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/align.hpp"
 100 #include "utilities/defaultStream.hpp"
 101 #include "utilities/dtrace.hpp"
 102 #include "utilities/events.hpp"
 103 #include "utilities/macros.hpp"
 104 #include "utilities/preserveException.hpp"
 105 #include "utilities/vmError.hpp"
 106 #if INCLUDE_ALL_GCS
 107 #include "gc/cms/concurrentMarkSweepThread.hpp"
 108 #include "gc/g1/concurrentMarkThread.inline.hpp"
 109 #include "gc/parallel/pcTasks.hpp"
 110 #endif // INCLUDE_ALL_GCS
 111 #if INCLUDE_JVMCI
 112 #include "jvmci/jvmciCompiler.hpp"
 113 #include "jvmci/jvmciRuntime.hpp"
 114 #endif
 115 #ifdef COMPILER1
 116 #include "c1/c1_Compiler.hpp"
 117 #endif
 118 #ifdef COMPILER2
 119 #include "opto/c2compiler.hpp"
 120 #include "opto/idealGraphPrinter.hpp"
 121 #endif
 122 #if INCLUDE_RTM_OPT
 123 #include "runtime/rtmLocking.hpp"
 124 #endif
 125 
 126 // Initialization after module runtime initialization
 127 void universe_post_module_init();  // must happen after call_initPhase2
 128 
 129 #ifdef DTRACE_ENABLED
 130 
 131 // Only bother with this argument setup if dtrace is available
 132 
 133   #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
 134   #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
 135 
 136   #define DTRACE_THREAD_PROBE(probe, javathread)                           \
 137     {                                                                      \
 138       ResourceMark rm(this);                                               \
 139       int len = 0;                                                         \
 140       const char* name = (javathread)->get_thread_name();                  \
 141       len = strlen(name);                                                  \
 142       HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */               \
 143         (char *) name, len,                                                \
 144         java_lang_Thread::thread_id((javathread)->threadObj()),            \
 145         (uintptr_t) (javathread)->osthread()->thread_id(),                 \
 146         java_lang_Thread::is_daemon((javathread)->threadObj()));           \
 147     }
 148 
 149 #else //  ndef DTRACE_ENABLED
 150 
 151   #define DTRACE_THREAD_PROBE(probe, javathread)
 152 
 153 #endif // ndef DTRACE_ENABLED
 154 
 155 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 156 // Current thread is maintained as a thread-local variable
 157 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
 158 #endif
 159 // Class hierarchy
 160 // - Thread
 161 //   - VMThread
 162 //   - WatcherThread
 163 //   - ConcurrentMarkSweepThread
 164 //   - JavaThread
 165 //     - CompilerThread
 166 
 167 // ======= Thread ========
 168 // Support for forcing alignment of thread objects for biased locking
 169 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
 170   if (UseBiasedLocking) {
 171     const int alignment = markOopDesc::biased_lock_alignment;
 172     size_t aligned_size = size + (alignment - sizeof(intptr_t));
 173     void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
 174                                           : AllocateHeap(aligned_size, flags, CURRENT_PC,
 175                                                          AllocFailStrategy::RETURN_NULL);
 176     void* aligned_addr     = align_up(real_malloc_addr, alignment);
 177     assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
 178            ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
 179            "JavaThread alignment code overflowed allocated storage");
 180     if (aligned_addr != real_malloc_addr) {
 181       log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
 182                               p2i(real_malloc_addr),
 183                               p2i(aligned_addr));
 184     }
 185     ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
 186     return aligned_addr;
 187   } else {
 188     return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
 189                        : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
 190   }
 191 }
 192 
 193 void Thread::operator delete(void* p) {
 194   if (UseBiasedLocking) {
 195     void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
 196     FreeHeap(real_malloc_addr);
 197   } else {
 198     FreeHeap(p);
 199   }
 200 }
 201 
 202 
 203 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
 204 // JavaThread
 205 
 206 
 207 Thread::Thread() {
 208   // stack and get_thread
 209   set_stack_base(NULL);
 210   set_stack_size(0);
 211   set_self_raw_id(0);
 212   set_lgrp_id(-1);
 213   DEBUG_ONLY(clear_suspendible_thread();)
 214 
 215   // allocated data structures
 216   set_osthread(NULL);
 217   set_resource_area(new (mtThread)ResourceArea());
 218   DEBUG_ONLY(_current_resource_mark = NULL;)
 219   set_handle_area(new (mtThread) HandleArea(NULL));
 220   set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
 221   set_active_handles(NULL);
 222   set_free_handle_block(NULL);
 223   set_last_handle_mark(NULL);
 224 
 225   // This initial value ==> never claimed.
 226   _oops_do_parity = 0;
 227 
 228   // the handle mark links itself to last_handle_mark
 229   new HandleMark(this);
 230 
 231   // plain initialization
 232   debug_only(_owned_locks = NULL;)
 233   debug_only(_allow_allocation_count = 0;)
 234   NOT_PRODUCT(_allow_safepoint_count = 0;)
 235   NOT_PRODUCT(_skip_gcalot = false;)
 236   _jvmti_env_iteration_count = 0;
 237   set_allocated_bytes(0);
 238   _vm_operation_started_count = 0;
 239   _vm_operation_completed_count = 0;
 240   _current_pending_monitor = NULL;
 241   _current_pending_monitor_is_from_java = true;
 242   _current_waiting_monitor = NULL;
 243   _num_nested_signal = 0;
 244   omFreeList = NULL;
 245   omFreeCount = 0;
 246   omFreeProvision = 32;
 247   omInUseList = NULL;
 248   omInUseCount = 0;
 249 
 250 #ifdef ASSERT
 251   _visited_for_critical_count = false;
 252 #endif
 253 
 254   _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
 255                          Monitor::_safepoint_check_sometimes);
 256   _suspend_flags = 0;
 257 
 258   // thread-specific hashCode stream generator state - Marsaglia shift-xor form
 259   _hashStateX = os::random();
 260   _hashStateY = 842502087;
 261   _hashStateZ = 0x8767;    // (int)(3579807591LL & 0xffff) ;
 262   _hashStateW = 273326509;
 263 
 264   _OnTrap   = 0;
 265   _schedctl = NULL;
 266   _Stalled  = 0;
 267   _TypeTag  = 0x2BAD;
 268 
 269   // Many of the following fields are effectively final - immutable
 270   // Note that nascent threads can't use the Native Monitor-Mutex
 271   // construct until the _MutexEvent is initialized ...
 272   // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
 273   // we might instead use a stack of ParkEvents that we could provision on-demand.
 274   // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
 275   // and ::Release()
 276   _ParkEvent   = ParkEvent::Allocate(this);
 277   _SleepEvent  = ParkEvent::Allocate(this);
 278   _MutexEvent  = ParkEvent::Allocate(this);
 279   _MuxEvent    = ParkEvent::Allocate(this);
 280 
 281 #ifdef CHECK_UNHANDLED_OOPS
 282   if (CheckUnhandledOops) {
 283     _unhandled_oops = new UnhandledOops(this);
 284   }
 285 #endif // CHECK_UNHANDLED_OOPS
 286 #ifdef ASSERT
 287   if (UseBiasedLocking) {
 288     assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
 289     assert(this == _real_malloc_address ||
 290            this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
 291            "bug in forced alignment of thread objects");
 292   }
 293 #endif // ASSERT
 294 }
 295 
 296 void Thread::initialize_thread_current() {
 297 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 298   assert(_thr_current == NULL, "Thread::current already initialized");
 299   _thr_current = this;
 300 #endif
 301   assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
 302   ThreadLocalStorage::set_thread(this);
 303   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 304 }
 305 
 306 void Thread::clear_thread_current() {
 307   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 308 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 309   _thr_current = NULL;
 310 #endif
 311   ThreadLocalStorage::set_thread(NULL);
 312 }
 313 
 314 void Thread::record_stack_base_and_size() {
 315   set_stack_base(os::current_stack_base());
 316   set_stack_size(os::current_stack_size());
 317   // CR 7190089: on Solaris, primordial thread's stack is adjusted
 318   // in initialize_thread(). Without the adjustment, stack size is
 319   // incorrect if stack is set to unlimited (ulimit -s unlimited).
 320   // So far, only Solaris has real implementation of initialize_thread().
 321   //
 322   // set up any platform-specific state.
 323   os::initialize_thread(this);
 324 
 325   // Set stack limits after thread is initialized.
 326   if (is_Java_thread()) {
 327     ((JavaThread*) this)->set_stack_overflow_limit();
 328     ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
 329   }
 330 #if INCLUDE_NMT
 331   // record thread's native stack, stack grows downward
 332   MemTracker::record_thread_stack(stack_end(), stack_size());
 333 #endif // INCLUDE_NMT
 334   log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
 335     PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
 336     os::current_thread_id(), p2i(stack_base() - stack_size()),
 337     p2i(stack_base()), stack_size()/1024);
 338 }
 339 
 340 
 341 Thread::~Thread() {
 342   EVENT_THREAD_DESTRUCT(this);
 343 
 344   // stack_base can be NULL if the thread is never started or exited before
 345   // record_stack_base_and_size called. Although, we would like to ensure
 346   // that all started threads do call record_stack_base_and_size(), there is
 347   // not proper way to enforce that.
 348 #if INCLUDE_NMT
 349   if (_stack_base != NULL) {
 350     MemTracker::release_thread_stack(stack_end(), stack_size());
 351 #ifdef ASSERT
 352     set_stack_base(NULL);
 353 #endif
 354   }
 355 #endif // INCLUDE_NMT
 356 
 357   // deallocate data structures
 358   delete resource_area();
 359   // since the handle marks are using the handle area, we have to deallocated the root
 360   // handle mark before deallocating the thread's handle area,
 361   assert(last_handle_mark() != NULL, "check we have an element");
 362   delete last_handle_mark();
 363   assert(last_handle_mark() == NULL, "check we have reached the end");
 364 
 365   // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
 366   // We NULL out the fields for good hygiene.
 367   ParkEvent::Release(_ParkEvent); _ParkEvent   = NULL;
 368   ParkEvent::Release(_SleepEvent); _SleepEvent  = NULL;
 369   ParkEvent::Release(_MutexEvent); _MutexEvent  = NULL;
 370   ParkEvent::Release(_MuxEvent); _MuxEvent    = NULL;
 371 
 372   delete handle_area();
 373   delete metadata_handles();
 374 
 375   // SR_handler uses this as a termination indicator -
 376   // needs to happen before os::free_thread()
 377   delete _SR_lock;
 378   _SR_lock = NULL;
 379 
 380   // osthread() can be NULL, if creation of thread failed.
 381   if (osthread() != NULL) os::free_thread(osthread());
 382 
 383   // clear Thread::current if thread is deleting itself.
 384   // Needed to ensure JNI correctly detects non-attached threads.
 385   if (this == Thread::current()) {
 386     clear_thread_current();
 387   }
 388 
 389   CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
 390 }
 391 
 392 // NOTE: dummy function for assertion purpose.
 393 void Thread::run() {
 394   ShouldNotReachHere();
 395 }
 396 
 397 #ifdef ASSERT
 398 // Private method to check for dangling thread pointer
 399 void check_for_dangling_thread_pointer(Thread *thread) {
 400   assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
 401          "possibility of dangling Thread pointer");
 402 }
 403 #endif
 404 
 405 ThreadPriority Thread::get_priority(const Thread* const thread) {
 406   ThreadPriority priority;
 407   // Can return an error!
 408   (void)os::get_priority(thread, priority);
 409   assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
 410   return priority;
 411 }
 412 
 413 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
 414   debug_only(check_for_dangling_thread_pointer(thread);)
 415   // Can return an error!
 416   (void)os::set_priority(thread, priority);
 417 }
 418 
 419 
 420 void Thread::start(Thread* thread) {
 421   // Start is different from resume in that its safety is guaranteed by context or
 422   // being called from a Java method synchronized on the Thread object.
 423   if (!DisableStartThread) {
 424     if (thread->is_Java_thread()) {
 425       // Initialize the thread state to RUNNABLE before starting this thread.
 426       // Can not set it after the thread started because we do not know the
 427       // exact thread state at that time. It could be in MONITOR_WAIT or
 428       // in SLEEPING or some other state.
 429       java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
 430                                           java_lang_Thread::RUNNABLE);
 431     }
 432     os::start_thread(thread);
 433   }
 434 }
 435 
 436 // Enqueue a VM_Operation to do the job for us - sometime later
 437 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
 438   VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
 439   VMThread::execute(vm_stop);
 440 }
 441 
 442 
 443 // Check if an external suspend request has completed (or has been
 444 // cancelled). Returns true if the thread is externally suspended and
 445 // false otherwise.
 446 //
 447 // The bits parameter returns information about the code path through
 448 // the routine. Useful for debugging:
 449 //
 450 // set in is_ext_suspend_completed():
 451 // 0x00000001 - routine was entered
 452 // 0x00000010 - routine return false at end
 453 // 0x00000100 - thread exited (return false)
 454 // 0x00000200 - suspend request cancelled (return false)
 455 // 0x00000400 - thread suspended (return true)
 456 // 0x00001000 - thread is in a suspend equivalent state (return true)
 457 // 0x00002000 - thread is native and walkable (return true)
 458 // 0x00004000 - thread is native_trans and walkable (needed retry)
 459 //
 460 // set in wait_for_ext_suspend_completion():
 461 // 0x00010000 - routine was entered
 462 // 0x00020000 - suspend request cancelled before loop (return false)
 463 // 0x00040000 - thread suspended before loop (return true)
 464 // 0x00080000 - suspend request cancelled in loop (return false)
 465 // 0x00100000 - thread suspended in loop (return true)
 466 // 0x00200000 - suspend not completed during retry loop (return false)
 467 
 468 // Helper class for tracing suspend wait debug bits.
 469 //
 470 // 0x00000100 indicates that the target thread exited before it could
 471 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
 472 // 0x00080000 each indicate a cancelled suspend request so they don't
 473 // count as wait failures either.
 474 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
 475 
 476 class TraceSuspendDebugBits : public StackObj {
 477  private:
 478   JavaThread * jt;
 479   bool         is_wait;
 480   bool         called_by_wait;  // meaningful when !is_wait
 481   uint32_t *   bits;
 482 
 483  public:
 484   TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
 485                         uint32_t *_bits) {
 486     jt             = _jt;
 487     is_wait        = _is_wait;
 488     called_by_wait = _called_by_wait;
 489     bits           = _bits;
 490   }
 491 
 492   ~TraceSuspendDebugBits() {
 493     if (!is_wait) {
 494 #if 1
 495       // By default, don't trace bits for is_ext_suspend_completed() calls.
 496       // That trace is very chatty.
 497       return;
 498 #else
 499       if (!called_by_wait) {
 500         // If tracing for is_ext_suspend_completed() is enabled, then only
 501         // trace calls to it from wait_for_ext_suspend_completion()
 502         return;
 503       }
 504 #endif
 505     }
 506 
 507     if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
 508       if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
 509         MutexLocker ml(Threads_lock);  // needed for get_thread_name()
 510         ResourceMark rm;
 511 
 512         tty->print_cr(
 513                       "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
 514                       jt->get_thread_name(), *bits);
 515 
 516         guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
 517       }
 518     }
 519   }
 520 };
 521 #undef DEBUG_FALSE_BITS
 522 
 523 
 524 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
 525                                           uint32_t *bits) {
 526   TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
 527 
 528   bool did_trans_retry = false;  // only do thread_in_native_trans retry once
 529   bool do_trans_retry;           // flag to force the retry
 530 
 531   *bits |= 0x00000001;
 532 
 533   do {
 534     do_trans_retry = false;
 535 
 536     if (is_exiting()) {
 537       // Thread is in the process of exiting. This is always checked
 538       // first to reduce the risk of dereferencing a freed JavaThread.
 539       *bits |= 0x00000100;
 540       return false;
 541     }
 542 
 543     if (!is_external_suspend()) {
 544       // Suspend request is cancelled. This is always checked before
 545       // is_ext_suspended() to reduce the risk of a rogue resume
 546       // confusing the thread that made the suspend request.
 547       *bits |= 0x00000200;
 548       return false;
 549     }
 550 
 551     if (is_ext_suspended()) {
 552       // thread is suspended
 553       *bits |= 0x00000400;
 554       return true;
 555     }
 556 
 557     // Now that we no longer do hard suspends of threads running
 558     // native code, the target thread can be changing thread state
 559     // while we are in this routine:
 560     //
 561     //   _thread_in_native -> _thread_in_native_trans -> _thread_blocked
 562     //
 563     // We save a copy of the thread state as observed at this moment
 564     // and make our decision about suspend completeness based on the
 565     // copy. This closes the race where the thread state is seen as
 566     // _thread_in_native_trans in the if-thread_blocked check, but is
 567     // seen as _thread_blocked in if-thread_in_native_trans check.
 568     JavaThreadState save_state = thread_state();
 569 
 570     if (save_state == _thread_blocked && is_suspend_equivalent()) {
 571       // If the thread's state is _thread_blocked and this blocking
 572       // condition is known to be equivalent to a suspend, then we can
 573       // consider the thread to be externally suspended. This means that
 574       // the code that sets _thread_blocked has been modified to do
 575       // self-suspension if the blocking condition releases. We also
 576       // used to check for CONDVAR_WAIT here, but that is now covered by
 577       // the _thread_blocked with self-suspension check.
 578       //
 579       // Return true since we wouldn't be here unless there was still an
 580       // external suspend request.
 581       *bits |= 0x00001000;
 582       return true;
 583     } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
 584       // Threads running native code will self-suspend on native==>VM/Java
 585       // transitions. If its stack is walkable (should always be the case
 586       // unless this function is called before the actual java_suspend()
 587       // call), then the wait is done.
 588       *bits |= 0x00002000;
 589       return true;
 590     } else if (!called_by_wait && !did_trans_retry &&
 591                save_state == _thread_in_native_trans &&
 592                frame_anchor()->walkable()) {
 593       // The thread is transitioning from thread_in_native to another
 594       // thread state. check_safepoint_and_suspend_for_native_trans()
 595       // will force the thread to self-suspend. If it hasn't gotten
 596       // there yet we may have caught the thread in-between the native
 597       // code check above and the self-suspend. Lucky us. If we were
 598       // called by wait_for_ext_suspend_completion(), then it
 599       // will be doing the retries so we don't have to.
 600       //
 601       // Since we use the saved thread state in the if-statement above,
 602       // there is a chance that the thread has already transitioned to
 603       // _thread_blocked by the time we get here. In that case, we will
 604       // make a single unnecessary pass through the logic below. This
 605       // doesn't hurt anything since we still do the trans retry.
 606 
 607       *bits |= 0x00004000;
 608 
 609       // Once the thread leaves thread_in_native_trans for another
 610       // thread state, we break out of this retry loop. We shouldn't
 611       // need this flag to prevent us from getting back here, but
 612       // sometimes paranoia is good.
 613       did_trans_retry = true;
 614 
 615       // We wait for the thread to transition to a more usable state.
 616       for (int i = 1; i <= SuspendRetryCount; i++) {
 617         // We used to do an "os::yield_all(i)" call here with the intention
 618         // that yielding would increase on each retry. However, the parameter
 619         // is ignored on Linux which means the yield didn't scale up. Waiting
 620         // on the SR_lock below provides a much more predictable scale up for
 621         // the delay. It also provides a simple/direct point to check for any
 622         // safepoint requests from the VMThread
 623 
 624         // temporarily drops SR_lock while doing wait with safepoint check
 625         // (if we're a JavaThread - the WatcherThread can also call this)
 626         // and increase delay with each retry
 627         SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 628 
 629         // check the actual thread state instead of what we saved above
 630         if (thread_state() != _thread_in_native_trans) {
 631           // the thread has transitioned to another thread state so
 632           // try all the checks (except this one) one more time.
 633           do_trans_retry = true;
 634           break;
 635         }
 636       } // end retry loop
 637 
 638 
 639     }
 640   } while (do_trans_retry);
 641 
 642   *bits |= 0x00000010;
 643   return false;
 644 }
 645 
 646 // Wait for an external suspend request to complete (or be cancelled).
 647 // Returns true if the thread is externally suspended and false otherwise.
