1 /*
2 * Copyright (c) 1997, 2024, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classLoaderDataGraph.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "classfile/symbolTable.hpp"
29 #include "classfile/vmSymbols.hpp"
30 #include "code/codeCache.hpp"
31 #include "compiler/compileBroker.hpp"
32 #include "gc/shared/collectedHeap.hpp"
33 #include "gc/shared/isGCActiveMark.hpp"
34 #include "logging/log.hpp"
35 #include "logging/logStream.hpp"
36 #include "logging/logConfiguration.hpp"
37 #include "memory/heapInspection.hpp"
38 #include "memory/metaspace/metaspaceReporter.hpp"
39 #include "memory/resourceArea.hpp"
40 #include "memory/universe.hpp"
41 #include "oops/symbol.hpp"
42 #include "runtime/arguments.hpp"
43 #include "runtime/deoptimization.hpp"
44 #include "runtime/frame.inline.hpp"
45 #include "runtime/interfaceSupport.inline.hpp"
46 #include "runtime/javaThread.inline.hpp"
47 #include "runtime/jniHandles.hpp"
48 #include "runtime/objectMonitor.inline.hpp"
49 #include "runtime/stackFrameStream.inline.hpp"
50 #include "runtime/synchronizer.hpp"
51 #include "runtime/threads.hpp"
52 #include "runtime/threadSMR.inline.hpp"
53 #include "runtime/vmOperations.hpp"
54 #include "services/threadService.hpp"
55 #include "utilities/ticks.hpp"
56
57 #define VM_OP_NAME_INITIALIZE(name) #name,
58
59 const char* VM_Operation::_names[VM_Operation::VMOp_Terminating] = \
60 { VM_OPS_DO(VM_OP_NAME_INITIALIZE) };
61
62 void VM_Operation::set_calling_thread(Thread* thread) {
63 _calling_thread = thread;
64 }
65
66 void VM_Operation::evaluate() {
67 ResourceMark rm;
68 LogTarget(Debug, vmoperation) lt;
69 if (lt.is_enabled()) {
70 LogStream ls(lt);
71 ls.print("begin ");
72 print_on_error(&ls);
73 ls.cr();
74 }
75 doit();
76 if (lt.is_enabled()) {
77 LogStream ls(lt);
78 ls.print("end ");
79 print_on_error(&ls);
80 ls.cr();
81 }
82 }
83
84 // Called by fatal error handler.
85 void VM_Operation::print_on_error(outputStream* st) const {
86 st->print("VM_Operation (" PTR_FORMAT "): ", p2i(this));
87 st->print("%s", name());
88
89 st->print(", mode: %s", evaluate_at_safepoint() ? "safepoint" : "no safepoint");
90
91 if (calling_thread()) {
92 st->print(", requested by thread " PTR_FORMAT, p2i(calling_thread()));
93 }
94 }
95
96 void VM_ClearICs::doit() {
97 if (_preserve_static_stubs) {
98 CodeCache::cleanup_inline_caches_whitebox();
99 } else {
100 CodeCache::clear_inline_caches();
101 }
102 }
103
104 void VM_CleanClassLoaderDataMetaspaces::doit() {
105 ClassLoaderDataGraph::walk_metadata_and_clean_metaspaces();
106 }
107
108 void VM_RehashStringTable::doit() {
109 StringTable::rehash_table();
110 }
111
112 void VM_RehashSymbolTable::doit() {
113 SymbolTable::rehash_table();
114 }
115
116 VM_DeoptimizeFrame::VM_DeoptimizeFrame(JavaThread* thread, intptr_t* id, int reason) {
117 _thread = thread;
118 _id = id;
119 _reason = reason;
120 }
121
122
123 void VM_DeoptimizeFrame::doit() {
124 assert(_reason > Deoptimization::Reason_none && _reason < Deoptimization::Reason_LIMIT, "invalid deopt reason");
125 Deoptimization::deoptimize_frame_internal(_thread, _id, (Deoptimization::DeoptReason)_reason);
126 }
127
128
129 #ifndef PRODUCT
130
131 void VM_DeoptimizeAll::doit() {
132 JavaThreadIteratorWithHandle jtiwh;
133 // deoptimize all java threads in the system
134 if (DeoptimizeALot) {
135 for (; JavaThread *thread = jtiwh.next(); ) {
136 if (thread->has_last_Java_frame()) {
137 thread->deoptimize();
138 }
139 }
140 } else if (DeoptimizeRandom) {
141
142 // Deoptimize some selected threads and frames
143 int tnum = os::random() & 0x3;
144 int fnum = os::random() & 0x3;
145 int tcount = 0;
146 for (; JavaThread *thread = jtiwh.next(); ) {
147 if (thread->has_last_Java_frame()) {
148 if (tcount++ == tnum) {
149 tcount = 0;
150 int fcount = 0;
151 // Deoptimize some selected frames.
