1 /*
2 * Copyright (c) 1997, 2020, 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.inline.hpp"
27 #include "classfile/dictionary.hpp"
28 #include "classfile/stringTable.hpp"
29 #include "classfile/symbolTable.hpp"
30 #include "classfile/systemDictionary.hpp"
31 #include "code/codeCache.hpp"
32 #include "code/icBuffer.hpp"
33 #include "code/nmethod.hpp"
34 #include "code/pcDesc.hpp"
35 #include "code/scopeDesc.hpp"
36 #include "compiler/compilationPolicy.hpp"
37 #include "gc/shared/collectedHeap.hpp"
38 #include "gc/shared/gcLocker.hpp"
39 #include "gc/shared/oopStorage.hpp"
40 #include "gc/shared/strongRootsScope.hpp"
41 #include "gc/shared/workgroup.hpp"
42 #include "interpreter/interpreter.hpp"
43 #include "jfr/jfrEvents.hpp"
44 #include "logging/log.hpp"
45 #include "logging/logStream.hpp"
46 #include "memory/resourceArea.hpp"
47 #include "memory/universe.hpp"
48 #include "oops/oop.inline.hpp"
49 #include "oops/symbol.hpp"
50 #include "runtime/atomic.hpp"
51 #include "runtime/deoptimization.hpp"
52 #include "runtime/frame.inline.hpp"
53 #include "runtime/handles.inline.hpp"
54 #include "runtime/interfaceSupport.inline.hpp"
55 #include "runtime/mutexLocker.hpp"
56 #include "runtime/orderAccess.hpp"
57 #include "runtime/osThread.hpp"
58 #include "runtime/safepoint.hpp"
59 #include "runtime/safepointMechanism.inline.hpp"
60 #include "runtime/signature.hpp"
61 #include "runtime/stubCodeGenerator.hpp"
62 #include "runtime/stubRoutines.hpp"
63 #include "runtime/sweeper.hpp"
64 #include "runtime/synchronizer.hpp"
65 #include "runtime/thread.inline.hpp"
66 #include "runtime/threadSMR.hpp"
67 #include "runtime/timerTrace.hpp"
68 #include "services/runtimeService.hpp"
69 #include "utilities/events.hpp"
70 #include "utilities/macros.hpp"
71
72 static void post_safepoint_begin_event(EventSafepointBegin& event,
73 uint64_t safepoint_id,
74 int thread_count,
75 int critical_thread_count) {
76 if (event.should_commit()) {
77 event.set_safepointId(safepoint_id);
78 event.set_totalThreadCount(thread_count);
79 event.set_jniCriticalThreadCount(critical_thread_count);
80 event.commit();
81 }
82 }
83
84 static void post_safepoint_cleanup_event(EventSafepointCleanup& event, uint64_t safepoint_id) {
85 if (event.should_commit()) {
86 event.set_safepointId(safepoint_id);
87 event.commit();
88 }
89 }
90
91 static void post_safepoint_synchronize_event(EventSafepointStateSynchronization& event,
92 uint64_t safepoint_id,
93 int initial_number_of_threads,
94 int threads_waiting_to_block,
95 uint64_t iterations) {
96 if (event.should_commit()) {
97 event.set_safepointId(safepoint_id);
98 event.set_initialThreadCount(initial_number_of_threads);
99 event.set_runningThreadCount(threads_waiting_to_block);
100 event.set_iterations(iterations);
101 event.commit();
102 }
103 }
104
105 static void post_safepoint_cleanup_task_event(EventSafepointCleanupTask& event,
106 uint64_t safepoint_id,
107 const char* name) {
108 if (event.should_commit()) {
109 event.set_safepointId(safepoint_id);
110 event.set_name(name);
111 event.commit();
112 }
113 }
114
115 static void post_safepoint_end_event(EventSafepointEnd& event, uint64_t safepoint_id) {
116 if (event.should_commit()) {
117 event.set_safepointId(safepoint_id);
118 event.commit();
119 }
120 }
121
122 // SafepointCheck
123 SafepointStateTracker::SafepointStateTracker(uint64_t safepoint_id, bool at_safepoint)
124 : _safepoint_id(safepoint_id), _at_safepoint(at_safepoint) {}
125
126 bool SafepointStateTracker::safepoint_state_changed() {
127 return _safepoint_id != SafepointSynchronize::safepoint_id() ||
128 _at_safepoint != SafepointSynchronize::is_at_safepoint();
129 }
130
131 // --------------------------------------------------------------------------------------------------
132 // Implementation of Safepoint begin/end
133
134 SafepointSynchronize::SynchronizeState volatile SafepointSynchronize::_state = SafepointSynchronize::_not_synchronized;
135 int SafepointSynchronize::_waiting_to_block = 0;
136 volatile uint64_t SafepointSynchronize::_safepoint_counter = 0;
137 uint64_t SafepointSynchronize::_safepoint_id = 0;
138 const uint64_t SafepointSynchronize::InactiveSafepointCounter = 0;
139 int SafepointSynchronize::_current_jni_active_count = 0;
140
141 WaitBarrier* SafepointSynchronize::_wait_barrier;
142
143 static bool timeout_error_printed = false;
144
145 // Statistic related
146 static jlong _safepoint_begin_time = 0;
147 static volatile int _nof_threads_hit_polling_page = 0;
148
149 void SafepointSynchronize::init(Thread* vmthread) {
150 // WaitBarrier should never be destroyed since we will have
151 // threads waiting on it while exiting.
152 _wait_barrier = new WaitBarrier(vmthread);
153 SafepointTracing::init();
154 }
155
156 void SafepointSynchronize::increment_jni_active_count() {
157 assert(Thread::current()->is_VM_thread(), "Only VM thread may increment");
158 ++_current_jni_active_count;
159 }
160
161 void SafepointSynchronize::decrement_waiting_to_block() {
162 assert(_waiting_to_block > 0, "sanity check");
163 assert(Thread::current()->is_VM_thread(), "Only VM thread may decrement");
164 --_waiting_to_block;
165 }
166
167 bool SafepointSynchronize::thread_not_running(ThreadSafepointState *cur_state) {
168 if (!cur_state->is_running()) {
169 return true;
170 }
171 cur_state->examine_state_of_thread(SafepointSynchronize::safepoint_counter());
172 if (!cur_state->is_running()) {
173 return true;
174 }
175 LogTarget(Trace, safepoint) lt;
176 if (lt.is_enabled()) {
177 ResourceMark rm;
178 LogStream ls(lt);
179 cur_state->print_on(&ls);
180 }
181 return false;
182 }
183
184 #ifdef ASSERT
185 static void assert_list_is_valid(const ThreadSafepointState* tss_head, int still_running) {
186 int a = 0;
187 const ThreadSafepointState *tmp_tss = tss_head;
188 while (tmp_tss != NULL) {
189 ++a;
190 assert(tmp_tss->is_running(), "Illegal initial state");
191 tmp_tss = tmp_tss->get_next();
192 }
193 assert(a == still_running, "Must be the same");
194 }
195 #endif // ASSERT
196
197 static void back_off(int64_t start_time) {
198 // We start with fine-grained nanosleeping until a millisecond has
199 // passed, at which point we resort to plain naked_short_sleep.
