1 /*
   2  * Copyright (c) 1997, 2024, Oracle and/or its affiliates. All rights reserved.
   3  * Copyright (c) 2021, Azul Systems, Inc. All rights reserved.
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This code is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 only, as
   8  * published by the Free Software Foundation.
   9  *
  10  * This code is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  13  * version 2 for more details (a copy is included in the LICENSE file that
  14  * accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License version
  17  * 2 along with this work; if not, write to the Free Software Foundation,
  18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  19  *
  20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  21  * or visit www.oracle.com if you need additional information or have any
  22  * questions.
  23  *
  24  */
  25 
  26 #include "precompiled.hpp"
  27 #include "cds/dynamicArchive.hpp"
  28 #include "ci/ciEnv.hpp"
  29 #include "classfile/javaClasses.inline.hpp"
  30 #include "classfile/javaThreadStatus.hpp"
  31 #include "classfile/systemDictionary.hpp"
  32 #include "classfile/vmClasses.hpp"
  33 #include "classfile/vmSymbols.hpp"
  34 #include "code/codeCache.hpp"
  35 #include "code/scopeDesc.hpp"
  36 #include "compiler/compileTask.hpp"
  37 #include "compiler/compilerThread.hpp"
  38 #include "gc/shared/oopStorage.hpp"
  39 #include "gc/shared/oopStorageSet.hpp"
  40 #include "gc/shared/tlab_globals.hpp"
  41 #include "jfr/jfrEvents.hpp"
  42 #include "jvm.h"
  43 #include "jvmtifiles/jvmtiEnv.hpp"
  44 #include "logging/log.hpp"
  45 #include "logging/logAsyncWriter.hpp"
  46 #include "logging/logStream.hpp"
  47 #include "memory/allocation.inline.hpp"
  48 #include "memory/iterator.hpp"
  49 #include "memory/universe.hpp"
  50 #include "oops/access.inline.hpp"
  51 #include "oops/instanceKlass.hpp"
  52 #include "oops/klass.inline.hpp"
  53 #include "oops/oop.inline.hpp"
  54 #include "oops/oopHandle.inline.hpp"
  55 #include "oops/verifyOopClosure.hpp"
  56 #include "prims/jvm_misc.hpp"
  57 #include "prims/jvmtiDeferredUpdates.hpp"
  58 #include "prims/jvmtiExport.hpp"
  59 #include "prims/jvmtiThreadState.inline.hpp"
  60 #include "runtime/atomic.hpp"
  61 #include "runtime/continuation.hpp"
  62 #include "runtime/continuationEntry.inline.hpp"
  63 #include "runtime/continuationHelper.inline.hpp"
  64 #include "runtime/deoptimization.hpp"
  65 #include "runtime/frame.inline.hpp"
  66 #include "runtime/handles.inline.hpp"
  67 #include "runtime/handshake.hpp"
  68 #include "runtime/interfaceSupport.inline.hpp"
  69 #include "runtime/java.hpp"
  70 #include "runtime/javaCalls.hpp"
  71 #include "runtime/javaThread.inline.hpp"
  72 #include "runtime/jniHandles.inline.hpp"
  73 #include "runtime/lockStack.inline.hpp"
  74 #include "runtime/mutexLocker.hpp"
  75 #include "runtime/orderAccess.hpp"
  76 #include "runtime/os.inline.hpp"
  77 #include "runtime/osThread.hpp"
  78 #include "runtime/safepoint.hpp"
  79 #include "runtime/safepointMechanism.inline.hpp"
  80 #include "runtime/safepointVerifiers.hpp"
  81 #include "runtime/serviceThread.hpp"
  82 #include "runtime/stackFrameStream.inline.hpp"
  83 #include "runtime/stackWatermarkSet.hpp"
  84 #include "runtime/synchronizer.hpp"
  85 #include "runtime/threadCritical.hpp"
  86 #include "runtime/threadSMR.inline.hpp"
  87 #include "runtime/threadStatisticalInfo.hpp"
  88 #include "runtime/threadWXSetters.inline.hpp"
  89 #include "runtime/timer.hpp"
  90 #include "runtime/timerTrace.hpp"
  91 #include "runtime/vframe.inline.hpp"
  92 #include "runtime/vframeArray.hpp"
  93 #include "runtime/vframe_hp.hpp"
  94 #include "runtime/vmThread.hpp"
  95 #include "runtime/vmOperations.hpp"
  96 #include "services/threadService.hpp"
  97 #include "utilities/copy.hpp"
  98 #include "utilities/defaultStream.hpp"
  99 #include "utilities/dtrace.hpp"
 100 #include "utilities/events.hpp"
 101 #include "utilities/globalDefinitions.hpp"
 102 #include "utilities/macros.hpp"
 103 #include "utilities/preserveException.hpp"
 104 #include "utilities/spinYield.hpp"
 105 #include "utilities/vmError.hpp"
 106 #if INCLUDE_JVMCI
 107 #include "jvmci/jvmci.hpp"
 108 #include "jvmci/jvmciEnv.hpp"
 109 #endif
 110 #if INCLUDE_JFR
 111 #include "jfr/jfr.hpp"
 112 #endif
 113 
 114 // Set by os layer.
 115 size_t      JavaThread::_stack_size_at_create = 0;
 116 
 117 #ifdef DTRACE_ENABLED
 118 
 119 // Only bother with this argument setup if dtrace is available
 120 
 121   #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
 122   #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
 123 
 124   #define DTRACE_THREAD_PROBE(probe, javathread)                           \
 125     {                                                                      \
 126       ResourceMark rm(this);                                               \
 127       int len = 0;                                                         \
 128       const char* name = (javathread)->name();                             \
 129       len = strlen(name);                                                  \
 130       HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */               \
 131         (char *) name, len,                                                \
 132         java_lang_Thread::thread_id((javathread)->threadObj()),            \
 133         (uintptr_t) (javathread)->osthread()->thread_id(),                 \
 134         java_lang_Thread::is_daemon((javathread)->threadObj()));           \
 135     }
 136 
 137 #else //  ndef DTRACE_ENABLED
 138 
 139   #define DTRACE_THREAD_PROBE(probe, javathread)
 140 
 141 #endif // ndef DTRACE_ENABLED
 142 
 143 void JavaThread::smr_delete() {
 144   if (_on_thread_list) {
 145     ThreadsSMRSupport::smr_delete(this);
 146   } else {
 147     delete this;
 148   }
 149 }
 150 
 151 // Initialized by VMThread at vm_global_init
 152 OopStorage* JavaThread::_thread_oop_storage = nullptr;
 153 
 154 OopStorage* JavaThread::thread_oop_storage() {
 155   assert(_thread_oop_storage != nullptr, "not yet initialized");
 156   return _thread_oop_storage;
 157 }
 158 
 159 void JavaThread::set_threadOopHandles(oop p) {
 160   assert(_thread_oop_storage != nullptr, "not yet initialized");
 161   _threadObj   = OopHandle(_thread_oop_storage, p);
 162   _vthread     = OopHandle(_thread_oop_storage, p);
 163   _jvmti_vthread = OopHandle(_thread_oop_storage, p->is_a(vmClasses::BoundVirtualThread_klass()) ? p : nullptr);
 164   _scopedValueCache = OopHandle(_thread_oop_storage, nullptr);
 165 }
 166 
 167 oop JavaThread::threadObj() const {
 168   // Ideally we would verify the current thread is oop_safe when this is called, but as we can
 169   // be called from a signal handler we would have to use Thread::current_or_null_safe(). That
 170   // has overhead and also interacts poorly with GetLastError on Windows due to the use of TLS.
 171   // Instead callers must verify oop safe access.
 172   return _threadObj.resolve();
 173 }
 174 
 175 oop JavaThread::vthread() const {
 176   return _vthread.resolve();
 177 }
 178 
 179 void JavaThread::set_vthread(oop p) {
 180   assert(_thread_oop_storage != nullptr, "not yet initialized");
 181   _vthread.replace(p);
 182 }
 183 
 184 oop JavaThread::jvmti_vthread() const {
 185   return _jvmti_vthread.resolve();
 186 }
 187 
 188 void JavaThread::set_jvmti_vthread(oop p) {
 189   assert(_thread_oop_storage != nullptr, "not yet initialized");
 190   _jvmti_vthread.replace(p);
 191 }
 192 
 193 // If there is a virtual thread mounted then return vthread() oop.
 194 // Otherwise, return threadObj().
 195 oop JavaThread::vthread_or_thread() const {
 196   oop result = vthread();
 197   if (result == nullptr) {
 198     result = threadObj();
 199   }
 200   return result;
 201 }
 202 
 203 oop JavaThread::scopedValueCache() const {
 204   return _scopedValueCache.resolve();
 205 }
 206 
 207 void JavaThread::set_scopedValueCache(oop p) {
 208   if (!_scopedValueCache.is_empty()) { // i.e. if the OopHandle has been allocated
 209     _scopedValueCache.replace(p);
 210   } else {
 211     assert(p == nullptr, "not yet initialized");
 212   }
 213 }
 214 
 215 void JavaThread::clear_scopedValueBindings() {
 216   set_scopedValueCache(nullptr);
 217   oop vthread_oop = vthread();
 218   // vthread may be null here if we get a VM error during startup,
 219   // before the java.lang.Thread instance has been created.
 220   if (vthread_oop != nullptr) {
 221     java_lang_Thread::clear_scopedValueBindings(vthread_oop);
 222   }
 223 }
 224 
 225 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
 226                                     bool daemon, TRAPS) {
 227   assert(thread_group.not_null(), "thread group should be specified");
 228   assert(threadObj() == nullptr, "should only create Java thread object once");
 229 
 230   InstanceKlass* ik = vmClasses::Thread_klass();
 231   assert(ik->is_initialized(), "must be");
 232   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
 233 
 234   // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon.
 235   // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread
 236   // constructor calls Thread.current(), which must be set here.
 237   java_lang_Thread::set_thread(thread_oop(), this);
 238   set_threadOopHandles(thread_oop());
 239 
 240   JavaValue result(T_VOID);
 241   if (thread_name != nullptr) {
 242     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
 243     // Thread gets assigned specified name and null target
 244     JavaCalls::call_special(&result,
 245                             thread_oop,
 246                             ik,
 247                             vmSymbols::object_initializer_name(),
 248                             vmSymbols::threadgroup_string_void_signature(),
 249                             thread_group,
 250                             name,
 251                             CHECK);
 252   } else {
 253     // Thread gets assigned name "Thread-nnn" and null target
 254     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
 255     JavaCalls::call_special(&result,
 256                             thread_oop,
 257                             ik,
 258                             vmSymbols::object_initializer_name(),
 259                             vmSymbols::threadgroup_runnable_void_signature(),
 260                             thread_group,
 261                             Handle(),
 262                             CHECK);
 263   }
 264   os::set_priority(this, NormPriority);
 265 
 266   if (daemon) {
 267     java_lang_Thread::set_daemon(thread_oop());
 268   }
 269 }
 270 
 271 // ======= JavaThread ========
 272 
 273 #if INCLUDE_JVMCI
 274 
 275 jlong* JavaThread::_jvmci_old_thread_counters;
 276 
 277 static bool jvmci_counters_include(JavaThread* thread) {
 278   return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
 279 }
 280 
 281 void JavaThread::collect_counters(jlong* array, int length) {
 282   assert(length == JVMCICounterSize, "wrong value");
 283   for (int i = 0; i < length; i++) {
 284     array[i] = _jvmci_old_thread_counters[i];
 285   }
 286   for (JavaThread* tp : ThreadsListHandle()) {
 287     if (jvmci_counters_include(tp)) {
 288       for (int i = 0; i < length; i++) {
 289         array[i] += tp->_jvmci_counters[i];
 290       }
 291     }
 292   }
 293 }
 294 
 295 // Attempt to enlarge the array for per thread counters.
