1 /*
2 * Copyright (c) 1997, 2025, 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 "cds/dynamicArchive.hpp"
27 #include "ci/ciEnv.hpp"
28 #include "classfile/javaClasses.inline.hpp"
29 #include "classfile/javaThreadStatus.hpp"
30 #include "classfile/systemDictionary.hpp"
31 #include "classfile/vmClasses.hpp"
32 #include "classfile/vmSymbols.hpp"
33 #include "code/codeCache.hpp"
34 #include "code/scopeDesc.hpp"
35 #include "compiler/compileTask.hpp"
36 #include "compiler/compilerThread.hpp"
37 #include "gc/shared/oopStorage.hpp"
38 #include "gc/shared/oopStorageSet.hpp"
39 #include "gc/shared/tlab_globals.hpp"
40 #include "jfr/jfrEvents.hpp"
41 #include "jvm.h"
42 #include "jvmtifiles/jvmtiEnv.hpp"
43 #include "logging/log.hpp"
44 #include "logging/logAsyncWriter.hpp"
45 #include "logging/logStream.hpp"
46 #include "memory/allocation.inline.hpp"
47 #include "memory/iterator.hpp"
48 #include "memory/universe.hpp"
49 #include "oops/access.inline.hpp"
50 #include "oops/inlineKlass.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/threadIdentifier.hpp"
87 #include "runtime/threadSMR.inline.hpp"
88 #include "runtime/threadStatisticalInfo.hpp"
89 #include "runtime/threadWXSetters.inline.hpp"
90 #include "runtime/timer.hpp"
91 #include "runtime/timerTrace.hpp"
92 #include "runtime/vframe.inline.hpp"
93 #include "runtime/vframeArray.hpp"
94 #include "runtime/vframe_hp.hpp"
95 #include "runtime/vmThread.hpp"
96 #include "runtime/vmOperations.hpp"
97 #include "services/threadService.hpp"
98 #include "utilities/copy.hpp"
99 #include "utilities/defaultStream.hpp"
100 #include "utilities/dtrace.hpp"
101 #include "utilities/events.hpp"
102 #include "utilities/macros.hpp"
103 #include "utilities/nativeStackPrinter.hpp"
104 #include "utilities/preserveException.hpp"
105 #include "utilities/spinYield.hpp"
106 #include "utilities/vmError.hpp"
107 #if INCLUDE_JVMCI
108 #include "jvmci/jvmci.hpp"
109 #include "jvmci/jvmciEnv.hpp"
110 #endif
111 #if INCLUDE_JFR
112 #include "jfr/jfr.hpp"
113 #endif
114
115 // Set by os layer.
116 size_t JavaThread::_stack_size_at_create = 0;
117
118 #ifdef DTRACE_ENABLED
119
120 // Only bother with this argument setup if dtrace is available
121
122 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
123 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
124
125 #define DTRACE_THREAD_PROBE(probe, javathread) \
126 { \
127 ResourceMark rm(this); \
128 int len = 0; \
129 const char* name = (javathread)->name(); \
130 len = strlen(name); \
131 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
132 (char *) name, len, \
133 java_lang_Thread::thread_id((javathread)->threadObj()), \
134 (uintptr_t) (javathread)->osthread()->thread_id(), \
135 java_lang_Thread::is_daemon((javathread)->threadObj())); \
136 }
137
138 #else // ndef DTRACE_ENABLED
139
140 #define DTRACE_THREAD_PROBE(probe, javathread)
141
142 #endif // ndef DTRACE_ENABLED
143
144 void JavaThread::smr_delete() {
145 if (_on_thread_list) {
146 ThreadsSMRSupport::smr_delete(this);
147 } else {
148 delete this;
149 }
150 }
151
152 // Initialized by VMThread at vm_global_init
153 OopStorage* JavaThread::_thread_oop_storage = nullptr;
154
155 OopStorage* JavaThread::thread_oop_storage() {
156 assert(_thread_oop_storage != nullptr, "not yet initialized");
157 return _thread_oop_storage;
158 }
159
160 void JavaThread::set_threadOopHandles(oop p) {
161 assert(_thread_oop_storage != nullptr, "not yet initialized");
162 _threadObj = OopHandle(_thread_oop_storage, p);
163 _vthread = OopHandle(_thread_oop_storage, p);
164 _jvmti_vthread = OopHandle(_thread_oop_storage, p->is_a(vmClasses::BoundVirtualThread_klass()) ? p : nullptr);
165 _scopedValueCache = OopHandle(_thread_oop_storage, nullptr);
166 }
167
168 oop JavaThread::threadObj() const {
169 // Ideally we would verify the current thread is oop_safe when this is called, but as we can
170 // be called from a signal handler we would have to use Thread::current_or_null_safe(). That
171 // has overhead and also interacts poorly with GetLastError on Windows due to the use of TLS.
172 // Instead callers must verify oop safe access.
173 return _threadObj.resolve();
174 }
175
176 oop JavaThread::vthread() const {
177 return _vthread.resolve();
178 }
179
180 void JavaThread::set_vthread(oop p) {
181 assert(_thread_oop_storage != nullptr, "not yet initialized");
182 _vthread.replace(p);
183 }
184
185 oop JavaThread::jvmti_vthread() const {
186 return _jvmti_vthread.resolve();
187 }
188
189 void JavaThread::set_jvmti_vthread(oop p) {
190 assert(_thread_oop_storage != nullptr, "not yet initialized");
191 _jvmti_vthread.replace(p);
192 }
193
194 // If there is a virtual thread mounted then return vthread() oop.
195 // Otherwise, return threadObj().
196 oop JavaThread::vthread_or_thread() const {
197 oop result = vthread();
198 if (result == nullptr) {
199 result = threadObj();
200 }
201 return result;
202 }
203
204 oop JavaThread::scopedValueCache() const {
205 return _scopedValueCache.resolve();
206 }
207
208 void JavaThread::set_scopedValueCache(oop p) {
209 if (!_scopedValueCache.is_empty()) { // i.e. if the OopHandle has been allocated
210 _scopedValueCache.replace(p);
211 } else {
212 assert(p == nullptr, "not yet initialized");
213 }
214 }
215
216 void JavaThread::clear_scopedValueBindings() {
217 set_scopedValueCache(nullptr);
218 oop vthread_oop = vthread();
219 // vthread may be null here if we get a VM error during startup,
220 // before the java.lang.Thread instance has been created.
221 if (vthread_oop != nullptr) {
222 java_lang_Thread::clear_scopedValueBindings(vthread_oop);
223 }
224 }
225
226 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
227 bool daemon, TRAPS) {
228 assert(thread_group.not_null(), "thread group should be specified");
229 assert(threadObj() == nullptr, "should only create Java thread object once");
230
231 InstanceKlass* ik = vmClasses::Thread_klass();
232 assert(ik->is_initialized(), "must be");
233 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
234
235 // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon.
236 // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread
237 // constructor calls Thread.current(), which must be set here.
238 java_lang_Thread::set_thread(thread_oop(), this);
239 set_threadOopHandles(thread_oop());
240
241 JavaValue result(T_VOID);
242 if (thread_name != nullptr) {
243 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
244 // Thread gets assigned specified name and null target
245 JavaCalls::call_special(&result,
246 thread_oop,
247 ik,
248 vmSymbols::object_initializer_name(),
249 vmSymbols::threadgroup_string_void_signature(),
250 thread_group,
251 name,
252 CHECK);
253 } else {
254 // Thread gets assigned name "Thread-nnn" and null target
255 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
256 JavaCalls::call_special(&result,
257 thread_oop,
258 ik,
259 vmSymbols::object_initializer_name(),
260 vmSymbols::threadgroup_runnable_void_signature(),
261 thread_group,
262 Handle(),
263 CHECK);
264 }
265
266 os::set_priority(this, NormPriority);
267
268 if (daemon) {
269 java_lang_Thread::set_daemon(thread_oop());
270 }
271 }
272
273 // ======= JavaThread ========
274
275 #if INCLUDE_JVMCI
276
277 jlong* JavaThread::_jvmci_old_thread_counters;
278
279 static bool jvmci_counters_include(JavaThread* thread) {
280 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
281 }
282
283 void JavaThread::collect_counters(jlong* array, int length) {
284 assert(length == JVMCICounterSize, "wrong value");
285 for (int i = 0; i < length; i++) {
286 array[i] = _jvmci_old_thread_counters[i];
287 }
288 for (JavaThread* tp : ThreadsListHandle()) {
289 if (jvmci_counters_include(tp)) {
290 for (int i = 0; i < length; i++) {
291 array[i] += tp->_jvmci_counters[i];
292 }
293 }
294 }
295 }
296
297 // Attempt to enlarge the array for per thread counters.
298 static jlong* resize_counters_array(jlong* old_counters, int current_size, int new_size) {
299 jlong* new_counters = NEW_C_HEAP_ARRAY_RETURN_NULL(jlong, new_size, mtJVMCI);
300 if (new_counters == nullptr) {
301 return nullptr;
302 }
303 if (old_counters == nullptr) {
304 old_counters = new_counters;
305 memset(old_counters, 0, sizeof(jlong) * new_size);
306 } else {
307 for (int i = 0; i < MIN2((int) current_size, new_size); i++) {
308 new_counters[i] = old_counters[i];
309 }
310 if (new_size > current_size) {
311 memset(new_counters + current_size, 0, sizeof(jlong) * (new_size - current_size));
312 }
313 FREE_C_HEAP_ARRAY(jlong, old_counters);
314 }
315 return new_counters;
316 }
317
318 // Attempt to enlarge the array for per thread counters.
319 bool JavaThread::resize_counters(int current_size, int new_size) {
320 jlong* new_counters = resize_counters_array(_jvmci_counters, current_size, new_size);
321 if (new_counters == nullptr) {
322 return false;
323 } else {
324 _jvmci_counters = new_counters;
325 return true;
326 }
327 }
328
329 class VM_JVMCIResizeCounters : public VM_Operation {
330 private:
331 int _new_size;
332 bool _failed;
333
334 public:
335 VM_JVMCIResizeCounters(int new_size) : _new_size(new_size), _failed(false) { }
336 VMOp_Type type() const { return VMOp_JVMCIResizeCounters; }
337 bool allow_nested_vm_operations() const { return true; }
338 void doit() {
339 // Resize the old thread counters array
340 jlong* new_counters = resize_counters_array(JavaThread::_jvmci_old_thread_counters, JVMCICounterSize, _new_size);
341 if (new_counters == nullptr) {
342 _failed = true;
343 return;
344 } else {
345 JavaThread::_jvmci_old_thread_counters = new_counters;
346 }
347
348 // Now resize each threads array
349 for (JavaThread* tp : ThreadsListHandle()) {
350 if (!tp->resize_counters(JVMCICounterSize, _new_size)) {
351 _failed = true;
352 break;
353 }
354 }
355 if (!_failed) {
356 JVMCICounterSize = _new_size;
357 }
358 }
359
360 bool failed() { return _failed; }
361 };
362
363 bool JavaThread::resize_all_jvmci_counters(int new_size) {
364 VM_JVMCIResizeCounters op(new_size);
365 VMThread::execute(&op);
366 return !op.failed();
367 }
368
369 #endif // INCLUDE_JVMCI
370
371 #ifdef ASSERT
372 // Checks safepoint allowed and clears unhandled oops at potential safepoints.
