1 /*
   2  * Copyright (c) 1997, 2022, Oracle and/or its affiliates. All rights reserved.
   3  * Copyright (c) 2021, Azul Systems, Inc. All rights reserved.
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This code is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 only, as
   8  * published by the Free Software Foundation.
   9  *
  10  * This code is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  13  * version 2 for more details (a copy is included in the LICENSE file that
  14  * accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License version
  17  * 2 along with this work; if not, write to the Free Software Foundation,
  18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  19  *
  20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  21  * or visit www.oracle.com if you need additional information or have any
  22  * questions.
  23  *
  24  */
  25 
  26 #include "precompiled.hpp"
  27 #include "jvm.h"
  28 #include "cds/dynamicArchive.hpp"
  29 #include "ci/ciEnv.hpp"
  30 #include "classfile/javaClasses.inline.hpp"
  31 #include "classfile/javaThreadStatus.hpp"
  32 #include "classfile/systemDictionary.hpp"
  33 #include "classfile/vmClasses.hpp"
  34 #include "classfile/vmSymbols.hpp"
  35 #include "code/codeCache.hpp"
  36 #include "code/scopeDesc.hpp"
  37 #include "compiler/compileTask.hpp"
  38 #include "compiler/compilerThread.hpp"
  39 #include "gc/shared/oopStorage.hpp"
  40 #include "gc/shared/oopStorageSet.hpp"
  41 #include "gc/shared/tlab_globals.hpp"
  42 #include "jfr/jfrEvents.hpp"
  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/mutexLocker.hpp"
  74 #include "runtime/orderAccess.hpp"
  75 #include "runtime/osThread.hpp"
  76 #include "runtime/safepoint.hpp"
  77 #include "runtime/safepointMechanism.inline.hpp"
  78 #include "runtime/safepointVerifiers.hpp"
  79 #include "runtime/serviceThread.hpp"
  80 #include "runtime/stackFrameStream.inline.hpp"
  81 #include "runtime/stackWatermarkSet.hpp"
  82 #include "runtime/synchronizer.hpp"
  83 #include "runtime/threadCritical.hpp"
  84 #include "runtime/threadSMR.inline.hpp"
  85 #include "runtime/threadStatisticalInfo.hpp"
  86 #include "runtime/threadWXSetters.inline.hpp"
  87 #include "runtime/timer.hpp"
  88 #include "runtime/timerTrace.hpp"
  89 #include "runtime/vframe.inline.hpp"
  90 #include "runtime/vframeArray.hpp"
  91 #include "runtime/vframe_hp.hpp"
  92 #include "runtime/vmThread.hpp"
  93 #include "runtime/vmOperations.hpp"
  94 #include "services/threadService.hpp"
  95 #include "utilities/copy.hpp"
  96 #include "utilities/defaultStream.hpp"
  97 #include "utilities/dtrace.hpp"
  98 #include "utilities/events.hpp"
  99 #include "utilities/macros.hpp"
 100 #include "utilities/preserveException.hpp"
 101 #include "utilities/spinYield.hpp"
 102 #if INCLUDE_JVMCI
 103 #include "jvmci/jvmci.hpp"
 104 #include "jvmci/jvmciEnv.hpp"
 105 #endif
 106 #if INCLUDE_JFR
 107 #include "jfr/jfr.hpp"
 108 #endif
 109 
 110 // Set by os layer.
 111 size_t      JavaThread::_stack_size_at_create = 0;
 112 
 113 #ifdef DTRACE_ENABLED
 114 
 115 // Only bother with this argument setup if dtrace is available
 116 
 117   #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
 118   #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
 119 
 120   #define DTRACE_THREAD_PROBE(probe, javathread)                           \
 121     {                                                                      \
 122       ResourceMark rm(this);                                               \
 123       int len = 0;                                                         \
 124       const char* name = (javathread)->name();                             \
 125       len = strlen(name);                                                  \
 126       HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */               \
 127         (char *) name, len,                                                \
 128         java_lang_Thread::thread_id((javathread)->threadObj()),            \
 129         (uintptr_t) (javathread)->osthread()->thread_id(),                 \
 130         java_lang_Thread::is_daemon((javathread)->threadObj()));           \
 131     }
 132 
 133 #else //  ndef DTRACE_ENABLED
 134 
 135   #define DTRACE_THREAD_PROBE(probe, javathread)
 136 
 137 #endif // ndef DTRACE_ENABLED
 138 
 139 void JavaThread::smr_delete() {
 140   if (_on_thread_list) {
 141     ThreadsSMRSupport::smr_delete(this);
 142   } else {
 143     delete this;
 144   }
 145 }
 146 
 147 // Initialized by VMThread at vm_global_init
 148 OopStorage* JavaThread::_thread_oop_storage = NULL;
 149 
 150 OopStorage* JavaThread::thread_oop_storage() {
 151   assert(_thread_oop_storage != NULL, "not yet initialized");
 152   return _thread_oop_storage;
 153 }
 154 
 155 void JavaThread::set_threadOopHandles(oop p) {
 156   assert(_thread_oop_storage != NULL, "not yet initialized");
 157   _threadObj   = OopHandle(_thread_oop_storage, p);
 158   _vthread     = OopHandle(_thread_oop_storage, p);
 159   _jvmti_vthread = OopHandle(_thread_oop_storage, NULL);
 160   _extentLocalCache = OopHandle(_thread_oop_storage, NULL);
 161 }
 162 
 163 oop JavaThread::threadObj() const {
 164   // Ideally we would verify the current thread is oop_safe when this is called, but as we can
 165   // be called from a signal handler we would have to use Thread::current_or_null_safe(). That
 166   // has overhead and also interacts poorly with GetLastError on Windows due to the use of TLS.
 167   // Instead callers must verify oop safe access.
 168   return _threadObj.resolve();
 169 }
 170 
 171 oop JavaThread::vthread() const {
 172   return _vthread.resolve();
 173 }
 174 
 175 void JavaThread::set_vthread(oop p) {
 176   assert(_thread_oop_storage != NULL, "not yet initialized");
 177   _vthread.replace(p);
 178 }
 179 
 180 oop JavaThread::jvmti_vthread() const {
 181   return _jvmti_vthread.resolve();
 182 }
 183 
 184 void JavaThread::set_jvmti_vthread(oop p) {
 185   assert(_thread_oop_storage != NULL, "not yet initialized");
 186   _jvmti_vthread.replace(p);
 187 }
 188 
 189 oop JavaThread::extentLocalCache() const {
 190   return _extentLocalCache.resolve();
 191 }
 192 
 193 void JavaThread::set_extentLocalCache(oop p) {
 194   assert(_thread_oop_storage != NULL, "not yet initialized");
 195   _extentLocalCache.replace(p);
 196 }
 197 
 198 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
 199                                     bool daemon, TRAPS) {
 200   assert(thread_group.not_null(), "thread group should be specified");
 201   assert(threadObj() == NULL, "should only create Java thread object once");
 202 
 203   InstanceKlass* ik = vmClasses::Thread_klass();
 204   assert(ik->is_initialized(), "must be");
 205   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
 206 
 207   // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon.
 208   // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread
 209   // constructor calls Thread.current(), which must be set here.
 210   java_lang_Thread::set_thread(thread_oop(), this);
 211   set_threadOopHandles(thread_oop());
 212 
 213   JavaValue result(T_VOID);
 214   if (thread_name != NULL) {
 215     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
 216     // Thread gets assigned specified name and null target
 217     JavaCalls::call_special(&result,
 218                             thread_oop,
 219                             ik,
 220                             vmSymbols::object_initializer_name(),
 221                             vmSymbols::threadgroup_string_void_signature(),
 222                             thread_group,
 223                             name,
 224                             THREAD);
 225   } else {
 226     // Thread gets assigned name "Thread-nnn" and null target
 227     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
 228     JavaCalls::call_special(&result,
 229                             thread_oop,
 230                             ik,
 231                             vmSymbols::object_initializer_name(),
 232                             vmSymbols::threadgroup_runnable_void_signature(),
 233                             thread_group,
 234                             Handle(),
 235                             THREAD);
 236   }
 237   os::set_priority(this, NormPriority);
 238 
 239   if (daemon) {
 240     java_lang_Thread::set_daemon(thread_oop());
 241   }
 242 }
 243 
 244 // ======= JavaThread ========
 245 
 246 #if INCLUDE_JVMCI
 247 
 248 jlong* JavaThread::_jvmci_old_thread_counters;
 249 
 250 bool jvmci_counters_include(JavaThread* thread) {
 251   return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
 252 }
 253 
 254 void JavaThread::collect_counters(jlong* array, int length) {
 255   assert(length == JVMCICounterSize, "wrong value");
 256   for (int i = 0; i < length; i++) {
 257     array[i] = _jvmci_old_thread_counters[i];
 258   }
 259   for (JavaThread* tp : ThreadsListHandle()) {
 260     if (jvmci_counters_include(tp)) {
 261       for (int i = 0; i < length; i++) {
 262         array[i] += tp->_jvmci_counters[i];
 263       }
 264     }
 265   }
 266 }
 267 
 268 // Attempt to enlarge the array for per thread counters.
 269 jlong* resize_counters_array(jlong* old_counters, int current_size, int new_size) {
 270   jlong* new_counters = NEW_C_HEAP_ARRAY_RETURN_NULL(jlong, new_size, mtJVMCI);
 271   if (new_counters == NULL) {
 272     return NULL;
 273   }
 274   if (old_counters == NULL) {
 275     old_counters = new_counters;
 276     memset(old_counters, 0, sizeof(jlong) * new_size);
 277   } else {
 278     for (int i = 0; i < MIN2((int) current_size, new_size); i++) {
 279       new_counters[i] = old_counters[i];
 280     }
 281     if (new_size > current_size) {
 282       memset(new_counters + current_size, 0, sizeof(jlong) * (new_size - current_size));
 283     }
 284     FREE_C_HEAP_ARRAY(jlong, old_counters);
 285   }
 286   return new_counters;
 287 }
 288 
 289 // Attempt to enlarge the array for per thread counters.