 296 static jlong* resize_counters_array(jlong* old_counters, int current_size, int new_size) {
 297   jlong* new_counters = NEW_C_HEAP_ARRAY_RETURN_NULL(jlong, new_size, mtJVMCI);
 298   if (new_counters == nullptr) {
 299     return nullptr;
 300   }
 301   if (old_counters == nullptr) {
 302     old_counters = new_counters;
 303     memset(old_counters, 0, sizeof(jlong) * new_size);
 304   } else {
 305     for (int i = 0; i < MIN2((int) current_size, new_size); i++) {
 306       new_counters[i] = old_counters[i];
 307     }
 308     if (new_size > current_size) {
 309       memset(new_counters + current_size, 0, sizeof(jlong) * (new_size - current_size));
 310     }
 311     FREE_C_HEAP_ARRAY(jlong, old_counters);
 312   }
 313   return new_counters;
 314 }
 315 
 316 // Attempt to enlarge the array for per thread counters.
 317 bool JavaThread::resize_counters(int current_size, int new_size) {
 318   jlong* new_counters = resize_counters_array(_jvmci_counters, current_size, new_size);
 319   if (new_counters == nullptr) {
 320     return false;
 321   } else {
 322     _jvmci_counters = new_counters;
 323     return true;
 324   }
 325 }
 326 
 327 class VM_JVMCIResizeCounters : public VM_Operation {
 328  private:
 329   int _new_size;
 330   bool _failed;
 331 
 332  public:
 333   VM_JVMCIResizeCounters(int new_size) : _new_size(new_size), _failed(false) { }
 334   VMOp_Type type()                  const        { return VMOp_JVMCIResizeCounters; }
 335   bool allow_nested_vm_operations() const        { return true; }
 336   void doit() {
 337     // Resize the old thread counters array
 338     jlong* new_counters = resize_counters_array(JavaThread::_jvmci_old_thread_counters, JVMCICounterSize, _new_size);
 339     if (new_counters == nullptr) {
 340       _failed = true;
 341       return;
 342     } else {
 343       JavaThread::_jvmci_old_thread_counters = new_counters;
 344     }
 345 
 346     // Now resize each threads array
 347     for (JavaThread* tp : ThreadsListHandle()) {
 348       if (!tp->resize_counters(JVMCICounterSize, _new_size)) {
 349         _failed = true;
 350         break;
 351       }
 352     }
 353     if (!_failed) {
 354       JVMCICounterSize = _new_size;
 355     }
 356   }
 357 
 358   bool failed() { return _failed; }
 359 };
 360 
 361 bool JavaThread::resize_all_jvmci_counters(int new_size) {
 362   VM_JVMCIResizeCounters op(new_size);
 363   VMThread::execute(&op);
 364   return !op.failed();
 365 }
 366 
 367 #endif // INCLUDE_JVMCI
 368 
 369 #ifdef ASSERT
 370 // Checks safepoint allowed and clears unhandled oops at potential safepoints.
 371 void JavaThread::check_possible_safepoint() {
 372   if (_no_safepoint_count > 0) {
 373     print_owned_locks();
 374     assert(false, "Possible safepoint reached by thread that does not allow it");
 375   }
 376 #ifdef CHECK_UNHANDLED_OOPS
 377   // Clear unhandled oops in JavaThreads so we get a crash right away.
 378   clear_unhandled_oops();
 379 #endif // CHECK_UNHANDLED_OOPS
 380 
 381   // Macos/aarch64 should be in the right state for safepoint (e.g.
 382   // deoptimization needs WXWrite).  Crashes caused by the wrong state rarely
 383   // happens in practice, making such issues hard to find and reproduce.
 384 #if defined(__APPLE__) && defined(AARCH64)
 385   if (AssertWXAtThreadSync) {
 386     assert_wx_state(WXWrite);
 387   }
 388 #endif
 389 }
 390 
 391 void JavaThread::check_for_valid_safepoint_state() {
 392   // Don't complain if running a debugging command.
 393   if (DebuggingContext::is_enabled()) return;
 394 
 395   // Check NoSafepointVerifier, which is implied by locks taken that can be
 396   // shared with the VM thread.  This makes sure that no locks with allow_vm_block
 397   // are held.
 398   check_possible_safepoint();
 399 
 400   if (thread_state() != _thread_in_vm) {
 401     fatal("LEAF method calling lock?");
 402   }
 403 
 404   if (GCALotAtAllSafepoints) {
 405     // We could enter a safepoint here and thus have a gc
 406     InterfaceSupport::check_gc_alot();
 407   }
 408 }
 409 #endif // ASSERT
 410 
 411 // A JavaThread is a normal Java thread
 412 
 413 JavaThread::JavaThread() :
 414   // Initialize fields
 415 
 416   _on_thread_list(false),
 417   DEBUG_ONLY(_java_call_counter(0) COMMA)
 418   _entry_point(nullptr),
 419   _deopt_mark(nullptr),
 420   _deopt_nmethod(nullptr),
 421   _vframe_array_head(nullptr),
 422   _vframe_array_last(nullptr),
 423   _jvmti_deferred_updates(nullptr),
 424   _callee_target(nullptr),
 425   _vm_result(nullptr),
 426   _vm_result_2(nullptr),
 427 
 428   _current_pending_monitor(nullptr),
 429   _current_pending_monitor_is_from_java(true),
 430   _current_waiting_monitor(nullptr),
 431   _active_handles(nullptr),
 432   _free_handle_block(nullptr),
 433 
 434   _suspend_flags(0),
 435 
 436   _thread_state(_thread_new),
 437   _saved_exception_pc(nullptr),
 438 #ifdef ASSERT
 439   _no_safepoint_count(0),
 440   _visited_for_critical_count(false),
 441 #endif
 442 
 443   _terminated(_not_terminated),
 444   _in_deopt_handler(0),
 445   _doing_unsafe_access(false),
 446   _do_not_unlock_if_synchronized(false),
 447 #if INCLUDE_JVMTI
 448   _carrier_thread_suspended(false),
 449   _is_in_VTMS_transition(false),
 450   _is_in_tmp_VTMS_transition(false),
 451   _is_disable_suspend(false),
 452   _VTMS_transition_mark(false),
 453 #ifdef ASSERT
 454   _is_VTMS_transition_disabler(false),
 455 #endif
 456 #endif
 457   _jni_attach_state(_not_attaching_via_jni),
 458   _is_in_internal_oome_mark(false),
 459 #if INCLUDE_JVMCI
 460   _pending_deoptimization(-1),
 461   _pending_monitorenter(false),
 462   _pending_transfer_to_interpreter(false),
 463   _pending_failed_speculation(0),
 464   _jvmci{nullptr},
 465   _libjvmci_runtime(nullptr),
 466   _jvmci_counters(nullptr),
 467   _jvmci_reserved0(0),
 468   _jvmci_reserved1(0),
 469   _jvmci_reserved_oop0(nullptr),
 470   _live_nmethod(nullptr),
 471 #endif // INCLUDE_JVMCI
 472 
 473   _exception_oop(oop()),
 474   _exception_pc(0),
 475   _exception_handler_pc(0),
 476   _is_method_handle_return(0),
 477 
 478   _jni_active_critical(0),
 479   _pending_jni_exception_check_fn(nullptr),
 480   _depth_first_number(0),
 481 
 482   // JVMTI PopFrame support
 483   _popframe_condition(popframe_inactive),
 484   _frames_to_pop_failed_realloc(0),
 485 
 486   _cont_entry(nullptr),
 487   _cont_fastpath(0),
 488   _cont_fastpath_thread_state(1),
 489   _held_monitor_count(0),
 490   _jni_monitor_count(0),
 491 
 492   _handshake(this),
 493 
 494   _popframe_preserved_args(nullptr),
 495   _popframe_preserved_args_size(0),
 496 
 497   _jvmti_thread_state(nullptr),
 498   _interp_only_mode(0),
 499   _should_post_on_exceptions_flag(JNI_FALSE),
 500   _thread_stat(new ThreadStatistics()),
 501 
 502   _parker(),
 503 
 504   _class_to_be_initialized(nullptr),
 505 
 506   _SleepEvent(ParkEvent::Allocate(this)),
 507 
 508   _lock_stack(this),
 509   _om_cache(this) {
 510   set_jni_functions(jni_functions());
 511 
 512 #if INCLUDE_JVMCI
 513   assert(_jvmci._implicit_exception_pc == nullptr, "must be");
 514   if (JVMCICounterSize > 0) {
 515     resize_counters(0, (int) JVMCICounterSize);
 516   }
 517 #endif // INCLUDE_JVMCI
 518 
 519   // Setup safepoint state info for this thread
 520   ThreadSafepointState::create(this);
 521 
 522   SafepointMechanism::initialize_header(this);
 523 
 524   set_requires_cross_modify_fence(false);
 525 
 526   pd_initialize();
 527   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
 528 }
 529 
 530 JavaThread::JavaThread(bool is_attaching_via_jni) : JavaThread() {
 531   if (is_attaching_via_jni) {
 532     _jni_attach_state = _attaching_via_jni;
 533   }
 534 }
 535 
 536 
 537 // interrupt support
 538 
 539 void JavaThread::interrupt() {
 540   // All callers should have 'this' thread protected by a
 541   // ThreadsListHandle so that it cannot terminate and deallocate
 542   // itself.
 543   debug_only(check_for_dangling_thread_pointer(this);)
 544 
 545   // For Windows _interrupt_event
 546   WINDOWS_ONLY(osthread()->set_interrupted(true);)
 547 
 548   // For Thread.sleep
 549   _SleepEvent->unpark();
 550 
 551   // For JSR166 LockSupport.park
 552   parker()->unpark();
 553 
 554   // For ObjectMonitor and JvmtiRawMonitor
 555   _ParkEvent->unpark();
 556 }
 557 
 558 bool JavaThread::is_interrupted(bool clear_interrupted) {
 559   debug_only(check_for_dangling_thread_pointer(this);)
 560 
 561   if (_threadObj.peek() == nullptr) {
 562     // If there is no j.l.Thread then it is impossible to have
 563     // been interrupted. We can find null during VM initialization
 564     // or when a JNI thread is still in the process of attaching.
 565     // In such cases this must be the current thread.
 566     assert(this == Thread::current(), "invariant");
 567     return false;
 568   }
 569 
 570   bool interrupted = java_lang_Thread::interrupted(threadObj());
 571 
 572   // NOTE that since there is no "lock" around the interrupt and
 573   // is_interrupted operations, there is the possibility that the
 574   // interrupted flag will be "false" but that the
 575   // low-level events will be in the signaled state. This is
 576   // intentional. The effect of this is that Object.wait() and
 577   // LockSupport.park() will appear to have a spurious wakeup, which
 578   // is allowed and not harmful, and the possibility is so rare that
 579   // it is not worth the added complexity to add yet another lock.
 580   // For the sleep event an explicit reset is performed on entry
 581   // to JavaThread::sleep, so there is no early return. It has also been
 582   // recommended not to put the interrupted flag into the "event"
 583   // structure because it hides the issue.
 584   // Also, because there is no lock, we must only clear the interrupt
 585   // state if we are going to report that we were interrupted; otherwise
 586   // an interrupt that happens just after we read the field would be lost.
