1 /*
   2  * Copyright (c) 1997, 2021, Oracle and/or its affiliates. All rights reserved.
   3  * Copyright (c) 2021, Azul Systems, Inc. All rights reserved.
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This code is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 only, as
   8  * published by the Free Software Foundation.
   9  *
  10  * This code is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  13  * version 2 for more details (a copy is included in the LICENSE file that
  14  * accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License version
  17  * 2 along with this work; if not, write to the Free Software Foundation,
  18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  19  *
  20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  21  * or visit www.oracle.com if you need additional information or have any
  22  * questions.
  23  *
  24  */
  25 
  26 #include "precompiled.hpp"
  27 #include "jvm.h"
  28 #include "cds/dynamicArchive.hpp"
  29 #include "cds/metaspaceShared.hpp"
  30 #include "classfile/classLoader.hpp"
  31 #include "classfile/javaClasses.hpp"
  32 #include "classfile/javaThreadStatus.hpp"
  33 #include "classfile/systemDictionary.hpp"
  34 #include "classfile/vmClasses.hpp"
  35 #include "classfile/vmSymbols.hpp"
  36 #include "code/codeCache.hpp"
  37 #include "code/scopeDesc.hpp"
  38 #include "compiler/compileBroker.hpp"
  39 #include "compiler/compileTask.hpp"
  40 #include "compiler/compilerThread.hpp"
  41 #include "gc/shared/barrierSet.hpp"
  42 #include "gc/shared/collectedHeap.hpp"
  43 #include "gc/shared/gcId.hpp"
  44 #include "gc/shared/gcLocker.inline.hpp"
  45 #include "gc/shared/gcVMOperations.hpp"
  46 #include "gc/shared/oopStorage.hpp"
  47 #include "gc/shared/oopStorageSet.hpp"
  48 #include "gc/shared/stringdedup/stringDedup.hpp"
  49 #include "gc/shared/tlab_globals.hpp"
  50 #include "interpreter/interpreter.hpp"
  51 #include "interpreter/linkResolver.hpp"
  52 #include "interpreter/oopMapCache.hpp"
  53 #include "jfr/jfrEvents.hpp"
  54 #include "jvmtifiles/jvmtiEnv.hpp"
  55 #include "logging/log.hpp"
  56 #include "logging/logAsyncWriter.hpp"
  57 #include "logging/logConfiguration.hpp"
  58 #include "logging/logStream.hpp"
  59 #include "memory/allocation.inline.hpp"
  60 #include "memory/iterator.hpp"
  61 #include "memory/oopFactory.hpp"
  62 #include "memory/resourceArea.hpp"
  63 #include "memory/universe.hpp"
  64 #include "oops/access.inline.hpp"
  65 #include "oops/instanceKlass.hpp"
  66 #include "oops/klass.inline.hpp"
  67 #include "oops/objArrayOop.hpp"
  68 #include "oops/oop.inline.hpp"
  69 #include "oops/oopHandle.inline.hpp"
  70 #include "oops/symbol.hpp"
  71 #include "oops/typeArrayOop.inline.hpp"
  72 #include "oops/verifyOopClosure.hpp"
  73 #include "prims/jvm_misc.hpp"
  74 #include "prims/jvmtiDeferredUpdates.hpp"
  75 #include "prims/jvmtiExport.hpp"
  76 #include "prims/jvmtiThreadState.hpp"
  77 #include "runtime/arguments.hpp"
  78 #include "runtime/atomic.hpp"
  79 #include "runtime/biasedLocking.hpp"
  80 #include "runtime/fieldDescriptor.inline.hpp"
  81 #include "runtime/flags/jvmFlagLimit.hpp"
  82 #include "runtime/deoptimization.hpp"
  83 #include "runtime/frame.inline.hpp"
  84 #include "runtime/handles.inline.hpp"
  85 #include "runtime/handshake.hpp"
  86 #include "runtime/init.hpp"
  87 #include "runtime/interfaceSupport.inline.hpp"
  88 #include "runtime/java.hpp"
  89 #include "runtime/javaCalls.hpp"
  90 #include "runtime/jniHandles.inline.hpp"
  91 #include "runtime/jniPeriodicChecker.hpp"
  92 #include "runtime/monitorDeflationThread.hpp"
  93 #include "runtime/mutexLocker.hpp"
  94 #include "runtime/nonJavaThread.hpp"
  95 #include "runtime/objectMonitor.hpp"
  96 #include "runtime/orderAccess.hpp"
  97 #include "runtime/osThread.hpp"
  98 #include "runtime/prefetch.inline.hpp"
  99 #include "runtime/safepoint.hpp"
 100 #include "runtime/safepointMechanism.inline.hpp"
 101 #include "runtime/safepointVerifiers.hpp"
 102 #include "runtime/serviceThread.hpp"
 103 #include "runtime/sharedRuntime.hpp"
 104 #include "runtime/stackFrameStream.inline.hpp"
 105 #include "runtime/stackWatermarkSet.hpp"
 106 #include "runtime/statSampler.hpp"
 107 #include "runtime/task.hpp"
 108 #include "runtime/thread.inline.hpp"
 109 #include "runtime/threadCritical.hpp"
 110 #include "runtime/threadSMR.inline.hpp"
 111 #include "runtime/threadStatisticalInfo.hpp"
 112 #include "runtime/threadWXSetters.inline.hpp"
 113 #include "runtime/timer.hpp"
 114 #include "runtime/timerTrace.hpp"
 115 #include "runtime/vframe.inline.hpp"
 116 #include "runtime/vframeArray.hpp"
 117 #include "runtime/vframe_hp.hpp"
 118 #include "runtime/vmThread.hpp"
 119 #include "runtime/vmOperations.hpp"
 120 #include "runtime/vm_version.hpp"
 121 #include "services/attachListener.hpp"
 122 #include "services/management.hpp"
 123 #include "services/memTracker.hpp"
 124 #include "services/threadService.hpp"
 125 #include "utilities/align.hpp"
 126 #include "utilities/copy.hpp"
 127 #include "utilities/defaultStream.hpp"
 128 #include "utilities/dtrace.hpp"
 129 #include "utilities/events.hpp"
 130 #include "utilities/macros.hpp"
 131 #include "utilities/preserveException.hpp"
 132 #include "utilities/spinYield.hpp"
 133 #include "utilities/vmError.hpp"
 134 #if INCLUDE_JVMCI
 135 #include "jvmci/jvmci.hpp"
 136 #include "jvmci/jvmciEnv.hpp"
 137 #endif
 138 #ifdef COMPILER1
 139 #include "c1/c1_Compiler.hpp"
 140 #endif
 141 #ifdef COMPILER2
 142 #include "opto/c2compiler.hpp"
 143 #include "opto/idealGraphPrinter.hpp"
 144 #endif
 145 #if INCLUDE_RTM_OPT
 146 #include "runtime/rtmLocking.hpp"
 147 #endif
 148 #if INCLUDE_JFR
 149 #include "jfr/jfr.hpp"
 150 #endif
 151 
 152 // Initialization after module runtime initialization
 153 void universe_post_module_init();  // must happen after call_initPhase2
 154 
 155 #ifdef DTRACE_ENABLED
 156 
 157 // Only bother with this argument setup if dtrace is available
 158 
 159   #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
 160   #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
 161 
 162   #define DTRACE_THREAD_PROBE(probe, javathread)                           \
 163     {                                                                      \
 164       ResourceMark rm(this);                                               \
 165       int len = 0;                                                         \
 166       const char* name = (javathread)->get_thread_name();                  \
 167       len = strlen(name);                                                  \
 168       HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */               \
 169         (char *) name, len,                                                \
 170         java_lang_Thread::thread_id((javathread)->threadObj()),            \
 171         (uintptr_t) (javathread)->osthread()->thread_id(),                 \
 172         java_lang_Thread::is_daemon((javathread)->threadObj()));           \
 173     }
 174 
 175 #else //  ndef DTRACE_ENABLED
 176 
 177   #define DTRACE_THREAD_PROBE(probe, javathread)
 178 
 179 #endif // ndef DTRACE_ENABLED
 180 
 181 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 182 // Current thread is maintained as a thread-local variable
 183 THREAD_LOCAL Thread* Thread::_thr_current = NULL;
 184 #endif
 185 
 186 // ======= Thread ========
 187 // Support for forcing alignment of thread objects for biased locking
 188 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
 189   if (UseBiasedLocking) {
 190     const size_t alignment = markWord::biased_lock_alignment;
 191     size_t aligned_size = size + (alignment - sizeof(intptr_t));
 192     void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
 193                                           : AllocateHeap(aligned_size, flags, CURRENT_PC,
 194                                                          AllocFailStrategy::RETURN_NULL);
 195     void* aligned_addr     = align_up(real_malloc_addr, alignment);
 196     assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
 197            ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
 198            "JavaThread alignment code overflowed allocated storage");
 199     if (aligned_addr != real_malloc_addr) {
 200       log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
 201                               p2i(real_malloc_addr),
 202                               p2i(aligned_addr));
 203     }
 204     ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
 205     return aligned_addr;
 206   } else {
 207     return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
 208                        : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
 209   }
 210 }
 211 
 212 void Thread::operator delete(void* p) {
 213   if (UseBiasedLocking) {
 214     FreeHeap(((Thread*) p)->_real_malloc_address);
 215   } else {
 216     FreeHeap(p);
 217   }
 218 }
 219 
 220 void JavaThread::smr_delete() {
 221   if (_on_thread_list) {
 222     ThreadsSMRSupport::smr_delete(this);
 223   } else {
 224     delete this;
 225   }
 226 }
 227 
 228 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
 229 // JavaThread
 230 
 231 DEBUG_ONLY(Thread* Thread::_starting_thread = NULL;)
 232 
 233 Thread::Thread() {
 234 
 235   DEBUG_ONLY(_run_state = PRE_CALL_RUN;)
 236 
 237   // stack and get_thread
 238   set_stack_base(NULL);
 239   set_stack_size(0);
 240   set_lgrp_id(-1);
 241   DEBUG_ONLY(clear_suspendible_thread();)
 242 
 243   // allocated data structures
 244   set_osthread(NULL);
 245   set_resource_area(new (mtThread)ResourceArea());
 246   DEBUG_ONLY(_current_resource_mark = NULL;)
 247   set_handle_area(new (mtThread) HandleArea(NULL));
 248   set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, mtClass));
 249   set_active_handles(NULL);
 250   set_free_handle_block(NULL);
 251   set_last_handle_mark(NULL);
 252   DEBUG_ONLY(_missed_ic_stub_refill_verifier = NULL);
 253 
 254   // Initial value of zero ==> never claimed.
 255   _threads_do_token = 0;
 256   _threads_hazard_ptr = NULL;
 257   _threads_list_ptr = NULL;
 258   _nested_threads_hazard_ptr_cnt = 0;
 259   _rcu_counter = 0;
 260 
 261   // the handle mark links itself to last_handle_mark
 262   new HandleMark(this);
 263 
 264   // plain initialization
 265   debug_only(_owned_locks = NULL;)
 266   NOT_PRODUCT(_skip_gcalot = false;)
 267   _jvmti_env_iteration_count = 0;
 268   set_allocated_bytes(0);
 269   _current_pending_raw_monitor = NULL;
 270 
 271   // thread-specific hashCode stream generator state - Marsaglia shift-xor form
 272   _hashStateX = os::random();
 273   _hashStateY = 842502087;
 274   _hashStateZ = 0x8767;    // (int)(3579807591LL & 0xffff) ;
 275   _hashStateW = 273326509;
 276 
 277   // Many of the following fields are effectively final - immutable
 278   // Note that nascent threads can't use the Native Monitor-Mutex
 279   // construct until the _MutexEvent is initialized ...
 280   // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
 281   // we might instead use a stack of ParkEvents that we could provision on-demand.
 282   // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
 283   // and ::Release()
 284   _ParkEvent   = ParkEvent::Allocate(this);
 285 
 286 #ifdef CHECK_UNHANDLED_OOPS
 287   if (CheckUnhandledOops) {
 288     _unhandled_oops = new UnhandledOops(this);
 289   }
 290 #endif // CHECK_UNHANDLED_OOPS
 291 #ifdef ASSERT
 292   if (UseBiasedLocking) {
 293     assert(is_aligned(this, markWord::biased_lock_alignment), "forced alignment of thread object failed");
 294     assert(this == _real_malloc_address ||
 295            this == align_up(_real_malloc_address, markWord::biased_lock_alignment),
 296            "bug in forced alignment of thread objects");
 297   }
 298 #endif // ASSERT
 299 
 300   // Notify the barrier set that a thread is being created. The initial
 301   // thread is created before the barrier set is available.  The call to
 302   // BarrierSet::on_thread_create() for this thread is therefore deferred
 303   // to BarrierSet::set_barrier_set().
 304   BarrierSet* const barrier_set = BarrierSet::barrier_set();
 305   if (barrier_set != NULL) {
 306     barrier_set->on_thread_create(this);
 307   } else {
 308     // Only the main thread should be created before the barrier set
 309     // and that happens just before Thread::current is set. No other thread
 310     // can attach as the VM is not created yet, so they can't execute this code.
 311     // If the main thread creates other threads before the barrier set that is an error.
 312     assert(Thread::current_or_null() == NULL, "creating thread before barrier set");
 313   }
 314 
 315   MACOS_AARCH64_ONLY(DEBUG_ONLY(_wx_init = false));
 316 }
 317 
 318 void Thread::initialize_tlab() {
 319   if (UseTLAB) {
 320     tlab().initialize();
 321   }
 322 }
 323 
 324 void Thread::initialize_thread_current() {
 325 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 326   assert(_thr_current == NULL, "Thread::current already initialized");
 327   _thr_current = this;
 328 #endif
 329   assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
 330   ThreadLocalStorage::set_thread(this);
 331   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 332 }
 333 
 334 void Thread::clear_thread_current() {
 335   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 336 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 337   _thr_current = NULL;
 338 #endif
 339   ThreadLocalStorage::set_thread(NULL);
 340 }
 341 
 342 void Thread::record_stack_base_and_size() {
 343   // Note: at this point, Thread object is not yet initialized. Do not rely on
 344   // any members being initialized. Do not rely on Thread::current() being set.
 345   // If possible, refrain from doing anything which may crash or assert since
 346   // quite probably those crash dumps will be useless.
 347   set_stack_base(os::current_stack_base());
 348   set_stack_size(os::current_stack_size());
 349 
 350   // Set stack limits after thread is initialized.
 351   if (is_Java_thread()) {
 352     as_Java_thread()->stack_overflow_state()->initialize(stack_base(), stack_end());
 353   }
 354 }
 355 
 356 #if INCLUDE_NMT
 357 void Thread::register_thread_stack_with_NMT() {
 358   MemTracker::record_thread_stack(stack_end(), stack_size());
 359 }
 360 
 361 void Thread::unregister_thread_stack_with_NMT() {
 362   MemTracker::release_thread_stack(stack_end(), stack_size());
 363 }
 364 #endif // INCLUDE_NMT
 365 
 366 void Thread::call_run() {
 367   DEBUG_ONLY(_run_state = CALL_RUN;)
 368 
 369   // At this point, Thread object should be fully initialized and
 370   // Thread::current() should be set.
 371 
 372   assert(Thread::current_or_null() != NULL, "current thread is unset");
 373   assert(Thread::current_or_null() == this, "current thread is wrong");
 374 
 375   // Perform common initialization actions
 376 
 377   MACOS_AARCH64_ONLY(this->init_wx());
 378 
 379   register_thread_stack_with_NMT();
 380 
 381   JFR_ONLY(Jfr::on_thread_start(this);)
 382 
 383   log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
 384     PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
 385     os::current_thread_id(), p2i(stack_end()),
 386     p2i(stack_base()), stack_size()/1024);
 387 
 388   // Perform <ChildClass> initialization actions
 389   DEBUG_ONLY(_run_state = PRE_RUN;)
 390   this->pre_run();
 391 
 392   // Invoke <ChildClass>::run()
 393   DEBUG_ONLY(_run_state = RUN;)
 394   this->run();
 395   // Returned from <ChildClass>::run(). Thread finished.
 396 
 397   // Perform common tear-down actions
 398 
 399   assert(Thread::current_or_null() != NULL, "current thread is unset");
 400   assert(Thread::current_or_null() == this, "current thread is wrong");
 401 
 402   // Perform <ChildClass> tear-down actions
 403   DEBUG_ONLY(_run_state = POST_RUN;)
 404   this->post_run();
 405 
 406   // Note: at this point the thread object may already have deleted itself,
 407   // so from here on do not dereference *this*. Not all thread types currently
 408   // delete themselves when they terminate. But no thread should ever be deleted
 409   // asynchronously with respect to its termination - that is what _run_state can
 410   // be used to check.
 411 
 412   assert(Thread::current_or_null() == NULL, "current thread still present");
 413 }
 414 
 415 Thread::~Thread() {
 416 
 417   // Attached threads will remain in PRE_CALL_RUN, as will threads that don't actually
 418   // get started due to errors etc. Any active thread should at least reach post_run
 419   // before it is deleted (usually in post_run()).
 420   assert(_run_state == PRE_CALL_RUN ||
 421          _run_state == POST_RUN, "Active Thread deleted before post_run(): "
 422          "_run_state=%d", (int)_run_state);
 423 
 424   // Notify the barrier set that a thread is being destroyed. Note that a barrier
 425   // set might not be available if we encountered errors during bootstrapping.
 426   BarrierSet* const barrier_set = BarrierSet::barrier_set();
 427   if (barrier_set != NULL) {
 428     barrier_set->on_thread_destroy(this);
 429   }
 430 
 431   // deallocate data structures
 432   delete resource_area();
 433   // since the handle marks are using the handle area, we have to deallocated the root
 434   // handle mark before deallocating the thread's handle area,
 435   assert(last_handle_mark() != NULL, "check we have an element");
 436   delete last_handle_mark();
 437   assert(last_handle_mark() == NULL, "check we have reached the end");
 438 
 439   ParkEvent::Release(_ParkEvent);
 440   // Set to NULL as a termination indicator for has_terminated().
 441   Atomic::store(&_ParkEvent, (ParkEvent*)NULL);
 442 
 443   delete handle_area();
 444   delete metadata_handles();
 445 
 446   // osthread() can be NULL, if creation of thread failed.