200 if (os::javaTimeNanos() - start_time < NANOSECS_PER_MILLISEC) {
201 os::naked_short_nanosleep(10 * (NANOUNITS / MICROUNITS));
202 } else {
203 os::naked_short_sleep(1);
204 }
205 }
206
207 int SafepointSynchronize::synchronize_threads(jlong safepoint_limit_time, int nof_threads, int* initial_running)
208 {
209 JavaThreadIteratorWithHandle jtiwh;
210
211 #ifdef ASSERT
212 for (; JavaThread *cur = jtiwh.next(); ) {
213 assert(cur->safepoint_state()->is_running(), "Illegal initial state");
214 }
215 jtiwh.rewind();
216 #endif // ASSERT
217
218 // Iterate through all threads until it has been determined how to stop them all at a safepoint.
219 int still_running = nof_threads;
220 ThreadSafepointState *tss_head = NULL;
221 ThreadSafepointState **p_prev = &tss_head;
222 for (; JavaThread *cur = jtiwh.next(); ) {
223 ThreadSafepointState *cur_tss = cur->safepoint_state();
224 assert(cur_tss->get_next() == NULL, "Must be NULL");
225 if (thread_not_running(cur_tss)) {
226 --still_running;
227 } else {
228 *p_prev = cur_tss;
229 p_prev = cur_tss->next_ptr();
230 }
231 }
232 *p_prev = NULL;
233
234 DEBUG_ONLY(assert_list_is_valid(tss_head, still_running);)
235
236 *initial_running = still_running;
237
238 // If there is no thread still running, we are already done.
239 if (still_running <= 0) {
240 assert(tss_head == NULL, "Must be empty");
241 return 1;
242 }
243
244 int iterations = 1; // The first iteration is above.
245 int64_t start_time = os::javaTimeNanos();
246
247 do {
248 // Check if this has taken too long:
249 if (SafepointTimeout && safepoint_limit_time < os::javaTimeNanos()) {
250 print_safepoint_timeout();
251 }
252
253 p_prev = &tss_head;
254 ThreadSafepointState *cur_tss = tss_head;
255 while (cur_tss != NULL) {
256 assert(cur_tss->is_running(), "Illegal initial state");
257 if (thread_not_running(cur_tss)) {
258 --still_running;
259 *p_prev = NULL;
260 ThreadSafepointState *tmp = cur_tss;
261 cur_tss = cur_tss->get_next();
262 tmp->set_next(NULL);
263 } else {
264 *p_prev = cur_tss;
265 p_prev = cur_tss->next_ptr();
266 cur_tss = cur_tss->get_next();
267 }
268 }
269
270 DEBUG_ONLY(assert_list_is_valid(tss_head, still_running);)
271
272 if (still_running > 0) {
273 back_off(start_time);
274 }
275
276 iterations++;
277 } while (still_running > 0);
278
279 assert(tss_head == NULL, "Must be empty");
280
281 return iterations;
282 }
283
284 void SafepointSynchronize::arm_safepoint() {
285 // Begin the process of bringing the system to a safepoint.
286 // Java threads can be in several different states and are
287 // stopped by different mechanisms:
288 //
289 // 1. Running interpreted
290 // When executing branching/returning byte codes interpreter
291 // checks if the poll is armed, if so blocks in SS::block().
292 // 2. Running in native code
293 // When returning from the native code, a Java thread must check
294 // the safepoint _state to see if we must block. If the
295 // VM thread sees a Java thread in native, it does
296 // not wait for this thread to block. The order of the memory
297 // writes and reads of both the safepoint state and the Java
298 // threads state is critical. In order to guarantee that the
299 // memory writes are serialized with respect to each other,
300 // the VM thread issues a memory barrier instruction.
301 // 3. Running compiled Code
302 // Compiled code reads the local polling page that
303 // is set to fault if we are trying to get to a safepoint.
304 // 4. Blocked
305 // A thread which is blocked will not be allowed to return from the
306 // block condition until the safepoint operation is complete.
307 // 5. In VM or Transitioning between states
308 // If a Java thread is currently running in the VM or transitioning
309 // between states, the safepointing code will poll the thread state
310 // until the thread blocks itself when it attempts transitions to a
311 // new state or locking a safepoint checked monitor.
312
313 // We must never miss a thread with correct safepoint id, so we must make sure we arm
314 // the wait barrier for the next safepoint id/counter.
315 // Arming must be done after resetting _current_jni_active_count, _waiting_to_block.
316 _wait_barrier->arm(static_cast<int>(_safepoint_counter + 1));
317
318 assert((_safepoint_counter & 0x1) == 0, "must be even");
319 // The store to _safepoint_counter must happen after any stores in arming.
320 Atomic::release_store(&_safepoint_counter, _safepoint_counter + 1);
321
322 // We are synchronizing
323 OrderAccess::storestore(); // Ordered with _safepoint_counter
324 _state = _synchronizing;
325
326 // Arming the per thread poll while having _state != _not_synchronized means safepointing
327 log_trace(safepoint)("Setting thread local yield flag for threads");
328 OrderAccess::storestore(); // storestore, global state -> local state
329 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *cur = jtiwh.next(); ) {
330 // Make sure the threads start polling, it is time to yield.
