Sun, 25 Sep 2011 16:03:29 -0700
7089790: integrate bsd-port changes
Reviewed-by: kvn, twisti, jrose
Contributed-by: Kurt Miller <kurt@intricatesoftware.com>, Greg Lewis <glewis@eyesbeyond.com>, Jung-uk Kim <jkim@freebsd.org>, Christos Zoulas <christos@zoulas.com>, Landon Fuller <landonf@plausible.coop>, The FreeBSD Foundation <board@freebsdfoundation.org>, Michael Franz <mvfranz@gmail.com>, Roger Hoover <rhoover@apple.com>, Alexander Strange <astrange@apple.com>
1 /*
2 * Copyright (c) 1997, 2011, 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 long SafepointSynchronize::_end_of_last_safepoint = 0;
99 static volatile int PageArmed = 0 ; // safepoint polling page is RO|RW vs PROT_NONE
100 static volatile int TryingToBlock = 0 ; // proximate value -- for advisory use only
101 static bool timeout_error_printed = false;
103 // Roll all threads forward to a safepoint and suspend them all
104 void SafepointSynchronize::begin() {
106 Thread* myThread = Thread::current();
107 assert(myThread->is_VM_thread(), "Only VM thread may execute a safepoint");
109 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) {
110 _safepoint_begin_time = os::javaTimeNanos();
111 _ts_of_current_safepoint = tty->time_stamp().seconds();
112 }
114 #ifndef SERIALGC
115 if (UseConcMarkSweepGC) {
116 // In the future we should investigate whether CMS can use the
117 // more-general mechanism below. DLD (01/05).
118 ConcurrentMarkSweepThread::synchronize(false);
119 } else if (UseG1GC) {
120 ConcurrentGCThread::safepoint_synchronize();
121 }
122 #endif // SERIALGC
124 // By getting the Threads_lock, we assure that no threads are about to start or
125 // exit. It is released again in SafepointSynchronize::end().
126 Threads_lock->lock();
128 assert( _state == _not_synchronized, "trying to safepoint synchronize with wrong state");
130 int nof_threads = Threads::number_of_threads();
132 if (TraceSafepoint) {
133 tty->print_cr("Safepoint synchronization initiated. (%d)", nof_threads);
134 }
136 RuntimeService::record_safepoint_begin();
138 {
139 MutexLocker mu(Safepoint_lock);
141 // Set number of threads to wait for, before we initiate the callbacks
142 _waiting_to_block = nof_threads;
143 TryingToBlock = 0 ;
144 int still_running = nof_threads;
146 // Save the starting time, so that it can be compared to see if this has taken
147 // too long to complete.
148 jlong safepoint_limit_time;
149 timeout_error_printed = false;
151 // PrintSafepointStatisticsTimeout can be specified separately. When
152 // specified, PrintSafepointStatistics will be set to true in
153 // deferred_initialize_stat method. The initialization has to be done
154 // early enough to avoid any races. See bug 6880029 for details.
155 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) {
156 deferred_initialize_stat();
157 }
159 // Begin the process of bringing the system to a safepoint.
160 // Java threads can be in several different states and are
161 // stopped by different mechanisms:
162 //
163 // 1. Running interpreted
164 // The interpeter dispatch table is changed to force it to
165 // check for a safepoint condition between bytecodes.
166 // 2. Running in native code
167 // When returning from the native code, a Java thread must check
168 // the safepoint _state to see if we must block. If the
169 // VM thread sees a Java thread in native, it does
170 // not wait for this thread to block. The order of the memory
171 // writes and reads of both the safepoint state and the Java
172 // threads state is critical. In order to guarantee that the
173 // memory writes are serialized with respect to each other,
174 // the VM thread issues a memory barrier instruction
175 // (on MP systems). In order to avoid the overhead of issuing
176 // a memory barrier for each Java thread making native calls, each Java
177 // thread performs a write to a single memory page after changing
178 // the thread state. The VM thread performs a sequence of
179 // mprotect OS calls which forces all previous writes from all
180 // Java threads to be serialized. This is done in the
181 // os::serialize_thread_states() call. This has proven to be
182 // much more efficient than executing a membar instruction
183 // on every call to native code.