 648 //
 649 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
 650                                                  uint32_t *bits) {
 651   TraceSuspendDebugBits tsdb(this, true /* is_wait */,
 652                              false /* !called_by_wait */, bits);
 653 
 654   // local flag copies to minimize SR_lock hold time
 655   bool is_suspended;
 656   bool pending;
 657   uint32_t reset_bits;
 658 
 659   // set a marker so is_ext_suspend_completed() knows we are the caller
 660   *bits |= 0x00010000;
 661 
 662   // We use reset_bits to reinitialize the bits value at the top of
 663   // each retry loop. This allows the caller to make use of any
 664   // unused bits for their own marking purposes.
 665   reset_bits = *bits;
 666 
 667   {
 668     MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
 669     is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 670                                             delay, bits);
 671     pending = is_external_suspend();
 672   }
 673   // must release SR_lock to allow suspension to complete
 674 
 675   if (!pending) {
 676     // A cancelled suspend request is the only false return from
 677     // is_ext_suspend_completed() that keeps us from entering the
 678     // retry loop.
 679     *bits |= 0x00020000;
 680     return false;
 681   }
 682 
 683   if (is_suspended) {
 684     *bits |= 0x00040000;
 685     return true;
 686   }
 687 
 688   for (int i = 1; i <= retries; i++) {
 689     *bits = reset_bits;  // reinit to only track last retry
 690 
 691     // We used to do an "os::yield_all(i)" call here with the intention
 692     // that yielding would increase on each retry. However, the parameter
 693     // is ignored on Linux which means the yield didn't scale up. Waiting
 694     // on the SR_lock below provides a much more predictable scale up for
 695     // the delay. It also provides a simple/direct point to check for any
 696     // safepoint requests from the VMThread
 697 
 698     {
 699       MutexLocker ml(SR_lock());
 700       // wait with safepoint check (if we're a JavaThread - the WatcherThread
 701       // can also call this)  and increase delay with each retry
 702       SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 703 
 704       is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 705                                               delay, bits);
 706 
 707       // It is possible for the external suspend request to be cancelled
 708       // (by a resume) before the actual suspend operation is completed.
 709       // Refresh our local copy to see if we still need to wait.
 710       pending = is_external_suspend();
 711     }
 712 
 713     if (!pending) {
 714       // A cancelled suspend request is the only false return from
 715       // is_ext_suspend_completed() that keeps us from staying in the
 716       // retry loop.
 717       *bits |= 0x00080000;
 718       return false;
 719     }
 720 
 721     if (is_suspended) {
 722       *bits |= 0x00100000;
 723       return true;
 724     }
 725   } // end retry loop
 726 
 727   // thread did not suspend after all our retries
 728   *bits |= 0x00200000;
 729   return false;
 730 }
 731 
 732 #ifndef PRODUCT
 733 void JavaThread::record_jump(address target, address instr, const char* file,
 734                              int line) {
 735 
 736   // This should not need to be atomic as the only way for simultaneous
 737   // updates is via interrupts. Even then this should be rare or non-existent
 738   // and we don't care that much anyway.
 739 
 740   int index = _jmp_ring_index;
 741   _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
 742   _jmp_ring[index]._target = (intptr_t) target;
 743   _jmp_ring[index]._instruction = (intptr_t) instr;
 744   _jmp_ring[index]._file = file;
 745   _jmp_ring[index]._line = line;
 746 }
 747 #endif // PRODUCT
 748 
 749 // Called by flat profiler
 750 // Callers have already called wait_for_ext_suspend_completion
 751 // The assertion for that is currently too complex to put here:
 752 bool JavaThread::profile_last_Java_frame(frame* _fr) {
 753   bool gotframe = false;
 754   // self suspension saves needed state.
 755   if (has_last_Java_frame() && _anchor.walkable()) {
 756     *_fr = pd_last_frame();
 757     gotframe = true;
 758   }
 759   return gotframe;
 760 }
 761 
 762 void Thread::interrupt(Thread* thread) {
 763   debug_only(check_for_dangling_thread_pointer(thread);)
 764   os::interrupt(thread);
 765 }
 766 
 767 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
 768   debug_only(check_for_dangling_thread_pointer(thread);)
 769   // Note:  If clear_interrupted==false, this simply fetches and
 770   // returns the value of the field osthread()->interrupted().
 771   return os::is_interrupted(thread, clear_interrupted);
 772 }
 773 
 774 
 775 // GC Support
 776 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
 777   jint thread_parity = _oops_do_parity;
 778   if (thread_parity != strong_roots_parity) {
 779     jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
 780     if (res == thread_parity) {
 781       return true;
 782     } else {
 783       guarantee(res == strong_roots_parity, "Or else what?");
 784       return false;
 785     }
 786   }
 787   return false;
 788 }
 789 
 790 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
 791   active_handles()->oops_do(f);
 792   // Do oop for ThreadShadow
 793   f->do_oop((oop*)&_pending_exception);
 794   handle_area()->oops_do(f);
 795 
 796   if (MonitorInUseLists) {
 797     // When using thread local monitor lists, we scan them here,
 798     // and the remaining global monitors in ObjectSynchronizer::oops_do().
 799     ObjectSynchronizer::thread_local_used_oops_do(this, f);
 800   }
 801 }
 802 
 803 void Thread::metadata_handles_do(void f(Metadata*)) {
 804   // Only walk the Handles in Thread.
 805   if (metadata_handles() != NULL) {
 806     for (int i = 0; i< metadata_handles()->length(); i++) {
 807       f(metadata_handles()->at(i));
 808     }
 809   }
 810 }
 811 
 812 void Thread::print_on(outputStream* st) const {
 813   // get_priority assumes osthread initialized
 814   if (osthread() != NULL) {
 815     int os_prio;
 816     if (os::get_native_priority(this, &os_prio) == OS_OK) {
 817       st->print("os_prio=%d ", os_prio);
 818     }
 819     st->print("tid=" INTPTR_FORMAT " ", p2i(this));
 820     ext().print_on(st);
 821     osthread()->print_on(st);
 822   }
 823   debug_only(if (WizardMode) print_owned_locks_on(st);)
 824 }
 825 
 826 // Thread::print_on_error() is called by fatal error handler. Don't use
 827 // any lock or allocate memory.
 828 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
 829   assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
 830 
 831   if (is_VM_thread())                 { st->print("VMThread"); }
 832   else if (is_GC_task_thread())       { st->print("GCTaskThread"); }
 833   else if (is_Watcher_thread())       { st->print("WatcherThread"); }
 834   else if (is_ConcurrentGC_thread())  { st->print("ConcurrentGCThread"); }
 835   else                                { st->print("Thread"); }
 836 
 837   if (is_Named_thread()) {
 838     st->print(" \"%s\"", name());
 839   }
 840 
 841   st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
 842             p2i(stack_end()), p2i(stack_base()));
 843 
 844   if (osthread()) {
 845     st->print(" [id=%d]", osthread()->thread_id());
 846   }
 847 }
 848 
 849 #ifdef ASSERT
 850 void Thread::print_owned_locks_on(outputStream* st) const {
 851   Monitor *cur = _owned_locks;
 852   if (cur == NULL) {
 853     st->print(" (no locks) ");
 854   } else {
 855     st->print_cr(" Locks owned:");
 856     while (cur) {
 857       cur->print_on(st);
 858       cur = cur->next();
 859     }
 860   }
 861 }
 862 
 863 static int ref_use_count  = 0;
 864 
 865 bool Thread::owns_locks_but_compiled_lock() const {
 866   for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 867     if (cur != Compile_lock) return true;
 868   }
 869   return false;
 870 }
 871 
 872 
 873 #endif
 874 
 875 #ifndef PRODUCT
 876 
 877 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
 878 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
 879 // no threads which allow_vm_block's are held
 880 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
 881   // Check if current thread is allowed to block at a safepoint
 882   if (!(_allow_safepoint_count == 0)) {
 883     fatal("Possible safepoint reached by thread that does not allow it");
 884   }
 885   if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
 886     fatal("LEAF method calling lock?");
 887   }
 888 
 889 #ifdef ASSERT
 890   if (potential_vm_operation && is_Java_thread()
 891       && !Universe::is_bootstrapping()) {
 892     // Make sure we do not hold any locks that the VM thread also uses.
 893     // This could potentially lead to deadlocks
 894     for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 895       // Threads_lock is special, since the safepoint synchronization will not start before this is
 896       // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
 897       // since it is used to transfer control between JavaThreads and the VMThread
 898       // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
 899       if ((cur->allow_vm_block() &&
 900            cur != Threads_lock &&
 901            cur != Compile_lock &&               // Temporary: should not be necessary when we get separate compilation
 902            cur != VMOperationRequest_lock &&
 903            cur != VMOperationQueue_lock) ||
 904            cur->rank() == Mutex::special) {
 905         fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
 906       }
 907     }
 908   }
 909 
 910   if (GCALotAtAllSafepoints) {
 911     // We could enter a safepoint here and thus have a gc
 912     InterfaceSupport::check_gc_alot();
 913   }
 914 #endif
 915 }
 916 #endif
 917 
 918 bool Thread::is_in_stack(address adr) const {
 919   assert(Thread::current() == this, "is_in_stack can only be called from current thread");
 920   address end = os::current_stack_pointer();
 921   // Allow non Java threads to call this without stack_base
 922   if (_stack_base == NULL) return true;
 923   if (stack_base() >= adr && adr >= end) return true;
 924 
 925   return false;
 926 }
 927 
 928 bool Thread::is_in_usable_stack(address adr) const {
 929   size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
 930   size_t usable_stack_size = _stack_size - stack_guard_size;
 931 
 932   return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
 933 }
 934 
 935 
 936 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
 937 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
 938 // used for compilation in the future. If that change is made, the need for these methods
 939 // should be revisited, and they should be removed if possible.
 940 
 941 bool Thread::is_lock_owned(address adr) const {
 942   return on_local_stack(adr);
 943 }
 944 
 945 bool Thread::set_as_starting_thread() {
 946   // NOTE: this must be called inside the main thread.
 947   return os::create_main_thread((JavaThread*)this);
 948 }
 949 
 950 static void initialize_class(Symbol* class_name, TRAPS) {
 951   Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
 952   InstanceKlass::cast(klass)->initialize(CHECK);
 953 }
 954 
 955 
 956 // Creates the initial ThreadGroup
 957 static Handle create_initial_thread_group(TRAPS) {
 958   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
 959   InstanceKlass* ik = InstanceKlass::cast(k);
 960 
 961   Handle system_instance = ik->allocate_instance_handle(CHECK_NH);
 962   {
 963     JavaValue result(T_VOID);
 964     JavaCalls::call_special(&result,
 965                             system_instance,
 966                             ik,
 967                             vmSymbols::object_initializer_name(),
 968                             vmSymbols::void_method_signature(),
 969                             CHECK_NH);
 970   }
 971   Universe::set_system_thread_group(system_instance());
 972 
 973   Handle main_instance = ik->allocate_instance_handle(CHECK_NH);
 974   {
 975     JavaValue result(T_VOID);
 976     Handle string = java_lang_String::create_from_str("main", CHECK_NH);
 977     JavaCalls::call_special(&result,
 978                             main_instance,
 979                             ik,
 980                             vmSymbols::object_initializer_name(),
 981                             vmSymbols::threadgroup_string_void_signature(),
 982                             system_instance,
 983                             string,
 984                             CHECK_NH);
 985   }
 986   return main_instance;
 987 }
 988 
 989 // Creates the initial Thread
 990 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
 991                                  TRAPS) {
 992   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
 993   InstanceKlass* ik = InstanceKlass::cast(k);
 994   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
 995 
 996   java_lang_Thread::set_thread(thread_oop(), thread);
 997   java_lang_Thread::set_priority(thread_oop(), NormPriority);
 998   thread->set_threadObj(thread_oop());
 999 
1000   Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1001 
1002   JavaValue result(T_VOID);
1003   JavaCalls::call_special(&result, thread_oop,
1004                           ik,
1005                           vmSymbols::object_initializer_name(),
1006                           vmSymbols::threadgroup_string_void_signature(),
1007                           thread_group,
1008                           string,
1009                           CHECK_NULL);
1010   return thread_oop();
1011 }
1012 
1013 char java_runtime_name[128] = "";
1014 char java_runtime_version[128] = "";
1015 
1016 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1017 static const char* get_java_runtime_name(TRAPS) {
1018   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1019                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1020   fieldDescriptor fd;
1021   bool found = k != NULL &&
1022                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1023                                                         vmSymbols::string_signature(), &fd);
1024   if (found) {
1025     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1026     if (name_oop == NULL) {
1027       return NULL;
1028     }
1029     const char* name = java_lang_String::as_utf8_string(name_oop,
1030                                                         java_runtime_name,
1031                                                         sizeof(java_runtime_name));
1032     return name;
1033   } else {
1034     return NULL;
1035   }
1036 }
1037 
1038 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1039 static const char* get_java_runtime_version(TRAPS) {
1040   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1041                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1042   fieldDescriptor fd;
1043   bool found = k != NULL &&
1044                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1045                                                         vmSymbols::string_signature(), &fd);
1046   if (found) {
1047     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1048     if (name_oop == NULL) {
1049       return NULL;
1050     }
1051     const char* name = java_lang_String::as_utf8_string(name_oop,
1052                                                         java_runtime_version,
1053                                                         sizeof(java_runtime_version));
1054     return name;
1055   } else {
1056     return NULL;
1057   }
1058 }
1059 
1060 // General purpose hook into Java code, run once when the VM is initialized.
1061 // The Java library method itself may be changed independently from the VM.
1062 static void call_postVMInitHook(TRAPS) {
1063   Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1064   if (klass != NULL) {
1065     JavaValue result(T_VOID);
1066     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1067                            vmSymbols::void_method_signature(),
1068                            CHECK);
1069   }
1070 }
1071 
1072 static void reset_vm_info_property(TRAPS) {
1073   // the vm info string
1074   ResourceMark rm(THREAD);
1075   const char *vm_info = VM_Version::vm_info_string();
1076 
1077   // java.lang.System class
1078   Klass* klass =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1079 
1080   // setProperty arguments
1081   Handle key_str    = java_lang_String::create_from_str("java.vm.info", CHECK);
1082   Handle value_str  = java_lang_String::create_from_str(vm_info, CHECK);
1083 
1084   // return value
1085   JavaValue r(T_OBJECT);
1086 
1087   // public static String setProperty(String key, String value);
1088   JavaCalls::call_static(&r,
1089                          klass,
1090                          vmSymbols::setProperty_name(),
1091                          vmSymbols::string_string_string_signature(),
1092                          key_str,
1093                          value_str,
1094                          CHECK);
1095 }
1096 
1097 
1098 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1099                                     bool daemon, TRAPS) {
1100   assert(thread_group.not_null(), "thread group should be specified");
1101   assert(threadObj() == NULL, "should only create Java thread object once");
1102 
1103   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1104   InstanceKlass* ik = InstanceKlass::cast(k);
1105   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1106 
1107   java_lang_Thread::set_thread(thread_oop(), this);
1108   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1109   set_threadObj(thread_oop());
1110 
1111   JavaValue result(T_VOID);
1112   if (thread_name != NULL) {
1113     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1114     // Thread gets assigned specified name and null target
1115     JavaCalls::call_special(&result,
1116                             thread_oop,
1117                             ik,
1118                             vmSymbols::object_initializer_name(),
1119                             vmSymbols::threadgroup_string_void_signature(),
1120                             thread_group, // Argument 1
1121                             name,         // Argument 2
1122                             THREAD);
1123   } else {
1124     // Thread gets assigned name "Thread-nnn" and null target
1125     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1126     JavaCalls::call_special(&result,
1127                             thread_oop,
1128                             ik,
1129                             vmSymbols::object_initializer_name(),
1130                             vmSymbols::threadgroup_runnable_void_signature(),
1131                             thread_group, // Argument 1
1132                             Handle(),     // Argument 2
1133                             THREAD);
1134   }
1135 
1136 
1137   if (daemon) {
1138     java_lang_Thread::set_daemon(thread_oop());
1139   }
1140 
1141   if (HAS_PENDING_EXCEPTION) {
1142     return;
1143   }
1144 
1145   Klass* group =  SystemDictionary::ThreadGroup_klass();
1146   Handle threadObj(THREAD, this->threadObj());
1147 
1148   JavaCalls::call_special(&result,
1149                           thread_group,
1150                           group,
1151                           vmSymbols::add_method_name(),
1152                           vmSymbols::thread_void_signature(),
1153                           threadObj,          // Arg 1
1154                           THREAD);
1155 }
1156 
1157 // NamedThread --  non-JavaThread subclasses with multiple
1158 // uniquely named instances should derive from this.
1159 NamedThread::NamedThread() : Thread() {
1160   _name = NULL;
1161   _processed_thread = NULL;
1162   _gc_id = GCId::undefined();
1163 }
1164 
1165 NamedThread::~NamedThread() {
1166   if (_name != NULL) {
1167     FREE_C_HEAP_ARRAY(char, _name);
1168     _name = NULL;
1169   }
1170 }
1171 
1172 void NamedThread::set_name(const char* format, ...) {
1173   guarantee(_name == NULL, "Only get to set name once.");
1174   _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1175   guarantee(_name != NULL, "alloc failure");
1176   va_list ap;
1177   va_start(ap, format);
1178   jio_vsnprintf(_name, max_name_len, format, ap);
1179   va_end(ap);
1180 }
1181 
1182 void NamedThread::initialize_named_thread() {
1183   set_native_thread_name(name());
1184 }
1185 
1186 void NamedThread::print_on(outputStream* st) const {
1187   st->print("\"%s\" ", name());
1188   Thread::print_on(st);
1189   st->cr();
1190 }
1191 
1192 
1193 // ======= WatcherThread ========
1194 
1195 // The watcher thread exists to simulate timer interrupts.  It should
1196 // be replaced by an abstraction over whatever native support for
1197 // timer interrupts exists on the platform.
1198 
1199 WatcherThread* WatcherThread::_watcher_thread   = NULL;
1200 bool WatcherThread::_startable = false;
1201 volatile bool  WatcherThread::_should_terminate = false;
1202 
1203 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) {
1204   assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1205   if (os::create_thread(this, os::watcher_thread)) {
1206     _watcher_thread = this;
1207 
1208     // Set the watcher thread to the highest OS priority which should not be
1209     // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1210     // is created. The only normal thread using this priority is the reference
1211     // handler thread, which runs for very short intervals only.
1212     // If the VMThread's priority is not lower than the WatcherThread profiling
1213     // will be inaccurate.
1214     os::set_priority(this, MaxPriority);
1215     if (!DisableStartThread) {
1216       os::start_thread(this);
1217     }
1218   }
1219 }
1220 
1221 int WatcherThread::sleep() const {
1222   // The WatcherThread does not participate in the safepoint protocol
1223   // for the PeriodicTask_lock because it is not a JavaThread.
1224   MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1225 
1226   if (_should_terminate) {
1227     // check for termination before we do any housekeeping or wait
1228     return 0;  // we did not sleep.
1229   }
1230 
1231   // remaining will be zero if there are no tasks,
1232   // causing the WatcherThread to sleep until a task is
1233   // enrolled
1234   int remaining = PeriodicTask::time_to_wait();
1235   int time_slept = 0;
1236 
1237   // we expect this to timeout - we only ever get unparked when
1238   // we should terminate or when a new task has been enrolled
1239   OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1240 
1241   jlong time_before_loop = os::javaTimeNanos();
1242 
1243   while (true) {
1244     bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1245                                             remaining);
1246     jlong now = os::javaTimeNanos();
1247 
1248     if (remaining == 0) {
1249       // if we didn't have any tasks we could have waited for a long time
1250       // consider the time_slept zero and reset time_before_loop
1251       time_slept = 0;
1252       time_before_loop = now;
1253     } else {
1254       // need to recalculate since we might have new tasks in _tasks
1255       time_slept = (int) ((now - time_before_loop) / 1000000);
1256     }
1257 
1258     // Change to task list or spurious wakeup of some kind
1259     if (timedout || _should_terminate) {
1260       break;
1261     }
1262 
1263     remaining = PeriodicTask::time_to_wait();
1264     if (remaining == 0) {
1265       // Last task was just disenrolled so loop around and wait until
1266       // another task gets enrolled
1267       continue;
1268     }
1269 
1270     remaining -= time_slept;
1271     if (remaining <= 0) {
1272       break;
1273     }
1274   }
1275 
1276   return time_slept;
1277 }
1278 
1279 void WatcherThread::run() {
1280   assert(this == watcher_thread(), "just checking");
1281 
1282   this->record_stack_base_and_size();
1283   this->set_native_thread_name(this->name());
1284   this->set_active_handles(JNIHandleBlock::allocate_block());
1285   while (true) {
1286     assert(watcher_thread() == Thread::current(), "thread consistency check");
1287     assert(watcher_thread() == this, "thread consistency check");
1288 
1289     // Calculate how long it'll be until the next PeriodicTask work
1290     // should be done, and sleep that amount of time.