331 SafepointMechanism::arm_local_poll(cur);
332 }
333
334 OrderAccess::fence(); // storestore|storeload, global state -> local state
335 }
336
337 // Roll all threads forward to a safepoint and suspend them all
338 void SafepointSynchronize::begin() {
339 assert(Thread::current()->is_VM_thread(), "Only VM thread may execute a safepoint");
340
341 EventSafepointBegin begin_event;
342 SafepointTracing::begin(VMThread::vm_op_type());
343
344 Universe::heap()->safepoint_synchronize_begin();
345
346 // By getting the Threads_lock, we assure that no threads are about to start or
347 // exit. It is released again in SafepointSynchronize::end().
348 Threads_lock->lock();
349
350 assert( _state == _not_synchronized, "trying to safepoint synchronize with wrong state");
351
352 int nof_threads = Threads::number_of_threads();
353
354 _nof_threads_hit_polling_page = 0;
355
356 log_debug(safepoint)("Safepoint synchronization initiated using %s wait barrier. (%d threads)", _wait_barrier->description(), nof_threads);
357
358 // Reset the count of active JNI critical threads
359 _current_jni_active_count = 0;
360
361 // Set number of threads to wait for
362 _waiting_to_block = nof_threads;
363
364 jlong safepoint_limit_time = 0;
365 if (SafepointTimeout) {
366 // Set the limit time, so that it can be compared to see if this has taken
367 // too long to complete.
368 safepoint_limit_time = SafepointTracing::start_of_safepoint() + (jlong)SafepointTimeoutDelay * (NANOUNITS / MILLIUNITS);
369 timeout_error_printed = false;
370 }
371
372 EventSafepointStateSynchronization sync_event;
373 int initial_running = 0;
374
375 // Arms the safepoint, _current_jni_active_count and _waiting_to_block must be set before.
376 arm_safepoint();
377
378 // Will spin until all threads are safe.
379 int iterations = synchronize_threads(safepoint_limit_time, nof_threads, &initial_running);
380 assert(_waiting_to_block == 0, "No thread should be running");
381
382 #ifndef PRODUCT
383 if (safepoint_limit_time != 0) {
384 jlong current_time = os::javaTimeNanos();
385 if (safepoint_limit_time < current_time) {
386 log_warning(safepoint)("# SafepointSynchronize: Finished after "
387 INT64_FORMAT_W(6) " ms",
388 (int64_t)(current_time - SafepointTracing::start_of_safepoint()) / (NANOUNITS / MILLIUNITS));
389 }
390 }
391 #endif
392
393 assert(Threads_lock->owned_by_self(), "must hold Threads_lock");
394
395 // Record state
396 _state = _synchronized;
397
398 OrderAccess::fence();
399
400 // Set the new id
401 ++_safepoint_id;
402
403 #ifdef ASSERT
404 // Make sure all the threads were visited.
405 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *cur = jtiwh.next(); ) {
406 assert(cur->was_visited_for_critical_count(_safepoint_counter), "missed a thread");
407 }
408 #endif // ASSERT
409
410 // Update the count of active JNI critical regions
411 GCLocker::set_jni_lock_count(_current_jni_active_count);
412
413 post_safepoint_synchronize_event(sync_event,
414 _safepoint_id,
415 initial_running,
416 _waiting_to_block, iterations);
417
418 SafepointTracing::synchronized(nof_threads, initial_running, _nof_threads_hit_polling_page);
419
420 // We do the safepoint cleanup first since a GC related safepoint
421 // needs cleanup to be completed before running the GC op.
422 EventSafepointCleanup cleanup_event;
423 do_cleanup_tasks();
424 post_safepoint_cleanup_event(cleanup_event, _safepoint_id);
425
426 post_safepoint_begin_event(begin_event, _safepoint_id, nof_threads, _current_jni_active_count);
427 SafepointTracing::cleanup();
428 }
429
430 void SafepointSynchronize::disarm_safepoint() {
431 uint64_t active_safepoint_counter = _safepoint_counter;
432 {
433 JavaThreadIteratorWithHandle jtiwh;
434 #ifdef ASSERT
435 // A pending_exception cannot be installed during a safepoint. The threads
436 // may install an async exception after they come back from a safepoint into
437 // pending_exception after they unblock. But that should happen later.
438 for (; JavaThread *cur = jtiwh.next(); ) {
439 assert (!(cur->has_pending_exception() &&
440 cur->safepoint_state()->is_at_poll_safepoint()),
441 "safepoint installed a pending exception");
442 }
443 #endif // ASSERT
444
445 OrderAccess::fence(); // keep read and write of _state from floating up
446 assert(_state == _synchronized, "must be synchronized before ending safepoint synchronization");
447
448 // Change state first to _not_synchronized.
449 // No threads should see _synchronized when running.
450 _state = _not_synchronized;
451
452 // Set the next dormant (even) safepoint id.
453 assert((_safepoint_counter & 0x1) == 1, "must be odd");
454 Atomic::release_store(&_safepoint_counter, _safepoint_counter + 1);
455
456 OrderAccess::fence(); // Keep the local state from floating up.
457
458 jtiwh.rewind();
459 for (; JavaThread *current = jtiwh.next(); ) {
460 // Clear the visited flag to ensure that the critical counts are collected properly.
461 DEBUG_ONLY(current->reset_visited_for_critical_count(active_safepoint_counter);)
462 ThreadSafepointState* cur_state = current->safepoint_state();
463 assert(!cur_state->is_running(), "Thread not suspended at safepoint");
464 cur_state->restart(); // TSS _running
465 assert(cur_state->is_running(), "safepoint state has not been reset");
466 }
467 } // ~JavaThreadIteratorWithHandle
468
469 // Release threads lock, so threads can be created/destroyed again.
470 Threads_lock->unlock();
471
472 // Wake threads after local state is correctly set.
473 _wait_barrier->disarm();
474 }
475
476 // Wake up all threads, so they are ready to resume execution after the safepoint
477 // operation has been carried out
478 void SafepointSynchronize::end() {
479 assert(Threads_lock->owned_by_self(), "must hold Threads_lock");
480 EventSafepointEnd event;
481 assert(Thread::current()->is_VM_thread(), "Only VM thread can execute a safepoint");
482
483 disarm_safepoint();
484
485 Universe::heap()->safepoint_synchronize_end();
486
487 SafepointTracing::end();
488
489 post_safepoint_end_event(event, safepoint_id());
490 }
491
492 bool SafepointSynchronize::is_cleanup_needed() {
493 // Need a safepoint if there are many monitors to deflate.
