1 /*
   2  * Copyright (c) 1997, 2024, 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 "cds/dynamicArchive.hpp"
  28 #include "ci/ciEnv.hpp"
  29 #include "classfile/javaClasses.inline.hpp"
  30 #include "classfile/javaThreadStatus.hpp"
  31 #include "classfile/systemDictionary.hpp"
  32 #include "classfile/vmClasses.hpp"
  33 #include "classfile/vmSymbols.hpp"
  34 #include "code/codeCache.hpp"
  35 #include "code/scopeDesc.hpp"
  36 #include "compiler/compileTask.hpp"
  37 #include "compiler/compilerThread.hpp"
  38 #include "gc/shared/oopStorage.hpp"
  39 #include "gc/shared/oopStorageSet.hpp"
  40 #include "gc/shared/tlab_globals.hpp"
  41 #include "jfr/jfrEvents.hpp"
  42 #include "jvm.h"
  43 #include "jvmtifiles/jvmtiEnv.hpp"
  44 #include "logging/log.hpp"
  45 #include "logging/logAsyncWriter.hpp"
  46 #include "logging/logStream.hpp"
  47 #include "memory/allocation.inline.hpp"
  48 #include "memory/iterator.hpp"
  49 #include "memory/universe.hpp"
  50 #include "oops/access.inline.hpp"
  51 #include "oops/instanceKlass.hpp"
  52 #include "oops/klass.inline.hpp"
  53 #include "oops/oop.inline.hpp"
  54 #include "oops/oopHandle.inline.hpp"
  55 #include "oops/verifyOopClosure.hpp"
  56 #include "prims/jvm_misc.hpp"
  57 #include "prims/jvmtiDeferredUpdates.hpp"
  58 #include "prims/jvmtiExport.hpp"
  59 #include "prims/jvmtiThreadState.inline.hpp"
  60 #include "runtime/atomic.hpp"
  61 #include "runtime/continuation.hpp"
  62 #include "runtime/continuationEntry.inline.hpp"
  63 #include "runtime/continuationHelper.inline.hpp"
  64 #include "runtime/deoptimization.hpp"
  65 #include "runtime/frame.inline.hpp"
  66 #include "runtime/handles.inline.hpp"
  67 #include "runtime/handshake.hpp"
  68 #include "runtime/interfaceSupport.inline.hpp"
  69 #include "runtime/java.hpp"
  70 #include "runtime/javaCalls.hpp"
  71 #include "runtime/javaThread.inline.hpp"
  72 #include "runtime/jniHandles.inline.hpp"
  73 #include "runtime/lockStack.inline.hpp"
  74 #include "runtime/mutexLocker.hpp"
  75 #include "runtime/orderAccess.hpp"
  76 #include "runtime/os.inline.hpp"
  77 #include "runtime/osThread.hpp"
  78 #include "runtime/safepoint.hpp"
  79 #include "runtime/safepointMechanism.inline.hpp"
  80 #include "runtime/safepointVerifiers.hpp"
  81 #include "runtime/serviceThread.hpp"
  82 #include "runtime/stackFrameStream.inline.hpp"
  83 #include "runtime/stackWatermarkSet.hpp"
  84 #include "runtime/synchronizer.hpp"
  85 #include "runtime/threadCritical.hpp"
  86 #include "runtime/threadIdentifier.hpp"
  87 #include "runtime/threadSMR.inline.hpp"
  88 #include "runtime/threadStatisticalInfo.hpp"
  89 #include "runtime/threadWXSetters.inline.hpp"
  90 #include "runtime/timer.hpp"
  91 #include "runtime/timerTrace.hpp"
  92 #include "runtime/vframe.inline.hpp"
  93 #include "runtime/vframeArray.hpp"
  94 #include "runtime/vframe_hp.hpp"
  95 #include "runtime/vmThread.hpp"
  96 #include "runtime/vmOperations.hpp"
  97 #include "services/threadService.hpp"
  98 #include "utilities/copy.hpp"
  99 #include "utilities/defaultStream.hpp"
 100 #include "utilities/dtrace.hpp"
 101 #include "utilities/events.hpp"
 102 #include "utilities/macros.hpp"
 103 #include "utilities/preserveException.hpp"
 104 #include "utilities/spinYield.hpp"
 105 #include "utilities/vmError.hpp"
 106 #if INCLUDE_JVMCI
 107 #include "jvmci/jvmci.hpp"
 108 #include "jvmci/jvmciEnv.hpp"
 109 #endif
 110 #if INCLUDE_JFR
 111 #include "jfr/jfr.hpp"
 112 #endif
 113 
 114 // Set by os layer.
 115 size_t      JavaThread::_stack_size_at_create = 0;
 116 
 117 #ifdef DTRACE_ENABLED
 118 
 119 // Only bother with this argument setup if dtrace is available
 120 
 121   #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
 122   #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
 123 
 124   #define DTRACE_THREAD_PROBE(probe, javathread)                           \
 125     {                                                                      \
 126       ResourceMark rm(this);                                               \
 127       int len = 0;                                                         \
 128       const char* name = (javathread)->name();                             \
 129       len = strlen(name);                                                  \
 130       HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */               \
 131         (char *) name, len,                                                \
 132         java_lang_Thread::thread_id((javathread)->threadObj()),            \
 133         (uintptr_t) (javathread)->osthread()->thread_id(),                 \
 134         java_lang_Thread::is_daemon((javathread)->threadObj()));           \
 135     }
 136 
 137 #else //  ndef DTRACE_ENABLED
 138 
 139   #define DTRACE_THREAD_PROBE(probe, javathread)
 140 
 141 #endif // ndef DTRACE_ENABLED
 142 
 143 void JavaThread::smr_delete() {
 144   if (_on_thread_list) {
 145     ThreadsSMRSupport::smr_delete(this);
 146   } else {
 147     delete this;
 148   }
 149 }
 150 
 151 // Initialized by VMThread at vm_global_init
 152 OopStorage* JavaThread::_thread_oop_storage = nullptr;
 153 
 154 OopStorage* JavaThread::thread_oop_storage() {
 155   assert(_thread_oop_storage != nullptr, "not yet initialized");
 156   return _thread_oop_storage;
 157 }
 158 
 159 void JavaThread::set_threadOopHandles(oop p) {
 160   assert(_thread_oop_storage != nullptr, "not yet initialized");
 161   _threadObj   = OopHandle(_thread_oop_storage, p);
 162   _vthread     = OopHandle(_thread_oop_storage, p);
 163   _jvmti_vthread = OopHandle(_thread_oop_storage, p->is_a(vmClasses::BoundVirtualThread_klass()) ? p : nullptr);
 164   _scopedValueCache = OopHandle(_thread_oop_storage, nullptr);
 165 }
 166 
 167 oop JavaThread::threadObj() const {
 168   // Ideally we would verify the current thread is oop_safe when this is called, but as we can
 169   // be called from a signal handler we would have to use Thread::current_or_null_safe(). That
 170   // has overhead and also interacts poorly with GetLastError on Windows due to the use of TLS.
 171   // Instead callers must verify oop safe access.
 172   return _threadObj.resolve();
 173 }
 174 
 175 oop JavaThread::vthread() const {
 176   return _vthread.resolve();
 177 }
 178 
 179 void JavaThread::set_vthread(oop p) {
 180   assert(_thread_oop_storage != nullptr, "not yet initialized");
 181   _vthread.replace(p);
 182 }
 183 
 184 oop JavaThread::jvmti_vthread() const {
 185   return _jvmti_vthread.resolve();
 186 }
 187 
 188 void JavaThread::set_jvmti_vthread(oop p) {
 189   assert(_thread_oop_storage != nullptr, "not yet initialized");
 190   _jvmti_vthread.replace(p);
 191 }
 192 
 193 // If there is a virtual thread mounted then return vthread() oop.
 194 // Otherwise, return threadObj().
 195 oop JavaThread::vthread_or_thread() const {
 196   oop result = vthread();
 197   if (result == nullptr) {
 198     result = threadObj();
 199   }
 200   return result;
 201 }
 202 
 203 oop JavaThread::scopedValueCache() const {
 204   return _scopedValueCache.resolve();
 205 }
 206 
 207 void JavaThread::set_scopedValueCache(oop p) {
 208   if (!_scopedValueCache.is_empty()) { // i.e. if the OopHandle has been allocated
 209     _scopedValueCache.replace(p);
 210   } else {
 211     assert(p == nullptr, "not yet initialized");
 212   }
 213 }
 214 
 215 void JavaThread::clear_scopedValueBindings() {
 216   set_scopedValueCache(nullptr);
 217   oop vthread_oop = vthread();
 218   // vthread may be null here if we get a VM error during startup,
 219   // before the java.lang.Thread instance has been created.
 220   if (vthread_oop != nullptr) {
 221     java_lang_Thread::clear_scopedValueBindings(vthread_oop);
 222   }
 223 }
 224 
 225 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
 226                                     bool daemon, TRAPS) {
 227   assert(thread_group.not_null(), "thread group should be specified");
 228   assert(threadObj() == nullptr, "should only create Java thread object once");
 229 
 230   InstanceKlass* ik = vmClasses::Thread_klass();
 231   assert(ik->is_initialized(), "must be");
 232   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
 233 
 234   // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon.
 235   // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread
 236   // constructor calls Thread.current(), which must be set here.
 237   java_lang_Thread::set_thread(thread_oop(), this);
 238   set_threadOopHandles(thread_oop());
 239   // Set the lock_id to the next thread_id temporarily while initialization runs.
 240   set_lock_id(ThreadIdentifier::next());
 241 
 242   JavaValue result(T_VOID);
 243   if (thread_name != nullptr) {
 244     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
 245     // Thread gets assigned specified name and null target
 246     JavaCalls::call_special(&result,
 247                             thread_oop,
 248                             ik,
 249                             vmSymbols::object_initializer_name(),
 250                             vmSymbols::threadgroup_string_void_signature(),
 251                             thread_group,
 252                             name,
 253                             CHECK);
 254   } else {
 255     // Thread gets assigned name "Thread-nnn" and null target
 256     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
 257     JavaCalls::call_special(&result,
 258                             thread_oop,
 259                             ik,
 260                             vmSymbols::object_initializer_name(),
 261                             vmSymbols::threadgroup_runnable_void_signature(),
 262                             thread_group,
 263                             Handle(),
 264                             CHECK);
 265   }
 266   // Update the lock_id with the tid value.
 267   set_lock_id(java_lang_Thread::thread_id(thread_oop()));
 268 
 269   os::set_priority(this, NormPriority);
 270 
 271   if (daemon) {
 272     java_lang_Thread::set_daemon(thread_oop());
 273   }
 274 }
 275 
 276 // ======= JavaThread ========
 277 
 278 #if INCLUDE_JVMCI
 279 
 280 jlong* JavaThread::_jvmci_old_thread_counters;
 281 
 282 static bool jvmci_counters_include(JavaThread* thread) {
 283   return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
 284 }
 285 
 286 void JavaThread::collect_counters(jlong* array, int length) {
 287   assert(length == JVMCICounterSize, "wrong value");
 288   for (int i = 0; i < length; i++) {
 289     array[i] = _jvmci_old_thread_counters[i];
 290   }
 291   for (JavaThread* tp : ThreadsListHandle()) {
 292     if (jvmci_counters_include(tp)) {
 293       for (int i = 0; i < length; i++) {
 294         array[i] += tp->_jvmci_counters[i];
 295       }
 296     }
 297   }
 298 }
 299 
 300 // Attempt to enlarge the array for per thread counters.
