Tue, 15 Mar 2011 06:35:10 -0700
7024234: 2/3 jvmti tests fail assert(!_oops_are_stale) failed: oops are stale on Win-AMD64
Summary: Move initialization of the '_instance' field to avoid race with ServiceThread start.
Reviewed-by: dholmes, kamg, never, dsamersoff, ysr, coleenp, acorn
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 */
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/symbol.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_ARCH_arm
65 # include "nativeInst_arm.hpp"
66 # include "vmreg_arm.inline.hpp"
67 #endif
68 #ifdef TARGET_ARCH_ppc
69 # include "nativeInst_ppc.hpp"
70 # include "vmreg_ppc.inline.hpp"
71 #endif
72 #ifdef TARGET_OS_FAMILY_linux
73 # include "thread_linux.inline.hpp"
74 #endif
75 #ifdef TARGET_OS_FAMILY_solaris
76 # include "thread_solaris.inline.hpp"
77 #endif
78 #ifdef TARGET_OS_FAMILY_windows
79 # include "thread_windows.inline.hpp"
80 #endif
81 #ifndef SERIALGC
82 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
83 #include "gc_implementation/shared/concurrentGCThread.hpp"
84 #endif
85 #ifdef COMPILER1
86 #include "c1/c1_globals.hpp"
87 #endif
89 // --------------------------------------------------------------------------------------------------
90 // Implementation of Safepoint begin/end
92 SafepointSynchronize::SynchronizeState volatile SafepointSynchronize::_state = SafepointSynchronize::_not_synchronized;
93 volatile int SafepointSynchronize::_waiting_to_block = 0;
94 volatile int SafepointSynchronize::_safepoint_counter = 0;
95 long SafepointSynchronize::_end_of_last_safepoint = 0;
96 static volatile int PageArmed = 0 ; // safepoint polling page is RO|RW vs PROT_NONE
97 static volatile int TryingToBlock = 0 ; // proximate value -- for advisory use only
98 static bool timeout_error_printed = false;
100 // Roll all threads forward to a safepoint and suspend them all
101 void SafepointSynchronize::begin() {
103 Thread* myThread = Thread::current();
104 assert(myThread->is_VM_thread(), "Only VM thread may execute a safepoint");
106 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) {
107 _safepoint_begin_time = os::javaTimeNanos();
108 _ts_of_current_safepoint = tty->time_stamp().seconds();
109 }
111 #ifndef SERIALGC
112 if (UseConcMarkSweepGC) {
113 // In the future we should investigate whether CMS can use the
114 // more-general mechanism below. DLD (01/05).
115 ConcurrentMarkSweepThread::synchronize(false);
116 } else if (UseG1GC) {
117 ConcurrentGCThread::safepoint_synchronize();
118 }
119 #endif // SERIALGC
121 // By getting the Threads_lock, we assure that no threads are about to start or
122 // exit. It is released again in SafepointSynchronize::end().
123 Threads_lock->lock();
125 assert( _state == _not_synchronized, "trying to safepoint synchronize with wrong state");
127 int nof_threads = Threads::number_of_threads();
129 if (TraceSafepoint) {
130 tty->print_cr("Safepoint synchronization initiated. (%d)", nof_threads);
131 }
133 RuntimeService::record_safepoint_begin();
135 {
136 MutexLocker mu(Safepoint_lock);
138 // Set number of threads to wait for, before we initiate the callbacks
139 _waiting_to_block = nof_threads;
140 TryingToBlock = 0 ;
141 int still_running = nof_threads;
143 // Save the starting time, so that it can be compared to see if this has taken
144 // too long to complete.
145 jlong safepoint_limit_time;
146 timeout_error_printed = false;
148 // PrintSafepointStatisticsTimeout can be specified separately. When
149 // specified, PrintSafepointStatistics will be set to true in
150 // deferred_initialize_stat method. The initialization has to be done
151 // early enough to avoid any races. See bug 6880029 for details.
152 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) {
153 deferred_initialize_stat();
154 }
156 // Begin the process of bringing the system to a safepoint.
157 // Java threads can be in several different states and are
158 // stopped by different mechanisms:
159 //
160 // 1. Running interpreted
161 // The interpeter dispatch table is changed to force it to
162 // check for a safepoint condition between bytecodes.
163 // 2. Running in native code
164 // When returning from the native code, a Java thread must check
165 // the safepoint _state to see if we must block. If the
166 // VM thread sees a Java thread in native, it does
167 // not wait for this thread to block. The order of the memory
168 // writes and reads of both the safepoint state and the Java
169 // threads state is critical. In order to guarantee that the
170 // memory writes are serialized with respect to each other,
171 // the VM thread issues a memory barrier instruction
172 // (on MP systems). In order to avoid the overhead of issuing
173 // a memory barrier for each Java thread making native calls, each Java
174 // thread performs a write to a single memory page after changing
175 // the thread state. The VM thread performs a sequence of
176 // mprotect OS calls which forces all previous writes from all
177 // Java threads to be serialized. This is done in the
178 // os::serialize_thread_states() call. This has proven to be
179 // much more efficient than executing a membar instruction
180 // on every call to native code.
181 // 3. Running compiled Code
182 // Compiled code reads a global (Safepoint Polling) page that
183 // is set to fault if we are trying to get to a safepoint.
184 // 4. Blocked
185 // A thread which is blocked will not be allowed to return from the
186 // block condition until the safepoint operation is complete.
187 // 5. In VM or Transitioning between states
188 // If a Java thread is currently running in the VM or transitioning
189 // between states, the safepointing code will wait for the thread to
190 // block itself when it attempts transitions to a new state.
191 //
192 _state = _synchronizing;
193 OrderAccess::fence();
195 // Flush all thread states to memory
196 if (!UseMembar) {
197 os::serialize_thread_states();
198 }
200 // Make interpreter safepoint aware
201 Interpreter::notice_safepoints();
203 if (UseCompilerSafepoints && DeferPollingPageLoopCount < 0) {
204 // Make polling safepoint aware
205 guarantee (PageArmed == 0, "invariant") ;
206 PageArmed = 1 ;
207 os::make_polling_page_unreadable();
208 }
210 // Consider using active_processor_count() ... but that call is expensive.
