1 /*
   2  * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/classLoader.hpp"
  27 #include "classfile/javaClasses.hpp"
  28 #include "classfile/moduleEntry.hpp"
  29 #include "classfile/systemDictionary.hpp"
  30 #include "classfile/vmSymbols.hpp"
  31 #include "code/codeCache.hpp"
  32 #include "code/scopeDesc.hpp"
  33 #include "compiler/compileBroker.hpp"
  34 #include "compiler/compileTask.hpp"
  35 #include "gc/shared/gcId.hpp"
  36 #include "gc/shared/gcLocker.inline.hpp"
  37 #include "gc/shared/workgroup.hpp"
  38 #include "interpreter/interpreter.hpp"
  39 #include "interpreter/linkResolver.hpp"
  40 #include "interpreter/oopMapCache.hpp"
  41 #include "jvmtifiles/jvmtiEnv.hpp"
  42 #include "logging/log.hpp"
  43 #include "logging/logConfiguration.hpp"
  44 #include "memory/metaspaceShared.hpp"
  45 #include "memory/oopFactory.hpp"
  46 #include "memory/resourceArea.hpp"
  47 #include "memory/universe.inline.hpp"
  48 #include "oops/instanceKlass.hpp"
  49 #include "oops/objArrayOop.hpp"
  50 #include "oops/oop.inline.hpp"
  51 #include "oops/symbol.hpp"
  52 #include "oops/verifyOopClosure.hpp"
  53 #include "prims/jvm.h"
  54 #include "prims/jvm_misc.hpp"
  55 #include "prims/jvmtiExport.hpp"
  56 #include "prims/jvmtiThreadState.hpp"
  57 #include "prims/privilegedStack.hpp"
  58 #include "runtime/arguments.hpp"
  59 #include "runtime/atomic.hpp"
  60 #include "runtime/biasedLocking.hpp"
  61 #include "runtime/commandLineFlagConstraintList.hpp"
  62 #include "runtime/commandLineFlagWriteableList.hpp"
  63 #include "runtime/commandLineFlagRangeList.hpp"
  64 #include "runtime/deoptimization.hpp"
  65 #include "runtime/fprofiler.hpp"
  66 #include "runtime/frame.inline.hpp"
  67 #include "runtime/globals.hpp"
  68 #include "runtime/init.hpp"
  69 #include "runtime/interfaceSupport.hpp"
  70 #include "runtime/java.hpp"
  71 #include "runtime/javaCalls.hpp"
  72 #include "runtime/jniPeriodicChecker.hpp"
  73 #include "runtime/timerTrace.hpp"
  74 #include "runtime/memprofiler.hpp"
  75 #include "runtime/mutexLocker.hpp"
  76 #include "runtime/objectMonitor.hpp"
  77 #include "runtime/orderAccess.inline.hpp"
  78 #include "runtime/osThread.hpp"
  79 #include "runtime/safepoint.hpp"
  80 #include "runtime/sharedRuntime.hpp"
  81 #include "runtime/statSampler.hpp"
  82 #include "runtime/stubRoutines.hpp"
  83 #include "runtime/sweeper.hpp"
  84 #include "runtime/task.hpp"
  85 #include "runtime/thread.inline.hpp"
  86 #include "runtime/threadCritical.hpp"
  87 #include "runtime/vframe.hpp"
  88 #include "runtime/vframeArray.hpp"
  89 #include "runtime/vframe_hp.hpp"
  90 #include "runtime/vmThread.hpp"
  91 #include "runtime/vm_operations.hpp"
  92 #include "runtime/vm_version.hpp"
  93 #include "services/attachListener.hpp"
  94 #include "services/management.hpp"
  95 #include "services/memTracker.hpp"
  96 #include "services/threadService.hpp"
  97 #include "trace/traceMacros.hpp"
  98 #include "trace/tracing.hpp"
  99 #include "utilities/defaultStream.hpp"
 100 #include "utilities/dtrace.hpp"
 101 #include "utilities/events.hpp"
 102 #include "utilities/macros.hpp"
 103 #include "utilities/preserveException.hpp"
 104 #if INCLUDE_ALL_GCS
 105 #include "gc/cms/concurrentMarkSweepThread.hpp"
 106 #include "gc/g1/concurrentMarkThread.inline.hpp"
 107 #include "gc/parallel/pcTasks.hpp"
 108 #endif // INCLUDE_ALL_GCS
 109 #if INCLUDE_JVMCI
 110 #include "jvmci/jvmciCompiler.hpp"
 111 #include "jvmci/jvmciRuntime.hpp"
 112 #endif
 113 #ifdef COMPILER1
 114 #include "c1/c1_Compiler.hpp"
 115 #endif
 116 #ifdef COMPILER2
 117 #include "opto/c2compiler.hpp"
 118 #include "opto/idealGraphPrinter.hpp"
 119 #endif
 120 #if INCLUDE_RTM_OPT
 121 #include "runtime/rtmLocking.hpp"
 122 #endif
 123 
 124 // Initialization after module runtime initialization
 125 void universe_post_module_init();  // must happen after call_initPhase2
 126 
 127 #ifdef DTRACE_ENABLED
 128 
 129 // Only bother with this argument setup if dtrace is available
 130 
 131   #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
 132   #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
 133 
 134   #define DTRACE_THREAD_PROBE(probe, javathread)                           \
 135     {                                                                      \
 136       ResourceMark rm(this);                                               \
 137       int len = 0;                                                         \
 138       const char* name = (javathread)->get_thread_name();                  \
 139       len = strlen(name);                                                  \
 140       HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */               \
 141         (char *) name, len,                                                \
 142         java_lang_Thread::thread_id((javathread)->threadObj()),            \
 143         (uintptr_t) (javathread)->osthread()->thread_id(),                 \
 144         java_lang_Thread::is_daemon((javathread)->threadObj()));           \
 145     }
 146 
 147 #else //  ndef DTRACE_ENABLED
 148 
 149   #define DTRACE_THREAD_PROBE(probe, javathread)
 150 
 151 #endif // ndef DTRACE_ENABLED
 152 
 153 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 154 // Current thread is maintained as a thread-local variable
 155 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
 156 #endif
 157 // Class hierarchy
 158 // - Thread
 159 //   - VMThread
 160 //   - WatcherThread
 161 //   - ConcurrentMarkSweepThread
 162 //   - JavaThread
 163 //     - CompilerThread
 164 
 165 // ======= Thread ========
 166 // Support for forcing alignment of thread objects for biased locking
 167 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
 168   if (UseBiasedLocking) {
 169     const int alignment = markOopDesc::biased_lock_alignment;
 170     size_t aligned_size = size + (alignment - sizeof(intptr_t));
 171     void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
 172                                           : AllocateHeap(aligned_size, flags, CURRENT_PC,
 173                                                          AllocFailStrategy::RETURN_NULL);
 174     void* aligned_addr     = align_ptr_up(real_malloc_addr, alignment);
 175     assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
 176            ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
 177            "JavaThread alignment code overflowed allocated storage");
 178     if (aligned_addr != real_malloc_addr) {
 179       log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
 180                               p2i(real_malloc_addr),
 181                               p2i(aligned_addr));
 182     }
 183     ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
 184     return aligned_addr;
 185   } else {
 186     return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
 187                        : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
 188   }
 189 }
 190 
 191 void Thread::operator delete(void* p) {
 192   if (UseBiasedLocking) {
 193     void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
 194     FreeHeap(real_malloc_addr);
 195   } else {
 196     FreeHeap(p);
 197   }
 198 }
 199 
 200 
 201 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
 202 // JavaThread
 203 
 204 
 205 Thread::Thread() {
 206   // stack and get_thread
 207   set_stack_base(NULL);
 208   set_stack_size(0);
 209   set_self_raw_id(0);
 210   set_lgrp_id(-1);
 211   DEBUG_ONLY(clear_suspendible_thread();)
 212 
 213   // allocated data structures
 214   set_osthread(NULL);
 215   set_resource_area(new (mtThread)ResourceArea());
 216   DEBUG_ONLY(_current_resource_mark = NULL;)
 217   set_handle_area(new (mtThread) HandleArea(NULL));
 218   set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
 219   set_active_handles(NULL);
 220   set_free_handle_block(NULL);
 221   set_last_handle_mark(NULL);
 222 
 223   // This initial value ==> never claimed.
 224   _oops_do_parity = 0;
 225 
 226   // the handle mark links itself to last_handle_mark
 227   new HandleMark(this);
 228 
 229   // plain initialization
 230   debug_only(_owned_locks = NULL;)
 231   debug_only(_allow_allocation_count = 0;)
 232   NOT_PRODUCT(_allow_safepoint_count = 0;)
 233   NOT_PRODUCT(_skip_gcalot = false;)
 234   _jvmti_env_iteration_count = 0;
 235   set_allocated_bytes(0);
 236   _vm_operation_started_count = 0;
 237   _vm_operation_completed_count = 0;
 238   _current_pending_monitor = NULL;
 239   _current_pending_monitor_is_from_java = true;
 240   _current_waiting_monitor = NULL;
 241   _num_nested_signal = 0;
 242   omFreeList = NULL;
 243   omFreeCount = 0;
 244   omFreeProvision = 32;
 245   omInUseList = NULL;
 246   omInUseCount = 0;
 247 
 248 #ifdef ASSERT
 249   _visited_for_critical_count = false;
 250 #endif
 251 
 252   _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
 253                          Monitor::_safepoint_check_sometimes);
 254   _suspend_flags = 0;
 255 
 256   // thread-specific hashCode stream generator state - Marsaglia shift-xor form
 257   _hashStateX = os::random();
 258   _hashStateY = 842502087;
 259   _hashStateZ = 0x8767;    // (int)(3579807591LL & 0xffff) ;
 260   _hashStateW = 273326509;
 261 
 262   _OnTrap   = 0;
 263   _schedctl = NULL;
 264   _Stalled  = 0;
 265   _TypeTag  = 0x2BAD;
 266 
 267   // Many of the following fields are effectively final - immutable
 268   // Note that nascent threads can't use the Native Monitor-Mutex
 269   // construct until the _MutexEvent is initialized ...
 270   // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
 271   // we might instead use a stack of ParkEvents that we could provision on-demand.
 272   // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
 273   // and ::Release()
 274   _ParkEvent   = ParkEvent::Allocate(this);
 275   _SleepEvent  = ParkEvent::Allocate(this);
 276   _MutexEvent  = ParkEvent::Allocate(this);
 277   _MuxEvent    = ParkEvent::Allocate(this);
 278 
 279 #ifdef CHECK_UNHANDLED_OOPS
 280   if (CheckUnhandledOops) {
 281     _unhandled_oops = new UnhandledOops(this);
 282   }
 283 #endif // CHECK_UNHANDLED_OOPS
 284 #ifdef ASSERT
 285   if (UseBiasedLocking) {
 286     assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
 287     assert(this == _real_malloc_address ||
 288            this == align_ptr_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
 289            "bug in forced alignment of thread objects");
 290   }
 291 #endif // ASSERT
 292 }
 293 
 294 void Thread::initialize_thread_current() {
 295 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 296   assert(_thr_current == NULL, "Thread::current already initialized");
 297   _thr_current = this;
 298 #endif
 299   assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
 300   ThreadLocalStorage::set_thread(this);
 301   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 302 }
 303 
 304 void Thread::clear_thread_current() {
 305   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 306 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 307   _thr_current = NULL;
 308 #endif
 309   ThreadLocalStorage::set_thread(NULL);
 310 }
 311 
 312 void Thread::record_stack_base_and_size() {
 313   set_stack_base(os::current_stack_base());
 314   set_stack_size(os::current_stack_size());
 315   // CR 7190089: on Solaris, primordial thread's stack is adjusted
 316   // in initialize_thread(). Without the adjustment, stack size is
 317   // incorrect if stack is set to unlimited (ulimit -s unlimited).
 318   // So far, only Solaris has real implementation of initialize_thread().
 319   //
 320   // set up any platform-specific state.
 321   os::initialize_thread(this);
 322 
 323   // Set stack limits after thread is initialized.
 324   if (is_Java_thread()) {
 325     ((JavaThread*) this)->set_stack_overflow_limit();
 326     ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
 327   }
 328 #if INCLUDE_NMT
 329   // record thread's native stack, stack grows downward
 330   MemTracker::record_thread_stack(stack_end(), stack_size());
 331 #endif // INCLUDE_NMT
 332   log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
 333     PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
 334     os::current_thread_id(), p2i(stack_base() - stack_size()),
 335     p2i(stack_base()), stack_size()/1024);
 336 }
 337 
 338 
 339 Thread::~Thread() {
 340   EVENT_THREAD_DESTRUCT(this);
 341 
 342   // stack_base can be NULL if the thread is never started or exited before
 343   // record_stack_base_and_size called. Although, we would like to ensure
 344   // that all started threads do call record_stack_base_and_size(), there is
 345   // not proper way to enforce that.
 346 #if INCLUDE_NMT
 347   if (_stack_base != NULL) {
 348     MemTracker::release_thread_stack(stack_end(), stack_size());
 349 #ifdef ASSERT
 350     set_stack_base(NULL);
 351 #endif
 352   }
 353 #endif // INCLUDE_NMT
 354 
 355   // deallocate data structures
 356   delete resource_area();
 357   // since the handle marks are using the handle area, we have to deallocated the root
 358   // handle mark before deallocating the thread's handle area,
 359   assert(last_handle_mark() != NULL, "check we have an element");
 360   delete last_handle_mark();
 361   assert(last_handle_mark() == NULL, "check we have reached the end");
 362 
 363   // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
 364   // We NULL out the fields for good hygiene.
 365   ParkEvent::Release(_ParkEvent); _ParkEvent   = NULL;
 366   ParkEvent::Release(_SleepEvent); _SleepEvent  = NULL;
 367   ParkEvent::Release(_MutexEvent); _MutexEvent  = NULL;
 368   ParkEvent::Release(_MuxEvent); _MuxEvent    = NULL;
 369 
 370   delete handle_area();
 371   delete metadata_handles();
 372 
 373   // SR_handler uses this as a termination indicator -
 374   // needs to happen before os::free_thread()
 375   delete _SR_lock;
 376   _SR_lock = NULL;
 377 
 378   // osthread() can be NULL, if creation of thread failed.
 379   if (osthread() != NULL) os::free_thread(osthread());
 380 
 381   // clear Thread::current if thread is deleting itself.
 382   // Needed to ensure JNI correctly detects non-attached threads.
 383   if (this == Thread::current()) {
 384     clear_thread_current();
 385   }
 386 
 387   CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
 388 }
 389 
 390 // NOTE: dummy function for assertion purpose.
 391 void Thread::run() {
 392   ShouldNotReachHere();
 393 }
 394 
 395 #ifdef ASSERT
 396 // Private method to check for dangling thread pointer
 397 void check_for_dangling_thread_pointer(Thread *thread) {
 398   assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
 399          "possibility of dangling Thread pointer");
 400 }
 401 #endif
 402 
 403 ThreadPriority Thread::get_priority(const Thread* const thread) {
 404   ThreadPriority priority;
 405   // Can return an error!
 406   (void)os::get_priority(thread, priority);
 407   assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
 408   return priority;
 409 }
 410 
 411 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
 412   debug_only(check_for_dangling_thread_pointer(thread);)
 413   // Can return an error!
 414   (void)os::set_priority(thread, priority);
 415 }
 416 
 417 
 418 void Thread::start(Thread* thread) {
 419   // Start is different from resume in that its safety is guaranteed by context or
 420   // being called from a Java method synchronized on the Thread object.
 421   if (!DisableStartThread) {
 422     if (thread->is_Java_thread()) {
 423       // Initialize the thread state to RUNNABLE before starting this thread.
 424       // Can not set it after the thread started because we do not know the
 425       // exact thread state at that time. It could be in MONITOR_WAIT or
 426       // in SLEEPING or some other state.
 427       java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
 428                                           java_lang_Thread::RUNNABLE);
 429     }
 430     os::start_thread(thread);
 431   }
 432 }
 433 
 434 // Enqueue a VM_Operation to do the job for us - sometime later
 435 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
 436   VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
 437   VMThread::execute(vm_stop);
 438 }
 439 
 440 
 441 // Check if an external suspend request has completed (or has been
 442 // cancelled). Returns true if the thread is externally suspended and
 443 // false otherwise.
 444 //
 445 // The bits parameter returns information about the code path through
 446 // the routine. Useful for debugging:
 447 //
 448 // set in is_ext_suspend_completed():
 449 // 0x00000001 - routine was entered
 450 // 0x00000010 - routine return false at end
 451 // 0x00000100 - thread exited (return false)
 452 // 0x00000200 - suspend request cancelled (return false)
 453 // 0x00000400 - thread suspended (return true)
 454 // 0x00001000 - thread is in a suspend equivalent state (return true)
 455 // 0x00002000 - thread is native and walkable (return true)
 456 // 0x00004000 - thread is native_trans and walkable (needed retry)
 457 //
 458 // set in wait_for_ext_suspend_completion():
 459 // 0x00010000 - routine was entered
 460 // 0x00020000 - suspend request cancelled before loop (return false)
 461 // 0x00040000 - thread suspended before loop (return true)
 462 // 0x00080000 - suspend request cancelled in loop (return false)
 463 // 0x00100000 - thread suspended in loop (return true)
 464 // 0x00200000 - suspend not completed during retry loop (return false)
 465 
 466 // Helper class for tracing suspend wait debug bits.
 467 //
 468 // 0x00000100 indicates that the target thread exited before it could
 469 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
 470 // 0x00080000 each indicate a cancelled suspend request so they don't
 471 // count as wait failures either.
 472 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
 473 
 474 class TraceSuspendDebugBits : public StackObj {
 475  private:
 476   JavaThread * jt;
 477   bool         is_wait;
 478   bool         called_by_wait;  // meaningful when !is_wait
 479   uint32_t *   bits;
 480 
 481  public:
 482   TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
 483                         uint32_t *_bits) {
 484     jt             = _jt;
 485     is_wait        = _is_wait;
 486     called_by_wait = _called_by_wait;
 487     bits           = _bits;
 488   }
 489 
 490   ~TraceSuspendDebugBits() {
 491     if (!is_wait) {
 492 #if 1
 493       // By default, don't trace bits for is_ext_suspend_completed() calls.
 494       // That trace is very chatty.
 495       return;
 496 #else
 497       if (!called_by_wait) {
 498         // If tracing for is_ext_suspend_completed() is enabled, then only
 499         // trace calls to it from wait_for_ext_suspend_completion()
 500         return;
 501       }
 502 #endif
 503     }
 504 
 505     if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
 506       if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
 507         MutexLocker ml(Threads_lock);  // needed for get_thread_name()
 508         ResourceMark rm;
 509 
 510         tty->print_cr(
 511                       "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
 512                       jt->get_thread_name(), *bits);
 513 
 514         guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
 515       }
 516     }
 517   }
 518 };
 519 #undef DEBUG_FALSE_BITS
 520 
 521 
 522 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
 523                                           uint32_t *bits) {
 524   TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
 525 
 526   bool did_trans_retry = false;  // only do thread_in_native_trans retry once
 527   bool do_trans_retry;           // flag to force the retry
 528 
 529   *bits |= 0x00000001;
 530 
 531   do {
 532     do_trans_retry = false;
 533 
 534     if (is_exiting()) {
 535       // Thread is in the process of exiting. This is always checked
 536       // first to reduce the risk of dereferencing a freed JavaThread.
 537       *bits |= 0x00000100;
 538       return false;
 539     }
 540 
 541     if (!is_external_suspend()) {
 542       // Suspend request is cancelled. This is always checked before
 543       // is_ext_suspended() to reduce the risk of a rogue resume
 544       // confusing the thread that made the suspend request.
 545       *bits |= 0x00000200;
 546       return false;
 547     }
 548 
 549     if (is_ext_suspended()) {
 550       // thread is suspended
 551       *bits |= 0x00000400;
 552       return true;
 553     }
 554 
 555     // Now that we no longer do hard suspends of threads running
 556     // native code, the target thread can be changing thread state
 557     // while we are in this routine:
 558     //
 559     //   _thread_in_native -> _thread_in_native_trans -> _thread_blocked
 560     //
 561     // We save a copy of the thread state as observed at this moment
 562     // and make our decision about suspend completeness based on the
 563     // copy. This closes the race where the thread state is seen as
 564     // _thread_in_native_trans in the if-thread_blocked check, but is
 565     // seen as _thread_blocked in if-thread_in_native_trans check.
