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 cleanup safepoint if there are too many monitors in use
494 // and the monitor deflation needs to be done at a safepoint.
495 if (ObjectSynchronizer::is_safepoint_deflation_needed()) return true;
496 // Need a safepoint if some inline cache buffers is non-empty
497 if (!InlineCacheBuffer::is_empty()) return true;
498 if (StringTable::needs_rehashing()) return true;
499 if (SymbolTable::needs_rehashing()) return true;
500 return false;
501 }
502
503 class ParallelSPCleanupThreadClosure : public ThreadClosure {
504 private:
505 DeflateMonitorCounters* _counters;
506
507 public:
508 ParallelSPCleanupThreadClosure(DeflateMonitorCounters* counters) :
509 _counters(counters) {}
510
511 void do_thread(Thread* thread) {
512 // deflate_thread_local_monitors() handles or requests deflation of
513 // this thread's idle monitors. If !AsyncDeflateIdleMonitors or if
514 // there is a special cleanup request, deflation is handled now.
515 // Otherwise, async deflation is requested via a flag.
516 ObjectSynchronizer::deflate_thread_local_monitors(thread, _counters);
517 }
518 };
519
520 class ParallelSPCleanupTask : public AbstractGangTask {
521 private:
522 SubTasksDone _subtasks;
523 ParallelSPCleanupThreadClosure _cleanup_threads_cl;
524 uint _num_workers;
525 DeflateMonitorCounters* _counters;
526 public:
527 ParallelSPCleanupTask(uint num_workers, DeflateMonitorCounters* counters) :
528 AbstractGangTask("Parallel Safepoint Cleanup"),
529 _subtasks(SafepointSynchronize::SAFEPOINT_CLEANUP_NUM_TASKS),
530 _cleanup_threads_cl(ParallelSPCleanupThreadClosure(counters)),
531 _num_workers(num_workers),
532 _counters(counters) {}
533
534 void work(uint worker_id) {
535 uint64_t safepoint_id = SafepointSynchronize::safepoint_id();
536 // All threads deflate monitors and mark nmethods (if necessary).
537 Threads::possibly_parallel_threads_do(true, &_cleanup_threads_cl);
538
539 if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_DEFLATE_MONITORS)) {
540 const char* name = "deflating global idle monitors";
541 EventSafepointCleanupTask event;
542 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
543 // AsyncDeflateIdleMonitors only uses DeflateMonitorCounters
544 // when a special cleanup has been requested.
545 // Note: This logging output will include global idle monitor
546 // elapsed times, but not global idle monitor deflation count.
547 ObjectSynchronizer::do_safepoint_work(_counters);
548
549 post_safepoint_cleanup_task_event(event, safepoint_id, name);
550 }
551
552 if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_UPDATE_INLINE_CACHES)) {
553 const char* name = "updating inline caches";
554 EventSafepointCleanupTask event;
555 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
556 InlineCacheBuffer::update_inline_caches();
557
558 post_safepoint_cleanup_task_event(event, safepoint_id, name);
559 }
560
561 if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_COMPILATION_POLICY)) {
562 const char* name = "compilation policy safepoint handler";
563 EventSafepointCleanupTask event;
564 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
565 CompilationPolicy::policy()->do_safepoint_work();
566
567 post_safepoint_cleanup_task_event(event, safepoint_id, name);
568 }
569
570 if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_SYMBOL_TABLE_REHASH)) {
571 if (SymbolTable::needs_rehashing()) {
572 const char* name = "rehashing symbol table";
573 EventSafepointCleanupTask event;
574 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
575 SymbolTable::rehash_table();
576
577 post_safepoint_cleanup_task_event(event, safepoint_id, name);
578 }
579 }
580
581 if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_STRING_TABLE_REHASH)) {
582 if (StringTable::needs_rehashing()) {
583 const char* name = "rehashing string table";
584 EventSafepointCleanupTask event;
585 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
586 StringTable::rehash_table();
587
588 post_safepoint_cleanup_task_event(event, safepoint_id, name);
589 }
590 }
591
592 if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_SYSTEM_DICTIONARY_RESIZE)) {
593 if (Dictionary::does_any_dictionary_needs_resizing()) {
594 const char* name = "resizing system dictionaries";
595 EventSafepointCleanupTask event;
596 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
597 ClassLoaderDataGraph::resize_dictionaries();
598
599 post_safepoint_cleanup_task_event(event, safepoint_id, name);
600 }
601 }
602
603 if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_REQUEST_OOPSTORAGE_CLEANUP)) {
604 // Don't bother reporting event or time for this very short operation.