 301 static jlong* resize_counters_array(jlong* old_counters, int current_size, int new_size) {
 302   jlong* new_counters = NEW_C_HEAP_ARRAY_RETURN_NULL(jlong, new_size, mtJVMCI);
 303   if (new_counters == nullptr) {
 304     return nullptr;
 305   }
 306   if (old_counters == nullptr) {
 307     old_counters = new_counters;
 308     memset(old_counters, 0, sizeof(jlong) * new_size);
 309   } else {
 310     for (int i = 0; i < MIN2((int) current_size, new_size); i++) {
 311       new_counters[i] = old_counters[i];
 312     }
 313     if (new_size > current_size) {
 314       memset(new_counters + current_size, 0, sizeof(jlong) * (new_size - current_size));
 315     }
 316     FREE_C_HEAP_ARRAY(jlong, old_counters);
 317   }
 318   return new_counters;
 319 }
 320 
 321 // Attempt to enlarge the array for per thread counters.
 322 bool JavaThread::resize_counters(int current_size, int new_size) {
 323   jlong* new_counters = resize_counters_array(_jvmci_counters, current_size, new_size);
 324   if (new_counters == nullptr) {
 325     return false;
 326   } else {
 327     _jvmci_counters = new_counters;
 328     return true;
 329   }
 330 }
 331 
 332 class VM_JVMCIResizeCounters : public VM_Operation {
 333  private:
 334   int _new_size;
 335   bool _failed;
 336 
 337  public:
 338   VM_JVMCIResizeCounters(int new_size) : _new_size(new_size), _failed(false) { }
 339   VMOp_Type type()                  const        { return VMOp_JVMCIResizeCounters; }
 340   bool allow_nested_vm_operations() const        { return true; }
 341   void doit() {
 342     // Resize the old thread counters array
 343     jlong* new_counters = resize_counters_array(JavaThread::_jvmci_old_thread_counters, JVMCICounterSize, _new_size);
 344     if (new_counters == nullptr) {
 345       _failed = true;
 346       return;
 347     } else {
 348       JavaThread::_jvmci_old_thread_counters = new_counters;
 349     }
 350 
 351     // Now resize each threads array
 352     for (JavaThread* tp : ThreadsListHandle()) {
 353       if (!tp->resize_counters(JVMCICounterSize, _new_size)) {
 354         _failed = true;
 355         break;
 356       }
 357     }
 358     if (!_failed) {
 359       JVMCICounterSize = _new_size;
 360     }
 361   }
 362 
 363   bool failed() { return _failed; }
 364 };
 365 
 366 bool JavaThread::resize_all_jvmci_counters(int new_size) {
 367   VM_JVMCIResizeCounters op(new_size);
 368   VMThread::execute(&op);
 369   return !op.failed();
 370 }
 371 
 372 #endif // INCLUDE_JVMCI
 373 
 374 #ifdef ASSERT
 375 // Checks safepoint allowed and clears unhandled oops at potential safepoints.
 376 void JavaThread::check_possible_safepoint() {
 377   if (_no_safepoint_count > 0) {
 378     print_owned_locks();
 379     assert(false, "Possible safepoint reached by thread that does not allow it");
 380   }
 381 #ifdef CHECK_UNHANDLED_OOPS
 382   // Clear unhandled oops in JavaThreads so we get a crash right away.
 383   clear_unhandled_oops();
 384 #endif // CHECK_UNHANDLED_OOPS
 385 
 386   // Macos/aarch64 should be in the right state for safepoint (e.g.
 387   // deoptimization needs WXWrite).  Crashes caused by the wrong state rarely
 388   // happens in practice, making such issues hard to find and reproduce.
 389 #if defined(__APPLE__) && defined(AARCH64)
 390   if (AssertWXAtThreadSync) {
 391     assert_wx_state(WXWrite);
 392   }
 393 #endif
 394 }
 395 
 396 void JavaThread::check_for_valid_safepoint_state() {
 397   // Don't complain if running a debugging command.
 398   if (DebuggingContext::is_enabled()) return;
 399 
 400   // Check NoSafepointVerifier, which is implied by locks taken that can be
 401   // shared with the VM thread.  This makes sure that no locks with allow_vm_block
 402   // are held.
 403   check_possible_safepoint();
 404 
 405   if (thread_state() != _thread_in_vm) {
 406     fatal("LEAF method calling lock?");
 407   }
 408 
 409   if (GCALotAtAllSafepoints) {
 410     // We could enter a safepoint here and thus have a gc
 411     InterfaceSupport::check_gc_alot();
 412   }
 413 }
 414 #endif // ASSERT
 415 
 416 // A JavaThread is a normal Java thread
 417 
 418 JavaThread::JavaThread() :
 419   // Initialize fields
 420 
 421   _on_thread_list(false),
 422   DEBUG_ONLY(_java_call_counter(0) COMMA)
 423   _entry_point(nullptr),
 424   _deopt_mark(nullptr),
 425   _deopt_nmethod(nullptr),
 426   _vframe_array_head(nullptr),
 427   _vframe_array_last(nullptr),
 428   _jvmti_deferred_updates(nullptr),
 429   _callee_target(nullptr),
 430   _vm_result(nullptr),
 431   _vm_result_2(nullptr),
 432 
 433   _current_pending_monitor(nullptr),
 434   _current_pending_monitor_is_from_java(true),
 435   _current_waiting_monitor(nullptr),
 436   _active_handles(nullptr),
 437   _free_handle_block(nullptr),
 438   _lock_id(0),
 439   _on_monitorenter(false),
 440 
 441   _monitor_chunks(nullptr),
 442 
 443   _suspend_flags(0),
 444 
 445   _thread_state(_thread_new),
 446   _saved_exception_pc(nullptr),
 447 #ifdef ASSERT
 448   _no_safepoint_count(0),
 449   _visited_for_critical_count(false),
 450 #endif
 451 
 452   _terminated(_not_terminated),
 453   _in_deopt_handler(0),
 454   _doing_unsafe_access(false),
 455   _do_not_unlock_if_synchronized(false),
 456 #if INCLUDE_JVMTI
 457   _carrier_thread_suspended(false),
 458   _is_in_VTMS_transition(false),
 459   _is_in_tmp_VTMS_transition(false),
 460   _is_disable_suspend(false),
 461 #ifdef ASSERT
 462   _is_VTMS_transition_disabler(false),
 463 #endif
 464 #endif
 465   _jni_attach_state(_not_attaching_via_jni),
 466 #if INCLUDE_JVMCI
 467   _pending_deoptimization(-1),
 468   _pending_monitorenter(false),
 469   _pending_transfer_to_interpreter(false),
 470   _in_retryable_allocation(false),
 471   _pending_failed_speculation(0),
 472   _jvmci{nullptr},
 473   _libjvmci_runtime(nullptr),
 474   _jvmci_counters(nullptr),
 475   _jvmci_reserved0(0),
 476   _jvmci_reserved1(0),
 477   _jvmci_reserved_oop0(nullptr),
 478   _live_nmethod(nullptr),
 479 #endif // INCLUDE_JVMCI
 480 
 481   _exception_oop(oop()),
 482   _exception_pc(0),
 483   _exception_handler_pc(0),
 484   _is_method_handle_return(0),
 485 
 486   _jni_active_critical(0),
 487   _pending_jni_exception_check_fn(nullptr),
 488   _depth_first_number(0),
 489 
 490   // JVMTI PopFrame support
 491   _popframe_condition(popframe_inactive),
 492   _frames_to_pop_failed_realloc(0),
 493 
 494   _cont_entry(nullptr),
 495   _cont_fastpath(0),
 496   _cont_fastpath_thread_state(1),
 497   _held_monitor_count(0),
 498   _jni_monitor_count(0),
 499   _preempting(false),
 500   _preemption_cancelled(false),
 501   _jvmti_unmount_event_pending(false),
 502   DEBUG_ONLY(_obj_locker_count(0) COMMA)
 503 
 504   _handshake(this),
 505 
 506   _popframe_preserved_args(nullptr),
 507   _popframe_preserved_args_size(0),
 508 
 509   _jvmti_thread_state(nullptr),
 510   _interp_only_mode(0),
 511   _should_post_on_exceptions_flag(JNI_FALSE),
 512   _thread_stat(new ThreadStatistics()),
 513 
 514   _parker(),
 515 
 516   _class_to_be_initialized(nullptr),
 517 
 518   _SleepEvent(ParkEvent::Allocate(this)),
 519 
 520   _lock_stack(this) {
 521   set_jni_functions(jni_functions());
 522 
 523 #if INCLUDE_JVMCI
 524   assert(_jvmci._implicit_exception_pc == nullptr, "must be");
 525   if (JVMCICounterSize > 0) {
 526     resize_counters(0, (int) JVMCICounterSize);
 527   }
 528 #endif // INCLUDE_JVMCI
 529 
 530   // Setup safepoint state info for this thread
 531   ThreadSafepointState::create(this);
 532 
 533   SafepointMechanism::initialize_header(this);
 534 
 535   set_requires_cross_modify_fence(false);
 536 
 537   pd_initialize();
 538   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
 539 }
 540 
 541 JavaThread::JavaThread(bool is_attaching_via_jni) : JavaThread() {
 542   if (is_attaching_via_jni) {
 543     _jni_attach_state = _attaching_via_jni;
 544   }
 545 }
 546 
 547 
 548 // interrupt support
 549 
 550 void JavaThread::interrupt() {
 551   // All callers should have 'this' thread protected by a
 552   // ThreadsListHandle so that it cannot terminate and deallocate
 553   // itself.
 554   debug_only(check_for_dangling_thread_pointer(this);)
 555 
 556   // For Windows _interrupt_event
 557   WINDOWS_ONLY(osthread()->set_interrupted(true);)
 558 
 559   // For Thread.sleep
 560   _SleepEvent->unpark();
 561 
 562   // For JSR166 LockSupport.park
 563   parker()->unpark();
 564 
 565   // For ObjectMonitor and JvmtiRawMonitor
 566   _ParkEvent->unpark();
 567 }
 568 
 569 bool JavaThread::is_interrupted(bool clear_interrupted) {
 570   debug_only(check_for_dangling_thread_pointer(this);)
 571 
 572   if (_threadObj.peek() == nullptr) {
 573     // If there is no j.l.Thread then it is impossible to have
 574     // been interrupted. We can find null during VM initialization
 575     // or when a JNI thread is still in the process of attaching.
 576     // In such cases this must be the current thread.
 577     assert(this == Thread::current(), "invariant");
 578     return false;
 579   }
 580 
 581   bool interrupted = java_lang_Thread::interrupted(threadObj());
 582 
 583   // NOTE that since there is no "lock" around the interrupt and
 584   // is_interrupted operations, there is the possibility that the
 585   // interrupted flag will be "false" but that the
 586   // low-level events will be in the signaled state. This is
 587   // intentional. The effect of this is that Object.wait() and
 588   // LockSupport.park() will appear to have a spurious wakeup, which
 589   // is allowed and not harmful, and the possibility is so rare that
 590   // it is not worth the added complexity to add yet another lock.
 591   // For the sleep event an explicit reset is performed on entry
 592   // to JavaThread::sleep, so there is no early return. It has also been
 593   // recommended not to put the interrupted flag into the "event"
 594   // structure because it hides the issue.
 595   // Also, because there is no lock, we must only clear the interrupt
 596   // state if we are going to report that we were interrupted; otherwise
 597   // an interrupt that happens just after we read the field would be lost.
 598   if (interrupted && clear_interrupted) {
 599     assert(this == Thread::current(), "only the current thread can clear");
 600     java_lang_Thread::set_interrupted(threadObj(), false);
 601     WINDOWS_ONLY(osthread()->set_interrupted(false);)
 602   }
 603   return interrupted;
 604 }
 605 
 606 // This is only for use by JVMTI RawMonitorWait. It emulates the actions of
 607 // the Java code in Object::wait which are not present in RawMonitorWait.