 566     JavaThreadState save_state = thread_state();
 567 
 568     if (save_state == _thread_blocked && is_suspend_equivalent()) {
 569       // If the thread's state is _thread_blocked and this blocking
 570       // condition is known to be equivalent to a suspend, then we can
 571       // consider the thread to be externally suspended. This means that
 572       // the code that sets _thread_blocked has been modified to do
 573       // self-suspension if the blocking condition releases. We also
 574       // used to check for CONDVAR_WAIT here, but that is now covered by
 575       // the _thread_blocked with self-suspension check.
 576       //
 577       // Return true since we wouldn't be here unless there was still an
 578       // external suspend request.
 579       *bits |= 0x00001000;
 580       return true;
 581     } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
 582       // Threads running native code will self-suspend on native==>VM/Java
 583       // transitions. If its stack is walkable (should always be the case
 584       // unless this function is called before the actual java_suspend()
 585       // call), then the wait is done.
 586       *bits |= 0x00002000;
 587       return true;
 588     } else if (!called_by_wait && !did_trans_retry &&
 589                save_state == _thread_in_native_trans &&
 590                frame_anchor()->walkable()) {
 591       // The thread is transitioning from thread_in_native to another
 592       // thread state. check_safepoint_and_suspend_for_native_trans()
 593       // will force the thread to self-suspend. If it hasn't gotten
 594       // there yet we may have caught the thread in-between the native
 595       // code check above and the self-suspend. Lucky us. If we were
 596       // called by wait_for_ext_suspend_completion(), then it
 597       // will be doing the retries so we don't have to.
 598       //
 599       // Since we use the saved thread state in the if-statement above,
 600       // there is a chance that the thread has already transitioned to
 601       // _thread_blocked by the time we get here. In that case, we will
 602       // make a single unnecessary pass through the logic below. This
 603       // doesn't hurt anything since we still do the trans retry.
 604 
 605       *bits |= 0x00004000;
 606 
 607       // Once the thread leaves thread_in_native_trans for another
 608       // thread state, we break out of this retry loop. We shouldn't
 609       // need this flag to prevent us from getting back here, but
 610       // sometimes paranoia is good.
 611       did_trans_retry = true;
 612 
 613       // We wait for the thread to transition to a more usable state.
 614       for (int i = 1; i <= SuspendRetryCount; i++) {
 615         // We used to do an "os::yield_all(i)" call here with the intention
 616         // that yielding would increase on each retry. However, the parameter
 617         // is ignored on Linux which means the yield didn't scale up. Waiting
 618         // on the SR_lock below provides a much more predictable scale up for
 619         // the delay. It also provides a simple/direct point to check for any
 620         // safepoint requests from the VMThread
 621 
 622         // temporarily drops SR_lock while doing wait with safepoint check
 623         // (if we're a JavaThread - the WatcherThread can also call this)
 624         // and increase delay with each retry
 625         SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 626 
 627         // check the actual thread state instead of what we saved above
 628         if (thread_state() != _thread_in_native_trans) {
 629           // the thread has transitioned to another thread state so
 630           // try all the checks (except this one) one more time.
 631           do_trans_retry = true;
 632           break;
 633         }
 634       } // end retry loop
 635 
 636 
 637     }
 638   } while (do_trans_retry);
 639 
 640   *bits |= 0x00000010;
 641   return false;
 642 }
 643 
 644 // Wait for an external suspend request to complete (or be cancelled).
 645 // Returns true if the thread is externally suspended and false otherwise.
 646 //
 647 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
 648                                                  uint32_t *bits) {
 649   TraceSuspendDebugBits tsdb(this, true /* is_wait */,
 650                              false /* !called_by_wait */, bits);
 651 
 652   // local flag copies to minimize SR_lock hold time
 653   bool is_suspended;
 654   bool pending;
 655   uint32_t reset_bits;
 656 
 657   // set a marker so is_ext_suspend_completed() knows we are the caller
 658   *bits |= 0x00010000;
 659 
 660   // We use reset_bits to reinitialize the bits value at the top of
 661   // each retry loop. This allows the caller to make use of any
 662   // unused bits for their own marking purposes.
 663   reset_bits = *bits;
 664 
 665   {
 666     MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
 667     is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 668                                             delay, bits);
 669     pending = is_external_suspend();
 670   }
 671   // must release SR_lock to allow suspension to complete
 672 
 673   if (!pending) {
 674     // A cancelled suspend request is the only false return from
 675     // is_ext_suspend_completed() that keeps us from entering the
 676     // retry loop.
 677     *bits |= 0x00020000;
 678     return false;
 679   }
 680 
 681   if (is_suspended) {
 682     *bits |= 0x00040000;
 683     return true;
 684   }
 685 
 686   for (int i = 1; i <= retries; i++) {
 687     *bits = reset_bits;  // reinit to only track last retry
 688 
 689     // We used to do an "os::yield_all(i)" call here with the intention
 690     // that yielding would increase on each retry. However, the parameter
 691     // is ignored on Linux which means the yield didn't scale up. Waiting
 692     // on the SR_lock below provides a much more predictable scale up for
 693     // the delay. It also provides a simple/direct point to check for any
 694     // safepoint requests from the VMThread
 695 
 696     {
 697       MutexLocker ml(SR_lock());
 698       // wait with safepoint check (if we're a JavaThread - the WatcherThread
 699       // can also call this)  and increase delay with each retry
 700       SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 701 
 702       is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 703                                               delay, bits);
 704 
 705       // It is possible for the external suspend request to be cancelled
 706       // (by a resume) before the actual suspend operation is completed.
 707       // Refresh our local copy to see if we still need to wait.
 708       pending = is_external_suspend();
 709     }
 710 
 711     if (!pending) {
 712       // A cancelled suspend request is the only false return from
 713       // is_ext_suspend_completed() that keeps us from staying in the
 714       // retry loop.
 715       *bits |= 0x00080000;
 716       return false;
 717     }
 718 
 719     if (is_suspended) {
 720       *bits |= 0x00100000;
 721       return true;
 722     }
 723   } // end retry loop
 724 
 725   // thread did not suspend after all our retries
 726   *bits |= 0x00200000;
 727   return false;
 728 }
 729 
 730 #ifndef PRODUCT
 731 void JavaThread::record_jump(address target, address instr, const char* file,
 732                              int line) {
 733 
 734   // This should not need to be atomic as the only way for simultaneous
 735   // updates is via interrupts. Even then this should be rare or non-existent
 736   // and we don't care that much anyway.
 737 
 738   int index = _jmp_ring_index;
 739   _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
 740   _jmp_ring[index]._target = (intptr_t) target;
 741   _jmp_ring[index]._instruction = (intptr_t) instr;
 742   _jmp_ring[index]._file = file;
 743   _jmp_ring[index]._line = line;
 744 }
 745 #endif // PRODUCT
 746 
 747 // Called by flat profiler
 748 // Callers have already called wait_for_ext_suspend_completion
 749 // The assertion for that is currently too complex to put here:
 750 bool JavaThread::profile_last_Java_frame(frame* _fr) {
 751   bool gotframe = false;
 752   // self suspension saves needed state.
 753   if (has_last_Java_frame() && _anchor.walkable()) {
 754     *_fr = pd_last_frame();
 755     gotframe = true;
 756   }
 757   return gotframe;
 758 }
 759 
 760 void Thread::interrupt(Thread* thread) {
 761   debug_only(check_for_dangling_thread_pointer(thread);)
 762   os::interrupt(thread);
 763 }
 764 
 765 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
 766   debug_only(check_for_dangling_thread_pointer(thread);)
 767   // Note:  If clear_interrupted==false, this simply fetches and
 768   // returns the value of the field osthread()->interrupted().
 769   return os::is_interrupted(thread, clear_interrupted);
 770 }
 771 
 772 
 773 // GC Support
 774 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
 775   jint thread_parity = _oops_do_parity;
 776   if (thread_parity != strong_roots_parity) {
 777     jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
 778     if (res == thread_parity) {
 779       return true;
 780     } else {
 781       guarantee(res == strong_roots_parity, "Or else what?");
 782       return false;
 783     }
 784   }
 785   return false;
 786 }
 787 
 788 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
 789   active_handles()->oops_do(f);
 790   // Do oop for ThreadShadow
 791   f->do_oop((oop*)&_pending_exception);
 792   handle_area()->oops_do(f);
 793 
 794   if (MonitorInUseLists) {
 795     // When using thread local monitor lists, we scan them here,
 796     // and the remaining global monitors in ObjectSynchronizer::oops_do().
 797     ObjectSynchronizer::thread_local_used_oops_do(this, f);
 798   }
 799 }
 800 
 801 void Thread::metadata_handles_do(void f(Metadata*)) {
 802   // Only walk the Handles in Thread.
 803   if (metadata_handles() != NULL) {
 804     for (int i = 0; i< metadata_handles()->length(); i++) {
 805       f(metadata_handles()->at(i));
 806     }
 807   }
 808 }
 809 
 810 void Thread::print_on(outputStream* st) const {
 811   // get_priority assumes osthread initialized
 812   if (osthread() != NULL) {
 813     int os_prio;
 814     if (os::get_native_priority(this, &os_prio) == OS_OK) {
 815       st->print("os_prio=%d ", os_prio);
 816     }
 817     st->print("tid=" INTPTR_FORMAT " ", p2i(this));
 818     ext().print_on(st);
 819     osthread()->print_on(st);
 820   }
 821   debug_only(if (WizardMode) print_owned_locks_on(st);)
 822 }
 823 
 824 // Thread::print_on_error() is called by fatal error handler. Don't use
 825 // any lock or allocate memory.
 826 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
 827   assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
 828 
 829   if (is_VM_thread())                 { st->print("VMThread"); }
 830   else if (is_GC_task_thread())       { st->print("GCTaskThread"); }
 831   else if (is_Watcher_thread())       { st->print("WatcherThread"); }
 832   else if (is_ConcurrentGC_thread())  { st->print("ConcurrentGCThread"); }
 833   else                                { st->print("Thread"); }
 834 
 835   if (is_Named_thread()) {
 836     st->print(" \"%s\"", name());
 837   }
 838 
 839   st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
 840             p2i(stack_end()), p2i(stack_base()));
 841 
 842   if (osthread()) {
 843     st->print(" [id=%d]", osthread()->thread_id());
 844   }
 845 }
 846 
 847 #ifdef ASSERT
 848 void Thread::print_owned_locks_on(outputStream* st) const {
 849   Monitor *cur = _owned_locks;
 850   if (cur == NULL) {
 851     st->print(" (no locks) ");
 852   } else {
 853     st->print_cr(" Locks owned:");
 854     while (cur) {
 855       cur->print_on(st);
 856       cur = cur->next();
 857     }
 858   }
 859 }
 860 
 861 static int ref_use_count  = 0;
 862 
 863 bool Thread::owns_locks_but_compiled_lock() const {
 864   for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 865     if (cur != Compile_lock) return true;
 866   }
 867   return false;
 868 }
 869 
 870 
 871 #endif
 872 
 873 #ifndef PRODUCT
 874 
 875 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
 876 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
 877 // no threads which allow_vm_block's are held
 878 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
 879   // Check if current thread is allowed to block at a safepoint
 880   if (!(_allow_safepoint_count == 0)) {
 881     fatal("Possible safepoint reached by thread that does not allow it");
 882   }
 883   if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
 884     fatal("LEAF method calling lock?");
 885   }
 886 
 887 #ifdef ASSERT
 888   if (potential_vm_operation && is_Java_thread()
 889       && !Universe::is_bootstrapping()) {
 890     // Make sure we do not hold any locks that the VM thread also uses.
 891     // This could potentially lead to deadlocks
 892     for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 893       // Threads_lock is special, since the safepoint synchronization will not start before this is
 894       // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
 895       // since it is used to transfer control between JavaThreads and the VMThread
 896       // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
 897       if ((cur->allow_vm_block() &&
 898            cur != Threads_lock &&
 899            cur != Compile_lock &&               // Temporary: should not be necessary when we get separate compilation
 900            cur != VMOperationRequest_lock &&
 901            cur != VMOperationQueue_lock) ||
 902            cur->rank() == Mutex::special) {
 903         fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
 904       }
 905     }
 906   }
 907 
 908   if (GCALotAtAllSafepoints) {
 909     // We could enter a safepoint here and thus have a gc
 910     InterfaceSupport::check_gc_alot();
 911   }
 912 #endif
 913 }
 914 #endif
 915 
 916 bool Thread::is_in_stack(address adr) const {
 917   assert(Thread::current() == this, "is_in_stack can only be called from current thread");
 918   address end = os::current_stack_pointer();
 919   // Allow non Java threads to call this without stack_base
 920   if (_stack_base == NULL) return true;
 921   if (stack_base() >= adr && adr >= end) return true;
 922 
 923   return false;
 924 }
 925 
 926 bool Thread::is_in_usable_stack(address adr) const {
 927   size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
 928   size_t usable_stack_size = _stack_size - stack_guard_size;
 929 
 930   return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
 931 }
 932 
 933 
 934 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
 935 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
 936 // used for compilation in the future. If that change is made, the need for these methods
 937 // should be revisited, and they should be removed if possible.
 938 
 939 bool Thread::is_lock_owned(address adr) const {
 940   return on_local_stack(adr);
 941 }
 942 
 943 bool Thread::set_as_starting_thread() {
 944   // NOTE: this must be called inside the main thread.
 945   return os::create_main_thread((JavaThread*)this);
 946 }
 947 
 948 static void initialize_class(Symbol* class_name, TRAPS) {
 949   Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
 950   InstanceKlass::cast(klass)->initialize(CHECK);
 951 }
 952 
 953 
 954 // Creates the initial ThreadGroup
 955 static Handle create_initial_thread_group(TRAPS) {
 956   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
 957   InstanceKlass* ik = InstanceKlass::cast(k);
 958 
 959   Handle system_instance = ik->allocate_instance_handle(CHECK_NH);
 960   {
 961     JavaValue result(T_VOID);
 962     JavaCalls::call_special(&result,
 963                             system_instance,
 964                             ik,
 965                             vmSymbols::object_initializer_name(),
 966                             vmSymbols::void_method_signature(),
 967                             CHECK_NH);
 968   }
 969   Universe::set_system_thread_group(system_instance());
 970 
 971   Handle main_instance = ik->allocate_instance_handle(CHECK_NH);
 972   {
 973     JavaValue result(T_VOID);
 974     Handle string = java_lang_String::create_from_str("main", CHECK_NH);
 975     JavaCalls::call_special(&result,
 976                             main_instance,
 977                             ik,
 978                             vmSymbols::object_initializer_name(),
 979                             vmSymbols::threadgroup_string_void_signature(),
 980                             system_instance,
 981                             string,
 982                             CHECK_NH);
 983   }
 984   return main_instance;
 985 }
 986 
 987 // Creates the initial Thread
 988 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
 989                                  TRAPS) {
 990   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
 991   InstanceKlass* ik = InstanceKlass::cast(k);
 992   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
 993 
 994   java_lang_Thread::set_thread(thread_oop(), thread);
 995   java_lang_Thread::set_priority(thread_oop(), NormPriority);
 996   thread->set_threadObj(thread_oop());
 997 
 998   Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
 999 
1000   JavaValue result(T_VOID);
1001   JavaCalls::call_special(&result, thread_oop,
1002                           ik,
1003                           vmSymbols::object_initializer_name(),
1004                           vmSymbols::threadgroup_string_void_signature(),
1005                           thread_group,
1006                           string,
1007                           CHECK_NULL);
1008   return thread_oop();
1009 }
1010 
1011 char java_runtime_name[128] = "";
1012 char java_runtime_version[128] = "";
1013 
1014 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1015 static const char* get_java_runtime_name(TRAPS) {
1016   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1017                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1018   fieldDescriptor fd;
1019   bool found = k != NULL &&
1020                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1021                                                         vmSymbols::string_signature(), &fd);
1022   if (found) {
1023     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1024     if (name_oop == NULL) {
1025       return NULL;
1026     }
1027     const char* name = java_lang_String::as_utf8_string(name_oop,
1028                                                         java_runtime_name,
1029                                                         sizeof(java_runtime_name));
1030     return name;
1031   } else {
1032     return NULL;
1033   }
1034 }
1035 
1036 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1037 static const char* get_java_runtime_version(TRAPS) {
1038   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1039                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1040   fieldDescriptor fd;
1041   bool found = k != NULL &&
1042                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1043                                                         vmSymbols::string_signature(), &fd);
1044   if (found) {
1045     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1046     if (name_oop == NULL) {
1047       return NULL;
1048     }
1049     const char* name = java_lang_String::as_utf8_string(name_oop,
1050                                                         java_runtime_version,
1051                                                         sizeof(java_runtime_version));
1052     return name;
1053   } else {
1054     return NULL;
1055   }
1056 }
1057 
1058 // General purpose hook into Java code, run once when the VM is initialized.
1059 // The Java library method itself may be changed independently from the VM.
1060 static void call_postVMInitHook(TRAPS) {
1061   Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1062   if (klass != NULL) {
1063     JavaValue result(T_VOID);
1064     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1065                            vmSymbols::void_method_signature(),
1066                            CHECK);
1067   }
1068 }
1069 
1070 static void reset_vm_info_property(TRAPS) {
1071   // the vm info string
1072   ResourceMark rm(THREAD);
1073   const char *vm_info = VM_Version::vm_info_string();
1074 
1075   // java.lang.System class
1076   Klass* klass =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1077 
1078   // setProperty arguments
1079   Handle key_str    = java_lang_String::create_from_str("java.vm.info", CHECK);
1080   Handle value_str  = java_lang_String::create_from_str(vm_info, CHECK);
1081 
1082   // return value
1083   JavaValue r(T_OBJECT);
1084 
1085   // public static String setProperty(String key, String value);
1086   JavaCalls::call_static(&r,
1087                          klass,
1088                          vmSymbols::setProperty_name(),
1089                          vmSymbols::string_string_string_signature(),
1090                          key_str,
1091                          value_str,
1092                          CHECK);
1093 }
1094 
1095 
1096 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1097                                     bool daemon, TRAPS) {
1098   assert(thread_group.not_null(), "thread group should be specified");
1099   assert(threadObj() == NULL, "should only create Java thread object once");
1100 
1101   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1102   InstanceKlass* ik = InstanceKlass::cast(k);
1103   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1104 
1105   java_lang_Thread::set_thread(thread_oop(), this);
1106   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1107   set_threadObj(thread_oop());
1108 
1109   JavaValue result(T_VOID);
1110   if (thread_name != NULL) {
1111     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1112     // Thread gets assigned specified name and null target
1113     JavaCalls::call_special(&result,
1114                             thread_oop,
1115                             ik,
1116                             vmSymbols::object_initializer_name(),
1117                             vmSymbols::threadgroup_string_void_signature(),
1118                             thread_group, // Argument 1
1119                             name,         // Argument 2
1120                             THREAD);
1121   } else {
1122     // Thread gets assigned name "Thread-nnn" and null target
1123     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1124     JavaCalls::call_special(&result,
1125                             thread_oop,
1126                             ik,
1127                             vmSymbols::object_initializer_name(),
1128                             vmSymbols::threadgroup_runnable_void_signature(),
1129                             thread_group, // Argument 1
1130                             Handle(),     // Argument 2
1131                             THREAD);
1132   }
1133 
1134 
1135   if (daemon) {
1136     java_lang_Thread::set_daemon(thread_oop());
1137   }
1138 
1139   if (HAS_PENDING_EXCEPTION) {
1140     return;
1141   }
1142 
1143   Klass* group =  SystemDictionary::ThreadGroup_klass();
1144   Handle threadObj(THREAD, this->threadObj());
1145 
1146   JavaCalls::call_special(&result,
1147                           thread_group,
1148                           group,
1149                           vmSymbols::add_method_name(),
1150                           vmSymbols::thread_void_signature(),
1151                           threadObj,          // Arg 1
1152                           THREAD);
1153 }
1154 
1155 // NamedThread --  non-JavaThread subclasses with multiple
1156 // uniquely named instances should derive from this.
1157 NamedThread::NamedThread() : Thread() {
1158   _name = NULL;
1159   _processed_thread = NULL;
1160   _gc_id = GCId::undefined();
1161 }
1162 
1163 NamedThread::~NamedThread() {
1164   if (_name != NULL) {
1165     FREE_C_HEAP_ARRAY(char, _name);
1166     _name = NULL;
1167   }
1168 }
1169 
1170 void NamedThread::set_name(const char* format, ...) {
1171   guarantee(_name == NULL, "Only get to set name once.");
1172   _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1173   guarantee(_name != NULL, "alloc failure");
1174   va_list ap;
1175   va_start(ap, format);
1176   jio_vsnprintf(_name, max_name_len, format, ap);
1177   va_end(ap);
1178 }
1179 
1180 void NamedThread::initialize_named_thread() {
1181   set_native_thread_name(name());
1182 }
1183 
1184 void NamedThread::print_on(outputStream* st) const {
1185   st->print("\"%s\" ", name());
1186   Thread::print_on(st);
1187   st->cr();
1188 }
1189 
1190 
1191 // ======= WatcherThread ========
1192 
1193 // The watcher thread exists to simulate timer interrupts.  It should
1194 // be replaced by an abstraction over whatever native support for
1195 // timer interrupts exists on the platform.