605 // To have any utility we'd also want to report whether needed.
606 OopStorage::trigger_cleanup_if_needed();
607 }
608
609 _subtasks.all_tasks_completed(_num_workers);
610 }
611 };
612
613 // Various cleaning tasks that should be done periodically at safepoints.
614 void SafepointSynchronize::do_cleanup_tasks() {
615
616 TraceTime timer("safepoint cleanup tasks", TRACETIME_LOG(Info, safepoint, cleanup));
617
618 // Prepare for monitor deflation.
619 DeflateMonitorCounters deflate_counters;
620 ObjectSynchronizer::prepare_deflate_idle_monitors(&deflate_counters);
621
622 CollectedHeap* heap = Universe::heap();
623 assert(heap != NULL, "heap not initialized yet?");
624 WorkGang* cleanup_workers = heap->get_safepoint_workers();
625 if (cleanup_workers != NULL) {
626 // Parallel cleanup using GC provided thread pool.
627 uint num_cleanup_workers = cleanup_workers->active_workers();
628 ParallelSPCleanupTask cleanup(num_cleanup_workers, &deflate_counters);
629 StrongRootsScope srs(num_cleanup_workers);
630 cleanup_workers->run_task(&cleanup);
631 } else {
632 // Serial cleanup using VMThread.
633 ParallelSPCleanupTask cleanup(1, &deflate_counters);
634 StrongRootsScope srs(1);
635 cleanup.work(0);
636 }
637
638 // Needs to be done single threaded by the VMThread. This walks
639 // the thread stacks looking for references to metadata before
640 // deciding to remove it from the metaspaces.
641 if (ClassLoaderDataGraph::should_clean_metaspaces_and_reset()) {
642 const char* name = "cleanup live ClassLoaderData metaspaces";
643 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
644 ClassLoaderDataGraph::walk_metadata_and_clean_metaspaces();
645 }
646
647 // Finish monitor deflation.
648 ObjectSynchronizer::finish_deflate_idle_monitors(&deflate_counters);
649
650 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
651 }
652
653 // Methods for determining if a JavaThread is safepoint safe.
654
655 // False means unsafe with undetermined state.
656 // True means a determined state, but it may be an unsafe state.
657 // If called from a non-safepoint context safepoint_count MUST be InactiveSafepointCounter.
658 bool SafepointSynchronize::try_stable_load_state(JavaThreadState *state, JavaThread *thread, uint64_t safepoint_count) {
659 assert((safepoint_count != InactiveSafepointCounter &&
660 Thread::current() == (Thread*)VMThread::vm_thread() &&
661 SafepointSynchronize::_state != _not_synchronized)
662 || safepoint_count == InactiveSafepointCounter, "Invalid check");
663
664 // To handle the thread_blocked state on the backedge of the WaitBarrier from
665 // previous safepoint and reading the reset value (0/InactiveSafepointCounter) we
666 // re-read state after we read thread safepoint id. The JavaThread changes its
667 // thread state from thread_blocked before resetting safepoint id to 0.
668 // This guarantees the second read will be from an updated thread state. It can
669 // either be different state making this an unsafe state or it can see blocked
670 // again. When we see blocked twice with a 0 safepoint id, either:
671 // - It is normally blocked, e.g. on Mutex, TBIVM.
672 // - It was in SS:block(), looped around to SS:block() and is blocked on the WaitBarrier.
673 // - It was in SS:block() but now on a Mutex.
674 // All of these cases are safe.
675
676 *state = thread->thread_state();
677 OrderAccess::loadload();
678 uint64_t sid = thread->safepoint_state()->get_safepoint_id(); // Load acquire
679 if (sid != InactiveSafepointCounter && sid != safepoint_count) {
680 // In an old safepoint, state not relevant.
