Wed, 15 Feb 2012 16:29:40 -0800
7142680: default GC affected by jvm path
Summary: Removed old tiered code
Reviewed-by: never, kvn
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 }
223 #endif // ASSERT
225 if (SafepointTimeout)
226 safepoint_limit_time = os::javaTimeNanos() + (jlong)SafepointTimeoutDelay * MICROUNITS;
228 // Iterate through all threads until it have been determined how to stop them all at a safepoint
229 unsigned int iterations = 0;
230 int steps = 0 ;
231 while(still_running > 0) {
232 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) {
233 assert(!cur->is_ConcurrentGC_thread(), "A concurrent GC thread is unexpectly being suspended");
234 ThreadSafepointState *cur_state = cur->safepoint_state();
235 if (cur_state->is_running()) {
236 cur_state->examine_state_of_thread();
237 if (!cur_state->is_running()) {
238 still_running--;
239 // consider adjusting steps downward:
240 // steps = 0
241 // steps -= NNN
242 // steps >>= 1
243 // steps = MIN(steps, 2000-100)
244 // if (iterations != 0) steps -= NNN
245 }
246 if (TraceSafepoint && Verbose) cur_state->print();
247 }
248 }
250 if (PrintSafepointStatistics && iterations == 0) {
251 begin_statistics(nof_threads, still_running);
252 }
254 if (still_running > 0) {
255 // Check for if it takes to long
256 if (SafepointTimeout && safepoint_limit_time < os::javaTimeNanos()) {
257 print_safepoint_timeout(_spinning_timeout);
258 }
260 // Spin to avoid context switching.
261 // There's a tension between allowing the mutators to run (and rendezvous)
262 // vs spinning. As the VM thread spins, wasting cycles, it consumes CPU that
263 // a mutator might otherwise use profitably to reach a safepoint. Excessive
264 // spinning by the VM thread on a saturated system can increase rendezvous latency.
265 // Blocking or yielding incur their own penalties in the form of context switching
266 // and the resultant loss of $ residency.
267 //
268 // Further complicating matters is that yield() does not work as naively expected
269 // on many platforms -- yield() does not guarantee that any other ready threads
270 // will run. As such we revert yield_all() after some number of iterations.
271 // Yield_all() is implemented as a short unconditional sleep on some platforms.
272 // Typical operating systems round a "short" sleep period up to 10 msecs, so sleeping
273 // can actually increase the time it takes the VM thread to detect that a system-wide
274 // stop-the-world safepoint has been reached. In a pathological scenario such as that
275 // described in CR6415670 the VMthread may sleep just before the mutator(s) become safe.
276 // In that case the mutators will be stalled waiting for the safepoint to complete and the
277 // the VMthread will be sleeping, waiting for the mutators to rendezvous. The VMthread
278 // will eventually wake up and detect that all mutators are safe, at which point
279 // we'll again make progress.
280 //
281 // Beware too that that the VMThread typically runs at elevated priority.
282 // Its default priority is higher than the default mutator priority.
283 // Obviously, this complicates spinning.
284 //
285 // Note too that on Windows XP SwitchThreadTo() has quite different behavior than Sleep(0).
286 // Sleep(0) will _not yield to lower priority threads, while SwitchThreadTo() will.
287 //
288 // See the comments in synchronizer.cpp for additional remarks on spinning.
289 //
290 // In the future we might:
291 // 1. Modify the safepoint scheme to avoid potentally unbounded spinning.
292 // This is tricky as the path used by a thread exiting the JVM (say on
293 // on JNI call-out) simply stores into its state field. The burden
294 // is placed on the VM thread, which must poll (spin).
295 // 2. Find something useful to do while spinning. If the safepoint is GC-related
296 // we might aggressively scan the stacks of threads that are already safe.
297 // 3. Use Solaris schedctl to examine the state of the still-running mutators.
298 // If all the mutators are ONPROC there's no reason to sleep or yield.
299 // 4. YieldTo() any still-running mutators that are ready but OFFPROC.
300 // 5. Check system saturation. If the system is not fully saturated then
301 // simply spin and avoid sleep/yield.
302 // 6. As still-running mutators rendezvous they could unpark the sleeping
303 // VMthread. This works well for still-running mutators that become
304 // safe. The VMthread must still poll for mutators that call-out.
305 // 7. Drive the policy on time-since-begin instead of iterations.
306 // 8. Consider making the spin duration a function of the # of CPUs:
307 // Spin = (((ncpus-1) * M) + K) + F(still_running)
308 // Alternately, instead of counting iterations of the outer loop
309 // we could count the # of threads visited in the inner loop, above.
310 // 9. On windows consider using the return value from SwitchThreadTo()
311 // to drive subsequent spin/SwitchThreadTo()/Sleep(N) decisions.
313 if (UseCompilerSafepoints && int(iterations) == DeferPollingPageLoopCount) {
314 guarantee (PageArmed == 0, "invariant") ;
315 PageArmed = 1 ;
316 os::make_polling_page_unreadable();
317 }
319 // Instead of (ncpus > 1) consider either (still_running < (ncpus + EPSILON)) or
320 // ((still_running + _waiting_to_block - TryingToBlock)) < ncpus)
321 ++steps ;
322 if (ncpus > 1 && steps < SafepointSpinBeforeYield) {
323 SpinPause() ; // MP-Polite spin
324 } else
325 if (steps < DeferThrSuspendLoopCount) {
326 os::NakedYield() ;
327 } else {
328 os::yield_all(steps) ;
329 // Alternately, the VM thread could transiently depress its scheduling priority or
330 // transiently increase the priority of the tardy mutator(s).