1196 
1197 WatcherThread* WatcherThread::_watcher_thread   = NULL;
1198 bool WatcherThread::_startable = false;
1199 volatile bool  WatcherThread::_should_terminate = false;
1200 
1201 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) {
1202   assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1203   if (os::create_thread(this, os::watcher_thread)) {
1204     _watcher_thread = this;
1205 
1206     // Set the watcher thread to the highest OS priority which should not be
1207     // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1208     // is created. The only normal thread using this priority is the reference
1209     // handler thread, which runs for very short intervals only.
1210     // If the VMThread's priority is not lower than the WatcherThread profiling
1211     // will be inaccurate.
1212     os::set_priority(this, MaxPriority);
1213     if (!DisableStartThread) {
1214       os::start_thread(this);
1215     }
1216   }
1217 }
1218 
1219 int WatcherThread::sleep() const {
1220   // The WatcherThread does not participate in the safepoint protocol
1221   // for the PeriodicTask_lock because it is not a JavaThread.
1222   MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1223 
1224   if (_should_terminate) {
1225     // check for termination before we do any housekeeping or wait
1226     return 0;  // we did not sleep.
1227   }
1228 
1229   // remaining will be zero if there are no tasks,
1230   // causing the WatcherThread to sleep until a task is
1231   // enrolled
1232   int remaining = PeriodicTask::time_to_wait();
1233   int time_slept = 0;
1234 
1235   // we expect this to timeout - we only ever get unparked when
1236   // we should terminate or when a new task has been enrolled
1237   OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1238 
1239   jlong time_before_loop = os::javaTimeNanos();
1240 
1241   while (true) {
1242     bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1243                                             remaining);
1244     jlong now = os::javaTimeNanos();
1245 
1246     if (remaining == 0) {
1247       // if we didn't have any tasks we could have waited for a long time
1248       // consider the time_slept zero and reset time_before_loop
1249       time_slept = 0;
1250       time_before_loop = now;
1251     } else {
1252       // need to recalculate since we might have new tasks in _tasks
1253       time_slept = (int) ((now - time_before_loop) / 1000000);
1254     }
1255 
1256     // Change to task list or spurious wakeup of some kind
1257     if (timedout || _should_terminate) {
1258       break;
1259     }
1260 
1261     remaining = PeriodicTask::time_to_wait();
1262     if (remaining == 0) {
1263       // Last task was just disenrolled so loop around and wait until
1264       // another task gets enrolled
1265       continue;
1266     }
1267 
1268     remaining -= time_slept;
1269     if (remaining <= 0) {
1270       break;
1271     }
1272   }
1273 
1274   return time_slept;
1275 }
1276 
1277 void WatcherThread::run() {
1278   assert(this == watcher_thread(), "just checking");
1279 
1280   this->record_stack_base_and_size();
1281   this->set_native_thread_name(this->name());
1282   this->set_active_handles(JNIHandleBlock::allocate_block());
1283   while (true) {
1284     assert(watcher_thread() == Thread::current(), "thread consistency check");
1285     assert(watcher_thread() == this, "thread consistency check");
1286 
1287     // Calculate how long it'll be until the next PeriodicTask work
1288     // should be done, and sleep that amount of time.
1289     int time_waited = sleep();
1290 
1291     if (is_error_reported()) {
1292       // A fatal error has happened, the error handler(VMError::report_and_die)
1293       // should abort JVM after creating an error log file. However in some
1294       // rare cases, the error handler itself might deadlock. Here periodically
1295       // check for error reporting timeouts, and if it happens, just proceed to
1296       // abort the VM.
1297 
1298       // This code is in WatcherThread because WatcherThread wakes up
1299       // periodically so the fatal error handler doesn't need to do anything;
1300       // also because the WatcherThread is less likely to crash than other
1301       // threads.
1302 
1303       for (;;) {
1304         // Note: we use naked sleep in this loop because we want to avoid using
1305         // any kind of VM infrastructure which may be broken at this point.
1306         if (VMError::check_timeout()) {
1307           // We hit error reporting timeout. Error reporting was interrupted and
1308           // will be wrapping things up now (closing files etc). Give it some more
1309           // time, then quit the VM.
1310           os::naked_short_sleep(200);
1311           // Print a message to stderr.
1312           fdStream err(defaultStream::output_fd());
1313           err.print_raw_cr("# [ timer expired, abort... ]");
1314           // skip atexit/vm_exit/vm_abort hooks
1315           os::die();
1316         }
1317 
1318         // Wait a second, then recheck for timeout.
1319         os::naked_short_sleep(999);
1320       }
1321     }
1322 
1323     if (_should_terminate) {
1324       // check for termination before posting the next tick
1325       break;
1326     }
1327 
1328     PeriodicTask::real_time_tick(time_waited);
1329   }
1330 
1331   // Signal that it is terminated
1332   {
1333     MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1334     _watcher_thread = NULL;
1335     Terminator_lock->notify();
1336   }
1337 }
1338 
1339 void WatcherThread::start() {
1340   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1341 
1342   if (watcher_thread() == NULL && _startable) {
1343     _should_terminate = false;
1344     // Create the single instance of WatcherThread
1345     new WatcherThread();
1346   }
1347 }
1348 
1349 void WatcherThread::make_startable() {
1350   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1351   _startable = true;
1352 }
1353 
1354 void WatcherThread::stop() {
1355   {
1356     // Follow normal safepoint aware lock enter protocol since the
1357     // WatcherThread is stopped by another JavaThread.
1358     MutexLocker ml(PeriodicTask_lock);
1359     _should_terminate = true;
1360 
1361     WatcherThread* watcher = watcher_thread();
1362     if (watcher != NULL) {
1363       // unpark the WatcherThread so it can see that it should terminate
1364       watcher->unpark();
1365     }
1366   }
1367 
1368   MutexLocker mu(Terminator_lock);
1369 
1370   while (watcher_thread() != NULL) {
1371     // This wait should make safepoint checks, wait without a timeout,
1372     // and wait as a suspend-equivalent condition.
1373     //
1374     // Note: If the FlatProfiler is running, then this thread is waiting
1375     // for the WatcherThread to terminate and the WatcherThread, via the
1376     // FlatProfiler task, is waiting for the external suspend request on
1377     // this thread to complete. wait_for_ext_suspend_completion() will
1378     // eventually timeout, but that takes time. Making this wait a
1379     // suspend-equivalent condition solves that timeout problem.
1380     //
1381     Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1382                           Mutex::_as_suspend_equivalent_flag);
1383   }
1384 }
1385 
1386 void WatcherThread::unpark() {
1387   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1388   PeriodicTask_lock->notify();
1389 }
1390 
1391 void WatcherThread::print_on(outputStream* st) const {
1392   st->print("\"%s\" ", name());
1393   Thread::print_on(st);
1394   st->cr();
1395 }
1396 
1397 // ======= JavaThread ========
1398 
1399 #if INCLUDE_JVMCI
1400 
1401 jlong* JavaThread::_jvmci_old_thread_counters;
1402 
1403 bool jvmci_counters_include(JavaThread* thread) {
1404   oop threadObj = thread->threadObj();
1405   return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1406 }
1407 
1408 void JavaThread::collect_counters(typeArrayOop array) {
1409   if (JVMCICounterSize > 0) {
1410     MutexLocker tl(Threads_lock);
1411     for (int i = 0; i < array->length(); i++) {
1412       array->long_at_put(i, _jvmci_old_thread_counters[i]);
1413     }
1414     for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) {
1415       if (jvmci_counters_include(tp)) {
1416         for (int i = 0; i < array->length(); i++) {
1417           array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1418         }
1419       }
1420     }
1421   }
1422 }
1423 
1424 #endif // INCLUDE_JVMCI
1425 
1426 // A JavaThread is a normal Java thread
1427 
1428 void JavaThread::initialize() {
1429   // Initialize fields
1430 
1431   set_saved_exception_pc(NULL);
1432   set_threadObj(NULL);
1433   _anchor.clear();
1434   set_entry_point(NULL);
1435   set_jni_functions(jni_functions());
1436   set_callee_target(NULL);
1437   set_vm_result(NULL);
1438   set_vm_result_2(NULL);
1439   set_vframe_array_head(NULL);
1440   set_vframe_array_last(NULL);
1441   set_deferred_locals(NULL);
1442   set_deopt_mark(NULL);
1443   set_deopt_compiled_method(NULL);
1444   clear_must_deopt_id();
1445   set_monitor_chunks(NULL);
1446   set_next(NULL);
1447   set_thread_state(_thread_new);
1448   _terminated = _not_terminated;
1449   _privileged_stack_top = NULL;
1450   _array_for_gc = NULL;
1451   _suspend_equivalent = false;
1452   _in_deopt_handler = 0;
1453   _doing_unsafe_access = false;
1454   _stack_guard_state = stack_guard_unused;
1455 #if INCLUDE_JVMCI
1456   _pending_monitorenter = false;
1457   _pending_deoptimization = -1;
1458   _pending_failed_speculation = NULL;
1459   _pending_transfer_to_interpreter = false;
1460   _adjusting_comp_level = false;
1461   _jvmci._alternate_call_target = NULL;
1462   assert(_jvmci._implicit_exception_pc == NULL, "must be");
1463   if (JVMCICounterSize > 0) {
1464     _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1465     memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1466   } else {
1467     _jvmci_counters = NULL;
1468   }
1469 #endif // INCLUDE_JVMCI
1470   _reserved_stack_activation = NULL;  // stack base not known yet
1471   (void)const_cast<oop&>(_exception_oop = oop(NULL));
1472   _exception_pc  = 0;
1473   _exception_handler_pc = 0;
1474   _is_method_handle_return = 0;
1475   _jvmti_thread_state= NULL;
1476   _should_post_on_exceptions_flag = JNI_FALSE;
1477   _jvmti_get_loaded_classes_closure = NULL;
1478   _interp_only_mode    = 0;
1479   _special_runtime_exit_condition = _no_async_condition;
1480   _pending_async_exception = NULL;
1481   _thread_stat = NULL;
1482   _thread_stat = new ThreadStatistics();
1483   _blocked_on_compilation = false;
1484   _jni_active_critical = 0;
1485   _pending_jni_exception_check_fn = NULL;
1486   _do_not_unlock_if_synchronized = false;
1487   _cached_monitor_info = NULL;
1488   _parker = Parker::Allocate(this);
1489 
1490 #ifndef PRODUCT
1491   _jmp_ring_index = 0;
1492   for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1493     record_jump(NULL, NULL, NULL, 0);
1494   }
1495 #endif // PRODUCT
1496 
1497   set_thread_profiler(NULL);
1498   if (FlatProfiler::is_active()) {
1499     // This is where we would decide to either give each thread it's own profiler
1500     // or use one global one from FlatProfiler,
1501     // or up to some count of the number of profiled threads, etc.
1502     ThreadProfiler* pp = new ThreadProfiler();
1503     pp->engage();
1504     set_thread_profiler(pp);
1505   }
1506 
1507   // Setup safepoint state info for this thread
1508   ThreadSafepointState::create(this);
1509 
1510   debug_only(_java_call_counter = 0);
1511 
1512   // JVMTI PopFrame support
1513   _popframe_condition = popframe_inactive;
1514   _popframe_preserved_args = NULL;
1515   _popframe_preserved_args_size = 0;
1516   _frames_to_pop_failed_realloc = 0;
1517 
1518   pd_initialize();
1519 }
1520 
1521 #if INCLUDE_ALL_GCS
1522 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1523 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1524 #endif // INCLUDE_ALL_GCS
1525 
1526 JavaThread::JavaThread(bool is_attaching_via_jni) :
1527                        Thread()
1528 #if INCLUDE_ALL_GCS
1529                        , _satb_mark_queue(&_satb_mark_queue_set),
1530                        _dirty_card_queue(&_dirty_card_queue_set)
1531 #endif // INCLUDE_ALL_GCS
1532 {
1533   initialize();
1534   if (is_attaching_via_jni) {
1535     _jni_attach_state = _attaching_via_jni;
1536   } else {
1537     _jni_attach_state = _not_attaching_via_jni;
1538   }
1539   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1540 }
1541 
1542 bool JavaThread::reguard_stack(address cur_sp) {
1543   if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1544       && _stack_guard_state != stack_guard_reserved_disabled) {
1545     return true; // Stack already guarded or guard pages not needed.
1546   }
1547 
1548   if (register_stack_overflow()) {
1549     // For those architectures which have separate register and
1550     // memory stacks, we must check the register stack to see if
1551     // it has overflowed.
1552     return false;
1553   }
1554 
1555   // Java code never executes within the yellow zone: the latter is only
1556   // there to provoke an exception during stack banging.  If java code
1557   // is executing there, either StackShadowPages should be larger, or
1558   // some exception code in c1, c2 or the interpreter isn't unwinding
1559   // when it should.
1560   guarantee(cur_sp > stack_reserved_zone_base(),
1561             "not enough space to reguard - increase StackShadowPages");
1562   if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1563     enable_stack_yellow_reserved_zone();
1564     if (reserved_stack_activation() != stack_base()) {
1565       set_reserved_stack_activation(stack_base());
1566     }
1567   } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1568     set_reserved_stack_activation(stack_base());
1569     enable_stack_reserved_zone();
1570   }
1571   return true;
1572 }
1573 
1574 bool JavaThread::reguard_stack(void) {
1575   return reguard_stack(os::current_stack_pointer());
1576 }
1577 
1578 
1579 void JavaThread::block_if_vm_exited() {
1580   if (_terminated == _vm_exited) {
1581     // _vm_exited is set at safepoint, and Threads_lock is never released
1582     // we will block here forever
1583     Threads_lock->lock_without_safepoint_check();
1584     ShouldNotReachHere();
1585   }
1586 }
1587 
1588 
1589 // Remove this ifdef when C1 is ported to the compiler interface.
1590 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1591 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1592 
1593 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1594                        Thread()
1595 #if INCLUDE_ALL_GCS
1596                        , _satb_mark_queue(&_satb_mark_queue_set),
1597                        _dirty_card_queue(&_dirty_card_queue_set)
1598 #endif // INCLUDE_ALL_GCS
1599 {
1600   initialize();
1601   _jni_attach_state = _not_attaching_via_jni;
1602   set_entry_point(entry_point);
1603   // Create the native thread itself.
1604   // %note runtime_23
1605   os::ThreadType thr_type = os::java_thread;
1606   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1607                                                      os::java_thread;
1608   os::create_thread(this, thr_type, stack_sz);
1609   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1610   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1611   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1612   // the exception consists of creating the exception object & initializing it, initialization
1613   // will leave the VM via a JavaCall and then all locks must be unlocked).
1614   //
1615   // The thread is still suspended when we reach here. Thread must be explicit started
1616   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1617   // by calling Threads:add. The reason why this is not done here, is because the thread
1618   // object must be fully initialized (take a look at JVM_Start)
1619 }
1620 
1621 JavaThread::~JavaThread() {
1622 
1623   // JSR166 -- return the parker to the free list
1624   Parker::Release(_parker);
1625   _parker = NULL;
1626 
1627   // Free any remaining  previous UnrollBlock
1628   vframeArray* old_array = vframe_array_last();
1629 
1630   if (old_array != NULL) {
1631     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1632     old_array->set_unroll_block(NULL);
1633     delete old_info;
1634     delete old_array;
1635   }
1636 
1637   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1638   if (deferred != NULL) {
1639     // This can only happen if thread is destroyed before deoptimization occurs.
1640     assert(deferred->length() != 0, "empty array!");
1641     do {
1642       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1643       deferred->remove_at(0);
1644       // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1645       delete dlv;
1646     } while (deferred->length() != 0);
1647     delete deferred;
1648   }
1649 
1650   // All Java related clean up happens in exit
1651   ThreadSafepointState::destroy(this);
1652   if (_thread_profiler != NULL) delete _thread_profiler;
1653   if (_thread_stat != NULL) delete _thread_stat;
1654 
1655 #if INCLUDE_JVMCI
1656   if (JVMCICounterSize > 0) {
1657     if (jvmci_counters_include(this)) {
1658       for (int i = 0; i < JVMCICounterSize; i++) {
1659         _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1660       }
1661     }
1662     FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1663   }
1664 #endif // INCLUDE_JVMCI
1665 }
1666 
1667 
1668 // The first routine called by a new Java thread
1669 void JavaThread::run() {
1670   // initialize thread-local alloc buffer related fields
1671   this->initialize_tlab();
1672 
1673   // used to test validity of stack trace backs
1674   this->record_base_of_stack_pointer();
1675 
1676   // Record real stack base and size.
1677   this->record_stack_base_and_size();
1678 
1679   this->create_stack_guard_pages();
1680 
1681   this->cache_global_variables();
1682 
1683   // Thread is now sufficient initialized to be handled by the safepoint code as being
1684   // in the VM. Change thread state from _thread_new to _thread_in_vm
1685   ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1686 
1687   assert(JavaThread::current() == this, "sanity check");
1688   assert(!Thread::current()->owns_locks(), "sanity check");
1689 
1690   DTRACE_THREAD_PROBE(start, this);
1691 
1692   // This operation might block. We call that after all safepoint checks for a new thread has
1693   // been completed.
1694   this->set_active_handles(JNIHandleBlock::allocate_block());
1695 
1696   if (JvmtiExport::should_post_thread_life()) {
1697     JvmtiExport::post_thread_start(this);
1698   }
1699 
1700   EventThreadStart event;
1701   if (event.should_commit()) {
1702     event.set_thread(THREAD_TRACE_ID(this));
1703     event.commit();
1704   }
1705 
1706   // We call another function to do the rest so we are sure that the stack addresses used
1707   // from there will be lower than the stack base just computed
1708   thread_main_inner();
1709 
1710   // Note, thread is no longer valid at this point!
1711 }
1712 
1713 
1714 void JavaThread::thread_main_inner() {
1715   assert(JavaThread::current() == this, "sanity check");
1716   assert(this->threadObj() != NULL, "just checking");
1717 
1718   // Execute thread entry point unless this thread has a pending exception
1719   // or has been stopped before starting.
1720   // Note: Due to JVM_StopThread we can have pending exceptions already!
1721   if (!this->has_pending_exception() &&
1722       !java_lang_Thread::is_stillborn(this->threadObj())) {
1723     {
1724       ResourceMark rm(this);
1725       this->set_native_thread_name(this->get_thread_name());
1726     }
1727     HandleMark hm(this);
1728     this->entry_point()(this, this);
1729   }
1730 
1731   DTRACE_THREAD_PROBE(stop, this);
1732 
1733   this->exit(false);
1734   delete this;
1735 }
1736 
1737 
1738 static void ensure_join(JavaThread* thread) {
1739   // We do not need to grap the Threads_lock, since we are operating on ourself.
1740   Handle threadObj(thread, thread->threadObj());
1741   assert(threadObj.not_null(), "java thread object must exist");
1742   ObjectLocker lock(threadObj, thread);
1743   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1744   thread->clear_pending_exception();
1745   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1746   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1747   // Clear the native thread instance - this makes isAlive return false and allows the join()
1748   // to complete once we've done the notify_all below
1749   java_lang_Thread::set_thread(threadObj(), NULL);
1750   lock.notify_all(thread);
1751   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1752   thread->clear_pending_exception();
1753 }
1754 
1755 
1756 // For any new cleanup additions, please check to see if they need to be applied to
1757 // cleanup_failed_attach_current_thread as well.
1758 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1759   assert(this == JavaThread::current(), "thread consistency check");
1760 
1761   HandleMark hm(this);
1762   Handle uncaught_exception(this, this->pending_exception());
1763   this->clear_pending_exception();
1764   Handle threadObj(this, this->threadObj());
1765   assert(threadObj.not_null(), "Java thread object should be created");
1766 
1767   if (get_thread_profiler() != NULL) {
1768     get_thread_profiler()->disengage();
1769     ResourceMark rm;
1770     get_thread_profiler()->print(get_thread_name());
1771   }
1772 
1773 
1774   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1775   {
1776     EXCEPTION_MARK;
1777 
1778     CLEAR_PENDING_EXCEPTION;
1779   }
1780   if (!destroy_vm) {
1781     if (uncaught_exception.not_null()) {
1782       EXCEPTION_MARK;
1783       // Call method Thread.dispatchUncaughtException().
