1 /*
2 * Copyright 1997-2009 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25 # include "incls/_precompiled.incl"
26 # include "incls/_safepoint.cpp.incl"
27
28 // --------------------------------------------------------------------------------------------------
29 // Implementation of Safepoint begin/end
30
31 SafepointSynchronize::SynchronizeState volatile SafepointSynchronize::_state = SafepointSynchronize::_not_synchronized;
32 volatile int SafepointSynchronize::_waiting_to_block = 0;
33 jlong SafepointSynchronize::_last_safepoint = 0;
34 volatile int SafepointSynchronize::_safepoint_counter = 0;
35 static volatile int PageArmed = 0 ; // safepoint polling page is RO|RW vs PROT_NONE
36 static volatile int TryingToBlock = 0 ; // proximate value -- for advisory use only
37 static bool timeout_error_printed = false;
38
39 // Roll all threads forward to a safepoint and suspend them all
40 void SafepointSynchronize::begin() {
41
42 Thread* myThread = Thread::current();
43 assert(myThread->is_VM_thread(), "Only VM thread may execute a safepoint");
44
45 _last_safepoint = os::javaTimeNanos();
46
47 #ifndef SERIALGC
48 if (UseConcMarkSweepGC) {
49 // In the future we should investigate whether CMS can use the
50 // more-general mechanism below. DLD (01/05).
51 ConcurrentMarkSweepThread::synchronize(false);
52 } else if (UseG1GC) {
53 ConcurrentGCThread::safepoint_synchronize();
54 }
55 #endif // SERIALGC
56
57 // By getting the Threads_lock, we assure that no threads are about to start or
58 // exit. It is released again in SafepointSynchronize::end().
59 Threads_lock->lock();
60
61 assert( _state == _not_synchronized, "trying to safepoint synchronize with wrong state");
62
63 int nof_threads = Threads::number_of_threads();
64
65 if (TraceSafepoint) {
66 tty->print_cr("Safepoint synchronization initiated. (%d)", nof_threads);
67 }
68
69 RuntimeService::record_safepoint_begin();
70
71 {
72 MutexLocker mu(Safepoint_lock);
73
74 // Set number of threads to wait for, before we initiate the callbacks
75 _waiting_to_block = nof_threads;
76 TryingToBlock = 0 ;
77 int still_running = nof_threads;
78
79 // Save the starting time, so that it can be compared to see if this has taken
80 // too long to complete.
81 jlong safepoint_limit_time;
82 timeout_error_printed = false;
83
84 // Begin the process of bringing the system to a safepoint.
85 // Java threads can be in several different states and are
86 // stopped by different mechanisms:
87 //
88 // 1. Running interpreted
89 // The interpeter dispatch table is changed to force it to
90 // check for a safepoint condition between bytecodes.
91 // 2. Running in native code
92 // When returning from the native code, a Java thread must check
93 // the safepoint _state to see if we must block. If the
94 // VM thread sees a Java thread in native, it does
95 // not wait for this thread to block. The order of the memory
96 // writes and reads of both the safepoint state and the Java
97 // threads state is critical. In order to guarantee that the
98 // memory writes are serialized with respect to each other,
99 // the VM thread issues a memory barrier instruction
100 // (on MP systems). In order to avoid the overhead of issuing
101 // a memory barrier for each Java thread making native calls, each Java
102 // thread performs a write to a single memory page after changing
103 // the thread state. The VM thread performs a sequence of
104 // mprotect OS calls which forces all previous writes from all
105 // Java threads to be serialized. This is done in the
106 // os::serialize_thread_states() call. This has proven to be
107 // much more efficient than executing a membar instruction
108 // on every call to native code.
109 // 3. Running compiled Code
110 // Compiled code reads a global (Safepoint Polling) page that
111 // is set to fault if we are trying to get to a safepoint.
112 // 4. Blocked
113 // A thread which is blocked will not be allowed to return from the
114 // block condition until the safepoint operation is complete.
115 // 5. In VM or Transitioning between states
116 // If a Java thread is currently running in the VM or transitioning
117 // between states, the safepointing code will wait for the thread to
118 // block itself when it attempts transitions to a new state.
119 //
120 _state = _synchronizing;
121 OrderAccess::fence();
122
123 // Flush all thread states to memory
124 if (!UseMembar) {
125 os::serialize_thread_states();
126 }
127
128 // Make interpreter safepoint aware
129 Interpreter::notice_safepoints();
130
131 // PrintSafepointStatisticsTimeout can be specified separately. When
132 // specified, PrintSafepointStatistics will be set to true in
133 // deferred_initialize_stat method. The initialization has to be done
134 // early enough to avoid any races. See bug 6880029 for details.
135 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) {
136 deferred_initialize_stat();
137 }
138
139 if (UseCompilerSafepoints && DeferPollingPageLoopCount < 0) {
140 // Make polling safepoint aware
141 guarantee (PageArmed == 0, "invariant") ;
142 PageArmed = 1 ;
143 os::make_polling_page_unreadable();
144 }
145
146 // Consider using active_processor_count() ... but that call is expensive.
147 int ncpus = os::processor_count() ;
148
149 #ifdef ASSERT
150 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) {
151 assert(cur->safepoint_state()->is_running(), "Illegal initial state");
152 }
153 #endif // ASSERT
154
155 if (SafepointTimeout)
156 safepoint_limit_time = os::javaTimeNanos() + (jlong)SafepointTimeoutDelay * MICROUNITS;
157
158 // Iterate through all threads until it have been determined how to stop them all at a safepoint
159 unsigned int iterations = 0;
160 int steps = 0 ;
161 while(still_running > 0) {
162 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) {
163 assert(!cur->is_ConcurrentGC_thread(), "A concurrent GC thread is unexpectly being suspended");
164 ThreadSafepointState *cur_state = cur->safepoint_state();
165 if (cur_state->is_running()) {
166 cur_state->examine_state_of_thread();
167 if (!cur_state->is_running()) {
168 still_running--;
169 // consider adjusting steps downward:
170 // steps = 0
171 // steps -= NNN
172 // steps >>= 1
173 // steps = MIN(steps, 2000-100)
174 // if (iterations != 0) steps -= NNN
175 }
176 if (TraceSafepoint && Verbose) cur_state->print();
177 }
178 }
179
180 if (PrintSafepointStatistics && iterations == 0) {
181 begin_statistics(nof_threads, still_running);
182 }
183
184 if (still_running > 0) {
185 // Check for if it takes to long
186 if (SafepointTimeout && safepoint_limit_time < os::javaTimeNanos()) {
187 print_safepoint_timeout(_spinning_timeout);
188 }
189
190 // Spin to avoid context switching.