331 }
333 iterations ++ ;
334 }
335 assert(iterations < (uint)max_jint, "We have been iterating in the safepoint loop too long");
336 }
337 assert(still_running == 0, "sanity check");
339 if (PrintSafepointStatistics) {
340 update_statistics_on_spin_end();
341 }
343 // wait until all threads are stopped
344 while (_waiting_to_block > 0) {
345 if (TraceSafepoint) tty->print_cr("Waiting for %d thread(s) to block", _waiting_to_block);
346 if (!SafepointTimeout || timeout_error_printed) {
347 Safepoint_lock->wait(true); // true, means with no safepoint checks
348 } else {
349 // Compute remaining time
350 jlong remaining_time = safepoint_limit_time - os::javaTimeNanos();
352 // If there is no remaining time, then there is an error
353 if (remaining_time < 0 || Safepoint_lock->wait(true, remaining_time / MICROUNITS)) {
354 print_safepoint_timeout(_blocking_timeout);
355 }
356 }
357 }
358 assert(_waiting_to_block == 0, "sanity check");
360 #ifndef PRODUCT
361 if (SafepointTimeout) {
362 jlong current_time = os::javaTimeNanos();
363 if (safepoint_limit_time < current_time) {
364 tty->print_cr("# SafepointSynchronize: Finished after "
365 INT64_FORMAT_W(6) " ms",
366 ((current_time - safepoint_limit_time) / MICROUNITS +
367 SafepointTimeoutDelay));
368 }
369 }
370 #endif
372 assert((_safepoint_counter & 0x1) == 0, "must be even");
373 assert(Threads_lock->owned_by_self(), "must hold Threads_lock");
374 _safepoint_counter ++;
376 // Record state
377 _state = _synchronized;
379 OrderAccess::fence();
381 // Update the count of active JNI critical regions
382 GC_locker::set_jni_lock_count(_current_jni_active_count);
384 if (TraceSafepoint) {
385 VM_Operation *op = VMThread::vm_operation();
386 tty->print_cr("Entering safepoint region: %s", (op != NULL) ? op->name() : "no vm operation");
387 }
389 RuntimeService::record_safepoint_synchronized();
390 if (PrintSafepointStatistics) {
391 update_statistics_on_sync_end(os::javaTimeNanos());
392 }
394 // Call stuff that needs to be run when a safepoint is just about to be completed
395 do_cleanup_tasks();
397 if (PrintSafepointStatistics) {
398 // Record how much time spend on the above cleanup tasks
399 update_statistics_on_cleanup_end(os::javaTimeNanos());
400 }
401 }
403 // Wake up all threads, so they are ready to resume execution after the safepoint
404 // operation has been carried out
405 void SafepointSynchronize::end() {
407 assert(Threads_lock->owned_by_self(), "must hold Threads_lock");
408 assert((_safepoint_counter & 0x1) == 1, "must be odd");
409 _safepoint_counter ++;
410 // memory fence isn't required here since an odd _safepoint_counter
411 // value can do no harm and a fence is issued below anyway.
413 DEBUG_ONLY(Thread* myThread = Thread::current();)
414 assert(myThread->is_VM_thread(), "Only VM thread can execute a safepoint");
416 if (PrintSafepointStatistics) {
417 end_statistics(os::javaTimeNanos());
418 }
420 #ifdef ASSERT
421 // A pending_exception cannot be installed during a safepoint. The threads
422 // may install an async exception after they come back from a safepoint into
423 // pending_exception after they unblock. But that should happen later.
424 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) {
425 assert (!(cur->has_pending_exception() &&
426 cur->safepoint_state()->is_at_poll_safepoint()),
427 "safepoint installed a pending exception");
428 }
429 #endif // ASSERT
431 if (PageArmed) {
432 // Make polling safepoint aware
433 os::make_polling_page_readable();
434 PageArmed = 0 ;
435 }
437 // Remove safepoint check from interpreter
438 Interpreter::ignore_safepoints();
440 {
441 MutexLocker mu(Safepoint_lock);
443 assert(_state == _synchronized, "must be synchronized before ending safepoint synchronization");
445 // Set to not synchronized, so the threads will not go into the signal_thread_blocked method
446 // when they get restarted.
447 _state = _not_synchronized;
448 OrderAccess::fence();
450 if (TraceSafepoint) {
451 tty->print_cr("Leaving safepoint region");
452 }
454 // Start suspended threads
455 for(JavaThread *current = Threads::first(); current; current = current->next()) {
456 // A problem occurring on Solaris is when attempting to restart threads
457 // the first #cpus - 1 go well, but then the VMThread is preempted when we get
458 // to the next one (since it has been running the longest). We then have
459 // to wait for a cpu to become available before we can continue restarting
460 // threads.
461 // FIXME: This causes the performance of the VM to degrade when active and with
462 // large numbers of threads. Apparently this is due to the synchronous nature
463 // of suspending threads.
464 //
465 // TODO-FIXME: the comments above are vestigial and no longer apply.
466 // Furthermore, using solaris' schedctl in this particular context confers no benefit
467 if (VMThreadHintNoPreempt) {
468 os::hint_no_preempt();
469 }
470 ThreadSafepointState* cur_state = current->safepoint_state();
471 assert(cur_state->type() != ThreadSafepointState::_running, "Thread not suspended at safepoint");
472 cur_state->restart();
473 assert(cur_state->is_running(), "safepoint state has not been reset");
474 }
476 RuntimeService::record_safepoint_end();
478 // Release threads lock, so threads can be created/destroyed again. It will also starts all threads
479 // blocked in signal_thread_blocked
480 Threads_lock->unlock();
482 }
483 #ifndef SERIALGC
484 // If there are any concurrent GC threads resume them.
