1 /*
   2  * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/classLoader.hpp"
  27 #include "classfile/javaClasses.hpp"
  28 #include "classfile/moduleEntry.hpp"
  29 #include "classfile/systemDictionary.hpp"
  30 #include "classfile/vmSymbols.hpp"
  31 #include "code/codeCache.hpp"
  32 #include "code/scopeDesc.hpp"
  33 #include "compiler/compileBroker.hpp"
  34 #include "compiler/compileTask.hpp"
  35 #include "gc/shared/gcId.hpp"
  36 #include "gc/shared/gcLocker.inline.hpp"
  37 #include "gc/shared/workgroup.hpp"
  38 #include "interpreter/interpreter.hpp"
  39 #include "interpreter/linkResolver.hpp"
  40 #include "interpreter/oopMapCache.hpp"
  41 #include "jvmtifiles/jvmtiEnv.hpp"
  42 #include "logging/log.hpp"
  43 #include "logging/logConfiguration.hpp"
  44 #include "logging/logStream.hpp"
  45 #include "memory/metaspaceShared.hpp"
  46 #include "memory/oopFactory.hpp"
  47 #include "memory/resourceArea.hpp"
  48 #include "memory/universe.inline.hpp"
  49 #include "oops/instanceKlass.hpp"
  50 #include "oops/objArrayOop.hpp"
  51 #include "oops/oop.inline.hpp"
  52 #include "oops/symbol.hpp"
  53 #include "oops/verifyOopClosure.hpp"
  54 #include "prims/jvm.h"
  55 #include "prims/jvm_misc.hpp"
  56 #include "prims/jvmtiExport.hpp"
  57 #include "prims/jvmtiThreadState.hpp"
  58 #include "prims/privilegedStack.hpp"
  59 #include "runtime/arguments.hpp"
  60 #include "runtime/atomic.hpp"
  61 #include "runtime/biasedLocking.hpp"
  62 #include "runtime/commandLineFlagConstraintList.hpp"
  63 #include "runtime/commandLineFlagWriteableList.hpp"
  64 #include "runtime/commandLineFlagRangeList.hpp"
  65 #include "runtime/deoptimization.hpp"
  66 #include "runtime/fprofiler.hpp"
  67 #include "runtime/frame.inline.hpp"
  68 #include "runtime/globals.hpp"
  69 #include "runtime/init.hpp"
  70 #include "runtime/interfaceSupport.hpp"
  71 #include "runtime/java.hpp"
  72 #include "runtime/javaCalls.hpp"
  73 #include "runtime/jniPeriodicChecker.hpp"
  74 #include "runtime/timerTrace.hpp"
  75 #include "runtime/memprofiler.hpp"
  76 #include "runtime/mutexLocker.hpp"
  77 #include "runtime/objectMonitor.hpp"
  78 #include "runtime/orderAccess.inline.hpp"
  79 #include "runtime/osThread.hpp"
  80 #include "runtime/safepoint.hpp"
  81 #include "runtime/sharedRuntime.hpp"
  82 #include "runtime/statSampler.hpp"
  83 #include "runtime/stubRoutines.hpp"
  84 #include "runtime/sweeper.hpp"
  85 #include "runtime/task.hpp"
  86 #include "runtime/thread.inline.hpp"
  87 #include "runtime/threadCritical.hpp"
  88 #include "runtime/vframe.hpp"
  89 #include "runtime/vframeArray.hpp"
  90 #include "runtime/vframe_hp.hpp"
  91 #include "runtime/vmThread.hpp"
  92 #include "runtime/vm_operations.hpp"
  93 #include "runtime/vm_version.hpp"
  94 #include "services/attachListener.hpp"
  95 #include "services/management.hpp"
  96 #include "services/memTracker.hpp"
  97 #include "services/threadService.hpp"
  98 #include "trace/traceMacros.hpp"
  99 #include "trace/tracing.hpp"
 100 #include "utilities/align.hpp"
 101 #include "utilities/defaultStream.hpp"
 102 #include "utilities/dtrace.hpp"
 103 #include "utilities/events.hpp"
 104 #include "utilities/macros.hpp"
 105 #include "utilities/preserveException.hpp"
 106 #include "utilities/vmError.hpp"
 107 #if INCLUDE_ALL_GCS
 108 #include "gc/cms/concurrentMarkSweepThread.hpp"
 109 #include "gc/g1/concurrentMarkThread.inline.hpp"
 110 #include "gc/parallel/pcTasks.hpp"
 111 #endif // INCLUDE_ALL_GCS
 112 #if INCLUDE_JVMCI
 113 #include "jvmci/jvmciCompiler.hpp"
 114 #include "jvmci/jvmciRuntime.hpp"
 115 #include "logging/logHandle.hpp"
 116 #endif
 117 #ifdef COMPILER1
 118 #include "c1/c1_Compiler.hpp"
 119 #endif
 120 #ifdef COMPILER2
 121 #include "opto/c2compiler.hpp"
 122 #include "opto/idealGraphPrinter.hpp"
 123 #endif
 124 #if INCLUDE_RTM_OPT
 125 #include "runtime/rtmLocking.hpp"
 126 #endif
 127 
 128 // Initialization after module runtime initialization
 129 void universe_post_module_init();  // must happen after call_initPhase2
 130 
 131 #ifdef DTRACE_ENABLED
 132 
 133 // Only bother with this argument setup if dtrace is available
 134 
 135   #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
 136   #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
 137 
 138   #define DTRACE_THREAD_PROBE(probe, javathread)                           \
 139     {                                                                      \
 140       ResourceMark rm(this);                                               \
 141       int len = 0;                                                         \
 142       const char* name = (javathread)->get_thread_name();                  \
 143       len = strlen(name);                                                  \
 144       HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */               \
 145         (char *) name, len,                                                \
 146         java_lang_Thread::thread_id((javathread)->threadObj()),            \
 147         (uintptr_t) (javathread)->osthread()->thread_id(),                 \
 148         java_lang_Thread::is_daemon((javathread)->threadObj()));           \
 149     }
 150 
 151 #else //  ndef DTRACE_ENABLED
 152 
 153   #define DTRACE_THREAD_PROBE(probe, javathread)
 154 
 155 #endif // ndef DTRACE_ENABLED
 156 
 157 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 158 // Current thread is maintained as a thread-local variable
 159 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
 160 #endif
 161 // Class hierarchy
 162 // - Thread
 163 //   - VMThread
 164 //   - WatcherThread
 165 //   - ConcurrentMarkSweepThread
 166 //   - JavaThread
 167 //     - CompilerThread
 168 
 169 // ======= Thread ========
 170 // Support for forcing alignment of thread objects for biased locking
 171 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
 172   if (UseBiasedLocking) {
 173     const int alignment = markOopDesc::biased_lock_alignment;
 174     size_t aligned_size = size + (alignment - sizeof(intptr_t));
 175     void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
 176                                           : AllocateHeap(aligned_size, flags, CURRENT_PC,
 177                                                          AllocFailStrategy::RETURN_NULL);
 178     void* aligned_addr     = align_up(real_malloc_addr, alignment);
 179     assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
 180            ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
 181            "JavaThread alignment code overflowed allocated storage");
 182     if (aligned_addr != real_malloc_addr) {
 183       log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
 184                               p2i(real_malloc_addr),
 185                               p2i(aligned_addr));
 186     }
 187     ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
 188     return aligned_addr;
 189   } else {
 190     return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
 191                        : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
 192   }
 193 }
 194 
 195 void Thread::operator delete(void* p) {
 196   if (UseBiasedLocking) {
 197     void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
 198     FreeHeap(real_malloc_addr);
 199   } else {
 200     FreeHeap(p);
 201   }
 202 }
 203 
 204 
 205 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
 206 // JavaThread
 207 
 208 
 209 Thread::Thread() {
 210   // stack and get_thread
 211   set_stack_base(NULL);
 212   set_stack_size(0);
 213   set_self_raw_id(0);
 214   set_lgrp_id(-1);
 215   DEBUG_ONLY(clear_suspendible_thread();)
 216 
 217   // allocated data structures
 218   set_osthread(NULL);
 219   set_resource_area(new (mtThread)ResourceArea());
 220   DEBUG_ONLY(_current_resource_mark = NULL;)
 221   set_handle_area(new (mtThread) HandleArea(NULL));
 222   set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
 223   set_active_handles(NULL);
 224   set_free_handle_block(NULL);
 225   set_last_handle_mark(NULL);
 226 
 227   // This initial value ==> never claimed.
 228   _oops_do_parity = 0;
 229 
 230   // the handle mark links itself to last_handle_mark
 231   new HandleMark(this);
 232 
 233   // plain initialization
 234   debug_only(_owned_locks = NULL;)
 235   debug_only(_allow_allocation_count = 0;)
 236   NOT_PRODUCT(_allow_safepoint_count = 0;)
 237   NOT_PRODUCT(_skip_gcalot = false;)
 238   _jvmti_env_iteration_count = 0;
 239   set_allocated_bytes(0);
 240   _vm_operation_started_count = 0;
 241   _vm_operation_completed_count = 0;
 242   _current_pending_monitor = NULL;
 243   _current_pending_monitor_is_from_java = true;
 244   _current_waiting_monitor = NULL;
 245   _num_nested_signal = 0;
 246   omFreeList = NULL;
 247   omFreeCount = 0;
 248   omFreeProvision = 32;
 249   omInUseList = NULL;
 250   omInUseCount = 0;
 251 
 252 #ifdef ASSERT
 253   _visited_for_critical_count = false;
 254 #endif
 255 
 256   _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
 257                          Monitor::_safepoint_check_sometimes);
 258   _suspend_flags = 0;
 259 
 260   // thread-specific hashCode stream generator state - Marsaglia shift-xor form
 261   _hashStateX = os::random();
 262   _hashStateY = 842502087;
 263   _hashStateZ = 0x8767;    // (int)(3579807591LL & 0xffff) ;
 264   _hashStateW = 273326509;
 265 
 266   _OnTrap   = 0;
 267   _schedctl = NULL;
 268   _Stalled  = 0;
 269   _TypeTag  = 0x2BAD;
 270 
 271   // Many of the following fields are effectively final - immutable
 272   // Note that nascent threads can't use the Native Monitor-Mutex
 273   // construct until the _MutexEvent is initialized ...
 274   // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
 275   // we might instead use a stack of ParkEvents that we could provision on-demand.
 276   // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
 277   // and ::Release()
 278   _ParkEvent   = ParkEvent::Allocate(this);
 279   _SleepEvent  = ParkEvent::Allocate(this);
 280   _MutexEvent  = ParkEvent::Allocate(this);
 281   _MuxEvent    = ParkEvent::Allocate(this);
 282 
 283 #ifdef CHECK_UNHANDLED_OOPS
 284   if (CheckUnhandledOops) {
 285     _unhandled_oops = new UnhandledOops(this);
 286   }
 287 #endif // CHECK_UNHANDLED_OOPS
 288 #ifdef ASSERT
 289   if (UseBiasedLocking) {
 290     assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
 291     assert(this == _real_malloc_address ||
 292            this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
 293            "bug in forced alignment of thread objects");
 294   }
 295 #endif // ASSERT
 296 }
 297 
 298 void Thread::initialize_thread_current() {
 299 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 300   assert(_thr_current == NULL, "Thread::current already initialized");
 301   _thr_current = this;
 302 #endif
 303   assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
 304   ThreadLocalStorage::set_thread(this);
 305   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 306 }
 307 
 308 void Thread::clear_thread_current() {
 309   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 310 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 311   _thr_current = NULL;
 312 #endif
 313   ThreadLocalStorage::set_thread(NULL);
 314 }
 315 
 316 void Thread::record_stack_base_and_size() {
 317   set_stack_base(os::current_stack_base());
 318   set_stack_size(os::current_stack_size());
 319   // CR 7190089: on Solaris, primordial thread's stack is adjusted
 320   // in initialize_thread(). Without the adjustment, stack size is
 321   // incorrect if stack is set to unlimited (ulimit -s unlimited).
 322   // So far, only Solaris has real implementation of initialize_thread().
 323   //
 324   // set up any platform-specific state.
 325   os::initialize_thread(this);
 326 
 327   // Set stack limits after thread is initialized.
 328   if (is_Java_thread()) {
 329     ((JavaThread*) this)->set_stack_overflow_limit();
 330     ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
 331   }
 332 #if INCLUDE_NMT
 333   // record thread's native stack, stack grows downward
 334   MemTracker::record_thread_stack(stack_end(), stack_size());
 335 #endif // INCLUDE_NMT
 336   log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
 337     PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
 338     os::current_thread_id(), p2i(stack_base() - stack_size()),
 339     p2i(stack_base()), stack_size()/1024);
 340 }
 341 
 342 
 343 Thread::~Thread() {
 344   EVENT_THREAD_DESTRUCT(this);
 345 
 346   // stack_base can be NULL if the thread is never started or exited before
 347   // record_stack_base_and_size called. Although, we would like to ensure
 348   // that all started threads do call record_stack_base_and_size(), there is
 349   // not proper way to enforce that.
 350 #if INCLUDE_NMT
 351   if (_stack_base != NULL) {
 352     MemTracker::release_thread_stack(stack_end(), stack_size());
 353 #ifdef ASSERT
 354     set_stack_base(NULL);
 355 #endif
 356   }
 357 #endif // INCLUDE_NMT
 358 
 359   // deallocate data structures
 360   delete resource_area();
 361   // since the handle marks are using the handle area, we have to deallocated the root
 362   // handle mark before deallocating the thread's handle area,
 363   assert(last_handle_mark() != NULL, "check we have an element");
 364   delete last_handle_mark();
 365   assert(last_handle_mark() == NULL, "check we have reached the end");
 366 
 367   // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
 368   // We NULL out the fields for good hygiene.
 369   ParkEvent::Release(_ParkEvent); _ParkEvent   = NULL;
 370   ParkEvent::Release(_SleepEvent); _SleepEvent  = NULL;
 371   ParkEvent::Release(_MutexEvent); _MutexEvent  = NULL;
 372   ParkEvent::Release(_MuxEvent); _MuxEvent    = NULL;
 373 
 374   delete handle_area();
 375   delete metadata_handles();
 376 
 377   // SR_handler uses this as a termination indicator -
 378   // needs to happen before os::free_thread()
 379   delete _SR_lock;
 380   _SR_lock = NULL;
 381 
 382   // osthread() can be NULL, if creation of thread failed.
 383   if (osthread() != NULL) os::free_thread(osthread());
 384 
 385   // clear Thread::current if thread is deleting itself.
 386   // Needed to ensure JNI correctly detects non-attached threads.
 387   if (this == Thread::current()) {
 388     clear_thread_current();
 389   }
 390 
 391   CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
 392 }
 393 
 394 // NOTE: dummy function for assertion purpose.
 395 void Thread::run() {
 396   ShouldNotReachHere();
 397 }
 398 
 399 #ifdef ASSERT
 400 // Private method to check for dangling thread pointer
 401 void check_for_dangling_thread_pointer(Thread *thread) {
 402   assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
 403          "possibility of dangling Thread pointer");
 404 }
 405 #endif
 406 
 407 ThreadPriority Thread::get_priority(const Thread* const thread) {
 408   ThreadPriority priority;
 409   // Can return an error!
 410   (void)os::get_priority(thread, priority);
 411   assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
 412   return priority;
 413 }
 414 
 415 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
 416   debug_only(check_for_dangling_thread_pointer(thread);)
 417   // Can return an error!
 418   (void)os::set_priority(thread, priority);
 419 }
 420 
 421 
 422 void Thread::start(Thread* thread) {
 423   // Start is different from resume in that its safety is guaranteed by context or
 424   // being called from a Java method synchronized on the Thread object.
 425   if (!DisableStartThread) {
 426     if (thread->is_Java_thread()) {
 427       // Initialize the thread state to RUNNABLE before starting this thread.
 428       // Can not set it after the thread started because we do not know the
 429       // exact thread state at that time. It could be in MONITOR_WAIT or
 430       // in SLEEPING or some other state.
 431       java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
 432                                           java_lang_Thread::RUNNABLE);
 433     }
 434     os::start_thread(thread);
 435   }
 436 }
 437 
 438 // Enqueue a VM_Operation to do the job for us - sometime later
 439 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
 440   VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
 441   VMThread::execute(vm_stop);
 442 }
 443 
 444 
 445 // Check if an external suspend request has completed (or has been
 446 // cancelled). Returns true if the thread is externally suspended and
 447 // false otherwise.
 448 //
 449 // The bits parameter returns information about the code path through
 450 // the routine. Useful for debugging:
 451 //
 452 // set in is_ext_suspend_completed():
 453 // 0x00000001 - routine was entered
 454 // 0x00000010 - routine return false at end
 455 // 0x00000100 - thread exited (return false)
 456 // 0x00000200 - suspend request cancelled (return false)
 457 // 0x00000400 - thread suspended (return true)
 458 // 0x00001000 - thread is in a suspend equivalent state (return true)
 459 // 0x00002000 - thread is native and walkable (return true)
 460 // 0x00004000 - thread is native_trans and walkable (needed retry)
 461 //
 462 // set in wait_for_ext_suspend_completion():
 463 // 0x00010000 - routine was entered
 464 // 0x00020000 - suspend request cancelled before loop (return false)
 465 // 0x00040000 - thread suspended before loop (return true)
 466 // 0x00080000 - suspend request cancelled in loop (return false)
 467 // 0x00100000 - thread suspended in loop (return true)
 468 // 0x00200000 - suspend not completed during retry loop (return false)
 469 
 470 // Helper class for tracing suspend wait debug bits.
 471 //
 472 // 0x00000100 indicates that the target thread exited before it could
 473 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
 474 // 0x00080000 each indicate a cancelled suspend request so they don't
 475 // count as wait failures either.
 476 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
 477 
 478 class TraceSuspendDebugBits : public StackObj {
 479  private:
 480   JavaThread * jt;
 481   bool         is_wait;
 482   bool         called_by_wait;  // meaningful when !is_wait
 483   uint32_t *   bits;
 484 
 485  public:
 486   TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
 487                         uint32_t *_bits) {
 488     jt             = _jt;
 489     is_wait        = _is_wait;
 490     called_by_wait = _called_by_wait;
 491     bits           = _bits;
 492   }
 493 
 494   ~TraceSuspendDebugBits() {
 495     if (!is_wait) {
 496 #if 1
 497       // By default, don't trace bits for is_ext_suspend_completed() calls.
 498       // That trace is very chatty.
 499       return;
 500 #else
 501       if (!called_by_wait) {
 502         // If tracing for is_ext_suspend_completed() is enabled, then only
 503         // trace calls to it from wait_for_ext_suspend_completion()
 504         return;
 505       }
 506 #endif
 507     }
 508 
 509     if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
 510       if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
 511         MutexLocker ml(Threads_lock);  // needed for get_thread_name()
 512         ResourceMark rm;
 513 
 514         tty->print_cr(
 515                       "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
 516                       jt->get_thread_name(), *bits);
 517 
 518         guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
 519       }
 520     }
 521   }
 522 };
 523 #undef DEBUG_FALSE_BITS
 524 
 525 
 526 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
 527                                           uint32_t *bits) {
 528   TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
 529 
 530   bool did_trans_retry = false;  // only do thread_in_native_trans retry once
 531   bool do_trans_retry;           // flag to force the retry
 532 
 533   *bits |= 0x00000001;
 534 
 535   do {
 536     do_trans_retry = false;
 537 
 538     if (is_exiting()) {
 539       // Thread is in the process of exiting. This is always checked
 540       // first to reduce the risk of dereferencing a freed JavaThread.
 541       *bits |= 0x00000100;
 542       return false;
 543     }
 544 
 545     if (!is_external_suspend()) {
 546       // Suspend request is cancelled. This is always checked before
 547       // is_ext_suspended() to reduce the risk of a rogue resume
 548       // confusing the thread that made the suspend request.
 549       *bits |= 0x00000200;
 550       return false;
 551     }
 552 
 553     if (is_ext_suspended()) {
 554       // thread is suspended
 555       *bits |= 0x00000400;
 556       return true;
 557     }
 558 
 559     // Now that we no longer do hard suspends of threads running
 560     // native code, the target thread can be changing thread state
 561     // while we are in this routine:
 562     //
 563     //   _thread_in_native -> _thread_in_native_trans -> _thread_blocked
 564     //
 565     // We save a copy of the thread state as observed at this moment
 566     // and make our decision about suspend completeness based on the
 567     // copy. This closes the race where the thread state is seen as
 568     // _thread_in_native_trans in the if-thread_blocked check, but is
 569     // seen as _thread_blocked in if-thread_in_native_trans check.