191 // There's a tension between allowing the mutators to run (and rendezvous)
192 // vs spinning. As the VM thread spins, wasting cycles, it consumes CPU that
193 // a mutator might otherwise use profitably to reach a safepoint. Excessive
194 // spinning by the VM thread on a saturated system can increase rendezvous latency.
195 // Blocking or yielding incur their own penalties in the form of context switching
196 // and the resultant loss of $ residency.
197 //
198 // Further complicating matters is that yield() does not work as naively expected
199 // on many platforms -- yield() does not guarantee that any other ready threads
200 // will run. As such we revert yield_all() after some number of iterations.
201 // Yield_all() is implemented as a short unconditional sleep on some platforms.
202 // Typical operating systems round a "short" sleep period up to 10 msecs, so sleeping
203 // can actually increase the time it takes the VM thread to detect that a system-wide
204 // stop-the-world safepoint has been reached. In a pathological scenario such as that
205 // described in CR6415670 the VMthread may sleep just before the mutator(s) become safe.
206 // In that case the mutators will be stalled waiting for the safepoint to complete and the
207 // the VMthread will be sleeping, waiting for the mutators to rendezvous. The VMthread
208 // will eventually wake up and detect that all mutators are safe, at which point
209 // we'll again make progress.
210 //
211 // Beware too that that the VMThread typically runs at elevated priority.
212 // Its default priority is higher than the default mutator priority.
213 // Obviously, this complicates spinning.
214 //
215 // Note too that on Windows XP SwitchThreadTo() has quite different behavior than Sleep(0).
216 // Sleep(0) will _not yield to lower priority threads, while SwitchThreadTo() will.
217 //
218 // See the comments in synchronizer.cpp for additional remarks on spinning.
219 //
220 // In the future we might:
221 // 1. Modify the safepoint scheme to avoid potentally unbounded spinning.
222 // This is tricky as the path used by a thread exiting the JVM (say on
223 // on JNI call-out) simply stores into its state field. The burden
224 // is placed on the VM thread, which must poll (spin).
225 // 2. Find something useful to do while spinning. If the safepoint is GC-related
226 // we might aggressively scan the stacks of threads that are already safe.
227 // 3. Use Solaris schedctl to examine the state of the still-running mutators.
228 // If all the mutators are ONPROC there's no reason to sleep or yield.
229 // 4. YieldTo() any still-running mutators that are ready but OFFPROC.
230 // 5. Check system saturation. If the system is not fully saturated then
231 // simply spin and avoid sleep/yield.
232 // 6. As still-running mutators rendezvous they could unpark the sleeping
233 // VMthread. This works well for still-running mutators that become
234 // safe. The VMthread must still poll for mutators that call-out.
235 // 7. Drive the policy on time-since-begin instead of iterations.
236 // 8. Consider making the spin duration a function of the # of CPUs:
237 // Spin = (((ncpus-1) * M) + K) + F(still_running)
238 // Alternately, instead of counting iterations of the outer loop
239 // we could count the # of threads visited in the inner loop, above.
240 // 9. On windows consider using the return value from SwitchThreadTo()
241 // to drive subsequent spin/SwitchThreadTo()/Sleep(N) decisions.
242
243 if (UseCompilerSafepoints && int(iterations) == DeferPollingPageLoopCount) {
244 guarantee (PageArmed == 0, "invariant") ;
245 PageArmed = 1 ;
246 os::make_polling_page_unreadable();
247 }
248
249 // Instead of (ncpus > 1) consider either (still_running < (ncpus + EPSILON)) or
250 // ((still_running + _waiting_to_block - TryingToBlock)) < ncpus)
251 ++steps ;
252 if (ncpus > 1 && steps < SafepointSpinBeforeYield) {
253 SpinPause() ; // MP-Polite spin
254 } else
255 if (steps < DeferThrSuspendLoopCount) {
256 os::NakedYield() ;
257 } else {
258 os::yield_all(steps) ;
259 // Alternately, the VM thread could transiently depress its scheduling priority or
260 // transiently increase the priority of the tardy mutator(s).
261 }
262
263 iterations ++ ;
264 }
265 assert(iterations < (uint)max_jint, "We have been iterating in the safepoint loop too long");
266 }
267 assert(still_running == 0, "sanity check");
268
269 if (PrintSafepointStatistics) {
270 update_statistics_on_spin_end();
271 }
272
273 // wait until all threads are stopped
274 while (_waiting_to_block > 0) {
275 if (TraceSafepoint) tty->print_cr("Waiting for %d thread(s) to block", _waiting_to_block);
276 if (!SafepointTimeout || timeout_error_printed) {
277 Safepoint_lock->wait(true); // true, means with no safepoint checks
278 } else {
279 // Compute remaining time
280 jlong remaining_time = safepoint_limit_time - os::javaTimeNanos();
281
282 // If there is no remaining time, then there is an error
283 if (remaining_time < 0 || Safepoint_lock->wait(true, remaining_time / MICROUNITS)) {
284 print_safepoint_timeout(_blocking_timeout);
285 }
286 }
287 }
288 assert(_waiting_to_block == 0, "sanity check");
289
290 #ifndef PRODUCT
291 if (SafepointTimeout) {
292 jlong current_time = os::javaTimeNanos();
293 if (safepoint_limit_time < current_time) {
294 tty->print_cr("# SafepointSynchronize: Finished after "
295 INT64_FORMAT_W(6) " ms",
296 ((current_time - safepoint_limit_time) / MICROUNITS +
297 SafepointTimeoutDelay));
298 }
299 }
300 #endif
301
302 assert((_safepoint_counter & 0x1) == 0, "must be even");
303 assert(Threads_lock->owned_by_self(), "must hold Threads_lock");
304 _safepoint_counter ++;
305
306 // Record state
307 _state = _synchronized;
308
309 OrderAccess::fence();
310
311 if (TraceSafepoint) {
312 VM_Operation *op = VMThread::vm_operation();
313 tty->print_cr("Entering safepoint region: %s", (op != NULL) ? op->name() : "no vm operation");
314 }
315
316 RuntimeService::record_safepoint_synchronized();
317 if (PrintSafepointStatistics) {
318 update_statistics_on_sync_end(os::javaTimeNanos());
319 }
320
321 // Call stuff that needs to be run when a safepoint is just about to be completed
322 do_cleanup_tasks();
323 }
324 }
325
326 // Wake up all threads, so they are ready to resume execution after the safepoint
327 // operation has been carried out
328 void SafepointSynchronize::end() {
329
330 assert(Threads_lock->owned_by_self(), "must hold Threads_lock");
331 assert((_safepoint_counter & 0x1) == 1, "must be odd");
332 _safepoint_counter ++;
333 // memory fence isn't required here since an odd _safepoint_counter
334 // value can do no harm and a fence is issued below anyway.