 587   if (interrupted && clear_interrupted) {
 588     assert(this == Thread::current(), "only the current thread can clear");
 589     java_lang_Thread::set_interrupted(threadObj(), false);
 590     WINDOWS_ONLY(osthread()->set_interrupted(false);)
 591   }
 592   return interrupted;
 593 }
 594 
 595 // This is only for use by JVMTI RawMonitorWait. It emulates the actions of
 596 // the Java code in Object::wait which are not present in RawMonitorWait.
 597 bool JavaThread::get_and_clear_interrupted() {
 598   if (!is_interrupted(false)) {
 599     return false;
 600   }
 601   oop thread_oop = vthread_or_thread();
 602   bool is_virtual = java_lang_VirtualThread::is_instance(thread_oop);
 603 
 604   if (!is_virtual) {
 605     return is_interrupted(true);
 606   }
 607   // Virtual thread: clear interrupt status for both virtual and
 608   // carrier threads under the interruptLock protection.
 609   JavaThread* current = JavaThread::current();
 610   HandleMark hm(current);
 611   Handle thread_h(current, thread_oop);
 612   ObjectLocker lock(Handle(current, java_lang_Thread::interrupt_lock(thread_h())), current);
 613 
 614   // re-check the interrupt status under the interruptLock protection
 615   bool interrupted = java_lang_Thread::interrupted(thread_h());
 616 
 617   if (interrupted) {
 618     assert(this == Thread::current(), "only the current thread can clear");
 619     java_lang_Thread::set_interrupted(thread_h(), false);  // clear for virtual
 620     java_lang_Thread::set_interrupted(threadObj(), false); // clear for carrier
 621     WINDOWS_ONLY(osthread()->set_interrupted(false);)
 622   }
 623   return interrupted;
 624 }
 625 
 626 void JavaThread::block_if_vm_exited() {
 627   if (_terminated == _vm_exited) {
 628     // _vm_exited is set at safepoint, and Threads_lock is never released
 629     // so we will block here forever.
 630     // Here we can be doing a jump from a safe state to an unsafe state without
 631     // proper transition, but it happens after the final safepoint has begun so
 632     // this jump won't cause any safepoint problems.
 633     set_thread_state(_thread_in_vm);
 634     Threads_lock->lock();
 635     ShouldNotReachHere();
 636   }
 637 }
 638 
 639 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : JavaThread() {
 640   _jni_attach_state = _not_attaching_via_jni;
 641   set_entry_point(entry_point);
 642   // Create the native thread itself.
 643   // %note runtime_23
 644   os::ThreadType thr_type = os::java_thread;
 645   thr_type = entry_point == &CompilerThread::thread_entry ? os::compiler_thread :
 646                                                             os::java_thread;
 647   os::create_thread(this, thr_type, stack_sz);
 648   // The _osthread may be null here because we ran out of memory (too many threads active).
 649   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
 650   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
 651   // the exception consists of creating the exception object & initializing it, initialization
 652   // will leave the VM via a JavaCall and then all locks must be unlocked).
 653   //
 654   // The thread is still suspended when we reach here. Thread must be explicit started
 655   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
 656   // by calling Threads:add. The reason why this is not done here, is because the thread
 657   // object must be fully initialized (take a look at JVM_Start)
 658 }
 659 
 660 JavaThread::~JavaThread() {
 661 
 662   // Enqueue OopHandles for release by the service thread.
 663   add_oop_handles_for_release();
 664 
 665   // Return the sleep event to the free list
 666   ParkEvent::Release(_SleepEvent);
 667   _SleepEvent = nullptr;
 668 
 669   // Free any remaining  previous UnrollBlock
 670   vframeArray* old_array = vframe_array_last();
 671 
 672   if (old_array != nullptr) {
 673     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
 674     old_array->set_unroll_block(nullptr);
 675     delete old_info;
 676     delete old_array;
 677   }
 678 
 679   JvmtiDeferredUpdates* updates = deferred_updates();
 680   if (updates != nullptr) {
 681     // This can only happen if thread is destroyed before deoptimization occurs.
 682     assert(updates->count() > 0, "Updates holder not deleted");
 683     // free deferred updates.
 684     delete updates;
 685     set_deferred_updates(nullptr);
 686   }
 687 
 688   // All Java related clean up happens in exit
 689   ThreadSafepointState::destroy(this);
 690   if (_thread_stat != nullptr) delete _thread_stat;
 691 
 692 #if INCLUDE_JVMCI
 693   if (JVMCICounterSize > 0) {
 694     FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
 695   }
 696 #endif // INCLUDE_JVMCI
 697 }
 698 
 699 
 700 // First JavaThread specific code executed by a new Java thread.
 701 void JavaThread::pre_run() {
 702   // empty - see comments in run()
 703 }
 704 
 705 // The main routine called by a new Java thread. This isn't overridden
 706 // by subclasses, instead different subclasses define a different "entry_point"
 707 // which defines the actual logic for that kind of thread.
 708 void JavaThread::run() {
 709   // initialize thread-local alloc buffer related fields
 710   initialize_tlab();
 711 
 712   _stack_overflow_state.create_stack_guard_pages();
 713 
 714   cache_global_variables();
 715 
 716   // Thread is now sufficiently initialized to be handled by the safepoint code as being
 717   // in the VM. Change thread state from _thread_new to _thread_in_vm
 718   assert(this->thread_state() == _thread_new, "wrong thread state");
 719   set_thread_state(_thread_in_vm);
 720 
 721   // Before a thread is on the threads list it is always safe, so after leaving the
 722   // _thread_new we should emit a instruction barrier. The distance to modified code
 723   // from here is probably far enough, but this is consistent and safe.
 724   OrderAccess::cross_modify_fence();
 725 
 726   assert(JavaThread::current() == this, "sanity check");
 727   assert(!Thread::current()->owns_locks(), "sanity check");
 728 
 729   DTRACE_THREAD_PROBE(start, this);
 730 
 731   // This operation might block. We call that after all safepoint checks for a new thread has
 732   // been completed.
 733   set_active_handles(JNIHandleBlock::allocate_block());
 734 
 735   if (JvmtiExport::should_post_thread_life()) {
 736     JvmtiExport::post_thread_start(this);
 737 
 738   }
 739 
 740   if (AlwaysPreTouchStacks) {
 741     pretouch_stack();
 742   }
 743 
 744   // We call another function to do the rest so we are sure that the stack addresses used
 745   // from there will be lower than the stack base just computed.
 746   thread_main_inner();
 747 }
 748 
 749 void JavaThread::thread_main_inner() {
 750   assert(JavaThread::current() == this, "sanity check");
 751   assert(_threadObj.peek() != nullptr, "just checking");
 752 
 753   // Execute thread entry point unless this thread has a pending exception.
 754   // Note: Due to JVMTI StopThread we can have pending exceptions already!
 755   if (!this->has_pending_exception()) {
 756     {
 757       ResourceMark rm(this);
 758       this->set_native_thread_name(this->name());
 759     }
 760     HandleMark hm(this);
 761     this->entry_point()(this, this);
 762   }
 763 
 764   DTRACE_THREAD_PROBE(stop, this);
 765 
 766   // Cleanup is handled in post_run()
 767 }
 768 
 769 // Shared teardown for all JavaThreads
 770 void JavaThread::post_run() {
 771   this->exit(false);
 772   this->unregister_thread_stack_with_NMT();
 773   // Defer deletion to here to ensure 'this' is still referenceable in call_run
 774   // for any shared tear-down.
 775   this->smr_delete();
 776 }
 777 
 778 static void ensure_join(JavaThread* thread) {
 779   // We do not need to grab the Threads_lock, since we are operating on ourself.
 780   Handle threadObj(thread, thread->threadObj());
 781   assert(threadObj.not_null(), "java thread object must exist");
 782   ObjectLocker lock(threadObj, thread);
 783   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
 784   java_lang_Thread::set_thread_status(threadObj(), JavaThreadStatus::TERMINATED);
 785   // Clear the native thread instance - this makes isAlive return false and allows the join()
 786   // to complete once we've done the notify_all below. Needs a release() to obey Java Memory Model
 787   // requirements.
 788   assert(java_lang_Thread::thread(threadObj()) == thread, "must be alive");
 789   java_lang_Thread::release_set_thread(threadObj(), nullptr);
 790   lock.notify_all(thread);
 791   // Ignore pending exception, since we are exiting anyway
 792   thread->clear_pending_exception();
 793 }
 794 
 795 static bool is_daemon(oop threadObj) {
 796   return (threadObj != nullptr && java_lang_Thread::is_daemon(threadObj));
 797 }
 798 
 799 // For any new cleanup additions, please check to see if they need to be applied to
 800 // cleanup_failed_attach_current_thread as well.
 801 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
 802   assert(this == JavaThread::current(), "thread consistency check");
 803   assert(!is_exiting(), "should not be exiting or terminated already");
 804 
 805   elapsedTimer _timer_exit_phase1;
 806   elapsedTimer _timer_exit_phase2;
 807   elapsedTimer _timer_exit_phase3;
 808   elapsedTimer _timer_exit_phase4;
 809 
 810   om_clear_monitor_cache();
 811 
 812   if (log_is_enabled(Debug, os, thread, timer)) {
 813     _timer_exit_phase1.start();
 814   }
 815 
 816   HandleMark hm(this);
 817   Handle uncaught_exception(this, this->pending_exception());
 818   this->clear_pending_exception();
 819   Handle threadObj(this, this->threadObj());
 820   assert(threadObj.not_null(), "Java thread object should be created");
 821 
 822   if (!destroy_vm) {
 823     if (uncaught_exception.not_null()) {
 824       EXCEPTION_MARK;
 825       // Call method Thread.dispatchUncaughtException().
 826       Klass* thread_klass = vmClasses::Thread_klass();
 827       JavaValue result(T_VOID);
 828       JavaCalls::call_virtual(&result,
 829                               threadObj, thread_klass,
 830                               vmSymbols::dispatchUncaughtException_name(),
 831                               vmSymbols::throwable_void_signature(),
 832                               uncaught_exception,
 833                               THREAD);
 834       if (HAS_PENDING_EXCEPTION) {
 835         ResourceMark rm(this);
 836         jio_fprintf(defaultStream::error_stream(),
 837                     "\nException: %s thrown from the UncaughtExceptionHandler"
 838                     " in thread \"%s\"\n",
 839                     pending_exception()->klass()->external_name(),
 840                     name());
 841         CLEAR_PENDING_EXCEPTION;
 842       }
 843     }
 844 
 845     if (!is_Compiler_thread()) {
 846       // We have finished executing user-defined Java code and now have to do the
 847       // implementation specific clean-up by calling Thread.exit(). We prevent any
 848       // asynchronous exceptions from being delivered while in Thread.exit()
 849       // to ensure the clean-up is not corrupted.
 850       NoAsyncExceptionDeliveryMark _no_async(this);
 851 
 852       EXCEPTION_MARK;
 853       JavaValue result(T_VOID);
 854       Klass* thread_klass = vmClasses::Thread_klass();
 855       JavaCalls::call_virtual(&result,
 856                               threadObj, thread_klass,
 857                               vmSymbols::exit_method_name(),
 858                               vmSymbols::void_method_signature(),
 859                               THREAD);
 860       CLEAR_PENDING_EXCEPTION;
 861     }
 862 
 863     // notify JVMTI
 864     if (JvmtiExport::should_post_thread_life()) {
 865       JvmtiExport::post_thread_end(this);
 866     }
 867   } else {
 868     // before_exit() has already posted JVMTI THREAD_END events
 869   }
 870 
 871   // Cleanup any pending async exception now since we cannot access oops after
 872   // BarrierSet::barrier_set()->on_thread_detach() has been executed.