152 for(StackFrameStream fst(thread, false /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
153 if (fst.current()->can_be_deoptimized()) {
154 if (fcount++ == fnum) {
155 fcount = 0;
156 Deoptimization::deoptimize(thread, *fst.current());
157 }
158 }
159 }
160 }
161 }
162 }
163 }
164 }
165
166
167 void VM_ZombieAll::doit() {
168 JavaThread::cast(calling_thread())->make_zombies();
169 }
170
171 #endif // !PRODUCT
172
173 bool VM_PrintThreads::doit_prologue() {
174 // Get Heap_lock if concurrent locks will be dumped
175 if (_print_concurrent_locks) {
176 Heap_lock->lock();
177 }
178 return true;
179 }
180
181 void VM_PrintThreads::doit() {
182 Threads::print_on(_out, true, false, _print_concurrent_locks, _print_extended_info);
183 if (_print_jni_handle_info) {
184 JNIHandles::print_on(_out);
185 }
186 }
187
188 void VM_PrintThreads::doit_epilogue() {
189 if (_print_concurrent_locks) {
190 // Release Heap_lock
191 Heap_lock->unlock();
192 }
193 }
194
195 void VM_PrintMetadata::doit() {
196 metaspace::MetaspaceReporter::print_report(_out, _scale, _flags);
197 }
198
199 VM_FindDeadlocks::~VM_FindDeadlocks() {
200 if (_deadlocks != nullptr) {
201 DeadlockCycle* cycle = _deadlocks;
202 while (cycle != nullptr) {
203 DeadlockCycle* d = cycle;
204 cycle = cycle->next();
205 delete d;
206 }
207 }
208 }
209
210 void VM_FindDeadlocks::doit() {
211 // Update the hazard ptr in the originating thread to the current
212 // list of threads. This VM operation needs the current list of
213 // threads for proper deadlock detection and those are the
214 // JavaThreads we need to be protected when we return info to the
215 // originating thread.
216 _setter.set();
217
218 _deadlocks = ThreadService::find_deadlocks_at_safepoint(_setter.list(), _concurrent_locks);
219 if (_out != nullptr) {
220 int num_deadlocks = 0;
221 for (DeadlockCycle* cycle = _deadlocks; cycle != nullptr; cycle = cycle->next()) {
222 num_deadlocks++;
223 cycle->print_on_with(_setter.list(), _out);
224 }
225
226 if (num_deadlocks == 1) {
227 _out->print_cr("\nFound 1 deadlock.\n");
228 _out->flush();
229 } else if (num_deadlocks > 1) {
230 _out->print_cr("\nFound %d deadlocks.\n", num_deadlocks);
231 _out->flush();
232 }
233 }
234 }
235
236 VM_ThreadDump::VM_ThreadDump(ThreadDumpResult* result,
237 int max_depth,
238 bool with_locked_monitors,
239 bool with_locked_synchronizers) {
240 _result = result;
241 _num_threads = 0; // 0 indicates all threads
242 _threads = nullptr;
243 _max_depth = max_depth;
244 _with_locked_monitors = with_locked_monitors;
245 _with_locked_synchronizers = with_locked_synchronizers;
246 }
247
248 VM_ThreadDump::VM_ThreadDump(ThreadDumpResult* result,
249 GrowableArray<instanceHandle>* threads,
250 int num_threads,
251 int max_depth,
252 bool with_locked_monitors,
253 bool with_locked_synchronizers) {
254 _result = result;
255 _num_threads = num_threads;
256 _threads = threads;
257 _max_depth = max_depth;
258 _with_locked_monitors = with_locked_monitors;
259 _with_locked_synchronizers = with_locked_synchronizers;
260 }
261
262 bool VM_ThreadDump::doit_prologue() {
263 if (_with_locked_synchronizers) {
264 // Acquire Heap_lock to dump concurrent locks
265 Heap_lock->lock();
266 }
267
268 return true;
269 }
270
271 void VM_ThreadDump::doit_epilogue() {
272 if (_with_locked_synchronizers) {
273 // Release Heap_lock
274 Heap_lock->unlock();
275 }
276 }
277
278 // Hash table of void* to a list of ObjectMonitor* owned by the JavaThread.
