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/instanceKlass.hpp"
51 #include "oops/klass.inline.hpp"
52 #include "oops/oop.inline.hpp"
53 #include "oops/oopHandle.inline.hpp"
54 #include "oops/verifyOopClosure.hpp"
55 #include "prims/jvm_misc.hpp"
56 #include "prims/jvmtiDeferredUpdates.hpp"
57 #include "prims/jvmtiExport.hpp"
58 #include "prims/jvmtiThreadState.inline.hpp"
59 #include "runtime/atomic.hpp"
60 #include "runtime/continuation.hpp"
61 #include "runtime/continuationEntry.inline.hpp"
62 #include "runtime/continuationHelper.inline.hpp"
63 #include "runtime/deoptimization.hpp"
64 #include "runtime/frame.inline.hpp"
65 #include "runtime/handles.inline.hpp"
66 #include "runtime/handshake.hpp"
67 #include "runtime/interfaceSupport.inline.hpp"
68 #include "runtime/java.hpp"
69 #include "runtime/javaCalls.hpp"
70 #include "runtime/javaThread.inline.hpp"
71 #include "runtime/jniHandles.inline.hpp"
72 #include "runtime/lockStack.inline.hpp"
73 #include "runtime/mutexLocker.hpp"
74 #include "runtime/orderAccess.hpp"
75 #include "runtime/os.inline.hpp"
76 #include "runtime/osThread.hpp"
77 #include "runtime/safepoint.hpp"
78 #include "runtime/safepointMechanism.inline.hpp"
79 #include "runtime/safepointVerifiers.hpp"
80 #include "runtime/serviceThread.hpp"
81 #include "runtime/stackFrameStream.inline.hpp"
82 #include "runtime/stackWatermarkSet.hpp"
83 #include "runtime/synchronizer.hpp"
84 #include "runtime/threadCritical.hpp"
85 #include "runtime/threadIdentifier.hpp"
86 #include "runtime/threadSMR.inline.hpp"
87 #include "runtime/threadStatisticalInfo.hpp"
88 #include "runtime/threadWXSetters.inline.hpp"
89 #include "runtime/timer.hpp"
90 #include "runtime/timerTrace.hpp"
91 #include "runtime/vframe.inline.hpp"
92 #include "runtime/vframeArray.hpp"
93 #include "runtime/vframe_hp.hpp"
94 #include "runtime/vmThread.hpp"
95 #include "runtime/vmOperations.hpp"
96 #include "services/threadService.hpp"
97 #include "utilities/copy.hpp"
98 #include "utilities/defaultStream.hpp"
99 #include "utilities/dtrace.hpp"
100 #include "utilities/events.hpp"
101 #include "utilities/macros.hpp"
102 #include "utilities/nativeStackPrinter.hpp"
103 #include "utilities/preserveException.hpp"
104 #include "utilities/spinYield.hpp"
105 #include "utilities/vmError.hpp"
106 #if INCLUDE_JVMCI
107 #include "jvmci/jvmci.hpp"
108 #include "jvmci/jvmciEnv.hpp"
109 #endif
110 #if INCLUDE_JFR
111 #include "jfr/jfr.hpp"
112 #endif
113
114 // Set by os layer.
115 size_t JavaThread::_stack_size_at_create = 0;
116
117 #ifdef DTRACE_ENABLED
118
119 // Only bother with this argument setup if dtrace is available
120
121 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
122 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
123
124 #define DTRACE_THREAD_PROBE(probe, javathread) \
125 { \
126 ResourceMark rm(this); \
127 int len = 0; \
128 const char* name = (javathread)->name(); \
129 len = strlen(name); \
130 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
131 (char *) name, len, \
132 java_lang_Thread::thread_id((javathread)->threadObj()), \
133 (uintptr_t) (javathread)->osthread()->thread_id(), \
134 java_lang_Thread::is_daemon((javathread)->threadObj())); \
135 }
136
137 #else // ndef DTRACE_ENABLED
138
139 #define DTRACE_THREAD_PROBE(probe, javathread)
140
141 #endif // ndef DTRACE_ENABLED
142
143 void JavaThread::smr_delete() {
144 if (_on_thread_list) {
145 ThreadsSMRSupport::smr_delete(this);
146 } else {
147 delete this;
148 }
149 }
150
151 // Initialized by VMThread at vm_global_init
152 OopStorage* JavaThread::_thread_oop_storage = nullptr;
153
154 OopStorage* JavaThread::thread_oop_storage() {
155 assert(_thread_oop_storage != nullptr, "not yet initialized");
156 return _thread_oop_storage;
157 }
158
159 void JavaThread::set_threadOopHandles(oop p) {
160 assert(_thread_oop_storage != nullptr, "not yet initialized");
161 _threadObj = OopHandle(_thread_oop_storage, p);
162 _vthread = OopHandle(_thread_oop_storage, p);
163 _jvmti_vthread = OopHandle(_thread_oop_storage, p->is_a(vmClasses::BoundVirtualThread_klass()) ? p : nullptr);
164 _scopedValueCache = OopHandle(_thread_oop_storage, nullptr);
165 }
166
167 oop JavaThread::threadObj() const {
168 // Ideally we would verify the current thread is oop_safe when this is called, but as we can
169 // be called from a signal handler we would have to use Thread::current_or_null_safe(). That
170 // has overhead and also interacts poorly with GetLastError on Windows due to the use of TLS.
171 // Instead callers must verify oop safe access.
172 return _threadObj.resolve();
173 }
174
175 oop JavaThread::vthread() const {
176 return _vthread.resolve();
177 }
178
179 void JavaThread::set_vthread(oop p) {
180 assert(_thread_oop_storage != nullptr, "not yet initialized");
181 _vthread.replace(p);
182 }
183
184 oop JavaThread::jvmti_vthread() const {
185 return _jvmti_vthread.resolve();
186 }
187
188 void JavaThread::set_jvmti_vthread(oop p) {
189 assert(_thread_oop_storage != nullptr, "not yet initialized");
190 _jvmti_vthread.replace(p);
191 }
192
193 // If there is a virtual thread mounted then return vthread() oop.
194 // Otherwise, return threadObj().
195 oop JavaThread::vthread_or_thread() const {
196 oop result = vthread();
197 if (result == nullptr) {
198 result = threadObj();
199 }
200 return result;
201 }
202
203 oop JavaThread::scopedValueCache() const {
204 return _scopedValueCache.resolve();
205 }
206
207 void JavaThread::set_scopedValueCache(oop p) {
208 if (!_scopedValueCache.is_empty()) { // i.e. if the OopHandle has been allocated
209 _scopedValueCache.replace(p);
210 } else {
211 assert(p == nullptr, "not yet initialized");
212 }
213 }
214
215 void JavaThread::clear_scopedValueBindings() {
216 set_scopedValueCache(nullptr);
217 oop vthread_oop = vthread();
218 // vthread may be null here if we get a VM error during startup,
219 // before the java.lang.Thread instance has been created.
220 if (vthread_oop != nullptr) {
221 java_lang_Thread::clear_scopedValueBindings(vthread_oop);
222 }
223 }
224
225 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
226 bool daemon, TRAPS) {
227 assert(thread_group.not_null(), "thread group should be specified");
228 assert(threadObj() == nullptr, "should only create Java thread object once");
229
230 InstanceKlass* ik = vmClasses::Thread_klass();
231 assert(ik->is_initialized(), "must be");
232 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
233
234 // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon.
235 // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread
236 // constructor calls Thread.current(), which must be set here.
237 java_lang_Thread::set_thread(thread_oop(), this);
238 set_threadOopHandles(thread_oop());
239 // Set the _monitor_owner_id to the next thread_id temporarily while initialization runs.
240 set_monitor_owner_id(ThreadIdentifier::next());
241
242 JavaValue result(T_VOID);
243 if (thread_name != nullptr) {
244 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
245 // Thread gets assigned specified name and null target
246 JavaCalls::call_special(&result,
247 thread_oop,
248 ik,
249 vmSymbols::object_initializer_name(),
250 vmSymbols::threadgroup_string_void_signature(),
251 thread_group,
252 name,
253 CHECK);
254 } else {
255 // Thread gets assigned name "Thread-nnn" and null target
256 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
257 JavaCalls::call_special(&result,
258 thread_oop,
259 ik,
260 vmSymbols::object_initializer_name(),
261 vmSymbols::threadgroup_runnable_void_signature(),
262 thread_group,
263 Handle(),
264 CHECK);
265 }
266 // Update the _monitor_owner_id with the tid value.
267 set_monitor_owner_id(java_lang_Thread::thread_id(thread_oop()));
268
269 os::set_priority(this, NormPriority);
270
271 if (daemon) {
272 java_lang_Thread::set_daemon(thread_oop());
273 }
274 }
275
276 // ======= JavaThread ========
277
278 #if INCLUDE_JVMCI
279
280 jlong* JavaThread::_jvmci_old_thread_counters;
281
282 static bool jvmci_counters_include(JavaThread* thread) {
283 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
284 }
285
286 void JavaThread::collect_counters(jlong* array, int length) {
287 assert(length == JVMCICounterSize, "wrong value");
288 for (int i = 0; i < length; i++) {
289 array[i] = _jvmci_old_thread_counters[i];
290 }
291 for (JavaThread* tp : ThreadsListHandle()) {
292 if (jvmci_counters_include(tp)) {
293 for (int i = 0; i < length; i++) {
294 array[i] += tp->_jvmci_counters[i];
295 }
296 }
297 }
298 }
299
300 // Attempt to enlarge the array for per thread counters.
301 static jlong* resize_counters_array(jlong* old_counters, int current_size, int new_size) {
302 jlong* new_counters = NEW_C_HEAP_ARRAY_RETURN_NULL(jlong, new_size, mtJVMCI);
303 if (new_counters == nullptr) {
304 return nullptr;
305 }
306 if (old_counters == nullptr) {
307 old_counters = new_counters;
308 memset(old_counters, 0, sizeof(jlong) * new_size);
309 } else {
310 for (int i = 0; i < MIN2((int) current_size, new_size); i++) {
311 new_counters[i] = old_counters[i];
312 }
313 if (new_size > current_size) {
314 memset(new_counters + current_size, 0, sizeof(jlong) * (new_size - current_size));
315 }
316 FREE_C_HEAP_ARRAY(jlong, old_counters);
317 }
318 return new_counters;
319 }
320
321 // Attempt to enlarge the array for per thread counters.
322 bool JavaThread::resize_counters(int current_size, int new_size) {
323 jlong* new_counters = resize_counters_array(_jvmci_counters, current_size, new_size);
324 if (new_counters == nullptr) {
325 return false;
326 } else {
327 _jvmci_counters = new_counters;
328 return true;
329 }
330 }
331
332 class VM_JVMCIResizeCounters : public VM_Operation {
333 private:
334 int _new_size;
335 bool _failed;
336
337 public:
338 VM_JVMCIResizeCounters(int new_size) : _new_size(new_size), _failed(false) { }
339 VMOp_Type type() const { return VMOp_JVMCIResizeCounters; }
340 bool allow_nested_vm_operations() const { return true; }
341 void doit() {
342 // Resize the old thread counters array
343 jlong* new_counters = resize_counters_array(JavaThread::_jvmci_old_thread_counters, JVMCICounterSize, _new_size);
344 if (new_counters == nullptr) {
345 _failed = true;
346 return;
347 } else {
348 JavaThread::_jvmci_old_thread_counters = new_counters;
349 }
350
351 // Now resize each threads array
352 for (JavaThread* tp : ThreadsListHandle()) {
353 if (!tp->resize_counters(JVMCICounterSize, _new_size)) {
354 _failed = true;
355 break;
356 }
357 }
358 if (!_failed) {
359 JVMCICounterSize = _new_size;
360 }
361 }
362
363 bool failed() { return _failed; }
364 };
365
366 bool JavaThread::resize_all_jvmci_counters(int new_size) {
367 VM_JVMCIResizeCounters op(new_size);
368 VMThread::execute(&op);
369 return !op.failed();
370 }
371
372 #endif // INCLUDE_JVMCI
373
374 #ifdef ASSERT
375 // Checks safepoint allowed and clears unhandled oops at potential safepoints.
