1 /*
2 * Copyright (c) 1997, 2010, 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/systemDictionary.hpp"
27 #include "code/codeCache.hpp"
28 #include "code/icBuffer.hpp"
29 #include "code/nmethod.hpp"
30 #include "code/pcDesc.hpp"
31 #include "code/scopeDesc.hpp"
32 #include "gc_interface/collectedHeap.hpp"
33 #include "interpreter/interpreter.hpp"
34 #include "memory/resourceArea.hpp"
35 #include "memory/universe.inline.hpp"
36 #include "oops/oop.inline.hpp"
37 #include "oops/symbolOop.hpp"
38 #include "runtime/compilationPolicy.hpp"
39 #include "runtime/deoptimization.hpp"
40 #include "runtime/frame.inline.hpp"
41 #include "runtime/interfaceSupport.hpp"
42 #include "runtime/mutexLocker.hpp"
43 #include "runtime/osThread.hpp"
44 #include "runtime/safepoint.hpp"
45 #include "runtime/signature.hpp"
46 #include "runtime/stubCodeGenerator.hpp"
47 #include "runtime/stubRoutines.hpp"
48 #include "runtime/sweeper.hpp"
49 #include "runtime/synchronizer.hpp"
50 #include "services/runtimeService.hpp"
51 #include "utilities/events.hpp"
52 #ifdef TARGET_ARCH_x86
53 # include "nativeInst_x86.hpp"
54 # include "vmreg_x86.inline.hpp"
55 #endif
56 #ifdef TARGET_ARCH_sparc
57 # include "nativeInst_sparc.hpp"
58 # include "vmreg_sparc.inline.hpp"
59 #endif
60 #ifdef TARGET_ARCH_zero
61 # include "nativeInst_zero.hpp"
62 # include "vmreg_zero.inline.hpp"
63 #endif
64 #ifdef TARGET_OS_FAMILY_linux
65 # include "thread_linux.inline.hpp"
66 #endif
67 #ifdef TARGET_OS_FAMILY_solaris
68 # include "thread_solaris.inline.hpp"
69 #endif
70 #ifdef TARGET_OS_FAMILY_windows
71 # include "thread_windows.inline.hpp"
72 #endif
73 #ifndef SERIALGC
74 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
75 #include "gc_implementation/shared/concurrentGCThread.hpp"
76 #endif
77 #ifdef COMPILER1
78 #include "c1/c1_globals.hpp"
79 #endif
80
81 // --------------------------------------------------------------------------------------------------
82 // Implementation of Safepoint begin/end
83
84 SafepointSynchronize::SynchronizeState volatile SafepointSynchronize::_state = SafepointSynchronize::_not_synchronized;
85 volatile int SafepointSynchronize::_waiting_to_block = 0;
86 volatile int SafepointSynchronize::_safepoint_counter = 0;
87 long SafepointSynchronize::_end_of_last_safepoint = 0;
88 static volatile int PageArmed = 0 ; // safepoint polling page is RO|RW vs PROT_NONE
89 static volatile int TryingToBlock = 0 ; // proximate value -- for advisory use only
90 static bool timeout_error_printed = false;
91
92 // Roll all threads forward to a safepoint and suspend them all
93 void SafepointSynchronize::begin() {
94
95 Thread* myThread = Thread::current();
96 assert(myThread->is_VM_thread(), "Only VM thread may execute a safepoint");
97
98 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) {
99 _safepoint_begin_time = os::javaTimeNanos();
100 _ts_of_current_safepoint = tty->time_stamp().seconds();
101 }
102
103 #ifndef SERIALGC
104 if (UseConcMarkSweepGC) {
105 // In the future we should investigate whether CMS can use the
106 // more-general mechanism below. DLD (01/05).
107 ConcurrentMarkSweepThread::synchronize(false);
108 } else if (UseG1GC) {
109 ConcurrentGCThread::safepoint_synchronize();
110 }
111 #endif // SERIALGC
112
113 // By getting the Threads_lock, we assure that no threads are about to start or
114 // exit. It is released again in SafepointSynchronize::end().
115 Threads_lock->lock();
116
117 assert( _state == _not_synchronized, "trying to safepoint synchronize with wrong state");
118
119 int nof_threads = Threads::number_of_threads();
120
121 if (TraceSafepoint) {
122 tty->print_cr("Safepoint synchronization initiated. (%d)", nof_threads);
123 }
124
125 RuntimeService::record_safepoint_begin();
126
127 {
128 MutexLocker mu(Safepoint_lock);
129
130 // Set number of threads to wait for, before we initiate the callbacks
131 _waiting_to_block = nof_threads;
132 TryingToBlock = 0 ;
133 int still_running = nof_threads;
134
135 // Save the starting time, so that it can be compared to see if this has taken
136 // too long to complete.
137 jlong safepoint_limit_time;
138 timeout_error_printed = false;
139
140 // PrintSafepointStatisticsTimeout can be specified separately. When
141 // specified, PrintSafepointStatistics will be set to true in
142 // deferred_initialize_stat method. The initialization has to be done
143 // early enough to avoid any races. See bug 6880029 for details.
144 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) {
145 deferred_initialize_stat();
146 }
147
148 // Begin the process of bringing the system to a safepoint.
149 // Java threads can be in several different states and are
150 // stopped by different mechanisms:
151 //
152 // 1. Running interpreted
153 // The interpeter dispatch table is changed to force it to
154 // check for a safepoint condition between bytecodes.
155 // 2. Running in native code
156 // When returning from the native code, a Java thread must check
157 // the safepoint _state to see if we must block. If the
158 // VM thread sees a Java thread in native, it does
159 // not wait for this thread to block. The order of the memory
160 // writes and reads of both the safepoint state and the Java
161 // threads state is critical. In order to guarantee that the
162 // memory writes are serialized with respect to each other,
163 // the VM thread issues a memory barrier instruction
164 // (on MP systems). In order to avoid the overhead of issuing
165 // a memory barrier for each Java thread making native calls, each Java
166 // thread performs a write to a single memory page after changing
167 // the thread state. The VM thread performs a sequence of
168 // mprotect OS calls which forces all previous writes from all
169 // Java threads to be serialized. This is done in the
170 // os::serialize_thread_states() call. This has proven to be
171 // much more efficient than executing a membar instruction
172 // on every call to native code.
173 // 3. Running compiled Code
174 // Compiled code reads a global (Safepoint Polling) page that
175 // is set to fault if we are trying to get to a safepoint.
176 // 4. Blocked
177 // A thread which is blocked will not be allowed to return from the
178 // block condition until the safepoint operation is complete.