 570     JavaThreadState save_state = thread_state();
 571 
 572     if (save_state == _thread_blocked && is_suspend_equivalent()) {
 573       // If the thread's state is _thread_blocked and this blocking
 574       // condition is known to be equivalent to a suspend, then we can
 575       // consider the thread to be externally suspended. This means that
 576       // the code that sets _thread_blocked has been modified to do
 577       // self-suspension if the blocking condition releases. We also
 578       // used to check for CONDVAR_WAIT here, but that is now covered by
 579       // the _thread_blocked with self-suspension check.
 580       //
 581       // Return true since we wouldn't be here unless there was still an
 582       // external suspend request.
 583       *bits |= 0x00001000;
 584       return true;
 585     } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
 586       // Threads running native code will self-suspend on native==>VM/Java
 587       // transitions. If its stack is walkable (should always be the case
 588       // unless this function is called before the actual java_suspend()
 589       // call), then the wait is done.
 590       *bits |= 0x00002000;
 591       return true;
 592     } else if (!called_by_wait && !did_trans_retry &&
 593                save_state == _thread_in_native_trans &&
 594                frame_anchor()->walkable()) {
 595       // The thread is transitioning from thread_in_native to another
 596       // thread state. check_safepoint_and_suspend_for_native_trans()
 597       // will force the thread to self-suspend. If it hasn't gotten
 598       // there yet we may have caught the thread in-between the native
 599       // code check above and the self-suspend. Lucky us. If we were
 600       // called by wait_for_ext_suspend_completion(), then it
 601       // will be doing the retries so we don't have to.
 602       //
 603       // Since we use the saved thread state in the if-statement above,
 604       // there is a chance that the thread has already transitioned to
 605       // _thread_blocked by the time we get here. In that case, we will
 606       // make a single unnecessary pass through the logic below. This
 607       // doesn't hurt anything since we still do the trans retry.
 608 
 609       *bits |= 0x00004000;
 610 
 611       // Once the thread leaves thread_in_native_trans for another
 612       // thread state, we break out of this retry loop. We shouldn't
 613       // need this flag to prevent us from getting back here, but
 614       // sometimes paranoia is good.
 615       did_trans_retry = true;
 616 
 617       // We wait for the thread to transition to a more usable state.
 618       for (int i = 1; i <= SuspendRetryCount; i++) {
 619         // We used to do an "os::yield_all(i)" call here with the intention
 620         // that yielding would increase on each retry. However, the parameter
 621         // is ignored on Linux which means the yield didn't scale up. Waiting
 622         // on the SR_lock below provides a much more predictable scale up for
 623         // the delay. It also provides a simple/direct point to check for any
 624         // safepoint requests from the VMThread
 625 
 626         // temporarily drops SR_lock while doing wait with safepoint check
 627         // (if we're a JavaThread - the WatcherThread can also call this)
 628         // and increase delay with each retry
 629         SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 630 
 631         // check the actual thread state instead of what we saved above
 632         if (thread_state() != _thread_in_native_trans) {
 633           // the thread has transitioned to another thread state so
 634           // try all the checks (except this one) one more time.
 635           do_trans_retry = true;
 636           break;
 637         }
 638       } // end retry loop
 639 
 640 
 641     }
 642   } while (do_trans_retry);
 643 
 644   *bits |= 0x00000010;
 645   return false;
 646 }
 647 
 648 // Wait for an external suspend request to complete (or be cancelled).
 649 // Returns true if the thread is externally suspended and false otherwise.
 650 //
 651 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
 652                                                  uint32_t *bits) {
 653   TraceSuspendDebugBits tsdb(this, true /* is_wait */,
 654                              false /* !called_by_wait */, bits);
 655 
 656   // local flag copies to minimize SR_lock hold time
 657   bool is_suspended;
 658   bool pending;
 659   uint32_t reset_bits;
 660 
 661   // set a marker so is_ext_suspend_completed() knows we are the caller
 662   *bits |= 0x00010000;
 663 
 664   // We use reset_bits to reinitialize the bits value at the top of
 665   // each retry loop. This allows the caller to make use of any
 666   // unused bits for their own marking purposes.
 667   reset_bits = *bits;
 668 
 669   {
 670     MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
 671     is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 672                                             delay, bits);
 673     pending = is_external_suspend();
 674   }
 675   // must release SR_lock to allow suspension to complete
 676 
 677   if (!pending) {
 678     // A cancelled suspend request is the only false return from
 679     // is_ext_suspend_completed() that keeps us from entering the
 680     // retry loop.
 681     *bits |= 0x00020000;
 682     return false;
 683   }
 684 
 685   if (is_suspended) {
 686     *bits |= 0x00040000;
 687     return true;
 688   }
 689 
 690   for (int i = 1; i <= retries; i++) {
 691     *bits = reset_bits;  // reinit to only track last retry
 692 
 693     // We used to do an "os::yield_all(i)" call here with the intention
 694     // that yielding would increase on each retry. However, the parameter
 695     // is ignored on Linux which means the yield didn't scale up. Waiting
 696     // on the SR_lock below provides a much more predictable scale up for
 697     // the delay. It also provides a simple/direct point to check for any
 698     // safepoint requests from the VMThread
 699 
 700     {
 701       MutexLocker ml(SR_lock());
 702       // wait with safepoint check (if we're a JavaThread - the WatcherThread
 703       // can also call this)  and increase delay with each retry
 704       SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 705 
 706       is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 707                                               delay, bits);
 708 
 709       // It is possible for the external suspend request to be cancelled
 710       // (by a resume) before the actual suspend operation is completed.
 711       // Refresh our local copy to see if we still need to wait.
 712       pending = is_external_suspend();
 713     }
 714 
 715     if (!pending) {
 716       // A cancelled suspend request is the only false return from
 717       // is_ext_suspend_completed() that keeps us from staying in the
 718       // retry loop.
 719       *bits |= 0x00080000;
 720       return false;
 721     }
 722 
 723     if (is_suspended) {
 724       *bits |= 0x00100000;
 725       return true;
 726     }
 727   } // end retry loop
 728 
 729   // thread did not suspend after all our retries
 730   *bits |= 0x00200000;
 731   return false;
 732 }
 733 
 734 #ifndef PRODUCT
 735 void JavaThread::record_jump(address target, address instr, const char* file,
 736                              int line) {
 737 
 738   // This should not need to be atomic as the only way for simultaneous
 739   // updates is via interrupts. Even then this should be rare or non-existent
 740   // and we don't care that much anyway.
 741 
 742   int index = _jmp_ring_index;
 743   _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
 744   _jmp_ring[index]._target = (intptr_t) target;
 745   _jmp_ring[index]._instruction = (intptr_t) instr;
 746   _jmp_ring[index]._file = file;
 747   _jmp_ring[index]._line = line;
 748 }
 749 #endif // PRODUCT
 750 
 751 // Called by flat profiler
 752 // Callers have already called wait_for_ext_suspend_completion
 753 // The assertion for that is currently too complex to put here:
 754 bool JavaThread::profile_last_Java_frame(frame* _fr) {
 755   bool gotframe = false;
 756   // self suspension saves needed state.
 757   if (has_last_Java_frame() && _anchor.walkable()) {
 758     *_fr = pd_last_frame();
 759     gotframe = true;
 760   }
 761   return gotframe;
 762 }
 763 
 764 void Thread::interrupt(Thread* thread) {
 765   debug_only(check_for_dangling_thread_pointer(thread);)
 766   os::interrupt(thread);
 767 }
 768 
 769 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
 770   debug_only(check_for_dangling_thread_pointer(thread);)
 771   // Note:  If clear_interrupted==false, this simply fetches and
 772   // returns the value of the field osthread()->interrupted().
 773   return os::is_interrupted(thread, clear_interrupted);
 774 }
 775 
 776 
 777 // GC Support
 778 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
 779   jint thread_parity = _oops_do_parity;
 780   if (thread_parity != strong_roots_parity) {
 781     jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
 782     if (res == thread_parity) {
 783       return true;
 784     } else {
 785       guarantee(res == strong_roots_parity, "Or else what?");
 786       return false;
 787     }
 788   }
 789   return false;
 790 }
 791 
 792 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
 793   active_handles()->oops_do(f);
 794   // Do oop for ThreadShadow
 795   f->do_oop((oop*)&_pending_exception);
 796   handle_area()->oops_do(f);
 797 
 798   if (MonitorInUseLists) {
 799     // When using thread local monitor lists, we scan them here,
 800     // and the remaining global monitors in ObjectSynchronizer::oops_do().
 801     ObjectSynchronizer::thread_local_used_oops_do(this, f);
 802   }
 803 }
 804 
 805 void Thread::metadata_handles_do(void f(Metadata*)) {
 806   // Only walk the Handles in Thread.
 807   if (metadata_handles() != NULL) {
 808     for (int i = 0; i< metadata_handles()->length(); i++) {
 809       f(metadata_handles()->at(i));
 810     }
 811   }
 812 }
 813 
 814 void Thread::print_on(outputStream* st) const {
 815   // get_priority assumes osthread initialized
 816   if (osthread() != NULL) {
 817     int os_prio;
 818     if (os::get_native_priority(this, &os_prio) == OS_OK) {
 819       st->print("os_prio=%d ", os_prio);
 820     }
 821     st->print("tid=" INTPTR_FORMAT " ", p2i(this));
 822     ext().print_on(st);
 823     osthread()->print_on(st);
 824   }
 825   debug_only(if (WizardMode) print_owned_locks_on(st);)
 826 }
 827 
 828 // Thread::print_on_error() is called by fatal error handler. Don't use
 829 // any lock or allocate memory.
 830 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
 831   assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
 832 
 833   if (is_VM_thread())                 { st->print("VMThread"); }
 834   else if (is_GC_task_thread())       { st->print("GCTaskThread"); }
 835   else if (is_Watcher_thread())       { st->print("WatcherThread"); }
 836   else if (is_ConcurrentGC_thread())  { st->print("ConcurrentGCThread"); }
 837   else                                { st->print("Thread"); }
 838 
 839   if (is_Named_thread()) {
 840     st->print(" \"%s\"", name());
 841   }
 842 
 843   st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
 844             p2i(stack_end()), p2i(stack_base()));
 845 
 846   if (osthread()) {
 847     st->print(" [id=%d]", osthread()->thread_id());
 848   }
 849 }
 850 
 851 #ifdef ASSERT
 852 void Thread::print_owned_locks_on(outputStream* st) const {
 853   Monitor *cur = _owned_locks;
 854   if (cur == NULL) {
 855     st->print(" (no locks) ");
 856   } else {
 857     st->print_cr(" Locks owned:");
 858     while (cur) {
 859       cur->print_on(st);
 860       cur = cur->next();
 861     }
 862   }
 863 }
 864 
 865 static int ref_use_count  = 0;
 866 
 867 bool Thread::owns_locks_but_compiled_lock() const {
 868   for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 869     if (cur != Compile_lock) return true;
 870   }
 871   return false;
 872 }
 873 
 874 
 875 #endif
 876 
 877 #ifndef PRODUCT
 878 
 879 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
 880 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
 881 // no threads which allow_vm_block's are held
 882 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
 883   // Check if current thread is allowed to block at a safepoint
 884   if (!(_allow_safepoint_count == 0)) {
 885     fatal("Possible safepoint reached by thread that does not allow it");
 886   }
 887   if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
 888     fatal("LEAF method calling lock?");
 889   }
 890 
 891 #ifdef ASSERT
 892   if (potential_vm_operation && is_Java_thread()
 893       && !Universe::is_bootstrapping()) {
 894     // Make sure we do not hold any locks that the VM thread also uses.
 895     // This could potentially lead to deadlocks
 896     for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 897       // Threads_lock is special, since the safepoint synchronization will not start before this is
 898       // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
 899       // since it is used to transfer control between JavaThreads and the VMThread
 900       // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
 901       if ((cur->allow_vm_block() &&
 902            cur != Threads_lock &&
 903            cur != Compile_lock &&               // Temporary: should not be necessary when we get separate compilation
 904            cur != VMOperationRequest_lock &&
 905            cur != VMOperationQueue_lock) ||
 906            cur->rank() == Mutex::special) {
 907         fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
 908       }
 909     }
 910   }
 911 
 912   if (GCALotAtAllSafepoints) {
 913     // We could enter a safepoint here and thus have a gc
 914     InterfaceSupport::check_gc_alot();
 915   }
 916 #endif
 917 }
 918 #endif
 919 
 920 bool Thread::is_in_stack(address adr) const {
 921   assert(Thread::current() == this, "is_in_stack can only be called from current thread");
 922   address end = os::current_stack_pointer();
 923   // Allow non Java threads to call this without stack_base
 924   if (_stack_base == NULL) return true;
 925   if (stack_base() >= adr && adr >= end) return true;
 926 
 927   return false;
 928 }
 929 
 930 bool Thread::is_in_usable_stack(address adr) const {
 931   size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
 932   size_t usable_stack_size = _stack_size - stack_guard_size;
 933 
 934   return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
 935 }
 936 
 937 
 938 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
 939 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
 940 // used for compilation in the future. If that change is made, the need for these methods
 941 // should be revisited, and they should be removed if possible.
 942 
 943 bool Thread::is_lock_owned(address adr) const {
 944   return on_local_stack(adr);
 945 }
 946 
 947 bool Thread::set_as_starting_thread() {
 948   // NOTE: this must be called inside the main thread.
 949   return os::create_main_thread((JavaThread*)this);
 950 }
 951 
 952 static void initialize_class(Symbol* class_name, TRAPS) {
 953   Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
 954   InstanceKlass::cast(klass)->initialize(CHECK);
 955 }
 956 
 957 
 958 // Creates the initial ThreadGroup
 959 static Handle create_initial_thread_group(TRAPS) {
 960   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
 961   InstanceKlass* ik = InstanceKlass::cast(k);
 962 
 963   Handle system_instance = ik->allocate_instance_handle(CHECK_NH);
 964   {
 965     JavaValue result(T_VOID);
 966     JavaCalls::call_special(&result,
 967                             system_instance,
 968                             ik,
 969                             vmSymbols::object_initializer_name(),
 970                             vmSymbols::void_method_signature(),
 971                             CHECK_NH);
 972   }
 973   Universe::set_system_thread_group(system_instance());
 974 
 975   Handle main_instance = ik->allocate_instance_handle(CHECK_NH);
 976   {
 977     JavaValue result(T_VOID);
 978     Handle string = java_lang_String::create_from_str("main", CHECK_NH);
 979     JavaCalls::call_special(&result,
 980                             main_instance,
 981                             ik,
 982                             vmSymbols::object_initializer_name(),
 983                             vmSymbols::threadgroup_string_void_signature(),
 984                             system_instance,
 985                             string,
 986                             CHECK_NH);
 987   }
 988   return main_instance;
 989 }
 990 
 991 // Creates the initial Thread
 992 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
 993                                  TRAPS) {
 994   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
 995   InstanceKlass* ik = InstanceKlass::cast(k);
 996   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
 997 
 998   java_lang_Thread::set_thread(thread_oop(), thread);
 999   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1000   thread->set_threadObj(thread_oop());
1001 
1002   Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1003 
1004   JavaValue result(T_VOID);
1005   JavaCalls::call_special(&result, thread_oop,
1006                           ik,
1007                           vmSymbols::object_initializer_name(),
1008                           vmSymbols::threadgroup_string_void_signature(),
1009                           thread_group,
1010                           string,
1011                           CHECK_NULL);
1012   return thread_oop();
1013 }
1014 
1015 char java_runtime_name[128] = "";
1016 char java_runtime_version[128] = "";
1017 
1018 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1019 static const char* get_java_runtime_name(TRAPS) {
1020   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1021                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1022   fieldDescriptor fd;
1023   bool found = k != NULL &&
1024                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1025                                                         vmSymbols::string_signature(), &fd);
1026   if (found) {
1027     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1028     if (name_oop == NULL) {
1029       return NULL;
1030     }
1031     const char* name = java_lang_String::as_utf8_string(name_oop,
1032                                                         java_runtime_name,
1033                                                         sizeof(java_runtime_name));
1034     return name;
1035   } else {
1036     return NULL;
1037   }
1038 }
1039 
1040 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1041 static const char* get_java_runtime_version(TRAPS) {
1042   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1043                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1044   fieldDescriptor fd;
1045   bool found = k != NULL &&
1046                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1047                                                         vmSymbols::string_signature(), &fd);
1048   if (found) {
1049     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1050     if (name_oop == NULL) {
1051       return NULL;
1052     }
1053     const char* name = java_lang_String::as_utf8_string(name_oop,
1054                                                         java_runtime_version,
1055                                                         sizeof(java_runtime_version));
1056     return name;
1057   } else {
1058     return NULL;
1059   }
1060 }
1061 
1062 // General purpose hook into Java code, run once when the VM is initialized.
1063 // The Java library method itself may be changed independently from the VM.
1064 static void call_postVMInitHook(TRAPS) {
1065   Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1066   if (klass != NULL) {
1067     JavaValue result(T_VOID);
1068     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1069                            vmSymbols::void_method_signature(),
1070                            CHECK);
1071   }
1072 }
1073 
1074 static void reset_vm_info_property(TRAPS) {
1075   // the vm info string
1076   ResourceMark rm(THREAD);
1077   const char *vm_info = VM_Version::vm_info_string();
1078 
1079   // java.lang.System class
1080   Klass* klass =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1081 
1082   // setProperty arguments
1083   Handle key_str    = java_lang_String::create_from_str("java.vm.info", CHECK);
1084   Handle value_str  = java_lang_String::create_from_str(vm_info, CHECK);
1085 
1086   // return value
1087   JavaValue r(T_OBJECT);
1088 
1089   // public static String setProperty(String key, String value);
1090   JavaCalls::call_static(&r,
1091                          klass,
1092                          vmSymbols::setProperty_name(),
1093                          vmSymbols::string_string_string_signature(),
1094                          key_str,
1095                          value_str,
1096                          CHECK);
1097 }
1098 
1099 
1100 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1101                                     bool daemon, TRAPS) {
1102   assert(thread_group.not_null(), "thread group should be specified");
1103   assert(threadObj() == NULL, "should only create Java thread object once");
1104 
1105   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1106   InstanceKlass* ik = InstanceKlass::cast(k);
1107   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1108 
1109   java_lang_Thread::set_thread(thread_oop(), this);
1110   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1111   set_threadObj(thread_oop());
1112 
1113   JavaValue result(T_VOID);
1114   if (thread_name != NULL) {
1115     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1116     // Thread gets assigned specified name and null target
1117     JavaCalls::call_special(&result,
1118                             thread_oop,
1119                             ik,
1120                             vmSymbols::object_initializer_name(),
1121                             vmSymbols::threadgroup_string_void_signature(),
1122                             thread_group, // Argument 1
1123                             name,         // Argument 2
1124                             THREAD);
1125   } else {
1126     // Thread gets assigned name "Thread-nnn" and null target
1127     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1128     JavaCalls::call_special(&result,
1129                             thread_oop,
1130                             ik,
1131                             vmSymbols::object_initializer_name(),
1132                             vmSymbols::threadgroup_runnable_void_signature(),
1133                             thread_group, // Argument 1
1134                             Handle(),     // Argument 2
1135                             THREAD);
1136   }
1137 
1138 
1139   if (daemon) {
1140     java_lang_Thread::set_daemon(thread_oop());
1141   }
1142 
1143   if (HAS_PENDING_EXCEPTION) {
1144     return;
1145   }
1146 
1147   Klass* group =  SystemDictionary::ThreadGroup_klass();
1148   Handle threadObj(THREAD, this->threadObj());
1149 
1150   JavaCalls::call_special(&result,
1151                           thread_group,
1152                           group,
1153                           vmSymbols::add_method_name(),
1154                           vmSymbols::thread_void_signature(),
1155                           threadObj,          // Arg 1
1156                           THREAD);
1157 }
1158 
1159 // NamedThread --  non-JavaThread subclasses with multiple
1160 // uniquely named instances should derive from this.
1161 NamedThread::NamedThread() : Thread() {
1162   _name = NULL;
1163   _processed_thread = NULL;
1164   _gc_id = GCId::undefined();
1165 }
1166 
1167 NamedThread::~NamedThread() {
1168   if (_name != NULL) {
1169     FREE_C_HEAP_ARRAY(char, _name);
1170     _name = NULL;
1171   }
1172 }
1173 
1174 void NamedThread::set_name(const char* format, ...) {
1175   guarantee(_name == NULL, "Only get to set name once.");
1176   _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1177   guarantee(_name != NULL, "alloc failure");
1178   va_list ap;
1179   va_start(ap, format);
1180   jio_vsnprintf(_name, max_name_len, format, ap);
1181   va_end(ap);
1182 }
1183 
1184 void NamedThread::initialize_named_thread() {
1185   set_native_thread_name(name());
1186 }
1187 
1188 void NamedThread::print_on(outputStream* st) const {
1189   st->print("\"%s\" ", name());
1190   Thread::print_on(st);
1191   st->cr();
1192 }
1193 
1194 
1195 // ======= WatcherThread ========
1196 
1197 // The watcher thread exists to simulate timer interrupts.  It should
1198 // be replaced by an abstraction over whatever native support for
1199 // timer interrupts exists on the platform.