1784       Klass* thread_klass = SystemDictionary::Thread_klass();
1785       JavaValue result(T_VOID);
1786       JavaCalls::call_virtual(&result,
1787                               threadObj, thread_klass,
1788                               vmSymbols::dispatchUncaughtException_name(),
1789                               vmSymbols::throwable_void_signature(),
1790                               uncaught_exception,
1791                               THREAD);
1792       if (HAS_PENDING_EXCEPTION) {
1793         ResourceMark rm(this);
1794         jio_fprintf(defaultStream::error_stream(),
1795                     "\nException: %s thrown from the UncaughtExceptionHandler"
1796                     " in thread \"%s\"\n",
1797                     pending_exception()->klass()->external_name(),
1798                     get_thread_name());
1799         CLEAR_PENDING_EXCEPTION;
1800       }
1801     }
1802 
1803     // Called before the java thread exit since we want to read info
1804     // from java_lang_Thread object
1805     EventThreadEnd event;
1806     if (event.should_commit()) {
1807       event.set_thread(THREAD_TRACE_ID(this));
1808       event.commit();
1809     }
1810 
1811     // Call after last event on thread
1812     EVENT_THREAD_EXIT(this);
1813 
1814     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1815     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1816     // is deprecated anyhow.
1817     if (!is_Compiler_thread()) {
1818       int count = 3;
1819       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1820         EXCEPTION_MARK;
1821         JavaValue result(T_VOID);
1822         Klass* thread_klass = SystemDictionary::Thread_klass();
1823         JavaCalls::call_virtual(&result,
1824                                 threadObj, thread_klass,
1825                                 vmSymbols::exit_method_name(),
1826                                 vmSymbols::void_method_signature(),
1827                                 THREAD);
1828         CLEAR_PENDING_EXCEPTION;
1829       }
1830     }
1831     // notify JVMTI
1832     if (JvmtiExport::should_post_thread_life()) {
1833       JvmtiExport::post_thread_end(this);
1834     }
1835 
1836     // We have notified the agents that we are exiting, before we go on,
1837     // we must check for a pending external suspend request and honor it
1838     // in order to not surprise the thread that made the suspend request.
1839     while (true) {
1840       {
1841         MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1842         if (!is_external_suspend()) {
1843           set_terminated(_thread_exiting);
1844           ThreadService::current_thread_exiting(this);
1845           break;
1846         }
1847         // Implied else:
1848         // Things get a little tricky here. We have a pending external
1849         // suspend request, but we are holding the SR_lock so we
1850         // can't just self-suspend. So we temporarily drop the lock
1851         // and then self-suspend.
1852       }
1853 
1854       ThreadBlockInVM tbivm(this);
1855       java_suspend_self();
1856 
1857       // We're done with this suspend request, but we have to loop around
1858       // and check again. Eventually we will get SR_lock without a pending
1859       // external suspend request and will be able to mark ourselves as
1860       // exiting.
1861     }
1862     // no more external suspends are allowed at this point
1863   } else {
1864     // before_exit() has already posted JVMTI THREAD_END events
1865   }
1866 
1867   // Notify waiters on thread object. This has to be done after exit() is called
1868   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1869   // group should have the destroyed bit set before waiters are notified).
1870   ensure_join(this);
1871   assert(!this->has_pending_exception(), "ensure_join should have cleared");
1872 
1873   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1874   // held by this thread must be released. The spec does not distinguish
1875   // between JNI-acquired and regular Java monitors. We can only see
1876   // regular Java monitors here if monitor enter-exit matching is broken.
1877   //
1878   // Optionally release any monitors for regular JavaThread exits. This
1879   // is provided as a work around for any bugs in monitor enter-exit
1880   // matching. This can be expensive so it is not enabled by default.
1881   //
1882   // ensure_join() ignores IllegalThreadStateExceptions, and so does
1883   // ObjectSynchronizer::release_monitors_owned_by_thread().
1884   if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1885     // Sanity check even though JNI DetachCurrentThread() would have
1886     // returned JNI_ERR if there was a Java frame. JavaThread exit
1887     // should be done executing Java code by the time we get here.
1888     assert(!this->has_last_Java_frame(),
1889            "should not have a Java frame when detaching or exiting");
1890     ObjectSynchronizer::release_monitors_owned_by_thread(this);
1891     assert(!this->has_pending_exception(), "release_monitors should have cleared");
1892   }
1893 
1894   // These things needs to be done while we are still a Java Thread. Make sure that thread
1895   // is in a consistent state, in case GC happens
1896   assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1897 
1898   if (active_handles() != NULL) {
1899     JNIHandleBlock* block = active_handles();
1900     set_active_handles(NULL);
1901     JNIHandleBlock::release_block(block);
1902   }
1903 
1904   if (free_handle_block() != NULL) {
1905     JNIHandleBlock* block = free_handle_block();
1906     set_free_handle_block(NULL);
1907     JNIHandleBlock::release_block(block);
1908   }
1909 
1910   // These have to be removed while this is still a valid thread.
1911   remove_stack_guard_pages();
1912 
1913   if (UseTLAB) {
1914     tlab().make_parsable(true);  // retire TLAB
1915   }
1916 
1917   if (JvmtiEnv::environments_might_exist()) {
1918     JvmtiExport::cleanup_thread(this);
1919   }
1920 
1921   // We must flush any deferred card marks before removing a thread from
1922   // the list of active threads.
1923   Universe::heap()->flush_deferred_store_barrier(this);
1924   assert(deferred_card_mark().is_empty(), "Should have been flushed");
1925 
1926 #if INCLUDE_ALL_GCS
1927   // We must flush the G1-related buffers before removing a thread
1928   // from the list of active threads. We must do this after any deferred
1929   // card marks have been flushed (above) so that any entries that are
1930   // added to the thread's dirty card queue as a result are not lost.
1931   if (UseG1GC) {
1932     flush_barrier_queues();
1933   }
1934 #endif // INCLUDE_ALL_GCS
1935 
1936   log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
1937     exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
1938     os::current_thread_id());
1939 
1940   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1941   Threads::remove(this);
1942 }
1943 
1944 #if INCLUDE_ALL_GCS
1945 // Flush G1-related queues.
1946 void JavaThread::flush_barrier_queues() {
1947   satb_mark_queue().flush();
1948   dirty_card_queue().flush();
1949 }
1950 
1951 void JavaThread::initialize_queues() {
1952   assert(!SafepointSynchronize::is_at_safepoint(),
1953          "we should not be at a safepoint");
1954 
1955   SATBMarkQueue& satb_queue = satb_mark_queue();
1956   SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1957   // The SATB queue should have been constructed with its active
1958   // field set to false.
1959   assert(!satb_queue.is_active(), "SATB queue should not be active");
1960   assert(satb_queue.is_empty(), "SATB queue should be empty");
1961   // If we are creating the thread during a marking cycle, we should
1962   // set the active field of the SATB queue to true.
1963   if (satb_queue_set.is_active()) {
1964     satb_queue.set_active(true);
1965   }
1966 
1967   DirtyCardQueue& dirty_queue = dirty_card_queue();
1968   // The dirty card queue should have been constructed with its
1969   // active field set to true.
1970   assert(dirty_queue.is_active(), "dirty card queue should be active");
1971 }
1972 #endif // INCLUDE_ALL_GCS
1973 
1974 void JavaThread::cleanup_failed_attach_current_thread() {
1975   if (get_thread_profiler() != NULL) {
1976     get_thread_profiler()->disengage();
1977     ResourceMark rm;
1978     get_thread_profiler()->print(get_thread_name());
1979   }
1980 
1981   if (active_handles() != NULL) {
1982     JNIHandleBlock* block = active_handles();
1983     set_active_handles(NULL);
1984     JNIHandleBlock::release_block(block);
1985   }
1986 
1987   if (free_handle_block() != NULL) {
1988     JNIHandleBlock* block = free_handle_block();
1989     set_free_handle_block(NULL);
1990     JNIHandleBlock::release_block(block);
1991   }
1992 
1993   // These have to be removed while this is still a valid thread.
1994   remove_stack_guard_pages();
1995 
1996   if (UseTLAB) {
1997     tlab().make_parsable(true);  // retire TLAB, if any
1998   }
1999 
2000 #if INCLUDE_ALL_GCS
2001   if (UseG1GC) {
2002     flush_barrier_queues();
2003   }
2004 #endif // INCLUDE_ALL_GCS
2005 
2006   Threads::remove(this);
2007   delete this;
2008 }
2009 
2010 
2011 
2012 
2013 JavaThread* JavaThread::active() {
2014   Thread* thread = Thread::current();
2015   if (thread->is_Java_thread()) {
2016     return (JavaThread*) thread;
2017   } else {
2018     assert(thread->is_VM_thread(), "this must be a vm thread");
2019     VM_Operation* op = ((VMThread*) thread)->vm_operation();
2020     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2021     assert(ret->is_Java_thread(), "must be a Java thread");
2022     return ret;
2023   }
2024 }
2025 
2026 bool JavaThread::is_lock_owned(address adr) const {
2027   if (Thread::is_lock_owned(adr)) return true;
2028 
2029   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2030     if (chunk->contains(adr)) return true;
2031   }
2032 
2033   return false;
2034 }
2035 
2036 
2037 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2038   chunk->set_next(monitor_chunks());
2039   set_monitor_chunks(chunk);
2040 }
2041 
2042 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2043   guarantee(monitor_chunks() != NULL, "must be non empty");
2044   if (monitor_chunks() == chunk) {
2045     set_monitor_chunks(chunk->next());
2046   } else {
2047     MonitorChunk* prev = monitor_chunks();
2048     while (prev->next() != chunk) prev = prev->next();
2049     prev->set_next(chunk->next());
2050   }
2051 }
2052 
2053 // JVM support.
2054 
2055 // Note: this function shouldn't block if it's called in
2056 // _thread_in_native_trans state (such as from
2057 // check_special_condition_for_native_trans()).
2058 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2059 
2060   if (has_last_Java_frame() && has_async_condition()) {
2061     // If we are at a polling page safepoint (not a poll return)
2062     // then we must defer async exception because live registers
2063     // will be clobbered by the exception path. Poll return is
2064     // ok because the call we a returning from already collides
2065     // with exception handling registers and so there is no issue.
2066     // (The exception handling path kills call result registers but
2067     //  this is ok since the exception kills the result anyway).
2068 
2069     if (is_at_poll_safepoint()) {
2070       // if the code we are returning to has deoptimized we must defer
2071       // the exception otherwise live registers get clobbered on the
2072       // exception path before deoptimization is able to retrieve them.
2073       //
2074       RegisterMap map(this, false);
2075       frame caller_fr = last_frame().sender(&map);
2076       assert(caller_fr.is_compiled_frame(), "what?");
2077       if (caller_fr.is_deoptimized_frame()) {
2078         log_info(exceptions)("deferred async exception at compiled safepoint");
2079         return;
2080       }
2081     }
2082   }
2083 
2084   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2085   if (condition == _no_async_condition) {
2086     // Conditions have changed since has_special_runtime_exit_condition()
2087     // was called:
2088     // - if we were here only because of an external suspend request,
2089     //   then that was taken care of above (or cancelled) so we are done
2090     // - if we were here because of another async request, then it has
2091     //   been cleared between the has_special_runtime_exit_condition()
2092     //   and now so again we are done
2093     return;
2094   }
2095 
2096   // Check for pending async. exception
2097   if (_pending_async_exception != NULL) {
2098     // Only overwrite an already pending exception, if it is not a threadDeath.
2099     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2100 
2101       // We cannot call Exceptions::_throw(...) here because we cannot block
2102       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2103 
2104       if (log_is_enabled(Info, exceptions)) {
2105         ResourceMark rm;
2106         outputStream* logstream = Log(exceptions)::info_stream();
2107         logstream->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2108           if (has_last_Java_frame()) {
2109             frame f = last_frame();
2110            logstream->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2111           }
2112         logstream->print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2113       }
2114       _pending_async_exception = NULL;
2115       clear_has_async_exception();
2116     }
2117   }
2118 
2119   if (check_unsafe_error &&
2120       condition == _async_unsafe_access_error && !has_pending_exception()) {
2121     condition = _no_async_condition;  // done
2122     switch (thread_state()) {
2123     case _thread_in_vm: {
2124       JavaThread* THREAD = this;
2125       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2126     }
2127     case _thread_in_native: {
2128       ThreadInVMfromNative tiv(this);
2129       JavaThread* THREAD = this;
2130       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2131     }
2132     case _thread_in_Java: {
2133       ThreadInVMfromJava tiv(this);
2134       JavaThread* THREAD = this;
2135       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2136     }
2137     default:
2138       ShouldNotReachHere();
2139     }
2140   }
2141 
2142   assert(condition == _no_async_condition || has_pending_exception() ||
2143          (!check_unsafe_error && condition == _async_unsafe_access_error),
2144          "must have handled the async condition, if no exception");
2145 }
2146 
2147 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2148   //
2149   // Check for pending external suspend. Internal suspend requests do
2150   // not use handle_special_runtime_exit_condition().
2151   // If JNIEnv proxies are allowed, don't self-suspend if the target
2152   // thread is not the current thread. In older versions of jdbx, jdbx
2153   // threads could call into the VM with another thread's JNIEnv so we
2154   // can be here operating on behalf of a suspended thread (4432884).
2155   bool do_self_suspend = is_external_suspend_with_lock();
2156   if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2157     //
2158     // Because thread is external suspended the safepoint code will count
2159     // thread as at a safepoint. This can be odd because we can be here
2160     // as _thread_in_Java which would normally transition to _thread_blocked
2161     // at a safepoint. We would like to mark the thread as _thread_blocked
2162     // before calling java_suspend_self like all other callers of it but
2163     // we must then observe proper safepoint protocol. (We can't leave
2164     // _thread_blocked with a safepoint in progress). However we can be
2165     // here as _thread_in_native_trans so we can't use a normal transition
2166     // constructor/destructor pair because they assert on that type of
2167     // transition. We could do something like:
2168     //
2169     // JavaThreadState state = thread_state();
2170     // set_thread_state(_thread_in_vm);
2171     // {
2172     //   ThreadBlockInVM tbivm(this);
2173     //   java_suspend_self()
2174     // }
2175     // set_thread_state(_thread_in_vm_trans);
2176     // if (safepoint) block;
2177     // set_thread_state(state);
2178     //
2179     // but that is pretty messy. Instead we just go with the way the
2180     // code has worked before and note that this is the only path to
2181     // java_suspend_self that doesn't put the thread in _thread_blocked
2182     // mode.
2183 
2184     frame_anchor()->make_walkable(this);
2185     java_suspend_self();
2186 
2187     // We might be here for reasons in addition to the self-suspend request
2188     // so check for other async requests.
2189   }
2190 
2191   if (check_asyncs) {
2192     check_and_handle_async_exceptions();
2193   }
2194 }
2195 
2196 void JavaThread::send_thread_stop(oop java_throwable)  {
2197   assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2198   assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2199   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2200 
2201   // Do not throw asynchronous exceptions against the compiler thread
2202   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2203   if (!can_call_java()) return;
2204 
2205   {
2206     // Actually throw the Throwable against the target Thread - however
2207     // only if there is no thread death exception installed already.
2208     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2209       // If the topmost frame is a runtime stub, then we are calling into
2210       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2211       // must deoptimize the caller before continuing, as the compiled  exception handler table
2212       // may not be valid
2213       if (has_last_Java_frame()) {
2214         frame f = last_frame();
2215         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2216           // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2217           RegisterMap reg_map(this, UseBiasedLocking);
2218           frame compiled_frame = f.sender(&reg_map);
2219           if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2220             Deoptimization::deoptimize(this, compiled_frame, &reg_map);
2221           }
2222         }
2223       }
2224 
2225       // Set async. pending exception in thread.
2226       set_pending_async_exception(java_throwable);
2227 
2228       if (log_is_enabled(Info, exceptions)) {
2229          ResourceMark rm;
2230         log_info(exceptions)("Pending Async. exception installed of type: %s",
2231                              InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2232       }
2233       // for AbortVMOnException flag
2234       Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2235     }
2236   }
2237 
2238 
2239   // Interrupt thread so it will wake up from a potential wait()
2240   Thread::interrupt(this);
2241 }
2242 
2243 // External suspension mechanism.
2244 //
2245 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2246 // to any VM_locks and it is at a transition
2247 // Self-suspension will happen on the transition out of the vm.
2248 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2249 //
2250 // Guarantees on return:
2251 //   + Target thread will not execute any new bytecode (that's why we need to
2252 //     force a safepoint)
2253 //   + Target thread will not enter any new monitors
2254 //
2255 void JavaThread::java_suspend() {
2256   { MutexLocker mu(Threads_lock);
2257     if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2258       return;
2259     }
2260   }
2261 
2262   { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2263     if (!is_external_suspend()) {
2264       // a racing resume has cancelled us; bail out now
2265       return;
2266     }
2267 
2268     // suspend is done
2269     uint32_t debug_bits = 0;
2270     // Warning: is_ext_suspend_completed() may temporarily drop the
2271     // SR_lock to allow the thread to reach a stable thread state if
2272     // it is currently in a transient thread state.
2273     if (is_ext_suspend_completed(false /* !called_by_wait */,
2274                                  SuspendRetryDelay, &debug_bits)) {
2275       return;
2276     }
2277   }
2278 
2279   VM_ThreadSuspend vm_suspend;
2280   VMThread::execute(&vm_suspend);
2281 }
2282 
2283 // Part II of external suspension.
2284 // A JavaThread self suspends when it detects a pending external suspend
2285 // request. This is usually on transitions. It is also done in places
2286 // where continuing to the next transition would surprise the caller,
2287 // e.g., monitor entry.
2288 //
2289 // Returns the number of times that the thread self-suspended.
2290 //
2291 // Note: DO NOT call java_suspend_self() when you just want to block current
2292 //       thread. java_suspend_self() is the second stage of cooperative
2293 //       suspension for external suspend requests and should only be used
2294 //       to complete an external suspend request.
2295 //
2296 int JavaThread::java_suspend_self() {
2297   int ret = 0;
2298 
2299   // we are in the process of exiting so don't suspend
2300   if (is_exiting()) {
2301     clear_external_suspend();
2302     return ret;
2303   }
2304 
2305   assert(_anchor.walkable() ||
2306          (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2307          "must have walkable stack");
2308 
2309   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2310 
2311   assert(!this->is_ext_suspended(),
2312          "a thread trying to self-suspend should not already be suspended");
2313 
2314   if (this->is_suspend_equivalent()) {
2315     // If we are self-suspending as a result of the lifting of a
2316     // suspend equivalent condition, then the suspend_equivalent
2317     // flag is not cleared until we set the ext_suspended flag so
2318     // that wait_for_ext_suspend_completion() returns consistent
2319     // results.
2320     this->clear_suspend_equivalent();
2321   }
2322 
2323   // A racing resume may have cancelled us before we grabbed SR_lock
2324   // above. Or another external suspend request could be waiting for us
2325   // by the time we return from SR_lock()->wait(). The thread
2326   // that requested the suspension may already be trying to walk our
2327   // stack and if we return now, we can change the stack out from under
2328   // it. This would be a "bad thing (TM)" and cause the stack walker
2329   // to crash. We stay self-suspended until there are no more pending
2330   // external suspend requests.
2331   while (is_external_suspend()) {
2332     ret++;
2333     this->set_ext_suspended();
2334 
2335     // _ext_suspended flag is cleared by java_resume()
2336     while (is_ext_suspended()) {
2337       this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2338     }
2339   }
2340 
2341   return ret;
2342 }
2343 
2344 #ifdef ASSERT
2345 // verify the JavaThread has not yet been published in the Threads::list, and
2346 // hence doesn't need protection from concurrent access at this stage
2347 void JavaThread::verify_not_published() {
2348   if (!Threads_lock->owned_by_self()) {
2349     MutexLockerEx ml(Threads_lock,  Mutex::_no_safepoint_check_flag);
2350     assert(!Threads::includes(this),
2351            "java thread shouldn't have been published yet!");
2352   } else {
2353     assert(!Threads::includes(this),
2354            "java thread shouldn't have been published yet!");
2355   }
2356 }
2357 #endif
2358 
2359 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2360 // progress or when _suspend_flags is non-zero.
2361 // Current thread needs to self-suspend if there is a suspend request and/or
2362 // block if a safepoint is in progress.
2363 // Async exception ISN'T checked.
2364 // Note only the ThreadInVMfromNative transition can call this function
2365 // directly and when thread state is _thread_in_native_trans
2366 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2367   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2368 
2369   JavaThread *curJT = JavaThread::current();
2370   bool do_self_suspend = thread->is_external_suspend();
2371 
2372   assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2373 
2374   // If JNIEnv proxies are allowed, don't self-suspend if the target
2375   // thread is not the current thread. In older versions of jdbx, jdbx
2376   // threads could call into the VM with another thread's JNIEnv so we
2377   // can be here operating on behalf of a suspended thread (4432884).