485 if (UseConcMarkSweepGC) {
486 ConcurrentMarkSweepThread::desynchronize(false);
487 } else if (UseG1GC) {
488 ConcurrentGCThread::safepoint_desynchronize();
489 }
490 #endif // SERIALGC
491 // record this time so VMThread can keep track how much time has elasped
492 // since last safepoint.
493 _end_of_last_safepoint = os::javaTimeMillis();
494 }
496 bool SafepointSynchronize::is_cleanup_needed() {
497 // Need a safepoint if some inline cache buffers is non-empty
498 if (!InlineCacheBuffer::is_empty()) return true;
499 return false;
500 }
504 // Various cleaning tasks that should be done periodically at safepoints
505 void SafepointSynchronize::do_cleanup_tasks() {
506 {
507 TraceTime t1("deflating idle monitors", TraceSafepointCleanupTime);
508 ObjectSynchronizer::deflate_idle_monitors();
509 }
511 {
512 TraceTime t2("updating inline caches", TraceSafepointCleanupTime);
513 InlineCacheBuffer::update_inline_caches();
514 }
515 {
516 TraceTime t3("compilation policy safepoint handler", TraceSafepointCleanupTime);
517 CompilationPolicy::policy()->do_safepoint_work();
518 }
520 TraceTime t4("sweeping nmethods", TraceSafepointCleanupTime);
521 NMethodSweeper::scan_stacks();
523 // rotate log files?
524 if (UseGCLogFileRotation) {
525 gclog_or_tty->rotate_log();
526 }
527 }
530 bool SafepointSynchronize::safepoint_safe(JavaThread *thread, JavaThreadState state) {
531 switch(state) {
532 case _thread_in_native:
533 // native threads are safe if they have no java stack or have walkable stack
534 return !thread->has_last_Java_frame() || thread->frame_anchor()->walkable();
536 // blocked threads should have already have walkable stack
537 case _thread_blocked:
538 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "blocked and not walkable");
539 return true;
541 default:
542 return false;
543 }
544 }
547 // See if the thread is running inside a lazy critical native and
548 // update the thread critical count if so. Also set a suspend flag to
549 // cause the native wrapper to return into the JVM to do the unlock
550 // once the native finishes.
551 void SafepointSynchronize::check_for_lazy_critical_native(JavaThread *thread, JavaThreadState state) {
552 if (state == _thread_in_native &&
553 thread->has_last_Java_frame() &&
554 thread->frame_anchor()->walkable()) {
555 // This thread might be in a critical native nmethod so look at
556 // the top of the stack and increment the critical count if it
557 // is.
558 frame wrapper_frame = thread->last_frame();
559 CodeBlob* stub_cb = wrapper_frame.cb();
560 if (stub_cb != NULL &&
561 stub_cb->is_nmethod() &&
562 stub_cb->as_nmethod_or_null()->is_lazy_critical_native()) {
563 // A thread could potentially be in a critical native across
564 // more than one safepoint, so only update the critical state on
565 // the first one. When it returns it will perform the unlock.
566 if (!thread->do_critical_native_unlock()) {
567 #ifdef ASSERT
568 if (!thread->in_critical()) {
569 GC_locker::increment_debug_jni_lock_count();
570 }
571 #endif
572 thread->enter_critical();
573 // Make sure the native wrapper calls back on return to
574 // perform the needed critical unlock.
575 thread->set_critical_native_unlock();
576 }
577 }
578 }
579 }
583 // -------------------------------------------------------------------------------------------------------
584 // Implementation of Safepoint callback point
586 void SafepointSynchronize::block(JavaThread *thread) {
587 assert(thread != NULL, "thread must be set");
588 assert(thread->is_Java_thread(), "not a Java thread");
590 // Threads shouldn't block if they are in the middle of printing, but...
591 ttyLocker::break_tty_lock_for_safepoint(os::current_thread_id());
593 // Only bail from the block() call if the thread is gone from the
594 // thread list; starting to exit should still block.
595 if (thread->is_terminated()) {
596 // block current thread if we come here from native code when VM is gone
597 thread->block_if_vm_exited();
599 // otherwise do nothing
600 return;
601 }
603 JavaThreadState state = thread->thread_state();
604 thread->frame_anchor()->make_walkable(thread);
606 // Check that we have a valid thread_state at this point
607 switch(state) {
608 case _thread_in_vm_trans:
609 case _thread_in_Java: // From compiled code
611 // We are highly likely to block on the Safepoint_lock. In order to avoid blocking in this case,
612 // we pretend we are still in the VM.
613 thread->set_thread_state(_thread_in_vm);
615 if (is_synchronizing()) {
616 Atomic::inc (&TryingToBlock) ;
617 }
619 // We will always be holding the Safepoint_lock when we are examine the state
620 // of a thread. Hence, the instructions between the Safepoint_lock->lock() and
621 // Safepoint_lock->unlock() are happening atomic with regards to the safepoint code
622 Safepoint_lock->lock_without_safepoint_check();
623 if (is_synchronizing()) {
624 // Decrement the number of threads to wait for and signal vm thread
625 assert(_waiting_to_block > 0, "sanity check");
626 _waiting_to_block--;
627 thread->safepoint_state()->set_has_called_back(true);
629 if (thread->in_critical()) {
630 // Notice that this thread is in a critical section
631 increment_jni_active_count();
632 }
634 // Consider (_waiting_to_block < 2) to pipeline the wakeup of the VM thread
635 if (_waiting_to_block == 0) {
636 Safepoint_lock->notify_all();
637 }
638 }
640 // We transition the thread to state _thread_blocked here, but
641 // we can't do our usual check for external suspension and then
642 // self-suspend after the lock_without_safepoint_check() call
643 // below because we are often called during transitions while
644 // we hold different locks. That would leave us suspended while
645 // holding a resource which results in deadlocks.