279 // The JavaThread's owner key is either a JavaThread* or a stack lock
280 // address in the JavaThread so we use "void*".
281 //
282 class ObjectMonitorsDump : public MonitorClosure, public ObjectMonitorsView {
283 private:
284 static unsigned int ptr_hash(void* const& s1) {
285 // 2654435761 = 2^32 * Phi (golden ratio)
286 return (unsigned int)(((uint32_t)(uintptr_t)s1) * 2654435761u);
287 }
288
289 private:
290 class ObjectMonitorLinkedList :
291 public LinkedListImpl<ObjectMonitor*,
292 AnyObj::C_HEAP, mtThread,
293 AllocFailStrategy::RETURN_NULL> {};
294
295 // ResourceHashtable SIZE is specified at compile time so we
296 // use 1031 which is the first prime after 1024.
297 typedef ResourceHashtable<void*, ObjectMonitorLinkedList*, 1031, AnyObj::C_HEAP, mtThread,
298 &ObjectMonitorsDump::ptr_hash> PtrTable;
299 PtrTable* _ptrs;
300 size_t _key_count;
301 size_t _om_count;
302
303 void add_list(void* key, ObjectMonitorLinkedList* list) {
304 _ptrs->put(key, list);
305 _key_count++;
306 }
307
308 ObjectMonitorLinkedList* get_list(void* key) {
309 ObjectMonitorLinkedList** listpp = _ptrs->get(key);
310 return (listpp == nullptr) ? nullptr : *listpp;
311 }
312
313 void add(ObjectMonitor* monitor) {
314 void* key = monitor->owner();
315
316 ObjectMonitorLinkedList* list = get_list(key);
317 if (list == nullptr) {
318 // Create new list and add it to the hash table:
319 list = new (mtThread) ObjectMonitorLinkedList;
320 _ptrs->put(key, list);
321 _key_count++;
322 }
323
324 assert(list->find(monitor) == nullptr, "Should not contain duplicates");
325 list->add(monitor); // Add the ObjectMonitor to the list.
326 _om_count++;
327 }
328
329 public:
330 // ResourceHashtable is passed to various functions and populated in
331 // different places so we allocate it using C_HEAP to make it immune
332 // from any ResourceMarks that happen to be in the code paths.
333 ObjectMonitorsDump() : _ptrs(new (mtThread) PtrTable), _key_count(0), _om_count(0) {}
334
335 ~ObjectMonitorsDump() {
336 class CleanupObjectMonitorsDump: StackObj {
337 public:
338 bool do_entry(void*& key, ObjectMonitorLinkedList*& list) {
339 list->clear(); // clear the LinkListNodes
340 delete list; // then delete the LinkedList
341 return true;
342 }
343 } cleanup;
344
345 _ptrs->unlink(&cleanup); // cleanup the LinkedLists
346 delete _ptrs; // then delete the hash table
347 }
348
349 // Implements MonitorClosure used to collect all owned monitors in the system
350 void do_monitor(ObjectMonitor* monitor) override {
351 assert(monitor->has_owner(), "Expects only owned monitors");
352
353 if (monitor->is_owner_anonymous()) {
354 // There's no need to collect anonymous owned monitors
355 // because the caller of this code is only interested
356 // in JNI owned monitors.
357 return;
358 }
359
360 if (monitor->object_peek() == nullptr) {
361 // JNI code doesn't necessarily keep the monitor object
362 // alive. Filter out monitors with dead objects.
363 return;
364 }
365
366 add(monitor);
367 }
368
369 // Implements the ObjectMonitorsView interface
370 void visit(MonitorClosure* closure, JavaThread* thread) override {
371 ObjectMonitorLinkedList* list = get_list(thread);
372 LinkedListIterator<ObjectMonitor*> iter(list != nullptr ? list->head() : nullptr);
373 while (!iter.is_empty()) {
374 ObjectMonitor* monitor = *iter.next();
375 closure->do_monitor(monitor);
376 }
377 }
378
379 size_t key_count() { return _key_count; }
380 size_t om_count() { return _om_count; }
381 };
382
383 void VM_ThreadDump::doit() {
384 ResourceMark rm;
385
386 // Set the hazard ptr in the originating thread to protect the
387 // current list of threads. This VM operation needs the current list
388 // of threads for a proper dump and those are the JavaThreads we need
389 // to be protected when we return info to the originating thread.
390 _result->set_t_list();
391
392 ConcurrentLocksDump concurrent_locks(true);
393 if (_with_locked_synchronizers) {
394 concurrent_locks.dump_at_safepoint();
395 }
396
397 ObjectMonitorsDump object_monitors;
398 if (_with_locked_monitors) {
399 // Gather information about owned monitors.