1200 
1201 WatcherThread* WatcherThread::_watcher_thread   = NULL;
1202 bool WatcherThread::_startable = false;
1203 volatile bool  WatcherThread::_should_terminate = false;
1204 
1205 WatcherThread::WatcherThread() : Thread() {
1206   assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1207   if (os::create_thread(this, os::watcher_thread)) {
1208     _watcher_thread = this;
1209 
1210     // Set the watcher thread to the highest OS priority which should not be
1211     // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1212     // is created. The only normal thread using this priority is the reference
1213     // handler thread, which runs for very short intervals only.
1214     // If the VMThread's priority is not lower than the WatcherThread profiling
1215     // will be inaccurate.
1216     os::set_priority(this, MaxPriority);
1217     if (!DisableStartThread) {
1218       os::start_thread(this);
1219     }
1220   }
1221 }
1222 
1223 int WatcherThread::sleep() const {
1224   // The WatcherThread does not participate in the safepoint protocol
1225   // for the PeriodicTask_lock because it is not a JavaThread.
1226   MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1227 
1228   if (_should_terminate) {
1229     // check for termination before we do any housekeeping or wait
1230     return 0;  // we did not sleep.
1231   }
1232 
1233   // remaining will be zero if there are no tasks,
1234   // causing the WatcherThread to sleep until a task is
1235   // enrolled
1236   int remaining = PeriodicTask::time_to_wait();
1237   int time_slept = 0;
1238 
1239   // we expect this to timeout - we only ever get unparked when
1240   // we should terminate or when a new task has been enrolled
1241   OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1242 
1243   jlong time_before_loop = os::javaTimeNanos();
1244 
1245   while (true) {
1246     bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1247                                             remaining);
1248     jlong now = os::javaTimeNanos();
1249 
1250     if (remaining == 0) {
1251       // if we didn't have any tasks we could have waited for a long time
1252       // consider the time_slept zero and reset time_before_loop
1253       time_slept = 0;
1254       time_before_loop = now;
1255     } else {
1256       // need to recalculate since we might have new tasks in _tasks
1257       time_slept = (int) ((now - time_before_loop) / 1000000);
1258     }
1259 
1260     // Change to task list or spurious wakeup of some kind
1261     if (timedout || _should_terminate) {
1262       break;
1263     }
1264 
1265     remaining = PeriodicTask::time_to_wait();
1266     if (remaining == 0) {
1267       // Last task was just disenrolled so loop around and wait until
1268       // another task gets enrolled
1269       continue;
1270     }
1271 
1272     remaining -= time_slept;
1273     if (remaining <= 0) {
1274       break;
1275     }
1276   }
1277 
1278   return time_slept;
1279 }
1280 
1281 void WatcherThread::run() {
1282   assert(this == watcher_thread(), "just checking");
1283 
1284   this->record_stack_base_and_size();
1285   this->set_native_thread_name(this->name());
1286   this->set_active_handles(JNIHandleBlock::allocate_block());
1287   while (true) {
1288     assert(watcher_thread() == Thread::current(), "thread consistency check");
1289     assert(watcher_thread() == this, "thread consistency check");
1290 
1291     // Calculate how long it'll be until the next PeriodicTask work
1292     // should be done, and sleep that amount of time.
1293     int time_waited = sleep();
1294 
1295     if (VMError::is_error_reported()) {
1296       // A fatal error has happened, the error handler(VMError::report_and_die)
1297       // should abort JVM after creating an error log file. However in some
1298       // rare cases, the error handler itself might deadlock. Here periodically
1299       // check for error reporting timeouts, and if it happens, just proceed to
1300       // abort the VM.
1301 
1302       // This code is in WatcherThread because WatcherThread wakes up
1303       // periodically so the fatal error handler doesn't need to do anything;
1304       // also because the WatcherThread is less likely to crash than other
1305       // threads.
1306 
1307       for (;;) {
1308         // Note: we use naked sleep in this loop because we want to avoid using
1309         // any kind of VM infrastructure which may be broken at this point.
1310         if (VMError::check_timeout()) {
1311           // We hit error reporting timeout. Error reporting was interrupted and
1312           // will be wrapping things up now (closing files etc). Give it some more
1313           // time, then quit the VM.
1314           os::naked_short_sleep(200);
1315           // Print a message to stderr.
1316           fdStream err(defaultStream::output_fd());
1317           err.print_raw_cr("# [ timer expired, abort... ]");
1318           // skip atexit/vm_exit/vm_abort hooks
1319           os::die();
1320         }
1321 
1322         // Wait a second, then recheck for timeout.
1323         os::naked_short_sleep(999);
1324       }
1325     }
1326 
1327     if (_should_terminate) {
1328       // check for termination before posting the next tick
1329       break;
1330     }
1331 
1332     PeriodicTask::real_time_tick(time_waited);
1333   }
1334 
1335   // Signal that it is terminated
1336   {
1337     MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1338     _watcher_thread = NULL;
1339     Terminator_lock->notify();
1340   }
1341 }
1342 
1343 void WatcherThread::start() {
1344   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1345 
1346   if (watcher_thread() == NULL && _startable) {
1347     _should_terminate = false;
1348     // Create the single instance of WatcherThread
1349     new WatcherThread();
1350   }
1351 }
1352 
1353 void WatcherThread::make_startable() {
1354   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1355   _startable = true;
1356 }
1357 
1358 void WatcherThread::stop() {
1359   {
1360     // Follow normal safepoint aware lock enter protocol since the
1361     // WatcherThread is stopped by another JavaThread.
1362     MutexLocker ml(PeriodicTask_lock);
1363     _should_terminate = true;
1364 
1365     WatcherThread* watcher = watcher_thread();
1366     if (watcher != NULL) {
1367       // unpark the WatcherThread so it can see that it should terminate
1368       watcher->unpark();
1369     }
1370   }
1371 
1372   MutexLocker mu(Terminator_lock);
1373 
1374   while (watcher_thread() != NULL) {
1375     // This wait should make safepoint checks, wait without a timeout,
1376     // and wait as a suspend-equivalent condition.
1377     //
1378     // Note: If the FlatProfiler is running, then this thread is waiting
1379     // for the WatcherThread to terminate and the WatcherThread, via the
1380     // FlatProfiler task, is waiting for the external suspend request on
1381     // this thread to complete. wait_for_ext_suspend_completion() will
1382     // eventually timeout, but that takes time. Making this wait a
1383     // suspend-equivalent condition solves that timeout problem.
1384     //
1385     Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1386                           Mutex::_as_suspend_equivalent_flag);
1387   }
1388 }
1389 
1390 void WatcherThread::unpark() {
1391   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1392   PeriodicTask_lock->notify();
1393 }
1394 
1395 void WatcherThread::print_on(outputStream* st) const {
1396   st->print("\"%s\" ", name());
1397   Thread::print_on(st);
1398   st->cr();
1399 }
1400 
1401 // ======= JavaThread ========
1402 
1403 #if INCLUDE_JVMCI
1404 
1405 jlong* JavaThread::_jvmci_old_thread_counters;
1406 
1407 bool jvmci_counters_include(JavaThread* thread) {
1408   oop threadObj = thread->threadObj();
1409   return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1410 }
1411 
1412 void JavaThread::collect_counters(typeArrayOop array) {
1413   if (JVMCICounterSize > 0) {
1414     MutexLocker tl(Threads_lock);
1415     for (int i = 0; i < array->length(); i++) {
1416       array->long_at_put(i, _jvmci_old_thread_counters[i]);
1417     }
1418     for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) {
1419       if (jvmci_counters_include(tp)) {
1420         for (int i = 0; i < array->length(); i++) {
1421           array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1422         }
1423       }
1424     }
1425   }
1426 }
1427 
1428 #endif // INCLUDE_JVMCI
1429 
1430 // A JavaThread is a normal Java thread
1431 
1432 void JavaThread::initialize() {
1433   // Initialize fields
1434 
1435   set_saved_exception_pc(NULL);
1436   set_threadObj(NULL);
1437   _anchor.clear();
1438   set_entry_point(NULL);
1439   set_jni_functions(jni_functions());
1440   set_callee_target(NULL);
1441   set_vm_result(NULL);
1442   set_vm_result_2(NULL);
1443   set_vframe_array_head(NULL);
1444   set_vframe_array_last(NULL);
1445   set_deferred_locals(NULL);
1446   set_deopt_mark(NULL);
1447   set_deopt_compiled_method(NULL);
1448   clear_must_deopt_id();
1449   set_monitor_chunks(NULL);
1450   set_next(NULL);
1451   set_thread_state(_thread_new);
1452   _terminated = _not_terminated;
1453   _privileged_stack_top = NULL;
1454   _array_for_gc = NULL;
1455   _suspend_equivalent = false;
1456   _in_deopt_handler = 0;
1457   _doing_unsafe_access = false;
1458   _stack_guard_state = stack_guard_unused;
1459 #if INCLUDE_JVMCI
1460   _pending_monitorenter = false;
1461   _pending_deoptimization = -1;
1462   _pending_failed_speculation = NULL;
1463   _pending_transfer_to_interpreter = false;
1464   _adjusting_comp_level = false;
1465   _jvmci._alternate_call_target = NULL;
1466   assert(_jvmci._implicit_exception_pc == NULL, "must be");
1467   if (JVMCICounterSize > 0) {
1468     _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1469     memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1470   } else {
1471     _jvmci_counters = NULL;
1472   }
1473 #endif // INCLUDE_JVMCI
1474   _reserved_stack_activation = NULL;  // stack base not known yet
1475   (void)const_cast<oop&>(_exception_oop = oop(NULL));
1476   _exception_pc  = 0;
1477   _exception_handler_pc = 0;
1478   _is_method_handle_return = 0;
1479   _jvmti_thread_state= NULL;
1480   _should_post_on_exceptions_flag = JNI_FALSE;
1481   _jvmti_get_loaded_classes_closure = NULL;
1482   _interp_only_mode    = 0;
1483   _special_runtime_exit_condition = _no_async_condition;
1484   _pending_async_exception = NULL;
1485   _thread_stat = NULL;
1486   _thread_stat = new ThreadStatistics();
1487   _blocked_on_compilation = false;
1488   _jni_active_critical = 0;
1489   _pending_jni_exception_check_fn = NULL;
1490   _do_not_unlock_if_synchronized = false;
1491   _cached_monitor_info = NULL;
1492   _parker = Parker::Allocate(this);
1493 
1494 #ifndef PRODUCT
1495   _jmp_ring_index = 0;
1496   for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1497     record_jump(NULL, NULL, NULL, 0);
1498   }
1499 #endif // PRODUCT
1500 
1501   set_thread_profiler(NULL);
1502   if (FlatProfiler::is_active()) {
1503     // This is where we would decide to either give each thread it's own profiler
1504     // or use one global one from FlatProfiler,
1505     // or up to some count of the number of profiled threads, etc.
1506     ThreadProfiler* pp = new ThreadProfiler();
1507     pp->engage();
1508     set_thread_profiler(pp);
1509   }
1510 
1511   // Setup safepoint state info for this thread
1512   ThreadSafepointState::create(this);
1513 
1514   debug_only(_java_call_counter = 0);
1515 
1516   // JVMTI PopFrame support
1517   _popframe_condition = popframe_inactive;
1518   _popframe_preserved_args = NULL;
1519   _popframe_preserved_args_size = 0;
1520   _frames_to_pop_failed_realloc = 0;
1521 
1522   pd_initialize();
1523 }
1524 
1525 #if INCLUDE_ALL_GCS
1526 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1527 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1528 #endif // INCLUDE_ALL_GCS
1529 
1530 JavaThread::JavaThread(bool is_attaching_via_jni) :
1531                        Thread()
1532 #if INCLUDE_ALL_GCS
1533                        , _satb_mark_queue(&_satb_mark_queue_set),
1534                        _dirty_card_queue(&_dirty_card_queue_set)
1535 #endif // INCLUDE_ALL_GCS
1536 {
1537   initialize();
1538   if (is_attaching_via_jni) {
1539     _jni_attach_state = _attaching_via_jni;
1540   } else {
1541     _jni_attach_state = _not_attaching_via_jni;
1542   }
1543   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1544 }
1545 
1546 bool JavaThread::reguard_stack(address cur_sp) {
1547   if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1548       && _stack_guard_state != stack_guard_reserved_disabled) {
1549     return true; // Stack already guarded or guard pages not needed.
1550   }
1551 
1552   if (register_stack_overflow()) {
1553     // For those architectures which have separate register and
1554     // memory stacks, we must check the register stack to see if
1555     // it has overflowed.
1556     return false;
1557   }
1558 
1559   // Java code never executes within the yellow zone: the latter is only
1560   // there to provoke an exception during stack banging.  If java code
1561   // is executing there, either StackShadowPages should be larger, or
1562   // some exception code in c1, c2 or the interpreter isn't unwinding
1563   // when it should.
1564   guarantee(cur_sp > stack_reserved_zone_base(),
1565             "not enough space to reguard - increase StackShadowPages");
1566   if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1567     enable_stack_yellow_reserved_zone();
1568     if (reserved_stack_activation() != stack_base()) {
1569       set_reserved_stack_activation(stack_base());
1570     }
1571   } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1572     set_reserved_stack_activation(stack_base());
1573     enable_stack_reserved_zone();
1574   }
1575   return true;
1576 }
1577 
1578 bool JavaThread::reguard_stack(void) {
1579   return reguard_stack(os::current_stack_pointer());
1580 }
1581 
1582 
1583 void JavaThread::block_if_vm_exited() {
1584   if (_terminated == _vm_exited) {
1585     // _vm_exited is set at safepoint, and Threads_lock is never released
1586     // we will block here forever
1587     Threads_lock->lock_without_safepoint_check();
1588     ShouldNotReachHere();
1589   }
1590 }
1591 
1592 
1593 // Remove this ifdef when C1 is ported to the compiler interface.
1594 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1595 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1596 
1597 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1598                        Thread()
1599 #if INCLUDE_ALL_GCS
1600                        , _satb_mark_queue(&_satb_mark_queue_set),
1601                        _dirty_card_queue(&_dirty_card_queue_set)
1602 #endif // INCLUDE_ALL_GCS
1603 {
1604   initialize();
1605   _jni_attach_state = _not_attaching_via_jni;
1606   set_entry_point(entry_point);
1607   // Create the native thread itself.
1608   // %note runtime_23
1609   os::ThreadType thr_type = os::java_thread;
1610   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1611                                                      os::java_thread;
1612   os::create_thread(this, thr_type, stack_sz);
1613   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1614   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1615   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1616   // the exception consists of creating the exception object & initializing it, initialization
1617   // will leave the VM via a JavaCall and then all locks must be unlocked).
1618   //
1619   // The thread is still suspended when we reach here. Thread must be explicit started
1620   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1621   // by calling Threads:add. The reason why this is not done here, is because the thread
1622   // object must be fully initialized (take a look at JVM_Start)
1623 }
1624 
1625 JavaThread::~JavaThread() {
1626 
1627   // JSR166 -- return the parker to the free list
1628   Parker::Release(_parker);
1629   _parker = NULL;
1630 
1631   // Free any remaining  previous UnrollBlock
1632   vframeArray* old_array = vframe_array_last();
1633 
1634   if (old_array != NULL) {
1635     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1636     old_array->set_unroll_block(NULL);
1637     delete old_info;
1638     delete old_array;
1639   }
1640 
1641   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1642   if (deferred != NULL) {
1643     // This can only happen if thread is destroyed before deoptimization occurs.
1644     assert(deferred->length() != 0, "empty array!");
1645     do {
1646       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1647       deferred->remove_at(0);
1648       // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1649       delete dlv;
1650     } while (deferred->length() != 0);
1651     delete deferred;
1652   }
1653 
1654   // All Java related clean up happens in exit
1655   ThreadSafepointState::destroy(this);
1656   if (_thread_profiler != NULL) delete _thread_profiler;
1657   if (_thread_stat != NULL) delete _thread_stat;
1658 
1659 #if INCLUDE_JVMCI
1660   if (JVMCICounterSize > 0) {
1661     if (jvmci_counters_include(this)) {
1662       for (int i = 0; i < JVMCICounterSize; i++) {
1663         _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1664       }
1665     }
1666     FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1667   }
1668 #endif // INCLUDE_JVMCI
1669 }
1670 
1671 
1672 // The first routine called by a new Java thread
1673 void JavaThread::run() {
1674   // initialize thread-local alloc buffer related fields
1675   this->initialize_tlab();
1676 
1677   // used to test validity of stack trace backs
1678   this->record_base_of_stack_pointer();
1679 
1680   // Record real stack base and size.
1681   this->record_stack_base_and_size();
1682 
1683   this->create_stack_guard_pages();
1684 
1685   this->cache_global_variables();
1686 
1687   // Thread is now sufficient initialized to be handled by the safepoint code as being
1688   // in the VM. Change thread state from _thread_new to _thread_in_vm
1689   ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1690 
1691   assert(JavaThread::current() == this, "sanity check");
1692   assert(!Thread::current()->owns_locks(), "sanity check");
1693 
1694   DTRACE_THREAD_PROBE(start, this);
1695 
1696   // This operation might block. We call that after all safepoint checks for a new thread has
1697   // been completed.
1698   this->set_active_handles(JNIHandleBlock::allocate_block());
1699 
1700   if (JvmtiExport::should_post_thread_life()) {
1701     JvmtiExport::post_thread_start(this);
1702   }
1703 
1704   EventThreadStart event;
1705   if (event.should_commit()) {
1706     event.set_thread(THREAD_TRACE_ID(this));
1707     event.commit();
1708   }
1709 
1710   // We call another function to do the rest so we are sure that the stack addresses used
1711   // from there will be lower than the stack base just computed
1712   thread_main_inner();
1713 
1714   // Note, thread is no longer valid at this point!
1715 }
1716 
1717 
1718 void JavaThread::thread_main_inner() {
1719   assert(JavaThread::current() == this, "sanity check");
1720   assert(this->threadObj() != NULL, "just checking");
1721 
1722   // Execute thread entry point unless this thread has a pending exception
1723   // or has been stopped before starting.
1724   // Note: Due to JVM_StopThread we can have pending exceptions already!
1725   if (!this->has_pending_exception() &&
1726       !java_lang_Thread::is_stillborn(this->threadObj())) {
1727     {
1728       ResourceMark rm(this);
1729       this->set_native_thread_name(this->get_thread_name());
1730     }
1731     HandleMark hm(this);
1732     this->entry_point()(this, this);
1733   }
1734 
1735   DTRACE_THREAD_PROBE(stop, this);
1736 
1737   this->exit(false);
1738   delete this;
1739 }
1740 
1741 
1742 static void ensure_join(JavaThread* thread) {
1743   // We do not need to grap the Threads_lock, since we are operating on ourself.
1744   Handle threadObj(thread, thread->threadObj());
1745   assert(threadObj.not_null(), "java thread object must exist");
1746   ObjectLocker lock(threadObj, thread);
1747   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1748   thread->clear_pending_exception();
1749   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1750   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1751   // Clear the native thread instance - this makes isAlive return false and allows the join()
1752   // to complete once we've done the notify_all below
1753   java_lang_Thread::set_thread(threadObj(), NULL);
1754   lock.notify_all(thread);
1755   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1756   thread->clear_pending_exception();
1757 }
1758 
1759 
1760 // For any new cleanup additions, please check to see if they need to be applied to
1761 // cleanup_failed_attach_current_thread as well.
1762 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1763   assert(this == JavaThread::current(), "thread consistency check");
1764 
1765   HandleMark hm(this);
1766   Handle uncaught_exception(this, this->pending_exception());
1767   this->clear_pending_exception();
1768   Handle threadObj(this, this->threadObj());
1769   assert(threadObj.not_null(), "Java thread object should be created");
1770 
1771   if (get_thread_profiler() != NULL) {
1772     get_thread_profiler()->disengage();
1773     ResourceMark rm;
1774     get_thread_profiler()->print(get_thread_name());
1775   }
1776 
1777 
1778   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1779   {
1780     EXCEPTION_MARK;
1781 
1782     CLEAR_PENDING_EXCEPTION;
1783   }
1784   if (!destroy_vm) {
1785     if (uncaught_exception.not_null()) {
1786       EXCEPTION_MARK;
1787       // Call method Thread.dispatchUncaughtException().