 608 bool JavaThread::get_and_clear_interrupted() {
 609   if (!is_interrupted(false)) {
 610     return false;
 611   }
 612   oop thread_oop = vthread_or_thread();
 613   bool is_virtual = java_lang_VirtualThread::is_instance(thread_oop);
 614 
 615   if (!is_virtual) {
 616     return is_interrupted(true);
 617   }
 618   // Virtual thread: clear interrupt status for both virtual and
 619   // carrier threads under the interruptLock protection.
 620   JavaThread* current = JavaThread::current();
 621   HandleMark hm(current);
 622   Handle thread_h(current, thread_oop);
 623   ObjectLocker lock(Handle(current, java_lang_Thread::interrupt_lock(thread_h())), current);
 624 
 625   // re-check the interrupt status under the interruptLock protection
 626   bool interrupted = java_lang_Thread::interrupted(thread_h());
 627 
 628   if (interrupted) {
 629     assert(this == Thread::current(), "only the current thread can clear");
 630     java_lang_Thread::set_interrupted(thread_h(), false);  // clear for virtual
 631     java_lang_Thread::set_interrupted(threadObj(), false); // clear for carrier
 632     WINDOWS_ONLY(osthread()->set_interrupted(false);)
 633   }
 634   return interrupted;
 635 }
 636 
 637 void JavaThread::block_if_vm_exited() {
 638   if (_terminated == _vm_exited) {
 639     // _vm_exited is set at safepoint, and Threads_lock is never released
 640     // so we will block here forever.
 641     // Here we can be doing a jump from a safe state to an unsafe state without
 642     // proper transition, but it happens after the final safepoint has begun so
 643     // this jump won't cause any safepoint problems.
 644     set_thread_state(_thread_in_vm);
 645     Threads_lock->lock();
 646     ShouldNotReachHere();
 647   }
 648 }
 649 
 650 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : JavaThread() {
 651   _jni_attach_state = _not_attaching_via_jni;
 652   set_entry_point(entry_point);
 653   // Create the native thread itself.
 654   // %note runtime_23
 655   os::ThreadType thr_type = os::java_thread;
 656   thr_type = entry_point == &CompilerThread::thread_entry ? os::compiler_thread :
 657                                                             os::java_thread;
 658   os::create_thread(this, thr_type, stack_sz);
 659   // The _osthread may be null here because we ran out of memory (too many threads active).
 660   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
 661   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
 662   // the exception consists of creating the exception object & initializing it, initialization
 663   // will leave the VM via a JavaCall and then all locks must be unlocked).
 664   //
 665   // The thread is still suspended when we reach here. Thread must be explicit started
 666   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
 667   // by calling Threads:add. The reason why this is not done here, is because the thread
 668   // object must be fully initialized (take a look at JVM_Start)
 669 }
 670 
 671 JavaThread::~JavaThread() {
 672 
 673   // Enqueue OopHandles for release by the service thread.
 674   add_oop_handles_for_release();
 675 
 676   // Return the sleep event to the free list
 677   ParkEvent::Release(_SleepEvent);
 678   _SleepEvent = nullptr;
 679 
 680   // Free any remaining  previous UnrollBlock
 681   vframeArray* old_array = vframe_array_last();
 682 
 683   if (old_array != nullptr) {
 684     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
 685     old_array->set_unroll_block(nullptr);
 686     delete old_info;
 687     delete old_array;
 688   }
 689 
 690   JvmtiDeferredUpdates* updates = deferred_updates();
 691   if (updates != nullptr) {
 692     // This can only happen if thread is destroyed before deoptimization occurs.
 693     assert(updates->count() > 0, "Updates holder not deleted");
 694     // free deferred updates.
 695     delete updates;
 696     set_deferred_updates(nullptr);
 697   }
 698 
 699   // All Java related clean up happens in exit
 700   ThreadSafepointState::destroy(this);
 701   if (_thread_stat != nullptr) delete _thread_stat;
 702 
 703 #if INCLUDE_JVMCI
 704   if (JVMCICounterSize > 0) {
 705     FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
 706   }
 707 #endif // INCLUDE_JVMCI
 708 }
 709 
 710 
 711 // First JavaThread specific code executed by a new Java thread.
 712 void JavaThread::pre_run() {
 713   // empty - see comments in run()
 714 }
 715 
 716 // The main routine called by a new Java thread. This isn't overridden
 717 // by subclasses, instead different subclasses define a different "entry_point"
 718 // which defines the actual logic for that kind of thread.
 719 void JavaThread::run() {
 720   // initialize thread-local alloc buffer related fields
 721   initialize_tlab();
 722 
 723   _stack_overflow_state.create_stack_guard_pages();
 724 
 725   cache_global_variables();
 726 
 727   // Thread is now sufficiently initialized to be handled by the safepoint code as being
 728   // in the VM. Change thread state from _thread_new to _thread_in_vm
 729   assert(this->thread_state() == _thread_new, "wrong thread state");
 730   set_thread_state(_thread_in_vm);
 731 
 732   // Before a thread is on the threads list it is always safe, so after leaving the
 733   // _thread_new we should emit a instruction barrier. The distance to modified code
 734   // from here is probably far enough, but this is consistent and safe.
 735   OrderAccess::cross_modify_fence();
 736 
 737   assert(JavaThread::current() == this, "sanity check");
 738   assert(!Thread::current()->owns_locks(), "sanity check");
 739 
 740   DTRACE_THREAD_PROBE(start, this);
 741 
 742   // This operation might block. We call that after all safepoint checks for a new thread has
 743   // been completed.
 744   set_active_handles(JNIHandleBlock::allocate_block());
 745 
 746   if (JvmtiExport::should_post_thread_life()) {
 747     JvmtiExport::post_thread_start(this);
 748 
 749   }
 750 
 751   if (AlwaysPreTouchStacks) {
 752     pretouch_stack();
 753   }
 754 
 755   // We call another function to do the rest so we are sure that the stack addresses used
 756   // from there will be lower than the stack base just computed.
 757   thread_main_inner();
 758 }
 759 
 760 void JavaThread::thread_main_inner() {
 761   assert(JavaThread::current() == this, "sanity check");
 762   assert(_threadObj.peek() != nullptr, "just checking");
 763 
 764   // Execute thread entry point unless this thread has a pending exception.
 765   // Note: Due to JVMTI StopThread we can have pending exceptions already!
 766   if (!this->has_pending_exception()) {
 767     {
 768       ResourceMark rm(this);
 769       this->set_native_thread_name(this->name());
 770     }
 771     HandleMark hm(this);
 772     this->entry_point()(this, this);
 773   }
 774 
 775   DTRACE_THREAD_PROBE(stop, this);
 776 
 777   // Cleanup is handled in post_run()
 778 }
 779 
 780 // Shared teardown for all JavaThreads
 781 void JavaThread::post_run() {
 782   this->exit(false);
 783   this->unregister_thread_stack_with_NMT();
 784   // Defer deletion to here to ensure 'this' is still referenceable in call_run
 785   // for any shared tear-down.
 786   this->smr_delete();
 787 }
 788 
 789 static void ensure_join(JavaThread* thread) {
 790   // We do not need to grab the Threads_lock, since we are operating on ourself.
 791   Handle threadObj(thread, thread->threadObj());
 792   assert(threadObj.not_null(), "java thread object must exist");
 793   ObjectLocker lock(threadObj, thread);
 794   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
 795   java_lang_Thread::set_thread_status(threadObj(), JavaThreadStatus::TERMINATED);
 796   // Clear the native thread instance - this makes isAlive return false and allows the join()
 797   // to complete once we've done the notify_all below. Needs a release() to obey Java Memory Model
 798   // requirements.
 799   assert(java_lang_Thread::thread(threadObj()) == thread, "must be alive");
 800   java_lang_Thread::release_set_thread(threadObj(), nullptr);
 801   lock.notify_all(thread);
 802   // Ignore pending exception, since we are exiting anyway
 803   thread->clear_pending_exception();
 804 }
 805 
 806 static bool is_daemon(oop threadObj) {
 807   return (threadObj != nullptr && java_lang_Thread::is_daemon(threadObj));
 808 }
 809 
 810 // For any new cleanup additions, please check to see if they need to be applied to
 811 // cleanup_failed_attach_current_thread as well.
 812 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
 813   assert(this == JavaThread::current(), "thread consistency check");
 814   assert(!is_exiting(), "should not be exiting or terminated already");
 815 
 816   elapsedTimer _timer_exit_phase1;
 817   elapsedTimer _timer_exit_phase2;
 818   elapsedTimer _timer_exit_phase3;
 819   elapsedTimer _timer_exit_phase4;
 820 
 821   if (log_is_enabled(Debug, os, thread, timer)) {
 822     _timer_exit_phase1.start();
 823   }
 824 
 825   HandleMark hm(this);
 826   Handle uncaught_exception(this, this->pending_exception());
 827   this->clear_pending_exception();
 828   Handle threadObj(this, this->threadObj());
 829   assert(threadObj.not_null(), "Java thread object should be created");
 830 
 831   if (!destroy_vm) {
 832     if (uncaught_exception.not_null()) {
 833       EXCEPTION_MARK;
 834       // Call method Thread.dispatchUncaughtException().
 835       Klass* thread_klass = vmClasses::Thread_klass();
 836       JavaValue result(T_VOID);
 837       JavaCalls::call_virtual(&result,
 838                               threadObj, thread_klass,
 839                               vmSymbols::dispatchUncaughtException_name(),
 840                               vmSymbols::throwable_void_signature(),
 841                               uncaught_exception,
 842                               THREAD);
 843       if (HAS_PENDING_EXCEPTION) {
 844         ResourceMark rm(this);
 845         jio_fprintf(defaultStream::error_stream(),
 846                     "\nException: %s thrown from the UncaughtExceptionHandler"
 847                     " in thread \"%s\"\n",
 848                     pending_exception()->klass()->external_name(),
 849                     name());
 850         CLEAR_PENDING_EXCEPTION;
 851       }
 852     }
 853 
 854     if (!is_Compiler_thread()) {
 855       // We have finished executing user-defined Java code and now have to do the
 856       // implementation specific clean-up by calling Thread.exit(). We prevent any
 857       // asynchronous exceptions from being delivered while in Thread.exit()
 858       // to ensure the clean-up is not corrupted.
 859       NoAsyncExceptionDeliveryMark _no_async(this);
 860 
 861       EXCEPTION_MARK;
 862       JavaValue result(T_VOID);
 863       Klass* thread_klass = vmClasses::Thread_klass();
 864       JavaCalls::call_virtual(&result,
 865                               threadObj, thread_klass,
 866                               vmSymbols::exit_method_name(),
 867                               vmSymbols::void_method_signature(),
 868                               THREAD);
 869       CLEAR_PENDING_EXCEPTION;
 870     }
 871 
 872     // notify JVMTI
 873     if (JvmtiExport::should_post_thread_life()) {
 874       JvmtiExport::post_thread_end(this);
 875     }
 876   } else {
 877     // before_exit() has already posted JVMTI THREAD_END events
 878   }
 879 
 880   // Cleanup any pending async exception now since we cannot access oops after
 881   // BarrierSet::barrier_set()->on_thread_detach() has been executed.
 882   if (has_async_exception_condition()) {
 883     handshake_state()->clean_async_exception_operation();
 884   }
 885 
 886   // The careful dance between thread suspension and exit is handled here.
 887   // Since we are in thread_in_vm state and suspension is done with handshakes,
 888   // we can just put in the exiting state and it will be correctly handled.
 889   // Also, no more async exceptions will be added to the queue after this point.