494 if (ObjectSynchronizer::is_cleanup_needed()) return true;
495 // Need a safepoint if some inline cache buffers is non-empty
496 if (!InlineCacheBuffer::is_empty()) return true;
497 if (StringTable::needs_rehashing()) return true;
498 if (SymbolTable::needs_rehashing()) return true;
499 return false;
500 }
501
502 class ParallelSPCleanupThreadClosure : public ThreadClosure {
503 private:
504 CodeBlobClosure* _nmethod_cl;
505 DeflateMonitorCounters* _counters;
506
507 public:
508 ParallelSPCleanupThreadClosure(DeflateMonitorCounters* counters) :
509 _nmethod_cl(UseCodeAging ? NMethodSweeper::prepare_reset_hotness_counters() : NULL),
510 _counters(counters) {}
511
512 void do_thread(Thread* thread) {
513 ObjectSynchronizer::deflate_thread_local_monitors(thread, _counters);
514 if (_nmethod_cl != NULL && thread->is_Java_thread() &&
515 ! thread->is_Code_cache_sweeper_thread()) {
516 JavaThread* jt = (JavaThread*) thread;
517 jt->nmethods_do(_nmethod_cl);
518 }
519 }
520 };
521
522 class ParallelSPCleanupTask : public AbstractGangTask {
523 private:
524 SubTasksDone _subtasks;
525 ParallelSPCleanupThreadClosure _cleanup_threads_cl;
526 uint _num_workers;
527 DeflateMonitorCounters* _counters;
528 public:
529 ParallelSPCleanupTask(uint num_workers, DeflateMonitorCounters* counters) :
530 AbstractGangTask("Parallel Safepoint Cleanup"),
531 _subtasks(SafepointSynchronize::SAFEPOINT_CLEANUP_NUM_TASKS),
532 _cleanup_threads_cl(ParallelSPCleanupThreadClosure(counters)),
533 _num_workers(num_workers),
534 _counters(counters) {}
535
536 void work(uint worker_id) {
537 uint64_t safepoint_id = SafepointSynchronize::safepoint_id();
538 // All threads deflate monitors and mark nmethods (if necessary).
539 Threads::possibly_parallel_threads_do(true, &_cleanup_threads_cl);
540
541 if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_DEFLATE_MONITORS)) {
542 const char* name = "deflating global idle monitors";
543 EventSafepointCleanupTask event;
544 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
545 ObjectSynchronizer::deflate_idle_monitors(_counters);
546
547 post_safepoint_cleanup_task_event(event, safepoint_id, name);
548 }
549
550 if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_UPDATE_INLINE_CACHES)) {
551 const char* name = "updating inline caches";
552 EventSafepointCleanupTask event;
553 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
554 InlineCacheBuffer::update_inline_caches();
555
556 post_safepoint_cleanup_task_event(event, safepoint_id, name);
557 }
558
559 if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_COMPILATION_POLICY)) {
560 const char* name = "compilation policy safepoint handler";
561 EventSafepointCleanupTask event;
562 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
563 CompilationPolicy::policy()->do_safepoint_work();
564
565 post_safepoint_cleanup_task_event(event, safepoint_id, name);
566 }
567
568 if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_SYMBOL_TABLE_REHASH)) {
569 if (SymbolTable::needs_rehashing()) {
570 const char* name = "rehashing symbol table";
571 EventSafepointCleanupTask event;
572 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
573 SymbolTable::rehash_table();
574
575 post_safepoint_cleanup_task_event(event, safepoint_id, name);
576 }
577 }
578
579 if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_STRING_TABLE_REHASH)) {
580 if (StringTable::needs_rehashing()) {
581 const char* name = "rehashing string table";
582 EventSafepointCleanupTask event;
583 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
584 StringTable::rehash_table();
585
586 post_safepoint_cleanup_task_event(event, safepoint_id, name);
587 }
588 }
589
590 if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_SYSTEM_DICTIONARY_RESIZE)) {
591 if (Dictionary::does_any_dictionary_needs_resizing()) {
592 const char* name = "resizing system dictionaries";
593 EventSafepointCleanupTask event;
594 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
595 ClassLoaderDataGraph::resize_dictionaries();
596
597 post_safepoint_cleanup_task_event(event, safepoint_id, name);
598 }
599 }
600
601 if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_REQUEST_OOPSTORAGE_CLEANUP)) {
602 // Don't bother reporting event or time for this very short operation.
603 // To have any utility we'd also want to report whether needed.
604 OopStorage::trigger_cleanup_if_needed();
605 }
606
607 _subtasks.all_tasks_completed(_num_workers);
608 }
609 };
610
611 // Various cleaning tasks that should be done periodically at safepoints.
612 void SafepointSynchronize::do_cleanup_tasks() {
613
614 TraceTime timer("safepoint cleanup tasks", TRACETIME_LOG(Info, safepoint, cleanup));
615
616 // Prepare for monitor deflation.
617 DeflateMonitorCounters deflate_counters;
618 ObjectSynchronizer::prepare_deflate_idle_monitors(&deflate_counters);
619
620 CollectedHeap* heap = Universe::heap();
621 assert(heap != NULL, "heap not initialized yet?");
622 WorkGang* cleanup_workers = heap->get_safepoint_workers();
623 if (cleanup_workers != NULL) {
624 // Parallel cleanup using GC provided thread pool.
625 uint num_cleanup_workers = cleanup_workers->active_workers();
626 ParallelSPCleanupTask cleanup(num_cleanup_workers, &deflate_counters);
627 StrongRootsScope srs(num_cleanup_workers);
628 cleanup_workers->run_task(&cleanup);
629 } else {
630 // Serial cleanup using VMThread.
631 ParallelSPCleanupTask cleanup(1, &deflate_counters);
632 StrongRootsScope srs(1);
633 cleanup.work(0);
634 }
635
636 // Needs to be done single threaded by the VMThread. This walks
637 // the thread stacks looking for references to metadata before
638 // deciding to remove it from the metaspaces.
639 if (ClassLoaderDataGraph::should_clean_metaspaces_and_reset()) {
640 const char* name = "cleanup live ClassLoaderData metaspaces";
641 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
642 ClassLoaderDataGraph::walk_metadata_and_clean_metaspaces();
643 }
644
645 // Finish monitor deflation.
646 ObjectSynchronizer::finish_deflate_idle_monitors(&deflate_counters);
647
648 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
649 }
650
651 // Methods for determining if a JavaThread is safepoint safe.
