1 /*
  2  * Copyright (c) 1997, 2023, 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/vmSymbols.hpp"
 28 #include "code/codeCache.hpp"
 29 #include "compiler/compileBroker.hpp"
 30 #include "gc/shared/collectedHeap.hpp"
 31 #include "gc/shared/isGCActiveMark.hpp"
 32 #include "logging/log.hpp"
 33 #include "logging/logStream.hpp"
 34 #include "logging/logConfiguration.hpp"
 35 #include "memory/heapInspection.hpp"
 36 #include "memory/metaspace/metaspaceReporter.hpp"
 37 #include "memory/resourceArea.hpp"
 38 #include "memory/universe.hpp"
 39 #include "oops/symbol.hpp"
 40 #include "runtime/arguments.hpp"
 41 #include "runtime/deoptimization.hpp"
 42 #include "runtime/frame.inline.hpp"
 43 #include "runtime/interfaceSupport.inline.hpp"
 44 #include "runtime/javaThread.inline.hpp"
 45 #include "runtime/jniHandles.hpp"
 46 #include "runtime/objectMonitor.inline.hpp"
 47 #include "runtime/stackFrameStream.inline.hpp"
 48 #include "runtime/synchronizer.hpp"
 49 #include "runtime/threads.hpp"
 50 #include "runtime/threadSMR.inline.hpp"
 51 #include "runtime/vmOperations.hpp"
 52 #include "services/threadService.hpp"
 53 #include "utilities/ticks.hpp"
 54 
 55 #define VM_OP_NAME_INITIALIZE(name) #name,
 56 
 57 const char* VM_Operation::_names[VM_Operation::VMOp_Terminating] = \
 58   { VM_OPS_DO(VM_OP_NAME_INITIALIZE) };
 59 
 60 void VM_Operation::set_calling_thread(Thread* thread) {
 61   _calling_thread = thread;
 62 }
 63 
 64 void VM_Operation::evaluate() {
 65   ResourceMark rm;
 66   LogTarget(Debug, vmoperation) lt;
 67   if (lt.is_enabled()) {
 68     LogStream ls(lt);
 69     ls.print("begin ");
 70     print_on_error(&ls);
 71     ls.cr();
 72   }
 73   doit();
 74   if (lt.is_enabled()) {
 75     LogStream ls(lt);
 76     ls.print("end ");
 77     print_on_error(&ls);
 78     ls.cr();
 79   }
 80 }
 81 
 82 // Called by fatal error handler.
 83 void VM_Operation::print_on_error(outputStream* st) const {
 84   st->print("VM_Operation (" PTR_FORMAT "): ", p2i(this));
 85   st->print("%s", name());
 86 
 87   st->print(", mode: %s", evaluate_at_safepoint() ? "safepoint" : "no safepoint");
 88 
 89   if (calling_thread()) {
 90     st->print(", requested by thread " PTR_FORMAT, p2i(calling_thread()));
 91   }
 92 }
 93 
 94 void VM_ClearICs::doit() {
 95   if (_preserve_static_stubs) {
 96     CodeCache::cleanup_inline_caches_whitebox();
 97   } else {
 98     CodeCache::clear_inline_caches();
 99   }
100 }
101 
102 void VM_CleanClassLoaderDataMetaspaces::doit() {
103   ClassLoaderDataGraph::walk_metadata_and_clean_metaspaces();
104 }
105 
106 VM_DeoptimizeFrame::VM_DeoptimizeFrame(JavaThread* thread, intptr_t* id, int reason) {
107   _thread = thread;
108   _id     = id;
109   _reason = reason;
110 }
111 
112 
113 void VM_DeoptimizeFrame::doit() {
114   assert(_reason > Deoptimization::Reason_none && _reason < Deoptimization::Reason_LIMIT, "invalid deopt reason");
115   Deoptimization::deoptimize_frame_internal(_thread, _id, (Deoptimization::DeoptReason)_reason);
116 }
117 
118 
119 #ifndef PRODUCT
120 
121 void VM_DeoptimizeAll::doit() {
122   JavaThreadIteratorWithHandle jtiwh;
123   // deoptimize all java threads in the system
124   if (DeoptimizeALot) {
125     for (; JavaThread *thread = jtiwh.next(); ) {
126       if (thread->has_last_Java_frame()) {
127         thread->deoptimize();
128       }
129     }
130   } else if (DeoptimizeRandom) {
131 
132     // Deoptimize some selected threads and frames
133     int tnum = os::random() & 0x3;
134     int fnum =  os::random() & 0x3;
135     int tcount = 0;
136     for (; JavaThread *thread = jtiwh.next(); ) {
137       if (thread->has_last_Java_frame()) {
138         if (tcount++ == tnum)  {
139         tcount = 0;
140           int fcount = 0;
141           // Deoptimize some selected frames.