 447   if (osthread() != NULL) os::free_thread(osthread());
 448 
 449   // Clear Thread::current if thread is deleting itself and it has not
 450   // already been done. This must be done before the memory is deallocated.
 451   // Needed to ensure JNI correctly detects non-attached threads.
 452   if (this == Thread::current_or_null()) {
 453     Thread::clear_thread_current();
 454   }
 455 
 456   CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
 457 }
 458 
 459 #ifdef ASSERT
 460 // A JavaThread is considered dangling if it not handshake-safe with respect to
 461 // the current thread, it is not on a ThreadsList, or not at safepoint.
 462 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
 463   assert(!thread->is_Java_thread() ||
 464          thread->as_Java_thread()->is_handshake_safe_for(Thread::current()) ||
 465          !thread->as_Java_thread()->on_thread_list() ||
 466          SafepointSynchronize::is_at_safepoint() ||
 467          ThreadsSMRSupport::is_a_protected_JavaThread_with_lock(thread->as_Java_thread()),
 468          "possibility of dangling Thread pointer");
 469 }
 470 #endif
 471 
 472 // Is the target JavaThread protected by the calling Thread
 473 // or by some other mechanism:
 474 bool Thread::is_JavaThread_protected(const JavaThread* p) {
 475   // Do the simplest check first:
 476   if (SafepointSynchronize::is_at_safepoint()) {
 477     // The target is protected since JavaThreads cannot exit
 478     // while we're at a safepoint.
 479     return true;
 480   }
 481 
 482   // If the target hasn't been started yet then it is trivially
 483   // "protected". We assume the caller is the thread that will do
 484   // the starting.
 485   if (p->osthread() == NULL || p->osthread()->get_state() <= INITIALIZED) {
 486     return true;
 487   }
 488 
 489   // Now make the simple checks based on who the caller is:
 490   Thread* current_thread = Thread::current();
 491   if (current_thread == p || Threads_lock->owner() == current_thread) {
 492     // Target JavaThread is self or calling thread owns the Threads_lock.
 493     // Second check is the same as Threads_lock->owner_is_self(),
 494     // but we already have the current thread so check directly.
 495     return true;
 496   }
 497 
 498   // Check the ThreadsLists associated with the calling thread (if any)
 499   // to see if one of them protects the target JavaThread:
 500   for (SafeThreadsListPtr* stlp = current_thread->_threads_list_ptr;
 501        stlp != NULL; stlp = stlp->previous()) {
 502     if (stlp->list()->includes(p)) {
 503       // The target JavaThread is protected by this ThreadsList:
 504       return true;
 505     }
 506   }
 507 
 508   // Use this debug code with -XX:+UseNewCode to diagnose locations that
 509   // are missing a ThreadsListHandle or other protection mechanism:
 510   // guarantee(!UseNewCode, "current_thread=" INTPTR_FORMAT " is not protecting p="
 511   //           INTPTR_FORMAT, p2i(current_thread), p2i(p));
 512 
 513   // Note: Since 'p' isn't protected by a TLH, the call to
 514   // p->is_handshake_safe_for() may crash, but we have debug bits so
 515   // we'll be able to figure out what protection mechanism is missing.
 516   assert(p->is_handshake_safe_for(current_thread), "JavaThread=" INTPTR_FORMAT
 517          " is not protected and not handshake safe.", p2i(p));
 518 
 519   // The target JavaThread is not protected so it is not safe to query:
 520   return false;
 521 }
 522 
 523 ThreadPriority Thread::get_priority(const Thread* const thread) {
 524   ThreadPriority priority;
 525   // Can return an error!
 526   (void)os::get_priority(thread, priority);
 527   assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
 528   return priority;
 529 }
 530 
 531 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
 532   debug_only(check_for_dangling_thread_pointer(thread);)
 533   // Can return an error!
 534   (void)os::set_priority(thread, priority);
 535 }
 536 
 537 
 538 void Thread::start(Thread* thread) {
 539   // Start is different from resume in that its safety is guaranteed by context or
 540   // being called from a Java method synchronized on the Thread object.
 541   if (thread->is_Java_thread()) {
 542     // Initialize the thread state to RUNNABLE before starting this thread.
 543     // Can not set it after the thread started because we do not know the
 544     // exact thread state at that time. It could be in MONITOR_WAIT or
 545     // in SLEEPING or some other state.
 546     java_lang_Thread::set_thread_status(thread->as_Java_thread()->threadObj(),
 547                                         JavaThreadStatus::RUNNABLE);
 548   }
 549   os::start_thread(thread);
 550 }
 551 
 552 // GC Support
 553 bool Thread::claim_par_threads_do(uintx claim_token) {
 554   uintx token = _threads_do_token;
 555   if (token != claim_token) {
 556     uintx res = Atomic::cmpxchg(&_threads_do_token, token, claim_token);
 557     if (res == token) {
 558       return true;
 559     }
 560     guarantee(res == claim_token, "invariant");
 561   }
 562   return false;
 563 }
 564 
 565 void Thread::oops_do_no_frames(OopClosure* f, CodeBlobClosure* cf) {
 566   if (active_handles() != NULL) {
 567     active_handles()->oops_do(f);
 568   }
 569   // Do oop for ThreadShadow
 570   f->do_oop((oop*)&_pending_exception);
 571   handle_area()->oops_do(f);
 572 }
 573 
 574 // If the caller is a NamedThread, then remember, in the current scope,
 575 // the given JavaThread in its _processed_thread field.
 576 class RememberProcessedThread: public StackObj {
 577   NamedThread* _cur_thr;
 578 public:
 579   RememberProcessedThread(Thread* thread) {
 580     Thread* self = Thread::current();
 581     if (self->is_Named_thread()) {
 582       _cur_thr = (NamedThread *)self;
 583       assert(_cur_thr->processed_thread() == NULL, "nesting not supported");
 584       _cur_thr->set_processed_thread(thread);
 585     } else {
 586       _cur_thr = NULL;
 587     }
 588   }
 589 
 590   ~RememberProcessedThread() {
 591     if (_cur_thr) {
 592       assert(_cur_thr->processed_thread() != NULL, "nesting not supported");
 593       _cur_thr->set_processed_thread(NULL);
 594     }
 595   }
 596 };
 597 
 598 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
 599   // Record JavaThread to GC thread
 600   RememberProcessedThread rpt(this);
 601   oops_do_no_frames(f, cf);
 602   oops_do_frames(f, cf);
 603 }
 604 
 605 void Thread::metadata_handles_do(void f(Metadata*)) {
 606   // Only walk the Handles in Thread.
 607   if (metadata_handles() != NULL) {
 608     for (int i = 0; i< metadata_handles()->length(); i++) {
 609       f(metadata_handles()->at(i));
 610     }
 611   }
 612 }
 613 
 614 void Thread::print_on(outputStream* st, bool print_extended_info) const {
 615   // get_priority assumes osthread initialized
 616   if (osthread() != NULL) {
 617     int os_prio;
 618     if (os::get_native_priority(this, &os_prio) == OS_OK) {
 619       st->print("os_prio=%d ", os_prio);
 620     }
 621 
 622     st->print("cpu=%.2fms ",
 623               os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0
 624               );
 625     st->print("elapsed=%.2fs ",
 626               _statistical_info.getElapsedTime() / 1000.0
 627               );
 628     if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) {
 629       size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes();
 630       st->print("allocated=" SIZE_FORMAT "%s ",
 631                 byte_size_in_proper_unit(allocated_bytes),
 632                 proper_unit_for_byte_size(allocated_bytes)
 633                 );
 634       st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount());
 635     }
 636 
 637     st->print("tid=" INTPTR_FORMAT " ", p2i(this));
 638     osthread()->print_on(st);
 639   }
 640   ThreadsSMRSupport::print_info_on(this, st);
 641   st->print(" ");
 642   debug_only(if (WizardMode) print_owned_locks_on(st);)
 643 }
 644 
 645 void Thread::print() const { print_on(tty); }
 646 
 647 // Thread::print_on_error() is called by fatal error handler. Don't use
 648 // any lock or allocate memory.
 649 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
 650   assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
 651 
 652   if (is_VM_thread())                 { st->print("VMThread"); }
 653   else if (is_GC_task_thread())       { st->print("GCTaskThread"); }
 654   else if (is_Watcher_thread())       { st->print("WatcherThread"); }
 655   else if (is_ConcurrentGC_thread())  { st->print("ConcurrentGCThread"); }
 656   else                                { st->print("Thread"); }
 657 
 658   if (is_Named_thread()) {
 659     st->print(" \"%s\"", name());
 660   }
 661 
 662   OSThread* os_thr = osthread();
 663   if (os_thr != NULL) {
 664     if (os_thr->get_state() != ZOMBIE) {
 665       st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
 666                 p2i(stack_end()), p2i(stack_base()));
 667       st->print(" [id=%d]", osthread()->thread_id());
 668     } else {
 669       st->print(" terminated");
 670     }
 671   } else {
 672     st->print(" unknown state (no osThread)");
 673   }
 674   ThreadsSMRSupport::print_info_on(this, st);
 675 }
 676 
 677 void Thread::print_value_on(outputStream* st) const {
 678   if (is_Named_thread()) {
 679     st->print(" \"%s\" ", name());
 680   }
 681   st->print(INTPTR_FORMAT, p2i(this));   // print address
 682 }
 683 
 684 #ifdef ASSERT
 685 void Thread::print_owned_locks_on(outputStream* st) const {
 686   Mutex* cur = _owned_locks;
 687   if (cur == NULL) {
 688     st->print(" (no locks) ");
 689   } else {
 690     st->print_cr(" Locks owned:");
 691     while (cur) {
 692       cur->print_on(st);
 693       cur = cur->next();
 694     }
 695   }
 696 }
 697 #endif // ASSERT
 698 
 699 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
 700 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
 701 // used for compilation in the future. If that change is made, the need for these methods
 702 // should be revisited, and they should be removed if possible.
 703 
 704 bool Thread::is_lock_owned(address adr) const {
 705   return is_in_full_stack(adr);
 706 }
 707 
 708 bool Thread::set_as_starting_thread() {
 709   assert(_starting_thread == NULL, "already initialized: "
 710          "_starting_thread=" INTPTR_FORMAT, p2i(_starting_thread));
 711   // NOTE: this must be called inside the main thread.
 712   DEBUG_ONLY(_starting_thread = this;)
 713   return os::create_main_thread(this->as_Java_thread());
 714 }
 715 
 716 static void initialize_class(Symbol* class_name, TRAPS) {
 717   Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
 718   InstanceKlass::cast(klass)->initialize(CHECK);
 719 }
 720 
 721 
 722 // Creates the initial ThreadGroup
 723 static Handle create_initial_thread_group(TRAPS) {
 724   Handle system_instance = JavaCalls::construct_new_instance(
 725                             vmClasses::ThreadGroup_klass(),
 726                             vmSymbols::void_method_signature(),
 727                             CHECK_NH);
 728   Universe::set_system_thread_group(system_instance());
 729 
 730   Handle string = java_lang_String::create_from_str("main", CHECK_NH);
 731   Handle main_instance = JavaCalls::construct_new_instance(
 732                             vmClasses::ThreadGroup_klass(),
 733                             vmSymbols::threadgroup_string_void_signature(),
 734                             system_instance,
 735                             string,
 736                             CHECK_NH);
 737   return main_instance;
 738 }
 739 
 740 // Creates the initial Thread, and sets it to running.
 741 static void create_initial_thread(Handle thread_group, JavaThread* thread,
 742                                  TRAPS) {
 743   InstanceKlass* ik = vmClasses::Thread_klass();
 744   assert(ik->is_initialized(), "must be");
 745   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
 746 
 747   // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread
 748   // constructor calls Thread.current(), which must be set here for the
 749   // initial thread.
 750   java_lang_Thread::set_thread(thread_oop(), thread);
 751   java_lang_Thread::set_priority(thread_oop(), NormPriority);
 752   thread->set_threadObj(thread_oop());
 753 
 754   Handle string = java_lang_String::create_from_str("main", CHECK);
 755 
 756   JavaValue result(T_VOID);
 757   JavaCalls::call_special(&result, thread_oop,
 758                           ik,
 759                           vmSymbols::object_initializer_name(),
 760                           vmSymbols::threadgroup_string_void_signature(),
 761                           thread_group,
 762                           string,
 763                           CHECK);
 764 
 765   // Set thread status to running since main thread has
 766   // been started and running.
 767   java_lang_Thread::set_thread_status(thread_oop(),
 768                                       JavaThreadStatus::RUNNABLE);
 769 }
 770 
 771 // Extract version and vendor specific information from
 772 // java.lang.VersionProps fields.
 773 // Returned char* is allocated in the thread's resource area
 774 // so must be copied for permanency.
 775 static const char* get_java_version_info(InstanceKlass* ik,
 776                                          Symbol* field_name) {
 777   fieldDescriptor fd;
 778   bool found = ik != NULL &&
 779                ik->find_local_field(field_name,
 780                                     vmSymbols::string_signature(), &fd);
 781   if (found) {
 782     oop name_oop = ik->java_mirror()->obj_field(fd.offset());
 783     if (name_oop == NULL) {
 784       return NULL;
 785     }
 786     const char* name = java_lang_String::as_utf8_string(name_oop);
 787     return name;
 788   } else {
 789     return NULL;
 790   }
 791 }
 792 
 793 // General purpose hook into Java code, run once when the VM is initialized.
 794 // The Java library method itself may be changed independently from the VM.
 795 static void call_postVMInitHook(TRAPS) {
 796   Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
 797   if (klass != NULL) {
 798     JavaValue result(T_VOID);
 799     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
 800                            vmSymbols::void_method_signature(),
 801                            CHECK);
 802   }
 803 }
 804 
 805 // Initialized by VMThread at vm_global_init
 806 static OopStorage* _thread_oop_storage = NULL;
 807 
 808 oop  JavaThread::threadObj() const    {
 809   return _threadObj.resolve();
 810 }
 811 
 812 void JavaThread::set_threadObj(oop p) {
 813   assert(_thread_oop_storage != NULL, "not yet initialized");
 814   _threadObj = OopHandle(_thread_oop_storage, p);
 815 }
 816 
 817 OopStorage* JavaThread::thread_oop_storage() {
 818   assert(_thread_oop_storage != NULL, "not yet initialized");
 819   return _thread_oop_storage;
 820 }
 821 
 822 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
 823                                     bool daemon, TRAPS) {
 824   assert(thread_group.not_null(), "thread group should be specified");
 825   assert(threadObj() == NULL, "should only create Java thread object once");
 826 
 827   InstanceKlass* ik = vmClasses::Thread_klass();
 828   assert(ik->is_initialized(), "must be");
 829   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
 830 
 831   // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon.
 832   // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread
 833   // constructor calls Thread.current(), which must be set here.
 834   java_lang_Thread::set_thread(thread_oop(), this);
 835   java_lang_Thread::set_priority(thread_oop(), NormPriority);
 836   set_threadObj(thread_oop());
 837 
 838   JavaValue result(T_VOID);
 839   if (thread_name != NULL) {
 840     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
 841     // Thread gets assigned specified name and null target
 842     JavaCalls::call_special(&result,
 843                             thread_oop,
 844                             ik,
 845                             vmSymbols::object_initializer_name(),
 846                             vmSymbols::threadgroup_string_void_signature(),
 847                             thread_group,
 848                             name,
 849                             THREAD);
 850   } else {
 851     // Thread gets assigned name "Thread-nnn" and null target
 852     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
 853     JavaCalls::call_special(&result,
 854                             thread_oop,
 855                             ik,
 856                             vmSymbols::object_initializer_name(),
 857                             vmSymbols::threadgroup_runnable_void_signature(),
 858                             thread_group,
 859                             Handle(),
 860                             THREAD);
 861   }
 862 
 863 
 864   if (daemon) {
 865     java_lang_Thread::set_daemon(thread_oop());
 866   }
 867 
 868   if (HAS_PENDING_EXCEPTION) {
 869     return;
 870   }
 871 
 872   Klass* group = vmClasses::ThreadGroup_klass();
 873   Handle threadObj(THREAD, this->threadObj());
 874 
 875   JavaCalls::call_special(&result,
 876                           thread_group,
 877                           group,
 878                           vmSymbols::add_method_name(),
 879                           vmSymbols::thread_void_signature(),
 880                           threadObj,          // Arg 1
 881                           THREAD);
 882 }
 883 
 884 // ======= JavaThread ========
 885 
 886 #if INCLUDE_JVMCI
 887 
 888 jlong* JavaThread::_jvmci_old_thread_counters;
 889 
 890 bool jvmci_counters_include(JavaThread* thread) {
 891   return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
 892 }
 893 
 894 void JavaThread::collect_counters(jlong* array, int length) {
 895   assert(length == JVMCICounterSize, "wrong value");
 896   for (int i = 0; i < length; i++) {
 897     array[i] = _jvmci_old_thread_counters[i];
 898   }
 899   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) {
 900     if (jvmci_counters_include(tp)) {
 901       for (int i = 0; i < length; i++) {
 902         array[i] += tp->_jvmci_counters[i];
 903       }
 904     }
 905   }
 906 }
 907 
 908 // Attempt to enlarge the array for per thread counters.
 909 jlong* resize_counters_array(jlong* old_counters, int current_size, int new_size) {
 910   jlong* new_counters = NEW_C_HEAP_ARRAY_RETURN_NULL(jlong, new_size, mtJVMCI);
 911   if (new_counters == NULL) {
 912     return NULL;
 913   }
 914   if (old_counters == NULL) {
 915     old_counters = new_counters;
 916     memset(old_counters, 0, sizeof(jlong) * new_size);
 917   } else {
 918     for (int i = 0; i < MIN2((int) current_size, new_size); i++) {
 919       new_counters[i] = old_counters[i];
 920     }
 921     if (new_size > current_size) {
 922       memset(new_counters + current_size, 0, sizeof(jlong) * (new_size - current_size));
 923     }
 924     FREE_C_HEAP_ARRAY(jlong, old_counters);
 925   }
 926   return new_counters;
 927 }
 928 
 929 // Attempt to enlarge the array for per thread counters.