652
653 // False means unsafe with undetermined state.
654 // True means a determined state, but it may be an unsafe state.
655 // If called from a non-safepoint context safepoint_count MUST be InactiveSafepointCounter.
656 bool SafepointSynchronize::try_stable_load_state(JavaThreadState *state, JavaThread *thread, uint64_t safepoint_count) {
657 assert((safepoint_count != InactiveSafepointCounter &&
658 Thread::current() == (Thread*)VMThread::vm_thread() &&
659 SafepointSynchronize::_state != _not_synchronized)
660 || safepoint_count == InactiveSafepointCounter, "Invalid check");
661
662 // To handle the thread_blocked state on the backedge of the WaitBarrier from
663 // previous safepoint and reading the reset value (0/InactiveSafepointCounter) we
664 // re-read state after we read thread safepoint id. The JavaThread changes its
665 // thread state from thread_blocked before resetting safepoint id to 0.
666 // This guarantees the second read will be from an updated thread state. It can
667 // either be different state making this an unsafe state or it can see blocked
668 // again. When we see blocked twice with a 0 safepoint id, either:
669 // - It is normally blocked, e.g. on Mutex, TBIVM.
670 // - It was in SS:block(), looped around to SS:block() and is blocked on the WaitBarrier.
671 // - It was in SS:block() but now on a Mutex.
672 // All of these cases are safe.
673
674 *state = thread->thread_state();
675 OrderAccess::loadload();
676 uint64_t sid = thread->safepoint_state()->get_safepoint_id(); // Load acquire
677 if (sid != InactiveSafepointCounter && sid != safepoint_count) {
678 // In an old safepoint, state not relevant.
679 return false;
680 }
681 return *state == thread->thread_state();
682 }
683
684 static bool safepoint_safe_with(JavaThread *thread, JavaThreadState state) {
685 switch(state) {
686 case _thread_in_native:
687 // native threads are safe if they have no java stack or have walkable stack
688 return !thread->has_last_Java_frame() || thread->frame_anchor()->walkable();
689
690 case _thread_blocked:
691 // On wait_barrier or blocked.
692 // Blocked threads should already have walkable stack.
693 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "blocked and not walkable");
694 return true;
695
696 default:
697 return false;
698 }
699 }
700
701 bool SafepointSynchronize::handshake_safe(JavaThread *thread) {
702 if (thread->is_ext_suspended() || thread->is_terminated()) {
703 return true;
704 }
705 JavaThreadState stable_state;
706 if (try_stable_load_state(&stable_state, thread, InactiveSafepointCounter)) {
707 return safepoint_safe_with(thread, stable_state);
708 }
709 return false;
710 }
711
712 // See if the thread is running inside a lazy critical native and
713 // update the thread critical count if so. Also set a suspend flag to
714 // cause the native wrapper to return into the JVM to do the unlock
715 // once the native finishes.
716 static void check_for_lazy_critical_native(JavaThread *thread, JavaThreadState state) {
717 if (state == _thread_in_native &&
718 thread->has_last_Java_frame() &&
719 thread->frame_anchor()->walkable()) {
720 // This thread might be in a critical native nmethod so look at
721 // the top of the stack and increment the critical count if it
722 // is.
723 frame wrapper_frame = thread->last_frame();
724 CodeBlob* stub_cb = wrapper_frame.cb();
725 if (stub_cb != NULL &&
726 stub_cb->is_nmethod() &&
727 stub_cb->as_nmethod_or_null()->is_lazy_critical_native()) {
728 // A thread could potentially be in a critical native across
729 // more than one safepoint, so only update the critical state on
730 // the first one. When it returns it will perform the unlock.
731 if (!thread->do_critical_native_unlock()) {
732 #ifdef ASSERT
733 if (!thread->in_critical()) {
734 GCLocker::increment_debug_jni_lock_count();
735 }
736 #endif
737 thread->enter_critical();
738 // Make sure the native wrapper calls back on return to
739 // perform the needed critical unlock.
740 thread->set_critical_native_unlock();
741 }
742 }
743 }
744 }
745
746 // -------------------------------------------------------------------------------------------------------
747 // Implementation of Safepoint blocking point
748
749 void SafepointSynchronize::block(JavaThread *thread) {
750 assert(thread != NULL, "thread must be set");
751 assert(thread->is_Java_thread(), "not a Java thread");
752
753 // Threads shouldn't block if they are in the middle of printing, but...
754 ttyLocker::break_tty_lock_for_safepoint(os::current_thread_id());
755
756 // Only bail from the block() call if the thread is gone from the
757 // thread list; starting to exit should still block.
758 if (thread->is_terminated()) {
759 // block current thread if we come here from native code when VM is gone
760 thread->block_if_vm_exited();
761
762 // otherwise do nothing
763 return;
764 }
765
766 JavaThreadState state = thread->thread_state();
767 thread->frame_anchor()->make_walkable(thread);
768
769 uint64_t safepoint_id = SafepointSynchronize::safepoint_counter();
770 // Check that we have a valid thread_state at this point
771 switch(state) {
772 case _thread_in_vm_trans:
773 case _thread_in_Java: // From compiled code
774 case _thread_in_native_trans:
775 case _thread_blocked_trans:
776 case _thread_new_trans:
777
778 // We have no idea where the VMThread is, it might even be at next safepoint.
779 // So we can miss this poll, but stop at next.
780
781 // Load dependent store, it must not pass loading of safepoint_id.
782 thread->safepoint_state()->set_safepoint_id(safepoint_id); // Release store
783
784 // This part we can skip if we notice we miss or are in a future safepoint.
785 OrderAccess::storestore();
786 // Load in wait barrier should not float up
787 thread->set_thread_state_fence(_thread_blocked);
788
789 _wait_barrier->wait(static_cast<int>(safepoint_id));
790 assert(_state != _synchronized, "Can't be");
791
792 // If barrier is disarmed stop store from floating above loads in barrier.
793 OrderAccess::loadstore();
794 thread->set_thread_state(state);
795
796 // Then we reset the safepoint id to inactive.
797 thread->safepoint_state()->reset_safepoint_id(); // Release store
798
799 OrderAccess::fence();
800
801 break;
802
803 default:
804 fatal("Illegal threadstate encountered: %d", state);
805 }
806 guarantee(thread->safepoint_state()->get_safepoint_id() == InactiveSafepointCounter,
807 "The safepoint id should be set only in block path");
808
809 // Check for pending. async. exceptions or suspends - except if the
810 // thread was blocked inside the VM. has_special_runtime_exit_condition()
811 // is called last since it grabs a lock and we only want to do that when
812 // we must.