 890   set_terminated(_thread_exiting);
 891   ThreadService::current_thread_exiting(this, is_daemon(threadObj()));
 892 
 893   if (log_is_enabled(Debug, os, thread, timer)) {
 894     _timer_exit_phase1.stop();
 895     _timer_exit_phase2.start();
 896   }
 897 
 898   // Capture daemon status before the thread is marked as terminated.
 899   bool daemon = is_daemon(threadObj());
 900 
 901   // Notify waiters on thread object. This has to be done after exit() is called
 902   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
 903   // group should have the destroyed bit set before waiters are notified).
 904   ensure_join(this);
 905   assert(!this->has_pending_exception(), "ensure_join should have cleared");
 906 
 907   if (log_is_enabled(Debug, os, thread, timer)) {
 908     _timer_exit_phase2.stop();
 909     _timer_exit_phase3.start();
 910   }
 911   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
 912   // held by this thread must be released. The spec does not distinguish
 913   // between JNI-acquired and regular Java monitors. We can only see
 914   // regular Java monitors here if monitor enter-exit matching is broken.
 915   //
 916   // ensure_join() ignores IllegalThreadStateExceptions, and so does
 917   // ObjectSynchronizer::release_monitors_owned_by_thread().
 918   if (exit_type == jni_detach) {
 919     // Sanity check even though JNI DetachCurrentThread() would have
 920     // returned JNI_ERR if there was a Java frame. JavaThread exit
 921     // should be done executing Java code by the time we get here.
 922     assert(!this->has_last_Java_frame(),
 923            "should not have a Java frame when detaching or exiting");
 924     ObjectSynchronizer::release_monitors_owned_by_thread(this);
 925     assert(!this->has_pending_exception(), "release_monitors should have cleared");
 926     // Check for monitor counts being out of sync.
 927     assert(held_monitor_count() == jni_monitor_count(),
 928            "held monitor count should be equal to jni: " INTX_FORMAT " != " INTX_FORMAT,
 929            held_monitor_count(), jni_monitor_count());
 930     // All in-use monitors, including JNI-locked ones, should have been released above.
 931     assert(held_monitor_count() == 0, "Failed to unlock " INTX_FORMAT " object monitors",
 932            held_monitor_count());
 933   } else {
 934     // Check for monitor counts being out of sync.
 935     assert(held_monitor_count() == jni_monitor_count(),
 936            "held monitor count should be equal to jni: " INTX_FORMAT " != " INTX_FORMAT,
 937            held_monitor_count(), jni_monitor_count());
 938     // It is possible that a terminating thread failed to unlock monitors it locked
 939     // via JNI so we don't assert the count is zero.
 940   }
 941 
 942   if (CheckJNICalls && jni_monitor_count() > 0) {
 943     // We would like a fatal here, but due to we never checked this before there
 944     // is a lot of tests which breaks, even with an error log.
 945     log_debug(jni)("JavaThread %s (tid: " UINTX_FORMAT ") with Objects still locked by JNI MonitorEnter.",
 946                    exit_type == JavaThread::normal_exit ? "exiting" : "detaching", os::current_thread_id());
 947   }
 948   assert(obj_locker_count() == 0, "expected 0 but found: " INTX_FORMAT, obj_locker_count());
 949 
 950   // These things needs to be done while we are still a Java Thread. Make sure that thread
 951   // is in a consistent state, in case GC happens
 952   JFR_ONLY(Jfr::on_thread_exit(this);)
 953 
 954   if (active_handles() != nullptr) {
 955     JNIHandleBlock* block = active_handles();
 956     set_active_handles(nullptr);
 957     JNIHandleBlock::release_block(block);
 958   }
 959 
 960   if (free_handle_block() != nullptr) {
 961     JNIHandleBlock* block = free_handle_block();
 962     set_free_handle_block(nullptr);
 963     JNIHandleBlock::release_block(block);
 964   }
 965 
 966   // These have to be removed while this is still a valid thread.
 967   _stack_overflow_state.remove_stack_guard_pages();
 968 
 969   if (UseTLAB) {
 970     tlab().retire();
 971   }
 972 
 973   if (JvmtiEnv::environments_might_exist()) {
 974     JvmtiExport::cleanup_thread(this);
 975   }
 976 
 977   // We need to cache the thread name for logging purposes below as once
 978   // we have called on_thread_detach this thread must not access any oops.
 979   char* thread_name = nullptr;
 980   if (log_is_enabled(Debug, os, thread, timer)) {
 981     ResourceMark rm(this);
 982     thread_name = os::strdup(name());
 983   }
 984 
 985   if (log_is_enabled(Info, os, thread)) {
 986     ResourceMark rm(this);
 987     log_info(os, thread)("JavaThread %s (name: \"%s\", tid: " UINTX_FORMAT ").",
 988                          exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
 989                          name(), os::current_thread_id());
 990   }
 991 
 992   if (log_is_enabled(Debug, os, thread, timer)) {
 993     _timer_exit_phase3.stop();
 994     _timer_exit_phase4.start();
 995   }
 996 
 997 #if INCLUDE_JVMCI
 998   if (JVMCICounterSize > 0) {
 999     if (jvmci_counters_include(this)) {
1000       for (int i = 0; i < JVMCICounterSize; i++) {
1001         _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1002       }
1003     }
1004   }
1005 #endif // INCLUDE_JVMCI
1006 
1007   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread.
1008   // We call BarrierSet::barrier_set()->on_thread_detach() here so no touching of oops after this point.
1009   Threads::remove(this, daemon);
1010 
1011   if (log_is_enabled(Debug, os, thread, timer)) {
1012     _timer_exit_phase4.stop();
1013     log_debug(os, thread, timer)("name='%s'"
1014                                  ", exit-phase1=" JLONG_FORMAT
1015                                  ", exit-phase2=" JLONG_FORMAT
1016                                  ", exit-phase3=" JLONG_FORMAT
1017                                  ", exit-phase4=" JLONG_FORMAT,
1018                                  thread_name,
1019                                  _timer_exit_phase1.milliseconds(),
1020                                  _timer_exit_phase2.milliseconds(),
1021                                  _timer_exit_phase3.milliseconds(),
1022                                  _timer_exit_phase4.milliseconds());
1023     os::free(thread_name);
1024   }
1025 }
1026 
1027 void JavaThread::cleanup_failed_attach_current_thread(bool is_daemon) {
1028   if (active_handles() != nullptr) {
1029     JNIHandleBlock* block = active_handles();
1030     set_active_handles(nullptr);
1031     JNIHandleBlock::release_block(block);
1032   }
1033 
1034   if (free_handle_block() != nullptr) {
1035     JNIHandleBlock* block = free_handle_block();
1036     set_free_handle_block(nullptr);
1037     JNIHandleBlock::release_block(block);
1038   }
1039 
1040   // These have to be removed while this is still a valid thread.
1041   _stack_overflow_state.remove_stack_guard_pages();
1042 
1043   if (UseTLAB) {
1044     tlab().retire();
1045   }
1046 
1047   Threads::remove(this, is_daemon);
1048   this->smr_delete();
1049 }
1050 
1051 JavaThread* JavaThread::active() {
1052   Thread* thread = Thread::current();
1053   if (thread->is_Java_thread()) {
1054     return JavaThread::cast(thread);
1055   } else {
1056     assert(thread->is_VM_thread(), "this must be a vm thread");
1057     VM_Operation* op = ((VMThread*) thread)->vm_operation();
1058     JavaThread *ret = op == nullptr ? nullptr : JavaThread::cast(op->calling_thread());
1059     return ret;
1060   }
1061 }
1062 
1063 bool JavaThread::is_lock_owned(address adr) const {
1064   assert(LockingMode != LM_LIGHTWEIGHT, "should not be called with new lightweight locking");
1065   if (Thread::is_lock_owned(adr)) return true;
1066 
1067   for (MonitorChunk* chunk = monitor_chunks(); chunk != nullptr; chunk = chunk->next()) {
1068     if (chunk->contains(adr)) return true;
1069   }
1070 
1071   return false;
1072 }
1073 
1074 oop JavaThread::exception_oop() const {
1075   return Atomic::load(&_exception_oop);
1076 }
1077 
1078 void JavaThread::set_exception_oop(oop o) {
1079   Atomic::store(&_exception_oop, o);
1080 }
1081 
1082 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
1083   chunk->set_next(monitor_chunks());
1084   set_monitor_chunks(chunk);
1085 }
1086 
1087 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
1088   guarantee(monitor_chunks() != nullptr, "must be non empty");
1089   if (monitor_chunks() == chunk) {
1090     set_monitor_chunks(chunk->next());
1091   } else {
1092     MonitorChunk* prev = monitor_chunks();
1093     while (prev->next() != chunk) prev = prev->next();
1094     prev->set_next(chunk->next());
1095   }
1096 }
1097 
1098 void JavaThread::handle_special_runtime_exit_condition() {
1099   if (is_obj_deopt_suspend()) {
1100     frame_anchor()->make_walkable();
1101     wait_for_object_deoptimization();
1102   }
1103   JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
1104 }
1105 
1106 
1107 // Asynchronous exceptions support
1108 //
1109 void JavaThread::handle_async_exception(oop java_throwable) {
1110   assert(java_throwable != nullptr, "should have an _async_exception to throw");
1111   assert(!is_at_poll_safepoint(), "should have never called this method");
1112 
1113   if (has_last_Java_frame()) {
1114     frame f = last_frame();
1115     if (f.is_runtime_frame()) {
1116       // If the topmost frame is a runtime stub, then we are calling into
1117       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
1118       // must deoptimize the caller before continuing, as the compiled exception
1119       // handler table may not be valid.
1120       RegisterMap reg_map(this,
1121                           RegisterMap::UpdateMap::skip,
1122                           RegisterMap::ProcessFrames::include,
1123                           RegisterMap::WalkContinuation::skip);
1124       frame compiled_frame = f.sender(&reg_map);
1125       if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
1126         Deoptimization::deoptimize(this, compiled_frame);
1127       }
1128     }
1129   }
1130 
1131   // We cannot call Exceptions::_throw(...) here because we cannot block
1132   set_pending_exception(java_throwable, __FILE__, __LINE__);
1133 
1134   clear_scopedValueBindings();
1135 
1136   LogTarget(Info, exceptions) lt;
1137   if (lt.is_enabled()) {
1138     ResourceMark rm;
1139     LogStream ls(lt);
1140     ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
1141     if (has_last_Java_frame()) {
1142       frame f = last_frame();
1143       ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
1144     }
1145     ls.print_cr(" of type: %s", java_throwable->klass()->external_name());
1146   }
1147 }
1148 
1149 void JavaThread::install_async_exception(AsyncExceptionHandshake* aeh) {
1150   // Do not throw asynchronous exceptions against the compiler thread
1151   // or if the thread is already exiting.
1152   if (!can_call_java() || is_exiting()) {
1153     delete aeh;
1154     return;
1155   }
1156 
1157   oop exception = aeh->exception();
1158   Handshake::execute(aeh, this);  // Install asynchronous handshake
1159 
1160   ResourceMark rm;
1161   if (log_is_enabled(Info, exceptions)) {
1162     log_info(exceptions)("Pending Async. exception installed of type: %s",
1163                          InstanceKlass::cast(exception->klass())->external_name());
1164   }
1165   // for AbortVMOnException flag
1166   Exceptions::debug_check_abort(exception->klass()->external_name());
1167 
1168   oop vt_oop = vthread();
1169   if (vt_oop == nullptr || !vt_oop->is_a(vmClasses::BaseVirtualThread_klass())) {
1170     // Interrupt thread so it will wake up from a potential wait()/sleep()/park()
1171     java_lang_Thread::set_interrupted(threadObj(), true);
1172     this->interrupt();
1173   }
1174 }
1175 
1176 class InstallAsyncExceptionHandshake : public HandshakeClosure {
1177   AsyncExceptionHandshake* _aeh;
1178 public:
1179   InstallAsyncExceptionHandshake(AsyncExceptionHandshake* aeh) :
1180     HandshakeClosure("InstallAsyncException"), _aeh(aeh) {}
1181   ~InstallAsyncExceptionHandshake() {
1182     // If InstallAsyncExceptionHandshake was never executed we need to clean up _aeh.
