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/lockStack.inline.hpp"
  93 #include "runtime/monitorDeflationThread.hpp"
  94 #include "runtime/mutexLocker.hpp"
  95 #include "runtime/nonJavaThread.hpp"
  96 #include "runtime/objectMonitor.inline.hpp"
  97 #include "runtime/orderAccess.hpp"
  98 #include "runtime/osThread.hpp"
  99 #include "runtime/prefetch.inline.hpp"
 100 #include "runtime/safepoint.hpp"
 101 #include "runtime/safepointMechanism.inline.hpp"
 102 #include "runtime/safepointVerifiers.hpp"
 103 #include "runtime/serviceThread.hpp"
 104 #include "runtime/sharedRuntime.hpp"
 105 #include "runtime/stackFrameStream.inline.hpp"
 106 #include "runtime/stackWatermarkSet.hpp"
 107 #include "runtime/statSampler.hpp"
 108 #include "runtime/task.hpp"
 109 #include "runtime/thread.inline.hpp"
 110 #include "runtime/threadCritical.hpp"
 111 #include "runtime/threadSMR.inline.hpp"
 112 #include "runtime/threadStatisticalInfo.hpp"
 113 #include "runtime/threadWXSetters.inline.hpp"
 114 #include "runtime/timer.hpp"
 115 #include "runtime/timerTrace.hpp"
 116 #include "runtime/vframe.inline.hpp"
 117 #include "runtime/vframeArray.hpp"
 118 #include "runtime/vframe_hp.hpp"
 119 #include "runtime/vmThread.hpp"
 120 #include "runtime/vmOperations.hpp"
 121 #include "runtime/vm_version.hpp"
 122 #include "services/attachListener.hpp"
 123 #include "services/management.hpp"
 124 #include "services/memTracker.hpp"
 125 #include "services/threadService.hpp"
 126 #include "utilities/align.hpp"
 127 #include "utilities/copy.hpp"
 128 #include "utilities/defaultStream.hpp"
 129 #include "utilities/dtrace.hpp"
 130 #include "utilities/events.hpp"
 131 #include "utilities/macros.hpp"
 132 #include "utilities/preserveException.hpp"
 133 #include "utilities/spinYield.hpp"
 134 #include "utilities/vmError.hpp"
 135 #if INCLUDE_JVMCI
 136 #include "jvmci/jvmci.hpp"
 137 #include "jvmci/jvmciEnv.hpp"
 138 #endif
 139 #ifdef COMPILER1
 140 #include "c1/c1_Compiler.hpp"
 141 #endif
 142 #ifdef COMPILER2
 143 #include "opto/c2compiler.hpp"
 144 #include "opto/idealGraphPrinter.hpp"
 145 #endif
 146 #if INCLUDE_RTM_OPT
 147 #include "runtime/rtmLocking.hpp"
 148 #endif
 149 #if INCLUDE_JFR
 150 #include "jfr/jfr.hpp"
 151 #endif
 152 
 153 // Initialization after module runtime initialization
 154 void universe_post_module_init();  // must happen after call_initPhase2
 155 
 156 #ifdef DTRACE_ENABLED
 157 
 158 // Only bother with this argument setup if dtrace is available
 159 
 160   #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
 161   #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
 162 
 163   #define DTRACE_THREAD_PROBE(probe, javathread)                           \
 164     {                                                                      \
 165       ResourceMark rm(this);                                               \
 166       int len = 0;                                                         \
 167       const char* name = (javathread)->get_thread_name();                  \
 168       len = strlen(name);                                                  \
 169       HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */               \
 170         (char *) name, len,                                                \
 171         java_lang_Thread::thread_id((javathread)->threadObj()),            \
 172         (uintptr_t) (javathread)->osthread()->thread_id(),                 \
 173         java_lang_Thread::is_daemon((javathread)->threadObj()));           \
 174     }
 175 
 176 #else //  ndef DTRACE_ENABLED
 177 
 178   #define DTRACE_THREAD_PROBE(probe, javathread)
 179 
 180 #endif // ndef DTRACE_ENABLED
 181 
 182 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 183 // Current thread is maintained as a thread-local variable
 184 THREAD_LOCAL Thread* Thread::_thr_current = NULL;
 185 #endif
 186 
 187 // ======= Thread ========
 188 // Support for forcing alignment of thread objects for biased locking
 189 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
 190   if (UseBiasedLocking) {
 191     const size_t alignment = markWord::biased_lock_alignment;
 192     size_t aligned_size = size + (alignment - sizeof(intptr_t));
 193     void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
 194                                           : AllocateHeap(aligned_size, flags, CURRENT_PC,
 195                                                          AllocFailStrategy::RETURN_NULL);
 196     void* aligned_addr     = align_up(real_malloc_addr, alignment);
 197     assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
 198            ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
 199            "JavaThread alignment code overflowed allocated storage");
 200     if (aligned_addr != real_malloc_addr) {
 201       log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
 202                               p2i(real_malloc_addr),
 203                               p2i(aligned_addr));
 204     }
 205     ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
 206     return aligned_addr;
 207   } else {
 208     return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
 209                        : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
 210   }
 211 }
 212 
 213 void Thread::operator delete(void* p) {
 214   if (UseBiasedLocking) {
 215     FreeHeap(((Thread*) p)->_real_malloc_address);
 216   } else {
 217     FreeHeap(p);
 218   }
 219 }
 220 
 221 void JavaThread::smr_delete() {
 222   if (_on_thread_list) {
 223     ThreadsSMRSupport::smr_delete(this);
 224   } else {
 225     delete this;
 226   }
 227 }
 228 
 229 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
 230 // JavaThread
 231 
 232 DEBUG_ONLY(Thread* Thread::_starting_thread = NULL;)
 233 
 234 Thread::Thread() {
 235 
 236   DEBUG_ONLY(_run_state = PRE_CALL_RUN;)
 237 
 238   // stack and get_thread
 239   set_stack_base(NULL);
 240   set_stack_size(0);
 241   set_lgrp_id(-1);
 242   DEBUG_ONLY(clear_suspendible_thread();)
 243 
 244   // allocated data structures
 245   set_osthread(NULL);
 246   set_resource_area(new (mtThread)ResourceArea());
 247   DEBUG_ONLY(_current_resource_mark = NULL;)
 248   set_handle_area(new (mtThread) HandleArea(NULL));
 249   set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, mtClass));
 250   set_active_handles(NULL);
 251   set_free_handle_block(NULL);
 252   set_last_handle_mark(NULL);
 253   DEBUG_ONLY(_missed_ic_stub_refill_verifier = NULL);
 254 
 255   // Initial value of zero ==> never claimed.
 256   _threads_do_token = 0;
 257   _threads_hazard_ptr = NULL;
 258   _threads_list_ptr = NULL;
 259   _nested_threads_hazard_ptr_cnt = 0;
 260   _rcu_counter = 0;
 261 
 262   // the handle mark links itself to last_handle_mark
 263   new HandleMark(this);
 264 
 265   // plain initialization
 266   debug_only(_owned_locks = NULL;)
 267   NOT_PRODUCT(_skip_gcalot = false;)
 268   _jvmti_env_iteration_count = 0;
 269   set_allocated_bytes(0);
 270   _current_pending_raw_monitor = NULL;
 271 
 272   // thread-specific hashCode stream generator state - Marsaglia shift-xor form
 273   _hashStateX = os::random();
 274   _hashStateY = 842502087;
 275   _hashStateZ = 0x8767;    // (int)(3579807591LL & 0xffff) ;
 276   _hashStateW = 273326509;
 277 
 278   // Many of the following fields are effectively final - immutable
 279   // Note that nascent threads can't use the Native Monitor-Mutex
 280   // construct until the _MutexEvent is initialized ...
 281   // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
 282   // we might instead use a stack of ParkEvents that we could provision on-demand.
 283   // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
 284   // and ::Release()
 285   _ParkEvent   = ParkEvent::Allocate(this);
 286 
 287 #ifdef CHECK_UNHANDLED_OOPS
 288   if (CheckUnhandledOops) {
 289     _unhandled_oops = new UnhandledOops(this);
 290   }
 291 #endif // CHECK_UNHANDLED_OOPS
 292 #ifdef ASSERT
 293   if (UseBiasedLocking) {
 294     assert(is_aligned(this, markWord::biased_lock_alignment), "forced alignment of thread object failed");
 295     assert(this == _real_malloc_address ||
 296            this == align_up(_real_malloc_address, markWord::biased_lock_alignment),
 297            "bug in forced alignment of thread objects");
 298   }
 299 #endif // ASSERT
 300 
 301   // Notify the barrier set that a thread is being created. The initial
 302   // thread is created before the barrier set is available.  The call to
 303   // BarrierSet::on_thread_create() for this thread is therefore deferred
 304   // to BarrierSet::set_barrier_set().
 305   BarrierSet* const barrier_set = BarrierSet::barrier_set();
 306   if (barrier_set != NULL) {
 307     barrier_set->on_thread_create(this);
 308   } else {
 309     // Only the main thread should be created before the barrier set
 310     // and that happens just before Thread::current is set. No other thread
 311     // can attach as the VM is not created yet, so they can't execute this code.
 312     // If the main thread creates other threads before the barrier set that is an error.
 313     assert(Thread::current_or_null() == NULL, "creating thread before barrier set");
 314   }
 315 
 316   MACOS_AARCH64_ONLY(DEBUG_ONLY(_wx_init = false));
 317 }
 318 
 319 void Thread::initialize_tlab() {
 320   if (UseTLAB) {
 321     tlab().initialize();
 322   }
 323 }
 324 
 325 void Thread::initialize_thread_current() {
 326 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 327   assert(_thr_current == NULL, "Thread::current already initialized");
 328   _thr_current = this;
 329 #endif
 330   assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
 331   ThreadLocalStorage::set_thread(this);
 332   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 333 }
 334 
 335 void Thread::clear_thread_current() {
 336   assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
 337 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 338   _thr_current = NULL;
 339 #endif
 340   ThreadLocalStorage::set_thread(NULL);
 341 }
 342 
 343 void Thread::record_stack_base_and_size() {
 344   // Note: at this point, Thread object is not yet initialized. Do not rely on
 345   // any members being initialized. Do not rely on Thread::current() being set.
 346   // If possible, refrain from doing anything which may crash or assert since
 347   // quite probably those crash dumps will be useless.
 348   set_stack_base(os::current_stack_base());
 349   set_stack_size(os::current_stack_size());
 350 
 351   // Set stack limits after thread is initialized.
 352   if (is_Java_thread()) {
 353     as_Java_thread()->stack_overflow_state()->initialize(stack_base(), stack_end());
 354   }
 355 }
 356 
 357 #if INCLUDE_NMT
 358 void Thread::register_thread_stack_with_NMT() {
 359   MemTracker::record_thread_stack(stack_end(), stack_size());
 360 }
 361 
 362 void Thread::unregister_thread_stack_with_NMT() {
 363   MemTracker::release_thread_stack(stack_end(), stack_size());
 364 }
 365 #endif // INCLUDE_NMT
 366 
 367 void Thread::call_run() {
 368   DEBUG_ONLY(_run_state = CALL_RUN;)
 369 
 370   // At this point, Thread object should be fully initialized and
 371   // Thread::current() should be set.
 372 
 373   assert(Thread::current_or_null() != NULL, "current thread is unset");
 374   assert(Thread::current_or_null() == this, "current thread is wrong");
 375 
 376   // Perform common initialization actions
 377 
 378   MACOS_AARCH64_ONLY(this->init_wx());
 379 
 380   register_thread_stack_with_NMT();
 381 
 382   JFR_ONLY(Jfr::on_thread_start(this);)
 383 
 384   log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
 385     PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
 386     os::current_thread_id(), p2i(stack_end()),
 387     p2i(stack_base()), stack_size()/1024);
 388 
 389   // Perform <ChildClass> initialization actions
 390   DEBUG_ONLY(_run_state = PRE_RUN;)
 391   this->pre_run();
 392 
 393   // Invoke <ChildClass>::run()
 394   DEBUG_ONLY(_run_state = RUN;)
 395   this->run();
 396   // Returned from <ChildClass>::run(). Thread finished.
 397 
 398   // Perform common tear-down actions
 399 
 400   assert(Thread::current_or_null() != NULL, "current thread is unset");
 401   assert(Thread::current_or_null() == this, "current thread is wrong");
 402 
 403   // Perform <ChildClass> tear-down actions
 404   DEBUG_ONLY(_run_state = POST_RUN;)
 405   this->post_run();
 406 
 407   // Note: at this point the thread object may already have deleted itself,
 408   // so from here on do not dereference *this*. Not all thread types currently
 409   // delete themselves when they terminate. But no thread should ever be deleted
 410   // asynchronously with respect to its termination - that is what _run_state can
 411   // be used to check.
 412 
 413   assert(Thread::current_or_null() == NULL, "current thread still present");
 414 }
 415 
 416 Thread::~Thread() {
 417 
 418   // Attached threads will remain in PRE_CALL_RUN, as will threads that don't actually
 419   // get started due to errors etc. Any active thread should at least reach post_run
 420   // before it is deleted (usually in post_run()).
 421   assert(_run_state == PRE_CALL_RUN ||
 422          _run_state == POST_RUN, "Active Thread deleted before post_run(): "
 423          "_run_state=%d", (int)_run_state);
 424 
 425   // Notify the barrier set that a thread is being destroyed. Note that a barrier
 426   // set might not be available if we encountered errors during bootstrapping.
 427   BarrierSet* const barrier_set = BarrierSet::barrier_set();
 428   if (barrier_set != NULL) {
 429     barrier_set->on_thread_destroy(this);
 430   }
 431 
 432   // deallocate data structures
 433   delete resource_area();
 434   // since the handle marks are using the handle area, we have to deallocated the root
 435   // handle mark before deallocating the thread's handle area,
 436   assert(last_handle_mark() != NULL, "check we have an element");
 437   delete last_handle_mark();
 438   assert(last_handle_mark() == NULL, "check we have reached the end");
 439 
 440   ParkEvent::Release(_ParkEvent);
 441   // Set to NULL as a termination indicator for has_terminated().
 442   Atomic::store(&_ParkEvent, (ParkEvent*)NULL);
 443 
 444   delete handle_area();
 445   delete metadata_handles();
 446 
 447   // osthread() can be NULL, if creation of thread failed.
 448   if (osthread() != NULL) os::free_thread(osthread());
 449 
 450   // Clear Thread::current if thread is deleting itself and it has not
 451   // already been done. This must be done before the memory is deallocated.
 452   // Needed to ensure JNI correctly detects non-attached threads.
 453   if (this == Thread::current_or_null()) {
 454     Thread::clear_thread_current();
 455   }
 456 
 457   CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
 458 }
 459 
 460 #ifdef ASSERT
 461 // A JavaThread is considered dangling if it not handshake-safe with respect to
 462 // the current thread, it is not on a ThreadsList, or not at safepoint.
 463 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
 464   assert(!thread->is_Java_thread() ||
 465          thread->as_Java_thread()->is_handshake_safe_for(Thread::current()) ||
 466          !thread->as_Java_thread()->on_thread_list() ||
 467          SafepointSynchronize::is_at_safepoint() ||
 468          ThreadsSMRSupport::is_a_protected_JavaThread_with_lock(thread->as_Java_thread()),
 469          "possibility of dangling Thread pointer");
 470 }
 471 #endif
 472 
 473 // Is the target JavaThread protected by the calling Thread
 474 // or by some other mechanism:
 475 bool Thread::is_JavaThread_protected(const JavaThread* p) {
 476   // Do the simplest check first:
 477   if (SafepointSynchronize::is_at_safepoint()) {
 478     // The target is protected since JavaThreads cannot exit
 479     // while we're at a safepoint.
 480     return true;
 481   }
 482 
 483   // If the target hasn't been started yet then it is trivially
 484   // "protected". We assume the caller is the thread that will do
 485   // the starting.
 486   if (p->osthread() == NULL || p->osthread()->get_state() <= INITIALIZED) {
 487     return true;
 488   }
 489 
 490   // Now make the simple checks based on who the caller is:
 491   Thread* current_thread = Thread::current();
 492   if (current_thread == p || Threads_lock->owner() == current_thread) {
 493     // Target JavaThread is self or calling thread owns the Threads_lock.
 494     // Second check is the same as Threads_lock->owner_is_self(),
 495     // but we already have the current thread so check directly.
 496     return true;
 497   }
 498 
 499   // Check the ThreadsLists associated with the calling thread (if any)
 500   // to see if one of them protects the target JavaThread:
 501   for (SafeThreadsListPtr* stlp = current_thread->_threads_list_ptr;
 502        stlp != NULL; stlp = stlp->previous()) {
 503     if (stlp->list()->includes(p)) {
 504       // The target JavaThread is protected by this ThreadsList:
 505       return true;
 506     }
 507   }
 508 
 509   // Use this debug code with -XX:+UseNewCode to diagnose locations that
 510   // are missing a ThreadsListHandle or other protection mechanism:
 511   // guarantee(!UseNewCode, "current_thread=" INTPTR_FORMAT " is not protecting p="
 512   //           INTPTR_FORMAT, p2i(current_thread), p2i(p));
 513 
 514   // Note: Since 'p' isn't protected by a TLH, the call to
 515   // p->is_handshake_safe_for() may crash, but we have debug bits so
 516   // we'll be able to figure out what protection mechanism is missing.
 517   assert(p->is_handshake_safe_for(current_thread), "JavaThread=" INTPTR_FORMAT
 518          " is not protected and not handshake safe.", p2i(p));
 519 
 520   // The target JavaThread is not protected so it is not safe to query:
 521   return false;
 522 }
 523 
 524 ThreadPriority Thread::get_priority(const Thread* const thread) {
 525   ThreadPriority priority;
 526   // Can return an error!
 527   (void)os::get_priority(thread, priority);
 528   assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
 529   return priority;
 530 }
 531 
 532 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
 533   debug_only(check_for_dangling_thread_pointer(thread);)
 534   // Can return an error!