813 //
814 // Note: we never deliver an async exception at a polling point as the
815 // compiler may not have an exception handler for it. The polling
816 // code will notice the async and deoptimize and the exception will
817 // be delivered. (Polling at a return point is ok though). Sure is
818 // a lot of bother for a deprecated feature...
819 //
820 // We don't deliver an async exception if the thread state is
821 // _thread_in_native_trans so JNI functions won't be called with
822 // a surprising pending exception. If the thread state is going back to java,
823 // async exception is checked in check_special_condition_for_native_trans().
824
825 if (state != _thread_blocked_trans &&
826 state != _thread_in_vm_trans &&
827 thread->has_special_runtime_exit_condition()) {
828 thread->handle_special_runtime_exit_condition(
829 !thread->is_at_poll_safepoint() && (state != _thread_in_native_trans));
830 }
831
832 // cross_modify_fence is done by SafepointMechanism::block_if_requested_slow
833 // which is the only caller here.
834 }
835
836 // ------------------------------------------------------------------------------------------------------
837 // Exception handlers
838
839
840 void SafepointSynchronize::handle_polling_page_exception(JavaThread *thread) {
841 assert(thread->is_Java_thread(), "polling reference encountered by VM thread");
842 assert(thread->thread_state() == _thread_in_Java, "should come from Java code");
843
844 if (log_is_enabled(Info, safepoint, stats)) {
845 Atomic::inc(&_nof_threads_hit_polling_page);
846 }
847
848 ThreadSafepointState* state = thread->safepoint_state();
849
850 state->handle_polling_page_exception();
851 }
852
853
854 void SafepointSynchronize::print_safepoint_timeout() {
855 if (!timeout_error_printed) {
856 timeout_error_printed = true;
857 // Print out the thread info which didn't reach the safepoint for debugging
858 // purposes (useful when there are lots of threads in the debugger).
859 LogTarget(Warning, safepoint) lt;
860 if (lt.is_enabled()) {
861 ResourceMark rm;
862 LogStream ls(lt);
863
864 ls.cr();
865 ls.print_cr("# SafepointSynchronize::begin: Timeout detected:");
866 ls.print_cr("# SafepointSynchronize::begin: Timed out while spinning to reach a safepoint.");
867 ls.print_cr("# SafepointSynchronize::begin: Threads which did not reach the safepoint:");
868 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *cur_thread = jtiwh.next(); ) {
869 if (cur_thread->safepoint_state()->is_running()) {
870 ls.print("# ");
871 cur_thread->print_on(&ls);
872 ls.cr();
873 }
874 }
875 ls.print_cr("# SafepointSynchronize::begin: (End of list)");
876 }
877 }
878
879 // To debug the long safepoint, specify both AbortVMOnSafepointTimeout &
880 // ShowMessageBoxOnError.
881 if (AbortVMOnSafepointTimeout) {
882 // Send the blocking thread a signal to terminate and write an error file.
883 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *cur_thread = jtiwh.next(); ) {
884 if (cur_thread->safepoint_state()->is_running()) {
885 if (!os::signal_thread(cur_thread, SIGILL, "blocking a safepoint")) {
886 break; // Could not send signal. Report fatal error.
887 }
888 // Give cur_thread a chance to report the error and terminate the VM.
889 os::naked_sleep(3000);
890 }
891 }
892 fatal("Safepoint sync time longer than " INTX_FORMAT "ms detected when executing %s.",
893 SafepointTimeoutDelay, VMThread::vm_operation()->name());
894 }
895 }
896
897 // -------------------------------------------------------------------------------------------------------
898 // Implementation of ThreadSafepointState
899
900 ThreadSafepointState::ThreadSafepointState(JavaThread *thread)
901 : _at_poll_safepoint(false), _thread(thread), _safepoint_safe(false),
902 _safepoint_id(SafepointSynchronize::InactiveSafepointCounter), _next(NULL) {
903 }
904
905 void ThreadSafepointState::create(JavaThread *thread) {
906 ThreadSafepointState *state = new ThreadSafepointState(thread);
907 thread->set_safepoint_state(state);
908 }
909
910 void ThreadSafepointState::destroy(JavaThread *thread) {
911 if (thread->safepoint_state()) {
912 delete(thread->safepoint_state());
913 thread->set_safepoint_state(NULL);
914 }
915 }
916
917 uint64_t ThreadSafepointState::get_safepoint_id() const {
918 return Atomic::load_acquire(&_safepoint_id);
919 }
920
921 void ThreadSafepointState::reset_safepoint_id() {
922 Atomic::release_store(&_safepoint_id, SafepointSynchronize::InactiveSafepointCounter);
923 }
924
925 void ThreadSafepointState::set_safepoint_id(uint64_t safepoint_id) {
926 Atomic::release_store(&_safepoint_id, safepoint_id);
927 }
928
929 void ThreadSafepointState::examine_state_of_thread(uint64_t safepoint_count) {
930 assert(is_running(), "better be running or just have hit safepoint poll");
931
932 JavaThreadState stable_state;
933 if (!SafepointSynchronize::try_stable_load_state(&stable_state, _thread, safepoint_count)) {
934 // We could not get stable state of the JavaThread.
935 // Consider it running and just return.
936 return;
937 }
938
939 // Check for a thread that is suspended. Note that thread resume tries
940 // to grab the Threads_lock which we own here, so a thread cannot be
941 // resumed during safepoint synchronization.
942
943 // We check to see if this thread is suspended without locking to
944 // avoid deadlocking with a third thread that is waiting for this
945 // thread to be suspended. The third thread can notice the safepoint
946 // that we're trying to start at the beginning of its SR_lock->wait()
947 // call. If that happens, then the third thread will block on the
948 // safepoint while still holding the underlying SR_lock. We won't be
949 // able to get the SR_lock and we'll deadlock.
950 //
951 // We don't need to grab the SR_lock here for two reasons:
952 // 1) The suspend flags are both volatile and are set with an
953 // Atomic::cmpxchg() call so we should see the suspended
954 // state right away.
955 // 2) We're being called from the safepoint polling loop; if
956 // we don't see the suspended state on this iteration, then
957 // we'll come around again.