335
336 DEBUG_ONLY(Thread* myThread = Thread::current();)
337 assert(myThread->is_VM_thread(), "Only VM thread can execute a safepoint");
338
339 if (PrintSafepointStatistics) {
340 end_statistics(os::javaTimeNanos());
341 }
342
343 #ifdef ASSERT
344 // A pending_exception cannot be installed during a safepoint. The threads
345 // may install an async exception after they come back from a safepoint into
346 // pending_exception after they unblock. But that should happen later.
347 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) {
348 assert (!(cur->has_pending_exception() &&
349 cur->safepoint_state()->is_at_poll_safepoint()),
350 "safepoint installed a pending exception");
351 }
352 #endif // ASSERT
353
354 if (PageArmed) {
355 // Make polling safepoint aware
356 os::make_polling_page_readable();
357 PageArmed = 0 ;
358 }
359
360 // Remove safepoint check from interpreter
361 Interpreter::ignore_safepoints();
362
363 {
364 MutexLocker mu(Safepoint_lock);
365
366 assert(_state == _synchronized, "must be synchronized before ending safepoint synchronization");
367
368 // Set to not synchronized, so the threads will not go into the signal_thread_blocked method
369 // when they get restarted.
370 _state = _not_synchronized;
371 OrderAccess::fence();
372
373 if (TraceSafepoint) {
374 tty->print_cr("Leaving safepoint region");
375 }
376
377 // Start suspended threads
378 for(JavaThread *current = Threads::first(); current; current = current->next()) {
379 // A problem occurring on Solaris is when attempting to restart threads
380 // the first #cpus - 1 go well, but then the VMThread is preempted when we get
381 // to the next one (since it has been running the longest). We then have
382 // to wait for a cpu to become available before we can continue restarting
383 // threads.
384 // FIXME: This causes the performance of the VM to degrade when active and with
385 // large numbers of threads. Apparently this is due to the synchronous nature
386 // of suspending threads.
387 //
388 // TODO-FIXME: the comments above are vestigial and no longer apply.
389 // Furthermore, using solaris' schedctl in this particular context confers no benefit
390 if (VMThreadHintNoPreempt) {
391 os::hint_no_preempt();
392 }
393 ThreadSafepointState* cur_state = current->safepoint_state();
394 assert(cur_state->type() != ThreadSafepointState::_running, "Thread not suspended at safepoint");
395 cur_state->restart();
396 assert(cur_state->is_running(), "safepoint state has not been reset");
397 }
398
399 RuntimeService::record_safepoint_end();
400
401 // Release threads lock, so threads can be created/destroyed again. It will also starts all threads
402 // blocked in signal_thread_blocked
403 Threads_lock->unlock();
404
405 }
406 #ifndef SERIALGC
407 // If there are any concurrent GC threads resume them.
408 if (UseConcMarkSweepGC) {
409 ConcurrentMarkSweepThread::desynchronize(false);
410 } else if (UseG1GC) {
411 ConcurrentGCThread::safepoint_desynchronize();
412 }
413 #endif // SERIALGC
414 }
415
416 bool SafepointSynchronize::is_cleanup_needed() {
417 // Need a safepoint if some inline cache buffers is non-empty
418 if (!InlineCacheBuffer::is_empty()) return true;
419 return false;
420 }
421
422 jlong CounterDecay::_last_timestamp = 0;
423
424 static void do_method(methodOop m) {
425 m->invocation_counter()->decay();
426 }
427
428 void CounterDecay::decay() {
429 _last_timestamp = os::javaTimeMillis();
430
431 // This operation is going to be performed only at the end of a safepoint
432 // and hence GC's will not be going on, all Java mutators are suspended
433 // at this point and hence SystemDictionary_lock is also not needed.
434 assert(SafepointSynchronize::is_at_safepoint(), "can only be executed at a safepoint");
435 int nclasses = SystemDictionary::number_of_classes();
436 double classes_per_tick = nclasses * (CounterDecayMinIntervalLength * 1e-3 /
437 CounterHalfLifeTime);
438 for (int i = 0; i < classes_per_tick; i++) {
439 klassOop k = SystemDictionary::try_get_next_class();
440 if (k != NULL && k->klass_part()->oop_is_instance()) {
441 instanceKlass::cast(k)->methods_do(do_method);
442 }
443 }
444 }
445
446 // Various cleaning tasks that should be done periodically at safepoints
447 void SafepointSynchronize::do_cleanup_tasks() {
448 jlong cleanup_time;
449
450 // Update fat-monitor pool, since this is a safepoint.