179 // 5. In VM or Transitioning between states
180 // If a Java thread is currently running in the VM or transitioning
181 // between states, the safepointing code will wait for the thread to
182 // block itself when it attempts transitions to a new state.
183 //
184 _state = _synchronizing;
185 OrderAccess::fence();
186
187 // Flush all thread states to memory
188 if (!UseMembar) {
189 os::serialize_thread_states();
190 }
191
192 // Make interpreter safepoint aware
193 Interpreter::notice_safepoints();
194
195 if (UseCompilerSafepoints && DeferPollingPageLoopCount < 0) {
196 // Make polling safepoint aware
197 guarantee (PageArmed == 0, "invariant") ;
198 PageArmed = 1 ;
199 os::make_polling_page_unreadable();
200 }
201
202 // Consider using active_processor_count() ... but that call is expensive.
203 int ncpus = os::processor_count() ;
204
205 #ifdef ASSERT
206 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) {
207 assert(cur->safepoint_state()->is_running(), "Illegal initial state");
208 }
209 #endif // ASSERT
210
211 if (SafepointTimeout)
212 safepoint_limit_time = os::javaTimeNanos() + (jlong)SafepointTimeoutDelay * MICROUNITS;
213
214 // Iterate through all threads until it have been determined how to stop them all at a safepoint
215 unsigned int iterations = 0;
216 int steps = 0 ;
217 while(still_running > 0) {
218 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) {
219 assert(!cur->is_ConcurrentGC_thread(), "A concurrent GC thread is unexpectly being suspended");
220 ThreadSafepointState *cur_state = cur->safepoint_state();
221 if (cur_state->is_running()) {
222 cur_state->examine_state_of_thread();
223 if (!cur_state->is_running()) {
224 still_running--;
225 // consider adjusting steps downward:
226 // steps = 0
227 // steps -= NNN
228 // steps >>= 1
229 // steps = MIN(steps, 2000-100)
230 // if (iterations != 0) steps -= NNN
231 }
232 if (TraceSafepoint && Verbose) cur_state->print();
233 }
234 }
235
236 if (PrintSafepointStatistics && iterations == 0) {
237 begin_statistics(nof_threads, still_running);
238 }
239
240 if (still_running > 0) {
241 // Check for if it takes to long
242 if (SafepointTimeout && safepoint_limit_time < os::javaTimeNanos()) {
243 print_safepoint_timeout(_spinning_timeout);
244 }
245
246 // Spin to avoid context switching.
247 // There's a tension between allowing the mutators to run (and rendezvous)
248 // vs spinning. As the VM thread spins, wasting cycles, it consumes CPU that
249 // a mutator might otherwise use profitably to reach a safepoint. Excessive
250 // spinning by the VM thread on a saturated system can increase rendezvous latency.
251 // Blocking or yielding incur their own penalties in the form of context switching
252 // and the resultant loss of $ residency.
253 //
254 // Further complicating matters is that yield() does not work as naively expected
255 // on many platforms -- yield() does not guarantee that any other ready threads
256 // will run. As such we revert yield_all() after some number of iterations.
257 // Yield_all() is implemented as a short unconditional sleep on some platforms.
258 // Typical operating systems round a "short" sleep period up to 10 msecs, so sleeping
259 // can actually increase the time it takes the VM thread to detect that a system-wide
260 // stop-the-world safepoint has been reached. In a pathological scenario such as that
261 // described in CR6415670 the VMthread may sleep just before the mutator(s) become safe.
262 // In that case the mutators will be stalled waiting for the safepoint to complete and the
263 // the VMthread will be sleeping, waiting for the mutators to rendezvous. The VMthread
264 // will eventually wake up and detect that all mutators are safe, at which point
265 // we'll again make progress.
266 //
267 // Beware too that that the VMThread typically runs at elevated priority.
268 // Its default priority is higher than the default mutator priority.
269 // Obviously, this complicates spinning.
270 //
271 // Note too that on Windows XP SwitchThreadTo() has quite different behavior than Sleep(0).
272 // Sleep(0) will _not yield to lower priority threads, while SwitchThreadTo() will.
273 //
274 // See the comments in synchronizer.cpp for additional remarks on spinning.
275 //
276 // In the future we might:
277 // 1. Modify the safepoint scheme to avoid potentally unbounded spinning.
278 // This is tricky as the path used by a thread exiting the JVM (say on
279 // on JNI call-out) simply stores into its state field. The burden
280 // is placed on the VM thread, which must poll (spin).
281 // 2. Find something useful to do while spinning. If the safepoint is GC-related
282 // we might aggressively scan the stacks of threads that are already safe.
283 // 3. Use Solaris schedctl to examine the state of the still-running mutators.
284 // If all the mutators are ONPROC there's no reason to sleep or yield.
285 // 4. YieldTo() any still-running mutators that are ready but OFFPROC.
286 // 5. Check system saturation. If the system is not fully saturated then
287 // simply spin and avoid sleep/yield.
288 // 6. As still-running mutators rendezvous they could unpark the sleeping
289 // VMthread. This works well for still-running mutators that become
290 // safe. The VMthread must still poll for mutators that call-out.
291 // 7. Drive the policy on time-since-begin instead of iterations.
292 // 8. Consider making the spin duration a function of the # of CPUs:
293 // Spin = (((ncpus-1) * M) + K) + F(still_running)
294 // Alternately, instead of counting iterations of the outer loop
295 // we could count the # of threads visited in the inner loop, above.
296 // 9. On windows consider using the return value from SwitchThreadTo()
297 // to drive subsequent spin/SwitchThreadTo()/Sleep(N) decisions.
298
299 if (UseCompilerSafepoints && int(iterations) == DeferPollingPageLoopCount) {
300 guarantee (PageArmed == 0, "invariant") ;
301 PageArmed = 1 ;
302 os::make_polling_page_unreadable();
303 }
304
305 // Instead of (ncpus > 1) consider either (still_running < (ncpus + EPSILON)) or
306 // ((still_running + _waiting_to_block - TryingToBlock)) < ncpus)
307 ++steps ;
308 if (ncpus > 1 && steps < SafepointSpinBeforeYield) {
309 SpinPause() ; // MP-Polite spin
310 } else
311 if (steps < DeferThrSuspendLoopCount) {
312 os::NakedYield() ;
313 } else {
314 os::yield_all(steps) ;
315 // Alternately, the VM thread could transiently depress its scheduling priority or
316 // transiently increase the priority of the tardy mutator(s).
