // Internal SpinLock and Mutex
5628 // Based on ParkEvent
5629 
5630 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
5631 //
5632 // We employ SpinLocks _only for low-contention, fixed-length
5633 // short-duration critical sections where we're concerned
5634 // about native mutex_t or HotSpot Mutex:: latency.
5635 // The mux construct provides a spin-then-block mutual exclusion
5636 // mechanism.
5637 //
5638 // Testing has shown that contention on the ListLock guarding gFreeList
5639 // is common.  If we implement ListLock as a simple SpinLock it's common
5640 // for the JVM to devolve to yielding with little progress.  This is true
5641 // despite the fact that the critical sections protected by ListLock are
5642 // extremely short.
5643 //
5644 // TODO-FIXME: ListLock should be of type SpinLock.
5645 // We should make this a 1st-class type, integrated into the lock
5646 // hierarchy as leaf-locks.  Critically, the SpinLock structure
5647 // should have sufficient padding to avoid false-sharing and excessive
5648 // cache-coherency traffic.
5649 
5650 
5651 typedef volatile int SpinLockT;
5652 
5653 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
5654   if (Atomic::cmpxchg (1, adr, 0) == 0) {
5655     return;   // normal fast-path return
5656   }
5657 
5658   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
5659   TEVENT(SpinAcquire - ctx);
5660   int ctr = 0;
5661   int Yields = 0;
5662   for (;;) {
5663     while (*adr != 0) {
5664       ++ctr;
5665       if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
5666         if (Yields > 5) {
5667           os::naked_short_sleep(1);
5668         } else {
5669           os::naked_yield();
5670           ++Yields;
5671         }
5672       } else {
5673         SpinPause();
5674       }
5675     }
5676     if (Atomic::cmpxchg(1, adr, 0) == 0) return;
5677   }
5678 }
5679 
5680 void Thread::SpinRelease(volatile int * adr) {
5681   assert(*adr != 0, "invariant");
5682   OrderAccess::fence();      // guarantee at least release consistency.
5683   // Roach-motel semantics.
5684   // It's safe if subsequent LDs and STs float "up" into the critical section,
5685   // but prior LDs and STs within the critical section can't be allowed
5686   // to reorder or float past the ST that releases the lock.
5687   // Loads and stores in the critical section - which appear in program
5688   // order before the store that releases the lock - must also appear
5689   // before the store that releases the lock in memory visibility order.
5690   // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
5691   // the ST of 0 into the lock-word which releases the lock, so fence
5692   // more than covers this on all platforms.
5693   *adr = 0;
5694 }
5695 
5696 // muxAcquire and muxRelease:
5697 //
5698 // *  muxAcquire and muxRelease support a single-word lock-word construct.
5699 //    The LSB of the word is set IFF the lock is held.
5700 //    The remainder of the word points to the head of a singly-linked list
5701 //    of threads blocked on the lock.
5702 //
5703 // *  The current implementation of muxAcquire-muxRelease uses its own
5704 //    dedicated Thread._MuxEvent instance.  If we're interested in
5705 //    minimizing the peak number of extant ParkEvent instances then
5706 //    we could eliminate _MuxEvent and "borrow" _ParkEvent as long
5707 //    as certain invariants were satisfied.  Specifically, care would need
5708 //    to be taken with regards to consuming unpark() "permits".
5709 //    A safe rule of thumb is that a thread would never call muxAcquire()
5710 //    if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
5711 //    park().  Otherwise the _ParkEvent park() operation in muxAcquire() could
5712 //    consume an unpark() permit intended for monitorenter, for instance.
5713 //    One way around this would be to widen the restricted-range semaphore
5714 //    implemented in park().  Another alternative would be to provide
5715 //    multiple instances of the PlatformEvent() for each thread.  One
5716 //    instance would be dedicated to muxAcquire-muxRelease, for instance.
5717 //
5718 // *  Usage:
5719 //    -- Only as leaf locks
5720 //    -- for short-term locking only as muxAcquire does not perform
5721 //       thread state transitions.
5722 //
5723 // Alternatives:
5724 // *  We could implement muxAcquire and muxRelease with MCS or CLH locks
5725 //    but with parking or spin-then-park instead of pure spinning.
5726 // *  Use Taura-Oyama-Yonenzawa locks.
5727 // *  It's possible to construct a 1-0 lock if we encode the lockword as
5728 //    (List,LockByte).  Acquire will CAS the full lockword while Release
5729 //    will STB 0 into the LockByte.  The 1-0 scheme admits stranding, so
5730 //    acquiring threads use timers (ParkTimed) to detect and recover from
5731 //    the stranding window.  Thread/Node structures must be aligned on 256-byte
5732 //    boundaries by using placement-new.
5733 // *  Augment MCS with advisory back-link fields maintained with CAS().
5734 //    Pictorially:  LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
5735 //    The validity of the backlinks must be ratified before we trust the value.
5736 //    If the backlinks are invalid the exiting thread must back-track through the
5737 //    the forward links, which are always trustworthy.
5738 // *  Add a successor indication.  The LockWord is currently encoded as
5739 //    (List, LOCKBIT:1).  We could also add a SUCCBIT or an explicit _succ variable
5740 //    to provide the usual futile-wakeup optimization.
5741 //    See RTStt for details.
5742 // *  Consider schedctl.sc_nopreempt to cover the critical section.
