1 /*
   2  * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "jvm.h"
  27 #include "classfile/classLoader.hpp"
  28 #include "classfile/javaClasses.hpp"
  29 #include "classfile/moduleEntry.hpp"
  30 #include "classfile/systemDictionary.hpp"
  31 #include "classfile/vmSymbols.hpp"
  32 #include "code/codeCache.hpp"
  33 #include "code/scopeDesc.hpp"
  34 #include "compiler/compileBroker.hpp"
  35 #include "compiler/compileTask.hpp"
  36 #include "gc/shared/gcId.hpp"
  37 #include "gc/shared/gcLocker.inline.hpp"
  38 #include "gc/shared/workgroup.hpp"
  39 #include "interpreter/interpreter.hpp"
  40 #include "interpreter/linkResolver.hpp"
  41 #include "interpreter/oopMapCache.hpp"
  42 #include "jvmtifiles/jvmtiEnv.hpp"
  43 #include "logging/log.hpp"
  44 #include "logging/logConfiguration.hpp"
  45 #include "logging/logStream.hpp"
  46 #include "memory/allocation.inline.hpp"
  47 #include "memory/metaspaceShared.hpp"
  48 #include "memory/oopFactory.hpp"
  49 #include "memory/resourceArea.hpp"
  50 #include "memory/universe.hpp"
  51 #include "oops/access.inline.hpp"
  52 #include "oops/instanceKlass.hpp"
  53 #include "oops/objArrayOop.hpp"
  54 #include "oops/oop.inline.hpp"
  55 #include "oops/symbol.hpp"
  56 #include "oops/typeArrayOop.inline.hpp"
  57 #include "oops/verifyOopClosure.hpp"
  58 #include "prims/jvm_misc.hpp"
  59 #include "prims/jvmtiExport.hpp"
  60 #include "prims/jvmtiThreadState.hpp"
  61 #include "prims/privilegedStack.hpp"
  62 #include "runtime/arguments.hpp"
  63 #include "runtime/atomic.hpp"
  64 #include "runtime/biasedLocking.hpp"
  65 #include "runtime/commandLineFlagConstraintList.hpp"
  66 #include "runtime/commandLineFlagWriteableList.hpp"
  67 #include "runtime/commandLineFlagRangeList.hpp"
  68 #include "runtime/deoptimization.hpp"
  69 #include "runtime/frame.inline.hpp"
  70 #include "runtime/globals.hpp"
  71 #include "runtime/handshake.hpp"
  72 #include "runtime/init.hpp"
  73 #include "runtime/interfaceSupport.inline.hpp"
  74 #include "runtime/java.hpp"
  75 #include "runtime/javaCalls.hpp"
  76 #include "runtime/jniHandles.inline.hpp"
  77 #include "runtime/jniPeriodicChecker.hpp"
  78 #include "runtime/memprofiler.hpp"
  79 #include "runtime/mutexLocker.hpp"
  80 #include "runtime/objectMonitor.hpp"
  81 #include "runtime/orderAccess.inline.hpp"
  82 #include "runtime/osThread.hpp"
  83 #include "runtime/prefetch.inline.hpp"
  84 #include "runtime/safepoint.hpp"
  85 #include "runtime/safepointMechanism.inline.hpp"
  86 #include "runtime/sharedRuntime.hpp"
  87 #include "runtime/statSampler.hpp"
  88 #include "runtime/stubRoutines.hpp"
  89 #include "runtime/sweeper.hpp"
  90 #include "runtime/task.hpp"
  91 #include "runtime/thread.inline.hpp"
  92 #include "runtime/threadCritical.hpp"
  93 #include "runtime/threadSMR.inline.hpp"
  94 #include "runtime/timer.hpp"
  95 #include "runtime/timerTrace.hpp"
  96 #include "runtime/vframe.inline.hpp"
  97 #include "runtime/vframeArray.hpp"
  98 #include "runtime/vframe_hp.hpp"
  99 #include "runtime/vmThread.hpp"
 100 #include "runtime/vm_operations.hpp"
 101 #include "runtime/vm_version.hpp"
 102 #include "services/attachListener.hpp"
 103 #include "services/management.hpp"
 104 #include "services/memTracker.hpp"
 105 #include "services/threadService.hpp"
 106 #include "trace/traceMacros.hpp"
 107 #include "trace/tracing.hpp"
 108 #include "utilities/align.hpp"
 109 #include "utilities/defaultStream.hpp"
 110 #include "utilities/dtrace.hpp"
 111 #include "utilities/events.hpp"
 112 #include "utilities/macros.hpp"
 113 #include "utilities/preserveException.hpp"
 114 #include "utilities/vmError.hpp"
 115 #if INCLUDE_ALL_GCS
 116 #include "gc/cms/concurrentMarkSweepThread.hpp"
 117 #include "gc/g1/g1BarrierSet.hpp"
 118 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
 119 #include "gc/parallel/pcTasks.hpp"
 120 #endif // INCLUDE_ALL_GCS
 121 #if INCLUDE_JVMCI
 122 #include "jvmci/jvmciCompiler.hpp"
 123 #include "jvmci/jvmciRuntime.hpp"
 124 #include "logging/logHandle.hpp"
 125 #endif
 126 #ifdef COMPILER1
 127 #include "c1/c1_Compiler.hpp"
 128 #endif
 129 #ifdef COMPILER2
 130 #include "opto/c2compiler.hpp"
 131 #include "opto/idealGraphPrinter.hpp"
 132 #endif
 133 #if INCLUDE_RTM_OPT
 134 #include "runtime/rtmLocking.hpp"
 135 #endif
 136 
 137 // Initialization after module runtime initialization
 138 void universe_post_module_init();  // must happen after call_initPhase2
 139 
 140 #ifdef DTRACE_ENABLED
 141 
 142 // Only bother with this argument setup if dtrace is available
 143 
 144   #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
 145   #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
 146 
 147   #define DTRACE_THREAD_PROBE(probe, javathread)                           \
 148     {                                                                      \
 149       ResourceMark rm(this);                                               \
 150       int len = 0;                                                         \
 151       const char* name = (javathread)->get_thread_name();                  \
 152       len = strlen(name);                                                  \
 153       HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */               \
 154         (char *) name, len,                                                \
 155         java_lang_Thread::thread_id((javathread)->threadObj()),            \
 156         (uintptr_t) (javathread)->osthread()->thread_id(),                 \
 157         java_lang_Thread::is_daemon((javathread)->threadObj()));           \
 158     }
 159 
 160 #else //  ndef DTRACE_ENABLED
 161 
 162   #define DTRACE_THREAD_PROBE(probe, javathread)
 163 
 164 #endif // ndef DTRACE_ENABLED
 165 
 166 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 167 // Current thread is maintained as a thread-local variable
 168 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
 169 #endif
 170 // Class hierarchy
 171 // - Thread
 172 //   - VMThread
 173 //   - WatcherThread
 174 //   - ConcurrentMarkSweepThread
 175 //   - JavaThread
 176 //     - CompilerThread
 177 
 178 // ======= Thread ========
 179 // Support for forcing alignment of thread objects for biased locking
 180 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
 181   if (UseBiasedLocking) {
 182     const int alignment = markOopDesc::biased_lock_alignment;
 183     size_t aligned_size = size + (alignment - sizeof(intptr_t));
 184     void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
 185                                           : AllocateHeap(aligned_size, flags, CURRENT_PC,
 186                                                          AllocFailStrategy::RETURN_NULL);
 187     void* aligned_addr     = align_up(real_malloc_addr, alignment);
 188     assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
 189            ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
 190            "JavaThread alignment code overflowed allocated storage");
 191     if (aligned_addr != real_malloc_addr) {
 192       log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
 193                               p2i(real_malloc_addr),
 194                               p2i(aligned_addr));
 195     }
 196     ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
 197     return aligned_addr;
 198   } else {
 199     return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
 200                        : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
 201   }
 202 }
 203 
 204 void Thread::operator delete(void* p) {
 205   if (UseBiasedLocking) {
 206     FreeHeap(((Thread*) p)->_real_malloc_address);
 207   } else {
 208     FreeHeap(p);
 209   }
 210 }
 211 
 212 void JavaThread::smr_delete() {
 213   if (_on_thread_list) {
 214     ThreadsSMRSupport::smr_delete(this);
 215   } else {
 216     delete this;
 217   }
 218 }
 219 
 220 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
 221 // JavaThread
 222 
 223 
 224 Thread::Thread() {
 225   // stack and get_thread
 226   set_stack_base(NULL);
 227   set_stack_size(0);
 228   set_self_raw_id(0);
 229   set_lgrp_id(-1);
 230   DEBUG_ONLY(clear_suspendible_thread();)
 231 
 232   // allocated data structures
 233   set_osthread(NULL);
 234   set_resource_area(new (mtThread)ResourceArea());
 235   DEBUG_ONLY(_current_resource_mark = NULL;)
 236   set_handle_area(new (mtThread) HandleArea(NULL));
 237   set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
 238   set_active_handles(NULL);
 239   set_free_handle_block(NULL);
 240   set_last_handle_mark(NULL);
 241 
 242   // This initial value ==> never claimed.
 243   _oops_do_parity = 0;
 244   _threads_hazard_ptr = NULL;
 245   _nested_threads_hazard_ptr = NULL;
 246   _nested_threads_hazard_ptr_cnt = 0;
 247 
 248   // the handle mark links itself to last_handle_mark
 249   new HandleMark(this);
 250 
 251   // plain initialization
 252   debug_only(_owned_locks = NULL;)
 253   debug_only(_allow_allocation_count = 0;)
 254   NOT_PRODUCT(_allow_safepoint_count = 0;)
 255   NOT_PRODUCT(_skip_gcalot = false;)
 256   _jvmti_env_iteration_count = 0;
 257   set_allocated_bytes(0);
 258   _vm_operation_started_count = 0;
 259   _vm_operation_completed_count = 0;
 260   _current_pending_monitor = NULL;
 261   _current_pending_monitor_is_from_java = true;
 262   _current_waiting_monitor = NULL;
 263   _num_nested_signal = 0;
 264   omFreeList = NULL;
 265   omFreeCount = 0;
 266   omFreeProvision = 32;
 267   omInUseList = NULL;
 268   omInUseCount = 0;
 269 
 270 #ifdef ASSERT
 271   _visited_for_critical_count = false;
 272 #endif
 273 
 274   _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
 275                          Monitor::_safepoint_check_sometimes);
 276   _suspend_flags = 0;
 277 
 278   // thread-specific hashCode stream generator state - Marsaglia shift-xor form
 279   _hashStateX = os::random();
 280   _hashStateY = 842502087;
 281   _hashStateZ = 0x8767;    // (int)(3579807591LL & 0xffff) ;
 282   _hashStateW = 273326509;
 283 
 284   _OnTrap   = 0;
 285   _schedctl = NULL;
 286   _Stalled  = 0;
 287   _TypeTag  = 0x2BAD;
 288 
 289   // Many of the following fields are effectively final - immutable
 290   // Note that nascent threads can't use the Native Monitor-Mutex
 291   // construct until the _MutexEvent is initialized ...
 292   // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
 293   // we might instead use a stack of ParkEvents that we could provision on-demand.
 294   // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
 295   // and ::Release()
 296   _ParkEvent   = ParkEvent::Allocate(this);
 297   _SleepEvent  = ParkEvent::Allocate(this);
 298   _MutexEvent  = ParkEvent::Allocate(this);
 299   _MuxEvent    = ParkEvent::Allocate(this);
 300 
 301 #ifdef CHECK_UNHANDLED_OOPS
 302   if (CheckUnhandledOops) {
 303     _unhandled_oops = new UnhandledOops(this);
 304   }
 305 #endif // CHECK_UNHANDLED_OOPS
 306 #ifdef ASSERT
 307   if (UseBiasedLocking) {
 308     assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
 309     assert(this == _real_malloc_address ||
 310            this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
 311            "bug in forced alignment of thread objects");
 312   }
 313 #endif // ASSERT
 314 }
 315 
 316 void Thread::initialize_thread_current() {
 317 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 318   assert(_thr_current == NULL, "Thread::current already initialized");
 319   _thr_current = this;
 320 #endif
 321   assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
 322   ThreadLocalStorage::set_thread(this);
 323   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 324 }
 325 
 326 void Thread::clear_thread_current() {
 327   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 328 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 329   _thr_current = NULL;
 330 #endif
 331   ThreadLocalStorage::set_thread(NULL);
 332 }
 333 
 334 void Thread::record_stack_base_and_size() {
 335   set_stack_base(os::current_stack_base());
 336   set_stack_size(os::current_stack_size());
 337   // CR 7190089: on Solaris, primordial thread's stack is adjusted
 338   // in initialize_thread(). Without the adjustment, stack size is
 339   // incorrect if stack is set to unlimited (ulimit -s unlimited).
 340   // So far, only Solaris has real implementation of initialize_thread().
 341   //
 342   // set up any platform-specific state.
 343   os::initialize_thread(this);
 344 
 345   // Set stack limits after thread is initialized.
 346   if (is_Java_thread()) {
 347     ((JavaThread*) this)->set_stack_overflow_limit();
 348     ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
 349   }
 350 #if INCLUDE_NMT
 351   // record thread's native stack, stack grows downward
 352   MemTracker::record_thread_stack(stack_end(), stack_size());
 353 #endif // INCLUDE_NMT
 354   log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
 355     PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
 356     os::current_thread_id(), p2i(stack_base() - stack_size()),
 357     p2i(stack_base()), stack_size()/1024);
 358 }
 359 
 360 
 361 Thread::~Thread() {
 362   EVENT_THREAD_DESTRUCT(this);
 363 
 364   // stack_base can be NULL if the thread is never started or exited before
 365   // record_stack_base_and_size called. Although, we would like to ensure
 366   // that all started threads do call record_stack_base_and_size(), there is
 367   // not proper way to enforce that.
 368 #if INCLUDE_NMT
 369   if (_stack_base != NULL) {
 370     MemTracker::release_thread_stack(stack_end(), stack_size());
 371 #ifdef ASSERT
 372     set_stack_base(NULL);
 373 #endif
 374   }
 375 #endif // INCLUDE_NMT
 376 
 377   // deallocate data structures
 378   delete resource_area();
 379   // since the handle marks are using the handle area, we have to deallocated the root
 380   // handle mark before deallocating the thread's handle area,
 381   assert(last_handle_mark() != NULL, "check we have an element");
 382   delete last_handle_mark();
 383   assert(last_handle_mark() == NULL, "check we have reached the end");
 384 
 385   // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
 386   // We NULL out the fields for good hygiene.
 387   ParkEvent::Release(_ParkEvent); _ParkEvent   = NULL;
 388   ParkEvent::Release(_SleepEvent); _SleepEvent  = NULL;
 389   ParkEvent::Release(_MutexEvent); _MutexEvent  = NULL;
 390   ParkEvent::Release(_MuxEvent); _MuxEvent    = NULL;
 391 
 392   delete handle_area();
 393   delete metadata_handles();
 394 
 395   // SR_handler uses this as a termination indicator -
 396   // needs to happen before os::free_thread()
 397   delete _SR_lock;
 398   _SR_lock = NULL;
 399 
 400   // osthread() can be NULL, if creation of thread failed.
 401   if (osthread() != NULL) os::free_thread(osthread());
 402 
 403   // clear Thread::current if thread is deleting itself.
 404   // Needed to ensure JNI correctly detects non-attached threads.
 405   if (this == Thread::current()) {
 406     clear_thread_current();
 407   }
 408 
 409   CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
 410 }
 411 
 412 // NOTE: dummy function for assertion purpose.
 413 void Thread::run() {
 414   ShouldNotReachHere();
 415 }
 416 
 417 #ifdef ASSERT
 418 // A JavaThread is considered "dangling" if it is not the current
 419 // thread, has been added the Threads list, the system is not at a
 420 // safepoint and the Thread is not "protected".
 421 //
 422 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
 423   assert(!thread->is_Java_thread() || Thread::current() == thread ||
 424          !((JavaThread *) thread)->on_thread_list() ||
 425          SafepointSynchronize::is_at_safepoint() ||
 426          ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
 427          "possibility of dangling Thread pointer");
 428 }
 429 #endif
 430 
 431 ThreadPriority Thread::get_priority(const Thread* const thread) {
 432   ThreadPriority priority;
 433   // Can return an error!
 434   (void)os::get_priority(thread, priority);
 435   assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
 436   return priority;
 437 }
 438 
 439 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
 440   debug_only(check_for_dangling_thread_pointer(thread);)
 441   // Can return an error!
 442   (void)os::set_priority(thread, priority);
 443 }
 444 
 445 
 446 void Thread::start(Thread* thread) {
 447   // Start is different from resume in that its safety is guaranteed by context or
 448   // being called from a Java method synchronized on the Thread object.
 449   if (!DisableStartThread) {
 450     if (thread->is_Java_thread()) {
 451       // Initialize the thread state to RUNNABLE before starting this thread.
 452       // Can not set it after the thread started because we do not know the
 453       // exact thread state at that time. It could be in MONITOR_WAIT or
 454       // in SLEEPING or some other state.
 455       java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
 456                                           java_lang_Thread::RUNNABLE);
 457     }
 458     os::start_thread(thread);
 459   }
 460 }
 461 
 462 // Enqueue a VM_Operation to do the job for us - sometime later
 463 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
 464   VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
 465   VMThread::execute(vm_stop);
 466 }
 467 
 468 
 469 // Check if an external suspend request has completed (or has been
 470 // cancelled). Returns true if the thread is externally suspended and
 471 // false otherwise.
 472 //
 473 // The bits parameter returns information about the code path through
 474 // the routine. Useful for debugging:
 475 //
 476 // set in is_ext_suspend_completed():
 477 // 0x00000001 - routine was entered
 478 // 0x00000010 - routine return false at end
 479 // 0x00000100 - thread exited (return false)
 480 // 0x00000200 - suspend request cancelled (return false)
 481 // 0x00000400 - thread suspended (return true)
 482 // 0x00001000 - thread is in a suspend equivalent state (return true)
 483 // 0x00002000 - thread is native and walkable (return true)
 484 // 0x00004000 - thread is native_trans and walkable (needed retry)
 485 //
 486 // set in wait_for_ext_suspend_completion():
 487 // 0x00010000 - routine was entered
 488 // 0x00020000 - suspend request cancelled before loop (return false)
 489 // 0x00040000 - thread suspended before loop (return true)
 490 // 0x00080000 - suspend request cancelled in loop (return false)
 491 // 0x00100000 - thread suspended in loop (return true)
 492 // 0x00200000 - suspend not completed during retry loop (return false)
 493 
 494 // Helper class for tracing suspend wait debug bits.
 495 //
 496 // 0x00000100 indicates that the target thread exited before it could
 497 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
 498 // 0x00080000 each indicate a cancelled suspend request so they don't
 499 // count as wait failures either.
 500 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
 501 
 502 class TraceSuspendDebugBits : public StackObj {
 503  private:
 504   JavaThread * jt;
 505   bool         is_wait;
 506   bool         called_by_wait;  // meaningful when !is_wait
 507   uint32_t *   bits;
 508 
 509  public:
 510   TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
 511                         uint32_t *_bits) {
 512     jt             = _jt;
 513     is_wait        = _is_wait;
 514     called_by_wait = _called_by_wait;
 515     bits           = _bits;
 516   }
 517 
 518   ~TraceSuspendDebugBits() {
 519     if (!is_wait) {
 520 #if 1
 521       // By default, don't trace bits for is_ext_suspend_completed() calls.
 522       // That trace is very chatty.
 523       return;
 524 #else
 525       if (!called_by_wait) {
 526         // If tracing for is_ext_suspend_completed() is enabled, then only
 527         // trace calls to it from wait_for_ext_suspend_completion()
 528         return;
 529       }
 530 #endif
 531     }
 532 
 533     if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
 534       if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
 535         MutexLocker ml(Threads_lock);  // needed for get_thread_name()
 536         ResourceMark rm;
 537 
 538         tty->print_cr(
 539                       "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
 540                       jt->get_thread_name(), *bits);
 541 
 542         guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
 543       }
 544     }
 545   }
 546 };
 547 #undef DEBUG_FALSE_BITS
 548 
 549 
 550 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
 551                                           uint32_t *bits) {
 552   TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
 553 
 554   bool did_trans_retry = false;  // only do thread_in_native_trans retry once
 555   bool do_trans_retry;           // flag to force the retry
 556 
 557   *bits |= 0x00000001;
 558 
 559   do {
 560     do_trans_retry = false;
 561 
 562     if (is_exiting()) {
 563       // Thread is in the process of exiting. This is always checked
 564       // first to reduce the risk of dereferencing a freed JavaThread.
 565       *bits |= 0x00000100;
 566       return false;
 567     }
 568 
 569     if (!is_external_suspend()) {
 570       // Suspend request is cancelled. This is always checked before
 571       // is_ext_suspended() to reduce the risk of a rogue resume
 572       // confusing the thread that made the suspend request.