 930 bool JavaThread::resize_counters(int current_size, int new_size) {
 931   jlong* new_counters = resize_counters_array(_jvmci_counters, current_size, new_size);
 932   if (new_counters == NULL) {
 933     return false;
 934   } else {
 935     _jvmci_counters = new_counters;
 936     return true;
 937   }
 938 }
 939 
 940 class VM_JVMCIResizeCounters : public VM_Operation {
 941  private:
 942   int _new_size;
 943   bool _failed;
 944 
 945  public:
 946   VM_JVMCIResizeCounters(int new_size) : _new_size(new_size), _failed(false) { }
 947   VMOp_Type type()                  const        { return VMOp_JVMCIResizeCounters; }
 948   bool allow_nested_vm_operations() const        { return true; }
 949   void doit() {
 950     // Resize the old thread counters array
 951     jlong* new_counters = resize_counters_array(JavaThread::_jvmci_old_thread_counters, JVMCICounterSize, _new_size);
 952     if (new_counters == NULL) {
 953       _failed = true;
 954       return;
 955     } else {
 956       JavaThread::_jvmci_old_thread_counters = new_counters;
 957     }
 958 
 959     // Now resize each threads array
 960     for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) {
 961       if (!tp->resize_counters(JVMCICounterSize, _new_size)) {
 962         _failed = true;
 963         break;
 964       }
 965     }
 966     if (!_failed) {
 967       JVMCICounterSize = _new_size;
 968     }
 969   }
 970 
 971   bool failed() { return _failed; }
 972 };
 973 
 974 bool JavaThread::resize_all_jvmci_counters(int new_size) {
 975   VM_JVMCIResizeCounters op(new_size);
 976   VMThread::execute(&op);
 977   return !op.failed();
 978 }
 979 
 980 #endif // INCLUDE_JVMCI
 981 
 982 #ifdef ASSERT
 983 // Checks safepoint allowed and clears unhandled oops at potential safepoints.
 984 void JavaThread::check_possible_safepoint() {
 985   if (_no_safepoint_count > 0) {
 986     print_owned_locks();
 987     assert(false, "Possible safepoint reached by thread that does not allow it");
 988   }
 989 #ifdef CHECK_UNHANDLED_OOPS
 990   // Clear unhandled oops in JavaThreads so we get a crash right away.
 991   clear_unhandled_oops();
 992 #endif // CHECK_UNHANDLED_OOPS
 993 }
 994 
 995 void JavaThread::check_for_valid_safepoint_state() {
 996   // Check NoSafepointVerifier, which is implied by locks taken that can be
 997   // shared with the VM thread.  This makes sure that no locks with allow_vm_block
 998   // are held.
 999   check_possible_safepoint();
1000 
1001   if (thread_state() != _thread_in_vm) {
1002     fatal("LEAF method calling lock?");
1003   }
1004 
1005   if (GCALotAtAllSafepoints) {
1006     // We could enter a safepoint here and thus have a gc
1007     InterfaceSupport::check_gc_alot();
1008   }
1009 }
1010 #endif // ASSERT
1011 
1012 // A JavaThread is a normal Java thread
1013 
1014 JavaThread::JavaThread() :
1015   // Initialize fields
1016 
1017   _in_asgct(false),
1018   _on_thread_list(false),
1019   DEBUG_ONLY(_java_call_counter(0) COMMA)
1020   _entry_point(nullptr),
1021   _deopt_mark(nullptr),
1022   _deopt_nmethod(nullptr),
1023   _vframe_array_head(nullptr),
1024   _vframe_array_last(nullptr),
1025   _jvmti_deferred_updates(nullptr),
1026   _callee_target(nullptr),
1027   _vm_result(nullptr),
1028   _vm_result_2(nullptr),
1029 
1030   _current_pending_monitor(NULL),
1031   _current_pending_monitor_is_from_java(true),
1032   _current_waiting_monitor(NULL),
1033   _Stalled(0),
1034 
1035   _monitor_chunks(nullptr),
1036 
1037   _suspend_flags(0),
1038   _async_exception_condition(_no_async_condition),
1039   _pending_async_exception(nullptr),
1040 
1041   _thread_state(_thread_new),
1042   _saved_exception_pc(nullptr),
1043 #ifdef ASSERT
1044   _no_safepoint_count(0),
1045   _visited_for_critical_count(false),
1046 #endif
1047 
1048   _terminated(_not_terminated),
1049   _in_deopt_handler(0),
1050   _doing_unsafe_access(false),
1051   _do_not_unlock_if_synchronized(false),
1052   _jni_attach_state(_not_attaching_via_jni),
1053 #if INCLUDE_JVMCI
1054   _pending_deoptimization(-1),
1055   _pending_monitorenter(false),
1056   _pending_transfer_to_interpreter(false),
1057   _in_retryable_allocation(false),
1058   _pending_failed_speculation(0),
1059   _jvmci{nullptr},
1060   _jvmci_counters(nullptr),
1061   _jvmci_reserved0(0),
1062   _jvmci_reserved1(0),
1063   _jvmci_reserved_oop0(nullptr),
1064 #endif // INCLUDE_JVMCI
1065 
1066   _exception_oop(oop()),
1067   _exception_pc(0),
1068   _exception_handler_pc(0),
1069   _is_method_handle_return(0),
1070 
1071   _jni_active_critical(0),
1072   _pending_jni_exception_check_fn(nullptr),
1073   _depth_first_number(0),
1074 
1075   // JVMTI PopFrame support
1076   _popframe_condition(popframe_inactive),
1077   _frames_to_pop_failed_realloc(0),
1078 
1079   _handshake(this),
1080 
1081   _popframe_preserved_args(nullptr),
1082   _popframe_preserved_args_size(0),
1083 
1084   _jvmti_thread_state(nullptr),
1085   _interp_only_mode(0),
1086   _should_post_on_exceptions_flag(JNI_FALSE),
1087   _thread_stat(new ThreadStatistics()),
1088 
1089   _parker(),
1090   _cached_monitor_info(nullptr),
1091 
1092   _class_to_be_initialized(nullptr),
1093 
1094   _SleepEvent(ParkEvent::Allocate(this))
1095 {
1096   set_jni_functions(jni_functions());
1097 
1098 #if INCLUDE_JVMCI
1099   assert(_jvmci._implicit_exception_pc == nullptr, "must be");
1100   if (JVMCICounterSize > 0) {
1101     resize_counters(0, (int) JVMCICounterSize);
1102   }
1103 #endif // INCLUDE_JVMCI
1104 
1105   // Setup safepoint state info for this thread
1106   ThreadSafepointState::create(this);
1107 
1108   SafepointMechanism::initialize_header(this);
1109 
1110   set_requires_cross_modify_fence(false);
1111 
1112   pd_initialize();
1113   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1114 }
1115 
1116 JavaThread::JavaThread(bool is_attaching_via_jni) : JavaThread() {
1117   if (is_attaching_via_jni) {
1118     _jni_attach_state = _attaching_via_jni;
1119   }
1120 }
1121 
1122 
1123 // interrupt support
1124 
1125 void JavaThread::interrupt() {
1126   // All callers should have 'this' thread protected by a
1127   // ThreadsListHandle so that it cannot terminate and deallocate
1128   // itself.
1129   debug_only(check_for_dangling_thread_pointer(this);)
1130 
1131   // For Windows _interrupt_event
1132   osthread()->set_interrupted(true);
1133 
1134   // For Thread.sleep
1135   _SleepEvent->unpark();
1136 
1137   // For JSR166 LockSupport.park
1138   parker()->unpark();
1139 
1140   // For ObjectMonitor and JvmtiRawMonitor
1141   _ParkEvent->unpark();
1142 }
1143 
1144 
1145 bool JavaThread::is_interrupted(bool clear_interrupted) {
1146   debug_only(check_for_dangling_thread_pointer(this);)
1147 
1148   if (_threadObj.peek() == NULL) {
1149     // If there is no j.l.Thread then it is impossible to have
1150     // been interrupted. We can find NULL during VM initialization
1151     // or when a JNI thread is still in the process of attaching.
1152     // In such cases this must be the current thread.
1153     assert(this == Thread::current(), "invariant");
1154     return false;
1155   }
1156 
1157   bool interrupted = java_lang_Thread::interrupted(threadObj());
1158 
1159   // NOTE that since there is no "lock" around the interrupt and
1160   // is_interrupted operations, there is the possibility that the
1161   // interrupted flag will be "false" but that the
1162   // low-level events will be in the signaled state. This is
1163   // intentional. The effect of this is that Object.wait() and
1164   // LockSupport.park() will appear to have a spurious wakeup, which
1165   // is allowed and not harmful, and the possibility is so rare that
1166   // it is not worth the added complexity to add yet another lock.
1167   // For the sleep event an explicit reset is performed on entry
1168   // to JavaThread::sleep, so there is no early return. It has also been
1169   // recommended not to put the interrupted flag into the "event"
1170   // structure because it hides the issue.
1171   // Also, because there is no lock, we must only clear the interrupt
1172   // state if we are going to report that we were interrupted; otherwise
1173   // an interrupt that happens just after we read the field would be lost.
1174   if (interrupted && clear_interrupted) {
1175     assert(this == Thread::current(), "only the current thread can clear");
1176     java_lang_Thread::set_interrupted(threadObj(), false);
1177     osthread()->set_interrupted(false);
1178   }
1179 
1180   return interrupted;
1181 }
1182 
1183 void JavaThread::block_if_vm_exited() {
1184   if (_terminated == _vm_exited) {
1185     // _vm_exited is set at safepoint, and Threads_lock is never released
1186     // we will block here forever.
1187     // Here we can be doing a jump from a safe state to an unsafe state without
1188     // proper transition, but it happens after the final safepoint has begun.
1189     set_thread_state(_thread_in_vm);
1190     Threads_lock->lock();
1191     ShouldNotReachHere();
1192   }
1193 }
1194 
1195 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : JavaThread() {
1196   _jni_attach_state = _not_attaching_via_jni;
1197   set_entry_point(entry_point);
1198   // Create the native thread itself.
1199   // %note runtime_23
1200   os::ThreadType thr_type = os::java_thread;
1201   thr_type = entry_point == &CompilerThread::thread_entry ? os::compiler_thread :
1202                                                             os::java_thread;
1203   os::create_thread(this, thr_type, stack_sz);
1204   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1205   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1206   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1207   // the exception consists of creating the exception object & initializing it, initialization
1208   // will leave the VM via a JavaCall and then all locks must be unlocked).
1209   //
1210   // The thread is still suspended when we reach here. Thread must be explicit started
1211   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1212   // by calling Threads:add. The reason why this is not done here, is because the thread
1213   // object must be fully initialized (take a look at JVM_Start)
1214 }
1215 
1216 JavaThread::~JavaThread() {
1217 
1218   // Ask ServiceThread to release the threadObj OopHandle
1219   ServiceThread::add_oop_handle_release(_threadObj);
1220 
1221   // Return the sleep event to the free list
1222   ParkEvent::Release(_SleepEvent);
1223   _SleepEvent = NULL;
1224 
1225   // Free any remaining  previous UnrollBlock
1226   vframeArray* old_array = vframe_array_last();
1227 
1228   if (old_array != NULL) {
1229     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1230     old_array->set_unroll_block(NULL);
1231     delete old_info;
1232     delete old_array;
1233   }
1234 
1235   JvmtiDeferredUpdates* updates = deferred_updates();
1236   if (updates != NULL) {
1237     // This can only happen if thread is destroyed before deoptimization occurs.
1238     assert(updates->count() > 0, "Updates holder not deleted");
1239     // free deferred updates.
1240     delete updates;
1241     set_deferred_updates(NULL);
1242   }
1243 
1244   // All Java related clean up happens in exit
1245   ThreadSafepointState::destroy(this);
1246   if (_thread_stat != NULL) delete _thread_stat;
1247 
1248 #if INCLUDE_JVMCI
1249   if (JVMCICounterSize > 0) {
1250     FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1251   }
1252 #endif // INCLUDE_JVMCI
1253 }
1254 
1255 
1256 // First JavaThread specific code executed by a new Java thread.
1257 void JavaThread::pre_run() {
1258   // empty - see comments in run()
1259 }
1260 
1261 // The main routine called by a new Java thread. This isn't overridden
1262 // by subclasses, instead different subclasses define a different "entry_point"
1263 // which defines the actual logic for that kind of thread.
1264 void JavaThread::run() {
1265   // initialize thread-local alloc buffer related fields
1266   initialize_tlab();
1267 
1268   _stack_overflow_state.create_stack_guard_pages();
1269 
1270   cache_global_variables();
1271 
1272   // Thread is now sufficiently initialized to be handled by the safepoint code as being
1273   // in the VM. Change thread state from _thread_new to _thread_in_vm
1274   ThreadStateTransition::transition(this, _thread_new, _thread_in_vm);
1275   // Before a thread is on the threads list it is always safe, so after leaving the
1276   // _thread_new we should emit a instruction barrier. The distance to modified code
1277   // from here is probably far enough, but this is consistent and safe.
1278   OrderAccess::cross_modify_fence();
1279 
1280   assert(JavaThread::current() == this, "sanity check");
1281   assert(!Thread::current()->owns_locks(), "sanity check");
1282 
1283   DTRACE_THREAD_PROBE(start, this);
1284 
1285   // This operation might block. We call that after all safepoint checks for a new thread has
1286   // been completed.
1287   set_active_handles(JNIHandleBlock::allocate_block());
1288 
1289   if (JvmtiExport::should_post_thread_life()) {
1290     JvmtiExport::post_thread_start(this);
1291 
1292   }
1293 
1294   // We call another function to do the rest so we are sure that the stack addresses used
1295   // from there will be lower than the stack base just computed.
1296   thread_main_inner();
1297 }
1298 
1299 void JavaThread::thread_main_inner() {
1300   assert(JavaThread::current() == this, "sanity check");
1301   assert(_threadObj.peek() != NULL, "just checking");
1302 
1303   // Execute thread entry point unless this thread has a pending exception
1304   // or has been stopped before starting.
1305   // Note: Due to JVM_StopThread we can have pending exceptions already!
1306   if (!this->has_pending_exception() &&
1307       !java_lang_Thread::is_stillborn(this->threadObj())) {
1308     {
1309       ResourceMark rm(this);
1310       this->set_native_thread_name(this->get_thread_name());
1311     }
1312     HandleMark hm(this);
1313     this->entry_point()(this, this);
1314   }
1315 
1316   DTRACE_THREAD_PROBE(stop, this);
1317 
1318   // Cleanup is handled in post_run()
1319 }
1320 
1321 // Shared teardown for all JavaThreads
1322 void JavaThread::post_run() {
1323   this->exit(false);
1324   this->unregister_thread_stack_with_NMT();
1325   // Defer deletion to here to ensure 'this' is still referenceable in call_run
1326   // for any shared tear-down.
1327   this->smr_delete();
1328 }
1329 
1330 static void ensure_join(JavaThread* thread) {
1331   // We do not need to grab the Threads_lock, since we are operating on ourself.
1332   Handle threadObj(thread, thread->threadObj());
1333   assert(threadObj.not_null(), "java thread object must exist");
1334   ObjectLocker lock(threadObj, thread);
1335   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1336   thread->clear_pending_exception();
1337   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1338   java_lang_Thread::set_thread_status(threadObj(), JavaThreadStatus::TERMINATED);
1339   // Clear the native thread instance - this makes isAlive return false and allows the join()
1340   // to complete once we've done the notify_all below
1341   java_lang_Thread::set_thread(threadObj(), NULL);
1342   lock.notify_all(thread);
1343   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1344   thread->clear_pending_exception();
1345 }
1346 
1347 static bool is_daemon(oop threadObj) {
1348   return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj));
1349 }
1350 
1351 // For any new cleanup additions, please check to see if they need to be applied to
1352 // cleanup_failed_attach_current_thread as well.
1353 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1354   assert(this == JavaThread::current(), "thread consistency check");
1355 
1356   elapsedTimer _timer_exit_phase1;
1357   elapsedTimer _timer_exit_phase2;
1358   elapsedTimer _timer_exit_phase3;
1359   elapsedTimer _timer_exit_phase4;
1360 
1361   if (log_is_enabled(Debug, os, thread, timer)) {
1362     _timer_exit_phase1.start();
1363   }
1364 
1365   HandleMark hm(this);
1366   Handle uncaught_exception(this, this->pending_exception());
1367   this->clear_pending_exception();
1368   Handle threadObj(this, this->threadObj());
1369   assert(threadObj.not_null(), "Java thread object should be created");
1370 
1371   if (!destroy_vm) {
1372     if (uncaught_exception.not_null()) {
1373       EXCEPTION_MARK;
1374       // Call method Thread.dispatchUncaughtException().
1375       Klass* thread_klass = vmClasses::Thread_klass();
1376       JavaValue result(T_VOID);
1377       JavaCalls::call_virtual(&result,
1378                               threadObj, thread_klass,
1379                               vmSymbols::dispatchUncaughtException_name(),
1380                               vmSymbols::throwable_void_signature(),
1381                               uncaught_exception,
1382                               THREAD);
1383       if (HAS_PENDING_EXCEPTION) {
1384         ResourceMark rm(this);
1385         jio_fprintf(defaultStream::error_stream(),
1386                     "\nException: %s thrown from the UncaughtExceptionHandler"
1387                     " in thread \"%s\"\n",
1388                     pending_exception()->klass()->external_name(),
1389                     get_thread_name());
1390         CLEAR_PENDING_EXCEPTION;
1391       }
1392     }
1393 
1394     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1395     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1396     // is deprecated anyhow.
1397     if (!is_Compiler_thread()) {
1398       int count = 3;
1399       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1400         EXCEPTION_MARK;
1401         JavaValue result(T_VOID);
1402         Klass* thread_klass = vmClasses::Thread_klass();
1403         JavaCalls::call_virtual(&result,
1404                                 threadObj, thread_klass,
1405                                 vmSymbols::exit_method_name(),
1406                                 vmSymbols::void_method_signature(),
1407                                 THREAD);
1408         CLEAR_PENDING_EXCEPTION;
1409       }
1410     }
1411     // notify JVMTI
1412     if (JvmtiExport::should_post_thread_life()) {
1413       JvmtiExport::post_thread_end(this);
1414     }
1415 
1416     // The careful dance between thread suspension and exit is handled here.
1417     // Since we are in thread_in_vm state and suspension is done with handshakes,
1418     // we can just put in the exiting state and it will be correctly handled.