451 if (TraceSafepoint) {
452 cleanup_time = os::javaTimeNanos();
453 }
454
455 ObjectSynchronizer::deflate_idle_monitors();
456 InlineCacheBuffer::update_inline_caches();
457 if(UseCounterDecay && CounterDecay::is_decay_needed()) {
458 CounterDecay::decay();
459 }
460 NMethodSweeper::sweep();
461
462 if (TraceSafepoint) {
463 tty->print_cr("do_cleanup_tasks takes "INT64_FORMAT_W(6) "ms",
464 (os::javaTimeNanos() - cleanup_time) / MICROUNITS);
465 }
466 }
467
468
469 bool SafepointSynchronize::safepoint_safe(JavaThread *thread, JavaThreadState state) {
470 switch(state) {
471 case _thread_in_native:
472 // native threads are safe if they have no java stack or have walkable stack
473 return !thread->has_last_Java_frame() || thread->frame_anchor()->walkable();
474
475 // blocked threads should have already have walkable stack
476 case _thread_blocked:
477 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "blocked and not walkable");
478 return true;
479
480 default:
481 return false;
482 }
483 }
484
485
486 // -------------------------------------------------------------------------------------------------------
487 // Implementation of Safepoint callback point
488
489 void SafepointSynchronize::block(JavaThread *thread) {
490 assert(thread != NULL, "thread must be set");
491 assert(thread->is_Java_thread(), "not a Java thread");
492
493 // Threads shouldn't block if they are in the middle of printing, but...
494 ttyLocker::break_tty_lock_for_safepoint(os::current_thread_id());
495
496 // Only bail from the block() call if the thread is gone from the
497 // thread list; starting to exit should still block.
498 if (thread->is_terminated()) {
499 // block current thread if we come here from native code when VM is gone
500 thread->block_if_vm_exited();
501
502 // otherwise do nothing
503 return;
504 }
505
506 JavaThreadState state = thread->thread_state();
507 thread->frame_anchor()->make_walkable(thread);
508
509 // Check that we have a valid thread_state at this point
510 switch(state) {
511 case _thread_in_vm_trans:
512 case _thread_in_Java: // From compiled code
513
514 // We are highly likely to block on the Safepoint_lock. In order to avoid blocking in this case,
515 // we pretend we are still in the VM.
516 thread->set_thread_state(_thread_in_vm);
517
518 if (is_synchronizing()) {
519 Atomic::inc (&TryingToBlock) ;
520 }
521
522 // We will always be holding the Safepoint_lock when we are examine the state
523 // of a thread. Hence, the instructions between the Safepoint_lock->lock() and
524 // Safepoint_lock->unlock() are happening atomic with regards to the safepoint code
525 Safepoint_lock->lock_without_safepoint_check();
526 if (is_synchronizing()) {
527 // Decrement the number of threads to wait for and signal vm thread
528 assert(_waiting_to_block > 0, "sanity check");
529 _waiting_to_block--;
530 thread->safepoint_state()->set_has_called_back(true);
531
532 // Consider (_waiting_to_block < 2) to pipeline the wakeup of the VM thread
533 if (_waiting_to_block == 0) {
534 Safepoint_lock->notify_all();
535 }
536 }
537
538 // We transition the thread to state _thread_blocked here, but
539 // we can't do our usual check for external suspension and then
540 // self-suspend after the lock_without_safepoint_check() call
541 // below because we are often called during transitions while
542 // we hold different locks. That would leave us suspended while
543 // holding a resource which results in deadlocks.
544 thread->set_thread_state(_thread_blocked);
545 Safepoint_lock->unlock();
546
547 // We now try to acquire the threads lock. Since this lock is hold by the VM thread during
548 // the entire safepoint, the threads will all line up here during the safepoint.
549 Threads_lock->lock_without_safepoint_check();
550 // restore original state. This is important if the thread comes from compiled code, so it
551 // will continue to execute with the _thread_in_Java state.
552 thread->set_thread_state(state);
553 Threads_lock->unlock();
554 break;
555
556 case _thread_in_native_trans:
557 case _thread_blocked_trans:
558 case _thread_new_trans:
559 if (thread->safepoint_state()->type() == ThreadSafepointState::_call_back) {
560 thread->print_thread_state();
561 fatal("Deadlock in safepoint code. "
562 "Should have called back to the VM before blocking.");
563 }
564
565 // We transition the thread to state _thread_blocked here, but
566 // we can't do our usual check for external suspension and then
567 // self-suspend after the lock_without_safepoint_check() call
568 // below because we are often called during transitions while
569 // we hold different locks. That would leave us suspended while
570 // holding a resource which results in deadlocks.
571 thread->set_thread_state(_thread_blocked);
572
573 // It is not safe to suspend a thread if we discover it is in _thread_in_native_trans. Hence,
574 // the safepoint code might still be waiting for it to block. We need to change the state here,
575 // so it can see that it is at a safepoint.
576
577 // Block until the safepoint operation is completed.
578 Threads_lock->lock_without_safepoint_check();
579
580 // Restore state
581 thread->set_thread_state(state);
582
583 Threads_lock->unlock();
584 break;
585
586 default:
587 fatal1("Illegal threadstate encountered: %d", state);
588 }
589
590 // Check for pending. async. exceptions or suspends - except if the
591 // thread was blocked inside the VM. has_special_runtime_exit_condition()
592 // is called last since it grabs a lock and we only want to do that when
593 // we must.
594 //
595 // Note: we never deliver an async exception at a polling point as the
596 // compiler may not have an exception handler for it. The polling
597 // code will notice the async and deoptimize and the exception will
598 // be delivered. (Polling at a return point is ok though). Sure is
599 // a lot of bother for a deprecated feature...
600 //
601 // We don't deliver an async exception if the thread state is
602 // _thread_in_native_trans so JNI functions won't be called with
603 // a surprising pending exception. If the thread state is going back to java,
604 // async exception is checked in check_special_condition_for_native_trans().