 290 bool JavaThread::resize_counters(int current_size, int new_size) {
 291   jlong* new_counters = resize_counters_array(_jvmci_counters, current_size, new_size);
 292   if (new_counters == NULL) {
 293     return false;
 294   } else {
 295     _jvmci_counters = new_counters;
 296     return true;
 297   }
 298 }
 299 
 300 class VM_JVMCIResizeCounters : public VM_Operation {
 301  private:
 302   int _new_size;
 303   bool _failed;
 304 
 305  public:
 306   VM_JVMCIResizeCounters(int new_size) : _new_size(new_size), _failed(false) { }
 307   VMOp_Type type()                  const        { return VMOp_JVMCIResizeCounters; }
 308   bool allow_nested_vm_operations() const        { return true; }
 309   void doit() {
 310     // Resize the old thread counters array
 311     jlong* new_counters = resize_counters_array(JavaThread::_jvmci_old_thread_counters, JVMCICounterSize, _new_size);
 312     if (new_counters == NULL) {
 313       _failed = true;
 314       return;
 315     } else {
 316       JavaThread::_jvmci_old_thread_counters = new_counters;
 317     }
 318 
 319     // Now resize each threads array
 320     for (JavaThread* tp : ThreadsListHandle()) {
 321       if (!tp->resize_counters(JVMCICounterSize, _new_size)) {
 322         _failed = true;
 323         break;
 324       }
 325     }
 326     if (!_failed) {
 327       JVMCICounterSize = _new_size;
 328     }
 329   }
 330 
 331   bool failed() { return _failed; }
 332 };
 333 
 334 bool JavaThread::resize_all_jvmci_counters(int new_size) {
 335   VM_JVMCIResizeCounters op(new_size);
 336   VMThread::execute(&op);
 337   return !op.failed();
 338 }
 339 
 340 #endif // INCLUDE_JVMCI
 341 
 342 #ifdef ASSERT
 343 // Checks safepoint allowed and clears unhandled oops at potential safepoints.
 344 void JavaThread::check_possible_safepoint() {
 345   if (_no_safepoint_count > 0) {
 346     print_owned_locks();
 347     assert(false, "Possible safepoint reached by thread that does not allow it");
 348   }
 349 #ifdef CHECK_UNHANDLED_OOPS
 350   // Clear unhandled oops in JavaThreads so we get a crash right away.
 351   clear_unhandled_oops();
 352 #endif // CHECK_UNHANDLED_OOPS
 353 
 354   // Macos/aarch64 should be in the right state for safepoint (e.g.
 355   // deoptimization needs WXWrite).  Crashes caused by the wrong state rarely
 356   // happens in practice, making such issues hard to find and reproduce.
 357 #if defined(__APPLE__) && defined(AARCH64)
 358   if (AssertWXAtThreadSync) {
 359     assert_wx_state(WXWrite);
 360   }
 361 #endif
 362 }
 363 
 364 void JavaThread::check_for_valid_safepoint_state() {
 365   // Check NoSafepointVerifier, which is implied by locks taken that can be
 366   // shared with the VM thread.  This makes sure that no locks with allow_vm_block
 367   // are held.
 368   check_possible_safepoint();
 369 
 370   if (thread_state() != _thread_in_vm) {
 371     fatal("LEAF method calling lock?");
 372   }
 373 
 374   if (GCALotAtAllSafepoints) {
 375     // We could enter a safepoint here and thus have a gc
 376     InterfaceSupport::check_gc_alot();
 377   }
 378 }
 379 #endif // ASSERT
 380 
 381 // A JavaThread is a normal Java thread
 382 
 383 JavaThread::JavaThread() :
 384   // Initialize fields
 385 
 386   _in_asgct(false),
 387   _on_thread_list(false),
 388   DEBUG_ONLY(_java_call_counter(0) COMMA)
 389   _entry_point(nullptr),
 390   _deopt_mark(nullptr),
 391   _deopt_nmethod(nullptr),
 392   _vframe_array_head(nullptr),
 393   _vframe_array_last(nullptr),
 394   _jvmti_deferred_updates(nullptr),
 395   _callee_target(nullptr),
 396   _vm_result(nullptr),
 397   _vm_result_2(nullptr),
 398 
 399   _current_pending_monitor(NULL),
 400   _current_pending_monitor_is_from_java(true),
 401   _current_waiting_monitor(NULL),
 402   _active_handles(NULL),
 403   _free_handle_block(NULL),
 404   _Stalled(0),
 405 
 406   _monitor_chunks(nullptr),
 407 
 408   _suspend_flags(0),
 409 
 410   _thread_state(_thread_new),
 411   _saved_exception_pc(nullptr),
 412 #ifdef ASSERT
 413   _no_safepoint_count(0),
 414   _visited_for_critical_count(false),
 415 #endif
 416 
 417   _terminated(_not_terminated),
 418   _in_deopt_handler(0),
 419   _doing_unsafe_access(false),
 420   _do_not_unlock_if_synchronized(false),
 421 #if INCLUDE_JVMTI
 422   _carrier_thread_suspended(false),
 423   _is_in_VTMS_transition(false),
 424   _is_in_tmp_VTMS_transition(false),
 425 #ifdef ASSERT
 426   _is_VTMS_transition_disabler(false),
 427 #endif
 428 #endif
 429   _jni_attach_state(_not_attaching_via_jni),
 430 #if INCLUDE_JVMCI
 431   _pending_deoptimization(-1),
 432   _pending_monitorenter(false),
 433   _pending_transfer_to_interpreter(false),
 434   _in_retryable_allocation(false),
 435   _pending_failed_speculation(0),
 436   _jvmci{nullptr},
 437   _libjvmci_runtime(nullptr),
 438   _jvmci_counters(nullptr),
 439   _jvmci_reserved0(0),
 440   _jvmci_reserved1(0),
 441   _jvmci_reserved_oop0(nullptr),
 442 #endif // INCLUDE_JVMCI
 443 
 444   _exception_oop(oop()),
 445   _exception_pc(0),
 446   _exception_handler_pc(0),
 447   _is_method_handle_return(0),
 448 
 449   _jni_active_critical(0),
 450   _pending_jni_exception_check_fn(nullptr),
 451   _depth_first_number(0),
 452 
 453   // JVMTI PopFrame support
 454   _popframe_condition(popframe_inactive),
 455   _frames_to_pop_failed_realloc(0),
 456 
 457   _cont_entry(nullptr),
 458   _cont_fastpath(0),
 459   _cont_fastpath_thread_state(1),
 460   _held_monitor_count(0),
 461   _jni_monitor_count(0),
 462 
 463   _handshake(this),
 464 
 465   _popframe_preserved_args(nullptr),
 466   _popframe_preserved_args_size(0),
 467 
 468   _jvmti_thread_state(nullptr),
 469   _interp_only_mode(0),
 470   _should_post_on_exceptions_flag(JNI_FALSE),
 471   _thread_stat(new ThreadStatistics()),
 472 
 473   _parker(),
 474 
 475   _class_to_be_initialized(nullptr),
 476 
 477   _SleepEvent(ParkEvent::Allocate(this))
 478 {
 479   set_jni_functions(jni_functions());
 480 
 481 #if INCLUDE_JVMCI
 482   assert(_jvmci._implicit_exception_pc == nullptr, "must be");
 483   if (JVMCICounterSize > 0) {
 484     resize_counters(0, (int) JVMCICounterSize);
 485   }
 486 #endif // INCLUDE_JVMCI
 487 
 488   // Setup safepoint state info for this thread
 489   ThreadSafepointState::create(this);
 490 
 491   SafepointMechanism::initialize_header(this);
 492 
 493   set_requires_cross_modify_fence(false);
 494 
 495   pd_initialize();
 496   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
 497 }
 498 
 499 JavaThread::JavaThread(bool is_attaching_via_jni) : JavaThread() {
 500   if (is_attaching_via_jni) {
 501     _jni_attach_state = _attaching_via_jni;
 502   }
 503 }
 504 
 505 
 506 // interrupt support
 507 
 508 void JavaThread::interrupt() {
 509   // All callers should have 'this' thread protected by a
 510   // ThreadsListHandle so that it cannot terminate and deallocate
 511   // itself.
 512   debug_only(check_for_dangling_thread_pointer(this);)
 513 
 514   // For Windows _interrupt_event
 515   WINDOWS_ONLY(osthread()->set_interrupted(true);)
 516 
 517   // For Thread.sleep
 518   _SleepEvent->unpark();
 519 
 520   // For JSR166 LockSupport.park
 521   parker()->unpark();
 522 
 523   // For ObjectMonitor and JvmtiRawMonitor
 524   _ParkEvent->unpark();
 525 }
 526 
 527 
 528 bool JavaThread::is_interrupted(bool clear_interrupted) {
 529   debug_only(check_for_dangling_thread_pointer(this);)
 530 
 531   if (_threadObj.peek() == NULL) {
 532     // If there is no j.l.Thread then it is impossible to have
 533     // been interrupted. We can find NULL during VM initialization
 534     // or when a JNI thread is still in the process of attaching.
 535     // In such cases this must be the current thread.
 536     assert(this == Thread::current(), "invariant");
 537     return false;
 538   }
 539 
 540   bool interrupted = java_lang_Thread::interrupted(threadObj());
 541 
 542   // NOTE that since there is no "lock" around the interrupt and
 543   // is_interrupted operations, there is the possibility that the
 544   // interrupted flag will be "false" but that the
 545   // low-level events will be in the signaled state. This is
 546   // intentional. The effect of this is that Object.wait() and
 547   // LockSupport.park() will appear to have a spurious wakeup, which
 548   // is allowed and not harmful, and the possibility is so rare that
 549   // it is not worth the added complexity to add yet another lock.