646 thread->set_thread_state(_thread_blocked);
647 Safepoint_lock->unlock();
649 // We now try to acquire the threads lock. Since this lock is hold by the VM thread during
650 // the entire safepoint, the threads will all line up here during the safepoint.
651 Threads_lock->lock_without_safepoint_check();
652 // restore original state. This is important if the thread comes from compiled code, so it
653 // will continue to execute with the _thread_in_Java state.
654 thread->set_thread_state(state);
655 Threads_lock->unlock();
656 break;
658 case _thread_in_native_trans:
659 case _thread_blocked_trans:
660 case _thread_new_trans:
661 if (thread->safepoint_state()->type() == ThreadSafepointState::_call_back) {
662 thread->print_thread_state();
663 fatal("Deadlock in safepoint code. "
664 "Should have called back to the VM before blocking.");
665 }
667 // We transition the thread to state _thread_blocked here, but
668 // we can't do our usual check for external suspension and then
669 // self-suspend after the lock_without_safepoint_check() call
670 // below because we are often called during transitions while
671 // we hold different locks. That would leave us suspended while
672 // holding a resource which results in deadlocks.
673 thread->set_thread_state(_thread_blocked);
675 // It is not safe to suspend a thread if we discover it is in _thread_in_native_trans. Hence,
676 // the safepoint code might still be waiting for it to block. We need to change the state here,
677 // so it can see that it is at a safepoint.
679 // Block until the safepoint operation is completed.
680 Threads_lock->lock_without_safepoint_check();
682 // Restore state
683 thread->set_thread_state(state);
685 Threads_lock->unlock();
686 break;
688 default:
689 fatal(err_msg("Illegal threadstate encountered: %d", state));
690 }
692 // Check for pending. async. exceptions or suspends - except if the
693 // thread was blocked inside the VM. has_special_runtime_exit_condition()
694 // is called last since it grabs a lock and we only want to do that when
695 // we must.
696 //
697 // Note: we never deliver an async exception at a polling point as the
698 // compiler may not have an exception handler for it. The polling
699 // code will notice the async and deoptimize and the exception will
700 // be delivered. (Polling at a return point is ok though). Sure is
701 // a lot of bother for a deprecated feature...
702 //
703 // We don't deliver an async exception if the thread state is
704 // _thread_in_native_trans so JNI functions won't be called with
705 // a surprising pending exception. If the thread state is going back to java,
706 // async exception is checked in check_special_condition_for_native_trans().
708 if (state != _thread_blocked_trans &&
709 state != _thread_in_vm_trans &&
710 thread->has_special_runtime_exit_condition()) {
711 thread->handle_special_runtime_exit_condition(
712 !thread->is_at_poll_safepoint() && (state != _thread_in_native_trans));
713 }
714 }
716 // ------------------------------------------------------------------------------------------------------
717 // Exception handlers
719 #ifndef PRODUCT
720 #ifdef _LP64
721 #define PTR_PAD ""
722 #else
723 #define PTR_PAD " "
724 #endif
726 static void print_ptrs(intptr_t oldptr, intptr_t newptr, bool wasoop) {
727 bool is_oop = newptr ? ((oop)newptr)->is_oop() : false;
728 tty->print_cr(PTR_FORMAT PTR_PAD " %s %c " PTR_FORMAT PTR_PAD " %s %s",
729 oldptr, wasoop?"oop":" ", oldptr == newptr ? ' ' : '!',
730 newptr, is_oop?"oop":" ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":" "));
731 }
733 static void print_longs(jlong oldptr, jlong newptr, bool wasoop) {
734 bool is_oop = newptr ? ((oop)(intptr_t)newptr)->is_oop() : false;
735 tty->print_cr(PTR64_FORMAT " %s %c " PTR64_FORMAT " %s %s",
736 oldptr, wasoop?"oop":" ", oldptr == newptr ? ' ' : '!',
737 newptr, is_oop?"oop":" ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":" "));
738 }
740 #ifdef SPARC
741 static void print_me(intptr_t *new_sp, intptr_t *old_sp, bool *was_oops) {
742 #ifdef _LP64
743 tty->print_cr("--------+------address-----+------before-----------+-------after----------+");
744 const int incr = 1; // Increment to skip a long, in units of intptr_t
745 #else
746 tty->print_cr("--------+--address-+------before-----------+-------after----------+");
747 const int incr = 2; // Increment to skip a long, in units of intptr_t
748 #endif
749 tty->print_cr("---SP---|");
750 for( int i=0; i<16; i++ ) {
751 tty->print("blob %c%d |"PTR_FORMAT" ","LO"[i>>3],i&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); }
752 tty->print_cr("--------|");
753 for( int i1=0; i1<frame::memory_parameter_word_sp_offset-16; i1++ ) {
754 tty->print("argv pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); }
755 tty->print(" pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++);
756 tty->print_cr("--------|");
757 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;
758 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;
759 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;
760 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;
761 tty->print_cr(" FSR |"PTR_FORMAT" "PTR64_FORMAT" "PTR64_FORMAT,new_sp,*(jlong*)old_sp,*(jlong*)new_sp);
762 old_sp += incr; new_sp += incr; was_oops += incr;
763 // Skip the floats
764 tty->print_cr("--Float-|"PTR_FORMAT,new_sp);
765 tty->print_cr("---FP---|");
766 old_sp += incr*32; new_sp += incr*32; was_oops += incr*32;
767 for( int i2=0; i2<16; i2++ ) {
768 tty->print("call %c%d |"PTR_FORMAT" ","LI"[i2>>3],i2&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); }
769 tty->print_cr("");
770 }
771 #endif // SPARC
772 #endif // PRODUCT
775 void SafepointSynchronize::handle_polling_page_exception(JavaThread *thread) {
776 assert(thread->is_Java_thread(), "polling reference encountered by VM thread");
777 assert(thread->thread_state() == _thread_in_Java, "should come from Java code");
778 assert(SafepointSynchronize::is_synchronizing(), "polling encountered outside safepoint synchronization");
780 // Uncomment this to get some serious before/after printing of the
781 // Sparc safepoint-blob frame structure.