142           for(StackFrameStream fst(thread, false /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
143             if (fst.current()->can_be_deoptimized()) {
144               if (fcount++ == fnum) {
145                 fcount = 0;
146                 Deoptimization::deoptimize(thread, *fst.current());
147               }
148             }
149           }
150         }
151       }
152     }
153   }
154 }
155 
156 
157 void VM_ZombieAll::doit() {
158   JavaThread::cast(calling_thread())->make_zombies();
159 }
160 
161 #endif // !PRODUCT
162 
163 bool VM_PrintThreads::doit_prologue() {
164   // Get Heap_lock if concurrent locks will be dumped
165   if (_print_concurrent_locks) {
166     Heap_lock->lock();
167   }
168   return true;
169 }
170 
171 void VM_PrintThreads::doit() {
172   Threads::print_on(_out, true, false, _print_concurrent_locks, _print_extended_info);
173   if (_print_jni_handle_info) {
174     JNIHandles::print_on(_out);
175   }
176 }
177 
178 void VM_PrintThreads::doit_epilogue() {
179   if (_print_concurrent_locks) {
180     // Release Heap_lock
181     Heap_lock->unlock();
182   }
183 }
184 
185 void VM_PrintMetadata::doit() {
186   metaspace::MetaspaceReporter::print_report(_out, _scale, _flags);
187 }
188 
189 VM_FindDeadlocks::~VM_FindDeadlocks() {
190   if (_deadlocks != nullptr) {
191     DeadlockCycle* cycle = _deadlocks;
192     while (cycle != nullptr) {
193       DeadlockCycle* d = cycle;
194       cycle = cycle->next();
195       delete d;
196     }
197   }
198 }
199 
200 void VM_FindDeadlocks::doit() {
201   // Update the hazard ptr in the originating thread to the current
202   // list of threads. This VM operation needs the current list of
203   // threads for proper deadlock detection and those are the
204   // JavaThreads we need to be protected when we return info to the
205   // originating thread.
206   _setter.set();
207 
208   _deadlocks = ThreadService::find_deadlocks_at_safepoint(_setter.list(), _concurrent_locks);
209   if (_out != nullptr) {
210     int num_deadlocks = 0;
211     for (DeadlockCycle* cycle = _deadlocks; cycle != nullptr; cycle = cycle->next()) {
212       num_deadlocks++;
213       cycle->print_on_with(_setter.list(), _out);
214     }
215 
216     if (num_deadlocks == 1) {
217       _out->print_cr("\nFound 1 deadlock.\n");
218       _out->flush();
219     } else if (num_deadlocks > 1) {
220       _out->print_cr("\nFound %d deadlocks.\n", num_deadlocks);
221       _out->flush();
222     }
223   }
224 }
225 
226 VM_ThreadDump::VM_ThreadDump(ThreadDumpResult* result,
227                              int max_depth,
228                              bool with_locked_monitors,
229                              bool with_locked_synchronizers) {
230   _result = result;
231   _num_threads = 0; // 0 indicates all threads
232   _threads = nullptr;
233   _max_depth = max_depth;
234   _with_locked_monitors = with_locked_monitors;
235   _with_locked_synchronizers = with_locked_synchronizers;
236 }
237 
238 VM_ThreadDump::VM_ThreadDump(ThreadDumpResult* result,
239                              GrowableArray<instanceHandle>* threads,
240                              int num_threads,
241                              int max_depth,
242                              bool with_locked_monitors,
243                              bool with_locked_synchronizers) {
244   _result = result;
245   _num_threads = num_threads;
246   _threads = threads;
247   _max_depth = max_depth;
248   _with_locked_monitors = with_locked_monitors;
249   _with_locked_synchronizers = with_locked_synchronizers;
250 }
251 
252 bool VM_ThreadDump::doit_prologue() {
253   if (_with_locked_synchronizers) {
254     // Acquire Heap_lock to dump concurrent locks
255     Heap_lock->lock();
256   }
257 
258   return true;
259 }
260 
261 void VM_ThreadDump::doit_epilogue() {
262   if (_with_locked_synchronizers) {
263     // Release Heap_lock
264     Heap_lock->unlock();
265   }
266 }
267 
268 // Hash table of void* to a list of ObjectMonitor* owned by the JavaThread.