211 int ncpus = os::processor_count() ;
213 #ifdef ASSERT
214 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) {
215 assert(cur->safepoint_state()->is_running(), "Illegal initial state");
216 }
217 #endif // ASSERT
219 if (SafepointTimeout)
220 safepoint_limit_time = os::javaTimeNanos() + (jlong)SafepointTimeoutDelay * MICROUNITS;
222 // Iterate through all threads until it have been determined how to stop them all at a safepoint
223 unsigned int iterations = 0;
224 int steps = 0 ;
225 while(still_running > 0) {
226 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) {
227 assert(!cur->is_ConcurrentGC_thread(), "A concurrent GC thread is unexpectly being suspended");
228 ThreadSafepointState *cur_state = cur->safepoint_state();
229 if (cur_state->is_running()) {
230 cur_state->examine_state_of_thread();
231 if (!cur_state->is_running()) {
232 still_running--;
233 // consider adjusting steps downward:
234 // steps = 0
235 // steps -= NNN
236 // steps >>= 1
237 // steps = MIN(steps, 2000-100)
238 // if (iterations != 0) steps -= NNN
239 }
240 if (TraceSafepoint && Verbose) cur_state->print();
241 }
242 }
244 if (PrintSafepointStatistics && iterations == 0) {
245 begin_statistics(nof_threads, still_running);
246 }
248 if (still_running > 0) {
249 // Check for if it takes to long
250 if (SafepointTimeout && safepoint_limit_time < os::javaTimeNanos()) {
251 print_safepoint_timeout(_spinning_timeout);
252 }
254 // Spin to avoid context switching.
255 // There's a tension between allowing the mutators to run (and rendezvous)
256 // vs spinning. As the VM thread spins, wasting cycles, it consumes CPU that
257 // a mutator might otherwise use profitably to reach a safepoint. Excessive
258 // spinning by the VM thread on a saturated system can increase rendezvous latency.
259 // Blocking or yielding incur their own penalties in the form of context switching
260 // and the resultant loss of $ residency.
261 //
262 // Further complicating matters is that yield() does not work as naively expected
263 // on many platforms -- yield() does not guarantee that any other ready threads
264 // will run. As such we revert yield_all() after some number of iterations.
265 // Yield_all() is implemented as a short unconditional sleep on some platforms.
266 // Typical operating systems round a "short" sleep period up to 10 msecs, so sleeping
267 // can actually increase the time it takes the VM thread to detect that a system-wide
268 // stop-the-world safepoint has been reached. In a pathological scenario such as that
269 // described in CR6415670 the VMthread may sleep just before the mutator(s) become safe.
270 // In that case the mutators will be stalled waiting for the safepoint to complete and the
271 // the VMthread will be sleeping, waiting for the mutators to rendezvous. The VMthread
272 // will eventually wake up and detect that all mutators are safe, at which point
273 // we'll again make progress.
274 //
275 // Beware too that that the VMThread typically runs at elevated priority.
276 // Its default priority is higher than the default mutator priority.
277 // Obviously, this complicates spinning.
278 //
279 // Note too that on Windows XP SwitchThreadTo() has quite different behavior than Sleep(0).
280 // Sleep(0) will _not yield to lower priority threads, while SwitchThreadTo() will.
281 //
282 // See the comments in synchronizer.cpp for additional remarks on spinning.
283 //
284 // In the future we might:
285 // 1. Modify the safepoint scheme to avoid potentally unbounded spinning.
286 // This is tricky as the path used by a thread exiting the JVM (say on
287 // on JNI call-out) simply stores into its state field. The burden
288 // is placed on the VM thread, which must poll (spin).
289 // 2. Find something useful to do while spinning. If the safepoint is GC-related
290 // we might aggressively scan the stacks of threads that are already safe.
291 // 3. Use Solaris schedctl to examine the state of the still-running mutators.
292 // If all the mutators are ONPROC there's no reason to sleep or yield.
293 // 4. YieldTo() any still-running mutators that are ready but OFFPROC.
294 // 5. Check system saturation. If the system is not fully saturated then
295 // simply spin and avoid sleep/yield.
296 // 6. As still-running mutators rendezvous they could unpark the sleeping
297 // VMthread. This works well for still-running mutators that become
298 // safe. The VMthread must still poll for mutators that call-out.
299 // 7. Drive the policy on time-since-begin instead of iterations.
300 // 8. Consider making the spin duration a function of the # of CPUs:
301 // Spin = (((ncpus-1) * M) + K) + F(still_running)
302 // Alternately, instead of counting iterations of the outer loop
303 // we could count the # of threads visited in the inner loop, above.
304 // 9. On windows consider using the return value from SwitchThreadTo()
305 // to drive subsequent spin/SwitchThreadTo()/Sleep(N) decisions.
307 if (UseCompilerSafepoints && int(iterations) == DeferPollingPageLoopCount) {
308 guarantee (PageArmed == 0, "invariant") ;
309 PageArmed = 1 ;
310 os::make_polling_page_unreadable();
311 }
313 // Instead of (ncpus > 1) consider either (still_running < (ncpus + EPSILON)) or
314 // ((still_running + _waiting_to_block - TryingToBlock)) < ncpus)
315 ++steps ;
316 if (ncpus > 1 && steps < SafepointSpinBeforeYield) {
317 SpinPause() ; // MP-Polite spin
318 } else
319 if (steps < DeferThrSuspendLoopCount) {
320 os::NakedYield() ;
321 } else {
322 os::yield_all(steps) ;
323 // Alternately, the VM thread could transiently depress its scheduling priority or
324 // transiently increase the priority of the tardy mutator(s).