 573       *bits |= 0x00000200;
 574       return false;
 575     }
 576 
 577     if (is_ext_suspended()) {
 578       // thread is suspended
 579       *bits |= 0x00000400;
 580       return true;
 581     }
 582 
 583     // Now that we no longer do hard suspends of threads running
 584     // native code, the target thread can be changing thread state
 585     // while we are in this routine:
 586     //
 587     //   _thread_in_native -> _thread_in_native_trans -> _thread_blocked
 588     //
 589     // We save a copy of the thread state as observed at this moment
 590     // and make our decision about suspend completeness based on the
 591     // copy. This closes the race where the thread state is seen as
 592     // _thread_in_native_trans in the if-thread_blocked check, but is
 593     // seen as _thread_blocked in if-thread_in_native_trans check.
 594     JavaThreadState save_state = thread_state();
 595 
 596     if (save_state == _thread_blocked && is_suspend_equivalent()) {
 597       // If the thread's state is _thread_blocked and this blocking
 598       // condition is known to be equivalent to a suspend, then we can
 599       // consider the thread to be externally suspended. This means that
 600       // the code that sets _thread_blocked has been modified to do
 601       // self-suspension if the blocking condition releases. We also
 602       // used to check for CONDVAR_WAIT here, but that is now covered by
 603       // the _thread_blocked with self-suspension check.
 604       //
 605       // Return true since we wouldn't be here unless there was still an
 606       // external suspend request.
 607       *bits |= 0x00001000;
 608       return true;
 609     } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
 610       // Threads running native code will self-suspend on native==>VM/Java
 611       // transitions. If its stack is walkable (should always be the case
 612       // unless this function is called before the actual java_suspend()
 613       // call), then the wait is done.
 614       *bits |= 0x00002000;
 615       return true;
 616     } else if (!called_by_wait && !did_trans_retry &&
 617                save_state == _thread_in_native_trans &&
 618                frame_anchor()->walkable()) {
 619       // The thread is transitioning from thread_in_native to another
 620       // thread state. check_safepoint_and_suspend_for_native_trans()
 621       // will force the thread to self-suspend. If it hasn't gotten
 622       // there yet we may have caught the thread in-between the native
 623       // code check above and the self-suspend. Lucky us. If we were
 624       // called by wait_for_ext_suspend_completion(), then it
 625       // will be doing the retries so we don't have to.
 626       //
 627       // Since we use the saved thread state in the if-statement above,
 628       // there is a chance that the thread has already transitioned to
 629       // _thread_blocked by the time we get here. In that case, we will
 630       // make a single unnecessary pass through the logic below. This
 631       // doesn't hurt anything since we still do the trans retry.
 632 
 633       *bits |= 0x00004000;
 634 
 635       // Once the thread leaves thread_in_native_trans for another
 636       // thread state, we break out of this retry loop. We shouldn't
 637       // need this flag to prevent us from getting back here, but
 638       // sometimes paranoia is good.
 639       did_trans_retry = true;
 640 
 641       // We wait for the thread to transition to a more usable state.
 642       for (int i = 1; i <= SuspendRetryCount; i++) {
 643         // We used to do an "os::yield_all(i)" call here with the intention
 644         // that yielding would increase on each retry. However, the parameter
 645         // is ignored on Linux which means the yield didn't scale up. Waiting
 646         // on the SR_lock below provides a much more predictable scale up for
 647         // the delay. It also provides a simple/direct point to check for any
 648         // safepoint requests from the VMThread
 649 
 650         // temporarily drops SR_lock while doing wait with safepoint check
 651         // (if we're a JavaThread - the WatcherThread can also call this)
 652         // and increase delay with each retry
 653         SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 654 
 655         // check the actual thread state instead of what we saved above
 656         if (thread_state() != _thread_in_native_trans) {
 657           // the thread has transitioned to another thread state so
 658           // try all the checks (except this one) one more time.
 659           do_trans_retry = true;
 660           break;
 661         }
 662       } // end retry loop
 663 
 664 
 665     }
 666   } while (do_trans_retry);
 667 
 668   *bits |= 0x00000010;
 669   return false;
 670 }
 671 
 672 // Wait for an external suspend request to complete (or be cancelled).
 673 // Returns true if the thread is externally suspended and false otherwise.
 674 //
 675 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
 676                                                  uint32_t *bits) {
 677   TraceSuspendDebugBits tsdb(this, true /* is_wait */,
 678                              false /* !called_by_wait */, bits);
 679 
 680   // local flag copies to minimize SR_lock hold time
 681   bool is_suspended;
 682   bool pending;
 683   uint32_t reset_bits;
 684 
 685   // set a marker so is_ext_suspend_completed() knows we are the caller
 686   *bits |= 0x00010000;
 687 
 688   // We use reset_bits to reinitialize the bits value at the top of
 689   // each retry loop. This allows the caller to make use of any
 690   // unused bits for their own marking purposes.
 691   reset_bits = *bits;
 692 
 693   {
 694     MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
 695     is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 696                                             delay, bits);
 697     pending = is_external_suspend();
 698   }
 699   // must release SR_lock to allow suspension to complete
 700 
 701   if (!pending) {
 702     // A cancelled suspend request is the only false return from
 703     // is_ext_suspend_completed() that keeps us from entering the
 704     // retry loop.
 705     *bits |= 0x00020000;
 706     return false;
 707   }
 708 
 709   if (is_suspended) {
 710     *bits |= 0x00040000;
 711     return true;
 712   }
 713 
 714   for (int i = 1; i <= retries; i++) {
 715     *bits = reset_bits;  // reinit to only track last retry
 716 
 717     // We used to do an "os::yield_all(i)" call here with the intention
 718     // that yielding would increase on each retry. However, the parameter
 719     // is ignored on Linux which means the yield didn't scale up. Waiting
 720     // on the SR_lock below provides a much more predictable scale up for
 721     // the delay. It also provides a simple/direct point to check for any
 722     // safepoint requests from the VMThread
 723 
 724     {
 725       MutexLocker ml(SR_lock());
 726       // wait with safepoint check (if we're a JavaThread - the WatcherThread
 727       // can also call this)  and increase delay with each retry
 728       SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
 729 
 730       is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
 731                                               delay, bits);
 732 
 733       // It is possible for the external suspend request to be cancelled
 734       // (by a resume) before the actual suspend operation is completed.
 735       // Refresh our local copy to see if we still need to wait.
 736       pending = is_external_suspend();
 737     }
 738 
 739     if (!pending) {
 740       // A cancelled suspend request is the only false return from
 741       // is_ext_suspend_completed() that keeps us from staying in the
 742       // retry loop.
 743       *bits |= 0x00080000;
 744       return false;
 745     }
 746 
 747     if (is_suspended) {
 748       *bits |= 0x00100000;
 749       return true;
 750     }
 751   } // end retry loop
 752 
 753   // thread did not suspend after all our retries
 754   *bits |= 0x00200000;
 755   return false;
 756 }
 757 
 758 // Called from API entry points which perform stack walking. If the
 759 // associated JavaThread is the current thread, then wait_for_suspend
 760 // is not used. Otherwise, it determines if we should wait for the
 761 // "other" thread to complete external suspension. (NOTE: in future
 762 // releases the suspension mechanism should be reimplemented so this
 763 // is not necessary.)
 764 //
 765 bool
 766 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
 767   if (this != JavaThread::current()) {
 768     // "other" threads require special handling.
 769     if (wait_for_suspend) {
 770       // We are allowed to wait for the external suspend to complete
 771       // so give the other thread a chance to get suspended.
 772       if (!wait_for_ext_suspend_completion(SuspendRetryCount,
 773                                            SuspendRetryDelay, bits)) {
 774         // Didn't make it so let the caller know.
 775         return false;
 776       }
 777     }
 778     // We aren't allowed to wait for the external suspend to complete
 779     // so if the other thread isn't externally suspended we need to
 780     // let the caller know.
 781     else if (!is_ext_suspend_completed_with_lock(bits)) {
 782       return false;
 783     }
 784   }
 785 
 786   return true;
 787 }
 788 
 789 #ifndef PRODUCT
 790 void JavaThread::record_jump(address target, address instr, const char* file,
 791                              int line) {
 792 
 793   // This should not need to be atomic as the only way for simultaneous
 794   // updates is via interrupts. Even then this should be rare or non-existent
 795   // and we don't care that much anyway.
 796 
 797   int index = _jmp_ring_index;
 798   _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
 799   _jmp_ring[index]._target = (intptr_t) target;
 800   _jmp_ring[index]._instruction = (intptr_t) instr;
 801   _jmp_ring[index]._file = file;
 802   _jmp_ring[index]._line = line;
 803 }
 804 #endif // PRODUCT
 805 
 806 void Thread::interrupt(Thread* thread) {
 807   debug_only(check_for_dangling_thread_pointer(thread);)
 808   os::interrupt(thread);
 809 }
 810 
 811 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
 812   debug_only(check_for_dangling_thread_pointer(thread);)
 813   // Note:  If clear_interrupted==false, this simply fetches and
 814   // returns the value of the field osthread()->interrupted().
 815   return os::is_interrupted(thread, clear_interrupted);
 816 }
 817 
 818 
 819 // GC Support
 820 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
 821   int thread_parity = _oops_do_parity;
 822   if (thread_parity != strong_roots_parity) {
 823     jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
 824     if (res == thread_parity) {
 825       return true;
 826     } else {
 827       guarantee(res == strong_roots_parity, "Or else what?");
 828       return false;
 829     }
 830   }
 831   return false;
 832 }
 833 
 834 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
 835   active_handles()->oops_do(f);
 836   // Do oop for ThreadShadow
 837   f->do_oop((oop*)&_pending_exception);
 838   handle_area()->oops_do(f);
 839 
 840   if (MonitorInUseLists) {
 841     // When using thread local monitor lists, we scan them here,
 842     // and the remaining global monitors in ObjectSynchronizer::oops_do().
 843     ObjectSynchronizer::thread_local_used_oops_do(this, f);
 844   }
 845 }
 846 
 847 void Thread::metadata_handles_do(void f(Metadata*)) {
 848   // Only walk the Handles in Thread.
 849   if (metadata_handles() != NULL) {
 850     for (int i = 0; i< metadata_handles()->length(); i++) {
 851       f(metadata_handles()->at(i));
 852     }
 853   }
 854 }
 855 
 856 void Thread::print_on(outputStream* st) const {
 857   // get_priority assumes osthread initialized
 858   if (osthread() != NULL) {
 859     int os_prio;
 860     if (os::get_native_priority(this, &os_prio) == OS_OK) {
 861       st->print("os_prio=%d ", os_prio);
 862     }
 863     st->print("tid=" INTPTR_FORMAT " ", p2i(this));
 864     osthread()->print_on(st);
 865   }
 866   if (_threads_hazard_ptr != NULL) {
 867     st->print("_threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
 868   }
 869   if (_nested_threads_hazard_ptr != NULL) {
 870     print_nested_threads_hazard_ptrs_on(st);
 871   }
 872   st->print(" ");
 873   debug_only(if (WizardMode) print_owned_locks_on(st);)
 874 }
 875 
 876 void Thread::print_nested_threads_hazard_ptrs_on(outputStream* st) const {
 877   assert(_nested_threads_hazard_ptr != NULL, "must be set to print");
 878 
 879   if (EnableThreadSMRStatistics) {
 880     st->print(", _nested_threads_hazard_ptr_cnt=%u", _nested_threads_hazard_ptr_cnt);
 881   }
 882   st->print(", _nested_threads_hazard_ptrs=");
 883   for (NestedThreadsList* node = _nested_threads_hazard_ptr; node != NULL;
 884        node = node->next()) {
 885     if (node != _nested_threads_hazard_ptr) {
 886       // First node does not need a comma-space separator.
 887       st->print(", ");
 888     }
 889     st->print(INTPTR_FORMAT, p2i(node->t_list()));
 890   }
 891 }
 892 
 893 // Thread::print_on_error() is called by fatal error handler. Don't use
 894 // any lock or allocate memory.
 895 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
 896   assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
 897 
 898   if (is_VM_thread())                 { st->print("VMThread"); }
 899   else if (is_GC_task_thread())       { st->print("GCTaskThread"); }
 900   else if (is_Watcher_thread())       { st->print("WatcherThread"); }
 901   else if (is_ConcurrentGC_thread())  { st->print("ConcurrentGCThread"); }
 902   else                                { st->print("Thread"); }
 903 
 904   if (is_Named_thread()) {
 905     st->print(" \"%s\"", name());
 906   }
 907 
 908   st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
 909             p2i(stack_end()), p2i(stack_base()));
 910 
 911   if (osthread()) {
 912     st->print(" [id=%d]", osthread()->thread_id());
 913   }
 914 
 915   if (_threads_hazard_ptr != NULL) {
 916     st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
 917   }
 918   if (_nested_threads_hazard_ptr != NULL) {
 919     print_nested_threads_hazard_ptrs_on(st);
 920   }
 921 }
 922 
 923 void Thread::print_value_on(outputStream* st) const {
 924   if (is_Named_thread()) {
 925     st->print(" \"%s\" ", name());
 926   }
 927   st->print(INTPTR_FORMAT, p2i(this));   // print address
 928 }
 929 
 930 #ifdef ASSERT
 931 void Thread::print_owned_locks_on(outputStream* st) const {
 932   Monitor *cur = _owned_locks;
 933   if (cur == NULL) {
 934     st->print(" (no locks) ");
 935   } else {
 936     st->print_cr(" Locks owned:");
 937     while (cur) {
 938       cur->print_on(st);
 939       cur = cur->next();
 940     }
 941   }
 942 }
 943 
 944 static int ref_use_count  = 0;
 945 
 946 bool Thread::owns_locks_but_compiled_lock() const {
 947   for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 948     if (cur != Compile_lock) return true;
 949   }
 950   return false;
 951 }
 952 
 953 
 954 #endif
 955 
 956 #ifndef PRODUCT
 957 
 958 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially
 959 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
 960 // no threads which allow_vm_block's are held
 961 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
 962   // Check if current thread is allowed to block at a safepoint
 963   if (!(_allow_safepoint_count == 0)) {
 964     fatal("Possible safepoint reached by thread that does not allow it");
 965   }
 966   if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
 967     fatal("LEAF method calling lock?");
 968   }
 969 
 970 #ifdef ASSERT
 971   if (potential_vm_operation && is_Java_thread()
 972       && !Universe::is_bootstrapping()) {
 973     // Make sure we do not hold any locks that the VM thread also uses.
 974     // This could potentially lead to deadlocks
 975     for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
 976       // Threads_lock is special, since the safepoint synchronization will not start before this is
 977       // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
 978       // since it is used to transfer control between JavaThreads and the VMThread
 979       // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
 980       if ((cur->allow_vm_block() &&
 981            cur != Threads_lock &&
 982            cur != Compile_lock &&               // Temporary: should not be necessary when we get separate compilation
 983            cur != VMOperationRequest_lock &&
 984            cur != VMOperationQueue_lock) ||
 985            cur->rank() == Mutex::special) {
 986         fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
 987       }
 988     }
 989   }
 990 
 991   if (GCALotAtAllSafepoints) {
 992     // We could enter a safepoint here and thus have a gc
 993     InterfaceSupport::check_gc_alot();
 994   }
 995 #endif
 996 }
 997 #endif
 998 
 999 bool Thread::is_in_stack(address adr) const {
1000   assert(Thread::current() == this, "is_in_stack can only be called from current thread");
1001   address end = os::current_stack_pointer();
1002   // Allow non Java threads to call this without stack_base
1003   if (_stack_base == NULL) return true;
1004   if (stack_base() >= adr && adr >= end) return true;
1005 
1006   return false;
1007 }
1008 
1009 bool Thread::is_in_usable_stack(address adr) const {
1010   size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1011   size_t usable_stack_size = _stack_size - stack_guard_size;
1012 
1013   return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1014 }
1015 
1016 
1017 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1018 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1019 // used for compilation in the future. If that change is made, the need for these methods
1020 // should be revisited, and they should be removed if possible.
1021 
1022 bool Thread::is_lock_owned(address adr) const {
1023   return on_local_stack(adr);
1024 }
1025 
1026 bool Thread::set_as_starting_thread() {
1027   // NOTE: this must be called inside the main thread.
1028   return os::create_main_thread((JavaThread*)this);
1029 }
1030 
1031 static void initialize_class(Symbol* class_name, TRAPS) {
1032   Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1033   InstanceKlass::cast(klass)->initialize(CHECK);
1034 }
1035 
1036 
1037 // Creates the initial ThreadGroup
1038 static Handle create_initial_thread_group(TRAPS) {
1039   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
1040   InstanceKlass* ik = InstanceKlass::cast(k);
1041 
1042   Handle system_instance = ik->allocate_instance_handle(CHECK_NH);
1043   {
1044     JavaValue result(T_VOID);
1045     JavaCalls::call_special(&result,
1046                             system_instance,
1047                             ik,
1048                             vmSymbols::object_initializer_name(),
1049                             vmSymbols::void_method_signature(),
1050                             CHECK_NH);
1051   }
1052   Universe::set_system_thread_group(system_instance());
1053 
1054   Handle main_instance = ik->allocate_instance_handle(CHECK_NH);
1055   {
1056     JavaValue result(T_VOID);
1057     Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1058     JavaCalls::call_special(&result,
1059                             main_instance,
1060                             ik,
1061                             vmSymbols::object_initializer_name(),
1062                             vmSymbols::threadgroup_string_void_signature(),
1063                             system_instance,
1064                             string,
1065                             CHECK_NH);
1066   }
1067   return main_instance;
1068 }
1069 
1070 // Creates the initial Thread
1071 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1072                                  TRAPS) {
1073   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
1074   InstanceKlass* ik = InstanceKlass::cast(k);
1075   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1076 
1077   java_lang_Thread::set_thread(thread_oop(), thread);
1078   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1079   thread->set_threadObj(thread_oop());
1080 
1081   Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1082 
1083   JavaValue result(T_VOID);
1084   JavaCalls::call_special(&result, thread_oop,
1085                           ik,
1086                           vmSymbols::object_initializer_name(),
1087                           vmSymbols::threadgroup_string_void_signature(),
1088                           thread_group,
1089                           string,
1090                           CHECK_NULL);
1091   return thread_oop();
1092 }
1093 
1094 char java_runtime_name[128] = "";
1095 char java_runtime_version[128] = "";
1096 
1097 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1098 static const char* get_java_runtime_name(TRAPS) {
1099   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1100                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1101   fieldDescriptor fd;
1102   bool found = k != NULL &&
1103                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1104                                                         vmSymbols::string_signature(), &fd);
1105   if (found) {
1106     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1107     if (name_oop == NULL) {
1108       return NULL;
1109     }
1110     const char* name = java_lang_String::as_utf8_string(name_oop,
1111                                                         java_runtime_name,
1112                                                         sizeof(java_runtime_name));
1113     return name;
1114   } else {
1115     return NULL;
1116   }
1117 }
1118 
1119 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1120 static const char* get_java_runtime_version(TRAPS) {
1121   Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1122                                     Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1123   fieldDescriptor fd;
1124   bool found = k != NULL &&
1125                InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1126                                                         vmSymbols::string_signature(), &fd);
1127   if (found) {
1128     oop name_oop = k->java_mirror()->obj_field(fd.offset());
1129     if (name_oop == NULL) {
1130       return NULL;
1131     }
1132     const char* name = java_lang_String::as_utf8_string(name_oop,
1133                                                         java_runtime_version,
1134                                                         sizeof(java_runtime_version));
1135     return name;
1136   } else {
1137     return NULL;
1138   }
1139 }
1140 
1141 // General purpose hook into Java code, run once when the VM is initialized.
1142 // The Java library method itself may be changed independently from the VM.
1143 static void call_postVMInitHook(TRAPS) {
1144   Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1145   if (klass != NULL) {
1146     JavaValue result(T_VOID);
1147     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1148                            vmSymbols::void_method_signature(),
1149                            CHECK);
1150   }
1151 }
1152 
1153 static void reset_vm_info_property(TRAPS) {
1154   // the vm info string
1155   ResourceMark rm(THREAD);
1156   const char *vm_info = VM_Version::vm_info_string();
1157 
1158   // java.lang.System class
1159   Klass* klass =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1160 
1161   // setProperty arguments
1162   Handle key_str    = java_lang_String::create_from_str("java.vm.info", CHECK);
1163   Handle value_str  = java_lang_String::create_from_str(vm_info, CHECK);
1164 
1165   // return value
1166   JavaValue r(T_OBJECT);
1167 
1168   // public static String setProperty(String key, String value);
1169   JavaCalls::call_static(&r,
1170                          klass,
1171                          vmSymbols::setProperty_name(),
1172                          vmSymbols::string_string_string_signature(),
1173                          key_str,
1174                          value_str,
1175                          CHECK);
1176 }
1177 
1178 
1179 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1180                                     bool daemon, TRAPS) {
1181   assert(thread_group.not_null(), "thread group should be specified");
1182   assert(threadObj() == NULL, "should only create Java thread object once");
1183 
1184   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1185   InstanceKlass* ik = InstanceKlass::cast(k);
1186   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1187 
1188   java_lang_Thread::set_thread(thread_oop(), this);
1189   java_lang_Thread::set_priority(thread_oop(), NormPriority);
1190   set_threadObj(thread_oop());
1191 
1192   JavaValue result(T_VOID);
1193   if (thread_name != NULL) {
1194     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1195     // Thread gets assigned specified name and null target
1196     JavaCalls::call_special(&result,
1197                             thread_oop,
1198                             ik,
1199                             vmSymbols::object_initializer_name(),
1200                             vmSymbols::threadgroup_string_void_signature(),
1201                             thread_group, // Argument 1
1202                             name,         // Argument 2
1203                             THREAD);
1204   } else {
1205     // Thread gets assigned name "Thread-nnn" and null target
1206     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1207     JavaCalls::call_special(&result,
1208                             thread_oop,
1209                             ik,
1210                             vmSymbols::object_initializer_name(),
1211                             vmSymbols::threadgroup_runnable_void_signature(),
1212                             thread_group, // Argument 1
1213                             Handle(),     // Argument 2
1214                             THREAD);
1215   }
1216 
1217 
1218   if (daemon) {
1219     java_lang_Thread::set_daemon(thread_oop());
1220   }
1221 
1222   if (HAS_PENDING_EXCEPTION) {
1223     return;
1224   }
1225 
1226   Klass* group =  SystemDictionary::ThreadGroup_klass();
1227   Handle threadObj(THREAD, this->threadObj());
1228 
1229   JavaCalls::call_special(&result,
1230                           thread_group,
1231                           group,
1232                           vmSymbols::add_method_name(),
1233                           vmSymbols::thread_void_signature(),
1234                           threadObj,          // Arg 1
1235                           THREAD);
1236 }
1237 
1238 // NamedThread --  non-JavaThread subclasses with multiple
1239 // uniquely named instances should derive from this.