373 void JavaThread::check_possible_safepoint() {
374 if (_no_safepoint_count > 0) {
375 print_owned_locks();
376 assert(false, "Possible safepoint reached by thread that does not allow it");
377 }
378 #ifdef CHECK_UNHANDLED_OOPS
379 // Clear unhandled oops in JavaThreads so we get a crash right away.
380 clear_unhandled_oops();
381 #endif // CHECK_UNHANDLED_OOPS
382
383 // Macos/aarch64 should be in the right state for safepoint (e.g.
384 // deoptimization needs WXWrite). Crashes caused by the wrong state rarely
385 // happens in practice, making such issues hard to find and reproduce.
386 #if defined(__APPLE__) && defined(AARCH64)
387 if (AssertWXAtThreadSync) {
388 assert_wx_state(WXWrite);
389 }
390 #endif
391 }
392
393 void JavaThread::check_for_valid_safepoint_state() {
394 // Don't complain if running a debugging command.
395 if (DebuggingContext::is_enabled()) return;
396
397 // Check NoSafepointVerifier, which is implied by locks taken that can be
398 // shared with the VM thread. This makes sure that no locks with allow_vm_block
399 // are held.
400 check_possible_safepoint();
401
402 if (thread_state() != _thread_in_vm) {
403 fatal("LEAF method calling lock?");
404 }
405
406 if (GCALotAtAllSafepoints) {
407 // We could enter a safepoint here and thus have a gc
408 InterfaceSupport::check_gc_alot();
409 }
410 }
411 #endif // ASSERT
412
413 // A JavaThread is a normal Java thread
414
415 JavaThread::JavaThread(MemTag mem_tag) :
416 Thread(mem_tag),
417 // Initialize fields
418 _on_thread_list(false),
419 DEBUG_ONLY(_java_call_counter(0) COMMA)
420 _entry_point(nullptr),
421 _deopt_mark(nullptr),
422 _deopt_nmethod(nullptr),
423 _vframe_array_head(nullptr),
424 _vframe_array_last(nullptr),
425 _jvmti_deferred_updates(nullptr),
426 _callee_target(nullptr),
427 _vm_result(nullptr),
428 _vm_result_2(nullptr),
429
430 _current_pending_monitor(nullptr),
431 _current_pending_monitor_is_from_java(true),
432 _current_waiting_monitor(nullptr),
433 _active_handles(nullptr),
434 _free_handle_block(nullptr),
435 _monitor_owner_id(0),
436
437 _suspend_flags(0),
438
439 _thread_state(_thread_new),
440 _saved_exception_pc(nullptr),
441 #ifdef ASSERT
442 _no_safepoint_count(0),
443 _visited_for_critical_count(false),
444 #endif
445
446 _terminated(_not_terminated),
447 _in_deopt_handler(0),
448 _doing_unsafe_access(false),
449 _do_not_unlock_if_synchronized(false),
450 #if INCLUDE_JVMTI
451 _carrier_thread_suspended(false),
452 _is_in_VTMS_transition(false),
453 _is_disable_suspend(false),
454 _VTMS_transition_mark(false),
455 _on_monitor_waited_event(false),
456 _contended_entered_monitor(nullptr),
457 #ifdef ASSERT
458 _is_VTMS_transition_disabler(false),
459 #endif
460 #endif
461 _jni_attach_state(_not_attaching_via_jni),
462 _is_in_internal_oome_mark(false),
463 #if INCLUDE_JVMCI
464 _pending_deoptimization(-1),
465 _pending_monitorenter(false),
466 _pending_transfer_to_interpreter(false),
467 _pending_failed_speculation(0),
468 _jvmci{nullptr},
469 _libjvmci_runtime(nullptr),
470 _jvmci_counters(nullptr),
471 _jvmci_reserved0(0),
472 _jvmci_reserved1(0),
473 _jvmci_reserved_oop0(nullptr),
474 _live_nmethod(nullptr),
475 #endif // INCLUDE_JVMCI
476
477 _exception_oop(oop()),
478 _exception_pc(nullptr),
479 _exception_handler_pc(nullptr),
480 _is_method_handle_return(0),
481
482 _jni_active_critical(0),
483 _pending_jni_exception_check_fn(nullptr),
484 _depth_first_number(0),
485
486 // JVMTI PopFrame support
487 _popframe_condition(popframe_inactive),
488 _frames_to_pop_failed_realloc(0),
489
490 _cont_entry(nullptr),
491 _cont_fastpath(nullptr),
492 _cont_fastpath_thread_state(1),
493 _held_monitor_count(0),
494 _jni_monitor_count(0),
495 _unlocked_inflated_monitor(nullptr),
496
497 _preempt_alternate_return(nullptr),
498 _preemption_cancelled(false),
499 _pending_interrupted_exception(false),
500
501 _handshake(this),
502
503 _popframe_preserved_args(nullptr),
504 _popframe_preserved_args_size(0),
505
506 _jvmti_thread_state(nullptr),
507 _interp_only_mode(0),
508 _should_post_on_exceptions_flag(JNI_FALSE),
509 _thread_stat(new ThreadStatistics()),
510
511 _parker(),
512
513 _class_to_be_initialized(nullptr),
514 _class_being_initialized(nullptr),
515
516 _SleepEvent(ParkEvent::Allocate(this)),
517
518 #if INCLUDE_JFR
519 _last_freeze_fail_result(freeze_ok),
520 #endif
521
522 _lock_stack(this),
523 _om_cache(this) {
524 set_jni_functions(jni_functions());
525
526 #if INCLUDE_JVMCI
527 assert(_jvmci._implicit_exception_pc == nullptr, "must be");
528 if (JVMCICounterSize > 0) {
529 resize_counters(0, (int) JVMCICounterSize);
530 }
531 #endif // INCLUDE_JVMCI
532
533 // Setup safepoint state info for this thread
534 ThreadSafepointState::create(this);
535
536 SafepointMechanism::initialize_header(this);
537
538 set_requires_cross_modify_fence(false);
539
540 pd_initialize();
541 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
542 }
543
544 JavaThread* JavaThread::create_attaching_thread() {
545 JavaThread* jt = new JavaThread();
546 jt->_jni_attach_state = _attaching_via_jni;
547 return jt;
548 }
549
550 // interrupt support
551
552 void JavaThread::interrupt() {
553 // All callers should have 'this' thread protected by a
554 // ThreadsListHandle so that it cannot terminate and deallocate
555 // itself.
556 debug_only(check_for_dangling_thread_pointer(this);)
557
558 // For Windows _interrupt_event
559 WINDOWS_ONLY(osthread()->set_interrupted(true);)
560
561 // For Thread.sleep
562 _SleepEvent->unpark();
563
564 // For JSR166 LockSupport.park
565 parker()->unpark();
566
567 // For ObjectMonitor and JvmtiRawMonitor
568 _ParkEvent->unpark();
569 }
570
571 bool JavaThread::is_interrupted(bool clear_interrupted) {
572 debug_only(check_for_dangling_thread_pointer(this);)
573
574 if (_threadObj.peek() == nullptr) {
575 // If there is no j.l.Thread then it is impossible to have
576 // been interrupted. We can find null during VM initialization
577 // or when a JNI thread is still in the process of attaching.
578 // In such cases this must be the current thread.
579 assert(this == Thread::current(), "invariant");
580 return false;
581 }
582
583 bool interrupted = java_lang_Thread::interrupted(threadObj());
584
585 // NOTE that since there is no "lock" around the interrupt and
586 // is_interrupted operations, there is the possibility that the
587 // interrupted flag will be "false" but that the
588 // low-level events will be in the signaled state. This is
589 // intentional. The effect of this is that Object.wait() and
590 // LockSupport.park() will appear to have a spurious wakeup, which
591 // is allowed and not harmful, and the possibility is so rare that
592 // it is not worth the added complexity to add yet another lock.
593 // For the sleep event an explicit reset is performed on entry
594 // to JavaThread::sleep, so there is no early return. It has also been
595 // recommended not to put the interrupted flag into the "event"
596 // structure because it hides the issue.
597 // Also, because there is no lock, we must only clear the interrupt
598 // state if we are going to report that we were interrupted; otherwise
599 // an interrupt that happens just after we read the field would be lost.
600 if (interrupted && clear_interrupted) {
601 assert(this == Thread::current(), "only the current thread can clear");
602 java_lang_Thread::set_interrupted(threadObj(), false);
603 WINDOWS_ONLY(osthread()->set_interrupted(false);)
604 }
605 return interrupted;
606 }
607
608 // This is only for use by JVMTI RawMonitorWait. It emulates the actions of
609 // the Java code in Object::wait which are not present in RawMonitorWait.
610 bool JavaThread::get_and_clear_interrupted() {
611 if (!is_interrupted(false)) {
612 return false;
613 }
614 oop thread_oop = vthread_or_thread();
615 bool is_virtual = java_lang_VirtualThread::is_instance(thread_oop);
616
617 if (!is_virtual) {
618 return is_interrupted(true);
619 }
620 // Virtual thread: clear interrupt status for both virtual and
621 // carrier threads under the interruptLock protection.
622 JavaThread* current = JavaThread::current();
623 HandleMark hm(current);
624 Handle thread_h(current, thread_oop);
625 ObjectLocker lock(Handle(current, java_lang_Thread::interrupt_lock(thread_h())), current);
626
627 // re-check the interrupt status under the interruptLock protection
628 bool interrupted = java_lang_Thread::interrupted(thread_h());
629
630 if (interrupted) {
631 assert(this == Thread::current(), "only the current thread can clear");
632 java_lang_Thread::set_interrupted(thread_h(), false); // clear for virtual
633 java_lang_Thread::set_interrupted(threadObj(), false); // clear for carrier
634 WINDOWS_ONLY(osthread()->set_interrupted(false);)
635 }
636 return interrupted;
637 }
638
639 void JavaThread::block_if_vm_exited() {
640 if (_terminated == _vm_exited) {
641 // _vm_exited is set at safepoint, and Threads_lock is never released
642 // so we will block here forever.
643 // Here we can be doing a jump from a safe state to an unsafe state without
644 // proper transition, but it happens after the final safepoint has begun so
645 // this jump won't cause any safepoint problems.
646 set_thread_state(_thread_in_vm);
647 Threads_lock->lock();
648 ShouldNotReachHere();
649 }
650 }
651
652 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz, MemTag mem_tag) : JavaThread(mem_tag) {
653 set_entry_point(entry_point);
654 // Create the native thread itself.
655 // %note runtime_23
656 os::ThreadType thr_type = os::java_thread;
657 thr_type = entry_point == &CompilerThread::thread_entry ? os::compiler_thread :
658 os::java_thread;
659 os::create_thread(this, thr_type, stack_sz);
660 // The _osthread may be null here because we ran out of memory (too many threads active).
661 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
662 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
663 // the exception consists of creating the exception object & initializing it, initialization
664 // will leave the VM via a JavaCall and then all locks must be unlocked).