1419     set_terminated(_thread_exiting);
1420 
1421     ThreadService::current_thread_exiting(this, is_daemon(threadObj()));
1422   } else {
1423     assert(!is_terminated() && !is_exiting(), "must not be exiting");
1424     // before_exit() has already posted JVMTI THREAD_END events
1425   }
1426 
1427   if (log_is_enabled(Debug, os, thread, timer)) {
1428     _timer_exit_phase1.stop();
1429     _timer_exit_phase2.start();
1430   }
1431 
1432   // Capture daemon status before the thread is marked as terminated.
1433   bool daemon = is_daemon(threadObj());
1434 
1435   // Notify waiters on thread object. This has to be done after exit() is called
1436   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1437   // group should have the destroyed bit set before waiters are notified).
1438   ensure_join(this);
1439   assert(!this->has_pending_exception(), "ensure_join should have cleared");
1440 
1441   if (log_is_enabled(Debug, os, thread, timer)) {
1442     _timer_exit_phase2.stop();
1443     _timer_exit_phase3.start();
1444   }
1445   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1446   // held by this thread must be released. The spec does not distinguish
1447   // between JNI-acquired and regular Java monitors. We can only see
1448   // regular Java monitors here if monitor enter-exit matching is broken.
1449   //
1450   // ensure_join() ignores IllegalThreadStateExceptions, and so does
1451   // ObjectSynchronizer::release_monitors_owned_by_thread().
1452   if (exit_type == jni_detach) {
1453     // Sanity check even though JNI DetachCurrentThread() would have
1454     // returned JNI_ERR if there was a Java frame. JavaThread exit
1455     // should be done executing Java code by the time we get here.
1456     assert(!this->has_last_Java_frame(),
1457            "should not have a Java frame when detaching or exiting");
1458     ObjectSynchronizer::release_monitors_owned_by_thread(this);
1459     assert(!this->has_pending_exception(), "release_monitors should have cleared");
1460   }
1461 
1462   // These things needs to be done while we are still a Java Thread. Make sure that thread
1463   // is in a consistent state, in case GC happens
1464   JFR_ONLY(Jfr::on_thread_exit(this);)
1465 
1466   if (active_handles() != NULL) {
1467     JNIHandleBlock* block = active_handles();
1468     set_active_handles(NULL);
1469     JNIHandleBlock::release_block(block);
1470   }
1471 
1472   if (free_handle_block() != NULL) {
1473     JNIHandleBlock* block = free_handle_block();
1474     set_free_handle_block(NULL);
1475     JNIHandleBlock::release_block(block);
1476   }
1477 
1478   // These have to be removed while this is still a valid thread.
1479   _stack_overflow_state.remove_stack_guard_pages();
1480 
1481   if (UseTLAB) {
1482     tlab().retire();
1483   }
1484 
1485   if (JvmtiEnv::environments_might_exist()) {
1486     JvmtiExport::cleanup_thread(this);
1487   }
1488 
1489   // We need to cache the thread name for logging purposes below as once
1490   // we have called on_thread_detach this thread must not access any oops.
1491   char* thread_name = NULL;
1492   if (log_is_enabled(Debug, os, thread, timer)) {
1493     ResourceMark rm(this);
1494     thread_name = os::strdup(get_thread_name());
1495   }
1496 
1497   log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
1498     exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
1499     os::current_thread_id());
1500 
1501   if (log_is_enabled(Debug, os, thread, timer)) {
1502     _timer_exit_phase3.stop();
1503     _timer_exit_phase4.start();
1504   }
1505 
1506 #if INCLUDE_JVMCI
1507   if (JVMCICounterSize > 0) {
1508     if (jvmci_counters_include(this)) {
1509       for (int i = 0; i < JVMCICounterSize; i++) {
1510         _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1511       }
1512     }
1513   }
1514 #endif // INCLUDE_JVMCI
1515 
1516   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1517   Threads::remove(this, daemon);
1518 
1519   if (log_is_enabled(Debug, os, thread, timer)) {
1520     _timer_exit_phase4.stop();
1521     log_debug(os, thread, timer)("name='%s'"
1522                                  ", exit-phase1=" JLONG_FORMAT
1523                                  ", exit-phase2=" JLONG_FORMAT
1524                                  ", exit-phase3=" JLONG_FORMAT
1525                                  ", exit-phase4=" JLONG_FORMAT,
1526                                  thread_name,
1527                                  _timer_exit_phase1.milliseconds(),
1528                                  _timer_exit_phase2.milliseconds(),
1529                                  _timer_exit_phase3.milliseconds(),
1530                                  _timer_exit_phase4.milliseconds());
1531     os::free(thread_name);
1532   }
1533 }
1534 
1535 void JavaThread::cleanup_failed_attach_current_thread(bool is_daemon) {
1536   if (active_handles() != NULL) {
1537     JNIHandleBlock* block = active_handles();
1538     set_active_handles(NULL);
1539     JNIHandleBlock::release_block(block);
1540   }
1541 
1542   if (free_handle_block() != NULL) {
1543     JNIHandleBlock* block = free_handle_block();
1544     set_free_handle_block(NULL);
1545     JNIHandleBlock::release_block(block);
1546   }
1547 
1548   // These have to be removed while this is still a valid thread.
1549   _stack_overflow_state.remove_stack_guard_pages();
1550 
1551   if (UseTLAB) {
1552     tlab().retire();
1553   }
1554 
1555   Threads::remove(this, is_daemon);
1556   this->smr_delete();
1557 }
1558 
1559 JavaThread* JavaThread::active() {
1560   Thread* thread = Thread::current();
1561   if (thread->is_Java_thread()) {
1562     return thread->as_Java_thread();
1563   } else {
1564     assert(thread->is_VM_thread(), "this must be a vm thread");
1565     VM_Operation* op = ((VMThread*) thread)->vm_operation();
1566     JavaThread *ret = op == NULL ? NULL : op->calling_thread()->as_Java_thread();
1567     return ret;
1568   }
1569 }
1570 
1571 bool JavaThread::is_lock_owned(address adr) const {
1572   if (Thread::is_lock_owned(adr)) return true;
1573 
1574   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
1575     if (chunk->contains(adr)) return true;
1576   }
1577 
1578   return false;
1579 }
1580 
1581 oop JavaThread::exception_oop() const {
1582   return Atomic::load(&_exception_oop);
1583 }
1584 
1585 void JavaThread::set_exception_oop(oop o) {
1586   Atomic::store(&_exception_oop, o);
1587 }
1588 
1589 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
1590   chunk->set_next(monitor_chunks());
1591   set_monitor_chunks(chunk);
1592 }
1593 
1594 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
1595   guarantee(monitor_chunks() != NULL, "must be non empty");
1596   if (monitor_chunks() == chunk) {
1597     set_monitor_chunks(chunk->next());
1598   } else {
1599     MonitorChunk* prev = monitor_chunks();
1600     while (prev->next() != chunk) prev = prev->next();
1601     prev->set_next(chunk->next());
1602   }
1603 }
1604 
1605 
1606 // Asynchronous exceptions support
1607 //
1608 // Note: this function shouldn't block if it's called in
1609 // _thread_in_native_trans state (such as from
1610 // check_special_condition_for_native_trans()).
1611 void JavaThread::check_and_handle_async_exceptions() {
1612   if (has_last_Java_frame() && has_async_exception_condition()) {
1613     // If we are at a polling page safepoint (not a poll return)
1614     // then we must defer async exception because live registers
1615     // will be clobbered by the exception path. Poll return is
1616     // ok because the call we a returning from already collides
1617     // with exception handling registers and so there is no issue.
1618     // (The exception handling path kills call result registers but
1619     //  this is ok since the exception kills the result anyway).
1620 
1621     if (is_at_poll_safepoint()) {
1622       // if the code we are returning to has deoptimized we must defer
1623       // the exception otherwise live registers get clobbered on the
1624       // exception path before deoptimization is able to retrieve them.
1625       //
1626       RegisterMap map(this, false);
1627       frame caller_fr = last_frame().sender(&map);
1628       assert(caller_fr.is_compiled_frame(), "what?");
1629       if (caller_fr.is_deoptimized_frame()) {
1630         log_info(exceptions)("deferred async exception at compiled safepoint");
1631         return;
1632       }
1633     }
1634   }
1635 
1636   AsyncExceptionCondition condition = clear_async_exception_condition();
1637   if (condition == _no_async_condition) {
1638     // Conditions have changed since has_special_runtime_exit_condition()
1639     // was called:
1640     // - if we were here only because of an external suspend request,
1641     //   then that was taken care of above (or cancelled) so we are done
1642     // - if we were here because of another async request, then it has
1643     //   been cleared between the has_special_runtime_exit_condition()
1644     //   and now so again we are done
1645     return;
1646   }
1647 
1648   // Check for pending async. exception
1649   if (_pending_async_exception != NULL) {
1650     // Only overwrite an already pending exception, if it is not a threadDeath.
1651     if (!has_pending_exception() || !pending_exception()->is_a(vmClasses::ThreadDeath_klass())) {
1652 
1653       // We cannot call Exceptions::_throw(...) here because we cannot block
1654       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
1655 
1656       LogTarget(Info, exceptions) lt;
1657       if (lt.is_enabled()) {
1658         ResourceMark rm;
1659         LogStream ls(lt);
1660         ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
1661           if (has_last_Java_frame()) {
1662             frame f = last_frame();
1663            ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
1664           }
1665         ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
1666       }
1667       _pending_async_exception = NULL;
1668       // Clear condition from _suspend_flags since we have finished processing it.
1669       clear_suspend_flag(_has_async_exception);
1670     }
1671   }
1672 
1673   if (condition == _async_unsafe_access_error && !has_pending_exception()) {
1674     // We may be at method entry which requires we save the do-not-unlock flag.
1675     UnlockFlagSaver fs(this);
1676     switch (thread_state()) {
1677     case _thread_in_vm: {
1678       JavaThread* THREAD = this;
1679       Exceptions::throw_unsafe_access_internal_error(THREAD, __FILE__, __LINE__, "a fault occurred in an unsafe memory access operation");
1680       return;
1681     }
1682     case _thread_in_native: {
1683       ThreadInVMfromNative tiv(this);
1684       JavaThread* THREAD = this;
1685       Exceptions::throw_unsafe_access_internal_error(THREAD, __FILE__, __LINE__, "a fault occurred in an unsafe memory access operation");
1686       return;
1687     }
1688     case _thread_in_Java: {
1689       ThreadInVMfromJava tiv(this);
1690       JavaThread* THREAD = this;
1691       Exceptions::throw_unsafe_access_internal_error(THREAD, __FILE__, __LINE__, "a fault occurred in a recent unsafe memory access operation in compiled Java code");
1692       return;
1693     }
1694     default:
1695       ShouldNotReachHere();
1696     }
1697   }
1698 
1699   assert(has_pending_exception(), "must have handled the async condition if no exception");
1700 }
1701 
1702 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
1703 
1704   if (is_obj_deopt_suspend()) {
1705     frame_anchor()->make_walkable();
1706     wait_for_object_deoptimization();
1707   }
1708 
1709   // We might be here for reasons in addition to the self-suspend request
1710   // so check for other async requests.
1711   if (check_asyncs) {
1712     check_and_handle_async_exceptions();
1713   }
1714 
1715   JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
1716 }
1717 
1718 class InstallAsyncExceptionClosure : public HandshakeClosure {
1719   Handle _throwable; // The Throwable thrown at the target Thread
1720 public:
1721   InstallAsyncExceptionClosure(Handle throwable) : HandshakeClosure("InstallAsyncException"), _throwable(throwable) {}
1722 
1723   void do_thread(Thread* thr) {
1724     JavaThread* target = thr->as_Java_thread();
1725     // Note that this now allows multiple ThreadDeath exceptions to be
1726     // thrown at a thread.
1727     // The target thread has run and has not exited yet.
1728     target->send_thread_stop(_throwable());
1729   }
1730 };
1731 
1732 void JavaThread::send_async_exception(oop java_thread, oop java_throwable) {
1733   Handle throwable(Thread::current(), java_throwable);
1734   JavaThread* target = java_lang_Thread::thread(java_thread);
1735   InstallAsyncExceptionClosure vm_stop(throwable);
1736   Handshake::execute(&vm_stop, target);
1737 }
1738 
1739 void JavaThread::send_thread_stop(oop java_throwable)  {
1740   ResourceMark rm;
1741   assert(is_handshake_safe_for(Thread::current()),
1742          "should be self or handshakee");
1743 
1744   // Do not throw asynchronous exceptions against the compiler thread
1745   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
1746   if (!can_call_java()) return;
1747 
1748   {
1749     // Actually throw the Throwable against the target Thread - however
1750     // only if there is no thread death exception installed already.
1751     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(vmClasses::ThreadDeath_klass())) {
1752       // If the topmost frame is a runtime stub, then we are calling into
1753       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
1754       // must deoptimize the caller before continuing, as the compiled  exception handler table
1755       // may not be valid
1756       if (has_last_Java_frame()) {
1757         frame f = last_frame();
1758         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
1759           RegisterMap reg_map(this, false);
1760           frame compiled_frame = f.sender(&reg_map);
1761           if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
1762             Deoptimization::deoptimize(this, compiled_frame);
1763           }
1764         }
1765       }
1766 
1767       // Set async. pending exception in thread.
1768       set_pending_async_exception(java_throwable);
1769 
1770       if (log_is_enabled(Info, exceptions)) {
1771          ResourceMark rm;
1772         log_info(exceptions)("Pending Async. exception installed of type: %s",
1773                              InstanceKlass::cast(_pending_async_exception->klass())->external_name());
1774       }
1775       // for AbortVMOnException flag
1776       Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
1777     }
1778   }
1779 
1780 
1781   // Interrupt thread so it will wake up from a potential wait()/sleep()/park()
1782   java_lang_Thread::set_interrupted(threadObj(), true);
1783   this->interrupt();
1784 }
1785 
1786 
1787 // External suspension mechanism.
1788 //
1789 // Guarantees on return (for a valid target thread):
1790 //   - Target thread will not execute any new bytecode.
1791 //   - Target thread will not enter any new monitors.
1792 //
1793 bool JavaThread::java_suspend() {
1794   ThreadsListHandle tlh;
1795   if (!tlh.includes(this)) {
1796     log_trace(thread, suspend)("JavaThread:" INTPTR_FORMAT " not on ThreadsList, no suspension", p2i(this));
1797     return false;
1798   }
1799   return this->handshake_state()->suspend();
1800 }
1801 
1802 bool JavaThread::java_resume() {
1803   ThreadsListHandle tlh;
1804   if (!tlh.includes(this)) {
1805     log_trace(thread, suspend)("JavaThread:" INTPTR_FORMAT " not on ThreadsList, nothing to resume", p2i(this));
1806     return false;
1807   }
1808   return this->handshake_state()->resume();
1809 }
1810 
1811 // Wait for another thread to perform object reallocation and relocking on behalf of
1812 // this thread.
1813 // Raw thread state transition to _thread_blocked and back again to the original
1814 // state before returning are performed. The current thread is required to
1815 // change to _thread_blocked in order to be seen to be safepoint/handshake safe
1816 // whilst suspended and only after becoming handshake safe, the other thread can
1817 // complete the handshake used to synchronize with this thread and then perform
1818 // the reallocation and relocking. We cannot use the thread state transition
1819 // helpers because we arrive here in various states and also because the helpers
1820 // indirectly call this method.  After leaving _thread_blocked we have to check
1821 // for safepoint/handshake, except if _thread_in_native. The thread is safe
1822 // without blocking then. Allowed states are enumerated in
1823 // SafepointSynchronize::block(). See also EscapeBarrier::sync_and_suspend_*()
1824 
1825 void JavaThread::wait_for_object_deoptimization() {
1826   assert(!has_last_Java_frame() || frame_anchor()->walkable(), "should have walkable stack");
1827   assert(this == Thread::current(), "invariant");
1828   JavaThreadState state = thread_state();
1829 
1830   bool spin_wait = os::is_MP();
1831   do {
1832     set_thread_state(_thread_blocked);
1833     // Wait for object deoptimization if requested.
1834     if (spin_wait) {
1835       // A single deoptimization is typically very short. Microbenchmarks
1836       // showed 5% better performance when spinning.
1837       const uint spin_limit = 10 * SpinYield::default_spin_limit;
1838       SpinYield spin(spin_limit);
1839       for (uint i = 0; is_obj_deopt_suspend() && i < spin_limit; i++) {
1840         spin.wait();
1841       }
1842       // Spin just once
1843       spin_wait = false;
1844     } else {
1845       MonitorLocker ml(this, EscapeBarrier_lock, Monitor::_no_safepoint_check_flag);
1846       if (is_obj_deopt_suspend()) {
1847         ml.wait();
1848       }
1849     }
1850     // The current thread could have been suspended again. We have to check for
1851     // suspend after restoring the saved state. Without this the current thread
1852     // might return to _thread_in_Java and execute bytecode.
1853     set_thread_state_fence(state);
1854 
1855     if (state != _thread_in_native) {
1856       SafepointMechanism::process_if_requested(this);
1857     }
1858     // A handshake for obj. deoptimization suspend could have been processed so
1859     // we must check after processing.
1860   } while (is_obj_deopt_suspend());
1861 }
1862 
1863 #ifdef ASSERT
1864 // Verify the JavaThread has not yet been published in the Threads::list, and
1865 // hence doesn't need protection from concurrent access at this stage.
1866 void JavaThread::verify_not_published() {
1867   // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
1868   // since an unpublished JavaThread doesn't participate in the
1869   // Thread-SMR protocol for keeping a ThreadsList alive.
1870   assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
1871 }
1872 #endif
1873 
1874 // Slow path when the native==>Java barriers detect a safepoint/handshake is
1875 // pending, when _suspend_flags is non-zero or when we need to process a stack
1876 // watermark. Also check for pending async exceptions (except unsafe access error).
1877 // Note only the native==>Java barriers can call this function when thread state
1878 // is _thread_in_native_trans.
1879 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
1880   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
1881   assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "Unwalkable stack in native->Java transition");
1882 
1883   // Enable WXWrite: called directly from interpreter native wrapper.
1884   MACOS_AARCH64_ONLY(ThreadWXEnable wx(WXWrite, thread));
1885 
1886   SafepointMechanism::process_if_requested_with_exit_check(thread, false /* check asyncs */);
1887 
1888   // After returning from native, it could be that the stack frames are not
1889   // yet safe to use. We catch such situations in the subsequent stack watermark
1890   // barrier, which will trap unsafe stack frames.