1788       Klass* thread_klass = SystemDictionary::Thread_klass();
1789       JavaValue result(T_VOID);
1790       JavaCalls::call_virtual(&result,
1791                               threadObj, thread_klass,
1792                               vmSymbols::dispatchUncaughtException_name(),
1793                               vmSymbols::throwable_void_signature(),
1794                               uncaught_exception,
1795                               THREAD);
1796       if (HAS_PENDING_EXCEPTION) {
1797         ResourceMark rm(this);
1798         jio_fprintf(defaultStream::error_stream(),
1799                     "\nException: %s thrown from the UncaughtExceptionHandler"
1800                     " in thread \"%s\"\n",
1801                     pending_exception()->klass()->external_name(),
1802                     get_thread_name());
1803         CLEAR_PENDING_EXCEPTION;
1804       }
1805     }
1806 
1807     // Called before the java thread exit since we want to read info
1808     // from java_lang_Thread object
1809     EventThreadEnd event;
1810     if (event.should_commit()) {
1811       event.set_thread(THREAD_TRACE_ID(this));
1812       event.commit();
1813     }
1814 
1815     // Call after last event on thread
1816     EVENT_THREAD_EXIT(this);
1817 
1818     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1819     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1820     // is deprecated anyhow.
1821     if (!is_Compiler_thread()) {
1822       int count = 3;
1823       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1824         EXCEPTION_MARK;
1825         JavaValue result(T_VOID);
1826         Klass* thread_klass = SystemDictionary::Thread_klass();
1827         JavaCalls::call_virtual(&result,
1828                                 threadObj, thread_klass,
1829                                 vmSymbols::exit_method_name(),
1830                                 vmSymbols::void_method_signature(),
1831                                 THREAD);
1832         CLEAR_PENDING_EXCEPTION;
1833       }
1834     }
1835     // notify JVMTI
1836     if (JvmtiExport::should_post_thread_life()) {
1837       JvmtiExport::post_thread_end(this);
1838     }
1839 
1840     // We have notified the agents that we are exiting, before we go on,
1841     // we must check for a pending external suspend request and honor it
1842     // in order to not surprise the thread that made the suspend request.
1843     while (true) {
1844       {
1845         MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1846         if (!is_external_suspend()) {
1847           set_terminated(_thread_exiting);
1848           ThreadService::current_thread_exiting(this);
1849           break;
1850         }
1851         // Implied else:
1852         // Things get a little tricky here. We have a pending external
1853         // suspend request, but we are holding the SR_lock so we
1854         // can't just self-suspend. So we temporarily drop the lock
1855         // and then self-suspend.
1856       }
1857 
1858       ThreadBlockInVM tbivm(this);
1859       java_suspend_self();
1860 
1861       // We're done with this suspend request, but we have to loop around
1862       // and check again. Eventually we will get SR_lock without a pending
1863       // external suspend request and will be able to mark ourselves as
1864       // exiting.
1865     }
1866     // no more external suspends are allowed at this point
1867   } else {
1868     // before_exit() has already posted JVMTI THREAD_END events
1869   }
1870 
1871   // Notify waiters on thread object. This has to be done after exit() is called
1872   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1873   // group should have the destroyed bit set before waiters are notified).
1874   ensure_join(this);
1875   assert(!this->has_pending_exception(), "ensure_join should have cleared");
1876 
1877   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1878   // held by this thread must be released. The spec does not distinguish
1879   // between JNI-acquired and regular Java monitors. We can only see
1880   // regular Java monitors here if monitor enter-exit matching is broken.
1881   //
1882   // Optionally release any monitors for regular JavaThread exits. This
1883   // is provided as a work around for any bugs in monitor enter-exit
1884   // matching. This can be expensive so it is not enabled by default.
1885   //
1886   // ensure_join() ignores IllegalThreadStateExceptions, and so does
1887   // ObjectSynchronizer::release_monitors_owned_by_thread().
1888   if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1889     // Sanity check even though JNI DetachCurrentThread() would have
1890     // returned JNI_ERR if there was a Java frame. JavaThread exit
1891     // should be done executing Java code by the time we get here.
1892     assert(!this->has_last_Java_frame(),
1893            "should not have a Java frame when detaching or exiting");
1894     ObjectSynchronizer::release_monitors_owned_by_thread(this);
1895     assert(!this->has_pending_exception(), "release_monitors should have cleared");
1896   }
1897 
1898   // These things needs to be done while we are still a Java Thread. Make sure that thread
1899   // is in a consistent state, in case GC happens
1900   assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1901 
1902   if (active_handles() != NULL) {
1903     JNIHandleBlock* block = active_handles();
1904     set_active_handles(NULL);
1905     JNIHandleBlock::release_block(block);
1906   }
1907 
1908   if (free_handle_block() != NULL) {
1909     JNIHandleBlock* block = free_handle_block();
1910     set_free_handle_block(NULL);
1911     JNIHandleBlock::release_block(block);
1912   }
1913 
1914   // These have to be removed while this is still a valid thread.
1915   remove_stack_guard_pages();
1916 
1917   if (UseTLAB) {
1918     tlab().make_parsable(true);  // retire TLAB
1919   }
1920 
1921   if (JvmtiEnv::environments_might_exist()) {
1922     JvmtiExport::cleanup_thread(this);
1923   }
1924 
1925   // We must flush any deferred card marks before removing a thread from
1926   // the list of active threads.
1927   Universe::heap()->flush_deferred_store_barrier(this);
1928   assert(deferred_card_mark().is_empty(), "Should have been flushed");
1929 
1930 #if INCLUDE_ALL_GCS
1931   // We must flush the G1-related buffers before removing a thread
1932   // from the list of active threads. We must do this after any deferred
1933   // card marks have been flushed (above) so that any entries that are
1934   // added to the thread's dirty card queue as a result are not lost.
1935   if (UseG1GC) {
1936     flush_barrier_queues();
1937   }
1938 #endif // INCLUDE_ALL_GCS
1939 
1940   log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
1941     exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
1942     os::current_thread_id());
1943 
1944   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1945   Threads::remove(this);
1946 }
1947 
1948 #if INCLUDE_ALL_GCS
1949 // Flush G1-related queues.
1950 void JavaThread::flush_barrier_queues() {
1951   satb_mark_queue().flush();
1952   dirty_card_queue().flush();
1953 }
1954 
1955 void JavaThread::initialize_queues() {
1956   assert(!SafepointSynchronize::is_at_safepoint(),
1957          "we should not be at a safepoint");
1958 
1959   SATBMarkQueue& satb_queue = satb_mark_queue();
1960   SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1961   // The SATB queue should have been constructed with its active
1962   // field set to false.
1963   assert(!satb_queue.is_active(), "SATB queue should not be active");
1964   assert(satb_queue.is_empty(), "SATB queue should be empty");
1965   // If we are creating the thread during a marking cycle, we should
1966   // set the active field of the SATB queue to true.
1967   if (satb_queue_set.is_active()) {
1968     satb_queue.set_active(true);
1969   }
1970 
1971   DirtyCardQueue& dirty_queue = dirty_card_queue();
1972   // The dirty card queue should have been constructed with its
1973   // active field set to true.
1974   assert(dirty_queue.is_active(), "dirty card queue should be active");
1975 }
1976 #endif // INCLUDE_ALL_GCS
1977 
1978 void JavaThread::cleanup_failed_attach_current_thread() {
1979   if (get_thread_profiler() != NULL) {
1980     get_thread_profiler()->disengage();
1981     ResourceMark rm;
1982     get_thread_profiler()->print(get_thread_name());
1983   }
1984 
1985   if (active_handles() != NULL) {
1986     JNIHandleBlock* block = active_handles();
1987     set_active_handles(NULL);
1988     JNIHandleBlock::release_block(block);
1989   }
1990 
1991   if (free_handle_block() != NULL) {
1992     JNIHandleBlock* block = free_handle_block();
1993     set_free_handle_block(NULL);
1994     JNIHandleBlock::release_block(block);
1995   }
1996 
1997   // These have to be removed while this is still a valid thread.
1998   remove_stack_guard_pages();
1999 
2000   if (UseTLAB) {
2001     tlab().make_parsable(true);  // retire TLAB, if any
2002   }
2003 
2004 #if INCLUDE_ALL_GCS
2005   if (UseG1GC) {
2006     flush_barrier_queues();
2007   }
2008 #endif // INCLUDE_ALL_GCS
2009 
2010   Threads::remove(this);
2011   delete this;
2012 }
2013 
2014 
2015 
2016 
2017 JavaThread* JavaThread::active() {
2018   Thread* thread = Thread::current();
2019   if (thread->is_Java_thread()) {
2020     return (JavaThread*) thread;
2021   } else {
2022     assert(thread->is_VM_thread(), "this must be a vm thread");
2023     VM_Operation* op = ((VMThread*) thread)->vm_operation();
2024     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2025     assert(ret->is_Java_thread(), "must be a Java thread");
2026     return ret;
2027   }
2028 }
2029 
2030 bool JavaThread::is_lock_owned(address adr) const {
2031   if (Thread::is_lock_owned(adr)) return true;
2032 
2033   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2034     if (chunk->contains(adr)) return true;
2035   }
2036 
2037   return false;
2038 }
2039 
2040 
2041 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2042   chunk->set_next(monitor_chunks());
2043   set_monitor_chunks(chunk);
2044 }
2045 
2046 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2047   guarantee(monitor_chunks() != NULL, "must be non empty");
2048   if (monitor_chunks() == chunk) {
2049     set_monitor_chunks(chunk->next());
2050   } else {
2051     MonitorChunk* prev = monitor_chunks();
2052     while (prev->next() != chunk) prev = prev->next();
2053     prev->set_next(chunk->next());
2054   }
2055 }
2056 
2057 // JVM support.
2058 
2059 // Note: this function shouldn't block if it's called in
2060 // _thread_in_native_trans state (such as from
2061 // check_special_condition_for_native_trans()).
2062 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2063 
2064   if (has_last_Java_frame() && has_async_condition()) {
2065     // If we are at a polling page safepoint (not a poll return)
2066     // then we must defer async exception because live registers
2067     // will be clobbered by the exception path. Poll return is
2068     // ok because the call we a returning from already collides
2069     // with exception handling registers and so there is no issue.
2070     // (The exception handling path kills call result registers but
2071     //  this is ok since the exception kills the result anyway).
2072 
2073     if (is_at_poll_safepoint()) {
2074       // if the code we are returning to has deoptimized we must defer
2075       // the exception otherwise live registers get clobbered on the
2076       // exception path before deoptimization is able to retrieve them.
2077       //
2078       RegisterMap map(this, false);
2079       frame caller_fr = last_frame().sender(&map);
2080       assert(caller_fr.is_compiled_frame(), "what?");
2081       if (caller_fr.is_deoptimized_frame()) {
2082         log_info(exceptions)("deferred async exception at compiled safepoint");
2083         return;
2084       }
2085     }
2086   }
2087 
2088   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2089   if (condition == _no_async_condition) {
2090     // Conditions have changed since has_special_runtime_exit_condition()
2091     // was called:
2092     // - if we were here only because of an external suspend request,
2093     //   then that was taken care of above (or cancelled) so we are done
2094     // - if we were here because of another async request, then it has
2095     //   been cleared between the has_special_runtime_exit_condition()
2096     //   and now so again we are done
2097     return;
2098   }
2099 
2100   // Check for pending async. exception
2101   if (_pending_async_exception != NULL) {
2102     // Only overwrite an already pending exception, if it is not a threadDeath.
2103     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2104 
2105       // We cannot call Exceptions::_throw(...) here because we cannot block
2106       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2107 
2108       LogTarget(Info, exceptions) lt;
2109       if (lt.is_enabled()) {
2110         ResourceMark rm;
2111         LogStream ls(lt);
2112         ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2113           if (has_last_Java_frame()) {
2114             frame f = last_frame();
2115            ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2116           }
2117         ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2118       }
2119       _pending_async_exception = NULL;
2120       clear_has_async_exception();
2121     }
2122   }
2123 
2124   if (check_unsafe_error &&
2125       condition == _async_unsafe_access_error && !has_pending_exception()) {
2126     condition = _no_async_condition;  // done
2127     switch (thread_state()) {
2128     case _thread_in_vm: {
2129       JavaThread* THREAD = this;
2130       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2131     }
2132     case _thread_in_native: {
2133       ThreadInVMfromNative tiv(this);
2134       JavaThread* THREAD = this;
2135       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2136     }
2137     case _thread_in_Java: {
2138       ThreadInVMfromJava tiv(this);
2139       JavaThread* THREAD = this;
2140       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2141     }
2142     default:
2143       ShouldNotReachHere();
2144     }
2145   }
2146 
2147   assert(condition == _no_async_condition || has_pending_exception() ||
2148          (!check_unsafe_error && condition == _async_unsafe_access_error),
2149          "must have handled the async condition, if no exception");
2150 }
2151 
2152 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2153   //
2154   // Check for pending external suspend. Internal suspend requests do
2155   // not use handle_special_runtime_exit_condition().
2156   // If JNIEnv proxies are allowed, don't self-suspend if the target
2157   // thread is not the current thread. In older versions of jdbx, jdbx
2158   // threads could call into the VM with another thread's JNIEnv so we
2159   // can be here operating on behalf of a suspended thread (4432884).
2160   bool do_self_suspend = is_external_suspend_with_lock();
2161   if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2162     //
2163     // Because thread is external suspended the safepoint code will count
2164     // thread as at a safepoint. This can be odd because we can be here
2165     // as _thread_in_Java which would normally transition to _thread_blocked
2166     // at a safepoint. We would like to mark the thread as _thread_blocked
2167     // before calling java_suspend_self like all other callers of it but
2168     // we must then observe proper safepoint protocol. (We can't leave
2169     // _thread_blocked with a safepoint in progress). However we can be
2170     // here as _thread_in_native_trans so we can't use a normal transition
2171     // constructor/destructor pair because they assert on that type of
2172     // transition. We could do something like:
2173     //
2174     // JavaThreadState state = thread_state();
2175     // set_thread_state(_thread_in_vm);
2176     // {
2177     //   ThreadBlockInVM tbivm(this);
2178     //   java_suspend_self()
2179     // }
2180     // set_thread_state(_thread_in_vm_trans);
2181     // if (safepoint) block;
2182     // set_thread_state(state);
2183     //
2184     // but that is pretty messy. Instead we just go with the way the
2185     // code has worked before and note that this is the only path to
2186     // java_suspend_self that doesn't put the thread in _thread_blocked
2187     // mode.
2188 
2189     frame_anchor()->make_walkable(this);
2190     java_suspend_self();
2191 
2192     // We might be here for reasons in addition to the self-suspend request
2193     // so check for other async requests.
2194   }
2195 
2196   if (check_asyncs) {
2197     check_and_handle_async_exceptions();
2198   }
2199 #if INCLUDE_TRACE
2200   if (is_trace_suspend()) {
2201     TRACE_SUSPEND_THREAD(this);
2202   }
2203 #endif
2204 }
2205 
2206 void JavaThread::send_thread_stop(oop java_throwable)  {
2207   assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2208   assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2209   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2210 
2211   // Do not throw asynchronous exceptions against the compiler thread
2212   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2213   if (!can_call_java()) return;
2214 
2215   {
2216     // Actually throw the Throwable against the target Thread - however
2217     // only if there is no thread death exception installed already.
2218     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2219       // If the topmost frame is a runtime stub, then we are calling into
2220       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2221       // must deoptimize the caller before continuing, as the compiled  exception handler table
2222       // may not be valid
2223       if (has_last_Java_frame()) {
2224         frame f = last_frame();
2225         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2226           // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2227           RegisterMap reg_map(this, UseBiasedLocking);
2228           frame compiled_frame = f.sender(&reg_map);
2229           if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2230             Deoptimization::deoptimize(this, compiled_frame, &reg_map);
2231           }
2232         }
2233       }
2234 
2235       // Set async. pending exception in thread.
2236       set_pending_async_exception(java_throwable);
2237 
2238       if (log_is_enabled(Info, exceptions)) {
2239          ResourceMark rm;
2240         log_info(exceptions)("Pending Async. exception installed of type: %s",
2241                              InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2242       }
2243       // for AbortVMOnException flag
2244       Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2245     }
2246   }
2247 
2248 
2249   // Interrupt thread so it will wake up from a potential wait()
2250   Thread::interrupt(this);
2251 }
2252 
2253 // External suspension mechanism.
2254 //
2255 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2256 // to any VM_locks and it is at a transition
2257 // Self-suspension will happen on the transition out of the vm.
2258 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2259 //
2260 // Guarantees on return:
2261 //   + Target thread will not execute any new bytecode (that's why we need to
2262 //     force a safepoint)
2263 //   + Target thread will not enter any new monitors
2264 //
2265 void JavaThread::java_suspend() {
2266   { MutexLocker mu(Threads_lock);
2267     if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2268       return;
2269     }
2270   }
2271 
2272   { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2273     if (!is_external_suspend()) {
2274       // a racing resume has cancelled us; bail out now
2275       return;
2276     }
2277 
2278     // suspend is done
2279     uint32_t debug_bits = 0;
2280     // Warning: is_ext_suspend_completed() may temporarily drop the
2281     // SR_lock to allow the thread to reach a stable thread state if
2282     // it is currently in a transient thread state.
2283     if (is_ext_suspend_completed(false /* !called_by_wait */,
2284                                  SuspendRetryDelay, &debug_bits)) {
2285       return;
2286     }
2287   }
2288 
2289   VM_ThreadSuspend vm_suspend;
2290   VMThread::execute(&vm_suspend);
2291 }
2292 
2293 // Part II of external suspension.
2294 // A JavaThread self suspends when it detects a pending external suspend
2295 // request. This is usually on transitions. It is also done in places
2296 // where continuing to the next transition would surprise the caller,
2297 // e.g., monitor entry.
2298 //
2299 // Returns the number of times that the thread self-suspended.
2300 //
2301 // Note: DO NOT call java_suspend_self() when you just want to block current
2302 //       thread. java_suspend_self() is the second stage of cooperative
2303 //       suspension for external suspend requests and should only be used
2304 //       to complete an external suspend request.
2305 //
2306 int JavaThread::java_suspend_self() {
2307   int ret = 0;
2308 
2309   // we are in the process of exiting so don't suspend
2310   if (is_exiting()) {
2311     clear_external_suspend();
2312     return ret;
2313   }
2314 
2315   assert(_anchor.walkable() ||
2316          (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2317          "must have walkable stack");
2318 
2319   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2320 
2321   assert(!this->is_ext_suspended(),
2322          "a thread trying to self-suspend should not already be suspended");
2323 
2324   if (this->is_suspend_equivalent()) {
2325     // If we are self-suspending as a result of the lifting of a
2326     // suspend equivalent condition, then the suspend_equivalent
2327     // flag is not cleared until we set the ext_suspended flag so
2328     // that wait_for_ext_suspend_completion() returns consistent
2329     // results.
2330     this->clear_suspend_equivalent();
2331   }
2332 
2333   // A racing resume may have cancelled us before we grabbed SR_lock
2334   // above. Or another external suspend request could be waiting for us
2335   // by the time we return from SR_lock()->wait(). The thread
2336   // that requested the suspension may already be trying to walk our
2337   // stack and if we return now, we can change the stack out from under
2338   // it. This would be a "bad thing (TM)" and cause the stack walker
2339   // to crash. We stay self-suspended until there are no more pending
2340   // external suspend requests.
2341   while (is_external_suspend()) {
2342     ret++;
2343     this->set_ext_suspended();
2344 
2345     // _ext_suspended flag is cleared by java_resume()
2346     while (is_ext_suspended()) {
2347       this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2348     }
2349   }
2350 
2351   return ret;
2352 }
2353 
2354 #ifdef ASSERT
2355 // verify the JavaThread has not yet been published in the Threads::list, and
2356 // hence doesn't need protection from concurrent access at this stage
2357 void JavaThread::verify_not_published() {
2358   if (!Threads_lock->owned_by_self()) {
2359     MutexLockerEx ml(Threads_lock,  Mutex::_no_safepoint_check_flag);
2360     assert(!Threads::includes(this),
2361            "java thread shouldn't have been published yet!");
2362   } else {
2363     assert(!Threads::includes(this),
2364            "java thread shouldn't have been published yet!");
2365   }
2366 }
2367 #endif
2368 
2369 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2370 // progress or when _suspend_flags is non-zero.
2371 // Current thread needs to self-suspend if there is a suspend request and/or
2372 // block if a safepoint is in progress.
2373 // Async exception ISN'T checked.
2374 // Note only the ThreadInVMfromNative transition can call this function
2375 // directly and when thread state is _thread_in_native_trans
2376 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2377   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2378 
2379   JavaThread *curJT = JavaThread::current();
2380   bool do_self_suspend = thread->is_external_suspend();
2381 
2382   assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2383 
2384   // If JNIEnv proxies are allowed, don't self-suspend if the target
2385   // thread is not the current thread. In older versions of jdbx, jdbx
2386   // threads could call into the VM with another thread's JNIEnv so we
2387   // can be here operating on behalf of a suspended thread (4432884).