 873   if (has_async_exception_condition()) {
 874     handshake_state()->clean_async_exception_operation();
 875   }
 876 
 877   // The careful dance between thread suspension and exit is handled here.
 878   // Since we are in thread_in_vm state and suspension is done with handshakes,
 879   // we can just put in the exiting state and it will be correctly handled.
 880   // Also, no more async exceptions will be added to the queue after this point.
 881   set_terminated(_thread_exiting);
 882   ThreadService::current_thread_exiting(this, is_daemon(threadObj()));
 883 
 884   if (log_is_enabled(Debug, os, thread, timer)) {
 885     _timer_exit_phase1.stop();
 886     _timer_exit_phase2.start();
 887   }
 888 
 889   // Capture daemon status before the thread is marked as terminated.
 890   bool daemon = is_daemon(threadObj());
 891 
 892   // Notify waiters on thread object. This has to be done after exit() is called
 893   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
 894   // group should have the destroyed bit set before waiters are notified).
 895   ensure_join(this);
 896   assert(!this->has_pending_exception(), "ensure_join should have cleared");
 897 
 898   if (log_is_enabled(Debug, os, thread, timer)) {
 899     _timer_exit_phase2.stop();
 900     _timer_exit_phase3.start();
 901   }
 902   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
 903   // held by this thread must be released. The spec does not distinguish
 904   // between JNI-acquired and regular Java monitors. We can only see
 905   // regular Java monitors here if monitor enter-exit matching is broken.
 906   //
 907   // ensure_join() ignores IllegalThreadStateExceptions, and so does
 908   // ObjectSynchronizer::release_monitors_owned_by_thread().
 909   if (exit_type == jni_detach) {
 910     // Sanity check even though JNI DetachCurrentThread() would have
 911     // returned JNI_ERR if there was a Java frame. JavaThread exit
 912     // should be done executing Java code by the time we get here.
 913     assert(!this->has_last_Java_frame(),
 914            "should not have a Java frame when detaching or exiting");
 915     ObjectSynchronizer::release_monitors_owned_by_thread(this);
 916     assert(!this->has_pending_exception(), "release_monitors should have cleared");
 917     // Check for monitor counts being out of sync.
 918     assert(held_monitor_count() == jni_monitor_count(),
 919            "held monitor count should be equal to jni: " INTX_FORMAT " != " INTX_FORMAT,
 920            held_monitor_count(), jni_monitor_count());
 921     // All in-use monitors, including JNI-locked ones, should have been released above.
 922     assert(held_monitor_count() == 0, "Failed to unlock " INTX_FORMAT " object monitors",
 923            held_monitor_count());
 924   } else {
 925     // Check for monitor counts being out of sync.
 926     assert(held_monitor_count() == jni_monitor_count(),
 927            "held monitor count should be equal to jni: " INTX_FORMAT " != " INTX_FORMAT,
 928            held_monitor_count(), jni_monitor_count());
 929     // It is possible that a terminating thread failed to unlock monitors it locked
 930     // via JNI so we don't assert the count is zero.
 931   }
 932 
 933   if (CheckJNICalls && jni_monitor_count() > 0) {
 934     // We would like a fatal here, but due to we never checked this before there
 935     // is a lot of tests which breaks, even with an error log.
 936     log_debug(jni)("JavaThread %s (tid: " UINTX_FORMAT ") with Objects still locked by JNI MonitorEnter.",
 937                    exit_type == JavaThread::normal_exit ? "exiting" : "detaching", os::current_thread_id());
 938   }
 939 
 940   // These things needs to be done while we are still a Java Thread. Make sure that thread
 941   // is in a consistent state, in case GC happens
 942   JFR_ONLY(Jfr::on_thread_exit(this);)
 943 
 944   if (active_handles() != nullptr) {
 945     JNIHandleBlock* block = active_handles();
 946     set_active_handles(nullptr);
 947     JNIHandleBlock::release_block(block);
 948   }
 949 
 950   if (free_handle_block() != nullptr) {
 951     JNIHandleBlock* block = free_handle_block();
 952     set_free_handle_block(nullptr);
 953     JNIHandleBlock::release_block(block);
 954   }
 955 
 956   // These have to be removed while this is still a valid thread.
 957   _stack_overflow_state.remove_stack_guard_pages();
 958 
 959   if (UseTLAB) {
 960     tlab().retire();
 961   }
 962 
 963   if (JvmtiEnv::environments_might_exist()) {
 964     JvmtiExport::cleanup_thread(this);
 965   }
 966 
 967   // We need to cache the thread name for logging purposes below as once
 968   // we have called on_thread_detach this thread must not access any oops.
 969   char* thread_name = nullptr;
 970   if (log_is_enabled(Debug, os, thread, timer)) {
 971     ResourceMark rm(this);
 972     thread_name = os::strdup(name());
 973   }
 974 
 975   if (log_is_enabled(Info, os, thread)) {
 976     ResourceMark rm(this);
 977     log_info(os, thread)("JavaThread %s (name: \"%s\", tid: " UINTX_FORMAT ").",
 978                          exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
 979                          name(), os::current_thread_id());
 980   }
 981 
 982   if (log_is_enabled(Debug, os, thread, timer)) {
 983     _timer_exit_phase3.stop();
 984     _timer_exit_phase4.start();
 985   }
 986 
 987 #if INCLUDE_JVMCI
 988   if (JVMCICounterSize > 0) {
 989     if (jvmci_counters_include(this)) {
 990       for (int i = 0; i < JVMCICounterSize; i++) {
 991         _jvmci_old_thread_counters[i] += _jvmci_counters[i];
 992       }
 993     }
 994   }
 995 #endif // INCLUDE_JVMCI
 996 
 997   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread.
 998   // We call BarrierSet::barrier_set()->on_thread_detach() here so no touching of oops after this point.
 999   Threads::remove(this, daemon);
1000 
1001   if (log_is_enabled(Debug, os, thread, timer)) {
1002     _timer_exit_phase4.stop();
1003     log_debug(os, thread, timer)("name='%s'"
1004                                  ", exit-phase1=" JLONG_FORMAT
1005                                  ", exit-phase2=" JLONG_FORMAT
1006                                  ", exit-phase3=" JLONG_FORMAT
1007                                  ", exit-phase4=" JLONG_FORMAT,
1008                                  thread_name,
1009                                  _timer_exit_phase1.milliseconds(),
1010                                  _timer_exit_phase2.milliseconds(),
1011                                  _timer_exit_phase3.milliseconds(),
1012                                  _timer_exit_phase4.milliseconds());
1013     os::free(thread_name);
1014   }
1015 }
1016 
1017 void JavaThread::cleanup_failed_attach_current_thread(bool is_daemon) {
1018   if (active_handles() != nullptr) {
1019     JNIHandleBlock* block = active_handles();
1020     set_active_handles(nullptr);
1021     JNIHandleBlock::release_block(block);
1022   }
1023 
1024   if (free_handle_block() != nullptr) {
1025     JNIHandleBlock* block = free_handle_block();
1026     set_free_handle_block(nullptr);
1027     JNIHandleBlock::release_block(block);
1028   }
1029 
1030   // These have to be removed while this is still a valid thread.
1031   _stack_overflow_state.remove_stack_guard_pages();
1032 
1033   if (UseTLAB) {
1034     tlab().retire();
1035   }
1036 
1037   Threads::remove(this, is_daemon);
1038   this->smr_delete();
1039 }
1040 
1041 JavaThread* JavaThread::active() {
1042   Thread* thread = Thread::current();
1043   if (thread->is_Java_thread()) {
1044     return JavaThread::cast(thread);
1045   } else {
1046     assert(thread->is_VM_thread(), "this must be a vm thread");
1047     VM_Operation* op = ((VMThread*) thread)->vm_operation();
1048     JavaThread *ret = op == nullptr ? nullptr : JavaThread::cast(op->calling_thread());
1049     return ret;
1050   }
1051 }
1052 
1053 bool JavaThread::is_lock_owned(address adr) const {
1054   assert(LockingMode != LM_LIGHTWEIGHT, "should not be called with new lightweight locking");
1055   return is_in_full_stack(adr);
1056 }
1057 
1058 oop JavaThread::exception_oop() const {
1059   return Atomic::load(&_exception_oop);
1060 }
1061 
1062 void JavaThread::set_exception_oop(oop o) {
1063   Atomic::store(&_exception_oop, o);
1064 }
1065 
1066 void JavaThread::handle_special_runtime_exit_condition() {
1067   if (is_obj_deopt_suspend()) {
1068     frame_anchor()->make_walkable();
1069     wait_for_object_deoptimization();
1070   }
1071   JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
1072 }
1073 
1074 
1075 // Asynchronous exceptions support
1076 //
1077 void JavaThread::handle_async_exception(oop java_throwable) {
1078   assert(java_throwable != nullptr, "should have an _async_exception to throw");
1079   assert(!is_at_poll_safepoint(), "should have never called this method");
1080 
1081   if (has_last_Java_frame()) {
1082     frame f = last_frame();
1083     if (f.is_runtime_frame()) {
1084       // If the topmost frame is a runtime stub, then we are calling into
1085       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
1086       // must deoptimize the caller before continuing, as the compiled exception
1087       // handler table may not be valid.
1088       RegisterMap reg_map(this,
1089                           RegisterMap::UpdateMap::skip,
1090                           RegisterMap::ProcessFrames::include,
1091                           RegisterMap::WalkContinuation::skip);
1092       frame compiled_frame = f.sender(&reg_map);
1093       if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
1094         Deoptimization::deoptimize(this, compiled_frame);
1095       }
1096     }
1097   }
1098 
1099   // We cannot call Exceptions::_throw(...) here because we cannot block
1100   set_pending_exception(java_throwable, __FILE__, __LINE__);
1101 
1102   clear_scopedValueBindings();
1103 
1104   LogTarget(Info, exceptions) lt;
1105   if (lt.is_enabled()) {
1106     ResourceMark rm;
1107     LogStream ls(lt);
1108     ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
1109     if (has_last_Java_frame()) {
1110       frame f = last_frame();
1111       ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
1112     }
1113     ls.print_cr(" of type: %s", java_throwable->klass()->external_name());
1114   }
1115 }
1116 
1117 void JavaThread::install_async_exception(AsyncExceptionHandshake* aeh) {
1118   // Do not throw asynchronous exceptions against the compiler thread
1119   // or if the thread is already exiting.
1120   if (!can_call_java() || is_exiting()) {
1121     delete aeh;
1122     return;
1123   }
1124 
1125   oop exception = aeh->exception();
1126   Handshake::execute(aeh, this);  // Install asynchronous handshake
1127 
1128   ResourceMark rm;
1129   if (log_is_enabled(Info, exceptions)) {
1130     log_info(exceptions)("Pending Async. exception installed of type: %s",
1131                          InstanceKlass::cast(exception->klass())->external_name());
1132   }
1133   // for AbortVMOnException flag
1134   Exceptions::debug_check_abort(exception->klass()->external_name());
1135 
1136   oop vt_oop = vthread();
1137   if (vt_oop == nullptr || !vt_oop->is_a(vmClasses::BaseVirtualThread_klass())) {
1138     // Interrupt thread so it will wake up from a potential wait()/sleep()/park()
1139     java_lang_Thread::set_interrupted(threadObj(), true);
1140     this->interrupt();
1141   }
1142 }
1143 
1144 class InstallAsyncExceptionHandshake : public HandshakeClosure {
1145   AsyncExceptionHandshake* _aeh;
1146 public:
1147   InstallAsyncExceptionHandshake(AsyncExceptionHandshake* aeh) :
1148     HandshakeClosure("InstallAsyncException"), _aeh(aeh) {}
1149   ~InstallAsyncExceptionHandshake() {
1150     // If InstallAsyncExceptionHandshake was never executed we need to clean up _aeh.