 535   (void)os::set_priority(thread, priority);
 536 }
 537 
 538 
 539 void Thread::start(Thread* thread) {
 540   // Start is different from resume in that its safety is guaranteed by context or
 541   // being called from a Java method synchronized on the Thread object.
 542   if (thread->is_Java_thread()) {
 543     // Initialize the thread state to RUNNABLE before starting this thread.
 544     // Can not set it after the thread started because we do not know the
 545     // exact thread state at that time. It could be in MONITOR_WAIT or
 546     // in SLEEPING or some other state.
 547     java_lang_Thread::set_thread_status(thread->as_Java_thread()->threadObj(),
 548                                         JavaThreadStatus::RUNNABLE);
 549   }
 550   os::start_thread(thread);
 551 }
 552 
 553 // GC Support
 554 bool Thread::claim_par_threads_do(uintx claim_token) {
 555   uintx token = _threads_do_token;
 556   if (token != claim_token) {
 557     uintx res = Atomic::cmpxchg(&_threads_do_token, token, claim_token);
 558     if (res == token) {
 559       return true;
 560     }
 561     guarantee(res == claim_token, "invariant");
 562   }
 563   return false;
 564 }
 565 
 566 void Thread::oops_do_no_frames(OopClosure* f, CodeBlobClosure* cf) {
 567   if (active_handles() != NULL) {
 568     active_handles()->oops_do(f);
 569   }
 570   // Do oop for ThreadShadow
 571   f->do_oop((oop*)&_pending_exception);
 572   handle_area()->oops_do(f);
 573 }
 574 
 575 // If the caller is a NamedThread, then remember, in the current scope,
 576 // the given JavaThread in its _processed_thread field.
 577 class RememberProcessedThread: public StackObj {
 578   NamedThread* _cur_thr;
 579 public:
 580   RememberProcessedThread(Thread* thread) {
 581     Thread* self = Thread::current();
 582     if (self->is_Named_thread()) {
 583       _cur_thr = (NamedThread *)self;
 584       assert(_cur_thr->processed_thread() == NULL, "nesting not supported");
 585       _cur_thr->set_processed_thread(thread);
 586     } else {
 587       _cur_thr = NULL;
 588     }
 589   }
 590 
 591   ~RememberProcessedThread() {
 592     if (_cur_thr) {
 593       assert(_cur_thr->processed_thread() != NULL, "nesting not supported");
 594       _cur_thr->set_processed_thread(NULL);
 595     }
 596   }
 597 };
 598 
 599 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
 600   // Record JavaThread to GC thread
 601   RememberProcessedThread rpt(this);
 602   oops_do_no_frames(f, cf);
 603   oops_do_frames(f, cf);
 604 }
 605 
 606 void Thread::metadata_handles_do(void f(Metadata*)) {
 607   // Only walk the Handles in Thread.
 608   if (metadata_handles() != NULL) {
 609     for (int i = 0; i< metadata_handles()->length(); i++) {
 610       f(metadata_handles()->at(i));
 611     }
 612   }
 613 }
 614 
 615 void Thread::print_on(outputStream* st, bool print_extended_info) const {
 616   // get_priority assumes osthread initialized
 617   if (osthread() != NULL) {
 618     int os_prio;
 619     if (os::get_native_priority(this, &os_prio) == OS_OK) {
 620       st->print("os_prio=%d ", os_prio);
 621     }
 622 
 623     st->print("cpu=%.2fms ",
 624               os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0
 625               );
 626     st->print("elapsed=%.2fs ",
 627               _statistical_info.getElapsedTime() / 1000.0
 628               );
 629     if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) {
 630       size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes();
 631       st->print("allocated=" SIZE_FORMAT "%s ",
 632                 byte_size_in_proper_unit(allocated_bytes),
 633                 proper_unit_for_byte_size(allocated_bytes)
 634                 );
 635       st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount());
 636     }
 637 
 638     st->print("tid=" INTPTR_FORMAT " ", p2i(this));
 639     osthread()->print_on(st);
 640   }
 641   ThreadsSMRSupport::print_info_on(this, st);
 642   st->print(" ");
 643   debug_only(if (WizardMode) print_owned_locks_on(st);)
 644 }
 645 
 646 void Thread::print() const { print_on(tty); }
 647 
 648 // Thread::print_on_error() is called by fatal error handler. Don't use
 649 // any lock or allocate memory.
 650 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
 651   assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
 652 
 653   if (is_VM_thread())                 { st->print("VMThread"); }
 654   else if (is_GC_task_thread())       { st->print("GCTaskThread"); }
 655   else if (is_Watcher_thread())       { st->print("WatcherThread"); }
 656   else if (is_ConcurrentGC_thread())  { st->print("ConcurrentGCThread"); }
 657   else                                { st->print("Thread"); }
 658 
 659   if (is_Named_thread()) {
 660     st->print(" \"%s\"", name());
 661   }
 662 
 663   OSThread* os_thr = osthread();
 664   if (os_thr != NULL) {
 665     if (os_thr->get_state() != ZOMBIE) {
 666       st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
 667                 p2i(stack_end()), p2i(stack_base()));
 668       st->print(" [id=%d]", osthread()->thread_id());
 669     } else {
 670       st->print(" terminated");
 671     }
 672   } else {
 673     st->print(" unknown state (no osThread)");
 674   }
 675   ThreadsSMRSupport::print_info_on(this, st);
 676 }
 677 
 678 void Thread::print_value_on(outputStream* st) const {
 679   if (is_Named_thread()) {
 680     st->print(" \"%s\" ", name());
 681   }
 682   st->print(INTPTR_FORMAT, p2i(this));   // print address
 683 }
 684 
 685 #ifdef ASSERT
 686 void Thread::print_owned_locks_on(outputStream* st) const {
 687   Mutex* cur = _owned_locks;
 688   if (cur == NULL) {
 689     st->print(" (no locks) ");
 690   } else {
 691     st->print_cr(" Locks owned:");
 692     while (cur) {
 693       cur->print_on(st);
 694       cur = cur->next();
 695     }
 696   }
 697 }
 698 #endif // ASSERT
 699 
 700 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
 701 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
 702 // used for compilation in the future. If that change is made, the need for these methods
 703 // should be revisited, and they should be removed if possible.
 704 
 705 bool Thread::is_lock_owned(address adr) const {
 706   assert(!UseFastLocking, "maybe not call that?");
 707   return is_in_full_stack(adr);
 708 }
 709 
 710 bool Thread::set_as_starting_thread() {
 711   assert(_starting_thread == NULL, "already initialized: "
 712          "_starting_thread=" INTPTR_FORMAT, p2i(_starting_thread));
 713   // NOTE: this must be called inside the main thread.
 714   DEBUG_ONLY(_starting_thread = this;)
 715   return os::create_main_thread(this->as_Java_thread());
 716 }
 717 
 718 static void initialize_class(Symbol* class_name, TRAPS) {
 719   Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
 720   InstanceKlass::cast(klass)->initialize(CHECK);
 721 }
 722 
 723 
 724 // Creates the initial ThreadGroup
 725 static Handle create_initial_thread_group(TRAPS) {
 726   Handle system_instance = JavaCalls::construct_new_instance(
 727                             vmClasses::ThreadGroup_klass(),
 728                             vmSymbols::void_method_signature(),
 729                             CHECK_NH);
 730   Universe::set_system_thread_group(system_instance());
 731 
 732   Handle string = java_lang_String::create_from_str("main", CHECK_NH);
 733   Handle main_instance = JavaCalls::construct_new_instance(
 734                             vmClasses::ThreadGroup_klass(),
 735                             vmSymbols::threadgroup_string_void_signature(),
 736                             system_instance,
 737                             string,
 738                             CHECK_NH);
 739   return main_instance;
 740 }
 741 
 742 // Creates the initial Thread, and sets it to running.
 743 static void create_initial_thread(Handle thread_group, JavaThread* thread,
 744                                  TRAPS) {
 745   InstanceKlass* ik = vmClasses::Thread_klass();
 746   assert(ik->is_initialized(), "must be");
 747   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
 748 
 749   // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread
 750   // constructor calls Thread.current(), which must be set here for the
 751   // initial thread.
 752   java_lang_Thread::set_thread(thread_oop(), thread);
 753   java_lang_Thread::set_priority(thread_oop(), NormPriority);
 754   thread->set_threadObj(thread_oop());
 755 
 756   Handle string = java_lang_String::create_from_str("main", CHECK);
 757 
 758   JavaValue result(T_VOID);
 759   JavaCalls::call_special(&result, thread_oop,
 760                           ik,
 761                           vmSymbols::object_initializer_name(),
 762                           vmSymbols::threadgroup_string_void_signature(),
 763                           thread_group,
 764                           string,
 765                           CHECK);
 766 
 767   // Set thread status to running since main thread has
 768   // been started and running.
 769   java_lang_Thread::set_thread_status(thread_oop(),
 770                                       JavaThreadStatus::RUNNABLE);
 771 }
 772 
 773 // Extract version and vendor specific information from
 774 // java.lang.VersionProps fields.
 775 // Returned char* is allocated in the thread's resource area
 776 // so must be copied for permanency.
 777 static const char* get_java_version_info(InstanceKlass* ik,
 778                                          Symbol* field_name) {
 779   fieldDescriptor fd;
 780   bool found = ik != NULL &&
 781                ik->find_local_field(field_name,
 782                                     vmSymbols::string_signature(), &fd);
 783   if (found) {
 784     oop name_oop = ik->java_mirror()->obj_field(fd.offset());
 785     if (name_oop == NULL) {
 786       return NULL;
 787     }
 788     const char* name = java_lang_String::as_utf8_string(name_oop);
 789     return name;
 790   } else {
 791     return NULL;
 792   }
 793 }
 794 
 795 // General purpose hook into Java code, run once when the VM is initialized.
 796 // The Java library method itself may be changed independently from the VM.
 797 static void call_postVMInitHook(TRAPS) {
 798   Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
 799   if (klass != NULL) {
 800     JavaValue result(T_VOID);
 801     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
 802                            vmSymbols::void_method_signature(),
 803                            CHECK);
 804   }
 805 }
 806 
 807 // Initialized by VMThread at vm_global_init
 808 static OopStorage* _thread_oop_storage = NULL;
 809 
 810 oop  JavaThread::threadObj() const    {
 811   return _threadObj.resolve();
 812 }
 813 
 814 void JavaThread::set_threadObj(oop p) {
 815   assert(_thread_oop_storage != NULL, "not yet initialized");
 816   _threadObj = OopHandle(_thread_oop_storage, p);
 817 }
 818 
 819 OopStorage* JavaThread::thread_oop_storage() {
 820   assert(_thread_oop_storage != NULL, "not yet initialized");
 821   return _thread_oop_storage;
 822 }
 823 
 824 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
 825                                     bool daemon, TRAPS) {
 826   assert(thread_group.not_null(), "thread group should be specified");
 827   assert(threadObj() == NULL, "should only create Java thread object once");
 828 
 829   InstanceKlass* ik = vmClasses::Thread_klass();
 830   assert(ik->is_initialized(), "must be");
 831   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
 832 
 833   // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon.
 834   // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread
 835   // constructor calls Thread.current(), which must be set here.
 836   java_lang_Thread::set_thread(thread_oop(), this);
 837   java_lang_Thread::set_priority(thread_oop(), NormPriority);
 838   set_threadObj(thread_oop());
 839 
 840   JavaValue result(T_VOID);
 841   if (thread_name != NULL) {
 842     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
 843     // Thread gets assigned specified name and null target
 844     JavaCalls::call_special(&result,
 845                             thread_oop,
 846                             ik,
 847                             vmSymbols::object_initializer_name(),
 848                             vmSymbols::threadgroup_string_void_signature(),
 849                             thread_group,
 850                             name,
 851                             THREAD);
 852   } else {
 853     // Thread gets assigned name "Thread-nnn" and null target
 854     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
 855     JavaCalls::call_special(&result,
 856                             thread_oop,
 857                             ik,
 858                             vmSymbols::object_initializer_name(),
 859                             vmSymbols::threadgroup_runnable_void_signature(),
 860                             thread_group,
 861                             Handle(),
 862                             THREAD);
 863   }
 864 
 865 
 866   if (daemon) {
 867     java_lang_Thread::set_daemon(thread_oop());
 868   }
 869 
 870   if (HAS_PENDING_EXCEPTION) {
 871     return;
 872   }
 873 
 874   Klass* group = vmClasses::ThreadGroup_klass();
 875   Handle threadObj(THREAD, this->threadObj());
 876 
 877   JavaCalls::call_special(&result,
 878                           thread_group,
 879                           group,
 880                           vmSymbols::add_method_name(),
 881                           vmSymbols::thread_void_signature(),
 882                           threadObj,          // Arg 1
 883                           THREAD);
 884 }
 885 
 886 // ======= JavaThread ========
 887 
 888 #if INCLUDE_JVMCI
 889 
 890 jlong* JavaThread::_jvmci_old_thread_counters;
 891 
 892 bool jvmci_counters_include(JavaThread* thread) {
 893   return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
 894 }
 895 
 896 void JavaThread::collect_counters(jlong* array, int length) {
 897   assert(length == JVMCICounterSize, "wrong value");
 898   for (int i = 0; i < length; i++) {
 899     array[i] = _jvmci_old_thread_counters[i];
 900   }
 901   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) {
 902     if (jvmci_counters_include(tp)) {
 903       for (int i = 0; i < length; i++) {
 904         array[i] += tp->_jvmci_counters[i];
 905       }
 906     }
 907   }
 908 }
 909 
 910 // Attempt to enlarge the array for per thread counters.
 911 jlong* resize_counters_array(jlong* old_counters, int current_size, int new_size) {
 912   jlong* new_counters = NEW_C_HEAP_ARRAY_RETURN_NULL(jlong, new_size, mtJVMCI);
 913   if (new_counters == NULL) {
 914     return NULL;
 915   }
 916   if (old_counters == NULL) {
 917     old_counters = new_counters;
 918     memset(old_counters, 0, sizeof(jlong) * new_size);
 919   } else {
 920     for (int i = 0; i < MIN2((int) current_size, new_size); i++) {
 921       new_counters[i] = old_counters[i];
 922     }
 923     if (new_size > current_size) {
 924       memset(new_counters + current_size, 0, sizeof(jlong) * (new_size - current_size));
 925     }
 926     FREE_C_HEAP_ARRAY(jlong, old_counters);
 927   }
 928   return new_counters;
 929 }
 930 
 931 // Attempt to enlarge the array for per thread counters.
 932 bool JavaThread::resize_counters(int current_size, int new_size) {
 933   jlong* new_counters = resize_counters_array(_jvmci_counters, current_size, new_size);
 934   if (new_counters == NULL) {
 935     return false;
 936   } else {
 937     _jvmci_counters = new_counters;
 938     return true;
 939   }
 940 }
 941 
 942 class VM_JVMCIResizeCounters : public VM_Operation {
 943  private:
 944   int _new_size;
 945   bool _failed;
 946 
 947  public:
 948   VM_JVMCIResizeCounters(int new_size) : _new_size(new_size), _failed(false) { }
 949   VMOp_Type type()                  const        { return VMOp_JVMCIResizeCounters; }
 950   bool allow_nested_vm_operations() const        { return true; }
 951   void doit() {
 952     // Resize the old thread counters array
 953     jlong* new_counters = resize_counters_array(JavaThread::_jvmci_old_thread_counters, JVMCICounterSize, _new_size);
 954     if (new_counters == NULL) {
 955       _failed = true;
 956       return;
 957     } else {
 958       JavaThread::_jvmci_old_thread_counters = new_counters;
 959     }
 960 
 961     // Now resize each threads array
 962     for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) {
 963       if (!tp->resize_counters(JVMCICounterSize, _new_size)) {
 964         _failed = true;
 965         break;
 966       }
 967     }
 968     if (!_failed) {
 969       JVMCICounterSize = _new_size;
 970     }
 971   }
 972 
 973   bool failed() { return _failed; }
 974 };
 975 
 976 bool JavaThread::resize_all_jvmci_counters(int new_size) {
 977   VM_JVMCIResizeCounters op(new_size);
 978   VMThread::execute(&op);
 979   return !op.failed();
 980 }
 981 
 982 #endif // INCLUDE_JVMCI
 983 
 984 #ifdef ASSERT
 985 // Checks safepoint allowed and clears unhandled oops at potential safepoints.
 986 void JavaThread::check_possible_safepoint() {
 987   if (_no_safepoint_count > 0) {
 988     print_owned_locks();
 989     assert(false, "Possible safepoint reached by thread that does not allow it");
 990   }
 991 #ifdef CHECK_UNHANDLED_OOPS
 992   // Clear unhandled oops in JavaThreads so we get a crash right away.
 993   clear_unhandled_oops();
 994 #endif // CHECK_UNHANDLED_OOPS
 995 }
 996 
 997 void JavaThread::check_for_valid_safepoint_state() {
 998   // Check NoSafepointVerifier, which is implied by locks taken that can be
 999   // shared with the VM thread.  This makes sure that no locks with allow_vm_block
1000   // are held.