317 }
318
319 iterations ++ ;
320 }
321 assert(iterations < (uint)max_jint, "We have been iterating in the safepoint loop too long");
322 }
323 assert(still_running == 0, "sanity check");
324
325 if (PrintSafepointStatistics) {
326 update_statistics_on_spin_end();
327 }
328
329 // wait until all threads are stopped
330 while (_waiting_to_block > 0) {
331 if (TraceSafepoint) tty->print_cr("Waiting for %d thread(s) to block", _waiting_to_block);
332 if (!SafepointTimeout || timeout_error_printed) {
333 Safepoint_lock->wait(true); // true, means with no safepoint checks
334 } else {
335 // Compute remaining time
336 jlong remaining_time = safepoint_limit_time - os::javaTimeNanos();
337
338 // If there is no remaining time, then there is an error
339 if (remaining_time < 0 || Safepoint_lock->wait(true, remaining_time / MICROUNITS)) {
340 print_safepoint_timeout(_blocking_timeout);
341 }
342 }
343 }
344 assert(_waiting_to_block == 0, "sanity check");
345
346 #ifndef PRODUCT
347 if (SafepointTimeout) {
348 jlong current_time = os::javaTimeNanos();
349 if (safepoint_limit_time < current_time) {
350 tty->print_cr("# SafepointSynchronize: Finished after "
351 INT64_FORMAT_W(6) " ms",
352 ((current_time - safepoint_limit_time) / MICROUNITS +
353 SafepointTimeoutDelay));
354 }
355 }
356 #endif
357
358 assert((_safepoint_counter & 0x1) == 0, "must be even");
359 assert(Threads_lock->owned_by_self(), "must hold Threads_lock");
360 _safepoint_counter ++;
361
362 // Record state
363 _state = _synchronized;
364
365 OrderAccess::fence();
366
367 if (TraceSafepoint) {
368 VM_Operation *op = VMThread::vm_operation();
369 tty->print_cr("Entering safepoint region: %s", (op != NULL) ? op->name() : "no vm operation");
370 }
371
372 RuntimeService::record_safepoint_synchronized();
373 if (PrintSafepointStatistics) {
374 update_statistics_on_sync_end(os::javaTimeNanos());
375 }
376
377 // Call stuff that needs to be run when a safepoint is just about to be completed
378 do_cleanup_tasks();
379
380 if (PrintSafepointStatistics) {
381 // Record how much time spend on the above cleanup tasks
382 update_statistics_on_cleanup_end(os::javaTimeNanos());
383 }
384 }
385 }
386
387 // Wake up all threads, so they are ready to resume execution after the safepoint
388 // operation has been carried out
389 void SafepointSynchronize::end() {
390
391 assert(Threads_lock->owned_by_self(), "must hold Threads_lock");
392 assert((_safepoint_counter & 0x1) == 1, "must be odd");
393 _safepoint_counter ++;
394 // memory fence isn't required here since an odd _safepoint_counter
395 // value can do no harm and a fence is issued below anyway.
396
397 DEBUG_ONLY(Thread* myThread = Thread::current();)
398 assert(myThread->is_VM_thread(), "Only VM thread can execute a safepoint");
399
400 if (PrintSafepointStatistics) {
401 end_statistics(os::javaTimeNanos());
402 }
403
404 #ifdef ASSERT
405 // A pending_exception cannot be installed during a safepoint. The threads
406 // may install an async exception after they come back from a safepoint into
407 // pending_exception after they unblock. But that should happen later.
408 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) {
409 assert (!(cur->has_pending_exception() &&
410 cur->safepoint_state()->is_at_poll_safepoint()),
411 "safepoint installed a pending exception");
412 }
413 #endif // ASSERT
414
415 if (PageArmed) {
416 // Make polling safepoint aware
417 os::make_polling_page_readable();
418 PageArmed = 0 ;
419 }
420
421 // Remove safepoint check from interpreter
422 Interpreter::ignore_safepoints();
423
424 {
425 MutexLocker mu(Safepoint_lock);
426
427 assert(_state == _synchronized, "must be synchronized before ending safepoint synchronization");
428
429 // Set to not synchronized, so the threads will not go into the signal_thread_blocked method
430 // when they get restarted.
431 _state = _not_synchronized;
432 OrderAccess::fence();
433
434 if (TraceSafepoint) {
435 tty->print_cr("Leaving safepoint region");
436 }
437
438 // Start suspended threads
439 for(JavaThread *current = Threads::first(); current; current = current->next()) {
440 // A problem occurring on Solaris is when attempting to restart threads
441 // the first #cpus - 1 go well, but then the VMThread is preempted when we get
442 // to the next one (since it has been running the longest). We then have
443 // to wait for a cpu to become available before we can continue restarting
444 // threads.
445 // FIXME: This causes the performance of the VM to degrade when active and with
446 // large numbers of threads. Apparently this is due to the synchronous nature
447 // of suspending threads.
448 //
449 // TODO-FIXME: the comments above are vestigial and no longer apply.
450 // Furthermore, using solaris' schedctl in this particular context confers no benefit
451 if (VMThreadHintNoPreempt) {
452 os::hint_no_preempt();
453 }
454 ThreadSafepointState* cur_state = current->safepoint_state();
455 assert(cur_state->type() != ThreadSafepointState::_running, "Thread not suspended at safepoint");
456 cur_state->restart();
457 assert(cur_state->is_running(), "safepoint state has not been reset");
458 }
459
460 RuntimeService::record_safepoint_end();
461
462 // Release threads lock, so threads can be created/destroyed again. It will also starts all threads
463 // blocked in signal_thread_blocked
464 Threads_lock->unlock();
465
466 }
467 #ifndef SERIALGC
468 // If there are any concurrent GC threads resume them.
469 if (UseConcMarkSweepGC) {
470 ConcurrentMarkSweepThread::desynchronize(false);
471 } else if (UseG1GC) {
472 ConcurrentGCThread::safepoint_desynchronize();
473 }
474 #endif // SERIALGC
475 // record this time so VMThread can keep track how much time has elasped
476 // since last safepoint.