958 //
959 bool is_suspended = _thread->is_ext_suspended();
960 if (is_suspended) {
961 account_safe_thread();
962 return;
963 }
964
965 if (safepoint_safe_with(_thread, stable_state)) {
966 check_for_lazy_critical_native(_thread, stable_state);
967 account_safe_thread();
968 return;
969 }
970
971 // All other thread states will continue to run until they
972 // transition and self-block in state _blocked
973 // Safepoint polling in compiled code causes the Java threads to do the same.
974 // Note: new threads may require a malloc so they must be allowed to finish
975
976 assert(is_running(), "examine_state_of_thread on non-running thread");
977 return;
978 }
979
980 void ThreadSafepointState::account_safe_thread() {
981 SafepointSynchronize::decrement_waiting_to_block();
982 if (_thread->in_critical()) {
983 // Notice that this thread is in a critical section
984 SafepointSynchronize::increment_jni_active_count();
985 }
986 DEBUG_ONLY(_thread->set_visited_for_critical_count(SafepointSynchronize::safepoint_counter());)
987 assert(!_safepoint_safe, "Must be unsafe before safe");
988 _safepoint_safe = true;
989 }
990
991 void ThreadSafepointState::restart() {
992 assert(_safepoint_safe, "Must be safe before unsafe");
993 _safepoint_safe = false;
994 }
995
996 void ThreadSafepointState::print_on(outputStream *st) const {
997 const char *s = _safepoint_safe ? "_at_safepoint" : "_running";
998
999 st->print_cr("Thread: " INTPTR_FORMAT
1000 " [0x%2x] State: %s _at_poll_safepoint %d",
1001 p2i(_thread), _thread->osthread()->thread_id(), s, _at_poll_safepoint);
1002
1003 _thread->print_thread_state_on(st);
1004 }
1005
1006 // ---------------------------------------------------------------------------------------------------------------------
1007
1008 // Block the thread at poll or poll return for safepoint/handshake.
1009 void ThreadSafepointState::handle_polling_page_exception() {
1010
1011 // Step 1: Find the nmethod from the return address
1012 address real_return_addr = thread()->saved_exception_pc();
1013
1014 CodeBlob *cb = CodeCache::find_blob(real_return_addr);
1015 assert(cb != NULL && cb->is_compiled(), "return address should be in nmethod");
1016 CompiledMethod* nm = (CompiledMethod*)cb;
1017
1018 // Find frame of caller
1019 frame stub_fr = thread()->last_frame();
1020 CodeBlob* stub_cb = stub_fr.cb();
1021 assert(stub_cb->is_safepoint_stub(), "must be a safepoint stub");
1022 RegisterMap map(thread(), true);
1023 frame caller_fr = stub_fr.sender(&map);
1024
1025 // Should only be poll_return or poll
1026 assert( nm->is_at_poll_or_poll_return(real_return_addr), "should not be at call" );
1027
1028 // This is a poll immediately before a return. The exception handling code
1029 // has already had the effect of causing the return to occur, so the execution
1030 // will continue immediately after the call. In addition, the oopmap at the
1031 // return point does not mark the return value as an oop (if it is), so
1032 // it needs a handle here to be updated.
1033 if( nm->is_at_poll_return(real_return_addr) ) {
1034 // See if return type is an oop.
1035 bool return_oop = nm->method()->is_returning_oop();
1036 Handle return_value;
1037 if (return_oop) {
1038 // The oop result has been saved on the stack together with all
1039 // the other registers. In order to preserve it over GCs we need
1040 // to keep it in a handle.
1041 oop result = caller_fr.saved_oop_result(&map);
1042 assert(oopDesc::is_oop_or_null(result), "must be oop");
1043 return_value = Handle(thread(), result);
1044 assert(Universe::heap()->is_in_or_null(result), "must be heap pointer");
1045 }
1046
1047 // Block the thread
1048 SafepointMechanism::block_if_requested(thread());
1049
1050 // restore oop result, if any
1051 if (return_oop) {
1052 caller_fr.set_saved_oop_result(&map, return_value());
1053 }
1054 }
1055
1056 // This is a safepoint poll. Verify the return address and block.
1057 else {
1058 set_at_poll_safepoint(true);
1059
1060 // verify the blob built the "return address" correctly
1061 assert(real_return_addr == caller_fr.pc(), "must match");
1062
1063 // Block the thread
1064 SafepointMechanism::block_if_requested(thread());
1065 set_at_poll_safepoint(false);
1066
1067 // If we have a pending async exception deoptimize the frame
1068 // as otherwise we may never deliver it.
1069 if (thread()->has_async_condition()) {
1070 ThreadInVMfromJavaNoAsyncException __tiv(thread());
1071 Deoptimization::deoptimize_frame(thread(), caller_fr.id());
1072 }
1073
1074 // If an exception has been installed we must check for a pending deoptimization
1075 // Deoptimize frame if exception has been thrown.
1076
1077 if (thread()->has_pending_exception() ) {
1078 RegisterMap map(thread(), true);
1079 frame caller_fr = stub_fr.sender(&map);
1080 if (caller_fr.is_deoptimized_frame()) {
1081 // The exception patch will destroy registers that are still
1082 // live and will be needed during deoptimization. Defer the
1083 // Async exception should have deferred the exception until the
1084 // next safepoint which will be detected when we get into
1085 // the interpreter so if we have an exception now things
1086 // are messed up.
1087
1088 fatal("Exception installed and deoptimization is pending");
1089 }
1090 }
1091 }
1092 }
1093
1094
1095 // -------------------------------------------------------------------------------------------------------
1096 // Implementation of SafepointTracing
1097
1098 jlong SafepointTracing::_last_safepoint_begin_time_ns = 0;
1099 jlong SafepointTracing::_last_safepoint_sync_time_ns = 0;
1100 jlong SafepointTracing::_last_safepoint_cleanup_time_ns = 0;
1101 jlong SafepointTracing::_last_safepoint_end_time_ns = 0;
1102 jlong SafepointTracing::_last_app_time_ns = 0;
1103 int SafepointTracing::_nof_threads = 0;
1104 int SafepointTracing::_nof_running = 0;
1105 int SafepointTracing::_page_trap = 0;
1106 VM_Operation::VMOp_Type SafepointTracing::_current_type;
1107 jlong SafepointTracing::_max_sync_time = 0;
1108 jlong SafepointTracing::_max_vmop_time = 0;
1109 uint64_t SafepointTracing::_op_count[VM_Operation::VMOp_Terminating] = {0};
1110
1111 void SafepointTracing::init() {
1112 // Application start
1113 _last_safepoint_end_time_ns = os::javaTimeNanos();
1114 }
1115
1116 // Helper method to print the header.