605
606 if (state != _thread_blocked_trans &&
607 state != _thread_in_vm_trans &&
608 thread->has_special_runtime_exit_condition()) {
609 thread->handle_special_runtime_exit_condition(
610 !thread->is_at_poll_safepoint() && (state != _thread_in_native_trans));
611 }
612 }
613
614 // ------------------------------------------------------------------------------------------------------
615 // Exception handlers
616
617 #ifndef PRODUCT
618 #ifdef _LP64
619 #define PTR_PAD ""
620 #else
621 #define PTR_PAD " "
622 #endif
623
624 static void print_ptrs(intptr_t oldptr, intptr_t newptr, bool wasoop) {
625 bool is_oop = newptr ? ((oop)newptr)->is_oop() : false;
626 tty->print_cr(PTR_FORMAT PTR_PAD " %s %c " PTR_FORMAT PTR_PAD " %s %s",
627 oldptr, wasoop?"oop":" ", oldptr == newptr ? ' ' : '!',
628 newptr, is_oop?"oop":" ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":" "));
629 }
630
631 static void print_longs(jlong oldptr, jlong newptr, bool wasoop) {
632 bool is_oop = newptr ? ((oop)(intptr_t)newptr)->is_oop() : false;
633 tty->print_cr(PTR64_FORMAT " %s %c " PTR64_FORMAT " %s %s",
634 oldptr, wasoop?"oop":" ", oldptr == newptr ? ' ' : '!',
635 newptr, is_oop?"oop":" ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":" "));
636 }
637
638 #ifdef SPARC
639 static void print_me(intptr_t *new_sp, intptr_t *old_sp, bool *was_oops) {
640 #ifdef _LP64
641 tty->print_cr("--------+------address-----+------before-----------+-------after----------+");
642 const int incr = 1; // Increment to skip a long, in units of intptr_t
643 #else
644 tty->print_cr("--------+--address-+------before-----------+-------after----------+");
645 const int incr = 2; // Increment to skip a long, in units of intptr_t
646 #endif
647 tty->print_cr("---SP---|");
648 for( int i=0; i<16; i++ ) {
649 tty->print("blob %c%d |"PTR_FORMAT" ","LO"[i>>3],i&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); }
650 tty->print_cr("--------|");
651 for( int i1=0; i1<frame::memory_parameter_word_sp_offset-16; i1++ ) {
652 tty->print("argv pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); }
653 tty->print(" pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++);
654 tty->print_cr("--------|");
655 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;
656 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;
657 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;
658 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;
659 tty->print_cr(" FSR |"PTR_FORMAT" "PTR64_FORMAT" "PTR64_FORMAT,new_sp,*(jlong*)old_sp,*(jlong*)new_sp);
660 old_sp += incr; new_sp += incr; was_oops += incr;
661 // Skip the floats
662 tty->print_cr("--Float-|"PTR_FORMAT,new_sp);
663 tty->print_cr("---FP---|");
664 old_sp += incr*32; new_sp += incr*32; was_oops += incr*32;
665 for( int i2=0; i2<16; i2++ ) {
666 tty->print("call %c%d |"PTR_FORMAT" ","LI"[i2>>3],i2&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); }
667 tty->print_cr("");
668 }
669 #endif // SPARC
670 #endif // PRODUCT
671
672
673 void SafepointSynchronize::handle_polling_page_exception(JavaThread *thread) {
674 assert(thread->is_Java_thread(), "polling reference encountered by VM thread");
675 assert(thread->thread_state() == _thread_in_Java, "should come from Java code");
676 assert(SafepointSynchronize::is_synchronizing(), "polling encountered outside safepoint synchronization");
677
678 // Uncomment this to get some serious before/after printing of the
679 // Sparc safepoint-blob frame structure.
680 /*
681 intptr_t* sp = thread->last_Java_sp();
682 intptr_t stack_copy[150];
683 for( int i=0; i<150; i++ ) stack_copy[i] = sp[i];
684 bool was_oops[150];
685 for( int i=0; i<150; i++ )
686 was_oops[i] = stack_copy[i] ? ((oop)stack_copy[i])->is_oop() : false;
687 */
688
689 if (ShowSafepointMsgs) {
690 tty->print("handle_polling_page_exception: ");
691 }
692
693 if (PrintSafepointStatistics) {
694 inc_page_trap_count();
695 }
696
697 ThreadSafepointState* state = thread->safepoint_state();
698
699 state->handle_polling_page_exception();
700 // print_me(sp,stack_copy,was_oops);
701 }
702
703
704 void SafepointSynchronize::print_safepoint_timeout(SafepointTimeoutReason reason) {
705 if (!timeout_error_printed) {
706 timeout_error_printed = true;
707 // Print out the thread infor which didn't reach the safepoint for debugging
708 // purposes (useful when there are lots of threads in the debugger).
709 tty->print_cr("");
710 tty->print_cr("# SafepointSynchronize::begin: Timeout detected:");
711 if (reason == _spinning_timeout) {
712 tty->print_cr("# SafepointSynchronize::begin: Timed out while spinning to reach a safepoint.");
713 } else if (reason == _blocking_timeout) {
714 tty->print_cr("# SafepointSynchronize::begin: Timed out while waiting for threads to stop.");
715 }
716
717 tty->print_cr("# SafepointSynchronize::begin: Threads which did not reach the safepoint:");
718 ThreadSafepointState *cur_state;
719 ResourceMark rm;
720 for(JavaThread *cur_thread = Threads::first(); cur_thread;
721 cur_thread = cur_thread->next()) {
722 cur_state = cur_thread->safepoint_state();
723
724 if (cur_thread->thread_state() != _thread_blocked &&
725 ((reason == _spinning_timeout && cur_state->is_running()) ||
726 (reason == _blocking_timeout && !cur_state->has_called_back()))) {
727 tty->print("# ");
728 cur_thread->print();
729 tty->print_cr("");
730 }
731 }
732 tty->print_cr("# SafepointSynchronize::begin: (End of list)");
733 }
734
735 // To debug the long safepoint, specify both DieOnSafepointTimeout &
736 // ShowMessageBoxOnError.