665 //
666 // The thread is still suspended when we reach here. Thread must be explicit started
667 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
668 // by calling Threads:add. The reason why this is not done here, is because the thread
669 // object must be fully initialized (take a look at JVM_Start)
670 }
671
672 JavaThread::~JavaThread() {
673
674 // Enqueue OopHandles for release by the service thread.
675 add_oop_handles_for_release();
676
677 // Return the sleep event to the free list
678 ParkEvent::Release(_SleepEvent);
679 _SleepEvent = nullptr;
680
681 // Free any remaining previous UnrollBlock
682 vframeArray* old_array = vframe_array_last();
683
684 if (old_array != nullptr) {
685 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
686 old_array->set_unroll_block(nullptr);
687 delete old_info;
688 delete old_array;
689 }
690
691 JvmtiDeferredUpdates* updates = deferred_updates();
692 if (updates != nullptr) {
693 // This can only happen if thread is destroyed before deoptimization occurs.
694 assert(updates->count() > 0, "Updates holder not deleted");
695 // free deferred updates.
696 delete updates;
697 set_deferred_updates(nullptr);
698 }
699
700 // All Java related clean up happens in exit
701 ThreadSafepointState::destroy(this);
702 if (_thread_stat != nullptr) delete _thread_stat;
703
704 #if INCLUDE_JVMCI
705 if (JVMCICounterSize > 0) {
706 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
707 }
708 #endif // INCLUDE_JVMCI
709 }
710
711
712 // First JavaThread specific code executed by a new Java thread.
713 void JavaThread::pre_run() {
714 // empty - see comments in run()
715 }
716
717 // The main routine called by a new Java thread. This isn't overridden
718 // by subclasses, instead different subclasses define a different "entry_point"
719 // which defines the actual logic for that kind of thread.
720 void JavaThread::run() {
721 // initialize thread-local alloc buffer related fields
722 initialize_tlab();
723
724 _stack_overflow_state.create_stack_guard_pages();
725
726 cache_global_variables();
727
728 // Thread is now sufficiently initialized to be handled by the safepoint code as being
729 // in the VM. Change thread state from _thread_new to _thread_in_vm
730 assert(this->thread_state() == _thread_new, "wrong thread state");
731 set_thread_state(_thread_in_vm);
732
733 // Before a thread is on the threads list it is always safe, so after leaving the
734 // _thread_new we should emit a instruction barrier. The distance to modified code
735 // from here is probably far enough, but this is consistent and safe.
736 OrderAccess::cross_modify_fence();
737
738 assert(JavaThread::current() == this, "sanity check");
739 assert(!Thread::current()->owns_locks(), "sanity check");
740
741 DTRACE_THREAD_PROBE(start, this);
742
743 // This operation might block. We call that after all safepoint checks for a new thread has
744 // been completed.
745 set_active_handles(JNIHandleBlock::allocate_block());
746
747 if (JvmtiExport::should_post_thread_life()) {
748 JvmtiExport::post_thread_start(this);
749
750 }
751
752 if (AlwaysPreTouchStacks) {
753 pretouch_stack();
754 }
755
756 // We call another function to do the rest so we are sure that the stack addresses used
757 // from there will be lower than the stack base just computed.
758 thread_main_inner();
759 }
760
761 void JavaThread::thread_main_inner() {
762 assert(JavaThread::current() == this, "sanity check");
763 assert(_threadObj.peek() != nullptr, "just checking");
764
765 // Execute thread entry point unless this thread has a pending exception.
766 // Note: Due to JVMTI StopThread we can have pending exceptions already!
767 if (!this->has_pending_exception()) {
768 {
769 ResourceMark rm(this);
770 this->set_native_thread_name(this->name());
771 }
772 HandleMark hm(this);
773 this->entry_point()(this, this);
774 }
775
776 DTRACE_THREAD_PROBE(stop, this);
777
778 // Cleanup is handled in post_run()
779 }
780
781 // Shared teardown for all JavaThreads
782 void JavaThread::post_run() {
783 this->exit(false);
784 this->unregister_thread_stack_with_NMT();
785 // Defer deletion to here to ensure 'this' is still referenceable in call_run
786 // for any shared tear-down.
787 this->smr_delete();
788 }
789
790 static void ensure_join(JavaThread* thread) {
791 // We do not need to grab the Threads_lock, since we are operating on ourself.
792 Handle threadObj(thread, thread->threadObj());
793 assert(threadObj.not_null(), "java thread object must exist");
794 ObjectLocker lock(threadObj, thread);
795 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
796 java_lang_Thread::set_thread_status(threadObj(), JavaThreadStatus::TERMINATED);
797 // Clear the native thread instance - this makes isAlive return false and allows the join()
798 // to complete once we've done the notify_all below. Needs a release() to obey Java Memory Model
799 // requirements.
800 assert(java_lang_Thread::thread(threadObj()) == thread, "must be alive");
801 java_lang_Thread::release_set_thread(threadObj(), nullptr);
802 lock.notify_all(thread);
803 // Ignore pending exception, since we are exiting anyway
804 thread->clear_pending_exception();
805 }
806
807 static bool is_daemon(oop threadObj) {
808 return (threadObj != nullptr && java_lang_Thread::is_daemon(threadObj));
809 }
810
811 // For any new cleanup additions, please check to see if they need to be applied to
812 // cleanup_failed_attach_current_thread as well.
813 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
814 assert(this == JavaThread::current(), "thread consistency check");
815 assert(!is_exiting(), "should not be exiting or terminated already");
816
817 elapsedTimer _timer_exit_phase1;
818 elapsedTimer _timer_exit_phase2;
819 elapsedTimer _timer_exit_phase3;
820 elapsedTimer _timer_exit_phase4;
821
822 om_clear_monitor_cache();
823
824 if (log_is_enabled(Debug, os, thread, timer)) {
825 _timer_exit_phase1.start();
826 }
827
828 HandleMark hm(this);
829 Handle uncaught_exception(this, this->pending_exception());
830 this->clear_pending_exception();
831 Handle threadObj(this, this->threadObj());
832 assert(threadObj.not_null(), "Java thread object should be created");
833
834 if (!destroy_vm) {
835 if (uncaught_exception.not_null()) {
836 EXCEPTION_MARK;
837 // Call method Thread.dispatchUncaughtException().
838 Klass* thread_klass = vmClasses::Thread_klass();
839 JavaValue result(T_VOID);
840 JavaCalls::call_virtual(&result,
841 threadObj, thread_klass,
842 vmSymbols::dispatchUncaughtException_name(),
843 vmSymbols::throwable_void_signature(),
844 uncaught_exception,
845 THREAD);
846 if (HAS_PENDING_EXCEPTION) {
847 ResourceMark rm(this);
848 jio_fprintf(defaultStream::error_stream(),
849 "\nException: %s thrown from the UncaughtExceptionHandler"
850 " in thread \"%s\"\n",
851 pending_exception()->klass()->external_name(),
852 name());
853 CLEAR_PENDING_EXCEPTION;
854 }
855 }
856
857 if (!is_Compiler_thread()) {
858 // We have finished executing user-defined Java code and now have to do the
859 // implementation specific clean-up by calling Thread.exit(). We prevent any
860 // asynchronous exceptions from being delivered while in Thread.exit()
861 // to ensure the clean-up is not corrupted.
862 NoAsyncExceptionDeliveryMark _no_async(this);
863
864 EXCEPTION_MARK;
865 JavaValue result(T_VOID);
866 Klass* thread_klass = vmClasses::Thread_klass();
867 JavaCalls::call_virtual(&result,
868 threadObj, thread_klass,
869 vmSymbols::exit_method_name(),
870 vmSymbols::void_method_signature(),
871 THREAD);
872 CLEAR_PENDING_EXCEPTION;
873 }
874
875 // notify JVMTI
876 if (JvmtiExport::should_post_thread_life()) {
877 JvmtiExport::post_thread_end(this);
878 }
879 } else {
880 // before_exit() has already posted JVMTI THREAD_END events
881 }
882
883 // Cleanup any pending async exception now since we cannot access oops after
884 // BarrierSet::barrier_set()->on_thread_detach() has been executed.
885 if (has_async_exception_condition()) {
886 handshake_state()->clean_async_exception_operation();
887 }
888
889 // The careful dance between thread suspension and exit is handled here.
890 // Since we are in thread_in_vm state and suspension is done with handshakes,
891 // we can just put in the exiting state and it will be correctly handled.
892 // Also, no more async exceptions will be added to the queue after this point.
893 set_terminated(_thread_exiting);
894 ThreadService::current_thread_exiting(this, is_daemon(threadObj()));
895
896 if (log_is_enabled(Debug, os, thread, timer)) {
897 _timer_exit_phase1.stop();
898 _timer_exit_phase2.start();
899 }
900
901 // Capture daemon status before the thread is marked as terminated.
902 bool daemon = is_daemon(threadObj());
903
904 // Notify waiters on thread object. This has to be done after exit() is called
905 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
906 // group should have the destroyed bit set before waiters are notified).
907 ensure_join(this);
908 assert(!this->has_pending_exception(), "ensure_join should have cleared");
909
910 if (log_is_enabled(Debug, os, thread, timer)) {
911 _timer_exit_phase2.stop();
912 _timer_exit_phase3.start();
913 }
914 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
915 // held by this thread must be released. The spec does not distinguish
916 // between JNI-acquired and regular Java monitors. We can only see
917 // regular Java monitors here if monitor enter-exit matching is broken.
918 //
919 // ensure_join() ignores IllegalThreadStateExceptions, and so does
920 // ObjectSynchronizer::release_monitors_owned_by_thread().
921 if (exit_type == jni_detach) {
922 // Sanity check even though JNI DetachCurrentThread() would have
923 // returned JNI_ERR if there was a Java frame. JavaThread exit
924 // should be done executing Java code by the time we get here.
925 assert(!this->has_last_Java_frame(),
926 "should not have a Java frame when detaching or exiting");
927 ObjectSynchronizer::release_monitors_owned_by_thread(this);
928 assert(!this->has_pending_exception(), "release_monitors should have cleared");
929 // Check for monitor counts being out of sync.
930 assert(held_monitor_count() == jni_monitor_count(),
931 "held monitor count should be equal to jni: %zd != %zd",
932 held_monitor_count(), jni_monitor_count());
933 // All in-use monitors, including JNI-locked ones, should have been released above.
934 assert(held_monitor_count() == 0, "Failed to unlock %zd object monitors",
935 held_monitor_count());
936 } else {
937 // Check for monitor counts being out of sync.
938 assert(held_monitor_count() == jni_monitor_count(),
939 "held monitor count should be equal to jni: %zd != %zd",
940 held_monitor_count(), jni_monitor_count());
941 // It is possible that a terminating thread failed to unlock monitors it locked
942 // via JNI so we don't assert the count is zero.
943 }
944
945 if (CheckJNICalls && jni_monitor_count() > 0) {
946 // We would like a fatal here, but due to we never checked this before there
947 // is a lot of tests which breaks, even with an error log.
