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