737 if (DieOnSafepointTimeout) {
738 char msg[1024];
739 VM_Operation *op = VMThread::vm_operation();
740 sprintf(msg, "Safepoint sync time longer than " INTX_FORMAT "ms detected when executing %s.",
741 SafepointTimeoutDelay,
742 op != NULL ? op->name() : "no vm operation");
743 fatal(msg);
744 }
745 }
746
747
748 // -------------------------------------------------------------------------------------------------------
749 // Implementation of ThreadSafepointState
750
751 ThreadSafepointState::ThreadSafepointState(JavaThread *thread) {
752 _thread = thread;
753 _type = _running;
754 _has_called_back = false;
755 _at_poll_safepoint = false;
756 }
757
758 void ThreadSafepointState::create(JavaThread *thread) {
759 ThreadSafepointState *state = new ThreadSafepointState(thread);
760 thread->set_safepoint_state(state);
761 }
762
763 void ThreadSafepointState::destroy(JavaThread *thread) {
764 if (thread->safepoint_state()) {
765 delete(thread->safepoint_state());
766 thread->set_safepoint_state(NULL);
767 }
768 }
769
770 void ThreadSafepointState::examine_state_of_thread() {
771 assert(is_running(), "better be running or just have hit safepoint poll");
772
773 JavaThreadState state = _thread->thread_state();
774
775 // Check for a thread that is suspended. Note that thread resume tries
776 // to grab the Threads_lock which we own here, so a thread cannot be
777 // resumed during safepoint synchronization.
778
779 // We check to see if this thread is suspended without locking to
780 // avoid deadlocking with a third thread that is waiting for this
781 // thread to be suspended. The third thread can notice the safepoint
782 // that we're trying to start at the beginning of its SR_lock->wait()
783 // call. If that happens, then the third thread will block on the
784 // safepoint while still holding the underlying SR_lock. We won't be
785 // able to get the SR_lock and we'll deadlock.
786 //
787 // We don't need to grab the SR_lock here for two reasons:
788 // 1) The suspend flags are both volatile and are set with an
789 // Atomic::cmpxchg() call so we should see the suspended
790 // state right away.
791 // 2) We're being called from the safepoint polling loop; if
792 // we don't see the suspended state on this iteration, then
793 // we'll come around again.
794 //
795 bool is_suspended = _thread->is_ext_suspended();
796 if (is_suspended) {
797 roll_forward(_at_safepoint);
798 return;
799 }
800
801 // Some JavaThread states have an initial safepoint state of
802 // running, but are actually at a safepoint. We will happily
803 // agree and update the safepoint state here.
804 if (SafepointSynchronize::safepoint_safe(_thread, state)) {
805 roll_forward(_at_safepoint);
806 return;
807 }
808
809 if (state == _thread_in_vm) {
810 roll_forward(_call_back);
811 return;
812 }
813
814 // All other thread states will continue to run until they
815 // transition and self-block in state _blocked
816 // Safepoint polling in compiled code causes the Java threads to do the same.
817 // Note: new threads may require a malloc so they must be allowed to finish
818
819 assert(is_running(), "examine_state_of_thread on non-running thread");
820 return;
821 }
822
823 // Returns true is thread could not be rolled forward at present position.
824 void ThreadSafepointState::roll_forward(suspend_type type) {
825 _type = type;
826
827 switch(_type) {
828 case _at_safepoint:
829 SafepointSynchronize::signal_thread_at_safepoint();
830 break;
831
832 case _call_back:
833 set_has_called_back(false);
834 break;
835
836 case _running:
837 default:
838 ShouldNotReachHere();
839 }
840 }
841
842 void ThreadSafepointState::restart() {
843 switch(type()) {
844 case _at_safepoint:
845 case _call_back:
846 break;
847
848 case _running:
849 default:
850 tty->print_cr("restart thread "INTPTR_FORMAT" with state %d",
851 _thread, _type);
852 _thread->print();
853 ShouldNotReachHere();
854 }
855 _type = _running;
856 set_has_called_back(false);
857 }
858
859
860 void ThreadSafepointState::print_on(outputStream *st) const {
861 const char *s;
862
863 switch(_type) {
864 case _running : s = "_running"; break;
865 case _at_safepoint : s = "_at_safepoint"; break;
866 case _call_back : s = "_call_back"; break;
867 default:
868 ShouldNotReachHere();
869 }
870
871 st->print_cr("Thread: " INTPTR_FORMAT
872 " [0x%2x] State: %s _has_called_back %d _at_poll_safepoint %d",
873 _thread, _thread->osthread()->thread_id(), s, _has_called_back,
874 _at_poll_safepoint);
875
876 _thread->print_thread_state_on(st);
877 }
878
879
880 // ---------------------------------------------------------------------------------------------------------------------
881
882 // Block the thread at the safepoint poll or poll return.
883 void ThreadSafepointState::handle_polling_page_exception() {
884
885 // Check state. block() will set thread state to thread_in_vm which will
886 // cause the safepoint state _type to become _call_back.
887 assert(type() == ThreadSafepointState::_running,
888 "polling page exception on thread not running state");
889
890 // Step 1: Find the nmethod from the return address
891 if (ShowSafepointMsgs && Verbose) {
892 tty->print_cr("Polling page exception at " INTPTR_FORMAT, thread()->saved_exception_pc());
893 }
894 address real_return_addr = thread()->saved_exception_pc();
895
896 CodeBlob *cb = CodeCache::find_blob(real_return_addr);
897 assert(cb != NULL && cb->is_nmethod(), "return address should be in nmethod");
898 nmethod* nm = (nmethod*)cb;
899
900 // Find frame of caller
901 frame stub_fr = thread()->last_frame();
902 CodeBlob* stub_cb = stub_fr.cb();
903 assert(stub_cb->is_safepoint_stub(), "must be a safepoint stub");
904 RegisterMap map(thread(), true);
905 frame caller_fr = stub_fr.sender(&map);
906
907 // Should only be poll_return or poll
908 assert( nm->is_at_poll_or_poll_return(real_return_addr), "should not be at call" );
909
910 // This is a poll immediately before a return. The exception handling code
911 // has already had the effect of causing the return to occur, so the execution
912 // will continue immediately after the call. In addition, the oopmap at the
913 // return point does not mark the return value as an oop (if it is), so
914 // it needs a handle here to be updated.
915 if( nm->is_at_poll_return(real_return_addr) ) {
916 // See if return type is an oop.
917 bool return_oop = nm->method()->is_returning_oop();
918 Handle return_value;
919 if (return_oop) {
920 // The oop result has been saved on the stack together with all
921 // the other registers. In order to preserve it over GCs we need
922 // to keep it in a handle.