184 // 3. Running compiled Code
185 // Compiled code reads a global (Safepoint Polling) page that
186 // is set to fault if we are trying to get to a safepoint.
187 // 4. Blocked
188 // A thread which is blocked will not be allowed to return from the
189 // block condition until the safepoint operation is complete.
190 // 5. In VM or Transitioning between states
191 // If a Java thread is currently running in the VM or transitioning
192 // between states, the safepointing code will wait for the thread to
193 // block itself when it attempts transitions to a new state.
194 //
195 _state = _synchronizing;
196 OrderAccess::fence();
198 // Flush all thread states to memory
199 if (!UseMembar) {
200 os::serialize_thread_states();
201 }
203 // Make interpreter safepoint aware
204 Interpreter::notice_safepoints();
206 if (UseCompilerSafepoints && DeferPollingPageLoopCount < 0) {
207 // Make polling safepoint aware
208 guarantee (PageArmed == 0, "invariant") ;
209 PageArmed = 1 ;
210 os::make_polling_page_unreadable();
211 }
213 // Consider using active_processor_count() ... but that call is expensive.
214 int ncpus = os::processor_count() ;
216 #ifdef ASSERT
217 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) {
218 assert(cur->safepoint_state()->is_running(), "Illegal initial state");
219 }
220 #endif // ASSERT
222 if (SafepointTimeout)
223 safepoint_limit_time = os::javaTimeNanos() + (jlong)SafepointTimeoutDelay * MICROUNITS;
225 // Iterate through all threads until it have been determined how to stop them all at a safepoint
226 unsigned int iterations = 0;
227 int steps = 0 ;
228 while(still_running > 0) {
229 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) {
230 assert(!cur->is_ConcurrentGC_thread(), "A concurrent GC thread is unexpectly being suspended");
231 ThreadSafepointState *cur_state = cur->safepoint_state();
232 if (cur_state->is_running()) {
233 cur_state->examine_state_of_thread();
234 if (!cur_state->is_running()) {
235 still_running--;
236 // consider adjusting steps downward:
237 // steps = 0
238 // steps -= NNN
239 // steps >>= 1
240 // steps = MIN(steps, 2000-100)
241 // if (iterations != 0) steps -= NNN
242 }
243 if (TraceSafepoint && Verbose) cur_state->print();
244 }
245 }
247 if (PrintSafepointStatistics && iterations == 0) {
248 begin_statistics(nof_threads, still_running);
249 }
251 if (still_running > 0) {
252 // Check for if it takes to long
253 if (SafepointTimeout && safepoint_limit_time < os::javaTimeNanos()) {
254 print_safepoint_timeout(_spinning_timeout);
255 }
257 // Spin to avoid context switching.
258 // There's a tension between allowing the mutators to run (and rendezvous)
259 // vs spinning. As the VM thread spins, wasting cycles, it consumes CPU that
260 // a mutator might otherwise use profitably to reach a safepoint. Excessive
261 // spinning by the VM thread on a saturated system can increase rendezvous latency.
262 // Blocking or yielding incur their own penalties in the form of context switching
263 // and the resultant loss of $ residency.
264 //
265 // Further complicating matters is that yield() does not work as naively expected
266 // on many platforms -- yield() does not guarantee that any other ready threads
267 // will run. As such we revert yield_all() after some number of iterations.
268 // Yield_all() is implemented as a short unconditional sleep on some platforms.
269 // Typical operating systems round a "short" sleep period up to 10 msecs, so sleeping
270 // can actually increase the time it takes the VM thread to detect that a system-wide
271 // stop-the-world safepoint has been reached. In a pathological scenario such as that
272 // described in CR6415670 the VMthread may sleep just before the mutator(s) become safe.
273 // In that case the mutators will be stalled waiting for the safepoint to complete and the
274 // the VMthread will be sleeping, waiting for the mutators to rendezvous. The VMthread
275 // will eventually wake up and detect that all mutators are safe, at which point
276 // we'll again make progress.
277 //
278 // Beware too that that the VMThread typically runs at elevated priority.