400 ObjectSynchronizer::owned_monitors_iterate(&object_monitors);
401
402 // If there are many object monitors in the system then the above iteration
403 // can start to take time. Be friendly to following thread dumps by telling
404 // the MonitorDeflationThread to deflate monitors.
405 //
406 // This is trying to be somewhat backwards compatible with the previous
407 // implementation, which performed monitor deflation right here. We might
408 // want to reconsider the need to trigger monitor deflation from the thread
409 // dumping and instead maybe tweak the deflation heuristics.
410 ObjectSynchronizer::request_deflate_idle_monitors();
411 }
412
413 if (_num_threads == 0) {
414 // Snapshot all live threads
415
416 for (uint i = 0; i < _result->t_list()->length(); i++) {
417 JavaThread* jt = _result->t_list()->thread_at(i);
418 if (jt->is_exiting() ||
419 jt->is_hidden_from_external_view()) {
420 // skip terminating threads and hidden threads
421 continue;
422 }
423 ThreadConcurrentLocks* tcl = nullptr;
424 if (_with_locked_synchronizers) {
425 tcl = concurrent_locks.thread_concurrent_locks(jt);
426 }
427 snapshot_thread(jt, tcl, &object_monitors);
428 }
429 } else {
430 // Snapshot threads in the given _threads array
431 // A dummy snapshot is created if a thread doesn't exist
432
433 for (int i = 0; i < _num_threads; i++) {
434 instanceHandle th = _threads->at(i);
435 if (th() == nullptr) {
436 // skip if the thread doesn't exist
437 // Add a dummy snapshot
438 _result->add_thread_snapshot();
439 continue;
440 }
441
442 // Dump thread stack only if the thread is alive and not exiting
443 // and not VM internal thread.
444 JavaThread* jt = java_lang_Thread::thread(th());
445 if (jt != nullptr && !_result->t_list()->includes(jt)) {
446 // _threads[i] doesn't refer to a valid JavaThread; this check
447 // is primarily for JVM_DumpThreads() which doesn't have a good
448 // way to validate the _threads array.
449 jt = nullptr;
450 }
451 if (jt == nullptr || /* thread not alive */
452 jt->is_exiting() ||
453 jt->is_hidden_from_external_view()) {
454 // add a null snapshot if skipped
455 _result->add_thread_snapshot();
456 continue;
457 }
458 ThreadConcurrentLocks* tcl = nullptr;
459 if (_with_locked_synchronizers) {
460 tcl = concurrent_locks.thread_concurrent_locks(jt);
461 }
462 snapshot_thread(jt, tcl, &object_monitors);
463 }
464 }
465 }
466
467 void VM_ThreadDump::snapshot_thread(JavaThread* java_thread, ThreadConcurrentLocks* tcl,
468 ObjectMonitorsView* monitors) {
469 ThreadSnapshot* snapshot = _result->add_thread_snapshot(java_thread);
470 snapshot->dump_stack_at_safepoint(_max_depth, _with_locked_monitors, monitors, false);
471 snapshot->set_concurrent_locks(tcl);
472 }
473
474 volatile bool VM_Exit::_vm_exited = false;
475 Thread * volatile VM_Exit::_shutdown_thread = nullptr;
476
477 int VM_Exit::set_vm_exited() {
478
479 Thread * thr_cur = Thread::current();
480
481 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint already");
482
483 int num_active = 0;
484
485 _shutdown_thread = thr_cur;
486 _vm_exited = true; // global flag
487 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thr = jtiwh.next(); ) {
488 if (thr != thr_cur && thr->thread_state() == _thread_in_native) {
489 ++num_active;
490 thr->set_terminated(JavaThread::_vm_exited); // per-thread flag
491 }
492 }
493
494 return num_active;
495 }
496
497 int VM_Exit::wait_for_threads_in_native_to_block() {
498 // VM exits at safepoint. This function must be called at the final safepoint
499 // to wait for threads in _thread_in_native state to be quiescent.
500 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint already");
501
502 Thread * thr_cur = Thread::current();
503 Monitor timer(Mutex::nosafepoint, "VM_ExitTimer_lock");
504
505 // Compiler threads need longer wait because they can access VM data directly
506 // while in native. If they are active and some structures being used are
507 // deleted by the shutdown sequence, they will crash. On the other hand, user
508 // threads must go through native=>Java/VM transitions first to access VM
509 // data, and they will be stopped during state transition. In theory, we
510 // don't have to wait for user threads to be quiescent, but it's always
511 // better to terminate VM when current thread is the only active thread, so
512 // wait for user threads too. Numbers are in 10 milliseconds.
