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