1240 NamedThread::NamedThread() : Thread() {
1241   _name = NULL;
1242   _processed_thread = NULL;
1243   _gc_id = GCId::undefined();
1244 }
1245 
1246 NamedThread::~NamedThread() {
1247   if (_name != NULL) {
1248     FREE_C_HEAP_ARRAY(char, _name);
1249     _name = NULL;
1250   }
1251 }
1252 
1253 void NamedThread::set_name(const char* format, ...) {
1254   guarantee(_name == NULL, "Only get to set name once.");
1255   _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1256   guarantee(_name != NULL, "alloc failure");
1257   va_list ap;
1258   va_start(ap, format);
1259   jio_vsnprintf(_name, max_name_len, format, ap);
1260   va_end(ap);
1261 }
1262 
1263 void NamedThread::initialize_named_thread() {
1264   set_native_thread_name(name());
1265 }
1266 
1267 void NamedThread::print_on(outputStream* st) const {
1268   st->print("\"%s\" ", name());
1269   Thread::print_on(st);
1270   st->cr();
1271 }
1272 
1273 
1274 // ======= WatcherThread ========
1275 
1276 // The watcher thread exists to simulate timer interrupts.  It should
1277 // be replaced by an abstraction over whatever native support for
1278 // timer interrupts exists on the platform.
1279 
1280 WatcherThread* WatcherThread::_watcher_thread   = NULL;
1281 bool WatcherThread::_startable = false;
1282 volatile bool  WatcherThread::_should_terminate = false;
1283 
1284 WatcherThread::WatcherThread() : Thread() {
1285   assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1286   if (os::create_thread(this, os::watcher_thread)) {
1287     _watcher_thread = this;
1288 
1289     // Set the watcher thread to the highest OS priority which should not be
1290     // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1291     // is created. The only normal thread using this priority is the reference
1292     // handler thread, which runs for very short intervals only.
1293     // If the VMThread's priority is not lower than the WatcherThread profiling
1294     // will be inaccurate.
1295     os::set_priority(this, MaxPriority);
1296     if (!DisableStartThread) {
1297       os::start_thread(this);
1298     }
1299   }
1300 }
1301 
1302 int WatcherThread::sleep() const {
1303   // The WatcherThread does not participate in the safepoint protocol
1304   // for the PeriodicTask_lock because it is not a JavaThread.
1305   MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1306 
1307   if (_should_terminate) {
1308     // check for termination before we do any housekeeping or wait
1309     return 0;  // we did not sleep.
1310   }
1311 
1312   // remaining will be zero if there are no tasks,
1313   // causing the WatcherThread to sleep until a task is
1314   // enrolled
1315   int remaining = PeriodicTask::time_to_wait();
1316   int time_slept = 0;
1317 
1318   // we expect this to timeout - we only ever get unparked when
1319   // we should terminate or when a new task has been enrolled
1320   OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1321 
1322   jlong time_before_loop = os::javaTimeNanos();
1323 
1324   while (true) {
1325     bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1326                                             remaining);
1327     jlong now = os::javaTimeNanos();
1328 
1329     if (remaining == 0) {
1330       // if we didn't have any tasks we could have waited for a long time
1331       // consider the time_slept zero and reset time_before_loop
1332       time_slept = 0;
1333       time_before_loop = now;
1334     } else {
1335       // need to recalculate since we might have new tasks in _tasks
1336       time_slept = (int) ((now - time_before_loop) / 1000000);
1337     }
1338 
1339     // Change to task list or spurious wakeup of some kind
1340     if (timedout || _should_terminate) {
1341       break;
1342     }
1343 
1344     remaining = PeriodicTask::time_to_wait();
1345     if (remaining == 0) {
1346       // Last task was just disenrolled so loop around and wait until
1347       // another task gets enrolled
1348       continue;
1349     }
1350 
1351     remaining -= time_slept;
1352     if (remaining <= 0) {
1353       break;
1354     }
1355   }
1356 
1357   return time_slept;
1358 }
1359 
1360 void WatcherThread::run() {
1361   assert(this == watcher_thread(), "just checking");
1362 
1363   this->record_stack_base_and_size();
1364   this->set_native_thread_name(this->name());
1365   this->set_active_handles(JNIHandleBlock::allocate_block());
1366   while (true) {
1367     assert(watcher_thread() == Thread::current(), "thread consistency check");
1368     assert(watcher_thread() == this, "thread consistency check");
1369 
1370     // Calculate how long it'll be until the next PeriodicTask work
1371     // should be done, and sleep that amount of time.
1372     int time_waited = sleep();
1373 
1374     if (VMError::is_error_reported()) {
1375       // A fatal error has happened, the error handler(VMError::report_and_die)
1376       // should abort JVM after creating an error log file. However in some
1377       // rare cases, the error handler itself might deadlock. Here periodically
1378       // check for error reporting timeouts, and if it happens, just proceed to
1379       // abort the VM.
1380 
1381       // This code is in WatcherThread because WatcherThread wakes up
1382       // periodically so the fatal error handler doesn't need to do anything;
1383       // also because the WatcherThread is less likely to crash than other
1384       // threads.
1385 
1386       for (;;) {
1387         // Note: we use naked sleep in this loop because we want to avoid using
1388         // any kind of VM infrastructure which may be broken at this point.
1389         if (VMError::check_timeout()) {
1390           // We hit error reporting timeout. Error reporting was interrupted and
1391           // will be wrapping things up now (closing files etc). Give it some more
1392           // time, then quit the VM.
1393           os::naked_short_sleep(200);
1394           // Print a message to stderr.
1395           fdStream err(defaultStream::output_fd());
1396           err.print_raw_cr("# [ timer expired, abort... ]");
1397           // skip atexit/vm_exit/vm_abort hooks
1398           os::die();
1399         }
1400 
1401         // Wait a second, then recheck for timeout.
1402         os::naked_short_sleep(999);
1403       }
1404     }
1405 
1406     if (_should_terminate) {
1407       // check for termination before posting the next tick
1408       break;
1409     }
1410 
1411     PeriodicTask::real_time_tick(time_waited);
1412   }
1413 
1414   // Signal that it is terminated
1415   {
1416     MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1417     _watcher_thread = NULL;
1418     Terminator_lock->notify();
1419   }
1420 }
1421 
1422 void WatcherThread::start() {
1423   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1424 
1425   if (watcher_thread() == NULL && _startable) {
1426     _should_terminate = false;
1427     // Create the single instance of WatcherThread
1428     new WatcherThread();
1429   }
1430 }
1431 
1432 void WatcherThread::make_startable() {
1433   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1434   _startable = true;
1435 }
1436 
1437 void WatcherThread::stop() {
1438   {
1439     // Follow normal safepoint aware lock enter protocol since the
1440     // WatcherThread is stopped by another JavaThread.
1441     MutexLocker ml(PeriodicTask_lock);
1442     _should_terminate = true;
1443 
1444     WatcherThread* watcher = watcher_thread();
1445     if (watcher != NULL) {
1446       // unpark the WatcherThread so it can see that it should terminate
1447       watcher->unpark();
1448     }
1449   }
1450 
1451   MutexLocker mu(Terminator_lock);
1452 
1453   while (watcher_thread() != NULL) {
1454     // This wait should make safepoint checks, wait without a timeout,
1455     // and wait as a suspend-equivalent condition.
1456     Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1457                           Mutex::_as_suspend_equivalent_flag);
1458   }
1459 }
1460 
1461 void WatcherThread::unpark() {
1462   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1463   PeriodicTask_lock->notify();
1464 }
1465 
1466 void WatcherThread::print_on(outputStream* st) const {
1467   st->print("\"%s\" ", name());
1468   Thread::print_on(st);
1469   st->cr();
1470 }
1471 
1472 // ======= JavaThread ========
1473 
1474 #if INCLUDE_JVMCI
1475 
1476 jlong* JavaThread::_jvmci_old_thread_counters;
1477 
1478 bool jvmci_counters_include(JavaThread* thread) {
1479   oop threadObj = thread->threadObj();
1480   return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1481 }
1482 
1483 void JavaThread::collect_counters(typeArrayOop array) {
1484   if (JVMCICounterSize > 0) {
1485     MutexLocker tl(Threads_lock);
1486     JavaThreadIteratorWithHandle jtiwh;
1487     for (int i = 0; i < array->length(); i++) {
1488       array->long_at_put(i, _jvmci_old_thread_counters[i]);
1489     }
1490     for (; JavaThread *tp = jtiwh.next(); ) {
1491       if (jvmci_counters_include(tp)) {
1492         for (int i = 0; i < array->length(); i++) {
1493           array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1494         }
1495       }
1496     }
1497   }
1498 }
1499 
1500 #endif // INCLUDE_JVMCI
1501 
1502 // A JavaThread is a normal Java thread
1503 
1504 void JavaThread::initialize() {
1505   // Initialize fields
1506 
1507   set_saved_exception_pc(NULL);
1508   set_threadObj(NULL);
1509   _anchor.clear();
1510   set_entry_point(NULL);
1511   set_jni_functions(jni_functions());
1512   set_callee_target(NULL);
1513   set_vm_result(NULL);
1514   set_vm_result_2(NULL);
1515   set_vframe_array_head(NULL);
1516   set_vframe_array_last(NULL);
1517   set_deferred_locals(NULL);
1518   set_deopt_mark(NULL);
1519   set_deopt_compiled_method(NULL);
1520   clear_must_deopt_id();
1521   set_monitor_chunks(NULL);
1522   set_next(NULL);
1523   _on_thread_list = false;
1524   set_thread_state(_thread_new);
1525   _terminated = _not_terminated;
1526   _privileged_stack_top = NULL;
1527   _array_for_gc = NULL;
1528   _suspend_equivalent = false;
1529   _in_deopt_handler = 0;
1530   _doing_unsafe_access = false;
1531   _stack_guard_state = stack_guard_unused;
1532 #if INCLUDE_JVMCI
1533   _pending_monitorenter = false;
1534   _pending_deoptimization = -1;
1535   _pending_failed_speculation = NULL;
1536   _pending_transfer_to_interpreter = false;
1537   _adjusting_comp_level = false;
1538   _jvmci._alternate_call_target = NULL;
1539   assert(_jvmci._implicit_exception_pc == NULL, "must be");
1540   if (JVMCICounterSize > 0) {
1541     _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1542     memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1543   } else {
1544     _jvmci_counters = NULL;
1545   }
1546 #endif // INCLUDE_JVMCI
1547   _reserved_stack_activation = NULL;  // stack base not known yet
1548   (void)const_cast<oop&>(_exception_oop = oop(NULL));
1549   _exception_pc  = 0;
1550   _exception_handler_pc = 0;
1551   _is_method_handle_return = 0;
1552   _jvmti_thread_state= NULL;
1553   _should_post_on_exceptions_flag = JNI_FALSE;
1554   _jvmti_get_loaded_classes_closure = NULL;
1555   _interp_only_mode    = 0;
1556   _special_runtime_exit_condition = _no_async_condition;
1557   _pending_async_exception = NULL;
1558   _thread_stat = NULL;
1559   _thread_stat = new ThreadStatistics();
1560   _blocked_on_compilation = false;
1561   _jni_active_critical = 0;
1562   _pending_jni_exception_check_fn = NULL;
1563   _do_not_unlock_if_synchronized = false;
1564   _cached_monitor_info = NULL;
1565   _parker = Parker::Allocate(this);
1566 
1567 #ifndef PRODUCT
1568   _jmp_ring_index = 0;
1569   for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1570     record_jump(NULL, NULL, NULL, 0);
1571   }
1572 #endif // PRODUCT
1573 
1574   // Setup safepoint state info for this thread
1575   ThreadSafepointState::create(this);
1576 
1577   debug_only(_java_call_counter = 0);
1578 
1579   // JVMTI PopFrame support
1580   _popframe_condition = popframe_inactive;
1581   _popframe_preserved_args = NULL;
1582   _popframe_preserved_args_size = 0;
1583   _frames_to_pop_failed_realloc = 0;
1584 
1585   if (SafepointMechanism::uses_thread_local_poll()) {
1586     SafepointMechanism::initialize_header(this);
1587   }
1588 
1589   pd_initialize();
1590 }
1591 
1592 JavaThread::JavaThread(bool is_attaching_via_jni) :
1593                        Thread()
1594 #if INCLUDE_ALL_GCS
1595                        , _satb_mark_queue(&G1BarrierSet::satb_mark_queue_set()),
1596                        _dirty_card_queue(&G1BarrierSet::dirty_card_queue_set())
1597 #endif // INCLUDE_ALL_GCS
1598 {
1599   initialize();
1600   if (is_attaching_via_jni) {
1601     _jni_attach_state = _attaching_via_jni;
1602   } else {
1603     _jni_attach_state = _not_attaching_via_jni;
1604   }
1605   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1606 }
1607 
1608 bool JavaThread::reguard_stack(address cur_sp) {
1609   if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1610       && _stack_guard_state != stack_guard_reserved_disabled) {
1611     return true; // Stack already guarded or guard pages not needed.
1612   }
1613 
1614   if (register_stack_overflow()) {
1615     // For those architectures which have separate register and
1616     // memory stacks, we must check the register stack to see if
1617     // it has overflowed.
1618     return false;
1619   }
1620 
1621   // Java code never executes within the yellow zone: the latter is only
1622   // there to provoke an exception during stack banging.  If java code
1623   // is executing there, either StackShadowPages should be larger, or
1624   // some exception code in c1, c2 or the interpreter isn't unwinding
1625   // when it should.
1626   guarantee(cur_sp > stack_reserved_zone_base(),
1627             "not enough space to reguard - increase StackShadowPages");
1628   if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1629     enable_stack_yellow_reserved_zone();
1630     if (reserved_stack_activation() != stack_base()) {
1631       set_reserved_stack_activation(stack_base());
1632     }
1633   } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1634     set_reserved_stack_activation(stack_base());
1635     enable_stack_reserved_zone();
1636   }
1637   return true;
1638 }
1639 
1640 bool JavaThread::reguard_stack(void) {
1641   return reguard_stack(os::current_stack_pointer());
1642 }
1643 
1644 
1645 void JavaThread::block_if_vm_exited() {
1646   if (_terminated == _vm_exited) {
1647     // _vm_exited is set at safepoint, and Threads_lock is never released
1648     // we will block here forever
1649     Threads_lock->lock_without_safepoint_check();
1650     ShouldNotReachHere();
1651   }
1652 }
1653 
1654 
1655 // Remove this ifdef when C1 is ported to the compiler interface.
1656 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1657 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1658 
1659 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1660                        Thread()
1661 #if INCLUDE_ALL_GCS
1662                        , _satb_mark_queue(&G1BarrierSet::satb_mark_queue_set()),
1663                        _dirty_card_queue(&G1BarrierSet::dirty_card_queue_set())
1664 #endif // INCLUDE_ALL_GCS
1665 {
1666   initialize();
1667   _jni_attach_state = _not_attaching_via_jni;
1668   set_entry_point(entry_point);
1669   // Create the native thread itself.
1670   // %note runtime_23
1671   os::ThreadType thr_type = os::java_thread;
1672   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1673                                                      os::java_thread;
1674   os::create_thread(this, thr_type, stack_sz);
1675   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1676   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1677   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1678   // the exception consists of creating the exception object & initializing it, initialization
1679   // will leave the VM via a JavaCall and then all locks must be unlocked).
1680   //
1681   // The thread is still suspended when we reach here. Thread must be explicit started
1682   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1683   // by calling Threads:add. The reason why this is not done here, is because the thread
1684   // object must be fully initialized (take a look at JVM_Start)
1685 }
1686 
1687 JavaThread::~JavaThread() {
1688 
1689   // JSR166 -- return the parker to the free list
1690   Parker::Release(_parker);
1691   _parker = NULL;
1692 
1693   // Free any remaining  previous UnrollBlock
1694   vframeArray* old_array = vframe_array_last();
1695 
1696   if (old_array != NULL) {
1697     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1698     old_array->set_unroll_block(NULL);
1699     delete old_info;
1700     delete old_array;
1701   }
1702 
1703   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1704   if (deferred != NULL) {
1705     // This can only happen if thread is destroyed before deoptimization occurs.
1706     assert(deferred->length() != 0, "empty array!");
1707     do {
1708       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1709       deferred->remove_at(0);
1710       // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1711       delete dlv;
1712     } while (deferred->length() != 0);
1713     delete deferred;
1714   }
1715 
1716   // All Java related clean up happens in exit
1717   ThreadSafepointState::destroy(this);
1718   if (_thread_stat != NULL) delete _thread_stat;
1719 
1720 #if INCLUDE_JVMCI
1721   if (JVMCICounterSize > 0) {
1722     if (jvmci_counters_include(this)) {
1723       for (int i = 0; i < JVMCICounterSize; i++) {
1724         _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1725       }
1726     }
1727     FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1728   }
1729 #endif // INCLUDE_JVMCI
1730 }
1731 
1732 
1733 // The first routine called by a new Java thread
1734 void JavaThread::run() {
1735   // initialize thread-local alloc buffer related fields
1736   this->initialize_tlab();
1737 
1738   // used to test validity of stack trace backs
1739   this->record_base_of_stack_pointer();
1740 
1741   // Record real stack base and size.
1742   this->record_stack_base_and_size();
1743 
1744   this->create_stack_guard_pages();
1745 
1746   this->cache_global_variables();
1747 
1748   // Thread is now sufficient initialized to be handled by the safepoint code as being
1749   // in the VM. Change thread state from _thread_new to _thread_in_vm
1750   ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1751 
1752   assert(JavaThread::current() == this, "sanity check");
1753   assert(!Thread::current()->owns_locks(), "sanity check");
1754 
1755   DTRACE_THREAD_PROBE(start, this);
1756 
1757   // This operation might block. We call that after all safepoint checks for a new thread has
1758   // been completed.
1759   this->set_active_handles(JNIHandleBlock::allocate_block());
1760 
1761   if (JvmtiExport::should_post_thread_life()) {
1762     JvmtiExport::post_thread_start(this);
1763   }
1764 
1765   EventThreadStart event;
1766   if (event.should_commit()) {
1767     event.set_thread(THREAD_TRACE_ID(this));
1768     event.commit();
1769   }
1770 
1771   // We call another function to do the rest so we are sure that the stack addresses used
1772   // from there will be lower than the stack base just computed
1773   thread_main_inner();
1774 
1775   // Note, thread is no longer valid at this point!
1776 }
1777 
1778 
1779 void JavaThread::thread_main_inner() {
1780   assert(JavaThread::current() == this, "sanity check");
1781   assert(this->threadObj() != NULL, "just checking");
1782 
1783   // Execute thread entry point unless this thread has a pending exception
1784   // or has been stopped before starting.
1785   // Note: Due to JVM_StopThread we can have pending exceptions already!
1786   if (!this->has_pending_exception() &&
1787       !java_lang_Thread::is_stillborn(this->threadObj())) {
1788     {
1789       ResourceMark rm(this);
1790       this->set_native_thread_name(this->get_thread_name());
1791     }
1792     HandleMark hm(this);
1793     this->entry_point()(this, this);
1794   }
1795 
1796   DTRACE_THREAD_PROBE(stop, this);
1797 
1798   this->exit(false);
1799   this->smr_delete();
1800 }
1801 
1802 
1803 static void ensure_join(JavaThread* thread) {
1804   // We do not need to grab the Threads_lock, since we are operating on ourself.
1805   Handle threadObj(thread, thread->threadObj());
1806   assert(threadObj.not_null(), "java thread object must exist");
1807   ObjectLocker lock(threadObj, thread);
1808   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1809   thread->clear_pending_exception();
1810   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1811   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1812   // Clear the native thread instance - this makes isAlive return false and allows the join()
1813   // to complete once we've done the notify_all below
1814   java_lang_Thread::set_thread(threadObj(), NULL);
1815   lock.notify_all(thread);
1816   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1817   thread->clear_pending_exception();
1818 }
1819 
1820 
1821 // For any new cleanup additions, please check to see if they need to be applied to
1822 // cleanup_failed_attach_current_thread as well.
