Mon, 18 Jun 2012 12:29:21 -0700
7176856: add the JRE name to the error log
Reviewed-by: coleenp, jrose, kvn, twisti
Contributed-by: Krystal Mok <sajia@taobao.com>
1 /*
2 * Copyright (c) 1997, 2012, 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 #ifdef TARGET_OS_FAMILY_bsd
82 # include "thread_bsd.inline.hpp"
83 #endif
84 #ifndef SERIALGC
85 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
86 #include "gc_implementation/shared/concurrentGCThread.hpp"
87 #endif
88 #ifdef COMPILER1
89 #include "c1/c1_globals.hpp"
90 #endif
92 // --------------------------------------------------------------------------------------------------
93 // Implementation of Safepoint begin/end
95 SafepointSynchronize::SynchronizeState volatile SafepointSynchronize::_state = SafepointSynchronize::_not_synchronized;
96 volatile int SafepointSynchronize::_waiting_to_block = 0;
97 volatile int SafepointSynchronize::_safepoint_counter = 0;
98 int SafepointSynchronize::_current_jni_active_count = 0;
99 long SafepointSynchronize::_end_of_last_safepoint = 0;
100 static volatile int PageArmed = 0 ; // safepoint polling page is RO|RW vs PROT_NONE
101 static volatile int TryingToBlock = 0 ; // proximate value -- for advisory use only
102 static bool timeout_error_printed = false;
104 // Roll all threads forward to a safepoint and suspend them all
105 void SafepointSynchronize::begin() {
107 Thread* myThread = Thread::current();
108 assert(myThread->is_VM_thread(), "Only VM thread may execute a safepoint");
110 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) {
111 _safepoint_begin_time = os::javaTimeNanos();
112 _ts_of_current_safepoint = tty->time_stamp().seconds();
113 }
115 #ifndef SERIALGC
116 if (UseConcMarkSweepGC) {
117 // In the future we should investigate whether CMS can use the
118 // more-general mechanism below. DLD (01/05).
119 ConcurrentMarkSweepThread::synchronize(false);
120 } else if (UseG1GC) {
121 ConcurrentGCThread::safepoint_synchronize();
122 }
123 #endif // SERIALGC
125 // By getting the Threads_lock, we assure that no threads are about to start or
126 // exit. It is released again in SafepointSynchronize::end().
127 Threads_lock->lock();
129 assert( _state == _not_synchronized, "trying to safepoint synchronize with wrong state");
131 int nof_threads = Threads::number_of_threads();
133 if (TraceSafepoint) {
134 tty->print_cr("Safepoint synchronization initiated. (%d)", nof_threads);
135 }
137 RuntimeService::record_safepoint_begin();
139 MutexLocker mu(Safepoint_lock);
141 // Reset the count of active JNI critical threads
142 _current_jni_active_count = 0;
144 // Set number of threads to wait for, before we initiate the callbacks
145 _waiting_to_block = nof_threads;
146 TryingToBlock = 0 ;
147 int still_running = nof_threads;
149 // Save the starting time, so that it can be compared to see if this has taken
150 // too long to complete.
151 jlong safepoint_limit_time;
152 timeout_error_printed = false;
154 // PrintSafepointStatisticsTimeout can be specified separately. When
155 // specified, PrintSafepointStatistics will be set to true in
156 // deferred_initialize_stat method. The initialization has to be done
157 // early enough to avoid any races. See bug 6880029 for details.
158 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) {
159 deferred_initialize_stat();
160 }
162 // Begin the process of bringing the system to a safepoint.
163 // Java threads can be in several different states and are
164 // stopped by different mechanisms:
165 //
166 // 1. Running interpreted
167 // The interpeter dispatch table is changed to force it to
168 // check for a safepoint condition between bytecodes.
169 // 2. Running in native code
170 // When returning from the native code, a Java thread must check
171 // the safepoint _state to see if we must block. If the
172 // VM thread sees a Java thread in native, it does
173 // not wait for this thread to block. The order of the memory
174 // writes and reads of both the safepoint state and the Java
175 // threads state is critical. In order to guarantee that the
176 // memory writes are serialized with respect to each other,
177 // the VM thread issues a memory barrier instruction
178 // (on MP systems). In order to avoid the overhead of issuing
179 // a memory barrier for each Java thread making native calls, each Java
180 // thread performs a write to a single memory page after changing
181 // the thread state. The VM thread performs a sequence of
182 // mprotect OS calls which forces all previous writes from all
183 // Java threads to be serialized. This is done in the
184 // os::serialize_thread_states() call. This has proven to be
185 // much more efficient than executing a membar instruction
186 // on every call to native code.
187 // 3. Running compiled Code
188 // Compiled code reads a global (Safepoint Polling) page that
189 // is set to fault if we are trying to get to a safepoint.
190 // 4. Blocked
191 // A thread which is blocked will not be allowed to return from the
192 // block condition until the safepoint operation is complete.
193 // 5. In VM or Transitioning between states
194 // If a Java thread is currently running in the VM or transitioning
195 // between states, the safepointing code will wait for the thread to
196 // block itself when it attempts transitions to a new state.
197 //
198 _state = _synchronizing;
199 OrderAccess::fence();
201 // Flush all thread states to memory
202 if (!UseMembar) {
203 os::serialize_thread_states();
204 }
206 // Make interpreter safepoint aware
207 Interpreter::notice_safepoints();
209 if (UseCompilerSafepoints && DeferPollingPageLoopCount < 0) {
210 // Make polling safepoint aware
211 guarantee (PageArmed == 0, "invariant") ;
212 PageArmed = 1 ;
213 os::make_polling_page_unreadable();
214 }
216 // Consider using active_processor_count() ... but that call is expensive.
217 int ncpus = os::processor_count() ;
219 #ifdef ASSERT
220 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) {
221 assert(cur->safepoint_state()->is_running(), "Illegal initial state");
222 // Clear the visited flag to ensure that the critical counts are collected properly.