1291     int time_waited = sleep();
1292 
1293     if (VMError::is_error_reported()) {
1294       // A fatal error has happened, the error handler(VMError::report_and_die)
1295       // should abort JVM after creating an error log file. However in some
1296       // rare cases, the error handler itself might deadlock. Here periodically
1297       // check for error reporting timeouts, and if it happens, just proceed to
1298       // abort the VM.
1299 
1300       // This code is in WatcherThread because WatcherThread wakes up
1301       // periodically so the fatal error handler doesn't need to do anything;
1302       // also because the WatcherThread is less likely to crash than other
1303       // threads.
1304 
1305       for (;;) {
1306         // Note: we use naked sleep in this loop because we want to avoid using
1307         // any kind of VM infrastructure which may be broken at this point.
1308         if (VMError::check_timeout()) {
1309           // We hit error reporting timeout. Error reporting was interrupted and
1310           // will be wrapping things up now (closing files etc). Give it some more
1311           // time, then quit the VM.
1312           os::naked_short_sleep(200);
1313           // Print a message to stderr.
1314           fdStream err(defaultStream::output_fd());
1315           err.print_raw_cr("# [ timer expired, abort... ]");
1316           // skip atexit/vm_exit/vm_abort hooks
1317           os::die();
1318         }
1319 
1320         // Wait a second, then recheck for timeout.
1321         os::naked_short_sleep(999);
1322       }
1323     }
1324 
1325     if (_should_terminate) {
1326       // check for termination before posting the next tick
1327       break;
1328     }
1329 
1330     PeriodicTask::real_time_tick(time_waited);
1331   }
1332 
1333   // Signal that it is terminated
1334   {
1335     MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1336     _watcher_thread = NULL;
1337     Terminator_lock->notify();
1338   }
1339 }
1340 
1341 void WatcherThread::start() {
1342   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1343 
1344   if (watcher_thread() == NULL && _startable) {
1345     _should_terminate = false;
1346     // Create the single instance of WatcherThread
1347     new WatcherThread();
1348   }
1349 }
1350 
1351 void WatcherThread::make_startable() {
1352   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1353   _startable = true;
1354 }
1355 
1356 void WatcherThread::stop() {
1357   {
1358     // Follow normal safepoint aware lock enter protocol since the
1359     // WatcherThread is stopped by another JavaThread.
1360     MutexLocker ml(PeriodicTask_lock);
1361     _should_terminate = true;
1362 
1363     WatcherThread* watcher = watcher_thread();
1364     if (watcher != NULL) {
1365       // unpark the WatcherThread so it can see that it should terminate
1366       watcher->unpark();
1367     }
1368   }
1369 
1370   MutexLocker mu(Terminator_lock);
1371 
1372   while (watcher_thread() != NULL) {
1373     // This wait should make safepoint checks, wait without a timeout,
1374     // and wait as a suspend-equivalent condition.
1375     //
1376     // Note: If the FlatProfiler is running, then this thread is waiting
1377     // for the WatcherThread to terminate and the WatcherThread, via the
1378     // FlatProfiler task, is waiting for the external suspend request on
1379     // this thread to complete. wait_for_ext_suspend_completion() will
1380     // eventually timeout, but that takes time. Making this wait a
1381     // suspend-equivalent condition solves that timeout problem.
1382     //
1383     Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1384                           Mutex::_as_suspend_equivalent_flag);
1385   }
1386 }
1387 
1388 void WatcherThread::unpark() {
1389   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1390   PeriodicTask_lock->notify();
1391 }
1392 
1393 void WatcherThread::print_on(outputStream* st) const {
1394   st->print("\"%s\" ", name());
1395   Thread::print_on(st);
1396   st->cr();
1397 }
1398 
1399 // ======= JavaThread ========
1400 
1401 #if INCLUDE_JVMCI
1402 
1403 jlong* JavaThread::_jvmci_old_thread_counters;
1404 
1405 bool jvmci_counters_include(JavaThread* thread) {
1406   oop threadObj = thread->threadObj();
1407   return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1408 }
1409 
1410 void JavaThread::collect_counters(typeArrayOop array) {
1411   if (JVMCICounterSize > 0) {
1412     MutexLocker tl(Threads_lock);
1413     for (int i = 0; i < array->length(); i++) {
1414       array->long_at_put(i, _jvmci_old_thread_counters[i]);
1415     }
1416     for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) {
1417       if (jvmci_counters_include(tp)) {
1418         for (int i = 0; i < array->length(); i++) {
1419           array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1420         }
1421       }
1422     }
1423   }
1424 }
1425 
1426 #endif // INCLUDE_JVMCI
1427 
1428 // A JavaThread is a normal Java thread
1429 
1430 void JavaThread::initialize() {
1431   // Initialize fields
1432 
1433   set_saved_exception_pc(NULL);
1434   set_threadObj(NULL);
1435   _anchor.clear();
1436   set_entry_point(NULL);
1437   set_jni_functions(jni_functions());
1438   set_callee_target(NULL);
1439   set_vm_result(NULL);
1440   set_vm_result_2(NULL);
1441   set_vframe_array_head(NULL);
1442   set_vframe_array_last(NULL);
1443   set_deferred_locals(NULL);
1444   set_deopt_mark(NULL);
1445   set_deopt_compiled_method(NULL);
1446   clear_must_deopt_id();
1447   set_monitor_chunks(NULL);
1448   set_next(NULL);
1449   set_thread_state(_thread_new);
1450   _terminated = _not_terminated;
1451   _privileged_stack_top = NULL;
1452   _array_for_gc = NULL;
1453   _suspend_equivalent = false;
1454   _in_deopt_handler = 0;
1455   _doing_unsafe_access = false;
1456   _stack_guard_state = stack_guard_unused;
1457 #if INCLUDE_JVMCI
1458   _pending_monitorenter = false;
1459   _pending_deoptimization = -1;
1460   _pending_failed_speculation = NULL;
1461   _pending_transfer_to_interpreter = false;
1462   _adjusting_comp_level = false;
1463   _jvmci._alternate_call_target = NULL;
1464   assert(_jvmci._implicit_exception_pc == NULL, "must be");
1465   if (JVMCICounterSize > 0) {
1466     _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1467     memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1468   } else {
1469     _jvmci_counters = NULL;
1470   }
1471 #endif // INCLUDE_JVMCI
1472   _reserved_stack_activation = NULL;  // stack base not known yet
1473   (void)const_cast<oop&>(_exception_oop = oop(NULL));
1474   _exception_pc  = 0;
1475   _exception_handler_pc = 0;
1476   _is_method_handle_return = 0;
1477   _jvmti_thread_state= NULL;
1478   _should_post_on_exceptions_flag = JNI_FALSE;
1479   _jvmti_get_loaded_classes_closure = NULL;
1480   _interp_only_mode    = 0;
1481   _special_runtime_exit_condition = _no_async_condition;
1482   _pending_async_exception = NULL;
1483   _thread_stat = NULL;
1484   _thread_stat = new ThreadStatistics();
1485   _blocked_on_compilation = false;
1486   _jni_active_critical = 0;
1487   _pending_jni_exception_check_fn = NULL;
1488   _do_not_unlock_if_synchronized = false;
1489   _cached_monitor_info = NULL;
1490   _parker = Parker::Allocate(this);
1491 
1492 #ifndef PRODUCT
1493   _jmp_ring_index = 0;
1494   for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1495     record_jump(NULL, NULL, NULL, 0);
1496   }
1497 #endif // PRODUCT
1498 
1499   set_thread_profiler(NULL);
1500   if (FlatProfiler::is_active()) {
1501     // This is where we would decide to either give each thread it's own profiler
1502     // or use one global one from FlatProfiler,
1503     // or up to some count of the number of profiled threads, etc.
1504     ThreadProfiler* pp = new ThreadProfiler();
1505     pp->engage();
1506     set_thread_profiler(pp);
1507   }
1508 
1509   // Setup safepoint state info for this thread
1510   ThreadSafepointState::create(this);
1511 
1512   debug_only(_java_call_counter = 0);
1513 
1514   // JVMTI PopFrame support
1515   _popframe_condition = popframe_inactive;
1516   _popframe_preserved_args = NULL;
1517   _popframe_preserved_args_size = 0;
1518   _frames_to_pop_failed_realloc = 0;
1519 
1520   pd_initialize();
1521 }
1522 
1523 #if INCLUDE_ALL_GCS
1524 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1525 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1526 #endif // INCLUDE_ALL_GCS
1527 
1528 JavaThread::JavaThread(bool is_attaching_via_jni) :
1529                        Thread()
1530 #if INCLUDE_ALL_GCS
1531                        , _satb_mark_queue(&_satb_mark_queue_set),
1532                        _dirty_card_queue(&_dirty_card_queue_set)
1533 #endif // INCLUDE_ALL_GCS
1534 {
1535   initialize();
1536   if (is_attaching_via_jni) {
1537     _jni_attach_state = _attaching_via_jni;
1538   } else {
1539     _jni_attach_state = _not_attaching_via_jni;
1540   }
1541   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1542 }
1543 
1544 bool JavaThread::reguard_stack(address cur_sp) {
1545   if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1546       && _stack_guard_state != stack_guard_reserved_disabled) {
1547     return true; // Stack already guarded or guard pages not needed.
1548   }
1549 
1550   if (register_stack_overflow()) {
1551     // For those architectures which have separate register and
1552     // memory stacks, we must check the register stack to see if
1553     // it has overflowed.
1554     return false;
1555   }
1556 
1557   // Java code never executes within the yellow zone: the latter is only
1558   // there to provoke an exception during stack banging.  If java code
1559   // is executing there, either StackShadowPages should be larger, or
1560   // some exception code in c1, c2 or the interpreter isn't unwinding
1561   // when it should.
1562   guarantee(cur_sp > stack_reserved_zone_base(),
1563             "not enough space to reguard - increase StackShadowPages");
1564   if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1565     enable_stack_yellow_reserved_zone();
1566     if (reserved_stack_activation() != stack_base()) {
1567       set_reserved_stack_activation(stack_base());
1568     }
1569   } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1570     set_reserved_stack_activation(stack_base());
1571     enable_stack_reserved_zone();
1572   }
1573   return true;
1574 }
1575 
1576 bool JavaThread::reguard_stack(void) {
1577   return reguard_stack(os::current_stack_pointer());
1578 }
1579 
1580 
1581 void JavaThread::block_if_vm_exited() {
1582   if (_terminated == _vm_exited) {
1583     // _vm_exited is set at safepoint, and Threads_lock is never released
1584     // we will block here forever
1585     Threads_lock->lock_without_safepoint_check();
1586     ShouldNotReachHere();
1587   }
1588 }
1589 
1590 
1591 // Remove this ifdef when C1 is ported to the compiler interface.
1592 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1593 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1594 
1595 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1596                        Thread()
1597 #if INCLUDE_ALL_GCS
1598                        , _satb_mark_queue(&_satb_mark_queue_set),
1599                        _dirty_card_queue(&_dirty_card_queue_set)
1600 #endif // INCLUDE_ALL_GCS
1601 {
1602   initialize();
1603   _jni_attach_state = _not_attaching_via_jni;
1604   set_entry_point(entry_point);
1605   // Create the native thread itself.
1606   // %note runtime_23
1607   os::ThreadType thr_type = os::java_thread;
1608   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1609                                                      os::java_thread;
1610   os::create_thread(this, thr_type, stack_sz);
1611   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1612   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1613   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1614   // the exception consists of creating the exception object & initializing it, initialization
1615   // will leave the VM via a JavaCall and then all locks must be unlocked).
1616   //
1617   // The thread is still suspended when we reach here. Thread must be explicit started
1618   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1619   // by calling Threads:add. The reason why this is not done here, is because the thread
1620   // object must be fully initialized (take a look at JVM_Start)
1621 }
1622 
1623 JavaThread::~JavaThread() {
1624 
1625   // JSR166 -- return the parker to the free list
1626   Parker::Release(_parker);
1627   _parker = NULL;
1628 
1629   // Free any remaining  previous UnrollBlock
1630   vframeArray* old_array = vframe_array_last();
1631 
1632   if (old_array != NULL) {
1633     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1634     old_array->set_unroll_block(NULL);
1635     delete old_info;
1636     delete old_array;
1637   }
1638 
1639   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1640   if (deferred != NULL) {
1641     // This can only happen if thread is destroyed before deoptimization occurs.
1642     assert(deferred->length() != 0, "empty array!");
1643     do {
1644       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1645       deferred->remove_at(0);
1646       // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1647       delete dlv;
1648     } while (deferred->length() != 0);
1649     delete deferred;
1650   }
1651 
1652   // All Java related clean up happens in exit
1653   ThreadSafepointState::destroy(this);
1654   if (_thread_profiler != NULL) delete _thread_profiler;
1655   if (_thread_stat != NULL) delete _thread_stat;
1656 
1657 #if INCLUDE_JVMCI
1658   if (JVMCICounterSize > 0) {
1659     if (jvmci_counters_include(this)) {
1660       for (int i = 0; i < JVMCICounterSize; i++) {
1661         _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1662       }
1663     }
1664     FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1665   }
1666 #endif // INCLUDE_JVMCI
1667 }
1668 
1669 
1670 // The first routine called by a new Java thread
1671 void JavaThread::run() {
1672   // initialize thread-local alloc buffer related fields
1673   this->initialize_tlab();
1674 
1675   // used to test validity of stack trace backs
1676   this->record_base_of_stack_pointer();
1677 
1678   // Record real stack base and size.
1679   this->record_stack_base_and_size();
1680 
1681   this->create_stack_guard_pages();
1682 
1683   this->cache_global_variables();
1684 
1685   // Thread is now sufficient initialized to be handled by the safepoint code as being
1686   // in the VM. Change thread state from _thread_new to _thread_in_vm
1687   ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1688 
1689   assert(JavaThread::current() == this, "sanity check");
1690   assert(!Thread::current()->owns_locks(), "sanity check");
1691 
1692   DTRACE_THREAD_PROBE(start, this);
1693 
1694   // This operation might block. We call that after all safepoint checks for a new thread has
1695   // been completed.
1696   this->set_active_handles(JNIHandleBlock::allocate_block());
1697 
1698   if (JvmtiExport::should_post_thread_life()) {
1699     JvmtiExport::post_thread_start(this);
1700   }
1701 
1702   EventThreadStart event;
1703   if (event.should_commit()) {
1704     event.set_thread(THREAD_TRACE_ID(this));
1705     event.commit();
1706   }
1707 
1708   // We call another function to do the rest so we are sure that the stack addresses used
1709   // from there will be lower than the stack base just computed
1710   thread_main_inner();
1711 
1712   // Note, thread is no longer valid at this point!
1713 }
1714 
1715 
1716 void JavaThread::thread_main_inner() {
1717   assert(JavaThread::current() == this, "sanity check");
1718   assert(this->threadObj() != NULL, "just checking");
1719 
1720   // Execute thread entry point unless this thread has a pending exception
1721   // or has been stopped before starting.
1722   // Note: Due to JVM_StopThread we can have pending exceptions already!
1723   if (!this->has_pending_exception() &&
1724       !java_lang_Thread::is_stillborn(this->threadObj())) {
1725     {
1726       ResourceMark rm(this);
1727       this->set_native_thread_name(this->get_thread_name());
1728     }
1729     HandleMark hm(this);
1730     this->entry_point()(this, this);
1731   }
1732 
1733   DTRACE_THREAD_PROBE(stop, this);
1734 
1735   this->exit(false);
1736   delete this;
1737 }
1738 
1739 
1740 static void ensure_join(JavaThread* thread) {
1741   // We do not need to grap the Threads_lock, since we are operating on ourself.
1742   Handle threadObj(thread, thread->threadObj());
1743   assert(threadObj.not_null(), "java thread object must exist");
1744   ObjectLocker lock(threadObj, thread);
1745   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1746   thread->clear_pending_exception();
1747   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1748   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1749   // Clear the native thread instance - this makes isAlive return false and allows the join()
1750   // to complete once we've done the notify_all below
1751   java_lang_Thread::set_thread(threadObj(), NULL);
1752   lock.notify_all(thread);
1753   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1754   thread->clear_pending_exception();
1755 }
1756 
1757 
1758 // For any new cleanup additions, please check to see if they need to be applied to
1759 // cleanup_failed_attach_current_thread as well.
1760 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1761   assert(this == JavaThread::current(), "thread consistency check");
1762 
1763   HandleMark hm(this);
1764   Handle uncaught_exception(this, this->pending_exception());
1765   this->clear_pending_exception();
1766   Handle threadObj(this, this->threadObj());
1767   assert(threadObj.not_null(), "Java thread object should be created");
1768 
1769   if (get_thread_profiler() != NULL) {
1770     get_thread_profiler()->disengage();
1771     ResourceMark rm;
1772     get_thread_profiler()->print(get_thread_name());
1773   }
1774 
1775 
1776   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1777   {
1778     EXCEPTION_MARK;
1779 
1780     CLEAR_PENDING_EXCEPTION;
1781   }
1782   if (!destroy_vm) {
1783     if (uncaught_exception.not_null()) {
1784       EXCEPTION_MARK;
1785       // Call method Thread.dispatchUncaughtException().
1786       Klass* thread_klass = SystemDictionary::Thread_klass();
1787       JavaValue result(T_VOID);
1788       JavaCalls::call_virtual(&result,
1789                               threadObj, thread_klass,
1790                               vmSymbols::dispatchUncaughtException_name(),
1791                               vmSymbols::throwable_void_signature(),
1792                               uncaught_exception,
1793                               THREAD);
1794       if (HAS_PENDING_EXCEPTION) {
1795         ResourceMark rm(this);
1796         jio_fprintf(defaultStream::error_stream(),
1797                     "\nException: %s thrown from the UncaughtExceptionHandler"
1798                     " in thread \"%s\"\n",
1799                     pending_exception()->klass()->external_name(),
1800                     get_thread_name());
1801         CLEAR_PENDING_EXCEPTION;
1802       }
1803     }
1804 
1805     // Called before the java thread exit since we want to read info
1806     // from java_lang_Thread object
1807     EventThreadEnd event;
1808     if (event.should_commit()) {
1809       event.set_thread(THREAD_TRACE_ID(this));
1810       event.commit();
1811     }
1812 
1813     // Call after last event on thread
1814     EVENT_THREAD_EXIT(this);
1815 
1816     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1817     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1818     // is deprecated anyhow.
1819     if (!is_Compiler_thread()) {
1820       int count = 3;
1821       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1822         EXCEPTION_MARK;
1823         JavaValue result(T_VOID);
1824         Klass* thread_klass = SystemDictionary::Thread_klass();
1825         JavaCalls::call_virtual(&result,
1826                                 threadObj, thread_klass,
1827                                 vmSymbols::exit_method_name(),
1828                                 vmSymbols::void_method_signature(),
1829                                 THREAD);
1830         CLEAR_PENDING_EXCEPTION;
1831       }
1832     }
1833     // notify JVMTI
1834     if (JvmtiExport::should_post_thread_life()) {
1835       JvmtiExport::post_thread_end(this);
1836     }
1837 
1838     // We have notified the agents that we are exiting, before we go on,
1839     // we must check for a pending external suspend request and honor it
1840     // in order to not surprise the thread that made the suspend request.
1841     while (true) {
1842       {
1843         MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1844         if (!is_external_suspend()) {
1845           set_terminated(_thread_exiting);
1846           ThreadService::current_thread_exiting(this);
1847           break;
1848         }
1849         // Implied else:
1850         // Things get a little tricky here. We have a pending external
1851         // suspend request, but we are holding the SR_lock so we
1852         // can't just self-suspend. So we temporarily drop the lock
1853         // and then self-suspend.