 550   // For the sleep event an explicit reset is performed on entry
 551   // to JavaThread::sleep, so there is no early return. It has also been
 552   // recommended not to put the interrupted flag into the "event"
 553   // structure because it hides the issue.
 554   // Also, because there is no lock, we must only clear the interrupt
 555   // state if we are going to report that we were interrupted; otherwise
 556   // an interrupt that happens just after we read the field would be lost.
 557   if (interrupted && clear_interrupted) {
 558     assert(this == Thread::current(), "only the current thread can clear");
 559     java_lang_Thread::set_interrupted(threadObj(), false);
 560     WINDOWS_ONLY(osthread()->set_interrupted(false);)
 561   }
 562 
 563   return interrupted;
 564 }
 565 
 566 void JavaThread::block_if_vm_exited() {
 567   if (_terminated == _vm_exited) {
 568     // _vm_exited is set at safepoint, and Threads_lock is never released
 569     // so we will block here forever.
 570     // Here we can be doing a jump from a safe state to an unsafe state without
 571     // proper transition, but it happens after the final safepoint has begun so
 572     // this jump won't cause any safepoint problems.
 573     set_thread_state(_thread_in_vm);
 574     Threads_lock->lock();
 575     ShouldNotReachHere();
 576   }
 577 }
 578 
 579 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : JavaThread() {
 580   _jni_attach_state = _not_attaching_via_jni;
 581   set_entry_point(entry_point);
 582   // Create the native thread itself.
 583   // %note runtime_23
 584   os::ThreadType thr_type = os::java_thread;
 585   thr_type = entry_point == &CompilerThread::thread_entry ? os::compiler_thread :
 586                                                             os::java_thread;
 587   os::create_thread(this, thr_type, stack_sz);
 588   // The _osthread may be NULL here because we ran out of memory (too many threads active).
 589   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
 590   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
 591   // the exception consists of creating the exception object & initializing it, initialization
 592   // will leave the VM via a JavaCall and then all locks must be unlocked).
 593   //
 594   // The thread is still suspended when we reach here. Thread must be explicit started
 595   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
 596   // by calling Threads:add. The reason why this is not done here, is because the thread
 597   // object must be fully initialized (take a look at JVM_Start)
 598 }
 599 
 600 JavaThread::~JavaThread() {
 601 
 602   // Ask ServiceThread to release the threadObj OopHandle
 603   ServiceThread::add_oop_handle_release(_threadObj);
 604   ServiceThread::add_oop_handle_release(_vthread);
 605   ServiceThread::add_oop_handle_release(_jvmti_vthread);
 606 
 607   // Return the sleep event to the free list
 608   ParkEvent::Release(_SleepEvent);
 609   _SleepEvent = NULL;
 610 
 611   // Free any remaining  previous UnrollBlock
 612   vframeArray* old_array = vframe_array_last();
 613 
 614   if (old_array != NULL) {
 615     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
 616     old_array->set_unroll_block(NULL);
 617     delete old_info;
 618     delete old_array;
 619   }
 620 
 621   JvmtiDeferredUpdates* updates = deferred_updates();
 622   if (updates != NULL) {
 623     // This can only happen if thread is destroyed before deoptimization occurs.
 624     assert(updates->count() > 0, "Updates holder not deleted");
 625     // free deferred updates.
 626     delete updates;
 627     set_deferred_updates(NULL);
 628   }
 629 
 630   // All Java related clean up happens in exit
 631   ThreadSafepointState::destroy(this);
 632   if (_thread_stat != NULL) delete _thread_stat;
 633 
 634 #if INCLUDE_JVMCI
 635   if (JVMCICounterSize > 0) {
 636     FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
 637   }
 638 #endif // INCLUDE_JVMCI
 639 }
 640 
 641 
 642 // First JavaThread specific code executed by a new Java thread.
 643 void JavaThread::pre_run() {
 644   // empty - see comments in run()
 645 }
 646 
 647 // The main routine called by a new Java thread. This isn't overridden
 648 // by subclasses, instead different subclasses define a different "entry_point"
 649 // which defines the actual logic for that kind of thread.
 650 void JavaThread::run() {
 651   // initialize thread-local alloc buffer related fields
 652   initialize_tlab();
 653 
 654   _stack_overflow_state.create_stack_guard_pages();
 655 
 656   cache_global_variables();
 657 
 658   // Thread is now sufficiently initialized to be handled by the safepoint code as being
 659   // in the VM. Change thread state from _thread_new to _thread_in_vm
 660   assert(this->thread_state() == _thread_new, "wrong thread state");
 661   set_thread_state(_thread_in_vm);
 662 
 663   // Before a thread is on the threads list it is always safe, so after leaving the
 664   // _thread_new we should emit a instruction barrier. The distance to modified code
 665   // from here is probably far enough, but this is consistent and safe.
 666   OrderAccess::cross_modify_fence();
 667 
 668   assert(JavaThread::current() == this, "sanity check");
 669   assert(!Thread::current()->owns_locks(), "sanity check");
 670 
 671   DTRACE_THREAD_PROBE(start, this);
 672 
 673   // This operation might block. We call that after all safepoint checks for a new thread has
 674   // been completed.
 675   set_active_handles(JNIHandleBlock::allocate_block());
 676 
 677   if (JvmtiExport::should_post_thread_life()) {
 678     JvmtiExport::post_thread_start(this);
 679 
 680   }
 681 
 682   // We call another function to do the rest so we are sure that the stack addresses used
 683   // from there will be lower than the stack base just computed.
 684   thread_main_inner();
 685 }
 686 
 687 void JavaThread::thread_main_inner() {
 688   assert(JavaThread::current() == this, "sanity check");
 689   assert(_threadObj.peek() != NULL, "just checking");
 690 
 691   // Execute thread entry point unless this thread has a pending exception.
 692   // Note: Due to JVMTI StopThread we can have pending exceptions already!
 693   if (!this->has_pending_exception()) {
 694     {
 695       ResourceMark rm(this);
 696       this->set_native_thread_name(this->name());
 697     }
 698     HandleMark hm(this);
 699     this->entry_point()(this, this);
 700   }
 701 
 702   DTRACE_THREAD_PROBE(stop, this);
 703 
 704   // Cleanup is handled in post_run()
 705 }
 706 
 707 // Shared teardown for all JavaThreads
 708 void JavaThread::post_run() {
 709   this->exit(false);
 710   this->unregister_thread_stack_with_NMT();
 711   // Defer deletion to here to ensure 'this' is still referenceable in call_run
 712   // for any shared tear-down.
 713   this->smr_delete();
 714 }
 715 
 716 static void ensure_join(JavaThread* thread) {
 717   // We do not need to grab the Threads_lock, since we are operating on ourself.
 718   Handle threadObj(thread, thread->threadObj());
 719   assert(threadObj.not_null(), "java thread object must exist");
 720   ObjectLocker lock(threadObj, thread);
 721   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
 722   java_lang_Thread::set_thread_status(threadObj(), JavaThreadStatus::TERMINATED);
 723   // Clear the native thread instance - this makes isAlive return false and allows the join()
 724   // to complete once we've done the notify_all below
 725   java_lang_Thread::set_thread(threadObj(), NULL);
 726   lock.notify_all(thread);
 727   // Ignore pending exception, since we are exiting anyway
 728   thread->clear_pending_exception();
 729 }
 730 
 731 static bool is_daemon(oop threadObj) {
 732   return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj));
 733 }
 734 
 735 // For any new cleanup additions, please check to see if they need to be applied to
 736 // cleanup_failed_attach_current_thread as well.
 737 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
 738   assert(this == JavaThread::current(), "thread consistency check");
 739   assert(!is_exiting(), "should not be exiting or terminated already");
 740 
 741   elapsedTimer _timer_exit_phase1;
 742   elapsedTimer _timer_exit_phase2;
 743   elapsedTimer _timer_exit_phase3;
 744   elapsedTimer _timer_exit_phase4;
 745 
 746   if (log_is_enabled(Debug, os, thread, timer)) {
 747     _timer_exit_phase1.start();
 748   }
 749 
 750   HandleMark hm(this);
 751   Handle uncaught_exception(this, this->pending_exception());
 752   this->clear_pending_exception();
 753   Handle threadObj(this, this->threadObj());
 754   assert(threadObj.not_null(), "Java thread object should be created");
 755 
 756   if (!destroy_vm) {
 757     if (uncaught_exception.not_null()) {
 758       EXCEPTION_MARK;
 759       // Call method Thread.dispatchUncaughtException().
 760       Klass* thread_klass = vmClasses::Thread_klass();
 761       JavaValue result(T_VOID);
 762       JavaCalls::call_virtual(&result,
 763                               threadObj, thread_klass,
 764                               vmSymbols::dispatchUncaughtException_name(),
 765                               vmSymbols::throwable_void_signature(),
 766                               uncaught_exception,
 767                               THREAD);
 768       if (HAS_PENDING_EXCEPTION) {
 769         ResourceMark rm(this);
 770         jio_fprintf(defaultStream::error_stream(),
 771                     "\nException: %s thrown from the UncaughtExceptionHandler"
 772                     " in thread \"%s\"\n",
 773                     pending_exception()->klass()->external_name(),
 774                     name());
 775         CLEAR_PENDING_EXCEPTION;
 776       }
 777     }
 778 
 779     if (!is_Compiler_thread()) {
 780       // We have finished executing user-defined Java code and now have to do the
 781       // implementation specific clean-up by calling Thread.exit(). We prevent any
 782       // asynchronous exceptions from being delivered while in Thread.exit()
 783       // to ensure the clean-up is not corrupted.