1001   check_possible_safepoint();
1002 
1003   if (thread_state() != _thread_in_vm) {
1004     fatal("LEAF method calling lock?");
1005   }
1006 
1007   if (GCALotAtAllSafepoints) {
1008     // We could enter a safepoint here and thus have a gc
1009     InterfaceSupport::check_gc_alot();
1010   }
1011 }
1012 #endif // ASSERT
1013 
1014 // A JavaThread is a normal Java thread
1015 
1016 JavaThread::JavaThread() :
1017   // Initialize fields
1018 
1019   _in_asgct(false),
1020   _on_thread_list(false),
1021   DEBUG_ONLY(_java_call_counter(0) COMMA)
1022   _entry_point(nullptr),
1023   _deopt_mark(nullptr),
1024   _deopt_nmethod(nullptr),
1025   _vframe_array_head(nullptr),
1026   _vframe_array_last(nullptr),
1027   _jvmti_deferred_updates(nullptr),
1028   _callee_target(nullptr),
1029   _vm_result(nullptr),
1030   _vm_result_2(nullptr),
1031 
1032   _current_pending_monitor(NULL),
1033   _current_pending_monitor_is_from_java(true),
1034   _current_waiting_monitor(NULL),
1035   _Stalled(0),
1036 
1037   _monitor_chunks(nullptr),
1038 
1039   _suspend_flags(0),
1040   _async_exception_condition(_no_async_condition),
1041   _pending_async_exception(nullptr),
1042 
1043   _thread_state(_thread_new),
1044   _saved_exception_pc(nullptr),
1045 #ifdef ASSERT
1046   _no_safepoint_count(0),
1047   _visited_for_critical_count(false),
1048 #endif
1049 
1050   _terminated(_not_terminated),
1051   _in_deopt_handler(0),
1052   _doing_unsafe_access(false),
1053   _do_not_unlock_if_synchronized(false),
1054   _jni_attach_state(_not_attaching_via_jni),
1055 #if INCLUDE_JVMCI
1056   _pending_deoptimization(-1),
1057   _pending_monitorenter(false),
1058   _pending_transfer_to_interpreter(false),
1059   _in_retryable_allocation(false),
1060   _pending_failed_speculation(0),
1061   _jvmci{nullptr},
1062   _jvmci_counters(nullptr),
1063   _jvmci_reserved0(0),
1064   _jvmci_reserved1(0),
1065   _jvmci_reserved_oop0(nullptr),
1066 #endif // INCLUDE_JVMCI
1067 
1068   _exception_oop(oop()),
1069   _exception_pc(0),
1070   _exception_handler_pc(0),
1071   _is_method_handle_return(0),
1072 
1073   _jni_active_critical(0),
1074   _pending_jni_exception_check_fn(nullptr),
1075   _depth_first_number(0),
1076 
1077   // JVMTI PopFrame support
1078   _popframe_condition(popframe_inactive),
1079   _frames_to_pop_failed_realloc(0),
1080 
1081   _handshake(this),
1082 
1083   _popframe_preserved_args(nullptr),
1084   _popframe_preserved_args_size(0),
1085 
1086   _jvmti_thread_state(nullptr),
1087   _interp_only_mode(0),
1088   _should_post_on_exceptions_flag(JNI_FALSE),
1089   _thread_stat(new ThreadStatistics()),
1090 
1091   _parker(),
1092   _cached_monitor_info(nullptr),
1093 
1094   _class_to_be_initialized(nullptr),
1095 
1096   _SleepEvent(ParkEvent::Allocate(this)),
1097   _lock_stack()
1098 {
1099   set_jni_functions(jni_functions());
1100 
1101 #if INCLUDE_JVMCI
1102   assert(_jvmci._implicit_exception_pc == nullptr, "must be");
1103   if (JVMCICounterSize > 0) {
1104     resize_counters(0, (int) JVMCICounterSize);
1105   }
1106 #endif // INCLUDE_JVMCI
1107 
1108   // Setup safepoint state info for this thread
1109   ThreadSafepointState::create(this);
1110 
1111   SafepointMechanism::initialize_header(this);
1112 
1113   set_requires_cross_modify_fence(false);
1114 
1115   pd_initialize();
1116   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1117 }
1118 
1119 JavaThread::JavaThread(bool is_attaching_via_jni) : JavaThread() {
1120   if (is_attaching_via_jni) {
1121     _jni_attach_state = _attaching_via_jni;
1122   }
1123 }
1124 
1125 
1126 // interrupt support
1127 
1128 void JavaThread::interrupt() {
1129   // All callers should have 'this' thread protected by a
1130   // ThreadsListHandle so that it cannot terminate and deallocate
1131   // itself.
1132   debug_only(check_for_dangling_thread_pointer(this);)
1133 
1134   // For Windows _interrupt_event
1135   osthread()->set_interrupted(true);
1136 
1137   // For Thread.sleep
1138   _SleepEvent->unpark();
1139 
1140   // For JSR166 LockSupport.park
1141   parker()->unpark();
1142 
1143   // For ObjectMonitor and JvmtiRawMonitor
1144   _ParkEvent->unpark();
1145 }
1146 
1147 
1148 bool JavaThread::is_interrupted(bool clear_interrupted) {
1149   debug_only(check_for_dangling_thread_pointer(this);)
1150 
1151   if (_threadObj.peek() == NULL) {
1152     // If there is no j.l.Thread then it is impossible to have
1153     // been interrupted. We can find NULL during VM initialization
1154     // or when a JNI thread is still in the process of attaching.
1155     // In such cases this must be the current thread.
1156     assert(this == Thread::current(), "invariant");
1157     return false;
1158   }
1159 
1160   bool interrupted = java_lang_Thread::interrupted(threadObj());
1161 
1162   // NOTE that since there is no "lock" around the interrupt and
1163   // is_interrupted operations, there is the possibility that the
1164   // interrupted flag will be "false" but that the
1165   // low-level events will be in the signaled state. This is
1166   // intentional. The effect of this is that Object.wait() and
1167   // LockSupport.park() will appear to have a spurious wakeup, which
1168   // is allowed and not harmful, and the possibility is so rare that
1169   // it is not worth the added complexity to add yet another lock.
1170   // For the sleep event an explicit reset is performed on entry
1171   // to JavaThread::sleep, so there is no early return. It has also been
1172   // recommended not to put the interrupted flag into the "event"
1173   // structure because it hides the issue.
1174   // Also, because there is no lock, we must only clear the interrupt
1175   // state if we are going to report that we were interrupted; otherwise
1176   // an interrupt that happens just after we read the field would be lost.
1177   if (interrupted && clear_interrupted) {
1178     assert(this == Thread::current(), "only the current thread can clear");
1179     java_lang_Thread::set_interrupted(threadObj(), false);
1180     osthread()->set_interrupted(false);
1181   }
1182 
1183   return interrupted;
1184 }
1185 
1186 void JavaThread::block_if_vm_exited() {
1187   if (_terminated == _vm_exited) {
1188     // _vm_exited is set at safepoint, and Threads_lock is never released
1189     // we will block here forever.
1190     // Here we can be doing a jump from a safe state to an unsafe state without
1191     // proper transition, but it happens after the final safepoint has begun.
1192     set_thread_state(_thread_in_vm);
1193     Threads_lock->lock();
1194     ShouldNotReachHere();
1195   }
1196 }
1197 
1198 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : JavaThread() {
1199   _jni_attach_state = _not_attaching_via_jni;
1200   set_entry_point(entry_point);
1201   // Create the native thread itself.
1202   // %note runtime_23
1203   os::ThreadType thr_type = os::java_thread;
1204   thr_type = entry_point == &CompilerThread::thread_entry ? os::compiler_thread :
1205                                                             os::java_thread;
1206   os::create_thread(this, thr_type, stack_sz);
1207   // The _osthread may be NULL here because we ran out of memory (too many threads active).
1208   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1209   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1210   // the exception consists of creating the exception object & initializing it, initialization
1211   // will leave the VM via a JavaCall and then all locks must be unlocked).
1212   //
1213   // The thread is still suspended when we reach here. Thread must be explicit started
1214   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1215   // by calling Threads:add. The reason why this is not done here, is because the thread
1216   // object must be fully initialized (take a look at JVM_Start)
1217 }
1218 
1219 JavaThread::~JavaThread() {
1220 
1221   // Ask ServiceThread to release the threadObj OopHandle
1222   ServiceThread::add_oop_handle_release(_threadObj);
1223 
1224   // Return the sleep event to the free list
1225   ParkEvent::Release(_SleepEvent);
1226   _SleepEvent = NULL;
1227 
1228   // Free any remaining  previous UnrollBlock
1229   vframeArray* old_array = vframe_array_last();
1230 
1231   if (old_array != NULL) {
1232     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1233     old_array->set_unroll_block(NULL);
1234     delete old_info;
1235     delete old_array;
1236   }
1237 
1238   JvmtiDeferredUpdates* updates = deferred_updates();
1239   if (updates != NULL) {
1240     // This can only happen if thread is destroyed before deoptimization occurs.
1241     assert(updates->count() > 0, "Updates holder not deleted");
1242     // free deferred updates.
1243     delete updates;
1244     set_deferred_updates(NULL);
1245   }
1246 
1247   // All Java related clean up happens in exit
1248   ThreadSafepointState::destroy(this);
1249   if (_thread_stat != NULL) delete _thread_stat;
1250 
1251 #if INCLUDE_JVMCI
1252   if (JVMCICounterSize > 0) {
1253     FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1254   }
1255 #endif // INCLUDE_JVMCI
1256 }
1257 
1258 
1259 // First JavaThread specific code executed by a new Java thread.
1260 void JavaThread::pre_run() {
1261   // empty - see comments in run()
1262 }
1263 
1264 // The main routine called by a new Java thread. This isn't overridden
1265 // by subclasses, instead different subclasses define a different "entry_point"
1266 // which defines the actual logic for that kind of thread.
1267 void JavaThread::run() {
1268   // initialize thread-local alloc buffer related fields
1269   initialize_tlab();
1270 
1271   _stack_overflow_state.create_stack_guard_pages();
1272 
1273   cache_global_variables();
1274 
1275   // Thread is now sufficiently initialized to be handled by the safepoint code as being
1276   // in the VM. Change thread state from _thread_new to _thread_in_vm
1277   ThreadStateTransition::transition(this, _thread_new, _thread_in_vm);
1278   // Before a thread is on the threads list it is always safe, so after leaving the
1279   // _thread_new we should emit a instruction barrier. The distance to modified code
1280   // from here is probably far enough, but this is consistent and safe.
1281   OrderAccess::cross_modify_fence();
1282 
1283   assert(JavaThread::current() == this, "sanity check");
1284   assert(!Thread::current()->owns_locks(), "sanity check");
1285 
1286   DTRACE_THREAD_PROBE(start, this);
1287 
1288   // This operation might block. We call that after all safepoint checks for a new thread has
1289   // been completed.
1290   set_active_handles(JNIHandleBlock::allocate_block());
1291 
1292   if (JvmtiExport::should_post_thread_life()) {
1293     JvmtiExport::post_thread_start(this);
1294 
1295   }
1296 
1297   // We call another function to do the rest so we are sure that the stack addresses used
1298   // from there will be lower than the stack base just computed.
1299   thread_main_inner();
1300 }
1301 
1302 void JavaThread::thread_main_inner() {
1303   assert(JavaThread::current() == this, "sanity check");
1304   assert(_threadObj.peek() != NULL, "just checking");
1305 
1306   // Execute thread entry point unless this thread has a pending exception
1307   // or has been stopped before starting.
1308   // Note: Due to JVM_StopThread we can have pending exceptions already!
1309   if (!this->has_pending_exception() &&
1310       !java_lang_Thread::is_stillborn(this->threadObj())) {
1311     {
1312       ResourceMark rm(this);
1313       this->set_native_thread_name(this->get_thread_name());
1314     }
1315     HandleMark hm(this);
1316     this->entry_point()(this, this);
1317   }
1318 
1319   DTRACE_THREAD_PROBE(stop, this);
1320 
1321   // Cleanup is handled in post_run()
1322 }
1323 
1324 // Shared teardown for all JavaThreads
1325 void JavaThread::post_run() {
1326   this->exit(false);
1327   this->unregister_thread_stack_with_NMT();
1328   // Defer deletion to here to ensure 'this' is still referenceable in call_run
1329   // for any shared tear-down.
1330   this->smr_delete();
1331 }
1332 
1333 static void ensure_join(JavaThread* thread) {
1334   // We do not need to grab the Threads_lock, since we are operating on ourself.
1335   Handle threadObj(thread, thread->threadObj());
1336   assert(threadObj.not_null(), "java thread object must exist");
1337   ObjectLocker lock(threadObj, thread);
1338   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1339   thread->clear_pending_exception();
1340   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
1341   java_lang_Thread::set_thread_status(threadObj(), JavaThreadStatus::TERMINATED);
1342   // Clear the native thread instance - this makes isAlive return false and allows the join()
1343   // to complete once we've done the notify_all below
1344   java_lang_Thread::set_thread(threadObj(), NULL);
1345   lock.notify_all(thread);
1346   // Ignore pending exception (ThreadDeath), since we are exiting anyway
1347   thread->clear_pending_exception();
1348 }
1349 
1350 static bool is_daemon(oop threadObj) {
1351   return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj));
1352 }
1353 
1354 // For any new cleanup additions, please check to see if they need to be applied to
1355 // cleanup_failed_attach_current_thread as well.
1356 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1357   assert(this == JavaThread::current(), "thread consistency check");
1358 
1359   elapsedTimer _timer_exit_phase1;
1360   elapsedTimer _timer_exit_phase2;
1361   elapsedTimer _timer_exit_phase3;
1362   elapsedTimer _timer_exit_phase4;
1363 
1364   if (log_is_enabled(Debug, os, thread, timer)) {
1365     _timer_exit_phase1.start();
1366   }
1367 
1368   HandleMark hm(this);
1369   Handle uncaught_exception(this, this->pending_exception());
1370   this->clear_pending_exception();
1371   Handle threadObj(this, this->threadObj());
1372   assert(threadObj.not_null(), "Java thread object should be created");
1373 
1374   if (!destroy_vm) {
1375     if (uncaught_exception.not_null()) {
1376       EXCEPTION_MARK;
1377       // Call method Thread.dispatchUncaughtException().
1378       Klass* thread_klass = vmClasses::Thread_klass();
1379       JavaValue result(T_VOID);
1380       JavaCalls::call_virtual(&result,
1381                               threadObj, thread_klass,
1382                               vmSymbols::dispatchUncaughtException_name(),
1383                               vmSymbols::throwable_void_signature(),
1384                               uncaught_exception,
1385                               THREAD);
1386       if (HAS_PENDING_EXCEPTION) {
1387         ResourceMark rm(this);
1388         jio_fprintf(defaultStream::error_stream(),
1389                     "\nException: %s thrown from the UncaughtExceptionHandler"
1390                     " in thread \"%s\"\n",
1391                     pending_exception()->klass()->external_name(),
1392                     get_thread_name());
1393         CLEAR_PENDING_EXCEPTION;
1394       }
1395     }
1396 
1397     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1398     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1399     // is deprecated anyhow.
1400     if (!is_Compiler_thread()) {
1401       int count = 3;
1402       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1403         EXCEPTION_MARK;
1404         JavaValue result(T_VOID);
1405         Klass* thread_klass = vmClasses::Thread_klass();
1406         JavaCalls::call_virtual(&result,
1407                                 threadObj, thread_klass,
1408                                 vmSymbols::exit_method_name(),
1409                                 vmSymbols::void_method_signature(),
1410                                 THREAD);
1411         CLEAR_PENDING_EXCEPTION;
1412       }
1413     }
1414     // notify JVMTI
1415     if (JvmtiExport::should_post_thread_life()) {
1416       JvmtiExport::post_thread_end(this);
1417     }
1418 
1419     // The careful dance between thread suspension and exit is handled here.
1420     // Since we are in thread_in_vm state and suspension is done with handshakes,
1421     // we can just put in the exiting state and it will be correctly handled.
1422     set_terminated(_thread_exiting);
1423 
1424     ThreadService::current_thread_exiting(this, is_daemon(threadObj()));
1425   } else {
1426     assert(!is_terminated() && !is_exiting(), "must not be exiting");
1427     // before_exit() has already posted JVMTI THREAD_END events
1428   }
1429 
1430   if (log_is_enabled(Debug, os, thread, timer)) {
1431     _timer_exit_phase1.stop();
1432     _timer_exit_phase2.start();
1433   }
1434 
1435   // Capture daemon status before the thread is marked as terminated.
1436   bool daemon = is_daemon(threadObj());
1437 
1438   // Notify waiters on thread object. This has to be done after exit() is called
1439   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1440   // group should have the destroyed bit set before waiters are notified).
1441   ensure_join(this);
1442   assert(!this->has_pending_exception(), "ensure_join should have cleared");
1443 
1444   if (log_is_enabled(Debug, os, thread, timer)) {
1445     _timer_exit_phase2.stop();
1446     _timer_exit_phase3.start();
1447   }
1448   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1449   // held by this thread must be released. The spec does not distinguish
1450   // between JNI-acquired and regular Java monitors. We can only see
1451   // regular Java monitors here if monitor enter-exit matching is broken.
1452   //
1453   // ensure_join() ignores IllegalThreadStateExceptions, and so does
1454   // ObjectSynchronizer::release_monitors_owned_by_thread().
1455   if (exit_type == jni_detach) {
1456     // Sanity check even though JNI DetachCurrentThread() would have
1457     // returned JNI_ERR if there was a Java frame. JavaThread exit
1458     // should be done executing Java code by the time we get here.
1459     assert(!this->has_last_Java_frame(),
1460            "should not have a Java frame when detaching or exiting");
1461     ObjectSynchronizer::release_monitors_owned_by_thread(this);
1462     assert(!this->has_pending_exception(), "release_monitors should have cleared");
1463   }
1464 
1465   // These things needs to be done while we are still a Java Thread. Make sure that thread
1466   // is in a consistent state, in case GC happens
1467   JFR_ONLY(Jfr::on_thread_exit(this);)
1468 
1469   if (active_handles() != NULL) {
1470     JNIHandleBlock* block = active_handles();
1471     set_active_handles(NULL);
1472     JNIHandleBlock::release_block(block);
1473   }
1474 
1475   if (free_handle_block() != NULL) {
1476     JNIHandleBlock* block = free_handle_block();
1477     set_free_handle_block(NULL);
1478     JNIHandleBlock::release_block(block);
1479   }
1480 
1481   // These have to be removed while this is still a valid thread.
1482   _stack_overflow_state.remove_stack_guard_pages();
1483 
1484   if (UseTLAB) {
1485     tlab().retire();
1486   }
1487 
1488   if (JvmtiEnv::environments_might_exist()) {
1489     JvmtiExport::cleanup_thread(this);
1490   }
1491 
1492   // We need to cache the thread name for logging purposes below as once
1493   // we have called on_thread_detach this thread must not access any oops.