1823 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1824   assert(this == JavaThread::current(), "thread consistency check");
1825 
1826   elapsedTimer _timer_exit_phase1;
1827   elapsedTimer _timer_exit_phase2;
1828   elapsedTimer _timer_exit_phase3;
1829   elapsedTimer _timer_exit_phase4;
1830 
1831   if (log_is_enabled(Debug, os, thread, timer)) {
1832     _timer_exit_phase1.start();
1833   }
1834 
1835   HandleMark hm(this);
1836   Handle uncaught_exception(this, this->pending_exception());
1837   this->clear_pending_exception();
1838   Handle threadObj(this, this->threadObj());
1839   assert(threadObj.not_null(), "Java thread object should be created");
1840 
1841   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1842   {
1843     EXCEPTION_MARK;
1844 
1845     CLEAR_PENDING_EXCEPTION;
1846   }
1847   if (!destroy_vm) {
1848     if (uncaught_exception.not_null()) {
1849       EXCEPTION_MARK;
1850       // Call method Thread.dispatchUncaughtException().
1851       Klass* thread_klass = SystemDictionary::Thread_klass();
1852       JavaValue result(T_VOID);
1853       JavaCalls::call_virtual(&result,
1854                               threadObj, thread_klass,
1855                               vmSymbols::dispatchUncaughtException_name(),
1856                               vmSymbols::throwable_void_signature(),
1857                               uncaught_exception,
1858                               THREAD);
1859       if (HAS_PENDING_EXCEPTION) {
1860         ResourceMark rm(this);
1861         jio_fprintf(defaultStream::error_stream(),
1862                     "\nException: %s thrown from the UncaughtExceptionHandler"
1863                     " in thread \"%s\"\n",
1864                     pending_exception()->klass()->external_name(),
1865                     get_thread_name());
1866         CLEAR_PENDING_EXCEPTION;
1867       }
1868     }
1869 
1870     // Called before the java thread exit since we want to read info
1871     // from java_lang_Thread object
1872     EventThreadEnd event;
1873     if (event.should_commit()) {
1874       event.set_thread(THREAD_TRACE_ID(this));
1875       event.commit();
1876     }
1877 
1878     // Call after last event on thread
1879     EVENT_THREAD_EXIT(this);
1880 
1881     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1882     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1883     // is deprecated anyhow.
1884     if (!is_Compiler_thread()) {
1885       int count = 3;
1886       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1887         EXCEPTION_MARK;
1888         JavaValue result(T_VOID);
1889         Klass* thread_klass = SystemDictionary::Thread_klass();
1890         JavaCalls::call_virtual(&result,
1891                                 threadObj, thread_klass,
1892                                 vmSymbols::exit_method_name(),
1893                                 vmSymbols::void_method_signature(),
1894                                 THREAD);
1895         CLEAR_PENDING_EXCEPTION;
1896       }
1897     }
1898     // notify JVMTI
1899     if (JvmtiExport::should_post_thread_life()) {
1900       JvmtiExport::post_thread_end(this);
1901     }
1902 
1903     // We have notified the agents that we are exiting, before we go on,
1904     // we must check for a pending external suspend request and honor it
1905     // in order to not surprise the thread that made the suspend request.
1906     while (true) {
1907       {
1908         MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1909         if (!is_external_suspend()) {
1910           set_terminated(_thread_exiting);
1911           ThreadService::current_thread_exiting(this);
1912           break;
1913         }
1914         // Implied else:
1915         // Things get a little tricky here. We have a pending external
1916         // suspend request, but we are holding the SR_lock so we
1917         // can't just self-suspend. So we temporarily drop the lock
1918         // and then self-suspend.
1919       }
1920 
1921       ThreadBlockInVM tbivm(this);
1922       java_suspend_self();
1923 
1924       // We're done with this suspend request, but we have to loop around
1925       // and check again. Eventually we will get SR_lock without a pending
1926       // external suspend request and will be able to mark ourselves as
1927       // exiting.
1928     }
1929     // no more external suspends are allowed at this point
1930   } else {
1931     // before_exit() has already posted JVMTI THREAD_END events
1932   }
1933 
1934   if (log_is_enabled(Debug, os, thread, timer)) {
1935     _timer_exit_phase1.stop();
1936     _timer_exit_phase2.start();
1937   }
1938   // Notify waiters on thread object. This has to be done after exit() is called
1939   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1940   // group should have the destroyed bit set before waiters are notified).
1941   ensure_join(this);
1942   assert(!this->has_pending_exception(), "ensure_join should have cleared");
1943 
1944   if (log_is_enabled(Debug, os, thread, timer)) {
1945     _timer_exit_phase2.stop();
1946     _timer_exit_phase3.start();
1947   }
1948   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1949   // held by this thread must be released. The spec does not distinguish
1950   // between JNI-acquired and regular Java monitors. We can only see
1951   // regular Java monitors here if monitor enter-exit matching is broken.
1952   //
1953   // Optionally release any monitors for regular JavaThread exits. This
1954   // is provided as a work around for any bugs in monitor enter-exit
1955   // matching. This can be expensive so it is not enabled by default.
1956   //
1957   // ensure_join() ignores IllegalThreadStateExceptions, and so does
1958   // ObjectSynchronizer::release_monitors_owned_by_thread().
1959   if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1960     // Sanity check even though JNI DetachCurrentThread() would have
1961     // returned JNI_ERR if there was a Java frame. JavaThread exit
1962     // should be done executing Java code by the time we get here.
1963     assert(!this->has_last_Java_frame(),
1964            "should not have a Java frame when detaching or exiting");
1965     ObjectSynchronizer::release_monitors_owned_by_thread(this);
1966     assert(!this->has_pending_exception(), "release_monitors should have cleared");
1967   }
1968 
1969   // These things needs to be done while we are still a Java Thread. Make sure that thread
1970   // is in a consistent state, in case GC happens
1971   assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1972 
1973   if (active_handles() != NULL) {
1974     JNIHandleBlock* block = active_handles();
1975     set_active_handles(NULL);
1976     JNIHandleBlock::release_block(block);
1977   }
1978 
1979   if (free_handle_block() != NULL) {
1980     JNIHandleBlock* block = free_handle_block();
1981     set_free_handle_block(NULL);
1982     JNIHandleBlock::release_block(block);
1983   }
1984 
1985   // These have to be removed while this is still a valid thread.
1986   remove_stack_guard_pages();
1987 
1988   if (UseTLAB) {
1989     tlab().make_parsable(true);  // retire TLAB
1990   }
1991 
1992   if (JvmtiEnv::environments_might_exist()) {
1993     JvmtiExport::cleanup_thread(this);
1994   }
1995 
1996   // We must flush any deferred card marks and other various GC barrier
1997   // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
1998   // before removing a thread from the list of active threads.
1999   BarrierSet::barrier_set()->on_thread_detach(this);
2000 
2001   log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2002     exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2003     os::current_thread_id());
2004 
2005   if (log_is_enabled(Debug, os, thread, timer)) {
2006     _timer_exit_phase3.stop();
2007     _timer_exit_phase4.start();
2008   }
2009   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2010   Threads::remove(this);
2011 
2012   if (log_is_enabled(Debug, os, thread, timer)) {
2013     _timer_exit_phase4.stop();
2014     ResourceMark rm(this);
2015     log_debug(os, thread, timer)("name='%s'"
2016                                  ", exit-phase1=" JLONG_FORMAT
2017                                  ", exit-phase2=" JLONG_FORMAT
2018                                  ", exit-phase3=" JLONG_FORMAT
2019                                  ", exit-phase4=" JLONG_FORMAT,
2020                                  get_thread_name(),
2021                                  _timer_exit_phase1.milliseconds(),
2022                                  _timer_exit_phase2.milliseconds(),
2023                                  _timer_exit_phase3.milliseconds(),
2024                                  _timer_exit_phase4.milliseconds());
2025   }
2026 }
2027 
2028 void JavaThread::cleanup_failed_attach_current_thread() {
2029   if (active_handles() != NULL) {
2030     JNIHandleBlock* block = active_handles();
2031     set_active_handles(NULL);
2032     JNIHandleBlock::release_block(block);
2033   }
2034 
2035   if (free_handle_block() != NULL) {
2036     JNIHandleBlock* block = free_handle_block();
2037     set_free_handle_block(NULL);
2038     JNIHandleBlock::release_block(block);
2039   }
2040 
2041   // These have to be removed while this is still a valid thread.
2042   remove_stack_guard_pages();
2043 
2044   if (UseTLAB) {
2045     tlab().make_parsable(true);  // retire TLAB, if any
2046   }
2047 
2048   BarrierSet::barrier_set()->on_thread_detach(this);
2049 
2050   Threads::remove(this);
2051   this->smr_delete();
2052 }
2053 
2054 JavaThread* JavaThread::active() {
2055   Thread* thread = Thread::current();
2056   if (thread->is_Java_thread()) {
2057     return (JavaThread*) thread;
2058   } else {
2059     assert(thread->is_VM_thread(), "this must be a vm thread");
2060     VM_Operation* op = ((VMThread*) thread)->vm_operation();
2061     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2062     assert(ret->is_Java_thread(), "must be a Java thread");
2063     return ret;
2064   }
2065 }
2066 
2067 bool JavaThread::is_lock_owned(address adr) const {
2068   if (Thread::is_lock_owned(adr)) return true;
2069 
2070   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2071     if (chunk->contains(adr)) return true;
2072   }
2073 
2074   return false;
2075 }
2076 
2077 
2078 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2079   chunk->set_next(monitor_chunks());
2080   set_monitor_chunks(chunk);
2081 }
2082 
2083 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2084   guarantee(monitor_chunks() != NULL, "must be non empty");
2085   if (monitor_chunks() == chunk) {
2086     set_monitor_chunks(chunk->next());
2087   } else {
2088     MonitorChunk* prev = monitor_chunks();
2089     while (prev->next() != chunk) prev = prev->next();
2090     prev->set_next(chunk->next());
2091   }
2092 }
2093 
2094 // JVM support.
2095 
2096 // Note: this function shouldn't block if it's called in
2097 // _thread_in_native_trans state (such as from
2098 // check_special_condition_for_native_trans()).
2099 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2100 
2101   if (has_last_Java_frame() && has_async_condition()) {
2102     // If we are at a polling page safepoint (not a poll return)
2103     // then we must defer async exception because live registers
2104     // will be clobbered by the exception path. Poll return is
2105     // ok because the call we a returning from already collides
2106     // with exception handling registers and so there is no issue.
2107     // (The exception handling path kills call result registers but
2108     //  this is ok since the exception kills the result anyway).
2109 
2110     if (is_at_poll_safepoint()) {
2111       // if the code we are returning to has deoptimized we must defer
2112       // the exception otherwise live registers get clobbered on the
2113       // exception path before deoptimization is able to retrieve them.
2114       //
2115       RegisterMap map(this, false);
2116       frame caller_fr = last_frame().sender(&map);
2117       assert(caller_fr.is_compiled_frame(), "what?");
2118       if (caller_fr.is_deoptimized_frame()) {
2119         log_info(exceptions)("deferred async exception at compiled safepoint");
2120         return;
2121       }
2122     }
2123   }
2124 
2125   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2126   if (condition == _no_async_condition) {
2127     // Conditions have changed since has_special_runtime_exit_condition()
2128     // was called:
2129     // - if we were here only because of an external suspend request,
2130     //   then that was taken care of above (or cancelled) so we are done
2131     // - if we were here because of another async request, then it has
2132     //   been cleared between the has_special_runtime_exit_condition()
2133     //   and now so again we are done
2134     return;
2135   }
2136 
2137   // Check for pending async. exception
2138   if (_pending_async_exception != NULL) {
2139     // Only overwrite an already pending exception, if it is not a threadDeath.
2140     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2141 
2142       // We cannot call Exceptions::_throw(...) here because we cannot block
2143       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2144 
2145       LogTarget(Info, exceptions) lt;
2146       if (lt.is_enabled()) {
2147         ResourceMark rm;
2148         LogStream ls(lt);
2149         ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2150           if (has_last_Java_frame()) {
2151             frame f = last_frame();
2152            ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2153           }
2154         ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2155       }
2156       _pending_async_exception = NULL;
2157       clear_has_async_exception();
2158     }
2159   }
2160 
2161   if (check_unsafe_error &&
2162       condition == _async_unsafe_access_error && !has_pending_exception()) {
2163     condition = _no_async_condition;  // done
2164     switch (thread_state()) {
2165     case _thread_in_vm: {
2166       JavaThread* THREAD = this;
2167       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2168     }
2169     case _thread_in_native: {
2170       ThreadInVMfromNative tiv(this);
2171       JavaThread* THREAD = this;
2172       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2173     }
2174     case _thread_in_Java: {
2175       ThreadInVMfromJava tiv(this);
2176       JavaThread* THREAD = this;
2177       THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2178     }
2179     default:
2180       ShouldNotReachHere();
2181     }
2182   }
2183 
2184   assert(condition == _no_async_condition || has_pending_exception() ||
2185          (!check_unsafe_error && condition == _async_unsafe_access_error),
2186          "must have handled the async condition, if no exception");
2187 }
2188 
2189 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2190   //
2191   // Check for pending external suspend. Internal suspend requests do
2192   // not use handle_special_runtime_exit_condition().
2193   // If JNIEnv proxies are allowed, don't self-suspend if the target
2194   // thread is not the current thread. In older versions of jdbx, jdbx
2195   // threads could call into the VM with another thread's JNIEnv so we
2196   // can be here operating on behalf of a suspended thread (4432884).
2197   bool do_self_suspend = is_external_suspend_with_lock();
2198   if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2199     //
2200     // Because thread is external suspended the safepoint code will count
2201     // thread as at a safepoint. This can be odd because we can be here
2202     // as _thread_in_Java which would normally transition to _thread_blocked
2203     // at a safepoint. We would like to mark the thread as _thread_blocked
2204     // before calling java_suspend_self like all other callers of it but
2205     // we must then observe proper safepoint protocol. (We can't leave
2206     // _thread_blocked with a safepoint in progress). However we can be
2207     // here as _thread_in_native_trans so we can't use a normal transition
2208     // constructor/destructor pair because they assert on that type of
2209     // transition. We could do something like:
2210     //
2211     // JavaThreadState state = thread_state();
2212     // set_thread_state(_thread_in_vm);
2213     // {
2214     //   ThreadBlockInVM tbivm(this);
2215     //   java_suspend_self()
2216     // }
2217     // set_thread_state(_thread_in_vm_trans);
2218     // if (safepoint) block;
2219     // set_thread_state(state);
2220     //
2221     // but that is pretty messy. Instead we just go with the way the
2222     // code has worked before and note that this is the only path to
2223     // java_suspend_self that doesn't put the thread in _thread_blocked
2224     // mode.
2225 
2226     frame_anchor()->make_walkable(this);
2227     java_suspend_self();
2228 
2229     // We might be here for reasons in addition to the self-suspend request
2230     // so check for other async requests.
2231   }
2232 
2233   if (check_asyncs) {
2234     check_and_handle_async_exceptions();
2235   }
2236 #if INCLUDE_TRACE
2237   if (is_trace_suspend()) {
2238     TRACE_SUSPEND_THREAD(this);
2239   }
2240 #endif
2241 }
2242 
2243 void JavaThread::send_thread_stop(oop java_throwable)  {
2244   assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2245   assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2246   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2247 
2248   // Do not throw asynchronous exceptions against the compiler thread
2249   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2250   if (!can_call_java()) return;
2251 
2252   {
2253     // Actually throw the Throwable against the target Thread - however
2254     // only if there is no thread death exception installed already.
2255     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2256       // If the topmost frame is a runtime stub, then we are calling into
2257       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2258       // must deoptimize the caller before continuing, as the compiled  exception handler table
2259       // may not be valid
2260       if (has_last_Java_frame()) {
2261         frame f = last_frame();
2262         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2263           // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2264           RegisterMap reg_map(this, UseBiasedLocking);
2265           frame compiled_frame = f.sender(&reg_map);
2266           if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2267             Deoptimization::deoptimize(this, compiled_frame, &reg_map);
2268           }
2269         }
2270       }
2271 
2272       // Set async. pending exception in thread.
2273       set_pending_async_exception(java_throwable);
2274 
2275       if (log_is_enabled(Info, exceptions)) {
2276          ResourceMark rm;
2277         log_info(exceptions)("Pending Async. exception installed of type: %s",
2278                              InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2279       }
2280       // for AbortVMOnException flag
2281       Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2282     }
2283   }
2284 
2285 
2286   // Interrupt thread so it will wake up from a potential wait()
2287   Thread::interrupt(this);
2288 }
2289 
2290 // External suspension mechanism.
2291 //
2292 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2293 // to any VM_locks and it is at a transition
2294 // Self-suspension will happen on the transition out of the vm.
2295 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2296 //
2297 // Guarantees on return:
2298 //   + Target thread will not execute any new bytecode (that's why we need to
2299 //     force a safepoint)
2300 //   + Target thread will not enter any new monitors
2301 //
2302 void JavaThread::java_suspend() {
2303   ThreadsListHandle tlh;
2304   if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2305     return;
2306   }
2307 
2308   { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2309     if (!is_external_suspend()) {
2310       // a racing resume has cancelled us; bail out now
2311       return;
2312     }
2313 
2314     // suspend is done
2315     uint32_t debug_bits = 0;
2316     // Warning: is_ext_suspend_completed() may temporarily drop the
2317     // SR_lock to allow the thread to reach a stable thread state if
2318     // it is currently in a transient thread state.
2319     if (is_ext_suspend_completed(false /* !called_by_wait */,
2320                                  SuspendRetryDelay, &debug_bits)) {
2321       return;
2322     }
2323   }
2324 
2325   VM_ThreadSuspend vm_suspend;
2326   VMThread::execute(&vm_suspend);
2327 }
2328 
2329 // Part II of external suspension.
2330 // A JavaThread self suspends when it detects a pending external suspend
2331 // request. This is usually on transitions. It is also done in places
2332 // where continuing to the next transition would surprise the caller,
2333 // e.g., monitor entry.
2334 //
2335 // Returns the number of times that the thread self-suspended.
2336 //
2337 // Note: DO NOT call java_suspend_self() when you just want to block current
2338 //       thread. java_suspend_self() is the second stage of cooperative
2339 //       suspension for external suspend requests and should only be used
2340 //       to complete an external suspend request.
2341 //
2342 int JavaThread::java_suspend_self() {
2343   int ret = 0;
2344 
2345   // we are in the process of exiting so don't suspend
2346   if (is_exiting()) {
2347     clear_external_suspend();
2348     return ret;
2349   }
2350 
2351   assert(_anchor.walkable() ||
2352          (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2353          "must have walkable stack");
2354 
2355   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2356 
2357   assert(!this->is_ext_suspended(),
2358          "a thread trying to self-suspend should not already be suspended");
2359 
2360   if (this->is_suspend_equivalent()) {
2361     // If we are self-suspending as a result of the lifting of a
2362     // suspend equivalent condition, then the suspend_equivalent
2363     // flag is not cleared until we set the ext_suspended flag so
2364     // that wait_for_ext_suspend_completion() returns consistent
2365     // results.
2366     this->clear_suspend_equivalent();
2367   }
2368 
2369   // A racing resume may have cancelled us before we grabbed SR_lock
2370   // above. Or another external suspend request could be waiting for us
2371   // by the time we return from SR_lock()->wait(). The thread
2372   // that requested the suspension may already be trying to walk our
2373   // stack and if we return now, we can change the stack out from under
2374   // it. This would be a "bad thing (TM)" and cause the stack walker
2375   // to crash. We stay self-suspended until there are no more pending
2376   // external suspend requests.
2377   while (is_external_suspend()) {
2378     ret++;
2379     this->set_ext_suspended();
2380 
2381     // _ext_suspended flag is cleared by java_resume()
2382     while (is_ext_suspended()) {
2383       this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2384     }
2385   }
2386 
2387   return ret;
2388 }
2389 
2390 #ifdef ASSERT
2391 // Verify the JavaThread has not yet been published in the Threads::list, and
2392 // hence doesn't need protection from concurrent access at this stage.
2393 void JavaThread::verify_not_published() {
2394   // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
2395   // since an unpublished JavaThread doesn't participate in the
2396   // Thread-SMR protocol for keeping a ThreadsList alive.
2397   assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
2398 }
2399 #endif
2400 
2401 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2402 // progress or when _suspend_flags is non-zero.
2403 // Current thread needs to self-suspend if there is a suspend request and/or
2404 // block if a safepoint is in progress.
2405 // Async exception ISN'T checked.
2406 // Note only the ThreadInVMfromNative transition can call this function
2407 // directly and when thread state is _thread_in_native_trans
2408 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2409   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2410 
2411   JavaThread *curJT = JavaThread::current();
2412   bool do_self_suspend = thread->is_external_suspend();
2413 
2414   assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2415 
2416   // If JNIEnv proxies are allowed, don't self-suspend if the target
2417   // thread is not the current thread. In older versions of jdbx, jdbx
2418   // threads could call into the VM with another thread's JNIEnv so we
2419   // can be here operating on behalf of a suspended thread (4432884).
