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