325 }
327 iterations ++ ;
328 }
329 assert(iterations < (uint)max_jint, "We have been iterating in the safepoint loop too long");
330 }
331 assert(still_running == 0, "sanity check");
333 if (PrintSafepointStatistics) {
334 update_statistics_on_spin_end();
335 }
337 // wait until all threads are stopped
338 while (_waiting_to_block > 0) {
339 if (TraceSafepoint) tty->print_cr("Waiting for %d thread(s) to block", _waiting_to_block);
340 if (!SafepointTimeout || timeout_error_printed) {
341 Safepoint_lock->wait(true); // true, means with no safepoint checks
342 } else {
343 // Compute remaining time
344 jlong remaining_time = safepoint_limit_time - os::javaTimeNanos();
346 // If there is no remaining time, then there is an error
347 if (remaining_time < 0 || Safepoint_lock->wait(true, remaining_time / MICROUNITS)) {
348 print_safepoint_timeout(_blocking_timeout);
349 }
350 }
351 }
352 assert(_waiting_to_block == 0, "sanity check");
354 #ifndef PRODUCT
355 if (SafepointTimeout) {
356 jlong current_time = os::javaTimeNanos();
357 if (safepoint_limit_time < current_time) {
358 tty->print_cr("# SafepointSynchronize: Finished after "
359 INT64_FORMAT_W(6) " ms",
360 ((current_time - safepoint_limit_time) / MICROUNITS +
361 SafepointTimeoutDelay));
362 }
363 }
364 #endif
366 assert((_safepoint_counter & 0x1) == 0, "must be even");
367 assert(Threads_lock->owned_by_self(), "must hold Threads_lock");
368 _safepoint_counter ++;
370 // Record state
371 _state = _synchronized;
373 OrderAccess::fence();
375 if (TraceSafepoint) {
376 VM_Operation *op = VMThread::vm_operation();
377 tty->print_cr("Entering safepoint region: %s", (op != NULL) ? op->name() : "no vm operation");
378 }
380 RuntimeService::record_safepoint_synchronized();
381 if (PrintSafepointStatistics) {
382 update_statistics_on_sync_end(os::javaTimeNanos());
383 }
385 // Call stuff that needs to be run when a safepoint is just about to be completed
386 do_cleanup_tasks();
388 if (PrintSafepointStatistics) {
389 // Record how much time spend on the above cleanup tasks
390 update_statistics_on_cleanup_end(os::javaTimeNanos());
391 }
392 }
393 }
395 // Wake up all threads, so they are ready to resume execution after the safepoint
396 // operation has been carried out
397 void SafepointSynchronize::end() {
399 assert(Threads_lock->owned_by_self(), "must hold Threads_lock");
400 assert((_safepoint_counter & 0x1) == 1, "must be odd");
401 _safepoint_counter ++;
402 // memory fence isn't required here since an odd _safepoint_counter
403 // value can do no harm and a fence is issued below anyway.
405 DEBUG_ONLY(Thread* myThread = Thread::current();)
406 assert(myThread->is_VM_thread(), "Only VM thread can execute a safepoint");
408 if (PrintSafepointStatistics) {
409 end_statistics(os::javaTimeNanos());
410 }
412 #ifdef ASSERT
413 // A pending_exception cannot be installed during a safepoint. The threads
414 // may install an async exception after they come back from a safepoint into
415 // pending_exception after they unblock. But that should happen later.
416 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) {
417 assert (!(cur->has_pending_exception() &&
418 cur->safepoint_state()->is_at_poll_safepoint()),
419 "safepoint installed a pending exception");
420 }
421 #endif // ASSERT
423 if (PageArmed) {
424 // Make polling safepoint aware
425 os::make_polling_page_readable();
426 PageArmed = 0 ;
427 }
429 // Remove safepoint check from interpreter
430 Interpreter::ignore_safepoints();
432 {
433 MutexLocker mu(Safepoint_lock);
435 assert(_state == _synchronized, "must be synchronized before ending safepoint synchronization");
437 // Set to not synchronized, so the threads will not go into the signal_thread_blocked method
438 // when they get restarted.
439 _state = _not_synchronized;
440 OrderAccess::fence();
442 if (TraceSafepoint) {
443 tty->print_cr("Leaving safepoint region");
444 }
446 // Start suspended threads
447 for(JavaThread *current = Threads::first(); current; current = current->next()) {
448 // A problem occurring on Solaris is when attempting to restart threads
449 // the first #cpus - 1 go well, but then the VMThread is preempted when we get
450 // to the next one (since it has been running the longest). We then have
451 // to wait for a cpu to become available before we can continue restarting
452 // threads.
453 // FIXME: This causes the performance of the VM to degrade when active and with
454 // large numbers of threads. Apparently this is due to the synchronous nature
455 // of suspending threads.
456 //
457 // TODO-FIXME: the comments above are vestigial and no longer apply.
458 // Furthermore, using solaris' schedctl in this particular context confers no benefit
459 if (VMThreadHintNoPreempt) {
460 os::hint_no_preempt();
461 }
462 ThreadSafepointState* cur_state = current->safepoint_state();
463 assert(cur_state->type() != ThreadSafepointState::_running, "Thread not suspended at safepoint");
464 cur_state->restart();
465 assert(cur_state->is_running(), "safepoint state has not been reset");
466 }
468 RuntimeService::record_safepoint_end();
470 // Release threads lock, so threads can be created/destroyed again. It will also starts all threads
471 // blocked in signal_thread_blocked
472 Threads_lock->unlock();
474 }
475 #ifndef SERIALGC
476 // If there are any concurrent GC threads resume them.
477 if (UseConcMarkSweepGC) {
478 ConcurrentMarkSweepThread::desynchronize(false);
479 } else if (UseG1GC) {
480 ConcurrentGCThread::safepoint_desynchronize();
481 }
482 #endif // SERIALGC
483 // record this time so VMThread can keep track how much time has elasped
484 // since last safepoint.