681 return false;
682 }
683 return *state == thread->thread_state();
684 }
685
686 static bool safepoint_safe_with(JavaThread *thread, JavaThreadState state) {
687 switch(state) {
688 case _thread_in_native:
689 // native threads are safe if they have no java stack or have walkable stack
690 return !thread->has_last_Java_frame() || thread->frame_anchor()->walkable();
691
692 case _thread_blocked:
693 // On wait_barrier or blocked.
694 // Blocked threads should already have walkable stack.
695 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "blocked and not walkable");
696 return true;
697
698 default:
699 return false;
700 }
701 }
702
703 bool SafepointSynchronize::handshake_safe(JavaThread *thread) {
704 if (thread->is_ext_suspended() || thread->is_terminated()) {
705 return true;
706 }
707 JavaThreadState stable_state;
708 if (try_stable_load_state(&stable_state, thread, InactiveSafepointCounter)) {
709 return safepoint_safe_with(thread, stable_state);
710 }
711 return false;
712 }
713
714 // See if the thread is running inside a lazy critical native and
715 // update the thread critical count if so. Also set a suspend flag to
716 // cause the native wrapper to return into the JVM to do the unlock
717 // once the native finishes.
718 static void check_for_lazy_critical_native(JavaThread *thread, JavaThreadState state) {
719 if (state == _thread_in_native &&
720 thread->has_last_Java_frame() &&
721 thread->frame_anchor()->walkable()) {
722 // This thread might be in a critical native nmethod so look at
723 // the top of the stack and increment the critical count if it
724 // is.
725 frame wrapper_frame = thread->last_frame();
726 CodeBlob* stub_cb = wrapper_frame.cb();
727 if (stub_cb != NULL &&
728 stub_cb->is_nmethod() &&
729 stub_cb->as_nmethod_or_null()->is_lazy_critical_native()) {
730 // A thread could potentially be in a critical native across
731 // more than one safepoint, so only update the critical state on
732 // the first one. When it returns it will perform the unlock.
733 if (!thread->do_critical_native_unlock()) {
734 #ifdef ASSERT
735 if (!thread->in_critical()) {
736 GCLocker::increment_debug_jni_lock_count();
737 }
738 #endif
739 thread->enter_critical();
740 // Make sure the native wrapper calls back on return to
741 // perform the needed critical unlock.
742 thread->set_critical_native_unlock();
743 }
744 }
745 }
746 }
747
748 // -------------------------------------------------------------------------------------------------------
749 // Implementation of Safepoint blocking point
750
751 void SafepointSynchronize::block(JavaThread *thread) {
752 assert(thread != NULL, "thread must be set");
753 assert(thread->is_Java_thread(), "not a Java thread");
754
755 // Threads shouldn't block if they are in the middle of printing, but...
756 ttyLocker::break_tty_lock_for_safepoint(os::current_thread_id());
757
758 // Only bail from the block() call if the thread is gone from the
759 // thread list; starting to exit should still block.
760 if (thread->is_terminated()) {
761 // block current thread if we come here from native code when VM is gone
762 thread->block_if_vm_exited();
763
764 // otherwise do nothing
765 return;
766 }
767
768 JavaThreadState state = thread->thread_state();
769 thread->frame_anchor()->make_walkable(thread);
770
771 uint64_t safepoint_id = SafepointSynchronize::safepoint_counter();
772 // Check that we have a valid thread_state at this point
773 switch(state) {
774 case _thread_in_vm_trans:
775 case _thread_in_Java: // From compiled code
776 case _thread_in_native_trans:
777 case _thread_blocked_trans:
778 case _thread_new_trans:
779
780 // We have no idea where the VMThread is, it might even be at next safepoint.
781 // So we can miss this poll, but stop at next.
782
783 // Load dependent store, it must not pass loading of safepoint_id.
784 thread->safepoint_state()->set_safepoint_id(safepoint_id); // Release store
785
786 // This part we can skip if we notice we miss or are in a future safepoint.