1151     delete _aeh;
1152   }
1153   void do_thread(Thread* thr) {
1154     JavaThread* target = JavaThread::cast(thr);
1155     target->install_async_exception(_aeh);
1156     _aeh = nullptr;
1157   }
1158 };
1159 
1160 void JavaThread::send_async_exception(JavaThread* target, oop java_throwable) {
1161   OopHandle e(Universe::vm_global(), java_throwable);
1162   InstallAsyncExceptionHandshake iaeh(new AsyncExceptionHandshake(e));
1163   Handshake::execute(&iaeh, target);
1164 }
1165 
1166 #if INCLUDE_JVMTI
1167 void JavaThread::set_is_in_VTMS_transition(bool val) {
1168   _is_in_VTMS_transition = val;
1169 }
1170 
1171 #ifdef ASSERT
1172 void JavaThread::set_is_VTMS_transition_disabler(bool val) {
1173   _is_VTMS_transition_disabler = val;
1174 }
1175 #endif
1176 #endif
1177 
1178 // External suspension mechanism.
1179 //
1180 // Guarantees on return (for a valid target thread):
1181 //   - Target thread will not execute any new bytecode.
1182 //   - Target thread will not enter any new monitors.
1183 //
1184 bool JavaThread::java_suspend() {
1185 #if INCLUDE_JVMTI
1186   // Suspending a JavaThread in VTMS transition or disabling VTMS transitions can cause deadlocks.
1187   assert(!is_in_VTMS_transition(), "no suspend allowed in VTMS transition");
1188   assert(!is_VTMS_transition_disabler(), "no suspend allowed for VTMS transition disablers");
1189 #endif
1190 
1191   guarantee(Thread::is_JavaThread_protected(/* target */ this),
1192             "target JavaThread is not protected in calling context.");
1193   return this->handshake_state()->suspend();
1194 }
1195 
1196 bool JavaThread::java_resume() {
1197   guarantee(Thread::is_JavaThread_protected_by_TLH(/* target */ this),
1198             "missing ThreadsListHandle in calling context.");
1199   return this->handshake_state()->resume();
1200 }
1201 
1202 // Wait for another thread to perform object reallocation and relocking on behalf of
1203 // this thread. The current thread is required to change to _thread_blocked in order
1204 // to be seen to be safepoint/handshake safe whilst suspended and only after becoming
1205 // handshake safe, the other thread can complete the handshake used to synchronize
1206 // with this thread and then perform the reallocation and relocking.
1207 // See EscapeBarrier::sync_and_suspend_*()
1208 
1209 void JavaThread::wait_for_object_deoptimization() {
1210   assert(!has_last_Java_frame() || frame_anchor()->walkable(), "should have walkable stack");
1211   assert(this == Thread::current(), "invariant");
1212 
1213   bool spin_wait = os::is_MP();
1214   do {
1215     ThreadBlockInVM tbivm(this, true /* allow_suspend */);
1216     // Wait for object deoptimization if requested.
1217     if (spin_wait) {
1218       // A single deoptimization is typically very short. Microbenchmarks
1219       // showed 5% better performance when spinning.
1220       const uint spin_limit = 10 * SpinYield::default_spin_limit;
1221       SpinYield spin(spin_limit);
1222       for (uint i = 0; is_obj_deopt_suspend() && i < spin_limit; i++) {
1223         spin.wait();
1224       }
1225       // Spin just once
1226       spin_wait = false;
1227     } else {
1228       MonitorLocker ml(this, EscapeBarrier_lock, Monitor::_no_safepoint_check_flag);
1229       if (is_obj_deopt_suspend()) {
1230         ml.wait();
1231       }
1232     }
1233     // A handshake for obj. deoptimization suspend could have been processed so
1234     // we must check after processing.
1235   } while (is_obj_deopt_suspend());
1236 }
1237 
1238 #ifdef ASSERT
1239 // Verify the JavaThread has not yet been published in the Threads::list, and
1240 // hence doesn't need protection from concurrent access at this stage.
1241 void JavaThread::verify_not_published() {
1242   // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
1243   // since an unpublished JavaThread doesn't participate in the
1244   // Thread-SMR protocol for keeping a ThreadsList alive.
1245   assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
1246 }
1247 #endif
1248 
1249 // Slow path when the native==>Java barriers detect a safepoint/handshake is
1250 // pending, when _suspend_flags is non-zero or when we need to process a stack
1251 // watermark. Also check for pending async exceptions (except unsafe access error).
1252 // Note only the native==>Java barriers can call this function when thread state
1253 // is _thread_in_native_trans.
1254 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
1255   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
1256   assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "Unwalkable stack in native->Java transition");
1257 
1258   thread->set_thread_state(_thread_in_vm);
1259 
1260   // Enable WXWrite: called directly from interpreter native wrapper.
1261   MACOS_AARCH64_ONLY(ThreadWXEnable wx(WXWrite, thread));
1262 
1263   SafepointMechanism::process_if_requested_with_exit_check(thread, true /* check asyncs */);
1264 
1265   // After returning from native, it could be that the stack frames are not
1266   // yet safe to use. We catch such situations in the subsequent stack watermark
1267   // barrier, which will trap unsafe stack frames.
1268   StackWatermarkSet::before_unwind(thread);
1269 }
1270 
1271 #ifndef PRODUCT
1272 // Deoptimization
1273 // Function for testing deoptimization
1274 void JavaThread::deoptimize() {
1275   StackFrameStream fst(this, false /* update */, true /* process_frames */);
1276   bool deopt = false;           // Dump stack only if a deopt actually happens.
1277   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
1278   // Iterate over all frames in the thread and deoptimize
1279   for (; !fst.is_done(); fst.next()) {
1280     if (fst.current()->can_be_deoptimized()) {
1281 
1282       if (only_at) {
1283         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
1284         // consists of comma or carriage return separated numbers so
1285         // search for the current bci in that string.
1286         address    pc = fst.current()->pc();
1287         nmethod*   nm = fst.current()->cb()->as_nmethod();
1288         ScopeDesc* sd = nm->scope_desc_at(pc);
1289         char buffer[8];
1290         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
1291         size_t len = strlen(buffer);
1292         const char * found = strstr(DeoptimizeOnlyAt, buffer);
1293         while (found != nullptr) {
1294           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
1295               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
1296             // Check that the bci found is bracketed by terminators.
1297             break;
1298           }
1299           found = strstr(found + 1, buffer);
1300         }
1301         if (!found) {
1302           continue;
1303         }
1304       }
1305 
1306       if (DebugDeoptimization && !deopt) {
1307         deopt = true; // One-time only print before deopt
1308         tty->print_cr("[BEFORE Deoptimization]");
1309         trace_frames();
1310         trace_stack();
1311       }
1312       Deoptimization::deoptimize(this, *fst.current());
1313     }
1314   }
1315 
1316   if (DebugDeoptimization && deopt) {
1317     tty->print_cr("[AFTER Deoptimization]");
1318     trace_frames();
1319   }
1320 }
1321 
1322 
1323 // Make zombies
1324 void JavaThread::make_zombies() {
1325   for (StackFrameStream fst(this, true /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
1326     if (fst.current()->can_be_deoptimized()) {
1327       // it is a Java nmethod
1328       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
1329       assert(nm != nullptr, "did not find nmethod");
1330       nm->make_not_entrant();
1331     }
1332   }
1333 }
1334 #endif // PRODUCT
1335 
1336 
1337 void JavaThread::deoptimize_marked_methods() {
1338   if (!has_last_Java_frame()) return;
1339   StackFrameStream fst(this, false /* update */, true /* process_frames */);
1340   for (; !fst.is_done(); fst.next()) {
1341     if (fst.current()->should_be_deoptimized()) {
1342       Deoptimization::deoptimize(this, *fst.current());
1343     }
1344   }
1345 }
1346 
1347 #ifdef ASSERT
1348 void JavaThread::verify_frame_info() {
1349   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
1350          (has_last_Java_frame() && java_call_counter() > 0),
1351          "unexpected frame info: has_last_frame=%s, java_call_counter=%d",
1352          has_last_Java_frame() ? "true" : "false", java_call_counter());
1353 }
1354 #endif
1355 
1356 // Push on a new block of JNI handles.
1357 void JavaThread::push_jni_handle_block() {
1358   // Allocate a new block for JNI handles.
1359   // Inlined code from jni_PushLocalFrame()
1360   JNIHandleBlock* old_handles = active_handles();
1361   JNIHandleBlock* new_handles = JNIHandleBlock::allocate_block(this);
1362   assert(old_handles != nullptr && new_handles != nullptr, "should not be null");
1363   new_handles->set_pop_frame_link(old_handles);  // make sure java handles get gc'd.
1364   set_active_handles(new_handles);
1365 }
1366 
1367 // Pop off the current block of JNI handles.
1368 void JavaThread::pop_jni_handle_block() {
1369   // Release our JNI handle block
1370   JNIHandleBlock* old_handles = active_handles();
1371   JNIHandleBlock* new_handles = old_handles->pop_frame_link();
1372   assert(new_handles != nullptr, "should never set active handles to null");
1373   set_active_handles(new_handles);
1374   old_handles->set_pop_frame_link(nullptr);
1375   JNIHandleBlock::release_block(old_handles, this);
1376 }
1377 
1378 void JavaThread::oops_do_no_frames(OopClosure* f, NMethodClosure* cf) {
1379   // Verify that the deferred card marks have been flushed.
1380   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
1381 
1382   // Traverse the GCHandles
1383   Thread::oops_do_no_frames(f, cf);
1384 
1385   if (active_handles() != nullptr) {
1386     active_handles()->oops_do(f);
1387   }
1388 
1389   DEBUG_ONLY(verify_frame_info();)
1390 
1391   assert(vframe_array_head() == nullptr, "deopt in progress at a safepoint!");
1392   // If we have deferred set_locals there might be oops waiting to be
1393   // written
1394   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = JvmtiDeferredUpdates::deferred_locals(this);
1395   if (list != nullptr) {
1396     for (int i = 0; i < list->length(); i++) {
1397       list->at(i)->oops_do(f);
1398     }
1399   }
1400 
1401   // Traverse instance variables at the end since the GC may be moving things
1402   // around using this function
1403   f->do_oop((oop*) &_vm_result);
1404   f->do_oop((oop*) &_exception_oop);
1405 #if INCLUDE_JVMCI
1406   f->do_oop((oop*) &_jvmci_reserved_oop0);
1407 
1408   if (_live_nmethod != nullptr && cf != nullptr) {
1409     cf->do_nmethod(_live_nmethod);
1410   }
1411 #endif
1412 
1413   if (jvmti_thread_state() != nullptr) {
1414     jvmti_thread_state()->oops_do(f, cf);
1415   }
1416 
1417   // The continuation oops are really on the stack. But there is typically at most
1418   // one of those per thread, so we handle them here in the oops_do_no_frames part
1419   // so that we don't have to sprinkle as many stack watermark checks where these
1420   // oops are used. We just need to make sure the thread has started processing.