223 cur->set_visited_for_critical_count(false);
224 }
225 #endif // ASSERT
227 if (SafepointTimeout)
228 safepoint_limit_time = os::javaTimeNanos() + (jlong)SafepointTimeoutDelay * MICROUNITS;
230 // Iterate through all threads until it have been determined how to stop them all at a safepoint
231 unsigned int iterations = 0;
232 int steps = 0 ;
233 while(still_running > 0) {
234 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) {
235 assert(!cur->is_ConcurrentGC_thread(), "A concurrent GC thread is unexpectly being suspended");
236 ThreadSafepointState *cur_state = cur->safepoint_state();
237 if (cur_state->is_running()) {
238 cur_state->examine_state_of_thread();
239 if (!cur_state->is_running()) {
240 still_running--;
241 // consider adjusting steps downward:
242 // steps = 0
243 // steps -= NNN
244 // steps >>= 1
245 // steps = MIN(steps, 2000-100)
246 // if (iterations != 0) steps -= NNN
247 }
248 if (TraceSafepoint && Verbose) cur_state->print();
249 }
250 }
252 if (PrintSafepointStatistics && iterations == 0) {
253 begin_statistics(nof_threads, still_running);
254 }
256 if (still_running > 0) {
257 // Check for if it takes to long
258 if (SafepointTimeout && safepoint_limit_time < os::javaTimeNanos()) {
259 print_safepoint_timeout(_spinning_timeout);
260 }
262 // Spin to avoid context switching.
263 // There's a tension between allowing the mutators to run (and rendezvous)
264 // vs spinning. As the VM thread spins, wasting cycles, it consumes CPU that
265 // a mutator might otherwise use profitably to reach a safepoint. Excessive
266 // spinning by the VM thread on a saturated system can increase rendezvous latency.
267 // Blocking or yielding incur their own penalties in the form of context switching
268 // and the resultant loss of $ residency.
269 //
270 // Further complicating matters is that yield() does not work as naively expected
271 // on many platforms -- yield() does not guarantee that any other ready threads
272 // will run. As such we revert yield_all() after some number of iterations.
273 // Yield_all() is implemented as a short unconditional sleep on some platforms.
274 // Typical operating systems round a "short" sleep period up to 10 msecs, so sleeping
275 // can actually increase the time it takes the VM thread to detect that a system-wide
276 // stop-the-world safepoint has been reached. In a pathological scenario such as that
277 // described in CR6415670 the VMthread may sleep just before the mutator(s) become safe.
278 // In that case the mutators will be stalled waiting for the safepoint to complete and the
279 // the VMthread will be sleeping, waiting for the mutators to rendezvous. The VMthread
280 // will eventually wake up and detect that all mutators are safe, at which point
281 // we'll again make progress.
282 //
283 // Beware too that that the VMThread typically runs at elevated priority.
284 // Its default priority is higher than the default mutator priority.
285 // Obviously, this complicates spinning.
286 //
287 // Note too that on Windows XP SwitchThreadTo() has quite different behavior than Sleep(0).
288 // Sleep(0) will _not yield to lower priority threads, while SwitchThreadTo() will.
289 //
290 // See the comments in synchronizer.cpp for additional remarks on spinning.
291 //
292 // In the future we might:
293 // 1. Modify the safepoint scheme to avoid potentally unbounded spinning.
294 // This is tricky as the path used by a thread exiting the JVM (say on
295 // on JNI call-out) simply stores into its state field. The burden
296 // is placed on the VM thread, which must poll (spin).
297 // 2. Find something useful to do while spinning. If the safepoint is GC-related
298 // we might aggressively scan the stacks of threads that are already safe.
299 // 3. Use Solaris schedctl to examine the state of the still-running mutators.
300 // If all the mutators are ONPROC there's no reason to sleep or yield.
301 // 4. YieldTo() any still-running mutators that are ready but OFFPROC.
302 // 5. Check system saturation. If the system is not fully saturated then
303 // simply spin and avoid sleep/yield.
304 // 6. As still-running mutators rendezvous they could unpark the sleeping
305 // VMthread. This works well for still-running mutators that become
306 // safe. The VMthread must still poll for mutators that call-out.
307 // 7. Drive the policy on time-since-begin instead of iterations.
308 // 8. Consider making the spin duration a function of the # of CPUs:
309 // Spin = (((ncpus-1) * M) + K) + F(still_running)
310 // Alternately, instead of counting iterations of the outer loop
311 // we could count the # of threads visited in the inner loop, above.
312 // 9. On windows consider using the return value from SwitchThreadTo()
313 // to drive subsequent spin/SwitchThreadTo()/Sleep(N) decisions.
315 if (UseCompilerSafepoints && int(iterations) == DeferPollingPageLoopCount) {
316 guarantee (PageArmed == 0, "invariant") ;
317 PageArmed = 1 ;
318 os::make_polling_page_unreadable();
319 }
321 // Instead of (ncpus > 1) consider either (still_running < (ncpus + EPSILON)) or
322 // ((still_running + _waiting_to_block - TryingToBlock)) < ncpus)
323 ++steps ;
324 if (ncpus > 1 && steps < SafepointSpinBeforeYield) {
325 SpinPause() ; // MP-Polite spin
326 } else
327 if (steps < DeferThrSuspendLoopCount) {
328 os::NakedYield() ;
329 } else {
330 os::yield_all(steps) ;
331 // Alternately, the VM thread could transiently depress its scheduling priority or
332 // transiently increase the priority of the tardy mutator(s).