1494   char* thread_name = NULL;
1495   if (log_is_enabled(Debug, os, thread, timer)) {
1496     ResourceMark rm(this);
1497     thread_name = os::strdup(get_thread_name());
1498   }
1499 
1500   log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
1501     exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
1502     os::current_thread_id());
1503 
1504   if (log_is_enabled(Debug, os, thread, timer)) {
1505     _timer_exit_phase3.stop();
1506     _timer_exit_phase4.start();
1507   }
1508 
1509 #if INCLUDE_JVMCI
1510   if (JVMCICounterSize > 0) {
1511     if (jvmci_counters_include(this)) {
1512       for (int i = 0; i < JVMCICounterSize; i++) {
1513         _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1514       }
1515     }
1516   }
1517 #endif // INCLUDE_JVMCI
1518 
1519   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1520   Threads::remove(this, daemon);
1521 
1522   if (log_is_enabled(Debug, os, thread, timer)) {
1523     _timer_exit_phase4.stop();
1524     log_debug(os, thread, timer)("name='%s'"
1525                                  ", exit-phase1=" JLONG_FORMAT
1526                                  ", exit-phase2=" JLONG_FORMAT
1527                                  ", exit-phase3=" JLONG_FORMAT
1528                                  ", exit-phase4=" JLONG_FORMAT,
1529                                  thread_name,
1530                                  _timer_exit_phase1.milliseconds(),
1531                                  _timer_exit_phase2.milliseconds(),
1532                                  _timer_exit_phase3.milliseconds(),
1533                                  _timer_exit_phase4.milliseconds());
1534     os::free(thread_name);
1535   }
1536 }
1537 
1538 void JavaThread::cleanup_failed_attach_current_thread(bool is_daemon) {
1539   if (active_handles() != NULL) {
1540     JNIHandleBlock* block = active_handles();
1541     set_active_handles(NULL);
1542     JNIHandleBlock::release_block(block);
1543   }
1544 
1545   if (free_handle_block() != NULL) {
1546     JNIHandleBlock* block = free_handle_block();
1547     set_free_handle_block(NULL);
1548     JNIHandleBlock::release_block(block);
1549   }
1550 
1551   // These have to be removed while this is still a valid thread.
1552   _stack_overflow_state.remove_stack_guard_pages();
1553 
1554   if (UseTLAB) {
1555     tlab().retire();
1556   }
1557 
1558   Threads::remove(this, is_daemon);
1559   this->smr_delete();
1560 }
1561 
1562 JavaThread* JavaThread::active() {
1563   Thread* thread = Thread::current();
1564   if (thread->is_Java_thread()) {
1565     return thread->as_Java_thread();
1566   } else {
1567     assert(thread->is_VM_thread(), "this must be a vm thread");
1568     VM_Operation* op = ((VMThread*) thread)->vm_operation();
1569     JavaThread *ret = op == NULL ? NULL : op->calling_thread()->as_Java_thread();
1570     return ret;
1571   }
1572 }
1573 
1574 bool JavaThread::is_lock_owned(address adr) const {
1575   assert(!UseFastLocking, "should not be called with fast-locking");
1576  if (Thread::is_lock_owned(adr)) return true;
1577 
1578   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
1579     if (chunk->contains(adr)) return true;
1580   }
1581 
1582   return false;
1583 }
1584 
1585 oop JavaThread::exception_oop() const {
1586   return Atomic::load(&_exception_oop);
1587 }
1588 
1589 void JavaThread::set_exception_oop(oop o) {
1590   Atomic::store(&_exception_oop, o);
1591 }
1592 
1593 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
1594   chunk->set_next(monitor_chunks());
1595   set_monitor_chunks(chunk);
1596 }
1597 
1598 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
1599   guarantee(monitor_chunks() != NULL, "must be non empty");
1600   if (monitor_chunks() == chunk) {
1601     set_monitor_chunks(chunk->next());
1602   } else {
1603     MonitorChunk* prev = monitor_chunks();
1604     while (prev->next() != chunk) prev = prev->next();
1605     prev->set_next(chunk->next());
1606   }
1607 }
1608 
1609 
1610 // Asynchronous exceptions support
1611 //
1612 // Note: this function shouldn't block if it's called in
1613 // _thread_in_native_trans state (such as from
1614 // check_special_condition_for_native_trans()).
1615 void JavaThread::check_and_handle_async_exceptions() {
1616   if (has_last_Java_frame() && has_async_exception_condition()) {
1617     // If we are at a polling page safepoint (not a poll return)
1618     // then we must defer async exception because live registers
1619     // will be clobbered by the exception path. Poll return is
1620     // ok because the call we a returning from already collides
1621     // with exception handling registers and so there is no issue.
1622     // (The exception handling path kills call result registers but
1623     //  this is ok since the exception kills the result anyway).
1624 
1625     if (is_at_poll_safepoint()) {
1626       // if the code we are returning to has deoptimized we must defer
1627       // the exception otherwise live registers get clobbered on the
1628       // exception path before deoptimization is able to retrieve them.
1629       //
1630       RegisterMap map(this, false);
1631       frame caller_fr = last_frame().sender(&map);
1632       assert(caller_fr.is_compiled_frame(), "what?");
1633       if (caller_fr.is_deoptimized_frame()) {
1634         log_info(exceptions)("deferred async exception at compiled safepoint");
1635         return;
1636       }
1637     }
1638   }
1639 
1640   AsyncExceptionCondition condition = clear_async_exception_condition();
1641   if (condition == _no_async_condition) {
1642     // Conditions have changed since has_special_runtime_exit_condition()
1643     // was called:
1644     // - if we were here only because of an external suspend request,
1645     //   then that was taken care of above (or cancelled) so we are done
1646     // - if we were here because of another async request, then it has
1647     //   been cleared between the has_special_runtime_exit_condition()
1648     //   and now so again we are done
1649     return;
1650   }
1651 
1652   // Check for pending async. exception
1653   if (_pending_async_exception != NULL) {
1654     // Only overwrite an already pending exception, if it is not a threadDeath.
1655     if (!has_pending_exception() || !pending_exception()->is_a(vmClasses::ThreadDeath_klass())) {
1656 
1657       // We cannot call Exceptions::_throw(...) here because we cannot block
1658       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
1659 
1660       LogTarget(Info, exceptions) lt;
1661       if (lt.is_enabled()) {
1662         ResourceMark rm;
1663         LogStream ls(lt);
1664         ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
1665           if (has_last_Java_frame()) {
1666             frame f = last_frame();
1667            ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
1668           }
1669         ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
1670       }
1671       _pending_async_exception = NULL;
1672       // Clear condition from _suspend_flags since we have finished processing it.
1673       clear_suspend_flag(_has_async_exception);
1674     }
1675   }
1676 
1677   if (condition == _async_unsafe_access_error && !has_pending_exception()) {
1678     // We may be at method entry which requires we save the do-not-unlock flag.
1679     UnlockFlagSaver fs(this);
1680     switch (thread_state()) {
1681     case _thread_in_vm: {
1682       JavaThread* THREAD = this;
1683       Exceptions::throw_unsafe_access_internal_error(THREAD, __FILE__, __LINE__, "a fault occurred in an unsafe memory access operation");
1684       return;
1685     }
1686     case _thread_in_native: {
1687       ThreadInVMfromNative tiv(this);
1688       JavaThread* THREAD = this;
1689       Exceptions::throw_unsafe_access_internal_error(THREAD, __FILE__, __LINE__, "a fault occurred in an unsafe memory access operation");
1690       return;
1691     }
1692     case _thread_in_Java: {
1693       ThreadInVMfromJava tiv(this);
1694       JavaThread* THREAD = this;
1695       Exceptions::throw_unsafe_access_internal_error(THREAD, __FILE__, __LINE__, "a fault occurred in a recent unsafe memory access operation in compiled Java code");
1696       return;
1697     }
1698     default:
1699       ShouldNotReachHere();
1700     }
1701   }
1702 
1703   assert(has_pending_exception(), "must have handled the async condition if no exception");
1704 }
1705 
1706 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
1707 
1708   if (is_obj_deopt_suspend()) {
1709     frame_anchor()->make_walkable();
1710     wait_for_object_deoptimization();
1711   }
1712 
1713   // We might be here for reasons in addition to the self-suspend request
1714   // so check for other async requests.
1715   if (check_asyncs) {
1716     check_and_handle_async_exceptions();
1717   }
1718 
1719   JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
1720 }
1721 
1722 class InstallAsyncExceptionClosure : public HandshakeClosure {
1723   Handle _throwable; // The Throwable thrown at the target Thread
1724 public:
1725   InstallAsyncExceptionClosure(Handle throwable) : HandshakeClosure("InstallAsyncException"), _throwable(throwable) {}
1726 
1727   void do_thread(Thread* thr) {
1728     JavaThread* target = thr->as_Java_thread();
1729     // Note that this now allows multiple ThreadDeath exceptions to be
1730     // thrown at a thread.
1731     // The target thread has run and has not exited yet.
1732     target->send_thread_stop(_throwable());
1733   }
1734 };
1735 
1736 void JavaThread::send_async_exception(oop java_thread, oop java_throwable) {
1737   Handle throwable(Thread::current(), java_throwable);
1738   JavaThread* target = java_lang_Thread::thread(java_thread);
1739   InstallAsyncExceptionClosure vm_stop(throwable);
1740   Handshake::execute(&vm_stop, target);
1741 }
1742 
1743 void JavaThread::send_thread_stop(oop java_throwable)  {
1744   ResourceMark rm;
1745   assert(is_handshake_safe_for(Thread::current()),
1746          "should be self or handshakee");
1747 
1748   // Do not throw asynchronous exceptions against the compiler thread
1749   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
1750   if (!can_call_java()) return;
1751 
1752   {
1753     // Actually throw the Throwable against the target Thread - however
1754     // only if there is no thread death exception installed already.
1755     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(vmClasses::ThreadDeath_klass())) {
1756       // If the topmost frame is a runtime stub, then we are calling into
1757       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
1758       // must deoptimize the caller before continuing, as the compiled  exception handler table
1759       // may not be valid
1760       if (has_last_Java_frame()) {
1761         frame f = last_frame();
1762         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
1763           RegisterMap reg_map(this, false);
1764           frame compiled_frame = f.sender(&reg_map);
1765           if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
1766             Deoptimization::deoptimize(this, compiled_frame);
1767           }
1768         }
1769       }
1770 
1771       // Set async. pending exception in thread.
1772       set_pending_async_exception(java_throwable);
1773 
1774       if (log_is_enabled(Info, exceptions)) {
1775          ResourceMark rm;
1776         log_info(exceptions)("Pending Async. exception installed of type: %s",
1777                              InstanceKlass::cast(_pending_async_exception->klass())->external_name());
1778       }
1779       // for AbortVMOnException flag
1780       Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
1781     }
1782   }
1783 
1784 
1785   // Interrupt thread so it will wake up from a potential wait()/sleep()/park()
1786   java_lang_Thread::set_interrupted(threadObj(), true);
1787   this->interrupt();
1788 }
1789 
1790 
1791 // External suspension mechanism.
1792 //
1793 // Guarantees on return (for a valid target thread):
1794 //   - Target thread will not execute any new bytecode.
1795 //   - Target thread will not enter any new monitors.
1796 //
1797 bool JavaThread::java_suspend() {
1798   ThreadsListHandle tlh;
1799   if (!tlh.includes(this)) {
1800     log_trace(thread, suspend)("JavaThread:" INTPTR_FORMAT " not on ThreadsList, no suspension", p2i(this));
1801     return false;
1802   }
1803   return this->handshake_state()->suspend();
1804 }
1805 
1806 bool JavaThread::java_resume() {
1807   ThreadsListHandle tlh;
1808   if (!tlh.includes(this)) {
1809     log_trace(thread, suspend)("JavaThread:" INTPTR_FORMAT " not on ThreadsList, nothing to resume", p2i(this));
1810     return false;
1811   }
1812   return this->handshake_state()->resume();
1813 }
1814 
1815 // Wait for another thread to perform object reallocation and relocking on behalf of
1816 // this thread.
1817 // Raw thread state transition to _thread_blocked and back again to the original
1818 // state before returning are performed. The current thread is required to
1819 // change to _thread_blocked in order to be seen to be safepoint/handshake safe
1820 // whilst suspended and only after becoming handshake safe, the other thread can
1821 // complete the handshake used to synchronize with this thread and then perform
1822 // the reallocation and relocking. We cannot use the thread state transition
1823 // helpers because we arrive here in various states and also because the helpers
1824 // indirectly call this method.  After leaving _thread_blocked we have to check
1825 // for safepoint/handshake, except if _thread_in_native. The thread is safe
1826 // without blocking then. Allowed states are enumerated in
1827 // SafepointSynchronize::block(). See also EscapeBarrier::sync_and_suspend_*()
1828 
1829 void JavaThread::wait_for_object_deoptimization() {
1830   assert(!has_last_Java_frame() || frame_anchor()->walkable(), "should have walkable stack");
1831   assert(this == Thread::current(), "invariant");
1832   JavaThreadState state = thread_state();
1833 
1834   bool spin_wait = os::is_MP();
1835   do {
1836     set_thread_state(_thread_blocked);
1837     // Wait for object deoptimization if requested.
1838     if (spin_wait) {
1839       // A single deoptimization is typically very short. Microbenchmarks
1840       // showed 5% better performance when spinning.
1841       const uint spin_limit = 10 * SpinYield::default_spin_limit;
1842       SpinYield spin(spin_limit);
1843       for (uint i = 0; is_obj_deopt_suspend() && i < spin_limit; i++) {
1844         spin.wait();
1845       }
1846       // Spin just once
1847       spin_wait = false;
1848     } else {
1849       MonitorLocker ml(this, EscapeBarrier_lock, Monitor::_no_safepoint_check_flag);
1850       if (is_obj_deopt_suspend()) {
1851         ml.wait();
1852       }
1853     }
1854     // The current thread could have been suspended again. We have to check for
1855     // suspend after restoring the saved state. Without this the current thread
1856     // might return to _thread_in_Java and execute bytecode.
1857     set_thread_state_fence(state);
1858 
1859     if (state != _thread_in_native) {
1860       SafepointMechanism::process_if_requested(this);
1861     }
1862     // A handshake for obj. deoptimization suspend could have been processed so
1863     // we must check after processing.
1864   } while (is_obj_deopt_suspend());
1865 }
1866 
1867 #ifdef ASSERT
1868 // Verify the JavaThread has not yet been published in the Threads::list, and
1869 // hence doesn't need protection from concurrent access at this stage.
1870 void JavaThread::verify_not_published() {
1871   // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
1872   // since an unpublished JavaThread doesn't participate in the
1873   // Thread-SMR protocol for keeping a ThreadsList alive.
1874   assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
1875 }
1876 #endif
1877 
1878 // Slow path when the native==>Java barriers detect a safepoint/handshake is
1879 // pending, when _suspend_flags is non-zero or when we need to process a stack
1880 // watermark. Also check for pending async exceptions (except unsafe access error).
1881 // Note only the native==>Java barriers can call this function when thread state
1882 // is _thread_in_native_trans.
1883 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
1884   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
1885   assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "Unwalkable stack in native->Java transition");
1886 
1887   // Enable WXWrite: called directly from interpreter native wrapper.
1888   MACOS_AARCH64_ONLY(ThreadWXEnable wx(WXWrite, thread));
1889 
1890   SafepointMechanism::process_if_requested_with_exit_check(thread, false /* check asyncs */);
1891 
1892   // After returning from native, it could be that the stack frames are not
1893   // yet safe to use. We catch such situations in the subsequent stack watermark
1894   // barrier, which will trap unsafe stack frames.
1895   StackWatermarkSet::before_unwind(thread);
1896 
1897   if (thread->has_async_exception_condition(false /* check unsafe access error */)) {
1898     // We are in _thread_in_native_trans state, don't handle unsafe
1899     // access error since that may block.
1900     thread->check_and_handle_async_exceptions();
1901   }
1902 }
1903 
1904 #ifndef PRODUCT
1905 // Deoptimization
1906 // Function for testing deoptimization
1907 void JavaThread::deoptimize() {
1908   StackFrameStream fst(this, false /* update */, true /* process_frames */);
1909   bool deopt = false;           // Dump stack only if a deopt actually happens.
1910   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
1911   // Iterate over all frames in the thread and deoptimize
1912   for (; !fst.is_done(); fst.next()) {
1913     if (fst.current()->can_be_deoptimized()) {
1914 
1915       if (only_at) {
1916         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
1917         // consists of comma or carriage return separated numbers so
1918         // search for the current bci in that string.
1919         address pc = fst.current()->pc();
1920         nmethod* nm =  (nmethod*) fst.current()->cb();
1921         ScopeDesc* sd = nm->scope_desc_at(pc);
1922         char buffer[8];
1923         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
1924         size_t len = strlen(buffer);
1925         const char * found = strstr(DeoptimizeOnlyAt, buffer);
1926         while (found != NULL) {
1927           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
1928               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
1929             // Check that the bci found is bracketed by terminators.
1930             break;
1931           }
1932           found = strstr(found + 1, buffer);
1933         }
1934         if (!found) {
1935           continue;
1936         }
1937       }
1938 
1939       if (DebugDeoptimization && !deopt) {
1940         deopt = true; // One-time only print before deopt
1941         tty->print_cr("[BEFORE Deoptimization]");
1942         trace_frames();
1943         trace_stack();
1944       }
1945       Deoptimization::deoptimize(this, *fst.current());
1946     }
1947   }
1948 
1949   if (DebugDeoptimization && deopt) {
1950     tty->print_cr("[AFTER Deoptimization]");
1951     trace_frames();
1952   }
1953 }
1954 
1955 
1956 // Make zombies
1957 void JavaThread::make_zombies() {
1958   for (StackFrameStream fst(this, true /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
1959     if (fst.current()->can_be_deoptimized()) {
1960       // it is a Java nmethod
1961       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
1962       nm->make_not_entrant();
1963     }
1964   }
1965 }
1966 #endif // PRODUCT
1967 
1968 
1969 void JavaThread::deoptimize_marked_methods() {
1970   if (!has_last_Java_frame()) return;
1971   StackFrameStream fst(this, false /* update */, true /* process_frames */);
1972   for (; !fst.is_done(); fst.next()) {
1973     if (fst.current()->should_be_deoptimized()) {
1974       Deoptimization::deoptimize(this, *fst.current());
1975     }
1976   }
1977 }
1978 
1979 #ifdef ASSERT
1980 void JavaThread::verify_frame_info() {
1981   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
1982          (has_last_Java_frame() && java_call_counter() > 0),
1983          "unexpected frame info: has_last_frame=%s, java_call_counter=%d",
1984          has_last_Java_frame() ? "true" : "false", java_call_counter());
1985 }
1986 #endif
1987 
1988 void JavaThread::oops_do_no_frames(OopClosure* f, CodeBlobClosure* cf) {
1989   // Verify that the deferred card marks have been flushed.