279 // Its default priority is higher than the default mutator priority.
280 // Obviously, this complicates spinning.
281 //
282 // Note too that on Windows XP SwitchThreadTo() has quite different behavior than Sleep(0).
283 // Sleep(0) will _not yield to lower priority threads, while SwitchThreadTo() will.
284 //
285 // See the comments in synchronizer.cpp for additional remarks on spinning.
286 //
287 // In the future we might:
288 // 1. Modify the safepoint scheme to avoid potentally unbounded spinning.
289 // This is tricky as the path used by a thread exiting the JVM (say on
290 // on JNI call-out) simply stores into its state field. The burden
291 // is placed on the VM thread, which must poll (spin).
292 // 2. Find something useful to do while spinning. If the safepoint is GC-related
293 // we might aggressively scan the stacks of threads that are already safe.
294 // 3. Use Solaris schedctl to examine the state of the still-running mutators.
295 // If all the mutators are ONPROC there's no reason to sleep or yield.
296 // 4. YieldTo() any still-running mutators that are ready but OFFPROC.
297 // 5. Check system saturation. If the system is not fully saturated then
298 // simply spin and avoid sleep/yield.
299 // 6. As still-running mutators rendezvous they could unpark the sleeping
300 // VMthread. This works well for still-running mutators that become
301 // safe. The VMthread must still poll for mutators that call-out.
302 // 7. Drive the policy on time-since-begin instead of iterations.
303 // 8. Consider making the spin duration a function of the # of CPUs:
304 // Spin = (((ncpus-1) * M) + K) + F(still_running)
305 // Alternately, instead of counting iterations of the outer loop
306 // we could count the # of threads visited in the inner loop, above.
307 // 9. On windows consider using the return value from SwitchThreadTo()
308 // to drive subsequent spin/SwitchThreadTo()/Sleep(N) decisions.
310 if (UseCompilerSafepoints && int(iterations) == DeferPollingPageLoopCount) {
311 guarantee (PageArmed == 0, "invariant") ;
312 PageArmed = 1 ;
313 os::make_polling_page_unreadable();
314 }
316 // Instead of (ncpus > 1) consider either (still_running < (ncpus + EPSILON)) or
317 // ((still_running + _waiting_to_block - TryingToBlock)) < ncpus)
318 ++steps ;
319 if (ncpus > 1 && steps < SafepointSpinBeforeYield) {
320 SpinPause() ; // MP-Polite spin
321 } else
322 if (steps < DeferThrSuspendLoopCount) {
323 os::NakedYield() ;
324 } else {
325 os::yield_all(steps) ;
326 // Alternately, the VM thread could transiently depress its scheduling priority or
327 // transiently increase the priority of the tardy mutator(s).
328 }
330 iterations ++ ;
331 }
332 assert(iterations < (uint)max_jint, "We have been iterating in the safepoint loop too long");
333 }
334 assert(still_running == 0, "sanity check");
336 if (PrintSafepointStatistics) {
337 update_statistics_on_spin_end();
338 }
340 // wait until all threads are stopped
341 while (_waiting_to_block > 0) {
342 if (TraceSafepoint) tty->print_cr("Waiting for %d thread(s) to block", _waiting_to_block);
343 if (!SafepointTimeout || timeout_error_printed) {
344 Safepoint_lock->wait(true); // true, means with no safepoint checks
345 } else {
346 // Compute remaining time
347 jlong remaining_time = safepoint_limit_time - os::javaTimeNanos();
349 // If there is no remaining time, then there is an error
350 if (remaining_time < 0 || Safepoint_lock->wait(true, remaining_time / MICROUNITS)) {
351 print_safepoint_timeout(_blocking_timeout);
352 }
353 }
354 }
355 assert(_waiting_to_block == 0, "sanity check");
357 #ifndef PRODUCT
358 if (SafepointTimeout) {
359 jlong current_time = os::javaTimeNanos();
360 if (safepoint_limit_time < current_time) {
361 tty->print_cr("# SafepointSynchronize: Finished after "
362 INT64_FORMAT_W(6) " ms",
363 ((current_time - safepoint_limit_time) / MICROUNITS +
364 SafepointTimeoutDelay));
365 }
366 }
367 #endif
369 assert((_safepoint_counter & 0x1) == 0, "must be even");