333 }
335 iterations ++ ;
336 }
337 assert(iterations < (uint)max_jint, "We have been iterating in the safepoint loop too long");
338 }
339 assert(still_running == 0, "sanity check");
341 if (PrintSafepointStatistics) {
342 update_statistics_on_spin_end();
343 }
345 // wait until all threads are stopped
346 while (_waiting_to_block > 0) {
347 if (TraceSafepoint) tty->print_cr("Waiting for %d thread(s) to block", _waiting_to_block);
348 if (!SafepointTimeout || timeout_error_printed) {
349 Safepoint_lock->wait(true); // true, means with no safepoint checks
350 } else {
351 // Compute remaining time
352 jlong remaining_time = safepoint_limit_time - os::javaTimeNanos();
354 // If there is no remaining time, then there is an error
355 if (remaining_time < 0 || Safepoint_lock->wait(true, remaining_time / MICROUNITS)) {
356 print_safepoint_timeout(_blocking_timeout);
357 }
358 }
359 }
360 assert(_waiting_to_block == 0, "sanity check");
362 #ifndef PRODUCT
363 if (SafepointTimeout) {
364 jlong current_time = os::javaTimeNanos();
365 if (safepoint_limit_time < current_time) {
366 tty->print_cr("# SafepointSynchronize: Finished after "
367 INT64_FORMAT_W(6) " ms",
368 ((current_time - safepoint_limit_time) / MICROUNITS +
369 SafepointTimeoutDelay));
370 }
371 }
372 #endif
374 assert((_safepoint_counter & 0x1) == 0, "must be even");
375 assert(Threads_lock->owned_by_self(), "must hold Threads_lock");
376 _safepoint_counter ++;
378 // Record state
379 _state = _synchronized;
381 OrderAccess::fence();
383 #ifdef ASSERT
384 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) {
385 // make sure all the threads were visited
386 assert(cur->was_visited_for_critical_count(), "missed a thread");
387 }
388 #endif // ASSERT
390 // Update the count of active JNI critical regions
391 GC_locker::set_jni_lock_count(_current_jni_active_count);
393 if (TraceSafepoint) {
394 VM_Operation *op = VMThread::vm_operation();
395 tty->print_cr("Entering safepoint region: %s", (op != NULL) ? op->name() : "no vm operation");
396 }
398 RuntimeService::record_safepoint_synchronized();
399 if (PrintSafepointStatistics) {
400 update_statistics_on_sync_end(os::javaTimeNanos());
401 }
403 // Call stuff that needs to be run when a safepoint is just about to be completed
404 do_cleanup_tasks();
406 if (PrintSafepointStatistics) {
407 // Record how much time spend on the above cleanup tasks
408 update_statistics_on_cleanup_end(os::javaTimeNanos());
409 }
410 }
412 // Wake up all threads, so they are ready to resume execution after the safepoint
413 // operation has been carried out
414 void SafepointSynchronize::end() {
416 assert(Threads_lock->owned_by_self(), "must hold Threads_lock");
417 assert((_safepoint_counter & 0x1) == 1, "must be odd");
418 _safepoint_counter ++;
419 // memory fence isn't required here since an odd _safepoint_counter
420 // value can do no harm and a fence is issued below anyway.
422 DEBUG_ONLY(Thread* myThread = Thread::current();)
423 assert(myThread->is_VM_thread(), "Only VM thread can execute a safepoint");
425 if (PrintSafepointStatistics) {
426 end_statistics(os::javaTimeNanos());
427 }
429 #ifdef ASSERT
430 // A pending_exception cannot be installed during a safepoint. The threads
431 // may install an async exception after they come back from a safepoint into
432 // pending_exception after they unblock. But that should happen later.
433 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) {
434 assert (!(cur->has_pending_exception() &&
435 cur->safepoint_state()->is_at_poll_safepoint()),
436 "safepoint installed a pending exception");
437 }
438 #endif // ASSERT
440 if (PageArmed) {
441 // Make polling safepoint aware
442 os::make_polling_page_readable();
443 PageArmed = 0 ;
444 }
446 // Remove safepoint check from interpreter
447 Interpreter::ignore_safepoints();
449 {
450 MutexLocker mu(Safepoint_lock);
452 assert(_state == _synchronized, "must be synchronized before ending safepoint synchronization");
454 // Set to not synchronized, so the threads will not go into the signal_thread_blocked method
455 // when they get restarted.
456 _state = _not_synchronized;
457 OrderAccess::fence();
459 if (TraceSafepoint) {
460 tty->print_cr("Leaving safepoint region");
461 }
463 // Start suspended threads
464 for(JavaThread *current = Threads::first(); current; current = current->next()) {
465 // A problem occurring on Solaris is when attempting to restart threads
466 // the first #cpus - 1 go well, but then the VMThread is preempted when we get
467 // to the next one (since it has been running the longest). We then have
468 // to wait for a cpu to become available before we can continue restarting
469 // threads.
470 // FIXME: This causes the performance of the VM to degrade when active and with
471 // large numbers of threads. Apparently this is due to the synchronous nature
472 // of suspending threads.
473 //
474 // TODO-FIXME: the comments above are vestigial and no longer apply.
475 // Furthermore, using solaris' schedctl in this particular context confers no benefit
476 if (VMThreadHintNoPreempt) {
477 os::hint_no_preempt();
478 }
479 ThreadSafepointState* cur_state = current->safepoint_state();
480 assert(cur_state->type() != ThreadSafepointState::_running, "Thread not suspended at safepoint");
481 cur_state->restart();
482 assert(cur_state->is_running(), "safepoint state has not been reset");
483 }
485 RuntimeService::record_safepoint_end();
487 // Release threads lock, so threads can be created/destroyed again. It will also starts all threads
488 // blocked in signal_thread_blocked
489 Threads_lock->unlock();
491 }
492 #ifndef SERIALGC
493 // If there are any concurrent GC threads resume them.
494 if (UseConcMarkSweepGC) {
495 ConcurrentMarkSweepThread::desynchronize(false);
496 } else if (UseG1GC) {
497 ConcurrentGCThread::safepoint_desynchronize();
498 }
499 #endif // SERIALGC
500 // record this time so VMThread can keep track how much time has elasped
501 // since last safepoint.
502 _end_of_last_safepoint = os::javaTimeMillis();
503 }
505 bool SafepointSynchronize::is_cleanup_needed() {
506 // Need a safepoint if some inline cache buffers is non-empty
507 if (!InlineCacheBuffer::is_empty()) return true;
508 return false;
509 }
513 // Various cleaning tasks that should be done periodically at safepoints
514 void SafepointSynchronize::do_cleanup_tasks() {
515 {
516 TraceTime t1("deflating idle monitors", TraceSafepointCleanupTime);
517 ObjectSynchronizer::deflate_idle_monitors();
518 }
520 {
521 TraceTime t2("updating inline caches", TraceSafepointCleanupTime);
522 InlineCacheBuffer::update_inline_caches();
523 }
524 {
525 TraceTime t3("compilation policy safepoint handler", TraceSafepointCleanupTime);
526 CompilationPolicy::policy()->do_safepoint_work();
527 }
529 TraceTime t4("sweeping nmethods", TraceSafepointCleanupTime);
530 NMethodSweeper::scan_stacks();
532 // rotate log files?
533 if (UseGCLogFileRotation) {
534 gclog_or_tty->rotate_log();
535 }
536 }
539 bool SafepointSynchronize::safepoint_safe(JavaThread *thread, JavaThreadState state) {
540 switch(state) {
541 case _thread_in_native:
542 // native threads are safe if they have no java stack or have walkable stack
543 return !thread->has_last_Java_frame() || thread->frame_anchor()->walkable();
545 // blocked threads should have already have walkable stack
546 case _thread_blocked:
547 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "blocked and not walkable");
548 return true;
550 default:
551 return false;
552 }
553 }
556 // See if the thread is running inside a lazy critical native and
557 // update the thread critical count if so. Also set a suspend flag to
558 // cause the native wrapper to return into the JVM to do the unlock
559 // once the native finishes.