923 oop result = caller_fr.saved_oop_result(&map);
924 assert(result == NULL || result->is_oop(), "must be oop");
925 return_value = Handle(thread(), result);
926 assert(Universe::heap()->is_in_or_null(result), "must be heap pointer");
927 }
928
929 // Block the thread
930 SafepointSynchronize::block(thread());
931
932 // restore oop result, if any
933 if (return_oop) {
934 caller_fr.set_saved_oop_result(&map, return_value());
935 }
936 }
937
938 // This is a safepoint poll. Verify the return address and block.
939 else {
940 set_at_poll_safepoint(true);
941
942 // verify the blob built the "return address" correctly
943 assert(real_return_addr == caller_fr.pc(), "must match");
944
945 // Block the thread
946 SafepointSynchronize::block(thread());
947 set_at_poll_safepoint(false);
948
949 // If we have a pending async exception deoptimize the frame
950 // as otherwise we may never deliver it.
951 if (thread()->has_async_condition()) {
952 ThreadInVMfromJavaNoAsyncException __tiv(thread());
953 VM_DeoptimizeFrame deopt(thread(), caller_fr.id());
954 VMThread::execute(&deopt);
955 }
956
957 // If an exception has been installed we must check for a pending deoptimization
958 // Deoptimize frame if exception has been thrown.
959
960 if (thread()->has_pending_exception() ) {
961 RegisterMap map(thread(), true);
962 frame caller_fr = stub_fr.sender(&map);
963 if (caller_fr.is_deoptimized_frame()) {
964 // The exception patch will destroy registers that are still
965 // live and will be needed during deoptimization. Defer the
966 // Async exception should have defered the exception until the
967 // next safepoint which will be detected when we get into
968 // the interpreter so if we have an exception now things
969 // are messed up.
970
971 fatal("Exception installed and deoptimization is pending");
972 }
973 }
974 }
975 }
976
977
978 //
979 // Statistics & Instrumentations
980 //
981 SafepointSynchronize::SafepointStats* SafepointSynchronize::_safepoint_stats = NULL;
982 int SafepointSynchronize::_cur_stat_index = 0;
983 julong SafepointSynchronize::_safepoint_reasons[VM_Operation::VMOp_Terminating];
984 julong SafepointSynchronize::_coalesced_vmop_count = 0;
985 jlong SafepointSynchronize::_max_sync_time = 0;
986
987 // last_safepoint_start_time records the start time of last safepoint.
988 static jlong last_safepoint_start_time = 0;
989 static jlong sync_end_time = 0;
990 static bool need_to_track_page_armed_status = false;
991 static bool init_done = false;
992
993 void SafepointSynchronize::deferred_initialize_stat() {
994 if (init_done) return;
995
996 if (PrintSafepointStatisticsCount <= 0) {
997 fatal("Wrong PrintSafepointStatisticsCount");
998 }
999
1000 // If PrintSafepointStatisticsTimeout is specified, the statistics data will
1001 // be printed right away, in which case, _safepoint_stats will regress to
1002 // a single element array. Otherwise, it is a circular ring buffer with default
1003 // size of PrintSafepointStatisticsCount.
1004 int stats_array_size;
1005 if (PrintSafepointStatisticsTimeout > 0) {
1006 stats_array_size = 1;
1007 PrintSafepointStatistics = true;
1008 } else {
1009 stats_array_size = PrintSafepointStatisticsCount;
1010 }
1011 _safepoint_stats = (SafepointStats*)os::malloc(stats_array_size
1012 * sizeof(SafepointStats));
1013 guarantee(_safepoint_stats != NULL,
1014 "not enough memory for safepoint instrumentation data");
1015
1016 if (UseCompilerSafepoints && DeferPollingPageLoopCount >= 0) {
1017 need_to_track_page_armed_status = true;
1018 }
1019
1020 tty->print(" vmop_name "
1021 "[threads: total initially_running wait_to_block] ");
1022 tty->print("[time: spin block sync] "
1023 "[vmop_time time_elapsed] ");
1024
1025 // no page armed status printed out if it is always armed.
1026 if (need_to_track_page_armed_status) {
1027 tty->print("page_armed ");
1028 }
1029
1030 tty->print_cr("page_trap_count");
1031
1032 init_done = true;
1033 }
1034
1035 void SafepointSynchronize::begin_statistics(int nof_threads, int nof_running) {
1036 assert(init_done, "safepoint statistics array hasn't been initialized");
1037 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
1038
1039 VM_Operation *op = VMThread::vm_operation();
1040 spstat->_vmop_type = (op != NULL ? op->type() : -1);
1041 if (op != NULL) {
1042 _safepoint_reasons[spstat->_vmop_type]++;
1043 }
1044
1045 spstat->_nof_total_threads = nof_threads;
1046 spstat->_nof_initial_running_threads = nof_running;
1047 spstat->_nof_threads_hit_page_trap = 0;
1048
1049 // Records the start time of spinning. The real time spent on spinning
1050 // will be adjusted when spin is done. Same trick is applied for time
1051 // spent on waiting for threads to block.
1052 if (nof_running != 0) {
1053 spstat->_time_to_spin = os::javaTimeNanos();
1054 } else {
1055 spstat->_time_to_spin = 0;
1056 }
1057
1058 if (last_safepoint_start_time == 0) {
1059 spstat->_time_elapsed_since_last_safepoint = 0;
1060 } else {
1061 spstat->_time_elapsed_since_last_safepoint = _last_safepoint -
1062 last_safepoint_start_time;
1063 }
1064 last_safepoint_start_time = _last_safepoint;
1065 }
1066
1067 void SafepointSynchronize::update_statistics_on_spin_end() {
1068 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
1069
1070 jlong cur_time = os::javaTimeNanos();
1071
1072 spstat->_nof_threads_wait_to_block = _waiting_to_block;
1073 if (spstat->_nof_initial_running_threads != 0) {
1074 spstat->_time_to_spin = cur_time - spstat->_time_to_spin;
1075 }
1076
1077 if (need_to_track_page_armed_status) {
1078 spstat->_page_armed = (PageArmed == 1);
1079 }
1080
1081 // Records the start time of waiting for to block. Updated when block is done.