1891   StackWatermarkSet::before_unwind(thread);
1892 
1893   if (thread->has_async_exception_condition(false /* check unsafe access error */)) {
1894     // We are in _thread_in_native_trans state, don't handle unsafe
1895     // access error since that may block.
1896     thread->check_and_handle_async_exceptions();
1897   }
1898 }
1899 
1900 #ifndef PRODUCT
1901 // Deoptimization
1902 // Function for testing deoptimization
1903 void JavaThread::deoptimize() {
1904   StackFrameStream fst(this, false /* update */, true /* process_frames */);
1905   bool deopt = false;           // Dump stack only if a deopt actually happens.
1906   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
1907   // Iterate over all frames in the thread and deoptimize
1908   for (; !fst.is_done(); fst.next()) {
1909     if (fst.current()->can_be_deoptimized()) {
1910 
1911       if (only_at) {
1912         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
1913         // consists of comma or carriage return separated numbers so
1914         // search for the current bci in that string.
1915         address pc = fst.current()->pc();
1916         nmethod* nm =  (nmethod*) fst.current()->cb();
1917         ScopeDesc* sd = nm->scope_desc_at(pc);
1918         char buffer[8];
1919         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
1920         size_t len = strlen(buffer);
1921         const char * found = strstr(DeoptimizeOnlyAt, buffer);
1922         while (found != NULL) {
1923           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
1924               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
1925             // Check that the bci found is bracketed by terminators.
1926             break;
1927           }
1928           found = strstr(found + 1, buffer);
1929         }
1930         if (!found) {
1931           continue;
1932         }
1933       }
1934 
1935       if (DebugDeoptimization && !deopt) {
1936         deopt = true; // One-time only print before deopt
1937         tty->print_cr("[BEFORE Deoptimization]");
1938         trace_frames();
1939         trace_stack();
1940       }
1941       Deoptimization::deoptimize(this, *fst.current());
1942     }
1943   }
1944 
1945   if (DebugDeoptimization && deopt) {
1946     tty->print_cr("[AFTER Deoptimization]");
1947     trace_frames();
1948   }
1949 }
1950 
1951 
1952 // Make zombies
1953 void JavaThread::make_zombies() {
1954   for (StackFrameStream fst(this, true /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
1955     if (fst.current()->can_be_deoptimized()) {
1956       // it is a Java nmethod
1957       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
1958       nm->make_not_entrant();
1959     }
1960   }
1961 }
1962 #endif // PRODUCT
1963 
1964 
1965 void JavaThread::deoptimize_marked_methods() {
1966   if (!has_last_Java_frame()) return;
1967   StackFrameStream fst(this, false /* update */, true /* process_frames */);
1968   for (; !fst.is_done(); fst.next()) {
1969     if (fst.current()->should_be_deoptimized()) {
1970       Deoptimization::deoptimize(this, *fst.current());
1971     }
1972   }
1973 }
1974 
1975 #ifdef ASSERT
1976 void JavaThread::verify_frame_info() {
1977   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
1978          (has_last_Java_frame() && java_call_counter() > 0),
1979          "unexpected frame info: has_last_frame=%s, java_call_counter=%d",
1980          has_last_Java_frame() ? "true" : "false", java_call_counter());
1981 }
1982 #endif
1983 
1984 void JavaThread::oops_do_no_frames(OopClosure* f, CodeBlobClosure* cf) {
1985   // Verify that the deferred card marks have been flushed.
1986   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
1987 
1988   // Traverse the GCHandles
1989   Thread::oops_do_no_frames(f, cf);
1990 
1991   DEBUG_ONLY(verify_frame_info();)
1992 
1993   if (has_last_Java_frame()) {
1994     // Traverse the monitor chunks
1995     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
1996       chunk->oops_do(f);
1997     }
1998   }
1999 
2000   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2001   // If we have deferred set_locals there might be oops waiting to be
2002   // written
2003   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = JvmtiDeferredUpdates::deferred_locals(this);
2004   if (list != NULL) {
2005     for (int i = 0; i < list->length(); i++) {
2006       list->at(i)->oops_do(f);
2007     }
2008   }
2009 
2010   // Traverse instance variables at the end since the GC may be moving things
2011   // around using this function
2012   f->do_oop((oop*) &_vm_result);
2013   f->do_oop((oop*) &_exception_oop);
2014   f->do_oop((oop*) &_pending_async_exception);
2015 #if INCLUDE_JVMCI
2016   f->do_oop((oop*) &_jvmci_reserved_oop0);
2017 #endif
2018 
2019   if (jvmti_thread_state() != NULL) {
2020     jvmti_thread_state()->oops_do(f, cf);
2021   }
2022 }
2023 
2024 void JavaThread::oops_do_frames(OopClosure* f, CodeBlobClosure* cf) {
2025   if (!has_last_Java_frame()) {
2026     return;
2027   }
2028   // Finish any pending lazy GC activity for the frames
2029   StackWatermarkSet::finish_processing(this, NULL /* context */, StackWatermarkKind::gc);
2030   // Traverse the execution stack
2031   for (StackFrameStream fst(this, true /* update */, false /* process_frames */); !fst.is_done(); fst.next()) {
2032     fst.current()->oops_do(f, cf, fst.register_map());
2033   }
2034 }
2035 
2036 #ifdef ASSERT
2037 void JavaThread::verify_states_for_handshake() {
2038   // This checks that the thread has a correct frame state during a handshake.
2039   verify_frame_info();
2040 }
2041 #endif
2042 
2043 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2044   DEBUG_ONLY(verify_frame_info();)
2045 
2046   if (has_last_Java_frame()) {
2047     // Traverse the execution stack
2048     for (StackFrameStream fst(this, true /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
2049       fst.current()->nmethods_do(cf);
2050     }
2051   }
2052 
2053   if (jvmti_thread_state() != NULL) {
2054     jvmti_thread_state()->nmethods_do(cf);
2055   }
2056 }
2057 
2058 void JavaThread::metadata_do(MetadataClosure* f) {
2059   if (has_last_Java_frame()) {
2060     // Traverse the execution stack to call f() on the methods in the stack
2061     for (StackFrameStream fst(this, true /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
2062       fst.current()->metadata_do(f);
2063     }
2064   } else if (is_Compiler_thread()) {
2065     // need to walk ciMetadata in current compile tasks to keep alive.
2066     CompilerThread* ct = (CompilerThread*)this;
2067     if (ct->env() != NULL) {
2068       ct->env()->metadata_do(f);
2069     }
2070     CompileTask* task = ct->task();
2071     if (task != NULL) {
2072       task->metadata_do(f);
2073     }
2074   }
2075 }
2076 
2077 // Printing
2078 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2079   switch (_thread_state) {
2080   case _thread_uninitialized:     return "_thread_uninitialized";
2081   case _thread_new:               return "_thread_new";
2082   case _thread_new_trans:         return "_thread_new_trans";
2083   case _thread_in_native:         return "_thread_in_native";
2084   case _thread_in_native_trans:   return "_thread_in_native_trans";
2085   case _thread_in_vm:             return "_thread_in_vm";
2086   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
2087   case _thread_in_Java:           return "_thread_in_Java";
2088   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
2089   case _thread_blocked:           return "_thread_blocked";
2090   case _thread_blocked_trans:     return "_thread_blocked_trans";
2091   default:                        return "unknown thread state";
2092   }
2093 }
2094 
2095 #ifndef PRODUCT
2096 void JavaThread::print_thread_state_on(outputStream *st) const {
2097   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
2098 };
2099 #endif // PRODUCT
2100 
2101 // Called by Threads::print() for VM_PrintThreads operation
2102 void JavaThread::print_on(outputStream *st, bool print_extended_info) const {
2103   st->print_raw("\"");
2104   st->print_raw(get_thread_name());
2105   st->print_raw("\" ");
2106   oop thread_oop = threadObj();
2107   if (thread_oop != NULL) {
2108     st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2109     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
2110     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2111   }
2112   Thread::print_on(st, print_extended_info);
2113   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2114   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2115   if (thread_oop != NULL) {
2116     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2117   }
2118 #ifndef PRODUCT
2119   _safepoint_state->print_on(st);
2120 #endif // PRODUCT
2121   if (is_Compiler_thread()) {
2122     CompileTask *task = ((CompilerThread*)this)->task();
2123     if (task != NULL) {
2124       st->print("   Compiling: ");
2125       task->print(st, NULL, true, false);
2126     } else {
2127       st->print("   No compile task");
2128     }
2129     st->cr();
2130   }
2131 }
2132 
2133 void JavaThread::print() const { print_on(tty); }
2134 
2135 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2136   st->print("%s", get_thread_name_string(buf, buflen));
2137 }
2138 
2139 // Called by fatal error handler. The difference between this and
2140 // JavaThread::print() is that we can't grab lock or allocate memory.
2141 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2142   st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2143   oop thread_obj = threadObj();
2144   if (thread_obj != NULL) {
2145     if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2146   }
2147   st->print(" [");
2148   st->print("%s", _get_thread_state_name(_thread_state));
2149   if (osthread()) {
2150     st->print(", id=%d", osthread()->thread_id());
2151   }
2152   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2153             p2i(stack_end()), p2i(stack_base()));
2154   st->print("]");
2155 
2156   ThreadsSMRSupport::print_info_on(this, st);
2157   return;
2158 }
2159 
2160 
2161 // Verification
2162 
2163 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2164   // ignore if there is no stack
2165   if (!has_last_Java_frame()) return;
2166   // traverse the stack frames. Starts from top frame.
2167   for (StackFrameStream fst(this, true /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
2168     frame* fr = fst.current();
2169     f(fr, fst.register_map());
2170   }
2171 }
2172 
2173 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2174 
2175 void JavaThread::verify() {
2176   // Verify oops in the thread.
2177   oops_do(&VerifyOopClosure::verify_oop, NULL);
2178 
2179   // Verify the stack frames.
2180   frames_do(frame_verify);
2181 }
2182 
2183 // CR 6300358 (sub-CR 2137150)
2184 // Most callers of this method assume that it can't return NULL but a
2185 // thread may not have a name whilst it is in the process of attaching to
2186 // the VM - see CR 6412693, and there are places where a JavaThread can be
2187 // seen prior to having its threadObj set (e.g., JNI attaching threads and
2188 // if vm exit occurs during initialization). These cases can all be accounted
2189 // for such that this method never returns NULL.
2190 const char* JavaThread::get_thread_name() const {
2191   if (Thread::is_JavaThread_protected(this)) {
2192     // The target JavaThread is protected so get_thread_name_string() is safe:
2193     return get_thread_name_string();
2194   }
2195 
2196   // The target JavaThread is not protected so we return the default:
2197   return Thread::name();
2198 }
2199 
2200 // Returns a non-NULL representation of this thread's name, or a suitable
2201 // descriptive string if there is no set name.
2202 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2203   const char* name_str;
2204   oop thread_obj = threadObj();
2205   if (thread_obj != NULL) {
2206     oop name = java_lang_Thread::name(thread_obj);
2207     if (name != NULL) {
2208       if (buf == NULL) {
2209         name_str = java_lang_String::as_utf8_string(name);
2210       } else {
2211         name_str = java_lang_String::as_utf8_string(name, buf, buflen);
2212       }
2213     } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
2214       name_str = "<no-name - thread is attaching>";
2215     } else {
2216       name_str = Thread::name();
2217     }
2218   } else {
2219     name_str = Thread::name();
2220   }
2221   assert(name_str != NULL, "unexpected NULL thread name");
2222   return name_str;
2223 }
2224 
2225 // Helper to extract the name from the thread oop for logging.
2226 const char* JavaThread::name_for(oop thread_obj) {
2227   assert(thread_obj != NULL, "precondition");
2228   oop name = java_lang_Thread::name(thread_obj);
2229   const char* name_str;
2230   if (name != NULL) {
2231     name_str = java_lang_String::as_utf8_string(name);
2232   } else {
2233     name_str = "<un-named>";
2234   }
2235   return name_str;
2236 }
2237 
2238 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
2239 
2240   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
2241   assert(NoPriority <= prio && prio <= MaxPriority, "sanity check");
2242   // Link Java Thread object <-> C++ Thread
2243 
2244   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
2245   // and put it into a new Handle.  The Handle "thread_oop" can then
2246   // be used to pass the C++ thread object to other methods.
2247 
2248   // Set the Java level thread object (jthread) field of the
2249   // new thread (a JavaThread *) to C++ thread object using the
2250   // "thread_oop" handle.
2251 
2252   // Set the thread field (a JavaThread *) of the
2253   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
2254 
2255   Handle thread_oop(Thread::current(),
2256                     JNIHandles::resolve_non_null(jni_thread));
2257   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
2258          "must be initialized");
2259   set_threadObj(thread_oop());
2260   java_lang_Thread::set_thread(thread_oop(), this);
2261 
2262   if (prio == NoPriority) {
2263     prio = java_lang_Thread::priority(thread_oop());
2264     assert(prio != NoPriority, "A valid priority should be present");
2265   }
2266 
2267   // Push the Java priority down to the native thread; needs Threads_lock
2268   Thread::set_priority(this, prio);
2269 
2270   // Add the new thread to the Threads list and set it in motion.
2271   // We must have threads lock in order to call Threads::add.
2272   // It is crucial that we do not block before the thread is
2273   // added to the Threads list for if a GC happens, then the java_thread oop
2274   // will not be visited by GC.
2275   Threads::add(this);
2276 }
2277 
2278 oop JavaThread::current_park_blocker() {
2279   // Support for JSR-166 locks
2280   oop thread_oop = threadObj();
2281   if (thread_oop != NULL) {
2282     return java_lang_Thread::park_blocker(thread_oop);
2283   }
2284   return NULL;
2285 }
2286 
2287 
2288 void JavaThread::print_stack_on(outputStream* st) {
2289   if (!has_last_Java_frame()) return;
2290 
2291   Thread* current_thread = Thread::current();
2292   ResourceMark rm(current_thread);
2293   HandleMark hm(current_thread);
2294 
2295   RegisterMap reg_map(this);
2296   vframe* start_vf = last_java_vframe(&reg_map);
2297   int count = 0;
2298   for (vframe* f = start_vf; f != NULL; f = f->sender()) {
2299     if (f->is_java_frame()) {
2300       javaVFrame* jvf = javaVFrame::cast(f);
2301       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
2302 
2303       // Print out lock information
2304       if (JavaMonitorsInStackTrace) {
2305         jvf->print_lock_info_on(st, count);
2306       }
2307     } else {
2308       // Ignore non-Java frames
2309     }
2310 
2311     // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
2312     count++;
2313     if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
2314   }
2315 }
2316 
2317 
2318 // JVMTI PopFrame support
2319 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
2320   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
2321   if (in_bytes(size_in_bytes) != 0) {
2322     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
2323     _popframe_preserved_args_size = in_bytes(size_in_bytes);
2324     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
2325   }
2326 }
2327 
2328 void* JavaThread::popframe_preserved_args() {
2329   return _popframe_preserved_args;
2330 }
2331 
2332 ByteSize JavaThread::popframe_preserved_args_size() {
2333   return in_ByteSize(_popframe_preserved_args_size);
2334 }
2335 
2336 WordSize JavaThread::popframe_preserved_args_size_in_words() {
2337   int sz = in_bytes(popframe_preserved_args_size());
2338   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
2339   return in_WordSize(sz / wordSize);
2340 }
2341 
2342 void JavaThread::popframe_free_preserved_args() {
2343   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
2344   FREE_C_HEAP_ARRAY(char, (char*)_popframe_preserved_args);
2345   _popframe_preserved_args = NULL;
2346   _popframe_preserved_args_size = 0;
2347 }
2348 
2349 #ifndef PRODUCT
2350 
2351 void JavaThread::trace_frames() {
2352   tty->print_cr("[Describe stack]");
2353   int frame_no = 1;
2354   for (StackFrameStream fst(this, true /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
2355     tty->print("  %d. ", frame_no++);
2356     fst.current()->print_value_on(tty, this);
2357     tty->cr();
2358   }
2359 }
2360 
2361 class PrintAndVerifyOopClosure: public OopClosure {
2362  protected:
2363   template <class T> inline void do_oop_work(T* p) {
2364     oop obj = RawAccess<>::oop_load(p);
2365     if (obj == NULL) return;
2366     tty->print(INTPTR_FORMAT ": ", p2i(p));
2367     if (oopDesc::is_oop_or_null(obj)) {
2368       if (obj->is_objArray()) {
2369         tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
2370       } else {
2371         obj->print();
2372       }
2373     } else {
2374       tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
2375     }
2376     tty->cr();
2377   }
2378  public:
2379   virtual void do_oop(oop* p) { do_oop_work(p); }
2380   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
2381 };
2382 
2383 #ifdef ASSERT
2384 // Print or validate the layout of stack frames
2385 void JavaThread::print_frame_layout(int depth, bool validate_only) {
2386   ResourceMark rm;
2387   PreserveExceptionMark pm(this);
2388   FrameValues values;
2389   int frame_no = 0;
2390   for (StackFrameStream fst(this, false /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
2391     fst.current()->describe(values, ++frame_no);
2392     if (depth == frame_no) break;
2393   }
2394   if (validate_only) {
2395     values.validate();
2396   } else {
2397     tty->print_cr("[Describe stack layout]");
2398     values.print(this);
2399   }
2400 }
2401 #endif
2402 
2403 void JavaThread::trace_stack_from(vframe* start_vf) {
2404   ResourceMark rm;
2405   int vframe_no = 1;
2406   for (vframe* f = start_vf; f; f = f->sender()) {
2407     if (f->is_java_frame()) {
2408       javaVFrame::cast(f)->print_activation(vframe_no++);
2409     } else {
2410       f->print();
2411     }
2412     if (vframe_no > StackPrintLimit) {
2413       tty->print_cr("...<more frames>...");
2414       return;
2415     }
2416   }
2417 }
2418 
2419 
2420 void JavaThread::trace_stack() {
2421   if (!has_last_Java_frame()) return;
2422   Thread* current_thread = Thread::current();
2423   ResourceMark rm(current_thread);
2424   HandleMark hm(current_thread);
2425   RegisterMap reg_map(this);
2426   trace_stack_from(last_java_vframe(&reg_map));
2427 }
2428 
2429 
2430 #endif // PRODUCT
2431 
2432 
2433 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
2434   assert(reg_map != NULL, "a map must be given");
2435   frame f = last_frame();
2436   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
2437     if (vf->is_java_frame()) return javaVFrame::cast(vf);
2438   }
2439   return NULL;
2440 }
2441 
2442 
2443 Klass* JavaThread::security_get_caller_class(int depth) {
2444   vframeStream vfst(this);
2445   vfst.security_get_caller_frame(depth);
2446   if (!vfst.at_end()) {
2447     return vfst.method()->method_holder();
2448   }
2449   return NULL;
2450 }
2451 
2452 // java.lang.Thread.sleep support
2453 // Returns true if sleep time elapsed as expected, and false
2454 // if the thread was interrupted.