376 void JavaThread::check_possible_safepoint() {
377 if (_no_safepoint_count > 0) {
378 print_owned_locks();
379 assert(false, "Possible safepoint reached by thread that does not allow it");
380 }
381 #ifdef CHECK_UNHANDLED_OOPS
382 // Clear unhandled oops in JavaThreads so we get a crash right away.
383 clear_unhandled_oops();
384 #endif // CHECK_UNHANDLED_OOPS
385
386 // Macos/aarch64 should be in the right state for safepoint (e.g.
387 // deoptimization needs WXWrite). Crashes caused by the wrong state rarely
388 // happens in practice, making such issues hard to find and reproduce.
389 #if defined(__APPLE__) && defined(AARCH64)
390 if (AssertWXAtThreadSync) {
391 assert_wx_state(WXWrite);
392 }
393 #endif
394 }
395
396 void JavaThread::check_for_valid_safepoint_state() {
397 // Don't complain if running a debugging command.
398 if (DebuggingContext::is_enabled()) return;
399
400 // Check NoSafepointVerifier, which is implied by locks taken that can be
401 // shared with the VM thread. This makes sure that no locks with allow_vm_block
402 // are held.
403 check_possible_safepoint();
404
405 if (thread_state() != _thread_in_vm) {
406 fatal("LEAF method calling lock?");
407 }
408
409 if (GCALotAtAllSafepoints) {
410 // We could enter a safepoint here and thus have a gc
411 InterfaceSupport::check_gc_alot();
412 }
413 }
414 #endif // ASSERT
415
416 // A JavaThread is a normal Java thread
417
418 JavaThread::JavaThread(MemTag mem_tag) :
419 Thread(mem_tag),
420 // Initialize fields
421 _on_thread_list(false),
422 DEBUG_ONLY(_java_call_counter(0) COMMA)
423 _entry_point(nullptr),
424 _deopt_mark(nullptr),
425 _deopt_nmethod(nullptr),
426 _vframe_array_head(nullptr),
427 _vframe_array_last(nullptr),
428 _jvmti_deferred_updates(nullptr),
429 _callee_target(nullptr),
430 _vm_result(nullptr),
431 _vm_result_2(nullptr),
432
433 _current_pending_monitor(nullptr),
434 _current_pending_monitor_is_from_java(true),
435 _current_waiting_monitor(nullptr),
436 _active_handles(nullptr),
437 _free_handle_block(nullptr),
438 _monitor_owner_id(0),
439
440 _suspend_flags(0),
441
442 _thread_state(_thread_new),
443 _saved_exception_pc(nullptr),
444 #ifdef ASSERT
445 _no_safepoint_count(0),
446 _visited_for_critical_count(false),
447 #endif
448
449 _terminated(_not_terminated),
450 _in_deopt_handler(0),
451 _doing_unsafe_access(false),
452 _do_not_unlock_if_synchronized(false),
453 #if INCLUDE_JVMTI
454 _carrier_thread_suspended(false),
455 _is_in_VTMS_transition(false),
456 _is_disable_suspend(false),
457 _VTMS_transition_mark(false),
458 _on_monitor_waited_event(false),
459 _contended_entered_monitor(nullptr),
460 #ifdef ASSERT
461 _is_VTMS_transition_disabler(false),
462 #endif
463 #endif
464 _jni_attach_state(_not_attaching_via_jni),
465 _is_in_internal_oome_mark(false),
466 #if INCLUDE_JVMCI
467 _pending_deoptimization(-1),
468 _pending_monitorenter(false),
469 _pending_transfer_to_interpreter(false),
470 _pending_failed_speculation(0),
471 _jvmci{nullptr},
472 _libjvmci_runtime(nullptr),
473 _jvmci_counters(nullptr),
474 _jvmci_reserved0(0),
475 _jvmci_reserved1(0),
476 _jvmci_reserved_oop0(nullptr),
477 _live_nmethod(nullptr),
478 #endif // INCLUDE_JVMCI
479
480 _exception_oop(oop()),
481 _exception_pc(nullptr),
482 _exception_handler_pc(nullptr),
483 _is_method_handle_return(0),
484
485 _jni_active_critical(0),
486 _pending_jni_exception_check_fn(nullptr),
487 _depth_first_number(0),
488
489 // JVMTI PopFrame support
490 _popframe_condition(popframe_inactive),
491 _frames_to_pop_failed_realloc(0),
492
493 _cont_entry(nullptr),
494 _cont_fastpath(nullptr),
495 _cont_fastpath_thread_state(1),
496 _held_monitor_count(0),
497 _jni_monitor_count(0),
498 _unlocked_inflated_monitor(nullptr),
499
500 _can_call_java(true),
501
502 _preempt_alternate_return(nullptr),
503 _preemption_cancelled(false),
504 _pending_interrupted_exception(false),
505
506 _handshake(this),
507
508 _popframe_preserved_args(nullptr),
509 _popframe_preserved_args_size(0),
510
511 _jvmti_thread_state(nullptr),
512 _interp_only_mode(0),
513 _should_post_on_exceptions_flag(JNI_FALSE),
514 _thread_stat(new ThreadStatistics()),
515
516 _parker(),
517
518 _class_to_be_initialized(nullptr),
519 _class_being_initialized(nullptr),
520
521 _SleepEvent(ParkEvent::Allocate(this)),
522
523 #if INCLUDE_JFR
524 _last_freeze_fail_result(freeze_ok),
525 #endif
526
527 _lock_stack(this),
528 _om_cache(this) {
529 set_jni_functions(jni_functions());
530
531 #if INCLUDE_JVMCI
532 assert(_jvmci._implicit_exception_pc == nullptr, "must be");
533 if (JVMCICounterSize > 0) {
534 resize_counters(0, (int) JVMCICounterSize);
535 }
536 #endif // INCLUDE_JVMCI
537
538 // Setup safepoint state info for this thread
539 ThreadSafepointState::create(this);
540
541 SafepointMechanism::initialize_header(this);
542
543 set_requires_cross_modify_fence(false);
544
545 pd_initialize();
546 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
547 }
548
549 JavaThread* JavaThread::create_attaching_thread() {
550 JavaThread* jt = new JavaThread();
551 jt->_jni_attach_state = _attaching_via_jni;
552 return jt;
553 }
554
555 // interrupt support
556
557 void JavaThread::interrupt() {
558 // All callers should have 'this' thread protected by a
559 // ThreadsListHandle so that it cannot terminate and deallocate
560 // itself.
561 debug_only(check_for_dangling_thread_pointer(this);)
562
563 // For Windows _interrupt_event
564 WINDOWS_ONLY(osthread()->set_interrupted(true);)
565
566 // For Thread.sleep
567 _SleepEvent->unpark();
568
569 // For JSR166 LockSupport.park
570 parker()->unpark();
571
572 // For ObjectMonitor and JvmtiRawMonitor
573 _ParkEvent->unpark();
574 }
575
576 bool JavaThread::is_interrupted(bool clear_interrupted) {
577 debug_only(check_for_dangling_thread_pointer(this);)
578
579 if (_threadObj.peek() == nullptr) {
580 // If there is no j.l.Thread then it is impossible to have
581 // been interrupted. We can find null during VM initialization
582 // or when a JNI thread is still in the process of attaching.
583 // In such cases this must be the current thread.
584 assert(this == Thread::current(), "invariant");
585 return false;
586 }
587
588 bool interrupted = java_lang_Thread::interrupted(threadObj());
589
590 // NOTE that since there is no "lock" around the interrupt and
591 // is_interrupted operations, there is the possibility that the
592 // interrupted flag will be "false" but that the
593 // low-level events will be in the signaled state. This is
594 // intentional. The effect of this is that Object.wait() and
595 // LockSupport.park() will appear to have a spurious wakeup, which
596 // is allowed and not harmful, and the possibility is so rare that
597 // it is not worth the added complexity to add yet another lock.
598 // For the sleep event an explicit reset is performed on entry
599 // to JavaThread::sleep, so there is no early return. It has also been
600 // recommended not to put the interrupted flag into the "event"
601 // structure because it hides the issue.
602 // Also, because there is no lock, we must only clear the interrupt
603 // state if we are going to report that we were interrupted; otherwise
604 // an interrupt that happens just after we read the field would be lost.
605 if (interrupted && clear_interrupted) {
606 assert(this == Thread::current(), "only the current thread can clear");
607 java_lang_Thread::set_interrupted(threadObj(), false);
608 WINDOWS_ONLY(osthread()->set_interrupted(false);)
609 }
610 return interrupted;
611 }
612
613 // This is only for use by JVMTI RawMonitorWait. It emulates the actions of
614 // the Java code in Object::wait which are not present in RawMonitorWait.
615 bool JavaThread::get_and_clear_interrupted() {
616 if (!is_interrupted(false)) {
617 return false;
618 }
619 oop thread_oop = vthread_or_thread();
620 bool is_virtual = java_lang_VirtualThread::is_instance(thread_oop);
621
622 if (!is_virtual) {
623 return is_interrupted(true);
624 }
625 // Virtual thread: clear interrupt status for both virtual and
626 // carrier threads under the interruptLock protection.
627 JavaThread* current = JavaThread::current();
628 HandleMark hm(current);
629 Handle thread_h(current, thread_oop);
630 ObjectLocker lock(Handle(current, java_lang_Thread::interrupt_lock(thread_h())), current);
631
632 // re-check the interrupt status under the interruptLock protection
633 bool interrupted = java_lang_Thread::interrupted(thread_h());
634
635 if (interrupted) {
636 assert(this == Thread::current(), "only the current thread can clear");
637 java_lang_Thread::set_interrupted(thread_h(), false); // clear for virtual
638 java_lang_Thread::set_interrupted(threadObj(), false); // clear for carrier
639 WINDOWS_ONLY(osthread()->set_interrupted(false);)
640 }
641 return interrupted;
642 }
643
644 void JavaThread::block_if_vm_exited() {
645 if (_terminated == _vm_exited) {
646 // _vm_exited is set at safepoint, and Threads_lock is never released
647 // so we will block here forever.
648 // Here we can be doing a jump from a safe state to an unsafe state without
649 // proper transition, but it happens after the final safepoint has begun so
650 // this jump won't cause any safepoint problems.
651 set_thread_state(_thread_in_vm);
652 Threads_lock->lock();
653 ShouldNotReachHere();
654 }
655 }
656
657 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz, MemTag mem_tag) : JavaThread(mem_tag) {
658 set_entry_point(entry_point);
659 // Create the native thread itself.