2420   if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2421     JavaThreadState state = thread->thread_state();
2422 
2423     // We mark this thread_blocked state as a suspend-equivalent so
2424     // that a caller to is_ext_suspend_completed() won't be confused.
2425     // The suspend-equivalent state is cleared by java_suspend_self().
2426     thread->set_suspend_equivalent();
2427 
2428     // If the safepoint code sees the _thread_in_native_trans state, it will
2429     // wait until the thread changes to other thread state. There is no
2430     // guarantee on how soon we can obtain the SR_lock and complete the
2431     // self-suspend request. It would be a bad idea to let safepoint wait for
2432     // too long. Temporarily change the state to _thread_blocked to
2433     // let the VM thread know that this thread is ready for GC. The problem
2434     // of changing thread state is that safepoint could happen just after
2435     // java_suspend_self() returns after being resumed, and VM thread will
2436     // see the _thread_blocked state. We must check for safepoint
2437     // after restoring the state and make sure we won't leave while a safepoint
2438     // is in progress.
2439     thread->set_thread_state(_thread_blocked);
2440     thread->java_suspend_self();
2441     thread->set_thread_state(state);
2442 
2443     InterfaceSupport::serialize_thread_state_with_handler(thread);
2444   }
2445 
2446   SafepointMechanism::block_if_requested(curJT);
2447 
2448   if (thread->is_deopt_suspend()) {
2449     thread->clear_deopt_suspend();
2450     RegisterMap map(thread, false);
2451     frame f = thread->last_frame();
2452     while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2453       f = f.sender(&map);
2454     }
2455     if (f.id() == thread->must_deopt_id()) {
2456       thread->clear_must_deopt_id();
2457       f.deoptimize(thread);
2458     } else {
2459       fatal("missed deoptimization!");
2460     }
2461   }
2462 #if INCLUDE_TRACE
2463   if (thread->is_trace_suspend()) {
2464     TRACE_SUSPEND_THREAD(thread);
2465   }
2466 #endif
2467 }
2468 
2469 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2470 // progress or when _suspend_flags is non-zero.
2471 // Current thread needs to self-suspend if there is a suspend request and/or
2472 // block if a safepoint is in progress.
2473 // Also check for pending async exception (not including unsafe access error).
2474 // Note only the native==>VM/Java barriers can call this function and when
2475 // thread state is _thread_in_native_trans.
2476 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2477   check_safepoint_and_suspend_for_native_trans(thread);
2478 
2479   if (thread->has_async_exception()) {
2480     // We are in _thread_in_native_trans state, don't handle unsafe
2481     // access error since that may block.
2482     thread->check_and_handle_async_exceptions(false);
2483   }
2484 }
2485 
2486 // This is a variant of the normal
2487 // check_special_condition_for_native_trans with slightly different
2488 // semantics for use by critical native wrappers.  It does all the
2489 // normal checks but also performs the transition back into
2490 // thread_in_Java state.  This is required so that critical natives
2491 // can potentially block and perform a GC if they are the last thread
2492 // exiting the GCLocker.
2493 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2494   check_special_condition_for_native_trans(thread);
2495 
2496   // Finish the transition
2497   thread->set_thread_state(_thread_in_Java);
2498 
2499   if (thread->do_critical_native_unlock()) {
2500     ThreadInVMfromJavaNoAsyncException tiv(thread);
2501     GCLocker::unlock_critical(thread);
2502     thread->clear_critical_native_unlock();
2503   }
2504 }
2505 
2506 // We need to guarantee the Threads_lock here, since resumes are not
2507 // allowed during safepoint synchronization
2508 // Can only resume from an external suspension
2509 void JavaThread::java_resume() {
2510   assert_locked_or_safepoint(Threads_lock);
2511 
2512   // Sanity check: thread is gone, has started exiting or the thread
2513   // was not externally suspended.
2514   ThreadsListHandle tlh;
2515   if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2516     return;
2517   }
2518 
2519   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2520 
2521   clear_external_suspend();
2522 
2523   if (is_ext_suspended()) {
2524     clear_ext_suspended();
2525     SR_lock()->notify_all();
2526   }
2527 }
2528 
2529 size_t JavaThread::_stack_red_zone_size = 0;
2530 size_t JavaThread::_stack_yellow_zone_size = 0;
2531 size_t JavaThread::_stack_reserved_zone_size = 0;
2532 size_t JavaThread::_stack_shadow_zone_size = 0;
2533 
2534 void JavaThread::create_stack_guard_pages() {
2535   if (!os::uses_stack_guard_pages() ||
2536       _stack_guard_state != stack_guard_unused ||
2537       (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2538       log_info(os, thread)("Stack guard page creation for thread "
2539                            UINTX_FORMAT " disabled", os::current_thread_id());
2540     return;
2541   }
2542   address low_addr = stack_end();
2543   size_t len = stack_guard_zone_size();
2544 
2545   assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2546   assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2547 
2548   int must_commit = os::must_commit_stack_guard_pages();
2549   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2550 
2551   if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2552     log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2553     return;
2554   }
2555 
2556   if (os::guard_memory((char *) low_addr, len)) {
2557     _stack_guard_state = stack_guard_enabled;
2558   } else {
2559     log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2560       PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2561     if (os::uncommit_memory((char *) low_addr, len)) {
2562       log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2563     }
2564     return;
2565   }
2566 
2567   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2568     PTR_FORMAT "-" PTR_FORMAT ".",
2569     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2570 }
2571 
2572 void JavaThread::remove_stack_guard_pages() {
2573   assert(Thread::current() == this, "from different thread");
2574   if (_stack_guard_state == stack_guard_unused) return;
2575   address low_addr = stack_end();
2576   size_t len = stack_guard_zone_size();
2577 
2578   if (os::must_commit_stack_guard_pages()) {
2579     if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2580       _stack_guard_state = stack_guard_unused;
2581     } else {
2582       log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2583         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2584       return;
2585     }
2586   } else {
2587     if (_stack_guard_state == stack_guard_unused) return;
2588     if (os::unguard_memory((char *) low_addr, len)) {
2589       _stack_guard_state = stack_guard_unused;
2590     } else {
2591       log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2592         PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2593       return;
2594     }
2595   }
2596 
2597   log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2598     PTR_FORMAT "-" PTR_FORMAT ".",
2599     os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2600 }
2601 
2602 void JavaThread::enable_stack_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 stack's point of view, growing downward.
2607   // We need to adjust it to work correctly with guard_memory()
2608   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2609 
2610   guarantee(base < stack_base(),"Error calculating stack reserved zone");
2611   guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2612 
2613   if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2614     _stack_guard_state = stack_guard_enabled;
2615   } else {
2616     warning("Attempt to guard stack reserved zone failed.");
2617   }
2618   enable_register_stack_guard();
2619 }
2620 
2621 void JavaThread::disable_stack_reserved_zone() {
2622   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2623   assert(_stack_guard_state != stack_guard_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 stack's point of view, growing downward.
2629   // We need to adjust it to work correctly with guard_memory()
2630   address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2631 
2632   if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2633     _stack_guard_state = stack_guard_reserved_disabled;
2634   } else {
2635     warning("Attempt to unguard stack reserved zone failed.");
2636   }
2637   disable_register_stack_guard();
2638 }
2639 
2640 void JavaThread::enable_stack_yellow_reserved_zone() {
2641   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2642   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2643 
2644   // The base notation is from the stacks point of view, growing downward.
2645   // We need to adjust it to work correctly with guard_memory()
2646   address base = stack_red_zone_base();
2647 
2648   guarantee(base < stack_base(), "Error calculating stack yellow zone");
2649   guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2650 
2651   if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2652     _stack_guard_state = stack_guard_enabled;
2653   } else {
2654     warning("Attempt to guard stack yellow zone failed.");
2655   }
2656   enable_register_stack_guard();
2657 }
2658 
2659 void JavaThread::disable_stack_yellow_reserved_zone() {
2660   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2661   assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2662 
2663   // Simply return if called for a thread that does not use guard pages.
2664   if (_stack_guard_state == stack_guard_unused) return;
2665 
2666   // The base notation is from the stacks point of view, growing downward.
2667   // We need to adjust it to work correctly with guard_memory()
2668   address base = stack_red_zone_base();
2669 
2670   if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2671     _stack_guard_state = stack_guard_yellow_reserved_disabled;
2672   } else {
2673     warning("Attempt to unguard stack yellow zone failed.");
2674   }
2675   disable_register_stack_guard();
2676 }
2677 
2678 void JavaThread::enable_stack_red_zone() {
2679   // The base notation is from the stacks point of view, growing downward.
2680   // We need to adjust it to work correctly with guard_memory()
2681   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2682   address base = stack_red_zone_base() - stack_red_zone_size();
2683 
2684   guarantee(base < stack_base(), "Error calculating stack red zone");
2685   guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2686 
2687   if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2688     warning("Attempt to guard stack red zone failed.");
2689   }
2690 }
2691 
2692 void JavaThread::disable_stack_red_zone() {
2693   // The base notation is from the stacks point of view, growing downward.
2694   // We need to adjust it to work correctly with guard_memory()
2695   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2696   address base = stack_red_zone_base() - stack_red_zone_size();
2697   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2698     warning("Attempt to unguard stack red zone failed.");
2699   }
2700 }
2701 
2702 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2703   // ignore is there is no stack
2704   if (!has_last_Java_frame()) return;
2705   // traverse the stack frames. Starts from top frame.
2706   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2707     frame* fr = fst.current();
2708     f(fr, fst.register_map());
2709   }
2710 }
2711 
2712 
2713 #ifndef PRODUCT
2714 // Deoptimization
2715 // Function for testing deoptimization
2716 void JavaThread::deoptimize() {
2717   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2718   StackFrameStream fst(this, UseBiasedLocking);
2719   bool deopt = false;           // Dump stack only if a deopt actually happens.
2720   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2721   // Iterate over all frames in the thread and deoptimize
2722   for (; !fst.is_done(); fst.next()) {
2723     if (fst.current()->can_be_deoptimized()) {
2724 
2725       if (only_at) {
2726         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
2727         // consists of comma or carriage return separated numbers so
2728         // search for the current bci in that string.
2729         address pc = fst.current()->pc();
2730         nmethod* nm =  (nmethod*) fst.current()->cb();
2731         ScopeDesc* sd = nm->scope_desc_at(pc);
2732         char buffer[8];
2733         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2734         size_t len = strlen(buffer);
2735         const char * found = strstr(DeoptimizeOnlyAt, buffer);
2736         while (found != NULL) {
2737           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2738               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2739             // Check that the bci found is bracketed by terminators.
2740             break;
2741           }
2742           found = strstr(found + 1, buffer);
2743         }
2744         if (!found) {
2745           continue;
2746         }
2747       }
2748 
2749       if (DebugDeoptimization && !deopt) {
2750         deopt = true; // One-time only print before deopt
2751         tty->print_cr("[BEFORE Deoptimization]");
2752         trace_frames();
2753         trace_stack();
2754       }
2755       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2756     }
2757   }
2758 
2759   if (DebugDeoptimization && deopt) {
2760     tty->print_cr("[AFTER Deoptimization]");
2761     trace_frames();
2762   }
2763 }
2764 
2765 
2766 // Make zombies
2767 void JavaThread::make_zombies() {
2768   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2769     if (fst.current()->can_be_deoptimized()) {
2770       // it is a Java nmethod
2771       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2772       nm->make_not_entrant();
2773     }
2774   }
2775 }
2776 #endif // PRODUCT
2777 
2778 
2779 void JavaThread::deoptimized_wrt_marked_nmethods() {
2780   if (!has_last_Java_frame()) return;
2781   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2782   StackFrameStream fst(this, UseBiasedLocking);
2783   for (; !fst.is_done(); fst.next()) {
2784     if (fst.current()->should_be_deoptimized()) {
2785       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2786     }
2787   }
2788 }
2789 
2790 
2791 // If the caller is a NamedThread, then remember, in the current scope,
2792 // the given JavaThread in its _processed_thread field.
2793 class RememberProcessedThread: public StackObj {
2794   NamedThread* _cur_thr;
2795  public:
2796   RememberProcessedThread(JavaThread* jthr) {
2797     Thread* thread = Thread::current();
2798     if (thread->is_Named_thread()) {
2799       _cur_thr = (NamedThread *)thread;
2800       _cur_thr->set_processed_thread(jthr);
2801     } else {
2802       _cur_thr = NULL;
2803     }
2804   }
2805 
2806   ~RememberProcessedThread() {
2807     if (_cur_thr) {
2808       _cur_thr->set_processed_thread(NULL);
2809     }
2810   }
2811 };
2812 
2813 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2814   // Verify that the deferred card marks have been flushed.
2815   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2816 
2817   // Traverse the GCHandles
2818   Thread::oops_do(f, cf);
2819 
2820   JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2821 
2822   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2823          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2824 
2825   if (has_last_Java_frame()) {
2826     // Record JavaThread to GC thread
2827     RememberProcessedThread rpt(this);
2828 
2829     // Traverse the privileged stack
2830     if (_privileged_stack_top != NULL) {
2831       _privileged_stack_top->oops_do(f);
2832     }
2833 
2834     // traverse the registered growable array
2835     if (_array_for_gc != NULL) {
2836       for (int index = 0; index < _array_for_gc->length(); index++) {
2837         f->do_oop(_array_for_gc->adr_at(index));
2838       }
2839     }
2840 
2841     // Traverse the monitor chunks
2842     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2843       chunk->oops_do(f);
2844     }
2845 
2846     // Traverse the execution stack
2847     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2848       fst.current()->oops_do(f, cf, fst.register_map());
2849     }
2850   }
2851 
2852   // callee_target is never live across a gc point so NULL it here should
2853   // it still contain a methdOop.
2854 
2855   set_callee_target(NULL);
2856 
2857   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2858   // If we have deferred set_locals there might be oops waiting to be
2859   // written
2860   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2861   if (list != NULL) {
2862     for (int i = 0; i < list->length(); i++) {
2863       list->at(i)->oops_do(f);
2864     }
2865   }
2866 
2867   // Traverse instance variables at the end since the GC may be moving things
2868   // around using this function
2869   f->do_oop((oop*) &_threadObj);
2870   f->do_oop((oop*) &_vm_result);
2871   f->do_oop((oop*) &_exception_oop);
2872   f->do_oop((oop*) &_pending_async_exception);
2873 
2874   if (jvmti_thread_state() != NULL) {
2875     jvmti_thread_state()->oops_do(f);
2876   }
2877 }
2878 
2879 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2880   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2881          (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2882 
2883   if (has_last_Java_frame()) {
2884     // Traverse the execution stack
2885     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2886       fst.current()->nmethods_do(cf);
2887     }
2888   }
2889 }
2890 
2891 void JavaThread::metadata_do(void f(Metadata*)) {
2892   if (has_last_Java_frame()) {
2893     // Traverse the execution stack to call f() on the methods in the stack
2894     for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2895       fst.current()->metadata_do(f);
2896     }
2897   } else if (is_Compiler_thread()) {
2898     // need to walk ciMetadata in current compile tasks to keep alive.
2899     CompilerThread* ct = (CompilerThread*)this;
2900     if (ct->env() != NULL) {
2901       ct->env()->metadata_do(f);
2902     }
2903     CompileTask* task = ct->task();
2904     if (task != NULL) {
2905       task->metadata_do(f);
2906     }
2907   }
2908 }
2909 
2910 // Printing
2911 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2912   switch (_thread_state) {
2913   case _thread_uninitialized:     return "_thread_uninitialized";
2914   case _thread_new:               return "_thread_new";
2915   case _thread_new_trans:         return "_thread_new_trans";
2916   case _thread_in_native:         return "_thread_in_native";
2917   case _thread_in_native_trans:   return "_thread_in_native_trans";
2918   case _thread_in_vm:             return "_thread_in_vm";
2919   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
2920   case _thread_in_Java:           return "_thread_in_Java";
2921   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
2922   case _thread_blocked:           return "_thread_blocked";
2923   case _thread_blocked_trans:     return "_thread_blocked_trans";
2924   default:                        return "unknown thread state";
2925   }
2926 }
2927 
2928 #ifndef PRODUCT
2929 void JavaThread::print_thread_state_on(outputStream *st) const {
2930   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
2931 };
2932 void JavaThread::print_thread_state() const {
2933   print_thread_state_on(tty);
2934 }
2935 #endif // PRODUCT
2936 
2937 // Called by Threads::print() for VM_PrintThreads operation
2938 void JavaThread::print_on(outputStream *st) const {
2939   st->print_raw("\"");
2940   st->print_raw(get_thread_name());
2941   st->print_raw("\" ");
2942   oop thread_oop = threadObj();
2943   if (thread_oop != NULL) {
2944     st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2945     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
2946     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2947   }
2948   Thread::print_on(st);
2949   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2950   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2951   if (thread_oop != NULL) {
2952     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2953   }
2954 #ifndef PRODUCT
2955   print_thread_state_on(st);
2956   _safepoint_state->print_on(st);
2957 #endif // PRODUCT
2958   if (is_Compiler_thread()) {
2959     CompileTask *task = ((CompilerThread*)this)->task();
2960     if (task != NULL) {
2961       st->print("   Compiling: ");
2962       task->print(st, NULL, true, false);
2963     } else {
2964       st->print("   No compile task");
2965     }
2966     st->cr();
2967   }
2968 }
2969 
2970 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2971   st->print("%s", get_thread_name_string(buf, buflen));
2972 }
2973 
2974 // Called by fatal error handler. The difference between this and
2975 // JavaThread::print() is that we can't grab lock or allocate memory.
2976 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2977   st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2978   oop thread_obj = threadObj();
2979   if (thread_obj != NULL) {
2980     if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2981   }
2982   st->print(" [");
2983   st->print("%s", _get_thread_state_name(_thread_state));
2984   if (osthread()) {
2985     st->print(", id=%d", osthread()->thread_id());
2986   }
2987   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2988             p2i(stack_end()), p2i(stack_base()));
2989   st->print("]");
2990 
2991   if (_threads_hazard_ptr != NULL) {
2992     st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
2993   }
2994   if (_nested_threads_hazard_ptr != NULL) {
2995     print_nested_threads_hazard_ptrs_on(st);
2996   }
2997   return;
2998 }
2999 
3000 // Verification
3001 
3002 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3003 
3004 void JavaThread::verify() {
3005   // Verify oops in the thread.
3006   oops_do(&VerifyOopClosure::verify_oop, NULL);
3007 
3008   // Verify the stack frames.
3009   frames_do(frame_verify);
3010 }
3011 
3012 // CR 6300358 (sub-CR 2137150)
3013 // Most callers of this method assume that it can't return NULL but a
3014 // thread may not have a name whilst it is in the process of attaching to
3015 // the VM - see CR 6412693, and there are places where a JavaThread can be
3016 // seen prior to having it's threadObj set (eg JNI attaching threads and
3017 // if vm exit occurs during initialization). These cases can all be accounted
3018 // for such that this method never returns NULL.
3019 const char* JavaThread::get_thread_name() const {
3020 #ifdef ASSERT
3021   // early safepoints can hit while current thread does not yet have TLS
3022   if (!SafepointSynchronize::is_at_safepoint()) {
3023     Thread *cur = Thread::current();
3024     if (!(cur->is_Java_thread() && cur == this)) {
3025       // Current JavaThreads are allowed to get their own name without
3026       // the Threads_lock.
3027       assert_locked_or_safepoint(Threads_lock);
3028     }
3029   }
3030 #endif // ASSERT
3031   return get_thread_name_string();
3032 }
3033 
3034 // Returns a non-NULL representation of this thread's name, or a suitable
3035 // descriptive string if there is no set name
3036 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3037   const char* name_str;
3038   oop thread_obj = threadObj();
3039   if (thread_obj != NULL) {
3040     oop name = java_lang_Thread::name(thread_obj);
3041     if (name != NULL) {
3042       if (buf == NULL) {
3043         name_str = java_lang_String::as_utf8_string(name);
3044       } else {
3045         name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3046       }
3047     } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3048       name_str = "<no-name - thread is attaching>";
3049     } else {
3050       name_str = Thread::name();
3051     }
3052   } else {
3053     name_str = Thread::name();
3054   }
3055   assert(name_str != NULL, "unexpected NULL thread name");
3056   return name_str;
3057 }
3058 
3059 
3060 const char* JavaThread::get_threadgroup_name() const {
3061   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3062   oop thread_obj = threadObj();
3063   if (thread_obj != NULL) {
3064     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3065     if (thread_group != NULL) {
3066       // ThreadGroup.name can be null
3067       return java_lang_ThreadGroup::name(thread_group);
3068     }
3069   }
3070   return NULL;
3071 }
3072 
3073 const char* JavaThread::get_parent_name() const {
3074   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3075   oop thread_obj = threadObj();
3076   if (thread_obj != NULL) {
3077     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3078     if (thread_group != NULL) {
3079       oop parent = java_lang_ThreadGroup::parent(thread_group);
3080       if (parent != NULL) {
3081         // ThreadGroup.name can be null
3082         return java_lang_ThreadGroup::name(parent);
3083       }
3084     }
3085   }
3086   return NULL;
3087 }
3088 
3089 ThreadPriority JavaThread::java_priority() const {
3090   oop thr_oop = threadObj();
3091   if (thr_oop == NULL) return NormPriority; // Bootstrapping
3092   ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3093   assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3094   return priority;
3095 }
3096 
3097 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3098 
3099   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3100   // Link Java Thread object <-> C++ Thread
3101 
3102   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3103   // and put it into a new Handle.  The Handle "thread_oop" can then
3104   // be used to pass the C++ thread object to other methods.