948 log_debug(jni)("JavaThread %s (tid: %zu) with Objects still locked by JNI MonitorEnter.",
949 exit_type == JavaThread::normal_exit ? "exiting" : "detaching", os::current_thread_id());
950 }
951
952 // These things needs to be done while we are still a Java Thread. Make sure that thread
953 // is in a consistent state, in case GC happens
954 JFR_ONLY(Jfr::on_thread_exit(this);)
955
956 if (active_handles() != nullptr) {
957 JNIHandleBlock* block = active_handles();
958 set_active_handles(nullptr);
959 JNIHandleBlock::release_block(block);
960 }
961
962 if (free_handle_block() != nullptr) {
963 JNIHandleBlock* block = free_handle_block();
964 set_free_handle_block(nullptr);
965 JNIHandleBlock::release_block(block);
966 }
967
968 // These have to be removed while this is still a valid thread.
969 _stack_overflow_state.remove_stack_guard_pages();
970
971 if (UseTLAB) {
972 tlab().retire();
973 }
974
975 if (JvmtiEnv::environments_might_exist()) {
976 JvmtiExport::cleanup_thread(this);
977 }
978
979 // We need to cache the thread name for logging purposes below as once
980 // we have called on_thread_detach this thread must not access any oops.
981 char* thread_name = nullptr;
982 if (log_is_enabled(Debug, os, thread, timer)) {
983 ResourceMark rm(this);
984 thread_name = os::strdup(name());
985 }
986
987 if (log_is_enabled(Info, os, thread)) {
988 ResourceMark rm(this);
989 log_info(os, thread)("JavaThread %s (name: \"%s\", tid: %zu).",
990 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
991 name(), os::current_thread_id());
992 }
993
994 if (log_is_enabled(Debug, os, thread, timer)) {
995 _timer_exit_phase3.stop();
996 _timer_exit_phase4.start();
997 }
998
999 #if INCLUDE_JVMCI
1000 if (JVMCICounterSize > 0) {
1001 if (jvmci_counters_include(this)) {
1002 for (int i = 0; i < JVMCICounterSize; i++) {
1003 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1004 }
1005 }
1006 }
1007 #endif // INCLUDE_JVMCI
1008
1009 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread.
1010 // We call BarrierSet::barrier_set()->on_thread_detach() here so no touching of oops after this point.
1011 Threads::remove(this, daemon);
1012
1013 if (log_is_enabled(Debug, os, thread, timer)) {
1014 _timer_exit_phase4.stop();
1015 log_debug(os, thread, timer)("name='%s'"
1016 ", exit-phase1=" JLONG_FORMAT
1017 ", exit-phase2=" JLONG_FORMAT
1018 ", exit-phase3=" JLONG_FORMAT
1019 ", exit-phase4=" JLONG_FORMAT,
1020 thread_name,
1021 _timer_exit_phase1.milliseconds(),
1022 _timer_exit_phase2.milliseconds(),
1023 _timer_exit_phase3.milliseconds(),
1024 _timer_exit_phase4.milliseconds());
1025 os::free(thread_name);
1026 }
1027 }
1028
1029 void JavaThread::cleanup_failed_attach_current_thread(bool is_daemon) {
1030 if (active_handles() != nullptr) {
1031 JNIHandleBlock* block = active_handles();
1032 set_active_handles(nullptr);
1033 JNIHandleBlock::release_block(block);
1034 }
1035
1036 if (free_handle_block() != nullptr) {
1037 JNIHandleBlock* block = free_handle_block();
1038 set_free_handle_block(nullptr);
1039 JNIHandleBlock::release_block(block);
1040 }
1041
1042 // These have to be removed while this is still a valid thread.
1043 _stack_overflow_state.remove_stack_guard_pages();
1044
1045 if (UseTLAB) {
1046 tlab().retire();
1047 }
1048
1049 Threads::remove(this, is_daemon);
1050 }
1051
1052 JavaThread* JavaThread::active() {
1053 Thread* thread = Thread::current();
1054 if (thread->is_Java_thread()) {
1055 return JavaThread::cast(thread);
1056 } else {
1057 assert(thread->is_VM_thread(), "this must be a vm thread");
1058 VM_Operation* op = ((VMThread*) thread)->vm_operation();
1059 JavaThread *ret = op == nullptr ? nullptr : JavaThread::cast(op->calling_thread());
1060 return ret;
1061 }
1062 }
1063
1064 bool JavaThread::is_lock_owned(address adr) const {
1065 assert(LockingMode != LM_LIGHTWEIGHT, "should not be called with new lightweight locking");
1066 return is_in_full_stack(adr);
1067 }
1068
1069 oop JavaThread::exception_oop() const {
1070 return Atomic::load(&_exception_oop);
1071 }
1072
1073 void JavaThread::set_exception_oop(oop o) {
1074 Atomic::store(&_exception_oop, o);
1075 }
1076
1077 void JavaThread::handle_special_runtime_exit_condition() {
1078 if (is_obj_deopt_suspend()) {
1079 frame_anchor()->make_walkable();
1080 wait_for_object_deoptimization();
1081 }
1082 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
1083 }
1084
1085
1086 // Asynchronous exceptions support
1087 //
1088 void JavaThread::handle_async_exception(oop java_throwable) {
1089 assert(java_throwable != nullptr, "should have an _async_exception to throw");
1090 assert(!is_at_poll_safepoint(), "should have never called this method");
1091
1092 if (has_last_Java_frame()) {
1093 frame f = last_frame();
1094 if (f.is_runtime_frame()) {
1095 // If the topmost frame is a runtime stub, then we are calling into
1096 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
1097 // must deoptimize the caller before continuing, as the compiled exception
1098 // handler table may not be valid.
1099 RegisterMap reg_map(this,
1100 RegisterMap::UpdateMap::skip,
1101 RegisterMap::ProcessFrames::include,
1102 RegisterMap::WalkContinuation::skip);
1103 frame compiled_frame = f.sender(®_map);
1104 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
1105 Deoptimization::deoptimize(this, compiled_frame);
1106 }
1107 }
1108 }
1109
1110 // We cannot call Exceptions::_throw(...) here because we cannot block
1111 set_pending_exception(java_throwable, __FILE__, __LINE__);
1112
1113 clear_scopedValueBindings();
1114
1115 LogTarget(Info, exceptions) lt;
1116 if (lt.is_enabled()) {
1117 ResourceMark rm;
1118 LogStream ls(lt);
1119 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
1120 if (has_last_Java_frame()) {
1121 frame f = last_frame();
1122 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
1123 }
1124 ls.print_cr(" of type: %s", java_throwable->klass()->external_name());
1125 }
1126 }
1127
1128 void JavaThread::install_async_exception(AsyncExceptionHandshake* aeh) {
1129 // Do not throw asynchronous exceptions against the compiler thread
1130 // or if the thread is already exiting.
1131 if (!can_call_java() || is_exiting()) {
1132 delete aeh;
1133 return;
1134 }
1135
1136 oop exception = aeh->exception();
1137 Handshake::execute(aeh, this); // Install asynchronous handshake
1138
1139 ResourceMark rm;
1140 if (log_is_enabled(Info, exceptions)) {
1141 log_info(exceptions)("Pending Async. exception installed of type: %s",
1142 InstanceKlass::cast(exception->klass())->external_name());
1143 }
1144 // for AbortVMOnException flag
1145 Exceptions::debug_check_abort(exception->klass()->external_name());
1146
1147 oop vt_oop = vthread();
1148 if (vt_oop == nullptr || !vt_oop->is_a(vmClasses::BaseVirtualThread_klass())) {
1149 // Interrupt thread so it will wake up from a potential wait()/sleep()/park()
1150 java_lang_Thread::set_interrupted(threadObj(), true);
1151 this->interrupt();
1152 }
1153 }
1154
1155 class InstallAsyncExceptionHandshake : public HandshakeClosure {
1156 AsyncExceptionHandshake* _aeh;
1157 public:
1158 InstallAsyncExceptionHandshake(AsyncExceptionHandshake* aeh) :
1159 HandshakeClosure("InstallAsyncException"), _aeh(aeh) {}
1160 ~InstallAsyncExceptionHandshake() {
1161 // If InstallAsyncExceptionHandshake was never executed we need to clean up _aeh.
1162 delete _aeh;
1163 }
1164 void do_thread(Thread* thr) {
1165 JavaThread* target = JavaThread::cast(thr);
1166 target->install_async_exception(_aeh);
1167 _aeh = nullptr;
1168 }
1169 };
1170
1171 void JavaThread::send_async_exception(JavaThread* target, oop java_throwable) {
1172 OopHandle e(Universe::vm_global(), java_throwable);
1173 InstallAsyncExceptionHandshake iaeh(new AsyncExceptionHandshake(e));
1174 Handshake::execute(&iaeh, target);
1175 }
1176
1177 #if INCLUDE_JVMTI
1178 void JavaThread::set_is_in_VTMS_transition(bool val) {
1179 assert(is_in_VTMS_transition() != val, "already %s transition", val ? "inside" : "outside");
1180 _is_in_VTMS_transition = val;
1181 }
1182
1183 #ifdef ASSERT
1184 void JavaThread::set_is_VTMS_transition_disabler(bool val) {
1185 _is_VTMS_transition_disabler = val;
1186 }
1187 #endif
1188 #endif
1189
1190 // External suspension mechanism.
1191 //
1192 // Guarantees on return (for a valid target thread):
1193 // - Target thread will not execute any new bytecode.
1194 // - Target thread will not enter any new monitors.
1195 //
1196 bool JavaThread::java_suspend() {
1197 #if INCLUDE_JVMTI
1198 // Suspending a JavaThread in VTMS transition or disabling VTMS transitions can cause deadlocks.
1199 assert(!is_in_VTMS_transition(), "no suspend allowed in VTMS transition");
1200 assert(!is_VTMS_transition_disabler(), "no suspend allowed for VTMS transition disablers");
1201 #endif
1202
1203 guarantee(Thread::is_JavaThread_protected(/* target */ this),
1204 "target JavaThread is not protected in calling context.");
1205 return this->handshake_state()->suspend();
1206 }
1207
1208 bool JavaThread::java_resume() {
1209 guarantee(Thread::is_JavaThread_protected_by_TLH(/* target */ this),
1210 "missing ThreadsListHandle in calling context.");
1211 return this->handshake_state()->resume();
1212 }
1213
1214 // Wait for another thread to perform object reallocation and relocking on behalf of
1215 // this thread. The current thread is required to change to _thread_blocked in order
1216 // to be seen to be safepoint/handshake safe whilst suspended and only after becoming
1217 // handshake safe, the other thread can complete the handshake used to synchronize
1218 // with this thread and then perform the reallocation and relocking.
1219 // See EscapeBarrier::sync_and_suspend_*()
1220
1221 void JavaThread::wait_for_object_deoptimization() {
1222 assert(!has_last_Java_frame() || frame_anchor()->walkable(), "should have walkable stack");
1223 assert(this == Thread::current(), "invariant");
1224
1225 bool spin_wait = os::is_MP();
1226 do {
1227 ThreadBlockInVM tbivm(this, true /* allow_suspend */);
1228 // Wait for object deoptimization if requested.
1229 if (spin_wait) {
1230 // A single deoptimization is typically very short. Microbenchmarks
1231 // showed 5% better performance when spinning.