370 assert(Threads_lock->owned_by_self(), "must hold Threads_lock");
371 _safepoint_counter ++;
373 // Record state
374 _state = _synchronized;
376 OrderAccess::fence();
378 if (TraceSafepoint) {
379 VM_Operation *op = VMThread::vm_operation();
380 tty->print_cr("Entering safepoint region: %s", (op != NULL) ? op->name() : "no vm operation");
381 }
383 RuntimeService::record_safepoint_synchronized();
384 if (PrintSafepointStatistics) {
385 update_statistics_on_sync_end(os::javaTimeNanos());
386 }
388 // Call stuff that needs to be run when a safepoint is just about to be completed
389 do_cleanup_tasks();
391 if (PrintSafepointStatistics) {
392 // Record how much time spend on the above cleanup tasks
393 update_statistics_on_cleanup_end(os::javaTimeNanos());
394 }
395 }
396 }
398 // Wake up all threads, so they are ready to resume execution after the safepoint
399 // operation has been carried out
400 void SafepointSynchronize::end() {
402 assert(Threads_lock->owned_by_self(), "must hold Threads_lock");
403 assert((_safepoint_counter & 0x1) == 1, "must be odd");
404 _safepoint_counter ++;
405 // memory fence isn't required here since an odd _safepoint_counter
406 // value can do no harm and a fence is issued below anyway.
408 DEBUG_ONLY(Thread* myThread = Thread::current();)
409 assert(myThread->is_VM_thread(), "Only VM thread can execute a safepoint");
411 if (PrintSafepointStatistics) {
412 end_statistics(os::javaTimeNanos());
413 }
415 #ifdef ASSERT
416 // A pending_exception cannot be installed during a safepoint. The threads
417 // may install an async exception after they come back from a safepoint into
418 // pending_exception after they unblock. But that should happen later.
419 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) {
420 assert (!(cur->has_pending_exception() &&
421 cur->safepoint_state()->is_at_poll_safepoint()),
422 "safepoint installed a pending exception");
423 }
424 #endif // ASSERT
426 if (PageArmed) {
427 // Make polling safepoint aware
428 os::make_polling_page_readable();
429 PageArmed = 0 ;
430 }
432 // Remove safepoint check from interpreter
433 Interpreter::ignore_safepoints();
435 {
436 MutexLocker mu(Safepoint_lock);
438 assert(_state == _synchronized, "must be synchronized before ending safepoint synchronization");
440 // Set to not synchronized, so the threads will not go into the signal_thread_blocked method
441 // when they get restarted.
442 _state = _not_synchronized;
443 OrderAccess::fence();
445 if (TraceSafepoint) {
446 tty->print_cr("Leaving safepoint region");
447 }
449 // Start suspended threads
450 for(JavaThread *current = Threads::first(); current; current = current->next()) {
451 // A problem occurring on Solaris is when attempting to restart threads
452 // the first #cpus - 1 go well, but then the VMThread is preempted when we get
453 // to the next one (since it has been running the longest). We then have
454 // to wait for a cpu to become available before we can continue restarting
455 // threads.
456 // FIXME: This causes the performance of the VM to degrade when active and with
457 // large numbers of threads. Apparently this is due to the synchronous nature
458 // of suspending threads.
459 //
460 // TODO-FIXME: the comments above are vestigial and no longer apply.
461 // Furthermore, using solaris' schedctl in this particular context confers no benefit
462 if (VMThreadHintNoPreempt) {
463 os::hint_no_preempt();
464 }
465 ThreadSafepointState* cur_state = current->safepoint_state();
466 assert(cur_state->type() != ThreadSafepointState::_running, "Thread not suspended at safepoint");
467 cur_state->restart();
468 assert(cur_state->is_running(), "safepoint state has not been reset");
469 }
471 RuntimeService::record_safepoint_end();
473 // Release threads lock, so threads can be created/destroyed again. It will also starts all threads
474 // blocked in signal_thread_blocked
475 Threads_lock->unlock();
477 }
478 #ifndef SERIALGC
479 // If there are any concurrent GC threads resume them.