3105 
3106   // Set the Java level thread object (jthread) field of the
3107   // new thread (a JavaThread *) to C++ thread object using the
3108   // "thread_oop" handle.
3109 
3110   // Set the thread field (a JavaThread *) of the
3111   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3112 
3113   Handle thread_oop(Thread::current(),
3114                     JNIHandles::resolve_non_null(jni_thread));
3115   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3116          "must be initialized");
3117   set_threadObj(thread_oop());
3118   java_lang_Thread::set_thread(thread_oop(), this);
3119 
3120   if (prio == NoPriority) {
3121     prio = java_lang_Thread::priority(thread_oop());
3122     assert(prio != NoPriority, "A valid priority should be present");
3123   }
3124 
3125   // Push the Java priority down to the native thread; needs Threads_lock
3126   Thread::set_priority(this, prio);
3127 
3128   // Add the new thread to the Threads list and set it in motion.
3129   // We must have threads lock in order to call Threads::add.
3130   // It is crucial that we do not block before the thread is
3131   // added to the Threads list for if a GC happens, then the java_thread oop
3132   // will not be visited by GC.
3133   Threads::add(this);
3134 }
3135 
3136 oop JavaThread::current_park_blocker() {
3137   // Support for JSR-166 locks
3138   oop thread_oop = threadObj();
3139   if (thread_oop != NULL &&
3140       JDK_Version::current().supports_thread_park_blocker()) {
3141     return java_lang_Thread::park_blocker(thread_oop);
3142   }
3143   return NULL;
3144 }
3145 
3146 
3147 void JavaThread::print_stack_on(outputStream* st) {
3148   if (!has_last_Java_frame()) return;
3149   ResourceMark rm;
3150   HandleMark   hm;
3151 
3152   RegisterMap reg_map(this);
3153   vframe* start_vf = last_java_vframe(&reg_map);
3154   int count = 0;
3155   for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3156     if (f->is_java_frame()) {
3157       javaVFrame* jvf = javaVFrame::cast(f);
3158       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3159 
3160       // Print out lock information
3161       if (JavaMonitorsInStackTrace) {
3162         jvf->print_lock_info_on(st, count);
3163       }
3164     } else {
3165       // Ignore non-Java frames
3166     }
3167 
3168     // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3169     count++;
3170     if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3171   }
3172 }
3173 
3174 
3175 // JVMTI PopFrame support
3176 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3177   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3178   if (in_bytes(size_in_bytes) != 0) {
3179     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3180     _popframe_preserved_args_size = in_bytes(size_in_bytes);
3181     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3182   }
3183 }
3184 
3185 void* JavaThread::popframe_preserved_args() {
3186   return _popframe_preserved_args;
3187 }
3188 
3189 ByteSize JavaThread::popframe_preserved_args_size() {
3190   return in_ByteSize(_popframe_preserved_args_size);
3191 }
3192 
3193 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3194   int sz = in_bytes(popframe_preserved_args_size());
3195   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3196   return in_WordSize(sz / wordSize);
3197 }
3198 
3199 void JavaThread::popframe_free_preserved_args() {
3200   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3201   FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3202   _popframe_preserved_args = NULL;
3203   _popframe_preserved_args_size = 0;
3204 }
3205 
3206 #ifndef PRODUCT
3207 
3208 void JavaThread::trace_frames() {
3209   tty->print_cr("[Describe stack]");
3210   int frame_no = 1;
3211   for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3212     tty->print("  %d. ", frame_no++);
3213     fst.current()->print_value_on(tty, this);
3214     tty->cr();
3215   }
3216 }
3217 
3218 class PrintAndVerifyOopClosure: public OopClosure {
3219  protected:
3220   template <class T> inline void do_oop_work(T* p) {
3221     oop obj = RawAccess<>::oop_load(p);
3222     if (obj == NULL) return;
3223     tty->print(INTPTR_FORMAT ": ", p2i(p));
3224     if (oopDesc::is_oop_or_null(obj)) {
3225       if (obj->is_objArray()) {
3226         tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3227       } else {
3228         obj->print();
3229       }
3230     } else {
3231       tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3232     }
3233     tty->cr();
3234   }
3235  public:
3236   virtual void do_oop(oop* p) { do_oop_work(p); }
3237   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
3238 };
3239 
3240 
3241 static void oops_print(frame* f, const RegisterMap *map) {
3242   PrintAndVerifyOopClosure print;
3243   f->print_value();
3244   f->oops_do(&print, NULL, (RegisterMap*)map);
3245 }
3246 
3247 // Print our all the locations that contain oops and whether they are
3248 // valid or not.  This useful when trying to find the oldest frame
3249 // where an oop has gone bad since the frame walk is from youngest to
3250 // oldest.
3251 void JavaThread::trace_oops() {
3252   tty->print_cr("[Trace oops]");
3253   frames_do(oops_print);
3254 }
3255 
3256 
3257 #ifdef ASSERT
3258 // Print or validate the layout of stack frames
3259 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3260   ResourceMark rm;
3261   PRESERVE_EXCEPTION_MARK;
3262   FrameValues values;
3263   int frame_no = 0;
3264   for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3265     fst.current()->describe(values, ++frame_no);
3266     if (depth == frame_no) break;
3267   }
3268   if (validate_only) {
3269     values.validate();
3270   } else {
3271     tty->print_cr("[Describe stack layout]");
3272     values.print(this);
3273   }
3274 }
3275 #endif
3276 
3277 void JavaThread::trace_stack_from(vframe* start_vf) {
3278   ResourceMark rm;
3279   int vframe_no = 1;
3280   for (vframe* f = start_vf; f; f = f->sender()) {
3281     if (f->is_java_frame()) {
3282       javaVFrame::cast(f)->print_activation(vframe_no++);
3283     } else {
3284       f->print();
3285     }
3286     if (vframe_no > StackPrintLimit) {
3287       tty->print_cr("...<more frames>...");
3288       return;
3289     }
3290   }
3291 }
3292 
3293 
3294 void JavaThread::trace_stack() {
3295   if (!has_last_Java_frame()) return;
3296   ResourceMark rm;
3297   HandleMark   hm;
3298   RegisterMap reg_map(this);
3299   trace_stack_from(last_java_vframe(&reg_map));
3300 }
3301 
3302 
3303 #endif // PRODUCT
3304 
3305 
3306 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3307   assert(reg_map != NULL, "a map must be given");
3308   frame f = last_frame();
3309   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3310     if (vf->is_java_frame()) return javaVFrame::cast(vf);
3311   }
3312   return NULL;
3313 }
3314 
3315 
3316 Klass* JavaThread::security_get_caller_class(int depth) {
3317   vframeStream vfst(this);
3318   vfst.security_get_caller_frame(depth);
3319   if (!vfst.at_end()) {
3320     return vfst.method()->method_holder();
3321   }
3322   return NULL;
3323 }
3324 
3325 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3326   assert(thread->is_Compiler_thread(), "must be compiler thread");
3327   CompileBroker::compiler_thread_loop();
3328 }
3329 
3330 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3331   NMethodSweeper::sweeper_loop();
3332 }
3333 
3334 // Create a CompilerThread
3335 CompilerThread::CompilerThread(CompileQueue* queue,
3336                                CompilerCounters* counters)
3337                                : JavaThread(&compiler_thread_entry) {
3338   _env   = NULL;
3339   _log   = NULL;
3340   _task  = NULL;
3341   _queue = queue;
3342   _counters = counters;
3343   _buffer_blob = NULL;
3344   _compiler = NULL;
3345 
3346   // Compiler uses resource area for compilation, let's bias it to mtCompiler
3347   resource_area()->bias_to(mtCompiler);
3348 
3349 #ifndef PRODUCT
3350   _ideal_graph_printer = NULL;
3351 #endif
3352 }
3353 
3354 bool CompilerThread::can_call_java() const {
3355   return _compiler != NULL && _compiler->is_jvmci();
3356 }
3357 
3358 // Create sweeper thread
3359 CodeCacheSweeperThread::CodeCacheSweeperThread()
3360 : JavaThread(&sweeper_thread_entry) {
3361   _scanned_compiled_method = NULL;
3362 }
3363 
3364 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3365   JavaThread::oops_do(f, cf);
3366   if (_scanned_compiled_method != NULL && cf != NULL) {
3367     // Safepoints can occur when the sweeper is scanning an nmethod so
3368     // process it here to make sure it isn't unloaded in the middle of
3369     // a scan.
3370     cf->do_code_blob(_scanned_compiled_method);
3371   }
3372 }
3373 
3374 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3375   JavaThread::nmethods_do(cf);
3376   if (_scanned_compiled_method != NULL && cf != NULL) {
3377     // Safepoints can occur when the sweeper is scanning an nmethod so
3378     // process it here to make sure it isn't unloaded in the middle of
3379     // a scan.
3380     cf->do_code_blob(_scanned_compiled_method);
3381   }
3382 }
3383 
3384 
3385 // ======= Threads ========
3386 
3387 // The Threads class links together all active threads, and provides
3388 // operations over all threads. It is protected by the Threads_lock,
3389 // which is also used in other global contexts like safepointing.
3390 // ThreadsListHandles are used to safely perform operations on one
3391 // or more threads without the risk of the thread exiting during the
3392 // operation.
3393 //
3394 // Note: The Threads_lock is currently more widely used than we
3395 // would like. We are actively migrating Threads_lock uses to other
3396 // mechanisms in order to reduce Threads_lock contention.
3397 
3398 JavaThread* Threads::_thread_list = NULL;
3399 int         Threads::_number_of_threads = 0;
3400 int         Threads::_number_of_non_daemon_threads = 0;
3401 int         Threads::_return_code = 0;
3402 int         Threads::_thread_claim_parity = 0;
3403 size_t      JavaThread::_stack_size_at_create = 0;
3404 
3405 #ifdef ASSERT
3406 bool        Threads::_vm_complete = false;
3407 #endif
3408 
3409 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3410   Prefetch::read((void*)addr, prefetch_interval);
3411   return *addr;
3412 }
3413 
3414 // Possibly the ugliest for loop the world has seen. C++ does not allow
3415 // multiple types in the declaration section of the for loop. In this case
3416 // we are only dealing with pointers and hence can cast them. It looks ugly
3417 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3418 #define DO_JAVA_THREADS(LIST, X)                                                                                          \
3419     for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes,                           \
3420              *MACRO_list = (JavaThread*)(LIST),                                                                           \
3421              **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(),  \
3422              **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(),                                     \
3423              *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval);                 \
3424          MACRO_current_p != MACRO_end;                                                                                    \
3425          MACRO_current_p++,                                                                                               \
3426              X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3427 
3428 // All JavaThreads
3429 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3430 
3431 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3432 void Threads::threads_do(ThreadClosure* tc) {
3433   assert_locked_or_safepoint(Threads_lock);
3434   // ALL_JAVA_THREADS iterates through all JavaThreads
3435   ALL_JAVA_THREADS(p) {
3436     tc->do_thread(p);
3437   }
3438   // Someday we could have a table or list of all non-JavaThreads.
3439   // For now, just manually iterate through them.
3440   tc->do_thread(VMThread::vm_thread());
3441   Universe::heap()->gc_threads_do(tc);
3442   WatcherThread *wt = WatcherThread::watcher_thread();
3443   // Strictly speaking, the following NULL check isn't sufficient to make sure
3444   // the data for WatcherThread is still valid upon being examined. However,
3445   // considering that WatchThread terminates when the VM is on the way to
3446   // exit at safepoint, the chance of the above is extremely small. The right
3447   // way to prevent termination of WatcherThread would be to acquire
3448   // Terminator_lock, but we can't do that without violating the lock rank
3449   // checking in some cases.
3450   if (wt != NULL) {
3451     tc->do_thread(wt);
3452   }
3453 
3454   // If CompilerThreads ever become non-JavaThreads, add them here
3455 }
3456 
3457 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3458   int cp = Threads::thread_claim_parity();
3459   ALL_JAVA_THREADS(p) {
3460     if (p->claim_oops_do(is_par, cp)) {
3461       tc->do_thread(p);
3462     }
3463   }
3464   VMThread* vmt = VMThread::vm_thread();
3465   if (vmt->claim_oops_do(is_par, cp)) {
3466     tc->do_thread(vmt);
3467   }
3468 }
3469 
3470 // The system initialization in the library has three phases.
3471 //
3472 // Phase 1: java.lang.System class initialization
3473 //     java.lang.System is a primordial class loaded and initialized
3474 //     by the VM early during startup.  java.lang.System.<clinit>
3475 //     only does registerNatives and keeps the rest of the class
3476 //     initialization work later until thread initialization completes.
3477 //
3478 //     System.initPhase1 initializes the system properties, the static
3479 //     fields in, out, and err. Set up java signal handlers, OS-specific
3480 //     system settings, and thread group of the main thread.
3481 static void call_initPhase1(TRAPS) {
3482   Klass* klass =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3483   JavaValue result(T_VOID);
3484   JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3485                                          vmSymbols::void_method_signature(), CHECK);
3486 }
3487 
3488 // Phase 2. Module system initialization
3489 //     This will initialize the module system.  Only java.base classes
3490 //     can be loaded until phase 2 completes.
3491 //
3492 //     Call System.initPhase2 after the compiler initialization and jsr292
3493 //     classes get initialized because module initialization runs a lot of java
3494 //     code, that for performance reasons, should be compiled.  Also, this will
3495 //     enable the startup code to use lambda and other language features in this
3496 //     phase and onward.
3497 //
3498 //     After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3499 static void call_initPhase2(TRAPS) {
3500   TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3501 
3502   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3503 
3504   JavaValue result(T_INT);
3505   JavaCallArguments args;
3506   args.push_int(DisplayVMOutputToStderr);
3507   args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3508   JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3509                                          vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3510   if (result.get_jint() != JNI_OK) {
3511     vm_exit_during_initialization(); // no message or exception
3512   }
3513 
3514   universe_post_module_init();
3515 }
3516 
3517 // Phase 3. final setup - set security manager, system class loader and TCCL
3518 //
3519 //     This will instantiate and set the security manager, set the system class
3520 //     loader as well as the thread context class loader.  The security manager
3521 //     and system class loader may be a custom class loaded from -Xbootclasspath/a,
3522 //     other modules or the application's classpath.
3523 static void call_initPhase3(TRAPS) {
3524   Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3525   JavaValue result(T_VOID);
3526   JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3527                                          vmSymbols::void_method_signature(), CHECK);
3528 }
3529 
3530 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3531   TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3532 
3533   if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3534     create_vm_init_libraries();
3535   }
3536 
3537   initialize_class(vmSymbols::java_lang_String(), CHECK);
3538 
3539   // Inject CompactStrings value after the static initializers for String ran.
3540   java_lang_String::set_compact_strings(CompactStrings);
3541 
3542   // Initialize java_lang.System (needed before creating the thread)
3543   initialize_class(vmSymbols::java_lang_System(), CHECK);
3544   // The VM creates & returns objects of this class. Make sure it's initialized.
3545   initialize_class(vmSymbols::java_lang_Class(), CHECK);
3546   initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3547   Handle thread_group = create_initial_thread_group(CHECK);
3548   Universe::set_main_thread_group(thread_group());
3549   initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3550   oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3551   main_thread->set_threadObj(thread_object);
3552   // Set thread status to running since main thread has
3553   // been started and running.
3554   java_lang_Thread::set_thread_status(thread_object,
3555                                       java_lang_Thread::RUNNABLE);
3556 
3557   // The VM creates objects of this class.
3558   initialize_class(vmSymbols::java_lang_Module(), CHECK);
3559 
3560   // The VM preresolves methods to these classes. Make sure that they get initialized
3561   initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3562   initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3563 
3564   // Phase 1 of the system initialization in the library, java.lang.System class initialization
3565   call_initPhase1(CHECK);
3566 
3567   // get the Java runtime name after java.lang.System is initialized
3568   JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3569   JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3570 
3571   // an instance of OutOfMemory exception has been allocated earlier
3572   initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3573   initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3574   initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3575   initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3576   initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3577   initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3578   initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3579   initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3580 }
3581 
3582 void Threads::initialize_jsr292_core_classes(TRAPS) {
3583   TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3584 
3585   initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3586   initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3587   initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3588   initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3589 }
3590 
3591 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3592   extern void JDK_Version_init();
3593 
3594   // Preinitialize version info.
3595   VM_Version::early_initialize();
3596 
3597   // Check version
3598   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3599 
3600   // Initialize library-based TLS
3601   ThreadLocalStorage::init();
3602 
3603   // Initialize the output stream module
3604   ostream_init();
3605 
3606   // Process java launcher properties.
3607   Arguments::process_sun_java_launcher_properties(args);
3608 
3609   // Initialize the os module
3610   os::init();
3611 
3612   // Record VM creation timing statistics
3613   TraceVmCreationTime create_vm_timer;
3614   create_vm_timer.start();
3615 
3616   // Initialize system properties.
3617   Arguments::init_system_properties();
3618 
3619   // So that JDK version can be used as a discriminator when parsing arguments
3620   JDK_Version_init();
3621 
3622   // Update/Initialize System properties after JDK version number is known
3623   Arguments::init_version_specific_system_properties();
3624 
3625   // Make sure to initialize log configuration *before* parsing arguments
3626   LogConfiguration::initialize(create_vm_timer.begin_time());
3627 
3628   // Parse arguments
3629   // Note: this internally calls os::init_container_support()
3630   jint parse_result = Arguments::parse(args);
3631   if (parse_result != JNI_OK) return parse_result;
3632 
3633   os::init_before_ergo();
3634 
3635   jint ergo_result = Arguments::apply_ergo();
3636   if (ergo_result != JNI_OK) return ergo_result;
3637 
3638   // Final check of all ranges after ergonomics which may change values.
3639   if (!CommandLineFlagRangeList::check_ranges()) {
3640     return JNI_EINVAL;
3641   }
3642 
3643   // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3644   bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3645   if (!constraint_result) {
3646     return JNI_EINVAL;
3647   }
3648 
3649   CommandLineFlagWriteableList::mark_startup();
3650 
3651   if (PauseAtStartup) {
3652     os::pause();
3653   }
3654 
3655   HOTSPOT_VM_INIT_BEGIN();
3656 
3657   // Timing (must come after argument parsing)
3658   TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3659 
3660 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
3661   // Initialize assert poison page mechanism.
3662   if (ShowRegistersOnAssert) {
3663     initialize_assert_poison();
3664   }
3665 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
3666 
3667   // Initialize the os module after parsing the args
3668   jint os_init_2_result = os::init_2();
3669   if (os_init_2_result != JNI_OK) return os_init_2_result;
3670 
3671   SafepointMechanism::initialize();
3672 
3673   jint adjust_after_os_result = Arguments::adjust_after_os();
3674   if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3675 
3676   // Initialize output stream logging
3677   ostream_init_log();
3678 
3679   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3680   // Must be before create_vm_init_agents()
3681   if (Arguments::init_libraries_at_startup()) {
3682     convert_vm_init_libraries_to_agents();
3683   }
3684 
3685   // Launch -agentlib/-agentpath and converted -Xrun agents
3686   if (Arguments::init_agents_at_startup()) {
3687     create_vm_init_agents();
3688   }
3689 
3690   // Initialize Threads state
3691   _thread_list = NULL;
3692   _number_of_threads = 0;
3693   _number_of_non_daemon_threads = 0;
3694 
3695   // Initialize global data structures and create system classes in heap
3696   vm_init_globals();
3697 
3698 #if INCLUDE_JVMCI
3699   if (JVMCICounterSize > 0) {
3700     JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3701     memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3702   } else {
3703     JavaThread::_jvmci_old_thread_counters = NULL;
3704   }
3705 #endif // INCLUDE_JVMCI
3706 
3707   // Attach the main thread to this os thread
3708   JavaThread* main_thread = new JavaThread();
3709   main_thread->set_thread_state(_thread_in_vm);
3710   main_thread->initialize_thread_current();
3711   // must do this before set_active_handles
3712   main_thread->record_stack_base_and_size();
3713   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3714 
3715   if (!main_thread->set_as_starting_thread()) {
3716     vm_shutdown_during_initialization(
3717                                       "Failed necessary internal allocation. Out of swap space");
3718     main_thread->smr_delete();
3719     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3720     return JNI_ENOMEM;
3721   }
3722 
3723   // Enable guard page *after* os::create_main_thread(), otherwise it would
3724   // crash Linux VM, see notes in os_linux.cpp.