2388   if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2389     JavaThreadState state = thread->thread_state();
2390 
2391     // We mark this thread_blocked state as a suspend-equivalent so
2392     // that a caller to is_ext_suspend_completed() won't be confused.
2393     // The suspend-equivalent state is cleared by java_suspend_self().
2394     thread->set_suspend_equivalent();
2395 
2396     // If the safepoint code sees the _thread_in_native_trans state, it will
2397     // wait until the thread changes to other thread state. There is no
2398     // guarantee on how soon we can obtain the SR_lock and complete the
2399     // self-suspend request. It would be a bad idea to let safepoint wait for
2400     // too long. Temporarily change the state to _thread_blocked to
2401     // let the VM thread know that this thread is ready for GC. The problem
2402     // of changing thread state is that safepoint could happen just after
2403     // java_suspend_self() returns after being resumed, and VM thread will
2404     // see the _thread_blocked state. We must check for safepoint
2405     // after restoring the state and make sure we won't leave while a safepoint
2406     // is in progress.
2407     thread->set_thread_state(_thread_blocked);
2408     thread->java_suspend_self();
2409     thread->set_thread_state(state);
2410 
2411     InterfaceSupport::serialize_thread_state_with_handler(thread);
2412   }
2413 
2414   if (SafepointSynchronize::do_call_back()) {
2415     // If we are safepointing, then block the caller which may not be
2416     // the same as the target thread (see above).
2417     SafepointSynchronize::block(curJT);
2418   }
2419 
2420   if (thread->is_deopt_suspend()) {
2421     thread->clear_deopt_suspend();
2422     RegisterMap map(thread, false);
2423     frame f = thread->last_frame();
2424     while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2425       f = f.sender(&map);
2426     }
2427     if (f.id() == thread->must_deopt_id()) {
2428       thread->clear_must_deopt_id();
2429       f.deoptimize(thread);
2430     } else {
2431       fatal("missed deoptimization!");
2432     }
2433   }
2434 #if INCLUDE_TRACE
2435   if (thread->is_trace_suspend()) {
2436     TRACE_SUSPEND_THREAD(thread);
2437   }
2438 #endif
2439 }
2440 
2441 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2442 // progress or when _suspend_flags is non-zero.
2443 // Current thread needs to self-suspend if there is a suspend request and/or
2444 // block if a safepoint is in progress.
2445 // Also check for pending async exception (not including unsafe access error).
2446 // Note only the native==>VM/Java barriers can call this function and when
2447 // thread state is _thread_in_native_trans.
2448 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2449   check_safepoint_and_suspend_for_native_trans(thread);
2450 
2451   if (thread->has_async_exception()) {
2452     // We are in _thread_in_native_trans state, don't handle unsafe
2453     // access error since that may block.
2454     thread->check_and_handle_async_exceptions(false);
2455   }
2456 }
2457 
2458 // This is a variant of the normal
2459 // check_special_condition_for_native_trans with slightly different
2460 // semantics for use by critical native wrappers.  It does all the
2461 // normal checks but also performs the transition back into
2462 // thread_in_Java state.  This is required so that critical natives
2463 // can potentially block and perform a GC if they are the last thread
2464 // exiting the GCLocker.
2465 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2466   check_special_condition_for_native_trans(thread);
2467 
2468   // Finish the transition
2469   thread->set_thread_state(_thread_in_Java);
2470 
2471   if (thread->do_critical_native_unlock()) {
2472     ThreadInVMfromJavaNoAsyncException tiv(thread);
2473     GCLocker::unlock_critical(thread);
2474     thread->clear_critical_native_unlock();
2475   }
2476 }
2477 
2478 // We need to guarantee the Threads_lock here, since resumes are not
2479 // allowed during safepoint synchronization
2480 // Can only resume from an external suspension
2481 void JavaThread::java_resume() {
2482   assert_locked_or_safepoint(Threads_lock);
2483 
2484   // Sanity check: thread is gone, has started exiting or the thread
2485   // was not externally suspended.
2486   if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2487     return;
2488   }
2489 
2490   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2491 
2492   clear_external_suspend();
2493 
2494   if (is_ext_suspended()) {
2495     clear_ext_suspended();
2496     SR_lock()->notify_all();
2497   }
2498 }
2499 
2500 size_t JavaThread::_stack_red_zone_size = 0;
2501 size_t JavaThread::_stack_yellow_zone_size = 0;
2502 size_t JavaThread::_stack_reserved_zone_size = 0;
2503 size_t JavaThread::_stack_shadow_zone_size = 0;
2504 
2505 void JavaThread::create_stack_guard_pages() {
2506   if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; }
2507   address low_addr = stack_end();
2508   size_t len = stack_guard_zone_size();
2509 
2510   int must_commit = os::must_commit_stack_guard_pages();
2511   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2512 
2513   if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2514     log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2515     return;
2516   }
2517 
2518   if (os::guard_memory((char *) low_addr, len)) {
2519     _stack_guard_state = stack_guard_enabled;
2520   } else {
2521     log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2522       PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2523     if (os::uncommit_memory((char *) low_addr, len)) {
2524       log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2525     }
2526     return;
2527   }
2528 
2529   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2530     PTR_FORMAT "-" PTR_FORMAT ".",
2531     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2532 }
2533 
2534 void JavaThread::remove_stack_guard_pages() {
2535   assert(Thread::current() == this, "from different thread");
2536   if (_stack_guard_state == stack_guard_unused) return;
2537   address low_addr = stack_end();
2538   size_t len = stack_guard_zone_size();
2539 
2540   if (os::must_commit_stack_guard_pages()) {
2541     if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2542       _stack_guard_state = stack_guard_unused;
2543     } else {
2544       log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2545         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2546       return;
2547     }
2548   } else {
2549     if (_stack_guard_state == stack_guard_unused) return;
2550     if (os::unguard_memory((char *) low_addr, len)) {
2551       _stack_guard_state = stack_guard_unused;
2552     } else {
2553       log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2554         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2555       return;
2556     }
2557   }
2558 
2559   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2560     PTR_FORMAT "-" PTR_FORMAT ".",
2561     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2562 }
2563 
2564 void JavaThread::enable_stack_reserved_zone() {
2565   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2566   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2567 
2568   // The base notation is from the stack's point of view, growing downward.
2569   // We need to adjust it to work correctly with guard_memory()
2570   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2571 
2572   guarantee(base < stack_base(),"Error calculating stack reserved zone");
2573   guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2574 
2575   if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2576     _stack_guard_state = stack_guard_enabled;
2577   } else {
2578     warning("Attempt to guard stack reserved zone failed.");
2579   }
2580   enable_register_stack_guard();
2581 }
2582 
2583 void JavaThread::disable_stack_reserved_zone() {
2584   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2585   assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2586 
2587   // Simply return if called for a thread that does not use guard pages.
2588   if (_stack_guard_state == stack_guard_unused) return;
2589 
2590   // The base notation is from the stack's point of view, growing downward.
2591   // We need to adjust it to work correctly with guard_memory()
2592   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2593 
2594   if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2595     _stack_guard_state = stack_guard_reserved_disabled;
2596   } else {
2597     warning("Attempt to unguard stack reserved zone failed.");
2598   }
2599   disable_register_stack_guard();
2600 }
2601 
2602 void JavaThread::enable_stack_yellow_reserved_zone() {
2603   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2604   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2605 
2606   // The base notation is from the stacks point of view, growing downward.
2607   // We need to adjust it to work correctly with guard_memory()
2608   address base = stack_red_zone_base();
2609 
2610   guarantee(base < stack_base(), "Error calculating stack yellow zone");
2611   guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2612 
2613   if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2614     _stack_guard_state = stack_guard_enabled;
2615   } else {
2616     warning("Attempt to guard stack yellow zone failed.");
2617   }
2618   enable_register_stack_guard();
2619 }
2620 
2621 void JavaThread::disable_stack_yellow_reserved_zone() {
2622   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2623   assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2624 
2625   // Simply return if called for a thread that does not use guard pages.
2626   if (_stack_guard_state == stack_guard_unused) return;
2627 
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   address base = stack_red_zone_base();
2631 
2632   if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2633     _stack_guard_state = stack_guard_yellow_reserved_disabled;
2634   } else {
2635     warning("Attempt to unguard stack yellow zone failed.");
2636   }
2637   disable_register_stack_guard();
2638 }
2639 
2640 void JavaThread::enable_stack_red_zone() {
2641   // The base notation is from the stacks point of view, growing downward.
2642   // We need to adjust it to work correctly with guard_memory()
2643   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2644   address base = stack_red_zone_base() - stack_red_zone_size();
2645 
2646   guarantee(base < stack_base(), "Error calculating stack red zone");
2647   guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2648 
2649   if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2650     warning("Attempt to guard stack red zone failed.");
2651   }
2652 }
2653 
2654 void JavaThread::disable_stack_red_zone() {
2655   // The base notation is from the stacks point of view, growing downward.
2656   // We need to adjust it to work correctly with guard_memory()
2657   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2658   address base = stack_red_zone_base() - stack_red_zone_size();
2659   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2660     warning("Attempt to unguard stack red zone failed.");
2661   }
2662 }
2663 
2664 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2665   // ignore is there is no stack
2666   if (!has_last_Java_frame()) return;
2667   // traverse the stack frames. Starts from top frame.
2668   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2669     frame* fr = fst.current();
2670     f(fr, fst.register_map());
2671   }
2672 }
2673 
2674 
2675 #ifndef PRODUCT
2676 // Deoptimization
2677 // Function for testing deoptimization
2678 void JavaThread::deoptimize() {
2679   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2680   StackFrameStream fst(this, UseBiasedLocking);
2681   bool deopt = false;           // Dump stack only if a deopt actually happens.
2682   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2683   // Iterate over all frames in the thread and deoptimize
2684   for (; !fst.is_done(); fst.next()) {
2685     if (fst.current()->can_be_deoptimized()) {
2686 
2687       if (only_at) {
2688         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
2689         // consists of comma or carriage return separated numbers so
2690         // search for the current bci in that string.
2691         address pc = fst.current()->pc();
2692         nmethod* nm =  (nmethod*) fst.current()->cb();
2693         ScopeDesc* sd = nm->scope_desc_at(pc);
2694         char buffer[8];
2695         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2696         size_t len = strlen(buffer);
2697         const char * found = strstr(DeoptimizeOnlyAt, buffer);
2698         while (found != NULL) {
2699           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2700               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2701             // Check that the bci found is bracketed by terminators.
2702             break;
2703           }
2704           found = strstr(found + 1, buffer);
2705         }
2706         if (!found) {
2707           continue;
2708         }
2709       }
2710 
2711       if (DebugDeoptimization && !deopt) {
2712         deopt = true; // One-time only print before deopt
2713         tty->print_cr("[BEFORE Deoptimization]");
2714         trace_frames();
2715         trace_stack();
2716       }
2717       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2718     }
2719   }
2720 
2721   if (DebugDeoptimization && deopt) {
2722     tty->print_cr("[AFTER Deoptimization]");
2723     trace_frames();
2724   }
2725 }
2726 
2727 
2728 // Make zombies
2729 void JavaThread::make_zombies() {
2730   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2731     if (fst.current()->can_be_deoptimized()) {
2732       // it is a Java nmethod
2733       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2734       nm->make_not_entrant();
2735     }
2736   }
2737 }
2738 #endif // PRODUCT
2739 
2740 
2741 void JavaThread::deoptimized_wrt_marked_nmethods() {
2742   if (!has_last_Java_frame()) return;
2743   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2744   StackFrameStream fst(this, UseBiasedLocking);
2745   for (; !fst.is_done(); fst.next()) {
2746     if (fst.current()->should_be_deoptimized()) {
2747       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2748     }
2749   }
2750 }
2751 
2752 
2753 // If the caller is a NamedThread, then remember, in the current scope,
2754 // the given JavaThread in its _processed_thread field.
2755 class RememberProcessedThread: public StackObj {
2756   NamedThread* _cur_thr;
2757  public:
2758   RememberProcessedThread(JavaThread* jthr) {
2759     Thread* thread = Thread::current();
2760     if (thread->is_Named_thread()) {
2761       _cur_thr = (NamedThread *)thread;
2762       _cur_thr->set_processed_thread(jthr);
2763     } else {
2764       _cur_thr = NULL;
2765     }
2766   }
2767 
2768   ~RememberProcessedThread() {
2769     if (_cur_thr) {
2770       _cur_thr->set_processed_thread(NULL);
2771     }
2772   }
2773 };
2774 
2775 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2776   // Verify that the deferred card marks have been flushed.
2777   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2778 
2779   // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2780   // since there may be more than one thread using each ThreadProfiler.
2781 
2782   // Traverse the GCHandles
2783   Thread::oops_do(f, cf);
2784 
2785   JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2786 
2787   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2788          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2789 
2790   if (has_last_Java_frame()) {
2791     // Record JavaThread to GC thread
2792     RememberProcessedThread rpt(this);
2793 
2794     // Traverse the privileged stack
2795     if (_privileged_stack_top != NULL) {
2796       _privileged_stack_top->oops_do(f);
2797     }
2798 
2799     // traverse the registered growable array
2800     if (_array_for_gc != NULL) {
2801       for (int index = 0; index < _array_for_gc->length(); index++) {
2802         f->do_oop(_array_for_gc->adr_at(index));
2803       }
2804     }
2805 
2806     // Traverse the monitor chunks
2807     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2808       chunk->oops_do(f);
2809     }
2810 
2811     // Traverse the execution stack
2812     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2813       fst.current()->oops_do(f, cf, fst.register_map());
2814     }
2815   }
2816 
2817   // callee_target is never live across a gc point so NULL it here should
2818   // it still contain a methdOop.
2819 
2820   set_callee_target(NULL);
2821 
2822   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2823   // If we have deferred set_locals there might be oops waiting to be
2824   // written
2825   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2826   if (list != NULL) {
2827     for (int i = 0; i < list->length(); i++) {
2828       list->at(i)->oops_do(f);
2829     }
2830   }
2831 
2832   // Traverse instance variables at the end since the GC may be moving things
2833   // around using this function
2834   f->do_oop((oop*) &_threadObj);
2835   f->do_oop((oop*) &_vm_result);
2836   f->do_oop((oop*) &_exception_oop);
2837   f->do_oop((oop*) &_pending_async_exception);
2838 
2839   if (jvmti_thread_state() != NULL) {
2840     jvmti_thread_state()->oops_do(f);
2841   }
2842 }
2843 
2844 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2845   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2846          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2847 
2848   if (has_last_Java_frame()) {
2849     // Traverse the execution stack
2850     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2851       fst.current()->nmethods_do(cf);
2852     }
2853   }
2854 }
2855 
2856 void JavaThread::metadata_do(void f(Metadata*)) {
2857   if (has_last_Java_frame()) {
2858     // Traverse the execution stack to call f() on the methods in the stack
2859     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2860       fst.current()->metadata_do(f);
2861     }
2862   } else if (is_Compiler_thread()) {
2863     // need to walk ciMetadata in current compile tasks to keep alive.
2864     CompilerThread* ct = (CompilerThread*)this;
2865     if (ct->env() != NULL) {
2866       ct->env()->metadata_do(f);
2867     }
2868     if (ct->task() != NULL) {
2869       ct->task()->metadata_do(f);
2870     }
2871   }
2872 }
2873 
2874 // Printing
2875 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2876   switch (_thread_state) {
2877   case _thread_uninitialized:     return "_thread_uninitialized";
2878   case _thread_new:               return "_thread_new";
2879   case _thread_new_trans:         return "_thread_new_trans";
2880   case _thread_in_native:         return "_thread_in_native";
2881   case _thread_in_native_trans:   return "_thread_in_native_trans";
2882   case _thread_in_vm:             return "_thread_in_vm";
2883   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
2884   case _thread_in_Java:           return "_thread_in_Java";
2885   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
2886   case _thread_blocked:           return "_thread_blocked";
2887   case _thread_blocked_trans:     return "_thread_blocked_trans";
2888   default:                        return "unknown thread state";
2889   }
2890 }
2891 
2892 #ifndef PRODUCT
2893 void JavaThread::print_thread_state_on(outputStream *st) const {
2894   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
2895 };
2896 void JavaThread::print_thread_state() const {
2897   print_thread_state_on(tty);
2898 }
2899 #endif // PRODUCT
2900 
2901 // Called by Threads::print() for VM_PrintThreads operation
2902 void JavaThread::print_on(outputStream *st) const {
2903   st->print_raw("\"");
2904   st->print_raw(get_thread_name());
2905   st->print_raw("\" ");
2906   oop thread_oop = threadObj();
2907   if (thread_oop != NULL) {
2908     st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2909     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
2910     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2911   }
2912   Thread::print_on(st);
2913   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2914   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2915   if (thread_oop != NULL) {
2916     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2917   }
2918 #ifndef PRODUCT
2919   print_thread_state_on(st);
2920   _safepoint_state->print_on(st);
2921 #endif // PRODUCT
2922   if (is_Compiler_thread()) {
2923     CompilerThread* ct = (CompilerThread*)this;
2924     if (ct->task() != NULL) {
2925       st->print("   Compiling: ");
2926       ct->task()->print(st, NULL, true, false);
2927     } else {
2928       st->print("   No compile task");
2929     }
2930     st->cr();
2931   }
2932 }
2933 
2934 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2935   st->print("%s", get_thread_name_string(buf, buflen));
2936 }
2937 
2938 // Called by fatal error handler. The difference between this and
2939 // JavaThread::print() is that we can't grab lock or allocate memory.
2940 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2941   st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2942   oop thread_obj = threadObj();
2943   if (thread_obj != NULL) {
2944     if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2945   }
2946   st->print(" [");
2947   st->print("%s", _get_thread_state_name(_thread_state));
2948   if (osthread()) {
2949     st->print(", id=%d", osthread()->thread_id());
2950   }
2951   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2952             p2i(stack_end()), p2i(stack_base()));
2953   st->print("]");
2954   return;
2955 }
2956 
2957 // Verification
2958 
2959 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2960 
2961 void JavaThread::verify() {
2962   // Verify oops in the thread.
2963   oops_do(&VerifyOopClosure::verify_oop, NULL);
2964 
2965   // Verify the stack frames.
2966   frames_do(frame_verify);
2967 }
2968 
2969 // CR 6300358 (sub-CR 2137150)
2970 // Most callers of this method assume that it can't return NULL but a
2971 // thread may not have a name whilst it is in the process of attaching to
2972 // the VM - see CR 6412693, and there are places where a JavaThread can be
2973 // seen prior to having it's threadObj set (eg JNI attaching threads and
2974 // if vm exit occurs during initialization). These cases can all be accounted
2975 // for such that this method never returns NULL.
2976 const char* JavaThread::get_thread_name() const {
2977 #ifdef ASSERT
2978   // early safepoints can hit while current thread does not yet have TLS
2979   if (!SafepointSynchronize::is_at_safepoint()) {
2980     Thread *cur = Thread::current();
2981     if (!(cur->is_Java_thread() && cur == this)) {
2982       // Current JavaThreads are allowed to get their own name without
2983       // the Threads_lock.
2984       assert_locked_or_safepoint(Threads_lock);
2985     }
2986   }
2987 #endif // ASSERT
2988   return get_thread_name_string();
2989 }
2990 
2991 // Returns a non-NULL representation of this thread's name, or a suitable
2992 // descriptive string if there is no set name
2993 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2994   const char* name_str;
2995   oop thread_obj = threadObj();
2996   if (thread_obj != NULL) {
2997     oop name = java_lang_Thread::name(thread_obj);
2998     if (name != NULL) {
2999       if (buf == NULL) {
3000         name_str = java_lang_String::as_utf8_string(name);
3001       } else {
3002         name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3003       }
3004     } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3005       name_str = "<no-name - thread is attaching>";
3006     } else {
3007       name_str = Thread::name();
3008     }
3009   } else {
3010     name_str = Thread::name();
3011   }
3012   assert(name_str != NULL, "unexpected NULL thread name");
3013   return name_str;
3014 }
3015 
3016 
3017 const char* JavaThread::get_threadgroup_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       // ThreadGroup.name can be null
3024       return java_lang_ThreadGroup::name(thread_group);
3025     }
3026   }
3027   return NULL;
3028 }
3029 
3030 const char* JavaThread::get_parent_name() const {
3031   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3032   oop thread_obj = threadObj();
3033   if (thread_obj != NULL) {
3034     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3035     if (thread_group != NULL) {
3036       oop parent = java_lang_ThreadGroup::parent(thread_group);
3037       if (parent != NULL) {
3038         // ThreadGroup.name can be null
3039         return java_lang_ThreadGroup::name(parent);
3040       }
3041     }
3042   }
3043   return NULL;
3044 }
3045 
3046 ThreadPriority JavaThread::java_priority() const {
3047   oop thr_oop = threadObj();
3048   if (thr_oop == NULL) return NormPriority; // Bootstrapping
3049   ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3050   assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3051   return priority;
3052 }
3053 
3054 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3055 
3056   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3057   // Link Java Thread object <-> C++ Thread
3058 
3059   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3060   // and put it into a new Handle.  The Handle "thread_oop" can then
3061   // be used to pass the C++ thread object to other methods.