660 // %note runtime_23
661 os::ThreadType thr_type = os::java_thread;
662 thr_type = entry_point == &CompilerThread::thread_entry ? os::compiler_thread :
663 os::java_thread;
664 os::create_thread(this, thr_type, stack_sz);
665 // The _osthread may be null here because we ran out of memory (too many threads active).
666 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
667 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
668 // the exception consists of creating the exception object & initializing it, initialization
669 // will leave the VM via a JavaCall and then all locks must be unlocked).
670 //
671 // The thread is still suspended when we reach here. Thread must be explicit started
672 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
673 // by calling Threads:add. The reason why this is not done here, is because the thread
674 // object must be fully initialized (take a look at JVM_Start)
675 }
676
677 JavaThread::~JavaThread() {
678
679 // Enqueue OopHandles for release by the service thread.
680 add_oop_handles_for_release();
681
682 // Return the sleep event to the free list
683 ParkEvent::Release(_SleepEvent);
684 _SleepEvent = nullptr;
685
686 // Free any remaining previous UnrollBlock
687 vframeArray* old_array = vframe_array_last();
688
689 if (old_array != nullptr) {
690 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
691 old_array->set_unroll_block(nullptr);
692 delete old_info;
693 delete old_array;
694 }
695
696 JvmtiDeferredUpdates* updates = deferred_updates();
697 if (updates != nullptr) {
698 // This can only happen if thread is destroyed before deoptimization occurs.
699 assert(updates->count() > 0, "Updates holder not deleted");
700 // free deferred updates.
701 delete updates;
702 set_deferred_updates(nullptr);
703 }
704
705 // All Java related clean up happens in exit
706 ThreadSafepointState::destroy(this);
707 if (_thread_stat != nullptr) delete _thread_stat;
708
709 #if INCLUDE_JVMCI
710 if (JVMCICounterSize > 0) {
711 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
712 }
713 #endif // INCLUDE_JVMCI
714 }
715
716
717 // First JavaThread specific code executed by a new Java thread.
718 void JavaThread::pre_run() {
719 // empty - see comments in run()
720 }
721
722 // The main routine called by a new Java thread. This isn't overridden
723 // by subclasses, instead different subclasses define a different "entry_point"
724 // which defines the actual logic for that kind of thread.
725 void JavaThread::run() {
726 // initialize thread-local alloc buffer related fields
727 initialize_tlab();
728
729 _stack_overflow_state.create_stack_guard_pages();
730
731 cache_global_variables();
732
733 // Thread is now sufficiently initialized to be handled by the safepoint code as being
734 // in the VM. Change thread state from _thread_new to _thread_in_vm
735 assert(this->thread_state() == _thread_new, "wrong thread state");
736 set_thread_state(_thread_in_vm);
737
738 // Before a thread is on the threads list it is always safe, so after leaving the
739 // _thread_new we should emit a instruction barrier. The distance to modified code
740 // from here is probably far enough, but this is consistent and safe.
741 OrderAccess::cross_modify_fence();
742
743 assert(JavaThread::current() == this, "sanity check");
744 assert(!Thread::current()->owns_locks(), "sanity check");
745
746 DTRACE_THREAD_PROBE(start, this);
747
748 // This operation might block. We call that after all safepoint checks for a new thread has
749 // been completed.
750 set_active_handles(JNIHandleBlock::allocate_block());
751
752 if (JvmtiExport::should_post_thread_life()) {
753 JvmtiExport::post_thread_start(this);
754
755 }
756
757 if (AlwaysPreTouchStacks) {
758 pretouch_stack();
759 }
760
761 // We call another function to do the rest so we are sure that the stack addresses used
762 // from there will be lower than the stack base just computed.
763 thread_main_inner();
764 }
765
766 void JavaThread::thread_main_inner() {
767 assert(JavaThread::current() == this, "sanity check");
768 assert(_threadObj.peek() != nullptr, "just checking");
769
770 // Execute thread entry point unless this thread has a pending exception.
771 // Note: Due to JVMTI StopThread we can have pending exceptions already!
772 if (!this->has_pending_exception()) {
773 {
774 ResourceMark rm(this);
775 this->set_native_thread_name(this->name());
776 }
777 HandleMark hm(this);
778 this->entry_point()(this, this);
779 }
780
781 DTRACE_THREAD_PROBE(stop, this);
782
783 // Cleanup is handled in post_run()
784 }
785
786 // Shared teardown for all JavaThreads
787 void JavaThread::post_run() {
788 this->exit(false);
789 this->unregister_thread_stack_with_NMT();
790 // Defer deletion to here to ensure 'this' is still referenceable in call_run
791 // for any shared tear-down.
792 this->smr_delete();
793 }
794
795 static void ensure_join(JavaThread* thread) {
796 // We do not need to grab the Threads_lock, since we are operating on ourself.
797 Handle threadObj(thread, thread->threadObj());
798 assert(threadObj.not_null(), "java thread object must exist");
799 ObjectLocker lock(threadObj, thread);
800 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
801 java_lang_Thread::set_thread_status(threadObj(), JavaThreadStatus::TERMINATED);
802 // Clear the native thread instance - this makes isAlive return false and allows the join()
803 // to complete once we've done the notify_all below. Needs a release() to obey Java Memory Model
804 // requirements.
805 assert(java_lang_Thread::thread(threadObj()) == thread, "must be alive");
806 java_lang_Thread::release_set_thread(threadObj(), nullptr);
807 lock.notify_all(thread);
808 // Ignore pending exception, since we are exiting anyway
809 thread->clear_pending_exception();
810 }
811
812 static bool is_daemon(oop threadObj) {
813 return (threadObj != nullptr && java_lang_Thread::is_daemon(threadObj));
814 }
815
816 // For any new cleanup additions, please check to see if they need to be applied to
817 // cleanup_failed_attach_current_thread as well.
818 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
819 assert(this == JavaThread::current(), "thread consistency check");
820 assert(!is_exiting(), "should not be exiting or terminated already");
821
822 elapsedTimer _timer_exit_phase1;
823 elapsedTimer _timer_exit_phase2;
824 elapsedTimer _timer_exit_phase3;
825 elapsedTimer _timer_exit_phase4;
826
827 om_clear_monitor_cache();
828
829 if (log_is_enabled(Debug, os, thread, timer)) {
830 _timer_exit_phase1.start();
831 }
832
833 HandleMark hm(this);
834 Handle uncaught_exception(this, this->pending_exception());
835 this->clear_pending_exception();
836 Handle threadObj(this, this->threadObj());
837 assert(threadObj.not_null(), "Java thread object should be created");
838
839 if (!destroy_vm) {
840 if (uncaught_exception.not_null()) {
841 EXCEPTION_MARK;
842 // Call method Thread.dispatchUncaughtException().
843 Klass* thread_klass = vmClasses::Thread_klass();
844 JavaValue result(T_VOID);
845 JavaCalls::call_virtual(&result,
846 threadObj, thread_klass,
847 vmSymbols::dispatchUncaughtException_name(),
848 vmSymbols::throwable_void_signature(),
849 uncaught_exception,
850 THREAD);
851 if (HAS_PENDING_EXCEPTION) {
852 ResourceMark rm(this);
853 jio_fprintf(defaultStream::error_stream(),
854 "\nException: %s thrown from the UncaughtExceptionHandler"
855 " in thread \"%s\"\n",
856 pending_exception()->klass()->external_name(),
857 name());
858 CLEAR_PENDING_EXCEPTION;
859 }
860 }
861
862 if (!is_Compiler_thread()) {
863 // We have finished executing user-defined Java code and now have to do the
864 // implementation specific clean-up by calling Thread.exit(). We prevent any
865 // asynchronous exceptions from being delivered while in Thread.exit()
866 // to ensure the clean-up is not corrupted.
867 NoAsyncExceptionDeliveryMark _no_async(this);
868
869 EXCEPTION_MARK;
870 JavaValue result(T_VOID);
871 Klass* thread_klass = vmClasses::Thread_klass();
872 JavaCalls::call_virtual(&result,
873 threadObj, thread_klass,
874 vmSymbols::exit_method_name(),
875 vmSymbols::void_method_signature(),
876 THREAD);
877 CLEAR_PENDING_EXCEPTION;
878 }
879
880 // notify JVMTI
881 if (JvmtiExport::should_post_thread_life()) {
882 JvmtiExport::post_thread_end(this);
883 }
884 } else {
885 // before_exit() has already posted JVMTI THREAD_END events
886 }
887
888 // Cleanup any pending async exception now since we cannot access oops after
889 // BarrierSet::barrier_set()->on_thread_detach() has been executed.
890 if (has_async_exception_condition()) {
891 handshake_state()->clean_async_exception_operation();
892 }
893
894 // The careful dance between thread suspension and exit is handled here.
895 // Since we are in thread_in_vm state and suspension is done with handshakes,
896 // we can just put in the exiting state and it will be correctly handled.
897 // Also, no more async exceptions will be added to the queue after this point.
898 set_terminated(_thread_exiting);
899 ThreadService::current_thread_exiting(this, is_daemon(threadObj()));
900
901 if (log_is_enabled(Debug, os, thread, timer)) {
902 _timer_exit_phase1.stop();
903 _timer_exit_phase2.start();
904 }
905
906 // Capture daemon status before the thread is marked as terminated.
907 bool daemon = is_daemon(threadObj());
908
909 // Notify waiters on thread object. This has to be done after exit() is called
910 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
911 // group should have the destroyed bit set before waiters are notified).
912 ensure_join(this);
913 assert(!this->has_pending_exception(), "ensure_join should have cleared");
914
915 if (log_is_enabled(Debug, os, thread, timer)) {
916 _timer_exit_phase2.stop();
917 _timer_exit_phase3.start();
918 }
919 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
920 // held by this thread must be released. The spec does not distinguish
921 // between JNI-acquired and regular Java monitors. We can only see
922 // regular Java monitors here if monitor enter-exit matching is broken.
923 //
924 // ensure_join() ignores IllegalThreadStateExceptions, and so does
925 // ObjectSynchronizer::release_monitors_owned_by_thread().
926 if (exit_type == jni_detach) {
927 // Sanity check even though JNI DetachCurrentThread() would have
928 // returned JNI_ERR if there was a Java frame. JavaThread exit
929 // should be done executing Java code by the time we get here.
930 assert(!this->has_last_Java_frame(),
931 "should not have a Java frame when detaching or exiting");
932 ObjectSynchronizer::release_monitors_owned_by_thread(this);
933 assert(!this->has_pending_exception(), "release_monitors should have cleared");
934 // Check for monitor counts being out of sync.
935 assert(held_monitor_count() == jni_monitor_count(),
936 "held monitor count should be equal to jni: %zd != %zd",
937 held_monitor_count(), jni_monitor_count());
938 // All in-use monitors, including JNI-locked ones, should have been released above.
939 assert(held_monitor_count() == 0, "Failed to unlock %zd object monitors",
940 held_monitor_count());
941 } else {
942 // Check for monitor counts being out of sync.
943 assert(held_monitor_count() == jni_monitor_count(),
944 "held monitor count should be equal to jni: %zd != %zd",
945 held_monitor_count(), jni_monitor_count());
946 // It is possible that a terminating thread failed to unlock monitors it locked
947 // via JNI so we don't assert the count is zero.