477 _end_of_last_safepoint = os::javaTimeMillis();
478 }
479
480 bool SafepointSynchronize::is_cleanup_needed() {
481 // Need a safepoint if some inline cache buffers is non-empty
482 if (!InlineCacheBuffer::is_empty()) return true;
483 return false;
484 }
485
486
487
488 // Various cleaning tasks that should be done periodically at safepoints
489 void SafepointSynchronize::do_cleanup_tasks() {
490 {
491 TraceTime t1("deflating idle monitors", TraceSafepointCleanupTime);
492 ObjectSynchronizer::deflate_idle_monitors();
493 }
494
495 {
496 TraceTime t2("updating inline caches", TraceSafepointCleanupTime);
497 InlineCacheBuffer::update_inline_caches();
498 }
499 {
500 TraceTime t3("compilation policy safepoint handler", TraceSafepointCleanupTime);
501 CompilationPolicy::policy()->do_safepoint_work();
502 }
503
504 TraceTime t4("sweeping nmethods", TraceSafepointCleanupTime);
505 NMethodSweeper::scan_stacks();
506 }
507
508
509 bool SafepointSynchronize::safepoint_safe(JavaThread *thread, JavaThreadState state) {
510 switch(state) {
511 case _thread_in_native:
512 // native threads are safe if they have no java stack or have walkable stack
513 return !thread->has_last_Java_frame() || thread->frame_anchor()->walkable();
514
515 // blocked threads should have already have walkable stack
516 case _thread_blocked:
517 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "blocked and not walkable");
518 return true;
519
520 default:
521 return false;
522 }
523 }
524
525
526 // -------------------------------------------------------------------------------------------------------
527 // Implementation of Safepoint callback point
528
529 void SafepointSynchronize::block(JavaThread *thread) {
530 assert(thread != NULL, "thread must be set");
531 assert(thread->is_Java_thread(), "not a Java thread");
532
533 // Threads shouldn't block if they are in the middle of printing, but...
534 ttyLocker::break_tty_lock_for_safepoint(os::current_thread_id());
535
536 // Only bail from the block() call if the thread is gone from the
537 // thread list; starting to exit should still block.
538 if (thread->is_terminated()) {
539 // block current thread if we come here from native code when VM is gone
540 thread->block_if_vm_exited();
541
542 // otherwise do nothing
543 return;
544 }
545
546 JavaThreadState state = thread->thread_state();
547 thread->frame_anchor()->make_walkable(thread);
548
549 // Check that we have a valid thread_state at this point
550 switch(state) {
551 case _thread_in_vm_trans:
552 case _thread_in_Java: // From compiled code
553
554 // We are highly likely to block on the Safepoint_lock. In order to avoid blocking in this case,
555 // we pretend we are still in the VM.
556 thread->set_thread_state(_thread_in_vm);
557
558 if (is_synchronizing()) {
559 Atomic::inc (&TryingToBlock) ;
560 }
561
562 // We will always be holding the Safepoint_lock when we are examine the state
563 // of a thread. Hence, the instructions between the Safepoint_lock->lock() and
564 // Safepoint_lock->unlock() are happening atomic with regards to the safepoint code
565 Safepoint_lock->lock_without_safepoint_check();
566 if (is_synchronizing()) {
567 // Decrement the number of threads to wait for and signal vm thread
568 assert(_waiting_to_block > 0, "sanity check");
569 _waiting_to_block--;
570 thread->safepoint_state()->set_has_called_back(true);
571
572 // Consider (_waiting_to_block < 2) to pipeline the wakeup of the VM thread
573 if (_waiting_to_block == 0) {
574 Safepoint_lock->notify_all();
575 }
576 }
577
578 // We transition the thread to state _thread_blocked here, but
579 // we can't do our usual check for external suspension and then
580 // self-suspend after the lock_without_safepoint_check() call
581 // below because we are often called during transitions while
582 // we hold different locks. That would leave us suspended while
583 // holding a resource which results in deadlocks.
584 thread->set_thread_state(_thread_blocked);
585 Safepoint_lock->unlock();
586
587 // We now try to acquire the threads lock. Since this lock is hold by the VM thread during
588 // the entire safepoint, the threads will all line up here during the safepoint.
589 Threads_lock->lock_without_safepoint_check();
590 // restore original state. This is important if the thread comes from compiled code, so it
591 // will continue to execute with the _thread_in_Java state.
592 thread->set_thread_state(state);
593 Threads_lock->unlock();
594 break;
595
596 case _thread_in_native_trans:
597 case _thread_blocked_trans:
598 case _thread_new_trans:
599 if (thread->safepoint_state()->type() == ThreadSafepointState::_call_back) {
600 thread->print_thread_state();
601 fatal("Deadlock in safepoint code. "
602 "Should have called back to the VM before blocking.");
603 }
604
605 // We transition the thread to state _thread_blocked here, but
606 // we can't do our usual check for external suspension and then
607 // self-suspend after the lock_without_safepoint_check() call
608 // below because we are often called during transitions while
609 // we hold different locks. That would leave us suspended while
610 // holding a resource which results in deadlocks.
611 thread->set_thread_state(_thread_blocked);
612
613 // It is not safe to suspend a thread if we discover it is in _thread_in_native_trans. Hence,
614 // the safepoint code might still be waiting for it to block. We need to change the state here,
615 // so it can see that it is at a safepoint.
616
617 // Block until the safepoint operation is completed.
618 Threads_lock->lock_without_safepoint_check();
619
620 // Restore state
621 thread->set_thread_state(state);
622
623 Threads_lock->unlock();
624 break;
625
626 default:
627 fatal(err_msg("Illegal threadstate encountered: %d", state));
628 }
629
630 // Check for pending. async. exceptions or suspends - except if the
631 // thread was blocked inside the VM. has_special_runtime_exit_condition()
632 // is called last since it grabs a lock and we only want to do that when
633 // we must.
634 //
635 // Note: we never deliver an async exception at a polling point as the
636 // compiler may not have an exception handler for it. The polling
637 // code will notice the async and deoptimize and the exception will
638 // be delivered. (Polling at a return point is ok though). Sure is
639 // a lot of bother for a deprecated feature...
640 //
641 // We don't deliver an async exception if the thread state is
642 // _thread_in_native_trans so JNI functions won't be called with
643 // a surprising pending exception. If the thread state is going back to java,
644 // async exception is checked in check_special_condition_for_native_trans().