782 /*
783 intptr_t* sp = thread->last_Java_sp();
784 intptr_t stack_copy[150];
785 for( int i=0; i<150; i++ ) stack_copy[i] = sp[i];
786 bool was_oops[150];
787 for( int i=0; i<150; i++ )
788 was_oops[i] = stack_copy[i] ? ((oop)stack_copy[i])->is_oop() : false;
789 */
791 if (ShowSafepointMsgs) {
792 tty->print("handle_polling_page_exception: ");
793 }
795 if (PrintSafepointStatistics) {
796 inc_page_trap_count();
797 }
799 ThreadSafepointState* state = thread->safepoint_state();
801 state->handle_polling_page_exception();
802 // print_me(sp,stack_copy,was_oops);
803 }
806 void SafepointSynchronize::print_safepoint_timeout(SafepointTimeoutReason reason) {
807 if (!timeout_error_printed) {
808 timeout_error_printed = true;
809 // Print out the thread infor which didn't reach the safepoint for debugging
810 // purposes (useful when there are lots of threads in the debugger).
811 tty->print_cr("");
812 tty->print_cr("# SafepointSynchronize::begin: Timeout detected:");
813 if (reason == _spinning_timeout) {
814 tty->print_cr("# SafepointSynchronize::begin: Timed out while spinning to reach a safepoint.");
815 } else if (reason == _blocking_timeout) {
816 tty->print_cr("# SafepointSynchronize::begin: Timed out while waiting for threads to stop.");
817 }
819 tty->print_cr("# SafepointSynchronize::begin: Threads which did not reach the safepoint:");
820 ThreadSafepointState *cur_state;
821 ResourceMark rm;
822 for(JavaThread *cur_thread = Threads::first(); cur_thread;
823 cur_thread = cur_thread->next()) {
824 cur_state = cur_thread->safepoint_state();
826 if (cur_thread->thread_state() != _thread_blocked &&
827 ((reason == _spinning_timeout && cur_state->is_running()) ||
828 (reason == _blocking_timeout && !cur_state->has_called_back()))) {
829 tty->print("# ");
830 cur_thread->print();
831 tty->print_cr("");
832 }
833 }
834 tty->print_cr("# SafepointSynchronize::begin: (End of list)");
835 }
837 // To debug the long safepoint, specify both DieOnSafepointTimeout &
838 // ShowMessageBoxOnError.
839 if (DieOnSafepointTimeout) {
840 char msg[1024];
841 VM_Operation *op = VMThread::vm_operation();
842 sprintf(msg, "Safepoint sync time longer than " INTX_FORMAT "ms detected when executing %s.",
843 SafepointTimeoutDelay,
844 op != NULL ? op->name() : "no vm operation");
845 fatal(msg);
846 }
847 }
850 // -------------------------------------------------------------------------------------------------------
851 // Implementation of ThreadSafepointState
853 ThreadSafepointState::ThreadSafepointState(JavaThread *thread) {
854 _thread = thread;
855 _type = _running;
856 _has_called_back = false;
857 _at_poll_safepoint = false;
858 }
860 void ThreadSafepointState::create(JavaThread *thread) {
861 ThreadSafepointState *state = new ThreadSafepointState(thread);
862 thread->set_safepoint_state(state);
863 }
865 void ThreadSafepointState::destroy(JavaThread *thread) {
866 if (thread->safepoint_state()) {
867 delete(thread->safepoint_state());
868 thread->set_safepoint_state(NULL);
869 }
870 }
872 void ThreadSafepointState::examine_state_of_thread() {
873 assert(is_running(), "better be running or just have hit safepoint poll");
875 JavaThreadState state = _thread->thread_state();
877 // Save the state at the start of safepoint processing.
878 _orig_thread_state = state;
880 // Check for a thread that is suspended. Note that thread resume tries
881 // to grab the Threads_lock which we own here, so a thread cannot be
882 // resumed during safepoint synchronization.
884 // We check to see if this thread is suspended without locking to
885 // avoid deadlocking with a third thread that is waiting for this
886 // thread to be suspended. The third thread can notice the safepoint
887 // that we're trying to start at the beginning of its SR_lock->wait()
888 // call. If that happens, then the third thread will block on the
889 // safepoint while still holding the underlying SR_lock. We won't be
890 // able to get the SR_lock and we'll deadlock.
891 //
892 // We don't need to grab the SR_lock here for two reasons:
893 // 1) The suspend flags are both volatile and are set with an
894 // Atomic::cmpxchg() call so we should see the suspended
895 // state right away.
896 // 2) We're being called from the safepoint polling loop; if
897 // we don't see the suspended state on this iteration, then
898 // we'll come around again.
899 //
900 bool is_suspended = _thread->is_ext_suspended();
901 if (is_suspended) {
902 roll_forward(_at_safepoint);
903 return;
904 }
906 // Some JavaThread states have an initial safepoint state of
907 // running, but are actually at a safepoint. We will happily
908 // agree and update the safepoint state here.