2455 bool JavaThread::sleep(jlong millis) {
2456   assert(this == Thread::current(),  "thread consistency check");
2457 
2458   ParkEvent * const slp = this->_SleepEvent;
2459   // Because there can be races with thread interruption sending an unpark()
2460   // to the event, we explicitly reset it here to avoid an immediate return.
2461   // The actual interrupt state will be checked before we park().
2462   slp->reset();
2463   // Thread interruption establishes a happens-before ordering in the
2464   // Java Memory Model, so we need to ensure we synchronize with the
2465   // interrupt state.
2466   OrderAccess::fence();
2467 
2468   jlong prevtime = os::javaTimeNanos();
2469 
2470   for (;;) {
2471     // interruption has precedence over timing out
2472     if (this->is_interrupted(true)) {
2473       return false;
2474     }
2475 
2476     if (millis <= 0) {
2477       return true;
2478     }
2479 
2480     {
2481       ThreadBlockInVM tbivm(this);
2482       OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
2483       slp->park(millis);
2484     }
2485 
2486     // Update elapsed time tracking
2487     jlong newtime = os::javaTimeNanos();
2488     if (newtime - prevtime < 0) {
2489       // time moving backwards, should only happen if no monotonic clock
2490       // not a guarantee() because JVM should not abort on kernel/glibc bugs
2491       assert(false,
2492              "unexpected time moving backwards detected in JavaThread::sleep()");
2493     } else {
2494       millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC;
2495     }
2496     prevtime = newtime;
2497   }
2498 }
2499 
2500 
2501 // ======= Threads ========
2502 
2503 // The Threads class links together all active threads, and provides
2504 // operations over all threads. It is protected by the Threads_lock,
2505 // which is also used in other global contexts like safepointing.
2506 // ThreadsListHandles are used to safely perform operations on one
2507 // or more threads without the risk of the thread exiting during the
2508 // operation.
2509 //
2510 // Note: The Threads_lock is currently more widely used than we
2511 // would like. We are actively migrating Threads_lock uses to other
2512 // mechanisms in order to reduce Threads_lock contention.
2513 
2514 int         Threads::_number_of_threads = 0;
2515 int         Threads::_number_of_non_daemon_threads = 0;
2516 int         Threads::_return_code = 0;
2517 uintx       Threads::_thread_claim_token = 1; // Never zero.
2518 size_t      JavaThread::_stack_size_at_create = 0;
2519 
2520 #ifdef ASSERT
2521 bool        Threads::_vm_complete = false;
2522 #endif
2523 
2524 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
2525   Prefetch::read((void*)addr, prefetch_interval);
2526   return *addr;
2527 }
2528 
2529 // Possibly the ugliest for loop the world has seen. C++ does not allow
2530 // multiple types in the declaration section of the for loop. In this case
2531 // we are only dealing with pointers and hence can cast them. It looks ugly
2532 // but macros are ugly and therefore it's fine to make things absurdly ugly.
2533 #define DO_JAVA_THREADS(LIST, X)                                                                                          \
2534     for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes,                           \
2535              *MACRO_list = (JavaThread*)(LIST),                                                                           \
2536              **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(),  \
2537              **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(),                                     \
2538              *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval);                 \
2539          MACRO_current_p != MACRO_end;                                                                                    \
2540          MACRO_current_p++,                                                                                               \
2541              X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
2542 
2543 // All JavaThreads
2544 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
2545 
2546 // All NonJavaThreads (i.e., every non-JavaThread in the system).
2547 void Threads::non_java_threads_do(ThreadClosure* tc) {
2548   NoSafepointVerifier nsv;
2549   for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) {
2550     tc->do_thread(njti.current());
2551   }
2552 }
2553 
2554 // All JavaThreads
2555 void Threads::java_threads_do(ThreadClosure* tc) {
2556   assert_locked_or_safepoint(Threads_lock);
2557   // ALL_JAVA_THREADS iterates through all JavaThreads.
2558   ALL_JAVA_THREADS(p) {
2559     tc->do_thread(p);
2560   }
2561 }
2562 
2563 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) {
2564   assert_locked_or_safepoint(Threads_lock);
2565   java_threads_do(tc);
2566   tc->do_thread(VMThread::vm_thread());
2567 }
2568 
2569 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
2570 void Threads::threads_do(ThreadClosure* tc) {
2571   assert_locked_or_safepoint(Threads_lock);
2572   java_threads_do(tc);
2573   non_java_threads_do(tc);
2574 }
2575 
2576 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
2577   uintx claim_token = Threads::thread_claim_token();
2578   ALL_JAVA_THREADS(p) {
2579     if (p->claim_threads_do(is_par, claim_token)) {
2580       tc->do_thread(p);
2581     }
2582   }
2583   VMThread* vmt = VMThread::vm_thread();
2584   if (vmt->claim_threads_do(is_par, claim_token)) {
2585     tc->do_thread(vmt);
2586   }
2587 }
2588 
2589 // The system initialization in the library has three phases.
2590 //
2591 // Phase 1: java.lang.System class initialization
2592 //     java.lang.System is a primordial class loaded and initialized
2593 //     by the VM early during startup.  java.lang.System.<clinit>
2594 //     only does registerNatives and keeps the rest of the class
2595 //     initialization work later until thread initialization completes.
2596 //
2597 //     System.initPhase1 initializes the system properties, the static
2598 //     fields in, out, and err. Set up java signal handlers, OS-specific
2599 //     system settings, and thread group of the main thread.
2600 static void call_initPhase1(TRAPS) {
2601   Klass* klass = vmClasses::System_klass();
2602   JavaValue result(T_VOID);
2603   JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
2604                                          vmSymbols::void_method_signature(), CHECK);
2605 }
2606 
2607 // Phase 2. Module system initialization
2608 //     This will initialize the module system.  Only java.base classes
2609 //     can be loaded until phase 2 completes.
2610 //
2611 //     Call System.initPhase2 after the compiler initialization and jsr292
2612 //     classes get initialized because module initialization runs a lot of java
2613 //     code, that for performance reasons, should be compiled.  Also, this will
2614 //     enable the startup code to use lambda and other language features in this
2615 //     phase and onward.
2616 //
2617 //     After phase 2, The VM will begin search classes from -Xbootclasspath/a.
2618 static void call_initPhase2(TRAPS) {
2619   TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
2620 
2621   Klass* klass = vmClasses::System_klass();
2622 
2623   JavaValue result(T_INT);
2624   JavaCallArguments args;
2625   args.push_int(DisplayVMOutputToStderr);
2626   args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
2627   JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
2628                                          vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
2629   if (result.get_jint() != JNI_OK) {
2630     vm_exit_during_initialization(); // no message or exception
2631   }
2632 
2633   universe_post_module_init();
2634 }
2635 
2636 // Phase 3. final setup - set security manager, system class loader and TCCL
2637 //
2638 //     This will instantiate and set the security manager, set the system class
2639 //     loader as well as the thread context class loader.  The security manager
2640 //     and system class loader may be a custom class loaded from -Xbootclasspath/a,
2641 //     other modules or the application's classpath.
2642 static void call_initPhase3(TRAPS) {
2643   Klass* klass = vmClasses::System_klass();
2644   JavaValue result(T_VOID);
2645   JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
2646                                          vmSymbols::void_method_signature(), CHECK);
2647 }
2648 
2649 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
2650   TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
2651 
2652   if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
2653     create_vm_init_libraries();
2654   }
2655 
2656   initialize_class(vmSymbols::java_lang_String(), CHECK);
2657 
2658   // Inject CompactStrings value after the static initializers for String ran.
2659   java_lang_String::set_compact_strings(CompactStrings);
2660 
2661   // Initialize java_lang.System (needed before creating the thread)
2662   initialize_class(vmSymbols::java_lang_System(), CHECK);
2663   // The VM creates & returns objects of this class. Make sure it's initialized.
2664   initialize_class(vmSymbols::java_lang_Class(), CHECK);
2665   initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
2666   Handle thread_group = create_initial_thread_group(CHECK);
2667   Universe::set_main_thread_group(thread_group());
2668   initialize_class(vmSymbols::java_lang_Thread(), CHECK);
2669   create_initial_thread(thread_group, main_thread, CHECK);
2670 
2671   // The VM creates objects of this class.
2672   initialize_class(vmSymbols::java_lang_Module(), CHECK);
2673 
2674 #ifdef ASSERT
2675   InstanceKlass *k = vmClasses::UnsafeConstants_klass();
2676   assert(k->is_not_initialized(), "UnsafeConstants should not already be initialized");
2677 #endif
2678 
2679   // initialize the hardware-specific constants needed by Unsafe
2680   initialize_class(vmSymbols::jdk_internal_misc_UnsafeConstants(), CHECK);
2681   jdk_internal_misc_UnsafeConstants::set_unsafe_constants();
2682 
2683   // The VM preresolves methods to these classes. Make sure that they get initialized
2684   initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
2685   initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
2686 
2687   // Phase 1 of the system initialization in the library, java.lang.System class initialization
2688   call_initPhase1(CHECK);
2689 
2690   // Get the Java runtime name, version, and vendor info after java.lang.System is initialized.
2691   // Some values are actually configure-time constants but some can be set via the jlink tool and
2692   // so must be read dynamically. We treat them all the same.
2693   InstanceKlass* ik = SystemDictionary::find_instance_klass(vmSymbols::java_lang_VersionProps(),
2694                                                             Handle(), Handle());
2695   {
2696     ResourceMark rm(main_thread);
2697     JDK_Version::set_java_version(get_java_version_info(ik, vmSymbols::java_version_name()));
2698 
2699     JDK_Version::set_runtime_name(get_java_version_info(ik, vmSymbols::java_runtime_name_name()));
2700 
2701     JDK_Version::set_runtime_version(get_java_version_info(ik, vmSymbols::java_runtime_version_name()));
2702 
2703     JDK_Version::set_runtime_vendor_version(get_java_version_info(ik, vmSymbols::java_runtime_vendor_version_name()));
2704 
2705     JDK_Version::set_runtime_vendor_vm_bug_url(get_java_version_info(ik, vmSymbols::java_runtime_vendor_vm_bug_url_name()));
2706   }
2707 
2708   // an instance of OutOfMemory exception has been allocated earlier
2709   initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
2710   initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
2711   initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
2712   initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
2713   initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
2714   initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
2715   initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
2716   initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
2717 }
2718 
2719 void Threads::initialize_jsr292_core_classes(TRAPS) {
2720   TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
2721 
2722   initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
2723   initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
2724   initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
2725   initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
2726 }
2727 
2728 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
2729   extern void JDK_Version_init();
2730 
2731   // Preinitialize version info.
2732   VM_Version::early_initialize();
2733 
2734   // Check version
2735   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
2736 
2737   // Initialize library-based TLS
2738   ThreadLocalStorage::init();
2739 
2740   // Initialize the output stream module
2741   ostream_init();
2742 
2743   // Process java launcher properties.
2744   Arguments::process_sun_java_launcher_properties(args);
2745 
2746   // Initialize the os module
2747   os::init();
2748 
2749   MACOS_AARCH64_ONLY(os::current_thread_enable_wx(WXWrite));
2750 
2751   // Record VM creation timing statistics
2752   TraceVmCreationTime create_vm_timer;
2753   create_vm_timer.start();
2754 
2755   // Initialize system properties.
2756   Arguments::init_system_properties();
2757 
2758   // So that JDK version can be used as a discriminator when parsing arguments
2759   JDK_Version_init();
2760 
2761   // Update/Initialize System properties after JDK version number is known
2762   Arguments::init_version_specific_system_properties();
2763 
2764   // Make sure to initialize log configuration *before* parsing arguments
2765   LogConfiguration::initialize(create_vm_timer.begin_time());
2766 
2767   // Parse arguments
2768   // Note: this internally calls os::init_container_support()
2769   jint parse_result = Arguments::parse(args);
2770   if (parse_result != JNI_OK) return parse_result;
2771 
2772 #if INCLUDE_NMT
2773   // Initialize NMT right after argument parsing to keep the pre-NMT-init window small.
2774   MemTracker::initialize();
2775 #endif // INCLUDE_NMT
2776 
2777   os::init_before_ergo();
2778 
2779   jint ergo_result = Arguments::apply_ergo();
2780   if (ergo_result != JNI_OK) return ergo_result;
2781 
2782   // Final check of all ranges after ergonomics which may change values.
2783   if (!JVMFlagLimit::check_all_ranges()) {
2784     return JNI_EINVAL;
2785   }
2786 
2787   // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
2788   bool constraint_result = JVMFlagLimit::check_all_constraints(JVMFlagConstraintPhase::AfterErgo);
2789   if (!constraint_result) {
2790     return JNI_EINVAL;
2791   }
2792 
2793   if (PauseAtStartup) {
2794     os::pause();
2795   }
2796 
2797   HOTSPOT_VM_INIT_BEGIN();
2798 
2799   // Timing (must come after argument parsing)
2800   TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
2801 
2802   // Initialize the os module after parsing the args
2803   jint os_init_2_result = os::init_2();
2804   if (os_init_2_result != JNI_OK) return os_init_2_result;
2805 
2806 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
2807   // Initialize assert poison page mechanism.
2808   if (ShowRegistersOnAssert) {
2809     initialize_assert_poison();
2810   }
2811 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
2812 
2813   SafepointMechanism::initialize();
2814 
2815   jint adjust_after_os_result = Arguments::adjust_after_os();
2816   if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
2817 
2818   // Initialize output stream logging
2819   ostream_init_log();
2820 
2821   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
2822   // Must be before create_vm_init_agents()
2823   if (Arguments::init_libraries_at_startup()) {
2824     convert_vm_init_libraries_to_agents();
2825   }
2826 
2827   // Launch -agentlib/-agentpath and converted -Xrun agents
2828   if (Arguments::init_agents_at_startup()) {
2829     create_vm_init_agents();
2830   }
2831 
2832   // Initialize Threads state
2833   _number_of_threads = 0;
2834   _number_of_non_daemon_threads = 0;
2835 
2836   // Initialize global data structures and create system classes in heap
2837   vm_init_globals();
2838 
2839 #if INCLUDE_JVMCI
2840   if (JVMCICounterSize > 0) {
2841     JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtJVMCI);
2842     memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
2843   } else {
2844     JavaThread::_jvmci_old_thread_counters = NULL;
2845   }
2846 #endif // INCLUDE_JVMCI
2847 
2848   // Initialize OopStorage for threadObj
2849   _thread_oop_storage = OopStorageSet::create_strong("Thread OopStorage", mtThread);
2850 
2851   // Attach the main thread to this os thread
2852   JavaThread* main_thread = new JavaThread();
2853   main_thread->set_thread_state(_thread_in_vm);
2854   main_thread->initialize_thread_current();
2855   // must do this before set_active_handles
2856   main_thread->record_stack_base_and_size();
2857   main_thread->register_thread_stack_with_NMT();
2858   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
2859   MACOS_AARCH64_ONLY(main_thread->init_wx());
2860 
2861   if (!main_thread->set_as_starting_thread()) {
2862     vm_shutdown_during_initialization(
2863                                       "Failed necessary internal allocation. Out of swap space");
2864     main_thread->smr_delete();
2865     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
2866     return JNI_ENOMEM;
2867   }
2868 
2869   // Enable guard page *after* os::create_main_thread(), otherwise it would
2870   // crash Linux VM, see notes in os_linux.cpp.
2871   main_thread->stack_overflow_state()->create_stack_guard_pages();
2872 
2873   // Initialize Java-Level synchronization subsystem
2874   ObjectMonitor::Initialize();
2875   ObjectSynchronizer::initialize();
2876 
2877   // Initialize global modules
2878   jint status = init_globals();
2879   if (status != JNI_OK) {
2880     main_thread->smr_delete();
2881     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
2882     return status;
2883   }
2884 
2885   JFR_ONLY(Jfr::on_create_vm_1();)
2886 
2887   // Should be done after the heap is fully created
2888   main_thread->cache_global_variables();
2889 
2890   { MutexLocker mu(Threads_lock);
2891     Threads::add(main_thread);
2892   }
2893 
2894   // Any JVMTI raw monitors entered in onload will transition into
2895   // real raw monitor. VM is setup enough here for raw monitor enter.
2896   JvmtiExport::transition_pending_onload_raw_monitors();
2897 
2898   // Create the VMThread
2899   { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
2900 
2901     VMThread::create();
2902     Thread* vmthread = VMThread::vm_thread();
2903 
2904     if (!os::create_thread(vmthread, os::vm_thread)) {
2905       vm_exit_during_initialization("Cannot create VM thread. "
2906                                     "Out of system resources.");
2907     }
2908 
2909     // Wait for the VM thread to become ready, and VMThread::run to initialize
2910     // Monitors can have spurious returns, must always check another state flag
2911     {
2912       MonitorLocker ml(Notify_lock);
2913       os::start_thread(vmthread);
2914       while (vmthread->active_handles() == NULL) {
2915         ml.wait();
2916       }
2917     }
2918   }
2919 
2920   assert(Universe::is_fully_initialized(), "not initialized");
2921   if (VerifyDuringStartup) {
2922     // Make sure we're starting with a clean slate.
2923     VM_Verify verify_op;
2924     VMThread::execute(&verify_op);
2925   }
2926 
2927   // We need this to update the java.vm.info property in case any flags used
2928   // to initially define it have been changed. This is needed for both CDS
2929   // since UseSharedSpaces may be changed after java.vm.info
2930   // is initially computed. See Abstract_VM_Version::vm_info_string().
2931   // This update must happen before we initialize the java classes, but
2932   // after any initialization logic that might modify the flags.