 784       NoAsyncExceptionDeliveryMark _no_async(this);
 785 
 786       EXCEPTION_MARK;
 787       JavaValue result(T_VOID);
 788       Klass* thread_klass = vmClasses::Thread_klass();
 789       JavaCalls::call_virtual(&result,
 790                               threadObj, thread_klass,
 791                               vmSymbols::exit_method_name(),
 792                               vmSymbols::void_method_signature(),
 793                               THREAD);
 794       CLEAR_PENDING_EXCEPTION;
 795     }
 796 
 797     // notify JVMTI
 798     if (JvmtiExport::should_post_thread_life()) {
 799       JvmtiExport::post_thread_end(this);
 800     }
 801   } else {
 802     // before_exit() has already posted JVMTI THREAD_END events
 803   }
 804 
 805   // Cleanup any pending async exception now since we cannot access oops after
 806   // BarrierSet::barrier_set()->on_thread_detach() has been executed.
 807   if (has_async_exception_condition()) {
 808     handshake_state()->clean_async_exception_operation();
 809   }
 810 
 811   // The careful dance between thread suspension and exit is handled here.
 812   // Since we are in thread_in_vm state and suspension is done with handshakes,
 813   // we can just put in the exiting state and it will be correctly handled.
 814   // Also, no more async exceptions will be added to the queue after this point.
 815   set_terminated(_thread_exiting);
 816   ThreadService::current_thread_exiting(this, is_daemon(threadObj()));
 817 
 818   if (log_is_enabled(Debug, os, thread, timer)) {
 819     _timer_exit_phase1.stop();
 820     _timer_exit_phase2.start();
 821   }
 822 
 823   // Capture daemon status before the thread is marked as terminated.
 824   bool daemon = is_daemon(threadObj());
 825 
 826   // Notify waiters on thread object. This has to be done after exit() is called
 827   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
 828   // group should have the destroyed bit set before waiters are notified).
 829   ensure_join(this);
 830   assert(!this->has_pending_exception(), "ensure_join should have cleared");
 831 
 832   if (log_is_enabled(Debug, os, thread, timer)) {
 833     _timer_exit_phase2.stop();
 834     _timer_exit_phase3.start();
 835   }
 836   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
 837   // held by this thread must be released. The spec does not distinguish
 838   // between JNI-acquired and regular Java monitors. We can only see
 839   // regular Java monitors here if monitor enter-exit matching is broken.
 840   //
 841   // ensure_join() ignores IllegalThreadStateExceptions, and so does
 842   // ObjectSynchronizer::release_monitors_owned_by_thread().
 843   if (exit_type == jni_detach) {
 844     // Sanity check even though JNI DetachCurrentThread() would have
 845     // returned JNI_ERR if there was a Java frame. JavaThread exit
 846     // should be done executing Java code by the time we get here.
 847     assert(!this->has_last_Java_frame(),
 848            "should not have a Java frame when detaching or exiting");
 849     ObjectSynchronizer::release_monitors_owned_by_thread(this);
 850     assert(!this->has_pending_exception(), "release_monitors should have cleared");
 851   }
 852 
 853   // Since above code may not release JNI monitors and if someone forgot to do an
 854   // JNI monitorexit, held count should be equal jni count.
 855   // Consider scan all object monitor for this owner if JNI count > 0 (at least on detach).
 856   assert(this->held_monitor_count() == this->jni_monitor_count(),
 857          "held monitor count should be equal to jni: " INT64_FORMAT " != " INT64_FORMAT,
 858          (int64_t)this->held_monitor_count(), (int64_t)this->jni_monitor_count());
 859   if (CheckJNICalls && this->jni_monitor_count() > 0) {
 860     // We would like a fatal here, but due to we never checked this before there
 861     // is a lot of tests which breaks, even with an error log.
 862     log_debug(jni)("JavaThread %s (tid: " UINTX_FORMAT ") with Objects still locked by JNI MonitorEnter.",
 863       exit_type == JavaThread::normal_exit ? "exiting" : "detaching", os::current_thread_id());
 864   }
 865 
 866   // These things needs to be done while we are still a Java Thread. Make sure that thread
 867   // is in a consistent state, in case GC happens
 868   JFR_ONLY(Jfr::on_thread_exit(this);)
 869 
 870   if (active_handles() != NULL) {
 871     JNIHandleBlock* block = active_handles();
 872     set_active_handles(NULL);
 873     JNIHandleBlock::release_block(block);
 874   }
 875 
 876   if (free_handle_block() != NULL) {
 877     JNIHandleBlock* block = free_handle_block();
 878     set_free_handle_block(NULL);
 879     JNIHandleBlock::release_block(block);
 880   }
 881 
 882   // These have to be removed while this is still a valid thread.
 883   _stack_overflow_state.remove_stack_guard_pages();
 884 
 885   if (UseTLAB) {
 886     tlab().retire();
 887   }
 888 
 889   if (JvmtiEnv::environments_might_exist()) {
 890     JvmtiExport::cleanup_thread(this);
 891   }
 892 
 893   // We need to cache the thread name for logging purposes below as once
 894   // we have called on_thread_detach this thread must not access any oops.
 895   char* thread_name = NULL;
 896   if (log_is_enabled(Debug, os, thread, timer)) {
 897     ResourceMark rm(this);
 898     thread_name = os::strdup(name());
 899   }
 900 
 901   log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
 902     exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
 903     os::current_thread_id());
 904 
 905   if (log_is_enabled(Debug, os, thread, timer)) {
 906     _timer_exit_phase3.stop();
 907     _timer_exit_phase4.start();
 908   }
 909 
 910 #if INCLUDE_JVMCI
 911   if (JVMCICounterSize > 0) {
 912     if (jvmci_counters_include(this)) {
 913       for (int i = 0; i < JVMCICounterSize; i++) {
 914         _jvmci_old_thread_counters[i] += _jvmci_counters[i];
 915       }
 916     }
 917   }
 918 #endif // INCLUDE_JVMCI
 919 
 920   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread.
 921   // We call BarrierSet::barrier_set()->on_thread_detach() here so no touching of oops after this point.
 922   Threads::remove(this, daemon);
 923 
 924   if (log_is_enabled(Debug, os, thread, timer)) {
 925     _timer_exit_phase4.stop();
 926     log_debug(os, thread, timer)("name='%s'"
 927                                  ", exit-phase1=" JLONG_FORMAT
 928                                  ", exit-phase2=" JLONG_FORMAT
 929                                  ", exit-phase3=" JLONG_FORMAT
 930                                  ", exit-phase4=" JLONG_FORMAT,
 931                                  thread_name,
 932                                  _timer_exit_phase1.milliseconds(),
 933                                  _timer_exit_phase2.milliseconds(),
 934                                  _timer_exit_phase3.milliseconds(),
 935                                  _timer_exit_phase4.milliseconds());
 936     os::free(thread_name);
 937   }
 938 }
 939 
 940 void JavaThread::cleanup_failed_attach_current_thread(bool is_daemon) {
 941   if (active_handles() != NULL) {
 942     JNIHandleBlock* block = active_handles();
 943     set_active_handles(NULL);
 944     JNIHandleBlock::release_block(block);
 945   }
 946 
 947   if (free_handle_block() != NULL) {
 948     JNIHandleBlock* block = free_handle_block();
 949     set_free_handle_block(NULL);
 950     JNIHandleBlock::release_block(block);
 951   }
 952 
 953   // These have to be removed while this is still a valid thread.
 954   _stack_overflow_state.remove_stack_guard_pages();
 955 
 956   if (UseTLAB) {
 957     tlab().retire();
 958   }
 959 
 960   Threads::remove(this, is_daemon);
 961   this->smr_delete();
 962 }
 963 
 964 JavaThread* JavaThread::active() {
 965   Thread* thread = Thread::current();
 966   if (thread->is_Java_thread()) {
 967     return JavaThread::cast(thread);
 968   } else {
 969     assert(thread->is_VM_thread(), "this must be a vm thread");
 970     VM_Operation* op = ((VMThread*) thread)->vm_operation();
 971     JavaThread *ret = op == NULL ? NULL : JavaThread::cast(op->calling_thread());
 972     return ret;
 973   }
 974 }
 975 
 976 oop JavaThread::exception_oop() const {
 977   return Atomic::load(&_exception_oop);
 978 }
 979 
 980 void JavaThread::set_exception_oop(oop o) {
 981   Atomic::store(&_exception_oop, o);
 982 }
 983 
 984 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
 985   chunk->set_next(monitor_chunks());
 986   set_monitor_chunks(chunk);
 987 }
 988 
 989 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
 990   guarantee(monitor_chunks() != NULL, "must be non empty");
 991   if (monitor_chunks() == chunk) {
 992     set_monitor_chunks(chunk->next());
 993   } else {
 994     MonitorChunk* prev = monitor_chunks();
 995     while (prev->next() != chunk) prev = prev->next();
 996     prev->set_next(chunk->next());
 997   }
 998 }
 999 
1000 void JavaThread::handle_special_runtime_exit_condition() {
1001   if (is_obj_deopt_suspend()) {
1002     frame_anchor()->make_walkable();
1003     wait_for_object_deoptimization();
1004   }
1005   JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
1006 }
1007 
1008 
1009 // Asynchronous exceptions support
1010 //
1011 void JavaThread::handle_async_exception(oop java_throwable) {
1012   assert(java_throwable != NULL, "should have an _async_exception to throw");
1013   assert(!is_at_poll_safepoint(), "should have never called this method");
1014 
1015   if (has_last_Java_frame()) {
1016     frame f = last_frame();
1017     if (f.is_runtime_frame()) {
1018       // If the topmost frame is a runtime stub, then we are calling into
1019       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
1020       // must deoptimize the caller before continuing, as the compiled exception
1021       // handler table may not be valid.