560 void SafepointSynchronize::check_for_lazy_critical_native(JavaThread *thread, JavaThreadState state) {
561 if (state == _thread_in_native &&
562 thread->has_last_Java_frame() &&
563 thread->frame_anchor()->walkable()) {
564 // This thread might be in a critical native nmethod so look at
565 // the top of the stack and increment the critical count if it
566 // is.
567 frame wrapper_frame = thread->last_frame();
568 CodeBlob* stub_cb = wrapper_frame.cb();
569 if (stub_cb != NULL &&
570 stub_cb->is_nmethod() &&
571 stub_cb->as_nmethod_or_null()->is_lazy_critical_native()) {
572 // A thread could potentially be in a critical native across
573 // more than one safepoint, so only update the critical state on
574 // the first one. When it returns it will perform the unlock.
575 if (!thread->do_critical_native_unlock()) {
576 #ifdef ASSERT
577 if (!thread->in_critical()) {
578 GC_locker::increment_debug_jni_lock_count();
579 }
580 #endif
581 thread->enter_critical();
582 // Make sure the native wrapper calls back on return to
583 // perform the needed critical unlock.
584 thread->set_critical_native_unlock();
585 }
586 }
587 }
588 }
592 // -------------------------------------------------------------------------------------------------------
593 // Implementation of Safepoint callback point
595 void SafepointSynchronize::block(JavaThread *thread) {
596 assert(thread != NULL, "thread must be set");
597 assert(thread->is_Java_thread(), "not a Java thread");
599 // Threads shouldn't block if they are in the middle of printing, but...
600 ttyLocker::break_tty_lock_for_safepoint(os::current_thread_id());
602 // Only bail from the block() call if the thread is gone from the
603 // thread list; starting to exit should still block.
604 if (thread->is_terminated()) {
605 // block current thread if we come here from native code when VM is gone
606 thread->block_if_vm_exited();
608 // otherwise do nothing
609 return;
610 }
612 JavaThreadState state = thread->thread_state();
613 thread->frame_anchor()->make_walkable(thread);
615 // Check that we have a valid thread_state at this point
616 switch(state) {
617 case _thread_in_vm_trans:
618 case _thread_in_Java: // From compiled code
620 // We are highly likely to block on the Safepoint_lock. In order to avoid blocking in this case,
621 // we pretend we are still in the VM.
622 thread->set_thread_state(_thread_in_vm);
624 if (is_synchronizing()) {
625 Atomic::inc (&TryingToBlock) ;
626 }
628 // We will always be holding the Safepoint_lock when we are examine the state
629 // of a thread. Hence, the instructions between the Safepoint_lock->lock() and
630 // Safepoint_lock->unlock() are happening atomic with regards to the safepoint code
631 Safepoint_lock->lock_without_safepoint_check();
632 if (is_synchronizing()) {
633 // Decrement the number of threads to wait for and signal vm thread
634 assert(_waiting_to_block > 0, "sanity check");
635 _waiting_to_block--;
636 thread->safepoint_state()->set_has_called_back(true);
638 DEBUG_ONLY(thread->set_visited_for_critical_count(true));
639 if (thread->in_critical()) {
640 // Notice that this thread is in a critical section
641 increment_jni_active_count();
642 }
644 // Consider (_waiting_to_block < 2) to pipeline the wakeup of the VM thread
645 if (_waiting_to_block == 0) {
646 Safepoint_lock->notify_all();
647 }
648 }
650 // We transition the thread to state _thread_blocked here, but
651 // we can't do our usual check for external suspension and then
652 // self-suspend after the lock_without_safepoint_check() call
653 // below because we are often called during transitions while
654 // we hold different locks. That would leave us suspended while
655 // holding a resource which results in deadlocks.
656 thread->set_thread_state(_thread_blocked);
657 Safepoint_lock->unlock();
659 // We now try to acquire the threads lock. Since this lock is hold by the VM thread during
660 // the entire safepoint, the threads will all line up here during the safepoint.
661 Threads_lock->lock_without_safepoint_check();
662 // restore original state. This is important if the thread comes from compiled code, so it
663 // will continue to execute with the _thread_in_Java state.
664 thread->set_thread_state(state);
665 Threads_lock->unlock();
666 break;
668 case _thread_in_native_trans:
669 case _thread_blocked_trans:
670 case _thread_new_trans:
671 if (thread->safepoint_state()->type() == ThreadSafepointState::_call_back) {
672 thread->print_thread_state();
673 fatal("Deadlock in safepoint code. "
674 "Should have called back to the VM before blocking.");
675 }
677 // We transition the thread to state _thread_blocked here, but
678 // we can't do our usual check for external suspension and then
679 // self-suspend after the lock_without_safepoint_check() call
680 // below because we are often called during transitions while
681 // we hold different locks. That would leave us suspended while
682 // holding a resource which results in deadlocks.
683 thread->set_thread_state(_thread_blocked);
685 // It is not safe to suspend a thread if we discover it is in _thread_in_native_trans. Hence,
686 // the safepoint code might still be waiting for it to block. We need to change the state here,
687 // so it can see that it is at a safepoint.
689 // Block until the safepoint operation is completed.
690 Threads_lock->lock_without_safepoint_check();
692 // Restore state
693 thread->set_thread_state(state);
695 Threads_lock->unlock();
696 break;
698 default:
699 fatal(err_msg("Illegal threadstate encountered: %d", state));
700 }
702 // Check for pending. async. exceptions or suspends - except if the
703 // thread was blocked inside the VM. has_special_runtime_exit_condition()
704 // is called last since it grabs a lock and we only want to do that when
705 // we must.
706 //
707 // Note: we never deliver an async exception at a polling point as the
708 // compiler may not have an exception handler for it. The polling
709 // code will notice the async and deoptimize and the exception will
710 // be delivered. (Polling at a return point is ok though). Sure is
711 // a lot of bother for a deprecated feature...
712 //
713 // We don't deliver an async exception if the thread state is
714 // _thread_in_native_trans so JNI functions won't be called with
715 // a surprising pending exception. If the thread state is going back to java,
716 // async exception is checked in check_special_condition_for_native_trans().