1990   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
1991 
1992   // Traverse the GCHandles
1993   Thread::oops_do_no_frames(f, cf);
1994 
1995   DEBUG_ONLY(verify_frame_info();)
1996 
1997   if (has_last_Java_frame()) {
1998     // Traverse the monitor chunks
1999     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2000       chunk->oops_do(f);
2001     }
2002   }
2003 
2004   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2005   // If we have deferred set_locals there might be oops waiting to be
2006   // written
2007   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = JvmtiDeferredUpdates::deferred_locals(this);
2008   if (list != NULL) {
2009     for (int i = 0; i < list->length(); i++) {
2010       list->at(i)->oops_do(f);
2011     }
2012   }
2013 
2014   // Traverse instance variables at the end since the GC may be moving things
2015   // around using this function
2016   f->do_oop((oop*) &_vm_result);
2017   f->do_oop((oop*) &_exception_oop);
2018   f->do_oop((oop*) &_pending_async_exception);
2019 #if INCLUDE_JVMCI
2020   f->do_oop((oop*) &_jvmci_reserved_oop0);
2021 #endif
2022 
2023   if (jvmti_thread_state() != NULL) {
2024     jvmti_thread_state()->oops_do(f, cf);
2025   }
2026 
2027   if (!UseHeavyMonitors && UseFastLocking) {
2028     lock_stack().oops_do(f);
2029   }
2030 }
2031 
2032 void JavaThread::oops_do_frames(OopClosure* f, CodeBlobClosure* cf) {
2033   if (!has_last_Java_frame()) {
2034     return;
2035   }
2036   // Finish any pending lazy GC activity for the frames
2037   StackWatermarkSet::finish_processing(this, NULL /* context */, StackWatermarkKind::gc);
2038   // Traverse the execution stack
2039   for (StackFrameStream fst(this, true /* update */, false /* process_frames */); !fst.is_done(); fst.next()) {
2040     fst.current()->oops_do(f, cf, fst.register_map());
2041   }
2042 }
2043 
2044 #ifdef ASSERT
2045 void JavaThread::verify_states_for_handshake() {
2046   // This checks that the thread has a correct frame state during a handshake.
2047   verify_frame_info();
2048 }
2049 #endif
2050 
2051 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2052   DEBUG_ONLY(verify_frame_info();)
2053 
2054   if (has_last_Java_frame()) {
2055     // Traverse the execution stack
2056     for (StackFrameStream fst(this, true /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
2057       fst.current()->nmethods_do(cf);
2058     }
2059   }
2060 
2061   if (jvmti_thread_state() != NULL) {
2062     jvmti_thread_state()->nmethods_do(cf);
2063   }
2064 }
2065 
2066 void JavaThread::metadata_do(MetadataClosure* f) {
2067   if (has_last_Java_frame()) {
2068     // Traverse the execution stack to call f() on the methods in the stack
2069     for (StackFrameStream fst(this, true /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
2070       fst.current()->metadata_do(f);
2071     }
2072   } else if (is_Compiler_thread()) {
2073     // need to walk ciMetadata in current compile tasks to keep alive.
2074     CompilerThread* ct = (CompilerThread*)this;
2075     if (ct->env() != NULL) {
2076       ct->env()->metadata_do(f);
2077     }
2078     CompileTask* task = ct->task();
2079     if (task != NULL) {
2080       task->metadata_do(f);
2081     }
2082   }
2083 }
2084 
2085 // Printing
2086 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2087   switch (_thread_state) {
2088   case _thread_uninitialized:     return "_thread_uninitialized";
2089   case _thread_new:               return "_thread_new";
2090   case _thread_new_trans:         return "_thread_new_trans";
2091   case _thread_in_native:         return "_thread_in_native";
2092   case _thread_in_native_trans:   return "_thread_in_native_trans";
2093   case _thread_in_vm:             return "_thread_in_vm";
2094   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
2095   case _thread_in_Java:           return "_thread_in_Java";
2096   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
2097   case _thread_blocked:           return "_thread_blocked";
2098   case _thread_blocked_trans:     return "_thread_blocked_trans";
2099   default:                        return "unknown thread state";
2100   }
2101 }
2102 
2103 #ifndef PRODUCT
2104 void JavaThread::print_thread_state_on(outputStream *st) const {
2105   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
2106 };
2107 #endif // PRODUCT
2108 
2109 // Called by Threads::print() for VM_PrintThreads operation
2110 void JavaThread::print_on(outputStream *st, bool print_extended_info) const {
2111   st->print_raw("\"");
2112   st->print_raw(get_thread_name());
2113   st->print_raw("\" ");
2114   oop thread_oop = threadObj();
2115   if (thread_oop != NULL) {
2116     st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2117     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
2118     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2119   }
2120   Thread::print_on(st, print_extended_info);
2121   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2122   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2123   if (thread_oop != NULL) {
2124     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2125   }
2126 #ifndef PRODUCT
2127   _safepoint_state->print_on(st);
2128 #endif // PRODUCT
2129   if (is_Compiler_thread()) {
2130     CompileTask *task = ((CompilerThread*)this)->task();
2131     if (task != NULL) {
2132       st->print("   Compiling: ");
2133       task->print(st, NULL, true, false);
2134     } else {
2135       st->print("   No compile task");
2136     }
2137     st->cr();
2138   }
2139 }
2140 
2141 void JavaThread::print() const { print_on(tty); }
2142 
2143 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2144   st->print("%s", get_thread_name_string(buf, buflen));
2145 }
2146 
2147 // Called by fatal error handler. The difference between this and
2148 // JavaThread::print() is that we can't grab lock or allocate memory.
2149 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2150   st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2151   oop thread_obj = threadObj();
2152   if (thread_obj != NULL) {
2153     if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2154   }
2155   st->print(" [");
2156   st->print("%s", _get_thread_state_name(_thread_state));
2157   if (osthread()) {
2158     st->print(", id=%d", osthread()->thread_id());
2159   }
2160   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2161             p2i(stack_end()), p2i(stack_base()));
2162   st->print("]");
2163 
2164   ThreadsSMRSupport::print_info_on(this, st);
2165   return;
2166 }
2167 
2168 
2169 // Verification
2170 
2171 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2172   // ignore if there is no stack
2173   if (!has_last_Java_frame()) return;
2174   // traverse the stack frames. Starts from top frame.
2175   for (StackFrameStream fst(this, true /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
2176     frame* fr = fst.current();
2177     f(fr, fst.register_map());
2178   }
2179 }
2180 
2181 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2182 
2183 void JavaThread::verify() {
2184   // Verify oops in the thread.
2185   oops_do(&VerifyOopClosure::verify_oop, NULL);
2186 
2187   // Verify the stack frames.
2188   frames_do(frame_verify);
2189 }
2190 
2191 // CR 6300358 (sub-CR 2137150)
2192 // Most callers of this method assume that it can't return NULL but a
2193 // thread may not have a name whilst it is in the process of attaching to
2194 // the VM - see CR 6412693, and there are places where a JavaThread can be
2195 // seen prior to having its threadObj set (e.g., JNI attaching threads and
2196 // if vm exit occurs during initialization). These cases can all be accounted
2197 // for such that this method never returns NULL.
2198 const char* JavaThread::get_thread_name() const {
2199   if (Thread::is_JavaThread_protected(this)) {
2200     // The target JavaThread is protected so get_thread_name_string() is safe:
2201     return get_thread_name_string();
2202   }
2203 
2204   // The target JavaThread is not protected so we return the default:
2205   return Thread::name();
2206 }
2207 
2208 // Returns a non-NULL representation of this thread's name, or a suitable
2209 // descriptive string if there is no set name.
2210 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2211   const char* name_str;
2212   oop thread_obj = threadObj();
2213   if (thread_obj != NULL) {
2214     oop name = java_lang_Thread::name(thread_obj);
2215     if (name != NULL) {
2216       if (buf == NULL) {
2217         name_str = java_lang_String::as_utf8_string(name);
2218       } else {
2219         name_str = java_lang_String::as_utf8_string(name, buf, buflen);
2220       }
2221     } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
2222       name_str = "<no-name - thread is attaching>";
2223     } else {
2224       name_str = Thread::name();
2225     }
2226   } else {
2227     name_str = Thread::name();
2228   }
2229   assert(name_str != NULL, "unexpected NULL thread name");
2230   return name_str;
2231 }
2232 
2233 // Helper to extract the name from the thread oop for logging.
2234 const char* JavaThread::name_for(oop thread_obj) {
2235   assert(thread_obj != NULL, "precondition");
2236   oop name = java_lang_Thread::name(thread_obj);
2237   const char* name_str;
2238   if (name != NULL) {
2239     name_str = java_lang_String::as_utf8_string(name);
2240   } else {
2241     name_str = "<un-named>";
2242   }
2243   return name_str;
2244 }
2245 
2246 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
2247 
2248   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
2249   assert(NoPriority <= prio && prio <= MaxPriority, "sanity check");
2250   // Link Java Thread object <-> C++ Thread
2251 
2252   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
2253   // and put it into a new Handle.  The Handle "thread_oop" can then
2254   // be used to pass the C++ thread object to other methods.
2255 
2256   // Set the Java level thread object (jthread) field of the
2257   // new thread (a JavaThread *) to C++ thread object using the
2258   // "thread_oop" handle.
2259 
2260   // Set the thread field (a JavaThread *) of the
2261   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
2262 
2263   Handle thread_oop(Thread::current(),
2264                     JNIHandles::resolve_non_null(jni_thread));
2265   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
2266          "must be initialized");
2267   set_threadObj(thread_oop());
2268   java_lang_Thread::set_thread(thread_oop(), this);
2269 
2270   if (prio == NoPriority) {
2271     prio = java_lang_Thread::priority(thread_oop());
2272     assert(prio != NoPriority, "A valid priority should be present");
2273   }
2274 
2275   // Push the Java priority down to the native thread; needs Threads_lock
2276   Thread::set_priority(this, prio);
2277 
2278   // Add the new thread to the Threads list and set it in motion.
2279   // We must have threads lock in order to call Threads::add.
2280   // It is crucial that we do not block before the thread is
2281   // added to the Threads list for if a GC happens, then the java_thread oop
2282   // will not be visited by GC.
2283   Threads::add(this);
2284 }
2285 
2286 oop JavaThread::current_park_blocker() {
2287   // Support for JSR-166 locks
2288   oop thread_oop = threadObj();
2289   if (thread_oop != NULL) {
2290     return java_lang_Thread::park_blocker(thread_oop);
2291   }
2292   return NULL;
2293 }
2294 
2295 
2296 void JavaThread::print_stack_on(outputStream* st) {
2297   if (!has_last_Java_frame()) return;
2298 
2299   Thread* current_thread = Thread::current();
2300   ResourceMark rm(current_thread);
2301   HandleMark hm(current_thread);
2302 
2303   RegisterMap reg_map(this);
2304   vframe* start_vf = last_java_vframe(&reg_map);
2305   int count = 0;
2306   for (vframe* f = start_vf; f != NULL; f = f->sender()) {
2307     if (f->is_java_frame()) {
2308       javaVFrame* jvf = javaVFrame::cast(f);
2309       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
2310 
2311       // Print out lock information
2312       if (JavaMonitorsInStackTrace) {
2313         jvf->print_lock_info_on(st, count);
2314       }
2315     } else {
2316       // Ignore non-Java frames
2317     }
2318 
2319     // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
2320     count++;
2321     if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
2322   }
2323 }
2324 
2325 
2326 // JVMTI PopFrame support
2327 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
2328   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
2329   if (in_bytes(size_in_bytes) != 0) {
2330     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
2331     _popframe_preserved_args_size = in_bytes(size_in_bytes);
2332     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
2333   }
2334 }
2335 
2336 void* JavaThread::popframe_preserved_args() {
2337   return _popframe_preserved_args;
2338 }
2339 
2340 ByteSize JavaThread::popframe_preserved_args_size() {
2341   return in_ByteSize(_popframe_preserved_args_size);
2342 }
2343 
2344 WordSize JavaThread::popframe_preserved_args_size_in_words() {
2345   int sz = in_bytes(popframe_preserved_args_size());
2346   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
2347   return in_WordSize(sz / wordSize);
2348 }
2349 
2350 void JavaThread::popframe_free_preserved_args() {
2351   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
2352   FREE_C_HEAP_ARRAY(char, (char*)_popframe_preserved_args);
2353   _popframe_preserved_args = NULL;
2354   _popframe_preserved_args_size = 0;
2355 }
2356 
2357 #ifndef PRODUCT
2358 
2359 void JavaThread::trace_frames() {
2360   tty->print_cr("[Describe stack]");
2361   int frame_no = 1;
2362   for (StackFrameStream fst(this, true /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
2363     tty->print("  %d. ", frame_no++);
2364     fst.current()->print_value_on(tty, this);
2365     tty->cr();
2366   }
2367 }
2368 
2369 class PrintAndVerifyOopClosure: public OopClosure {
2370  protected:
2371   template <class T> inline void do_oop_work(T* p) {
2372     oop obj = RawAccess<>::oop_load(p);
2373     if (obj == NULL) return;
2374     tty->print(INTPTR_FORMAT ": ", p2i(p));
2375     if (oopDesc::is_oop_or_null(obj)) {
2376       if (obj->is_objArray()) {
2377         tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
2378       } else {
2379         obj->print();
2380       }
2381     } else {
2382       tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
2383     }
2384     tty->cr();
2385   }
2386  public:
2387   virtual void do_oop(oop* p) { do_oop_work(p); }
2388   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
2389 };
2390 
2391 #ifdef ASSERT
2392 // Print or validate the layout of stack frames
2393 void JavaThread::print_frame_layout(int depth, bool validate_only) {
2394   ResourceMark rm;
2395   PreserveExceptionMark pm(this);
2396   FrameValues values;
2397   int frame_no = 0;
2398   for (StackFrameStream fst(this, false /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
2399     fst.current()->describe(values, ++frame_no);
2400     if (depth == frame_no) break;
2401   }
2402   if (validate_only) {
2403     values.validate();
2404   } else {
2405     tty->print_cr("[Describe stack layout]");
2406     values.print(this);
2407   }
2408 }
2409 #endif
2410 
2411 void JavaThread::trace_stack_from(vframe* start_vf) {
2412   ResourceMark rm;
2413   int vframe_no = 1;
2414   for (vframe* f = start_vf; f; f = f->sender()) {
2415     if (f->is_java_frame()) {
2416       javaVFrame::cast(f)->print_activation(vframe_no++);
2417     } else {
2418       f->print();
2419     }
2420     if (vframe_no > StackPrintLimit) {
2421       tty->print_cr("...<more frames>...");
2422       return;
2423     }
2424   }
2425 }
2426 
2427 
2428 void JavaThread::trace_stack() {
2429   if (!has_last_Java_frame()) return;
2430   Thread* current_thread = Thread::current();
2431   ResourceMark rm(current_thread);
2432   HandleMark hm(current_thread);
2433   RegisterMap reg_map(this);
2434   trace_stack_from(last_java_vframe(&reg_map));
2435 }
2436 
2437 
2438 #endif // PRODUCT
2439 
2440 
2441 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
2442   assert(reg_map != NULL, "a map must be given");
2443   frame f = last_frame();
2444   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
2445     if (vf->is_java_frame()) return javaVFrame::cast(vf);
2446   }
2447   return NULL;
2448 }
2449 
2450 
2451 Klass* JavaThread::security_get_caller_class(int depth) {
2452   vframeStream vfst(this);
2453   vfst.security_get_caller_frame(depth);
2454   if (!vfst.at_end()) {
2455     return vfst.method()->method_holder();
2456   }
2457   return NULL;
2458 }
2459 
2460 // java.lang.Thread.sleep support
2461 // Returns true if sleep time elapsed as expected, and false
2462 // if the thread was interrupted.
2463 bool JavaThread::sleep(jlong millis) {
2464   assert(this == Thread::current(),  "thread consistency check");
2465 
2466   ParkEvent * const slp = this->_SleepEvent;
2467   // Because there can be races with thread interruption sending an unpark()
2468   // to the event, we explicitly reset it here to avoid an immediate return.
2469   // The actual interrupt state will be checked before we park().
2470   slp->reset();
2471   // Thread interruption establishes a happens-before ordering in the
2472   // Java Memory Model, so we need to ensure we synchronize with the
2473   // interrupt state.
2474   OrderAccess::fence();
2475 
2476   jlong prevtime = os::javaTimeNanos();
2477 
2478   for (;;) {
2479     // interruption has precedence over timing out
2480     if (this->is_interrupted(true)) {
2481       return false;
2482     }
2483 
2484     if (millis <= 0) {
2485       return true;
2486     }
2487 
2488     {
2489       ThreadBlockInVM tbivm(this);
2490       OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
2491       slp->park(millis);
2492     }
2493 
2494     // Update elapsed time tracking
2495     jlong newtime = os::javaTimeNanos();
2496     if (newtime - prevtime < 0) {
2497       // time moving backwards, should only happen if no monotonic clock
2498       // not a guarantee() because JVM should not abort on kernel/glibc bugs
2499       assert(false,
2500              "unexpected time moving backwards detected in JavaThread::sleep()");
2501     } else {
2502       millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC;
2503     }
2504     prevtime = newtime;
2505   }
2506 }
2507 
2508 
2509 // ======= Threads ========
2510 
2511 // The Threads class links together all active threads, and provides
2512 // operations over all threads. It is protected by the Threads_lock,
2513 // which is also used in other global contexts like safepointing.