645
646 if (state != _thread_blocked_trans &&
647 state != _thread_in_vm_trans &&
648 thread->has_special_runtime_exit_condition()) {
649 thread->handle_special_runtime_exit_condition(
650 !thread->is_at_poll_safepoint() && (state != _thread_in_native_trans));
651 }
652 }
653
654 // ------------------------------------------------------------------------------------------------------
655 // Exception handlers
656
657 #ifndef PRODUCT
658 #ifdef _LP64
659 #define PTR_PAD ""
660 #else
661 #define PTR_PAD " "
662 #endif
663
664 static void print_ptrs(intptr_t oldptr, intptr_t newptr, bool wasoop) {
665 bool is_oop = newptr ? ((oop)newptr)->is_oop() : false;
666 tty->print_cr(PTR_FORMAT PTR_PAD " %s %c " PTR_FORMAT PTR_PAD " %s %s",
667 oldptr, wasoop?"oop":" ", oldptr == newptr ? ' ' : '!',
668 newptr, is_oop?"oop":" ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":" "));
669 }
670
671 static void print_longs(jlong oldptr, jlong newptr, bool wasoop) {
672 bool is_oop = newptr ? ((oop)(intptr_t)newptr)->is_oop() : false;
673 tty->print_cr(PTR64_FORMAT " %s %c " PTR64_FORMAT " %s %s",
674 oldptr, wasoop?"oop":" ", oldptr == newptr ? ' ' : '!',
675 newptr, is_oop?"oop":" ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":" "));
676 }
677
678 #ifdef SPARC
679 static void print_me(intptr_t *new_sp, intptr_t *old_sp, bool *was_oops) {
680 #ifdef _LP64
681 tty->print_cr("--------+------address-----+------before-----------+-------after----------+");
682 const int incr = 1; // Increment to skip a long, in units of intptr_t
683 #else
684 tty->print_cr("--------+--address-+------before-----------+-------after----------+");
685 const int incr = 2; // Increment to skip a long, in units of intptr_t
686 #endif
687 tty->print_cr("---SP---|");
688 for( int i=0; i<16; i++ ) {
689 tty->print("blob %c%d |"PTR_FORMAT" ","LO"[i>>3],i&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); }
690 tty->print_cr("--------|");
691 for( int i1=0; i1<frame::memory_parameter_word_sp_offset-16; i1++ ) {
692 tty->print("argv pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); }
693 tty->print(" pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++);
694 tty->print_cr("--------|");
695 tty->print(" G1 |"PTR_FORMAT" ",new_sp); print_longs(*(jlong*)old_sp,*(jlong*)new_sp,was_oops[incr-1]); old_sp += incr; new_sp += incr; was_oops += incr;
696 tty->print(" G3 |"PTR_FORMAT" ",new_sp); print_longs(*(jlong*)old_sp,*(jlong*)new_sp,was_oops[incr-1]); old_sp += incr; new_sp += incr; was_oops += incr;
697 tty->print(" G4 |"PTR_FORMAT" ",new_sp); print_longs(*(jlong*)old_sp,*(jlong*)new_sp,was_oops[incr-1]); old_sp += incr; new_sp += incr; was_oops += incr;
698 tty->print(" G5 |"PTR_FORMAT" ",new_sp); print_longs(*(jlong*)old_sp,*(jlong*)new_sp,was_oops[incr-1]); old_sp += incr; new_sp += incr; was_oops += incr;
699 tty->print_cr(" FSR |"PTR_FORMAT" "PTR64_FORMAT" "PTR64_FORMAT,new_sp,*(jlong*)old_sp,*(jlong*)new_sp);
700 old_sp += incr; new_sp += incr; was_oops += incr;
701 // Skip the floats
702 tty->print_cr("--Float-|"PTR_FORMAT,new_sp);
703 tty->print_cr("---FP---|");
704 old_sp += incr*32; new_sp += incr*32; was_oops += incr*32;
705 for( int i2=0; i2<16; i2++ ) {
706 tty->print("call %c%d |"PTR_FORMAT" ","LI"[i2>>3],i2&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); }
707 tty->print_cr("");
708 }
709 #endif // SPARC
710 #endif // PRODUCT
711
712
713 void SafepointSynchronize::handle_polling_page_exception(JavaThread *thread) {
714 assert(thread->is_Java_thread(), "polling reference encountered by VM thread");
715 assert(thread->thread_state() == _thread_in_Java, "should come from Java code");
716 assert(SafepointSynchronize::is_synchronizing(), "polling encountered outside safepoint synchronization");
717
718 // Uncomment this to get some serious before/after printing of the
719 // Sparc safepoint-blob frame structure.
720 /*
721 intptr_t* sp = thread->last_Java_sp();
722 intptr_t stack_copy[150];
723 for( int i=0; i<150; i++ ) stack_copy[i] = sp[i];
724 bool was_oops[150];
725 for( int i=0; i<150; i++ )
726 was_oops[i] = stack_copy[i] ? ((oop)stack_copy[i])->is_oop() : false;
727 */
728
729 if (ShowSafepointMsgs) {
730 tty->print("handle_polling_page_exception: ");
731 }
732
733 if (PrintSafepointStatistics) {
734 inc_page_trap_count();
735 }
736
737 ThreadSafepointState* state = thread->safepoint_state();
738
739 state->handle_polling_page_exception();
740 // print_me(sp,stack_copy,was_oops);
741 }
742
743
744 void SafepointSynchronize::print_safepoint_timeout(SafepointTimeoutReason reason) {
745 if (!timeout_error_printed) {
746 timeout_error_printed = true;
747 // Print out the thread infor which didn't reach the safepoint for debugging
748 // purposes (useful when there are lots of threads in the debugger).
749 tty->print_cr("");
750 tty->print_cr("# SafepointSynchronize::begin: Timeout detected:");
751 if (reason == _spinning_timeout) {
752 tty->print_cr("# SafepointSynchronize::begin: Timed out while spinning to reach a safepoint.");
753 } else if (reason == _blocking_timeout) {
754 tty->print_cr("# SafepointSynchronize::begin: Timed out while waiting for threads to stop.");
755 }
756
757 tty->print_cr("# SafepointSynchronize::begin: Threads which did not reach the safepoint:");
758 ThreadSafepointState *cur_state;
759 ResourceMark rm;
760 for(JavaThread *cur_thread = Threads::first(); cur_thread;
761 cur_thread = cur_thread->next()) {
762 cur_state = cur_thread->safepoint_state();
763
764 if (cur_thread->thread_state() != _thread_blocked &&
765 ((reason == _spinning_timeout && cur_state->is_running()) ||
766 (reason == _blocking_timeout && !cur_state->has_called_back()))) {
767 tty->print("# ");
768 cur_thread->print();
769 tty->print_cr("");
770 }
771 }
772 tty->print_cr("# SafepointSynchronize::begin: (End of list)");
773 }
774
775 // To debug the long safepoint, specify both DieOnSafepointTimeout &
776 // ShowMessageBoxOnError.