1232 const uint spin_limit = 10 * SpinYield::default_spin_limit;
1233 SpinYield spin(spin_limit);
1234 for (uint i = 0; is_obj_deopt_suspend() && i < spin_limit; i++) {
1235 spin.wait();
1236 }
1237 // Spin just once
1238 spin_wait = false;
1239 } else {
1240 MonitorLocker ml(this, EscapeBarrier_lock, Monitor::_no_safepoint_check_flag);
1241 if (is_obj_deopt_suspend()) {
1242 ml.wait();
1243 }
1244 }
1245 // A handshake for obj. deoptimization suspend could have been processed so
1246 // we must check after processing.
1247 } while (is_obj_deopt_suspend());
1248 }
1249
1250 #ifdef ASSERT
1251 // Verify the JavaThread has not yet been published in the Threads::list, and
1252 // hence doesn't need protection from concurrent access at this stage.
1253 void JavaThread::verify_not_published() {
1254 // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
1255 // since an unpublished JavaThread doesn't participate in the
1256 // Thread-SMR protocol for keeping a ThreadsList alive.
1257 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
1258 }
1259 #endif
1260
1261 // Slow path when the native==>Java barriers detect a safepoint/handshake is
1262 // pending, when _suspend_flags is non-zero or when we need to process a stack
1263 // watermark. Also check for pending async exceptions (except unsafe access error).
1264 // Note only the native==>Java barriers can call this function when thread state
1265 // is _thread_in_native_trans.
1266 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
1267 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
1268 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "Unwalkable stack in native->Java transition");
1269
1270 thread->set_thread_state(_thread_in_vm);
1271
1272 // Enable WXWrite: called directly from interpreter native wrapper.
1273 MACOS_AARCH64_ONLY(ThreadWXEnable wx(WXWrite, thread));
1274
1275 SafepointMechanism::process_if_requested_with_exit_check(thread, true /* check asyncs */);
1276
1277 // After returning from native, it could be that the stack frames are not
1278 // yet safe to use. We catch such situations in the subsequent stack watermark
1279 // barrier, which will trap unsafe stack frames.
1280 StackWatermarkSet::before_unwind(thread);
1281 }
1282
1283 #ifndef PRODUCT
1284 // Deoptimization
1285 // Function for testing deoptimization
1286 void JavaThread::deoptimize() {
1287 StackFrameStream fst(this, false /* update */, true /* process_frames */);
1288 bool deopt = false; // Dump stack only if a deopt actually happens.
1289 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
1290 // Iterate over all frames in the thread and deoptimize
1291 for (; !fst.is_done(); fst.next()) {
1292 if (fst.current()->can_be_deoptimized()) {
1293
1294 if (only_at) {
1295 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
1296 // consists of comma or carriage return separated numbers so
1297 // search for the current bci in that string.
1298 address pc = fst.current()->pc();
1299 nmethod* nm = fst.current()->cb()->as_nmethod();
1300 ScopeDesc* sd = nm->scope_desc_at(pc);
1301 char buffer[8];
1302 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
1303 size_t len = strlen(buffer);
1304 const char * found = strstr(DeoptimizeOnlyAt, buffer);
1305 while (found != nullptr) {
1306 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
1307 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
1308 // Check that the bci found is bracketed by terminators.
1309 break;
1310 }
1311 found = strstr(found + 1, buffer);
1312 }
1313 if (!found) {
1314 continue;
1315 }
1316 }
1317
1318 if (DebugDeoptimization && !deopt) {
1319 deopt = true; // One-time only print before deopt
1320 tty->print_cr("[BEFORE Deoptimization]");
1321 trace_frames();
1322 trace_stack();
1323 }
1324 Deoptimization::deoptimize(this, *fst.current());
1325 }
1326 }
1327
1328 if (DebugDeoptimization && deopt) {
1329 tty->print_cr("[AFTER Deoptimization]");
1330 trace_frames();
1331 }
1332 }
1333
1334
1335 // Make zombies
1336 void JavaThread::make_zombies() {
1337 for (StackFrameStream fst(this, true /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
1338 if (fst.current()->can_be_deoptimized()) {
1339 // it is a Java nmethod
1340 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
1341 assert(nm != nullptr, "did not find nmethod");
1342 nm->make_not_entrant("zombie");
1343 }
1344 }
1345 }
1346 #endif // PRODUCT
1347
1348
1349 void JavaThread::deoptimize_marked_methods() {
1350 if (!has_last_Java_frame()) return;
1351 StackFrameStream fst(this, false /* update */, true /* process_frames */);
1352 for (; !fst.is_done(); fst.next()) {
1353 if (fst.current()->should_be_deoptimized()) {
1354 Deoptimization::deoptimize(this, *fst.current());
1355 }
1356 }
1357 }
1358
1359 #ifdef ASSERT
1360 void JavaThread::verify_frame_info() {
1361 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
1362 (has_last_Java_frame() && java_call_counter() > 0),
1363 "unexpected frame info: has_last_frame=%s, java_call_counter=%d",
1364 has_last_Java_frame() ? "true" : "false", java_call_counter());
1365 }
1366 #endif
1367
1368 // Push on a new block of JNI handles.
1369 void JavaThread::push_jni_handle_block() {
1370 // Allocate a new block for JNI handles.
1371 // Inlined code from jni_PushLocalFrame()
1372 JNIHandleBlock* old_handles = active_handles();
1373 JNIHandleBlock* new_handles = JNIHandleBlock::allocate_block(this);
1374 assert(old_handles != nullptr && new_handles != nullptr, "should not be null");
1375 new_handles->set_pop_frame_link(old_handles); // make sure java handles get gc'd.
1376 set_active_handles(new_handles);
1377 }
1378
1379 // Pop off the current block of JNI handles.
1380 void JavaThread::pop_jni_handle_block() {
1381 // Release our JNI handle block
1382 JNIHandleBlock* old_handles = active_handles();
1383 JNIHandleBlock* new_handles = old_handles->pop_frame_link();
1384 assert(new_handles != nullptr, "should never set active handles to null");
1385 set_active_handles(new_handles);
1386 old_handles->set_pop_frame_link(nullptr);
1387 JNIHandleBlock::release_block(old_handles, this);
1388 }
1389
1390 void JavaThread::oops_do_no_frames(OopClosure* f, NMethodClosure* cf) {
1391 // Verify that the deferred card marks have been flushed.
1392 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
1393
1394 // Traverse the GCHandles
1395 Thread::oops_do_no_frames(f, cf);
1396
1397 if (active_handles() != nullptr) {
1398 active_handles()->oops_do(f);
1399 }
1400
1401 DEBUG_ONLY(verify_frame_info();)
1402
1403 assert(vframe_array_head() == nullptr, "deopt in progress at a safepoint!");
1404 // If we have deferred set_locals there might be oops waiting to be
1405 // written
1406 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = JvmtiDeferredUpdates::deferred_locals(this);
1407 if (list != nullptr) {
1408 for (int i = 0; i < list->length(); i++) {
1409 list->at(i)->oops_do(f);
1410 }
1411 }
1412
1413 // Traverse instance variables at the end since the GC may be moving things
1414 // around using this function
1415 f->do_oop((oop*) &_vm_result);
1416 f->do_oop((oop*) &_exception_oop);
1417 #if INCLUDE_JVMCI
1418 f->do_oop((oop*) &_jvmci_reserved_oop0);
1419
1420 if (_live_nmethod != nullptr && cf != nullptr) {
1421 cf->do_nmethod(_live_nmethod);
1422 }
1423 #endif
1424
1425 if (jvmti_thread_state() != nullptr) {
1426 jvmti_thread_state()->oops_do(f, cf);
1427 }
1428
1429 // The continuation oops are really on the stack. But there is typically at most
1430 // one of those per thread, so we handle them here in the oops_do_no_frames part
1431 // so that we don't have to sprinkle as many stack watermark checks where these
1432 // oops are used. We just need to make sure the thread has started processing.
1433 ContinuationEntry* entry = _cont_entry;
1434 while (entry != nullptr) {
1435 f->do_oop((oop*)entry->cont_addr());
1436 f->do_oop((oop*)entry->chunk_addr());
1437 entry = entry->parent();
1438 }
1439
1440 if (LockingMode == LM_LIGHTWEIGHT) {
1441 lock_stack().oops_do(f);
1442 }
1443 }
1444
1445 void JavaThread::oops_do_frames(OopClosure* f, NMethodClosure* cf) {
1446 if (!has_last_Java_frame()) {
1447 return;
1448 }
1449 // Finish any pending lazy GC activity for the frames
1450 StackWatermarkSet::finish_processing(this, nullptr /* context */, StackWatermarkKind::gc);
1451 // Traverse the execution stack
1452 for (StackFrameStream fst(this, true /* update */, false /* process_frames */); !fst.is_done(); fst.next()) {
1453 fst.current()->oops_do(f, cf, fst.register_map());
1454 }
1455 }
1456
1457 #ifdef ASSERT
1458 void JavaThread::verify_states_for_handshake() {
1459 // This checks that the thread has a correct frame state during a handshake.
1460 verify_frame_info();
1461 }
1462 #endif
1463
1464 void JavaThread::nmethods_do(NMethodClosure* cf) {
1465 DEBUG_ONLY(verify_frame_info();)
1466 MACOS_AARCH64_ONLY(ThreadWXEnable wx(WXWrite, Thread::current());)
1467
1468 if (has_last_Java_frame()) {
1469 // Traverse the execution stack
1470 for (StackFrameStream fst(this, true /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
1471 fst.current()->nmethod_do(cf);
1472 }
1473 }
1474
1475 if (jvmti_thread_state() != nullptr) {
1476 jvmti_thread_state()->nmethods_do(cf);
1477 }
1478
1479 #if INCLUDE_JVMCI
1480 if (_live_nmethod != nullptr) {
1481 cf->do_nmethod(_live_nmethod);
1482 }
1483 #endif
1484 }
1485
1486 void JavaThread::metadata_do(MetadataClosure* f) {
1487 if (has_last_Java_frame()) {
1488 // Traverse the execution stack to call f() on the methods in the stack
1489 for (StackFrameStream fst(this, true /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
1490 fst.current()->metadata_do(f);
1491 }
1492 } else if (is_Compiler_thread()) {
1493 // need to walk ciMetadata in current compile tasks to keep alive.