269 // The JavaThread's owner key is either a JavaThread* or a stack lock
270 // address in the JavaThread so we use "void*".
271 //
272 class ObjectMonitorsDump : public MonitorClosure, public ObjectMonitorsView {
273  private:
274   static unsigned int ptr_hash(void* const& s1) {
275     // 2654435761 = 2^32 * Phi (golden ratio)
276     return (unsigned int)(((uint32_t)(uintptr_t)s1) * 2654435761u);
277   }
278 
279  private:
280   class ObjectMonitorLinkedList :
281     public LinkedListImpl<ObjectMonitor*,
282                           AnyObj::C_HEAP, mtThread,
283                           AllocFailStrategy::RETURN_NULL> {};
284 
285   // ResourceHashtable SIZE is specified at compile time so we
286   // use 1031 which is the first prime after 1024.
287   typedef ResourceHashtable<void*, ObjectMonitorLinkedList*, 1031, AnyObj::C_HEAP, mtThread,
288                             &ObjectMonitorsDump::ptr_hash> PtrTable;
289   PtrTable* _ptrs;
290   size_t _key_count;
291   size_t _om_count;
292 
293   void add_list(void* key, ObjectMonitorLinkedList* list) {
294     _ptrs->put(key, list);
295     _key_count++;
296   }
297 
298   ObjectMonitorLinkedList* get_list(void* key) {
299     ObjectMonitorLinkedList** listpp = _ptrs->get(key);
300     return (listpp == nullptr) ? nullptr : *listpp;
301   }
302 
303   void add(ObjectMonitor* monitor) {
304     void* key = monitor->owner();
305 
306     ObjectMonitorLinkedList* list = get_list(key);
307     if (list == nullptr) {
308       // Create new list and add it to the hash table:
309       list = new (mtThread) ObjectMonitorLinkedList;
310       _ptrs->put(key, list);
311       _key_count++;
312     }
313 
314     assert(list->find(monitor) == nullptr, "Should not contain duplicates");
315     list->add(monitor);  // Add the ObjectMonitor to the list.
316     _om_count++;
317   }
318 
319  public:
320   // ResourceHashtable is passed to various functions and populated in
321   // different places so we allocate it using C_HEAP to make it immune
322   // from any ResourceMarks that happen to be in the code paths.
323   ObjectMonitorsDump() : _ptrs(new (mtThread) PtrTable), _key_count(0), _om_count(0) {}
324 
325   ~ObjectMonitorsDump() {
326     class CleanupObjectMonitorsDump: StackObj {
327      public:
328       bool do_entry(void*& key, ObjectMonitorLinkedList*& list) {
329         list->clear();  // clear the LinkListNodes
330         delete list;    // then delete the LinkedList
331         return true;
332       }
333     } cleanup;
334 
335     _ptrs->unlink(&cleanup);  // cleanup the LinkedLists
336     delete _ptrs;             // then delete the hash table
337   }
338 
339   // Implements MonitorClosure used to collect all owned monitors in the system
340   void do_monitor(ObjectMonitor* monitor) override {
341     assert(monitor->has_owner(), "Expects only owned monitors");
342 
343     if (monitor->is_owner_anonymous()) {
344       // There's no need to collect anonymous owned monitors
345       // because the caller of this code is only interested
346       // in JNI owned monitors.
347       return;
348     }
349 
350     add(monitor);
351   }
352 
353   // Implements the ObjectMonitorsView interface
354   void visit(MonitorClosure* closure, JavaThread* thread) override {
355     ObjectMonitorLinkedList* list = get_list(thread);
356     LinkedListIterator<ObjectMonitor*> iter(list != nullptr ? list->head() : nullptr);
357     while (!iter.is_empty()) {
358       ObjectMonitor* monitor = *iter.next();
359       closure->do_monitor(monitor);
360     }
361   }
362 
363   size_t key_count() { return _key_count; }
364   size_t om_count() { return _om_count; }
365 };
366 
367 void VM_ThreadDump::doit() {
368   ResourceMark rm;
369 
370   // Set the hazard ptr in the originating thread to protect the
371   // current list of threads. This VM operation needs the current list
372   // of threads for a proper dump and those are the JavaThreads we need
373   // to be protected when we return info to the originating thread.
374   _result->set_t_list();
375 
376   ConcurrentLocksDump concurrent_locks(true);
377   if (_with_locked_synchronizers) {
378     concurrent_locks.dump_at_safepoint();
379   }
380 
381   ObjectMonitorsDump object_monitors;
382   if (_with_locked_monitors) {
383     // Gather information about owned monitors.