480 if (UseConcMarkSweepGC) {
481 ConcurrentMarkSweepThread::desynchronize(false);
482 } else if (UseG1GC) {
483 ConcurrentGCThread::safepoint_desynchronize();
484 }
485 #endif // SERIALGC
486 // record this time so VMThread can keep track how much time has elasped
487 // since last safepoint.
488 _end_of_last_safepoint = os::javaTimeMillis();
489 }
491 bool SafepointSynchronize::is_cleanup_needed() {
492 // Need a safepoint if some inline cache buffers is non-empty
493 if (!InlineCacheBuffer::is_empty()) return true;
494 return false;
495 }
499 // Various cleaning tasks that should be done periodically at safepoints
500 void SafepointSynchronize::do_cleanup_tasks() {
501 {
502 TraceTime t1("deflating idle monitors", TraceSafepointCleanupTime);
503 ObjectSynchronizer::deflate_idle_monitors();
504 }
506 {
507 TraceTime t2("updating inline caches", TraceSafepointCleanupTime);
508 InlineCacheBuffer::update_inline_caches();
509 }
510 {
511 TraceTime t3("compilation policy safepoint handler", TraceSafepointCleanupTime);
512 CompilationPolicy::policy()->do_safepoint_work();
513 }
515 TraceTime t4("sweeping nmethods", TraceSafepointCleanupTime);
516 NMethodSweeper::scan_stacks();
518 // rotate log files?
519 if (UseGCLogFileRotation) {
520 gclog_or_tty->rotate_log();
521 }
522 }
525 bool SafepointSynchronize::safepoint_safe(JavaThread *thread, JavaThreadState state) {
526 switch(state) {
527 case _thread_in_native:
528 // native threads are safe if they have no java stack or have walkable stack
529 return !thread->has_last_Java_frame() || thread->frame_anchor()->walkable();
531 // blocked threads should have already have walkable stack
532 case _thread_blocked:
533 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "blocked and not walkable");
534 return true;
536 default:
537 return false;
538 }
539 }
542 // -------------------------------------------------------------------------------------------------------
543 // Implementation of Safepoint callback point
545 void SafepointSynchronize::block(JavaThread *thread) {
546 assert(thread != NULL, "thread must be set");
547 assert(thread->is_Java_thread(), "not a Java thread");
549 // Threads shouldn't block if they are in the middle of printing, but...
550 ttyLocker::break_tty_lock_for_safepoint(os::current_thread_id());
552 // Only bail from the block() call if the thread is gone from the
553 // thread list; starting to exit should still block.
554 if (thread->is_terminated()) {
555 // block current thread if we come here from native code when VM is gone
556 thread->block_if_vm_exited();
558 // otherwise do nothing
559 return;
560 }
562 JavaThreadState state = thread->thread_state();
563 thread->frame_anchor()->make_walkable(thread);
565 // Check that we have a valid thread_state at this point
566 switch(state) {
567 case _thread_in_vm_trans:
568 case _thread_in_Java: // From compiled code
570 // We are highly likely to block on the Safepoint_lock. In order to avoid blocking in this case,
571 // we pretend we are still in the VM.
572 thread->set_thread_state(_thread_in_vm);
574 if (is_synchronizing()) {
575 Atomic::inc (&TryingToBlock) ;
576 }
578 // We will always be holding the Safepoint_lock when we are examine the state
579 // of a thread. Hence, the instructions between the Safepoint_lock->lock() and
580 // Safepoint_lock->unlock() are happening atomic with regards to the safepoint code
581 Safepoint_lock->lock_without_safepoint_check();
582 if (is_synchronizing()) {
583 // Decrement the number of threads to wait for and signal vm thread
584 assert(_waiting_to_block > 0, "sanity check");
585 _waiting_to_block--;
586 thread->safepoint_state()->set_has_called_back(true);
588 // Consider (_waiting_to_block < 2) to pipeline the wakeup of the VM thread
589 if (_waiting_to_block == 0) {
590 Safepoint_lock->notify_all();
591 }
592 }
594 // We transition the thread to state _thread_blocked here, but
595 // we can't do our usual check for external suspension and then
596 // self-suspend after the lock_without_safepoint_check() call
597 // below because we are often called during transitions while
598 // we hold different locks. That would leave us suspended while
599 // holding a resource which results in deadlocks.