1494 CompilerThread* ct = (CompilerThread*)this;
1495 if (ct->env() != nullptr) {
1496 ct->env()->metadata_do(f);
1497 }
1498 CompileTask* task = ct->task();
1499 if (task != nullptr) {
1500 task->metadata_do(f);
1501 }
1502 }
1503 }
1504
1505 // Printing
1506 static const char* _get_thread_state_name(JavaThreadState _thread_state) {
1507 switch (_thread_state) {
1508 case _thread_uninitialized: return "_thread_uninitialized";
1509 case _thread_new: return "_thread_new";
1510 case _thread_new_trans: return "_thread_new_trans";
1511 case _thread_in_native: return "_thread_in_native";
1512 case _thread_in_native_trans: return "_thread_in_native_trans";
1513 case _thread_in_vm: return "_thread_in_vm";
1514 case _thread_in_vm_trans: return "_thread_in_vm_trans";
1515 case _thread_in_Java: return "_thread_in_Java";
1516 case _thread_in_Java_trans: return "_thread_in_Java_trans";
1517 case _thread_blocked: return "_thread_blocked";
1518 case _thread_blocked_trans: return "_thread_blocked_trans";
1519 default: return "unknown thread state";
1520 }
1521 }
1522
1523 void JavaThread::print_thread_state_on(outputStream *st) const {
1524 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
1525 }
1526
1527 // Called by Threads::print() for VM_PrintThreads operation
1528 void JavaThread::print_on(outputStream *st, bool print_extended_info) const {
1529 st->print_raw("\"");
1530 st->print_raw(name());
1531 st->print_raw("\" ");
1532 oop thread_oop = threadObj();
1533 if (thread_oop != nullptr) {
1534 st->print("#" INT64_FORMAT " [%ld] ", (int64_t)java_lang_Thread::thread_id(thread_oop), (long) osthread()->thread_id());
1535 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
1536 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
1537 }
1538 Thread::print_on(st, print_extended_info);
1539 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
1540 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
1541 if (thread_oop != nullptr) {
1542 if (is_vthread_mounted()) {
1543 st->print_cr(" Carrying virtual thread #" INT64_FORMAT, java_lang_Thread::thread_id(vthread()));
1544 } else {
1545 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
1546 }
1547 }
1548 #ifndef PRODUCT
1549 _safepoint_state->print_on(st);
1550 #endif // PRODUCT
1551 if (is_Compiler_thread()) {
1552 CompileTask *task = ((CompilerThread*)this)->task();
1553 if (task != nullptr) {
1554 st->print(" Compiling: ");
1555 task->print(st, nullptr, true, false);
1556 } else {
1557 st->print(" No compile task");
1558 }
1559 st->cr();
1560 }
1561 }
1562
1563 void JavaThread::print() const { print_on(tty); }
1564
1565 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
1566 st->print("%s", get_thread_name_string(buf, buflen));
1567 }
1568
1569 // Called by fatal error handler. The difference between this and
1570 // JavaThread::print() is that we can't grab lock or allocate memory.
1571 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
1572 st->print("%s \"%s\"", type_name(), get_thread_name_string(buf, buflen));
1573 Thread* current = Thread::current_or_null_safe();
1574 assert(current != nullptr, "cannot be called by a detached thread");
1575 st->fill_to(60);
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 oop thread_obj = threadObj();
1580 if (thread_obj != nullptr) {
1581 st->print(java_lang_Thread::is_daemon(thread_obj) ? " daemon" : " ");
1582 }
1583 }
1584 st->print(" [");
1585 st->print("%s", _get_thread_state_name(_thread_state));
1586 if (osthread()) {
1587 st->print(", id=%d", osthread()->thread_id());
1588 }
1589 // Use raw field members for stack base/size as this could be
1590 // called before a thread has run enough to initialize them.
1591 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ") (" PROPERFMT ")",
1592 p2i(_stack_base - _stack_size), p2i(_stack_base),
1593 PROPERFMTARGS(_stack_size));
1594 st->print("]");
1595
1596 ThreadsSMRSupport::print_info_on(this, st);
1597 return;
1598 }
1599
1600
1601 // Verification
1602
1603 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
1604 // ignore if there is no stack
1605 if (!has_last_Java_frame()) return;
1606 // traverse the stack frames. Starts from top frame.
1607 for (StackFrameStream fst(this, true /* update_map */, true /* process_frames */, false /* walk_cont */); !fst.is_done(); fst.next()) {
1608 frame* fr = fst.current();
1609 f(fr, fst.register_map());
1610 }
1611 }
1612
1613 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
1614
1615 void JavaThread::verify() {
1616 // Verify oops in the thread.
1617 oops_do(&VerifyOopClosure::verify_oop, nullptr);
1618
1619 // Verify the stack frames.
1620 frames_do(frame_verify);
1621 }
1622
1623 // CR 6300358 (sub-CR 2137150)
1624 // Most callers of this method assume that it can't return null but a
1625 // thread may not have a name whilst it is in the process of attaching to
1626 // the VM - see CR 6412693, and there are places where a JavaThread can be
1627 // seen prior to having its threadObj set (e.g., JNI attaching threads and
1628 // if vm exit occurs during initialization). These cases can all be accounted
1629 // for such that this method never returns null.
1630 const char* JavaThread::name() const {
1631 if (Thread::is_JavaThread_protected(/* target */ this)) {
1632 // The target JavaThread is protected so get_thread_name_string() is safe:
1633 return get_thread_name_string();
1634 }
1635
1636 // The target JavaThread is not protected so we return the default:
1637 return Thread::name();
1638 }
1639
1640 // Like name() but doesn't include the protection check. This must only be
1641 // called when it is known to be safe, even though the protection check can't tell
1642 // that e.g. when this thread is the init_thread() - see instanceKlass.cpp.
1643 const char* JavaThread::name_raw() const {
1644 return get_thread_name_string();
1645 }
1646
1647 // Returns a non-null representation of this thread's name, or a suitable
1648 // descriptive string if there is no set name.
1649 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
1650 const char* name_str;
1651 #ifdef ASSERT
1652 Thread* current = Thread::current_or_null_safe();
1653 assert(current != nullptr, "cannot be called by a detached thread");
1654 if (!current->is_Java_thread() || JavaThread::cast(current)->is_oop_safe()) {
1655 // Only access threadObj() if current thread is not a JavaThread
1656 // or if it is a JavaThread that can safely access oops.
1657 #endif
1658 oop thread_obj = threadObj();
1659 if (thread_obj != nullptr) {
1660 oop name = java_lang_Thread::name(thread_obj);
1661 if (name != nullptr) {
1662 if (buf == nullptr) {
1663 name_str = java_lang_String::as_utf8_string(name);
1664 } else {
1665 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
1666 }
1667 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
1668 name_str = "<no-name - thread is attaching>";
1669 } else {
1670 name_str = "<un-named>";
1671 }
1672 } else {
1673 name_str = Thread::name();
1674 }
1675 #ifdef ASSERT
1676 } else {
1677 // Current JavaThread has exited...
1678 if (current == this) {
1679 // ... and is asking about itself:
1680 name_str = "<no-name - current JavaThread has exited>";
1681 } else {
1682 // ... and it can't safely determine this JavaThread's name so
1683 // use the default thread name.
1684 name_str = Thread::name();
1685 }
1686 }
1687 #endif
1688 assert(name_str != nullptr, "unexpected null thread name");
1689 return name_str;
1690 }
1691
1692 // Helper to extract the name from the thread oop for logging.
1693 const char* JavaThread::name_for(oop thread_obj) {
1694 assert(thread_obj != nullptr, "precondition");
1695 oop name = java_lang_Thread::name(thread_obj);
1696 const char* name_str;
1697 if (name != nullptr) {
1698 name_str = java_lang_String::as_utf8_string(name);
1699 } else {
1700 name_str = "<un-named>";
1701 }
1702 return name_str;
1703 }
1704
1705 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
1706
1707 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
1708 assert(NoPriority <= prio && prio <= MaxPriority, "sanity check");
1709 // Link Java Thread object <-> C++ Thread
1710
1711 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
1712 // and put it into a new Handle. The Handle "thread_oop" can then
1713 // be used to pass the C++ thread object to other methods.
1714
1715 // Set the Java level thread object (jthread) field of the
1716 // new thread (a JavaThread *) to C++ thread object using the
1717 // "thread_oop" handle.
1718
1719 // Set the thread field (a JavaThread *) of the
1720 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
1721
1722 Handle thread_oop(Thread::current(),
1723 JNIHandles::resolve_non_null(jni_thread));
1724 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
1725 "must be initialized");
1726 set_threadOopHandles(thread_oop());
1727 set_monitor_owner_id(java_lang_Thread::thread_id(thread_oop()));
1728
1729 if (prio == NoPriority) {
1730 prio = java_lang_Thread::priority(thread_oop());
1731 assert(prio != NoPriority, "A valid priority should be present");
1732 }
1733
1734 // Push the Java priority down to the native thread; needs Threads_lock
1735 Thread::set_priority(this, prio);
1736
1737 // Add the new thread to the Threads list and set it in motion.
1738 // We must have threads lock in order to call Threads::add.
1739 // It is crucial that we do not block before the thread is
1740 // added to the Threads list for if a GC happens, then the java_thread oop
1741 // will not be visited by GC.
1742 Threads::add(this);
1743 // Publish the JavaThread* in java.lang.Thread after the JavaThread* is
1744 // on a ThreadsList. We don't want to wait for the release when the
1745 // Theads_lock is dropped somewhere in the caller since the JavaThread*
1746 // is already visible to JVM/TI via the ThreadsList.
1747 java_lang_Thread::release_set_thread(thread_oop(), this);
1748 }
1749
1750 oop JavaThread::current_park_blocker() {
1751 // Support for JSR-166 locks
1752 oop thread_oop = threadObj();
1753 if (thread_oop != nullptr) {
1754 return java_lang_Thread::park_blocker(thread_oop);
1755 }
1756 return nullptr;
1757 }
1758
1759 // Print current stack trace for checked JNI warnings and JNI fatal errors.
1760 // This is the external format, selecting the platform or vthread
1761 // as applicable, and allowing for a native-only stack.