3725   main_thread->create_stack_guard_pages();
3726 
3727   // Initialize Java-Level synchronization subsystem
3728   ObjectMonitor::Initialize();
3729 
3730   // Initialize global modules
3731   jint status = init_globals();
3732   if (status != JNI_OK) {
3733     main_thread->smr_delete();
3734     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3735     return status;
3736   }
3737 
3738   if (TRACE_INITIALIZE() != JNI_OK) {
3739     vm_exit_during_initialization("Failed to initialize tracing backend");
3740   }
3741 
3742   // Should be done after the heap is fully created
3743   main_thread->cache_global_variables();
3744 
3745   HandleMark hm;
3746 
3747   { MutexLocker mu(Threads_lock);
3748     Threads::add(main_thread);
3749   }
3750 
3751   // Any JVMTI raw monitors entered in onload will transition into
3752   // real raw monitor. VM is setup enough here for raw monitor enter.
3753   JvmtiExport::transition_pending_onload_raw_monitors();
3754 
3755   // Create the VMThread
3756   { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3757 
3758   VMThread::create();
3759     Thread* vmthread = VMThread::vm_thread();
3760 
3761     if (!os::create_thread(vmthread, os::vm_thread)) {
3762       vm_exit_during_initialization("Cannot create VM thread. "
3763                                     "Out of system resources.");
3764     }
3765 
3766     // Wait for the VM thread to become ready, and VMThread::run to initialize
3767     // Monitors can have spurious returns, must always check another state flag
3768     {
3769       MutexLocker ml(Notify_lock);
3770       os::start_thread(vmthread);
3771       while (vmthread->active_handles() == NULL) {
3772         Notify_lock->wait();
3773       }
3774     }
3775   }
3776 
3777   assert(Universe::is_fully_initialized(), "not initialized");
3778   if (VerifyDuringStartup) {
3779     // Make sure we're starting with a clean slate.
3780     VM_Verify verify_op;
3781     VMThread::execute(&verify_op);
3782   }
3783 
3784   Thread* THREAD = Thread::current();
3785 
3786   // Always call even when there are not JVMTI environments yet, since environments
3787   // may be attached late and JVMTI must track phases of VM execution
3788   JvmtiExport::enter_early_start_phase();
3789 
3790   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3791   JvmtiExport::post_early_vm_start();
3792 
3793   initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3794 
3795   // We need this for ClassDataSharing - the initial vm.info property is set
3796   // with the default value of CDS "sharing" which may be reset through
3797   // command line options.
3798   reset_vm_info_property(CHECK_JNI_ERR);
3799 
3800   quicken_jni_functions();
3801 
3802   // No more stub generation allowed after that point.
3803   StubCodeDesc::freeze();
3804 
3805   // Set flag that basic initialization has completed. Used by exceptions and various
3806   // debug stuff, that does not work until all basic classes have been initialized.
3807   set_init_completed();
3808 
3809   LogConfiguration::post_initialize();
3810   Metaspace::post_initialize();
3811 
3812   HOTSPOT_VM_INIT_END();
3813 
3814   // record VM initialization completion time
3815 #if INCLUDE_MANAGEMENT
3816   Management::record_vm_init_completed();
3817 #endif // INCLUDE_MANAGEMENT
3818 
3819   // Signal Dispatcher needs to be started before VMInit event is posted
3820   os::signal_init(CHECK_JNI_ERR);
3821 
3822   // Start Attach Listener if +StartAttachListener or it can't be started lazily
3823   if (!DisableAttachMechanism) {
3824     AttachListener::vm_start();
3825     if (StartAttachListener || AttachListener::init_at_startup()) {
3826       AttachListener::init();
3827     }
3828   }
3829 
3830   // Launch -Xrun agents
3831   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3832   // back-end can launch with -Xdebug -Xrunjdwp.
3833   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3834     create_vm_init_libraries();
3835   }
3836 
3837   if (CleanChunkPoolAsync) {
3838     Chunk::start_chunk_pool_cleaner_task();
3839   }
3840 
3841   // initialize compiler(s)
3842 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3843 #if INCLUDE_JVMCI
3844   bool force_JVMCI_intialization = false;
3845   if (EnableJVMCI) {
3846     // Initialize JVMCI eagerly when it is explicitly requested.
3847     // Or when JVMCIPrintProperties is enabled.
3848     // The JVMCI Java initialization code will read this flag and
3849     // do the printing if it's set.
3850     force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties;
3851 
3852     if (!force_JVMCI_intialization) {
3853       // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3854       // compilations via JVMCI will not actually block until JVMCI is initialized.
3855       force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3856     }
3857   }
3858 #endif
3859   CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
3860   // Postpone completion of compiler initialization to after JVMCI
3861   // is initialized to avoid timeouts of blocking compilations.
3862   if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
3863     CompileBroker::compilation_init_phase2();
3864   }
3865 #endif
3866 
3867   // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3868   // It is done after compilers are initialized, because otherwise compilations of
3869   // signature polymorphic MH intrinsics can be missed
3870   // (see SystemDictionary::find_method_handle_intrinsic).
3871   initialize_jsr292_core_classes(CHECK_JNI_ERR);
3872 
3873   // This will initialize the module system.  Only java.base classes can be
3874   // loaded until phase 2 completes
3875   call_initPhase2(CHECK_JNI_ERR);
3876 
3877   // Always call even when there are not JVMTI environments yet, since environments
3878   // may be attached late and JVMTI must track phases of VM execution
3879   JvmtiExport::enter_start_phase();
3880 
3881   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3882   JvmtiExport::post_vm_start();
3883 
3884   // Final system initialization including security manager and system class loader
3885   call_initPhase3(CHECK_JNI_ERR);
3886 
3887   // cache the system and platform class loaders
3888   SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3889 
3890 #if INCLUDE_JVMCI
3891   if (force_JVMCI_intialization) {
3892     JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3893     CompileBroker::compilation_init_phase2();
3894   }
3895 #endif
3896 
3897   // Always call even when there are not JVMTI environments yet, since environments
3898   // may be attached late and JVMTI must track phases of VM execution
3899   JvmtiExport::enter_live_phase();
3900 
3901   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3902   JvmtiExport::post_vm_initialized();
3903 
3904   if (TRACE_START() != JNI_OK) {
3905     vm_exit_during_initialization("Failed to start tracing backend.");
3906   }
3907 
3908 #if INCLUDE_MANAGEMENT
3909   Management::initialize(THREAD);
3910 
3911   if (HAS_PENDING_EXCEPTION) {
3912     // management agent fails to start possibly due to
3913     // configuration problem and is responsible for printing
3914     // stack trace if appropriate. Simply exit VM.
3915     vm_exit(1);
3916   }
3917 #endif // INCLUDE_MANAGEMENT
3918 
3919   if (MemProfiling)                   MemProfiler::engage();
3920   StatSampler::engage();
3921   if (CheckJNICalls)                  JniPeriodicChecker::engage();
3922 
3923   BiasedLocking::init();
3924 
3925 #if INCLUDE_RTM_OPT
3926   RTMLockingCounters::init();
3927 #endif
3928 
3929   if (JDK_Version::current().post_vm_init_hook_enabled()) {
3930     call_postVMInitHook(THREAD);
3931     // The Java side of PostVMInitHook.run must deal with all
3932     // exceptions and provide means of diagnosis.
3933     if (HAS_PENDING_EXCEPTION) {
3934       CLEAR_PENDING_EXCEPTION;
3935     }
3936   }
3937 
3938   {
3939     MutexLocker ml(PeriodicTask_lock);
3940     // Make sure the WatcherThread can be started by WatcherThread::start()
3941     // or by dynamic enrollment.
3942     WatcherThread::make_startable();
3943     // Start up the WatcherThread if there are any periodic tasks
3944     // NOTE:  All PeriodicTasks should be registered by now. If they
3945     //   aren't, late joiners might appear to start slowly (we might
3946     //   take a while to process their first tick).
3947     if (PeriodicTask::num_tasks() > 0) {
3948       WatcherThread::start();
3949     }
3950   }
3951 
3952   create_vm_timer.end();
3953 #ifdef ASSERT
3954   _vm_complete = true;
3955 #endif
3956 
3957   if (DumpSharedSpaces) {
3958     MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3959     ShouldNotReachHere();
3960   }
3961 
3962   return JNI_OK;
3963 }
3964 
3965 // type for the Agent_OnLoad and JVM_OnLoad entry points
3966 extern "C" {
3967   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3968 }
3969 // Find a command line agent library and return its entry point for
3970 //         -agentlib:  -agentpath:   -Xrun
3971 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3972 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3973                                     const char *on_load_symbols[],
3974                                     size_t num_symbol_entries) {
3975   OnLoadEntry_t on_load_entry = NULL;
3976   void *library = NULL;
3977 
3978   if (!agent->valid()) {
3979     char buffer[JVM_MAXPATHLEN];
3980     char ebuf[1024] = "";
3981     const char *name = agent->name();
3982     const char *msg = "Could not find agent library ";
3983 
3984     // First check to see if agent is statically linked into executable
3985     if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3986       library = agent->os_lib();
3987     } else if (agent->is_absolute_path()) {
3988       library = os::dll_load(name, ebuf, sizeof ebuf);
3989       if (library == NULL) {
3990         const char *sub_msg = " in absolute path, with error: ";
3991         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3992         char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3993         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3994         // If we can't find the agent, exit.
3995         vm_exit_during_initialization(buf, NULL);
3996         FREE_C_HEAP_ARRAY(char, buf);
3997       }
3998     } else {
3999       // Try to load the agent from the standard dll directory
4000       if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4001                              name)) {
4002         library = os::dll_load(buffer, ebuf, sizeof ebuf);
4003       }
4004       if (library == NULL) { // Try the library path directory.
4005         if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4006           library = os::dll_load(buffer, ebuf, sizeof ebuf);
4007         }
4008         if (library == NULL) {
4009           const char *sub_msg = " on the library path, with error: ";
4010           const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4011 
4012           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4013                        strlen(ebuf) + strlen(sub_msg2) + 1;
4014           char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4015           if (!agent->is_instrument_lib()) {
4016             jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4017           } else {
4018             jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4019           }
4020           // If we can't find the agent, exit.
4021           vm_exit_during_initialization(buf, NULL);
4022           FREE_C_HEAP_ARRAY(char, buf);
4023         }
4024       }
4025     }
4026     agent->set_os_lib(library);
4027     agent->set_valid();
4028   }
4029 
4030   // Find the OnLoad function.
4031   on_load_entry =
4032     CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4033                                                           false,
4034                                                           on_load_symbols,
4035                                                           num_symbol_entries));
4036   return on_load_entry;
4037 }
4038 
4039 // Find the JVM_OnLoad entry point
4040 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4041   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4042   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4043 }
4044 
4045 // Find the Agent_OnLoad entry point
4046 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4047   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4048   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4049 }
4050 
4051 // For backwards compatibility with -Xrun
4052 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4053 // treated like -agentpath:
4054 // Must be called before agent libraries are created
4055 void Threads::convert_vm_init_libraries_to_agents() {
4056   AgentLibrary* agent;
4057   AgentLibrary* next;
4058 
4059   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4060     next = agent->next();  // cache the next agent now as this agent may get moved off this list
4061     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4062 
4063     // If there is an JVM_OnLoad function it will get called later,
4064     // otherwise see if there is an Agent_OnLoad
4065     if (on_load_entry == NULL) {
4066       on_load_entry = lookup_agent_on_load(agent);
4067       if (on_load_entry != NULL) {
4068         // switch it to the agent list -- so that Agent_OnLoad will be called,
4069         // JVM_OnLoad won't be attempted and Agent_OnUnload will
4070         Arguments::convert_library_to_agent(agent);
4071       } else {
4072         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4073       }
4074     }
4075   }
4076 }
4077 
4078 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
4079 // Invokes Agent_OnLoad
4080 // Called very early -- before JavaThreads exist
4081 void Threads::create_vm_init_agents() {
4082   extern struct JavaVM_ main_vm;
4083   AgentLibrary* agent;
4084 
4085   JvmtiExport::enter_onload_phase();
4086 
4087   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4088     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
4089 
4090     if (on_load_entry != NULL) {
4091       // Invoke the Agent_OnLoad function
4092       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4093       if (err != JNI_OK) {
4094         vm_exit_during_initialization("agent library failed to init", agent->name());
4095       }
4096     } else {
4097       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4098     }
4099   }
4100   JvmtiExport::enter_primordial_phase();
4101 }
4102 
4103 extern "C" {
4104   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4105 }
4106 
4107 void Threads::shutdown_vm_agents() {
4108   // Send any Agent_OnUnload notifications
4109   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4110   size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4111   extern struct JavaVM_ main_vm;
4112   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4113 
4114     // Find the Agent_OnUnload function.
4115     Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4116                                                    os::find_agent_function(agent,
4117                                                    false,
4118                                                    on_unload_symbols,
4119                                                    num_symbol_entries));
4120 
4121     // Invoke the Agent_OnUnload function
4122     if (unload_entry != NULL) {
4123       JavaThread* thread = JavaThread::current();
4124       ThreadToNativeFromVM ttn(thread);
4125       HandleMark hm(thread);
4126       (*unload_entry)(&main_vm);
4127     }
4128   }
4129 }
4130 
4131 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4132 // Invokes JVM_OnLoad
4133 void Threads::create_vm_init_libraries() {
4134   extern struct JavaVM_ main_vm;
4135   AgentLibrary* agent;
4136 
4137   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4138     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4139 
4140     if (on_load_entry != NULL) {
4141       // Invoke the JVM_OnLoad function
4142       JavaThread* thread = JavaThread::current();
4143       ThreadToNativeFromVM ttn(thread);
4144       HandleMark hm(thread);
4145       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4146       if (err != JNI_OK) {
4147         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4148       }
4149     } else {
4150       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4151     }
4152   }
4153 }
4154 
4155 
4156 // Last thread running calls java.lang.Shutdown.shutdown()
4157 void JavaThread::invoke_shutdown_hooks() {
4158   HandleMark hm(this);
4159 
4160   // We could get here with a pending exception, if so clear it now.
4161   if (this->has_pending_exception()) {
4162     this->clear_pending_exception();
4163   }
4164 
4165   EXCEPTION_MARK;
4166   Klass* shutdown_klass =
4167     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4168                                       THREAD);
4169   if (shutdown_klass != NULL) {
4170     // SystemDictionary::resolve_or_null will return null if there was
4171     // an exception.  If we cannot load the Shutdown class, just don't
4172     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
4173     // won't be run.  Note that if a shutdown hook was registered,
4174     // the Shutdown class would have already been loaded
4175     // (Runtime.addShutdownHook will load it).
4176     JavaValue result(T_VOID);
4177     JavaCalls::call_static(&result,
4178                            shutdown_klass,
4179                            vmSymbols::shutdown_method_name(),
4180                            vmSymbols::void_method_signature(),
4181                            THREAD);
4182   }
4183   CLEAR_PENDING_EXCEPTION;
4184 }
4185 
4186 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4187 // the program falls off the end of main(). Another VM exit path is through
4188 // vm_exit() when the program calls System.exit() to return a value or when
4189 // there is a serious error in VM. The two shutdown paths are not exactly
4190 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4191 // and VM_Exit op at VM level.
4192 //
4193 // Shutdown sequence:
4194 //   + Shutdown native memory tracking if it is on
4195 //   + Wait until we are the last non-daemon thread to execute
4196 //     <-- every thing is still working at this moment -->
4197 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4198 //        shutdown hooks
4199 //   + Call before_exit(), prepare for VM exit
4200 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4201 //        currently the only user of this mechanism is File.deleteOnExit())
4202 //      > stop StatSampler, watcher thread, CMS threads,
4203 //        post thread end and vm death events to JVMTI,
4204 //        stop signal thread
4205 //   + Call JavaThread::exit(), it will:
4206 //      > release JNI handle blocks, remove stack guard pages
4207 //      > remove this thread from Threads list
4208 //     <-- no more Java code from this thread after this point -->
4209 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4210 //     the compiler threads at safepoint
4211 //     <-- do not use anything that could get blocked by Safepoint -->
4212 //   + Disable tracing at JNI/JVM barriers
4213 //   + Set _vm_exited flag for threads that are still running native code
4214 //   + Delete this thread
4215 //   + Call exit_globals()
4216 //      > deletes tty
4217 //      > deletes PerfMemory resources
4218 //   + Return to caller
4219 
4220 bool Threads::destroy_vm() {
4221   JavaThread* thread = JavaThread::current();
4222 
4223 #ifdef ASSERT
4224   _vm_complete = false;
4225 #endif
4226   // Wait until we are the last non-daemon thread to execute
4227   { MutexLocker nu(Threads_lock);
4228     while (Threads::number_of_non_daemon_threads() > 1)
4229       // This wait should make safepoint checks, wait without a timeout,
4230       // and wait as a suspend-equivalent condition.
4231       Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4232                          Mutex::_as_suspend_equivalent_flag);
4233   }
4234 
4235   EventShutdown e;
4236   if (e.should_commit()) {
4237     e.set_reason("No remaining non-daemon Java threads");
4238     e.commit();
4239   }
4240 
4241   // Hang forever on exit if we are reporting an error.
4242   if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4243     os::infinite_sleep();
4244   }
4245   os::wait_for_keypress_at_exit();
4246 
4247   // run Java level shutdown hooks
4248   thread->invoke_shutdown_hooks();
4249 
4250   before_exit(thread);
4251 
4252   thread->exit(true);
4253 
4254   // Stop VM thread.
4255   {
4256     // 4945125 The vm thread comes to a safepoint during exit.
4257     // GC vm_operations can get caught at the safepoint, and the
4258     // heap is unparseable if they are caught. Grab the Heap_lock
4259     // to prevent this. The GC vm_operations will not be able to
4260     // queue until after the vm thread is dead. After this point,
4261     // we'll never emerge out of the safepoint before the VM exits.
4262 
4263     MutexLocker ml(Heap_lock);
4264 
4265     VMThread::wait_for_vm_thread_exit();
4266     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4267     VMThread::destroy();
4268   }
4269 
4270   // Now, all Java threads are gone except daemon threads. Daemon threads
4271   // running Java code or in VM are stopped by the Safepoint. However,
4272   // daemon threads executing native code are still running.  But they
4273   // will be stopped at native=>Java/VM barriers. Note that we can't
4274   // simply kill or suspend them, as it is inherently deadlock-prone.
4275 
4276   VM_Exit::set_vm_exited();
4277 
4278   // Clean up ideal graph printers after the VMThread has started
4279   // the final safepoint which will block all the Compiler threads.
4280   // Note that this Thread has already logically exited so the
4281   // clean_up() function's use of a JavaThreadIteratorWithHandle
4282   // would be a problem except set_vm_exited() has remembered the
4283   // shutdown thread which is granted a policy exception.
4284 #if defined(COMPILER2) && !defined(PRODUCT)
4285   IdealGraphPrinter::clean_up();
4286 #endif
4287 
4288   notify_vm_shutdown();
4289 
4290   // We are after VM_Exit::set_vm_exited() so we can't call
4291   // thread->smr_delete() or we will block on the Threads_lock.
4292   // Deleting the shutdown thread here is safe because another
4293   // JavaThread cannot have an active ThreadsListHandle for
4294   // this JavaThread.
4295   delete thread;
4296 
4297 #if INCLUDE_JVMCI
4298   if (JVMCICounterSize > 0) {
4299     FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4300   }
4301 #endif
4302 
4303   // exit_globals() will delete tty
4304   exit_globals();
4305 
4306   LogConfiguration::finalize();
4307 
4308   return true;
4309 }
4310 
4311 
4312 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4313   if (version == JNI_VERSION_1_1) return JNI_TRUE;
4314   return is_supported_jni_version(version);
4315 }
4316 
4317 
4318 jboolean Threads::is_supported_jni_version(jint version) {
4319   if (version == JNI_VERSION_1_2) return JNI_TRUE;
4320   if (version == JNI_VERSION_1_4) return JNI_TRUE;
4321   if (version == JNI_VERSION_1_6) return JNI_TRUE;
4322   if (version == JNI_VERSION_1_8) return JNI_TRUE;
4323   if (version == JNI_VERSION_9) return JNI_TRUE;
4324   if (version == JNI_VERSION_10) return JNI_TRUE;
4325   return JNI_FALSE;
4326 }
4327 
4328 
4329 void Threads::add(JavaThread* p, bool force_daemon) {
4330   // The threads lock must be owned at this point
4331   assert_locked_or_safepoint(Threads_lock);
4332 
4333   BarrierSet::barrier_set()->on_thread_attach(p);
4334 
4335   p->set_next(_thread_list);
4336   _thread_list = p;
4337 
4338   // Once a JavaThread is added to the Threads list, smr_delete() has
4339   // to be used to delete it. Otherwise we can just delete it directly.
4340   p->set_on_thread_list();
4341 
4342   _number_of_threads++;
4343   oop threadObj = p->threadObj();
4344   bool daemon = true;
4345   // Bootstrapping problem: threadObj can be null for initial
4346   // JavaThread (or for threads attached via JNI)
4347   if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4348     _number_of_non_daemon_threads++;
4349     daemon = false;
4350   }
4351 
4352   ThreadService::add_thread(p, daemon);
4353 
4354   // Maintain fast thread list
4355   ThreadsSMRSupport::add_thread(p);
4356 
4357   // Possible GC point.