948 }
949
950 if (CheckJNICalls && jni_monitor_count() > 0) {
951 // We would like a fatal here, but due to we never checked this before there
952 // is a lot of tests which breaks, even with an error log.
953 log_debug(jni)("JavaThread %s (tid: %zu) with Objects still locked by JNI MonitorEnter.",
954 exit_type == JavaThread::normal_exit ? "exiting" : "detaching", os::current_thread_id());
955 }
956
957 // These things needs to be done while we are still a Java Thread. Make sure that thread
958 // is in a consistent state, in case GC happens
959 JFR_ONLY(Jfr::on_thread_exit(this);)
960
961 if (active_handles() != nullptr) {
962 JNIHandleBlock* block = active_handles();
963 set_active_handles(nullptr);
964 JNIHandleBlock::release_block(block);
965 }
966
967 if (free_handle_block() != nullptr) {
968 JNIHandleBlock* block = free_handle_block();
969 set_free_handle_block(nullptr);
970 JNIHandleBlock::release_block(block);
971 }
972
973 // These have to be removed while this is still a valid thread.
974 _stack_overflow_state.remove_stack_guard_pages();
975
976 if (UseTLAB) {
977 tlab().retire();
978 }
979
980 if (JvmtiEnv::environments_might_exist()) {
981 JvmtiExport::cleanup_thread(this);
982 }
983
984 // We need to cache the thread name for logging purposes below as once
985 // we have called on_thread_detach this thread must not access any oops.
986 char* thread_name = nullptr;
987 if (log_is_enabled(Debug, os, thread, timer) || (CountBytecodesPerThread && log_is_enabled(Info, init))) {
988 ResourceMark rm(this);
989 thread_name = os::strdup(name());
990 }
991
992 if (log_is_enabled(Info, os, thread)) {
993 ResourceMark rm(this);
994 log_info(os, thread)("JavaThread %s (name: \"%s\", tid: %zu).",
995 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
996 name(), os::current_thread_id());
997 }
998
999 if (log_is_enabled(Debug, os, thread, timer)) {
1000 _timer_exit_phase3.stop();
1001 _timer_exit_phase4.start();
1002 }
1003
1004 #if INCLUDE_JVMCI
1005 if (JVMCICounterSize > 0) {
1006 if (jvmci_counters_include(this)) {
1007 for (int i = 0; i < JVMCICounterSize; i++) {
1008 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1009 }
1010 }
1011 }
1012 #endif // INCLUDE_JVMCI
1013
1014 if (bc_counter_value() > 0) {
1015 log_info(init)("Thread '%s': " JLONG_FORMAT " bytecodes executed (during clinit: " JLONG_FORMAT ")",
1016 thread_name, bc_counter_value(), clinit_bc_counter_value());
1017 }
1018
1019 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread.
1020 // We call BarrierSet::barrier_set()->on_thread_detach() here so no touching of oops after this point.
1021 Threads::remove(this, daemon);
1022
1023 if (log_is_enabled(Debug, os, thread, timer)) {
1024 _timer_exit_phase4.stop();
1025 log_debug(os, thread, timer)("name='%s'"
1026 ", exit-phase1=" JLONG_FORMAT
1027 ", exit-phase2=" JLONG_FORMAT
1028 ", exit-phase3=" JLONG_FORMAT
1029 ", exit-phase4=" JLONG_FORMAT,
1030 thread_name,
1031 _timer_exit_phase1.milliseconds(),
1032 _timer_exit_phase2.milliseconds(),
1033 _timer_exit_phase3.milliseconds(),
1034 _timer_exit_phase4.milliseconds());
1035 os::free(thread_name);
1036 }
1037 }
1038
1039 void JavaThread::cleanup_failed_attach_current_thread(bool is_daemon) {
1040 if (active_handles() != nullptr) {
1041 JNIHandleBlock* block = active_handles();
1042 set_active_handles(nullptr);
1043 JNIHandleBlock::release_block(block);
1044 }
1045
1046 if (free_handle_block() != nullptr) {
1047 JNIHandleBlock* block = free_handle_block();
1048 set_free_handle_block(nullptr);
1049 JNIHandleBlock::release_block(block);
1050 }
1051
1052 // These have to be removed while this is still a valid thread.
1053 _stack_overflow_state.remove_stack_guard_pages();
1054
1055 if (UseTLAB) {
1056 tlab().retire();
1057 }
1058
1059 Threads::remove(this, is_daemon);
1060 }
1061
1062 JavaThread* JavaThread::active() {
1063 Thread* thread = Thread::current();
1064 if (thread->is_Java_thread()) {
1065 return JavaThread::cast(thread);
1066 } else {
1067 assert(thread->is_VM_thread(), "this must be a vm thread");
1068 VM_Operation* op = ((VMThread*) thread)->vm_operation();
1069 JavaThread *ret = op == nullptr ? nullptr : JavaThread::cast(op->calling_thread());
1070 return ret;
1071 }
1072 }
1073
1074 bool JavaThread::is_lock_owned(address adr) const {
1075 assert(LockingMode != LM_LIGHTWEIGHT, "should not be called with new lightweight locking");
1076 return is_in_full_stack(adr);
1077 }
1078
1079 oop JavaThread::exception_oop() const {
1080 return Atomic::load(&_exception_oop);
1081 }
1082
1083 void JavaThread::set_exception_oop(oop o) {
1084 Atomic::store(&_exception_oop, o);
1085 }
1086
1087 void JavaThread::handle_special_runtime_exit_condition() {
1088 if (is_obj_deopt_suspend()) {
1089 frame_anchor()->make_walkable();
1090 wait_for_object_deoptimization();
1091 }
1092 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
1093 }
1094
1095
1096 // Asynchronous exceptions support
1097 //
1098 void JavaThread::handle_async_exception(oop java_throwable) {
1099 assert(java_throwable != nullptr, "should have an _async_exception to throw");
1100 assert(!is_at_poll_safepoint(), "should have never called this method");
1101
1102 if (has_last_Java_frame()) {
1103 frame f = last_frame();
1104 if (f.is_runtime_frame()) {
1105 // If the topmost frame is a runtime stub, then we are calling into
1106 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
1107 // must deoptimize the caller before continuing, as the compiled exception
1108 // handler table may not be valid.
1109 RegisterMap reg_map(this,
1110 RegisterMap::UpdateMap::skip,
1111 RegisterMap::ProcessFrames::include,
1112 RegisterMap::WalkContinuation::skip);
1113 frame compiled_frame = f.sender(®_map);
1114 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
1115 Deoptimization::deoptimize(this, compiled_frame);
1116 }
1117 }
1118 }
1119
1120 // We cannot call Exceptions::_throw(...) here because we cannot block
1121 set_pending_exception(java_throwable, __FILE__, __LINE__);
1122
1123 clear_scopedValueBindings();
1124
1125 LogTarget(Info, exceptions) lt;
1126 if (lt.is_enabled()) {
1127 ResourceMark rm;
1128 LogStream ls(lt);
1129 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
1130 if (has_last_Java_frame()) {
1131 frame f = last_frame();
1132 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
1133 }
1134 ls.print_cr(" of type: %s", java_throwable->klass()->external_name());
1135 }
1136 }
1137
1138 void JavaThread::install_async_exception(AsyncExceptionHandshake* aeh) {
1139 // Do not throw asynchronous exceptions against the compiler thread
1140 // or if the thread is already exiting.
1141 if (!can_call_java() || is_exiting()) {
1142 delete aeh;
1143 return;
1144 }
1145
1146 oop exception = aeh->exception();
1147 Handshake::execute(aeh, this); // Install asynchronous handshake
1148
1149 ResourceMark rm;
1150 if (log_is_enabled(Info, exceptions)) {
1151 log_info(exceptions)("Pending Async. exception installed of type: %s",
1152 InstanceKlass::cast(exception->klass())->external_name());
1153 }
1154 // for AbortVMOnException flag
1155 Exceptions::debug_check_abort(exception->klass()->external_name());
1156
1157 oop vt_oop = vthread();
1158 if (vt_oop == nullptr || !vt_oop->is_a(vmClasses::BaseVirtualThread_klass())) {
1159 // Interrupt thread so it will wake up from a potential wait()/sleep()/park()
1160 java_lang_Thread::set_interrupted(threadObj(), true);
1161 this->interrupt();
1162 }
1163 }
1164
1165 class InstallAsyncExceptionHandshake : public HandshakeClosure {
1166 AsyncExceptionHandshake* _aeh;
1167 public:
1168 InstallAsyncExceptionHandshake(AsyncExceptionHandshake* aeh) :
1169 HandshakeClosure("InstallAsyncException"), _aeh(aeh) {}
1170 ~InstallAsyncExceptionHandshake() {
1171 // If InstallAsyncExceptionHandshake was never executed we need to clean up _aeh.
1172 delete _aeh;
1173 }
1174 void do_thread(Thread* thr) {
1175 JavaThread* target = JavaThread::cast(thr);
1176 target->install_async_exception(_aeh);
1177 _aeh = nullptr;
1178 }
1179 };
1180
1181 void JavaThread::send_async_exception(JavaThread* target, oop java_throwable) {
1182 OopHandle e(Universe::vm_global(), java_throwable);
1183 InstallAsyncExceptionHandshake iaeh(new AsyncExceptionHandshake(e));
1184 Handshake::execute(&iaeh, target);
1185 }
1186
1187 #if INCLUDE_JVMTI
1188 void JavaThread::set_is_in_VTMS_transition(bool val) {
1189 assert(is_in_VTMS_transition() != val, "already %s transition", val ? "inside" : "outside");
1190 _is_in_VTMS_transition = val;
1191 }
1192
1193 #ifdef ASSERT
1194 void JavaThread::set_is_VTMS_transition_disabler(bool val) {
1195 _is_VTMS_transition_disabler = val;
1196 }
1197 #endif
1198 #endif
1199
1200 // External suspension mechanism.
1201 //
1202 // Guarantees on return (for a valid target thread):
1203 // - Target thread will not execute any new bytecode.
1204 // - Target thread will not enter any new monitors.
1205 //
1206 bool JavaThread::java_suspend() {
1207 #if INCLUDE_JVMTI
1208 // Suspending a JavaThread in VTMS transition or disabling VTMS transitions can cause deadlocks.
1209 assert(!is_in_VTMS_transition(), "no suspend allowed in VTMS transition");
1210 assert(!is_VTMS_transition_disabler(), "no suspend allowed for VTMS transition disablers");
1211 #endif
1212
1213 guarantee(Thread::is_JavaThread_protected(/* target */ this),
1214 "target JavaThread is not protected in calling context.");
1215 return this->handshake_state()->suspend();
1216 }
1217
1218 bool JavaThread::java_resume() {
1219 guarantee(Thread::is_JavaThread_protected_by_TLH(/* target */ this),
1220 "missing ThreadsListHandle in calling context.");
1221 return this->handshake_state()->resume();
1222 }
1223
1224 // Wait for another thread to perform object reallocation and relocking on behalf of
1225 // this thread. The current thread is required to change to _thread_blocked in order
1226 // to be seen to be safepoint/handshake safe whilst suspended and only after becoming
1227 // handshake safe, the other thread can complete the handshake used to synchronize
1228 // with this thread and then perform the reallocation and relocking.