718 if (state != _thread_blocked_trans &&
719 state != _thread_in_vm_trans &&
720 thread->has_special_runtime_exit_condition()) {
721 thread->handle_special_runtime_exit_condition(
722 !thread->is_at_poll_safepoint() && (state != _thread_in_native_trans));
723 }
724 }
726 // ------------------------------------------------------------------------------------------------------
727 // Exception handlers
729 #ifndef PRODUCT
730 #ifdef _LP64
731 #define PTR_PAD ""
732 #else
733 #define PTR_PAD " "
734 #endif
736 static void print_ptrs(intptr_t oldptr, intptr_t newptr, bool wasoop) {
737 bool is_oop = newptr ? ((oop)newptr)->is_oop() : false;
738 tty->print_cr(PTR_FORMAT PTR_PAD " %s %c " PTR_FORMAT PTR_PAD " %s %s",
739 oldptr, wasoop?"oop":" ", oldptr == newptr ? ' ' : '!',
740 newptr, is_oop?"oop":" ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":" "));
741 }
743 static void print_longs(jlong oldptr, jlong newptr, bool wasoop) {
744 bool is_oop = newptr ? ((oop)(intptr_t)newptr)->is_oop() : false;
745 tty->print_cr(PTR64_FORMAT " %s %c " PTR64_FORMAT " %s %s",
746 oldptr, wasoop?"oop":" ", oldptr == newptr ? ' ' : '!',
747 newptr, is_oop?"oop":" ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":" "));
748 }
750 #ifdef SPARC
751 static void print_me(intptr_t *new_sp, intptr_t *old_sp, bool *was_oops) {
752 #ifdef _LP64
753 tty->print_cr("--------+------address-----+------before-----------+-------after----------+");
754 const int incr = 1; // Increment to skip a long, in units of intptr_t
755 #else
756 tty->print_cr("--------+--address-+------before-----------+-------after----------+");
757 const int incr = 2; // Increment to skip a long, in units of intptr_t
758 #endif
759 tty->print_cr("---SP---|");
760 for( int i=0; i<16; i++ ) {
761 tty->print("blob %c%d |"PTR_FORMAT" ","LO"[i>>3],i&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); }
762 tty->print_cr("--------|");
763 for( int i1=0; i1<frame::memory_parameter_word_sp_offset-16; i1++ ) {
764 tty->print("argv pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); }
765 tty->print(" pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++);
766 tty->print_cr("--------|");
767 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;
768 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;
769 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;
770 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;
771 tty->print_cr(" FSR |"PTR_FORMAT" "PTR64_FORMAT" "PTR64_FORMAT,new_sp,*(jlong*)old_sp,*(jlong*)new_sp);
772 old_sp += incr; new_sp += incr; was_oops += incr;
773 // Skip the floats
774 tty->print_cr("--Float-|"PTR_FORMAT,new_sp);
775 tty->print_cr("---FP---|");
776 old_sp += incr*32; new_sp += incr*32; was_oops += incr*32;
777 for( int i2=0; i2<16; i2++ ) {
778 tty->print("call %c%d |"PTR_FORMAT" ","LI"[i2>>3],i2&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); }
779 tty->print_cr("");
780 }
781 #endif // SPARC
782 #endif // PRODUCT
785 void SafepointSynchronize::handle_polling_page_exception(JavaThread *thread) {
786 assert(thread->is_Java_thread(), "polling reference encountered by VM thread");
787 assert(thread->thread_state() == _thread_in_Java, "should come from Java code");
788 assert(SafepointSynchronize::is_synchronizing(), "polling encountered outside safepoint synchronization");
790 // Uncomment this to get some serious before/after printing of the
791 // Sparc safepoint-blob frame structure.
792 /*
793 intptr_t* sp = thread->last_Java_sp();
794 intptr_t stack_copy[150];
795 for( int i=0; i<150; i++ ) stack_copy[i] = sp[i];
796 bool was_oops[150];
797 for( int i=0; i<150; i++ )
798 was_oops[i] = stack_copy[i] ? ((oop)stack_copy[i])->is_oop() : false;
799 */
801 if (ShowSafepointMsgs) {
802 tty->print("handle_polling_page_exception: ");
803 }
805 if (PrintSafepointStatistics) {
806 inc_page_trap_count();
807 }
809 ThreadSafepointState* state = thread->safepoint_state();
811 state->handle_polling_page_exception();
812 // print_me(sp,stack_copy,was_oops);
813 }
816 void SafepointSynchronize::print_safepoint_timeout(SafepointTimeoutReason reason) {
817 if (!timeout_error_printed) {
818 timeout_error_printed = true;
819 // Print out the thread infor which didn't reach the safepoint for debugging
820 // purposes (useful when there are lots of threads in the debugger).
821 tty->print_cr("");
822 tty->print_cr("# SafepointSynchronize::begin: Timeout detected:");
823 if (reason == _spinning_timeout) {
824 tty->print_cr("# SafepointSynchronize::begin: Timed out while spinning to reach a safepoint.");
825 } else if (reason == _blocking_timeout) {
826 tty->print_cr("# SafepointSynchronize::begin: Timed out while waiting for threads to stop.");
827 }
829 tty->print_cr("# SafepointSynchronize::begin: Threads which did not reach the safepoint:");
830 ThreadSafepointState *cur_state;
831 ResourceMark rm;
832 for(JavaThread *cur_thread = Threads::first(); cur_thread;
833 cur_thread = cur_thread->next()) {
834 cur_state = cur_thread->safepoint_state();
836 if (cur_thread->thread_state() != _thread_blocked &&
837 ((reason == _spinning_timeout && cur_state->is_running()) ||
838 (reason == _blocking_timeout && !cur_state->has_called_back()))) {
839 tty->print("# ");
840 cur_thread->print();
841 tty->print_cr("");
842 }
843 }
844 tty->print_cr("# SafepointSynchronize::begin: (End of list)");
845 }
847 // To debug the long safepoint, specify both DieOnSafepointTimeout &
848 // ShowMessageBoxOnError.