2933   Arguments::update_vm_info_property(VM_Version::vm_info_string());
2934 
2935   JavaThread* THREAD = JavaThread::current(); // For exception macros.
2936   HandleMark hm(THREAD);
2937 
2938   // Always call even when there are not JVMTI environments yet, since environments
2939   // may be attached late and JVMTI must track phases of VM execution
2940   JvmtiExport::enter_early_start_phase();
2941 
2942   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
2943   JvmtiExport::post_early_vm_start();
2944 
2945   initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
2946 
2947   quicken_jni_functions();
2948 
2949   // No more stub generation allowed after that point.
2950   StubCodeDesc::freeze();
2951 
2952   // Set flag that basic initialization has completed. Used by exceptions and various
2953   // debug stuff, that does not work until all basic classes have been initialized.
2954   set_init_completed();
2955 
2956   LogConfiguration::post_initialize();
2957   Metaspace::post_initialize();
2958 
2959   HOTSPOT_VM_INIT_END();
2960 
2961   // record VM initialization completion time
2962 #if INCLUDE_MANAGEMENT
2963   Management::record_vm_init_completed();
2964 #endif // INCLUDE_MANAGEMENT
2965 
2966   // Signal Dispatcher needs to be started before VMInit event is posted
2967   os::initialize_jdk_signal_support(CHECK_JNI_ERR);
2968 
2969   // Start Attach Listener if +StartAttachListener or it can't be started lazily
2970   if (!DisableAttachMechanism) {
2971     AttachListener::vm_start();
2972     if (StartAttachListener || AttachListener::init_at_startup()) {
2973       AttachListener::init();
2974     }
2975   }
2976 
2977   // Launch -Xrun agents
2978   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
2979   // back-end can launch with -Xdebug -Xrunjdwp.
2980   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
2981     create_vm_init_libraries();
2982   }
2983 
2984   Chunk::start_chunk_pool_cleaner_task();
2985 
2986   // Start the service thread
2987   // The service thread enqueues JVMTI deferred events and does various hashtable
2988   // and other cleanups.  Needs to start before the compilers start posting events.
2989   ServiceThread::initialize();
2990 
2991   // Start the monitor deflation thread:
2992   MonitorDeflationThread::initialize();
2993 
2994   // initialize compiler(s)
2995 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
2996 #if INCLUDE_JVMCI
2997   bool force_JVMCI_intialization = false;
2998   if (EnableJVMCI) {
2999     // Initialize JVMCI eagerly when it is explicitly requested.
3000     // Or when JVMCILibDumpJNIConfig or JVMCIPrintProperties is enabled.
3001     force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties || JVMCILibDumpJNIConfig;
3002 
3003     if (!force_JVMCI_intialization) {
3004       // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3005       // compilations via JVMCI will not actually block until JVMCI is initialized.
3006       force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3007     }
3008   }
3009 #endif
3010   CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
3011   // Postpone completion of compiler initialization to after JVMCI
3012   // is initialized to avoid timeouts of blocking compilations.
3013   if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
3014     CompileBroker::compilation_init_phase2();
3015   }
3016 #endif
3017 
3018   // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3019   // It is done after compilers are initialized, because otherwise compilations of
3020   // signature polymorphic MH intrinsics can be missed
3021   // (see SystemDictionary::find_method_handle_intrinsic).
3022   initialize_jsr292_core_classes(CHECK_JNI_ERR);
3023 
3024   // This will initialize the module system.  Only java.base classes can be
3025   // loaded until phase 2 completes
3026   call_initPhase2(CHECK_JNI_ERR);
3027 
3028   JFR_ONLY(Jfr::on_create_vm_2();)
3029 
3030   // Always call even when there are not JVMTI environments yet, since environments
3031   // may be attached late and JVMTI must track phases of VM execution
3032   JvmtiExport::enter_start_phase();
3033 
3034   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3035   JvmtiExport::post_vm_start();
3036 
3037   // Final system initialization including security manager and system class loader
3038   call_initPhase3(CHECK_JNI_ERR);
3039 
3040   // cache the system and platform class loaders
3041   SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3042 
3043 #if INCLUDE_CDS
3044   // capture the module path info from the ModuleEntryTable
3045   ClassLoader::initialize_module_path(THREAD);
3046   if (HAS_PENDING_EXCEPTION) {
3047     java_lang_Throwable::print(PENDING_EXCEPTION, tty);
3048     vm_exit_during_initialization("ClassLoader::initialize_module_path() failed unexpectedly");
3049   }
3050 #endif
3051 
3052 #if INCLUDE_JVMCI
3053   if (force_JVMCI_intialization) {
3054     JVMCI::initialize_compiler(CHECK_JNI_ERR);
3055     CompileBroker::compilation_init_phase2();
3056   }
3057 #endif
3058 
3059   // Always call even when there are not JVMTI environments yet, since environments
3060   // may be attached late and JVMTI must track phases of VM execution
3061   JvmtiExport::enter_live_phase();
3062 
3063   // Make perfmemory accessible
3064   PerfMemory::set_accessible(true);
3065 
3066   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3067   JvmtiExport::post_vm_initialized();
3068 
3069   JFR_ONLY(Jfr::on_create_vm_3();)
3070 
3071 #if INCLUDE_MANAGEMENT
3072   Management::initialize(THREAD);
3073 
3074   if (HAS_PENDING_EXCEPTION) {
3075     // management agent fails to start possibly due to
3076     // configuration problem and is responsible for printing
3077     // stack trace if appropriate. Simply exit VM.
3078     vm_exit(1);
3079   }
3080 #endif // INCLUDE_MANAGEMENT
3081 
3082   StatSampler::engage();
3083   if (CheckJNICalls)                  JniPeriodicChecker::engage();
3084 
3085   BiasedLocking::init();
3086 
3087 #if INCLUDE_RTM_OPT
3088   RTMLockingCounters::init();
3089 #endif
3090 
3091   call_postVMInitHook(THREAD);
3092   // The Java side of PostVMInitHook.run must deal with all
3093   // exceptions and provide means of diagnosis.
3094   if (HAS_PENDING_EXCEPTION) {
3095     CLEAR_PENDING_EXCEPTION;
3096   }
3097 
3098   {
3099     MutexLocker ml(PeriodicTask_lock);
3100     // Make sure the WatcherThread can be started by WatcherThread::start()
3101     // or by dynamic enrollment.
3102     WatcherThread::make_startable();
3103     // Start up the WatcherThread if there are any periodic tasks
3104     // NOTE:  All PeriodicTasks should be registered by now. If they
3105     //   aren't, late joiners might appear to start slowly (we might
3106     //   take a while to process their first tick).
3107     if (PeriodicTask::num_tasks() > 0) {
3108       WatcherThread::start();
3109     }
3110   }
3111 
3112   create_vm_timer.end();
3113 #ifdef ASSERT
3114   _vm_complete = true;
3115 #endif
3116 
3117   if (DumpSharedSpaces) {
3118     MetaspaceShared::preload_and_dump();
3119     ShouldNotReachHere();
3120   }
3121 
3122   return JNI_OK;
3123 }
3124 
3125 // type for the Agent_OnLoad and JVM_OnLoad entry points
3126 extern "C" {
3127   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3128 }
3129 // Find a command line agent library and return its entry point for
3130 //         -agentlib:  -agentpath:   -Xrun
3131 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3132 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3133                                     const char *on_load_symbols[],
3134                                     size_t num_symbol_entries) {
3135   OnLoadEntry_t on_load_entry = NULL;
3136   void *library = NULL;
3137 
3138   if (!agent->valid()) {
3139     char buffer[JVM_MAXPATHLEN];
3140     char ebuf[1024] = "";
3141     const char *name = agent->name();
3142     const char *msg = "Could not find agent library ";
3143 
3144     // First check to see if agent is statically linked into executable
3145     if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3146       library = agent->os_lib();
3147     } else if (agent->is_absolute_path()) {
3148       library = os::dll_load(name, ebuf, sizeof ebuf);
3149       if (library == NULL) {
3150         const char *sub_msg = " in absolute path, with error: ";
3151         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3152         char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3153         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3154         // If we can't find the agent, exit.
3155         vm_exit_during_initialization(buf, NULL);
3156         FREE_C_HEAP_ARRAY(char, buf);
3157       }
3158     } else {
3159       // Try to load the agent from the standard dll directory
3160       if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3161                              name)) {
3162         library = os::dll_load(buffer, ebuf, sizeof ebuf);
3163       }
3164       if (library == NULL) { // Try the library path directory.
3165         if (os::dll_build_name(buffer, sizeof(buffer), name)) {
3166           library = os::dll_load(buffer, ebuf, sizeof ebuf);
3167         }
3168         if (library == NULL) {
3169           const char *sub_msg = " on the library path, with error: ";
3170           const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
3171 
3172           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
3173                        strlen(ebuf) + strlen(sub_msg2) + 1;
3174           char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3175           if (!agent->is_instrument_lib()) {
3176             jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3177           } else {
3178             jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
3179           }
3180           // If we can't find the agent, exit.
3181           vm_exit_during_initialization(buf, NULL);
3182           FREE_C_HEAP_ARRAY(char, buf);
3183         }
3184       }
3185     }
3186     agent->set_os_lib(library);
3187     agent->set_valid();
3188   }
3189 
3190   // Find the OnLoad function.
3191   on_load_entry =
3192     CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3193                                                           false,
3194                                                           on_load_symbols,
3195                                                           num_symbol_entries));
3196   return on_load_entry;
3197 }
3198 
3199 // Find the JVM_OnLoad entry point
3200 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3201   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3202   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3203 }
3204 
3205 // Find the Agent_OnLoad entry point
3206 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3207   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3208   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3209 }
3210 
3211 // For backwards compatibility with -Xrun
3212 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3213 // treated like -agentpath:
3214 // Must be called before agent libraries are created
3215 void Threads::convert_vm_init_libraries_to_agents() {
3216   AgentLibrary* agent;
3217   AgentLibrary* next;
3218 
3219   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3220     next = agent->next();  // cache the next agent now as this agent may get moved off this list
3221     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3222 
3223     // If there is an JVM_OnLoad function it will get called later,
3224     // otherwise see if there is an Agent_OnLoad
3225     if (on_load_entry == NULL) {
3226       on_load_entry = lookup_agent_on_load(agent);
3227       if (on_load_entry != NULL) {
3228         // switch it to the agent list -- so that Agent_OnLoad will be called,
3229         // JVM_OnLoad won't be attempted and Agent_OnUnload will
3230         Arguments::convert_library_to_agent(agent);
3231       } else {
3232         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3233       }
3234     }
3235   }
3236 }
3237 
3238 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
3239 // Invokes Agent_OnLoad
3240 // Called very early -- before JavaThreads exist
3241 void Threads::create_vm_init_agents() {
3242   extern struct JavaVM_ main_vm;
3243   AgentLibrary* agent;
3244 
3245   JvmtiExport::enter_onload_phase();
3246 
3247   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3248     // CDS dumping does not support native JVMTI agent.
3249     // CDS dumping supports Java agent if the AllowArchivingWithJavaAgent diagnostic option is specified.
3250     if (Arguments::is_dumping_archive()) {
3251       if(!agent->is_instrument_lib()) {
3252         vm_exit_during_cds_dumping("CDS dumping does not support native JVMTI agent, name", agent->name());
3253       } else if (!AllowArchivingWithJavaAgent) {
3254         vm_exit_during_cds_dumping(
3255           "Must enable AllowArchivingWithJavaAgent in order to run Java agent during CDS dumping");
3256       }
3257     }
3258 
3259     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
3260 
3261     if (on_load_entry != NULL) {
3262       // Invoke the Agent_OnLoad function
3263       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3264       if (err != JNI_OK) {
3265         vm_exit_during_initialization("agent library failed to init", agent->name());
3266       }
3267     } else {
3268       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3269     }
3270   }
3271 
3272   JvmtiExport::enter_primordial_phase();
3273 }
3274 
3275 extern "C" {
3276   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3277 }
3278 
3279 void Threads::shutdown_vm_agents() {
3280   // Send any Agent_OnUnload notifications
3281   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3282   size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
3283   extern struct JavaVM_ main_vm;
3284   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3285 
3286     // Find the Agent_OnUnload function.
3287     Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3288                                                    os::find_agent_function(agent,
3289                                                    false,
3290                                                    on_unload_symbols,
3291                                                    num_symbol_entries));
3292 
3293     // Invoke the Agent_OnUnload function
3294     if (unload_entry != NULL) {
3295       JavaThread* thread = JavaThread::current();
3296       ThreadToNativeFromVM ttn(thread);
3297       HandleMark hm(thread);
3298       (*unload_entry)(&main_vm);
3299     }
3300   }
3301 }
3302 
3303 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
3304 // Invokes JVM_OnLoad
3305 void Threads::create_vm_init_libraries() {
3306   extern struct JavaVM_ main_vm;
3307   AgentLibrary* agent;
3308 
3309   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
3310     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3311 
3312     if (on_load_entry != NULL) {
3313       // Invoke the JVM_OnLoad function
3314       JavaThread* thread = JavaThread::current();
3315       ThreadToNativeFromVM ttn(thread);
3316       HandleMark hm(thread);
3317       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3318       if (err != JNI_OK) {
3319         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
3320       }
3321     } else {
3322       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
3323     }
3324   }
3325 }
3326 
3327 
3328 // Last thread running calls java.lang.Shutdown.shutdown()
3329 void JavaThread::invoke_shutdown_hooks() {
3330   HandleMark hm(this);
3331 
3332   // We could get here with a pending exception, if so clear it now or
3333   // it will cause MetaspaceShared::link_and_cleanup_shared_classes to
3334   // fail for dynamic dump.
3335   if (this->has_pending_exception()) {
3336     this->clear_pending_exception();
3337   }
3338 
3339 #if INCLUDE_CDS
3340   // Link all classes for dynamic CDS dumping before vm exit.
3341   // Same operation is being done in JVM_BeforeHalt for handling the
3342   // case where the application calls System.exit().
3343   if (DynamicDumpSharedSpaces) {
3344     DynamicArchive::prepare_for_dynamic_dumping_at_exit();
3345   }
3346 #endif
3347 
3348   EXCEPTION_MARK;
3349   Klass* shutdown_klass =
3350     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
3351                                       THREAD);
3352   if (shutdown_klass != NULL) {
3353     // SystemDictionary::resolve_or_null will return null if there was
3354     // an exception.  If we cannot load the Shutdown class, just don't
3355     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
3356     // won't be run.  Note that if a shutdown hook was registered,
3357     // the Shutdown class would have already been loaded
3358     // (Runtime.addShutdownHook will load it).
3359     JavaValue result(T_VOID);
3360     JavaCalls::call_static(&result,
3361                            shutdown_klass,
3362                            vmSymbols::shutdown_name(),
3363                            vmSymbols::void_method_signature(),
3364                            THREAD);
3365   }
3366   CLEAR_PENDING_EXCEPTION;
3367 }
3368 
3369 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
3370 // the program falls off the end of main(). Another VM exit path is through
3371 // vm_exit() when the program calls System.exit() to return a value or when
3372 // there is a serious error in VM. The two shutdown paths are not exactly
3373 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
3374 // and VM_Exit op at VM level.
3375 //
3376 // Shutdown sequence:
3377 //   + Shutdown native memory tracking if it is on
3378 //   + Wait until we are the last non-daemon thread to execute
3379 //     <-- every thing is still working at this moment -->
3380 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
3381 //        shutdown hooks
3382 //   + Call before_exit(), prepare for VM exit
3383 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
3384 //        currently the only user of this mechanism is File.deleteOnExit())
3385 //      > stop StatSampler, watcher thread,
3386 //        post thread end and vm death events to JVMTI,
3387 //        stop signal thread
3388 //   + Call JavaThread::exit(), it will:
3389 //      > release JNI handle blocks, remove stack guard pages
3390 //      > remove this thread from Threads list
3391 //     <-- no more Java code from this thread after this point -->
3392 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
3393 //     the compiler threads at safepoint
3394 //     <-- do not use anything that could get blocked by Safepoint -->
3395 //   + Disable tracing at JNI/JVM barriers
3396 //   + Set _vm_exited flag for threads that are still running native code
3397 //   + Call exit_globals()
3398 //      > deletes tty
3399 //      > deletes PerfMemory resources
3400 //   + Delete this thread
3401 //   + Return to caller
3402 
3403 void Threads::destroy_vm() {
3404   JavaThread* thread = JavaThread::current();
3405 
3406 #ifdef ASSERT
3407   _vm_complete = false;
3408 #endif
3409   // Wait until we are the last non-daemon thread to execute
3410   {
3411     MonitorLocker nu(Threads_lock);
3412     while (Threads::number_of_non_daemon_threads() > 1)
3413       // This wait should make safepoint checks, wait without a timeout.
3414       nu.wait(0);
3415   }
3416 
3417   EventShutdown e;
3418   if (e.should_commit()) {
3419     e.set_reason("No remaining non-daemon Java threads");
3420     e.commit();
3421   }
3422 
3423   // Hang forever on exit if we are reporting an error.
3424   if (ShowMessageBoxOnError && VMError::is_error_reported()) {
3425     os::infinite_sleep();
3426   }
3427   os::wait_for_keypress_at_exit();
3428 
3429   // run Java level shutdown hooks
3430   thread->invoke_shutdown_hooks();
3431 
3432   before_exit(thread);
3433 
3434   thread->exit(true);
3435 
3436   // We are no longer on the main thread list but could still be in a
3437   // secondary list where another thread may try to interact with us.
3438   // So wait until all such interactions are complete before we bring
3439   // the VM to the termination safepoint. Normally this would be done
3440   // using thread->smr_delete() below where we delete the thread, but
3441   // we can't call that after the termination safepoint is active as
3442   // we will deadlock on the Threads_lock. Once all interactions are
3443   // complete it is safe to directly delete the thread at any time.
3444   ThreadsSMRSupport::wait_until_not_protected(thread);
3445 
3446   // Stop VM thread.
3447   {
3448     // 4945125 The vm thread comes to a safepoint during exit.
3449     // GC vm_operations can get caught at the safepoint, and the
3450     // heap is unparseable if they are caught. Grab the Heap_lock
3451     // to prevent this. The GC vm_operations will not be able to
3452     // queue until after the vm thread is dead. After this point,
3453     // we'll never emerge out of the safepoint before the VM exits.