777 if (DieOnSafepointTimeout) {
778 char msg[1024];
779 VM_Operation *op = VMThread::vm_operation();
780 sprintf(msg, "Safepoint sync time longer than " INTX_FORMAT "ms detected when executing %s.",
781 SafepointTimeoutDelay,
782 op != NULL ? op->name() : "no vm operation");
783 fatal(msg);
784 }
785 }
786
787
788 // -------------------------------------------------------------------------------------------------------
789 // Implementation of ThreadSafepointState
790
791 ThreadSafepointState::ThreadSafepointState(JavaThread *thread) {
792 _thread = thread;
793 _type = _running;
794 _has_called_back = false;
795 _at_poll_safepoint = false;
796 }
797
798 void ThreadSafepointState::create(JavaThread *thread) {
799 ThreadSafepointState *state = new ThreadSafepointState(thread);
800 thread->set_safepoint_state(state);
801 }
802
803 void ThreadSafepointState::destroy(JavaThread *thread) {
804 if (thread->safepoint_state()) {
805 delete(thread->safepoint_state());
806 thread->set_safepoint_state(NULL);
807 }
808 }
809
810 void ThreadSafepointState::examine_state_of_thread() {
811 assert(is_running(), "better be running or just have hit safepoint poll");
812
813 JavaThreadState state = _thread->thread_state();
814
815 // Save the state at the start of safepoint processing.
816 _orig_thread_state = state;
817
818 // Check for a thread that is suspended. Note that thread resume tries
819 // to grab the Threads_lock which we own here, so a thread cannot be
820 // resumed during safepoint synchronization.
821
822 // We check to see if this thread is suspended without locking to
823 // avoid deadlocking with a third thread that is waiting for this
824 // thread to be suspended. The third thread can notice the safepoint
825 // that we're trying to start at the beginning of its SR_lock->wait()
826 // call. If that happens, then the third thread will block on the
827 // safepoint while still holding the underlying SR_lock. We won't be
828 // able to get the SR_lock and we'll deadlock.
829 //
830 // We don't need to grab the SR_lock here for two reasons:
831 // 1) The suspend flags are both volatile and are set with an
832 // Atomic::cmpxchg() call so we should see the suspended
833 // state right away.
834 // 2) We're being called from the safepoint polling loop; if
835 // we don't see the suspended state on this iteration, then
836 // we'll come around again.
837 //
838 bool is_suspended = _thread->is_ext_suspended();
839 if (is_suspended) {
840 roll_forward(_at_safepoint);
841 return;
842 }
843
844 // Some JavaThread states have an initial safepoint state of
845 // running, but are actually at a safepoint. We will happily
846 // agree and update the safepoint state here.
847 if (SafepointSynchronize::safepoint_safe(_thread, state)) {
848 roll_forward(_at_safepoint);
849 return;
850 }
851
852 if (state == _thread_in_vm) {
853 roll_forward(_call_back);
854 return;
855 }
856
857 // All other thread states will continue to run until they
858 // transition and self-block in state _blocked
859 // Safepoint polling in compiled code causes the Java threads to do the same.
860 // Note: new threads may require a malloc so they must be allowed to finish
861
862 assert(is_running(), "examine_state_of_thread on non-running thread");
863 return;
864 }
865
866 // Returns true is thread could not be rolled forward at present position.
867 void ThreadSafepointState::roll_forward(suspend_type type) {
868 _type = type;
869
870 switch(_type) {
871 case _at_safepoint:
872 SafepointSynchronize::signal_thread_at_safepoint();
873 break;
874
875 case _call_back:
876 set_has_called_back(false);
877 break;
878
879 case _running:
880 default:
881 ShouldNotReachHere();
882 }
883 }
884
885 void ThreadSafepointState::restart() {
886 switch(type()) {
887 case _at_safepoint:
888 case _call_back:
889 break;
890
891 case _running:
892 default:
893 tty->print_cr("restart thread "INTPTR_FORMAT" with state %d",
894 _thread, _type);
895 _thread->print();
896 ShouldNotReachHere();
897 }
898 _type = _running;
899 set_has_called_back(false);
900 }
901
902
903 void ThreadSafepointState::print_on(outputStream *st) const {
904 const char *s;
905
906 switch(_type) {
907 case _running : s = "_running"; break;
908 case _at_safepoint : s = "_at_safepoint"; break;
909 case _call_back : s = "_call_back"; break;
910 default:
911 ShouldNotReachHere();
912 }
913
914 st->print_cr("Thread: " INTPTR_FORMAT
915 " [0x%2x] State: %s _has_called_back %d _at_poll_safepoint %d",
916 _thread, _thread->osthread()->thread_id(), s, _has_called_back,
917 _at_poll_safepoint);
918
919 _thread->print_thread_state_on(st);
920 }
921
922
923 // ---------------------------------------------------------------------------------------------------------------------
924
925 // Block the thread at the safepoint poll or poll return.
926 void ThreadSafepointState::handle_polling_page_exception() {
927
928 // Check state. block() will set thread state to thread_in_vm which will
929 // cause the safepoint state _type to become _call_back.
930 assert(type() == ThreadSafepointState::_running,
931 "polling page exception on thread not running state");
932
933 // Step 1: Find the nmethod from the return address
934 if (ShowSafepointMsgs && Verbose) {
935 tty->print_cr("Polling page exception at " INTPTR_FORMAT, thread()->saved_exception_pc());
936 }
937 address real_return_addr = thread()->saved_exception_pc();
938
939 CodeBlob *cb = CodeCache::find_blob(real_return_addr);
940 assert(cb != NULL && cb->is_nmethod(), "return address should be in nmethod");
941 nmethod* nm = (nmethod*)cb;
942
943 // Find frame of caller
944 frame stub_fr = thread()->last_frame();
945 CodeBlob* stub_cb = stub_fr.cb();
946 assert(stub_cb->is_safepoint_stub(), "must be a safepoint stub");
947 RegisterMap map(thread(), true);
948 frame caller_fr = stub_fr.sender(&map);
949
950 // Should only be poll_return or poll
951 assert( nm->is_at_poll_or_poll_return(real_return_addr), "should not be at call" );
952
953 // This is a poll immediately before a return. The exception handling code
954 // has already had the effect of causing the return to occur, so the execution
955 // will continue immediately after the call. In addition, the oopmap at the
956 // return point does not mark the return value as an oop (if it is), so
957 // it needs a handle here to be updated.
958 if( nm->is_at_poll_return(real_return_addr) ) {
959 // See if return type is an oop.
960 bool return_oop = nm->method()->is_returning_oop();
961 Handle return_value;
962 if (return_oop) {
963 // The oop result has been saved on the stack together with all
964 // the other registers. In order to preserve it over GCs we need
965 // to keep it in a handle.
