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