485 _end_of_last_safepoint = os::javaTimeMillis();
486 }
488 bool SafepointSynchronize::is_cleanup_needed() {
489 // Need a safepoint if some inline cache buffers is non-empty
490 if (!InlineCacheBuffer::is_empty()) return true;
491 return false;
492 }
496 // Various cleaning tasks that should be done periodically at safepoints
497 void SafepointSynchronize::do_cleanup_tasks() {
498 {
499 TraceTime t1("deflating idle monitors", TraceSafepointCleanupTime);
500 ObjectSynchronizer::deflate_idle_monitors();
501 }
503 {
504 TraceTime t2("updating inline caches", TraceSafepointCleanupTime);
505 InlineCacheBuffer::update_inline_caches();
506 }
507 {
508 TraceTime t3("compilation policy safepoint handler", TraceSafepointCleanupTime);
509 CompilationPolicy::policy()->do_safepoint_work();
510 }
512 TraceTime t4("sweeping nmethods", TraceSafepointCleanupTime);
513 NMethodSweeper::scan_stacks();
514 }
517 bool SafepointSynchronize::safepoint_safe(JavaThread *thread, JavaThreadState state) {
518 switch(state) {
519 case _thread_in_native:
520 // native threads are safe if they have no java stack or have walkable stack
521 return !thread->has_last_Java_frame() || thread->frame_anchor()->walkable();
523 // blocked threads should have already have walkable stack
524 case _thread_blocked:
525 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "blocked and not walkable");
526 return true;
528 default:
529 return false;
530 }
531 }
534 // -------------------------------------------------------------------------------------------------------
535 // Implementation of Safepoint callback point
537 void SafepointSynchronize::block(JavaThread *thread) {
538 assert(thread != NULL, "thread must be set");
539 assert(thread->is_Java_thread(), "not a Java thread");
541 // Threads shouldn't block if they are in the middle of printing, but...
542 ttyLocker::break_tty_lock_for_safepoint(os::current_thread_id());
544 // Only bail from the block() call if the thread is gone from the
545 // thread list; starting to exit should still block.
546 if (thread->is_terminated()) {
547 // block current thread if we come here from native code when VM is gone
548 thread->block_if_vm_exited();
550 // otherwise do nothing
551 return;
552 }
554 JavaThreadState state = thread->thread_state();
555 thread->frame_anchor()->make_walkable(thread);
557 // Check that we have a valid thread_state at this point
558 switch(state) {
559 case _thread_in_vm_trans:
560 case _thread_in_Java: // From compiled code
562 // We are highly likely to block on the Safepoint_lock. In order to avoid blocking in this case,
563 // we pretend we are still in the VM.
564 thread->set_thread_state(_thread_in_vm);
566 if (is_synchronizing()) {
567 Atomic::inc (&TryingToBlock) ;
568 }
570 // We will always be holding the Safepoint_lock when we are examine the state
571 // of a thread. Hence, the instructions between the Safepoint_lock->lock() and
572 // Safepoint_lock->unlock() are happening atomic with regards to the safepoint code
573 Safepoint_lock->lock_without_safepoint_check();
574 if (is_synchronizing()) {
575 // Decrement the number of threads to wait for and signal vm thread
576 assert(_waiting_to_block > 0, "sanity check");
577 _waiting_to_block--;
578 thread->safepoint_state()->set_has_called_back(true);
580 // Consider (_waiting_to_block < 2) to pipeline the wakeup of the VM thread
581 if (_waiting_to_block == 0) {
582 Safepoint_lock->notify_all();
583 }
584 }
586 // We transition the thread to state _thread_blocked here, but
587 // we can't do our usual check for external suspension and then
588 // self-suspend after the lock_without_safepoint_check() call
589 // below because we are often called during transitions while
590 // we hold different locks. That would leave us suspended while
591 // holding a resource which results in deadlocks.
592 thread->set_thread_state(_thread_blocked);
593 Safepoint_lock->unlock();
595 // We now try to acquire the threads lock. Since this lock is hold by the VM thread during
596 // the entire safepoint, the threads will all line up here during the safepoint.
597 Threads_lock->lock_without_safepoint_check();
598 // restore original state. This is important if the thread comes from compiled code, so it
599 // will continue to execute with the _thread_in_Java state.
600 thread->set_thread_state(state);
601 Threads_lock->unlock();
602 break;
604 case _thread_in_native_trans:
605 case _thread_blocked_trans:
606 case _thread_new_trans:
607 if (thread->safepoint_state()->type() == ThreadSafepointState::_call_back) {
608 thread->print_thread_state();
609 fatal("Deadlock in safepoint code. "
610 "Should have called back to the VM before blocking.");
611 }
613 // We transition the thread to state _thread_blocked here, but
614 // we can't do our usual check for external suspension and then
615 // self-suspend after the lock_without_safepoint_check() call
616 // below because we are often called during transitions while
617 // we hold different locks. That would leave us suspended while
618 // holding a resource which results in deadlocks.
619 thread->set_thread_state(_thread_blocked);
621 // It is not safe to suspend a thread if we discover it is in _thread_in_native_trans. Hence,
622 // the safepoint code might still be waiting for it to block. We need to change the state here,
623 // so it can see that it is at a safepoint.
625 // Block until the safepoint operation is completed.
626 Threads_lock->lock_without_safepoint_check();
628 // Restore state
629 thread->set_thread_state(state);
631 Threads_lock->unlock();
632 break;
634 default:
635 fatal(err_msg("Illegal threadstate encountered: %d", state));
636 }
638 // Check for pending. async. exceptions or suspends - except if the
639 // thread was blocked inside the VM. has_special_runtime_exit_condition()
640 // is called last since it grabs a lock and we only want to do that when
641 // we must.
642 //
643 // Note: we never deliver an async exception at a polling point as the
644 // compiler may not have an exception handler for it. The polling
645 // code will notice the async and deoptimize and the exception will
646 // be delivered. (Polling at a return point is ok though). Sure is
647 // a lot of bother for a deprecated feature...
648 //
649 // We don't deliver an async exception if the thread state is
650 // _thread_in_native_trans so JNI functions won't be called with
651 // a surprising pending exception. If the thread state is going back to java,
652 // async exception is checked in check_special_condition_for_native_trans().