1022       RegisterMap reg_map(this,
1023                           RegisterMap::UpdateMap::skip,
1024                           RegisterMap::ProcessFrames::include,
1025                           RegisterMap::WalkContinuation::skip);
1026       frame compiled_frame = f.sender(&reg_map);
1027       if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
1028         Deoptimization::deoptimize(this, compiled_frame);
1029       }
1030     }
1031   }
1032 
1033   // We cannot call Exceptions::_throw(...) here because we cannot block
1034   set_pending_exception(java_throwable, __FILE__, __LINE__);
1035 
1036   // Clear any extent-local bindings
1037   set_extentLocalCache(NULL);
1038   oop threadOop = threadObj();
1039   assert(threadOop != NULL, "must be");
1040   java_lang_Thread::clear_extentLocalBindings(threadOop);
1041 
1042   LogTarget(Info, exceptions) lt;
1043   if (lt.is_enabled()) {
1044     ResourceMark rm;
1045     LogStream ls(lt);
1046     ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
1047     if (has_last_Java_frame()) {
1048       frame f = last_frame();
1049       ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
1050     }
1051     ls.print_cr(" of type: %s", java_throwable->klass()->external_name());
1052   }
1053 }
1054 
1055 void JavaThread::install_async_exception(AsyncExceptionHandshake* aeh) {
1056   // Do not throw asynchronous exceptions against the compiler thread
1057   // or if the thread is already exiting.
1058   if (!can_call_java() || is_exiting()) {
1059     delete aeh;
1060     return;
1061   }
1062 
1063   oop exception = aeh->exception();
1064   Handshake::execute(aeh, this);  // Install asynchronous handshake
1065 
1066   ResourceMark rm;
1067   if (log_is_enabled(Info, exceptions)) {
1068     log_info(exceptions)("Pending Async. exception installed of type: %s",
1069                          InstanceKlass::cast(exception->klass())->external_name());
1070   }
1071   // for AbortVMOnException flag
1072   Exceptions::debug_check_abort(exception->klass()->external_name());
1073 
1074   // Interrupt thread so it will wake up from a potential wait()/sleep()/park()
1075   java_lang_Thread::set_interrupted(threadObj(), true);
1076   this->interrupt();
1077 }
1078 
1079 class InstallAsyncExceptionHandshake : public HandshakeClosure {
1080   AsyncExceptionHandshake* _aeh;
1081 public:
1082   InstallAsyncExceptionHandshake(AsyncExceptionHandshake* aeh) :
1083     HandshakeClosure("InstallAsyncException"), _aeh(aeh) {}
1084   ~InstallAsyncExceptionHandshake() {
1085     // If InstallAsyncExceptionHandshake was never executed we need to clean up _aeh.
1086     delete _aeh;
1087   }
1088   void do_thread(Thread* thr) {
1089     JavaThread* target = JavaThread::cast(thr);
1090     target->install_async_exception(_aeh);
1091     _aeh = nullptr;
1092   }
1093 };
1094 
1095 void JavaThread::send_async_exception(JavaThread* target, oop java_throwable) {
1096   OopHandle e(Universe::vm_global(), java_throwable);
1097   InstallAsyncExceptionHandshake iaeh(new AsyncExceptionHandshake(e));
1098   Handshake::execute(&iaeh, target);
1099 }
1100 
1101 #if INCLUDE_JVMTI
1102 void JavaThread::set_is_in_VTMS_transition(bool val) {
1103   _is_in_VTMS_transition = val;
1104 }
1105 
1106 #ifdef ASSERT
1107 void JavaThread::set_is_VTMS_transition_disabler(bool val) {
1108   _is_VTMS_transition_disabler = val;
1109 }
1110 #endif
1111 #endif
1112 
1113 // External suspension mechanism.
1114 //
1115 // Guarantees on return (for a valid target thread):
1116 //   - Target thread will not execute any new bytecode.
1117 //   - Target thread will not enter any new monitors.
1118 //
1119 bool JavaThread::java_suspend() {
1120 #if INCLUDE_JVMTI
1121   // Suspending a JavaThread in VTMS transition or disabling VTMS transitions can cause deadlocks.
1122   assert(!is_in_VTMS_transition(), "no suspend allowed in VTMS transition");
1123   assert(!is_VTMS_transition_disabler(), "no suspend allowed for VTMS transition disablers");
1124 #endif
1125 
1126   guarantee(Thread::is_JavaThread_protected(/* target */ this),
1127             "target JavaThread is not protected in calling context.");
1128   return this->handshake_state()->suspend();
1129 }
1130 
1131 bool JavaThread::java_resume() {
1132   guarantee(Thread::is_JavaThread_protected_by_TLH(/* target */ this),
1133             "missing ThreadsListHandle in calling context.");
1134   return this->handshake_state()->resume();
1135 }
1136 
1137 // Wait for another thread to perform object reallocation and relocking on behalf of
1138 // this thread. The current thread is required to change to _thread_blocked in order
1139 // to be seen to be safepoint/handshake safe whilst suspended and only after becoming
1140 // handshake safe, the other thread can complete the handshake used to synchronize
1141 // with this thread and then perform the reallocation and relocking.
1142 // See EscapeBarrier::sync_and_suspend_*()
1143 
1144 void JavaThread::wait_for_object_deoptimization() {
1145   assert(!has_last_Java_frame() || frame_anchor()->walkable(), "should have walkable stack");
1146   assert(this == Thread::current(), "invariant");
1147 
1148   bool spin_wait = os::is_MP();
1149   do {
1150     ThreadBlockInVM tbivm(this, true /* allow_suspend */);
1151     // Wait for object deoptimization if requested.
1152     if (spin_wait) {
1153       // A single deoptimization is typically very short. Microbenchmarks
1154       // showed 5% better performance when spinning.
1155       const uint spin_limit = 10 * SpinYield::default_spin_limit;
1156       SpinYield spin(spin_limit);
1157       for (uint i = 0; is_obj_deopt_suspend() && i < spin_limit; i++) {
1158         spin.wait();
1159       }
1160       // Spin just once
1161       spin_wait = false;
1162     } else {
1163       MonitorLocker ml(this, EscapeBarrier_lock, Monitor::_no_safepoint_check_flag);
1164       if (is_obj_deopt_suspend()) {
1165         ml.wait();
1166       }
1167     }
1168     // A handshake for obj. deoptimization suspend could have been processed so
1169     // we must check after processing.
1170   } while (is_obj_deopt_suspend());
1171 }
1172 
1173 #ifdef ASSERT
1174 // Verify the JavaThread has not yet been published in the Threads::list, and
1175 // hence doesn't need protection from concurrent access at this stage.
1176 void JavaThread::verify_not_published() {
1177   // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
1178   // since an unpublished JavaThread doesn't participate in the
1179   // Thread-SMR protocol for keeping a ThreadsList alive.
1180   assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
1181 }
1182 #endif
1183 
1184 // Slow path when the native==>Java barriers detect a safepoint/handshake is
1185 // pending, when _suspend_flags is non-zero or when we need to process a stack
1186 // watermark. Also check for pending async exceptions (except unsafe access error).
1187 // Note only the native==>Java barriers can call this function when thread state
1188 // is _thread_in_native_trans.
1189 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
1190   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
1191   assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "Unwalkable stack in native->Java transition");
1192 
1193   thread->set_thread_state(_thread_in_vm);
1194 
1195   // Enable WXWrite: called directly from interpreter native wrapper.
1196   MACOS_AARCH64_ONLY(ThreadWXEnable wx(WXWrite, thread));
1197 
1198   SafepointMechanism::process_if_requested_with_exit_check(thread, true /* check asyncs */);
1199 
1200   // After returning from native, it could be that the stack frames are not
1201   // yet safe to use. We catch such situations in the subsequent stack watermark
1202   // barrier, which will trap unsafe stack frames.
1203   StackWatermarkSet::before_unwind(thread);
1204 }
1205 
1206 #ifndef PRODUCT
1207 // Deoptimization
1208 // Function for testing deoptimization
1209 void JavaThread::deoptimize() {
1210   StackFrameStream fst(this, false /* update */, true /* process_frames */);
1211   bool deopt = false;           // Dump stack only if a deopt actually happens.
1212   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
1213   // Iterate over all frames in the thread and deoptimize
1214   for (; !fst.is_done(); fst.next()) {
1215     if (fst.current()->can_be_deoptimized()) {
1216 
1217       if (only_at) {
1218         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
1219         // consists of comma or carriage return separated numbers so
1220         // search for the current bci in that string.
1221         address pc = fst.current()->pc();
1222         nmethod* nm =  (nmethod*) fst.current()->cb();
1223         ScopeDesc* sd = nm->scope_desc_at(pc);
1224         char buffer[8];
1225         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
1226         size_t len = strlen(buffer);
1227         const char * found = strstr(DeoptimizeOnlyAt, buffer);
1228         while (found != NULL) {
1229           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
1230               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
1231             // Check that the bci found is bracketed by terminators.
1232             break;
1233           }
1234           found = strstr(found + 1, buffer);
1235         }
1236         if (!found) {
1237           continue;
1238         }
1239       }
1240 
1241       if (DebugDeoptimization && !deopt) {
1242         deopt = true; // One-time only print before deopt
1243         tty->print_cr("[BEFORE Deoptimization]");
1244         trace_frames();
1245         trace_stack();
1246       }
1247       Deoptimization::deoptimize(this, *fst.current());
1248     }
1249   }
1250 
1251   if (DebugDeoptimization && deopt) {
1252     tty->print_cr("[AFTER Deoptimization]");
1253     trace_frames();
1254   }
1255 }
1256 
1257 
1258 // Make zombies
1259 void JavaThread::make_zombies() {
1260   for (StackFrameStream fst(this, true /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
1261     if (fst.current()->can_be_deoptimized()) {
1262       // it is a Java nmethod
1263       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
1264       nm->make_not_entrant();
1265     }
1266   }
1267 }
1268 #endif // PRODUCT
1269 
1270 
1271 void JavaThread::deoptimize_marked_methods() {
1272   if (!has_last_Java_frame()) return;
1273   StackFrameStream fst(this, false /* update */, true /* process_frames */);
1274   for (; !fst.is_done(); fst.next()) {
1275     if (fst.current()->should_be_deoptimized()) {
1276       Deoptimization::deoptimize(this, *fst.current());
1277     }
1278   }
1279 }
1280 
1281 #ifdef ASSERT
1282 void JavaThread::verify_frame_info() {
1283   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
1284          (has_last_Java_frame() && java_call_counter() > 0),
1285          "unexpected frame info: has_last_frame=%s, java_call_counter=%d",
1286          has_last_Java_frame() ? "true" : "false", java_call_counter());
1287 }
1288 #endif
1289 
1290 // Push on a new block of JNI handles.