1183     delete _aeh;
1184   }
1185   void do_thread(Thread* thr) {
1186     JavaThread* target = JavaThread::cast(thr);
1187     target->install_async_exception(_aeh);
1188     _aeh = nullptr;
1189   }
1190 };
1191 
1192 void JavaThread::send_async_exception(JavaThread* target, oop java_throwable) {
1193   OopHandle e(Universe::vm_global(), java_throwable);
1194   InstallAsyncExceptionHandshake iaeh(new AsyncExceptionHandshake(e));
1195   Handshake::execute(&iaeh, target);
1196 }
1197 
1198 #if INCLUDE_JVMTI
1199 void JavaThread::set_is_in_VTMS_transition(bool val) {
1200   assert(is_in_VTMS_transition() != val, "already %s transition", val ? "inside" : "outside");
1201   _is_in_VTMS_transition = val;
1202 }
1203 
1204 #ifdef ASSERT
1205 void JavaThread::set_is_VTMS_transition_disabler(bool val) {
1206   _is_VTMS_transition_disabler = val;
1207 }
1208 #endif
1209 #endif
1210 
1211 // External suspension mechanism.
1212 //
1213 // Guarantees on return (for a valid target thread):
1214 //   - Target thread will not execute any new bytecode.
1215 //   - Target thread will not enter any new monitors.
1216 //
1217 bool JavaThread::java_suspend() {
1218 #if INCLUDE_JVMTI
1219   // Suspending a JavaThread in VTMS transition or disabling VTMS transitions can cause deadlocks.
1220   assert(!is_in_VTMS_transition(), "no suspend allowed in VTMS transition");
1221   assert(!is_VTMS_transition_disabler(), "no suspend allowed for VTMS transition disablers");
1222 #endif
1223 
1224   guarantee(Thread::is_JavaThread_protected(/* target */ this),
1225             "target JavaThread is not protected in calling context.");
1226   return this->handshake_state()->suspend();
1227 }
1228 
1229 bool JavaThread::java_resume() {
1230   guarantee(Thread::is_JavaThread_protected_by_TLH(/* target */ this),
1231             "missing ThreadsListHandle in calling context.");
1232   return this->handshake_state()->resume();
1233 }
1234 
1235 // Wait for another thread to perform object reallocation and relocking on behalf of
1236 // this thread. The current thread is required to change to _thread_blocked in order
1237 // to be seen to be safepoint/handshake safe whilst suspended and only after becoming
1238 // handshake safe, the other thread can complete the handshake used to synchronize
1239 // with this thread and then perform the reallocation and relocking.
1240 // See EscapeBarrier::sync_and_suspend_*()
1241 
1242 void JavaThread::wait_for_object_deoptimization() {
1243   assert(!has_last_Java_frame() || frame_anchor()->walkable(), "should have walkable stack");
1244   assert(this == Thread::current(), "invariant");
1245 
1246   bool spin_wait = os::is_MP();
1247   do {
1248     ThreadBlockInVM tbivm(this, true /* allow_suspend */);
1249     // Wait for object deoptimization if requested.
1250     if (spin_wait) {
1251       // A single deoptimization is typically very short. Microbenchmarks
1252       // showed 5% better performance when spinning.
1253       const uint spin_limit = 10 * SpinYield::default_spin_limit;
1254       SpinYield spin(spin_limit);
1255       for (uint i = 0; is_obj_deopt_suspend() && i < spin_limit; i++) {
1256         spin.wait();
1257       }
1258       // Spin just once
1259       spin_wait = false;
1260     } else {
1261       MonitorLocker ml(this, EscapeBarrier_lock, Monitor::_no_safepoint_check_flag);
1262       if (is_obj_deopt_suspend()) {
1263         ml.wait();
1264       }
1265     }
1266     // A handshake for obj. deoptimization suspend could have been processed so
1267     // we must check after processing.
1268   } while (is_obj_deopt_suspend());
1269 }
1270 
1271 #ifdef ASSERT
1272 // Verify the JavaThread has not yet been published in the Threads::list, and
1273 // hence doesn't need protection from concurrent access at this stage.
1274 void JavaThread::verify_not_published() {
1275   // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
1276   // since an unpublished JavaThread doesn't participate in the
1277   // Thread-SMR protocol for keeping a ThreadsList alive.
1278   assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
1279 }
1280 #endif
1281 
1282 // Slow path when the native==>Java barriers detect a safepoint/handshake is
1283 // pending, when _suspend_flags is non-zero or when we need to process a stack
1284 // watermark. Also check for pending async exceptions (except unsafe access error).
1285 // Note only the native==>Java barriers can call this function when thread state
1286 // is _thread_in_native_trans.
1287 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
1288   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
1289   assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "Unwalkable stack in native->Java transition");
1290 
1291   thread->set_thread_state(_thread_in_vm);
1292 
1293   // Enable WXWrite: called directly from interpreter native wrapper.
1294   MACOS_AARCH64_ONLY(ThreadWXEnable wx(WXWrite, thread));
1295 
1296   SafepointMechanism::process_if_requested_with_exit_check(thread, true /* check asyncs */);
1297 
1298   // After returning from native, it could be that the stack frames are not
1299   // yet safe to use. We catch such situations in the subsequent stack watermark
1300   // barrier, which will trap unsafe stack frames.
1301   StackWatermarkSet::before_unwind(thread);
1302 }
1303 
1304 #ifndef PRODUCT
1305 // Deoptimization
1306 // Function for testing deoptimization
1307 void JavaThread::deoptimize() {
1308   StackFrameStream fst(this, false /* update */, true /* process_frames */);
1309   bool deopt = false;           // Dump stack only if a deopt actually happens.
1310   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
1311   // Iterate over all frames in the thread and deoptimize
1312   for (; !fst.is_done(); fst.next()) {
1313     if (fst.current()->can_be_deoptimized()) {
1314 
1315       if (only_at) {
1316         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
1317         // consists of comma or carriage return separated numbers so
1318         // search for the current bci in that string.
1319         address    pc = fst.current()->pc();
1320         nmethod*   nm = fst.current()->cb()->as_nmethod();
1321         ScopeDesc* sd = nm->scope_desc_at(pc);
1322         char buffer[8];
1323         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
1324         size_t len = strlen(buffer);
1325         const char * found = strstr(DeoptimizeOnlyAt, buffer);
1326         while (found != nullptr) {
1327           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
1328               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
1329             // Check that the bci found is bracketed by terminators.
1330             break;
1331           }
1332           found = strstr(found + 1, buffer);
1333         }
1334         if (!found) {
1335           continue;
1336         }
1337       }
1338 
1339       if (DebugDeoptimization && !deopt) {
1340         deopt = true; // One-time only print before deopt
1341         tty->print_cr("[BEFORE Deoptimization]");
1342         trace_frames();
1343         trace_stack();
1344       }
1345       Deoptimization::deoptimize(this, *fst.current());
1346     }
1347   }
1348 
1349   if (DebugDeoptimization && deopt) {
1350     tty->print_cr("[AFTER Deoptimization]");
1351     trace_frames();
1352   }
1353 }
1354 
1355 
1356 // Make zombies
1357 void JavaThread::make_zombies() {
1358   for (StackFrameStream fst(this, true /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
1359     if (fst.current()->can_be_deoptimized()) {
1360       // it is a Java nmethod
1361       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
1362       assert(nm != nullptr, "did not find nmethod");
1363       nm->make_not_entrant();
1364     }
1365   }
1366 }
1367 #endif // PRODUCT
1368 
1369 
1370 void JavaThread::deoptimize_marked_methods() {
1371   if (!has_last_Java_frame()) return;
1372   StackFrameStream fst(this, false /* update */, true /* process_frames */);
1373   for (; !fst.is_done(); fst.next()) {
1374     if (fst.current()->should_be_deoptimized()) {
1375       Deoptimization::deoptimize(this, *fst.current());
1376     }
1377   }
1378 }
1379 
1380 #ifdef ASSERT
1381 void JavaThread::verify_frame_info() {
1382   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
1383          (has_last_Java_frame() && java_call_counter() > 0),
1384          "unexpected frame info: has_last_frame=%s, java_call_counter=%d",
1385          has_last_Java_frame() ? "true" : "false", java_call_counter());
1386 }
1387 #endif
1388 
1389 // Push on a new block of JNI handles.
1390 void JavaThread::push_jni_handle_block() {
1391   // Allocate a new block for JNI handles.
1392   // Inlined code from jni_PushLocalFrame()
1393   JNIHandleBlock* old_handles = active_handles();
1394   JNIHandleBlock* new_handles = JNIHandleBlock::allocate_block(this);
1395   assert(old_handles != nullptr && new_handles != nullptr, "should not be null");
1396   new_handles->set_pop_frame_link(old_handles);  // make sure java handles get gc'd.
1397   set_active_handles(new_handles);
1398 }
1399 
1400 // Pop off the current block of JNI handles.
1401 void JavaThread::pop_jni_handle_block() {
1402   // Release our JNI handle block
1403   JNIHandleBlock* old_handles = active_handles();
1404   JNIHandleBlock* new_handles = old_handles->pop_frame_link();
1405   assert(new_handles != nullptr, "should never set active handles to null");
1406   set_active_handles(new_handles);
1407   old_handles->set_pop_frame_link(nullptr);
1408   JNIHandleBlock::release_block(old_handles, this);
1409 }
1410 
1411 void JavaThread::oops_do_no_frames(OopClosure* f, NMethodClosure* cf) {
1412   // Verify that the deferred card marks have been flushed.
1413   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
1414 
1415   // Traverse the GCHandles
1416   Thread::oops_do_no_frames(f, cf);
1417 
1418   if (active_handles() != nullptr) {
1419     active_handles()->oops_do(f);
1420   }
1421 
1422   DEBUG_ONLY(verify_frame_info();)
1423 
1424   if (has_last_Java_frame()) {
1425     // Traverse the monitor chunks
1426     for (MonitorChunk* chunk = monitor_chunks(); chunk != nullptr; chunk = chunk->next()) {
1427       chunk->oops_do(f);
1428     }
1429   }
1430 
1431   assert(vframe_array_head() == nullptr, "deopt in progress at a safepoint!");
1432   // If we have deferred set_locals there might be oops waiting to be
1433   // written
1434   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = JvmtiDeferredUpdates::deferred_locals(this);
1435   if (list != nullptr) {
1436     for (int i = 0; i < list->length(); i++) {
1437       list->at(i)->oops_do(f);
1438     }
1439   }
1440 
1441   // Traverse instance variables at the end since the GC may be moving things
1442   // around using this function
1443   f->do_oop((oop*) &_vm_result);
1444   f->do_oop((oop*) &_exception_oop);
1445 #if INCLUDE_JVMCI
1446   f->do_oop((oop*) &_jvmci_reserved_oop0);
1447 
1448   if (_live_nmethod != nullptr && cf != nullptr) {
1449     cf->do_nmethod(_live_nmethod);
1450   }
1451 #endif
1452 
1453   if (jvmti_thread_state() != nullptr) {
1454     jvmti_thread_state()->oops_do(f, cf);
1455   }
1456 
1457   // The continuation oops are really on the stack. But there is typically at most
1458   // one of those per thread, so we handle them here in the oops_do_no_frames part
1459   // so that we don't have to sprinkle as many stack watermark checks where these
1460   // oops are used. We just need to make sure the thread has started processing.