849 if (DieOnSafepointTimeout) {
850 char msg[1024];
851 VM_Operation *op = VMThread::vm_operation();
852 sprintf(msg, "Safepoint sync time longer than " INTX_FORMAT "ms detected when executing %s.",
853 SafepointTimeoutDelay,
854 op != NULL ? op->name() : "no vm operation");
855 fatal(msg);
856 }
857 }
860 // -------------------------------------------------------------------------------------------------------
861 // Implementation of ThreadSafepointState
863 ThreadSafepointState::ThreadSafepointState(JavaThread *thread) {
864 _thread = thread;
865 _type = _running;
866 _has_called_back = false;
867 _at_poll_safepoint = false;
868 }
870 void ThreadSafepointState::create(JavaThread *thread) {
871 ThreadSafepointState *state = new ThreadSafepointState(thread);
872 thread->set_safepoint_state(state);
873 }
875 void ThreadSafepointState::destroy(JavaThread *thread) {
876 if (thread->safepoint_state()) {
877 delete(thread->safepoint_state());
878 thread->set_safepoint_state(NULL);
879 }
880 }
882 void ThreadSafepointState::examine_state_of_thread() {
883 assert(is_running(), "better be running or just have hit safepoint poll");
885 JavaThreadState state = _thread->thread_state();
887 // Save the state at the start of safepoint processing.
888 _orig_thread_state = state;
890 // Check for a thread that is suspended. Note that thread resume tries
891 // to grab the Threads_lock which we own here, so a thread cannot be
892 // resumed during safepoint synchronization.
894 // We check to see if this thread is suspended without locking to
895 // avoid deadlocking with a third thread that is waiting for this
896 // thread to be suspended. The third thread can notice the safepoint
897 // that we're trying to start at the beginning of its SR_lock->wait()
898 // call. If that happens, then the third thread will block on the
899 // safepoint while still holding the underlying SR_lock. We won't be
900 // able to get the SR_lock and we'll deadlock.
901 //
902 // We don't need to grab the SR_lock here for two reasons:
903 // 1) The suspend flags are both volatile and are set with an
904 // Atomic::cmpxchg() call so we should see the suspended
905 // state right away.
906 // 2) We're being called from the safepoint polling loop; if
907 // we don't see the suspended state on this iteration, then
908 // we'll come around again.
909 //
910 bool is_suspended = _thread->is_ext_suspended();
911 if (is_suspended) {
912 roll_forward(_at_safepoint);
913 return;
914 }
916 // Some JavaThread states have an initial safepoint state of
917 // running, but are actually at a safepoint. We will happily
918 // agree and update the safepoint state here.
919 if (SafepointSynchronize::safepoint_safe(_thread, state)) {
920 SafepointSynchronize::check_for_lazy_critical_native(_thread, state);
921 roll_forward(_at_safepoint);
922 return;
923 }
925 if (state == _thread_in_vm) {
926 roll_forward(_call_back);
927 return;
928 }
930 // All other thread states will continue to run until they
931 // transition and self-block in state _blocked
932 // Safepoint polling in compiled code causes the Java threads to do the same.
933 // Note: new threads may require a malloc so they must be allowed to finish
935 assert(is_running(), "examine_state_of_thread on non-running thread");
936 return;
937 }
939 // Returns true is thread could not be rolled forward at present position.
940 void ThreadSafepointState::roll_forward(suspend_type type) {
941 _type = type;
943 switch(_type) {
944 case _at_safepoint:
945 SafepointSynchronize::signal_thread_at_safepoint();
946 DEBUG_ONLY(_thread->set_visited_for_critical_count(true));
947 if (_thread->in_critical()) {
948 // Notice that this thread is in a critical section
949 SafepointSynchronize::increment_jni_active_count();
950 }
951 break;
953 case _call_back:
954 set_has_called_back(false);
955 break;
957 case _running:
958 default:
959 ShouldNotReachHere();
960 }
961 }
963 void ThreadSafepointState::restart() {
964 switch(type()) {
965 case _at_safepoint:
966 case _call_back:
967 break;
969 case _running:
970 default:
971 tty->print_cr("restart thread "INTPTR_FORMAT" with state %d",
972 _thread, _type);
973 _thread->print();
974 ShouldNotReachHere();
975 }
976 _type = _running;
977 set_has_called_back(false);
978 }
981 void ThreadSafepointState::print_on(outputStream *st) const {
982 const char *s;
984 switch(_type) {
985 case _running : s = "_running"; break;
986 case _at_safepoint : s = "_at_safepoint"; break;
987 case _call_back : s = "_call_back"; break;
988 default:
989 ShouldNotReachHere();
990 }
992 st->print_cr("Thread: " INTPTR_FORMAT
993 " [0x%2x] State: %s _has_called_back %d _at_poll_safepoint %d",
994 _thread, _thread->osthread()->thread_id(), s, _has_called_back,
995 _at_poll_safepoint);
997 _thread->print_thread_state_on(st);
998 }
1001 // ---------------------------------------------------------------------------------------------------------------------
1003 // Block the thread at the safepoint poll or poll return.
1004 void ThreadSafepointState::handle_polling_page_exception() {
1006 // Check state. block() will set thread state to thread_in_vm which will
1007 // cause the safepoint state _type to become _call_back.
1008 assert(type() == ThreadSafepointState::_running,
1009 "polling page exception on thread not running state");
1011 // Step 1: Find the nmethod from the return address
1012 if (ShowSafepointMsgs && Verbose) {
1013 tty->print_cr("Polling page exception at " INTPTR_FORMAT, thread()->saved_exception_pc());
1014 }
1015 address real_return_addr = thread()->saved_exception_pc();
1017 CodeBlob *cb = CodeCache::find_blob(real_return_addr);
1018 assert(cb != NULL && cb->is_nmethod(), "return address should be in nmethod");
1019 nmethod* nm = (nmethod*)cb;
1021 // Find frame of caller
1022 frame stub_fr = thread()->last_frame();
1023 CodeBlob* stub_cb = stub_fr.cb();
1024 assert(stub_cb->is_safepoint_stub(), "must be a safepoint stub");
1025 RegisterMap map(thread(), true);
1026 frame caller_fr = stub_fr.sender(&map);
1028 // Should only be poll_return or poll
1029 assert( nm->is_at_poll_or_poll_return(real_return_addr), "should not be at call" );
1031 // This is a poll immediately before a return. The exception handling code
1032 // has already had the effect of causing the return to occur, so the execution
1033 // will continue immediately after the call. In addition, the oopmap at the
1034 // return point does not mark the return value as an oop (if it is), so
1035 // it needs a handle here to be updated.
1036 if( nm->is_at_poll_return(real_return_addr) ) {
1037 // See if return type is an oop.
1038 bool return_oop = nm->method()->is_returning_oop();
1039 Handle return_value;
1040 if (return_oop) {
1041 // The oop result has been saved on the stack together with all
1042 // the other registers. In order to preserve it over GCs we need
1043 // to keep it in a handle.