513 int wait_time_per_attempt = 10; // in milliseconds
514 int max_wait_attempts_user_thread = UserThreadWaitAttemptsAtExit;
515 int max_wait_attempts_compiler_thread = 1000; // at least 10 seconds
516
517 int attempts = 0;
518 JavaThreadIteratorWithHandle jtiwh;
519 while (true) {
520 int num_active = 0;
521 int num_active_compiler_thread = 0;
522
523 jtiwh.rewind();
524 for (; JavaThread *thr = jtiwh.next(); ) {
525 if (thr!=thr_cur && thr->thread_state() == _thread_in_native) {
526 num_active++;
527 if (thr->is_Compiler_thread()) {
528 #if INCLUDE_JVMCI
529 CompilerThread* ct = (CompilerThread*) thr;
530 if (ct->compiler() == nullptr || !ct->compiler()->is_jvmci()) {
531 num_active_compiler_thread++;
532 } else {
533 // A JVMCI compiler thread never accesses VM data structures
534 // while in _thread_in_native state so there's no need to wait
535 // for it and potentially add a 300 millisecond delay to VM
536 // shutdown.
537 num_active--;
538 }
539 #else
540 num_active_compiler_thread++;
541 #endif
542 }
543 }
544 }
545
546 if (num_active == 0) {
547 return 0;
548 } else if (attempts >= max_wait_attempts_compiler_thread) {
549 return num_active;
550 } else if (num_active_compiler_thread == 0 &&
551 attempts >= max_wait_attempts_user_thread) {
552 return num_active;
553 }
554
555 attempts++;
556
557 MonitorLocker ml(&timer, Mutex::_no_safepoint_check_flag);
558 ml.wait(wait_time_per_attempt);
559 }
560 }
561
562 void VM_Exit::doit() {
563
564 if (VerifyBeforeExit) {
565 HandleMark hm(VMThread::vm_thread());
566 // Among other things, this ensures that Eden top is correct.
567 Universe::heap()->prepare_for_verify();
568 // Silent verification so as not to pollute normal output,
569 // unless we really asked for it.
570 Universe::verify();
571 }
572
573 CompileBroker::set_should_block();
574
575 // Wait for a short period for threads in native to block. Any thread
576 // still executing native code after the wait will be stopped at
577 // native==>Java/VM barriers.
578 // Among 16276 JCK tests, 94% of them come here without any threads still
579 // running in native; the other 6% are quiescent within 250ms (Ultra 80).
580 wait_for_threads_in_native_to_block();
581
582 set_vm_exited();
583
584 // The ObjectMonitor subsystem uses perf counters so do this before
585 // we call exit_globals() so we don't run afoul of perfMemory_exit().
586 ObjectSynchronizer::do_final_audit_and_print_stats();
587
588 // We'd like to call IdealGraphPrinter::clean_up() to finalize the
589 // XML logging, but we can't safely do that here. The logic to make
590 // XML termination logging safe is tied to the termination of the
591 // VMThread, and it doesn't terminate on this exit path. See 8222534.
592
593 // cleanup globals resources before exiting. exit_globals() currently
594 // cleans up outputStream resources and PerfMemory resources.
595 exit_globals();
596
597 LogConfiguration::finalize();
598
599 // Check for exit hook
600 exit_hook_t exit_hook = Arguments::exit_hook();
601 if (exit_hook != nullptr) {
602 // exit hook should exit.
603 exit_hook(_exit_code);
604 // ... but if it didn't, we must do it here
605 vm_direct_exit(_exit_code);
606 } else {
607 vm_direct_exit(_exit_code);
608 }
609 }
610
611
612 void VM_Exit::wait_if_vm_exited() {
613 if (_vm_exited &&
614 Thread::current_or_null() != _shutdown_thread) {
615 // _vm_exited is set at safepoint, and the Threads_lock is never released
616 // so we will block here until the process dies.
617 Threads_lock->lock();
618 ShouldNotReachHere();
619 }
620 }
621
622 void VM_PrintCompileQueue::doit() {
623 CompileBroker::print_compile_queues(_out);
624 }
625
626 #if INCLUDE_SERVICES
627 void VM_PrintClassHierarchy::doit() {
628 KlassHierarchy::print_class_hierarchy(_out, _print_interfaces, _print_subclasses, _classname);
629 }
630 #endif