1421   ContinuationEntry* entry = _cont_entry;
1422   while (entry != nullptr) {
1423     f->do_oop((oop*)entry->cont_addr());
1424     f->do_oop((oop*)entry->chunk_addr());
1425     entry = entry->parent();
1426   }
1427 
1428   if (LockingMode == LM_LIGHTWEIGHT) {
1429     lock_stack().oops_do(f);
1430   }
1431 }
1432 
1433 void JavaThread::oops_do_frames(OopClosure* f, NMethodClosure* cf) {
1434   if (!has_last_Java_frame()) {
1435     return;
1436   }
1437   // Finish any pending lazy GC activity for the frames
1438   StackWatermarkSet::finish_processing(this, nullptr /* context */, StackWatermarkKind::gc);
1439   // Traverse the execution stack
1440   for (StackFrameStream fst(this, true /* update */, false /* process_frames */); !fst.is_done(); fst.next()) {
1441     fst.current()->oops_do(f, cf, fst.register_map());
1442   }
1443 }
1444 
1445 #ifdef ASSERT
1446 void JavaThread::verify_states_for_handshake() {
1447   // This checks that the thread has a correct frame state during a handshake.
1448   verify_frame_info();
1449 }
1450 #endif
1451 
1452 void JavaThread::nmethods_do(NMethodClosure* cf) {
1453   DEBUG_ONLY(verify_frame_info();)
1454   MACOS_AARCH64_ONLY(ThreadWXEnable wx(WXWrite, Thread::current());)
1455 
1456   if (has_last_Java_frame()) {
1457     // Traverse the execution stack
1458     for (StackFrameStream fst(this, true /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
1459       fst.current()->nmethod_do(cf);
1460     }
1461   }
1462 
1463   if (jvmti_thread_state() != nullptr) {
1464     jvmti_thread_state()->nmethods_do(cf);
1465   }
1466 
1467 #if INCLUDE_JVMCI
1468   if (_live_nmethod != nullptr) {
1469     cf->do_nmethod(_live_nmethod);
1470   }
1471 #endif
1472 }
1473 
1474 void JavaThread::metadata_do(MetadataClosure* f) {
1475   if (has_last_Java_frame()) {
1476     // Traverse the execution stack to call f() on the methods in the stack
1477     for (StackFrameStream fst(this, true /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
1478       fst.current()->metadata_do(f);
1479     }
1480   } else if (is_Compiler_thread()) {
1481     // need to walk ciMetadata in current compile tasks to keep alive.
1482     CompilerThread* ct = (CompilerThread*)this;
1483     if (ct->env() != nullptr) {
1484       ct->env()->metadata_do(f);
1485     }
1486     CompileTask* task = ct->task();
1487     if (task != nullptr) {
1488       task->metadata_do(f);
1489     }
1490   }
1491 }
1492 
1493 // Printing
1494 static const char* _get_thread_state_name(JavaThreadState _thread_state) {
1495   switch (_thread_state) {
1496   case _thread_uninitialized:     return "_thread_uninitialized";
1497   case _thread_new:               return "_thread_new";
1498   case _thread_new_trans:         return "_thread_new_trans";
1499   case _thread_in_native:         return "_thread_in_native";
1500   case _thread_in_native_trans:   return "_thread_in_native_trans";
1501   case _thread_in_vm:             return "_thread_in_vm";
1502   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
1503   case _thread_in_Java:           return "_thread_in_Java";
1504   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
1505   case _thread_blocked:           return "_thread_blocked";
1506   case _thread_blocked_trans:     return "_thread_blocked_trans";
1507   default:                        return "unknown thread state";
1508   }
1509 }
1510 
1511 void JavaThread::print_thread_state_on(outputStream *st) const {
1512   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
1513 }
1514 
1515 // Called by Threads::print() for VM_PrintThreads operation
1516 void JavaThread::print_on(outputStream *st, bool print_extended_info) const {
1517   st->print_raw("\"");
1518   st->print_raw(name());
1519   st->print_raw("\" ");
1520   oop thread_oop = threadObj();
1521   if (thread_oop != nullptr) {
1522     st->print("#" INT64_FORMAT " [%ld] ", (int64_t)java_lang_Thread::thread_id(thread_oop), (long) osthread()->thread_id());
1523     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
1524     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
1525   }
1526   Thread::print_on(st, print_extended_info);
1527   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
1528   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
1529   if (thread_oop != nullptr) {
1530     if (is_vthread_mounted()) {
1531       oop vt = vthread();
1532       assert(vt != nullptr, "");
1533       st->print_cr("   Carrying virtual thread #" INT64_FORMAT, (int64_t)java_lang_Thread::thread_id(vt));
1534     } else {
1535       st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
1536     }
1537   }
1538 #ifndef PRODUCT
1539   _safepoint_state->print_on(st);
1540 #endif // PRODUCT
1541   if (is_Compiler_thread()) {
1542     CompileTask *task = ((CompilerThread*)this)->task();
1543     if (task != nullptr) {
1544       st->print("   Compiling: ");
1545       task->print(st, nullptr, true, false);
1546     } else {
1547       st->print("   No compile task");
1548     }
1549     st->cr();
1550   }
1551 }
1552 
1553 void JavaThread::print() const { print_on(tty); }
1554 
1555 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
1556   st->print("%s", get_thread_name_string(buf, buflen));
1557 }
1558 
1559 // Called by fatal error handler. The difference between this and
1560 // JavaThread::print() is that we can't grab lock or allocate memory.
1561 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
1562   st->print("%s \"%s\"", type_name(), get_thread_name_string(buf, buflen));
1563   Thread* current = Thread::current_or_null_safe();
1564   assert(current != nullptr, "cannot be called by a detached thread");
1565   st->fill_to(60);
1566   if (!current->is_Java_thread() || JavaThread::cast(current)->is_oop_safe()) {
1567     // Only access threadObj() if current thread is not a JavaThread
1568     // or if it is a JavaThread that can safely access oops.
1569     oop thread_obj = threadObj();
1570     if (thread_obj != nullptr) {
1571       st->print(java_lang_Thread::is_daemon(thread_obj) ? " daemon" : "       ");
1572     }
1573   }
1574   st->print(" [");
1575   st->print("%s", _get_thread_state_name(_thread_state));
1576   if (osthread()) {
1577     st->print(", id=%d", osthread()->thread_id());
1578   }
1579   // Use raw field members for stack base/size as this could be
1580   // called before a thread has run enough to initialize them.
1581   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ") (" PROPERFMT ")",
1582             p2i(_stack_base - _stack_size), p2i(_stack_base),
1583             PROPERFMTARGS(_stack_size));
1584   st->print("]");
1585 
1586   ThreadsSMRSupport::print_info_on(this, st);
1587   return;
1588 }
1589 
1590 
1591 // Verification
1592 
1593 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
1594   // ignore if there is no stack
1595   if (!has_last_Java_frame()) return;
1596   // traverse the stack frames. Starts from top frame.
1597   for (StackFrameStream fst(this, true /* update_map */, true /* process_frames */, false /* walk_cont */); !fst.is_done(); fst.next()) {
1598     frame* fr = fst.current();
1599     f(fr, fst.register_map());
1600   }
1601 }
1602 
1603 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
1604 
1605 void JavaThread::verify() {
1606   // Verify oops in the thread.
1607   oops_do(&VerifyOopClosure::verify_oop, nullptr);
1608 
1609   // Verify the stack frames.
1610   frames_do(frame_verify);
1611 }
1612 
1613 // CR 6300358 (sub-CR 2137150)
1614 // Most callers of this method assume that it can't return null but a
1615 // thread may not have a name whilst it is in the process of attaching to
1616 // the VM - see CR 6412693, and there are places where a JavaThread can be
1617 // seen prior to having its threadObj set (e.g., JNI attaching threads and
1618 // if vm exit occurs during initialization). These cases can all be accounted
1619 // for such that this method never returns null.
1620 const char* JavaThread::name() const  {
1621   if (Thread::is_JavaThread_protected(/* target */ this)) {
1622     // The target JavaThread is protected so get_thread_name_string() is safe:
1623     return get_thread_name_string();
1624   }
1625 
1626   // The target JavaThread is not protected so we return the default:
1627   return Thread::name();
1628 }
1629 
1630 // Like name() but doesn't include the protection check. This must only be
1631 // called when it is known to be safe, even though the protection check can't tell
1632 // that e.g. when this thread is the init_thread() - see instanceKlass.cpp.
1633 const char* JavaThread::name_raw() const  {
1634   return get_thread_name_string();
1635 }
1636 
1637 // Returns a non-null representation of this thread's name, or a suitable
1638 // descriptive string if there is no set name.
1639 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
1640   const char* name_str;
1641 #ifdef ASSERT
1642   Thread* current = Thread::current_or_null_safe();
1643   assert(current != nullptr, "cannot be called by a detached thread");
1644   if (!current->is_Java_thread() || JavaThread::cast(current)->is_oop_safe()) {
1645     // Only access threadObj() if current thread is not a JavaThread
1646     // or if it is a JavaThread that can safely access oops.
1647 #endif
1648     oop thread_obj = threadObj();
1649     if (thread_obj != nullptr) {
1650       oop name = java_lang_Thread::name(thread_obj);
1651       if (name != nullptr) {
1652         if (buf == nullptr) {
1653           name_str = java_lang_String::as_utf8_string(name);
1654         } else {
1655           name_str = java_lang_String::as_utf8_string(name, buf, buflen);
1656         }
1657       } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
1658         name_str = "<no-name - thread is attaching>";
1659       } else {
1660         name_str = "<un-named>";
1661       }
1662     } else {
1663       name_str = Thread::name();
1664     }
1665 #ifdef ASSERT
1666   } else {
1667     // Current JavaThread has exited...
1668     if (current == this) {
1669       // ... and is asking about itself:
1670       name_str = "<no-name - current JavaThread has exited>";
1671     } else {
1672       // ... and it can't safely determine this JavaThread's name so
1673       // use the default thread name.
1674       name_str = Thread::name();
1675     }
1676   }
1677 #endif
1678   assert(name_str != nullptr, "unexpected null thread name");
1679   return name_str;
1680 }
1681 
1682 // Helper to extract the name from the thread oop for logging.
1683 const char* JavaThread::name_for(oop thread_obj) {
1684   assert(thread_obj != nullptr, "precondition");
1685   oop name = java_lang_Thread::name(thread_obj);
1686   const char* name_str;
1687   if (name != nullptr) {
1688     name_str = java_lang_String::as_utf8_string(name);
1689   } else {
1690     name_str = "<un-named>";
1691   }
1692   return name_str;
1693 }
1694 
1695 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
1696 
1697   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
1698   assert(NoPriority <= prio && prio <= MaxPriority, "sanity check");
1699   // Link Java Thread object <-> C++ Thread
1700 
1701   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
1702   // and put it into a new Handle.  The Handle "thread_oop" can then
1703   // be used to pass the C++ thread object to other methods.
1704 
1705   // Set the Java level thread object (jthread) field of the
1706   // new thread (a JavaThread *) to C++ thread object using the
1707   // "thread_oop" handle.
1708 
1709   // Set the thread field (a JavaThread *) of the
1710   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
1711 
1712   Handle thread_oop(Thread::current(),
1713                     JNIHandles::resolve_non_null(jni_thread));
1714   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
1715          "must be initialized");
1716   set_threadOopHandles(thread_oop());
1717 
1718   if (prio == NoPriority) {
1719     prio = java_lang_Thread::priority(thread_oop());
1720     assert(prio != NoPriority, "A valid priority should be present");
1721   }
1722 
1723   // Push the Java priority down to the native thread; needs Threads_lock
1724   Thread::set_priority(this, prio);
1725 
1726   // Add the new thread to the Threads list and set it in motion.
1727   // We must have threads lock in order to call Threads::add.