966 oop result = caller_fr.saved_oop_result(&map);
967 assert(result == NULL || result->is_oop(), "must be oop");
968 return_value = Handle(thread(), result);
969 assert(Universe::heap()->is_in_or_null(result), "must be heap pointer");
970 }
971
972 // Block the thread
973 SafepointSynchronize::block(thread());
974
975 // restore oop result, if any
976 if (return_oop) {
977 caller_fr.set_saved_oop_result(&map, return_value());
978 }
979 }
980
981 // This is a safepoint poll. Verify the return address and block.
982 else {
983 set_at_poll_safepoint(true);
984
985 // verify the blob built the "return address" correctly
986 assert(real_return_addr == caller_fr.pc(), "must match");
987
988 // Block the thread
989 SafepointSynchronize::block(thread());
990 set_at_poll_safepoint(false);
991
992 // If we have a pending async exception deoptimize the frame
993 // as otherwise we may never deliver it.
994 if (thread()->has_async_condition()) {
995 ThreadInVMfromJavaNoAsyncException __tiv(thread());
996 VM_DeoptimizeFrame deopt(thread(), caller_fr.id());
997 VMThread::execute(&deopt);
998 }
999
1000 // If an exception has been installed we must check for a pending deoptimization
1001 // Deoptimize frame if exception has been thrown.
1002
1003 if (thread()->has_pending_exception() ) {
1004 RegisterMap map(thread(), true);
1005 frame caller_fr = stub_fr.sender(&map);
1006 if (caller_fr.is_deoptimized_frame()) {
1007 // The exception patch will destroy registers that are still
1008 // live and will be needed during deoptimization. Defer the
1009 // Async exception should have defered the exception until the
1010 // next safepoint which will be detected when we get into
1011 // the interpreter so if we have an exception now things
1012 // are messed up.
1013
1014 fatal("Exception installed and deoptimization is pending");
1015 }
1016 }
1017 }
1018 }
1019
1020
1021 //
1022 // Statistics & Instrumentations
1023 //
1024 SafepointSynchronize::SafepointStats* SafepointSynchronize::_safepoint_stats = NULL;
1025 jlong SafepointSynchronize::_safepoint_begin_time = 0;
1026 int SafepointSynchronize::_cur_stat_index = 0;
1027 julong SafepointSynchronize::_safepoint_reasons[VM_Operation::VMOp_Terminating];
1028 julong SafepointSynchronize::_coalesced_vmop_count = 0;
1029 jlong SafepointSynchronize::_max_sync_time = 0;
1030 jlong SafepointSynchronize::_max_vmop_time = 0;
1031 float SafepointSynchronize::_ts_of_current_safepoint = 0.0f;
1032
1033 static jlong cleanup_end_time = 0;
1034 static bool need_to_track_page_armed_status = false;
1035 static bool init_done = false;
1036
1037 // Helper method to print the header.
1038 static void print_header() {
1039 tty->print(" vmop "
1040 "[threads: total initially_running wait_to_block] ");
1041 tty->print("[time: spin block sync cleanup vmop] ");
1042
1043 // no page armed status printed out if it is always armed.
1044 if (need_to_track_page_armed_status) {
1045 tty->print("page_armed ");
1046 }
1047
1048 tty->print_cr("page_trap_count");
1049 }
1050
1051 void SafepointSynchronize::deferred_initialize_stat() {
1052 if (init_done) return;
1053
1054 if (PrintSafepointStatisticsCount <= 0) {
1055 fatal("Wrong PrintSafepointStatisticsCount");
1056 }
1057
1058 // If PrintSafepointStatisticsTimeout is specified, the statistics data will
1059 // be printed right away, in which case, _safepoint_stats will regress to
1060 // a single element array. Otherwise, it is a circular ring buffer with default
1061 // size of PrintSafepointStatisticsCount.
1062 int stats_array_size;
1063 if (PrintSafepointStatisticsTimeout > 0) {
1064 stats_array_size = 1;
1065 PrintSafepointStatistics = true;
1066 } else {
1067 stats_array_size = PrintSafepointStatisticsCount;
1068 }
1069 _safepoint_stats = (SafepointStats*)os::malloc(stats_array_size
1070 * sizeof(SafepointStats));
1071 guarantee(_safepoint_stats != NULL,
1072 "not enough memory for safepoint instrumentation data");
1073
1074 if (UseCompilerSafepoints && DeferPollingPageLoopCount >= 0) {
1075 need_to_track_page_armed_status = true;
1076 }
1077 init_done = true;
1078 }
1079
1080 void SafepointSynchronize::begin_statistics(int nof_threads, int nof_running) {
1081 assert(init_done, "safepoint statistics array hasn't been initialized");
1082 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
1083
1084 spstat->_time_stamp = _ts_of_current_safepoint;
1085
1086 VM_Operation *op = VMThread::vm_operation();
1087 spstat->_vmop_type = (op != NULL ? op->type() : -1);
1088 if (op != NULL) {
1089 _safepoint_reasons[spstat->_vmop_type]++;
1090 }
1091
1092 spstat->_nof_total_threads = nof_threads;
1093 spstat->_nof_initial_running_threads = nof_running;
1094 spstat->_nof_threads_hit_page_trap = 0;
1095
1096 // Records the start time of spinning. The real time spent on spinning
1097 // will be adjusted when spin is done. Same trick is applied for time
1098 // spent on waiting for threads to block.
1099 if (nof_running != 0) {
1100 spstat->_time_to_spin = os::javaTimeNanos();
1101 } else {
1102 spstat->_time_to_spin = 0;
1103 }
1104 }
1105
1106 void SafepointSynchronize::update_statistics_on_spin_end() {
1107 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
1108
1109 jlong cur_time = os::javaTimeNanos();
1110
1111 spstat->_nof_threads_wait_to_block = _waiting_to_block;
1112 if (spstat->_nof_initial_running_threads != 0) {
1113 spstat->_time_to_spin = cur_time - spstat->_time_to_spin;
1114 }
1115
1116 if (need_to_track_page_armed_status) {
1117 spstat->_page_armed = (PageArmed == 1);
1118 }
1119
1120 // Records the start time of waiting for to block. Updated when block is done.
1121 if (_waiting_to_block != 0) {
1122 spstat->_time_to_wait_to_block = cur_time;
1123 } else {
1124 spstat->_time_to_wait_to_block = 0;
1125 }
1126 }
1127
1128 void SafepointSynchronize::update_statistics_on_sync_end(jlong end_time) {
1129 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
1130
1131 if (spstat->_nof_threads_wait_to_block != 0) {
1132 spstat->_time_to_wait_to_block = end_time -
1133 spstat->_time_to_wait_to_block;
1134 }
1135
1136 // Records the end time of sync which will be used to calculate the total
1137 // vm operation time. Again, the real time spending in syncing will be deducted
1138 // from the start of the sync time later when end_statistics is called.