1044 oop result = caller_fr.saved_oop_result(&map);
1045 assert(result == NULL || result->is_oop(), "must be oop");
1046 return_value = Handle(thread(), result);
1047 assert(Universe::heap()->is_in_or_null(result), "must be heap pointer");
1048 }
1050 // Block the thread
1051 SafepointSynchronize::block(thread());
1053 // restore oop result, if any
1054 if (return_oop) {
1055 caller_fr.set_saved_oop_result(&map, return_value());
1056 }
1057 }
1059 // This is a safepoint poll. Verify the return address and block.
1060 else {
1061 set_at_poll_safepoint(true);
1063 // verify the blob built the "return address" correctly
1064 assert(real_return_addr == caller_fr.pc(), "must match");
1066 // Block the thread
1067 SafepointSynchronize::block(thread());
1068 set_at_poll_safepoint(false);
1070 // If we have a pending async exception deoptimize the frame
1071 // as otherwise we may never deliver it.
1072 if (thread()->has_async_condition()) {
1073 ThreadInVMfromJavaNoAsyncException __tiv(thread());
1074 Deoptimization::deoptimize_frame(thread(), caller_fr.id());
1075 }
1077 // If an exception has been installed we must check for a pending deoptimization
1078 // Deoptimize frame if exception has been thrown.
1080 if (thread()->has_pending_exception() ) {
1081 RegisterMap map(thread(), true);
1082 frame caller_fr = stub_fr.sender(&map);
1083 if (caller_fr.is_deoptimized_frame()) {
1084 // The exception patch will destroy registers that are still
1085 // live and will be needed during deoptimization. Defer the
1086 // Async exception should have defered the exception until the
1087 // next safepoint which will be detected when we get into
1088 // the interpreter so if we have an exception now things
1089 // are messed up.
1091 fatal("Exception installed and deoptimization is pending");
1092 }
1093 }
1094 }
1095 }
1098 //
1099 // Statistics & Instrumentations
1100 //
1101 SafepointSynchronize::SafepointStats* SafepointSynchronize::_safepoint_stats = NULL;
1102 jlong SafepointSynchronize::_safepoint_begin_time = 0;
1103 int SafepointSynchronize::_cur_stat_index = 0;
1104 julong SafepointSynchronize::_safepoint_reasons[VM_Operation::VMOp_Terminating];
1105 julong SafepointSynchronize::_coalesced_vmop_count = 0;
1106 jlong SafepointSynchronize::_max_sync_time = 0;
1107 jlong SafepointSynchronize::_max_vmop_time = 0;
1108 float SafepointSynchronize::_ts_of_current_safepoint = 0.0f;
1110 static jlong cleanup_end_time = 0;
1111 static bool need_to_track_page_armed_status = false;
1112 static bool init_done = false;
1114 // Helper method to print the header.
1115 static void print_header() {
1116 tty->print(" vmop "
1117 "[threads: total initially_running wait_to_block] ");
1118 tty->print("[time: spin block sync cleanup vmop] ");
1120 // no page armed status printed out if it is always armed.
1121 if (need_to_track_page_armed_status) {
1122 tty->print("page_armed ");
1123 }
1125 tty->print_cr("page_trap_count");
1126 }
1128 void SafepointSynchronize::deferred_initialize_stat() {
1129 if (init_done) return;
1131 if (PrintSafepointStatisticsCount <= 0) {
1132 fatal("Wrong PrintSafepointStatisticsCount");
1133 }
1135 // If PrintSafepointStatisticsTimeout is specified, the statistics data will
1136 // be printed right away, in which case, _safepoint_stats will regress to
1137 // a single element array. Otherwise, it is a circular ring buffer with default
1138 // size of PrintSafepointStatisticsCount.
1139 int stats_array_size;
1140 if (PrintSafepointStatisticsTimeout > 0) {
1141 stats_array_size = 1;
1142 PrintSafepointStatistics = true;
1143 } else {
1144 stats_array_size = PrintSafepointStatisticsCount;
1145 }
1146 _safepoint_stats = (SafepointStats*)os::malloc(stats_array_size
1147 * sizeof(SafepointStats));
1148 guarantee(_safepoint_stats != NULL,
1149 "not enough memory for safepoint instrumentation data");
1151 if (UseCompilerSafepoints && DeferPollingPageLoopCount >= 0) {
1152 need_to_track_page_armed_status = true;
1153 }
1154 init_done = true;
1155 }
1157 void SafepointSynchronize::begin_statistics(int nof_threads, int nof_running) {
1158 assert(init_done, "safepoint statistics array hasn't been initialized");
1159 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
1161 spstat->_time_stamp = _ts_of_current_safepoint;
1163 VM_Operation *op = VMThread::vm_operation();
1164 spstat->_vmop_type = (op != NULL ? op->type() : -1);
1165 if (op != NULL) {
1166 _safepoint_reasons[spstat->_vmop_type]++;
1167 }
1169 spstat->_nof_total_threads = nof_threads;
1170 spstat->_nof_initial_running_threads = nof_running;
1171 spstat->_nof_threads_hit_page_trap = 0;
1173 // Records the start time of spinning. The real time spent on spinning
1174 // will be adjusted when spin is done. Same trick is applied for time
1175 // spent on waiting for threads to block.
1176 if (nof_running != 0) {
1177 spstat->_time_to_spin = os::javaTimeNanos();
1178 } else {
1179 spstat->_time_to_spin = 0;
1180 }
1181 }
1183 void SafepointSynchronize::update_statistics_on_spin_end() {
1184 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
1186 jlong cur_time = os::javaTimeNanos();
1188 spstat->_nof_threads_wait_to_block = _waiting_to_block;
1189 if (spstat->_nof_initial_running_threads != 0) {
1190 spstat->_time_to_spin = cur_time - spstat->_time_to_spin;
1191 }
1193 if (need_to_track_page_armed_status) {
1194 spstat->_page_armed = (PageArmed == 1);
1195 }
1197 // Records the start time of waiting for to block. Updated when block is done.
1198 if (_waiting_to_block != 0) {
1199 spstat->_time_to_wait_to_block = cur_time;
1200 } else {
1201 spstat->_time_to_wait_to_block = 0;
1202 }
1203 }
1205 void SafepointSynchronize::update_statistics_on_sync_end(jlong end_time) {
1206 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
1208 if (spstat->_nof_threads_wait_to_block != 0) {
1209 spstat->_time_to_wait_to_block = end_time -
1210 spstat->_time_to_wait_to_block;
1211 }
1213 // Records the end time of sync which will be used to calculate the total
1214 // vm operation time. Again, the real time spending in syncing will be deducted
1215 // from the start of the sync time later when end_statistics is called.