654 if (state != _thread_blocked_trans &&
655 state != _thread_in_vm_trans &&
656 thread->has_special_runtime_exit_condition()) {
657 thread->handle_special_runtime_exit_condition(
658 !thread->is_at_poll_safepoint() && (state != _thread_in_native_trans));
659 }
660 }
662 // ------------------------------------------------------------------------------------------------------
663 // Exception handlers
665 #ifndef PRODUCT
666 #ifdef _LP64
667 #define PTR_PAD ""
668 #else
669 #define PTR_PAD " "
670 #endif
672 static void print_ptrs(intptr_t oldptr, intptr_t newptr, bool wasoop) {
673 bool is_oop = newptr ? ((oop)newptr)->is_oop() : false;
674 tty->print_cr(PTR_FORMAT PTR_PAD " %s %c " PTR_FORMAT PTR_PAD " %s %s",
675 oldptr, wasoop?"oop":" ", oldptr == newptr ? ' ' : '!',
676 newptr, is_oop?"oop":" ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":" "));
677 }
679 static void print_longs(jlong oldptr, jlong newptr, bool wasoop) {
680 bool is_oop = newptr ? ((oop)(intptr_t)newptr)->is_oop() : false;
681 tty->print_cr(PTR64_FORMAT " %s %c " PTR64_FORMAT " %s %s",
682 oldptr, wasoop?"oop":" ", oldptr == newptr ? ' ' : '!',
683 newptr, is_oop?"oop":" ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":" "));
684 }
686 #ifdef SPARC
687 static void print_me(intptr_t *new_sp, intptr_t *old_sp, bool *was_oops) {
688 #ifdef _LP64
689 tty->print_cr("--------+------address-----+------before-----------+-------after----------+");
690 const int incr = 1; // Increment to skip a long, in units of intptr_t
691 #else
692 tty->print_cr("--------+--address-+------before-----------+-------after----------+");
693 const int incr = 2; // Increment to skip a long, in units of intptr_t
694 #endif
695 tty->print_cr("---SP---|");
696 for( int i=0; i<16; i++ ) {
697 tty->print("blob %c%d |"PTR_FORMAT" ","LO"[i>>3],i&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); }
698 tty->print_cr("--------|");
699 for( int i1=0; i1<frame::memory_parameter_word_sp_offset-16; i1++ ) {
700 tty->print("argv pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); }
701 tty->print(" pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++);
702 tty->print_cr("--------|");
703 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;
704 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;
705 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;
706 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;
707 tty->print_cr(" FSR |"PTR_FORMAT" "PTR64_FORMAT" "PTR64_FORMAT,new_sp,*(jlong*)old_sp,*(jlong*)new_sp);
708 old_sp += incr; new_sp += incr; was_oops += incr;
709 // Skip the floats
710 tty->print_cr("--Float-|"PTR_FORMAT,new_sp);
711 tty->print_cr("---FP---|");
712 old_sp += incr*32; new_sp += incr*32; was_oops += incr*32;
713 for( int i2=0; i2<16; i2++ ) {
714 tty->print("call %c%d |"PTR_FORMAT" ","LI"[i2>>3],i2&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); }
715 tty->print_cr("");
716 }
717 #endif // SPARC
718 #endif // PRODUCT
721 void SafepointSynchronize::handle_polling_page_exception(JavaThread *thread) {
722 assert(thread->is_Java_thread(), "polling reference encountered by VM thread");
723 assert(thread->thread_state() == _thread_in_Java, "should come from Java code");
724 assert(SafepointSynchronize::is_synchronizing(), "polling encountered outside safepoint synchronization");
726 // Uncomment this to get some serious before/after printing of the
727 // Sparc safepoint-blob frame structure.
728 /*
729 intptr_t* sp = thread->last_Java_sp();
730 intptr_t stack_copy[150];
731 for( int i=0; i<150; i++ ) stack_copy[i] = sp[i];
732 bool was_oops[150];
733 for( int i=0; i<150; i++ )
734 was_oops[i] = stack_copy[i] ? ((oop)stack_copy[i])->is_oop() : false;
735 */
737 if (ShowSafepointMsgs) {
738 tty->print("handle_polling_page_exception: ");
739 }
741 if (PrintSafepointStatistics) {
742 inc_page_trap_count();
743 }
745 ThreadSafepointState* state = thread->safepoint_state();
747 state->handle_polling_page_exception();
748 // print_me(sp,stack_copy,was_oops);
749 }
752 void SafepointSynchronize::print_safepoint_timeout(SafepointTimeoutReason reason) {
753 if (!timeout_error_printed) {
754 timeout_error_printed = true;
755 // Print out the thread infor which didn't reach the safepoint for debugging
756 // purposes (useful when there are lots of threads in the debugger).
757 tty->print_cr("");
758 tty->print_cr("# SafepointSynchronize::begin: Timeout detected:");
759 if (reason == _spinning_timeout) {
760 tty->print_cr("# SafepointSynchronize::begin: Timed out while spinning to reach a safepoint.");
761 } else if (reason == _blocking_timeout) {
762 tty->print_cr("# SafepointSynchronize::begin: Timed out while waiting for threads to stop.");
763 }
765 tty->print_cr("# SafepointSynchronize::begin: Threads which did not reach the safepoint:");
766 ThreadSafepointState *cur_state;
767 ResourceMark rm;
768 for(JavaThread *cur_thread = Threads::first(); cur_thread;
769 cur_thread = cur_thread->next()) {
770 cur_state = cur_thread->safepoint_state();
772 if (cur_thread->thread_state() != _thread_blocked &&
773 ((reason == _spinning_timeout && cur_state->is_running()) ||
774 (reason == _blocking_timeout && !cur_state->has_called_back()))) {
775 tty->print("# ");
776 cur_thread->print();
777 tty->print_cr("");
778 }
779 }
780 tty->print_cr("# SafepointSynchronize::begin: (End of list)");
781 }
783 // To debug the long safepoint, specify both DieOnSafepointTimeout &
784 // ShowMessageBoxOnError.
785 if (DieOnSafepointTimeout) {
786 char msg[1024];
787 VM_Operation *op = VMThread::vm_operation();
788 sprintf(msg, "Safepoint sync time longer than " INTX_FORMAT "ms detected when executing %s.",
789 SafepointTimeoutDelay,
790 op != NULL ? op->name() : "no vm operation");
791 fatal(msg);
792 }
793 }
796 // -------------------------------------------------------------------------------------------------------
797 // Implementation of ThreadSafepointState
799 ThreadSafepointState::ThreadSafepointState(JavaThread *thread) {
800 _thread = thread;
801 _type = _running;
802 _has_called_back = false;
803 _at_poll_safepoint = false;
804 }
806 void ThreadSafepointState::create(JavaThread *thread) {
807 ThreadSafepointState *state = new ThreadSafepointState(thread);
808 thread->set_safepoint_state(state);
809 }
811 void ThreadSafepointState::destroy(JavaThread *thread) {
812 if (thread->safepoint_state()) {
813 delete(thread->safepoint_state());
814 thread->set_safepoint_state(NULL);
815 }
816 }
818 void ThreadSafepointState::examine_state_of_thread() {
819 assert(is_running(), "better be running or just have hit safepoint poll");
821 JavaThreadState state = _thread->thread_state();
823 // Save the state at the start of safepoint processing.