1229 // See EscapeBarrier::sync_and_suspend_*()
1230
1231 void JavaThread::wait_for_object_deoptimization() {
1232 assert(!has_last_Java_frame() || frame_anchor()->walkable(), "should have walkable stack");
1233 assert(this == Thread::current(), "invariant");
1234
1235 bool spin_wait = os::is_MP();
1236 do {
1237 ThreadBlockInVM tbivm(this, true /* allow_suspend */);
1238 // Wait for object deoptimization if requested.
1239 if (spin_wait) {
1240 // A single deoptimization is typically very short. Microbenchmarks
1241 // showed 5% better performance when spinning.
1242 const uint spin_limit = 10 * SpinYield::default_spin_limit;
1243 SpinYield spin(spin_limit);
1244 for (uint i = 0; is_obj_deopt_suspend() && i < spin_limit; i++) {
1245 spin.wait();
1246 }
1247 // Spin just once
1248 spin_wait = false;
1249 } else {
1250 MonitorLocker ml(this, EscapeBarrier_lock, Monitor::_no_safepoint_check_flag);
1251 if (is_obj_deopt_suspend()) {
1252 ml.wait();
1253 }
1254 }
1255 // A handshake for obj. deoptimization suspend could have been processed so
1256 // we must check after processing.
1257 } while (is_obj_deopt_suspend());
1258 }
1259
1260 #ifdef ASSERT
1261 // Verify the JavaThread has not yet been published in the Threads::list, and
1262 // hence doesn't need protection from concurrent access at this stage.
1263 void JavaThread::verify_not_published() {
1264 // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
1265 // since an unpublished JavaThread doesn't participate in the
1266 // Thread-SMR protocol for keeping a ThreadsList alive.
1267 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
1268 }
1269 #endif
1270
1271 // Slow path when the native==>Java barriers detect a safepoint/handshake is
1272 // pending, when _suspend_flags is non-zero or when we need to process a stack
1273 // watermark. Also check for pending async exceptions (except unsafe access error).
1274 // Note only the native==>Java barriers can call this function when thread state
1275 // is _thread_in_native_trans.
1276 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
1277 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
1278 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "Unwalkable stack in native->Java transition");
1279
1280 thread->set_thread_state(_thread_in_vm);
1281
1282 // Enable WXWrite: called directly from interpreter native wrapper.
1283 MACOS_AARCH64_ONLY(ThreadWXEnable wx(WXWrite, thread));
1284
1285 SafepointMechanism::process_if_requested_with_exit_check(thread, true /* check asyncs */);
1286
1287 // After returning from native, it could be that the stack frames are not
1288 // yet safe to use. We catch such situations in the subsequent stack watermark
1289 // barrier, which will trap unsafe stack frames.
1290 StackWatermarkSet::before_unwind(thread);
1291 }
1292
1293 #ifndef PRODUCT
1294 // Deoptimization
1295 // Function for testing deoptimization
1296 void JavaThread::deoptimize() {
1297 StackFrameStream fst(this, false /* update */, true /* process_frames */);
1298 bool deopt = false; // Dump stack only if a deopt actually happens.
1299 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
1300 // Iterate over all frames in the thread and deoptimize
1301 for (; !fst.is_done(); fst.next()) {
1302 if (fst.current()->can_be_deoptimized()) {
1303
1304 if (only_at) {
1305 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
1306 // consists of comma or carriage return separated numbers so
1307 // search for the current bci in that string.
1308 address pc = fst.current()->pc();
1309 nmethod* nm = fst.current()->cb()->as_nmethod();
1310 ScopeDesc* sd = nm->scope_desc_at(pc);
1311 char buffer[8];
1312 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
1313 size_t len = strlen(buffer);
1314 const char * found = strstr(DeoptimizeOnlyAt, buffer);
1315 while (found != nullptr) {
1316 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
1317 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
1318 // Check that the bci found is bracketed by terminators.
1319 break;
1320 }
1321 found = strstr(found + 1, buffer);
1322 }
1323 if (!found) {
1324 continue;
1325 }
1326 }
1327
1328 if (DebugDeoptimization && !deopt) {
1329 deopt = true; // One-time only print before deopt
1330 tty->print_cr("[BEFORE Deoptimization]");
1331 trace_frames();
1332 trace_stack();
1333 }
1334 Deoptimization::deoptimize(this, *fst.current());
1335 }
1336 }
1337
1338 if (DebugDeoptimization && deopt) {
1339 tty->print_cr("[AFTER Deoptimization]");
1340 trace_frames();
1341 }
1342 }
1343
1344
1345 // Make zombies
1346 void JavaThread::make_zombies() {
1347 for (StackFrameStream fst(this, true /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
1348 if (fst.current()->can_be_deoptimized()) {
1349 // it is a Java nmethod
1350 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
1351 assert(nm != nullptr, "did not find nmethod");
1352 nm->make_not_entrant();
1353 }
1354 }
1355 }
1356 #endif // PRODUCT
1357
1358
1359 void JavaThread::deoptimize_marked_methods() {
1360 if (!has_last_Java_frame()) return;
1361 StackFrameStream fst(this, false /* update */, true /* process_frames */);
1362 for (; !fst.is_done(); fst.next()) {
1363 if (fst.current()->should_be_deoptimized()) {
1364 Deoptimization::deoptimize(this, *fst.current());
1365 }
1366 }
1367 }
1368
1369 #ifdef ASSERT
1370 void JavaThread::verify_frame_info() {
1371 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
1372 (has_last_Java_frame() && java_call_counter() > 0),
1373 "unexpected frame info: has_last_frame=%s, java_call_counter=%d",
1374 has_last_Java_frame() ? "true" : "false", java_call_counter());
1375 }
1376 #endif
1377
1378 // Push on a new block of JNI handles.
1379 void JavaThread::push_jni_handle_block() {
1380 // Allocate a new block for JNI handles.
1381 // Inlined code from jni_PushLocalFrame()
1382 JNIHandleBlock* old_handles = active_handles();
1383 JNIHandleBlock* new_handles = JNIHandleBlock::allocate_block(this);
1384 assert(old_handles != nullptr && new_handles != nullptr, "should not be null");
1385 new_handles->set_pop_frame_link(old_handles); // make sure java handles get gc'd.
1386 set_active_handles(new_handles);
1387 }
1388
1389 // Pop off the current block of JNI handles.
1390 void JavaThread::pop_jni_handle_block() {
1391 // Release our JNI handle block
1392 JNIHandleBlock* old_handles = active_handles();
1393 JNIHandleBlock* new_handles = old_handles->pop_frame_link();
1394 assert(new_handles != nullptr, "should never set active handles to null");
1395 set_active_handles(new_handles);
1396 old_handles->set_pop_frame_link(nullptr);
1397 JNIHandleBlock::release_block(old_handles, this);
1398 }
1399
1400 void JavaThread::oops_do_no_frames(OopClosure* f, NMethodClosure* cf) {
1401 // Verify that the deferred card marks have been flushed.
1402 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
1403
1404 // Traverse the GCHandles
1405 Thread::oops_do_no_frames(f, cf);
1406
1407 if (active_handles() != nullptr) {
1408 active_handles()->oops_do(f);
1409 }
1410
1411 DEBUG_ONLY(verify_frame_info();)
1412
1413 assert(vframe_array_head() == nullptr, "deopt in progress at a safepoint!");
1414 // If we have deferred set_locals there might be oops waiting to be
1415 // written
1416 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = JvmtiDeferredUpdates::deferred_locals(this);
1417 if (list != nullptr) {
1418 for (int i = 0; i < list->length(); i++) {
1419 list->at(i)->oops_do(f);
1420 }
1421 }
1422
1423 // Traverse instance variables at the end since the GC may be moving things
1424 // around using this function
1425 f->do_oop((oop*) &_vm_result);
1426 f->do_oop((oop*) &_exception_oop);
1427 #if INCLUDE_JVMCI
1428 f->do_oop((oop*) &_jvmci_reserved_oop0);
1429
1430 if (_live_nmethod != nullptr && cf != nullptr) {
1431 cf->do_nmethod(_live_nmethod);
1432 }
1433 #endif
1434
1435 if (jvmti_thread_state() != nullptr) {
1436 jvmti_thread_state()->oops_do(f, cf);
1437 }
1438
1439 // The continuation oops are really on the stack. But there is typically at most
1440 // one of those per thread, so we handle them here in the oops_do_no_frames part
1441 // so that we don't have to sprinkle as many stack watermark checks where these
1442 // oops are used. We just need to make sure the thread has started processing.
1443 ContinuationEntry* entry = _cont_entry;
1444 while (entry != nullptr) {
1445 f->do_oop((oop*)entry->cont_addr());
1446 f->do_oop((oop*)entry->chunk_addr());
1447 entry = entry->parent();
1448 }
1449
1450 if (LockingMode == LM_LIGHTWEIGHT) {
1451 lock_stack().oops_do(f);
1452 }
1453 }
1454
1455 void JavaThread::oops_do_frames(OopClosure* f, NMethodClosure* cf) {
1456 if (!has_last_Java_frame()) {
1457 return;
1458 }
1459 // Finish any pending lazy GC activity for the frames
1460 StackWatermarkSet::finish_processing(this, nullptr /* context */, StackWatermarkKind::gc);
1461 // Traverse the execution stack
1462 for (StackFrameStream fst(this, true /* update */, false /* process_frames */); !fst.is_done(); fst.next()) {
1463 fst.current()->oops_do(f, cf, fst.register_map());
1464 }
1465 }
1466
1467 #ifdef ASSERT
1468 void JavaThread::verify_states_for_handshake() {
1469 // This checks that the thread has a correct frame state during a handshake.
1470 verify_frame_info();
1471 }
1472 #endif
1473
1474 void JavaThread::nmethods_do(NMethodClosure* cf) {
1475 DEBUG_ONLY(verify_frame_info();)
1476 MACOS_AARCH64_ONLY(ThreadWXEnable wx(WXWrite, Thread::current());)
1477
1478 if (has_last_Java_frame()) {
1479 // Traverse the execution stack
1480 for (StackFrameStream fst(this, true /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
1481 fst.current()->nmethod_do(cf);
1482 }
1483 }
1484
1485 if (jvmti_thread_state() != nullptr) {
1486 jvmti_thread_state()->nmethods_do(cf);
1487 }
1488
1489 #if INCLUDE_JVMCI
1490 if (_live_nmethod != nullptr) {
1491 cf->do_nmethod(_live_nmethod);
1492 }
1493 #endif
1494 }
1495
1496 void JavaThread::metadata_do(MetadataClosure* f) {
1497 if (has_last_Java_frame()) {
1498 // Traverse the execution stack to call f() on the methods in the stack
1499 for (StackFrameStream fst(this, true /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
1500 fst.current()->metadata_do(f);
1501 }
1502 } else if (is_Compiler_thread()) {
1503 // need to walk ciMetadata in current compile tasks to keep alive.