1082 if (_waiting_to_block != 0) {
1083 spstat->_time_to_wait_to_block = cur_time;
1084 } else {
1085 spstat->_time_to_wait_to_block = 0;
1086 }
1087 }
1088
1089 void SafepointSynchronize::update_statistics_on_sync_end(jlong end_time) {
1090 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
1091
1092 if (spstat->_nof_threads_wait_to_block != 0) {
1093 spstat->_time_to_wait_to_block = end_time -
1094 spstat->_time_to_wait_to_block;
1095 }
1096
1097 // Records the end time of sync which will be used to calculate the total
1098 // vm operation time. Again, the real time spending in syncing will be deducted
1099 // from the start of the sync time later when end_statistics is called.
1100 spstat->_time_to_sync = end_time - _last_safepoint;
1101 if (spstat->_time_to_sync > _max_sync_time) {
1102 _max_sync_time = spstat->_time_to_sync;
1103 }
1104 sync_end_time = end_time;
1105 }
1106
1107 void SafepointSynchronize::end_statistics(jlong vmop_end_time) {
1108 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
1109
1110 // Update the vm operation time.
1111 spstat->_time_to_exec_vmop = vmop_end_time - sync_end_time;
1112 // Only the sync time longer than the specified
1113 // PrintSafepointStatisticsTimeout will be printed out right away.
1114 // By default, it is -1 meaning all samples will be put into the list.
1115 if ( PrintSafepointStatisticsTimeout > 0) {
1116 if (spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) {
1117 print_statistics();
1118 }
1119 } else {
1120 // The safepoint statistics will be printed out when the _safepoin_stats
1121 // array fills up.
1122 if (_cur_stat_index != PrintSafepointStatisticsCount - 1) {
1123 _cur_stat_index ++;
1124 } else {
1125 print_statistics();
1126 _cur_stat_index = 0;
1127 tty->print_cr("");
1128 }
1129 }
1130 }
1131
1132 void SafepointSynchronize::print_statistics() {
1133 int index;
1134 SafepointStats* sstats = _safepoint_stats;
1135
1136 for (index = 0; index <= _cur_stat_index; index++) {
1137 sstats = &_safepoint_stats[index];
1138 tty->print("%-28s ["
1139 INT32_FORMAT_W(8)INT32_FORMAT_W(11)INT32_FORMAT_W(15)
1140 "] ",
1141 sstats->_vmop_type == -1 ? "no vm operation" :
1142 VM_Operation::name(sstats->_vmop_type),
1143 sstats->_nof_total_threads,
1144 sstats->_nof_initial_running_threads,
1145 sstats->_nof_threads_wait_to_block);
1146 // "/ MICROUNITS " is to convert the unit from nanos to millis.
1147 tty->print(" ["
1148 INT64_FORMAT_W(6)INT64_FORMAT_W(6)INT64_FORMAT_W(6)
1149 "] "
1150 "["INT64_FORMAT_W(6)INT64_FORMAT_W(9) "] ",
1151 sstats->_time_to_spin / MICROUNITS,
1152 sstats->_time_to_wait_to_block / MICROUNITS,
1153 sstats->_time_to_sync / MICROUNITS,
1154 sstats->_time_to_exec_vmop / MICROUNITS,
1155 sstats->_time_elapsed_since_last_safepoint / MICROUNITS);
1156
1157 if (need_to_track_page_armed_status) {
1158 tty->print(INT32_FORMAT" ", sstats->_page_armed);
1159 }
1160 tty->print_cr(INT32_FORMAT" ", sstats->_nof_threads_hit_page_trap);
1161 }
1162 }
1163
1164 // This method will be called when VM exits. It will first call
1165 // print_statistics to print out the rest of the sampling. Then
1166 // it tries to summarize the sampling.
1167 void SafepointSynchronize::print_stat_on_exit() {
1168 if (_safepoint_stats == NULL) return;
1169
1170 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
1171
1172 // During VM exit, end_statistics may not get called and in that
1173 // case, if the sync time is less than PrintSafepointStatisticsTimeout,
1174 // don't print it out.
1175 // Approximate the vm op time.
1176 _safepoint_stats[_cur_stat_index]._time_to_exec_vmop =
1177 os::javaTimeNanos() - sync_end_time;
1178
1179 if ( PrintSafepointStatisticsTimeout < 0 ||
1180 spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) {
1181 print_statistics();
1182 }
1183 tty->print_cr("");
1184
1185 // Print out polling page sampling status.
1186 if (!need_to_track_page_armed_status) {
1187 if (UseCompilerSafepoints) {
1188 tty->print_cr("Polling page always armed");
1189 }
1190 } else {
1191 tty->print_cr("Defer polling page loop count = %d\n",
1192 DeferPollingPageLoopCount);
1193 }
1194
1195 for (int index = 0; index < VM_Operation::VMOp_Terminating; index++) {
1196 if (_safepoint_reasons[index] != 0) {
1197 tty->print_cr("%-26s"UINT64_FORMAT_W(10), VM_Operation::name(index),
1198 _safepoint_reasons[index]);
1199 }
1200 }
1201
1202 tty->print_cr(UINT64_FORMAT_W(5)" VM operations coalesced during safepoint",
1203 _coalesced_vmop_count);
1204 tty->print_cr("Maximum sync time "INT64_FORMAT_W(5)" ms",
1205 _max_sync_time / MICROUNITS);
1206 }
1207
1208 // ------------------------------------------------------------------------------------------------
1209 // Non-product code
1210
1211 #ifndef PRODUCT
1212
1213 void SafepointSynchronize::print_state() {
1214 if (_state == _not_synchronized) {
1215 tty->print_cr("not synchronized");
1216 } else if (_state == _synchronizing || _state == _synchronized) {
1217 tty->print_cr("State: %s", (_state == _synchronizing) ? "synchronizing" :
1218 "synchronized");
1219
1220 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) {
1221 cur->safepoint_state()->print();
1222 }
1223 }
1224 }
1225
1226 void SafepointSynchronize::safepoint_msg(const char* format, ...) {
1227 if (ShowSafepointMsgs) {
1228 va_list ap;
1229 va_start(ap, format);
1230 tty->vprint_cr(format, ap);
1231 va_end(ap);
1232 }
1233 }
1234
1235 #endif // !PRODUCT