824 _orig_thread_state = state;
826 // Check for a thread that is suspended. Note that thread resume tries
827 // to grab the Threads_lock which we own here, so a thread cannot be
828 // resumed during safepoint synchronization.
830 // We check to see if this thread is suspended without locking to
831 // avoid deadlocking with a third thread that is waiting for this
832 // thread to be suspended. The third thread can notice the safepoint
833 // that we're trying to start at the beginning of its SR_lock->wait()
834 // call. If that happens, then the third thread will block on the
835 // safepoint while still holding the underlying SR_lock. We won't be
836 // able to get the SR_lock and we'll deadlock.
837 //
838 // We don't need to grab the SR_lock here for two reasons:
839 // 1) The suspend flags are both volatile and are set with an
840 // Atomic::cmpxchg() call so we should see the suspended
841 // state right away.
842 // 2) We're being called from the safepoint polling loop; if
843 // we don't see the suspended state on this iteration, then
844 // we'll come around again.
845 //
846 bool is_suspended = _thread->is_ext_suspended();
847 if (is_suspended) {
848 roll_forward(_at_safepoint);
849 return;
850 }
852 // Some JavaThread states have an initial safepoint state of
853 // running, but are actually at a safepoint. We will happily
854 // agree and update the safepoint state here.
855 if (SafepointSynchronize::safepoint_safe(_thread, state)) {
856 roll_forward(_at_safepoint);
857 return;
858 }
860 if (state == _thread_in_vm) {
861 roll_forward(_call_back);
862 return;
863 }
865 // All other thread states will continue to run until they
866 // transition and self-block in state _blocked
867 // Safepoint polling in compiled code causes the Java threads to do the same.
868 // Note: new threads may require a malloc so they must be allowed to finish
870 assert(is_running(), "examine_state_of_thread on non-running thread");
871 return;
872 }
874 // Returns true is thread could not be rolled forward at present position.
875 void ThreadSafepointState::roll_forward(suspend_type type) {
876 _type = type;
878 switch(_type) {
879 case _at_safepoint:
880 SafepointSynchronize::signal_thread_at_safepoint();
881 break;
883 case _call_back:
884 set_has_called_back(false);
885 break;
887 case _running:
888 default:
889 ShouldNotReachHere();
890 }
891 }
893 void ThreadSafepointState::restart() {
894 switch(type()) {
895 case _at_safepoint:
896 case _call_back:
897 break;
899 case _running:
900 default:
901 tty->print_cr("restart thread "INTPTR_FORMAT" with state %d",
902 _thread, _type);
903 _thread->print();
904 ShouldNotReachHere();
905 }
906 _type = _running;
907 set_has_called_back(false);
908 }
911 void ThreadSafepointState::print_on(outputStream *st) const {
912 const char *s;
914 switch(_type) {
915 case _running : s = "_running"; break;
916 case _at_safepoint : s = "_at_safepoint"; break;
917 case _call_back : s = "_call_back"; break;
918 default:
919 ShouldNotReachHere();
920 }
922 st->print_cr("Thread: " INTPTR_FORMAT
923 " [0x%2x] State: %s _has_called_back %d _at_poll_safepoint %d",
924 _thread, _thread->osthread()->thread_id(), s, _has_called_back,
925 _at_poll_safepoint);
927 _thread->print_thread_state_on(st);
928 }
931 // ---------------------------------------------------------------------------------------------------------------------
933 // Block the thread at the safepoint poll or poll return.
934 void ThreadSafepointState::handle_polling_page_exception() {
936 // Check state. block() will set thread state to thread_in_vm which will
937 // cause the safepoint state _type to become _call_back.
938 assert(type() == ThreadSafepointState::_running,
939 "polling page exception on thread not running state");
941 // Step 1: Find the nmethod from the return address
942 if (ShowSafepointMsgs && Verbose) {
943 tty->print_cr("Polling page exception at " INTPTR_FORMAT, thread()->saved_exception_pc());
944 }
945 address real_return_addr = thread()->saved_exception_pc();
947 CodeBlob *cb = CodeCache::find_blob(real_return_addr);
948 assert(cb != NULL && cb->is_nmethod(), "return address should be in nmethod");
949 nmethod* nm = (nmethod*)cb;
951 // Find frame of caller
952 frame stub_fr = thread()->last_frame();
953 CodeBlob* stub_cb = stub_fr.cb();
954 assert(stub_cb->is_safepoint_stub(), "must be a safepoint stub");
955 RegisterMap map(thread(), true);
956 frame caller_fr = stub_fr.sender(&map);
958 // Should only be poll_return or poll
959 assert( nm->is_at_poll_or_poll_return(real_return_addr), "should not be at call" );
961 // This is a poll immediately before a return. The exception handling code
962 // has already had the effect of causing the return to occur, so the execution
963 // will continue immediately after the call. In addition, the oopmap at the
964 // return point does not mark the return value as an oop (if it is), so
965 // it needs a handle here to be updated.
966 if( nm->is_at_poll_return(real_return_addr) ) {
967 // See if return type is an oop.
968 bool return_oop = nm->method()->is_returning_oop();
969 Handle return_value;
970 if (return_oop) {
971 // The oop result has been saved on the stack together with all
972 // the other registers. In order to preserve it over GCs we need
973 // to keep it in a handle.
974 oop result = caller_fr.saved_oop_result(&map);
975 assert(result == NULL || result->is_oop(), "must be oop");
976 return_value = Handle(thread(), result);
977 assert(Universe::heap()->is_in_or_null(result), "must be heap pointer");
978 }
980 // Block the thread
981 SafepointSynchronize::block(thread());
983 // restore oop result, if any
984 if (return_oop) {
985 caller_fr.set_saved_oop_result(&map, return_value());
986 }
987 }
989 // This is a safepoint poll. Verify the return address and block.