1762 void JavaThread::print_jni_stack() {
1763 assert(this == JavaThread::current(), "Can't print stack of other threads");
1764 if (!has_last_Java_frame()) {
1765 ResourceMark rm(this);
1766 char* buf = NEW_RESOURCE_ARRAY_RETURN_NULL(char, O_BUFLEN);
1767 if (buf == nullptr) {
1768 tty->print_cr("Unable to print native stack - out of memory");
1769 return;
1770 }
1771 NativeStackPrinter nsp(this);
1772 address lastpc = nullptr;
1773 nsp.print_stack(tty, buf, O_BUFLEN, lastpc,
1774 true /*print_source_info */, -1 /* max stack */ );
1775 } else {
1776 print_active_stack_on(tty);
1777 }
1778 }
1779
1780 void JavaThread::print_stack_on(outputStream* st) {
1781 if (!has_last_Java_frame()) return;
1782
1783 Thread* current_thread = Thread::current();
1784 ResourceMark rm(current_thread);
1785 HandleMark hm(current_thread);
1786
1787 RegisterMap reg_map(this,
1788 RegisterMap::UpdateMap::include,
1789 RegisterMap::ProcessFrames::include,
1790 RegisterMap::WalkContinuation::skip);
1791 vframe* start_vf = platform_thread_last_java_vframe(®_map);
1792 int count = 0;
1793 for (vframe* f = start_vf; f != nullptr; f = f->sender()) {
1794 if (f->is_java_frame()) {
1795 javaVFrame* jvf = javaVFrame::cast(f);
1796 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
1797
1798 // Print out lock information
1799 if (JavaMonitorsInStackTrace) {
1800 jvf->print_lock_info_on(st, count);
1801 }
1802 } else {
1803 // Ignore non-Java frames
1804 }
1805
1806 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
1807 count++;
1808 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
1809 }
1810 }
1811
1812 void JavaThread::print_vthread_stack_on(outputStream* st) {
1813 assert(is_vthread_mounted(), "Caller should have checked this");
1814 assert(has_last_Java_frame(), "must be");
1815
1816 Thread* current_thread = Thread::current();
1817 ResourceMark rm(current_thread);
1818 HandleMark hm(current_thread);
1819
1820 RegisterMap reg_map(this,
1821 RegisterMap::UpdateMap::include,
1822 RegisterMap::ProcessFrames::include,
1823 RegisterMap::WalkContinuation::include);
1824 ContinuationEntry* cont_entry = last_continuation();
1825 vframe* start_vf = last_java_vframe(®_map);
1826 int count = 0;
1827 for (vframe* f = start_vf; f != nullptr; f = f->sender()) {
1828 // Watch for end of vthread stack
1829 if (Continuation::is_continuation_enterSpecial(f->fr())) {
1830 assert(cont_entry == Continuation::get_continuation_entry_for_entry_frame(this, f->fr()), "");
1831 if (cont_entry->is_virtual_thread()) {
1832 break;
1833 }
1834 cont_entry = cont_entry->parent();
1835 }
1836 if (f->is_java_frame()) {
1837 javaVFrame* jvf = javaVFrame::cast(f);
1838 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
1839
1840 // Print out lock information
1841 if (JavaMonitorsInStackTrace) {
1842 jvf->print_lock_info_on(st, count);
1843 }
1844 } else {
1845 // Ignore non-Java frames
1846 }
1847
1848 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
1849 count++;
1850 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
1851 }
1852 }
1853
1854 void JavaThread::print_active_stack_on(outputStream* st) {
1855 if (is_vthread_mounted()) {
1856 print_vthread_stack_on(st);
1857 } else {
1858 print_stack_on(st);
1859 }
1860 }
1861
1862 #if INCLUDE_JVMTI
1863 // Rebind JVMTI thread state from carrier to virtual or from virtual to carrier.
1864 JvmtiThreadState* JavaThread::rebind_to_jvmti_thread_state_of(oop thread_oop) {
1865 set_jvmti_vthread(thread_oop);
1866
1867 // unbind current JvmtiThreadState from JavaThread
1868 JvmtiThreadState::unbind_from(jvmti_thread_state(), this);
1869
1870 // bind new JvmtiThreadState to JavaThread
1871 JvmtiThreadState::bind_to(java_lang_Thread::jvmti_thread_state(thread_oop), this);
1872
1873 // enable interp_only_mode for virtual or carrier thread if it has pending bit
1874 JvmtiThreadState::process_pending_interp_only(this);
1875
1876 return jvmti_thread_state();
1877 }
1878 #endif
1879
1880 // JVMTI PopFrame support
1881 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
1882 assert(_popframe_preserved_args == nullptr, "should not wipe out old PopFrame preserved arguments");
1883 if (in_bytes(size_in_bytes) != 0) {
1884 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
1885 _popframe_preserved_args_size = in_bytes(size_in_bytes);
1886 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
1887 }
1888 }
1889
1890 void* JavaThread::popframe_preserved_args() {
1891 return _popframe_preserved_args;
1892 }
1893
1894 ByteSize JavaThread::popframe_preserved_args_size() {
1895 return in_ByteSize(_popframe_preserved_args_size);
1896 }
1897
1898 WordSize JavaThread::popframe_preserved_args_size_in_words() {
1899 int sz = in_bytes(popframe_preserved_args_size());
1900 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
1901 return in_WordSize(sz / wordSize);
1902 }
1903
1904 void JavaThread::popframe_free_preserved_args() {
1905 assert(_popframe_preserved_args != nullptr, "should not free PopFrame preserved arguments twice");
1906 FREE_C_HEAP_ARRAY(char, (char*)_popframe_preserved_args);
1907 _popframe_preserved_args = nullptr;
1908 _popframe_preserved_args_size = 0;
1909 }
1910
1911 #ifndef PRODUCT
1912
1913 void JavaThread::trace_frames() {
1914 tty->print_cr("[Describe stack]");
1915 int frame_no = 1;
1916 for (StackFrameStream fst(this, true /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
1917 tty->print(" %d. ", frame_no++);
1918 fst.current()->print_value_on(tty);
1919 tty->cr();
1920 }
1921 }
1922
1923 class PrintAndVerifyOopClosure: public OopClosure {
1924 protected:
1925 template <class T> inline void do_oop_work(T* p) {
1926 oop obj = RawAccess<>::oop_load(p);
1927 if (obj == nullptr) return;
1928 tty->print(INTPTR_FORMAT ": ", p2i(p));
1929 if (oopDesc::is_oop_or_null(obj)) {
1930 if (obj->is_objArray()) {
1931 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
1932 } else {
1933 obj->print();
1934 }
1935 } else {
1936 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
1937 }
1938 tty->cr();
1939 }
1940 public:
1941 virtual void do_oop(oop* p) { do_oop_work(p); }
1942 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
1943 };
1944
1945 #ifdef ASSERT
1946 // Print or validate the layout of stack frames
1947 void JavaThread::print_frame_layout(int depth, bool validate_only) {
1948 ResourceMark rm;
1949 PreserveExceptionMark pm(this);
1950 FrameValues values;
1951 int frame_no = 0;
1952 for (StackFrameStream fst(this, true, true, true); !fst.is_done(); fst.next()) {
1953 fst.current()->describe(values, ++frame_no, fst.register_map());
1954 if (depth == frame_no) break;
1955 }
1956 Continuation::describe(values);
1957 if (validate_only) {
1958 values.validate();
1959 } else {
1960 tty->print_cr("[Describe stack layout]");
1961 values.print(this);
1962 }
1963 }
1964 #endif
1965
1966 void JavaThread::trace_stack_from(vframe* start_vf) {
1967 ResourceMark rm;
1968 int vframe_no = 1;
1969 for (vframe* f = start_vf; f; f = f->sender()) {
1970 if (f->is_java_frame()) {
1971 javaVFrame::cast(f)->print_activation(vframe_no++);
1972 } else {
1973 f->print();
1974 }
1975 if (vframe_no > StackPrintLimit) {
1976 tty->print_cr("...<more frames>...");
1977 return;
1978 }
1979 }
1980 }
1981
1982
1983 void JavaThread::trace_stack() {
1984 if (!has_last_Java_frame()) return;
1985 Thread* current_thread = Thread::current();
1986 ResourceMark rm(current_thread);
1987 HandleMark hm(current_thread);
1988 RegisterMap reg_map(this,
1989 RegisterMap::UpdateMap::include,
1990 RegisterMap::ProcessFrames::include,
1991 RegisterMap::WalkContinuation::skip);
1992 trace_stack_from(last_java_vframe(®_map));
1993 }
1994
1995
1996 #endif // PRODUCT
1997
1998 // Slow-path increment of the held monitor counts. JNI locking is always
1999 // this slow-path.
2000 void JavaThread::inc_held_monitor_count(intx i, bool jni) {
2001 #ifdef SUPPORT_MONITOR_COUNT
2002
2003 if (LockingMode != LM_LEGACY) {
2004 // Nothing to do. Just do some sanity check.
2005 assert(_held_monitor_count == 0, "counter should not be used");
2006 assert(_jni_monitor_count == 0, "counter should not be used");
2007 return;
2008 }
2009
2010 assert(_held_monitor_count >= 0, "Must always be non-negative: %zd", _held_monitor_count);
2011 _held_monitor_count += i;
2012 if (jni) {
2013 assert(_jni_monitor_count >= 0, "Must always be non-negative: %zd", _jni_monitor_count);
2014 _jni_monitor_count += i;
2015 }
2016 assert(_held_monitor_count >= _jni_monitor_count, "Monitor count discrepancy detected - held count "
2017 "%zd is less than JNI count %zd", _held_monitor_count, _jni_monitor_count);
2018 #endif // SUPPORT_MONITOR_COUNT
2019 }
2020
2021 // Slow-path decrement of the held monitor counts. JNI unlocking is always
2022 // this slow-path.
2023 void JavaThread::dec_held_monitor_count(intx i, bool jni) {
2024 #ifdef SUPPORT_MONITOR_COUNT
2025
2026 if (LockingMode != LM_LEGACY) {
2027 // Nothing to do. Just do some sanity check.
2028 assert(_held_monitor_count == 0, "counter should not be used");
2029 assert(_jni_monitor_count == 0, "counter should not be used");
2030 return;
2031 }
2032
2033 _held_monitor_count -= i;
2034 assert(_held_monitor_count >= 0, "Must always be non-negative: %zd", _held_monitor_count);
2035 if (jni) {
2036 _jni_monitor_count -= i;
2037 assert(_jni_monitor_count >= 0, "Must always be non-negative: %zd", _jni_monitor_count);
2038 }
2039 // When a thread is detaching with still owned JNI monitors, the logic that releases
2040 // the monitors doesn't know to set the "jni" flag and so the counts can get out of sync.
2041 // So we skip this assert if the thread is exiting. Once all monitors are unlocked the
2042 // JNI count is directly set to zero.
2043 assert(_held_monitor_count >= _jni_monitor_count || is_exiting(), "Monitor count discrepancy detected - held count "
2044 "%zd is less than JNI count %zd", _held_monitor_count, _jni_monitor_count);
2045 #endif // SUPPORT_MONITOR_COUNT
2046 }
2047
2048 frame JavaThread::vthread_last_frame() {
2049 assert (is_vthread_mounted(), "Virtual thread not mounted");
2050 return last_frame();
2051 }
2052
2053 frame JavaThread::carrier_last_frame(RegisterMap* reg_map) {
2054 const ContinuationEntry* entry = vthread_continuation();
2055 guarantee (entry != nullptr, "Not a carrier thread");
2056 frame f = entry->to_frame();
2057 if (reg_map->process_frames()) {
2058 entry->flush_stack_processing(this);
2059 }
2060 entry->update_register_map(reg_map);
2061 return f.sender(reg_map);
2062 }
2063
2064 frame JavaThread::platform_thread_last_frame(RegisterMap* reg_map) {
2065 return is_vthread_mounted() ? carrier_last_frame(reg_map) : last_frame();
2066 }
2067
2068 javaVFrame* JavaThread::last_java_vframe(const frame f, RegisterMap *reg_map) {
2069 assert(reg_map != nullptr, "a map must be given");
2070 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
2071 if (vf->is_java_frame()) return javaVFrame::cast(vf);
2072 }
2073 return nullptr;
2074 }
2075
2076 Klass* JavaThread::security_get_caller_class(int depth) {
2077 ResetNoHandleMark rnhm;
2078 HandleMark hm(Thread::current());
2079
2080 vframeStream vfst(this);
2081 vfst.security_get_caller_frame(depth);
2082 if (!vfst.at_end()) {
2083 return vfst.method()->method_holder();
2084 }
2085 return nullptr;
2086 }
2087
2088 // Internal convenience function for millisecond resolution sleeps.