3062 
3063   // Set the Java level thread object (jthread) field of the
3064   // new thread (a JavaThread *) to C++ thread object using the
3065   // "thread_oop" handle.
3066 
3067   // Set the thread field (a JavaThread *) of the
3068   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3069 
3070   Handle thread_oop(Thread::current(),
3071                     JNIHandles::resolve_non_null(jni_thread));
3072   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3073          "must be initialized");
3074   set_threadObj(thread_oop());
3075   java_lang_Thread::set_thread(thread_oop(), this);
3076 
3077   if (prio == NoPriority) {
3078     prio = java_lang_Thread::priority(thread_oop());
3079     assert(prio != NoPriority, "A valid priority should be present");
3080   }
3081 
3082   // Push the Java priority down to the native thread; needs Threads_lock
3083   Thread::set_priority(this, prio);
3084 
3085   prepare_ext();
3086 
3087   // Add the new thread to the Threads list and set it in motion.
3088   // We must have threads lock in order to call Threads::add.
3089   // It is crucial that we do not block before the thread is
3090   // added to the Threads list for if a GC happens, then the java_thread oop
3091   // will not be visited by GC.
3092   Threads::add(this);
3093 }
3094 
3095 oop JavaThread::current_park_blocker() {
3096   // Support for JSR-166 locks
3097   oop thread_oop = threadObj();
3098   if (thread_oop != NULL &&
3099       JDK_Version::current().supports_thread_park_blocker()) {
3100     return java_lang_Thread::park_blocker(thread_oop);
3101   }
3102   return NULL;
3103 }
3104 
3105 
3106 void JavaThread::print_stack_on(outputStream* st) {
3107   if (!has_last_Java_frame()) return;
3108   ResourceMark rm;
3109   HandleMark   hm;
3110 
3111   RegisterMap reg_map(this);
3112   vframe* start_vf = last_java_vframe(&reg_map);
3113   int count = 0;
3114   for (vframe* f = start_vf; f; f = f->sender()) {
3115     if (f->is_java_frame()) {
3116       javaVFrame* jvf = javaVFrame::cast(f);
3117       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3118 
3119       // Print out lock information
3120       if (JavaMonitorsInStackTrace) {
3121         jvf->print_lock_info_on(st, count);
3122       }
3123     } else {
3124       // Ignore non-Java frames
3125     }
3126 
3127     // Bail-out case for too deep stacks
3128     count++;
3129     if (MaxJavaStackTraceDepth == count) return;
3130   }
3131 }
3132 
3133 
3134 // JVMTI PopFrame support
3135 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3136   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3137   if (in_bytes(size_in_bytes) != 0) {
3138     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3139     _popframe_preserved_args_size = in_bytes(size_in_bytes);
3140     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3141   }
3142 }
3143 
3144 void* JavaThread::popframe_preserved_args() {
3145   return _popframe_preserved_args;
3146 }
3147 
3148 ByteSize JavaThread::popframe_preserved_args_size() {
3149   return in_ByteSize(_popframe_preserved_args_size);
3150 }
3151 
3152 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3153   int sz = in_bytes(popframe_preserved_args_size());
3154   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3155   return in_WordSize(sz / wordSize);
3156 }
3157 
3158 void JavaThread::popframe_free_preserved_args() {
3159   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3160   FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3161   _popframe_preserved_args = NULL;
3162   _popframe_preserved_args_size = 0;
3163 }
3164 
3165 #ifndef PRODUCT
3166 
3167 void JavaThread::trace_frames() {
3168   tty->print_cr("[Describe stack]");
3169   int frame_no = 1;
3170   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3171     tty->print("  %d. ", frame_no++);
3172     fst.current()->print_value_on(tty, this);
3173     tty->cr();
3174   }
3175 }
3176 
3177 class PrintAndVerifyOopClosure: public OopClosure {
3178  protected:
3179   template <class T> inline void do_oop_work(T* p) {
3180     oop obj = oopDesc::load_decode_heap_oop(p);
3181     if (obj == NULL) return;
3182     tty->print(INTPTR_FORMAT ": ", p2i(p));
3183     if (obj->is_oop_or_null()) {
3184       if (obj->is_objArray()) {
3185         tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3186       } else {
3187         obj->print();
3188       }
3189     } else {
3190       tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3191     }
3192     tty->cr();
3193   }
3194  public:
3195   virtual void do_oop(oop* p) { do_oop_work(p); }
3196   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
3197 };
3198 
3199 
3200 static void oops_print(frame* f, const RegisterMap *map) {
3201   PrintAndVerifyOopClosure print;
3202   f->print_value();
3203   f->oops_do(&print, NULL, (RegisterMap*)map);
3204 }
3205 
3206 // Print our all the locations that contain oops and whether they are
3207 // valid or not.  This useful when trying to find the oldest frame
3208 // where an oop has gone bad since the frame walk is from youngest to
3209 // oldest.
3210 void JavaThread::trace_oops() {
3211   tty->print_cr("[Trace oops]");
3212   frames_do(oops_print);
3213 }
3214 
3215 
3216 #ifdef ASSERT
3217 // Print or validate the layout of stack frames
3218 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3219   ResourceMark rm;
3220   PRESERVE_EXCEPTION_MARK;
3221   FrameValues values;
3222   int frame_no = 0;
3223   for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3224     fst.current()->describe(values, ++frame_no);
3225     if (depth == frame_no) break;
3226   }
3227   if (validate_only) {
3228     values.validate();
3229   } else {
3230     tty->print_cr("[Describe stack layout]");
3231     values.print(this);
3232   }
3233 }
3234 #endif
3235 
3236 void JavaThread::trace_stack_from(vframe* start_vf) {
3237   ResourceMark rm;
3238   int vframe_no = 1;
3239   for (vframe* f = start_vf; f; f = f->sender()) {
3240     if (f->is_java_frame()) {
3241       javaVFrame::cast(f)->print_activation(vframe_no++);
3242     } else {
3243       f->print();
3244     }
3245     if (vframe_no > StackPrintLimit) {
3246       tty->print_cr("...<more frames>...");
3247       return;
3248     }
3249   }
3250 }
3251 
3252 
3253 void JavaThread::trace_stack() {
3254   if (!has_last_Java_frame()) return;
3255   ResourceMark rm;
3256   HandleMark   hm;
3257   RegisterMap reg_map(this);
3258   trace_stack_from(last_java_vframe(&reg_map));
3259 }
3260 
3261 
3262 #endif // PRODUCT
3263 
3264 
3265 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3266   assert(reg_map != NULL, "a map must be given");
3267   frame f = last_frame();
3268   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3269     if (vf->is_java_frame()) return javaVFrame::cast(vf);
3270   }
3271   return NULL;
3272 }
3273 
3274 
3275 Klass* JavaThread::security_get_caller_class(int depth) {
3276   vframeStream vfst(this);
3277   vfst.security_get_caller_frame(depth);
3278   if (!vfst.at_end()) {
3279     return vfst.method()->method_holder();
3280   }
3281   return NULL;
3282 }
3283 
3284 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3285   assert(thread->is_Compiler_thread(), "must be compiler thread");
3286   CompileBroker::compiler_thread_loop();
3287 }
3288 
3289 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3290   NMethodSweeper::sweeper_loop();
3291 }
3292 
3293 // Create a CompilerThread
3294 CompilerThread::CompilerThread(CompileQueue* queue,
3295                                CompilerCounters* counters)
3296                                : JavaThread(&compiler_thread_entry) {
3297   _env   = NULL;
3298   _log   = NULL;
3299   _task  = NULL;
3300   _queue = queue;
3301   _counters = counters;
3302   _buffer_blob = NULL;
3303   _compiler = NULL;
3304 
3305 #ifndef PRODUCT
3306   _ideal_graph_printer = NULL;
3307 #endif
3308 }
3309 
3310 bool CompilerThread::can_call_java() const {
3311   return _compiler != NULL && _compiler->is_jvmci();
3312 }
3313 
3314 // Create sweeper thread
3315 CodeCacheSweeperThread::CodeCacheSweeperThread()
3316 : JavaThread(&sweeper_thread_entry) {
3317   _scanned_compiled_method = NULL;
3318 }
3319 
3320 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3321   JavaThread::oops_do(f, cf);
3322   if (_scanned_compiled_method != NULL && cf != NULL) {
3323     // Safepoints can occur when the sweeper is scanning an nmethod so
3324     // process it here to make sure it isn't unloaded in the middle of
3325     // a scan.
3326     cf->do_code_blob(_scanned_compiled_method);
3327   }
3328 }
3329 
3330 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3331   JavaThread::nmethods_do(cf);
3332   if (_scanned_compiled_method != NULL && cf != NULL) {
3333     // Safepoints can occur when the sweeper is scanning an nmethod so
3334     // process it here to make sure it isn't unloaded in the middle of
3335     // a scan.
3336     cf->do_code_blob(_scanned_compiled_method);
3337   }
3338 }
3339 
3340 
3341 // ======= Threads ========
3342 
3343 // The Threads class links together all active threads, and provides
3344 // operations over all threads.  It is protected by its own Mutex
3345 // lock, which is also used in other contexts to protect thread
3346 // operations from having the thread being operated on from exiting
3347 // and going away unexpectedly (e.g., safepoint synchronization)
3348 
3349 JavaThread* Threads::_thread_list = NULL;
3350 int         Threads::_number_of_threads = 0;
3351 int         Threads::_number_of_non_daemon_threads = 0;
3352 int         Threads::_return_code = 0;
3353 int         Threads::_thread_claim_parity = 0;
3354 size_t      JavaThread::_stack_size_at_create = 0;
3355 #ifdef ASSERT
3356 bool        Threads::_vm_complete = false;
3357 #endif
3358 
3359 // All JavaThreads
3360 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3361 
3362 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3363 void Threads::threads_do(ThreadClosure* tc) {
3364   assert_locked_or_safepoint(Threads_lock);
3365   // ALL_JAVA_THREADS iterates through all JavaThreads
3366   ALL_JAVA_THREADS(p) {
3367     tc->do_thread(p);
3368   }
3369   // Someday we could have a table or list of all non-JavaThreads.
3370   // For now, just manually iterate through them.
3371   tc->do_thread(VMThread::vm_thread());
3372   Universe::heap()->gc_threads_do(tc);
3373   WatcherThread *wt = WatcherThread::watcher_thread();
3374   // Strictly speaking, the following NULL check isn't sufficient to make sure
3375   // the data for WatcherThread is still valid upon being examined. However,
3376   // considering that WatchThread terminates when the VM is on the way to
3377   // exit at safepoint, the chance of the above is extremely small. The right
3378   // way to prevent termination of WatcherThread would be to acquire
3379   // Terminator_lock, but we can't do that without violating the lock rank
3380   // checking in some cases.
3381   if (wt != NULL) {
3382     tc->do_thread(wt);
3383   }
3384 
3385   // If CompilerThreads ever become non-JavaThreads, add them here
3386 }
3387 
3388 void Threads::parallel_java_threads_do(ThreadClosure* tc) {
3389   int cp = Threads::thread_claim_parity();
3390   ALL_JAVA_THREADS(p) {
3391     if (p->claim_oops_do(true, cp)) {
3392       tc->do_thread(p);
3393     }
3394   }
3395   // Thread claiming protocol requires us to claim the same interesting
3396   // threads on all paths. Notably, Threads::possibly_parallel_threads_do
3397   // claims all Java threads *and* the VMThread. To avoid breaking the
3398   // claiming protocol, we have to claim VMThread on this path too, even
3399   // if we do not apply the closure to the VMThread.
3400   VMThread* vmt = VMThread::vm_thread();
3401   (void)vmt->claim_oops_do(true, cp);
3402 }
3403 
3404 // The system initialization in the library has three phases.
3405 //
3406 // Phase 1: java.lang.System class initialization
3407 //     java.lang.System is a primordial class loaded and initialized
3408 //     by the VM early during startup.  java.lang.System.<clinit>
3409 //     only does registerNatives and keeps the rest of the class
3410 //     initialization work later until thread initialization completes.
3411 //
3412 //     System.initPhase1 initializes the system properties, the static
3413 //     fields in, out, and err. Set up java signal handlers, OS-specific
3414 //     system settings, and thread group of the main thread.
3415 static void call_initPhase1(TRAPS) {
3416   Klass* klass =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3417   JavaValue result(T_VOID);
3418   JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3419                                          vmSymbols::void_method_signature(), CHECK);
3420 }
3421 
3422 // Phase 2. Module system initialization
3423 //     This will initialize the module system.  Only java.base classes
3424 //     can be loaded until phase 2 completes.
3425 //
3426 //     Call System.initPhase2 after the compiler initialization and jsr292
3427 //     classes get initialized because module initialization runs a lot of java
3428 //     code, that for performance reasons, should be compiled.  Also, this will
3429 //     enable the startup code to use lambda and other language features in this
3430 //     phase and onward.
3431 //
3432 //     After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3433 static void call_initPhase2(TRAPS) {
3434   TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3435 
3436   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3437 
3438   JavaValue result(T_INT);
3439   JavaCallArguments args;
3440   args.push_int(DisplayVMOutputToStderr);
3441   args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3442   JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3443                                          vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3444   if (result.get_jint() != JNI_OK) {
3445     vm_exit_during_initialization(); // no message or exception
3446   }
3447 
3448   universe_post_module_init();
3449 }
3450 
3451 // Phase 3. final setup - set security manager, system class loader and TCCL
3452 //
3453 //     This will instantiate and set the security manager, set the system class
3454 //     loader as well as the thread context class loader.  The security manager
3455 //     and system class loader may be a custom class loaded from -Xbootclasspath/a,
3456 //     other modules or the application's classpath.
3457 static void call_initPhase3(TRAPS) {
3458   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3459   JavaValue result(T_VOID);
3460   JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3461                                          vmSymbols::void_method_signature(), CHECK);
3462 }
3463 
3464 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3465   TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3466 
3467   if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3468     create_vm_init_libraries();
3469   }
3470 
3471   initialize_class(vmSymbols::java_lang_String(), CHECK);
3472 
3473   // Inject CompactStrings value after the static initializers for String ran.
3474   java_lang_String::set_compact_strings(CompactStrings);
3475 
3476   // Initialize java_lang.System (needed before creating the thread)
3477   initialize_class(vmSymbols::java_lang_System(), CHECK);
3478   // The VM creates & returns objects of this class. Make sure it's initialized.
3479   initialize_class(vmSymbols::java_lang_Class(), CHECK);
3480   initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3481   Handle thread_group = create_initial_thread_group(CHECK);
3482   Universe::set_main_thread_group(thread_group());
3483   initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3484   oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3485   main_thread->set_threadObj(thread_object);
3486   // Set thread status to running since main thread has
3487   // been started and running.
3488   java_lang_Thread::set_thread_status(thread_object,
3489                                       java_lang_Thread::RUNNABLE);
3490 
3491   // The VM creates objects of this class.
3492   initialize_class(vmSymbols::java_lang_Module(), CHECK);
3493 
3494   // The VM preresolves methods to these classes. Make sure that they get initialized
3495   initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3496   initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3497 
3498   // Phase 1 of the system initialization in the library, java.lang.System class initialization
3499   call_initPhase1(CHECK);
3500 
3501   // get the Java runtime name after java.lang.System is initialized
3502   JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3503   JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3504 
3505   // an instance of OutOfMemory exception has been allocated earlier
3506   initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3507   initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3508   initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3509   initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3510   initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3511   initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3512   initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3513   initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3514 }
3515 
3516 void Threads::initialize_jsr292_core_classes(TRAPS) {
3517   TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3518 
3519   initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3520   initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3521   initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3522   initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3523 }
3524 
3525 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3526   extern void JDK_Version_init();
3527 
3528   // Preinitialize version info.
3529   VM_Version::early_initialize();
3530 
3531   // Check version
3532   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3533 
3534   // Initialize library-based TLS
3535   ThreadLocalStorage::init();
3536 
3537   // Initialize the output stream module
3538   ostream_init();
3539 
3540   // Process java launcher properties.
3541   Arguments::process_sun_java_launcher_properties(args);
3542 
3543   // Initialize the os module
3544   os::init();
3545 
3546   // Record VM creation timing statistics
3547   TraceVmCreationTime create_vm_timer;
3548   create_vm_timer.start();
3549 
3550   // Initialize system properties.
3551   Arguments::init_system_properties();
3552 
3553   // So that JDK version can be used as a discriminator when parsing arguments
3554   JDK_Version_init();
3555 
3556   // Update/Initialize System properties after JDK version number is known
3557   Arguments::init_version_specific_system_properties();
3558 
3559   // Make sure to initialize log configuration *before* parsing arguments
3560   LogConfiguration::initialize(create_vm_timer.begin_time());
3561 
3562   // Parse arguments
3563   jint parse_result = Arguments::parse(args);
3564   if (parse_result != JNI_OK) return parse_result;
3565 
3566   os::init_before_ergo();
3567 
3568   jint ergo_result = Arguments::apply_ergo();
3569   if (ergo_result != JNI_OK) return ergo_result;
3570 
3571   // Final check of all ranges after ergonomics which may change values.
3572   if (!CommandLineFlagRangeList::check_ranges()) {
3573     return JNI_EINVAL;
3574   }
3575 
3576   // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3577   bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3578   if (!constraint_result) {
3579     return JNI_EINVAL;
3580   }
3581 
3582   CommandLineFlagWriteableList::mark_startup();
3583 
3584   if (PauseAtStartup) {
3585     os::pause();
3586   }
3587 
3588   HOTSPOT_VM_INIT_BEGIN();
3589 
3590   // Timing (must come after argument parsing)
3591   TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3592 
3593   // Initialize the os module after parsing the args
3594   jint os_init_2_result = os::init_2();
3595   if (os_init_2_result != JNI_OK) return os_init_2_result;
3596 
3597   jint adjust_after_os_result = Arguments::adjust_after_os();
3598   if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3599 
3600   // Initialize output stream logging
3601   ostream_init_log();
3602 
3603   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3604   // Must be before create_vm_init_agents()
3605   if (Arguments::init_libraries_at_startup()) {
3606     convert_vm_init_libraries_to_agents();
3607   }
3608 
3609   // Launch -agentlib/-agentpath and converted -Xrun agents
3610   if (Arguments::init_agents_at_startup()) {
3611     create_vm_init_agents();
3612   }
3613 
3614   // Initialize Threads state
3615   _thread_list = NULL;
3616   _number_of_threads = 0;
3617   _number_of_non_daemon_threads = 0;
3618 
3619   // Initialize global data structures and create system classes in heap
3620   vm_init_globals();
3621 
3622 #if INCLUDE_JVMCI
3623   if (JVMCICounterSize > 0) {
3624     JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3625     memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3626   } else {
3627     JavaThread::_jvmci_old_thread_counters = NULL;
3628   }
3629 #endif // INCLUDE_JVMCI
3630 
3631   // Attach the main thread to this os thread
3632   JavaThread* main_thread = new JavaThread();
3633   main_thread->set_thread_state(_thread_in_vm);
3634   main_thread->initialize_thread_current();
3635   // must do this before set_active_handles
3636   main_thread->record_stack_base_and_size();
3637   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3638 
3639   if (!main_thread->set_as_starting_thread()) {
3640     vm_shutdown_during_initialization(
3641                                       "Failed necessary internal allocation. Out of swap space");
3642     delete main_thread;
3643     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3644     return JNI_ENOMEM;
3645   }
3646 
3647   // Enable guard page *after* os::create_main_thread(), otherwise it would
3648   // crash Linux VM, see notes in os_linux.cpp.
3649   main_thread->create_stack_guard_pages();
3650 
3651   // Initialize Java-Level synchronization subsystem
3652   ObjectMonitor::Initialize();
3653 
3654   // Initialize global modules
3655   jint status = init_globals();
3656   if (status != JNI_OK) {
3657     delete main_thread;
3658     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3659     return status;
3660   }
3661 
3662   if (TRACE_INITIALIZE() != JNI_OK) {
3663     vm_exit_during_initialization("Failed to initialize tracing backend");
3664   }
3665 
3666   // Should be done after the heap is fully created
3667   main_thread->cache_global_variables();
3668 
3669   HandleMark hm;
3670 
3671   { MutexLocker mu(Threads_lock);
3672     Threads::add(main_thread);
3673   }
3674 
3675   // Any JVMTI raw monitors entered in onload will transition into
3676   // real raw monitor. VM is setup enough here for raw monitor enter.