990 else {
991 set_at_poll_safepoint(true);
993 // verify the blob built the "return address" correctly
994 assert(real_return_addr == caller_fr.pc(), "must match");
996 // Block the thread
997 SafepointSynchronize::block(thread());
998 set_at_poll_safepoint(false);
1000 // If we have a pending async exception deoptimize the frame
1001 // as otherwise we may never deliver it.
1002 if (thread()->has_async_condition()) {
1003 ThreadInVMfromJavaNoAsyncException __tiv(thread());
1004 Deoptimization::deoptimize_frame(thread(), caller_fr.id());
1005 }
1007 // If an exception has been installed we must check for a pending deoptimization
1008 // Deoptimize frame if exception has been thrown.
1010 if (thread()->has_pending_exception() ) {
1011 RegisterMap map(thread(), true);
1012 frame caller_fr = stub_fr.sender(&map);
1013 if (caller_fr.is_deoptimized_frame()) {
1014 // The exception patch will destroy registers that are still
1015 // live and will be needed during deoptimization. Defer the
1016 // Async exception should have defered the exception until the
1017 // next safepoint which will be detected when we get into
1018 // the interpreter so if we have an exception now things
1019 // are messed up.
1021 fatal("Exception installed and deoptimization is pending");
1022 }
1023 }
1024 }
1025 }
1028 //
1029 // Statistics & Instrumentations
1030 //
1031 SafepointSynchronize::SafepointStats* SafepointSynchronize::_safepoint_stats = NULL;
1032 jlong SafepointSynchronize::_safepoint_begin_time = 0;
1033 int SafepointSynchronize::_cur_stat_index = 0;
1034 julong SafepointSynchronize::_safepoint_reasons[VM_Operation::VMOp_Terminating];
1035 julong SafepointSynchronize::_coalesced_vmop_count = 0;
1036 jlong SafepointSynchronize::_max_sync_time = 0;
1037 jlong SafepointSynchronize::_max_vmop_time = 0;
1038 float SafepointSynchronize::_ts_of_current_safepoint = 0.0f;
1040 static jlong cleanup_end_time = 0;
1041 static bool need_to_track_page_armed_status = false;
1042 static bool init_done = false;
1044 // Helper method to print the header.
1045 static void print_header() {
1046 tty->print(" vmop "
1047 "[threads: total initially_running wait_to_block] ");
1048 tty->print("[time: spin block sync cleanup vmop] ");
1050 // no page armed status printed out if it is always armed.
1051 if (need_to_track_page_armed_status) {
1052 tty->print("page_armed ");
1053 }
1055 tty->print_cr("page_trap_count");
1056 }
1058 void SafepointSynchronize::deferred_initialize_stat() {
1059 if (init_done) return;
1061 if (PrintSafepointStatisticsCount <= 0) {
1062 fatal("Wrong PrintSafepointStatisticsCount");
1063 }
1065 // If PrintSafepointStatisticsTimeout is specified, the statistics data will
1066 // be printed right away, in which case, _safepoint_stats will regress to
1067 // a single element array. Otherwise, it is a circular ring buffer with default
1068 // size of PrintSafepointStatisticsCount.
1069 int stats_array_size;
1070 if (PrintSafepointStatisticsTimeout > 0) {
1071 stats_array_size = 1;
1072 PrintSafepointStatistics = true;
1073 } else {
1074 stats_array_size = PrintSafepointStatisticsCount;
1075 }
1076 _safepoint_stats = (SafepointStats*)os::malloc(stats_array_size
1077 * sizeof(SafepointStats));
1078 guarantee(_safepoint_stats != NULL,
1079 "not enough memory for safepoint instrumentation data");
1081 if (UseCompilerSafepoints && DeferPollingPageLoopCount >= 0) {
1082 need_to_track_page_armed_status = true;
1083 }
1084 init_done = true;
1085 }
1087 void SafepointSynchronize::begin_statistics(int nof_threads, int nof_running) {
1088 assert(init_done, "safepoint statistics array hasn't been initialized");
1089 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
1091 spstat->_time_stamp = _ts_of_current_safepoint;
1093 VM_Operation *op = VMThread::vm_operation();
1094 spstat->_vmop_type = (op != NULL ? op->type() : -1);
1095 if (op != NULL) {
1096 _safepoint_reasons[spstat->_vmop_type]++;
1097 }
1099 spstat->_nof_total_threads = nof_threads;
1100 spstat->_nof_initial_running_threads = nof_running;
1101 spstat->_nof_threads_hit_page_trap = 0;
1103 // Records the start time of spinning. The real time spent on spinning
1104 // will be adjusted when spin is done. Same trick is applied for time
1105 // spent on waiting for threads to block.
1106 if (nof_running != 0) {
1107 spstat->_time_to_spin = os::javaTimeNanos();
1108 } else {
1109 spstat->_time_to_spin = 0;
1110 }
1111 }
1113 void SafepointSynchronize::update_statistics_on_spin_end() {
1114 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
1116 jlong cur_time = os::javaTimeNanos();
1118 spstat->_nof_threads_wait_to_block = _waiting_to_block;
1119 if (spstat->_nof_initial_running_threads != 0) {
1120 spstat->_time_to_spin = cur_time - spstat->_time_to_spin;
1121 }
1123 if (need_to_track_page_armed_status) {
1124 spstat->_page_armed = (PageArmed == 1);
1125 }
1127 // Records the start time of waiting for to block. Updated when block is done.
1128 if (_waiting_to_block != 0) {
1129 spstat->_time_to_wait_to_block = cur_time;
1130 } else {
1131 spstat->_time_to_wait_to_block = 0;
1132 }
1133 }
1135 void SafepointSynchronize::update_statistics_on_sync_end(jlong end_time) {
1136 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
1138 if (spstat->_nof_threads_wait_to_block != 0) {
1139 spstat->_time_to_wait_to_block = end_time -
1140 spstat->_time_to_wait_to_block;
1141 }
1143 // Records the end time of sync which will be used to calculate the total
1144 // vm operation time. Again, the real time spending in syncing will be deducted
1145 // from the start of the sync time later when end_statistics is called.