2378   if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2379     JavaThreadState state = thread->thread_state();
2380 
2381     // We mark this thread_blocked state as a suspend-equivalent so
2382     // that a caller to is_ext_suspend_completed() won't be confused.
2383     // The suspend-equivalent state is cleared by java_suspend_self().
2384     thread->set_suspend_equivalent();
2385 
2386     // If the safepoint code sees the _thread_in_native_trans state, it will
2387     // wait until the thread changes to other thread state. There is no
2388     // guarantee on how soon we can obtain the SR_lock and complete the
2389     // self-suspend request. It would be a bad idea to let safepoint wait for
2390     // too long. Temporarily change the state to _thread_blocked to
2391     // let the VM thread know that this thread is ready for GC. The problem
2392     // of changing thread state is that safepoint could happen just after
2393     // java_suspend_self() returns after being resumed, and VM thread will
2394     // see the _thread_blocked state. We must check for safepoint
2395     // after restoring the state and make sure we won't leave while a safepoint
2396     // is in progress.
2397     thread->set_thread_state(_thread_blocked);
2398     thread->java_suspend_self();
2399     thread->set_thread_state(state);
2400     // Make sure new state is seen by VM thread
2401     if (os::is_MP()) {
2402       if (UseMembar) {
2403         // Force a fence between the write above and read below
2404         OrderAccess::fence();
2405       } else {
2406         // Must use this rather than serialization page in particular on Windows
2407         InterfaceSupport::serialize_memory(thread);
2408       }
2409     }
2410   }
2411 
2412   if (SafepointSynchronize::do_call_back()) {
2413     // If we are safepointing, then block the caller which may not be
2414     // the same as the target thread (see above).
2415     SafepointSynchronize::block(curJT);
2416   }
2417 
2418   if (thread->is_deopt_suspend()) {
2419     thread->clear_deopt_suspend();
2420     RegisterMap map(thread, false);
2421     frame f = thread->last_frame();
2422     while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2423       f = f.sender(&map);
2424     }
2425     if (f.id() == thread->must_deopt_id()) {
2426       thread->clear_must_deopt_id();
2427       f.deoptimize(thread);
2428     } else {
2429       fatal("missed deoptimization!");
2430     }
2431   }
2432 }
2433 
2434 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2435 // progress or when _suspend_flags is non-zero.
2436 // Current thread needs to self-suspend if there is a suspend request and/or
2437 // block if a safepoint is in progress.
2438 // Also check for pending async exception (not including unsafe access error).
2439 // Note only the native==>VM/Java barriers can call this function and when
2440 // thread state is _thread_in_native_trans.
2441 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2442   check_safepoint_and_suspend_for_native_trans(thread);
2443 
2444   if (thread->has_async_exception()) {
2445     // We are in _thread_in_native_trans state, don't handle unsafe
2446     // access error since that may block.
2447     thread->check_and_handle_async_exceptions(false);
2448   }
2449 }
2450 
2451 // This is a variant of the normal
2452 // check_special_condition_for_native_trans with slightly different
2453 // semantics for use by critical native wrappers.  It does all the
2454 // normal checks but also performs the transition back into
2455 // thread_in_Java state.  This is required so that critical natives
2456 // can potentially block and perform a GC if they are the last thread
2457 // exiting the GCLocker.
2458 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2459   check_special_condition_for_native_trans(thread);
2460 
2461   // Finish the transition
2462   thread->set_thread_state(_thread_in_Java);
2463 
2464   if (thread->do_critical_native_unlock()) {
2465     ThreadInVMfromJavaNoAsyncException tiv(thread);
2466     GCLocker::unlock_critical(thread);
2467     thread->clear_critical_native_unlock();
2468   }
2469 }
2470 
2471 // We need to guarantee the Threads_lock here, since resumes are not
2472 // allowed during safepoint synchronization
2473 // Can only resume from an external suspension
2474 void JavaThread::java_resume() {
2475   assert_locked_or_safepoint(Threads_lock);
2476 
2477   // Sanity check: thread is gone, has started exiting or the thread
2478   // was not externally suspended.
2479   if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2480     return;
2481   }
2482 
2483   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2484 
2485   clear_external_suspend();
2486 
2487   if (is_ext_suspended()) {
2488     clear_ext_suspended();
2489     SR_lock()->notify_all();
2490   }
2491 }
2492 
2493 size_t JavaThread::_stack_red_zone_size = 0;
2494 size_t JavaThread::_stack_yellow_zone_size = 0;
2495 size_t JavaThread::_stack_reserved_zone_size = 0;
2496 size_t JavaThread::_stack_shadow_zone_size = 0;
2497 
2498 void JavaThread::create_stack_guard_pages() {
2499   if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; }
2500   address low_addr = stack_end();
2501   size_t len = stack_guard_zone_size();
2502 
2503   int must_commit = os::must_commit_stack_guard_pages();
2504   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2505 
2506   if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2507     log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2508     return;
2509   }
2510 
2511   if (os::guard_memory((char *) low_addr, len)) {
2512     _stack_guard_state = stack_guard_enabled;
2513   } else {
2514     log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2515       PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2516     if (os::uncommit_memory((char *) low_addr, len)) {
2517       log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2518     }
2519     return;
2520   }
2521 
2522   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2523     PTR_FORMAT "-" PTR_FORMAT ".",
2524     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2525 }
2526 
2527 void JavaThread::remove_stack_guard_pages() {
2528   assert(Thread::current() == this, "from different thread");
2529   if (_stack_guard_state == stack_guard_unused) return;
2530   address low_addr = stack_end();
2531   size_t len = stack_guard_zone_size();
2532 
2533   if (os::must_commit_stack_guard_pages()) {
2534     if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2535       _stack_guard_state = stack_guard_unused;
2536     } else {
2537       log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2538         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2539       return;
2540     }
2541   } else {
2542     if (_stack_guard_state == stack_guard_unused) return;
2543     if (os::unguard_memory((char *) low_addr, len)) {
2544       _stack_guard_state = stack_guard_unused;
2545     } else {
2546       log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2547         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2548       return;
2549     }
2550   }
2551 
2552   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2553     PTR_FORMAT "-" PTR_FORMAT ".",
2554     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2555 }
2556 
2557 void JavaThread::enable_stack_reserved_zone() {
2558   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2559   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2560 
2561   // The base notation is from the stack's point of view, growing downward.
2562   // We need to adjust it to work correctly with guard_memory()
2563   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2564 
2565   guarantee(base < stack_base(),"Error calculating stack reserved zone");
2566   guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2567 
2568   if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2569     _stack_guard_state = stack_guard_enabled;
2570   } else {
2571     warning("Attempt to guard stack reserved zone failed.");
2572   }
2573   enable_register_stack_guard();
2574 }
2575 
2576 void JavaThread::disable_stack_reserved_zone() {
2577   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2578   assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2579 
2580   // Simply return if called for a thread that does not use guard pages.
2581   if (_stack_guard_state == stack_guard_unused) return;
2582 
2583   // The base notation is from the stack's point of view, growing downward.
2584   // We need to adjust it to work correctly with guard_memory()
2585   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2586 
2587   if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2588     _stack_guard_state = stack_guard_reserved_disabled;
2589   } else {
2590     warning("Attempt to unguard stack reserved zone failed.");
2591   }
2592   disable_register_stack_guard();
2593 }
2594 
2595 void JavaThread::enable_stack_yellow_reserved_zone() {
2596   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2597   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2598 
2599   // The base notation is from the stacks point of view, growing downward.
2600   // We need to adjust it to work correctly with guard_memory()
2601   address base = stack_red_zone_base();
2602 
2603   guarantee(base < stack_base(), "Error calculating stack yellow zone");
2604   guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2605 
2606   if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2607     _stack_guard_state = stack_guard_enabled;
2608   } else {
2609     warning("Attempt to guard stack yellow zone failed.");
2610   }
2611   enable_register_stack_guard();
2612 }
2613 
2614 void JavaThread::disable_stack_yellow_reserved_zone() {
2615   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2616   assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2617 
2618   // Simply return if called for a thread that does not use guard pages.
2619   if (_stack_guard_state == stack_guard_unused) return;
2620 
2621   // The base notation is from the stacks point of view, growing downward.
2622   // We need to adjust it to work correctly with guard_memory()
2623   address base = stack_red_zone_base();
2624 
2625   if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2626     _stack_guard_state = stack_guard_yellow_reserved_disabled;
2627   } else {
2628     warning("Attempt to unguard stack yellow zone failed.");
2629   }
2630   disable_register_stack_guard();
2631 }
2632 
2633 void JavaThread::enable_stack_red_zone() {
2634   // The base notation is from the stacks point of view, growing downward.
2635   // We need to adjust it to work correctly with guard_memory()
2636   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2637   address base = stack_red_zone_base() - stack_red_zone_size();
2638 
2639   guarantee(base < stack_base(), "Error calculating stack red zone");
2640   guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2641 
2642   if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2643     warning("Attempt to guard stack red zone failed.");
2644   }
2645 }
2646 
2647 void JavaThread::disable_stack_red_zone() {
2648   // The base notation is from the stacks point of view, growing downward.
2649   // We need to adjust it to work correctly with guard_memory()
2650   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2651   address base = stack_red_zone_base() - stack_red_zone_size();
2652   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2653     warning("Attempt to unguard stack red zone failed.");
2654   }
2655 }
2656 
2657 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2658   // ignore is there is no stack
2659   if (!has_last_Java_frame()) return;
2660   // traverse the stack frames. Starts from top frame.
2661   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2662     frame* fr = fst.current();
2663     f(fr, fst.register_map());
2664   }
2665 }
2666 
2667 
2668 #ifndef PRODUCT
2669 // Deoptimization
2670 // Function for testing deoptimization
2671 void JavaThread::deoptimize() {
2672   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2673   StackFrameStream fst(this, UseBiasedLocking);
2674   bool deopt = false;           // Dump stack only if a deopt actually happens.
2675   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2676   // Iterate over all frames in the thread and deoptimize
2677   for (; !fst.is_done(); fst.next()) {
2678     if (fst.current()->can_be_deoptimized()) {
2679 
2680       if (only_at) {
2681         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
2682         // consists of comma or carriage return separated numbers so
2683         // search for the current bci in that string.
2684         address pc = fst.current()->pc();
2685         nmethod* nm =  (nmethod*) fst.current()->cb();
2686         ScopeDesc* sd = nm->scope_desc_at(pc);
2687         char buffer[8];
2688         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2689         size_t len = strlen(buffer);
2690         const char * found = strstr(DeoptimizeOnlyAt, buffer);
2691         while (found != NULL) {
2692           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2693               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2694             // Check that the bci found is bracketed by terminators.
2695             break;
2696           }
2697           found = strstr(found + 1, buffer);
2698         }
2699         if (!found) {
2700           continue;
2701         }
2702       }
2703 
2704       if (DebugDeoptimization && !deopt) {
2705         deopt = true; // One-time only print before deopt
2706         tty->print_cr("[BEFORE Deoptimization]");
2707         trace_frames();
2708         trace_stack();
2709       }
2710       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2711     }
2712   }
2713 
2714   if (DebugDeoptimization && deopt) {
2715     tty->print_cr("[AFTER Deoptimization]");
2716     trace_frames();
2717   }
2718 }
2719 
2720 
2721 // Make zombies
2722 void JavaThread::make_zombies() {
2723   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2724     if (fst.current()->can_be_deoptimized()) {
2725       // it is a Java nmethod
2726       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2727       nm->make_not_entrant();
2728     }
2729   }
2730 }
2731 #endif // PRODUCT
2732 
2733 
2734 void JavaThread::deoptimized_wrt_marked_nmethods() {
2735   if (!has_last_Java_frame()) return;
2736   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2737   StackFrameStream fst(this, UseBiasedLocking);
2738   for (; !fst.is_done(); fst.next()) {
2739     if (fst.current()->should_be_deoptimized()) {
2740       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2741     }
2742   }
2743 }
2744 
2745 
2746 // If the caller is a NamedThread, then remember, in the current scope,
2747 // the given JavaThread in its _processed_thread field.
2748 class RememberProcessedThread: public StackObj {
2749   NamedThread* _cur_thr;
2750  public:
2751   RememberProcessedThread(JavaThread* jthr) {
2752     Thread* thread = Thread::current();
2753     if (thread->is_Named_thread()) {
2754       _cur_thr = (NamedThread *)thread;
2755       _cur_thr->set_processed_thread(jthr);
2756     } else {
2757       _cur_thr = NULL;
2758     }
2759   }
2760 
2761   ~RememberProcessedThread() {
2762     if (_cur_thr) {
2763       _cur_thr->set_processed_thread(NULL);
2764     }
2765   }
2766 };
2767 
2768 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2769   // Verify that the deferred card marks have been flushed.
2770   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2771 
2772   // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2773   // since there may be more than one thread using each ThreadProfiler.
2774 
2775   // Traverse the GCHandles
2776   Thread::oops_do(f, cf);
2777 
2778   JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2779 
2780   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2781          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2782 
2783   if (has_last_Java_frame()) {
2784     // Record JavaThread to GC thread
2785     RememberProcessedThread rpt(this);
2786 
2787     // Traverse the privileged stack
2788     if (_privileged_stack_top != NULL) {
2789       _privileged_stack_top->oops_do(f);
2790     }
2791 
2792     // traverse the registered growable array
2793     if (_array_for_gc != NULL) {
2794       for (int index = 0; index < _array_for_gc->length(); index++) {
2795         f->do_oop(_array_for_gc->adr_at(index));
2796       }
2797     }
2798 
2799     // Traverse the monitor chunks
2800     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2801       chunk->oops_do(f);
2802     }
2803 
2804     // Traverse the execution stack
2805     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2806       fst.current()->oops_do(f, cf, fst.register_map());
2807     }
2808   }
2809 
2810   // callee_target is never live across a gc point so NULL it here should
2811   // it still contain a methdOop.
2812 
2813   set_callee_target(NULL);
2814 
2815   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2816   // If we have deferred set_locals there might be oops waiting to be
2817   // written
2818   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2819   if (list != NULL) {
2820     for (int i = 0; i < list->length(); i++) {
2821       list->at(i)->oops_do(f);
2822     }
2823   }
2824 
2825   // Traverse instance variables at the end since the GC may be moving things
2826   // around using this function
2827   f->do_oop((oop*) &_threadObj);
2828   f->do_oop((oop*) &_vm_result);
2829   f->do_oop((oop*) &_exception_oop);
2830   f->do_oop((oop*) &_pending_async_exception);
2831 
2832   if (jvmti_thread_state() != NULL) {
2833     jvmti_thread_state()->oops_do(f);
2834   }
2835 }
2836 
2837 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2838   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2839          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2840 
2841   if (has_last_Java_frame()) {
2842     // Traverse the execution stack
2843     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2844       fst.current()->nmethods_do(cf);
2845     }
2846   }
2847 }
2848 
2849 void JavaThread::metadata_do(void f(Metadata*)) {
2850   if (has_last_Java_frame()) {
2851     // Traverse the execution stack to call f() on the methods in the stack
2852     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2853       fst.current()->metadata_do(f);
2854     }
2855   } else if (is_Compiler_thread()) {
2856     // need to walk ciMetadata in current compile tasks to keep alive.
2857     CompilerThread* ct = (CompilerThread*)this;
2858     if (ct->env() != NULL) {
2859       ct->env()->metadata_do(f);
2860     }
2861     if (ct->task() != NULL) {
2862       ct->task()->metadata_do(f);
2863     }
2864   }
2865 }
2866 
2867 // Printing
2868 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2869   switch (_thread_state) {
2870   case _thread_uninitialized:     return "_thread_uninitialized";
2871   case _thread_new:               return "_thread_new";
2872   case _thread_new_trans:         return "_thread_new_trans";
2873   case _thread_in_native:         return "_thread_in_native";
2874   case _thread_in_native_trans:   return "_thread_in_native_trans";
2875   case _thread_in_vm:             return "_thread_in_vm";
2876   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
2877   case _thread_in_Java:           return "_thread_in_Java";
2878   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
2879   case _thread_blocked:           return "_thread_blocked";
2880   case _thread_blocked_trans:     return "_thread_blocked_trans";
2881   default:                        return "unknown thread state";
2882   }
2883 }
2884 
2885 #ifndef PRODUCT
2886 void JavaThread::print_thread_state_on(outputStream *st) const {
2887   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
2888 };
2889 void JavaThread::print_thread_state() const {
2890   print_thread_state_on(tty);
2891 }
2892 #endif // PRODUCT
2893 
2894 // Called by Threads::print() for VM_PrintThreads operation
2895 void JavaThread::print_on(outputStream *st) const {
2896   st->print_raw("\"");
2897   st->print_raw(get_thread_name());
2898   st->print_raw("\" ");
2899   oop thread_oop = threadObj();
2900   if (thread_oop != NULL) {
2901     st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop));
2902     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
2903     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2904   }
2905   Thread::print_on(st);
2906   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2907   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2908   if (thread_oop != NULL) {
2909     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2910   }
2911 #ifndef PRODUCT
2912   print_thread_state_on(st);
2913   _safepoint_state->print_on(st);
2914 #endif // PRODUCT
2915   if (is_Compiler_thread()) {
2916     CompilerThread* ct = (CompilerThread*)this;
2917     if (ct->task() != NULL) {
2918       st->print("   Compiling: ");
2919       ct->task()->print(st, NULL, true, false);
2920     } else {
2921       st->print("   No compile task");
2922     }
2923     st->cr();
2924   }
2925 }
2926 
2927 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2928   st->print("%s", get_thread_name_string(buf, buflen));
2929 }
2930 
2931 // Called by fatal error handler. The difference between this and
2932 // JavaThread::print() is that we can't grab lock or allocate memory.
2933 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2934   st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2935   oop thread_obj = threadObj();
2936   if (thread_obj != NULL) {
2937     if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2938   }
2939   st->print(" [");
2940   st->print("%s", _get_thread_state_name(_thread_state));
2941   if (osthread()) {
2942     st->print(", id=%d", osthread()->thread_id());
2943   }
2944   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2945             p2i(stack_end()), p2i(stack_base()));
2946   st->print("]");
2947   return;
2948 }
2949 
2950 // Verification
2951 
2952 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2953 
2954 void JavaThread::verify() {
2955   // Verify oops in the thread.
2956   oops_do(&VerifyOopClosure::verify_oop, NULL);
2957 
2958   // Verify the stack frames.
2959   frames_do(frame_verify);
2960 }
2961 
2962 // CR 6300358 (sub-CR 2137150)
2963 // Most callers of this method assume that it can't return NULL but a
2964 // thread may not have a name whilst it is in the process of attaching to
2965 // the VM - see CR 6412693, and there are places where a JavaThread can be
2966 // seen prior to having it's threadObj set (eg JNI attaching threads and
2967 // if vm exit occurs during initialization). These cases can all be accounted
2968 // for such that this method never returns NULL.
2969 const char* JavaThread::get_thread_name() const {
2970 #ifdef ASSERT
2971   // early safepoints can hit while current thread does not yet have TLS
2972   if (!SafepointSynchronize::is_at_safepoint()) {
2973     Thread *cur = Thread::current();
2974     if (!(cur->is_Java_thread() && cur == this)) {
2975       // Current JavaThreads are allowed to get their own name without
2976       // the Threads_lock.
2977       assert_locked_or_safepoint(Threads_lock);
2978     }
2979   }
2980 #endif // ASSERT
2981   return get_thread_name_string();
2982 }
2983 
2984 // Returns a non-NULL representation of this thread's name, or a suitable
2985 // descriptive string if there is no set name
2986 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2987   const char* name_str;
2988   oop thread_obj = threadObj();
2989   if (thread_obj != NULL) {
2990     oop name = java_lang_Thread::name(thread_obj);
2991     if (name != NULL) {
2992       if (buf == NULL) {
2993         name_str = java_lang_String::as_utf8_string(name);
2994       } else {
2995         name_str = java_lang_String::as_utf8_string(name, buf, buflen);
2996       }
2997     } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
2998       name_str = "<no-name - thread is attaching>";
2999     } else {
3000       name_str = Thread::name();
3001     }
3002   } else {
3003     name_str = Thread::name();
3004   }
3005   assert(name_str != NULL, "unexpected NULL thread name");
3006   return name_str;
3007 }
3008 
3009 
3010 const char* JavaThread::get_threadgroup_name() const {
3011   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3012   oop thread_obj = threadObj();
3013   if (thread_obj != NULL) {
3014     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3015     if (thread_group != NULL) {
3016       // ThreadGroup.name can be null
3017       return java_lang_ThreadGroup::name(thread_group);
3018     }
3019   }
3020   return NULL;
3021 }
3022 
3023 const char* JavaThread::get_parent_name() const {
3024   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3025   oop thread_obj = threadObj();
3026   if (thread_obj != NULL) {
3027     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3028     if (thread_group != NULL) {
3029       oop parent = java_lang_ThreadGroup::parent(thread_group);
3030       if (parent != NULL) {
3031         // ThreadGroup.name can be null
3032         return java_lang_ThreadGroup::name(parent);
3033       }
3034     }
3035   }
3036   return NULL;
3037 }
3038 
3039 ThreadPriority JavaThread::java_priority() const {
3040   oop thr_oop = threadObj();
3041   if (thr_oop == NULL) return NormPriority; // Bootstrapping
3042   ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3043   assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3044   return priority;
3045 }
3046 
3047 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3048 
3049   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3050   // Link Java Thread object <-> C++ Thread
3051 
3052   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3053   // and put it into a new Handle.  The Handle "thread_oop" can then
3054   // be used to pass the C++ thread object to other methods.