1291 void JavaThread::push_jni_handle_block() {
1292   // Allocate a new block for JNI handles.
1293   // Inlined code from jni_PushLocalFrame()
1294   JNIHandleBlock* old_handles = active_handles();
1295   JNIHandleBlock* new_handles = JNIHandleBlock::allocate_block(this);
1296   assert(old_handles != NULL && new_handles != NULL, "should not be NULL");
1297   new_handles->set_pop_frame_link(old_handles);  // make sure java handles get gc'd.
1298   set_active_handles(new_handles);
1299 }
1300 
1301 // Pop off the current block of JNI handles.
1302 void JavaThread::pop_jni_handle_block() {
1303   // Release our JNI handle block
1304   JNIHandleBlock* old_handles = active_handles();
1305   JNIHandleBlock* new_handles = old_handles->pop_frame_link();
1306   assert(new_handles != nullptr, "should never set active handles to null");
1307   set_active_handles(new_handles);
1308   old_handles->set_pop_frame_link(NULL);
1309   JNIHandleBlock::release_block(old_handles, this);
1310 }
1311 
1312 void JavaThread::oops_do_no_frames(OopClosure* f, CodeBlobClosure* cf) {
1313   // Verify that the deferred card marks have been flushed.
1314   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
1315 
1316   // Traverse the GCHandles
1317   Thread::oops_do_no_frames(f, cf);
1318 
1319   if (active_handles() != NULL) {
1320     active_handles()->oops_do(f);
1321   }
1322 
1323   DEBUG_ONLY(verify_frame_info();)
1324 
1325   if (has_last_Java_frame()) {
1326     // Traverse the monitor chunks
1327     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
1328       chunk->oops_do(f);
1329     }
1330   }
1331 
1332   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
1333   // If we have deferred set_locals there might be oops waiting to be
1334   // written
1335   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = JvmtiDeferredUpdates::deferred_locals(this);
1336   if (list != NULL) {
1337     for (int i = 0; i < list->length(); i++) {
1338       list->at(i)->oops_do(f);
1339     }
1340   }
1341 
1342   // Traverse instance variables at the end since the GC may be moving things
1343   // around using this function
1344   f->do_oop((oop*) &_vm_result);
1345   f->do_oop((oop*) &_exception_oop);
1346 #if INCLUDE_JVMCI
1347   f->do_oop((oop*) &_jvmci_reserved_oop0);
1348 #endif
1349 
1350   if (jvmti_thread_state() != NULL) {
1351     jvmti_thread_state()->oops_do(f, cf);
1352   }
1353 }
1354 
1355 void JavaThread::oops_do_frames(OopClosure* f, CodeBlobClosure* cf) {
1356   if (!has_last_Java_frame()) {
1357     return;
1358   }
1359   // Finish any pending lazy GC activity for the frames
1360   StackWatermarkSet::finish_processing(this, NULL /* context */, StackWatermarkKind::gc);
1361   // Traverse the execution stack
1362   for (StackFrameStream fst(this, true /* update */, false /* process_frames */); !fst.is_done(); fst.next()) {
1363     fst.current()->oops_do(f, cf, fst.register_map());
1364   }
1365 }
1366 
1367 #ifdef ASSERT
1368 void JavaThread::verify_states_for_handshake() {
1369   // This checks that the thread has a correct frame state during a handshake.
1370   verify_frame_info();
1371 }
1372 #endif
1373 
1374 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
1375   DEBUG_ONLY(verify_frame_info();)
1376   MACOS_AARCH64_ONLY(ThreadWXEnable wx(WXWrite, Thread::current());)
1377 
1378   if (has_last_Java_frame()) {
1379     // Traverse the execution stack
1380     for (StackFrameStream fst(this, true /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
1381       fst.current()->nmethods_do(cf);
1382     }
1383   }
1384 
1385   if (jvmti_thread_state() != NULL) {
1386     jvmti_thread_state()->nmethods_do(cf);
1387   }
1388 }
1389 
1390 void JavaThread::metadata_do(MetadataClosure* f) {
1391   if (has_last_Java_frame()) {
1392     // Traverse the execution stack to call f() on the methods in the stack
1393     for (StackFrameStream fst(this, true /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
1394       fst.current()->metadata_do(f);
1395     }
1396   } else if (is_Compiler_thread()) {
1397     // need to walk ciMetadata in current compile tasks to keep alive.
1398     CompilerThread* ct = (CompilerThread*)this;
1399     if (ct->env() != NULL) {
1400       ct->env()->metadata_do(f);
1401     }
1402     CompileTask* task = ct->task();
1403     if (task != NULL) {
1404       task->metadata_do(f);
1405     }
1406   }
1407 }
1408 
1409 // Printing
1410 const char* _get_thread_state_name(JavaThreadState _thread_state) {
1411   switch (_thread_state) {
1412   case _thread_uninitialized:     return "_thread_uninitialized";
1413   case _thread_new:               return "_thread_new";
1414   case _thread_new_trans:         return "_thread_new_trans";
1415   case _thread_in_native:         return "_thread_in_native";
1416   case _thread_in_native_trans:   return "_thread_in_native_trans";
1417   case _thread_in_vm:             return "_thread_in_vm";
1418   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
1419   case _thread_in_Java:           return "_thread_in_Java";
1420   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
1421   case _thread_blocked:           return "_thread_blocked";
1422   case _thread_blocked_trans:     return "_thread_blocked_trans";
1423   default:                        return "unknown thread state";
1424   }
1425 }
1426 
1427 void JavaThread::print_thread_state_on(outputStream *st) const {
1428   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
1429 }
1430 
1431 const char* JavaThread::thread_state_name() const {
1432   return _get_thread_state_name(_thread_state);
1433 }
1434 
1435 // Called by Threads::print() for VM_PrintThreads operation
1436 void JavaThread::print_on(outputStream *st, bool print_extended_info) const {
1437   st->print_raw("\"");
1438   st->print_raw(name());
1439   st->print_raw("\" ");
1440   oop thread_oop = threadObj();
1441   if (thread_oop != NULL) {
1442     st->print("#" INT64_FORMAT " [%ld] ", (int64_t)java_lang_Thread::thread_id(thread_oop), (long) osthread()->thread_id());
1443     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
1444     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
1445   }
1446   Thread::print_on(st, print_extended_info);
1447   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
1448   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
1449   if (thread_oop != NULL) {
1450     if (is_vthread_mounted()) {
1451       oop vt = vthread();
1452       assert(vt != NULL, "");
1453       st->print_cr("   Carrying virtual thread #" INT64_FORMAT, (int64_t)java_lang_Thread::thread_id(vt));
1454     } else {
1455       st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
1456     }
1457   }
1458 #ifndef PRODUCT
1459   _safepoint_state->print_on(st);
1460 #endif // PRODUCT
1461   if (is_Compiler_thread()) {
1462     CompileTask *task = ((CompilerThread*)this)->task();
1463     if (task != NULL) {
1464       st->print("   Compiling: ");
1465       task->print(st, NULL, true, false);
1466     } else {
1467       st->print("   No compile task");
1468     }
1469     st->cr();
1470   }
1471 }
1472 
1473 void JavaThread::print() const { print_on(tty); }
1474 
1475 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
1476   st->print("%s", get_thread_name_string(buf, buflen));
1477 }
1478 
1479 // Called by fatal error handler. The difference between this and
1480 // JavaThread::print() is that we can't grab lock or allocate memory.
1481 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
1482   st->print("%s \"%s\"", type_name(), get_thread_name_string(buf, buflen));
1483   Thread* current = Thread::current_or_null_safe();
1484   assert(current != nullptr, "cannot be called by a detached thread");
1485   if (!current->is_Java_thread() || JavaThread::cast(current)->is_oop_safe()) {
1486     // Only access threadObj() if current thread is not a JavaThread
1487     // or if it is a JavaThread that can safely access oops.
1488     oop thread_obj = threadObj();
1489     if (thread_obj != nullptr) {
1490       if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
1491     }
1492   }
1493   st->print(" [");
1494   st->print("%s", _get_thread_state_name(_thread_state));
1495   if (osthread()) {
1496     st->print(", id=%d", osthread()->thread_id());
1497   }
1498   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
1499             p2i(stack_end()), p2i(stack_base()));
1500   st->print("]");
1501 
1502   ThreadsSMRSupport::print_info_on(this, st);
1503   return;
1504 }
1505 
1506 
1507 // Verification
1508 
1509 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
1510   // ignore if there is no stack
1511   if (!has_last_Java_frame()) return;
1512   // traverse the stack frames. Starts from top frame.
1513   for (StackFrameStream fst(this, true /* update_map */, true /* process_frames */, false /* walk_cont */); !fst.is_done(); fst.next()) {
1514     frame* fr = fst.current();
1515     f(fr, fst.register_map());
1516   }
1517 }
1518 
1519 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
1520 
1521 void JavaThread::verify() {
1522   // Verify oops in the thread.
1523   oops_do(&VerifyOopClosure::verify_oop, NULL);
1524 
1525   // Verify the stack frames.