909 if (SafepointSynchronize::safepoint_safe(_thread, state)) {
910 roll_forward(_at_safepoint);
911 SafepointSynchronize::check_for_lazy_critical_native(_thread, state);
912 if (_thread->in_critical()) {
913 // Notice that this thread is in a critical section
914 SafepointSynchronize::increment_jni_active_count();
915 }
916 return;
917 }
919 if (state == _thread_in_vm) {
920 roll_forward(_call_back);
921 return;
922 }
924 // All other thread states will continue to run until they
925 // transition and self-block in state _blocked
926 // Safepoint polling in compiled code causes the Java threads to do the same.
927 // Note: new threads may require a malloc so they must be allowed to finish
929 assert(is_running(), "examine_state_of_thread on non-running thread");
930 return;
931 }
933 // Returns true is thread could not be rolled forward at present position.
934 void ThreadSafepointState::roll_forward(suspend_type type) {
935 _type = type;
937 switch(_type) {
938 case _at_safepoint:
939 SafepointSynchronize::signal_thread_at_safepoint();
940 break;
942 case _call_back:
943 set_has_called_back(false);
944 break;
946 case _running:
947 default:
948 ShouldNotReachHere();
949 }
950 }
952 void ThreadSafepointState::restart() {
953 switch(type()) {
954 case _at_safepoint:
955 case _call_back:
956 break;
958 case _running:
959 default:
960 tty->print_cr("restart thread "INTPTR_FORMAT" with state %d",
961 _thread, _type);
962 _thread->print();
963 ShouldNotReachHere();
964 }
965 _type = _running;
966 set_has_called_back(false);
967 }
970 void ThreadSafepointState::print_on(outputStream *st) const {
971 const char *s;
973 switch(_type) {
974 case _running : s = "_running"; break;
975 case _at_safepoint : s = "_at_safepoint"; break;
976 case _call_back : s = "_call_back"; break;
977 default:
978 ShouldNotReachHere();
979 }
981 st->print_cr("Thread: " INTPTR_FORMAT
982 " [0x%2x] State: %s _has_called_back %d _at_poll_safepoint %d",
983 _thread, _thread->osthread()->thread_id(), s, _has_called_back,
984 _at_poll_safepoint);
986 _thread->print_thread_state_on(st);
987 }
990 // ---------------------------------------------------------------------------------------------------------------------
992 // Block the thread at the safepoint poll or poll return.
993 void ThreadSafepointState::handle_polling_page_exception() {
995 // Check state. block() will set thread state to thread_in_vm which will
996 // cause the safepoint state _type to become _call_back.
997 assert(type() == ThreadSafepointState::_running,
998 "polling page exception on thread not running state");
1000 // Step 1: Find the nmethod from the return address
1001 if (ShowSafepointMsgs && Verbose) {
1002 tty->print_cr("Polling page exception at " INTPTR_FORMAT, thread()->saved_exception_pc());
1003 }
1004 address real_return_addr = thread()->saved_exception_pc();
1006 CodeBlob *cb = CodeCache::find_blob(real_return_addr);
1007 assert(cb != NULL && cb->is_nmethod(), "return address should be in nmethod");
1008 nmethod* nm = (nmethod*)cb;
1010 // Find frame of caller
1011 frame stub_fr = thread()->last_frame();
1012 CodeBlob* stub_cb = stub_fr.cb();
1013 assert(stub_cb->is_safepoint_stub(), "must be a safepoint stub");
1014 RegisterMap map(thread(), true);
1015 frame caller_fr = stub_fr.sender(&map);
1017 // Should only be poll_return or poll
1018 assert( nm->is_at_poll_or_poll_return(real_return_addr), "should not be at call" );
1020 // This is a poll immediately before a return. The exception handling code
1021 // has already had the effect of causing the return to occur, so the execution
1022 // will continue immediately after the call. In addition, the oopmap at the
1023 // return point does not mark the return value as an oop (if it is), so
1024 // it needs a handle here to be updated.
1025 if( nm->is_at_poll_return(real_return_addr) ) {
1026 // See if return type is an oop.
1027 bool return_oop = nm->method()->is_returning_oop();
1028 Handle return_value;
1029 if (return_oop) {
1030 // The oop result has been saved on the stack together with all
1031 // the other registers. In order to preserve it over GCs we need
1032 // to keep it in a handle.
1033 oop result = caller_fr.saved_oop_result(&map);
1034 assert(result == NULL || result->is_oop(), "must be oop");
1035 return_value = Handle(thread(), result);
1036 assert(Universe::heap()->is_in_or_null(result), "must be heap pointer");
1037 }
1039 // Block the thread
1040 SafepointSynchronize::block(thread());
1042 // restore oop result, if any
1043 if (return_oop) {
1044 caller_fr.set_saved_oop_result(&map, return_value());
1045 }
1046 }
1048 // This is a safepoint poll. Verify the return address and block.
1049 else {
1050 set_at_poll_safepoint(true);
1052 // verify the blob built the "return address" correctly
1053 assert(real_return_addr == caller_fr.pc(), "must match");
1055 // Block the thread
1056 SafepointSynchronize::block(thread());
1057 set_at_poll_safepoint(false);
1059 // If we have a pending async exception deoptimize the frame
1060 // as otherwise we may never deliver it.
1061 if (thread()->has_async_condition()) {
1062 ThreadInVMfromJavaNoAsyncException __tiv(thread());
1063 Deoptimization::deoptimize_frame(thread(), caller_fr.id());
1064 }
1066 // If an exception has been installed we must check for a pending deoptimization
1067 // Deoptimize frame if exception has been thrown.
1069 if (thread()->has_pending_exception() ) {
1070 RegisterMap map(thread(), true);
1071 frame caller_fr = stub_fr.sender(&map);
1072 if (caller_fr.is_deoptimized_frame()) {
1073 // The exception patch will destroy registers that are still
1074 // live and will be needed during deoptimization. Defer the
1075 // Async exception should have defered the exception until the
1076 // next safepoint which will be detected when we get into
1077 // the interpreter so if we have an exception now things
1078 // are messed up.