3055 
3056   // Set the Java level thread object (jthread) field of the
3057   // new thread (a JavaThread *) to C++ thread object using the
3058   // "thread_oop" handle.
3059 
3060   // Set the thread field (a JavaThread *) of the
3061   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3062 
3063   Handle thread_oop(Thread::current(),
3064                     JNIHandles::resolve_non_null(jni_thread));
3065   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3066          "must be initialized");
3067   set_threadObj(thread_oop());
3068   java_lang_Thread::set_thread(thread_oop(), this);
3069 
3070   if (prio == NoPriority) {
3071     prio = java_lang_Thread::priority(thread_oop());
3072     assert(prio != NoPriority, "A valid priority should be present");
3073   }
3074 
3075   // Push the Java priority down to the native thread; needs Threads_lock
3076   Thread::set_priority(this, prio);
3077 
3078   prepare_ext();
3079 
3080   // Add the new thread to the Threads list and set it in motion.
3081   // We must have threads lock in order to call Threads::add.
3082   // It is crucial that we do not block before the thread is
3083   // added to the Threads list for if a GC happens, then the java_thread oop
3084   // will not be visited by GC.
3085   Threads::add(this);
3086 }
3087 
3088 oop JavaThread::current_park_blocker() {
3089   // Support for JSR-166 locks
3090   oop thread_oop = threadObj();
3091   if (thread_oop != NULL &&
3092       JDK_Version::current().supports_thread_park_blocker()) {
3093     return java_lang_Thread::park_blocker(thread_oop);
3094   }
3095   return NULL;
3096 }
3097 
3098 
3099 void JavaThread::print_stack_on(outputStream* st) {
3100   if (!has_last_Java_frame()) return;
3101   ResourceMark rm;
3102   HandleMark   hm;
3103 
3104   RegisterMap reg_map(this);
3105   vframe* start_vf = last_java_vframe(&reg_map);
3106   int count = 0;
3107   for (vframe* f = start_vf; f; f = f->sender()) {
3108     if (f->is_java_frame()) {
3109       javaVFrame* jvf = javaVFrame::cast(f);
3110       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3111 
3112       // Print out lock information
3113       if (JavaMonitorsInStackTrace) {
3114         jvf->print_lock_info_on(st, count);
3115       }
3116     } else {
3117       // Ignore non-Java frames
3118     }
3119 
3120     // Bail-out case for too deep stacks
3121     count++;
3122     if (MaxJavaStackTraceDepth == count) return;
3123   }
3124 }
3125 
3126 
3127 // JVMTI PopFrame support
3128 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3129   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3130   if (in_bytes(size_in_bytes) != 0) {
3131     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3132     _popframe_preserved_args_size = in_bytes(size_in_bytes);
3133     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3134   }
3135 }
3136 
3137 void* JavaThread::popframe_preserved_args() {
3138   return _popframe_preserved_args;
3139 }
3140 
3141 ByteSize JavaThread::popframe_preserved_args_size() {
3142   return in_ByteSize(_popframe_preserved_args_size);
3143 }
3144 
3145 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3146   int sz = in_bytes(popframe_preserved_args_size());
3147   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3148   return in_WordSize(sz / wordSize);
3149 }
3150 
3151 void JavaThread::popframe_free_preserved_args() {
3152   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3153   FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3154   _popframe_preserved_args = NULL;
3155   _popframe_preserved_args_size = 0;
3156 }
3157 
3158 #ifndef PRODUCT
3159 
3160 void JavaThread::trace_frames() {
3161   tty->print_cr("[Describe stack]");
3162   int frame_no = 1;
3163   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3164     tty->print("  %d. ", frame_no++);
3165     fst.current()->print_value_on(tty, this);
3166     tty->cr();
3167   }
3168 }
3169 
3170 class PrintAndVerifyOopClosure: public OopClosure {
3171  protected:
3172   template <class T> inline void do_oop_work(T* p) {
3173     oop obj = oopDesc::load_decode_heap_oop(p);
3174     if (obj == NULL) return;
3175     tty->print(INTPTR_FORMAT ": ", p2i(p));
3176     if (obj->is_oop_or_null()) {
3177       if (obj->is_objArray()) {
3178         tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3179       } else {
3180         obj->print();
3181       }
3182     } else {
3183       tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3184     }
3185     tty->cr();
3186   }
3187  public:
3188   virtual void do_oop(oop* p) { do_oop_work(p); }
3189   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
3190 };
3191 
3192 
3193 static void oops_print(frame* f, const RegisterMap *map) {
3194   PrintAndVerifyOopClosure print;
3195   f->print_value();
3196   f->oops_do(&print, NULL, (RegisterMap*)map);
3197 }
3198 
3199 // Print our all the locations that contain oops and whether they are
3200 // valid or not.  This useful when trying to find the oldest frame
3201 // where an oop has gone bad since the frame walk is from youngest to
3202 // oldest.
3203 void JavaThread::trace_oops() {
3204   tty->print_cr("[Trace oops]");
3205   frames_do(oops_print);
3206 }
3207 
3208 
3209 #ifdef ASSERT
3210 // Print or validate the layout of stack frames
3211 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3212   ResourceMark rm;
3213   PRESERVE_EXCEPTION_MARK;
3214   FrameValues values;
3215   int frame_no = 0;
3216   for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3217     fst.current()->describe(values, ++frame_no);
3218     if (depth == frame_no) break;
3219   }
3220   if (validate_only) {
3221     values.validate();
3222   } else {
3223     tty->print_cr("[Describe stack layout]");
3224     values.print(this);
3225   }
3226 }
3227 #endif
3228 
3229 void JavaThread::trace_stack_from(vframe* start_vf) {
3230   ResourceMark rm;
3231   int vframe_no = 1;
3232   for (vframe* f = start_vf; f; f = f->sender()) {
3233     if (f->is_java_frame()) {
3234       javaVFrame::cast(f)->print_activation(vframe_no++);
3235     } else {
3236       f->print();
3237     }
3238     if (vframe_no > StackPrintLimit) {
3239       tty->print_cr("...<more frames>...");
3240       return;
3241     }
3242   }
3243 }
3244 
3245 
3246 void JavaThread::trace_stack() {
3247   if (!has_last_Java_frame()) return;
3248   ResourceMark rm;
3249   HandleMark   hm;
3250   RegisterMap reg_map(this);
3251   trace_stack_from(last_java_vframe(&reg_map));
3252 }
3253 
3254 
3255 #endif // PRODUCT
3256 
3257 
3258 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3259   assert(reg_map != NULL, "a map must be given");
3260   frame f = last_frame();
3261   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3262     if (vf->is_java_frame()) return javaVFrame::cast(vf);
3263   }
3264   return NULL;
3265 }
3266 
3267 
3268 Klass* JavaThread::security_get_caller_class(int depth) {
3269   vframeStream vfst(this);
3270   vfst.security_get_caller_frame(depth);
3271   if (!vfst.at_end()) {
3272     return vfst.method()->method_holder();
3273   }
3274   return NULL;
3275 }
3276 
3277 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3278   assert(thread->is_Compiler_thread(), "must be compiler thread");
3279   CompileBroker::compiler_thread_loop();
3280 }
3281 
3282 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3283   NMethodSweeper::sweeper_loop();
3284 }
3285 
3286 // Create a CompilerThread
3287 CompilerThread::CompilerThread(CompileQueue* queue,
3288                                CompilerCounters* counters)
3289                                : JavaThread(&compiler_thread_entry) {
3290   _env   = NULL;
3291   _log   = NULL;
3292   _task  = NULL;
3293   _queue = queue;
3294   _counters = counters;
3295   _buffer_blob = NULL;
3296   _compiler = NULL;
3297 
3298 #ifndef PRODUCT
3299   _ideal_graph_printer = NULL;
3300 #endif
3301 }
3302 
3303 bool CompilerThread::can_call_java() const {
3304   return _compiler != NULL && _compiler->is_jvmci();
3305 }
3306 
3307 // Create sweeper thread
3308 CodeCacheSweeperThread::CodeCacheSweeperThread()
3309 : JavaThread(&sweeper_thread_entry) {
3310   _scanned_compiled_method = NULL;
3311 }
3312 
3313 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3314   JavaThread::oops_do(f, cf);
3315   if (_scanned_compiled_method != NULL && cf != NULL) {
3316     // Safepoints can occur when the sweeper is scanning an nmethod so
3317     // process it here to make sure it isn't unloaded in the middle of
3318     // a scan.
3319     cf->do_code_blob(_scanned_compiled_method);
3320   }
3321 }
3322 
3323 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3324   JavaThread::nmethods_do(cf);
3325   if (_scanned_compiled_method != NULL && cf != NULL) {
3326     // Safepoints can occur when the sweeper is scanning an nmethod so
3327     // process it here to make sure it isn't unloaded in the middle of
3328     // a scan.
3329     cf->do_code_blob(_scanned_compiled_method);
3330   }
3331 }
3332 
3333 
3334 // ======= Threads ========
3335 
3336 // The Threads class links together all active threads, and provides
3337 // operations over all threads.  It is protected by its own Mutex
3338 // lock, which is also used in other contexts to protect thread
3339 // operations from having the thread being operated on from exiting
3340 // and going away unexpectedly (e.g., safepoint synchronization)
3341 
3342 JavaThread* Threads::_thread_list = NULL;
3343 int         Threads::_number_of_threads = 0;
3344 int         Threads::_number_of_non_daemon_threads = 0;
3345 int         Threads::_return_code = 0;
3346 int         Threads::_thread_claim_parity = 0;
3347 size_t      JavaThread::_stack_size_at_create = 0;
3348 #ifdef ASSERT
3349 bool        Threads::_vm_complete = false;
3350 #endif
3351 
3352 // All JavaThreads
3353 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3354 
3355 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3356 void Threads::threads_do(ThreadClosure* tc) {
3357   assert_locked_or_safepoint(Threads_lock);
3358   // ALL_JAVA_THREADS iterates through all JavaThreads
3359   ALL_JAVA_THREADS(p) {
3360     tc->do_thread(p);
3361   }
3362   // Someday we could have a table or list of all non-JavaThreads.
3363   // For now, just manually iterate through them.
3364   tc->do_thread(VMThread::vm_thread());
3365   Universe::heap()->gc_threads_do(tc);
3366   WatcherThread *wt = WatcherThread::watcher_thread();
3367   // Strictly speaking, the following NULL check isn't sufficient to make sure
3368   // the data for WatcherThread is still valid upon being examined. However,
3369   // considering that WatchThread terminates when the VM is on the way to
3370   // exit at safepoint, the chance of the above is extremely small. The right
3371   // way to prevent termination of WatcherThread would be to acquire
3372   // Terminator_lock, but we can't do that without violating the lock rank
3373   // checking in some cases.
3374   if (wt != NULL) {
3375     tc->do_thread(wt);
3376   }
3377 
3378   // If CompilerThreads ever become non-JavaThreads, add them here
3379 }
3380 
3381 // The system initialization in the library has three phases.
3382 //
3383 // Phase 1: java.lang.System class initialization
3384 //     java.lang.System is a primordial class loaded and initialized
3385 //     by the VM early during startup.  java.lang.System.<clinit>
3386 //     only does registerNatives and keeps the rest of the class
3387 //     initialization work later until thread initialization completes.
3388 //
3389 //     System.initPhase1 initializes the system properties, the static
3390 //     fields in, out, and err. Set up java signal handlers, OS-specific
3391 //     system settings, and thread group of the main thread.
3392 static void call_initPhase1(TRAPS) {
3393   Klass* klass =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3394   JavaValue result(T_VOID);
3395   JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3396                                          vmSymbols::void_method_signature(), CHECK);
3397 }
3398 
3399 // Phase 2. Module system initialization
3400 //     This will initialize the module system.  Only java.base classes
3401 //     can be loaded until phase 2 completes.
3402 //
3403 //     Call System.initPhase2 after the compiler initialization and jsr292
3404 //     classes get initialized because module initialization runs a lot of java
3405 //     code, that for performance reasons, should be compiled.  Also, this will
3406 //     enable the startup code to use lambda and other language features in this
3407 //     phase and onward.
3408 //
3409 //     After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3410 static void call_initPhase2(TRAPS) {
3411   TraceTime timer("Phase2 initialization", TRACETIME_LOG(Info, module, startuptime));
3412 
3413   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3414 
3415   JavaValue result(T_INT);
3416   JavaCallArguments args;
3417   args.push_int(DisplayVMOutputToStderr);
3418   args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3419   JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3420                                          vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3421   if (result.get_jint() != JNI_OK) {
3422     vm_exit_during_initialization(); // no message or exception
3423   }
3424 
3425   universe_post_module_init();
3426 }
3427 
3428 // Phase 3. final setup - set security manager, system class loader and TCCL
3429 //
3430 //     This will instantiate and set the security manager, set the system class
3431 //     loader as well as the thread context class loader.  The security manager
3432 //     and system class loader may be a custom class loaded from -Xbootclasspath/a,
3433 //     other modules or the application's classpath.
3434 static void call_initPhase3(TRAPS) {
3435   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3436   JavaValue result(T_VOID);
3437   JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3438                                          vmSymbols::void_method_signature(), CHECK);
3439 }
3440 
3441 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3442   TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3443 
3444   if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3445     create_vm_init_libraries();
3446   }
3447 
3448   initialize_class(vmSymbols::java_lang_String(), CHECK);
3449 
3450   // Inject CompactStrings value after the static initializers for String ran.
3451   java_lang_String::set_compact_strings(CompactStrings);
3452 
3453   // Initialize java_lang.System (needed before creating the thread)
3454   initialize_class(vmSymbols::java_lang_System(), CHECK);
3455   // The VM creates & returns objects of this class. Make sure it's initialized.
3456   initialize_class(vmSymbols::java_lang_Class(), CHECK);
3457   initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3458   Handle thread_group = create_initial_thread_group(CHECK);
3459   Universe::set_main_thread_group(thread_group());
3460   initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3461   oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3462   main_thread->set_threadObj(thread_object);
3463   // Set thread status to running since main thread has
3464   // been started and running.
3465   java_lang_Thread::set_thread_status(thread_object,
3466                                       java_lang_Thread::RUNNABLE);
3467 
3468   // The VM creates objects of this class.
3469   initialize_class(vmSymbols::java_lang_Module(), CHECK);
3470 
3471   // The VM preresolves methods to these classes. Make sure that they get initialized
3472   initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3473   initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3474 
3475   // Phase 1 of the system initialization in the library, java.lang.System class initialization
3476   call_initPhase1(CHECK);
3477 
3478   // get the Java runtime name after java.lang.System is initialized
3479   JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3480   JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3481 
3482   // an instance of OutOfMemory exception has been allocated earlier
3483   initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3484   initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3485   initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3486   initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3487   initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3488   initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3489   initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3490   initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3491 }
3492 
3493 void Threads::initialize_jsr292_core_classes(TRAPS) {
3494   TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3495 
3496   initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3497   initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3498   initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3499   initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3500 }
3501 
3502 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3503   extern void JDK_Version_init();
3504 
3505   // Preinitialize version info.
3506   VM_Version::early_initialize();
3507 
3508   // Check version
3509   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3510 
3511   // Initialize library-based TLS
3512   ThreadLocalStorage::init();
3513 
3514   // Initialize the output stream module
3515   ostream_init();
3516 
3517   // Process java launcher properties.
3518   Arguments::process_sun_java_launcher_properties(args);
3519 
3520   // Initialize the os module
3521   os::init();
3522 
3523   // Record VM creation timing statistics
3524   TraceVmCreationTime create_vm_timer;
3525   create_vm_timer.start();
3526 
3527   // Initialize system properties.
3528   Arguments::init_system_properties();
3529 
3530   // So that JDK version can be used as a discriminator when parsing arguments
3531   JDK_Version_init();
3532 
3533   // Update/Initialize System properties after JDK version number is known
3534   Arguments::init_version_specific_system_properties();
3535 
3536   // Make sure to initialize log configuration *before* parsing arguments
3537   LogConfiguration::initialize(create_vm_timer.begin_time());
3538 
3539   // Parse arguments
3540   jint parse_result = Arguments::parse(args);
3541   if (parse_result != JNI_OK) return parse_result;
3542 
3543   os::init_before_ergo();
3544 
3545   jint ergo_result = Arguments::apply_ergo();
3546   if (ergo_result != JNI_OK) return ergo_result;
3547 
3548   // Final check of all ranges after ergonomics which may change values.
3549   if (!CommandLineFlagRangeList::check_ranges()) {
3550     return JNI_EINVAL;
3551   }
3552 
3553   // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3554   bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3555   if (!constraint_result) {
3556     return JNI_EINVAL;
3557   }
3558 
3559   CommandLineFlagWriteableList::mark_startup();
3560 
3561   if (PauseAtStartup) {
3562     os::pause();
3563   }
3564 
3565   HOTSPOT_VM_INIT_BEGIN();
3566 
3567   // Timing (must come after argument parsing)
3568   TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3569 
3570   // Initialize the os module after parsing the args
3571   jint os_init_2_result = os::init_2();
3572   if (os_init_2_result != JNI_OK) return os_init_2_result;
3573 
3574   jint adjust_after_os_result = Arguments::adjust_after_os();
3575   if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3576 
3577   // Initialize output stream logging
3578   ostream_init_log();
3579 
3580   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3581   // Must be before create_vm_init_agents()
3582   if (Arguments::init_libraries_at_startup()) {
3583     convert_vm_init_libraries_to_agents();
3584   }
3585 
3586   // Launch -agentlib/-agentpath and converted -Xrun agents
3587   if (Arguments::init_agents_at_startup()) {
3588     create_vm_init_agents();
3589   }
3590 
3591   // Initialize Threads state
3592   _thread_list = NULL;
3593   _number_of_threads = 0;
3594   _number_of_non_daemon_threads = 0;
3595 
3596   // Initialize global data structures and create system classes in heap
3597   vm_init_globals();
3598 
3599 #if INCLUDE_JVMCI
3600   if (JVMCICounterSize > 0) {
3601     JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3602     memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3603   } else {
3604     JavaThread::_jvmci_old_thread_counters = NULL;
3605   }
3606 #endif // INCLUDE_JVMCI
3607 
3608   // Attach the main thread to this os thread
3609   JavaThread* main_thread = new JavaThread();
3610   main_thread->set_thread_state(_thread_in_vm);
3611   main_thread->initialize_thread_current();
3612   // must do this before set_active_handles
3613   main_thread->record_stack_base_and_size();
3614   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3615 
3616   if (!main_thread->set_as_starting_thread()) {
3617     vm_shutdown_during_initialization(
3618                                       "Failed necessary internal allocation. Out of swap space");
3619     delete main_thread;
3620     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3621     return JNI_ENOMEM;
3622   }
3623 
3624   // Enable guard page *after* os::create_main_thread(), otherwise it would
3625   // crash Linux VM, see notes in os_linux.cpp.
3626   main_thread->create_stack_guard_pages();
3627 
3628   // Initialize Java-Level synchronization subsystem
3629   ObjectMonitor::Initialize();
3630 
3631   // Initialize global modules
3632   jint status = init_globals();
3633   if (status != JNI_OK) {
3634     delete main_thread;
3635     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3636     return status;
3637   }
3638 
3639   if (TRACE_INITIALIZE() != JNI_OK) {
3640     vm_exit_during_initialization("Failed to initialize tracing backend");
3641   }
3642 
3643   // Should be done after the heap is fully created
3644   main_thread->cache_global_variables();
3645 
3646   HandleMark hm;
3647 
3648   { MutexLocker mu(Threads_lock);
3649     Threads::add(main_thread);
3650   }
3651 
3652   // Any JVMTI raw monitors entered in onload will transition into
3653   // real raw monitor. VM is setup enough here for raw monitor enter.