1526   frames_do(frame_verify);
1527 }
1528 
1529 // CR 6300358 (sub-CR 2137150)
1530 // Most callers of this method assume that it can't return NULL but a
1531 // thread may not have a name whilst it is in the process of attaching to
1532 // the VM - see CR 6412693, and there are places where a JavaThread can be
1533 // seen prior to having its threadObj set (e.g., JNI attaching threads and
1534 // if vm exit occurs during initialization). These cases can all be accounted
1535 // for such that this method never returns NULL.
1536 const char* JavaThread::name() const  {
1537   if (Thread::is_JavaThread_protected(/* target */ this)) {
1538     // The target JavaThread is protected so get_thread_name_string() is safe:
1539     return get_thread_name_string();
1540   }
1541 
1542   // The target JavaThread is not protected so we return the default:
1543   return Thread::name();
1544 }
1545 
1546 // Returns a non-NULL representation of this thread's name, or a suitable
1547 // descriptive string if there is no set name.
1548 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
1549   const char* name_str;
1550 #ifdef ASSERT
1551   Thread* current = Thread::current_or_null_safe();
1552   assert(current != nullptr, "cannot be called by a detached thread");
1553   if (!current->is_Java_thread() || JavaThread::cast(current)->is_oop_safe()) {
1554     // Only access threadObj() if current thread is not a JavaThread
1555     // or if it is a JavaThread that can safely access oops.
1556 #endif
1557     oop thread_obj = threadObj();
1558     if (thread_obj != NULL) {
1559       oop name = java_lang_Thread::name(thread_obj);
1560       if (name != NULL) {
1561         if (buf == NULL) {
1562           name_str = java_lang_String::as_utf8_string(name);
1563         } else {
1564           name_str = java_lang_String::as_utf8_string(name, buf, buflen);
1565         }
1566       } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
1567         name_str = "<no-name - thread is attaching>";
1568       } else {
1569         name_str = "<un-named>";
1570       }
1571     } else {
1572       name_str = Thread::name();
1573     }
1574 #ifdef ASSERT
1575   } else {
1576     // Current JavaThread has exited...
1577     if (current == this) {
1578       // ... and is asking about itself:
1579       name_str = "<no-name - current JavaThread has exited>";
1580     } else {
1581       // ... and it can't safely determine this JavaThread's name so
1582       // use the default thread name.
1583       name_str = Thread::name();
1584     }
1585   }
1586 #endif
1587   assert(name_str != NULL, "unexpected NULL thread name");
1588   return name_str;
1589 }
1590 
1591 // Helper to extract the name from the thread oop for logging.
1592 const char* JavaThread::name_for(oop thread_obj) {
1593   assert(thread_obj != NULL, "precondition");
1594   oop name = java_lang_Thread::name(thread_obj);
1595   const char* name_str;
1596   if (name != NULL) {
1597     name_str = java_lang_String::as_utf8_string(name);
1598   } else {
1599     name_str = "<un-named>";
1600   }
1601   return name_str;
1602 }
1603 
1604 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
1605 
1606   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
1607   assert(NoPriority <= prio && prio <= MaxPriority, "sanity check");
1608   // Link Java Thread object <-> C++ Thread
1609 
1610   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
1611   // and put it into a new Handle.  The Handle "thread_oop" can then
1612   // be used to pass the C++ thread object to other methods.
1613 
1614   // Set the Java level thread object (jthread) field of the
1615   // new thread (a JavaThread *) to C++ thread object using the
1616   // "thread_oop" handle.
1617 
1618   // Set the thread field (a JavaThread *) of the
1619   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
1620 
1621   Handle thread_oop(Thread::current(),
1622                     JNIHandles::resolve_non_null(jni_thread));
1623   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
1624          "must be initialized");
1625   set_threadOopHandles(thread_oop());
1626   java_lang_Thread::set_thread(thread_oop(), this);
1627 
1628   if (prio == NoPriority) {
1629     prio = java_lang_Thread::priority(thread_oop());
1630     assert(prio != NoPriority, "A valid priority should be present");
1631   }
1632 
1633   // Push the Java priority down to the native thread; needs Threads_lock
1634   Thread::set_priority(this, prio);
1635 
1636   // Add the new thread to the Threads list and set it in motion.
1637   // We must have threads lock in order to call Threads::add.
1638   // It is crucial that we do not block before the thread is
1639   // added to the Threads list for if a GC happens, then the java_thread oop
1640   // will not be visited by GC.
1641   Threads::add(this);
1642 }
1643 
1644 oop JavaThread::current_park_blocker() {
1645   // Support for JSR-166 locks
1646   oop thread_oop = threadObj();
1647   if (thread_oop != NULL) {
1648     return java_lang_Thread::park_blocker(thread_oop);
1649   }
1650   return NULL;
1651 }
1652 
1653 
1654 void JavaThread::print_stack_on(outputStream* st) {
1655   if (!has_last_Java_frame()) return;
1656 
1657   Thread* current_thread = Thread::current();
1658   ResourceMark rm(current_thread);
1659   HandleMark hm(current_thread);
1660 
1661   RegisterMap reg_map(this,
1662                       RegisterMap::UpdateMap::include,
1663                       RegisterMap::ProcessFrames::include,
1664                       RegisterMap::WalkContinuation::skip);
1665   vframe* start_vf = platform_thread_last_java_vframe(&reg_map);
1666   int count = 0;
1667   for (vframe* f = start_vf; f != NULL; f = f->sender()) {
1668     if (f->is_java_frame()) {
1669       javaVFrame* jvf = javaVFrame::cast(f);
1670       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
1671 
1672       // Print out lock information
1673       if (JavaMonitorsInStackTrace) {
1674         jvf->print_lock_info_on(st, count);
1675       }
1676     } else {
1677       // Ignore non-Java frames
1678     }
1679 
1680     // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
1681     count++;
1682     if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
1683   }
1684 }
1685 
1686 #if INCLUDE_JVMTI
1687 // Rebind JVMTI thread state from carrier to virtual or from virtual to carrier.
1688 JvmtiThreadState* JavaThread::rebind_to_jvmti_thread_state_of(oop thread_oop) {
1689   set_jvmti_vthread(thread_oop);
1690 
1691   // unbind current JvmtiThreadState from JavaThread
1692   JvmtiThreadState::unbind_from(jvmti_thread_state(), this);
1693 
1694   // bind new JvmtiThreadState to JavaThread
1695   JvmtiThreadState::bind_to(java_lang_Thread::jvmti_thread_state(thread_oop), this);
1696 
1697   return jvmti_thread_state();
1698 }
1699 #endif
1700 
1701 // JVMTI PopFrame support
1702 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
1703   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
1704   if (in_bytes(size_in_bytes) != 0) {
1705     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
1706     _popframe_preserved_args_size = in_bytes(size_in_bytes);
1707     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
1708   }
1709 }
1710 
1711 void* JavaThread::popframe_preserved_args() {
1712   return _popframe_preserved_args;
1713 }
1714 
1715 ByteSize JavaThread::popframe_preserved_args_size() {
1716   return in_ByteSize(_popframe_preserved_args_size);
1717 }
1718 
1719 WordSize JavaThread::popframe_preserved_args_size_in_words() {
1720   int sz = in_bytes(popframe_preserved_args_size());
1721   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
1722   return in_WordSize(sz / wordSize);
1723 }
1724 
1725 void JavaThread::popframe_free_preserved_args() {
1726   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
1727   FREE_C_HEAP_ARRAY(char, (char*)_popframe_preserved_args);
1728   _popframe_preserved_args = NULL;
1729   _popframe_preserved_args_size = 0;
1730 }
1731 
1732 #ifndef PRODUCT
1733 
1734 void JavaThread::trace_frames() {
1735   tty->print_cr("[Describe stack]");
1736   int frame_no = 1;
1737   for (StackFrameStream fst(this, true /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
1738     tty->print("  %d. ", frame_no++);
1739     fst.current()->print_value_on(tty, this);
1740     tty->cr();
1741   }
1742 }
1743 
1744 class PrintAndVerifyOopClosure: public OopClosure {
1745  protected:
1746   template <class T> inline void do_oop_work(T* p) {
1747     oop obj = RawAccess<>::oop_load(p);
1748     if (obj == NULL) return;
1749     tty->print(INTPTR_FORMAT ": ", p2i(p));
1750     if (oopDesc::is_oop_or_null(obj)) {
1751       if (obj->is_objArray()) {
1752         tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
1753       } else {
1754         obj->print();
1755       }
1756     } else {
1757       tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
1758     }
1759     tty->cr();
1760   }
1761  public:
1762   virtual void do_oop(oop* p) { do_oop_work(p); }
1763   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
1764 };
1765 
1766 #ifdef ASSERT
1767 // Print or validate the layout of stack frames
1768 void JavaThread::print_frame_layout(int depth, bool validate_only) {
1769   ResourceMark rm;
1770   PreserveExceptionMark pm(this);
1771   FrameValues values;
1772   int frame_no = 0;
1773   for (StackFrameStream fst(this, true, true, true); !fst.is_done(); fst.next()) {
1774     fst.current()->describe(values, ++frame_no, fst.register_map());
1775     if (depth == frame_no) break;
1776   }
1777   Continuation::describe(values);
1778   if (validate_only) {
1779     values.validate();
1780   } else {
1781     tty->print_cr("[Describe stack layout]");
1782     values.print(this);
1783   }
1784 }
1785 #endif
1786 
1787 void JavaThread::trace_stack_from(vframe* start_vf) {
1788   ResourceMark rm;
1789   int vframe_no = 1;