1139 spstat->_time_to_sync = end_time - _safepoint_begin_time;
1140 if (spstat->_time_to_sync > _max_sync_time) {
1141 _max_sync_time = spstat->_time_to_sync;
1142 }
1143
1144 spstat->_time_to_do_cleanups = end_time;
1145 }
1146
1147 void SafepointSynchronize::update_statistics_on_cleanup_end(jlong end_time) {
1148 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
1149
1150 // Record how long spent in cleanup tasks.
1151 spstat->_time_to_do_cleanups = end_time - spstat->_time_to_do_cleanups;
1152
1153 cleanup_end_time = end_time;
1154 }
1155
1156 void SafepointSynchronize::end_statistics(jlong vmop_end_time) {
1157 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
1158
1159 // Update the vm operation time.
1160 spstat->_time_to_exec_vmop = vmop_end_time - cleanup_end_time;
1161 if (spstat->_time_to_exec_vmop > _max_vmop_time) {
1162 _max_vmop_time = spstat->_time_to_exec_vmop;
1163 }
1164 // Only the sync time longer than the specified
1165 // PrintSafepointStatisticsTimeout will be printed out right away.
1166 // By default, it is -1 meaning all samples will be put into the list.
1167 if ( PrintSafepointStatisticsTimeout > 0) {
1168 if (spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) {
1169 print_statistics();
1170 }
1171 } else {
1172 // The safepoint statistics will be printed out when the _safepoin_stats
1173 // array fills up.
1174 if (_cur_stat_index == PrintSafepointStatisticsCount - 1) {
1175 print_statistics();
1176 _cur_stat_index = 0;
1177 } else {
1178 _cur_stat_index++;
1179 }
1180 }
1181 }
1182
1183 void SafepointSynchronize::print_statistics() {
1184 SafepointStats* sstats = _safepoint_stats;
1185
1186 for (int index = 0; index <= _cur_stat_index; index++) {
1187 if (index % 30 == 0) {
1188 print_header();
1189 }
1190 sstats = &_safepoint_stats[index];
1191 tty->print("%.3f: ", sstats->_time_stamp);
1192 tty->print("%-26s ["
1193 INT32_FORMAT_W(8)INT32_FORMAT_W(11)INT32_FORMAT_W(15)
1194 " ] ",
1195 sstats->_vmop_type == -1 ? "no vm operation" :
1196 VM_Operation::name(sstats->_vmop_type),
1197 sstats->_nof_total_threads,
1198 sstats->_nof_initial_running_threads,
1199 sstats->_nof_threads_wait_to_block);
1200 // "/ MICROUNITS " is to convert the unit from nanos to millis.
1201 tty->print(" ["
1202 INT64_FORMAT_W(6)INT64_FORMAT_W(6)
1203 INT64_FORMAT_W(6)INT64_FORMAT_W(6)
1204 INT64_FORMAT_W(6)" ] ",
1205 sstats->_time_to_spin / MICROUNITS,
1206 sstats->_time_to_wait_to_block / MICROUNITS,
1207 sstats->_time_to_sync / MICROUNITS,
1208 sstats->_time_to_do_cleanups / MICROUNITS,
1209 sstats->_time_to_exec_vmop / MICROUNITS);
1210
1211 if (need_to_track_page_armed_status) {
1212 tty->print(INT32_FORMAT" ", sstats->_page_armed);
1213 }
1214 tty->print_cr(INT32_FORMAT" ", sstats->_nof_threads_hit_page_trap);
1215 }
1216 }
1217
1218 // This method will be called when VM exits. It will first call
1219 // print_statistics to print out the rest of the sampling. Then
1220 // it tries to summarize the sampling.
1221 void SafepointSynchronize::print_stat_on_exit() {
1222 if (_safepoint_stats == NULL) return;
1223
1224 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
1225
1226 // During VM exit, end_statistics may not get called and in that
1227 // case, if the sync time is less than PrintSafepointStatisticsTimeout,
1228 // don't print it out.
1229 // Approximate the vm op time.
1230 _safepoint_stats[_cur_stat_index]._time_to_exec_vmop =
1231 os::javaTimeNanos() - cleanup_end_time;
1232
1233 if ( PrintSafepointStatisticsTimeout < 0 ||
1234 spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) {
1235 print_statistics();
1236 }
1237 tty->print_cr("");
1238
1239 // Print out polling page sampling status.
1240 if (!need_to_track_page_armed_status) {
1241 if (UseCompilerSafepoints) {
1242 tty->print_cr("Polling page always armed");
1243 }
1244 } else {
1245 tty->print_cr("Defer polling page loop count = %d\n",
1246 DeferPollingPageLoopCount);
1247 }
1248
1249 for (int index = 0; index < VM_Operation::VMOp_Terminating; index++) {
1250 if (_safepoint_reasons[index] != 0) {
1251 tty->print_cr("%-26s"UINT64_FORMAT_W(10), VM_Operation::name(index),
1252 _safepoint_reasons[index]);
1253 }
1254 }
1255
1256 tty->print_cr(UINT64_FORMAT_W(5)" VM operations coalesced during safepoint",
1257 _coalesced_vmop_count);
1258 tty->print_cr("Maximum sync time "INT64_FORMAT_W(5)" ms",
1259 _max_sync_time / MICROUNITS);
1260 tty->print_cr("Maximum vm operation time (except for Exit VM operation) "
1261 INT64_FORMAT_W(5)" ms",
1262 _max_vmop_time / MICROUNITS);
1263 }
1264
1265 // ------------------------------------------------------------------------------------------------
1266 // Non-product code
1267
1268 #ifndef PRODUCT
1269
1270 void SafepointSynchronize::print_state() {
1271 if (_state == _not_synchronized) {
1272 tty->print_cr("not synchronized");
1273 } else if (_state == _synchronizing || _state == _synchronized) {
1274 tty->print_cr("State: %s", (_state == _synchronizing) ? "synchronizing" :
1275 "synchronized");
1276
1277 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) {
1278 cur->safepoint_state()->print();
1279 }
1280 }
1281 }
1282
1283 void SafepointSynchronize::safepoint_msg(const char* format, ...) {
1284 if (ShowSafepointMsgs) {
1285 va_list ap;
1286 va_start(ap, format);
1287 tty->vprint_cr(format, ap);
1288 va_end(ap);
1289 }
1290 }
1291
1292 #endif // !PRODUCT