787 OrderAccess::storestore();
788 // Load in wait barrier should not float up
789 thread->set_thread_state_fence(_thread_blocked);
790
791 _wait_barrier->wait(static_cast<int>(safepoint_id));
792 assert(_state != _synchronized, "Can't be");
793
794 // If barrier is disarmed stop store from floating above loads in barrier.
795 OrderAccess::loadstore();
796 thread->set_thread_state(state);
797
798 // Then we reset the safepoint id to inactive.
799 thread->safepoint_state()->reset_safepoint_id(); // Release store
800
801 OrderAccess::fence();
802
803 break;
804
805 default:
806 fatal("Illegal threadstate encountered: %d", state);
807 }
808 guarantee(thread->safepoint_state()->get_safepoint_id() == InactiveSafepointCounter,
809 "The safepoint id should be set only in block path");
810
811 // Check for pending. async. exceptions or suspends - except if the
812 // thread was blocked inside the VM. has_special_runtime_exit_condition()
813 // is called last since it grabs a lock and we only want to do that when
814 // we must.
815 //
816 // Note: we never deliver an async exception at a polling point as the
817 // compiler may not have an exception handler for it. The polling
818 // code will notice the async and deoptimize and the exception will
819 // be delivered. (Polling at a return point is ok though). Sure is
820 // a lot of bother for a deprecated feature...
821 //
822 // We don't deliver an async exception if the thread state is
823 // _thread_in_native_trans so JNI functions won't be called with
824 // a surprising pending exception. If the thread state is going back to java,
825 // async exception is checked in check_special_condition_for_native_trans().
826
827 if (state != _thread_blocked_trans &&
828 state != _thread_in_vm_trans &&
829 thread->has_special_runtime_exit_condition()) {
830 thread->handle_special_runtime_exit_condition(
831 !thread->is_at_poll_safepoint() && (state != _thread_in_native_trans));
832 }
833
834 // cross_modify_fence is done by SafepointMechanism::block_if_requested_slow
835 // which is the only caller here.
836 }
837
838 // ------------------------------------------------------------------------------------------------------
839 // Exception handlers
840
841
842 void SafepointSynchronize::handle_polling_page_exception(JavaThread *thread) {
843 assert(thread->is_Java_thread(), "polling reference encountered by VM thread");
844 assert(thread->thread_state() == _thread_in_Java, "should come from Java code");
845
846 if (log_is_enabled(Info, safepoint, stats)) {
847 Atomic::inc(&_nof_threads_hit_polling_page);
848 }
849
850 ThreadSafepointState* state = thread->safepoint_state();
851
852 state->handle_polling_page_exception();
853 }
854
855
856 void SafepointSynchronize::print_safepoint_timeout() {
857 if (!timeout_error_printed) {
858 timeout_error_printed = true;
859 // Print out the thread info which didn't reach the safepoint for debugging
860 // purposes (useful when there are lots of threads in the debugger).
861 LogTarget(Warning, safepoint) lt;
862 if (lt.is_enabled()) {
863 ResourceMark rm;
864 LogStream ls(lt);
865
866 ls.cr();
867 ls.print_cr("# SafepointSynchronize::begin: Timeout detected:");
868 ls.print_cr("# SafepointSynchronize::begin: Timed out while spinning to reach a safepoint.");
869 ls.print_cr("# SafepointSynchronize::begin: Threads which did not reach the safepoint:");
870 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *cur_thread = jtiwh.next(); ) {
871 if (cur_thread->safepoint_state()->is_running()) {
872 ls.print("# ");
873 cur_thread->print_on(&ls);
874 ls.cr();
875 }
876 }
877 ls.print_cr("# SafepointSynchronize::begin: (End of list)");
878 }
879 }
880
881 // To debug the long safepoint, specify both AbortVMOnSafepointTimeout &
882 // ShowMessageBoxOnError.
883 if (AbortVMOnSafepointTimeout) {
884 // Send the blocking thread a signal to terminate and write an error file.
885 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *cur_thread = jtiwh.next(); ) {
886 if (cur_thread->safepoint_state()->is_running()) {
887 if (!os::signal_thread(cur_thread, SIGILL, "blocking a safepoint")) {
888 break; // Could not send signal. Report fatal error.
889 }
890 // Give cur_thread a chance to report the error and terminate the VM.