3654   JvmtiExport::transition_pending_onload_raw_monitors();
3655 
3656   // Create the VMThread
3657   { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3658 
3659   VMThread::create();
3660     Thread* vmthread = VMThread::vm_thread();
3661 
3662     if (!os::create_thread(vmthread, os::vm_thread)) {
3663       vm_exit_during_initialization("Cannot create VM thread. "
3664                                     "Out of system resources.");
3665     }
3666 
3667     // Wait for the VM thread to become ready, and VMThread::run to initialize
3668     // Monitors can have spurious returns, must always check another state flag
3669     {
3670       MutexLocker ml(Notify_lock);
3671       os::start_thread(vmthread);
3672       while (vmthread->active_handles() == NULL) {
3673         Notify_lock->wait();
3674       }
3675     }
3676   }
3677 
3678   assert(Universe::is_fully_initialized(), "not initialized");
3679   if (VerifyDuringStartup) {
3680     // Make sure we're starting with a clean slate.
3681     VM_Verify verify_op;
3682     VMThread::execute(&verify_op);
3683   }
3684 
3685   Thread* THREAD = Thread::current();
3686 
3687   // At this point, the Universe is initialized, but we have not executed
3688   // any byte code.  Now is a good time (the only time) to dump out the
3689   // internal state of the JVM for sharing.
3690   if (DumpSharedSpaces) {
3691     MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3692     ShouldNotReachHere();
3693   }
3694 
3695   // Always call even when there are not JVMTI environments yet, since environments
3696   // may be attached late and JVMTI must track phases of VM execution
3697   JvmtiExport::enter_early_start_phase();
3698 
3699   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3700   JvmtiExport::post_early_vm_start();
3701 
3702   initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3703 
3704   // We need this for ClassDataSharing - the initial vm.info property is set
3705   // with the default value of CDS "sharing" which may be reset through
3706   // command line options.
3707   reset_vm_info_property(CHECK_JNI_ERR);
3708 
3709   quicken_jni_functions();
3710 
3711   // No more stub generation allowed after that point.
3712   StubCodeDesc::freeze();
3713 
3714   // Set flag that basic initialization has completed. Used by exceptions and various
3715   // debug stuff, that does not work until all basic classes have been initialized.
3716   set_init_completed();
3717 
3718   LogConfiguration::post_initialize();
3719   Metaspace::post_initialize();
3720 
3721   HOTSPOT_VM_INIT_END();
3722 
3723   // record VM initialization completion time
3724 #if INCLUDE_MANAGEMENT
3725   Management::record_vm_init_completed();
3726 #endif // INCLUDE_MANAGEMENT
3727 
3728   // Signal Dispatcher needs to be started before VMInit event is posted
3729   os::signal_init(CHECK_JNI_ERR);
3730 
3731   // Start Attach Listener if +StartAttachListener or it can't be started lazily
3732   if (!DisableAttachMechanism) {
3733     AttachListener::vm_start();
3734     if (StartAttachListener || AttachListener::init_at_startup()) {
3735       AttachListener::init();
3736     }
3737   }
3738 
3739   // Launch -Xrun agents
3740   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3741   // back-end can launch with -Xdebug -Xrunjdwp.
3742   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3743     create_vm_init_libraries();
3744   }
3745 
3746   if (CleanChunkPoolAsync) {
3747     Chunk::start_chunk_pool_cleaner_task();
3748   }
3749 
3750   // initialize compiler(s)
3751 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI
3752   CompileBroker::compilation_init(CHECK_JNI_ERR);
3753 #endif
3754 
3755   // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3756   // It is done after compilers are initialized, because otherwise compilations of
3757   // signature polymorphic MH intrinsics can be missed
3758   // (see SystemDictionary::find_method_handle_intrinsic).
3759   initialize_jsr292_core_classes(CHECK_JNI_ERR);
3760 
3761   // This will initialize the module system.  Only java.base classes can be
3762   // loaded until phase 2 completes
3763   call_initPhase2(CHECK_JNI_ERR);
3764 
3765   // Always call even when there are not JVMTI environments yet, since environments
3766   // may be attached late and JVMTI must track phases of VM execution
3767   JvmtiExport::enter_start_phase();
3768 
3769   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3770   JvmtiExport::post_vm_start();
3771 
3772   // Final system initialization including security manager and system class loader
3773   call_initPhase3(CHECK_JNI_ERR);
3774 
3775   // cache the system class loader
3776   SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR));
3777 
3778 #if INCLUDE_JVMCI
3779   if (EnableJVMCI) {
3780     // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled.
3781     // The JVMCI Java initialization code will read this flag and
3782     // do the printing if it's set.
3783     bool init = JVMCIPrintProperties;
3784 
3785     if (!init) {
3786       // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3787       // compilations via JVMCI will not actually block until JVMCI is initialized.
3788       init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3789     }
3790 
3791     if (init) {
3792       JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3793     }
3794   }
3795 #endif
3796 
3797   // Always call even when there are not JVMTI environments yet, since environments
3798   // may be attached late and JVMTI must track phases of VM execution
3799   JvmtiExport::enter_live_phase();
3800 
3801   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3802   JvmtiExport::post_vm_initialized();
3803 
3804   if (TRACE_START() != JNI_OK) {
3805     vm_exit_during_initialization("Failed to start tracing backend.");
3806   }
3807 
3808 #if INCLUDE_MANAGEMENT
3809   Management::initialize(THREAD);
3810 
3811   if (HAS_PENDING_EXCEPTION) {
3812     // management agent fails to start possibly due to
3813     // configuration problem and is responsible for printing
3814     // stack trace if appropriate. Simply exit VM.
3815     vm_exit(1);
3816   }
3817 #endif // INCLUDE_MANAGEMENT
3818 
3819   if (Arguments::has_profile())       FlatProfiler::engage(main_thread, true);
3820   if (MemProfiling)                   MemProfiler::engage();
3821   StatSampler::engage();
3822   if (CheckJNICalls)                  JniPeriodicChecker::engage();
3823 
3824   BiasedLocking::init();
3825 
3826 #if INCLUDE_RTM_OPT
3827   RTMLockingCounters::init();
3828 #endif
3829 
3830   if (JDK_Version::current().post_vm_init_hook_enabled()) {
3831     call_postVMInitHook(THREAD);
3832     // The Java side of PostVMInitHook.run must deal with all
3833     // exceptions and provide means of diagnosis.
3834     if (HAS_PENDING_EXCEPTION) {
3835       CLEAR_PENDING_EXCEPTION;
3836     }
3837   }
3838 
3839   {
3840     MutexLocker ml(PeriodicTask_lock);
3841     // Make sure the WatcherThread can be started by WatcherThread::start()
3842     // or by dynamic enrollment.
3843     WatcherThread::make_startable();
3844     // Start up the WatcherThread if there are any periodic tasks
3845     // NOTE:  All PeriodicTasks should be registered by now. If they
3846     //   aren't, late joiners might appear to start slowly (we might
3847     //   take a while to process their first tick).
3848     if (PeriodicTask::num_tasks() > 0) {
3849       WatcherThread::start();
3850     }
3851   }
3852 
3853   create_vm_timer.end();
3854 #ifdef ASSERT
3855   _vm_complete = true;
3856 #endif
3857   return JNI_OK;
3858 }
3859 
3860 // type for the Agent_OnLoad and JVM_OnLoad entry points
3861 extern "C" {
3862   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3863 }
3864 // Find a command line agent library and return its entry point for
3865 //         -agentlib:  -agentpath:   -Xrun
3866 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3867 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3868                                     const char *on_load_symbols[],
3869                                     size_t num_symbol_entries) {
3870   OnLoadEntry_t on_load_entry = NULL;
3871   void *library = NULL;
3872 
3873   if (!agent->valid()) {
3874     char buffer[JVM_MAXPATHLEN];
3875     char ebuf[1024] = "";
3876     const char *name = agent->name();
3877     const char *msg = "Could not find agent library ";
3878 
3879     // First check to see if agent is statically linked into executable
3880     if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3881       library = agent->os_lib();
3882     } else if (agent->is_absolute_path()) {
3883       library = os::dll_load(name, ebuf, sizeof ebuf);
3884       if (library == NULL) {
3885         const char *sub_msg = " in absolute path, with error: ";
3886         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3887         char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3888         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3889         // If we can't find the agent, exit.
3890         vm_exit_during_initialization(buf, NULL);
3891         FREE_C_HEAP_ARRAY(char, buf);
3892       }
3893     } else {
3894       // Try to load the agent from the standard dll directory
3895       if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3896                              name)) {
3897         library = os::dll_load(buffer, ebuf, sizeof ebuf);
3898       }
3899       if (library == NULL) { // Try the local directory
3900         char ns[1] = {0};
3901         if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3902           library = os::dll_load(buffer, ebuf, sizeof ebuf);
3903         }
3904         if (library == NULL) {
3905           const char *sub_msg = " on the library path, with error: ";
3906           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3907           char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3908           jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3909           // If we can't find the agent, exit.
3910           vm_exit_during_initialization(buf, NULL);
3911           FREE_C_HEAP_ARRAY(char, buf);
3912         }
3913       }
3914     }
3915     agent->set_os_lib(library);
3916     agent->set_valid();
3917   }
3918 
3919   // Find the OnLoad function.
3920   on_load_entry =
3921     CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3922                                                           false,
3923                                                           on_load_symbols,
3924                                                           num_symbol_entries));
3925   return on_load_entry;
3926 }
3927 
3928 // Find the JVM_OnLoad entry point
3929 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3930   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3931   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3932 }
3933 
3934 // Find the Agent_OnLoad entry point
3935 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3936   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3937   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3938 }
3939 
3940 // For backwards compatibility with -Xrun
3941 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3942 // treated like -agentpath:
3943 // Must be called before agent libraries are created
3944 void Threads::convert_vm_init_libraries_to_agents() {
3945   AgentLibrary* agent;
3946   AgentLibrary* next;
3947 
3948   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3949     next = agent->next();  // cache the next agent now as this agent may get moved off this list
3950     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3951 
3952     // If there is an JVM_OnLoad function it will get called later,
3953     // otherwise see if there is an Agent_OnLoad
3954     if (on_load_entry == NULL) {
3955       on_load_entry = lookup_agent_on_load(agent);
3956       if (on_load_entry != NULL) {
3957         // switch it to the agent list -- so that Agent_OnLoad will be called,
3958         // JVM_OnLoad won't be attempted and Agent_OnUnload will
3959         Arguments::convert_library_to_agent(agent);
3960       } else {
3961         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3962       }
3963     }
3964   }
3965 }
3966 
3967 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
3968 // Invokes Agent_OnLoad
3969 // Called very early -- before JavaThreads exist
3970 void Threads::create_vm_init_agents() {
3971   extern struct JavaVM_ main_vm;
3972   AgentLibrary* agent;
3973 
3974   JvmtiExport::enter_onload_phase();
3975 
3976   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3977     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
3978 
3979     if (on_load_entry != NULL) {
3980       // Invoke the Agent_OnLoad function
3981       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3982       if (err != JNI_OK) {
3983         vm_exit_during_initialization("agent library failed to init", agent->name());
3984       }
3985     } else {
3986       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3987     }
3988   }
3989   JvmtiExport::enter_primordial_phase();
3990 }
3991 
3992 extern "C" {
3993   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3994 }
3995 
3996 void Threads::shutdown_vm_agents() {
3997   // Send any Agent_OnUnload notifications
3998   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3999   size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4000   extern struct JavaVM_ main_vm;
4001   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4002 
4003     // Find the Agent_OnUnload function.
4004     Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4005                                                    os::find_agent_function(agent,
4006                                                    false,
4007                                                    on_unload_symbols,
4008                                                    num_symbol_entries));
4009 
4010     // Invoke the Agent_OnUnload function
4011     if (unload_entry != NULL) {
4012       JavaThread* thread = JavaThread::current();
4013       ThreadToNativeFromVM ttn(thread);
4014       HandleMark hm(thread);
4015       (*unload_entry)(&main_vm);
4016     }
4017   }
4018 }
4019 
4020 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4021 // Invokes JVM_OnLoad
4022 void Threads::create_vm_init_libraries() {
4023   extern struct JavaVM_ main_vm;
4024   AgentLibrary* agent;
4025 
4026   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4027     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4028 
4029     if (on_load_entry != NULL) {
4030       // Invoke the JVM_OnLoad function
4031       JavaThread* thread = JavaThread::current();
4032       ThreadToNativeFromVM ttn(thread);
4033       HandleMark hm(thread);
4034       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4035       if (err != JNI_OK) {
4036         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4037       }
4038     } else {
4039       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4040     }
4041   }
4042 }
4043 
4044 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
4045   assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
4046 
4047   JavaThread* java_thread = NULL;
4048   // Sequential search for now.  Need to do better optimization later.
4049   for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
4050     oop tobj = thread->threadObj();
4051     if (!thread->is_exiting() &&
4052         tobj != NULL &&
4053         java_tid == java_lang_Thread::thread_id(tobj)) {
4054       java_thread = thread;
4055       break;
4056     }
4057   }
4058   return java_thread;
4059 }
4060 
4061 
4062 // Last thread running calls java.lang.Shutdown.shutdown()
4063 void JavaThread::invoke_shutdown_hooks() {
4064   HandleMark hm(this);
4065 
4066   // We could get here with a pending exception, if so clear it now.
4067   if (this->has_pending_exception()) {
4068     this->clear_pending_exception();
4069   }
4070 
4071   EXCEPTION_MARK;
4072   Klass* shutdown_klass =
4073     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4074                                       THREAD);
4075   if (shutdown_klass != NULL) {
4076     // SystemDictionary::resolve_or_null will return null if there was
4077     // an exception.  If we cannot load the Shutdown class, just don't
4078     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
4079     // and finalizers (if runFinalizersOnExit is set) won't be run.
4080     // Note that if a shutdown hook was registered or runFinalizersOnExit
4081     // was called, the Shutdown class would have already been loaded
4082     // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4083     JavaValue result(T_VOID);
4084     JavaCalls::call_static(&result,
4085                            shutdown_klass,
4086                            vmSymbols::shutdown_method_name(),
4087                            vmSymbols::void_method_signature(),
4088                            THREAD);
4089   }
4090   CLEAR_PENDING_EXCEPTION;
4091 }
4092 
4093 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4094 // the program falls off the end of main(). Another VM exit path is through
4095 // vm_exit() when the program calls System.exit() to return a value or when
4096 // there is a serious error in VM. The two shutdown paths are not exactly
4097 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4098 // and VM_Exit op at VM level.
4099 //
4100 // Shutdown sequence:
4101 //   + Shutdown native memory tracking if it is on
4102 //   + Wait until we are the last non-daemon thread to execute
4103 //     <-- every thing is still working at this moment -->
4104 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4105 //        shutdown hooks, run finalizers if finalization-on-exit
4106 //   + Call before_exit(), prepare for VM exit
4107 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4108 //        currently the only user of this mechanism is File.deleteOnExit())
4109 //      > stop flat profiler, StatSampler, watcher thread, CMS threads,
4110 //        post thread end and vm death events to JVMTI,
4111 //        stop signal thread
4112 //   + Call JavaThread::exit(), it will:
4113 //      > release JNI handle blocks, remove stack guard pages
4114 //      > remove this thread from Threads list
4115 //     <-- no more Java code from this thread after this point -->
4116 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4117 //     the compiler threads at safepoint
4118 //     <-- do not use anything that could get blocked by Safepoint -->
4119 //   + Disable tracing at JNI/JVM barriers
4120 //   + Set _vm_exited flag for threads that are still running native code
4121 //   + Delete this thread
4122 //   + Call exit_globals()
4123 //      > deletes tty
4124 //      > deletes PerfMemory resources
4125 //   + Return to caller
4126 
4127 bool Threads::destroy_vm() {
4128   JavaThread* thread = JavaThread::current();
4129 
4130 #ifdef ASSERT
4131   _vm_complete = false;
4132 #endif
4133   // Wait until we are the last non-daemon thread to execute
4134   { MutexLocker nu(Threads_lock);
4135     while (Threads::number_of_non_daemon_threads() > 1)
4136       // This wait should make safepoint checks, wait without a timeout,
4137       // and wait as a suspend-equivalent condition.
4138       //
4139       // Note: If the FlatProfiler is running and this thread is waiting
4140       // for another non-daemon thread to finish, then the FlatProfiler
4141       // is waiting for the external suspend request on this thread to
4142       // complete. wait_for_ext_suspend_completion() will eventually
4143       // timeout, but that takes time. Making this wait a suspend-
4144       // equivalent condition solves that timeout problem.
4145       //
4146       Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4147                          Mutex::_as_suspend_equivalent_flag);
4148   }
4149 
4150   // Hang forever on exit if we are reporting an error.
4151   if (ShowMessageBoxOnError && is_error_reported()) {
4152     os::infinite_sleep();
4153   }
4154   os::wait_for_keypress_at_exit();
4155 
4156   // run Java level shutdown hooks
4157   thread->invoke_shutdown_hooks();
4158 
4159   before_exit(thread);
4160 
4161   thread->exit(true);
4162 
4163   // Stop VM thread.
4164   {
4165     // 4945125 The vm thread comes to a safepoint during exit.
4166     // GC vm_operations can get caught at the safepoint, and the
4167     // heap is unparseable if they are caught. Grab the Heap_lock
4168     // to prevent this. The GC vm_operations will not be able to
4169     // queue until after the vm thread is dead. After this point,
4170     // we'll never emerge out of the safepoint before the VM exits.
4171 
4172     MutexLocker ml(Heap_lock);
4173 
4174     VMThread::wait_for_vm_thread_exit();
4175     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4176     VMThread::destroy();
4177   }
4178 
4179   // clean up ideal graph printers
4180 #if defined(COMPILER2) && !defined(PRODUCT)
4181   IdealGraphPrinter::clean_up();
4182 #endif
4183 
4184   // Now, all Java threads are gone except daemon threads. Daemon threads
4185   // running Java code or in VM are stopped by the Safepoint. However,
4186   // daemon threads executing native code are still running.  But they
4187   // will be stopped at native=>Java/VM barriers. Note that we can't
4188   // simply kill or suspend them, as it is inherently deadlock-prone.
4189 
4190   VM_Exit::set_vm_exited();
4191 
4192   notify_vm_shutdown();
4193 
4194   delete thread;
4195 
4196 #if INCLUDE_JVMCI
4197   if (JVMCICounterSize > 0) {
4198     FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4199   }
4200 #endif
4201 
4202   // exit_globals() will delete tty
4203   exit_globals();
4204 
4205   LogConfiguration::finalize();
4206 
4207   return true;
4208 }
4209 
4210 
4211 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4212   if (version == JNI_VERSION_1_1) return JNI_TRUE;
4213   return is_supported_jni_version(version);
4214 }
4215 
4216 
4217 jboolean Threads::is_supported_jni_version(jint version) {
4218   if (version == JNI_VERSION_1_2) return JNI_TRUE;
4219   if (version == JNI_VERSION_1_4) return JNI_TRUE;
4220   if (version == JNI_VERSION_1_6) return JNI_TRUE;
4221   if (version == JNI_VERSION_1_8) return JNI_TRUE;
4222   if (version == JNI_VERSION_9) return JNI_TRUE;
4223   return JNI_FALSE;
4224 }
4225 
4226 
4227 void Threads::add(JavaThread* p, bool force_daemon) {
4228   // The threads lock must be owned at this point
4229   assert_locked_or_safepoint(Threads_lock);
4230 
4231   // See the comment for this method in thread.hpp for its purpose and
4232   // why it is called here.
4233   p->initialize_queues();
4234   p->set_next(_thread_list);
4235   _thread_list = p;
4236   _number_of_threads++;
4237   oop threadObj = p->threadObj();
4238   bool daemon = true;
4239   // Bootstrapping problem: threadObj can be null for initial
4240   // JavaThread (or for threads attached via JNI)
4241   if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4242     _number_of_non_daemon_threads++;
4243     daemon = false;
4244   }
4245 
4246   ThreadService::add_thread(p, daemon);
4247 
4248   // Possible GC point.
4249   Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4250 }
4251 
4252 void Threads::remove(JavaThread* p) {
4253 
4254   // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
4255   ObjectSynchronizer::omFlush(p);
4256 
4257   // Extra scope needed for Thread_lock, so we can check
4258   // that we do not remove thread without safepoint code notice
4259   { MutexLocker ml(Threads_lock);
4260 
4261     assert(includes(p), "p must be present");
4262 
4263     JavaThread* current = _thread_list;
4264     JavaThread* prev    = NULL;
4265 
4266     while (current != p) {
4267       prev    = current;
4268       current = current->next();
4269     }
4270 
4271     if (prev) {
4272       prev->set_next(current->next());
4273     } else {
4274       _thread_list = p->next();
4275     }
4276     _number_of_threads--;
4277     oop threadObj = p->threadObj();
4278     bool daemon = true;
4279     if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4280       _number_of_non_daemon_threads--;
4281       daemon = false;
4282 
4283       // Only one thread left, do a notify on the Threads_lock so a thread waiting
4284       // on destroy_vm will wake up.