2514 // ThreadsListHandles are used to safely perform operations on one
2515 // or more threads without the risk of the thread exiting during the
2516 // operation.
2517 //
2518 // Note: The Threads_lock is currently more widely used than we
2519 // would like. We are actively migrating Threads_lock uses to other
2520 // mechanisms in order to reduce Threads_lock contention.
2521 
2522 int         Threads::_number_of_threads = 0;
2523 int         Threads::_number_of_non_daemon_threads = 0;
2524 int         Threads::_return_code = 0;
2525 uintx       Threads::_thread_claim_token = 1; // Never zero.
2526 size_t      JavaThread::_stack_size_at_create = 0;
2527 
2528 #ifdef ASSERT
2529 bool        Threads::_vm_complete = false;
2530 #endif
2531 
2532 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
2533   Prefetch::read((void*)addr, prefetch_interval);
2534   return *addr;
2535 }
2536 
2537 // Possibly the ugliest for loop the world has seen. C++ does not allow
2538 // multiple types in the declaration section of the for loop. In this case
2539 // we are only dealing with pointers and hence can cast them. It looks ugly
2540 // but macros are ugly and therefore it's fine to make things absurdly ugly.
2541 #define DO_JAVA_THREADS(LIST, X)                                                                                          \
2542     for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes,                           \
2543              *MACRO_list = (JavaThread*)(LIST),                                                                           \
2544              **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(),  \
2545              **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(),                                     \
2546              *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval);                 \
2547          MACRO_current_p != MACRO_end;                                                                                    \
2548          MACRO_current_p++,                                                                                               \
2549              X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
2550 
2551 // All JavaThreads
2552 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
2553 
2554 // All NonJavaThreads (i.e., every non-JavaThread in the system).
2555 void Threads::non_java_threads_do(ThreadClosure* tc) {
2556   NoSafepointVerifier nsv;
2557   for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) {
2558     tc->do_thread(njti.current());
2559   }
2560 }
2561 
2562 // All JavaThreads
2563 void Threads::java_threads_do(ThreadClosure* tc) {
2564   assert_locked_or_safepoint(Threads_lock);
2565   // ALL_JAVA_THREADS iterates through all JavaThreads.
2566   ALL_JAVA_THREADS(p) {
2567     tc->do_thread(p);
2568   }
2569 }
2570 
2571 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) {
2572   assert_locked_or_safepoint(Threads_lock);
2573   java_threads_do(tc);
2574   tc->do_thread(VMThread::vm_thread());
2575 }
2576 
2577 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
2578 void Threads::threads_do(ThreadClosure* tc) {
2579   assert_locked_or_safepoint(Threads_lock);
2580   java_threads_do(tc);
2581   non_java_threads_do(tc);
2582 }
2583 
2584 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
2585   uintx claim_token = Threads::thread_claim_token();
2586   ALL_JAVA_THREADS(p) {
2587     if (p->claim_threads_do(is_par, claim_token)) {
2588       tc->do_thread(p);
2589     }
2590   }
2591   VMThread* vmt = VMThread::vm_thread();
2592   if (vmt->claim_threads_do(is_par, claim_token)) {
2593     tc->do_thread(vmt);
2594   }
2595 }
2596 
2597 // The system initialization in the library has three phases.
2598 //
2599 // Phase 1: java.lang.System class initialization
2600 //     java.lang.System is a primordial class loaded and initialized
2601 //     by the VM early during startup.  java.lang.System.<clinit>
2602 //     only does registerNatives and keeps the rest of the class
2603 //     initialization work later until thread initialization completes.
2604 //
2605 //     System.initPhase1 initializes the system properties, the static
2606 //     fields in, out, and err. Set up java signal handlers, OS-specific
2607 //     system settings, and thread group of the main thread.
2608 static void call_initPhase1(TRAPS) {
2609   Klass* klass = vmClasses::System_klass();
2610   JavaValue result(T_VOID);
2611   JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
2612                                          vmSymbols::void_method_signature(), CHECK);
2613 }
2614 
2615 // Phase 2. Module system initialization
2616 //     This will initialize the module system.  Only java.base classes
2617 //     can be loaded until phase 2 completes.
2618 //
2619 //     Call System.initPhase2 after the compiler initialization and jsr292
2620 //     classes get initialized because module initialization runs a lot of java
2621 //     code, that for performance reasons, should be compiled.  Also, this will
2622 //     enable the startup code to use lambda and other language features in this
2623 //     phase and onward.
2624 //
2625 //     After phase 2, The VM will begin search classes from -Xbootclasspath/a.
2626 static void call_initPhase2(TRAPS) {
2627   TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
2628 
2629   Klass* klass = vmClasses::System_klass();
2630 
2631   JavaValue result(T_INT);
2632   JavaCallArguments args;
2633   args.push_int(DisplayVMOutputToStderr);
2634   args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
2635   JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
2636                                          vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
2637   if (result.get_jint() != JNI_OK) {
2638     vm_exit_during_initialization(); // no message or exception
2639   }
2640 
2641   universe_post_module_init();
2642 }
2643 
2644 // Phase 3. final setup - set security manager, system class loader and TCCL
2645 //
2646 //     This will instantiate and set the security manager, set the system class
2647 //     loader as well as the thread context class loader.  The security manager
2648 //     and system class loader may be a custom class loaded from -Xbootclasspath/a,
2649 //     other modules or the application's classpath.
2650 static void call_initPhase3(TRAPS) {
2651   Klass* klass = vmClasses::System_klass();
2652   JavaValue result(T_VOID);
2653   JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
2654                                          vmSymbols::void_method_signature(), CHECK);
2655 }
2656 
2657 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
2658   TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
2659 
2660   if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
2661     create_vm_init_libraries();
2662   }
2663 
2664   initialize_class(vmSymbols::java_lang_String(), CHECK);
2665 
2666   // Inject CompactStrings value after the static initializers for String ran.
2667   java_lang_String::set_compact_strings(CompactStrings);
2668 
2669   // Initialize java_lang.System (needed before creating the thread)
2670   initialize_class(vmSymbols::java_lang_System(), CHECK);
2671   // The VM creates & returns objects of this class. Make sure it's initialized.
2672   initialize_class(vmSymbols::java_lang_Class(), CHECK);
2673   initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
2674   Handle thread_group = create_initial_thread_group(CHECK);
2675   Universe::set_main_thread_group(thread_group());
2676   initialize_class(vmSymbols::java_lang_Thread(), CHECK);
2677   create_initial_thread(thread_group, main_thread, CHECK);
2678 
2679   // The VM creates objects of this class.
2680   initialize_class(vmSymbols::java_lang_Module(), CHECK);
2681 
2682 #ifdef ASSERT
2683   InstanceKlass *k = vmClasses::UnsafeConstants_klass();
2684   assert(k->is_not_initialized(), "UnsafeConstants should not already be initialized");
2685 #endif
2686 
2687   // initialize the hardware-specific constants needed by Unsafe
2688   initialize_class(vmSymbols::jdk_internal_misc_UnsafeConstants(), CHECK);
2689   jdk_internal_misc_UnsafeConstants::set_unsafe_constants();
2690 
2691   // The VM preresolves methods to these classes. Make sure that they get initialized
2692   initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
2693   initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
2694 
2695   // Phase 1 of the system initialization in the library, java.lang.System class initialization
2696   call_initPhase1(CHECK);
2697 
2698   // Get the Java runtime name, version, and vendor info after java.lang.System is initialized.
2699   // Some values are actually configure-time constants but some can be set via the jlink tool and
2700   // so must be read dynamically. We treat them all the same.
2701   InstanceKlass* ik = SystemDictionary::find_instance_klass(vmSymbols::java_lang_VersionProps(),
2702                                                             Handle(), Handle());
2703   {
2704     ResourceMark rm(main_thread);
2705     JDK_Version::set_java_version(get_java_version_info(ik, vmSymbols::java_version_name()));
2706 
2707     JDK_Version::set_runtime_name(get_java_version_info(ik, vmSymbols::java_runtime_name_name()));
2708 
2709     JDK_Version::set_runtime_version(get_java_version_info(ik, vmSymbols::java_runtime_version_name()));
2710 
2711     JDK_Version::set_runtime_vendor_version(get_java_version_info(ik, vmSymbols::java_runtime_vendor_version_name()));
2712 
2713     JDK_Version::set_runtime_vendor_vm_bug_url(get_java_version_info(ik, vmSymbols::java_runtime_vendor_vm_bug_url_name()));
2714   }
2715 
2716   // an instance of OutOfMemory exception has been allocated earlier
2717   initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
2718   initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
2719   initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
2720   initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
2721   initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
2722   initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
2723   initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
2724   initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
2725 }
2726 
2727 void Threads::initialize_jsr292_core_classes(TRAPS) {
2728   TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
2729 
2730   initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
2731   initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
2732   initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
2733   initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
2734 }
2735 
2736 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
2737   extern void JDK_Version_init();
2738 
2739   // Preinitialize version info.
2740   VM_Version::early_initialize();
2741 
2742   // Check version
2743   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
2744 
2745   // Initialize library-based TLS
2746   ThreadLocalStorage::init();
2747 
2748   // Initialize the output stream module
2749   ostream_init();
2750 
2751   // Process java launcher properties.
2752   Arguments::process_sun_java_launcher_properties(args);
2753 
2754   // Initialize the os module
2755   os::init();
2756 
2757   MACOS_AARCH64_ONLY(os::current_thread_enable_wx(WXWrite));
2758 
2759   // Record VM creation timing statistics
2760   TraceVmCreationTime create_vm_timer;
2761   create_vm_timer.start();
2762 
2763   // Initialize system properties.
2764   Arguments::init_system_properties();
2765 
2766   // So that JDK version can be used as a discriminator when parsing arguments
2767   JDK_Version_init();
2768 
2769   // Update/Initialize System properties after JDK version number is known
2770   Arguments::init_version_specific_system_properties();
2771 
2772   // Make sure to initialize log configuration *before* parsing arguments
2773   LogConfiguration::initialize(create_vm_timer.begin_time());
2774 
2775   // Parse arguments
2776   // Note: this internally calls os::init_container_support()
2777   jint parse_result = Arguments::parse(args);
2778   if (parse_result != JNI_OK) return parse_result;
2779 
2780 #if INCLUDE_NMT
2781   // Initialize NMT right after argument parsing to keep the pre-NMT-init window small.
2782   MemTracker::initialize();
2783 #endif // INCLUDE_NMT
2784 
2785   os::init_before_ergo();
2786 
2787   jint ergo_result = Arguments::apply_ergo();
2788   if (ergo_result != JNI_OK) return ergo_result;
2789 
2790   // Final check of all ranges after ergonomics which may change values.
2791   if (!JVMFlagLimit::check_all_ranges()) {
2792     return JNI_EINVAL;
2793   }
2794 
2795   // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
2796   bool constraint_result = JVMFlagLimit::check_all_constraints(JVMFlagConstraintPhase::AfterErgo);
2797   if (!constraint_result) {
2798     return JNI_EINVAL;
2799   }
2800 
2801   if (PauseAtStartup) {
2802     os::pause();
2803   }
2804 
2805   HOTSPOT_VM_INIT_BEGIN();
2806 
2807   // Timing (must come after argument parsing)
2808   TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
2809 
2810   // Initialize the os module after parsing the args
2811   jint os_init_2_result = os::init_2();
2812   if (os_init_2_result != JNI_OK) return os_init_2_result;
2813 
2814 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
2815   // Initialize assert poison page mechanism.
2816   if (ShowRegistersOnAssert) {
2817     initialize_assert_poison();
2818   }
2819 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
2820 
2821   SafepointMechanism::initialize();
2822 
2823   jint adjust_after_os_result = Arguments::adjust_after_os();
2824   if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
2825 
2826   // Initialize output stream logging
2827   ostream_init_log();
2828 
2829   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
2830   // Must be before create_vm_init_agents()
2831   if (Arguments::init_libraries_at_startup()) {
2832     convert_vm_init_libraries_to_agents();
2833   }
2834 
2835   // Launch -agentlib/-agentpath and converted -Xrun agents
2836   if (Arguments::init_agents_at_startup()) {
2837     create_vm_init_agents();
2838   }
2839 
2840   // Initialize Threads state
2841   _number_of_threads = 0;
2842   _number_of_non_daemon_threads = 0;
2843 
2844   // Initialize global data structures and create system classes in heap
2845   vm_init_globals();
2846 
2847 #if INCLUDE_JVMCI
2848   if (JVMCICounterSize > 0) {
2849     JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtJVMCI);
2850     memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
2851   } else {
2852     JavaThread::_jvmci_old_thread_counters = NULL;
2853   }
2854 #endif // INCLUDE_JVMCI
2855 
2856   // Initialize OopStorage for threadObj
2857   _thread_oop_storage = OopStorageSet::create_strong("Thread OopStorage", mtThread);
2858 
2859   // Attach the main thread to this os thread
2860   JavaThread* main_thread = new JavaThread();
2861   main_thread->set_thread_state(_thread_in_vm);
2862   main_thread->initialize_thread_current();
2863   // must do this before set_active_handles
2864   main_thread->record_stack_base_and_size();
2865   main_thread->register_thread_stack_with_NMT();
2866   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
2867   MACOS_AARCH64_ONLY(main_thread->init_wx());
2868 
2869   if (!main_thread->set_as_starting_thread()) {
2870     vm_shutdown_during_initialization(
2871                                       "Failed necessary internal allocation. Out of swap space");
2872     main_thread->smr_delete();
2873     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
2874     return JNI_ENOMEM;
2875   }
2876 
2877   // Enable guard page *after* os::create_main_thread(), otherwise it would
2878   // crash Linux VM, see notes in os_linux.cpp.
2879   main_thread->stack_overflow_state()->create_stack_guard_pages();
2880 
2881   // Initialize Java-Level synchronization subsystem
2882   ObjectMonitor::Initialize();
2883   ObjectSynchronizer::initialize();
2884 
2885   // Initialize global modules
2886   jint status = init_globals();
2887   if (status != JNI_OK) {
2888     main_thread->smr_delete();
2889     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
2890     return status;
2891   }
2892 
2893   JFR_ONLY(Jfr::on_create_vm_1();)
2894 
2895   // Should be done after the heap is fully created
2896   main_thread->cache_global_variables();
2897 
2898   { MutexLocker mu(Threads_lock);
2899     Threads::add(main_thread);
2900   }
2901 
2902   // Any JVMTI raw monitors entered in onload will transition into
2903   // real raw monitor. VM is setup enough here for raw monitor enter.
2904   JvmtiExport::transition_pending_onload_raw_monitors();
2905 
2906   // Create the VMThread
2907   { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
2908 
2909     VMThread::create();
2910     Thread* vmthread = VMThread::vm_thread();
2911 
2912     if (!os::create_thread(vmthread, os::vm_thread)) {
2913       vm_exit_during_initialization("Cannot create VM thread. "
2914                                     "Out of system resources.");
2915     }
2916 
2917     // Wait for the VM thread to become ready, and VMThread::run to initialize
2918     // Monitors can have spurious returns, must always check another state flag
2919     {
2920       MonitorLocker ml(Notify_lock);
2921       os::start_thread(vmthread);
2922       while (vmthread->active_handles() == NULL) {
2923         ml.wait();
2924       }
2925     }
2926   }
2927 
2928   assert(Universe::is_fully_initialized(), "not initialized");
2929   if (VerifyDuringStartup) {
2930     // Make sure we're starting with a clean slate.
2931     VM_Verify verify_op;
2932     VMThread::execute(&verify_op);
2933   }
2934 
2935   // We need this to update the java.vm.info property in case any flags used
2936   // to initially define it have been changed. This is needed for both CDS
2937   // since UseSharedSpaces may be changed after java.vm.info
2938   // is initially computed. See Abstract_VM_Version::vm_info_string().
2939   // This update must happen before we initialize the java classes, but
2940   // after any initialization logic that might modify the flags.
2941   Arguments::update_vm_info_property(VM_Version::vm_info_string());
2942 
2943   JavaThread* THREAD = JavaThread::current(); // For exception macros.
2944   HandleMark hm(THREAD);
2945 
2946   // Always call even when there are not JVMTI environments yet, since environments
2947   // may be attached late and JVMTI must track phases of VM execution
2948   JvmtiExport::enter_early_start_phase();
2949 
2950   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
2951   JvmtiExport::post_early_vm_start();
2952 
2953   initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
2954 
2955   quicken_jni_functions();
2956 
2957   // No more stub generation allowed after that point.
2958   StubCodeDesc::freeze();
2959 
2960   // Set flag that basic initialization has completed. Used by exceptions and various
2961   // debug stuff, that does not work until all basic classes have been initialized.
2962   set_init_completed();
2963 
2964   LogConfiguration::post_initialize();
2965   Metaspace::post_initialize();
2966 
2967   HOTSPOT_VM_INIT_END();
2968 
2969   // record VM initialization completion time
2970 #if INCLUDE_MANAGEMENT
2971   Management::record_vm_init_completed();
2972 #endif // INCLUDE_MANAGEMENT
2973 
2974   // Signal Dispatcher needs to be started before VMInit event is posted
2975   os::initialize_jdk_signal_support(CHECK_JNI_ERR);
2976 
2977   // Start Attach Listener if +StartAttachListener or it can't be started lazily
2978   if (!DisableAttachMechanism) {
2979     AttachListener::vm_start();
2980     if (StartAttachListener || AttachListener::init_at_startup()) {
2981       AttachListener::init();
2982     }
2983   }
2984 
2985   // Launch -Xrun agents
2986   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
2987   // back-end can launch with -Xdebug -Xrunjdwp.
2988   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
2989     create_vm_init_libraries();
2990   }
2991 
2992   Chunk::start_chunk_pool_cleaner_task();
2993 
2994   // Start the service thread
2995   // The service thread enqueues JVMTI deferred events and does various hashtable
2996   // and other cleanups.  Needs to start before the compilers start posting events.