1080 fatal("Exception installed and deoptimization is pending");
1081 }
1082 }
1083 }
1084 }
1087 //
1088 // Statistics & Instrumentations
1089 //
1090 SafepointSynchronize::SafepointStats* SafepointSynchronize::_safepoint_stats = NULL;
1091 jlong SafepointSynchronize::_safepoint_begin_time = 0;
1092 int SafepointSynchronize::_cur_stat_index = 0;
1093 julong SafepointSynchronize::_safepoint_reasons[VM_Operation::VMOp_Terminating];
1094 julong SafepointSynchronize::_coalesced_vmop_count = 0;
1095 jlong SafepointSynchronize::_max_sync_time = 0;
1096 jlong SafepointSynchronize::_max_vmop_time = 0;
1097 float SafepointSynchronize::_ts_of_current_safepoint = 0.0f;
1099 static jlong cleanup_end_time = 0;
1100 static bool need_to_track_page_armed_status = false;
1101 static bool init_done = false;
1103 // Helper method to print the header.
1104 static void print_header() {
1105 tty->print(" vmop "
1106 "[threads: total initially_running wait_to_block] ");
1107 tty->print("[time: spin block sync cleanup vmop] ");
1109 // no page armed status printed out if it is always armed.
1110 if (need_to_track_page_armed_status) {
1111 tty->print("page_armed ");
1112 }
1114 tty->print_cr("page_trap_count");
1115 }
1117 void SafepointSynchronize::deferred_initialize_stat() {
1118 if (init_done) return;
1120 if (PrintSafepointStatisticsCount <= 0) {
1121 fatal("Wrong PrintSafepointStatisticsCount");
1122 }
1124 // If PrintSafepointStatisticsTimeout is specified, the statistics data will
1125 // be printed right away, in which case, _safepoint_stats will regress to
1126 // a single element array. Otherwise, it is a circular ring buffer with default
1127 // size of PrintSafepointStatisticsCount.
1128 int stats_array_size;
1129 if (PrintSafepointStatisticsTimeout > 0) {
1130 stats_array_size = 1;
1131 PrintSafepointStatistics = true;
1132 } else {
1133 stats_array_size = PrintSafepointStatisticsCount;
1134 }
1135 _safepoint_stats = (SafepointStats*)os::malloc(stats_array_size
1136 * sizeof(SafepointStats));
1137 guarantee(_safepoint_stats != NULL,
1138 "not enough memory for safepoint instrumentation data");
1140 if (UseCompilerSafepoints && DeferPollingPageLoopCount >= 0) {
1141 need_to_track_page_armed_status = true;
1142 }
1143 init_done = true;
1144 }
1146 void SafepointSynchronize::begin_statistics(int nof_threads, int nof_running) {
1147 assert(init_done, "safepoint statistics array hasn't been initialized");
1148 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
1150 spstat->_time_stamp = _ts_of_current_safepoint;
1152 VM_Operation *op = VMThread::vm_operation();
1153 spstat->_vmop_type = (op != NULL ? op->type() : -1);
1154 if (op != NULL) {
1155 _safepoint_reasons[spstat->_vmop_type]++;
1156 }
1158 spstat->_nof_total_threads = nof_threads;
1159 spstat->_nof_initial_running_threads = nof_running;
1160 spstat->_nof_threads_hit_page_trap = 0;
1162 // Records the start time of spinning. The real time spent on spinning
1163 // will be adjusted when spin is done. Same trick is applied for time
1164 // spent on waiting for threads to block.
1165 if (nof_running != 0) {
1166 spstat->_time_to_spin = os::javaTimeNanos();
1167 } else {
1168 spstat->_time_to_spin = 0;
1169 }
1170 }
1172 void SafepointSynchronize::update_statistics_on_spin_end() {
1173 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
1175 jlong cur_time = os::javaTimeNanos();
1177 spstat->_nof_threads_wait_to_block = _waiting_to_block;
1178 if (spstat->_nof_initial_running_threads != 0) {
1179 spstat->_time_to_spin = cur_time - spstat->_time_to_spin;
1180 }
1182 if (need_to_track_page_armed_status) {
1183 spstat->_page_armed = (PageArmed == 1);
1184 }
1186 // Records the start time of waiting for to block. Updated when block is done.
1187 if (_waiting_to_block != 0) {
1188 spstat->_time_to_wait_to_block = cur_time;
1189 } else {
1190 spstat->_time_to_wait_to_block = 0;
1191 }
1192 }
1194 void SafepointSynchronize::update_statistics_on_sync_end(jlong end_time) {
1195 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
1197 if (spstat->_nof_threads_wait_to_block != 0) {
1198 spstat->_time_to_wait_to_block = end_time -
1199 spstat->_time_to_wait_to_block;
1200 }
1202 // Records the end time of sync which will be used to calculate the total
1203 // vm operation time. Again, the real time spending in syncing will be deducted
1204 // from the start of the sync time later when end_statistics is called.
1205 spstat->_time_to_sync = end_time - _safepoint_begin_time;
1206 if (spstat->_time_to_sync > _max_sync_time) {
1207 _max_sync_time = spstat->_time_to_sync;
1208 }
1210 spstat->_time_to_do_cleanups = end_time;
1211 }
1213 void SafepointSynchronize::update_statistics_on_cleanup_end(jlong end_time) {
1214 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
1216 // Record how long spent in cleanup tasks.