5743 //
5744 
5745 
5746 const intptr_t LOCKBIT = 1;
5747 
5748 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
5749   intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
5750   if (w == 0) return;
5751   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5752     return;
5753   }
5754 
5755   TEVENT(muxAcquire - Contention);
5756   ParkEvent * const Self = Thread::current()->_MuxEvent;
5757   assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
5758   for (;;) {
5759     int its = (os::is_MP() ? 100 : 0) + 1;
5760 
5761     // Optional spin phase: spin-then-park strategy
5762     while (--its >= 0) {
5763       w = *Lock;
5764       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5765         return;
5766       }
5767     }
5768 
5769     Self->reset();
5770     Self->OnList = intptr_t(Lock);
5771     // The following fence() isn't _strictly necessary as the subsequent
5772     // CAS() both serializes execution and ratifies the fetched *Lock value.
5773     OrderAccess::fence();
5774     for (;;) {
5775       w = *Lock;
5776       if ((w & LOCKBIT) == 0) {
5777         if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5778           Self->OnList = 0;   // hygiene - allows stronger asserts
5779           return;
5780         }
5781         continue;      // Interference -- *Lock changed -- Just retry
5782       }
5783       assert(w & LOCKBIT, "invariant");
5784       Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
5785       if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
5786     }
5787 
5788     while (Self->OnList != 0) {
5789       Self->park();
5790     }
5791   }
5792 }
5793 
5794 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
5795   intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
5796   if (w == 0) return;
5797   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5798     return;
5799   }
5800 
5801   TEVENT(muxAcquire - Contention);
5802   ParkEvent * ReleaseAfter = NULL;
5803   if (ev == NULL) {
5804     ev = ReleaseAfter = ParkEvent::Allocate(NULL);
5805   }
5806   assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
5807   for (;;) {
5808     guarantee(ev->OnList == 0, "invariant");
5809     int its = (os::is_MP() ? 100 : 0) + 1;
5810 
5811     // Optional spin phase: spin-then-park strategy
5812     while (--its >= 0) {
5813       w = *Lock;
5814       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5815         if (ReleaseAfter != NULL) {
5816           ParkEvent::Release(ReleaseAfter);
5817         }
5818         return;
5819       }
5820     }
5821 
5822     ev->reset();
5823     ev->OnList = intptr_t(Lock);
5824     // The following fence() isn't _strictly necessary as the subsequent
5825     // CAS() both serializes execution and ratifies the fetched *Lock value.
5826     OrderAccess::fence();
5827     for (;;) {
5828       w = *Lock;
5829       if ((w & LOCKBIT) == 0) {
5830         if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5831           ev->OnList = 0;
5832           // We call ::Release while holding the outer lock, thus
5833           // artificially lengthening the critical section.
5834           // Consider deferring the ::Release() until the subsequent unlock(),
5835           // after we've dropped the outer lock.
5836           if (ReleaseAfter != NULL) {
5837             ParkEvent::Release(ReleaseAfter);
5838           }
5839           return;
5840         }
5841         continue;      // Interference -- *Lock changed -- Just retry
5842       }
5843       assert(w & LOCKBIT, "invariant");
5844       ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
5845       if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
5846     }
5847 
5848     while (ev->OnList != 0) {
5849       ev->park();
5850     }
5851   }
5852 }
5853 
5854 // Release() must extract a successor from the list and then wake that thread.
5855 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
5856 // similar to that used by ParkEvent::Allocate() and ::Release().  DMR-based
5857 // Release() would :
5858 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
5859 // (B) Extract a successor from the private list "in-hand"
5860 // (C) attempt to CAS() the residual back into *Lock over null.
5861 //     If there were any newly arrived threads and the CAS() would fail.
5862 //     In that case Release() would detach the RATs, re-merge the list in-hand
5863 //     with the RATs and repeat as needed.  Alternately, Release() might
5864 //     detach and extract a successor, but then pass the residual list to the wakee.
5865 //     The wakee would be responsible for reattaching and remerging before it
5866 //     competed for the lock.
5867 //
5868 // Both "pop" and DMR are immune from ABA corruption -- there can be
5869 // multiple concurrent pushers, but only one popper or detacher.
5870 // This implementation pops from the head of the list.  This is unfair,
5871 // but tends to provide excellent throughput as hot threads remain hot.
5872 // (We wake recently run threads first).
5873 //
5874 // All paths through muxRelease() will execute a CAS.
5875 // Release consistency -- We depend on the CAS in muxRelease() to provide full
5876 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
5877 // executed within the critical section are complete and globally visible before the
5878 // store (CAS) to the lock-word that releases the lock becomes globally visible.
5879 void Thread::muxRelease(volatile intptr_t * Lock)  {
5880   for (;;) {
5881     const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
5882     assert(w & LOCKBIT, "invariant");
5883     if (w == LOCKBIT) return;
5884     ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
5885     assert(List != NULL, "invariant");
5886     assert(List->OnList == intptr_t(Lock), "invariant");
5887     ParkEvent * const nxt = List->ListNext;
5888     guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
5889 
5890     // The following CAS() releases the lock and pops the head element.
5891     // The CAS() also ratifies the previously fetched lock-word value.
5892     if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
5893       continue;
5894     }
5895     List->OnList = 0;
5896     OrderAccess::fence();
5897     List->unpark();
5898     return;
5899   }
5900 }
5901 
5902 
5903 void Threads::verify() {
5904   ALL_JAVA_THREADS(p) {
5905     p->verify();
5906   }
5907   VMThread* thread = VMThread::vm_thread();
5908   if (thread != NULL) thread->verify();
5909 }
--- EOF ---