2997   ServiceThread::initialize();
2998 
2999   // Start the monitor deflation thread:
3000   MonitorDeflationThread::initialize();
3001 
3002   // initialize compiler(s)
3003 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3004 #if INCLUDE_JVMCI
3005   bool force_JVMCI_intialization = false;
3006   if (EnableJVMCI) {
3007     // Initialize JVMCI eagerly when it is explicitly requested.
3008     // Or when JVMCILibDumpJNIConfig or JVMCIPrintProperties is enabled.
3009     force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties || JVMCILibDumpJNIConfig;
3010 
3011     if (!force_JVMCI_intialization) {
3012       // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3013       // compilations via JVMCI will not actually block until JVMCI is initialized.
3014       force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3015     }
3016   }
3017 #endif
3018   CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
3019   // Postpone completion of compiler initialization to after JVMCI
3020   // is initialized to avoid timeouts of blocking compilations.
3021   if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
3022     CompileBroker::compilation_init_phase2();
3023   }
3024 #endif
3025 
3026   // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3027   // It is done after compilers are initialized, because otherwise compilations of
3028   // signature polymorphic MH intrinsics can be missed
3029   // (see SystemDictionary::find_method_handle_intrinsic).
3030   initialize_jsr292_core_classes(CHECK_JNI_ERR);
3031 
3032   // This will initialize the module system.  Only java.base classes can be
3033   // loaded until phase 2 completes
3034   call_initPhase2(CHECK_JNI_ERR);
3035 
3036   JFR_ONLY(Jfr::on_create_vm_2();)
3037 
3038   // Always call even when there are not JVMTI environments yet, since environments
3039   // may be attached late and JVMTI must track phases of VM execution
3040   JvmtiExport::enter_start_phase();
3041 
3042   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3043   JvmtiExport::post_vm_start();
3044 
3045   // Final system initialization including security manager and system class loader
3046   call_initPhase3(CHECK_JNI_ERR);
3047 
3048   // cache the system and platform class loaders
3049   SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3050 
3051 #if INCLUDE_CDS
3052   // capture the module path info from the ModuleEntryTable
3053   ClassLoader::initialize_module_path(THREAD);
3054   if (HAS_PENDING_EXCEPTION) {
3055     java_lang_Throwable::print(PENDING_EXCEPTION, tty);
3056     vm_exit_during_initialization("ClassLoader::initialize_module_path() failed unexpectedly");
3057   }
3058 #endif
3059 
3060 #if INCLUDE_JVMCI
3061   if (force_JVMCI_intialization) {
3062     JVMCI::initialize_compiler(CHECK_JNI_ERR);
3063     CompileBroker::compilation_init_phase2();
3064   }
3065 #endif
3066 
3067   // Always call even when there are not JVMTI environments yet, since environments
3068   // may be attached late and JVMTI must track phases of VM execution
3069   JvmtiExport::enter_live_phase();
3070 
3071   // Make perfmemory accessible
3072   PerfMemory::set_accessible(true);
3073 
3074   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3075   JvmtiExport::post_vm_initialized();
3076 
3077   JFR_ONLY(Jfr::on_create_vm_3();)
3078 
3079 #if INCLUDE_MANAGEMENT
3080   Management::initialize(THREAD);
3081 
3082   if (HAS_PENDING_EXCEPTION) {
3083     // management agent fails to start possibly due to
3084     // configuration problem and is responsible for printing
3085     // stack trace if appropriate. Simply exit VM.
3086     vm_exit(1);
3087   }
3088 #endif // INCLUDE_MANAGEMENT
3089 
3090   StatSampler::engage();
3091   if (CheckJNICalls)                  JniPeriodicChecker::engage();
3092 
3093   BiasedLocking::init();
3094 
3095 #if INCLUDE_RTM_OPT
3096   RTMLockingCounters::init();
3097 #endif
3098 
3099   call_postVMInitHook(THREAD);
3100   // The Java side of PostVMInitHook.run must deal with all
3101   // exceptions and provide means of diagnosis.
3102   if (HAS_PENDING_EXCEPTION) {
3103     CLEAR_PENDING_EXCEPTION;
3104   }
3105 
3106   {
3107     MutexLocker ml(PeriodicTask_lock);
3108     // Make sure the WatcherThread can be started by WatcherThread::start()
3109     // or by dynamic enrollment.
3110     WatcherThread::make_startable();
3111     // Start up the WatcherThread if there are any periodic tasks
3112     // NOTE:  All PeriodicTasks should be registered by now. If they
3113     //   aren't, late joiners might appear to start slowly (we might
3114     //   take a while to process their first tick).
3115     if (PeriodicTask::num_tasks() > 0) {
3116       WatcherThread::start();
3117     }
3118   }
3119 
3120   create_vm_timer.end();
3121 #ifdef ASSERT
3122   _vm_complete = true;
3123 #endif
3124 
3125   if (DumpSharedSpaces) {
3126     MetaspaceShared::preload_and_dump();
3127     ShouldNotReachHere();
3128   }
3129 
3130   return JNI_OK;
3131 }
3132 
3133 // type for the Agent_OnLoad and JVM_OnLoad entry points
3134 extern "C" {
3135   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3136 }
3137 // Find a command line agent library and return its entry point for
3138 //         -agentlib:  -agentpath:   -Xrun
3139 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3140 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3141                                     const char *on_load_symbols[],
3142                                     size_t num_symbol_entries) {
3143   OnLoadEntry_t on_load_entry = NULL;
3144   void *library = NULL;
3145 
3146   if (!agent->valid()) {
3147     char buffer[JVM_MAXPATHLEN];
3148     char ebuf[1024] = "";
3149     const char *name = agent->name();
3150     const char *msg = "Could not find agent library ";
3151 
3152     // First check to see if agent is statically linked into executable
3153     if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3154       library = agent->os_lib();
3155     } else if (agent->is_absolute_path()) {
3156       library = os::dll_load(name, ebuf, sizeof ebuf);
3157       if (library == NULL) {
3158         const char *sub_msg = " in absolute path, with error: ";
3159         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3160         char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3161         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3162         // If we can't find the agent, exit.
3163         vm_exit_during_initialization(buf, NULL);
3164         FREE_C_HEAP_ARRAY(char, buf);
3165       }
3166     } else {
3167       // Try to load the agent from the standard dll directory
3168       if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3169                              name)) {
3170         library = os::dll_load(buffer, ebuf, sizeof ebuf);
3171       }
3172       if (library == NULL) { // Try the library path directory.
3173         if (os::dll_build_name(buffer, sizeof(buffer), name)) {
3174           library = os::dll_load(buffer, ebuf, sizeof ebuf);
3175         }
3176         if (library == NULL) {
3177           const char *sub_msg = " on the library path, with error: ";
3178           const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
3179 
3180           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
3181                        strlen(ebuf) + strlen(sub_msg2) + 1;
3182           char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3183           if (!agent->is_instrument_lib()) {
3184             jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3185           } else {
3186             jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
3187           }
3188           // If we can't find the agent, exit.
3189           vm_exit_during_initialization(buf, NULL);
3190           FREE_C_HEAP_ARRAY(char, buf);
3191         }
3192       }
3193     }
3194     agent->set_os_lib(library);
3195     agent->set_valid();
3196   }
3197 
3198   // Find the OnLoad function.
3199   on_load_entry =
3200     CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3201                                                           false,
3202                                                           on_load_symbols,
3203                                                           num_symbol_entries));
3204   return on_load_entry;
3205 }
3206 
3207 // Find the JVM_OnLoad entry point
3208 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3209   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3210   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3211 }
3212 
3213 // Find the Agent_OnLoad entry point
3214 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3215   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3216   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3217 }
3218 
3219 // For backwards compatibility with -Xrun
3220 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3221 // treated like -agentpath:
3222 // Must be called before agent libraries are created
3223 void Threads::convert_vm_init_libraries_to_agents() {
3224   AgentLibrary* agent;
3225   AgentLibrary* next;
3226 
3227   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3228     next = agent->next();  // cache the next agent now as this agent may get moved off this list
3229     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3230 
3231     // If there is an JVM_OnLoad function it will get called later,
3232     // otherwise see if there is an Agent_OnLoad
3233     if (on_load_entry == NULL) {
3234       on_load_entry = lookup_agent_on_load(agent);
3235       if (on_load_entry != NULL) {
3236         // switch it to the agent list -- so that Agent_OnLoad will be called,
3237         // JVM_OnLoad won't be attempted and Agent_OnUnload will
3238         Arguments::convert_library_to_agent(agent);
3239       } else {
3240         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3241       }
3242     }
3243   }
3244 }
3245 
3246 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
3247 // Invokes Agent_OnLoad
3248 // Called very early -- before JavaThreads exist
3249 void Threads::create_vm_init_agents() {
3250   extern struct JavaVM_ main_vm;
3251   AgentLibrary* agent;
3252 
3253   JvmtiExport::enter_onload_phase();
3254 
3255   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3256     // CDS dumping does not support native JVMTI agent.
3257     // CDS dumping supports Java agent if the AllowArchivingWithJavaAgent diagnostic option is specified.
3258     if (Arguments::is_dumping_archive()) {
3259       if(!agent->is_instrument_lib()) {
3260         vm_exit_during_cds_dumping("CDS dumping does not support native JVMTI agent, name", agent->name());
3261       } else if (!AllowArchivingWithJavaAgent) {
3262         vm_exit_during_cds_dumping(
3263           "Must enable AllowArchivingWithJavaAgent in order to run Java agent during CDS dumping");
3264       }
3265     }
3266 
3267     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
3268 
3269     if (on_load_entry != NULL) {
3270       // Invoke the Agent_OnLoad function
3271       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3272       if (err != JNI_OK) {
3273         vm_exit_during_initialization("agent library failed to init", agent->name());
3274       }
3275     } else {
3276       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3277     }
3278   }
3279 
3280   JvmtiExport::enter_primordial_phase();
3281 }
3282 
3283 extern "C" {
3284   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3285 }
3286 
3287 void Threads::shutdown_vm_agents() {
3288   // Send any Agent_OnUnload notifications
3289   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3290   size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
3291   extern struct JavaVM_ main_vm;
3292   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3293 
3294     // Find the Agent_OnUnload function.
3295     Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3296                                                    os::find_agent_function(agent,
3297                                                    false,
3298                                                    on_unload_symbols,
3299                                                    num_symbol_entries));
3300 
3301     // Invoke the Agent_OnUnload function
3302     if (unload_entry != NULL) {
3303       JavaThread* thread = JavaThread::current();
3304       ThreadToNativeFromVM ttn(thread);
3305       HandleMark hm(thread);
3306       (*unload_entry)(&main_vm);
3307     }
3308   }
3309 }
3310 
3311 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
3312 // Invokes JVM_OnLoad
3313 void Threads::create_vm_init_libraries() {
3314   extern struct JavaVM_ main_vm;
3315   AgentLibrary* agent;
3316 
3317   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
3318     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3319 
3320     if (on_load_entry != NULL) {
3321       // Invoke the JVM_OnLoad function
3322       JavaThread* thread = JavaThread::current();
3323       ThreadToNativeFromVM ttn(thread);
3324       HandleMark hm(thread);
3325       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3326       if (err != JNI_OK) {
3327         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
3328       }
3329     } else {
3330       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
3331     }
3332   }
3333 }
3334 
3335 
3336 // Last thread running calls java.lang.Shutdown.shutdown()
3337 void JavaThread::invoke_shutdown_hooks() {
3338   HandleMark hm(this);
3339 
3340   // We could get here with a pending exception, if so clear it now or
3341   // it will cause MetaspaceShared::link_and_cleanup_shared_classes to
3342   // fail for dynamic dump.
3343   if (this->has_pending_exception()) {
3344     this->clear_pending_exception();
3345   }
3346 
3347 #if INCLUDE_CDS
3348   // Link all classes for dynamic CDS dumping before vm exit.
3349   // Same operation is being done in JVM_BeforeHalt for handling the
3350   // case where the application calls System.exit().
3351   if (DynamicDumpSharedSpaces) {
3352     DynamicArchive::prepare_for_dynamic_dumping_at_exit();
3353   }
3354 #endif
3355 
3356   EXCEPTION_MARK;
3357   Klass* shutdown_klass =
3358     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
3359                                       THREAD);
3360   if (shutdown_klass != NULL) {
3361     // SystemDictionary::resolve_or_null will return null if there was
3362     // an exception.  If we cannot load the Shutdown class, just don't
3363     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
3364     // won't be run.  Note that if a shutdown hook was registered,
3365     // the Shutdown class would have already been loaded
3366     // (Runtime.addShutdownHook will load it).
3367     JavaValue result(T_VOID);
3368     JavaCalls::call_static(&result,
3369                            shutdown_klass,
3370                            vmSymbols::shutdown_name(),
3371                            vmSymbols::void_method_signature(),
3372                            THREAD);
3373   }
3374   CLEAR_PENDING_EXCEPTION;
3375 }
3376 
3377 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
3378 // the program falls off the end of main(). Another VM exit path is through
3379 // vm_exit() when the program calls System.exit() to return a value or when
3380 // there is a serious error in VM. The two shutdown paths are not exactly
3381 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
3382 // and VM_Exit op at VM level.
3383 //
3384 // Shutdown sequence:
3385 //   + Shutdown native memory tracking if it is on
3386 //   + Wait until we are the last non-daemon thread to execute
3387 //     <-- every thing is still working at this moment -->
3388 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
3389 //        shutdown hooks
3390 //   + Call before_exit(), prepare for VM exit
3391 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
3392 //        currently the only user of this mechanism is File.deleteOnExit())
3393 //      > stop StatSampler, watcher thread,
3394 //        post thread end and vm death events to JVMTI,
3395 //        stop signal thread
3396 //   + Call JavaThread::exit(), it will:
3397 //      > release JNI handle blocks, remove stack guard pages
3398 //      > remove this thread from Threads list
3399 //     <-- no more Java code from this thread after this point -->
3400 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
3401 //     the compiler threads at safepoint
3402 //     <-- do not use anything that could get blocked by Safepoint -->
3403 //   + Disable tracing at JNI/JVM barriers
3404 //   + Set _vm_exited flag for threads that are still running native code
3405 //   + Call exit_globals()
3406 //      > deletes tty
3407 //      > deletes PerfMemory resources
3408 //   + Delete this thread
3409 //   + Return to caller
3410 
3411 void Threads::destroy_vm() {
3412   JavaThread* thread = JavaThread::current();
3413 
3414 #ifdef ASSERT
3415   _vm_complete = false;
3416 #endif
3417   // Wait until we are the last non-daemon thread to execute
3418   {
3419     MonitorLocker nu(Threads_lock);
3420     while (Threads::number_of_non_daemon_threads() > 1)
3421       // This wait should make safepoint checks, wait without a timeout.
3422       nu.wait(0);
3423   }
3424 
3425   EventShutdown e;
3426   if (e.should_commit()) {
3427     e.set_reason("No remaining non-daemon Java threads");
3428     e.commit();
3429   }
3430 
3431   // Hang forever on exit if we are reporting an error.
3432   if (ShowMessageBoxOnError && VMError::is_error_reported()) {
3433     os::infinite_sleep();
3434   }
3435   os::wait_for_keypress_at_exit();
3436 
3437   // run Java level shutdown hooks
3438   thread->invoke_shutdown_hooks();
3439 
3440   before_exit(thread);
3441 
3442   thread->exit(true);
3443 
3444   // We are no longer on the main thread list but could still be in a
3445   // secondary list where another thread may try to interact with us.
3446   // So wait until all such interactions are complete before we bring
3447   // the VM to the termination safepoint. Normally this would be done
3448   // using thread->smr_delete() below where we delete the thread, but
3449   // we can't call that after the termination safepoint is active as
3450   // we will deadlock on the Threads_lock. Once all interactions are
3451   // complete it is safe to directly delete the thread at any time.
3452   ThreadsSMRSupport::wait_until_not_protected(thread);
3453 
3454   // Stop VM thread.
3455   {
3456     // 4945125 The vm thread comes to a safepoint during exit.
3457     // GC vm_operations can get caught at the safepoint, and the
3458     // heap is unparseable if they are caught. Grab the Heap_lock
3459     // to prevent this. The GC vm_operations will not be able to
3460     // queue until after the vm thread is dead. After this point,
3461     // we'll never emerge out of the safepoint before the VM exits.
3462     // Assert that the thread is terminated so that acquiring the
3463     // Heap_lock doesn't cause the terminated thread to participate in
3464     // the safepoint protocol.
3465 
3466     assert(thread->is_terminated(), "must be terminated here");
3467     MutexLocker ml(Heap_lock);
3468 
3469     VMThread::wait_for_vm_thread_exit();
3470     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
3471     VMThread::destroy();
3472   }
3473 
3474   // Now, all Java threads are gone except daemon threads. Daemon threads
3475   // running Java code or in VM are stopped by the Safepoint. However,
3476   // daemon threads executing native code are still running.  But they
3477   // will be stopped at native=>Java/VM barriers. Note that we can't
3478   // simply kill or suspend them, as it is inherently deadlock-prone.
3479 
3480   VM_Exit::set_vm_exited();
3481 
3482   // Clean up ideal graph printers after the VMThread has started
3483   // the final safepoint which will block all the Compiler threads.
3484   // Note that this Thread has already logically exited so the
3485   // clean_up() function's use of a JavaThreadIteratorWithHandle
3486   // would be a problem except set_vm_exited() has remembered the
3487   // shutdown thread which is granted a policy exception.
3488 #if defined(COMPILER2) && !defined(PRODUCT)
3489   IdealGraphPrinter::clean_up();
3490 #endif
3491 
3492   notify_vm_shutdown();
3493 
3494   // exit_globals() will delete tty
3495   exit_globals();
3496 
3497   // Deleting the shutdown thread here is safe. See comment on
3498   // wait_until_not_protected() above.