1217 spstat->_time_to_do_cleanups = end_time - spstat->_time_to_do_cleanups;
1219 cleanup_end_time = end_time;
1220 }
1222 void SafepointSynchronize::end_statistics(jlong vmop_end_time) {
1223 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
1225 // Update the vm operation time.
1226 spstat->_time_to_exec_vmop = vmop_end_time - cleanup_end_time;
1227 if (spstat->_time_to_exec_vmop > _max_vmop_time) {
1228 _max_vmop_time = spstat->_time_to_exec_vmop;
1229 }
1230 // Only the sync time longer than the specified
1231 // PrintSafepointStatisticsTimeout will be printed out right away.
1232 // By default, it is -1 meaning all samples will be put into the list.
1233 if ( PrintSafepointStatisticsTimeout > 0) {
1234 if (spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) {
1235 print_statistics();
1236 }
1237 } else {
1238 // The safepoint statistics will be printed out when the _safepoin_stats
1239 // array fills up.
1240 if (_cur_stat_index == PrintSafepointStatisticsCount - 1) {
1241 print_statistics();
1242 _cur_stat_index = 0;
1243 } else {
1244 _cur_stat_index++;
1245 }
1246 }
1247 }
1249 void SafepointSynchronize::print_statistics() {
1250 SafepointStats* sstats = _safepoint_stats;
1252 for (int index = 0; index <= _cur_stat_index; index++) {
1253 if (index % 30 == 0) {
1254 print_header();
1255 }
1256 sstats = &_safepoint_stats[index];
1257 tty->print("%.3f: ", sstats->_time_stamp);
1258 tty->print("%-26s ["
1259 INT32_FORMAT_W(8)INT32_FORMAT_W(11)INT32_FORMAT_W(15)
1260 " ] ",
1261 sstats->_vmop_type == -1 ? "no vm operation" :
1262 VM_Operation::name(sstats->_vmop_type),
1263 sstats->_nof_total_threads,
1264 sstats->_nof_initial_running_threads,
1265 sstats->_nof_threads_wait_to_block);
1266 // "/ MICROUNITS " is to convert the unit from nanos to millis.
1267 tty->print(" ["
1268 INT64_FORMAT_W(6)INT64_FORMAT_W(6)
1269 INT64_FORMAT_W(6)INT64_FORMAT_W(6)
1270 INT64_FORMAT_W(6)" ] ",
1271 sstats->_time_to_spin / MICROUNITS,
1272 sstats->_time_to_wait_to_block / MICROUNITS,
1273 sstats->_time_to_sync / MICROUNITS,
1274 sstats->_time_to_do_cleanups / MICROUNITS,
1275 sstats->_time_to_exec_vmop / MICROUNITS);
1277 if (need_to_track_page_armed_status) {
1278 tty->print(INT32_FORMAT" ", sstats->_page_armed);
1279 }
1280 tty->print_cr(INT32_FORMAT" ", sstats->_nof_threads_hit_page_trap);
1281 }
1282 }
1284 // This method will be called when VM exits. It will first call
1285 // print_statistics to print out the rest of the sampling. Then
1286 // it tries to summarize the sampling.
1287 void SafepointSynchronize::print_stat_on_exit() {
1288 if (_safepoint_stats == NULL) return;
1290 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
1292 // During VM exit, end_statistics may not get called and in that
1293 // case, if the sync time is less than PrintSafepointStatisticsTimeout,
1294 // don't print it out.
1295 // Approximate the vm op time.
1296 _safepoint_stats[_cur_stat_index]._time_to_exec_vmop =
1297 os::javaTimeNanos() - cleanup_end_time;
1299 if ( PrintSafepointStatisticsTimeout < 0 ||
1300 spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) {
1301 print_statistics();
1302 }
1303 tty->print_cr("");
1305 // Print out polling page sampling status.
1306 if (!need_to_track_page_armed_status) {
1307 if (UseCompilerSafepoints) {
1308 tty->print_cr("Polling page always armed");
1309 }
1310 } else {
1311 tty->print_cr("Defer polling page loop count = %d\n",
1312 DeferPollingPageLoopCount);
1313 }
1315 for (int index = 0; index < VM_Operation::VMOp_Terminating; index++) {
1316 if (_safepoint_reasons[index] != 0) {
1317 tty->print_cr("%-26s"UINT64_FORMAT_W(10), VM_Operation::name(index),
1318 _safepoint_reasons[index]);
1319 }
1320 }
1322 tty->print_cr(UINT64_FORMAT_W(5)" VM operations coalesced during safepoint",
1323 _coalesced_vmop_count);
1324 tty->print_cr("Maximum sync time "INT64_FORMAT_W(5)" ms",
1325 _max_sync_time / MICROUNITS);
1326 tty->print_cr("Maximum vm operation time (except for Exit VM operation) "
1327 INT64_FORMAT_W(5)" ms",
1328 _max_vmop_time / MICROUNITS);
1329 }
1331 // ------------------------------------------------------------------------------------------------
1332 // Non-product code
1334 #ifndef PRODUCT
1336 void SafepointSynchronize::print_state() {
1337 if (_state == _not_synchronized) {
1338 tty->print_cr("not synchronized");
1339 } else if (_state == _synchronizing || _state == _synchronized) {
1340 tty->print_cr("State: %s", (_state == _synchronizing) ? "synchronizing" :
1341 "synchronized");
1343 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) {
1344 cur->safepoint_state()->print();
1345 }
1346 }
1347 }
1349 void SafepointSynchronize::safepoint_msg(const char* format, ...) {
1350 if (ShowSafepointMsgs) {
1351 va_list ap;
1352 va_start(ap, format);
1353 tty->vprint_cr(format, ap);
1354 va_end(ap);
1355 }
1356 }
1358 #endif // !PRODUCT