1461   ContinuationEntry* entry = _cont_entry;
1462   while (entry != nullptr) {
1463     f->do_oop((oop*)entry->cont_addr());
1464     f->do_oop((oop*)entry->chunk_addr());
1465     entry = entry->parent();
1466   }
1467 
1468   if (LockingMode == LM_LIGHTWEIGHT) {
1469     lock_stack().oops_do(f);
1470   }
1471 }
1472 
1473 void JavaThread::oops_do_frames(OopClosure* f, NMethodClosure* cf) {
1474   if (!has_last_Java_frame()) {
1475     return;
1476   }
1477   // Finish any pending lazy GC activity for the frames
1478   StackWatermarkSet::finish_processing(this, nullptr /* context */, StackWatermarkKind::gc);
1479   // Traverse the execution stack
1480   for (StackFrameStream fst(this, true /* update */, false /* process_frames */); !fst.is_done(); fst.next()) {
1481     fst.current()->oops_do(f, cf, fst.register_map());
1482   }
1483 }
1484 
1485 #ifdef ASSERT
1486 void JavaThread::verify_states_for_handshake() {
1487   // This checks that the thread has a correct frame state during a handshake.
1488   verify_frame_info();
1489 }
1490 #endif
1491 
1492 void JavaThread::nmethods_do(NMethodClosure* cf) {
1493   DEBUG_ONLY(verify_frame_info();)
1494   MACOS_AARCH64_ONLY(ThreadWXEnable wx(WXWrite, Thread::current());)
1495 
1496   if (has_last_Java_frame()) {
1497     // Traverse the execution stack
1498     for (StackFrameStream fst(this, true /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
1499       fst.current()->nmethod_do(cf);
1500     }
1501   }
1502 
1503   if (jvmti_thread_state() != nullptr) {
1504     jvmti_thread_state()->nmethods_do(cf);
1505   }
1506 
1507 #if INCLUDE_JVMCI
1508   if (_live_nmethod != nullptr) {
1509     cf->do_nmethod(_live_nmethod);
1510   }
1511 #endif
1512 }
1513 
1514 void JavaThread::metadata_do(MetadataClosure* f) {
1515   if (has_last_Java_frame()) {
1516     // Traverse the execution stack to call f() on the methods in the stack
1517     for (StackFrameStream fst(this, true /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
1518       fst.current()->metadata_do(f);
1519     }
1520   } else if (is_Compiler_thread()) {
1521     // need to walk ciMetadata in current compile tasks to keep alive.
1522     CompilerThread* ct = (CompilerThread*)this;
1523     if (ct->env() != nullptr) {
1524       ct->env()->metadata_do(f);
1525     }
1526     CompileTask* task = ct->task();
1527     if (task != nullptr) {
1528       task->metadata_do(f);
1529     }
1530   }
1531 }
1532 
1533 // Printing
1534 static const char* _get_thread_state_name(JavaThreadState _thread_state) {
1535   switch (_thread_state) {
1536   case _thread_uninitialized:     return "_thread_uninitialized";
1537   case _thread_new:               return "_thread_new";
1538   case _thread_new_trans:         return "_thread_new_trans";
1539   case _thread_in_native:         return "_thread_in_native";
1540   case _thread_in_native_trans:   return "_thread_in_native_trans";
1541   case _thread_in_vm:             return "_thread_in_vm";
1542   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
1543   case _thread_in_Java:           return "_thread_in_Java";
1544   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
1545   case _thread_blocked:           return "_thread_blocked";
1546   case _thread_blocked_trans:     return "_thread_blocked_trans";
1547   default:                        return "unknown thread state";
1548   }
1549 }
1550 
1551 void JavaThread::print_thread_state_on(outputStream *st) const {
1552   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
1553 }
1554 
1555 // Called by Threads::print() for VM_PrintThreads operation
1556 void JavaThread::print_on(outputStream *st, bool print_extended_info) const {
1557   st->print_raw("\"");
1558   st->print_raw(name());
1559   st->print_raw("\" ");
1560   oop thread_oop = threadObj();
1561   if (thread_oop != nullptr) {
1562     st->print("#" INT64_FORMAT " [%ld] ", (int64_t)java_lang_Thread::thread_id(thread_oop), (long) osthread()->thread_id());
1563     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
1564     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
1565   }
1566   Thread::print_on(st, print_extended_info);
1567   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
1568   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
1569   if (thread_oop != nullptr) {
1570     if (is_vthread_mounted()) {
1571       oop vt = vthread();
1572       assert(vt != nullptr, "");
1573       st->print_cr("   Carrying virtual thread #" INT64_FORMAT, (int64_t)java_lang_Thread::thread_id(vt));
1574     } else {
1575       st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
1576     }
1577   }
1578 #ifndef PRODUCT
1579   _safepoint_state->print_on(st);
1580 #endif // PRODUCT
1581   if (is_Compiler_thread()) {
1582     CompileTask *task = ((CompilerThread*)this)->task();
1583     if (task != nullptr) {
1584       st->print("   Compiling: ");
1585       task->print(st, nullptr, true, false);
1586     } else {
1587       st->print("   No compile task");
1588     }
1589     st->cr();
1590   }
1591 }
1592 
1593 void JavaThread::print() const { print_on(tty); }
1594 
1595 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
1596   st->print("%s", get_thread_name_string(buf, buflen));
1597 }
1598 
1599 // Called by fatal error handler. The difference between this and
1600 // JavaThread::print() is that we can't grab lock or allocate memory.
1601 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
1602   st->print("%s \"%s\"", type_name(), get_thread_name_string(buf, buflen));
1603   Thread* current = Thread::current_or_null_safe();
1604   assert(current != nullptr, "cannot be called by a detached thread");
1605   st->fill_to(60);
1606   if (!current->is_Java_thread() || JavaThread::cast(current)->is_oop_safe()) {
1607     // Only access threadObj() if current thread is not a JavaThread
1608     // or if it is a JavaThread that can safely access oops.
1609     oop thread_obj = threadObj();
1610     if (thread_obj != nullptr) {
1611       st->print(java_lang_Thread::is_daemon(thread_obj) ? " daemon" : "       ");
1612     }
1613   }
1614   st->print(" [");
1615   st->print("%s", _get_thread_state_name(_thread_state));
1616   if (osthread()) {
1617     st->print(", id=%d", osthread()->thread_id());
1618   }
1619   // Use raw field members for stack base/size as this could be
1620   // called before a thread has run enough to initialize them.
1621   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ") (" PROPERFMT ")",
1622             p2i(_stack_base - _stack_size), p2i(_stack_base),
1623             PROPERFMTARGS(_stack_size));
1624   st->print("]");
1625 
1626   ThreadsSMRSupport::print_info_on(this, st);
1627   return;
1628 }
1629 
1630 
1631 // Verification
1632 
1633 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
1634   // ignore if there is no stack
1635   if (!has_last_Java_frame()) return;
1636   // traverse the stack frames. Starts from top frame.
1637   for (StackFrameStream fst(this, true /* update_map */, true /* process_frames */, false /* walk_cont */); !fst.is_done(); fst.next()) {
1638     frame* fr = fst.current();
1639     f(fr, fst.register_map());
1640   }
1641 }
1642 
1643 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
1644 
1645 void JavaThread::verify() {
1646   // Verify oops in the thread.
1647   oops_do(&VerifyOopClosure::verify_oop, nullptr);
1648 
1649   // Verify the stack frames.
1650   frames_do(frame_verify);
1651 }
1652 
1653 // CR 6300358 (sub-CR 2137150)
1654 // Most callers of this method assume that it can't return null but a
1655 // thread may not have a name whilst it is in the process of attaching to
1656 // the VM - see CR 6412693, and there are places where a JavaThread can be
1657 // seen prior to having its threadObj set (e.g., JNI attaching threads and
1658 // if vm exit occurs during initialization). These cases can all be accounted
1659 // for such that this method never returns null.
1660 const char* JavaThread::name() const  {
1661   if (Thread::is_JavaThread_protected(/* target */ this)) {
1662     // The target JavaThread is protected so get_thread_name_string() is safe:
1663     return get_thread_name_string();
1664   }
1665 
1666   // The target JavaThread is not protected so we return the default:
1667   return Thread::name();
1668 }
1669 
1670 // Like name() but doesn't include the protection check. This must only be
1671 // called when it is known to be safe, even though the protection check can't tell
1672 // that e.g. when this thread is the init_thread() - see instanceKlass.cpp.
1673 const char* JavaThread::name_raw() const  {
1674   return get_thread_name_string();
1675 }
1676 
1677 // Returns a non-null representation of this thread's name, or a suitable
1678 // descriptive string if there is no set name.
1679 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
1680   const char* name_str;
1681 #ifdef ASSERT
1682   Thread* current = Thread::current_or_null_safe();
1683   assert(current != nullptr, "cannot be called by a detached thread");
1684   if (!current->is_Java_thread() || JavaThread::cast(current)->is_oop_safe()) {
1685     // Only access threadObj() if current thread is not a JavaThread
1686     // or if it is a JavaThread that can safely access oops.
1687 #endif
1688     oop thread_obj = threadObj();
1689     if (thread_obj != nullptr) {
1690       oop name = java_lang_Thread::name(thread_obj);
1691       if (name != nullptr) {
1692         if (buf == nullptr) {
1693           name_str = java_lang_String::as_utf8_string(name);
1694         } else {
1695           name_str = java_lang_String::as_utf8_string(name, buf, buflen);
1696         }
1697       } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
1698         name_str = "<no-name - thread is attaching>";
1699       } else {
1700         name_str = "<un-named>";
1701       }
1702     } else {
1703       name_str = Thread::name();
1704     }
1705 #ifdef ASSERT
1706   } else {
1707     // Current JavaThread has exited...
1708     if (current == this) {
1709       // ... and is asking about itself:
1710       name_str = "<no-name - current JavaThread has exited>";
1711     } else {
1712       // ... and it can't safely determine this JavaThread's name so
1713       // use the default thread name.
1714       name_str = Thread::name();
1715     }
1716   }
1717 #endif
1718   assert(name_str != nullptr, "unexpected null thread name");
1719   return name_str;
1720 }
1721 
1722 // Helper to extract the name from the thread oop for logging.
1723 const char* JavaThread::name_for(oop thread_obj) {
1724   assert(thread_obj != nullptr, "precondition");
1725   oop name = java_lang_Thread::name(thread_obj);
1726   const char* name_str;
1727   if (name != nullptr) {
1728     name_str = java_lang_String::as_utf8_string(name);
1729   } else {
1730     name_str = "<un-named>";
1731   }
1732   return name_str;
1733 }
1734 
1735 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
1736 
1737   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
1738   assert(NoPriority <= prio && prio <= MaxPriority, "sanity check");
1739   // Link Java Thread object <-> C++ Thread
1740 
1741   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
1742   // and put it into a new Handle.  The Handle "thread_oop" can then
1743   // be used to pass the C++ thread object to other methods.
1744 
1745   // Set the Java level thread object (jthread) field of the
1746   // new thread (a JavaThread *) to C++ thread object using the
1747   // "thread_oop" handle.
1748 
1749   // Set the thread field (a JavaThread *) of the
1750   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
1751 
1752   Handle thread_oop(Thread::current(),
1753                     JNIHandles::resolve_non_null(jni_thread));
1754   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
1755          "must be initialized");
1756   set_threadOopHandles(thread_oop());
1757   set_lock_id(java_lang_Thread::thread_id(thread_oop()));
1758 
1759   if (prio == NoPriority) {
1760     prio = java_lang_Thread::priority(thread_oop());
1761     assert(prio != NoPriority, "A valid priority should be present");
1762   }
1763 
1764   // Push the Java priority down to the native thread; needs Threads_lock
1765   Thread::set_priority(this, prio);
1766 
1767   // Add the new thread to the Threads list and set it in motion.