3677   JvmtiExport::transition_pending_onload_raw_monitors();
3678 
3679   // Create the VMThread
3680   { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3681 
3682   VMThread::create();
3683     Thread* vmthread = VMThread::vm_thread();
3684 
3685     if (!os::create_thread(vmthread, os::vm_thread)) {
3686       vm_exit_during_initialization("Cannot create VM thread. "
3687                                     "Out of system resources.");
3688     }
3689 
3690     // Wait for the VM thread to become ready, and VMThread::run to initialize
3691     // Monitors can have spurious returns, must always check another state flag
3692     {
3693       MutexLocker ml(Notify_lock);
3694       os::start_thread(vmthread);
3695       while (vmthread->active_handles() == NULL) {
3696         Notify_lock->wait();
3697       }
3698     }
3699   }
3700 
3701   assert(Universe::is_fully_initialized(), "not initialized");
3702   if (VerifyDuringStartup) {
3703     // Make sure we're starting with a clean slate.
3704     VM_Verify verify_op;
3705     VMThread::execute(&verify_op);
3706   }
3707 
3708   Thread* THREAD = Thread::current();
3709 
3710   // At this point, the Universe is initialized, but we have not executed
3711   // any byte code.  Now is a good time (the only time) to dump out the
3712   // internal state of the JVM for sharing.
3713   if (DumpSharedSpaces) {
3714     MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3715     ShouldNotReachHere();
3716   }
3717 
3718   // Always call even when there are not JVMTI environments yet, since environments
3719   // may be attached late and JVMTI must track phases of VM execution
3720   JvmtiExport::enter_early_start_phase();
3721 
3722   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3723   JvmtiExport::post_early_vm_start();
3724 
3725   initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3726 
3727   // We need this for ClassDataSharing - the initial vm.info property is set
3728   // with the default value of CDS "sharing" which may be reset through
3729   // command line options.
3730   reset_vm_info_property(CHECK_JNI_ERR);
3731 
3732   quicken_jni_functions();
3733 
3734   // No more stub generation allowed after that point.
3735   StubCodeDesc::freeze();
3736 
3737   // Set flag that basic initialization has completed. Used by exceptions and various
3738   // debug stuff, that does not work until all basic classes have been initialized.
3739   set_init_completed();
3740 
3741   LogConfiguration::post_initialize();
3742   Metaspace::post_initialize();
3743 
3744   HOTSPOT_VM_INIT_END();
3745 
3746   // record VM initialization completion time
3747 #if INCLUDE_MANAGEMENT
3748   Management::record_vm_init_completed();
3749 #endif // INCLUDE_MANAGEMENT
3750 
3751   // Signal Dispatcher needs to be started before VMInit event is posted
3752   os::signal_init(CHECK_JNI_ERR);
3753 
3754   // Start Attach Listener if +StartAttachListener or it can't be started lazily
3755   if (!DisableAttachMechanism) {
3756     AttachListener::vm_start();
3757     if (StartAttachListener || AttachListener::init_at_startup()) {
3758       AttachListener::init();
3759     }
3760   }
3761 
3762   // Launch -Xrun agents
3763   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3764   // back-end can launch with -Xdebug -Xrunjdwp.
3765   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3766     create_vm_init_libraries();
3767   }
3768 
3769   if (CleanChunkPoolAsync) {
3770     Chunk::start_chunk_pool_cleaner_task();
3771   }
3772 
3773   // initialize compiler(s)
3774 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI
3775   CompileBroker::compilation_init(CHECK_JNI_ERR);
3776 #endif
3777 
3778   // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3779   // It is done after compilers are initialized, because otherwise compilations of
3780   // signature polymorphic MH intrinsics can be missed
3781   // (see SystemDictionary::find_method_handle_intrinsic).
3782   initialize_jsr292_core_classes(CHECK_JNI_ERR);
3783 
3784   // This will initialize the module system.  Only java.base classes can be
3785   // loaded until phase 2 completes
3786   call_initPhase2(CHECK_JNI_ERR);
3787 
3788   // Always call even when there are not JVMTI environments yet, since environments
3789   // may be attached late and JVMTI must track phases of VM execution
3790   JvmtiExport::enter_start_phase();
3791 
3792   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3793   JvmtiExport::post_vm_start();
3794 
3795   // Final system initialization including security manager and system class loader
3796   call_initPhase3(CHECK_JNI_ERR);
3797 
3798   // cache the system class loader
3799   SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR));
3800 
3801 #if INCLUDE_JVMCI
3802   if (EnableJVMCI) {
3803     // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled.
3804     // The JVMCI Java initialization code will read this flag and
3805     // do the printing if it's set.
3806     bool init = JVMCIPrintProperties;
3807 
3808     if (!init) {
3809       // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3810       // compilations via JVMCI will not actually block until JVMCI is initialized.
3811       init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3812     }
3813 
3814     if (init) {
3815       JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3816     }
3817   }
3818 #endif
3819 
3820   // Always call even when there are not JVMTI environments yet, since environments
3821   // may be attached late and JVMTI must track phases of VM execution
3822   JvmtiExport::enter_live_phase();
3823 
3824   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3825   JvmtiExport::post_vm_initialized();
3826 
3827   if (TRACE_START() != JNI_OK) {
3828     vm_exit_during_initialization("Failed to start tracing backend.");
3829   }
3830 
3831 #if INCLUDE_MANAGEMENT
3832   Management::initialize(THREAD);
3833 
3834   if (HAS_PENDING_EXCEPTION) {
3835     // management agent fails to start possibly due to
3836     // configuration problem and is responsible for printing
3837     // stack trace if appropriate. Simply exit VM.
3838     vm_exit(1);
3839   }
3840 #endif // INCLUDE_MANAGEMENT
3841 
3842   if (Arguments::has_profile())       FlatProfiler::engage(main_thread, true);
3843   if (MemProfiling)                   MemProfiler::engage();
3844   StatSampler::engage();
3845   if (CheckJNICalls)                  JniPeriodicChecker::engage();
3846 
3847   BiasedLocking::init();
3848 
3849 #if INCLUDE_RTM_OPT
3850   RTMLockingCounters::init();
3851 #endif
3852 
3853   if (JDK_Version::current().post_vm_init_hook_enabled()) {
3854     call_postVMInitHook(THREAD);
3855     // The Java side of PostVMInitHook.run must deal with all
3856     // exceptions and provide means of diagnosis.
3857     if (HAS_PENDING_EXCEPTION) {
3858       CLEAR_PENDING_EXCEPTION;
3859     }
3860   }
3861 
3862   {
3863     MutexLocker ml(PeriodicTask_lock);
3864     // Make sure the WatcherThread can be started by WatcherThread::start()
3865     // or by dynamic enrollment.
3866     WatcherThread::make_startable();
3867     // Start up the WatcherThread if there are any periodic tasks
3868     // NOTE:  All PeriodicTasks should be registered by now. If they
3869     //   aren't, late joiners might appear to start slowly (we might
3870     //   take a while to process their first tick).
3871     if (PeriodicTask::num_tasks() > 0) {
3872       WatcherThread::start();
3873     }
3874   }
3875 
3876   create_vm_timer.end();
3877 #ifdef ASSERT
3878   _vm_complete = true;
3879 #endif
3880   return JNI_OK;
3881 }
3882 
3883 // type for the Agent_OnLoad and JVM_OnLoad entry points
3884 extern "C" {
3885   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3886 }
3887 // Find a command line agent library and return its entry point for
3888 //         -agentlib:  -agentpath:   -Xrun
3889 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3890 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3891                                     const char *on_load_symbols[],
3892                                     size_t num_symbol_entries) {
3893   OnLoadEntry_t on_load_entry = NULL;
3894   void *library = NULL;
3895 
3896   if (!agent->valid()) {
3897     char buffer[JVM_MAXPATHLEN];
3898     char ebuf[1024] = "";
3899     const char *name = agent->name();
3900     const char *msg = "Could not find agent library ";
3901 
3902     // First check to see if agent is statically linked into executable
3903     if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3904       library = agent->os_lib();
3905     } else if (agent->is_absolute_path()) {
3906       library = os::dll_load(name, ebuf, sizeof ebuf);
3907       if (library == NULL) {
3908         const char *sub_msg = " in absolute path, with error: ";
3909         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3910         char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3911         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3912         // If we can't find the agent, exit.
3913         vm_exit_during_initialization(buf, NULL);
3914         FREE_C_HEAP_ARRAY(char, buf);
3915       }
3916     } else {
3917       // Try to load the agent from the standard dll directory
3918       if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3919                              name)) {
3920         library = os::dll_load(buffer, ebuf, sizeof ebuf);
3921       }
3922       if (library == NULL) { // Try the local directory
3923         char ns[1] = {0};
3924         if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3925           library = os::dll_load(buffer, ebuf, sizeof ebuf);
3926         }
3927         if (library == NULL) {
3928           const char *sub_msg = " on the library path, with error: ";
3929           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3930           char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3931           jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3932           // If we can't find the agent, exit.
3933           vm_exit_during_initialization(buf, NULL);
3934           FREE_C_HEAP_ARRAY(char, buf);
3935         }
3936       }
3937     }
3938     agent->set_os_lib(library);
3939     agent->set_valid();
3940   }
3941 
3942   // Find the OnLoad function.
3943   on_load_entry =
3944     CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3945                                                           false,
3946                                                           on_load_symbols,
3947                                                           num_symbol_entries));
3948   return on_load_entry;
3949 }
3950 
3951 // Find the JVM_OnLoad entry point
3952 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3953   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3954   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3955 }
3956 
3957 // Find the Agent_OnLoad entry point
3958 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3959   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3960   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3961 }
3962 
3963 // For backwards compatibility with -Xrun
3964 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3965 // treated like -agentpath:
3966 // Must be called before agent libraries are created
3967 void Threads::convert_vm_init_libraries_to_agents() {
3968   AgentLibrary* agent;
3969   AgentLibrary* next;
3970 
3971   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3972     next = agent->next();  // cache the next agent now as this agent may get moved off this list
3973     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3974 
3975     // If there is an JVM_OnLoad function it will get called later,
3976     // otherwise see if there is an Agent_OnLoad
3977     if (on_load_entry == NULL) {
3978       on_load_entry = lookup_agent_on_load(agent);
3979       if (on_load_entry != NULL) {
3980         // switch it to the agent list -- so that Agent_OnLoad will be called,
3981         // JVM_OnLoad won't be attempted and Agent_OnUnload will
3982         Arguments::convert_library_to_agent(agent);
3983       } else {
3984         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3985       }
3986     }
3987   }
3988 }
3989 
3990 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
3991 // Invokes Agent_OnLoad
3992 // Called very early -- before JavaThreads exist
3993 void Threads::create_vm_init_agents() {
3994   extern struct JavaVM_ main_vm;
3995   AgentLibrary* agent;
3996 
3997   JvmtiExport::enter_onload_phase();
3998 
3999   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4000     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
4001 
4002     if (on_load_entry != NULL) {
4003       // Invoke the Agent_OnLoad function
4004       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4005       if (err != JNI_OK) {
4006         vm_exit_during_initialization("agent library failed to init", agent->name());
4007       }
4008     } else {
4009       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4010     }
4011   }
4012   JvmtiExport::enter_primordial_phase();
4013 }
4014 
4015 extern "C" {
4016   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4017 }
4018 
4019 void Threads::shutdown_vm_agents() {
4020   // Send any Agent_OnUnload notifications
4021   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4022   size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4023   extern struct JavaVM_ main_vm;
4024   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4025 
4026     // Find the Agent_OnUnload function.
4027     Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4028                                                    os::find_agent_function(agent,
4029                                                    false,
4030                                                    on_unload_symbols,
4031                                                    num_symbol_entries));
4032 
4033     // Invoke the Agent_OnUnload function
4034     if (unload_entry != NULL) {
4035       JavaThread* thread = JavaThread::current();
4036       ThreadToNativeFromVM ttn(thread);
4037       HandleMark hm(thread);
4038       (*unload_entry)(&main_vm);
4039     }
4040   }
4041 }
4042 
4043 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4044 // Invokes JVM_OnLoad
4045 void Threads::create_vm_init_libraries() {
4046   extern struct JavaVM_ main_vm;
4047   AgentLibrary* agent;
4048 
4049   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4050     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4051 
4052     if (on_load_entry != NULL) {
4053       // Invoke the JVM_OnLoad function
4054       JavaThread* thread = JavaThread::current();
4055       ThreadToNativeFromVM ttn(thread);
4056       HandleMark hm(thread);
4057       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4058       if (err != JNI_OK) {
4059         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4060       }
4061     } else {
4062       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4063     }
4064   }
4065 }
4066 
4067 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
4068   assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
4069 
4070   JavaThread* java_thread = NULL;
4071   // Sequential search for now.  Need to do better optimization later.
4072   for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
4073     oop tobj = thread->threadObj();
4074     if (!thread->is_exiting() &&
4075         tobj != NULL &&
4076         java_tid == java_lang_Thread::thread_id(tobj)) {
4077       java_thread = thread;
4078       break;
4079     }
4080   }
4081   return java_thread;
4082 }
4083 
4084 
4085 // Last thread running calls java.lang.Shutdown.shutdown()
4086 void JavaThread::invoke_shutdown_hooks() {
4087   HandleMark hm(this);
4088 
4089   // We could get here with a pending exception, if so clear it now.
4090   if (this->has_pending_exception()) {
4091     this->clear_pending_exception();
4092   }
4093 
4094   EXCEPTION_MARK;
4095   Klass* shutdown_klass =
4096     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4097                                       THREAD);
4098   if (shutdown_klass != NULL) {
4099     // SystemDictionary::resolve_or_null will return null if there was
4100     // an exception.  If we cannot load the Shutdown class, just don't
4101     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
4102     // and finalizers (if runFinalizersOnExit is set) won't be run.
4103     // Note that if a shutdown hook was registered or runFinalizersOnExit
4104     // was called, the Shutdown class would have already been loaded
4105     // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4106     JavaValue result(T_VOID);
4107     JavaCalls::call_static(&result,
4108                            shutdown_klass,
4109                            vmSymbols::shutdown_method_name(),
4110                            vmSymbols::void_method_signature(),
4111                            THREAD);
4112   }
4113   CLEAR_PENDING_EXCEPTION;
4114 }
4115 
4116 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4117 // the program falls off the end of main(). Another VM exit path is through
4118 // vm_exit() when the program calls System.exit() to return a value or when
4119 // there is a serious error in VM. The two shutdown paths are not exactly
4120 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4121 // and VM_Exit op at VM level.
4122 //
4123 // Shutdown sequence:
4124 //   + Shutdown native memory tracking if it is on
4125 //   + Wait until we are the last non-daemon thread to execute
4126 //     <-- every thing is still working at this moment -->
4127 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4128 //        shutdown hooks, run finalizers if finalization-on-exit
4129 //   + Call before_exit(), prepare for VM exit
4130 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4131 //        currently the only user of this mechanism is File.deleteOnExit())
4132 //      > stop flat profiler, StatSampler, watcher thread, CMS threads,
4133 //        post thread end and vm death events to JVMTI,
4134 //        stop signal thread
4135 //   + Call JavaThread::exit(), it will:
4136 //      > release JNI handle blocks, remove stack guard pages
4137 //      > remove this thread from Threads list
4138 //     <-- no more Java code from this thread after this point -->
4139 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4140 //     the compiler threads at safepoint
4141 //     <-- do not use anything that could get blocked by Safepoint -->
4142 //   + Disable tracing at JNI/JVM barriers
4143 //   + Set _vm_exited flag for threads that are still running native code
4144 //   + Delete this thread
4145 //   + Call exit_globals()
4146 //      > deletes tty
4147 //      > deletes PerfMemory resources
4148 //   + Return to caller
4149 
4150 bool Threads::destroy_vm() {
4151   JavaThread* thread = JavaThread::current();
4152 
4153 #ifdef ASSERT
4154   _vm_complete = false;
4155 #endif
4156   // Wait until we are the last non-daemon thread to execute
4157   { MutexLocker nu(Threads_lock);
4158     while (Threads::number_of_non_daemon_threads() > 1)
4159       // This wait should make safepoint checks, wait without a timeout,
4160       // and wait as a suspend-equivalent condition.
4161       //
4162       // Note: If the FlatProfiler is running and this thread is waiting
4163       // for another non-daemon thread to finish, then the FlatProfiler
4164       // is waiting for the external suspend request on this thread to
4165       // complete. wait_for_ext_suspend_completion() will eventually
4166       // timeout, but that takes time. Making this wait a suspend-
4167       // equivalent condition solves that timeout problem.
4168       //
4169       Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4170                          Mutex::_as_suspend_equivalent_flag);
4171   }
4172 
4173   // Hang forever on exit if we are reporting an error.
4174   if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4175     os::infinite_sleep();
4176   }
4177   os::wait_for_keypress_at_exit();
4178 
4179   // run Java level shutdown hooks
4180   thread->invoke_shutdown_hooks();
4181 
4182   before_exit(thread);
4183 
4184   thread->exit(true);
4185 
4186   // Stop VM thread.
4187   {
4188     // 4945125 The vm thread comes to a safepoint during exit.
4189     // GC vm_operations can get caught at the safepoint, and the
4190     // heap is unparseable if they are caught. Grab the Heap_lock
4191     // to prevent this. The GC vm_operations will not be able to
4192     // queue until after the vm thread is dead. After this point,
4193     // we'll never emerge out of the safepoint before the VM exits.
4194 
4195     MutexLocker ml(Heap_lock);
4196 
4197     VMThread::wait_for_vm_thread_exit();
4198     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4199     VMThread::destroy();
4200   }
4201 
4202   // clean up ideal graph printers
4203 #if defined(COMPILER2) && !defined(PRODUCT)
4204   IdealGraphPrinter::clean_up();
4205 #endif
4206 
4207   // Now, all Java threads are gone except daemon threads. Daemon threads
4208   // running Java code or in VM are stopped by the Safepoint. However,
4209   // daemon threads executing native code are still running.  But they
4210   // will be stopped at native=>Java/VM barriers. Note that we can't
4211   // simply kill or suspend them, as it is inherently deadlock-prone.
4212 
4213   VM_Exit::set_vm_exited();
4214 
4215   notify_vm_shutdown();
4216 
4217   delete thread;
4218 
4219 #if INCLUDE_JVMCI
4220   if (JVMCICounterSize > 0) {
4221     FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4222   }
4223 #endif
4224 
4225   // exit_globals() will delete tty
4226   exit_globals();
4227 
4228   LogConfiguration::finalize();
4229 
4230   return true;
4231 }
4232 
4233 
4234 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4235   if (version == JNI_VERSION_1_1) return JNI_TRUE;
4236   return is_supported_jni_version(version);
4237 }
4238 
4239 
4240 jboolean Threads::is_supported_jni_version(jint version) {
4241   if (version == JNI_VERSION_1_2) return JNI_TRUE;
4242   if (version == JNI_VERSION_1_4) return JNI_TRUE;
4243   if (version == JNI_VERSION_1_6) return JNI_TRUE;
4244   if (version == JNI_VERSION_1_8) return JNI_TRUE;
4245   if (version == JNI_VERSION_9) return JNI_TRUE;
4246   return JNI_FALSE;
4247 }
4248 
4249 
4250 void Threads::add(JavaThread* p, bool force_daemon) {
4251   // The threads lock must be owned at this point
4252   assert_locked_or_safepoint(Threads_lock);
4253 
4254   // See the comment for this method in thread.hpp for its purpose and
4255   // why it is called here.
4256   p->initialize_queues();
4257   p->set_next(_thread_list);
4258   _thread_list = p;
4259   _number_of_threads++;
4260   oop threadObj = p->threadObj();
4261   bool daemon = true;
4262   // Bootstrapping problem: threadObj can be null for initial
4263   // JavaThread (or for threads attached via JNI)
4264   if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4265     _number_of_non_daemon_threads++;
4266     daemon = false;
4267   }
4268 
4269   ThreadService::add_thread(p, daemon);
4270 
4271   // Possible GC point.
4272   Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4273 }
4274 
4275 void Threads::remove(JavaThread* p) {
4276 
4277   // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
4278   ObjectSynchronizer::omFlush(p);
4279 
4280   // Extra scope needed for Thread_lock, so we can check
4281   // that we do not remove thread without safepoint code notice
4282   { MutexLocker ml(Threads_lock);
4283 
4284     assert(includes(p), "p must be present");
4285 
4286     JavaThread* current = _thread_list;
4287     JavaThread* prev    = NULL;
4288 
4289     while (current != p) {
4290       prev    = current;
4291       current = current->next();
4292     }
4293 
4294     if (prev) {
4295       prev->set_next(current->next());
4296     } else {
4297       _thread_list = p->next();
4298     }
4299     _number_of_threads--;
4300     oop threadObj = p->threadObj();
4301     bool daemon = true;
4302     if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4303       _number_of_non_daemon_threads--;
4304       daemon = false;
4305 
4306       // Only one thread left, do a notify on the Threads_lock so a thread waiting
4307       // on destroy_vm will wake up.