1854       }
1855 
1856       ThreadBlockInVM tbivm(this);
1857       java_suspend_self();
1858 
1859       // We're done with this suspend request, but we have to loop around
1860       // and check again. Eventually we will get SR_lock without a pending
1861       // external suspend request and will be able to mark ourselves as
1862       // exiting.
1863     }
1864     // no more external suspends are allowed at this point
1865   } else {
1866     // before_exit() has already posted JVMTI THREAD_END events
1867   }
1868 
1869   // Notify waiters on thread object. This has to be done after exit() is called
1870   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1871   // group should have the destroyed bit set before waiters are notified).
1872   ensure_join(this);
1873   assert(!this->has_pending_exception(), "ensure_join should have cleared");
1874 
1875   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1876   // held by this thread must be released. The spec does not distinguish
1877   // between JNI-acquired and regular Java monitors. We can only see
1878   // regular Java monitors here if monitor enter-exit matching is broken.
1879   //
1880   // Optionally release any monitors for regular JavaThread exits. This
1881   // is provided as a work around for any bugs in monitor enter-exit
1882   // matching. This can be expensive so it is not enabled by default.
1883   //
1884   // ensure_join() ignores IllegalThreadStateExceptions, and so does
1885   // ObjectSynchronizer::release_monitors_owned_by_thread().
1886   if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1887     // Sanity check even though JNI DetachCurrentThread() would have
1888     // returned JNI_ERR if there was a Java frame. JavaThread exit
1889     // should be done executing Java code by the time we get here.
1890     assert(!this->has_last_Java_frame(),
1891            "should not have a Java frame when detaching or exiting");
1892     ObjectSynchronizer::release_monitors_owned_by_thread(this);
1893     assert(!this->has_pending_exception(), "release_monitors should have cleared");
1894   }
1895 
1896   // These things needs to be done while we are still a Java Thread. Make sure that thread
1897   // is in a consistent state, in case GC happens
1898   assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1899 
1900   if (active_handles() != NULL) {
1901     JNIHandleBlock* block = active_handles();
1902     set_active_handles(NULL);
1903     JNIHandleBlock::release_block(block);
1904   }
1905 
1906   if (free_handle_block() != NULL) {
1907     JNIHandleBlock* block = free_handle_block();
1908     set_free_handle_block(NULL);
1909     JNIHandleBlock::release_block(block);
1910   }
1911 
1912   // These have to be removed while this is still a valid thread.
1913   remove_stack_guard_pages();
1914 
1915   if (UseTLAB) {
1916     tlab().make_parsable(true);  // retire TLAB
1917   }
1918 
1919   if (JvmtiEnv::environments_might_exist()) {
1920     JvmtiExport::cleanup_thread(this);
1921   }
1922 
1923   // We must flush any deferred card marks before removing a thread from
1924   // the list of active threads.
1925   Universe::heap()->flush_deferred_store_barrier(this);
1926   assert(deferred_card_mark().is_empty(), "Should have been flushed");
1927 
1928 #if INCLUDE_ALL_GCS
1929   // We must flush the G1-related buffers before removing a thread
1930   // from the list of active threads. We must do this after any deferred
1931   // card marks have been flushed (above) so that any entries that are
1932   // added to the thread's dirty card queue as a result are not lost.
1933   if (UseG1GC) {
1934     flush_barrier_queues();
1935   }
1936 #endif // INCLUDE_ALL_GCS
1937 
1938   log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
1939     exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
1940     os::current_thread_id());
1941 
1942   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1943   Threads::remove(this);
1944 }
1945 
1946 #if INCLUDE_ALL_GCS
1947 // Flush G1-related queues.
1948 void JavaThread::flush_barrier_queues() {
1949   satb_mark_queue().flush();
1950   dirty_card_queue().flush();
1951 }
1952 
1953 void JavaThread::initialize_queues() {
1954   assert(!SafepointSynchronize::is_at_safepoint(),
1955          "we should not be at a safepoint");
1956 
1957   SATBMarkQueue& satb_queue = satb_mark_queue();
1958   SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1959   // The SATB queue should have been constructed with its active
1960   // field set to false.
1961   assert(!satb_queue.is_active(), "SATB queue should not be active");
1962   assert(satb_queue.is_empty(), "SATB queue should be empty");
1963   // If we are creating the thread during a marking cycle, we should
1964   // set the active field of the SATB queue to true.
1965   if (satb_queue_set.is_active()) {
1966     satb_queue.set_active(true);
1967   }
1968 
1969   DirtyCardQueue& dirty_queue = dirty_card_queue();
1970   // The dirty card queue should have been constructed with its
1971   // active field set to true.
1972   assert(dirty_queue.is_active(), "dirty card queue should be active");
1973 }
1974 #endif // INCLUDE_ALL_GCS
1975 
1976 void JavaThread::cleanup_failed_attach_current_thread() {
1977   if (get_thread_profiler() != NULL) {
1978     get_thread_profiler()->disengage();
1979     ResourceMark rm;
1980     get_thread_profiler()->print(get_thread_name());
1981   }
1982 
1983   if (active_handles() != NULL) {
1984     JNIHandleBlock* block = active_handles();
1985     set_active_handles(NULL);
1986     JNIHandleBlock::release_block(block);
1987   }
1988 
1989   if (free_handle_block() != NULL) {
1990     JNIHandleBlock* block = free_handle_block();
1991     set_free_handle_block(NULL);
1992     JNIHandleBlock::release_block(block);
1993   }
1994 
1995   // These have to be removed while this is still a valid thread.
1996   remove_stack_guard_pages();
1997 
1998   if (UseTLAB) {
1999     tlab().make_parsable(true);  // retire TLAB, if any
2000   }
2001 
2002 #if INCLUDE_ALL_GCS
2003   if (UseG1GC) {
2004     flush_barrier_queues();
2005   }
2006 #endif // INCLUDE_ALL_GCS
2007 
2008   Threads::remove(this);
2009   delete this;
2010 }
2011 
2012 
2013 
2014 
2015 JavaThread* JavaThread::active() {
2016   Thread* thread = Thread::current();
2017   if (thread->is_Java_thread()) {
2018     return (JavaThread*) thread;
2019   } else {
2020     assert(thread->is_VM_thread(), "this must be a vm thread");
2021     VM_Operation* op = ((VMThread*) thread)->vm_operation();
2022     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2023     assert(ret->is_Java_thread(), "must be a Java thread");
2024     return ret;
2025   }
2026 }
2027 
2028 bool JavaThread::is_lock_owned(address adr) const {
2029   if (Thread::is_lock_owned(adr)) return true;
2030 
2031   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2032     if (chunk->contains(adr)) return true;
2033   }
2034 
2035   return false;
2036 }
2037 
2038 
2039 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2040   chunk->set_next(monitor_chunks());
2041   set_monitor_chunks(chunk);
2042 }
2043 
2044 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2045   guarantee(monitor_chunks() != NULL, "must be non empty");
2046   if (monitor_chunks() == chunk) {
2047     set_monitor_chunks(chunk->next());
2048   } else {
2049     MonitorChunk* prev = monitor_chunks();
2050     while (prev->next() != chunk) prev = prev->next();
2051     prev->set_next(chunk->next());
2052   }
2053 }
2054 
2055 // JVM support.
2056 
2057 // Note: this function shouldn't block if it's called in
2058 // _thread_in_native_trans state (such as from
2059 // check_special_condition_for_native_trans()).
2060 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2061 
2062   if (has_last_Java_frame() && has_async_condition()) {
2063     // If we are at a polling page safepoint (not a poll return)
2064     // then we must defer async exception because live registers
2065     // will be clobbered by the exception path. Poll return is
2066     // ok because the call we a returning from already collides
2067     // with exception handling registers and so there is no issue.
2068     // (The exception handling path kills call result registers but
2069     //  this is ok since the exception kills the result anyway).
2070 
2071     if (is_at_poll_safepoint()) {
2072       // if the code we are returning to has deoptimized we must defer
2073       // the exception otherwise live registers get clobbered on the
2074       // exception path before deoptimization is able to retrieve them.
2075       //
2076       RegisterMap map(this, false);
2077       frame caller_fr = last_frame().sender(&map);
2078       assert(caller_fr.is_compiled_frame(), "what?");
2079       if (caller_fr.is_deoptimized_frame()) {
2080         log_info(exceptions)("deferred async exception at compiled safepoint");
2081         return;
2082       }
2083     }
2084   }
2085 
2086   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2087   if (condition == _no_async_condition) {
2088     // Conditions have changed since has_special_runtime_exit_condition()
2089     // was called:
2090     // - if we were here only because of an external suspend request,
2091     //   then that was taken care of above (or cancelled) so we are done
2092     // - if we were here because of another async request, then it has
2093     //   been cleared between the has_special_runtime_exit_condition()
2094     //   and now so again we are done
2095     return;
2096   }
2097 
2098   // Check for pending async. exception
2099   if (_pending_async_exception != NULL) {
2100     // Only overwrite an already pending exception, if it is not a threadDeath.
2101     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2102 
2103       // We cannot call Exceptions::_throw(...) here because we cannot block
2104       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2105 
2106       if (log_is_enabled(Info, exceptions)) {
2107         ResourceMark rm;
2108         outputStream* logstream = Log(exceptions)::info_stream();
2109         logstream->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2110           if (has_last_Java_frame()) {
2111             frame f = last_frame();
2112            logstream->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2113           }
2114         logstream->print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2115       }
2116       _pending_async_exception = NULL;
2117       clear_has_async_exception();
2118     }
2119   }
2120 
2121   if (check_unsafe_error &&
2122       condition == _async_unsafe_access_error && !has_pending_exception()) {
2123     condition = _no_async_condition;  // done
2124     switch (thread_state()) {
2125     case _thread_in_vm: {
2126       JavaThread* THREAD = this;
2127       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2128     }
2129     case _thread_in_native: {
2130       ThreadInVMfromNative tiv(this);
2131       JavaThread* THREAD = this;
2132       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2133     }
2134     case _thread_in_Java: {
2135       ThreadInVMfromJava tiv(this);
2136       JavaThread* THREAD = this;
2137       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2138     }
2139     default:
2140       ShouldNotReachHere();
2141     }
2142   }
2143 
2144   assert(condition == _no_async_condition || has_pending_exception() ||
2145          (!check_unsafe_error && condition == _async_unsafe_access_error),
2146          "must have handled the async condition, if no exception");
2147 }
2148 
2149 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2150   //
2151   // Check for pending external suspend. Internal suspend requests do
2152   // not use handle_special_runtime_exit_condition().
2153   // If JNIEnv proxies are allowed, don't self-suspend if the target
2154   // thread is not the current thread. In older versions of jdbx, jdbx
2155   // threads could call into the VM with another thread's JNIEnv so we
2156   // can be here operating on behalf of a suspended thread (4432884).
2157   bool do_self_suspend = is_external_suspend_with_lock();
2158   if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2159     //
2160     // Because thread is external suspended the safepoint code will count
2161     // thread as at a safepoint. This can be odd because we can be here
2162     // as _thread_in_Java which would normally transition to _thread_blocked
2163     // at a safepoint. We would like to mark the thread as _thread_blocked
2164     // before calling java_suspend_self like all other callers of it but
2165     // we must then observe proper safepoint protocol. (We can't leave
2166     // _thread_blocked with a safepoint in progress). However we can be
2167     // here as _thread_in_native_trans so we can't use a normal transition
2168     // constructor/destructor pair because they assert on that type of
2169     // transition. We could do something like:
2170     //
2171     // JavaThreadState state = thread_state();
2172     // set_thread_state(_thread_in_vm);
2173     // {
2174     //   ThreadBlockInVM tbivm(this);
2175     //   java_suspend_self()
2176     // }
2177     // set_thread_state(_thread_in_vm_trans);
2178     // if (safepoint) block;
2179     // set_thread_state(state);
2180     //
2181     // but that is pretty messy. Instead we just go with the way the
2182     // code has worked before and note that this is the only path to
2183     // java_suspend_self that doesn't put the thread in _thread_blocked
2184     // mode.
2185 
2186     frame_anchor()->make_walkable(this);
2187     java_suspend_self();
2188 
2189     // We might be here for reasons in addition to the self-suspend request
2190     // so check for other async requests.
2191   }
2192 
2193   if (check_asyncs) {
2194     check_and_handle_async_exceptions();
2195   }
2196 }
2197 
2198 void JavaThread::send_thread_stop(oop java_throwable)  {
2199   assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2200   assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2201   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2202 
2203   // Do not throw asynchronous exceptions against the compiler thread
2204   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2205   if (!can_call_java()) return;
2206 
2207   {
2208     // Actually throw the Throwable against the target Thread - however
2209     // only if there is no thread death exception installed already.
2210     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2211       // If the topmost frame is a runtime stub, then we are calling into
2212       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2213       // must deoptimize the caller before continuing, as the compiled  exception handler table
2214       // may not be valid
2215       if (has_last_Java_frame()) {
2216         frame f = last_frame();
2217         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2218           // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2219           RegisterMap reg_map(this, UseBiasedLocking);
2220           frame compiled_frame = f.sender(&reg_map);
2221           if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2222             Deoptimization::deoptimize(this, compiled_frame, &reg_map);
2223           }
2224         }
2225       }
2226 
2227       // Set async. pending exception in thread.
2228       set_pending_async_exception(java_throwable);
2229 
2230       if (log_is_enabled(Info, exceptions)) {
2231          ResourceMark rm;
2232         log_info(exceptions)("Pending Async. exception installed of type: %s",
2233                              InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2234       }
2235       // for AbortVMOnException flag
2236       Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2237     }
2238   }
2239 
2240 
2241   // Interrupt thread so it will wake up from a potential wait()
2242   Thread::interrupt(this);
2243 }
2244 
2245 // External suspension mechanism.
2246 //
2247 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2248 // to any VM_locks and it is at a transition
2249 // Self-suspension will happen on the transition out of the vm.
2250 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2251 //
2252 // Guarantees on return:
2253 //   + Target thread will not execute any new bytecode (that's why we need to
2254 //     force a safepoint)
2255 //   + Target thread will not enter any new monitors
2256 //
2257 void JavaThread::java_suspend() {
2258   { MutexLocker mu(Threads_lock);
2259     if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2260       return;
2261     }
2262   }
2263 
2264   { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2265     if (!is_external_suspend()) {
2266       // a racing resume has cancelled us; bail out now
2267       return;
2268     }
2269 
2270     // suspend is done
2271     uint32_t debug_bits = 0;
2272     // Warning: is_ext_suspend_completed() may temporarily drop the
2273     // SR_lock to allow the thread to reach a stable thread state if
2274     // it is currently in a transient thread state.
2275     if (is_ext_suspend_completed(false /* !called_by_wait */,
2276                                  SuspendRetryDelay, &debug_bits)) {
2277       return;
2278     }
2279   }
2280 
2281   VM_ThreadSuspend vm_suspend;
2282   VMThread::execute(&vm_suspend);
2283 }
2284 
2285 // Part II of external suspension.
2286 // A JavaThread self suspends when it detects a pending external suspend
2287 // request. This is usually on transitions. It is also done in places
2288 // where continuing to the next transition would surprise the caller,
2289 // e.g., monitor entry.
2290 //
2291 // Returns the number of times that the thread self-suspended.
2292 //
2293 // Note: DO NOT call java_suspend_self() when you just want to block current
2294 //       thread. java_suspend_self() is the second stage of cooperative
2295 //       suspension for external suspend requests and should only be used
2296 //       to complete an external suspend request.
2297 //
2298 int JavaThread::java_suspend_self() {
2299   int ret = 0;
2300 
2301   // we are in the process of exiting so don't suspend
2302   if (is_exiting()) {
2303     clear_external_suspend();
2304     return ret;
2305   }
2306 
2307   assert(_anchor.walkable() ||
2308          (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2309          "must have walkable stack");
2310 
2311   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2312 
2313   assert(!this->is_ext_suspended(),
2314          "a thread trying to self-suspend should not already be suspended");
2315 
2316   if (this->is_suspend_equivalent()) {
2317     // If we are self-suspending as a result of the lifting of a
2318     // suspend equivalent condition, then the suspend_equivalent
2319     // flag is not cleared until we set the ext_suspended flag so
2320     // that wait_for_ext_suspend_completion() returns consistent
2321     // results.
2322     this->clear_suspend_equivalent();
2323   }
2324 
2325   // A racing resume may have cancelled us before we grabbed SR_lock
2326   // above. Or another external suspend request could be waiting for us
2327   // by the time we return from SR_lock()->wait(). The thread
2328   // that requested the suspension may already be trying to walk our
2329   // stack and if we return now, we can change the stack out from under
2330   // it. This would be a "bad thing (TM)" and cause the stack walker
2331   // to crash. We stay self-suspended until there are no more pending
2332   // external suspend requests.
2333   while (is_external_suspend()) {
2334     ret++;
2335     this->set_ext_suspended();
2336 
2337     // _ext_suspended flag is cleared by java_resume()
2338     while (is_ext_suspended()) {
2339       this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2340     }
2341   }
2342 
2343   return ret;
2344 }
2345 
2346 #ifdef ASSERT
2347 // verify the JavaThread has not yet been published in the Threads::list, and
2348 // hence doesn't need protection from concurrent access at this stage
2349 void JavaThread::verify_not_published() {
2350   if (!Threads_lock->owned_by_self()) {
2351     MutexLockerEx ml(Threads_lock,  Mutex::_no_safepoint_check_flag);
2352     assert(!Threads::includes(this),
2353            "java thread shouldn't have been published yet!");
2354   } else {
2355     assert(!Threads::includes(this),
2356            "java thread shouldn't have been published yet!");
2357   }
2358 }
2359 #endif
2360 
2361 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2362 // progress or when _suspend_flags is non-zero.
2363 // Current thread needs to self-suspend if there is a suspend request and/or
2364 // block if a safepoint is in progress.
2365 // Async exception ISN'T checked.
2366 // Note only the ThreadInVMfromNative transition can call this function
2367 // directly and when thread state is _thread_in_native_trans
2368 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2369   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2370 
2371   JavaThread *curJT = JavaThread::current();
2372   bool do_self_suspend = thread->is_external_suspend();
2373 
2374   assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2375 
2376   // If JNIEnv proxies are allowed, don't self-suspend if the target
2377   // thread is not the current thread. In older versions of jdbx, jdbx
2378   // threads could call into the VM with another thread's JNIEnv so we
2379   // can be here operating on behalf of a suspended thread (4432884).
2380   if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2381     JavaThreadState state = thread->thread_state();
2382 
2383     // We mark this thread_blocked state as a suspend-equivalent so
2384     // that a caller to is_ext_suspend_completed() won't be confused.
2385     // The suspend-equivalent state is cleared by java_suspend_self().
2386     thread->set_suspend_equivalent();
2387 
2388     // If the safepoint code sees the _thread_in_native_trans state, it will
2389     // wait until the thread changes to other thread state. There is no
2390     // guarantee on how soon we can obtain the SR_lock and complete the
2391     // self-suspend request. It would be a bad idea to let safepoint wait for
2392     // too long. Temporarily change the state to _thread_blocked to
2393     // let the VM thread know that this thread is ready for GC. The problem
2394     // of changing thread state is that safepoint could happen just after
2395     // java_suspend_self() returns after being resumed, and VM thread will
2396     // see the _thread_blocked state. We must check for safepoint
2397     // after restoring the state and make sure we won't leave while a safepoint
2398     // is in progress.
2399     thread->set_thread_state(_thread_blocked);
2400     thread->java_suspend_self();
2401     thread->set_thread_state(state);
2402 
2403     InterfaceSupport::serialize_thread_state_with_handler(thread);
2404   }
2405 
2406   if (SafepointSynchronize::do_call_back()) {
2407     // If we are safepointing, then block the caller which may not be
2408     // the same as the target thread (see above).