384     ObjectSynchronizer::owned_monitors_iterate(&object_monitors);
385 
386     // If there are many object monitors in the system then the above iteration
387     // can start to take time. Be friendly to following thread dumps by telling
388     // the MonitorDeflationThread to deflate monitors.
389     //
390     // This is trying to be somewhat backwards compatible with the previous
391     // implementation, which performed monitor deflation right here. We might
392     // want to reconsider the need to trigger monitor deflation from the thread
393     // dumping and instead maybe tweak the deflation heuristics.
394     ObjectSynchronizer::request_deflate_idle_monitors();
395   }
396 
397   if (_num_threads == 0) {
398     // Snapshot all live threads
399 
400     for (uint i = 0; i < _result->t_list()->length(); i++) {
401       JavaThread* jt = _result->t_list()->thread_at(i);
402       if (jt->is_exiting() ||
403           jt->is_hidden_from_external_view())  {
404         // skip terminating threads and hidden threads
405         continue;
406       }
407       ThreadConcurrentLocks* tcl = nullptr;
408       if (_with_locked_synchronizers) {
409         tcl = concurrent_locks.thread_concurrent_locks(jt);
410       }
411       snapshot_thread(jt, tcl, &object_monitors);
412     }
413   } else {
414     // Snapshot threads in the given _threads array
415     // A dummy snapshot is created if a thread doesn't exist
416 
417     for (int i = 0; i < _num_threads; i++) {
418       instanceHandle th = _threads->at(i);
419       if (th() == nullptr) {
420         // skip if the thread doesn't exist
421         // Add a dummy snapshot
422         _result->add_thread_snapshot();
423         continue;
424       }
425 
426       // Dump thread stack only if the thread is alive and not exiting
427       // and not VM internal thread.
428       JavaThread* jt = java_lang_Thread::thread(th());
429       if (jt != nullptr && !_result->t_list()->includes(jt)) {
430         // _threads[i] doesn't refer to a valid JavaThread; this check
431         // is primarily for JVM_DumpThreads() which doesn't have a good
432         // way to validate the _threads array.
433         jt = nullptr;
434       }
435       if (jt == nullptr || /* thread not alive */
436           jt->is_exiting() ||
437           jt->is_hidden_from_external_view())  {
438         // add a null snapshot if skipped
439         _result->add_thread_snapshot();
440         continue;
441       }
442       ThreadConcurrentLocks* tcl = nullptr;
443       if (_with_locked_synchronizers) {
444         tcl = concurrent_locks.thread_concurrent_locks(jt);
445       }
446       snapshot_thread(jt, tcl, &object_monitors);
447     }
448   }
449 }
450 
451 void VM_ThreadDump::snapshot_thread(JavaThread* java_thread, ThreadConcurrentLocks* tcl,
452                                     ObjectMonitorsView* monitors) {
453   ThreadSnapshot* snapshot = _result->add_thread_snapshot(java_thread);
454   snapshot->dump_stack_at_safepoint(_max_depth, _with_locked_monitors, monitors, false);
455   snapshot->set_concurrent_locks(tcl);
456 }
457 
458 volatile bool VM_Exit::_vm_exited = false;
459 Thread * volatile VM_Exit::_shutdown_thread = nullptr;
460 
461 int VM_Exit::set_vm_exited() {
462 
463   Thread * thr_cur = Thread::current();
464 
465   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint already");
466 
467   int num_active = 0;
468 
469   _shutdown_thread = thr_cur;
470   _vm_exited = true;                                // global flag
471   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thr = jtiwh.next(); ) {
472     if (thr != thr_cur && thr->thread_state() == _thread_in_native) {
473       ++num_active;
474       thr->set_terminated(JavaThread::_vm_exited);  // per-thread flag
475     }
476   }
477 
478   return num_active;
479 }
480 
481 int VM_Exit::wait_for_threads_in_native_to_block() {
482   // VM exits at safepoint. This function must be called at the final safepoint
483   // to wait for threads in _thread_in_native state to be quiescent.
484   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint already");
485 
486   Thread * thr_cur = Thread::current();
487   Monitor timer(Mutex::nosafepoint, "VM_ExitTimer_lock");
488 
489   // Compiler threads need longer wait because they can access VM data directly
490   // while in native. If they are active and some structures being used are
491   // deleted by the shutdown sequence, they will crash. On the other hand, user
492   // threads must go through native=>Java/VM transitions first to access VM
493   // data, and they will be stopped during state transition. In theory, we
494   // don't have to wait for user threads to be quiescent, but it's always
495   // better to terminate VM when current thread is the only active thread, so
496   // wait for user threads too. Numbers are in 10 milliseconds.