4285       if (number_of_non_daemon_threads() == 1) {
4286         Threads_lock->notify_all();
4287       }
4288     }
4289     ThreadService::remove_thread(p, daemon);
4290 
4291     // Make sure that safepoint code disregard this thread. This is needed since
4292     // the thread might mess around with locks after this point. This can cause it
4293     // to do callbacks into the safepoint code. However, the safepoint code is not aware
4294     // of this thread since it is removed from the queue.
4295     p->set_terminated_value();
4296   } // unlock Threads_lock
4297 
4298   // Since Events::log uses a lock, we grab it outside the Threads_lock
4299   Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4300 }
4301 
4302 // Threads_lock must be held when this is called (or must be called during a safepoint)
4303 bool Threads::includes(JavaThread* p) {
4304   assert(Threads_lock->is_locked(), "sanity check");
4305   ALL_JAVA_THREADS(q) {
4306     if (q == p) {
4307       return true;
4308     }
4309   }
4310   return false;
4311 }
4312 
4313 // Operations on the Threads list for GC.  These are not explicitly locked,
4314 // but the garbage collector must provide a safe context for them to run.
4315 // In particular, these things should never be called when the Threads_lock
4316 // is held by some other thread. (Note: the Safepoint abstraction also
4317 // uses the Threads_lock to guarantee this property. It also makes sure that
4318 // all threads gets blocked when exiting or starting).
4319 
4320 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4321   ALL_JAVA_THREADS(p) {
4322     p->oops_do(f, cf);
4323   }
4324   VMThread::vm_thread()->oops_do(f, cf);
4325 }
4326 
4327 void Threads::change_thread_claim_parity() {
4328   // Set the new claim parity.
4329   assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4330          "Not in range.");
4331   _thread_claim_parity++;
4332   if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4333   assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4334          "Not in range.");
4335 }
4336 
4337 #ifdef ASSERT
4338 void Threads::assert_all_threads_claimed() {
4339   ALL_JAVA_THREADS(p) {
4340     const int thread_parity = p->oops_do_parity();
4341     assert((thread_parity == _thread_claim_parity),
4342            "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4343   }
4344 }
4345 #endif // ASSERT
4346 
4347 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4348   int cp = Threads::thread_claim_parity();
4349   ALL_JAVA_THREADS(p) {
4350     if (p->claim_oops_do(is_par, cp)) {
4351       p->oops_do(f, cf);
4352     }
4353   }
4354   VMThread* vmt = VMThread::vm_thread();
4355   if (vmt->claim_oops_do(is_par, cp)) {
4356     vmt->oops_do(f, cf);
4357   }
4358 }
4359 
4360 #if INCLUDE_ALL_GCS
4361 // Used by ParallelScavenge
4362 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4363   ALL_JAVA_THREADS(p) {
4364     q->enqueue(new ThreadRootsTask(p));
4365   }
4366   q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4367 }
4368 
4369 // Used by Parallel Old
4370 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4371   ALL_JAVA_THREADS(p) {
4372     q->enqueue(new ThreadRootsMarkingTask(p));
4373   }
4374   q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4375 }
4376 #endif // INCLUDE_ALL_GCS
4377 
4378 void Threads::nmethods_do(CodeBlobClosure* cf) {
4379   ALL_JAVA_THREADS(p) {
4380     // This is used by the code cache sweeper to mark nmethods that are active
4381     // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4382     // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4383     if(!p->is_Code_cache_sweeper_thread()) {
4384       p->nmethods_do(cf);
4385     }
4386   }
4387 }
4388 
4389 void Threads::metadata_do(void f(Metadata*)) {
4390   ALL_JAVA_THREADS(p) {
4391     p->metadata_do(f);
4392   }
4393 }
4394 
4395 class ThreadHandlesClosure : public ThreadClosure {
4396   void (*_f)(Metadata*);
4397  public:
4398   ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4399   virtual void do_thread(Thread* thread) {
4400     thread->metadata_handles_do(_f);
4401   }
4402 };
4403 
4404 void Threads::metadata_handles_do(void f(Metadata*)) {
4405   // Only walk the Handles in Thread.
4406   ThreadHandlesClosure handles_closure(f);
4407   threads_do(&handles_closure);
4408 }
4409 
4410 void Threads::deoptimized_wrt_marked_nmethods() {
4411   ALL_JAVA_THREADS(p) {
4412     p->deoptimized_wrt_marked_nmethods();
4413   }
4414 }
4415 
4416 
4417 // Get count Java threads that are waiting to enter the specified monitor.
4418 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4419                                                          address monitor,
4420                                                          bool doLock) {
4421   assert(doLock || SafepointSynchronize::is_at_safepoint(),
4422          "must grab Threads_lock or be at safepoint");
4423   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4424 
4425   int i = 0;
4426   {
4427     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4428     ALL_JAVA_THREADS(p) {
4429       if (!p->can_call_java()) continue;
4430 
4431       address pending = (address)p->current_pending_monitor();
4432       if (pending == monitor) {             // found a match
4433         if (i < count) result->append(p);   // save the first count matches
4434         i++;
4435       }
4436     }
4437   }
4438   return result;
4439 }
4440 
4441 
4442 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4443                                                       bool doLock) {
4444   assert(doLock ||
4445          Threads_lock->owned_by_self() ||
4446          SafepointSynchronize::is_at_safepoint(),
4447          "must grab Threads_lock or be at safepoint");
4448 
4449   // NULL owner means not locked so we can skip the search
4450   if (owner == NULL) return NULL;
4451 
4452   {
4453     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4454     ALL_JAVA_THREADS(p) {
4455       // first, see if owner is the address of a Java thread
4456       if (owner == (address)p) return p;
4457     }
4458   }
4459   // Cannot assert on lack of success here since this function may be
4460   // used by code that is trying to report useful problem information
4461   // like deadlock detection.
4462   if (UseHeavyMonitors) return NULL;
4463 
4464   // If we didn't find a matching Java thread and we didn't force use of
4465   // heavyweight monitors, then the owner is the stack address of the
4466   // Lock Word in the owning Java thread's stack.
4467   //
4468   JavaThread* the_owner = NULL;
4469   {
4470     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4471     ALL_JAVA_THREADS(q) {
4472       if (q->is_lock_owned(owner)) {
4473         the_owner = q;
4474         break;
4475       }
4476     }
4477   }
4478   // cannot assert on lack of success here; see above comment
4479   return the_owner;
4480 }
4481 
4482 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4483 void Threads::print_on(outputStream* st, bool print_stacks,
4484                        bool internal_format, bool print_concurrent_locks) {
4485   char buf[32];
4486   st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4487 
4488   st->print_cr("Full thread dump %s (%s %s):",
4489                Abstract_VM_Version::vm_name(),
4490                Abstract_VM_Version::vm_release(),
4491                Abstract_VM_Version::vm_info_string());
4492   st->cr();
4493 
4494 #if INCLUDE_SERVICES
4495   // Dump concurrent locks
4496   ConcurrentLocksDump concurrent_locks;
4497   if (print_concurrent_locks) {
4498     concurrent_locks.dump_at_safepoint();
4499   }
4500 #endif // INCLUDE_SERVICES
4501 
4502   ALL_JAVA_THREADS(p) {
4503     ResourceMark rm;
4504     p->print_on(st);
4505     if (print_stacks) {
4506       if (internal_format) {
4507         p->trace_stack();
4508       } else {
4509         p->print_stack_on(st);
4510       }
4511     }
4512     st->cr();
4513 #if INCLUDE_SERVICES
4514     if (print_concurrent_locks) {
4515       concurrent_locks.print_locks_on(p, st);
4516     }
4517 #endif // INCLUDE_SERVICES
4518   }
4519 
4520   VMThread::vm_thread()->print_on(st);
4521   st->cr();
4522   Universe::heap()->print_gc_threads_on(st);
4523   WatcherThread* wt = WatcherThread::watcher_thread();
4524   if (wt != NULL) {
4525     wt->print_on(st);
4526     st->cr();
4527   }
4528   st->flush();
4529 }
4530 
4531 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4532                              int buflen, bool* found_current) {
4533   if (this_thread != NULL) {
4534     bool is_current = (current == this_thread);
4535     *found_current = *found_current || is_current;
4536     st->print("%s", is_current ? "=>" : "  ");
4537 
4538     st->print(PTR_FORMAT, p2i(this_thread));
4539     st->print(" ");
4540     this_thread->print_on_error(st, buf, buflen);
4541     st->cr();
4542   }
4543 }
4544 
4545 class PrintOnErrorClosure : public ThreadClosure {
4546   outputStream* _st;
4547   Thread* _current;
4548   char* _buf;
4549   int _buflen;
4550   bool* _found_current;
4551  public:
4552   PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4553                       int buflen, bool* found_current) :
4554    _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4555 
4556   virtual void do_thread(Thread* thread) {
4557     Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4558   }
4559 };
4560 
4561 // Threads::print_on_error() is called by fatal error handler. It's possible
4562 // that VM is not at safepoint and/or current thread is inside signal handler.
4563 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4564 // memory (even in resource area), it might deadlock the error handler.
4565 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4566                              int buflen) {
4567   bool found_current = false;
4568   st->print_cr("Java Threads: ( => current thread )");
4569   ALL_JAVA_THREADS(thread) {
4570     print_on_error(thread, st, current, buf, buflen, &found_current);
4571   }
4572   st->cr();
4573 
4574   st->print_cr("Other Threads:");
4575   print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4576   print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4577 
4578   PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4579   Universe::heap()->gc_threads_do(&print_closure);
4580 
4581   if (!found_current) {
4582     st->cr();
4583     st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4584     current->print_on_error(st, buf, buflen);
4585     st->cr();
4586   }
4587   st->cr();
4588   st->print_cr("Threads with active compile tasks:");
4589   print_threads_compiling(st, buf, buflen);
4590 }
4591 
4592 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4593   ALL_JAVA_THREADS(thread) {
4594     if (thread->is_Compiler_thread()) {
4595       CompilerThread* ct = (CompilerThread*) thread;
4596       if (ct->task() != NULL) {
4597         thread->print_name_on_error(st, buf, buflen);
4598         ct->task()->print(st, NULL, true, true);
4599       }
4600     }
4601   }
4602 }
4603 
4604 
4605 // Internal SpinLock and Mutex
4606 // Based on ParkEvent
4607 
4608 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4609 //
4610 // We employ SpinLocks _only for low-contention, fixed-length
4611 // short-duration critical sections where we're concerned
4612 // about native mutex_t or HotSpot Mutex:: latency.
4613 // The mux construct provides a spin-then-block mutual exclusion
4614 // mechanism.
4615 //
4616 // Testing has shown that contention on the ListLock guarding gFreeList
4617 // is common.  If we implement ListLock as a simple SpinLock it's common
4618 // for the JVM to devolve to yielding with little progress.  This is true
4619 // despite the fact that the critical sections protected by ListLock are
4620 // extremely short.
4621 //
4622 // TODO-FIXME: ListLock should be of type SpinLock.
4623 // We should make this a 1st-class type, integrated into the lock
4624 // hierarchy as leaf-locks.  Critically, the SpinLock structure
4625 // should have sufficient padding to avoid false-sharing and excessive
4626 // cache-coherency traffic.
4627 
4628 
4629 typedef volatile int SpinLockT;
4630 
4631 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4632   if (Atomic::cmpxchg (1, adr, 0) == 0) {
4633     return;   // normal fast-path return
4634   }
4635 
4636   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4637   TEVENT(SpinAcquire - ctx);
4638   int ctr = 0;
4639   int Yields = 0;
4640   for (;;) {
4641     while (*adr != 0) {
4642       ++ctr;
4643       if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4644         if (Yields > 5) {
4645           os::naked_short_sleep(1);
4646         } else {
4647           os::naked_yield();
4648           ++Yields;
4649         }
4650       } else {
4651         SpinPause();
4652       }
4653     }
4654     if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4655   }
4656 }
4657 
4658 void Thread::SpinRelease(volatile int * adr) {
4659   assert(*adr != 0, "invariant");
4660   OrderAccess::fence();      // guarantee at least release consistency.
4661   // Roach-motel semantics.
4662   // It's safe if subsequent LDs and STs float "up" into the critical section,
4663   // but prior LDs and STs within the critical section can't be allowed
4664   // to reorder or float past the ST that releases the lock.
4665   // Loads and stores in the critical section - which appear in program
4666   // order before the store that releases the lock - must also appear
4667   // before the store that releases the lock in memory visibility order.
4668   // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4669   // the ST of 0 into the lock-word which releases the lock, so fence
4670   // more than covers this on all platforms.
4671   *adr = 0;
4672 }
4673 
4674 // muxAcquire and muxRelease:
4675 //
4676 // *  muxAcquire and muxRelease support a single-word lock-word construct.
4677 //    The LSB of the word is set IFF the lock is held.
4678 //    The remainder of the word points to the head of a singly-linked list
4679 //    of threads blocked on the lock.
4680 //
4681 // *  The current implementation of muxAcquire-muxRelease uses its own
4682 //    dedicated Thread._MuxEvent instance.  If we're interested in
4683 //    minimizing the peak number of extant ParkEvent instances then
4684 //    we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4685 //    as certain invariants were satisfied.  Specifically, care would need
4686 //    to be taken with regards to consuming unpark() "permits".
4687 //    A safe rule of thumb is that a thread would never call muxAcquire()
4688 //    if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4689 //    park().  Otherwise the _ParkEvent park() operation in muxAcquire() could
4690 //    consume an unpark() permit intended for monitorenter, for instance.
4691 //    One way around this would be to widen the restricted-range semaphore
4692 //    implemented in park().  Another alternative would be to provide
4693 //    multiple instances of the PlatformEvent() for each thread.  One
4694 //    instance would be dedicated to muxAcquire-muxRelease, for instance.
4695 //
4696 // *  Usage:
4697 //    -- Only as leaf locks
4698 //    -- for short-term locking only as muxAcquire does not perform
4699 //       thread state transitions.
4700 //
4701 // Alternatives:
4702 // *  We could implement muxAcquire and muxRelease with MCS or CLH locks
4703 //    but with parking or spin-then-park instead of pure spinning.
4704 // *  Use Taura-Oyama-Yonenzawa locks.
4705 // *  It's possible to construct a 1-0 lock if we encode the lockword as
4706 //    (List,LockByte).  Acquire will CAS the full lockword while Release
4707 //    will STB 0 into the LockByte.  The 1-0 scheme admits stranding, so
4708 //    acquiring threads use timers (ParkTimed) to detect and recover from
4709 //    the stranding window.  Thread/Node structures must be aligned on 256-byte
4710 //    boundaries by using placement-new.
4711 // *  Augment MCS with advisory back-link fields maintained with CAS().
4712 //    Pictorially:  LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4713 //    The validity of the backlinks must be ratified before we trust the value.
4714 //    If the backlinks are invalid the exiting thread must back-track through the
4715 //    the forward links, which are always trustworthy.
4716 // *  Add a successor indication.  The LockWord is currently encoded as
4717 //    (List, LOCKBIT:1).  We could also add a SUCCBIT or an explicit _succ variable
4718 //    to provide the usual futile-wakeup optimization.
4719 //    See RTStt for details.
4720 // *  Consider schedctl.sc_nopreempt to cover the critical section.
4721 //
4722 
4723 
4724 typedef volatile intptr_t MutexT;      // Mux Lock-word
4725 enum MuxBits { LOCKBIT = 1 };
4726 
4727 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4728   intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4729   if (w == 0) return;
4730   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4731     return;
4732   }
4733 
4734   TEVENT(muxAcquire - Contention);
4735   ParkEvent * const Self = Thread::current()->_MuxEvent;
4736   assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4737   for (;;) {
4738     int its = (os::is_MP() ? 100 : 0) + 1;
4739 
4740     // Optional spin phase: spin-then-park strategy
4741     while (--its >= 0) {
4742       w = *Lock;
4743       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4744         return;
4745       }
4746     }
4747 
4748     Self->reset();
4749     Self->OnList = intptr_t(Lock);
4750     // The following fence() isn't _strictly necessary as the subsequent
4751     // CAS() both serializes execution and ratifies the fetched *Lock value.
4752     OrderAccess::fence();
4753     for (;;) {
4754       w = *Lock;
4755       if ((w & LOCKBIT) == 0) {
4756         if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4757           Self->OnList = 0;   // hygiene - allows stronger asserts
4758           return;
4759         }
4760         continue;      // Interference -- *Lock changed -- Just retry
4761       }
4762       assert(w & LOCKBIT, "invariant");
4763       Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4764       if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4765     }
4766 
4767     while (Self->OnList != 0) {
4768       Self->park();
4769     }
4770   }
4771 }
4772 
4773 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4774   intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4775   if (w == 0) return;
4776   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4777     return;
4778   }
4779 
4780   TEVENT(muxAcquire - Contention);
4781   ParkEvent * ReleaseAfter = NULL;
4782   if (ev == NULL) {
4783     ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4784   }
4785   assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4786   for (;;) {
4787     guarantee(ev->OnList == 0, "invariant");
4788     int its = (os::is_MP() ? 100 : 0) + 1;
4789 
4790     // Optional spin phase: spin-then-park strategy
4791     while (--its >= 0) {
4792       w = *Lock;
4793       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4794         if (ReleaseAfter != NULL) {
4795           ParkEvent::Release(ReleaseAfter);
4796         }
4797         return;
4798       }
4799     }
4800 
4801     ev->reset();
4802     ev->OnList = intptr_t(Lock);
4803     // The following fence() isn't _strictly necessary as the subsequent
4804     // CAS() both serializes execution and ratifies the fetched *Lock value.
4805     OrderAccess::fence();
4806     for (;;) {
4807       w = *Lock;
4808       if ((w & LOCKBIT) == 0) {
4809         if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4810           ev->OnList = 0;
4811           // We call ::Release while holding the outer lock, thus
4812           // artificially lengthening the critical section.
4813           // Consider deferring the ::Release() until the subsequent unlock(),
4814           // after we've dropped the outer lock.
4815           if (ReleaseAfter != NULL) {
4816             ParkEvent::Release(ReleaseAfter);
4817           }
4818           return;
4819         }
4820         continue;      // Interference -- *Lock changed -- Just retry
4821       }
4822       assert(w & LOCKBIT, "invariant");
4823       ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4824       if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4825     }
4826 
4827     while (ev->OnList != 0) {
4828       ev->park();
4829     }
4830   }
4831 }
4832 
4833 // Release() must extract a successor from the list and then wake that thread.
4834 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4835 // similar to that used by ParkEvent::Allocate() and ::Release().  DMR-based
4836 // Release() would :
4837 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4838 // (B) Extract a successor from the private list "in-hand"
4839 // (C) attempt to CAS() the residual back into *Lock over null.
4840 //     If there were any newly arrived threads and the CAS() would fail.
4841 //     In that case Release() would detach the RATs, re-merge the list in-hand
4842 //     with the RATs and repeat as needed.  Alternately, Release() might
4843 //     detach and extract a successor, but then pass the residual list to the wakee.
4844 //     The wakee would be responsible for reattaching and remerging before it
4845 //     competed for the lock.
4846 //
4847 // Both "pop" and DMR are immune from ABA corruption -- there can be
4848 // multiple concurrent pushers, but only one popper or detacher.
4849 // This implementation pops from the head of the list.  This is unfair,
4850 // but tends to provide excellent throughput as hot threads remain hot.
4851 // (We wake recently run threads first).
4852 //
4853 // All paths through muxRelease() will execute a CAS.
4854 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4855 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4856 // executed within the critical section are complete and globally visible before the
4857 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4858 void Thread::muxRelease(volatile intptr_t * Lock)  {
4859   for (;;) {
4860     const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4861     assert(w & LOCKBIT, "invariant");
4862     if (w == LOCKBIT) return;
4863     ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4864     assert(List != NULL, "invariant");
4865     assert(List->OnList == intptr_t(Lock), "invariant");
4866     ParkEvent * const nxt = List->ListNext;
4867     guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4868 
4869     // The following CAS() releases the lock and pops the head element.
4870     // The CAS() also ratifies the previously fetched lock-word value.
4871     if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4872       continue;
4873     }
4874     List->OnList = 0;
4875     OrderAccess::fence();
4876     List->unpark();
4877     return;
4878   }
4879 }
4880 
4881 
4882 void Threads::verify() {
4883   ALL_JAVA_THREADS(p) {
4884     p->verify();
4885   }
4886   VMThread* thread = VMThread::vm_thread();
4887   if (thread != NULL) thread->verify();
4888 }