1790   for (vframe* f = start_vf; f; f = f->sender()) {
1791     if (f->is_java_frame()) {
1792       javaVFrame::cast(f)->print_activation(vframe_no++);
1793     } else {
1794       f->print();
1795     }
1796     if (vframe_no > StackPrintLimit) {
1797       tty->print_cr("...<more frames>...");
1798       return;
1799     }
1800   }
1801 }
1802 
1803 
1804 void JavaThread::trace_stack() {
1805   if (!has_last_Java_frame()) return;
1806   Thread* current_thread = Thread::current();
1807   ResourceMark rm(current_thread);
1808   HandleMark hm(current_thread);
1809   RegisterMap reg_map(this,
1810                       RegisterMap::UpdateMap::include,
1811                       RegisterMap::ProcessFrames::include,
1812                       RegisterMap::WalkContinuation::skip);
1813   trace_stack_from(last_java_vframe(&reg_map));
1814 }
1815 
1816 
1817 #endif // PRODUCT
1818 
1819 void JavaThread::inc_held_monitor_count(int i, bool jni) {
1820 #ifdef SUPPORT_MONITOR_COUNT
1821   assert(_held_monitor_count >= 0, "Must always be greater than 0: " INT64_FORMAT, (int64_t)_held_monitor_count);
1822   _held_monitor_count += i;
1823   if (jni) {
1824     assert(_jni_monitor_count >= 0, "Must always be greater than 0: " INT64_FORMAT, (int64_t)_jni_monitor_count);
1825     _jni_monitor_count += i;
1826   }
1827 #endif
1828 }
1829 
1830 void JavaThread::dec_held_monitor_count(int i, bool jni) {
1831 #ifdef SUPPORT_MONITOR_COUNT
1832   _held_monitor_count -= i;
1833   assert(_held_monitor_count >= 0, "Must always be greater than 0: " INT64_FORMAT, (int64_t)_held_monitor_count);
1834   if (jni) {
1835     _jni_monitor_count -= i;
1836     assert(_jni_monitor_count >= 0, "Must always be greater than 0: " INT64_FORMAT, (int64_t)_jni_monitor_count);
1837   }
1838 #endif
1839 }
1840 
1841 frame JavaThread::vthread_last_frame() {
1842   assert (is_vthread_mounted(), "Virtual thread not mounted");
1843   return last_frame();
1844 }
1845 
1846 frame JavaThread::carrier_last_frame(RegisterMap* reg_map) {
1847   const ContinuationEntry* entry = vthread_continuation();
1848   guarantee (entry != NULL, "Not a carrier thread");
1849   frame f = entry->to_frame();
1850   if (reg_map->process_frames()) {
1851     entry->flush_stack_processing(this);
1852   }
1853   entry->update_register_map(reg_map);
1854   return f.sender(reg_map);
1855 }
1856 
1857 frame JavaThread::platform_thread_last_frame(RegisterMap* reg_map) {
1858   return is_vthread_mounted() ? carrier_last_frame(reg_map) : last_frame();
1859 }
1860 
1861 javaVFrame* JavaThread::last_java_vframe(const frame f, RegisterMap *reg_map) {
1862   assert(reg_map != NULL, "a map must be given");
1863   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
1864     if (vf->is_java_frame()) return javaVFrame::cast(vf);
1865   }
1866   return NULL;
1867 }
1868 
1869 oop JavaThread::get_continuation() const {
1870   assert(threadObj() != nullptr, "must be set");
1871   return java_lang_Thread::continuation(threadObj());
1872 }
1873 
1874 Klass* JavaThread::security_get_caller_class(int depth) {
1875   ResetNoHandleMark rnhm;
1876   HandleMark hm(Thread::current());
1877 
1878   vframeStream vfst(this);
1879   vfst.security_get_caller_frame(depth);
1880   if (!vfst.at_end()) {
1881     return vfst.method()->method_holder();
1882   }
1883   return NULL;
1884 }
1885 
1886 // java.lang.Thread.sleep support
1887 // Returns true if sleep time elapsed as expected, and false
1888 // if the thread was interrupted.
1889 bool JavaThread::sleep(jlong millis) {
1890   assert(this == Thread::current(),  "thread consistency check");
1891 
1892   ParkEvent * const slp = this->_SleepEvent;
1893   // Because there can be races with thread interruption sending an unpark()
1894   // to the event, we explicitly reset it here to avoid an immediate return.
1895   // The actual interrupt state will be checked before we park().
1896   slp->reset();
1897   // Thread interruption establishes a happens-before ordering in the
1898   // Java Memory Model, so we need to ensure we synchronize with the
1899   // interrupt state.
1900   OrderAccess::fence();
1901 
1902   jlong prevtime = os::javaTimeNanos();
1903 
1904   for (;;) {
1905     // interruption has precedence over timing out
1906     if (this->is_interrupted(true)) {
1907       return false;
1908     }
1909 
1910     if (millis <= 0) {
1911       return true;
1912     }
1913 
1914     {
1915       ThreadBlockInVM tbivm(this);
1916       OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1917       slp->park(millis);
1918     }
1919 
1920     // Update elapsed time tracking
1921     jlong newtime = os::javaTimeNanos();
1922     if (newtime - prevtime < 0) {
1923       // time moving backwards, should only happen if no monotonic clock
1924       // not a guarantee() because JVM should not abort on kernel/glibc bugs
1925       assert(false,
1926              "unexpected time moving backwards detected in JavaThread::sleep()");
1927     } else {
1928       millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC;
1929     }
1930     prevtime = newtime;
1931   }
1932 }
1933 
1934 // Last thread running calls java.lang.Shutdown.shutdown()
1935 void JavaThread::invoke_shutdown_hooks() {
1936   HandleMark hm(this);
1937 
1938   // We could get here with a pending exception, if so clear it now or
1939   // it will cause MetaspaceShared::link_shared_classes to
1940   // fail for dynamic dump.
1941   if (this->has_pending_exception()) {
1942     this->clear_pending_exception();
1943   }
1944 
1945 #if INCLUDE_CDS
1946   // Link all classes for dynamic CDS dumping before vm exit.
1947   // Same operation is being done in JVM_BeforeHalt for handling the
1948   // case where the application calls System.exit().
1949   if (DynamicArchive::should_dump_at_vm_exit()) {
1950     DynamicArchive::prepare_for_dump_at_exit();
1951   }
1952 #endif
1953 
1954   EXCEPTION_MARK;
1955   Klass* shutdown_klass =
1956     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
1957                                       THREAD);
1958   if (shutdown_klass != NULL) {
1959     // SystemDictionary::resolve_or_null will return null if there was
1960     // an exception.  If we cannot load the Shutdown class, just don't
1961     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
1962     // won't be run.  Note that if a shutdown hook was registered,
1963     // the Shutdown class would have already been loaded
1964     // (Runtime.addShutdownHook will load it).
1965     JavaValue result(T_VOID);
1966     JavaCalls::call_static(&result,
1967                            shutdown_klass,
1968                            vmSymbols::shutdown_name(),
1969                            vmSymbols::void_method_signature(),
1970                            THREAD);
1971   }
1972   CLEAR_PENDING_EXCEPTION;
1973 }
1974 
1975 #ifndef PRODUCT
1976 void JavaThread::verify_cross_modify_fence_failure(JavaThread *thread) {
1977    report_vm_error(__FILE__, __LINE__, "Cross modify fence failure", "%p", thread);
1978 }
1979 #endif
1980 
1981 // Helper function to create the java.lang.Thread object for a
1982 // VM-internal thread. The thread will have the given name, and be
1983 // a member of the "system" ThreadGroup.
1984 Handle JavaThread::create_system_thread_object(const char* name,
1985                                                bool is_visible, TRAPS) {
1986   Handle string = java_lang_String::create_from_str(name, CHECK_NH);
1987 
1988   // Initialize thread_oop to put it into the system threadGroup.
1989   // This is done by calling the Thread(ThreadGroup group, String name) constructor.
1990   Handle thread_group(THREAD, Universe::system_thread_group());
1991   Handle thread_oop =
1992     JavaCalls::construct_new_instance(vmClasses::Thread_klass(),
1993                                       vmSymbols::threadgroup_string_void_signature(),
1994                                       thread_group,
1995                                       string,
1996                                       CHECK_NH);
1997 
1998   return thread_oop;
1999 }
2000 
2001 // Starts the target JavaThread as a daemon of the given priority, and
2002 // bound to the given java.lang.Thread instance.
2003 // The Threads_lock is held for the duration.
2004 void JavaThread::start_internal_daemon(JavaThread* current, JavaThread* target,
2005                                        Handle thread_oop, ThreadPriority prio) {
2006 
2007   assert(target->osthread() != NULL, "target thread is not properly initialized");
2008 
2009   MutexLocker mu(current, Threads_lock);
2010 
2011   // Initialize the fields of the thread_oop first.
2012 
2013   java_lang_Thread::set_thread(thread_oop(), target); // isAlive == true now
2014 
2015   if (prio != NoPriority) {
2016     java_lang_Thread::set_priority(thread_oop(), prio);
2017     // Note: we don't call os::set_priority here. Possibly we should,
2018     // else all threads should call it themselves when they first run.
2019   }
2020 
2021   java_lang_Thread::set_daemon(thread_oop());
2022 
2023   // Now bind the thread_oop to the target JavaThread.
2024   target->set_threadOopHandles(thread_oop());
2025 
2026   Threads::add(target); // target is now visible for safepoint/handshake
2027   Thread::start(target);
2028 }
2029 
2030 void JavaThread::vm_exit_on_osthread_failure(JavaThread* thread) {
2031   // At this point it may be possible that no osthread was created for the
2032   // JavaThread due to lack of resources. However, since this must work
2033   // for critical system threads just check and abort if this fails.
2034   if (thread->osthread() == nullptr) {
2035     // This isn't really an OOM condition, but historically this is what
2036     // we report.
2037     vm_exit_during_initialization("java.lang.OutOfMemoryError",
2038                                   os::native_thread_creation_failed_msg());
2039   }
2040 }