2409     SafepointSynchronize::block(curJT);
2410   }
2411 
2412   if (thread->is_deopt_suspend()) {
2413     thread->clear_deopt_suspend();
2414     RegisterMap map(thread, false);
2415     frame f = thread->last_frame();
2416     while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2417       f = f.sender(&map);
2418     }
2419     if (f.id() == thread->must_deopt_id()) {
2420       thread->clear_must_deopt_id();
2421       f.deoptimize(thread);
2422     } else {
2423       fatal("missed deoptimization!");
2424     }
2425   }
2426 }
2427 
2428 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2429 // progress or when _suspend_flags is non-zero.
2430 // Current thread needs to self-suspend if there is a suspend request and/or
2431 // block if a safepoint is in progress.
2432 // Also check for pending async exception (not including unsafe access error).
2433 // Note only the native==>VM/Java barriers can call this function and when
2434 // thread state is _thread_in_native_trans.
2435 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2436   check_safepoint_and_suspend_for_native_trans(thread);
2437 
2438   if (thread->has_async_exception()) {
2439     // We are in _thread_in_native_trans state, don't handle unsafe
2440     // access error since that may block.
2441     thread->check_and_handle_async_exceptions(false);
2442   }
2443 }
2444 
2445 // This is a variant of the normal
2446 // check_special_condition_for_native_trans with slightly different
2447 // semantics for use by critical native wrappers.  It does all the
2448 // normal checks but also performs the transition back into
2449 // thread_in_Java state.  This is required so that critical natives
2450 // can potentially block and perform a GC if they are the last thread
2451 // exiting the GCLocker.
2452 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2453   check_special_condition_for_native_trans(thread);
2454 
2455   // Finish the transition
2456   thread->set_thread_state(_thread_in_Java);
2457 
2458   if (thread->do_critical_native_unlock()) {
2459     ThreadInVMfromJavaNoAsyncException tiv(thread);
2460     GCLocker::unlock_critical(thread);
2461     thread->clear_critical_native_unlock();
2462   }
2463 }
2464 
2465 // We need to guarantee the Threads_lock here, since resumes are not
2466 // allowed during safepoint synchronization
2467 // Can only resume from an external suspension
2468 void JavaThread::java_resume() {
2469   assert_locked_or_safepoint(Threads_lock);
2470 
2471   // Sanity check: thread is gone, has started exiting or the thread
2472   // was not externally suspended.
2473   if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2474     return;
2475   }
2476 
2477   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2478 
2479   clear_external_suspend();
2480 
2481   if (is_ext_suspended()) {
2482     clear_ext_suspended();
2483     SR_lock()->notify_all();
2484   }
2485 }
2486 
2487 size_t JavaThread::_stack_red_zone_size = 0;
2488 size_t JavaThread::_stack_yellow_zone_size = 0;
2489 size_t JavaThread::_stack_reserved_zone_size = 0;
2490 size_t JavaThread::_stack_shadow_zone_size = 0;
2491 
2492 void JavaThread::create_stack_guard_pages() {
2493   if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; }
2494   address low_addr = stack_end();
2495   size_t len = stack_guard_zone_size();
2496 
2497   int must_commit = os::must_commit_stack_guard_pages();
2498   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2499 
2500   if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2501     log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2502     return;
2503   }
2504 
2505   if (os::guard_memory((char *) low_addr, len)) {
2506     _stack_guard_state = stack_guard_enabled;
2507   } else {
2508     log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2509       PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2510     if (os::uncommit_memory((char *) low_addr, len)) {
2511       log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2512     }
2513     return;
2514   }
2515 
2516   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2517     PTR_FORMAT "-" PTR_FORMAT ".",
2518     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2519 }
2520 
2521 void JavaThread::remove_stack_guard_pages() {
2522   assert(Thread::current() == this, "from different thread");
2523   if (_stack_guard_state == stack_guard_unused) return;
2524   address low_addr = stack_end();
2525   size_t len = stack_guard_zone_size();
2526 
2527   if (os::must_commit_stack_guard_pages()) {
2528     if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2529       _stack_guard_state = stack_guard_unused;
2530     } else {
2531       log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2532         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2533       return;
2534     }
2535   } else {
2536     if (_stack_guard_state == stack_guard_unused) return;
2537     if (os::unguard_memory((char *) low_addr, len)) {
2538       _stack_guard_state = stack_guard_unused;
2539     } else {
2540       log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2541         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2542       return;
2543     }
2544   }
2545 
2546   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2547     PTR_FORMAT "-" PTR_FORMAT ".",
2548     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2549 }
2550 
2551 void JavaThread::enable_stack_reserved_zone() {
2552   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2553   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2554 
2555   // The base notation is from the stack's point of view, growing downward.
2556   // We need to adjust it to work correctly with guard_memory()
2557   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2558 
2559   guarantee(base < stack_base(),"Error calculating stack reserved zone");
2560   guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2561 
2562   if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2563     _stack_guard_state = stack_guard_enabled;
2564   } else {
2565     warning("Attempt to guard stack reserved zone failed.");
2566   }
2567   enable_register_stack_guard();
2568 }
2569 
2570 void JavaThread::disable_stack_reserved_zone() {
2571   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2572   assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2573 
2574   // Simply return if called for a thread that does not use guard pages.
2575   if (_stack_guard_state == stack_guard_unused) return;
2576 
2577   // The base notation is from the stack's point of view, growing downward.
2578   // We need to adjust it to work correctly with guard_memory()
2579   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2580 
2581   if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2582     _stack_guard_state = stack_guard_reserved_disabled;
2583   } else {
2584     warning("Attempt to unguard stack reserved zone failed.");
2585   }
2586   disable_register_stack_guard();
2587 }
2588 
2589 void JavaThread::enable_stack_yellow_reserved_zone() {
2590   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2591   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2592 
2593   // The base notation is from the stacks point of view, growing downward.
2594   // We need to adjust it to work correctly with guard_memory()
2595   address base = stack_red_zone_base();
2596 
2597   guarantee(base < stack_base(), "Error calculating stack yellow zone");
2598   guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2599 
2600   if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2601     _stack_guard_state = stack_guard_enabled;
2602   } else {
2603     warning("Attempt to guard stack yellow zone failed.");
2604   }
2605   enable_register_stack_guard();
2606 }
2607 
2608 void JavaThread::disable_stack_yellow_reserved_zone() {
2609   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2610   assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2611 
2612   // Simply return if called for a thread that does not use guard pages.
2613   if (_stack_guard_state == stack_guard_unused) return;
2614 
2615   // The base notation is from the stacks point of view, growing downward.
2616   // We need to adjust it to work correctly with guard_memory()
2617   address base = stack_red_zone_base();
2618 
2619   if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2620     _stack_guard_state = stack_guard_yellow_reserved_disabled;
2621   } else {
2622     warning("Attempt to unguard stack yellow zone failed.");
2623   }
2624   disable_register_stack_guard();
2625 }
2626 
2627 void JavaThread::enable_stack_red_zone() {
2628   // The base notation is from the stacks point of view, growing downward.
2629   // We need to adjust it to work correctly with guard_memory()
2630   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2631   address base = stack_red_zone_base() - stack_red_zone_size();
2632 
2633   guarantee(base < stack_base(), "Error calculating stack red zone");
2634   guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2635 
2636   if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2637     warning("Attempt to guard stack red zone failed.");
2638   }
2639 }
2640 
2641 void JavaThread::disable_stack_red_zone() {
2642   // The base notation is from the stacks point of view, growing downward.
2643   // We need to adjust it to work correctly with guard_memory()
2644   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2645   address base = stack_red_zone_base() - stack_red_zone_size();
2646   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2647     warning("Attempt to unguard stack red zone failed.");
2648   }
2649 }
2650 
2651 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2652   // ignore is there is no stack
2653   if (!has_last_Java_frame()) return;
2654   // traverse the stack frames. Starts from top frame.
2655   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2656     frame* fr = fst.current();
2657     f(fr, fst.register_map());
2658   }
2659 }
2660 
2661 
2662 #ifndef PRODUCT
2663 // Deoptimization
2664 // Function for testing deoptimization
2665 void JavaThread::deoptimize() {
2666   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2667   StackFrameStream fst(this, UseBiasedLocking);
2668   bool deopt = false;           // Dump stack only if a deopt actually happens.
2669   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2670   // Iterate over all frames in the thread and deoptimize
2671   for (; !fst.is_done(); fst.next()) {
2672     if (fst.current()->can_be_deoptimized()) {
2673 
2674       if (only_at) {
2675         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
2676         // consists of comma or carriage return separated numbers so
2677         // search for the current bci in that string.
2678         address pc = fst.current()->pc();
2679         nmethod* nm =  (nmethod*) fst.current()->cb();
2680         ScopeDesc* sd = nm->scope_desc_at(pc);
2681         char buffer[8];
2682         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2683         size_t len = strlen(buffer);
2684         const char * found = strstr(DeoptimizeOnlyAt, buffer);
2685         while (found != NULL) {
2686           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2687               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2688             // Check that the bci found is bracketed by terminators.
2689             break;
2690           }
2691           found = strstr(found + 1, buffer);
2692         }
2693         if (!found) {
2694           continue;
2695         }
2696       }
2697 
2698       if (DebugDeoptimization && !deopt) {
2699         deopt = true; // One-time only print before deopt
2700         tty->print_cr("[BEFORE Deoptimization]");
2701         trace_frames();
2702         trace_stack();
2703       }
2704       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2705     }
2706   }
2707 
2708   if (DebugDeoptimization && deopt) {
2709     tty->print_cr("[AFTER Deoptimization]");
2710     trace_frames();
2711   }
2712 }
2713 
2714 
2715 // Make zombies
2716 void JavaThread::make_zombies() {
2717   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2718     if (fst.current()->can_be_deoptimized()) {
2719       // it is a Java nmethod
2720       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2721       nm->make_not_entrant();
2722     }
2723   }
2724 }
2725 #endif // PRODUCT
2726 
2727 
2728 void JavaThread::deoptimized_wrt_marked_nmethods() {
2729   if (!has_last_Java_frame()) return;
2730   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2731   StackFrameStream fst(this, UseBiasedLocking);
2732   for (; !fst.is_done(); fst.next()) {
2733     if (fst.current()->should_be_deoptimized()) {
2734       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2735     }
2736   }
2737 }
2738 
2739 
2740 // If the caller is a NamedThread, then remember, in the current scope,
2741 // the given JavaThread in its _processed_thread field.
2742 class RememberProcessedThread: public StackObj {
2743   NamedThread* _cur_thr;
2744  public:
2745   RememberProcessedThread(JavaThread* jthr) {
2746     Thread* thread = Thread::current();
2747     if (thread->is_Named_thread()) {
2748       _cur_thr = (NamedThread *)thread;
2749       _cur_thr->set_processed_thread(jthr);
2750     } else {
2751       _cur_thr = NULL;
2752     }
2753   }
2754 
2755   ~RememberProcessedThread() {
2756     if (_cur_thr) {
2757       _cur_thr->set_processed_thread(NULL);
2758     }
2759   }
2760 };
2761 
2762 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2763   // Verify that the deferred card marks have been flushed.
2764   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2765 
2766   // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2767   // since there may be more than one thread using each ThreadProfiler.
2768 
2769   // Traverse the GCHandles
2770   Thread::oops_do(f, cf);
2771 
2772   JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2773 
2774   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2775          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2776 
2777   if (has_last_Java_frame()) {
2778     // Record JavaThread to GC thread
2779     RememberProcessedThread rpt(this);
2780 
2781     // Traverse the privileged stack
2782     if (_privileged_stack_top != NULL) {
2783       _privileged_stack_top->oops_do(f);
2784     }
2785 
2786     // traverse the registered growable array
2787     if (_array_for_gc != NULL) {
2788       for (int index = 0; index < _array_for_gc->length(); index++) {
2789         f->do_oop(_array_for_gc->adr_at(index));
2790       }
2791     }
2792 
2793     // Traverse the monitor chunks
2794     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2795       chunk->oops_do(f);
2796     }
2797 
2798     // Traverse the execution stack
2799     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2800       fst.current()->oops_do(f, cf, fst.register_map());
2801     }
2802   }
2803 
2804   // callee_target is never live across a gc point so NULL it here should
2805   // it still contain a methdOop.
2806 
2807   set_callee_target(NULL);
2808 
2809   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2810   // If we have deferred set_locals there might be oops waiting to be
2811   // written
2812   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2813   if (list != NULL) {
2814     for (int i = 0; i < list->length(); i++) {
2815       list->at(i)->oops_do(f);
2816     }
2817   }
2818 
2819   // Traverse instance variables at the end since the GC may be moving things
2820   // around using this function
2821   f->do_oop((oop*) &_threadObj);
2822   f->do_oop((oop*) &_vm_result);
2823   f->do_oop((oop*) &_exception_oop);
2824   f->do_oop((oop*) &_pending_async_exception);
2825 
2826   if (jvmti_thread_state() != NULL) {
2827     jvmti_thread_state()->oops_do(f);
2828   }
2829 }
2830 
2831 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2832   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2833          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2834 
2835   if (has_last_Java_frame()) {
2836     // Traverse the execution stack
2837     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2838       fst.current()->nmethods_do(cf);
2839     }
2840   }
2841 }
2842 
2843 void JavaThread::metadata_do(void f(Metadata*)) {
2844   if (has_last_Java_frame()) {
2845     // Traverse the execution stack to call f() on the methods in the stack
2846     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2847       fst.current()->metadata_do(f);
2848     }
2849   } else if (is_Compiler_thread()) {
2850     // need to walk ciMetadata in current compile tasks to keep alive.
2851     CompilerThread* ct = (CompilerThread*)this;
2852     if (ct->env() != NULL) {
2853       ct->env()->metadata_do(f);
2854     }
2855     if (ct->task() != NULL) {
2856       ct->task()->metadata_do(f);
2857     }
2858   }
2859 }
2860 
2861 // Printing
2862 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2863   switch (_thread_state) {
2864   case _thread_uninitialized:     return "_thread_uninitialized";
2865   case _thread_new:               return "_thread_new";
2866   case _thread_new_trans:         return "_thread_new_trans";
2867   case _thread_in_native:         return "_thread_in_native";
2868   case _thread_in_native_trans:   return "_thread_in_native_trans";
2869   case _thread_in_vm:             return "_thread_in_vm";
2870   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
2871   case _thread_in_Java:           return "_thread_in_Java";
2872   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
2873   case _thread_blocked:           return "_thread_blocked";
2874   case _thread_blocked_trans:     return "_thread_blocked_trans";
2875   default:                        return "unknown thread state";
2876   }
2877 }
2878 
2879 #ifndef PRODUCT
2880 void JavaThread::print_thread_state_on(outputStream *st) const {
2881   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
2882 };
2883 void JavaThread::print_thread_state() const {
2884   print_thread_state_on(tty);
2885 }
2886 #endif // PRODUCT
2887 
2888 // Called by Threads::print() for VM_PrintThreads operation
2889 void JavaThread::print_on(outputStream *st) const {
2890   st->print_raw("\"");
2891   st->print_raw(get_thread_name());
2892   st->print_raw("\" ");
2893   oop thread_oop = threadObj();
2894   if (thread_oop != NULL) {
2895     st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2896     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
2897     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2898   }
2899   Thread::print_on(st);
2900   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2901   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2902   if (thread_oop != NULL) {
2903     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2904   }
2905 #ifndef PRODUCT
2906   print_thread_state_on(st);
2907   _safepoint_state->print_on(st);
2908 #endif // PRODUCT
2909   if (is_Compiler_thread()) {
2910     CompilerThread* ct = (CompilerThread*)this;
2911     if (ct->task() != NULL) {
2912       st->print("   Compiling: ");
2913       ct->task()->print(st, NULL, true, false);
2914     } else {
2915       st->print("   No compile task");
2916     }
2917     st->cr();
2918   }
2919 }
2920 
2921 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2922   st->print("%s", get_thread_name_string(buf, buflen));
2923 }
2924 
2925 // Called by fatal error handler. The difference between this and
2926 // JavaThread::print() is that we can't grab lock or allocate memory.
2927 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2928   st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2929   oop thread_obj = threadObj();
2930   if (thread_obj != NULL) {
2931     if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2932   }
2933   st->print(" [");
2934   st->print("%s", _get_thread_state_name(_thread_state));
2935   if (osthread()) {
2936     st->print(", id=%d", osthread()->thread_id());
2937   }
2938   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2939             p2i(stack_end()), p2i(stack_base()));
2940   st->print("]");
2941   return;
2942 }
2943 
2944 // Verification
2945 
2946 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2947 
2948 void JavaThread::verify() {
2949   // Verify oops in the thread.
2950   oops_do(&VerifyOopClosure::verify_oop, NULL);
2951 
2952   // Verify the stack frames.
2953   frames_do(frame_verify);
2954 }
2955 
2956 // CR 6300358 (sub-CR 2137150)
2957 // Most callers of this method assume that it can't return NULL but a
2958 // thread may not have a name whilst it is in the process of attaching to
2959 // the VM - see CR 6412693, and there are places where a JavaThread can be
2960 // seen prior to having it's threadObj set (eg JNI attaching threads and
2961 // if vm exit occurs during initialization). These cases can all be accounted
2962 // for such that this method never returns NULL.
2963 const char* JavaThread::get_thread_name() const {
2964 #ifdef ASSERT
2965   // early safepoints can hit while current thread does not yet have TLS
2966   if (!SafepointSynchronize::is_at_safepoint()) {
2967     Thread *cur = Thread::current();
2968     if (!(cur->is_Java_thread() && cur == this)) {
2969       // Current JavaThreads are allowed to get their own name without
2970       // the Threads_lock.
2971       assert_locked_or_safepoint(Threads_lock);
2972     }
2973   }
2974 #endif // ASSERT
2975   return get_thread_name_string();
2976 }
2977 
2978 // Returns a non-NULL representation of this thread's name, or a suitable
2979 // descriptive string if there is no set name
2980 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2981   const char* name_str;
2982   oop thread_obj = threadObj();
2983   if (thread_obj != NULL) {
2984     oop name = java_lang_Thread::name(thread_obj);
2985     if (name != NULL) {
2986       if (buf == NULL) {
2987         name_str = java_lang_String::as_utf8_string(name);
2988       } else {
2989         name_str = java_lang_String::as_utf8_string(name, buf, buflen);
2990       }
2991     } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
2992       name_str = "<no-name - thread is attaching>";
2993     } else {
2994       name_str = Thread::name();
2995     }
2996   } else {
2997     name_str = Thread::name();
2998   }
2999   assert(name_str != NULL, "unexpected NULL thread name");
3000   return name_str;
3001 }
3002 
3003 
3004 const char* JavaThread::get_threadgroup_name() const {
3005   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3006   oop thread_obj = threadObj();
3007   if (thread_obj != NULL) {
3008     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3009     if (thread_group != NULL) {
3010       // ThreadGroup.name can be null
3011       return java_lang_ThreadGroup::name(thread_group);
3012     }
3013   }
3014   return NULL;
3015 }
3016 
3017 const char* JavaThread::get_parent_name() const {
3018   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3019   oop thread_obj = threadObj();
3020   if (thread_obj != NULL) {
3021     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3022     if (thread_group != NULL) {
3023       oop parent = java_lang_ThreadGroup::parent(thread_group);
3024       if (parent != NULL) {
3025         // ThreadGroup.name can be null
3026         return java_lang_ThreadGroup::name(parent);
3027       }
3028     }
3029   }
3030   return NULL;
3031 }
3032 
3033 ThreadPriority JavaThread::java_priority() const {
3034   oop thr_oop = threadObj();
3035   if (thr_oop == NULL) return NormPriority; // Bootstrapping
3036   ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3037   assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3038   return priority;
3039 }
3040 
3041 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3042 
3043   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3044   // Link Java Thread object <-> C++ Thread
3045 
3046   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3047   // and put it into a new Handle.  The Handle "thread_oop" can then
3048   // be used to pass the C++ thread object to other methods.
3049 
3050   // Set the Java level thread object (jthread) field of the
3051   // new thread (a JavaThread *) to C++ thread object using the
3052   // "thread_oop" handle.
3053 
3054   // Set the thread field (a JavaThread *) of the
3055   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3056 
3057   Handle thread_oop(Thread::current(),
3058                     JNIHandles::resolve_non_null(jni_thread));
3059   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3060          "must be initialized");
3061   set_threadObj(thread_oop());
3062   java_lang_Thread::set_thread(thread_oop(), this);
3063 
3064   if (prio == NoPriority) {
3065     prio = java_lang_Thread::priority(thread_oop());
3066     assert(prio != NoPriority, "A valid priority should be present");
3067   }
3068 
3069   // Push the Java priority down to the native thread; needs Threads_lock
3070   Thread::set_priority(this, prio);
3071 
3072   prepare_ext();
3073 
3074   // Add the new thread to the Threads list and set it in motion.