1728   // It is crucial that we do not block before the thread is
1729   // added to the Threads list for if a GC happens, then the java_thread oop
1730   // will not be visited by GC.
1731   Threads::add(this);
1732   // Publish the JavaThread* in java.lang.Thread after the JavaThread* is
1733   // on a ThreadsList. We don't want to wait for the release when the
1734   // Theads_lock is dropped somewhere in the caller since the JavaThread*
1735   // is already visible to JVM/TI via the ThreadsList.
1736   java_lang_Thread::release_set_thread(thread_oop(), this);
1737 }
1738 
1739 oop JavaThread::current_park_blocker() {
1740   // Support for JSR-166 locks
1741   oop thread_oop = threadObj();
1742   if (thread_oop != nullptr) {
1743     return java_lang_Thread::park_blocker(thread_oop);
1744   }
1745   return nullptr;
1746 }
1747 
1748 // Print current stack trace for checked JNI warnings and JNI fatal errors.
1749 // This is the external format, selecting the platform or vthread
1750 // as applicable, and allowing for a native-only stack.
1751 void JavaThread::print_jni_stack() {
1752   assert(this == JavaThread::current(), "Can't print stack of other threads");
1753   if (!has_last_Java_frame()) {
1754     ResourceMark rm(this);
1755     char* buf = NEW_RESOURCE_ARRAY_RETURN_NULL(char, O_BUFLEN);
1756     if (buf == nullptr) {
1757       tty->print_cr("Unable to print native stack - out of memory");
1758       return;
1759     }
1760     address lastpc = nullptr;
1761     if (os::platform_print_native_stack(tty, nullptr, buf, O_BUFLEN, lastpc)) {
1762       // We have printed the native stack in platform-specific code,
1763       // so nothing else to do in this case.
1764     } else {
1765       frame f = os::current_frame();
1766       VMError::print_native_stack(tty, f, this, true /*print_source_info */,
1767                                   -1 /* max stack */, buf, O_BUFLEN);
1768     }
1769   } else {
1770     print_active_stack_on(tty);
1771   }
1772 }
1773 
1774 void JavaThread::print_stack_on(outputStream* st) {
1775   if (!has_last_Java_frame()) return;
1776 
1777   Thread* current_thread = Thread::current();
1778   ResourceMark rm(current_thread);
1779   HandleMark hm(current_thread);
1780 
1781   RegisterMap reg_map(this,
1782                       RegisterMap::UpdateMap::include,
1783                       RegisterMap::ProcessFrames::include,
1784                       RegisterMap::WalkContinuation::skip);
1785   vframe* start_vf = platform_thread_last_java_vframe(&reg_map);
1786   int count = 0;
1787   for (vframe* f = start_vf; f != nullptr; f = f->sender()) {
1788     if (f->is_java_frame()) {
1789       javaVFrame* jvf = javaVFrame::cast(f);
1790       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
1791 
1792       // Print out lock information
1793       if (JavaMonitorsInStackTrace) {
1794         jvf->print_lock_info_on(st, count);
1795       }
1796     } else {
1797       // Ignore non-Java frames
1798     }
1799 
1800     // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
1801     count++;
1802     if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
1803   }
1804 }
1805 
1806 void JavaThread::print_vthread_stack_on(outputStream* st) {
1807   assert(is_vthread_mounted(), "Caller should have checked this");
1808   assert(has_last_Java_frame(), "must be");
1809 
1810   Thread* current_thread = Thread::current();
1811   ResourceMark rm(current_thread);
1812   HandleMark hm(current_thread);
1813 
1814   RegisterMap reg_map(this,
1815                       RegisterMap::UpdateMap::include,
1816                       RegisterMap::ProcessFrames::include,
1817                       RegisterMap::WalkContinuation::include);
1818   ContinuationEntry* cont_entry = last_continuation();
1819   vframe* start_vf = last_java_vframe(&reg_map);
1820   int count = 0;
1821   for (vframe* f = start_vf; f != nullptr; f = f->sender()) {
1822     // Watch for end of vthread stack
1823     if (Continuation::is_continuation_enterSpecial(f->fr())) {
1824       assert(cont_entry == Continuation::get_continuation_entry_for_entry_frame(this, f->fr()), "");
1825       if (cont_entry->is_virtual_thread()) {
1826         break;
1827       }
1828       cont_entry = cont_entry->parent();
1829     }
1830     if (f->is_java_frame()) {
1831       javaVFrame* jvf = javaVFrame::cast(f);
1832       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
1833 
1834       // Print out lock information
1835       if (JavaMonitorsInStackTrace) {
1836         jvf->print_lock_info_on(st, count);
1837       }
1838     } else {
1839       // Ignore non-Java frames
1840     }
1841 
1842     // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
1843     count++;
1844     if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
1845   }
1846 }
1847 
1848 void JavaThread::print_active_stack_on(outputStream* st) {
1849   if (is_vthread_mounted()) {
1850     print_vthread_stack_on(st);
1851   } else {
1852     print_stack_on(st);
1853   }
1854 }
1855 
1856 #if INCLUDE_JVMTI
1857 // Rebind JVMTI thread state from carrier to virtual or from virtual to carrier.
1858 JvmtiThreadState* JavaThread::rebind_to_jvmti_thread_state_of(oop thread_oop) {
1859   set_jvmti_vthread(thread_oop);
1860 
1861   // unbind current JvmtiThreadState from JavaThread
1862   JvmtiThreadState::unbind_from(jvmti_thread_state(), this);
1863 
1864   // bind new JvmtiThreadState to JavaThread
1865   JvmtiThreadState::bind_to(java_lang_Thread::jvmti_thread_state(thread_oop), this);
1866 
1867   return jvmti_thread_state();
1868 }
1869 #endif
1870 
1871 // JVMTI PopFrame support
1872 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
1873   assert(_popframe_preserved_args == nullptr, "should not wipe out old PopFrame preserved arguments");
1874   if (in_bytes(size_in_bytes) != 0) {
1875     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
1876     _popframe_preserved_args_size = in_bytes(size_in_bytes);
1877     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
1878   }
1879 }
1880 
1881 void* JavaThread::popframe_preserved_args() {
1882   return _popframe_preserved_args;
1883 }
1884 
1885 ByteSize JavaThread::popframe_preserved_args_size() {
1886   return in_ByteSize(_popframe_preserved_args_size);
1887 }
1888 
1889 WordSize JavaThread::popframe_preserved_args_size_in_words() {
1890   int sz = in_bytes(popframe_preserved_args_size());
1891   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
1892   return in_WordSize(sz / wordSize);
1893 }
1894 
1895 void JavaThread::popframe_free_preserved_args() {
1896   assert(_popframe_preserved_args != nullptr, "should not free PopFrame preserved arguments twice");
1897   FREE_C_HEAP_ARRAY(char, (char*)_popframe_preserved_args);
1898   _popframe_preserved_args = nullptr;
1899   _popframe_preserved_args_size = 0;
1900 }
1901 
1902 #ifndef PRODUCT
1903 
1904 void JavaThread::trace_frames() {
1905   tty->print_cr("[Describe stack]");
1906   int frame_no = 1;
1907   for (StackFrameStream fst(this, true /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
1908     tty->print("  %d. ", frame_no++);
1909     fst.current()->print_value_on(tty, this);
1910     tty->cr();
1911   }
1912 }
1913 
1914 class PrintAndVerifyOopClosure: public OopClosure {
1915  protected:
1916   template <class T> inline void do_oop_work(T* p) {
1917     oop obj = RawAccess<>::oop_load(p);
1918     if (obj == nullptr) return;
1919     tty->print(INTPTR_FORMAT ": ", p2i(p));
1920     if (oopDesc::is_oop_or_null(obj)) {
1921       if (obj->is_objArray()) {
1922         tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
1923       } else {
1924         obj->print();
1925       }
1926     } else {
1927       tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
1928     }
1929     tty->cr();
1930   }
1931  public:
1932   virtual void do_oop(oop* p) { do_oop_work(p); }
1933   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
1934 };
1935 
1936 #ifdef ASSERT
1937 // Print or validate the layout of stack frames
1938 void JavaThread::print_frame_layout(int depth, bool validate_only) {
1939   ResourceMark rm;
1940   PreserveExceptionMark pm(this);
1941   FrameValues values;
1942   int frame_no = 0;
1943   for (StackFrameStream fst(this, true, true, true); !fst.is_done(); fst.next()) {
1944     fst.current()->describe(values, ++frame_no, fst.register_map());
1945     if (depth == frame_no) break;
1946   }
1947   Continuation::describe(values);
1948   if (validate_only) {
1949     values.validate();
1950   } else {
1951     tty->print_cr("[Describe stack layout]");
1952     values.print(this);
1953   }
1954 }
1955 #endif
1956 
1957 void JavaThread::trace_stack_from(vframe* start_vf) {
1958   ResourceMark rm;
1959   int vframe_no = 1;
1960   for (vframe* f = start_vf; f; f = f->sender()) {
1961     if (f->is_java_frame()) {
1962       javaVFrame::cast(f)->print_activation(vframe_no++);
1963     } else {
1964       f->print();
1965     }
1966     if (vframe_no > StackPrintLimit) {
1967       tty->print_cr("...<more frames>...");
1968       return;
1969     }
1970   }
1971 }
1972 
1973 
1974 void JavaThread::trace_stack() {
1975   if (!has_last_Java_frame()) return;
1976   Thread* current_thread = Thread::current();
1977   ResourceMark rm(current_thread);
1978   HandleMark hm(current_thread);
1979   RegisterMap reg_map(this,
1980                       RegisterMap::UpdateMap::include,
1981                       RegisterMap::ProcessFrames::include,
1982                       RegisterMap::WalkContinuation::skip);
1983   trace_stack_from(last_java_vframe(&reg_map));
1984 }
1985 
1986 
1987 #endif // PRODUCT
1988 
1989 // Slow-path increment of the held monitor counts. JNI locking is always
1990 // this slow-path.
1991 void JavaThread::inc_held_monitor_count(intx i, bool jni) {
1992 #ifdef SUPPORT_MONITOR_COUNT
1993   assert(_held_monitor_count >= 0, "Must always be non-negative: " INTX_FORMAT, _held_monitor_count);
1994   _held_monitor_count += i;
1995   if (jni) {
1996     assert(_jni_monitor_count >= 0, "Must always be non-negative: " INTX_FORMAT, _jni_monitor_count);
1997     _jni_monitor_count += i;
1998   }
1999   assert(_held_monitor_count >= _jni_monitor_count, "Monitor count discrepancy detected - held count "
2000          INTX_FORMAT " is less than JNI count " INTX_FORMAT, _held_monitor_count, _jni_monitor_count);
2001 #endif
2002 }
2003 
2004 // Slow-path decrement of the held monitor counts. JNI unlocking is always
2005 // this slow-path.
2006 void JavaThread::dec_held_monitor_count(intx i, bool jni) {
2007 #ifdef SUPPORT_MONITOR_COUNT
2008   _held_monitor_count -= i;
2009   assert(_held_monitor_count >= 0, "Must always be greater than 0: " INTX_FORMAT, _held_monitor_count);
2010   if (jni) {
2011     _jni_monitor_count -= i;
2012     assert(_jni_monitor_count >= 0, "Must always be greater than 0: " INTX_FORMAT, _jni_monitor_count);
2013   }
2014   // When a thread is detaching with still owned JNI monitors, the logic that releases
2015   // the monitors doesn't know to set the "jni" flag and so the counts can get out of sync.
2016   // So we skip this assert if the thread is exiting. Once all monitors are unlocked the
2017   // JNI count is directly set to zero.