891 os::naked_sleep(3000);
892 }
893 }
894 fatal("Safepoint sync time longer than " INTX_FORMAT "ms detected when executing %s.",
895 SafepointTimeoutDelay, VMThread::vm_operation()->name());
896 }
897 }
898
899 // -------------------------------------------------------------------------------------------------------
900 // Implementation of ThreadSafepointState
901
902 ThreadSafepointState::ThreadSafepointState(JavaThread *thread)
903 : _at_poll_safepoint(false), _thread(thread), _safepoint_safe(false),
904 _safepoint_id(SafepointSynchronize::InactiveSafepointCounter), _next(NULL) {
905 }
906
907 void ThreadSafepointState::create(JavaThread *thread) {
908 ThreadSafepointState *state = new ThreadSafepointState(thread);
909 thread->set_safepoint_state(state);
910 }
911
912 void ThreadSafepointState::destroy(JavaThread *thread) {
913 if (thread->safepoint_state()) {
914 delete(thread->safepoint_state());
915 thread->set_safepoint_state(NULL);
916 }
917 }
918
919 uint64_t ThreadSafepointState::get_safepoint_id() const {
920 return Atomic::load_acquire(&_safepoint_id);
921 }
922
923 void ThreadSafepointState::reset_safepoint_id() {
924 Atomic::release_store(&_safepoint_id, SafepointSynchronize::InactiveSafepointCounter);
925 }
926
927 void ThreadSafepointState::set_safepoint_id(uint64_t safepoint_id) {
928 Atomic::release_store(&_safepoint_id, safepoint_id);
929 }
930
931 void ThreadSafepointState::examine_state_of_thread(uint64_t safepoint_count) {
932 assert(is_running(), "better be running or just have hit safepoint poll");
933
934 JavaThreadState stable_state;
935 if (!SafepointSynchronize::try_stable_load_state(&stable_state, _thread, safepoint_count)) {
936 // We could not get stable state of the JavaThread.
937 // Consider it running and just return.
938 return;
939 }
940
941 // Check for a thread that is suspended. Note that thread resume tries
942 // to grab the Threads_lock which we own here, so a thread cannot be
943 // resumed during safepoint synchronization.
944
945 // We check to see if this thread is suspended without locking to
946 // avoid deadlocking with a third thread that is waiting for this
947 // thread to be suspended. The third thread can notice the safepoint
948 // that we're trying to start at the beginning of its SR_lock->wait()
949 // call. If that happens, then the third thread will block on the
950 // safepoint while still holding the underlying SR_lock. We won't be
951 // able to get the SR_lock and we'll deadlock.
952 //
953 // We don't need to grab the SR_lock here for two reasons:
954 // 1) The suspend flags are both volatile and are set with an
955 // Atomic::cmpxchg() call so we should see the suspended
956 // state right away.
957 // 2) We're being called from the safepoint polling loop; if
958 // we don't see the suspended state on this iteration, then
959 // we'll come around again.
960 //
961 bool is_suspended = _thread->is_ext_suspended();
962 if (is_suspended) {
963 account_safe_thread();
964 return;
965 }
966
967 if (safepoint_safe_with(_thread, stable_state)) {
968 check_for_lazy_critical_native(_thread, stable_state);
969 account_safe_thread();
970 return;
971 }
972
973 // All other thread states will continue to run until they
974 // transition and self-block in state _blocked
975 // Safepoint polling in compiled code causes the Java threads to do the same.