1216 spstat->_time_to_sync = end_time - _safepoint_begin_time;
1217 if (spstat->_time_to_sync > _max_sync_time) {
1218 _max_sync_time = spstat->_time_to_sync;
1219 }
1221 spstat->_time_to_do_cleanups = end_time;
1222 }
1224 void SafepointSynchronize::update_statistics_on_cleanup_end(jlong end_time) {
1225 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
1227 // Record how long spent in cleanup tasks.
1228 spstat->_time_to_do_cleanups = end_time - spstat->_time_to_do_cleanups;
1230 cleanup_end_time = end_time;
1231 }
1233 void SafepointSynchronize::end_statistics(jlong vmop_end_time) {
1234 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
1236 // Update the vm operation time.
1237 spstat->_time_to_exec_vmop = vmop_end_time - cleanup_end_time;
1238 if (spstat->_time_to_exec_vmop > _max_vmop_time) {
1239 _max_vmop_time = spstat->_time_to_exec_vmop;
1240 }
1241 // Only the sync time longer than the specified
1242 // PrintSafepointStatisticsTimeout will be printed out right away.
1243 // By default, it is -1 meaning all samples will be put into the list.
1244 if ( PrintSafepointStatisticsTimeout > 0) {
1245 if (spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) {
1246 print_statistics();
1247 }
1248 } else {
1249 // The safepoint statistics will be printed out when the _safepoin_stats
1250 // array fills up.
1251 if (_cur_stat_index == PrintSafepointStatisticsCount - 1) {
1252 print_statistics();
1253 _cur_stat_index = 0;
1254 } else {
1255 _cur_stat_index++;
1256 }
1257 }
1258 }
1260 void SafepointSynchronize::print_statistics() {
1261 SafepointStats* sstats = _safepoint_stats;
1263 for (int index = 0; index <= _cur_stat_index; index++) {
1264 if (index % 30 == 0) {
1265 print_header();
1266 }
1267 sstats = &_safepoint_stats[index];
1268 tty->print("%.3f: ", sstats->_time_stamp);
1269 tty->print("%-26s ["
1270 INT32_FORMAT_W(8)INT32_FORMAT_W(11)INT32_FORMAT_W(15)
1271 " ] ",
1272 sstats->_vmop_type == -1 ? "no vm operation" :
1273 VM_Operation::name(sstats->_vmop_type),
1274 sstats->_nof_total_threads,
1275 sstats->_nof_initial_running_threads,
1276 sstats->_nof_threads_wait_to_block);
1277 // "/ MICROUNITS " is to convert the unit from nanos to millis.
1278 tty->print(" ["
1279 INT64_FORMAT_W(6)INT64_FORMAT_W(6)
1280 INT64_FORMAT_W(6)INT64_FORMAT_W(6)
1281 INT64_FORMAT_W(6)" ] ",
1282 sstats->_time_to_spin / MICROUNITS,
1283 sstats->_time_to_wait_to_block / MICROUNITS,
1284 sstats->_time_to_sync / MICROUNITS,
1285 sstats->_time_to_do_cleanups / MICROUNITS,
1286 sstats->_time_to_exec_vmop / MICROUNITS);
1288 if (need_to_track_page_armed_status) {
1289 tty->print(INT32_FORMAT" ", sstats->_page_armed);
1290 }
1291 tty->print_cr(INT32_FORMAT" ", sstats->_nof_threads_hit_page_trap);
1292 }
1293 }
1295 // This method will be called when VM exits. It will first call
1296 // print_statistics to print out the rest of the sampling. Then
1297 // it tries to summarize the sampling.
1298 void SafepointSynchronize::print_stat_on_exit() {
1299 if (_safepoint_stats == NULL) return;
1301 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
1303 // During VM exit, end_statistics may not get called and in that
1304 // case, if the sync time is less than PrintSafepointStatisticsTimeout,
1305 // don't print it out.
1306 // Approximate the vm op time.
1307 _safepoint_stats[_cur_stat_index]._time_to_exec_vmop =
1308 os::javaTimeNanos() - cleanup_end_time;
1310 if ( PrintSafepointStatisticsTimeout < 0 ||
1311 spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) {
1312 print_statistics();
1313 }
1314 tty->print_cr("");
1316 // Print out polling page sampling status.
1317 if (!need_to_track_page_armed_status) {
1318 if (UseCompilerSafepoints) {
1319 tty->print_cr("Polling page always armed");
1320 }
1321 } else {
1322 tty->print_cr("Defer polling page loop count = %d\n",
1323 DeferPollingPageLoopCount);
1324 }
1326 for (int index = 0; index < VM_Operation::VMOp_Terminating; index++) {
1327 if (_safepoint_reasons[index] != 0) {
1328 tty->print_cr("%-26s"UINT64_FORMAT_W(10), VM_Operation::name(index),
1329 _safepoint_reasons[index]);
1330 }
1331 }
1333 tty->print_cr(UINT64_FORMAT_W(5)" VM operations coalesced during safepoint",
1334 _coalesced_vmop_count);
1335 tty->print_cr("Maximum sync time "INT64_FORMAT_W(5)" ms",
1336 _max_sync_time / MICROUNITS);
1337 tty->print_cr("Maximum vm operation time (except for Exit VM operation) "
1338 INT64_FORMAT_W(5)" ms",
1339 _max_vmop_time / MICROUNITS);
1340 }
1342 // ------------------------------------------------------------------------------------------------
1343 // Non-product code
1345 #ifndef PRODUCT
1347 void SafepointSynchronize::print_state() {
1348 if (_state == _not_synchronized) {
1349 tty->print_cr("not synchronized");
1350 } else if (_state == _synchronizing || _state == _synchronized) {
1351 tty->print_cr("State: %s", (_state == _synchronizing) ? "synchronizing" :
1352 "synchronized");
1354 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) {
1355 cur->safepoint_state()->print();
1356 }
1357 }
1358 }
1360 void SafepointSynchronize::safepoint_msg(const char* format, ...) {
1361 if (ShowSafepointMsgs) {
1362 va_list ap;
1363 va_start(ap, format);
1364 tty->vprint_cr(format, ap);
1365 va_end(ap);
1366 }
1367 }
1369 #endif // !PRODUCT