2089 bool JavaThread::sleep(jlong millis) {
2090 jlong nanos;
2091 if (millis > max_jlong / NANOUNITS_PER_MILLIUNIT) {
2092 // Conversion to nanos would overflow, saturate at max
2093 nanos = max_jlong;
2094 } else {
2095 nanos = millis * NANOUNITS_PER_MILLIUNIT;
2096 }
2097 return sleep_nanos(nanos);
2098 }
2099
2100 // java.lang.Thread.sleep support
2101 // Returns true if sleep time elapsed as expected, and false
2102 // if the thread was interrupted.
2103 bool JavaThread::sleep_nanos(jlong nanos) {
2104 assert(this == Thread::current(), "thread consistency check");
2105 assert(nanos >= 0, "nanos are in range");
2106
2107 ParkEvent * const slp = this->_SleepEvent;
2108 // Because there can be races with thread interruption sending an unpark()
2109 // to the event, we explicitly reset it here to avoid an immediate return.
2110 // The actual interrupt state will be checked before we park().
2111 slp->reset();
2112 // Thread interruption establishes a happens-before ordering in the
2113 // Java Memory Model, so we need to ensure we synchronize with the
2114 // interrupt state.
2115 OrderAccess::fence();
2116
2117 jlong prevtime = os::javaTimeNanos();
2118
2119 jlong nanos_remaining = nanos;
2120
2121 for (;;) {
2122 // interruption has precedence over timing out
2123 if (this->is_interrupted(true)) {
2124 return false;
2125 }
2126
2127 if (nanos_remaining <= 0) {
2128 return true;
2129 }
2130
2131 {
2132 ThreadBlockInVM tbivm(this);
2133 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
2134 slp->park_nanos(nanos_remaining);
2135 }
2136
2137 // Update elapsed time tracking
2138 jlong newtime = os::javaTimeNanos();
2139 if (newtime - prevtime < 0) {
2140 // time moving backwards, should only happen if no monotonic clock
2141 // not a guarantee() because JVM should not abort on kernel/glibc bugs
2142 assert(false,
2143 "unexpected time moving backwards detected in JavaThread::sleep()");
2144 } else {
2145 nanos_remaining -= (newtime - prevtime);
2146 }
2147 prevtime = newtime;
2148 }
2149 }
2150
2151 // Last thread running calls java.lang.Shutdown.shutdown()
2152 void JavaThread::invoke_shutdown_hooks() {
2153 HandleMark hm(this);
2154
2155 // We could get here with a pending exception, if so clear it now.
2156 if (this->has_pending_exception()) {
2157 this->clear_pending_exception();
2158 }
2159
2160 EXCEPTION_MARK;
2161 Klass* shutdown_klass =
2162 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
2163 THREAD);
2164 if (shutdown_klass != nullptr) {
2165 // SystemDictionary::resolve_or_null will return null if there was
2166 // an exception. If we cannot load the Shutdown class, just don't
2167 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
2168 // won't be run. Note that if a shutdown hook was registered,
2169 // the Shutdown class would have already been loaded
2170 // (Runtime.addShutdownHook will load it).
2171 JavaValue result(T_VOID);
2172 JavaCalls::call_static(&result,
2173 shutdown_klass,
2174 vmSymbols::shutdown_name(),
2175 vmSymbols::void_method_signature(),
2176 THREAD);
2177 }
2178 CLEAR_PENDING_EXCEPTION;
2179 }
2180
2181 #ifndef PRODUCT
2182 void JavaThread::verify_cross_modify_fence_failure(JavaThread *thread) {
2183 report_vm_error(__FILE__, __LINE__, "Cross modify fence failure", "%p", thread);
2184 }
2185 #endif
2186
2187 // Helper function to create the java.lang.Thread object for a
2188 // VM-internal thread. The thread will have the given name, and be
2189 // a member of the "system" ThreadGroup.
2190 Handle JavaThread::create_system_thread_object(const char* name, TRAPS) {
2191 Handle string = java_lang_String::create_from_str(name, CHECK_NH);
2192
2193 // Initialize thread_oop to put it into the system threadGroup.
2194 // This is done by calling the Thread(ThreadGroup group, String name) constructor.
2195 Handle thread_group(THREAD, Universe::system_thread_group());
2196 Handle thread_oop =
2197 JavaCalls::construct_new_instance(vmClasses::Thread_klass(),
2198 vmSymbols::threadgroup_string_void_signature(),
2199 thread_group,
2200 string,
2201 CHECK_NH);
2202
2203 return thread_oop;
2204 }
2205
2206 // Starts the target JavaThread as a daemon of the given priority, and
2207 // bound to the given java.lang.Thread instance.
2208 // The Threads_lock is held for the duration.
2209 void JavaThread::start_internal_daemon(JavaThread* current, JavaThread* target,
2210 Handle thread_oop, ThreadPriority prio) {
2211
2212 assert(target->osthread() != nullptr, "target thread is not properly initialized");
2213
2214 MutexLocker mu(current, Threads_lock);
2215
2216 // Initialize the fields of the thread_oop first.
2217 if (prio != NoPriority) {
2218 java_lang_Thread::set_priority(thread_oop(), prio);
2219 // Note: we don't call os::set_priority here. Possibly we should,
2220 // else all threads should call it themselves when they first run.
2221 }
2222
2223 java_lang_Thread::set_daemon(thread_oop());
2224
2225 // Now bind the thread_oop to the target JavaThread.
2226 target->set_threadOopHandles(thread_oop());
2227 target->set_monitor_owner_id(java_lang_Thread::thread_id(thread_oop()));
2228
2229 Threads::add(target); // target is now visible for safepoint/handshake
2230 // Publish the JavaThread* in java.lang.Thread after the JavaThread* is
2231 // on a ThreadsList. We don't want to wait for the release when the
2232 // Theads_lock is dropped when the 'mu' destructor is run since the
2233 // JavaThread* is already visible to JVM/TI via the ThreadsList.
2234
2235 assert(java_lang_Thread::thread(thread_oop()) == nullptr, "must not be alive");
2236 java_lang_Thread::release_set_thread(thread_oop(), target); // isAlive == true now
2237 Thread::start(target);
2238 }
2239
2240 void JavaThread::vm_exit_on_osthread_failure(JavaThread* thread) {
2241 // At this point it may be possible that no osthread was created for the
2242 // JavaThread due to lack of resources. However, since this must work
2243 // for critical system threads just check and abort if this fails.
2244 if (thread->osthread() == nullptr) {
2245 // This isn't really an OOM condition, but historically this is what
2246 // we report.
2247 vm_exit_during_initialization("java.lang.OutOfMemoryError",
2248 os::native_thread_creation_failed_msg());
2249 }
2250 }
2251
2252 void JavaThread::pretouch_stack() {
2253 // Given an established java thread stack with usable area followed by
2254 // shadow zone and reserved/yellow/red zone, pretouch the usable area ranging
2255 // from the current frame down to the start of the shadow zone.
2256 const address end = _stack_overflow_state.shadow_zone_safe_limit();
2257 if (is_in_full_stack(end)) {
2258 char* p1 = (char*) alloca(1);
2259 address here = (address) &p1;
2260 if (is_in_full_stack(here) && here > end) {
2261 size_t to_alloc = here - end;
2262 char* p2 = (char*) alloca(to_alloc);
2263 log_trace(os, thread)("Pretouching thread stack for %zu: " RANGEFMT ".",
2264 (uintx) osthread()->thread_id(), RANGEFMTARGS(p2, to_alloc));
2265 os::pretouch_memory(p2, p2 + to_alloc,
2266 NOT_AIX(os::vm_page_size()) AIX_ONLY(4096));
2267 }
2268 }
2269 }
2270
2271 // Deferred OopHandle release support.
2272
2273 class OopHandleList : public CHeapObj<mtInternal> {
2274 static const int _count = 4;
2275 OopHandle _handles[_count];
2276 OopHandleList* _next;
2277 int _index;
2278 public:
2279 OopHandleList(OopHandleList* next) : _next(next), _index(0) {}
2280 void add(OopHandle h) {
2281 assert(_index < _count, "too many additions");
2282 _handles[_index++] = h;
2283 }
2284 ~OopHandleList() {
2285 assert(_index == _count, "usage error");
2286 for (int i = 0; i < _index; i++) {
2287 _handles[i].release(JavaThread::thread_oop_storage());
2288 }
2289 }
2290 OopHandleList* next() const { return _next; }
2291 };
2292
2293 OopHandleList* JavaThread::_oop_handle_list = nullptr;
2294
2295 // Called by the ServiceThread to do the work of releasing
2296 // the OopHandles.
2297 void JavaThread::release_oop_handles() {
2298 OopHandleList* list;
2299 {
2300 MutexLocker ml(Service_lock, Mutex::_no_safepoint_check_flag);
2301 list = _oop_handle_list;
2302 _oop_handle_list = nullptr;
2303 }
2304 assert(!SafepointSynchronize::is_at_safepoint(), "cannot be called at a safepoint");
2305
2306 while (list != nullptr) {
2307 OopHandleList* l = list;
2308 list = l->next();
2309 delete l;
2310 }
2311 }
2312
2313 // Add our OopHandles for later release.
2314 void JavaThread::add_oop_handles_for_release() {
2315 MutexLocker ml(Service_lock, Mutex::_no_safepoint_check_flag);
2316 OopHandleList* new_head = new OopHandleList(_oop_handle_list);
2317 new_head->add(_threadObj);
2318 new_head->add(_vthread);
2319 new_head->add(_jvmti_vthread);
2320 new_head->add(_scopedValueCache);
2321 _oop_handle_list = new_head;
2322 Service_lock->notify_all();
2323 }
2324
2325 #if INCLUDE_JFR
2326 void JavaThread::set_last_freeze_fail_result(freeze_result result) {
2327 assert(result != freeze_ok, "sanity check");
2328 _last_freeze_fail_result = result;
2329 _last_freeze_fail_time = Ticks::now();
2330 }
2331
2332 // Post jdk.VirtualThreadPinned event
2333 void JavaThread::post_vthread_pinned_event(EventVirtualThreadPinned* event, const char* op, freeze_result result) {
2334 assert(result != freeze_ok, "sanity check");
2335 if (event->should_commit()) {
2336 char reason[256];
2337 if (class_to_be_initialized() != nullptr) {
2338 ResourceMark rm(this);
2339 jio_snprintf(reason, sizeof reason, "Waited for initialization of %s by another thread",
2340 class_to_be_initialized()->external_name());
2341 event->set_pinnedReason(reason);
2342 } else if (class_being_initialized() != nullptr) {
2343 ResourceMark rm(this);
2344 jio_snprintf(reason, sizeof(reason), "VM call to %s.<clinit> on stack",
2345 class_being_initialized()->external_name());
2346 event->set_pinnedReason(reason);
2347 } else if (result == freeze_pinned_native) {
2348 event->set_pinnedReason("Native or VM frame on stack");
2349 } else {
2350 jio_snprintf(reason, sizeof(reason), "Freeze or preempt failed (%d)", result);
2351 event->set_pinnedReason(reason);
2352 }
2353 event->set_blockingOperation(op);
2354 event->set_carrierThread(JFR_JVM_THREAD_ID(this));
2355 event->commit();
2356 }
2357 }
2358 #endif