4308       if (number_of_non_daemon_threads() == 1) {
4309         Threads_lock->notify_all();
4310       }
4311     }
4312     ThreadService::remove_thread(p, daemon);
4313 
4314     // Make sure that safepoint code disregard this thread. This is needed since
4315     // the thread might mess around with locks after this point. This can cause it
4316     // to do callbacks into the safepoint code. However, the safepoint code is not aware
4317     // of this thread since it is removed from the queue.
4318     p->set_terminated_value();
4319   } // unlock Threads_lock
4320 
4321   // Since Events::log uses a lock, we grab it outside the Threads_lock
4322   Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4323 }
4324 
4325 // Threads_lock must be held when this is called (or must be called during a safepoint)
4326 bool Threads::includes(JavaThread* p) {
4327   assert(Threads_lock->is_locked(), "sanity check");
4328   ALL_JAVA_THREADS(q) {
4329     if (q == p) {
4330       return true;
4331     }
4332   }
4333   return false;
4334 }
4335 
4336 // Operations on the Threads list for GC.  These are not explicitly locked,
4337 // but the garbage collector must provide a safe context for them to run.
4338 // In particular, these things should never be called when the Threads_lock
4339 // is held by some other thread. (Note: the Safepoint abstraction also
4340 // uses the Threads_lock to guarantee this property. It also makes sure that
4341 // all threads gets blocked when exiting or starting).
4342 
4343 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4344   ALL_JAVA_THREADS(p) {
4345     p->oops_do(f, cf);
4346   }
4347   VMThread::vm_thread()->oops_do(f, cf);
4348 }
4349 
4350 void Threads::change_thread_claim_parity() {
4351   // Set the new claim parity.
4352   assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4353          "Not in range.");
4354   _thread_claim_parity++;
4355   if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4356   assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4357          "Not in range.");
4358 }
4359 
4360 #ifdef ASSERT
4361 void Threads::assert_all_threads_claimed() {
4362   ALL_JAVA_THREADS(p) {
4363     const int thread_parity = p->oops_do_parity();
4364     assert((thread_parity == _thread_claim_parity),
4365            "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4366   }
4367   VMThread* vmt = VMThread::vm_thread();
4368   const int thread_parity = vmt->oops_do_parity();
4369   assert((thread_parity == _thread_claim_parity),
4370          "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity);
4371 }
4372 #endif // ASSERT
4373 
4374 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4375   int cp = Threads::thread_claim_parity();
4376   ALL_JAVA_THREADS(p) {
4377     if (p->claim_oops_do(is_par, cp)) {
4378       p->oops_do(f, cf);
4379     }
4380   }
4381   VMThread* vmt = VMThread::vm_thread();
4382   if (vmt->claim_oops_do(is_par, cp)) {
4383     vmt->oops_do(f, cf);
4384   }
4385 }
4386 
4387 #if INCLUDE_ALL_GCS
4388 // Used by ParallelScavenge
4389 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4390   ALL_JAVA_THREADS(p) {
4391     q->enqueue(new ThreadRootsTask(p));
4392   }
4393   q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4394 }
4395 
4396 // Used by Parallel Old
4397 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4398   ALL_JAVA_THREADS(p) {
4399     q->enqueue(new ThreadRootsMarkingTask(p));
4400   }
4401   q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4402 }
4403 #endif // INCLUDE_ALL_GCS
4404 
4405 void Threads::nmethods_do(CodeBlobClosure* cf) {
4406   ALL_JAVA_THREADS(p) {
4407     // This is used by the code cache sweeper to mark nmethods that are active
4408     // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4409     // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4410     if(!p->is_Code_cache_sweeper_thread()) {
4411       p->nmethods_do(cf);
4412     }
4413   }
4414 }
4415 
4416 void Threads::metadata_do(void f(Metadata*)) {
4417   ALL_JAVA_THREADS(p) {
4418     p->metadata_do(f);
4419   }
4420 }
4421 
4422 class ThreadHandlesClosure : public ThreadClosure {
4423   void (*_f)(Metadata*);
4424  public:
4425   ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4426   virtual void do_thread(Thread* thread) {
4427     thread->metadata_handles_do(_f);
4428   }
4429 };
4430 
4431 void Threads::metadata_handles_do(void f(Metadata*)) {
4432   // Only walk the Handles in Thread.
4433   ThreadHandlesClosure handles_closure(f);
4434   threads_do(&handles_closure);
4435 }
4436 
4437 void Threads::deoptimized_wrt_marked_nmethods() {
4438   ALL_JAVA_THREADS(p) {
4439     p->deoptimized_wrt_marked_nmethods();
4440   }
4441 }
4442 
4443 
4444 // Get count Java threads that are waiting to enter the specified monitor.
4445 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4446                                                          address monitor,
4447                                                          bool doLock) {
4448   assert(doLock || SafepointSynchronize::is_at_safepoint(),
4449          "must grab Threads_lock or be at safepoint");
4450   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4451 
4452   int i = 0;
4453   {
4454     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4455     ALL_JAVA_THREADS(p) {
4456       if (!p->can_call_java()) continue;
4457 
4458       address pending = (address)p->current_pending_monitor();
4459       if (pending == monitor) {             // found a match
4460         if (i < count) result->append(p);   // save the first count matches
4461         i++;
4462       }
4463     }
4464   }
4465   return result;
4466 }
4467 
4468 
4469 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4470                                                       bool doLock) {
4471   assert(doLock ||
4472          Threads_lock->owned_by_self() ||
4473          SafepointSynchronize::is_at_safepoint(),
4474          "must grab Threads_lock or be at safepoint");
4475 
4476   // NULL owner means not locked so we can skip the search
4477   if (owner == NULL) return NULL;
4478 
4479   {
4480     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4481     ALL_JAVA_THREADS(p) {
4482       // first, see if owner is the address of a Java thread
4483       if (owner == (address)p) return p;
4484     }
4485   }
4486   // Cannot assert on lack of success here since this function may be
4487   // used by code that is trying to report useful problem information
4488   // like deadlock detection.
4489   if (UseHeavyMonitors) return NULL;
4490 
4491   // If we didn't find a matching Java thread and we didn't force use of
4492   // heavyweight monitors, then the owner is the stack address of the
4493   // Lock Word in the owning Java thread's stack.
4494   //
4495   JavaThread* the_owner = NULL;
4496   {
4497     MutexLockerEx ml(doLock ? Threads_lock : NULL);
4498     ALL_JAVA_THREADS(q) {
4499       if (q->is_lock_owned(owner)) {
4500         the_owner = q;
4501         break;
4502       }
4503     }
4504   }
4505   // cannot assert on lack of success here; see above comment
4506   return the_owner;
4507 }
4508 
4509 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4510 void Threads::print_on(outputStream* st, bool print_stacks,
4511                        bool internal_format, bool print_concurrent_locks) {
4512   char buf[32];
4513   st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4514 
4515   st->print_cr("Full thread dump %s (%s %s):",
4516                Abstract_VM_Version::vm_name(),
4517                Abstract_VM_Version::vm_release(),
4518                Abstract_VM_Version::vm_info_string());
4519   st->cr();
4520 
4521 #if INCLUDE_SERVICES
4522   // Dump concurrent locks
4523   ConcurrentLocksDump concurrent_locks;
4524   if (print_concurrent_locks) {
4525     concurrent_locks.dump_at_safepoint();
4526   }
4527 #endif // INCLUDE_SERVICES
4528 
4529   ALL_JAVA_THREADS(p) {
4530     ResourceMark rm;
4531     p->print_on(st);
4532     if (print_stacks) {
4533       if (internal_format) {
4534         p->trace_stack();
4535       } else {
4536         p->print_stack_on(st);
4537       }
4538     }
4539     st->cr();
4540 #if INCLUDE_SERVICES
4541     if (print_concurrent_locks) {
4542       concurrent_locks.print_locks_on(p, st);
4543     }
4544 #endif // INCLUDE_SERVICES
4545   }
4546 
4547   VMThread::vm_thread()->print_on(st);
4548   st->cr();
4549   Universe::heap()->print_gc_threads_on(st);
4550   WatcherThread* wt = WatcherThread::watcher_thread();
4551   if (wt != NULL) {
4552     wt->print_on(st);
4553     st->cr();
4554   }
4555   st->flush();
4556 }
4557 
4558 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4559                              int buflen, bool* found_current) {
4560   if (this_thread != NULL) {
4561     bool is_current = (current == this_thread);
4562     *found_current = *found_current || is_current;
4563     st->print("%s", is_current ? "=>" : "  ");
4564 
4565     st->print(PTR_FORMAT, p2i(this_thread));
4566     st->print(" ");
4567     this_thread->print_on_error(st, buf, buflen);
4568     st->cr();
4569   }
4570 }
4571 
4572 class PrintOnErrorClosure : public ThreadClosure {
4573   outputStream* _st;
4574   Thread* _current;
4575   char* _buf;
4576   int _buflen;
4577   bool* _found_current;
4578  public:
4579   PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4580                       int buflen, bool* found_current) :
4581    _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4582 
4583   virtual void do_thread(Thread* thread) {
4584     Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4585   }
4586 };
4587 
4588 // Threads::print_on_error() is called by fatal error handler. It's possible
4589 // that VM is not at safepoint and/or current thread is inside signal handler.
4590 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4591 // memory (even in resource area), it might deadlock the error handler.
4592 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4593                              int buflen) {
4594   bool found_current = false;
4595   st->print_cr("Java Threads: ( => current thread )");
4596   ALL_JAVA_THREADS(thread) {
4597     print_on_error(thread, st, current, buf, buflen, &found_current);
4598   }
4599   st->cr();
4600 
4601   st->print_cr("Other Threads:");
4602   print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4603   print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4604 
4605   PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4606   Universe::heap()->gc_threads_do(&print_closure);
4607 
4608   if (!found_current) {
4609     st->cr();
4610     st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4611     current->print_on_error(st, buf, buflen);
4612     st->cr();
4613   }
4614   st->cr();
4615   st->print_cr("Threads with active compile tasks:");
4616   print_threads_compiling(st, buf, buflen);
4617 }
4618 
4619 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4620   ALL_JAVA_THREADS(thread) {
4621     if (thread->is_Compiler_thread()) {
4622       CompilerThread* ct = (CompilerThread*) thread;
4623       if (ct->task() != NULL) {
4624         thread->print_name_on_error(st, buf, buflen);
4625         ct->task()->print(st, NULL, true, true);
4626       }
4627     }
4628   }
4629 }
4630 
4631 
4632 // Internal SpinLock and Mutex
4633 // Based on ParkEvent
4634 
4635 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4636 //
4637 // We employ SpinLocks _only for low-contention, fixed-length
4638 // short-duration critical sections where we're concerned
4639 // about native mutex_t or HotSpot Mutex:: latency.
4640 // The mux construct provides a spin-then-block mutual exclusion
4641 // mechanism.
4642 //
4643 // Testing has shown that contention on the ListLock guarding gFreeList
4644 // is common.  If we implement ListLock as a simple SpinLock it's common
4645 // for the JVM to devolve to yielding with little progress.  This is true
4646 // despite the fact that the critical sections protected by ListLock are
4647 // extremely short.
4648 //
4649 // TODO-FIXME: ListLock should be of type SpinLock.
4650 // We should make this a 1st-class type, integrated into the lock
4651 // hierarchy as leaf-locks.  Critically, the SpinLock structure
4652 // should have sufficient padding to avoid false-sharing and excessive
4653 // cache-coherency traffic.
4654 
4655 
4656 typedef volatile int SpinLockT;
4657 
4658 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4659   if (Atomic::cmpxchg (1, adr, 0) == 0) {
4660     return;   // normal fast-path return
4661   }
4662 
4663   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4664   TEVENT(SpinAcquire - ctx);
4665   int ctr = 0;
4666   int Yields = 0;
4667   for (;;) {
4668     while (*adr != 0) {
4669       ++ctr;
4670       if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4671         if (Yields > 5) {
4672           os::naked_short_sleep(1);
4673         } else {
4674           os::naked_yield();
4675           ++Yields;
4676         }
4677       } else {
4678         SpinPause();
4679       }
4680     }
4681     if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4682   }
4683 }
4684 
4685 void Thread::SpinRelease(volatile int * adr) {
4686   assert(*adr != 0, "invariant");
4687   OrderAccess::fence();      // guarantee at least release consistency.
4688   // Roach-motel semantics.
4689   // It's safe if subsequent LDs and STs float "up" into the critical section,
4690   // but prior LDs and STs within the critical section can't be allowed
4691   // to reorder or float past the ST that releases the lock.
4692   // Loads and stores in the critical section - which appear in program
4693   // order before the store that releases the lock - must also appear
4694   // before the store that releases the lock in memory visibility order.
4695   // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4696   // the ST of 0 into the lock-word which releases the lock, so fence
4697   // more than covers this on all platforms.
4698   *adr = 0;
4699 }
4700 
4701 // muxAcquire and muxRelease:
4702 //
4703 // *  muxAcquire and muxRelease support a single-word lock-word construct.
4704 //    The LSB of the word is set IFF the lock is held.
4705 //    The remainder of the word points to the head of a singly-linked list
4706 //    of threads blocked on the lock.
4707 //
4708 // *  The current implementation of muxAcquire-muxRelease uses its own
4709 //    dedicated Thread._MuxEvent instance.  If we're interested in
4710 //    minimizing the peak number of extant ParkEvent instances then
4711 //    we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4712 //    as certain invariants were satisfied.  Specifically, care would need
4713 //    to be taken with regards to consuming unpark() "permits".
4714 //    A safe rule of thumb is that a thread would never call muxAcquire()
4715 //    if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4716 //    park().  Otherwise the _ParkEvent park() operation in muxAcquire() could
4717 //    consume an unpark() permit intended for monitorenter, for instance.
4718 //    One way around this would be to widen the restricted-range semaphore
4719 //    implemented in park().  Another alternative would be to provide
4720 //    multiple instances of the PlatformEvent() for each thread.  One
4721 //    instance would be dedicated to muxAcquire-muxRelease, for instance.
4722 //
4723 // *  Usage:
4724 //    -- Only as leaf locks
4725 //    -- for short-term locking only as muxAcquire does not perform
4726 //       thread state transitions.
4727 //
4728 // Alternatives:
4729 // *  We could implement muxAcquire and muxRelease with MCS or CLH locks
4730 //    but with parking or spin-then-park instead of pure spinning.
4731 // *  Use Taura-Oyama-Yonenzawa locks.
4732 // *  It's possible to construct a 1-0 lock if we encode the lockword as
4733 //    (List,LockByte).  Acquire will CAS the full lockword while Release
4734 //    will STB 0 into the LockByte.  The 1-0 scheme admits stranding, so
4735 //    acquiring threads use timers (ParkTimed) to detect and recover from
4736 //    the stranding window.  Thread/Node structures must be aligned on 256-byte
4737 //    boundaries by using placement-new.
4738 // *  Augment MCS with advisory back-link fields maintained with CAS().
4739 //    Pictorially:  LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4740 //    The validity of the backlinks must be ratified before we trust the value.
4741 //    If the backlinks are invalid the exiting thread must back-track through the
4742 //    the forward links, which are always trustworthy.
4743 // *  Add a successor indication.  The LockWord is currently encoded as
4744 //    (List, LOCKBIT:1).  We could also add a SUCCBIT or an explicit _succ variable
4745 //    to provide the usual futile-wakeup optimization.
4746 //    See RTStt for details.
4747 // *  Consider schedctl.sc_nopreempt to cover the critical section.
4748 //
4749 
4750 
4751 typedef volatile intptr_t MutexT;      // Mux Lock-word
4752 enum MuxBits { LOCKBIT = 1 };
4753 
4754 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4755   intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4756   if (w == 0) return;
4757   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4758     return;
4759   }
4760 
4761   TEVENT(muxAcquire - Contention);
4762   ParkEvent * const Self = Thread::current()->_MuxEvent;
4763   assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4764   for (;;) {
4765     int its = (os::is_MP() ? 100 : 0) + 1;
4766 
4767     // Optional spin phase: spin-then-park strategy
4768     while (--its >= 0) {
4769       w = *Lock;
4770       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4771         return;
4772       }
4773     }
4774 
4775     Self->reset();
4776     Self->OnList = intptr_t(Lock);
4777     // The following fence() isn't _strictly necessary as the subsequent
4778     // CAS() both serializes execution and ratifies the fetched *Lock value.
4779     OrderAccess::fence();
4780     for (;;) {
4781       w = *Lock;
4782       if ((w & LOCKBIT) == 0) {
4783         if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4784           Self->OnList = 0;   // hygiene - allows stronger asserts
4785           return;
4786         }
4787         continue;      // Interference -- *Lock changed -- Just retry
4788       }
4789       assert(w & LOCKBIT, "invariant");
4790       Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4791       if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4792     }
4793 
4794     while (Self->OnList != 0) {
4795       Self->park();
4796     }
4797   }
4798 }
4799 
4800 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4801   intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4802   if (w == 0) return;
4803   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4804     return;
4805   }
4806 
4807   TEVENT(muxAcquire - Contention);
4808   ParkEvent * ReleaseAfter = NULL;
4809   if (ev == NULL) {
4810     ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4811   }
4812   assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4813   for (;;) {
4814     guarantee(ev->OnList == 0, "invariant");
4815     int its = (os::is_MP() ? 100 : 0) + 1;
4816 
4817     // Optional spin phase: spin-then-park strategy
4818     while (--its >= 0) {
4819       w = *Lock;
4820       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4821         if (ReleaseAfter != NULL) {
4822           ParkEvent::Release(ReleaseAfter);
4823         }
4824         return;
4825       }
4826     }
4827 
4828     ev->reset();
4829     ev->OnList = intptr_t(Lock);
4830     // The following fence() isn't _strictly necessary as the subsequent
4831     // CAS() both serializes execution and ratifies the fetched *Lock value.
4832     OrderAccess::fence();
4833     for (;;) {
4834       w = *Lock;
4835       if ((w & LOCKBIT) == 0) {
4836         if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4837           ev->OnList = 0;
4838           // We call ::Release while holding the outer lock, thus
4839           // artificially lengthening the critical section.
4840           // Consider deferring the ::Release() until the subsequent unlock(),
4841           // after we've dropped the outer lock.
4842           if (ReleaseAfter != NULL) {
4843             ParkEvent::Release(ReleaseAfter);
4844           }
4845           return;
4846         }
4847         continue;      // Interference -- *Lock changed -- Just retry
4848       }
4849       assert(w & LOCKBIT, "invariant");
4850       ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4851       if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4852     }
4853 
4854     while (ev->OnList != 0) {
4855       ev->park();
4856     }
4857   }
4858 }
4859 
4860 // Release() must extract a successor from the list and then wake that thread.
4861 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4862 // similar to that used by ParkEvent::Allocate() and ::Release().  DMR-based
4863 // Release() would :
4864 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4865 // (B) Extract a successor from the private list "in-hand"
4866 // (C) attempt to CAS() the residual back into *Lock over null.
4867 //     If there were any newly arrived threads and the CAS() would fail.
4868 //     In that case Release() would detach the RATs, re-merge the list in-hand
4869 //     with the RATs and repeat as needed.  Alternately, Release() might
4870 //     detach and extract a successor, but then pass the residual list to the wakee.
4871 //     The wakee would be responsible for reattaching and remerging before it
4872 //     competed for the lock.
4873 //
4874 // Both "pop" and DMR are immune from ABA corruption -- there can be
4875 // multiple concurrent pushers, but only one popper or detacher.
4876 // This implementation pops from the head of the list.  This is unfair,
4877 // but tends to provide excellent throughput as hot threads remain hot.
4878 // (We wake recently run threads first).
4879 //
4880 // All paths through muxRelease() will execute a CAS.
4881 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4882 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4883 // executed within the critical section are complete and globally visible before the
4884 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4885 void Thread::muxRelease(volatile intptr_t * Lock)  {
4886   for (;;) {
4887     const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4888     assert(w & LOCKBIT, "invariant");
4889     if (w == LOCKBIT) return;
4890     ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4891     assert(List != NULL, "invariant");
4892     assert(List->OnList == intptr_t(Lock), "invariant");
4893     ParkEvent * const nxt = List->ListNext;
4894     guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4895 
4896     // The following CAS() releases the lock and pops the head element.
4897     // The CAS() also ratifies the previously fetched lock-word value.
4898     if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4899       continue;
4900     }
4901     List->OnList = 0;
4902     OrderAccess::fence();
4903     List->unpark();
4904     return;
4905   }
4906 }
4907 
4908 
4909 void Threads::verify() {
4910   ALL_JAVA_THREADS(p) {
4911     p->verify();
4912   }
4913   VMThread* thread = VMThread::vm_thread();
4914   if (thread != NULL) thread->verify();
4915 }
--- EOF ---