3454     // Assert that the thread is terminated so that acquiring the
3455     // Heap_lock doesn't cause the terminated thread to participate in
3456     // the safepoint protocol.
3457 
3458     assert(thread->is_terminated(), "must be terminated here");
3459     MutexLocker ml(Heap_lock);
3460 
3461     VMThread::wait_for_vm_thread_exit();
3462     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
3463     VMThread::destroy();
3464   }
3465 
3466   // Now, all Java threads are gone except daemon threads. Daemon threads
3467   // running Java code or in VM are stopped by the Safepoint. However,
3468   // daemon threads executing native code are still running.  But they
3469   // will be stopped at native=>Java/VM barriers. Note that we can't
3470   // simply kill or suspend them, as it is inherently deadlock-prone.
3471 
3472   VM_Exit::set_vm_exited();
3473 
3474   // Clean up ideal graph printers after the VMThread has started
3475   // the final safepoint which will block all the Compiler threads.
3476   // Note that this Thread has already logically exited so the
3477   // clean_up() function's use of a JavaThreadIteratorWithHandle
3478   // would be a problem except set_vm_exited() has remembered the
3479   // shutdown thread which is granted a policy exception.
3480 #if defined(COMPILER2) && !defined(PRODUCT)
3481   IdealGraphPrinter::clean_up();
3482 #endif
3483 
3484   notify_vm_shutdown();
3485 
3486   // exit_globals() will delete tty
3487   exit_globals();
3488 
3489   // Deleting the shutdown thread here is safe. See comment on
3490   // wait_until_not_protected() above.
3491   delete thread;
3492 
3493 #if INCLUDE_JVMCI
3494   if (JVMCICounterSize > 0) {
3495     FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
3496   }
3497 #endif
3498 
3499   LogConfiguration::finalize();
3500 }
3501 
3502 
3503 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
3504   if (version == JNI_VERSION_1_1) return JNI_TRUE;
3505   return is_supported_jni_version(version);
3506 }
3507 
3508 
3509 jboolean Threads::is_supported_jni_version(jint version) {
3510   if (version == JNI_VERSION_1_2) return JNI_TRUE;
3511   if (version == JNI_VERSION_1_4) return JNI_TRUE;
3512   if (version == JNI_VERSION_1_6) return JNI_TRUE;
3513   if (version == JNI_VERSION_1_8) return JNI_TRUE;
3514   if (version == JNI_VERSION_9) return JNI_TRUE;
3515   if (version == JNI_VERSION_10) return JNI_TRUE;
3516   return JNI_FALSE;
3517 }
3518 
3519 
3520 void Threads::add(JavaThread* p, bool force_daemon) {
3521   // The threads lock must be owned at this point
3522   assert(Threads_lock->owned_by_self(), "must have threads lock");
3523 
3524   BarrierSet::barrier_set()->on_thread_attach(p);
3525 
3526   // Once a JavaThread is added to the Threads list, smr_delete() has
3527   // to be used to delete it. Otherwise we can just delete it directly.
3528   p->set_on_thread_list();
3529 
3530   _number_of_threads++;
3531   oop threadObj = p->threadObj();
3532   bool daemon = true;
3533   // Bootstrapping problem: threadObj can be null for initial
3534   // JavaThread (or for threads attached via JNI)
3535   if ((!force_daemon) && !is_daemon((threadObj))) {
3536     _number_of_non_daemon_threads++;
3537     daemon = false;
3538   }
3539 
3540   ThreadService::add_thread(p, daemon);
3541 
3542   // Maintain fast thread list
3543   ThreadsSMRSupport::add_thread(p);
3544 
3545   // Increase the ObjectMonitor ceiling for the new thread.
3546   ObjectSynchronizer::inc_in_use_list_ceiling();
3547 
3548   // Possible GC point.
3549   Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
3550 
3551   // Make new thread known to active EscapeBarrier
3552   EscapeBarrier::thread_added(p);
3553 }
3554 
3555 void Threads::remove(JavaThread* p, bool is_daemon) {
3556   // Extra scope needed for Thread_lock, so we can check
3557   // that we do not remove thread without safepoint code notice
3558   { MonitorLocker ml(Threads_lock);
3559 
3560     // BarrierSet state must be destroyed after the last thread transition
3561     // before the thread terminates. Thread transitions result in calls to
3562     // StackWatermarkSet::on_safepoint(), which performs GC processing,
3563     // requiring the GC state to be alive.
3564     BarrierSet::barrier_set()->on_thread_detach(p);
3565 
3566     assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
3567 
3568     // Maintain fast thread list
3569     ThreadsSMRSupport::remove_thread(p);
3570 
3571     _number_of_threads--;
3572     if (!is_daemon) {
3573       _number_of_non_daemon_threads--;
3574 
3575       // Only one thread left, do a notify on the Threads_lock so a thread waiting
3576       // on destroy_vm will wake up.
3577       if (number_of_non_daemon_threads() == 1) {
3578         ml.notify_all();
3579       }
3580     }
3581     ThreadService::remove_thread(p, is_daemon);
3582 
3583     // Make sure that safepoint code disregard this thread. This is needed since
3584     // the thread might mess around with locks after this point. This can cause it
3585     // to do callbacks into the safepoint code. However, the safepoint code is not aware
3586     // of this thread since it is removed from the queue.
3587     p->set_terminated(JavaThread::_thread_terminated);
3588 
3589     // Notify threads waiting in EscapeBarriers
3590     EscapeBarrier::thread_removed(p);
3591   } // unlock Threads_lock
3592 
3593   // Reduce the ObjectMonitor ceiling for the exiting thread.
3594   ObjectSynchronizer::dec_in_use_list_ceiling();
3595 
3596   // Since Events::log uses a lock, we grab it outside the Threads_lock
3597   Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
3598 }
3599 
3600 // Operations on the Threads list for GC.  These are not explicitly locked,
3601 // but the garbage collector must provide a safe context for them to run.
3602 // In particular, these things should never be called when the Threads_lock
3603 // is held by some other thread. (Note: the Safepoint abstraction also
3604 // uses the Threads_lock to guarantee this property. It also makes sure that
3605 // all threads gets blocked when exiting or starting).
3606 
3607 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3608   ALL_JAVA_THREADS(p) {
3609     p->oops_do(f, cf);
3610   }
3611   VMThread::vm_thread()->oops_do(f, cf);
3612 }
3613 
3614 void Threads::change_thread_claim_token() {
3615   if (++_thread_claim_token == 0) {
3616     // On overflow of the token counter, there is a risk of future
3617     // collisions between a new global token value and a stale token
3618     // for a thread, because not all iterations visit all threads.
3619     // (Though it's pretty much a theoretical concern for non-trivial
3620     // token counter sizes.)  To deal with the possibility, reset all
3621     // the thread tokens to zero on global token overflow.
3622     struct ResetClaims : public ThreadClosure {
3623       virtual void do_thread(Thread* t) {
3624         t->claim_threads_do(false, 0);
3625       }
3626     } reset_claims;
3627     Threads::threads_do(&reset_claims);
3628     // On overflow, update the global token to non-zero, to
3629     // avoid the special "never claimed" initial thread value.
3630     _thread_claim_token = 1;
3631   }
3632 }
3633 
3634 #ifdef ASSERT
3635 void assert_thread_claimed(const char* kind, Thread* t, uintx expected) {
3636   const uintx token = t->threads_do_token();
3637   assert(token == expected,
3638          "%s " PTR_FORMAT " has incorrect value " UINTX_FORMAT " != "
3639          UINTX_FORMAT, kind, p2i(t), token, expected);
3640 }
3641 
3642 void Threads::assert_all_threads_claimed() {
3643   ALL_JAVA_THREADS(p) {
3644     assert_thread_claimed("Thread", p, _thread_claim_token);
3645   }
3646   assert_thread_claimed("VMThread", VMThread::vm_thread(), _thread_claim_token);
3647 }
3648 #endif // ASSERT
3649 
3650 class ParallelOopsDoThreadClosure : public ThreadClosure {
3651 private:
3652   OopClosure* _f;
3653   CodeBlobClosure* _cf;
3654 public:
3655   ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
3656   void do_thread(Thread* t) {
3657     t->oops_do(_f, _cf);
3658   }
3659 };
3660 
3661 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
3662   ParallelOopsDoThreadClosure tc(f, cf);
3663   possibly_parallel_threads_do(is_par, &tc);
3664 }
3665 
3666 void Threads::metadata_do(MetadataClosure* f) {
3667   ALL_JAVA_THREADS(p) {
3668     p->metadata_do(f);
3669   }
3670 }
3671 
3672 class ThreadHandlesClosure : public ThreadClosure {
3673   void (*_f)(Metadata*);
3674  public:
3675   ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
3676   virtual void do_thread(Thread* thread) {
3677     thread->metadata_handles_do(_f);
3678   }
3679 };
3680 
3681 void Threads::metadata_handles_do(void f(Metadata*)) {
3682   // Only walk the Handles in Thread.
3683   ThreadHandlesClosure handles_closure(f);
3684   threads_do(&handles_closure);
3685 }
3686 
3687 // Get count Java threads that are waiting to enter the specified monitor.
3688 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
3689                                                          int count,
3690                                                          address monitor) {
3691   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
3692 
3693   int i = 0;
3694   DO_JAVA_THREADS(t_list, p) {
3695     if (!p->can_call_java()) continue;
3696 
3697     // The first stage of async deflation does not affect any field
3698     // used by this comparison so the ObjectMonitor* is usable here.
3699     address pending = (address)p->current_pending_monitor();
3700     if (pending == monitor) {             // found a match
3701       if (i < count) result->append(p);   // save the first count matches
3702       i++;
3703     }
3704   }
3705 
3706   return result;
3707 }
3708 
3709 
3710 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
3711                                                       address owner) {
3712   // NULL owner means not locked so we can skip the search
3713   if (owner == NULL) return NULL;
3714 
3715   DO_JAVA_THREADS(t_list, p) {
3716     // first, see if owner is the address of a Java thread
3717     if (owner == (address)p) return p;
3718   }
3719 
3720   // Cannot assert on lack of success here since this function may be
3721   // used by code that is trying to report useful problem information
3722   // like deadlock detection.
3723   if (UseHeavyMonitors) return NULL;
3724 
3725   // If we didn't find a matching Java thread and we didn't force use of
3726   // heavyweight monitors, then the owner is the stack address of the
3727   // Lock Word in the owning Java thread's stack.
3728   //
3729   JavaThread* the_owner = NULL;
3730   DO_JAVA_THREADS(t_list, q) {
3731     if (q->is_lock_owned(owner)) {
3732       the_owner = q;
3733       break;
3734     }
3735   }
3736 
3737   // cannot assert on lack of success here; see above comment
3738   return the_owner;
3739 }
3740 
3741 class PrintOnClosure : public ThreadClosure {
3742 private:
3743   outputStream* _st;
3744 
3745 public:
3746   PrintOnClosure(outputStream* st) :
3747       _st(st) {}
3748 
3749   virtual void do_thread(Thread* thread) {
3750     if (thread != NULL) {
3751       thread->print_on(_st);
3752       _st->cr();
3753     }
3754   }
3755 };
3756 
3757 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
3758 void Threads::print_on(outputStream* st, bool print_stacks,
3759                        bool internal_format, bool print_concurrent_locks,
3760                        bool print_extended_info) {
3761   char buf[32];
3762   st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
3763 
3764   st->print_cr("Full thread dump %s (%s %s):",
3765                VM_Version::vm_name(),
3766                VM_Version::vm_release(),
3767                VM_Version::vm_info_string());
3768   st->cr();
3769 
3770 #if INCLUDE_SERVICES
3771   // Dump concurrent locks
3772   ConcurrentLocksDump concurrent_locks;
3773   if (print_concurrent_locks) {
3774     concurrent_locks.dump_at_safepoint();
3775   }
3776 #endif // INCLUDE_SERVICES
3777 
3778   ThreadsSMRSupport::print_info_on(st);
3779   st->cr();
3780 
3781   ALL_JAVA_THREADS(p) {
3782     ResourceMark rm;
3783     p->print_on(st, print_extended_info);
3784     if (print_stacks) {
3785       if (internal_format) {
3786         p->trace_stack();
3787       } else {
3788         p->print_stack_on(st);
3789       }
3790     }
3791     st->cr();
3792 #if INCLUDE_SERVICES
3793     if (print_concurrent_locks) {
3794       concurrent_locks.print_locks_on(p, st);
3795     }
3796 #endif // INCLUDE_SERVICES
3797   }
3798 
3799   PrintOnClosure cl(st);
3800   cl.do_thread(VMThread::vm_thread());
3801   Universe::heap()->gc_threads_do(&cl);
3802   if (StringDedup::is_enabled()) {
3803     StringDedup::threads_do(&cl);
3804   }
3805   cl.do_thread(WatcherThread::watcher_thread());
3806   cl.do_thread(AsyncLogWriter::instance());
3807 
3808   st->flush();
3809 }
3810 
3811 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
3812                              int buflen, bool* found_current) {
3813   if (this_thread != NULL) {
3814     bool is_current = (current == this_thread);
3815     *found_current = *found_current || is_current;
3816     st->print("%s", is_current ? "=>" : "  ");
3817 
3818     st->print(PTR_FORMAT, p2i(this_thread));
3819     st->print(" ");
3820     this_thread->print_on_error(st, buf, buflen);
3821     st->cr();
3822   }
3823 }
3824 
3825 class PrintOnErrorClosure : public ThreadClosure {
3826   outputStream* _st;
3827   Thread* _current;
3828   char* _buf;
3829   int _buflen;
3830   bool* _found_current;
3831  public:
3832   PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
3833                       int buflen, bool* found_current) :
3834    _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
3835 
3836   virtual void do_thread(Thread* thread) {
3837     Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
3838   }
3839 };
3840 
3841 // Threads::print_on_error() is called by fatal error handler. It's possible
3842 // that VM is not at safepoint and/or current thread is inside signal handler.
3843 // Don't print stack trace, as the stack may not be walkable. Don't allocate
3844 // memory (even in resource area), it might deadlock the error handler.
3845 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
3846                              int buflen) {
3847   ThreadsSMRSupport::print_info_on(st);
3848   st->cr();
3849 
3850   bool found_current = false;
3851   st->print_cr("Java Threads: ( => current thread )");
3852   ALL_JAVA_THREADS(thread) {
3853     print_on_error(thread, st, current, buf, buflen, &found_current);
3854   }
3855   st->cr();
3856 
3857   st->print_cr("Other Threads:");
3858   print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
3859   print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
3860   print_on_error(AsyncLogWriter::instance(), st, current, buf, buflen, &found_current);
3861 
3862   if (Universe::heap() != NULL) {
3863     PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
3864     Universe::heap()->gc_threads_do(&print_closure);
3865   }
3866 
3867   if (StringDedup::is_enabled()) {
3868     PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
3869     StringDedup::threads_do(&print_closure);
3870   }
3871 
3872   if (!found_current) {
3873     st->cr();
3874     st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
3875     current->print_on_error(st, buf, buflen);
3876     st->cr();
3877   }
3878   st->cr();
3879 
3880   st->print_cr("Threads with active compile tasks:");
3881   print_threads_compiling(st, buf, buflen);
3882 }
3883 
3884 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen, bool short_form) {
3885   ALL_JAVA_THREADS(thread) {
3886     if (thread->is_Compiler_thread()) {
3887       CompilerThread* ct = (CompilerThread*) thread;
3888 
3889       // Keep task in local variable for NULL check.
3890       // ct->_task might be set to NULL by concurring compiler thread
3891       // because it completed the compilation. The task is never freed,
3892       // though, just returned to a free list.
3893       CompileTask* task = ct->task();
3894       if (task != NULL) {
3895         thread->print_name_on_error(st, buf, buflen);
3896         st->print("  ");
3897         task->print(st, NULL, short_form, true);
3898       }
3899     }
3900   }
3901 }
3902 
3903 
3904 // Ad-hoc mutual exclusion primitives: SpinLock
3905 //
3906 // We employ SpinLocks _only for low-contention, fixed-length
3907 // short-duration critical sections where we're concerned
3908 // about native mutex_t or HotSpot Mutex:: latency.
3909 //
3910 // TODO-FIXME: ListLock should be of type SpinLock.
3911 // We should make this a 1st-class type, integrated into the lock
3912 // hierarchy as leaf-locks.  Critically, the SpinLock structure
3913 // should have sufficient padding to avoid false-sharing and excessive
3914 // cache-coherency traffic.
3915 
3916 
3917 typedef volatile int SpinLockT;
3918 
3919 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
3920   if (Atomic::cmpxchg(adr, 0, 1) == 0) {
3921     return;   // normal fast-path return
3922   }
3923 
3924   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
3925   int ctr = 0;
3926   int Yields = 0;
3927   for (;;) {
3928     while (*adr != 0) {
3929       ++ctr;
3930       if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
3931         if (Yields > 5) {
3932           os::naked_short_sleep(1);
3933         } else {
3934           os::naked_yield();
3935           ++Yields;
3936         }
3937       } else {
3938         SpinPause();
3939       }
3940     }
3941     if (Atomic::cmpxchg(adr, 0, 1) == 0) return;
3942   }
3943 }
3944 
3945 void Thread::SpinRelease(volatile int * adr) {
3946   assert(*adr != 0, "invariant");
3947   OrderAccess::fence();      // guarantee at least release consistency.
3948   // Roach-motel semantics.
3949   // It's safe if subsequent LDs and STs float "up" into the critical section,
3950   // but prior LDs and STs within the critical section can't be allowed
3951   // to reorder or float past the ST that releases the lock.
3952   // Loads and stores in the critical section - which appear in program
3953   // order before the store that releases the lock - must also appear
3954   // before the store that releases the lock in memory visibility order.
3955   // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
3956   // the ST of 0 into the lock-word which releases the lock, so fence
3957   // more than covers this on all platforms.
3958   *adr = 0;
3959 }
3960 
3961 
3962 void Threads::verify() {
3963   ALL_JAVA_THREADS(p) {
3964     p->verify();
3965   }
3966   VMThread* thread = VMThread::vm_thread();
3967   if (thread != NULL) thread->verify();
3968 }
3969 
3970 #ifndef PRODUCT
3971 void JavaThread::verify_cross_modify_fence_failure(JavaThread *thread) {
3972    report_vm_error(__FILE__, __LINE__, "Cross modify fence failure", "%p", thread);
3973 }
3974 #endif