1504 CompilerThread* ct = (CompilerThread*)this;
1505 if (ct->env() != nullptr) {
1506 ct->env()->metadata_do(f);
1507 }
1508 CompileTask* task = ct->task();
1509 if (task != nullptr) {
1510 task->metadata_do(f);
1511 }
1512 }
1513 }
1514
1515 // Printing
1516 static const char* _get_thread_state_name(JavaThreadState _thread_state) {
1517 switch (_thread_state) {
1518 case _thread_uninitialized: return "_thread_uninitialized";
1519 case _thread_new: return "_thread_new";
1520 case _thread_new_trans: return "_thread_new_trans";
1521 case _thread_in_native: return "_thread_in_native";
1522 case _thread_in_native_trans: return "_thread_in_native_trans";
1523 case _thread_in_vm: return "_thread_in_vm";
1524 case _thread_in_vm_trans: return "_thread_in_vm_trans";
1525 case _thread_in_Java: return "_thread_in_Java";
1526 case _thread_in_Java_trans: return "_thread_in_Java_trans";
1527 case _thread_blocked: return "_thread_blocked";
1528 case _thread_blocked_trans: return "_thread_blocked_trans";
1529 default: return "unknown thread state";
1530 }
1531 }
1532
1533 void JavaThread::print_thread_state_on(outputStream *st) const {
1534 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
1535 }
1536
1537 // Called by Threads::print() for VM_PrintThreads operation
1538 void JavaThread::print_on(outputStream *st, bool print_extended_info) const {
1539 st->print_raw("\"");
1540 st->print_raw(name());
1541 st->print_raw("\" ");
1542 oop thread_oop = threadObj();
1543 if (thread_oop != nullptr) {
1544 st->print("#" INT64_FORMAT " [%ld] ", (int64_t)java_lang_Thread::thread_id(thread_oop), (long) osthread()->thread_id());
1545 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
1546 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
1547 }
1548 Thread::print_on(st, print_extended_info);
1549 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
1550 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
1551 if (thread_oop != nullptr) {
1552 if (is_vthread_mounted()) {
1553 st->print_cr(" Carrying virtual thread #" INT64_FORMAT, java_lang_Thread::thread_id(vthread()));
1554 } else {
1555 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
1556 }
1557 }
1558 #ifndef PRODUCT
1559 _safepoint_state->print_on(st);
1560 #endif // PRODUCT
1561 if (is_Compiler_thread()) {
1562 CompileTask *task = ((CompilerThread*)this)->task();
1563 if (task != nullptr) {
1564 st->print(" Compiling: ");
1565 task->print(st, nullptr, true, false);
1566 } else {
1567 st->print(" No compile task");
1568 }
1569 st->cr();
1570 }
1571 }
1572
1573 void JavaThread::print() const { print_on(tty); }
1574
1575 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
1576 st->print("%s", get_thread_name_string(buf, buflen));
1577 }
1578
1579 // Called by fatal error handler. The difference between this and
1580 // JavaThread::print() is that we can't grab lock or allocate memory.
1581 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
1582 st->print("%s \"%s\"", type_name(), get_thread_name_string(buf, buflen));
1583 Thread* current = Thread::current_or_null_safe();
1584 assert(current != nullptr, "cannot be called by a detached thread");
1585 st->fill_to(60);
1586 if (!current->is_Java_thread() || JavaThread::cast(current)->is_oop_safe()) {
1587 // Only access threadObj() if current thread is not a JavaThread
1588 // or if it is a JavaThread that can safely access oops.
1589 oop thread_obj = threadObj();
1590 if (thread_obj != nullptr) {
1591 st->print(java_lang_Thread::is_daemon(thread_obj) ? " daemon" : " ");
1592 }
1593 }
1594 st->print(" [");
1595 st->print("%s", _get_thread_state_name(_thread_state));
1596 if (osthread()) {
1597 st->print(", id=%d", osthread()->thread_id());
1598 }
1599 // Use raw field members for stack base/size as this could be
1600 // called before a thread has run enough to initialize them.
1601 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ") (" PROPERFMT ")",
1602 p2i(_stack_base - _stack_size), p2i(_stack_base),
1603 PROPERFMTARGS(_stack_size));
1604 st->print("]");
1605
1606 ThreadsSMRSupport::print_info_on(this, st);
1607 return;
1608 }
1609
1610
1611 // Verification
1612
1613 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
1614 // ignore if there is no stack
1615 if (!has_last_Java_frame()) return;
1616 // traverse the stack frames. Starts from top frame.
1617 for (StackFrameStream fst(this, true /* update_map */, true /* process_frames */, false /* walk_cont */); !fst.is_done(); fst.next()) {
1618 frame* fr = fst.current();
1619 f(fr, fst.register_map());
1620 }
1621 }
1622
1623 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
1624
1625 void JavaThread::verify() {
1626 // Verify oops in the thread.
1627 oops_do(&VerifyOopClosure::verify_oop, nullptr);
1628
1629 // Verify the stack frames.
1630 frames_do(frame_verify);
1631 }
1632
1633 // CR 6300358 (sub-CR 2137150)
1634 // Most callers of this method assume that it can't return null but a
1635 // thread may not have a name whilst it is in the process of attaching to
1636 // the VM - see CR 6412693, and there are places where a JavaThread can be
1637 // seen prior to having its threadObj set (e.g., JNI attaching threads and
1638 // if vm exit occurs during initialization). These cases can all be accounted
1639 // for such that this method never returns null.
1640 const char* JavaThread::name() const {
1641 if (Thread::is_JavaThread_protected(/* target */ this)) {
1642 // The target JavaThread is protected so get_thread_name_string() is safe:
1643 return get_thread_name_string();
1644 }
1645
1646 // The target JavaThread is not protected so we return the default:
1647 return Thread::name();
1648 }
1649
1650 // Like name() but doesn't include the protection check. This must only be
1651 // called when it is known to be safe, even though the protection check can't tell
1652 // that e.g. when this thread is the init_thread() - see instanceKlass.cpp.
1653 const char* JavaThread::name_raw() const {
1654 return get_thread_name_string();
1655 }
1656
1657 // Returns a non-null representation of this thread's name, or a suitable
1658 // descriptive string if there is no set name.
1659 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
1660 const char* name_str;
1661 #ifdef ASSERT
1662 Thread* current = Thread::current_or_null_safe();
1663 assert(current != nullptr, "cannot be called by a detached thread");
1664 if (!current->is_Java_thread() || JavaThread::cast(current)->is_oop_safe()) {
1665 // Only access threadObj() if current thread is not a JavaThread
1666 // or if it is a JavaThread that can safely access oops.
1667 #endif
1668 oop thread_obj = threadObj();
1669 if (thread_obj != nullptr) {
1670 oop name = java_lang_Thread::name(thread_obj);
1671 if (name != nullptr) {
1672 if (buf == nullptr) {
1673 name_str = java_lang_String::as_utf8_string(name);
1674 } else {
1675 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
1676 }
1677 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
1678 name_str = "<no-name - thread is attaching>";
1679 } else {
1680 name_str = "<un-named>";
1681 }
1682 } else {
1683 name_str = Thread::name();
1684 }
1685 #ifdef ASSERT
1686 } else {
1687 // Current JavaThread has exited...
1688 if (current == this) {
1689 // ... and is asking about itself:
1690 name_str = "<no-name - current JavaThread has exited>";
1691 } else {
1692 // ... and it can't safely determine this JavaThread's name so
1693 // use the default thread name.
1694 name_str = Thread::name();
1695 }
1696 }
1697 #endif
1698 assert(name_str != nullptr, "unexpected null thread name");
1699 return name_str;
1700 }
1701
1702 // Helper to extract the name from the thread oop for logging.
1703 const char* JavaThread::name_for(oop thread_obj) {
1704 assert(thread_obj != nullptr, "precondition");
1705 oop name = java_lang_Thread::name(thread_obj);
1706 const char* name_str;
1707 if (name != nullptr) {
1708 name_str = java_lang_String::as_utf8_string(name);
1709 } else {
1710 name_str = "<un-named>";
1711 }
1712 return name_str;
1713 }
1714
1715 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
1716
1717 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
1718 assert(NoPriority <= prio && prio <= MaxPriority, "sanity check");
1719 // Link Java Thread object <-> C++ Thread
1720
1721 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
1722 // and put it into a new Handle. The Handle "thread_oop" can then
1723 // be used to pass the C++ thread object to other methods.
1724
1725 // Set the Java level thread object (jthread) field of the
1726 // new thread (a JavaThread *) to C++ thread object using the
1727 // "thread_oop" handle.
1728
1729 // Set the thread field (a JavaThread *) of the
1730 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
1731
1732 Handle thread_oop(Thread::current(),
1733 JNIHandles::resolve_non_null(jni_thread));
1734 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
1735 "must be initialized");
1736 set_threadOopHandles(thread_oop());
1737 set_monitor_owner_id(java_lang_Thread::thread_id(thread_oop()));
1738
1739 if (prio == NoPriority) {
1740 prio = java_lang_Thread::priority(thread_oop());
1741 assert(prio != NoPriority, "A valid priority should be present");
1742 }
1743
1744 // Push the Java priority down to the native thread; needs Threads_lock
1745 Thread::set_priority(this, prio);
1746
1747 // Add the new thread to the Threads list and set it in motion.
1748 // We must have threads lock in order to call Threads::add.
1749 // It is crucial that we do not block before the thread is
1750 // added to the Threads list for if a GC happens, then the java_thread oop
1751 // will not be visited by GC.
1752 Threads::add(this);
1753 // Publish the JavaThread* in java.lang.Thread after the JavaThread* is
1754 // on a ThreadsList. We don't want to wait for the release when the
1755 // Theads_lock is dropped somewhere in the caller since the JavaThread*
1756 // is already visible to JVM/TI via the ThreadsList.
1757 java_lang_Thread::release_set_thread(thread_oop(), this);
1758 }
1759
1760 oop JavaThread::current_park_blocker() {
1761 // Support for JSR-166 locks
1762 oop thread_oop = threadObj();
1763 if (thread_oop != nullptr) {
1764 return java_lang_Thread::park_blocker(thread_oop);
1765 }
1766 return nullptr;
1767 }
1768
1769 // Print current stack trace for checked JNI warnings and JNI fatal errors.
1770 // This is the external format, selecting the platform or vthread
1771 // as applicable, and allowing for a native-only stack.