1117 static void print_header(outputStream* st) {
1118 // The number of spaces is significant here, and should match the format
1119 // specifiers in print_statistics().
1120
1121 st->print("VM Operation "
1122 "[ threads: total initial_running ]"
1123 "[ time: sync cleanup vmop total ]");
1124
1125 st->print_cr(" page_trap_count");
1126 }
1127
1128 // This prints a nice table. To get the statistics to not shift due to the logging uptime
1129 // decorator, use the option as: -Xlog:safepoint+stats:[outputfile]:none
1130 void SafepointTracing::statistics_log() {
1131 LogTarget(Info, safepoint, stats) lt;
1132 assert (lt.is_enabled(), "should only be called when printing statistics is enabled");
1133 LogStream ls(lt);
1134
1135 static int _cur_stat_index = 0;
1136
1137 // Print header every 30 entries
1138 if ((_cur_stat_index % 30) == 0) {
1139 print_header(&ls);
1140 _cur_stat_index = 1; // wrap
1141 } else {
1142 _cur_stat_index++;
1143 }
1144
1145 ls.print("%-28s [ "
1146 INT32_FORMAT_W(8) " " INT32_FORMAT_W(8) " "
1147 "]",
1148 VM_Operation::name(_current_type),
1149 _nof_threads,
1150 _nof_running);
1151 ls.print("[ "
1152 INT64_FORMAT_W(10) " " INT64_FORMAT_W(10) " "
1153 INT64_FORMAT_W(10) " " INT64_FORMAT_W(10) " ]",
1154 (int64_t)(_last_safepoint_sync_time_ns - _last_safepoint_begin_time_ns),
1155 (int64_t)(_last_safepoint_cleanup_time_ns - _last_safepoint_sync_time_ns),
1156 (int64_t)(_last_safepoint_end_time_ns - _last_safepoint_cleanup_time_ns),
1157 (int64_t)(_last_safepoint_end_time_ns - _last_safepoint_begin_time_ns));
1158
1159 ls.print_cr(INT32_FORMAT_W(16), _page_trap);
1160 }
1161
1162 // This method will be called when VM exits. This tries to summarize the sampling.
1163 // Current thread may already be deleted, so don't use ResourceMark.
1164 void SafepointTracing::statistics_exit_log() {
1165 if (!log_is_enabled(Info, safepoint, stats)) {
1166 return;
1167 }
1168 for (int index = 0; index < VM_Operation::VMOp_Terminating; index++) {
1169 if (_op_count[index] != 0) {
1170 log_info(safepoint, stats)("%-28s" UINT64_FORMAT_W(10), VM_Operation::name(index),
1171 _op_count[index]);
1172 }
1173 }
1174
1175 log_info(safepoint, stats)("VM operations coalesced during safepoint " INT64_FORMAT,
1176 VMThread::get_coalesced_count());
1177 log_info(safepoint, stats)("Maximum sync time " INT64_FORMAT" ns",
1178 (int64_t)(_max_sync_time));
1179 log_info(safepoint, stats)("Maximum vm operation time (except for Exit VM operation) "
1180 INT64_FORMAT " ns",
1181 (int64_t)(_max_vmop_time));
1182 }
1183
1184 void SafepointTracing::begin(VM_Operation::VMOp_Type type) {
1185 _op_count[type]++;
1186 _current_type = type;
1187
1188 // update the time stamp to begin recording safepoint time
1189 _last_safepoint_begin_time_ns = os::javaTimeNanos();
1190 _last_safepoint_sync_time_ns = 0;
1191 _last_safepoint_cleanup_time_ns = 0;
1192
1193 _last_app_time_ns = _last_safepoint_begin_time_ns - _last_safepoint_end_time_ns;
1194 _last_safepoint_end_time_ns = 0;
1195
1196 RuntimeService::record_safepoint_begin(_last_app_time_ns);
1197 }
1198
1199 void SafepointTracing::synchronized(int nof_threads, int nof_running, int traps) {
1200 _last_safepoint_sync_time_ns = os::javaTimeNanos();
1201 _nof_threads = nof_threads;
1202 _nof_running = nof_running;
1203 _page_trap = traps;
1204 RuntimeService::record_safepoint_synchronized(_last_safepoint_sync_time_ns - _last_safepoint_begin_time_ns);
1205 }
1206
1207 void SafepointTracing::cleanup() {
1208 _last_safepoint_cleanup_time_ns = os::javaTimeNanos();
1209 }
1210
1211 void SafepointTracing::end() {
1212 _last_safepoint_end_time_ns = os::javaTimeNanos();
1213
1214 if (_max_sync_time < (_last_safepoint_sync_time_ns - _last_safepoint_begin_time_ns)) {
1215 _max_sync_time = _last_safepoint_sync_time_ns - _last_safepoint_begin_time_ns;
1216 }
1217 if (_max_vmop_time < (_last_safepoint_end_time_ns - _last_safepoint_sync_time_ns)) {
1218 _max_vmop_time = _last_safepoint_end_time_ns - _last_safepoint_sync_time_ns;
1219 }
1220 if (log_is_enabled(Info, safepoint, stats)) {
1221 statistics_log();
1222 }
1223
1224 log_info(safepoint)(
1225 "Safepoint \"%s\", "
1226 "Time since last: " JLONG_FORMAT " ns, "
1227 "Reaching safepoint: " JLONG_FORMAT " ns, "
1228 "At safepoint: " JLONG_FORMAT " ns, "
1229 "Total: " JLONG_FORMAT " ns",
1230 VM_Operation::name(_current_type),
1231 _last_app_time_ns,
1232 _last_safepoint_cleanup_time_ns - _last_safepoint_begin_time_ns,
1233 _last_safepoint_end_time_ns - _last_safepoint_cleanup_time_ns,
1234 _last_safepoint_end_time_ns - _last_safepoint_begin_time_ns
1235 );
1236
1237 RuntimeService::record_safepoint_end(_last_safepoint_end_time_ns - _last_safepoint_cleanup_time_ns);
1238 }