976 // Note: new threads may require a malloc so they must be allowed to finish
977
978 assert(is_running(), "examine_state_of_thread on non-running thread");
979 return;
980 }
981
982 void ThreadSafepointState::account_safe_thread() {
983 SafepointSynchronize::decrement_waiting_to_block();
984 if (_thread->in_critical()) {
985 // Notice that this thread is in a critical section
986 SafepointSynchronize::increment_jni_active_count();
987 }
988 DEBUG_ONLY(_thread->set_visited_for_critical_count(SafepointSynchronize::safepoint_counter());)
989 assert(!_safepoint_safe, "Must be unsafe before safe");
990 _safepoint_safe = true;
991 }
992
993 void ThreadSafepointState::restart() {
994 assert(_safepoint_safe, "Must be safe before unsafe");
995 _safepoint_safe = false;
996 }
997
998 void ThreadSafepointState::print_on(outputStream *st) const {
999 const char *s = _safepoint_safe ? "_at_safepoint" : "_running";
1000
1001 st->print_cr("Thread: " INTPTR_FORMAT
1002 " [0x%2x] State: %s _at_poll_safepoint %d",
1003 p2i(_thread), _thread->osthread()->thread_id(), s, _at_poll_safepoint);
1004
1005 _thread->print_thread_state_on(st);
1006 }
1007
1008 // ---------------------------------------------------------------------------------------------------------------------
1009
1010 // Block the thread at poll or poll return for safepoint/handshake.
1011 void ThreadSafepointState::handle_polling_page_exception() {
1012
1013 // Step 1: Find the nmethod from the return address
1014 address real_return_addr = thread()->saved_exception_pc();
1015
1016 CodeBlob *cb = CodeCache::find_blob(real_return_addr);
1017 assert(cb != NULL && cb->is_compiled(), "return address should be in nmethod");
1018 CompiledMethod* nm = (CompiledMethod*)cb;
1019
1020 // Find frame of caller
1021 frame stub_fr = thread()->last_frame();
1022 CodeBlob* stub_cb = stub_fr.cb();
1023 assert(stub_cb->is_safepoint_stub(), "must be a safepoint stub");
1024 RegisterMap map(thread(), true);
1025 frame caller_fr = stub_fr.sender(&map);
1026
1027 // Should only be poll_return or poll
1028 assert( nm->is_at_poll_or_poll_return(real_return_addr), "should not be at call" );
1029
1030 // This is a poll immediately before a return. The exception handling code
1031 // has already had the effect of causing the return to occur, so the execution
1032 // will continue immediately after the call. In addition, the oopmap at the
1033 // return point does not mark the return value as an oop (if it is), so
1034 // it needs a handle here to be updated.
1035 if( nm->is_at_poll_return(real_return_addr) ) {
1036 // See if return type is an oop.
1037 bool return_oop = nm->method()->is_returning_oop();
1038 Handle return_value;
1039 if (return_oop) {
1040 // The oop result has been saved on the stack together with all
1041 // the other registers. In order to preserve it over GCs we need
1042 // to keep it in a handle.
1043 oop result = caller_fr.saved_oop_result(&map);
1044 assert(oopDesc::is_oop_or_null(result), "must be oop");
1045 return_value = Handle(thread(), result);
1046 assert(Universe::heap()->is_in_or_null(result), "must be heap pointer");
1047 }
1048
1049 // Block the thread
1050 SafepointMechanism::block_if_requested(thread());
1051
1052 // restore oop result, if any
1053 if (return_oop) {
1054 caller_fr.set_saved_oop_result(&map, return_value());
1055 }
1056 }
1057
1058 // This is a safepoint poll. Verify the return address and block.
1059 else {
1060 set_at_poll_safepoint(true);
1061
1062 // verify the blob built the "return address" correctly
1063 assert(real_return_addr == caller_fr.pc(), "must match");
1064
1065 // Block the thread
1066 SafepointMechanism::block_if_requested(thread());
1067 set_at_poll_safepoint(false);
1068
1069 // If we have a pending async exception deoptimize the frame
1070 // as otherwise we may never deliver it.
1071 if (thread()->has_async_condition()) {
1072 ThreadInVMfromJavaNoAsyncException __tiv(thread());
1073 Deoptimization::deoptimize_frame(thread(), caller_fr.id());
1074 }
1075
1076 // If an exception has been installed we must check for a pending deoptimization
1077 // Deoptimize frame if exception has been thrown.
1078
1079 if (thread()->has_pending_exception() ) {
1080 RegisterMap map(thread(), true);
1081 frame caller_fr = stub_fr.sender(&map);
1082 if (caller_fr.is_deoptimized_frame()) {
1083 // The exception patch will destroy registers that are still
1084 // live and will be needed during deoptimization. Defer the
1085 // Async exception should have deferred the exception until the
1086 // next safepoint which will be detected when we get into
1087 // the interpreter so if we have an exception now things
1088 // are messed up.