3075   // We must have threads lock in order to call Threads::add.
3076   // It is crucial that we do not block before the thread is
3077   // added to the Threads list for if a GC happens, then the java_thread oop
3078   // will not be visited by GC.
3079   Threads::add(this);
3080 }
3081 
3082 oop JavaThread::current_park_blocker() {
3083   // Support for JSR-166 locks
3084   oop thread_oop = threadObj();
3085   if (thread_oop != NULL &&
3086       JDK_Version::current().supports_thread_park_blocker()) {
3087     return java_lang_Thread::park_blocker(thread_oop);
3088   }
3089   return NULL;
3090 }
3091 
3092 
3093 void JavaThread::print_stack_on(outputStream* st) {
3094   if (!has_last_Java_frame()) return;
3095   ResourceMark rm;
3096   HandleMark   hm;
3097 
3098   RegisterMap reg_map(this);
3099   vframe* start_vf = last_java_vframe(&reg_map);
3100   int count = 0;
3101   for (vframe* f = start_vf; f; f = f->sender()) {
3102     if (f->is_java_frame()) {
3103       javaVFrame* jvf = javaVFrame::cast(f);
3104       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3105 
3106       // Print out lock information
3107       if (JavaMonitorsInStackTrace) {
3108         jvf->print_lock_info_on(st, count);
3109       }
3110     } else {
3111       // Ignore non-Java frames
3112     }
3113 
3114     // Bail-out case for too deep stacks
3115     count++;
3116     if (MaxJavaStackTraceDepth == count) return;
3117   }
3118 }
3119 
3120 
3121 // JVMTI PopFrame support
3122 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3123   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3124   if (in_bytes(size_in_bytes) != 0) {
3125     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3126     _popframe_preserved_args_size = in_bytes(size_in_bytes);
3127     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3128   }
3129 }
3130 
3131 void* JavaThread::popframe_preserved_args() {
3132   return _popframe_preserved_args;
3133 }
3134 
3135 ByteSize JavaThread::popframe_preserved_args_size() {
3136   return in_ByteSize(_popframe_preserved_args_size);
3137 }
3138 
3139 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3140   int sz = in_bytes(popframe_preserved_args_size());
3141   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3142   return in_WordSize(sz / wordSize);
3143 }
3144 
3145 void JavaThread::popframe_free_preserved_args() {
3146   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3147   FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3148   _popframe_preserved_args = NULL;
3149   _popframe_preserved_args_size = 0;
3150 }
3151 
3152 #ifndef PRODUCT
3153 
3154 void JavaThread::trace_frames() {
3155   tty->print_cr("[Describe stack]");
3156   int frame_no = 1;
3157   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3158     tty->print("  %d. ", frame_no++);
3159     fst.current()->print_value_on(tty, this);
3160     tty->cr();
3161   }
3162 }
3163 
3164 class PrintAndVerifyOopClosure: public OopClosure {
3165  protected:
3166   template <class T> inline void do_oop_work(T* p) {
3167     oop obj = oopDesc::load_decode_heap_oop(p);
3168     if (obj == NULL) return;
3169     tty->print(INTPTR_FORMAT ": ", p2i(p));
3170     if (obj->is_oop_or_null()) {
3171       if (obj->is_objArray()) {
3172         tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3173       } else {
3174         obj->print();
3175       }
3176     } else {
3177       tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3178     }
3179     tty->cr();
3180   }
3181  public:
3182   virtual void do_oop(oop* p) { do_oop_work(p); }
3183   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
3184 };
3185 
3186 
3187 static void oops_print(frame* f, const RegisterMap *map) {
3188   PrintAndVerifyOopClosure print;
3189   f->print_value();
3190   f->oops_do(&print, NULL, (RegisterMap*)map);
3191 }
3192 
3193 // Print our all the locations that contain oops and whether they are
3194 // valid or not.  This useful when trying to find the oldest frame
3195 // where an oop has gone bad since the frame walk is from youngest to
3196 // oldest.
3197 void JavaThread::trace_oops() {
3198   tty->print_cr("[Trace oops]");
3199   frames_do(oops_print);
3200 }
3201 
3202 
3203 #ifdef ASSERT
3204 // Print or validate the layout of stack frames
3205 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3206   ResourceMark rm;
3207   PRESERVE_EXCEPTION_MARK;
3208   FrameValues values;
3209   int frame_no = 0;
3210   for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3211     fst.current()->describe(values, ++frame_no);
3212     if (depth == frame_no) break;
3213   }
3214   if (validate_only) {
3215     values.validate();
3216   } else {
3217     tty->print_cr("[Describe stack layout]");
3218     values.print(this);
3219   }
3220 }
3221 #endif
3222 
3223 void JavaThread::trace_stack_from(vframe* start_vf) {
3224   ResourceMark rm;
3225   int vframe_no = 1;
3226   for (vframe* f = start_vf; f; f = f->sender()) {
3227     if (f->is_java_frame()) {
3228       javaVFrame::cast(f)->print_activation(vframe_no++);
3229     } else {
3230       f->print();
3231     }
3232     if (vframe_no > StackPrintLimit) {
3233       tty->print_cr("...<more frames>...");
3234       return;
3235     }
3236   }
3237 }
3238 
3239 
3240 void JavaThread::trace_stack() {
3241   if (!has_last_Java_frame()) return;
3242   ResourceMark rm;
3243   HandleMark   hm;
3244   RegisterMap reg_map(this);
3245   trace_stack_from(last_java_vframe(&reg_map));
3246 }
3247 
3248 
3249 #endif // PRODUCT
3250 
3251 
3252 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3253   assert(reg_map != NULL, "a map must be given");
3254   frame f = last_frame();
3255   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3256     if (vf->is_java_frame()) return javaVFrame::cast(vf);
3257   }
3258   return NULL;
3259 }
3260 
3261 
3262 Klass* JavaThread::security_get_caller_class(int depth) {
3263   vframeStream vfst(this);
3264   vfst.security_get_caller_frame(depth);
3265   if (!vfst.at_end()) {
3266     return vfst.method()->method_holder();
3267   }
3268   return NULL;
3269 }
3270 
3271 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3272   assert(thread->is_Compiler_thread(), "must be compiler thread");
3273   CompileBroker::compiler_thread_loop();
3274 }
3275 
3276 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3277   NMethodSweeper::sweeper_loop();
3278 }
3279 
3280 // Create a CompilerThread
3281 CompilerThread::CompilerThread(CompileQueue* queue,
3282                                CompilerCounters* counters)
3283                                : JavaThread(&compiler_thread_entry) {
3284   _env   = NULL;
3285   _log   = NULL;
3286   _task  = NULL;
3287   _queue = queue;
3288   _counters = counters;
3289   _buffer_blob = NULL;
3290   _compiler = NULL;
3291 
3292 #ifndef PRODUCT
3293   _ideal_graph_printer = NULL;
3294 #endif
3295 }
3296 
3297 bool CompilerThread::can_call_java() const {
3298   return _compiler != NULL && _compiler->is_jvmci();
3299 }
3300 
3301 // Create sweeper thread
3302 CodeCacheSweeperThread::CodeCacheSweeperThread()
3303 : JavaThread(&sweeper_thread_entry) {
3304   _scanned_compiled_method = NULL;
3305 }
3306 
3307 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3308   JavaThread::oops_do(f, cf);
3309   if (_scanned_compiled_method != NULL && cf != NULL) {
3310     // Safepoints can occur when the sweeper is scanning an nmethod so
3311     // process it here to make sure it isn't unloaded in the middle of
3312     // a scan.
3313     cf->do_code_blob(_scanned_compiled_method);
3314   }
3315 }
3316 
3317 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3318   JavaThread::nmethods_do(cf);
3319   if (_scanned_compiled_method != NULL && cf != NULL) {
3320     // Safepoints can occur when the sweeper is scanning an nmethod so
3321     // process it here to make sure it isn't unloaded in the middle of
3322     // a scan.
3323     cf->do_code_blob(_scanned_compiled_method);
3324   }
3325 }
3326 
3327 
3328 // ======= Threads ========
3329 
3330 // The Threads class links together all active threads, and provides
3331 // operations over all threads.  It is protected by its own Mutex
3332 // lock, which is also used in other contexts to protect thread
3333 // operations from having the thread being operated on from exiting
3334 // and going away unexpectedly (e.g., safepoint synchronization)
3335 
3336 JavaThread* Threads::_thread_list = NULL;
3337 int         Threads::_number_of_threads = 0;
3338 int         Threads::_number_of_non_daemon_threads = 0;
3339 int         Threads::_return_code = 0;
3340 int         Threads::_thread_claim_parity = 0;
3341 size_t      JavaThread::_stack_size_at_create = 0;
3342 #ifdef ASSERT
3343 bool        Threads::_vm_complete = false;
3344 #endif
3345 
3346 // All JavaThreads
3347 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3348 
3349 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3350 void Threads::threads_do(ThreadClosure* tc) {
3351   assert_locked_or_safepoint(Threads_lock);
3352   // ALL_JAVA_THREADS iterates through all JavaThreads
3353   ALL_JAVA_THREADS(p) {
3354     tc->do_thread(p);
3355   }
3356   // Someday we could have a table or list of all non-JavaThreads.
3357   // For now, just manually iterate through them.
3358   tc->do_thread(VMThread::vm_thread());
3359   Universe::heap()->gc_threads_do(tc);
3360   WatcherThread *wt = WatcherThread::watcher_thread();
3361   // Strictly speaking, the following NULL check isn't sufficient to make sure
3362   // the data for WatcherThread is still valid upon being examined. However,
3363   // considering that WatchThread terminates when the VM is on the way to
3364   // exit at safepoint, the chance of the above is extremely small. The right
3365   // way to prevent termination of WatcherThread would be to acquire
3366   // Terminator_lock, but we can't do that without violating the lock rank
3367   // checking in some cases.
3368   if (wt != NULL) {
3369     tc->do_thread(wt);
3370   }
3371 
3372   // If CompilerThreads ever become non-JavaThreads, add them here
3373 }
3374 
3375 // The system initialization in the library has three phases.
3376 //
3377 // Phase 1: java.lang.System class initialization
3378 //     java.lang.System is a primordial class loaded and initialized
3379 //     by the VM early during startup.  java.lang.System.<clinit>
3380 //     only does registerNatives and keeps the rest of the class
3381 //     initialization work later until thread initialization completes.
3382 //
3383 //     System.initPhase1 initializes the system properties, the static
3384 //     fields in, out, and err. Set up java signal handlers, OS-specific
3385 //     system settings, and thread group of the main thread.
3386 static void call_initPhase1(TRAPS) {
3387   Klass* klass =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3388   JavaValue result(T_VOID);
3389   JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3390                                          vmSymbols::void_method_signature(), CHECK);
3391 }
3392 
3393 // Phase 2. Module system initialization
3394 //     This will initialize the module system.  Only java.base classes
3395 //     can be loaded until phase 2 completes.
3396 //
3397 //     Call System.initPhase2 after the compiler initialization and jsr292
3398 //     classes get initialized because module initialization runs a lot of java
3399 //     code, that for performance reasons, should be compiled.  Also, this will
3400 //     enable the startup code to use lambda and other language features in this
3401 //     phase and onward.
3402 //
3403 //     After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3404 static void call_initPhase2(TRAPS) {
3405   TraceTime timer("Phase2 initialization", TRACETIME_LOG(Info, module, startuptime));
3406 
3407   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3408 
3409   JavaValue result(T_INT);
3410   JavaCallArguments args;
3411   args.push_int(DisplayVMOutputToStderr);
3412   args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3413   JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3414                                          vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3415   if (result.get_jint() != JNI_OK) {
3416     vm_exit_during_initialization(); // no message or exception
3417   }
3418 
3419   universe_post_module_init();
3420 }
3421 
3422 // Phase 3. final setup - set security manager, system class loader and TCCL
3423 //
3424 //     This will instantiate and set the security manager, set the system class
3425 //     loader as well as the thread context class loader.  The security manager
3426 //     and system class loader may be a custom class loaded from -Xbootclasspath/a,
3427 //     other modules or the application's classpath.
3428 static void call_initPhase3(TRAPS) {
3429   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3430   JavaValue result(T_VOID);
3431   JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3432                                          vmSymbols::void_method_signature(), CHECK);
3433 }
3434 
3435 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3436   TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3437 
3438   if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3439     create_vm_init_libraries();
3440   }
3441 
3442   initialize_class(vmSymbols::java_lang_String(), CHECK);
3443 
3444   // Inject CompactStrings value after the static initializers for String ran.
3445   java_lang_String::set_compact_strings(CompactStrings);
3446 
3447   // Initialize java_lang.System (needed before creating the thread)
3448   initialize_class(vmSymbols::java_lang_System(), CHECK);
3449   // The VM creates & returns objects of this class. Make sure it's initialized.
3450   initialize_class(vmSymbols::java_lang_Class(), CHECK);
3451   initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3452   Handle thread_group = create_initial_thread_group(CHECK);
3453   Universe::set_main_thread_group(thread_group());
3454   initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3455   oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3456   main_thread->set_threadObj(thread_object);
3457   // Set thread status to running since main thread has
3458   // been started and running.
3459   java_lang_Thread::set_thread_status(thread_object,
3460                                       java_lang_Thread::RUNNABLE);
3461 
3462   // The VM creates objects of this class.
3463   initialize_class(vmSymbols::java_lang_Module(), CHECK);
3464 
3465   // The VM preresolves methods to these classes. Make sure that they get initialized
3466   initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3467   initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3468 
3469   // Phase 1 of the system initialization in the library, java.lang.System class initialization
3470   call_initPhase1(CHECK);
3471 
3472   // get the Java runtime name after java.lang.System is initialized
3473   JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3474   JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3475 
3476   // an instance of OutOfMemory exception has been allocated earlier
3477   initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3478   initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3479   initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3480   initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3481   initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3482   initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3483   initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3484   initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3485 }
3486 
3487 void Threads::initialize_jsr292_core_classes(TRAPS) {
3488   TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3489 
3490   initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3491   initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3492   initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3493   initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3494 }
3495 
3496 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3497   extern void JDK_Version_init();
3498 
3499   // Preinitialize version info.
3500   VM_Version::early_initialize();
3501 
3502   // Check version
3503   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3504 
3505   // Initialize library-based TLS
3506   ThreadLocalStorage::init();
3507 
3508   // Initialize the output stream module
3509   ostream_init();
3510 
3511   // Process java launcher properties.
3512   Arguments::process_sun_java_launcher_properties(args);
3513 
3514   // Initialize the os module
3515   os::init();
3516 
3517   // Record VM creation timing statistics
3518   TraceVmCreationTime create_vm_timer;
3519   create_vm_timer.start();
3520 
3521   // Initialize system properties.
3522   Arguments::init_system_properties();
3523 
3524   // So that JDK version can be used as a discriminator when parsing arguments
3525   JDK_Version_init();
3526 
3527   // Update/Initialize System properties after JDK version number is known
3528   Arguments::init_version_specific_system_properties();
3529 
3530   // Make sure to initialize log configuration *before* parsing arguments
3531   LogConfiguration::initialize(create_vm_timer.begin_time());
3532 
3533   // Parse arguments
3534   jint parse_result = Arguments::parse(args);
3535   if (parse_result != JNI_OK) return parse_result;
3536 
3537   os::init_before_ergo();
3538 
3539   jint ergo_result = Arguments::apply_ergo();
3540   if (ergo_result != JNI_OK) return ergo_result;
3541 
3542   // Final check of all ranges after ergonomics which may change values.
3543   if (!CommandLineFlagRangeList::check_ranges()) {
3544     return JNI_EINVAL;
3545   }
3546 
3547   // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3548   bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3549   if (!constraint_result) {
3550     return JNI_EINVAL;
3551   }
3552 
3553   CommandLineFlagWriteableList::mark_startup();
3554 
3555   if (PauseAtStartup) {
3556     os::pause();
3557   }
3558 
3559   HOTSPOT_VM_INIT_BEGIN();
3560 
3561   // Timing (must come after argument parsing)
3562   TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3563 
3564   // Initialize the os module after parsing the args
3565   jint os_init_2_result = os::init_2();
3566   if (os_init_2_result != JNI_OK) return os_init_2_result;
3567 
3568   jint adjust_after_os_result = Arguments::adjust_after_os();
3569   if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3570 
3571   // Initialize output stream logging
3572   ostream_init_log();
3573 
3574   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3575   // Must be before create_vm_init_agents()
3576   if (Arguments::init_libraries_at_startup()) {
3577     convert_vm_init_libraries_to_agents();
3578   }
3579 
3580   // Launch -agentlib/-agentpath and converted -Xrun agents
3581   if (Arguments::init_agents_at_startup()) {
3582     create_vm_init_agents();
3583   }
3584 
3585   // Initialize Threads state
3586   _thread_list = NULL;
3587   _number_of_threads = 0;
3588   _number_of_non_daemon_threads = 0;
3589 
3590   // Initialize global data structures and create system classes in heap
3591   vm_init_globals();
3592 
3593 #if INCLUDE_JVMCI
3594   if (JVMCICounterSize > 0) {
3595     JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3596     memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3597   } else {
3598     JavaThread::_jvmci_old_thread_counters = NULL;
3599   }
3600 #endif // INCLUDE_JVMCI
3601 
3602   // Attach the main thread to this os thread
3603   JavaThread* main_thread = new JavaThread();
3604   main_thread->set_thread_state(_thread_in_vm);
3605   main_thread->initialize_thread_current();
3606   // must do this before set_active_handles
3607   main_thread->record_stack_base_and_size();
3608   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3609 
3610   if (!main_thread->set_as_starting_thread()) {
3611     vm_shutdown_during_initialization(
3612                                       "Failed necessary internal allocation. Out of swap space");
3613     delete main_thread;
3614     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3615     return JNI_ENOMEM;
3616   }
3617 
3618   // Enable guard page *after* os::create_main_thread(), otherwise it would
3619   // crash Linux VM, see notes in os_linux.cpp.
3620   main_thread->create_stack_guard_pages();
3621 
3622   // Initialize Java-Level synchronization subsystem
3623   ObjectMonitor::Initialize();
3624 
3625   // Initialize global modules
3626   jint status = init_globals();
3627   if (status != JNI_OK) {
3628     delete main_thread;
3629     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3630     return status;
3631   }
3632 
3633   if (TRACE_INITIALIZE() != JNI_OK) {
3634     vm_exit_during_initialization("Failed to initialize tracing backend");
3635   }
3636 
3637   // Should be done after the heap is fully created
3638   main_thread->cache_global_variables();
3639 
3640   HandleMark hm;
3641 
3642   { MutexLocker mu(Threads_lock);
3643     Threads::add(main_thread);
3644   }
3645 
3646   // Any JVMTI raw monitors entered in onload will transition into
3647   // real raw monitor. VM is setup enough here for raw monitor enter.
3648   JvmtiExport::transition_pending_onload_raw_monitors();
3649 
3650   // Create the VMThread
3651   { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3652 
3653   VMThread::create();
3654     Thread* vmthread = VMThread::vm_thread();
3655 
3656     if (!os::create_thread(vmthread, os::vm_thread)) {
3657       vm_exit_during_initialization("Cannot create VM thread. "
3658                                     "Out of system resources.");
3659     }
3660 
3661     // Wait for the VM thread to become ready, and VMThread::run to initialize
3662     // Monitors can have spurious returns, must always check another state flag
3663     {
3664       MutexLocker ml(Notify_lock);
3665       os::start_thread(vmthread);
3666       while (vmthread->active_handles() == NULL) {
3667         Notify_lock->wait();
3668       }
3669     }
3670   }
3671 
3672   assert(Universe::is_fully_initialized(), "not initialized");
3673   if (VerifyDuringStartup) {
3674     // Make sure we're starting with a clean slate.