2018   assert(_held_monitor_count >= _jni_monitor_count || is_exiting(), "Monitor count discrepancy detected - held count "
2019          INTX_FORMAT " is less than JNI count " INTX_FORMAT, _held_monitor_count, _jni_monitor_count);
2020 #endif
2021 }
2022 
2023 frame JavaThread::vthread_last_frame() {
2024   assert (is_vthread_mounted(), "Virtual thread not mounted");
2025   return last_frame();
2026 }
2027 
2028 frame JavaThread::carrier_last_frame(RegisterMap* reg_map) {
2029   const ContinuationEntry* entry = vthread_continuation();
2030   guarantee (entry != nullptr, "Not a carrier thread");
2031   frame f = entry->to_frame();
2032   if (reg_map->process_frames()) {
2033     entry->flush_stack_processing(this);
2034   }
2035   entry->update_register_map(reg_map);
2036   return f.sender(reg_map);
2037 }
2038 
2039 frame JavaThread::platform_thread_last_frame(RegisterMap* reg_map) {
2040   return is_vthread_mounted() ? carrier_last_frame(reg_map) : last_frame();
2041 }
2042 
2043 javaVFrame* JavaThread::last_java_vframe(const frame f, RegisterMap *reg_map) {
2044   assert(reg_map != nullptr, "a map must be given");
2045   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
2046     if (vf->is_java_frame()) return javaVFrame::cast(vf);
2047   }
2048   return nullptr;
2049 }
2050 
2051 Klass* JavaThread::security_get_caller_class(int depth) {
2052   ResetNoHandleMark rnhm;
2053   HandleMark hm(Thread::current());
2054 
2055   vframeStream vfst(this);
2056   vfst.security_get_caller_frame(depth);
2057   if (!vfst.at_end()) {
2058     return vfst.method()->method_holder();
2059   }
2060   return nullptr;
2061 }
2062 
2063 // Internal convenience function for millisecond resolution sleeps.
2064 bool JavaThread::sleep(jlong millis) {
2065   jlong nanos;
2066   if (millis > max_jlong / NANOUNITS_PER_MILLIUNIT) {
2067     // Conversion to nanos would overflow, saturate at max
2068     nanos = max_jlong;
2069   } else {
2070     nanos = millis * NANOUNITS_PER_MILLIUNIT;
2071   }
2072   return sleep_nanos(nanos);
2073 }
2074 
2075 // java.lang.Thread.sleep support
2076 // Returns true if sleep time elapsed as expected, and false
2077 // if the thread was interrupted.
2078 bool JavaThread::sleep_nanos(jlong nanos) {
2079   assert(this == Thread::current(),  "thread consistency check");
2080   assert(nanos >= 0, "nanos are in range");
2081 
2082   ParkEvent * const slp = this->_SleepEvent;
2083   // Because there can be races with thread interruption sending an unpark()
2084   // to the event, we explicitly reset it here to avoid an immediate return.
2085   // The actual interrupt state will be checked before we park().
2086   slp->reset();
2087   // Thread interruption establishes a happens-before ordering in the
2088   // Java Memory Model, so we need to ensure we synchronize with the
2089   // interrupt state.
2090   OrderAccess::fence();
2091 
2092   jlong prevtime = os::javaTimeNanos();
2093 
2094   jlong nanos_remaining = nanos;
2095 
2096   for (;;) {
2097     // interruption has precedence over timing out
2098     if (this->is_interrupted(true)) {
2099       return false;
2100     }
2101 
2102     if (nanos_remaining <= 0) {
2103       return true;
2104     }
2105 
2106     {
2107       ThreadBlockInVM tbivm(this);
2108       OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
2109       slp->park_nanos(nanos_remaining);
2110     }
2111 
2112     // Update elapsed time tracking
2113     jlong newtime = os::javaTimeNanos();
2114     if (newtime - prevtime < 0) {
2115       // time moving backwards, should only happen if no monotonic clock
2116       // not a guarantee() because JVM should not abort on kernel/glibc bugs
2117       assert(false,
2118              "unexpected time moving backwards detected in JavaThread::sleep()");
2119     } else {
2120       nanos_remaining -= (newtime - prevtime);
2121     }
2122     prevtime = newtime;
2123   }
2124 }
2125 
2126 // Last thread running calls java.lang.Shutdown.shutdown()
2127 void JavaThread::invoke_shutdown_hooks() {
2128   HandleMark hm(this);
2129 
2130   // We could get here with a pending exception, if so clear it now.
2131   if (this->has_pending_exception()) {
2132     this->clear_pending_exception();
2133   }
2134 
2135   EXCEPTION_MARK;
2136   Klass* shutdown_klass =
2137     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
2138                                       THREAD);
2139   if (shutdown_klass != nullptr) {
2140     // SystemDictionary::resolve_or_null will return null if there was
2141     // an exception.  If we cannot load the Shutdown class, just don't
2142     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
2143     // won't be run.  Note that if a shutdown hook was registered,
2144     // the Shutdown class would have already been loaded
2145     // (Runtime.addShutdownHook will load it).
2146     JavaValue result(T_VOID);
2147     JavaCalls::call_static(&result,
2148                            shutdown_klass,
2149                            vmSymbols::shutdown_name(),
2150                            vmSymbols::void_method_signature(),
2151                            THREAD);
2152   }
2153   CLEAR_PENDING_EXCEPTION;
2154 }
2155 
2156 #ifndef PRODUCT
2157 void JavaThread::verify_cross_modify_fence_failure(JavaThread *thread) {
2158    report_vm_error(__FILE__, __LINE__, "Cross modify fence failure", "%p", thread);
2159 }
2160 #endif
2161 
2162 // Helper function to create the java.lang.Thread object for a
2163 // VM-internal thread. The thread will have the given name, and be
2164 // a member of the "system" ThreadGroup.
2165 Handle JavaThread::create_system_thread_object(const char* name, TRAPS) {
2166   Handle string = java_lang_String::create_from_str(name, CHECK_NH);
2167 
2168   // Initialize thread_oop to put it into the system threadGroup.
2169   // This is done by calling the Thread(ThreadGroup group, String name) constructor.
2170   Handle thread_group(THREAD, Universe::system_thread_group());
2171   Handle thread_oop =
2172     JavaCalls::construct_new_instance(vmClasses::Thread_klass(),
2173                                       vmSymbols::threadgroup_string_void_signature(),
2174                                       thread_group,
2175                                       string,
2176                                       CHECK_NH);
2177 
2178   return thread_oop;
2179 }
2180 
2181 // Starts the target JavaThread as a daemon of the given priority, and
2182 // bound to the given java.lang.Thread instance.
2183 // The Threads_lock is held for the duration.
2184 void JavaThread::start_internal_daemon(JavaThread* current, JavaThread* target,
2185                                        Handle thread_oop, ThreadPriority prio) {
2186 
2187   assert(target->osthread() != nullptr, "target thread is not properly initialized");
2188 
2189   MutexLocker mu(current, Threads_lock);
2190 
2191   // Initialize the fields of the thread_oop first.
2192   if (prio != NoPriority) {
2193     java_lang_Thread::set_priority(thread_oop(), prio);
2194     // Note: we don't call os::set_priority here. Possibly we should,
2195     // else all threads should call it themselves when they first run.
2196   }
2197 
2198   java_lang_Thread::set_daemon(thread_oop());
2199 
2200   // Now bind the thread_oop to the target JavaThread.
2201   target->set_threadOopHandles(thread_oop());
2202 
2203   Threads::add(target); // target is now visible for safepoint/handshake
2204   // Publish the JavaThread* in java.lang.Thread after the JavaThread* is
2205   // on a ThreadsList. We don't want to wait for the release when the
2206   // Theads_lock is dropped when the 'mu' destructor is run since the
2207   // JavaThread* is already visible to JVM/TI via the ThreadsList.
2208 
2209   assert(java_lang_Thread::thread(thread_oop()) == nullptr, "must not be alive");
2210   java_lang_Thread::release_set_thread(thread_oop(), target); // isAlive == true now
2211   Thread::start(target);
2212 }
2213 
2214 void JavaThread::vm_exit_on_osthread_failure(JavaThread* thread) {
2215   // At this point it may be possible that no osthread was created for the
2216   // JavaThread due to lack of resources. However, since this must work
2217   // for critical system threads just check and abort if this fails.
2218   if (thread->osthread() == nullptr) {
2219     // This isn't really an OOM condition, but historically this is what
2220     // we report.
2221     vm_exit_during_initialization("java.lang.OutOfMemoryError",
2222                                   os::native_thread_creation_failed_msg());
2223   }
2224 }
2225 
2226 void JavaThread::pretouch_stack() {
2227   // Given an established java thread stack with usable area followed by
2228   // shadow zone and reserved/yellow/red zone, pretouch the usable area ranging
2229   // from the current frame down to the start of the shadow zone.
2230   const address end = _stack_overflow_state.shadow_zone_safe_limit();
2231   if (is_in_full_stack(end)) {
2232     char* p1 = (char*) alloca(1);
2233     address here = (address) &p1;
2234     if (is_in_full_stack(here) && here > end) {
2235       size_t to_alloc = here - end;
2236       char* p2 = (char*) alloca(to_alloc);
2237       log_trace(os, thread)("Pretouching thread stack from " PTR_FORMAT " to " PTR_FORMAT ".",
2238                             p2i(p2), p2i(end));
2239       os::pretouch_memory(p2, p2 + to_alloc,
2240                           NOT_AIX(os::vm_page_size()) AIX_ONLY(4096));
2241     }
2242   }
2243 }
2244 
2245 // Deferred OopHandle release support.
2246 
2247 class OopHandleList : public CHeapObj<mtInternal> {
2248   static const int _count = 4;
2249   OopHandle _handles[_count];
2250   OopHandleList* _next;
2251   int _index;
2252  public:
2253   OopHandleList(OopHandleList* next) : _next(next), _index(0) {}
2254   void add(OopHandle h) {
2255     assert(_index < _count, "too many additions");
2256     _handles[_index++] = h;
2257   }
2258   ~OopHandleList() {
2259     assert(_index == _count, "usage error");
2260     for (int i = 0; i < _index; i++) {
2261       _handles[i].release(JavaThread::thread_oop_storage());
2262     }
2263   }
2264   OopHandleList* next() const { return _next; }
2265 };
2266 
2267 OopHandleList* JavaThread::_oop_handle_list = nullptr;
2268 
2269 // Called by the ServiceThread to do the work of releasing
2270 // the OopHandles.
2271 void JavaThread::release_oop_handles() {
2272   OopHandleList* list;
2273   {
2274     MutexLocker ml(Service_lock, Mutex::_no_safepoint_check_flag);
2275     list = _oop_handle_list;
2276     _oop_handle_list = nullptr;
2277   }
2278   assert(!SafepointSynchronize::is_at_safepoint(), "cannot be called at a safepoint");
2279 
2280   while (list != nullptr) {
2281     OopHandleList* l = list;
2282     list = l->next();
2283     delete l;
2284   }
2285 }
2286 
2287 // Add our OopHandles for later release.
2288 void JavaThread::add_oop_handles_for_release() {
2289   MutexLocker ml(Service_lock, Mutex::_no_safepoint_check_flag);
2290   OopHandleList* new_head = new OopHandleList(_oop_handle_list);
2291   new_head->add(_threadObj);
2292   new_head->add(_vthread);
2293   new_head->add(_jvmti_vthread);
2294   new_head->add(_scopedValueCache);
2295   _oop_handle_list = new_head;
2296   Service_lock->notify_all();
2297 }