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