3675     VM_Verify verify_op;
3676     VMThread::execute(&verify_op);
3677   }
3678 
3679   Thread* THREAD = Thread::current();
3680 
3681   // At this point, the Universe is initialized, but we have not executed
3682   // any byte code.  Now is a good time (the only time) to dump out the
3683   // internal state of the JVM for sharing.
3684   if (DumpSharedSpaces) {
3685     MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3686     ShouldNotReachHere();
3687   }
3688 
3689   // Always call even when there are not JVMTI environments yet, since environments
3690   // may be attached late and JVMTI must track phases of VM execution
3691   JvmtiExport::enter_early_start_phase();
3692 
3693   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3694   JvmtiExport::post_early_vm_start();
3695 
3696   initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3697 
3698   // We need this for ClassDataSharing - the initial vm.info property is set
3699   // with the default value of CDS "sharing" which may be reset through
3700   // command line options.
3701   reset_vm_info_property(CHECK_JNI_ERR);
3702 
3703   quicken_jni_functions();
3704 
3705   // No more stub generation allowed after that point.
3706   StubCodeDesc::freeze();
3707 
3708   // Set flag that basic initialization has completed. Used by exceptions and various
3709   // debug stuff, that does not work until all basic classes have been initialized.
3710   set_init_completed();
3711 
3712   LogConfiguration::post_initialize();
3713   Metaspace::post_initialize();
3714 
3715   HOTSPOT_VM_INIT_END();
3716 
3717   // record VM initialization completion time
3718 #if INCLUDE_MANAGEMENT
3719   Management::record_vm_init_completed();
3720 #endif // INCLUDE_MANAGEMENT
3721 
3722   // Signal Dispatcher needs to be started before VMInit event is posted
3723   os::signal_init(CHECK_JNI_ERR);
3724 
3725   // Start Attach Listener if +StartAttachListener or it can't be started lazily
3726   if (!DisableAttachMechanism) {
3727     AttachListener::vm_start();
3728     if (StartAttachListener || AttachListener::init_at_startup()) {
3729       AttachListener::init();
3730     }
3731   }
3732 
3733   // Launch -Xrun agents
3734   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3735   // back-end can launch with -Xdebug -Xrunjdwp.
3736   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3737     create_vm_init_libraries();
3738   }
3739 
3740   if (CleanChunkPoolAsync) {
3741     Chunk::start_chunk_pool_cleaner_task();
3742   }
3743 
3744   // initialize compiler(s)
3745 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI
3746   CompileBroker::compilation_init(CHECK_JNI_ERR);
3747 #endif
3748 
3749   // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3750   // It is done after compilers are initialized, because otherwise compilations of
3751   // signature polymorphic MH intrinsics can be missed
3752   // (see SystemDictionary::find_method_handle_intrinsic).
3753   initialize_jsr292_core_classes(CHECK_JNI_ERR);
3754 
3755   // This will initialize the module system.  Only java.base classes can be
3756   // loaded until phase 2 completes
3757   call_initPhase2(CHECK_JNI_ERR);
3758 
3759   // Always call even when there are not JVMTI environments yet, since environments
3760   // may be attached late and JVMTI must track phases of VM execution
3761   JvmtiExport::enter_start_phase();
3762 
3763   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3764   JvmtiExport::post_vm_start();
3765 
3766   // Final system initialization including security manager and system class loader
3767   call_initPhase3(CHECK_JNI_ERR);
3768 
3769   // cache the system class loader
3770   SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR));
3771 
3772 #if INCLUDE_JVMCI
3773   if (EnableJVMCI) {
3774     // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled.
3775     // The JVMCI Java initialization code will read this flag and
3776     // do the printing if it's set.
3777     bool init = JVMCIPrintProperties;
3778 
3779     if (!init) {
3780       // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3781       // compilations via JVMCI will not actually block until JVMCI is initialized.
3782       init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3783     }
3784 
3785     if (init) {
3786       JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3787     }
3788   }
3789 #endif
3790 
3791   // Always call even when there are not JVMTI environments yet, since environments
3792   // may be attached late and JVMTI must track phases of VM execution
3793   JvmtiExport::enter_live_phase();
3794 
3795   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3796   JvmtiExport::post_vm_initialized();
3797 
3798   if (TRACE_START() != JNI_OK) {
3799     vm_exit_during_initialization("Failed to start tracing backend.");
3800   }
3801 
3802 #if INCLUDE_MANAGEMENT
3803   Management::initialize(THREAD);
3804 
3805   if (HAS_PENDING_EXCEPTION) {
3806     // management agent fails to start possibly due to
3807     // configuration problem and is responsible for printing
3808     // stack trace if appropriate. Simply exit VM.
3809     vm_exit(1);
3810   }
3811 #endif // INCLUDE_MANAGEMENT
3812 
3813   if (Arguments::has_profile())       FlatProfiler::engage(main_thread, true);
3814   if (MemProfiling)                   MemProfiler::engage();
3815   StatSampler::engage();
3816   if (CheckJNICalls)                  JniPeriodicChecker::engage();
3817 
3818   BiasedLocking::init();
3819 
3820 #if INCLUDE_RTM_OPT
3821   RTMLockingCounters::init();
3822 #endif
3823 
3824   if (JDK_Version::current().post_vm_init_hook_enabled()) {
3825     call_postVMInitHook(THREAD);
3826     // The Java side of PostVMInitHook.run must deal with all
3827     // exceptions and provide means of diagnosis.
3828     if (HAS_PENDING_EXCEPTION) {
3829       CLEAR_PENDING_EXCEPTION;
3830     }
3831   }
3832 
3833   {
3834     MutexLocker ml(PeriodicTask_lock);
3835     // Make sure the WatcherThread can be started by WatcherThread::start()
3836     // or by dynamic enrollment.
3837     WatcherThread::make_startable();
3838     // Start up the WatcherThread if there are any periodic tasks
3839     // NOTE:  All PeriodicTasks should be registered by now. If they
3840     //   aren't, late joiners might appear to start slowly (we might
3841     //   take a while to process their first tick).
3842     if (PeriodicTask::num_tasks() > 0) {
3843       WatcherThread::start();
3844     }
3845   }
3846 
3847   create_vm_timer.end();
3848 #ifdef ASSERT
3849   _vm_complete = true;
3850 #endif
3851   return JNI_OK;
3852 }
3853 
3854 // type for the Agent_OnLoad and JVM_OnLoad entry points
3855 extern "C" {
3856   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3857 }
3858 // Find a command line agent library and return its entry point for
3859 //         -agentlib:  -agentpath:   -Xrun
3860 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3861 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3862                                     const char *on_load_symbols[],
3863                                     size_t num_symbol_entries) {
3864   OnLoadEntry_t on_load_entry = NULL;
3865   void *library = NULL;
3866 
3867   if (!agent->valid()) {
3868     char buffer[JVM_MAXPATHLEN];
3869     char ebuf[1024] = "";
3870     const char *name = agent->name();
3871     const char *msg = "Could not find agent library ";
3872 
3873     // First check to see if agent is statically linked into executable
3874     if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3875       library = agent->os_lib();
3876     } else if (agent->is_absolute_path()) {
3877       library = os::dll_load(name, ebuf, sizeof ebuf);
3878       if (library == NULL) {
3879         const char *sub_msg = " in absolute path, with error: ";
3880         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3881         char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3882         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3883         // If we can't find the agent, exit.
3884         vm_exit_during_initialization(buf, NULL);
3885         FREE_C_HEAP_ARRAY(char, buf);
3886       }
3887     } else {
3888       // Try to load the agent from the standard dll directory
3889       if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3890                              name)) {
3891         library = os::dll_load(buffer, ebuf, sizeof ebuf);
3892       }
3893       if (library == NULL) { // Try the local directory
3894         char ns[1] = {0};
3895         if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3896           library = os::dll_load(buffer, ebuf, sizeof ebuf);
3897         }
3898         if (library == NULL) {
3899           const char *sub_msg = " on the library path, with error: ";
3900           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3901           char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3902           jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3903           // If we can't find the agent, exit.
3904           vm_exit_during_initialization(buf, NULL);
3905           FREE_C_HEAP_ARRAY(char, buf);
3906         }
3907       }
3908     }
3909     agent->set_os_lib(library);
3910     agent->set_valid();
3911   }
3912 
3913   // Find the OnLoad function.
3914   on_load_entry =
3915     CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3916                                                           false,
3917                                                           on_load_symbols,
3918                                                           num_symbol_entries));
3919   return on_load_entry;
3920 }
3921 
3922 // Find the JVM_OnLoad entry point
3923 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3924   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3925   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3926 }
3927 
3928 // Find the Agent_OnLoad entry point
3929 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3930   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3931   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3932 }
3933 
3934 // For backwards compatibility with -Xrun
3935 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3936 // treated like -agentpath:
3937 // Must be called before agent libraries are created
3938 void Threads::convert_vm_init_libraries_to_agents() {
3939   AgentLibrary* agent;
3940   AgentLibrary* next;
3941 
3942   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3943     next = agent->next();  // cache the next agent now as this agent may get moved off this list
3944     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3945 
3946     // If there is an JVM_OnLoad function it will get called later,
3947     // otherwise see if there is an Agent_OnLoad
3948     if (on_load_entry == NULL) {
3949       on_load_entry = lookup_agent_on_load(agent);
3950       if (on_load_entry != NULL) {
3951         // switch it to the agent list -- so that Agent_OnLoad will be called,
3952         // JVM_OnLoad won't be attempted and Agent_OnUnload will
3953         Arguments::convert_library_to_agent(agent);
3954       } else {
3955         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3956       }
3957     }
3958   }
3959 }
3960 
3961 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
3962 // Invokes Agent_OnLoad
3963 // Called very early -- before JavaThreads exist
3964 void Threads::create_vm_init_agents() {
3965   extern struct JavaVM_ main_vm;
3966   AgentLibrary* agent;
3967 
3968   JvmtiExport::enter_onload_phase();
3969 
3970   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3971     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
3972 
3973     if (on_load_entry != NULL) {
3974       // Invoke the Agent_OnLoad function
3975       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3976       if (err != JNI_OK) {
3977         vm_exit_during_initialization("agent library failed to init", agent->name());
3978       }
3979     } else {
3980       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3981     }
3982   }
3983   JvmtiExport::enter_primordial_phase();
3984 }
3985 
3986 extern "C" {
3987   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3988 }
3989 
3990 void Threads::shutdown_vm_agents() {
3991   // Send any Agent_OnUnload notifications
3992   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3993   size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
3994   extern struct JavaVM_ main_vm;
3995   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3996 
3997     // Find the Agent_OnUnload function.
3998     Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3999                                                    os::find_agent_function(agent,
4000                                                    false,
4001                                                    on_unload_symbols,
4002                                                    num_symbol_entries));
4003 
4004     // Invoke the Agent_OnUnload function
4005     if (unload_entry != NULL) {
4006       JavaThread* thread = JavaThread::current();
4007       ThreadToNativeFromVM ttn(thread);
4008       HandleMark hm(thread);
4009       (*unload_entry)(&main_vm);
4010     }
4011   }
4012 }
4013 
4014 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4015 // Invokes JVM_OnLoad
4016 void Threads::create_vm_init_libraries() {
4017   extern struct JavaVM_ main_vm;
4018   AgentLibrary* agent;
4019 
4020   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4021     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4022 
4023     if (on_load_entry != NULL) {
4024       // Invoke the JVM_OnLoad function
4025       JavaThread* thread = JavaThread::current();
4026       ThreadToNativeFromVM ttn(thread);
4027       HandleMark hm(thread);
4028       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4029       if (err != JNI_OK) {
4030         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4031       }
4032     } else {
4033       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4034     }
4035   }
4036 }
4037 
4038 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
4039   assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
4040 
4041   JavaThread* java_thread = NULL;
4042   // Sequential search for now.  Need to do better optimization later.
4043   for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
4044     oop tobj = thread->threadObj();
4045     if (!thread->is_exiting() &&
4046         tobj != NULL &&
4047         java_tid == java_lang_Thread::thread_id(tobj)) {
4048       java_thread = thread;
4049       break;
4050     }
4051   }
4052   return java_thread;
4053 }
4054 
4055 
4056 // Last thread running calls java.lang.Shutdown.shutdown()
4057 void JavaThread::invoke_shutdown_hooks() {
4058   HandleMark hm(this);
4059 
4060   // We could get here with a pending exception, if so clear it now.
4061   if (this->has_pending_exception()) {
4062     this->clear_pending_exception();
4063   }
4064 
4065   EXCEPTION_MARK;
4066   Klass* shutdown_klass =
4067     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4068                                       THREAD);
4069   if (shutdown_klass != NULL) {
4070     // SystemDictionary::resolve_or_null will return null if there was
4071     // an exception.  If we cannot load the Shutdown class, just don't
4072     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
4073     // and finalizers (if runFinalizersOnExit is set) won't be run.
4074     // Note that if a shutdown hook was registered or runFinalizersOnExit
4075     // was called, the Shutdown class would have already been loaded
4076     // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4077     JavaValue result(T_VOID);
4078     JavaCalls::call_static(&result,
4079                            shutdown_klass,
4080                            vmSymbols::shutdown_method_name(),
4081                            vmSymbols::void_method_signature(),
4082                            THREAD);
4083   }
4084   CLEAR_PENDING_EXCEPTION;
4085 }
4086 
4087 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4088 // the program falls off the end of main(). Another VM exit path is through
4089 // vm_exit() when the program calls System.exit() to return a value or when
4090 // there is a serious error in VM. The two shutdown paths are not exactly
4091 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4092 // and VM_Exit op at VM level.
4093 //
4094 // Shutdown sequence:
4095 //   + Shutdown native memory tracking if it is on
4096 //   + Wait until we are the last non-daemon thread to execute
4097 //     <-- every thing is still working at this moment -->
4098 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4099 //        shutdown hooks, run finalizers if finalization-on-exit
4100 //   + Call before_exit(), prepare for VM exit
4101 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4102 //        currently the only user of this mechanism is File.deleteOnExit())
4103 //      > stop flat profiler, StatSampler, watcher thread, CMS threads,
4104 //        post thread end and vm death events to JVMTI,
4105 //        stop signal thread
4106 //   + Call JavaThread::exit(), it will:
4107 //      > release JNI handle blocks, remove stack guard pages
4108 //      > remove this thread from Threads list
4109 //     <-- no more Java code from this thread after this point -->
4110 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4111 //     the compiler threads at safepoint
4112 //     <-- do not use anything that could get blocked by Safepoint -->
4113 //   + Disable tracing at JNI/JVM barriers
4114 //   + Set _vm_exited flag for threads that are still running native code
4115 //   + Delete this thread
4116 //   + Call exit_globals()
4117 //      > deletes tty
4118 //      > deletes PerfMemory resources
4119 //   + Return to caller
4120 
4121 bool Threads::destroy_vm() {
4122   JavaThread* thread = JavaThread::current();
4123 
4124 #ifdef ASSERT
4125   _vm_complete = false;
4126 #endif
4127   // Wait until we are the last non-daemon thread to execute
4128   { MutexLocker nu(Threads_lock);
4129     while (Threads::number_of_non_daemon_threads() > 1)
4130       // This wait should make safepoint checks, wait without a timeout,
4131       // and wait as a suspend-equivalent condition.
4132       //
4133       // Note: If the FlatProfiler is running and this thread is waiting
4134       // for another non-daemon thread to finish, then the FlatProfiler
4135       // is waiting for the external suspend request on this thread to
4136       // complete. wait_for_ext_suspend_completion() will eventually
4137       // timeout, but that takes time. Making this wait a suspend-
4138       // equivalent condition solves that timeout problem.
4139       //
4140       Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4141                          Mutex::_as_suspend_equivalent_flag);
4142   }
4143 
4144   // Hang forever on exit if we are reporting an error.
4145   if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4146     os::infinite_sleep();
4147   }
4148   os::wait_for_keypress_at_exit();
4149 
4150   // run Java level shutdown hooks
4151   thread->invoke_shutdown_hooks();
4152 
4153   before_exit(thread);
4154 
4155   thread->exit(true);
4156 
4157   // Stop VM thread.
4158   {
4159     // 4945125 The vm thread comes to a safepoint during exit.
4160     // GC vm_operations can get caught at the safepoint, and the
4161     // heap is unparseable if they are caught. Grab the Heap_lock
4162     // to prevent this. The GC vm_operations will not be able to
4163     // queue until after the vm thread is dead. After this point,
4164     // we'll never emerge out of the safepoint before the VM exits.
4165 
4166     MutexLocker ml(Heap_lock);
4167 
4168     VMThread::wait_for_vm_thread_exit();
4169     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4170     VMThread::destroy();
4171   }
4172 
4173   // clean up ideal graph printers
4174 #if defined(COMPILER2) && !defined(PRODUCT)
4175   IdealGraphPrinter::clean_up();
4176 #endif
4177 
4178   // Now, all Java threads are gone except daemon threads. Daemon threads
4179   // running Java code or in VM are stopped by the Safepoint. However,
4180   // daemon threads executing native code are still running.  But they
4181   // will be stopped at native=>Java/VM barriers. Note that we can't
4182   // simply kill or suspend them, as it is inherently deadlock-prone.
4183 
4184   VM_Exit::set_vm_exited();
4185 
4186   notify_vm_shutdown();
4187 
4188   delete thread;
4189 
4190 #if INCLUDE_JVMCI
4191   if (JVMCICounterSize > 0) {
4192     FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4193   }
4194 #endif
4195 
4196   // exit_globals() will delete tty
4197   exit_globals();
4198 
4199   LogConfiguration::finalize();
4200 
4201   return true;
4202 }
4203 
4204 
4205 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4206   if (version == JNI_VERSION_1_1) return JNI_TRUE;
4207   return is_supported_jni_version(version);
4208 }
4209 
4210 
4211 jboolean Threads::is_supported_jni_version(jint version) {
4212   if (version == JNI_VERSION_1_2) return JNI_TRUE;
4213   if (version == JNI_VERSION_1_4) return JNI_TRUE;
4214   if (version == JNI_VERSION_1_6) return JNI_TRUE;
4215   if (version == JNI_VERSION_1_8) return JNI_TRUE;
4216   if (version == JNI_VERSION_9) return JNI_TRUE;
4217   return JNI_FALSE;
4218 }
4219 
4220 
4221 void Threads::add(JavaThread* p, bool force_daemon) {
4222   // The threads lock must be owned at this point
4223   assert_locked_or_safepoint(Threads_lock);
4224 
4225   // See the comment for this method in thread.hpp for its purpose and
4226   // why it is called here.
4227   p->initialize_queues();
4228   p->set_next(_thread_list);
4229   _thread_list = p;
4230   _number_of_threads++;
4231   oop threadObj = p->threadObj();
4232   bool daemon = true;
4233   // Bootstrapping problem: threadObj can be null for initial
4234   // JavaThread (or for threads attached via JNI)
4235   if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4236     _number_of_non_daemon_threads++;
4237     daemon = false;
4238   }
4239 
4240   ThreadService::add_thread(p, daemon);
4241 
4242   // Possible GC point.
4243   Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4244 }
4245 
4246 void Threads::remove(JavaThread* p) {
4247 
4248   // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
4249   ObjectSynchronizer::omFlush(p);
4250 
4251   // Extra scope needed for Thread_lock, so we can check
4252   // that we do not remove thread without safepoint code notice
4253   { MutexLocker ml(Threads_lock);
4254 
4255     assert(includes(p), "p must be present");
4256 
4257     JavaThread* current = _thread_list;
4258     JavaThread* prev    = NULL;
4259 
4260     while (current != p) {
4261       prev    = current;
4262       current = current->next();
4263     }
4264 
4265     if (prev) {
4266       prev->set_next(current->next());
4267     } else {
4268       _thread_list = p->next();
4269     }
4270     _number_of_threads--;
4271     oop threadObj = p->threadObj();
4272     bool daemon = true;
4273     if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4274       _number_of_non_daemon_threads--;
4275       daemon = false;
4276 
4277       // Only one thread left, do a notify on the Threads_lock so a thread waiting
4278       // on destroy_vm will wake up.
4279       if (number_of_non_daemon_threads() == 1) {
4280         Threads_lock->notify_all();
4281       }
4282     }
4283     ThreadService::remove_thread(p, daemon);
4284 
4285     // Make sure that safepoint code disregard this thread. This is needed since
4286     // the thread might mess around with locks after this point. This can cause it
4287     // to do callbacks into the safepoint code. However, the safepoint code is not aware
4288     // of this thread since it is removed from the queue.