1768   // We must have threads lock in order to call Threads::add.
1769   // It is crucial that we do not block before the thread is
1770   // added to the Threads list for if a GC happens, then the java_thread oop
1771   // will not be visited by GC.
1772   Threads::add(this);
1773   // Publish the JavaThread* in java.lang.Thread after the JavaThread* is
1774   // on a ThreadsList. We don't want to wait for the release when the
1775   // Theads_lock is dropped somewhere in the caller since the JavaThread*
1776   // is already visible to JVM/TI via the ThreadsList.
1777   java_lang_Thread::release_set_thread(thread_oop(), this);
1778 }
1779 
1780 oop JavaThread::current_park_blocker() {
1781   // Support for JSR-166 locks
1782   oop thread_oop = threadObj();
1783   if (thread_oop != nullptr) {
1784     return java_lang_Thread::park_blocker(thread_oop);
1785   }
1786   return nullptr;
1787 }
1788 
1789 // Print current stack trace for checked JNI warnings and JNI fatal errors.
1790 // This is the external format, selecting the platform or vthread
1791 // as applicable, and allowing for a native-only stack.
1792 void JavaThread::print_jni_stack() {
1793   assert(this == JavaThread::current(), "Can't print stack of other threads");
1794   if (!has_last_Java_frame()) {
1795     ResourceMark rm(this);
1796     char* buf = NEW_RESOURCE_ARRAY_RETURN_NULL(char, O_BUFLEN);
1797     if (buf == nullptr) {
1798       tty->print_cr("Unable to print native stack - out of memory");
1799       return;
1800     }
1801     address lastpc = nullptr;
1802     if (os::platform_print_native_stack(tty, nullptr, buf, O_BUFLEN, lastpc)) {
1803       // We have printed the native stack in platform-specific code,
1804       // so nothing else to do in this case.
1805     } else {
1806       frame f = os::current_frame();
1807       VMError::print_native_stack(tty, f, this, true /*print_source_info */,
1808                                   -1 /* max stack */, buf, O_BUFLEN);
1809     }
1810   } else {
1811     print_active_stack_on(tty);
1812   }
1813 }
1814 
1815 void JavaThread::print_stack_on(outputStream* st) {
1816   if (!has_last_Java_frame()) return;
1817 
1818   Thread* current_thread = Thread::current();
1819   ResourceMark rm(current_thread);
1820   HandleMark hm(current_thread);
1821 
1822   RegisterMap reg_map(this,
1823                       RegisterMap::UpdateMap::include,
1824                       RegisterMap::ProcessFrames::include,
1825                       RegisterMap::WalkContinuation::skip);
1826   vframe* start_vf = platform_thread_last_java_vframe(&reg_map);
1827   int count = 0;
1828   for (vframe* f = start_vf; f != nullptr; f = f->sender()) {
1829     if (f->is_java_frame()) {
1830       javaVFrame* jvf = javaVFrame::cast(f);
1831       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
1832 
1833       // Print out lock information
1834       if (JavaMonitorsInStackTrace) {
1835         jvf->print_lock_info_on(st, count);
1836       }
1837     } else {
1838       // Ignore non-Java frames
1839     }
1840 
1841     // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
1842     count++;
1843     if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
1844   }
1845 }
1846 
1847 void JavaThread::print_vthread_stack_on(outputStream* st) {
1848   assert(is_vthread_mounted(), "Caller should have checked this");
1849   assert(has_last_Java_frame(), "must be");
1850 
1851   Thread* current_thread = Thread::current();
1852   ResourceMark rm(current_thread);
1853   HandleMark hm(current_thread);
1854 
1855   RegisterMap reg_map(this,
1856                       RegisterMap::UpdateMap::include,
1857                       RegisterMap::ProcessFrames::include,
1858                       RegisterMap::WalkContinuation::include);
1859   ContinuationEntry* cont_entry = last_continuation();
1860   vframe* start_vf = last_java_vframe(&reg_map);
1861   int count = 0;
1862   for (vframe* f = start_vf; f != nullptr; f = f->sender()) {
1863     // Watch for end of vthread stack
1864     if (Continuation::is_continuation_enterSpecial(f->fr())) {
1865       assert(cont_entry == Continuation::get_continuation_entry_for_entry_frame(this, f->fr()), "");
1866       if (cont_entry->is_virtual_thread()) {
1867         break;
1868       }
1869       cont_entry = cont_entry->parent();
1870     }
1871     if (f->is_java_frame()) {
1872       javaVFrame* jvf = javaVFrame::cast(f);
1873       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
1874 
1875       // Print out lock information
1876       if (JavaMonitorsInStackTrace) {
1877         jvf->print_lock_info_on(st, count);
1878       }
1879     } else {
1880       // Ignore non-Java frames
1881     }
1882 
1883     // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
1884     count++;
1885     if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
1886   }
1887 }
1888 
1889 void JavaThread::print_active_stack_on(outputStream* st) {
1890   if (is_vthread_mounted()) {
1891     print_vthread_stack_on(st);
1892   } else {
1893     print_stack_on(st);
1894   }
1895 }
1896 
1897 #if INCLUDE_JVMTI
1898 // Rebind JVMTI thread state from carrier to virtual or from virtual to carrier.
1899 JvmtiThreadState* JavaThread::rebind_to_jvmti_thread_state_of(oop thread_oop) {
1900   set_jvmti_vthread(thread_oop);
1901 
1902   // unbind current JvmtiThreadState from JavaThread
1903   JvmtiThreadState::unbind_from(jvmti_thread_state(), this);
1904 
1905   // bind new JvmtiThreadState to JavaThread
1906   JvmtiThreadState::bind_to(java_lang_Thread::jvmti_thread_state(thread_oop), this);
1907 
1908   return jvmti_thread_state();
1909 }
1910 #endif
1911 
1912 // JVMTI PopFrame support
1913 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
1914   assert(_popframe_preserved_args == nullptr, "should not wipe out old PopFrame preserved arguments");
1915   if (in_bytes(size_in_bytes) != 0) {
1916     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
1917     _popframe_preserved_args_size = in_bytes(size_in_bytes);
1918     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
1919   }
1920 }
1921 
1922 void* JavaThread::popframe_preserved_args() {
1923   return _popframe_preserved_args;
1924 }
1925 
1926 ByteSize JavaThread::popframe_preserved_args_size() {
1927   return in_ByteSize(_popframe_preserved_args_size);
1928 }
1929 
1930 WordSize JavaThread::popframe_preserved_args_size_in_words() {
1931   int sz = in_bytes(popframe_preserved_args_size());
1932   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
1933   return in_WordSize(sz / wordSize);
1934 }
1935 
1936 void JavaThread::popframe_free_preserved_args() {
1937   assert(_popframe_preserved_args != nullptr, "should not free PopFrame preserved arguments twice");
1938   FREE_C_HEAP_ARRAY(char, (char*)_popframe_preserved_args);
1939   _popframe_preserved_args = nullptr;
1940   _popframe_preserved_args_size = 0;
1941 }
1942 
1943 #ifndef PRODUCT
1944 
1945 void JavaThread::trace_frames() {
1946   tty->print_cr("[Describe stack]");
1947   int frame_no = 1;
1948   for (StackFrameStream fst(this, true /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
1949     tty->print("  %d. ", frame_no++);
1950     fst.current()->print_value_on(tty, this);
1951     tty->cr();
1952   }
1953 }
1954 
1955 class PrintAndVerifyOopClosure: public OopClosure {
1956  protected:
1957   template <class T> inline void do_oop_work(T* p) {
1958     oop obj = RawAccess<>::oop_load(p);
1959     if (obj == nullptr) return;
1960     tty->print(INTPTR_FORMAT ": ", p2i(p));
1961     if (oopDesc::is_oop_or_null(obj)) {
1962       if (obj->is_objArray()) {
1963         tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
1964       } else {
1965         obj->print();
1966       }
1967     } else {
1968       tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
1969     }
1970     tty->cr();
1971   }
1972  public:
1973   virtual void do_oop(oop* p) { do_oop_work(p); }
1974   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
1975 };
1976 
1977 #ifdef ASSERT
1978 // Print or validate the layout of stack frames
1979 void JavaThread::print_frame_layout(int depth, bool validate_only) {
1980   ResourceMark rm;
1981   PreserveExceptionMark pm(this);
1982   FrameValues values;
1983   int frame_no = 0;
1984   for (StackFrameStream fst(this, true, true, true); !fst.is_done(); fst.next()) {
1985     fst.current()->describe(values, ++frame_no, fst.register_map());
1986     if (depth == frame_no) break;
1987   }
1988   Continuation::describe(values);
1989   if (validate_only) {
1990     values.validate();
1991   } else {
1992     tty->print_cr("[Describe stack layout]");
1993     values.print(this);
1994   }
1995 }
1996 #endif
1997 
1998 void JavaThread::trace_stack_from(vframe* start_vf) {
1999   ResourceMark rm;
2000   int vframe_no = 1;
2001   for (vframe* f = start_vf; f; f = f->sender()) {
2002     if (f->is_java_frame()) {
2003       javaVFrame::cast(f)->print_activation(vframe_no++);
2004     } else {
2005       f->print();
2006     }
2007     if (vframe_no > StackPrintLimit) {
2008       tty->print_cr("...<more frames>...");
2009       return;
2010     }
2011   }
2012 }
2013 
2014 
2015 void JavaThread::trace_stack() {
2016   if (!has_last_Java_frame()) return;
2017   Thread* current_thread = Thread::current();
2018   ResourceMark rm(current_thread);
2019   HandleMark hm(current_thread);
2020   RegisterMap reg_map(this,
2021                       RegisterMap::UpdateMap::include,
2022                       RegisterMap::ProcessFrames::include,
2023                       RegisterMap::WalkContinuation::skip);
2024   trace_stack_from(last_java_vframe(&reg_map));
2025 }
2026 
2027 
2028 #endif // PRODUCT
2029 
2030 // Slow-path increment of the held monitor counts. JNI locking is always
2031 // this slow-path.
2032 void JavaThread::inc_held_monitor_count(intx i, bool jni) {
2033 #ifdef SUPPORT_MONITOR_COUNT
2034   assert(_held_monitor_count >= 0, "Must always be non-negative: " INTX_FORMAT, _held_monitor_count);
2035   _held_monitor_count += i;
2036   if (jni) {
2037     assert(_jni_monitor_count >= 0, "Must always be non-negative: " INTX_FORMAT, _jni_monitor_count);
2038     _jni_monitor_count += i;
2039   }
2040   assert(_held_monitor_count >= _jni_monitor_count, "Monitor count discrepancy detected - held count "
2041          INTX_FORMAT " is less than JNI count " INTX_FORMAT, _held_monitor_count, _jni_monitor_count);
2042 #endif
2043 }
2044 
2045 // Slow-path decrement of the held monitor counts. JNI unlocking is always
2046 // this slow-path.
2047 void JavaThread::dec_held_monitor_count(intx i, bool jni) {
2048 #ifdef SUPPORT_MONITOR_COUNT
2049   _held_monitor_count -= i;
2050   assert(_held_monitor_count >= 0, "Must always be non-negative: " INTX_FORMAT, _held_monitor_count);
2051   if (jni) {
2052     _jni_monitor_count -= i;
2053     assert(_jni_monitor_count >= 0, "Must always be non-negative: " INTX_FORMAT, _jni_monitor_count);
2054   }
2055   // When a thread is detaching with still owned JNI monitors, the logic that releases
2056   // the monitors doesn't know to set the "jni" flag and so the counts can get out of sync.