497   int wait_time_per_attempt = 10;               // in milliseconds
498   int max_wait_attempts_user_thread = UserThreadWaitAttemptsAtExit;
499   int max_wait_attempts_compiler_thread = 1000; // at least 10 seconds
500 
501   int attempts = 0;
502   JavaThreadIteratorWithHandle jtiwh;
503   while (true) {
504     int num_active = 0;
505     int num_active_compiler_thread = 0;
506 
507     jtiwh.rewind();
508     for (; JavaThread *thr = jtiwh.next(); ) {
509       if (thr!=thr_cur && thr->thread_state() == _thread_in_native) {
510         num_active++;
511         if (thr->is_Compiler_thread()) {
512 #if INCLUDE_JVMCI
513           CompilerThread* ct = (CompilerThread*) thr;
514           if (ct->compiler() == nullptr || !ct->compiler()->is_jvmci()) {
515             num_active_compiler_thread++;
516           } else {
517             // A JVMCI compiler thread never accesses VM data structures
518             // while in _thread_in_native state so there's no need to wait
519             // for it and potentially add a 300 millisecond delay to VM
520             // shutdown.
521             num_active--;
522           }
523 #else
524           num_active_compiler_thread++;
525 #endif
526         }
527       }
528     }
529 
530     if (num_active == 0) {
531        return 0;
532     } else if (attempts >= max_wait_attempts_compiler_thread) {
533        return num_active;
534     } else if (num_active_compiler_thread == 0 &&
535                attempts >= max_wait_attempts_user_thread) {
536        return num_active;
537     }
538 
539     attempts++;
540 
541     MonitorLocker ml(&timer, Mutex::_no_safepoint_check_flag);
542     ml.wait(wait_time_per_attempt);
543   }
544 }
545 
546 void VM_Exit::doit() {
547 
548   if (VerifyBeforeExit) {
549     HandleMark hm(VMThread::vm_thread());
550     // Among other things, this ensures that Eden top is correct.
551     Universe::heap()->prepare_for_verify();
552     // Silent verification so as not to pollute normal output,
553     // unless we really asked for it.
554     Universe::verify();
555   }
556 
557   CompileBroker::set_should_block();
558 
559   // Wait for a short period for threads in native to block. Any thread
560   // still executing native code after the wait will be stopped at
561   // native==>Java/VM barriers.
562   // Among 16276 JCK tests, 94% of them come here without any threads still
563   // running in native; the other 6% are quiescent within 250ms (Ultra 80).
564   wait_for_threads_in_native_to_block();
565 
566   set_vm_exited();
567 
568   // The ObjectMonitor subsystem uses perf counters so do this before
569   // we call exit_globals() so we don't run afoul of perfMemory_exit().
570   ObjectSynchronizer::do_final_audit_and_print_stats();
571 
572   // We'd like to call IdealGraphPrinter::clean_up() to finalize the
573   // XML logging, but we can't safely do that here. The logic to make
574   // XML termination logging safe is tied to the termination of the
575   // VMThread, and it doesn't terminate on this exit path. See 8222534.
576 
577   // cleanup globals resources before exiting. exit_globals() currently
578   // cleans up outputStream resources and PerfMemory resources.
579   exit_globals();
580 
581   LogConfiguration::finalize();
582 
583   // Check for exit hook
584   exit_hook_t exit_hook = Arguments::exit_hook();
585   if (exit_hook != nullptr) {
586     // exit hook should exit.
587     exit_hook(_exit_code);
588     // ... but if it didn't, we must do it here
589     vm_direct_exit(_exit_code);
590   } else {
591     vm_direct_exit(_exit_code);
592   }
593 }
594 
595 
596 void VM_Exit::wait_if_vm_exited() {
597   if (_vm_exited &&
598       Thread::current_or_null() != _shutdown_thread) {
599     // _vm_exited is set at safepoint, and the Threads_lock is never released
600     // so we will block here until the process dies.
601     Threads_lock->lock();
602     ShouldNotReachHere();
603   }
604 }
605 
606 void VM_PrintCompileQueue::doit() {
607   CompileBroker::print_compile_queues(_out);
608 }
609 
610 #if INCLUDE_SERVICES
611 void VM_PrintClassHierarchy::doit() {
612   KlassHierarchy::print_class_hierarchy(_out, _print_interfaces, _print_subclasses, _classname);
613 }
614 #endif