4289     p->set_terminated_value();
4290   } // unlock Threads_lock
4291 
4292   // Since Events::log uses a lock, we grab it outside the Threads_lock
4293   Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4294 }
4295 
4296 // Threads_lock must be held when this is called (or must be called during a safepoint)
4297 bool Threads::includes(JavaThread* p) {
4298   assert(Threads_lock->is_locked(), "sanity check");
4299   ALL_JAVA_THREADS(q) {
4300     if (q == p) {
4301       return true;
4302     }
4303   }
4304   return false;
4305 }
4306 
4307 // Operations on the Threads list for GC.  These are not explicitly locked,
4308 // but the garbage collector must provide a safe context for them to run.
4309 // In particular, these things should never be called when the Threads_lock
4310 // is held by some other thread. (Note: the Safepoint abstraction also
4311 // uses the Threads_lock to guarantee this property. It also makes sure that
4312 // all threads gets blocked when exiting or starting).
4313 
4314 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4315   ALL_JAVA_THREADS(p) {
4316     p->oops_do(f, cf);
4317   }
4318   VMThread::vm_thread()->oops_do(f, cf);
4319 }
4320 
4321 void Threads::change_thread_claim_parity() {
4322   // Set the new claim parity.
4323   assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4324          "Not in range.");
4325   _thread_claim_parity++;
4326   if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4327   assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4328          "Not in range.");
4329 }
4330 
4331 #ifdef ASSERT
4332 void Threads::assert_all_threads_claimed() {
4333   ALL_JAVA_THREADS(p) {
4334     const int thread_parity = p->oops_do_parity();
4335     assert((thread_parity == _thread_claim_parity),
4336            "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4337   }
4338 }
4339 #endif // ASSERT
4340 
4341 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4342   int cp = Threads::thread_claim_parity();
4343   ALL_JAVA_THREADS(p) {
4344     if (p->claim_oops_do(is_par, cp)) {
4345       p->oops_do(f, cf);
4346     }
4347   }
4348   VMThread* vmt = VMThread::vm_thread();
4349   if (vmt->claim_oops_do(is_par, cp)) {
4350     vmt->oops_do(f, cf);
4351   }
4352 }
4353 
4354 #if INCLUDE_ALL_GCS
4355 // Used by ParallelScavenge
4356 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4357   ALL_JAVA_THREADS(p) {
4358     q->enqueue(new ThreadRootsTask(p));
4359   }
4360   q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4361 }
4362 
4363 // Used by Parallel Old
4364 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4365   ALL_JAVA_THREADS(p) {
4366     q->enqueue(new ThreadRootsMarkingTask(p));
4367   }
4368   q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4369 }
4370 #endif // INCLUDE_ALL_GCS
4371 
4372 void Threads::nmethods_do(CodeBlobClosure* cf) {
4373   ALL_JAVA_THREADS(p) {
4374     // This is used by the code cache sweeper to mark nmethods that are active
4375     // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4376     // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4377     if(!p->is_Code_cache_sweeper_thread()) {
4378       p->nmethods_do(cf);
4379     }
4380   }
4381 }
4382 
4383 void Threads::metadata_do(void f(Metadata*)) {
4384   ALL_JAVA_THREADS(p) {
4385     p->metadata_do(f);
4386   }
4387 }
4388 
4389 class ThreadHandlesClosure : public ThreadClosure {
4390   void (*_f)(Metadata*);
4391  public:
4392   ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4393   virtual void do_thread(Thread* thread) {
4394     thread->metadata_handles_do(_f);
4395   }
4396 };
4397 
4398 void Threads::metadata_handles_do(void f(Metadata*)) {
4399   // Only walk the Handles in Thread.
4400   ThreadHandlesClosure handles_closure(f);
4401   threads_do(&handles_closure);
4402 }
4403 
4404 void Threads::deoptimized_wrt_marked_nmethods() {
4405   ALL_JAVA_THREADS(p) {
4406     p->deoptimized_wrt_marked_nmethods();
4407   }
4408 }
4409 
4410 
4411 // Get count Java threads that are waiting to enter the specified monitor.
4412 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4413                                                          address monitor,
4414                                                          bool doLock) {
4415   assert(doLock || SafepointSynchronize::is_at_safepoint(),
4416          "must grab Threads_lock or be at safepoint");
4417   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4418 
4419   int i = 0;
4420   {
4421     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4422     ALL_JAVA_THREADS(p) {
4423       if (!p->can_call_java()) continue;
4424 
4425       address pending = (address)p->current_pending_monitor();
4426       if (pending == monitor) {             // found a match
4427         if (i < count) result->append(p);   // save the first count matches
4428         i++;
4429       }
4430     }
4431   }
4432   return result;
4433 }
4434 
4435 
4436 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4437                                                       bool doLock) {
4438   assert(doLock ||
4439          Threads_lock->owned_by_self() ||
4440          SafepointSynchronize::is_at_safepoint(),
4441          "must grab Threads_lock or be at safepoint");
4442 
4443   // NULL owner means not locked so we can skip the search
4444   if (owner == NULL) return NULL;
4445 
4446   {
4447     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4448     ALL_JAVA_THREADS(p) {
4449       // first, see if owner is the address of a Java thread
4450       if (owner == (address)p) return p;
4451     }
4452   }
4453   // Cannot assert on lack of success here since this function may be
4454   // used by code that is trying to report useful problem information
4455   // like deadlock detection.
4456   if (UseHeavyMonitors) return NULL;
4457 
4458   // If we didn't find a matching Java thread and we didn't force use of
4459   // heavyweight monitors, then the owner is the stack address of the
4460   // Lock Word in the owning Java thread's stack.
4461   //
4462   JavaThread* the_owner = NULL;
4463   {
4464     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4465     ALL_JAVA_THREADS(q) {
4466       if (q->is_lock_owned(owner)) {
4467         the_owner = q;
4468         break;
4469       }
4470     }
4471   }
4472   // cannot assert on lack of success here; see above comment
4473   return the_owner;
4474 }
4475 
4476 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4477 void Threads::print_on(outputStream* st, bool print_stacks,
4478                        bool internal_format, bool print_concurrent_locks) {
4479   char buf[32];
4480   st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4481 
4482   st->print_cr("Full thread dump %s (%s %s):",
4483                Abstract_VM_Version::vm_name(),
4484                Abstract_VM_Version::vm_release(),
4485                Abstract_VM_Version::vm_info_string());
4486   st->cr();
4487 
4488 #if INCLUDE_SERVICES
4489   // Dump concurrent locks
4490   ConcurrentLocksDump concurrent_locks;
4491   if (print_concurrent_locks) {
4492     concurrent_locks.dump_at_safepoint();
4493   }
4494 #endif // INCLUDE_SERVICES
4495 
4496   ALL_JAVA_THREADS(p) {
4497     ResourceMark rm;
4498     p->print_on(st);
4499     if (print_stacks) {
4500       if (internal_format) {
4501         p->trace_stack();
4502       } else {
4503         p->print_stack_on(st);
4504       }
4505     }
4506     st->cr();
4507 #if INCLUDE_SERVICES
4508     if (print_concurrent_locks) {
4509       concurrent_locks.print_locks_on(p, st);
4510     }
4511 #endif // INCLUDE_SERVICES
4512   }
4513 
4514   VMThread::vm_thread()->print_on(st);
4515   st->cr();
4516   Universe::heap()->print_gc_threads_on(st);
4517   WatcherThread* wt = WatcherThread::watcher_thread();
4518   if (wt != NULL) {
4519     wt->print_on(st);
4520     st->cr();
4521   }
4522   st->flush();
4523 }
4524 
4525 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4526                              int buflen, bool* found_current) {
4527   if (this_thread != NULL) {
4528     bool is_current = (current == this_thread);
4529     *found_current = *found_current || is_current;
4530     st->print("%s", is_current ? "=>" : "  ");
4531 
4532     st->print(PTR_FORMAT, p2i(this_thread));
4533     st->print(" ");
4534     this_thread->print_on_error(st, buf, buflen);
4535     st->cr();
4536   }
4537 }
4538 
4539 class PrintOnErrorClosure : public ThreadClosure {
4540   outputStream* _st;
4541   Thread* _current;
4542   char* _buf;
4543   int _buflen;
4544   bool* _found_current;
4545  public:
4546   PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4547                       int buflen, bool* found_current) :
4548    _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4549 
4550   virtual void do_thread(Thread* thread) {
4551     Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4552   }
4553 };
4554 
4555 // Threads::print_on_error() is called by fatal error handler. It's possible
4556 // that VM is not at safepoint and/or current thread is inside signal handler.
4557 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4558 // memory (even in resource area), it might deadlock the error handler.
4559 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4560                              int buflen) {
4561   bool found_current = false;
4562   st->print_cr("Java Threads: ( => current thread )");
4563   ALL_JAVA_THREADS(thread) {
4564     print_on_error(thread, st, current, buf, buflen, &found_current);
4565   }
4566   st->cr();
4567 
4568   st->print_cr("Other Threads:");
4569   print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4570   print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4571 
4572   PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4573   Universe::heap()->gc_threads_do(&print_closure);
4574 
4575   if (!found_current) {
4576     st->cr();
4577     st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4578     current->print_on_error(st, buf, buflen);
4579     st->cr();
4580   }
4581   st->cr();
4582   st->print_cr("Threads with active compile tasks:");
4583   print_threads_compiling(st, buf, buflen);
4584 }
4585 
4586 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4587   ALL_JAVA_THREADS(thread) {
4588     if (thread->is_Compiler_thread()) {
4589       CompilerThread* ct = (CompilerThread*) thread;
4590       if (ct->task() != NULL) {
4591         thread->print_name_on_error(st, buf, buflen);
4592         ct->task()->print(st, NULL, true, true);
4593       }
4594     }
4595   }
4596 }
4597 
4598 
4599 // Internal SpinLock and Mutex
4600 // Based on ParkEvent
4601 
4602 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4603 //
4604 // We employ SpinLocks _only for low-contention, fixed-length
4605 // short-duration critical sections where we're concerned
4606 // about native mutex_t or HotSpot Mutex:: latency.
4607 // The mux construct provides a spin-then-block mutual exclusion
4608 // mechanism.
4609 //
4610 // Testing has shown that contention on the ListLock guarding gFreeList
4611 // is common.  If we implement ListLock as a simple SpinLock it's common
4612 // for the JVM to devolve to yielding with little progress.  This is true
4613 // despite the fact that the critical sections protected by ListLock are
4614 // extremely short.
4615 //
4616 // TODO-FIXME: ListLock should be of type SpinLock.
4617 // We should make this a 1st-class type, integrated into the lock
4618 // hierarchy as leaf-locks.  Critically, the SpinLock structure
4619 // should have sufficient padding to avoid false-sharing and excessive
4620 // cache-coherency traffic.
4621 
4622 
4623 typedef volatile int SpinLockT;
4624 
4625 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4626   if (Atomic::cmpxchg (1, adr, 0) == 0) {
4627     return;   // normal fast-path return
4628   }
4629 
4630   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4631   TEVENT(SpinAcquire - ctx);
4632   int ctr = 0;
4633   int Yields = 0;
4634   for (;;) {
4635     while (*adr != 0) {
4636       ++ctr;
4637       if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4638         if (Yields > 5) {
4639           os::naked_short_sleep(1);
4640         } else {
4641           os::naked_yield();
4642           ++Yields;
4643         }
4644       } else {
4645         SpinPause();
4646       }
4647     }
4648     if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4649   }
4650 }
4651 
4652 void Thread::SpinRelease(volatile int * adr) {
4653   assert(*adr != 0, "invariant");
4654   OrderAccess::fence();      // guarantee at least release consistency.
4655   // Roach-motel semantics.
4656   // It's safe if subsequent LDs and STs float "up" into the critical section,
4657   // but prior LDs and STs within the critical section can't be allowed
4658   // to reorder or float past the ST that releases the lock.
4659   // Loads and stores in the critical section - which appear in program
4660   // order before the store that releases the lock - must also appear
4661   // before the store that releases the lock in memory visibility order.
4662   // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4663   // the ST of 0 into the lock-word which releases the lock, so fence
4664   // more than covers this on all platforms.
4665   *adr = 0;
4666 }
4667 
4668 // muxAcquire and muxRelease:
4669 //
4670 // *  muxAcquire and muxRelease support a single-word lock-word construct.
4671 //    The LSB of the word is set IFF the lock is held.
4672 //    The remainder of the word points to the head of a singly-linked list
4673 //    of threads blocked on the lock.
4674 //
4675 // *  The current implementation of muxAcquire-muxRelease uses its own
4676 //    dedicated Thread._MuxEvent instance.  If we're interested in
4677 //    minimizing the peak number of extant ParkEvent instances then
4678 //    we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4679 //    as certain invariants were satisfied.  Specifically, care would need
4680 //    to be taken with regards to consuming unpark() "permits".
4681 //    A safe rule of thumb is that a thread would never call muxAcquire()
4682 //    if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4683 //    park().  Otherwise the _ParkEvent park() operation in muxAcquire() could
4684 //    consume an unpark() permit intended for monitorenter, for instance.
4685 //    One way around this would be to widen the restricted-range semaphore
4686 //    implemented in park().  Another alternative would be to provide
4687 //    multiple instances of the PlatformEvent() for each thread.  One
4688 //    instance would be dedicated to muxAcquire-muxRelease, for instance.
4689 //
4690 // *  Usage:
4691 //    -- Only as leaf locks
4692 //    -- for short-term locking only as muxAcquire does not perform
4693 //       thread state transitions.
4694 //
4695 // Alternatives:
4696 // *  We could implement muxAcquire and muxRelease with MCS or CLH locks
4697 //    but with parking or spin-then-park instead of pure spinning.
4698 // *  Use Taura-Oyama-Yonenzawa locks.
4699 // *  It's possible to construct a 1-0 lock if we encode the lockword as
4700 //    (List,LockByte).  Acquire will CAS the full lockword while Release
4701 //    will STB 0 into the LockByte.  The 1-0 scheme admits stranding, so
4702 //    acquiring threads use timers (ParkTimed) to detect and recover from
4703 //    the stranding window.  Thread/Node structures must be aligned on 256-byte
4704 //    boundaries by using placement-new.
4705 // *  Augment MCS with advisory back-link fields maintained with CAS().
4706 //    Pictorially:  LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4707 //    The validity of the backlinks must be ratified before we trust the value.
4708 //    If the backlinks are invalid the exiting thread must back-track through the
4709 //    the forward links, which are always trustworthy.
4710 // *  Add a successor indication.  The LockWord is currently encoded as
4711 //    (List, LOCKBIT:1).  We could also add a SUCCBIT or an explicit _succ variable
4712 //    to provide the usual futile-wakeup optimization.
4713 //    See RTStt for details.
4714 // *  Consider schedctl.sc_nopreempt to cover the critical section.
4715 //
4716 
4717 
4718 typedef volatile intptr_t MutexT;      // Mux Lock-word
4719 enum MuxBits { LOCKBIT = 1 };
4720 
4721 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4722   intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4723   if (w == 0) return;
4724   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4725     return;
4726   }
4727 
4728   TEVENT(muxAcquire - Contention);
4729   ParkEvent * const Self = Thread::current()->_MuxEvent;
4730   assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4731   for (;;) {
4732     int its = (os::is_MP() ? 100 : 0) + 1;
4733 
4734     // Optional spin phase: spin-then-park strategy
4735     while (--its >= 0) {
4736       w = *Lock;
4737       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4738         return;
4739       }
4740     }
4741 
4742     Self->reset();
4743     Self->OnList = intptr_t(Lock);
4744     // The following fence() isn't _strictly necessary as the subsequent
4745     // CAS() both serializes execution and ratifies the fetched *Lock value.
4746     OrderAccess::fence();
4747     for (;;) {
4748       w = *Lock;
4749       if ((w & LOCKBIT) == 0) {
4750         if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4751           Self->OnList = 0;   // hygiene - allows stronger asserts
4752           return;
4753         }
4754         continue;      // Interference -- *Lock changed -- Just retry
4755       }
4756       assert(w & LOCKBIT, "invariant");
4757       Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4758       if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4759     }
4760 
4761     while (Self->OnList != 0) {
4762       Self->park();
4763     }
4764   }
4765 }
4766 
4767 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4768   intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4769   if (w == 0) return;
4770   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4771     return;
4772   }
4773 
4774   TEVENT(muxAcquire - Contention);
4775   ParkEvent * ReleaseAfter = NULL;
4776   if (ev == NULL) {
4777     ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4778   }
4779   assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4780   for (;;) {
4781     guarantee(ev->OnList == 0, "invariant");
4782     int its = (os::is_MP() ? 100 : 0) + 1;
4783 
4784     // Optional spin phase: spin-then-park strategy
4785     while (--its >= 0) {
4786       w = *Lock;
4787       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4788         if (ReleaseAfter != NULL) {
4789           ParkEvent::Release(ReleaseAfter);
4790         }
4791         return;
4792       }
4793     }
4794 
4795     ev->reset();
4796     ev->OnList = intptr_t(Lock);
4797     // The following fence() isn't _strictly necessary as the subsequent
4798     // CAS() both serializes execution and ratifies the fetched *Lock value.
4799     OrderAccess::fence();
4800     for (;;) {
4801       w = *Lock;
4802       if ((w & LOCKBIT) == 0) {
4803         if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4804           ev->OnList = 0;
4805           // We call ::Release while holding the outer lock, thus
4806           // artificially lengthening the critical section.
4807           // Consider deferring the ::Release() until the subsequent unlock(),
4808           // after we've dropped the outer lock.
4809           if (ReleaseAfter != NULL) {
4810             ParkEvent::Release(ReleaseAfter);
4811           }
4812           return;
4813         }
4814         continue;      // Interference -- *Lock changed -- Just retry
4815       }
4816       assert(w & LOCKBIT, "invariant");
4817       ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4818       if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4819     }
4820 
4821     while (ev->OnList != 0) {
4822       ev->park();
4823     }
4824   }
4825 }
4826 
4827 // Release() must extract a successor from the list and then wake that thread.
4828 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4829 // similar to that used by ParkEvent::Allocate() and ::Release().  DMR-based
4830 // Release() would :
4831 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4832 // (B) Extract a successor from the private list "in-hand"
4833 // (C) attempt to CAS() the residual back into *Lock over null.
4834 //     If there were any newly arrived threads and the CAS() would fail.
4835 //     In that case Release() would detach the RATs, re-merge the list in-hand
4836 //     with the RATs and repeat as needed.  Alternately, Release() might
4837 //     detach and extract a successor, but then pass the residual list to the wakee.
4838 //     The wakee would be responsible for reattaching and remerging before it
4839 //     competed for the lock.
4840 //
4841 // Both "pop" and DMR are immune from ABA corruption -- there can be
4842 // multiple concurrent pushers, but only one popper or detacher.
4843 // This implementation pops from the head of the list.  This is unfair,
4844 // but tends to provide excellent throughput as hot threads remain hot.
4845 // (We wake recently run threads first).
4846 //
4847 // All paths through muxRelease() will execute a CAS.
4848 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4849 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4850 // executed within the critical section are complete and globally visible before the
4851 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4852 void Thread::muxRelease(volatile intptr_t * Lock)  {
4853   for (;;) {
4854     const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4855     assert(w & LOCKBIT, "invariant");
4856     if (w == LOCKBIT) return;
4857     ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4858     assert(List != NULL, "invariant");
4859     assert(List->OnList == intptr_t(Lock), "invariant");
4860     ParkEvent * const nxt = List->ListNext;
4861     guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4862 
4863     // The following CAS() releases the lock and pops the head element.
4864     // The CAS() also ratifies the previously fetched lock-word value.
4865     if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4866       continue;
4867     }
4868     List->OnList = 0;
4869     OrderAccess::fence();
4870     List->unpark();
4871     return;
4872   }
4873 }
4874 
4875 
4876 void Threads::verify() {
4877   ALL_JAVA_THREADS(p) {
4878     p->verify();
4879   }
4880   VMThread* thread = VMThread::vm_thread();
4881   if (thread != NULL) thread->verify();
4882 }