1089
1090 fatal("Exception installed and deoptimization is pending");
1091 }
1092 }
1093 }
1094 }
1095
1096
1097 // -------------------------------------------------------------------------------------------------------
1098 // Implementation of SafepointTracing
1099
1100 jlong SafepointTracing::_last_safepoint_begin_time_ns = 0;
1101 jlong SafepointTracing::_last_safepoint_sync_time_ns = 0;
1102 jlong SafepointTracing::_last_safepoint_cleanup_time_ns = 0;
1103 jlong SafepointTracing::_last_safepoint_end_time_ns = 0;
1104 jlong SafepointTracing::_last_app_time_ns = 0;
1105 int SafepointTracing::_nof_threads = 0;
1106 int SafepointTracing::_nof_running = 0;
1107 int SafepointTracing::_page_trap = 0;
1108 VM_Operation::VMOp_Type SafepointTracing::_current_type;
1109 jlong SafepointTracing::_max_sync_time = 0;
1110 jlong SafepointTracing::_max_vmop_time = 0;
1111 uint64_t SafepointTracing::_op_count[VM_Operation::VMOp_Terminating] = {0};
1112
1113 void SafepointTracing::init() {
1114 // Application start
1115 _last_safepoint_end_time_ns = os::javaTimeNanos();
1116 }
1117
1118 // Helper method to print the header.
1119 static void print_header(outputStream* st) {
1120 // The number of spaces is significant here, and should match the format
1121 // specifiers in print_statistics().
1122
1123 st->print("VM Operation "
1124 "[ threads: total initial_running ]"
1125 "[ time: sync cleanup vmop total ]");
1126
1127 st->print_cr(" page_trap_count");
1128 }
1129
1130 // This prints a nice table. To get the statistics to not shift due to the logging uptime
1131 // decorator, use the option as: -Xlog:safepoint+stats:[outputfile]:none
1132 void SafepointTracing::statistics_log() {
1133 LogTarget(Info, safepoint, stats) lt;
1134 assert (lt.is_enabled(), "should only be called when printing statistics is enabled");
1135 LogStream ls(lt);
1136
1137 static int _cur_stat_index = 0;
1138
1139 // Print header every 30 entries
1140 if ((_cur_stat_index % 30) == 0) {
1141 print_header(&ls);
1142 _cur_stat_index = 1; // wrap
1143 } else {
1144 _cur_stat_index++;
1145 }
1146
1147 ls.print("%-28s [ "
1148 INT32_FORMAT_W(8) " " INT32_FORMAT_W(8) " "
1149 "]",
1150 VM_Operation::name(_current_type),
1151 _nof_threads,
1152 _nof_running);
1153 ls.print("[ "
1154 INT64_FORMAT_W(10) " " INT64_FORMAT_W(10) " "
1155 INT64_FORMAT_W(10) " " INT64_FORMAT_W(10) " ]",
1156 (int64_t)(_last_safepoint_sync_time_ns - _last_safepoint_begin_time_ns),
1157 (int64_t)(_last_safepoint_cleanup_time_ns - _last_safepoint_sync_time_ns),
1158 (int64_t)(_last_safepoint_end_time_ns - _last_safepoint_cleanup_time_ns),
1159 (int64_t)(_last_safepoint_end_time_ns - _last_safepoint_begin_time_ns));
1160
1161 ls.print_cr(INT32_FORMAT_W(16), _page_trap);
1162 }
1163
1164 // This method will be called when VM exits. This tries to summarize the sampling.
1165 // Current thread may already be deleted, so don't use ResourceMark.
1166 void SafepointTracing::statistics_exit_log() {
1167 if (!log_is_enabled(Info, safepoint, stats)) {
1168 return;
1169 }
1170 for (int index = 0; index < VM_Operation::VMOp_Terminating; index++) {
1171 if (_op_count[index] != 0) {
1172 log_info(safepoint, stats)("%-28s" UINT64_FORMAT_W(10), VM_Operation::name(index),
1173 _op_count[index]);
1174 }
1175 }
1176
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 }