4358   Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4359 }
4360 
4361 void Threads::remove(JavaThread* p) {
4362 
4363   // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
4364   ObjectSynchronizer::omFlush(p);
4365 
4366   // Extra scope needed for Thread_lock, so we can check
4367   // that we do not remove thread without safepoint code notice
4368   { MutexLocker ml(Threads_lock);
4369 
4370     assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4371 
4372     // Maintain fast thread list
4373     ThreadsSMRSupport::remove_thread(p);
4374 
4375     JavaThread* current = _thread_list;
4376     JavaThread* prev    = NULL;
4377 
4378     while (current != p) {
4379       prev    = current;
4380       current = current->next();
4381     }
4382 
4383     if (prev) {
4384       prev->set_next(current->next());
4385     } else {
4386       _thread_list = p->next();
4387     }
4388 
4389     _number_of_threads--;
4390     oop threadObj = p->threadObj();
4391     bool daemon = true;
4392     if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4393       _number_of_non_daemon_threads--;
4394       daemon = false;
4395 
4396       // Only one thread left, do a notify on the Threads_lock so a thread waiting
4397       // on destroy_vm will wake up.
4398       if (number_of_non_daemon_threads() == 1) {
4399         Threads_lock->notify_all();
4400       }
4401     }
4402     ThreadService::remove_thread(p, daemon);
4403 
4404     // Make sure that safepoint code disregard this thread. This is needed since
4405     // the thread might mess around with locks after this point. This can cause it
4406     // to do callbacks into the safepoint code. However, the safepoint code is not aware
4407     // of this thread since it is removed from the queue.
4408     p->set_terminated_value();
4409   } // unlock Threads_lock
4410 
4411   // Since Events::log uses a lock, we grab it outside the Threads_lock
4412   Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4413 }
4414 
4415 // Operations on the Threads list for GC.  These are not explicitly locked,
4416 // but the garbage collector must provide a safe context for them to run.
4417 // In particular, these things should never be called when the Threads_lock
4418 // is held by some other thread. (Note: the Safepoint abstraction also
4419 // uses the Threads_lock to guarantee this property. It also makes sure that
4420 // all threads gets blocked when exiting or starting).
4421 
4422 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4423   ALL_JAVA_THREADS(p) {
4424     p->oops_do(f, cf);
4425   }
4426   VMThread::vm_thread()->oops_do(f, cf);
4427 }
4428 
4429 void Threads::change_thread_claim_parity() {
4430   // Set the new claim parity.
4431   assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4432          "Not in range.");
4433   _thread_claim_parity++;
4434   if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4435   assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4436          "Not in range.");
4437 }
4438 
4439 #ifdef ASSERT
4440 void Threads::assert_all_threads_claimed() {
4441   ALL_JAVA_THREADS(p) {
4442     const int thread_parity = p->oops_do_parity();
4443     assert((thread_parity == _thread_claim_parity),
4444            "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4445   }
4446   VMThread* vmt = VMThread::vm_thread();
4447   const int thread_parity = vmt->oops_do_parity();
4448   assert((thread_parity == _thread_claim_parity),
4449          "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity);
4450 }
4451 #endif // ASSERT
4452 
4453 class ParallelOopsDoThreadClosure : public ThreadClosure {
4454 private:
4455   OopClosure* _f;
4456   CodeBlobClosure* _cf;
4457 public:
4458   ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4459   void do_thread(Thread* t) {
4460     t->oops_do(_f, _cf);
4461   }
4462 };
4463 
4464 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4465   ParallelOopsDoThreadClosure tc(f, cf);
4466   possibly_parallel_threads_do(is_par, &tc);
4467 }
4468 
4469 #if INCLUDE_ALL_GCS
4470 // Used by ParallelScavenge
4471 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4472   ALL_JAVA_THREADS(p) {
4473     q->enqueue(new ThreadRootsTask(p));
4474   }
4475   q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4476 }
4477 
4478 // Used by Parallel Old
4479 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4480   ALL_JAVA_THREADS(p) {
4481     q->enqueue(new ThreadRootsMarkingTask(p));
4482   }
4483   q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4484 }
4485 #endif // INCLUDE_ALL_GCS
4486 
4487 void Threads::nmethods_do(CodeBlobClosure* cf) {
4488   ALL_JAVA_THREADS(p) {
4489     // This is used by the code cache sweeper to mark nmethods that are active
4490     // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4491     // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4492     if(!p->is_Code_cache_sweeper_thread()) {
4493       p->nmethods_do(cf);
4494     }
4495   }
4496 }
4497 
4498 void Threads::metadata_do(void f(Metadata*)) {
4499   ALL_JAVA_THREADS(p) {
4500     p->metadata_do(f);
4501   }
4502 }
4503 
4504 class ThreadHandlesClosure : public ThreadClosure {
4505   void (*_f)(Metadata*);
4506  public:
4507   ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4508   virtual void do_thread(Thread* thread) {
4509     thread->metadata_handles_do(_f);
4510   }
4511 };
4512 
4513 void Threads::metadata_handles_do(void f(Metadata*)) {
4514   // Only walk the Handles in Thread.
4515   ThreadHandlesClosure handles_closure(f);
4516   threads_do(&handles_closure);
4517 }
4518 
4519 void Threads::deoptimized_wrt_marked_nmethods() {
4520   ALL_JAVA_THREADS(p) {
4521     p->deoptimized_wrt_marked_nmethods();
4522   }
4523 }
4524 
4525 
4526 // Get count Java threads that are waiting to enter the specified monitor.
4527 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4528                                                          int count,
4529                                                          address monitor) {
4530   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4531 
4532   int i = 0;
4533   DO_JAVA_THREADS(t_list, p) {
4534     if (!p->can_call_java()) continue;
4535 
4536     address pending = (address)p->current_pending_monitor();
4537     if (pending == monitor) {             // found a match
4538       if (i < count) result->append(p);   // save the first count matches
4539       i++;
4540     }
4541   }
4542 
4543   return result;
4544 }
4545 
4546 
4547 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4548                                                       address owner) {
4549   // NULL owner means not locked so we can skip the search
4550   if (owner == NULL) return NULL;
4551 
4552   DO_JAVA_THREADS(t_list, p) {
4553     // first, see if owner is the address of a Java thread
4554     if (owner == (address)p) return p;
4555   }
4556 
4557   // Cannot assert on lack of success here since this function may be
4558   // used by code that is trying to report useful problem information
4559   // like deadlock detection.
4560   if (UseHeavyMonitors) return NULL;
4561 
4562   // If we didn't find a matching Java thread and we didn't force use of
4563   // heavyweight monitors, then the owner is the stack address of the
4564   // Lock Word in the owning Java thread's stack.
4565   //
4566   JavaThread* the_owner = NULL;
4567   DO_JAVA_THREADS(t_list, q) {
4568     if (q->is_lock_owned(owner)) {
4569       the_owner = q;
4570       break;
4571     }
4572   }
4573 
4574   // cannot assert on lack of success here; see above comment
4575   return the_owner;
4576 }
4577 
4578 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4579 void Threads::print_on(outputStream* st, bool print_stacks,
4580                        bool internal_format, bool print_concurrent_locks) {
4581   char buf[32];
4582   st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4583 
4584   st->print_cr("Full thread dump %s (%s %s):",
4585                Abstract_VM_Version::vm_name(),
4586                Abstract_VM_Version::vm_release(),
4587                Abstract_VM_Version::vm_info_string());
4588   st->cr();
4589 
4590 #if INCLUDE_SERVICES
4591   // Dump concurrent locks
4592   ConcurrentLocksDump concurrent_locks;
4593   if (print_concurrent_locks) {
4594     concurrent_locks.dump_at_safepoint();
4595   }
4596 #endif // INCLUDE_SERVICES
4597 
4598   ThreadsSMRSupport::print_info_on(st);
4599   st->cr();
4600 
4601   ALL_JAVA_THREADS(p) {
4602     ResourceMark rm;
4603     p->print_on(st);
4604     if (print_stacks) {
4605       if (internal_format) {
4606         p->trace_stack();
4607       } else {
4608         p->print_stack_on(st);
4609       }
4610     }
4611     st->cr();
4612 #if INCLUDE_SERVICES
4613     if (print_concurrent_locks) {
4614       concurrent_locks.print_locks_on(p, st);
4615     }
4616 #endif // INCLUDE_SERVICES
4617   }
4618 
4619   VMThread::vm_thread()->print_on(st);
4620   st->cr();
4621   Universe::heap()->print_gc_threads_on(st);
4622   WatcherThread* wt = WatcherThread::watcher_thread();
4623   if (wt != NULL) {
4624     wt->print_on(st);
4625     st->cr();
4626   }
4627 
4628   st->flush();
4629 }
4630 
4631 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4632                              int buflen, bool* found_current) {
4633   if (this_thread != NULL) {
4634     bool is_current = (current == this_thread);
4635     *found_current = *found_current || is_current;
4636     st->print("%s", is_current ? "=>" : "  ");
4637 
4638     st->print(PTR_FORMAT, p2i(this_thread));
4639     st->print(" ");
4640     this_thread->print_on_error(st, buf, buflen);
4641     st->cr();
4642   }
4643 }
4644 
4645 class PrintOnErrorClosure : public ThreadClosure {
4646   outputStream* _st;
4647   Thread* _current;
4648   char* _buf;
4649   int _buflen;
4650   bool* _found_current;
4651  public:
4652   PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4653                       int buflen, bool* found_current) :
4654    _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4655 
4656   virtual void do_thread(Thread* thread) {
4657     Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4658   }
4659 };
4660 
4661 // Threads::print_on_error() is called by fatal error handler. It's possible
4662 // that VM is not at safepoint and/or current thread is inside signal handler.
4663 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4664 // memory (even in resource area), it might deadlock the error handler.
4665 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4666                              int buflen) {
4667   ThreadsSMRSupport::print_info_on(st);
4668   st->cr();
4669 
4670   bool found_current = false;
4671   st->print_cr("Java Threads: ( => current thread )");
4672   ALL_JAVA_THREADS(thread) {
4673     print_on_error(thread, st, current, buf, buflen, &found_current);
4674   }
4675   st->cr();
4676 
4677   st->print_cr("Other Threads:");
4678   print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4679   print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4680 
4681   PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4682   Universe::heap()->gc_threads_do(&print_closure);
4683 
4684   if (!found_current) {
4685     st->cr();
4686     st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4687     current->print_on_error(st, buf, buflen);
4688     st->cr();
4689   }
4690   st->cr();
4691 
4692   st->print_cr("Threads with active compile tasks:");
4693   print_threads_compiling(st, buf, buflen);
4694 }
4695 
4696 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4697   ALL_JAVA_THREADS(thread) {
4698     if (thread->is_Compiler_thread()) {
4699       CompilerThread* ct = (CompilerThread*) thread;
4700 
4701       // Keep task in local variable for NULL check.
4702       // ct->_task might be set to NULL by concurring compiler thread
4703       // because it completed the compilation. The task is never freed,
4704       // though, just returned to a free list.
4705       CompileTask* task = ct->task();
4706       if (task != NULL) {
4707         thread->print_name_on_error(st, buf, buflen);
4708         task->print(st, NULL, true, true);
4709       }
4710     }
4711   }
4712 }
4713 
4714 
4715 // Internal SpinLock and Mutex
4716 // Based on ParkEvent
4717 
4718 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4719 //
4720 // We employ SpinLocks _only for low-contention, fixed-length
4721 // short-duration critical sections where we're concerned
4722 // about native mutex_t or HotSpot Mutex:: latency.
4723 // The mux construct provides a spin-then-block mutual exclusion
4724 // mechanism.
4725 //
4726 // Testing has shown that contention on the ListLock guarding gFreeList
4727 // is common.  If we implement ListLock as a simple SpinLock it's common
4728 // for the JVM to devolve to yielding with little progress.  This is true
4729 // despite the fact that the critical sections protected by ListLock are
4730 // extremely short.
4731 //
4732 // TODO-FIXME: ListLock should be of type SpinLock.
4733 // We should make this a 1st-class type, integrated into the lock
4734 // hierarchy as leaf-locks.  Critically, the SpinLock structure
4735 // should have sufficient padding to avoid false-sharing and excessive
4736 // cache-coherency traffic.
4737 
4738 
4739 typedef volatile int SpinLockT;
4740 
4741 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4742   if (Atomic::cmpxchg (1, adr, 0) == 0) {
4743     return;   // normal fast-path return
4744   }
4745 
4746   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4747   TEVENT(SpinAcquire - ctx);
4748   int ctr = 0;
4749   int Yields = 0;
4750   for (;;) {
4751     while (*adr != 0) {
4752       ++ctr;
4753       if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4754         if (Yields > 5) {
4755           os::naked_short_sleep(1);
4756         } else {
4757           os::naked_yield();
4758           ++Yields;
4759         }
4760       } else {
4761         SpinPause();
4762       }
4763     }
4764     if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4765   }
4766 }
4767 
4768 void Thread::SpinRelease(volatile int * adr) {
4769   assert(*adr != 0, "invariant");
4770   OrderAccess::fence();      // guarantee at least release consistency.
4771   // Roach-motel semantics.
4772   // It's safe if subsequent LDs and STs float "up" into the critical section,
4773   // but prior LDs and STs within the critical section can't be allowed
4774   // to reorder or float past the ST that releases the lock.
4775   // Loads and stores in the critical section - which appear in program
4776   // order before the store that releases the lock - must also appear
4777   // before the store that releases the lock in memory visibility order.
4778   // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4779   // the ST of 0 into the lock-word which releases the lock, so fence
4780   // more than covers this on all platforms.
4781   *adr = 0;
4782 }
4783 
4784 // muxAcquire and muxRelease:
4785 //
4786 // *  muxAcquire and muxRelease support a single-word lock-word construct.
4787 //    The LSB of the word is set IFF the lock is held.
4788 //    The remainder of the word points to the head of a singly-linked list
4789 //    of threads blocked on the lock.
4790 //
4791 // *  The current implementation of muxAcquire-muxRelease uses its own
4792 //    dedicated Thread._MuxEvent instance.  If we're interested in
4793 //    minimizing the peak number of extant ParkEvent instances then
4794 //    we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4795 //    as certain invariants were satisfied.  Specifically, care would need
4796 //    to be taken with regards to consuming unpark() "permits".
4797 //    A safe rule of thumb is that a thread would never call muxAcquire()
4798 //    if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4799 //    park().  Otherwise the _ParkEvent park() operation in muxAcquire() could
4800 //    consume an unpark() permit intended for monitorenter, for instance.
4801 //    One way around this would be to widen the restricted-range semaphore
4802 //    implemented in park().  Another alternative would be to provide
4803 //    multiple instances of the PlatformEvent() for each thread.  One
4804 //    instance would be dedicated to muxAcquire-muxRelease, for instance.
4805 //
4806 // *  Usage:
4807 //    -- Only as leaf locks
4808 //    -- for short-term locking only as muxAcquire does not perform
4809 //       thread state transitions.
4810 //
4811 // Alternatives:
4812 // *  We could implement muxAcquire and muxRelease with MCS or CLH locks
4813 //    but with parking or spin-then-park instead of pure spinning.
4814 // *  Use Taura-Oyama-Yonenzawa locks.
4815 // *  It's possible to construct a 1-0 lock if we encode the lockword as
4816 //    (List,LockByte).  Acquire will CAS the full lockword while Release
4817 //    will STB 0 into the LockByte.  The 1-0 scheme admits stranding, so
4818 //    acquiring threads use timers (ParkTimed) to detect and recover from
4819 //    the stranding window.  Thread/Node structures must be aligned on 256-byte
4820 //    boundaries by using placement-new.
4821 // *  Augment MCS with advisory back-link fields maintained with CAS().
4822 //    Pictorially:  LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4823 //    The validity of the backlinks must be ratified before we trust the value.
4824 //    If the backlinks are invalid the exiting thread must back-track through the
4825 //    the forward links, which are always trustworthy.
4826 // *  Add a successor indication.  The LockWord is currently encoded as
4827 //    (List, LOCKBIT:1).  We could also add a SUCCBIT or an explicit _succ variable
4828 //    to provide the usual futile-wakeup optimization.
4829 //    See RTStt for details.
4830 // *  Consider schedctl.sc_nopreempt to cover the critical section.
4831 //
4832 
4833 
4834 const intptr_t LOCKBIT = 1;
4835 
4836 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4837   intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4838   if (w == 0) return;
4839   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4840     return;
4841   }
4842 
4843   TEVENT(muxAcquire - Contention);
4844   ParkEvent * const Self = Thread::current()->_MuxEvent;
4845   assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4846   for (;;) {
4847     int its = (os::is_MP() ? 100 : 0) + 1;
4848 
4849     // Optional spin phase: spin-then-park strategy
4850     while (--its >= 0) {
4851       w = *Lock;
4852       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4853         return;
4854       }
4855     }
4856 
4857     Self->reset();
4858     Self->OnList = intptr_t(Lock);
4859     // The following fence() isn't _strictly necessary as the subsequent
4860     // CAS() both serializes execution and ratifies the fetched *Lock value.
4861     OrderAccess::fence();
4862     for (;;) {
4863       w = *Lock;
4864       if ((w & LOCKBIT) == 0) {
4865         if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4866           Self->OnList = 0;   // hygiene - allows stronger asserts
4867           return;
4868         }
4869         continue;      // Interference -- *Lock changed -- Just retry
4870       }
4871       assert(w & LOCKBIT, "invariant");
4872       Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4873       if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4874     }
4875 
4876     while (Self->OnList != 0) {
4877       Self->park();
4878     }
4879   }
4880 }
4881 
4882 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4883   intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4884   if (w == 0) return;
4885   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4886     return;
4887   }
4888 
4889   TEVENT(muxAcquire - Contention);
4890   ParkEvent * ReleaseAfter = NULL;
4891   if (ev == NULL) {
4892     ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4893   }
4894   assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4895   for (;;) {
4896     guarantee(ev->OnList == 0, "invariant");
4897     int its = (os::is_MP() ? 100 : 0) + 1;
4898 
4899     // Optional spin phase: spin-then-park strategy
4900     while (--its >= 0) {
4901       w = *Lock;
4902       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4903         if (ReleaseAfter != NULL) {
4904           ParkEvent::Release(ReleaseAfter);
4905         }
4906         return;
4907       }
4908     }
4909 
4910     ev->reset();
4911     ev->OnList = intptr_t(Lock);
4912     // The following fence() isn't _strictly necessary as the subsequent
4913     // CAS() both serializes execution and ratifies the fetched *Lock value.
4914     OrderAccess::fence();
4915     for (;;) {
4916       w = *Lock;
4917       if ((w & LOCKBIT) == 0) {
4918         if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4919           ev->OnList = 0;
4920           // We call ::Release while holding the outer lock, thus
4921           // artificially lengthening the critical section.
4922           // Consider deferring the ::Release() until the subsequent unlock(),
4923           // after we've dropped the outer lock.
4924           if (ReleaseAfter != NULL) {
4925             ParkEvent::Release(ReleaseAfter);
4926           }
4927           return;
4928         }
4929         continue;      // Interference -- *Lock changed -- Just retry
4930       }
4931       assert(w & LOCKBIT, "invariant");
4932       ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4933       if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4934     }
4935 
4936     while (ev->OnList != 0) {
4937       ev->park();
4938     }
4939   }
4940 }
4941 
4942 // Release() must extract a successor from the list and then wake that thread.
4943 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4944 // similar to that used by ParkEvent::Allocate() and ::Release().  DMR-based
4945 // Release() would :
4946 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4947 // (B) Extract a successor from the private list "in-hand"
4948 // (C) attempt to CAS() the residual back into *Lock over null.
4949 //     If there were any newly arrived threads and the CAS() would fail.
4950 //     In that case Release() would detach the RATs, re-merge the list in-hand
4951 //     with the RATs and repeat as needed.  Alternately, Release() might
4952 //     detach and extract a successor, but then pass the residual list to the wakee.
4953 //     The wakee would be responsible for reattaching and remerging before it
4954 //     competed for the lock.
4955 //
4956 // Both "pop" and DMR are immune from ABA corruption -- there can be
4957 // multiple concurrent pushers, but only one popper or detacher.
4958 // This implementation pops from the head of the list.  This is unfair,
4959 // but tends to provide excellent throughput as hot threads remain hot.
4960 // (We wake recently run threads first).
4961 //
4962 // All paths through muxRelease() will execute a CAS.
4963 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4964 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4965 // executed within the critical section are complete and globally visible before the
4966 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4967 void Thread::muxRelease(volatile intptr_t * Lock)  {
4968   for (;;) {
4969     const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
4970     assert(w & LOCKBIT, "invariant");
4971     if (w == LOCKBIT) return;
4972     ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4973     assert(List != NULL, "invariant");
4974     assert(List->OnList == intptr_t(Lock), "invariant");
4975     ParkEvent * const nxt = List->ListNext;
4976     guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4977 
4978     // The following CAS() releases the lock and pops the head element.
4979     // The CAS() also ratifies the previously fetched lock-word value.
4980     if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
4981       continue;
4982     }
4983     List->OnList = 0;
4984     OrderAccess::fence();
4985     List->unpark();
4986     return;
4987   }
4988 }
4989 
4990 
4991 void Threads::verify() {
4992   ALL_JAVA_THREADS(p) {
4993     p->verify();
4994   }
4995   VMThread* thread = VMThread::vm_thread();
4996   if (thread != NULL) thread->verify();
4997 }