1772 void JavaThread::print_jni_stack() {
1773 assert(this == JavaThread::current(), "Can't print stack of other threads");
1774 if (!has_last_Java_frame()) {
1775 ResourceMark rm(this);
1776 char* buf = NEW_RESOURCE_ARRAY_RETURN_NULL(char, O_BUFLEN);
1777 if (buf == nullptr) {
1778 tty->print_cr("Unable to print native stack - out of memory");
1779 return;
1780 }
1781 NativeStackPrinter nsp(this);
1782 address lastpc = nullptr;
1783 nsp.print_stack(tty, buf, O_BUFLEN, lastpc,
1784 true /*print_source_info */, -1 /* max stack */ );
1785 } else {
1786 print_active_stack_on(tty);
1787 }
1788 }
1789
1790 void JavaThread::print_stack_on(outputStream* st) {
1791 if (!has_last_Java_frame()) return;
1792
1793 Thread* current_thread = Thread::current();
1794 ResourceMark rm(current_thread);
1795 HandleMark hm(current_thread);
1796
1797 RegisterMap reg_map(this,
1798 RegisterMap::UpdateMap::include,
1799 RegisterMap::ProcessFrames::include,
1800 RegisterMap::WalkContinuation::skip);
1801 vframe* start_vf = platform_thread_last_java_vframe(®_map);
1802 int count = 0;
1803 for (vframe* f = start_vf; f != nullptr; f = f->sender()) {
1804 if (f->is_java_frame()) {
1805 javaVFrame* jvf = javaVFrame::cast(f);
1806 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
1807
1808 // Print out lock information
1809 if (JavaMonitorsInStackTrace) {
1810 jvf->print_lock_info_on(st, count);
1811 }
1812 } else {
1813 // Ignore non-Java frames
1814 }
1815
1816 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
1817 count++;
1818 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
1819 }
1820 }
1821
1822 void JavaThread::print_vthread_stack_on(outputStream* st) {
1823 assert(is_vthread_mounted(), "Caller should have checked this");
1824 assert(has_last_Java_frame(), "must be");
1825
1826 Thread* current_thread = Thread::current();
1827 ResourceMark rm(current_thread);
1828 HandleMark hm(current_thread);
1829
1830 RegisterMap reg_map(this,
1831 RegisterMap::UpdateMap::include,
1832 RegisterMap::ProcessFrames::include,
1833 RegisterMap::WalkContinuation::include);
1834 ContinuationEntry* cont_entry = last_continuation();
1835 vframe* start_vf = last_java_vframe(®_map);
1836 int count = 0;
1837 for (vframe* f = start_vf; f != nullptr; f = f->sender()) {
1838 // Watch for end of vthread stack
1839 if (Continuation::is_continuation_enterSpecial(f->fr())) {
1840 assert(cont_entry == Continuation::get_continuation_entry_for_entry_frame(this, f->fr()), "");
1841 if (cont_entry->is_virtual_thread()) {
1842 break;
1843 }
1844 cont_entry = cont_entry->parent();
1845 }
1846 if (f->is_java_frame()) {
1847 javaVFrame* jvf = javaVFrame::cast(f);
1848 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
1849
1850 // Print out lock information
1851 if (JavaMonitorsInStackTrace) {
1852 jvf->print_lock_info_on(st, count);
1853 }
1854 } else {
1855 // Ignore non-Java frames
1856 }
1857
1858 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
1859 count++;
1860 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
1861 }
1862 }
1863
1864 void JavaThread::print_active_stack_on(outputStream* st) {
1865 if (is_vthread_mounted()) {
1866 print_vthread_stack_on(st);
1867 } else {
1868 print_stack_on(st);
1869 }
1870 }
1871
1872 #if INCLUDE_JVMTI
1873 // Rebind JVMTI thread state from carrier to virtual or from virtual to carrier.
1874 JvmtiThreadState* JavaThread::rebind_to_jvmti_thread_state_of(oop thread_oop) {
1875 set_jvmti_vthread(thread_oop);
1876
1877 // unbind current JvmtiThreadState from JavaThread
1878 JvmtiThreadState::unbind_from(jvmti_thread_state(), this);
1879
1880 // bind new JvmtiThreadState to JavaThread
1881 JvmtiThreadState::bind_to(java_lang_Thread::jvmti_thread_state(thread_oop), this);
1882
1883 // enable interp_only_mode for virtual or carrier thread if it has pending bit
1884 JvmtiThreadState::process_pending_interp_only(this);
1885
1886 return jvmti_thread_state();
1887 }
1888 #endif
1889
1890 // JVMTI PopFrame support
1891 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
1892 assert(_popframe_preserved_args == nullptr, "should not wipe out old PopFrame preserved arguments");
1893 if (in_bytes(size_in_bytes) != 0) {
1894 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
1895 _popframe_preserved_args_size = in_bytes(size_in_bytes);
1896 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
1897 }
1898 }
1899
1900 void* JavaThread::popframe_preserved_args() {
1901 return _popframe_preserved_args;
1902 }
1903
1904 ByteSize JavaThread::popframe_preserved_args_size() {
1905 return in_ByteSize(_popframe_preserved_args_size);
1906 }
1907
1908 WordSize JavaThread::popframe_preserved_args_size_in_words() {
1909 int sz = in_bytes(popframe_preserved_args_size());
1910 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
1911 return in_WordSize(sz / wordSize);
1912 }
1913
1914 void JavaThread::popframe_free_preserved_args() {
1915 assert(_popframe_preserved_args != nullptr, "should not free PopFrame preserved arguments twice");
1916 FREE_C_HEAP_ARRAY(char, (char*)_popframe_preserved_args);
1917 _popframe_preserved_args = nullptr;
1918 _popframe_preserved_args_size = 0;
1919 }
1920
1921 #ifndef PRODUCT
1922
1923 void JavaThread::trace_frames() {
1924 tty->print_cr("[Describe stack]");
1925 int frame_no = 1;
1926 for (StackFrameStream fst(this, true /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
1927 tty->print(" %d. ", frame_no++);
1928 fst.current()->print_value_on(tty);
1929 tty->cr();
1930 }
1931 }
1932
1933 class PrintAndVerifyOopClosure: public OopClosure {
1934 protected:
1935 template <class T> inline void do_oop_work(T* p) {
1936 oop obj = RawAccess<>::oop_load(p);
1937 if (obj == nullptr) return;
1938 tty->print(INTPTR_FORMAT ": ", p2i(p));
1939 if (oopDesc::is_oop_or_null(obj)) {
1940 if (obj->is_objArray()) {
1941 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
1942 } else {
1943 obj->print();
1944 }
1945 } else {
1946 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
1947 }
1948 tty->cr();
1949 }
1950 public:
1951 virtual void do_oop(oop* p) { do_oop_work(p); }
1952 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
1953 };
1954
1955 #ifdef ASSERT
1956 // Print or validate the layout of stack frames
1957 void JavaThread::print_frame_layout(int depth, bool validate_only) {
1958 ResourceMark rm;
1959 PreserveExceptionMark pm(this);
1960 FrameValues values;
1961 int frame_no = 0;
1962 for (StackFrameStream fst(this, true, true, true); !fst.is_done(); fst.next()) {
1963 fst.current()->describe(values, ++frame_no, fst.register_map());
1964 if (depth == frame_no) break;
1965 }
1966 Continuation::describe(values);
1967 if (validate_only) {
1968 values.validate();
1969 } else {
1970 tty->print_cr("[Describe stack layout]");
1971 values.print(this);
1972 }
1973 }
1974 #endif
1975
1976 void JavaThread::trace_stack_from(vframe* start_vf) {
1977 ResourceMark rm;
1978 int vframe_no = 1;
1979 for (vframe* f = start_vf; f; f = f->sender()) {
1980 if (f->is_java_frame()) {
1981 javaVFrame::cast(f)->print_activation(vframe_no++);
1982 } else {
1983 f->print();
1984 }
1985 if (vframe_no > StackPrintLimit) {
1986 tty->print_cr("...<more frames>...");
1987 return;
1988 }
1989 }
1990 }
1991
1992
1993 void JavaThread::trace_stack() {
1994 if (!has_last_Java_frame()) return;
1995 Thread* current_thread = Thread::current();
1996 ResourceMark rm(current_thread);
1997 HandleMark hm(current_thread);
1998 RegisterMap reg_map(this,
1999 RegisterMap::UpdateMap::include,
2000 RegisterMap::ProcessFrames::include,
2001 RegisterMap::WalkContinuation::skip);
2002 trace_stack_from(last_java_vframe(®_map));
2003 }
2004
2005
2006 #endif // PRODUCT
2007
2008 // Slow-path increment of the held monitor counts. JNI locking is always
2009 // this slow-path.
2010 void JavaThread::inc_held_monitor_count(intx i, bool jni) {
2011 #ifdef SUPPORT_MONITOR_COUNT
2012
2013 if (LockingMode != LM_LEGACY) {
2014 // Nothing to do. Just do some sanity check.
2015 assert(_held_monitor_count == 0, "counter should not be used");
2016 assert(_jni_monitor_count == 0, "counter should not be used");
2017 return;
2018 }
2019
2020 assert(_held_monitor_count >= 0, "Must always be non-negative: %zd", _held_monitor_count);
2021 _held_monitor_count += i;
2022 if (jni) {
2023 assert(_jni_monitor_count >= 0, "Must always be non-negative: %zd", _jni_monitor_count);
2024 _jni_monitor_count += i;
2025 }
2026 assert(_held_monitor_count >= _jni_monitor_count, "Monitor count discrepancy detected - held count "
2027 "%zd is less than JNI count %zd", _held_monitor_count, _jni_monitor_count);
2028 #endif // SUPPORT_MONITOR_COUNT
2029 }
2030
2031 // Slow-path decrement of the held monitor counts. JNI unlocking is always
2032 // this slow-path.
2033 void JavaThread::dec_held_monitor_count(intx i, bool jni) {
2034 #ifdef SUPPORT_MONITOR_COUNT
2035
2036 if (LockingMode != LM_LEGACY) {
2037 // Nothing to do. Just do some sanity check.
2038 assert(_held_monitor_count == 0, "counter should not be used");
2039 assert(_jni_monitor_count == 0, "counter should not be used");
2040 return;
2041 }
2042
2043 _held_monitor_count -= i;
2044 assert(_held_monitor_count >= 0, "Must always be non-negative: %zd", _held_monitor_count);
2045 if (jni) {
2046 _jni_monitor_count -= i;
2047 assert(_jni_monitor_count >= 0, "Must always be non-negative: %zd", _jni_monitor_count);
2048 }
2049 // When a thread is detaching with still owned JNI monitors, the logic that releases
2050 // the monitors doesn't know to set the "jni" flag and so the counts can get out of sync.
2051 // So we skip this assert if the thread is exiting. Once all monitors are unlocked the
2052 // JNI count is directly set to zero.
2053 assert(_held_monitor_count >= _jni_monitor_count || is_exiting(), "Monitor count discrepancy detected - held count "
2054 "%zd is less than JNI count %zd", _held_monitor_count, _jni_monitor_count);
2055 #endif // SUPPORT_MONITOR_COUNT
2056 }
2057
2058 frame JavaThread::vthread_last_frame() {
2059 assert (is_vthread_mounted(), "Virtual thread not mounted");
2060 return last_frame();
2061 }
2062
2063 frame JavaThread::carrier_last_frame(RegisterMap* reg_map) {
2064 const ContinuationEntry* entry = vthread_continuation();
2065 guarantee (entry != nullptr, "Not a carrier thread");
2066 frame f = entry->to_frame();
2067 if (reg_map->process_frames()) {
2068 entry->flush_stack_processing(this);
2069 }
2070 entry->update_register_map(reg_map);
2071 return f.sender(reg_map);
2072 }
2073
2074 frame JavaThread::platform_thread_last_frame(RegisterMap* reg_map) {
2075 return is_vthread_mounted() ? carrier_last_frame(reg_map) : last_frame();
2076 }
2077
2078 javaVFrame* JavaThread::last_java_vframe(const frame f, RegisterMap *reg_map) {
2079 assert(reg_map != nullptr, "a map must be given");
2080 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
2081 if (vf->is_java_frame()) return javaVFrame::cast(vf);
2082 }
2083 return nullptr;
2084 }
2085
2086 Klass* JavaThread::security_get_caller_class(int depth) {
2087 ResetNoHandleMark rnhm;
2088 HandleMark hm(Thread::current());
2089
2090 vframeStream vfst(this);
2091 vfst.security_get_caller_frame(depth);
2092 if (!vfst.at_end()) {
2093 return vfst.method()->method_holder();
2094 }
2095 return nullptr;
2096 }
2097
2098 // Internal convenience function for millisecond resolution sleeps.