3499   delete thread;
3500 
3501 #if INCLUDE_JVMCI
3502   if (JVMCICounterSize > 0) {
3503     FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
3504   }
3505 #endif
3506 
3507   LogConfiguration::finalize();
3508 }
3509 
3510 
3511 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
3512   if (version == JNI_VERSION_1_1) return JNI_TRUE;
3513   return is_supported_jni_version(version);
3514 }
3515 
3516 
3517 jboolean Threads::is_supported_jni_version(jint version) {
3518   if (version == JNI_VERSION_1_2) return JNI_TRUE;
3519   if (version == JNI_VERSION_1_4) return JNI_TRUE;
3520   if (version == JNI_VERSION_1_6) return JNI_TRUE;
3521   if (version == JNI_VERSION_1_8) return JNI_TRUE;
3522   if (version == JNI_VERSION_9) return JNI_TRUE;
3523   if (version == JNI_VERSION_10) return JNI_TRUE;
3524   return JNI_FALSE;
3525 }
3526 
3527 
3528 void Threads::add(JavaThread* p, bool force_daemon) {
3529   // The threads lock must be owned at this point
3530   assert(Threads_lock->owned_by_self(), "must have threads lock");
3531 
3532   BarrierSet::barrier_set()->on_thread_attach(p);
3533 
3534   // Once a JavaThread is added to the Threads list, smr_delete() has
3535   // to be used to delete it. Otherwise we can just delete it directly.
3536   p->set_on_thread_list();
3537 
3538   _number_of_threads++;
3539   oop threadObj = p->threadObj();
3540   bool daemon = true;
3541   // Bootstrapping problem: threadObj can be null for initial
3542   // JavaThread (or for threads attached via JNI)
3543   if ((!force_daemon) && !is_daemon((threadObj))) {
3544     _number_of_non_daemon_threads++;
3545     daemon = false;
3546   }
3547 
3548   ThreadService::add_thread(p, daemon);
3549 
3550   // Maintain fast thread list
3551   ThreadsSMRSupport::add_thread(p);
3552 
3553   // Increase the ObjectMonitor ceiling for the new thread.
3554   ObjectSynchronizer::inc_in_use_list_ceiling();
3555 
3556   // Possible GC point.
3557   Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
3558 
3559   // Make new thread known to active EscapeBarrier
3560   EscapeBarrier::thread_added(p);
3561 }
3562 
3563 void Threads::remove(JavaThread* p, bool is_daemon) {
3564   // Extra scope needed for Thread_lock, so we can check
3565   // that we do not remove thread without safepoint code notice
3566   { MonitorLocker ml(Threads_lock);
3567 
3568     // BarrierSet state must be destroyed after the last thread transition
3569     // before the thread terminates. Thread transitions result in calls to
3570     // StackWatermarkSet::on_safepoint(), which performs GC processing,
3571     // requiring the GC state to be alive.
3572     BarrierSet::barrier_set()->on_thread_detach(p);
3573 
3574     assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
3575 
3576     // Maintain fast thread list
3577     ThreadsSMRSupport::remove_thread(p);
3578 
3579     _number_of_threads--;
3580     if (!is_daemon) {
3581       _number_of_non_daemon_threads--;
3582 
3583       // Only one thread left, do a notify on the Threads_lock so a thread waiting
3584       // on destroy_vm will wake up.
3585       if (number_of_non_daemon_threads() == 1) {
3586         ml.notify_all();
3587       }
3588     }
3589     ThreadService::remove_thread(p, is_daemon);
3590 
3591     // Make sure that safepoint code disregard this thread. This is needed since
3592     // the thread might mess around with locks after this point. This can cause it
3593     // to do callbacks into the safepoint code. However, the safepoint code is not aware
3594     // of this thread since it is removed from the queue.
3595     p->set_terminated(JavaThread::_thread_terminated);
3596 
3597     // Notify threads waiting in EscapeBarriers
3598     EscapeBarrier::thread_removed(p);
3599   } // unlock Threads_lock
3600 
3601   // Reduce the ObjectMonitor ceiling for the exiting thread.
3602   ObjectSynchronizer::dec_in_use_list_ceiling();
3603 
3604   // Since Events::log uses a lock, we grab it outside the Threads_lock
3605   Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
3606 }
3607 
3608 // Operations on the Threads list for GC.  These are not explicitly locked,
3609 // but the garbage collector must provide a safe context for them to run.
3610 // In particular, these things should never be called when the Threads_lock
3611 // is held by some other thread. (Note: the Safepoint abstraction also
3612 // uses the Threads_lock to guarantee this property. It also makes sure that
3613 // all threads gets blocked when exiting or starting).
3614 
3615 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3616   ALL_JAVA_THREADS(p) {
3617     p->oops_do(f, cf);
3618   }
3619   VMThread::vm_thread()->oops_do(f, cf);
3620 }
3621 
3622 void Threads::change_thread_claim_token() {
3623   if (++_thread_claim_token == 0) {
3624     // On overflow of the token counter, there is a risk of future
3625     // collisions between a new global token value and a stale token
3626     // for a thread, because not all iterations visit all threads.
3627     // (Though it's pretty much a theoretical concern for non-trivial
3628     // token counter sizes.)  To deal with the possibility, reset all
3629     // the thread tokens to zero on global token overflow.
3630     struct ResetClaims : public ThreadClosure {
3631       virtual void do_thread(Thread* t) {
3632         t->claim_threads_do(false, 0);
3633       }
3634     } reset_claims;
3635     Threads::threads_do(&reset_claims);
3636     // On overflow, update the global token to non-zero, to
3637     // avoid the special "never claimed" initial thread value.
3638     _thread_claim_token = 1;
3639   }
3640 }
3641 
3642 #ifdef ASSERT
3643 void assert_thread_claimed(const char* kind, Thread* t, uintx expected) {
3644   const uintx token = t->threads_do_token();
3645   assert(token == expected,
3646          "%s " PTR_FORMAT " has incorrect value " UINTX_FORMAT " != "
3647          UINTX_FORMAT, kind, p2i(t), token, expected);
3648 }
3649 
3650 void Threads::assert_all_threads_claimed() {
3651   ALL_JAVA_THREADS(p) {
3652     assert_thread_claimed("Thread", p, _thread_claim_token);
3653   }
3654   assert_thread_claimed("VMThread", VMThread::vm_thread(), _thread_claim_token);
3655 }
3656 #endif // ASSERT
3657 
3658 class ParallelOopsDoThreadClosure : public ThreadClosure {
3659 private:
3660   OopClosure* _f;
3661   CodeBlobClosure* _cf;
3662 public:
3663   ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
3664   void do_thread(Thread* t) {
3665     t->oops_do(_f, _cf);
3666   }
3667 };
3668 
3669 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
3670   ParallelOopsDoThreadClosure tc(f, cf);
3671   possibly_parallel_threads_do(is_par, &tc);
3672 }
3673 
3674 void Threads::metadata_do(MetadataClosure* f) {
3675   ALL_JAVA_THREADS(p) {
3676     p->metadata_do(f);
3677   }
3678 }
3679 
3680 class ThreadHandlesClosure : public ThreadClosure {
3681   void (*_f)(Metadata*);
3682  public:
3683   ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
3684   virtual void do_thread(Thread* thread) {
3685     thread->metadata_handles_do(_f);
3686   }
3687 };
3688 
3689 void Threads::metadata_handles_do(void f(Metadata*)) {
3690   // Only walk the Handles in Thread.
3691   ThreadHandlesClosure handles_closure(f);
3692   threads_do(&handles_closure);
3693 }
3694 
3695 // Get count Java threads that are waiting to enter the specified monitor.
3696 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
3697                                                          int count,
3698                                                          address monitor) {
3699   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
3700 
3701   int i = 0;
3702   DO_JAVA_THREADS(t_list, p) {
3703     if (!p->can_call_java()) continue;
3704 
3705     // The first stage of async deflation does not affect any field
3706     // used by this comparison so the ObjectMonitor* is usable here.
3707     address pending = (address)p->current_pending_monitor();
3708     if (pending == monitor) {             // found a match
3709       if (i < count) result->append(p);   // save the first count matches
3710       i++;
3711     }
3712   }
3713 
3714   return result;
3715 }
3716 
3717 
3718 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
3719                                                       address owner) {
3720   assert(!UseFastLocking, "only with stack-locking");
3721   // NULL owner means not locked so we can skip the search
3722   if (owner == NULL) return NULL;
3723 
3724   DO_JAVA_THREADS(t_list, p) {
3725     // first, see if owner is the address of a Java thread
3726     if (owner == (address)p) return p;
3727   }
3728 
3729   // Cannot assert on lack of success here since this function may be
3730   // used by code that is trying to report useful problem information
3731   // like deadlock detection.
3732   if (UseHeavyMonitors) return NULL;
3733 
3734   // If we didn't find a matching Java thread and we didn't force use of
3735   // heavyweight monitors, then the owner is the stack address of the
3736   // Lock Word in the owning Java thread's stack.
3737   //
3738   JavaThread* the_owner = NULL;
3739   DO_JAVA_THREADS(t_list, q) {
3740     if (q->is_lock_owned(owner)) {
3741       the_owner = q;
3742       break;
3743     }
3744   }
3745 
3746   // cannot assert on lack of success here; see above comment
3747   return the_owner;
3748 }
3749 
3750 JavaThread* Threads::owning_thread_from_object(ThreadsList * t_list, oop obj) {
3751   assert(UseFastLocking, "Only with fast-locking");
3752   DO_JAVA_THREADS(t_list, q) {
3753     if (q->lock_stack().contains(obj)) {
3754       return q;
3755     }
3756   }
3757   return NULL;
3758 }
3759 
3760 JavaThread* Threads::owning_thread_from_monitor(ThreadsList* t_list, ObjectMonitor* monitor) {
3761   if (UseFastLocking) {
3762     void* raw_owner = monitor->owner_raw();
3763     if (raw_owner == ANONYMOUS_OWNER) {
3764       return owning_thread_from_object(t_list, monitor->object());
3765     } else if (raw_owner == DEFLATER_MARKER) {
3766       return NULL;
3767     } else {
3768       Thread* owner = reinterpret_cast<Thread*>(raw_owner);
3769 #ifdef ASSERT
3770       if (owner != NULL) {
3771         bool found = false;
3772         DO_JAVA_THREADS(t_list, q) {
3773           if (q == owner) {
3774             found = true;;
3775             break;
3776           }
3777         }
3778         assert(found, "owner is not a thread: " PTR_FORMAT, p2i(owner));
3779       }
3780 #endif
3781       assert(owner == NULL || owner->is_Java_thread(), "only JavaThreads own monitors");
3782       return reinterpret_cast<JavaThread*>(owner);
3783     }
3784   } else {
3785     return owning_thread_from_monitor_owner(t_list, (address)monitor->owner());
3786   }
3787 }
3788 
3789 class PrintOnClosure : public ThreadClosure {
3790 private:
3791   outputStream* _st;
3792 
3793 public:
3794   PrintOnClosure(outputStream* st) :
3795       _st(st) {}
3796 
3797   virtual void do_thread(Thread* thread) {
3798     if (thread != NULL) {
3799       thread->print_on(_st);
3800       _st->cr();
3801     }
3802   }
3803 };
3804 
3805 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
3806 void Threads::print_on(outputStream* st, bool print_stacks,
3807                        bool internal_format, bool print_concurrent_locks,
3808                        bool print_extended_info) {
3809   char buf[32];
3810   st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
3811 
3812   st->print_cr("Full thread dump %s (%s %s):",
3813                VM_Version::vm_name(),
3814                VM_Version::vm_release(),
3815                VM_Version::vm_info_string());
3816   st->cr();
3817 
3818 #if INCLUDE_SERVICES
3819   // Dump concurrent locks
3820   ConcurrentLocksDump concurrent_locks;
3821   if (print_concurrent_locks) {
3822     concurrent_locks.dump_at_safepoint();
3823   }
3824 #endif // INCLUDE_SERVICES
3825 
3826   ThreadsSMRSupport::print_info_on(st);
3827   st->cr();
3828 
3829   ALL_JAVA_THREADS(p) {
3830     ResourceMark rm;
3831     p->print_on(st, print_extended_info);
3832     if (print_stacks) {
3833       if (internal_format) {
3834         p->trace_stack();
3835       } else {
3836         p->print_stack_on(st);
3837       }
3838     }
3839     st->cr();
3840 #if INCLUDE_SERVICES
3841     if (print_concurrent_locks) {
3842       concurrent_locks.print_locks_on(p, st);
3843     }
3844 #endif // INCLUDE_SERVICES
3845   }
3846 
3847   PrintOnClosure cl(st);
3848   cl.do_thread(VMThread::vm_thread());
3849   Universe::heap()->gc_threads_do(&cl);
3850   if (StringDedup::is_enabled()) {
3851     StringDedup::threads_do(&cl);
3852   }
3853   cl.do_thread(WatcherThread::watcher_thread());
3854   cl.do_thread(AsyncLogWriter::instance());
3855 
3856   st->flush();
3857 }
3858 
3859 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
3860                              int buflen, bool* found_current) {
3861   if (this_thread != NULL) {
3862     bool is_current = (current == this_thread);
3863     *found_current = *found_current || is_current;
3864     st->print("%s", is_current ? "=>" : "  ");
3865 
3866     st->print(PTR_FORMAT, p2i(this_thread));
3867     st->print(" ");
3868     this_thread->print_on_error(st, buf, buflen);
3869     st->cr();
3870   }
3871 }
3872 
3873 class PrintOnErrorClosure : public ThreadClosure {
3874   outputStream* _st;
3875   Thread* _current;
3876   char* _buf;
3877   int _buflen;
3878   bool* _found_current;
3879  public:
3880   PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
3881                       int buflen, bool* found_current) :
3882    _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
3883 
3884   virtual void do_thread(Thread* thread) {
3885     Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
3886   }
3887 };
3888 
3889 // Threads::print_on_error() is called by fatal error handler. It's possible
3890 // that VM is not at safepoint and/or current thread is inside signal handler.
3891 // Don't print stack trace, as the stack may not be walkable. Don't allocate
3892 // memory (even in resource area), it might deadlock the error handler.
3893 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
3894                              int buflen) {
3895   ThreadsSMRSupport::print_info_on(st);
3896   st->cr();
3897 
3898   bool found_current = false;
3899   st->print_cr("Java Threads: ( => current thread )");
3900   ALL_JAVA_THREADS(thread) {
3901     print_on_error(thread, st, current, buf, buflen, &found_current);
3902   }
3903   st->cr();
3904 
3905   st->print_cr("Other Threads:");
3906   print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
3907   print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
3908   print_on_error(AsyncLogWriter::instance(), st, current, buf, buflen, &found_current);
3909 
3910   if (Universe::heap() != NULL) {
3911     PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
3912     Universe::heap()->gc_threads_do(&print_closure);
3913   }
3914 
3915   if (StringDedup::is_enabled()) {
3916     PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
3917     StringDedup::threads_do(&print_closure);
3918   }
3919 
3920   if (!found_current) {
3921     st->cr();
3922     st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
3923     current->print_on_error(st, buf, buflen);
3924     st->cr();
3925   }
3926   st->cr();
3927 
3928   st->print_cr("Threads with active compile tasks:");
3929   print_threads_compiling(st, buf, buflen);
3930 }
3931 
3932 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen, bool short_form) {
3933   ALL_JAVA_THREADS(thread) {
3934     if (thread->is_Compiler_thread()) {
3935       CompilerThread* ct = (CompilerThread*) thread;
3936 
3937       // Keep task in local variable for NULL check.
3938       // ct->_task might be set to NULL by concurring compiler thread
3939       // because it completed the compilation. The task is never freed,
3940       // though, just returned to a free list.
3941       CompileTask* task = ct->task();
3942       if (task != NULL) {
3943         thread->print_name_on_error(st, buf, buflen);
3944         st->print("  ");
3945         task->print(st, NULL, short_form, true);
3946       }
3947     }
3948   }
3949 }
3950 
3951 
3952 // Ad-hoc mutual exclusion primitives: SpinLock
3953 //
3954 // We employ SpinLocks _only for low-contention, fixed-length
3955 // short-duration critical sections where we're concerned
3956 // about native mutex_t or HotSpot Mutex:: latency.
3957 //
3958 // TODO-FIXME: ListLock should be of type SpinLock.
3959 // We should make this a 1st-class type, integrated into the lock
3960 // hierarchy as leaf-locks.  Critically, the SpinLock structure
3961 // should have sufficient padding to avoid false-sharing and excessive
3962 // cache-coherency traffic.
3963 
3964 
3965 typedef volatile int SpinLockT;
3966 
3967 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
3968   if (Atomic::cmpxchg(adr, 0, 1) == 0) {
3969     return;   // normal fast-path return
3970   }
3971 
3972   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
3973   int ctr = 0;
3974   int Yields = 0;
3975   for (;;) {
3976     while (*adr != 0) {
3977       ++ctr;
3978       if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
3979         if (Yields > 5) {
3980           os::naked_short_sleep(1);
3981         } else {
3982           os::naked_yield();
3983           ++Yields;
3984         }
3985       } else {
3986         SpinPause();
3987       }
3988     }
3989     if (Atomic::cmpxchg(adr, 0, 1) == 0) return;
3990   }
3991 }
3992 
3993 void Thread::SpinRelease(volatile int * adr) {
3994   assert(*adr != 0, "invariant");
3995   OrderAccess::fence();      // guarantee at least release consistency.
3996   // Roach-motel semantics.
3997   // It's safe if subsequent LDs and STs float "up" into the critical section,
3998   // but prior LDs and STs within the critical section can't be allowed
3999   // to reorder or float past the ST that releases the lock.
4000   // Loads and stores in the critical section - which appear in program
4001   // order before the store that releases the lock - must also appear
4002   // before the store that releases the lock in memory visibility order.
4003   // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4004   // the ST of 0 into the lock-word which releases the lock, so fence
4005   // more than covers this on all platforms.
4006   *adr = 0;
4007 }
4008 
4009 
4010 void Threads::verify() {
4011   ALL_JAVA_THREADS(p) {
4012     p->verify();
4013   }
4014   VMThread* thread = VMThread::vm_thread();
4015   if (thread != NULL) thread->verify();
4016 }
4017 
4018 #ifndef PRODUCT
4019 void JavaThread::verify_cross_modify_fence_failure(JavaThread *thread) {
4020    report_vm_error(__FILE__, __LINE__, "Cross modify fence failure", "%p", thread);
4021 }
4022 #endif