1146 spstat->_time_to_sync = end_time - _safepoint_begin_time;
1147 if (spstat->_time_to_sync > _max_sync_time) {
1148 _max_sync_time = spstat->_time_to_sync;
1149 }
1151 spstat->_time_to_do_cleanups = end_time;
1152 }
1154 void SafepointSynchronize::update_statistics_on_cleanup_end(jlong end_time) {
1155 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
1157 // Record how long spent in cleanup tasks.
1158 spstat->_time_to_do_cleanups = end_time - spstat->_time_to_do_cleanups;
1160 cleanup_end_time = end_time;
1161 }
1163 void SafepointSynchronize::end_statistics(jlong vmop_end_time) {
1164 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
1166 // Update the vm operation time.
1167 spstat->_time_to_exec_vmop = vmop_end_time - cleanup_end_time;
1168 if (spstat->_time_to_exec_vmop > _max_vmop_time) {
1169 _max_vmop_time = spstat->_time_to_exec_vmop;
1170 }
1171 // Only the sync time longer than the specified
1172 // PrintSafepointStatisticsTimeout will be printed out right away.
1173 // By default, it is -1 meaning all samples will be put into the list.
1174 if ( PrintSafepointStatisticsTimeout > 0) {
1175 if (spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) {
1176 print_statistics();
1177 }
1178 } else {
1179 // The safepoint statistics will be printed out when the _safepoin_stats
1180 // array fills up.
1181 if (_cur_stat_index == PrintSafepointStatisticsCount - 1) {
1182 print_statistics();
1183 _cur_stat_index = 0;
1184 } else {
1185 _cur_stat_index++;
1186 }
1187 }
1188 }
1190 void SafepointSynchronize::print_statistics() {
1191 SafepointStats* sstats = _safepoint_stats;
1193 for (int index = 0; index <= _cur_stat_index; index++) {
1194 if (index % 30 == 0) {
1195 print_header();
1196 }
1197 sstats = &_safepoint_stats[index];
1198 tty->print("%.3f: ", sstats->_time_stamp);
1199 tty->print("%-26s ["
1200 INT32_FORMAT_W(8)INT32_FORMAT_W(11)INT32_FORMAT_W(15)
1201 " ] ",
1202 sstats->_vmop_type == -1 ? "no vm operation" :
1203 VM_Operation::name(sstats->_vmop_type),
1204 sstats->_nof_total_threads,
1205 sstats->_nof_initial_running_threads,
1206 sstats->_nof_threads_wait_to_block);
1207 // "/ MICROUNITS " is to convert the unit from nanos to millis.
1208 tty->print(" ["
1209 INT64_FORMAT_W(6)INT64_FORMAT_W(6)
1210 INT64_FORMAT_W(6)INT64_FORMAT_W(6)
1211 INT64_FORMAT_W(6)" ] ",
1212 sstats->_time_to_spin / MICROUNITS,
1213 sstats->_time_to_wait_to_block / MICROUNITS,
1214 sstats->_time_to_sync / MICROUNITS,
1215 sstats->_time_to_do_cleanups / MICROUNITS,
1216 sstats->_time_to_exec_vmop / MICROUNITS);
1218 if (need_to_track_page_armed_status) {
1219 tty->print(INT32_FORMAT" ", sstats->_page_armed);
1220 }
1221 tty->print_cr(INT32_FORMAT" ", sstats->_nof_threads_hit_page_trap);
1222 }
1223 }
1225 // This method will be called when VM exits. It will first call
1226 // print_statistics to print out the rest of the sampling. Then
1227 // it tries to summarize the sampling.
1228 void SafepointSynchronize::print_stat_on_exit() {
1229 if (_safepoint_stats == NULL) return;
1231 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
1233 // During VM exit, end_statistics may not get called and in that
1234 // case, if the sync time is less than PrintSafepointStatisticsTimeout,
1235 // don't print it out.
1236 // Approximate the vm op time.
1237 _safepoint_stats[_cur_stat_index]._time_to_exec_vmop =
1238 os::javaTimeNanos() - cleanup_end_time;
1240 if ( PrintSafepointStatisticsTimeout < 0 ||
1241 spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) {
1242 print_statistics();
1243 }
1244 tty->print_cr("");
1246 // Print out polling page sampling status.
1247 if (!need_to_track_page_armed_status) {
1248 if (UseCompilerSafepoints) {
1249 tty->print_cr("Polling page always armed");
1250 }
1251 } else {
1252 tty->print_cr("Defer polling page loop count = %d\n",
1253 DeferPollingPageLoopCount);
1254 }
1256 for (int index = 0; index < VM_Operation::VMOp_Terminating; index++) {
1257 if (_safepoint_reasons[index] != 0) {
1258 tty->print_cr("%-26s"UINT64_FORMAT_W(10), VM_Operation::name(index),
1259 _safepoint_reasons[index]);
1260 }
1261 }
1263 tty->print_cr(UINT64_FORMAT_W(5)" VM operations coalesced during safepoint",
1264 _coalesced_vmop_count);
1265 tty->print_cr("Maximum sync time "INT64_FORMAT_W(5)" ms",
1266 _max_sync_time / MICROUNITS);
1267 tty->print_cr("Maximum vm operation time (except for Exit VM operation) "
1268 INT64_FORMAT_W(5)" ms",
1269 _max_vmop_time / MICROUNITS);
1270 }
1272 // ------------------------------------------------------------------------------------------------
1273 // Non-product code
1275 #ifndef PRODUCT
1277 void SafepointSynchronize::print_state() {
1278 if (_state == _not_synchronized) {
1279 tty->print_cr("not synchronized");
1280 } else if (_state == _synchronizing || _state == _synchronized) {
1281 tty->print_cr("State: %s", (_state == _synchronizing) ? "synchronizing" :
1282 "synchronized");
1284 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) {
1285 cur->safepoint_state()->print();
1286 }
1287 }
1288 }
1290 void SafepointSynchronize::safepoint_msg(const char* format, ...) {
1291 if (ShowSafepointMsgs) {
1292 va_list ap;
1293 va_start(ap, format);
1294 tty->vprint_cr(format, ap);
1295 va_end(ap);
1296 }
1297 }
1299 #endif // !PRODUCT