2099 bool JavaThread::sleep(jlong millis) {
2100 jlong nanos;
2101 if (millis > max_jlong / NANOUNITS_PER_MILLIUNIT) {
2102 // Conversion to nanos would overflow, saturate at max
2103 nanos = max_jlong;
2104 } else {
2105 nanos = millis * NANOUNITS_PER_MILLIUNIT;
2106 }
2107 return sleep_nanos(nanos);
2108 }
2109
2110 // java.lang.Thread.sleep support
2111 // Returns true if sleep time elapsed as expected, and false
2112 // if the thread was interrupted.
2113 bool JavaThread::sleep_nanos(jlong nanos) {
2114 assert(this == Thread::current(), "thread consistency check");
2115 assert(nanos >= 0, "nanos are in range");
2116
2117 ParkEvent * const slp = this->_SleepEvent;
2118 // Because there can be races with thread interruption sending an unpark()
2119 // to the event, we explicitly reset it here to avoid an immediate return.
2120 // The actual interrupt state will be checked before we park().
2121 slp->reset();
2122 // Thread interruption establishes a happens-before ordering in the
2123 // Java Memory Model, so we need to ensure we synchronize with the
2124 // interrupt state.
2125 OrderAccess::fence();
2126
2127 jlong prevtime = os::javaTimeNanos();
2128
2129 jlong nanos_remaining = nanos;
2130
2131 for (;;) {
2132 // interruption has precedence over timing out
2133 if (this->is_interrupted(true)) {
2134 return false;
2135 }
2136
2137 if (nanos_remaining <= 0) {
2138 return true;
2139 }
2140
2141 {
2142 ThreadBlockInVM tbivm(this);
2143 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
2144 slp->park_nanos(nanos_remaining);
2145 }
2146
2147 // Update elapsed time tracking
2148 jlong newtime = os::javaTimeNanos();
2149 if (newtime - prevtime < 0) {
2150 // time moving backwards, should only happen if no monotonic clock
2151 // not a guarantee() because JVM should not abort on kernel/glibc bugs
2152 assert(false,
2153 "unexpected time moving backwards detected in JavaThread::sleep()");
2154 } else {
2155 nanos_remaining -= (newtime - prevtime);
2156 }
2157 prevtime = newtime;
2158 }
2159 }
2160
2161 // Last thread running calls java.lang.Shutdown.shutdown()
2162 void JavaThread::invoke_shutdown_hooks() {
2163 HandleMark hm(this);
2164
2165 // We could get here with a pending exception, if so clear it now.
2166 if (this->has_pending_exception()) {
2167 this->clear_pending_exception();
2168 }
2169
2170 EXCEPTION_MARK;
2171 Klass* shutdown_klass =
2172 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
2173 THREAD);
2174 if (shutdown_klass != nullptr) {
2175 // SystemDictionary::resolve_or_null will return null if there was
2176 // an exception. If we cannot load the Shutdown class, just don't
2177 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
2178 // won't be run. Note that if a shutdown hook was registered,
2179 // the Shutdown class would have already been loaded
2180 // (Runtime.addShutdownHook will load it).
2181 JavaValue result(T_VOID);
2182 JavaCalls::call_static(&result,
2183 shutdown_klass,
2184 vmSymbols::shutdown_name(),
2185 vmSymbols::void_method_signature(),
2186 THREAD);
2187 }
2188 CLEAR_PENDING_EXCEPTION;
2189 }
2190
2191 #ifndef PRODUCT
2192 void JavaThread::verify_cross_modify_fence_failure(JavaThread *thread) {
2193 report_vm_error(__FILE__, __LINE__, "Cross modify fence failure", "%p", thread);
2194 }
2195 #endif
2196
2197 // Helper function to create the java.lang.Thread object for a
2198 // VM-internal thread. The thread will have the given name, and be
2199 // a member of the "system" ThreadGroup.
2200 Handle JavaThread::create_system_thread_object(const char* name, TRAPS) {
2201 Handle string = java_lang_String::create_from_str(name, CHECK_NH);
2202
2203 // Initialize thread_oop to put it into the system threadGroup.
2204 // This is done by calling the Thread(ThreadGroup group, String name) constructor.
2205 Handle thread_group(THREAD, Universe::system_thread_group());
2206 Handle thread_oop =
2207 JavaCalls::construct_new_instance(vmClasses::Thread_klass(),
2208 vmSymbols::threadgroup_string_void_signature(),
2209 thread_group,
2210 string,
2211 CHECK_NH);
2212
2213 return thread_oop;
2214 }
2215
2216 // Starts the target JavaThread as a daemon of the given priority, and
2217 // bound to the given java.lang.Thread instance.
2218 // The Threads_lock is held for the duration.
2219 void JavaThread::start_internal_daemon(JavaThread* current, JavaThread* target,
2220 Handle thread_oop, ThreadPriority prio) {
2221
2222 assert(target->osthread() != nullptr, "target thread is not properly initialized");
2223
2224 MutexLocker mu(current, Threads_lock);
2225
2226 // Initialize the fields of the thread_oop first.
2227 if (prio != NoPriority) {
2228 java_lang_Thread::set_priority(thread_oop(), prio);
2229 // Note: we don't call os::set_priority here. Possibly we should,
2230 // else all threads should call it themselves when they first run.
2231 }
2232
2233 java_lang_Thread::set_daemon(thread_oop());
2234
2235 // Now bind the thread_oop to the target JavaThread.
2236 target->set_threadOopHandles(thread_oop());
2237 target->set_monitor_owner_id(java_lang_Thread::thread_id(thread_oop()));
2238
2239 Threads::add(target); // target is now visible for safepoint/handshake
2240 // Publish the JavaThread* in java.lang.Thread after the JavaThread* is
2241 // on a ThreadsList. We don't want to wait for the release when the
2242 // Theads_lock is dropped when the 'mu' destructor is run since the
2243 // JavaThread* is already visible to JVM/TI via the ThreadsList.
2244
2245 assert(java_lang_Thread::thread(thread_oop()) == nullptr, "must not be alive");
2246 java_lang_Thread::release_set_thread(thread_oop(), target); // isAlive == true now
2247 Thread::start(target);
2248 }
2249
2250 void JavaThread::vm_exit_on_osthread_failure(JavaThread* thread) {
2251 // At this point it may be possible that no osthread was created for the
2252 // JavaThread due to lack of resources. However, since this must work
2253 // for critical system threads just check and abort if this fails.
2254 if (thread->osthread() == nullptr) {
2255 // This isn't really an OOM condition, but historically this is what
2256 // we report.
2257 vm_exit_during_initialization("java.lang.OutOfMemoryError",
2258 os::native_thread_creation_failed_msg());
2259 }
2260 }
2261
2262 void JavaThread::pretouch_stack() {
2263 // Given an established java thread stack with usable area followed by
2264 // shadow zone and reserved/yellow/red zone, pretouch the usable area ranging
2265 // from the current frame down to the start of the shadow zone.
2266 const address end = _stack_overflow_state.shadow_zone_safe_limit();
2267 if (is_in_full_stack(end)) {
2268 char* p1 = (char*) alloca(1);
2269 address here = (address) &p1;
2270 if (is_in_full_stack(here) && here > end) {
2271 size_t to_alloc = here - end;
2272 char* p2 = (char*) alloca(to_alloc);
2273 log_trace(os, thread)("Pretouching thread stack for %zu: " RANGEFMT ".",
2274 (uintx) osthread()->thread_id(), RANGEFMTARGS(p2, to_alloc));
2275 os::pretouch_memory(p2, p2 + to_alloc,
2276 NOT_AIX(os::vm_page_size()) AIX_ONLY(4096));
2277 }
2278 }
2279 }
2280
2281 // Deferred OopHandle release support.
2282
2283 class OopHandleList : public CHeapObj<mtInternal> {
2284 static const int _count = 4;
2285 OopHandle _handles[_count];
2286 OopHandleList* _next;
2287 int _index;
2288 public:
2289 OopHandleList(OopHandleList* next) : _next(next), _index(0) {}
2290 void add(OopHandle h) {
2291 assert(_index < _count, "too many additions");
2292 _handles[_index++] = h;
2293 }
2294 ~OopHandleList() {
2295 assert(_index == _count, "usage error");
2296 for (int i = 0; i < _index; i++) {
2297 _handles[i].release(JavaThread::thread_oop_storage());
2298 }
2299 }
2300 OopHandleList* next() const { return _next; }
2301 };
2302
2303 OopHandleList* JavaThread::_oop_handle_list = nullptr;
2304
2305 // Called by the ServiceThread to do the work of releasing
2306 // the OopHandles.
2307 void JavaThread::release_oop_handles() {
2308 OopHandleList* list;
2309 {
2310 MutexLocker ml(Service_lock, Mutex::_no_safepoint_check_flag);
2311 list = _oop_handle_list;
2312 _oop_handle_list = nullptr;
2313 }
2314 assert(!SafepointSynchronize::is_at_safepoint(), "cannot be called at a safepoint");
2315
2316 while (list != nullptr) {
2317 OopHandleList* l = list;
2318 list = l->next();
2319 delete l;
2320 }
2321 }
2322
2323 // Add our OopHandles for later release.
2324 void JavaThread::add_oop_handles_for_release() {
2325 MutexLocker ml(Service_lock, Mutex::_no_safepoint_check_flag);
2326 OopHandleList* new_head = new OopHandleList(_oop_handle_list);
2327 new_head->add(_threadObj);
2328 new_head->add(_vthread);
2329 new_head->add(_jvmti_vthread);
2330 new_head->add(_scopedValueCache);
2331 _oop_handle_list = new_head;
2332 Service_lock->notify_all();
2333 }
2334
2335 #if INCLUDE_JFR
2336 void JavaThread::set_last_freeze_fail_result(freeze_result result) {
2337 assert(result != freeze_ok, "sanity check");
2338 _last_freeze_fail_result = result;
2339 _last_freeze_fail_time = Ticks::now();
2340 }
2341
2342 // Post jdk.VirtualThreadPinned event
2343 void JavaThread::post_vthread_pinned_event(EventVirtualThreadPinned* event, const char* op, freeze_result result) {
2344 assert(result != freeze_ok, "sanity check");
2345 if (event->should_commit()) {
2346 char reason[256];
2347 if (class_to_be_initialized() != nullptr) {
2348 ResourceMark rm(this);
2349 jio_snprintf(reason, sizeof reason, "Waited for initialization of %s by another thread",
2350 class_to_be_initialized()->external_name());
2351 event->set_pinnedReason(reason);
2352 } else if (class_being_initialized() != nullptr) {
2353 ResourceMark rm(this);
2354 jio_snprintf(reason, sizeof(reason), "VM call to %s.<clinit> on stack",
2355 class_being_initialized()->external_name());
2356 event->set_pinnedReason(reason);
2357 } else if (result == freeze_pinned_native) {
2358 event->set_pinnedReason("Native or VM frame on stack");
2359 } else {
2360 jio_snprintf(reason, sizeof(reason), "Freeze or preempt failed (%d)", result);
2361 event->set_pinnedReason(reason);
2362 }
2363 event->set_blockingOperation(op);
2364 event->set_carrierThread(JFR_JVM_THREAD_ID(this));
2365 event->commit();
2366 }
2367 }
2368 #endif