2057   // So we skip this assert if the thread is exiting. Once all monitors are unlocked the
2058   // JNI count is directly set to zero.
2059   assert(_held_monitor_count >= _jni_monitor_count || is_exiting(), "Monitor count discrepancy detected - held count "
2060          INTX_FORMAT " is less than JNI count " INTX_FORMAT, _held_monitor_count, _jni_monitor_count);
2061 #endif
2062 }
2063 
2064 frame JavaThread::vthread_last_frame() {
2065   assert (is_vthread_mounted(), "Virtual thread not mounted");
2066   return last_frame();
2067 }
2068 
2069 frame JavaThread::carrier_last_frame(RegisterMap* reg_map) {
2070   const ContinuationEntry* entry = vthread_continuation();
2071   guarantee (entry != nullptr, "Not a carrier thread");
2072   frame f = entry->to_frame();
2073   if (reg_map->process_frames()) {
2074     entry->flush_stack_processing(this);
2075   }
2076   entry->update_register_map(reg_map);
2077   return f.sender(reg_map);
2078 }
2079 
2080 frame JavaThread::platform_thread_last_frame(RegisterMap* reg_map) {
2081   return is_vthread_mounted() ? carrier_last_frame(reg_map) : last_frame();
2082 }
2083 
2084 javaVFrame* JavaThread::last_java_vframe(const frame f, RegisterMap *reg_map) {
2085   assert(reg_map != nullptr, "a map must be given");
2086   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
2087     if (vf->is_java_frame()) return javaVFrame::cast(vf);
2088   }
2089   return nullptr;
2090 }
2091 
2092 Klass* JavaThread::security_get_caller_class(int depth) {
2093   ResetNoHandleMark rnhm;
2094   HandleMark hm(Thread::current());
2095 
2096   vframeStream vfst(this);
2097   vfst.security_get_caller_frame(depth);
2098   if (!vfst.at_end()) {
2099     return vfst.method()->method_holder();
2100   }
2101   return nullptr;
2102 }
2103 
2104 // Internal convenience function for millisecond resolution sleeps.
2105 bool JavaThread::sleep(jlong millis) {
2106   jlong nanos;
2107   if (millis > max_jlong / NANOUNITS_PER_MILLIUNIT) {
2108     // Conversion to nanos would overflow, saturate at max
2109     nanos = max_jlong;
2110   } else {
2111     nanos = millis * NANOUNITS_PER_MILLIUNIT;
2112   }
2113   return sleep_nanos(nanos);
2114 }
2115 
2116 // java.lang.Thread.sleep support
2117 // Returns true if sleep time elapsed as expected, and false
2118 // if the thread was interrupted.
2119 bool JavaThread::sleep_nanos(jlong nanos) {
2120   assert(this == Thread::current(),  "thread consistency check");
2121   assert(nanos >= 0, "nanos are in range");
2122 
2123   ParkEvent * const slp = this->_SleepEvent;
2124   // Because there can be races with thread interruption sending an unpark()
2125   // to the event, we explicitly reset it here to avoid an immediate return.
2126   // The actual interrupt state will be checked before we park().
2127   slp->reset();
2128   // Thread interruption establishes a happens-before ordering in the
2129   // Java Memory Model, so we need to ensure we synchronize with the
2130   // interrupt state.
2131   OrderAccess::fence();
2132 
2133   jlong prevtime = os::javaTimeNanos();
2134 
2135   jlong nanos_remaining = nanos;
2136 
2137   for (;;) {
2138     // interruption has precedence over timing out
2139     if (this->is_interrupted(true)) {
2140       return false;
2141     }
2142 
2143     if (nanos_remaining <= 0) {
2144       return true;
2145     }
2146 
2147     {
2148       ThreadBlockInVM tbivm(this);
2149       OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
2150       slp->park_nanos(nanos_remaining);
2151     }
2152 
2153     // Update elapsed time tracking
2154     jlong newtime = os::javaTimeNanos();
2155     if (newtime - prevtime < 0) {
2156       // time moving backwards, should only happen if no monotonic clock
2157       // not a guarantee() because JVM should not abort on kernel/glibc bugs
2158       assert(false,
2159              "unexpected time moving backwards detected in JavaThread::sleep()");
2160     } else {
2161       nanos_remaining -= (newtime - prevtime);
2162     }
2163     prevtime = newtime;
2164   }
2165 }
2166 
2167 // Last thread running calls java.lang.Shutdown.shutdown()
2168 void JavaThread::invoke_shutdown_hooks() {
2169   HandleMark hm(this);
2170 
2171   // We could get here with a pending exception, if so clear it now.
2172   if (this->has_pending_exception()) {
2173     this->clear_pending_exception();
2174   }
2175 
2176   EXCEPTION_MARK;
2177   Klass* shutdown_klass =
2178     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
2179                                       THREAD);
2180   if (shutdown_klass != nullptr) {
2181     // SystemDictionary::resolve_or_null will return null if there was
2182     // an exception.  If we cannot load the Shutdown class, just don't
2183     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
2184     // won't be run.  Note that if a shutdown hook was registered,
2185     // the Shutdown class would have already been loaded
2186     // (Runtime.addShutdownHook will load it).
2187     JavaValue result(T_VOID);
2188     JavaCalls::call_static(&result,
2189                            shutdown_klass,
2190                            vmSymbols::shutdown_name(),
2191                            vmSymbols::void_method_signature(),
2192                            THREAD);
2193   }
2194   CLEAR_PENDING_EXCEPTION;
2195 }
2196 
2197 #ifndef PRODUCT
2198 void JavaThread::verify_cross_modify_fence_failure(JavaThread *thread) {
2199    report_vm_error(__FILE__, __LINE__, "Cross modify fence failure", "%p", thread);
2200 }
2201 #endif
2202 
2203 // Helper function to create the java.lang.Thread object for a
2204 // VM-internal thread. The thread will have the given name, and be
2205 // a member of the "system" ThreadGroup.
2206 Handle JavaThread::create_system_thread_object(const char* name, TRAPS) {
2207   Handle string = java_lang_String::create_from_str(name, CHECK_NH);
2208 
2209   // Initialize thread_oop to put it into the system threadGroup.
2210   // This is done by calling the Thread(ThreadGroup group, String name) constructor.
2211   Handle thread_group(THREAD, Universe::system_thread_group());
2212   Handle thread_oop =
2213     JavaCalls::construct_new_instance(vmClasses::Thread_klass(),
2214                                       vmSymbols::threadgroup_string_void_signature(),
2215                                       thread_group,
2216                                       string,
2217                                       CHECK_NH);
2218 
2219   return thread_oop;
2220 }
2221 
2222 // Starts the target JavaThread as a daemon of the given priority, and
2223 // bound to the given java.lang.Thread instance.
2224 // The Threads_lock is held for the duration.
2225 void JavaThread::start_internal_daemon(JavaThread* current, JavaThread* target,
2226                                        Handle thread_oop, ThreadPriority prio) {
2227 
2228   assert(target->osthread() != nullptr, "target thread is not properly initialized");
2229 
2230   MutexLocker mu(current, Threads_lock);
2231 
2232   // Initialize the fields of the thread_oop first.
2233   if (prio != NoPriority) {
2234     java_lang_Thread::set_priority(thread_oop(), prio);
2235     // Note: we don't call os::set_priority here. Possibly we should,
2236     // else all threads should call it themselves when they first run.
2237   }
2238 
2239   java_lang_Thread::set_daemon(thread_oop());
2240 
2241   // Now bind the thread_oop to the target JavaThread.
2242   target->set_threadOopHandles(thread_oop());
2243   target->set_lock_id(java_lang_Thread::thread_id(thread_oop()));
2244 
2245   Threads::add(target); // target is now visible for safepoint/handshake
2246   // Publish the JavaThread* in java.lang.Thread after the JavaThread* is
2247   // on a ThreadsList. We don't want to wait for the release when the
2248   // Theads_lock is dropped when the 'mu' destructor is run since the
2249   // JavaThread* is already visible to JVM/TI via the ThreadsList.
2250 
2251   assert(java_lang_Thread::thread(thread_oop()) == nullptr, "must not be alive");
2252   java_lang_Thread::release_set_thread(thread_oop(), target); // isAlive == true now
2253   Thread::start(target);
2254 }
2255 
2256 void JavaThread::vm_exit_on_osthread_failure(JavaThread* thread) {
2257   // At this point it may be possible that no osthread was created for the
2258   // JavaThread due to lack of resources. However, since this must work
2259   // for critical system threads just check and abort if this fails.
2260   if (thread->osthread() == nullptr) {
2261     // This isn't really an OOM condition, but historically this is what
2262     // we report.
2263     vm_exit_during_initialization("java.lang.OutOfMemoryError",
2264                                   os::native_thread_creation_failed_msg());
2265   }
2266 }
2267 
2268 void JavaThread::pretouch_stack() {
2269   // Given an established java thread stack with usable area followed by
2270   // shadow zone and reserved/yellow/red zone, pretouch the usable area ranging
2271   // from the current frame down to the start of the shadow zone.
2272   const address end = _stack_overflow_state.shadow_zone_safe_limit();
2273   if (is_in_full_stack(end)) {
2274     char* p1 = (char*) alloca(1);
2275     address here = (address) &p1;
2276     if (is_in_full_stack(here) && here > end) {
2277       size_t to_alloc = here - end;
2278       char* p2 = (char*) alloca(to_alloc);
2279       log_trace(os, thread)("Pretouching thread stack from " PTR_FORMAT " to " PTR_FORMAT ".",
2280                             p2i(p2), p2i(end));
2281       os::pretouch_memory(p2, p2 + to_alloc,
2282                           NOT_AIX(os::vm_page_size()) AIX_ONLY(4096));
2283     }
2284   }
2285 }
2286 
2287 // Deferred OopHandle release support.
2288 
2289 class OopHandleList : public CHeapObj<mtInternal> {
2290   static const int _count = 4;
2291   OopHandle _handles[_count];
2292   OopHandleList* _next;
2293   int _index;
2294  public:
2295   OopHandleList(OopHandleList* next) : _next(next), _index(0) {}
2296   void add(OopHandle h) {
2297     assert(_index < _count, "too many additions");
2298     _handles[_index++] = h;
2299   }
2300   ~OopHandleList() {
2301     assert(_index == _count, "usage error");
2302     for (int i = 0; i < _index; i++) {
2303       _handles[i].release(JavaThread::thread_oop_storage());
2304     }
2305   }
2306   OopHandleList* next() const { return _next; }
2307 };
2308 
2309 OopHandleList* JavaThread::_oop_handle_list = nullptr;
2310 
2311 // Called by the ServiceThread to do the work of releasing
2312 // the OopHandles.
2313 void JavaThread::release_oop_handles() {
2314   OopHandleList* list;
2315   {
2316     MutexLocker ml(Service_lock, Mutex::_no_safepoint_check_flag);
2317     list = _oop_handle_list;
2318     _oop_handle_list = nullptr;
2319   }
2320   assert(!SafepointSynchronize::is_at_safepoint(), "cannot be called at a safepoint");
2321 
2322   while (list != nullptr) {
2323     OopHandleList* l = list;
2324     list = l->next();
2325     delete l;
2326   }
2327 }
2328 
2329 // Add our OopHandles for later release.
2330 void JavaThread::add_oop_handles_for_release() {
2331   MutexLocker ml(Service_lock, Mutex::_no_safepoint_check_flag);
2332   OopHandleList* new_head = new OopHandleList(_oop_handle_list);
2333   new_head->add(_threadObj);
2334   new_head->add(_vthread);
2335   new_head->add(_jvmti_vthread);
2336   new_head->add(_scopedValueCache);
2337   _oop_handle_list = new_head;
2338   Service_lock->notify_all();
2339 }
--- EOF ---