600 thread->set_thread_state(_thread_blocked);
601 Safepoint_lock->unlock();
603 // We now try to acquire the threads lock. Since this lock is hold by the VM thread during
604 // the entire safepoint, the threads will all line up here during the safepoint.
605 Threads_lock->lock_without_safepoint_check();
606 // restore original state. This is important if the thread comes from compiled code, so it
607 // will continue to execute with the _thread_in_Java state.
608 thread->set_thread_state(state);
609 Threads_lock->unlock();
610 break;
612 case _thread_in_native_trans:
613 case _thread_blocked_trans:
614 case _thread_new_trans:
615 if (thread->safepoint_state()->type() == ThreadSafepointState::_call_back) {
616 thread->print_thread_state();
617 fatal("Deadlock in safepoint code. "
618 "Should have called back to the VM before blocking.");
619 }
621 // We transition the thread to state _thread_blocked here, but
622 // we can't do our usual check for external suspension and then
623 // self-suspend after the lock_without_safepoint_check() call
624 // below because we are often called during transitions while
625 // we hold different locks. That would leave us suspended while
626 // holding a resource which results in deadlocks.
627 thread->set_thread_state(_thread_blocked);
629 // It is not safe to suspend a thread if we discover it is in _thread_in_native_trans. Hence,
630 // the safepoint code might still be waiting for it to block. We need to change the state here,
631 // so it can see that it is at a safepoint.
633 // Block until the safepoint operation is completed.
634 Threads_lock->lock_without_safepoint_check();
636 // Restore state
637 thread->set_thread_state(state);
639 Threads_lock->unlock();
640 break;
642 default:
643 fatal(err_msg("Illegal threadstate encountered: %d", state));
644 }
646 // Check for pending. async. exceptions or suspends - except if the
647 // thread was blocked inside the VM. has_special_runtime_exit_condition()
648 // is called last since it grabs a lock and we only want to do that when
649 // we must.
650 //
651 // Note: we never deliver an async exception at a polling point as the
652 // compiler may not have an exception handler for it. The polling
653 // code will notice the async and deoptimize and the exception will
654 // be delivered. (Polling at a return point is ok though). Sure is
655 // a lot of bother for a deprecated feature...
656 //
657 // We don't deliver an async exception if the thread state is
658 // _thread_in_native_trans so JNI functions won't be called with
659 // a surprising pending exception. If the thread state is going back to java,
660 // async exception is checked in check_special_condition_for_native_trans().
662 if (state != _thread_blocked_trans &&
663 state != _thread_in_vm_trans &&
664 thread->has_special_runtime_exit_condition()) {
665 thread->handle_special_runtime_exit_condition(
666 !thread->is_at_poll_safepoint() && (state != _thread_in_native_trans));
667 }
668 }
670 // ------------------------------------------------------------------------------------------------------
671 // Exception handlers
673 #ifndef PRODUCT
674 #ifdef _LP64
675 #define PTR_PAD ""
676 #else
677 #define PTR_PAD " "
678 #endif
680 static void print_ptrs(intptr_t oldptr, intptr_t newptr, bool wasoop) {
681 bool is_oop = newptr ? ((oop)newptr)->is_oop() : false;
682 tty->print_cr(PTR_FORMAT PTR_PAD " %s %c " PTR_FORMAT PTR_PAD " %s %s",
683 oldptr, wasoop?"oop":" ", oldptr == newptr ? ' ' : '!',
684 newptr, is_oop?"oop":" ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":" "));
685 }
687 static void print_longs(jlong oldptr, jlong newptr, bool wasoop) {
688 bool is_oop = newptr ? ((oop)(intptr_t)newptr)->is_oop() : false;
689 tty->print_cr(PTR64_FORMAT " %s %c " PTR64_FORMAT " %s %s",
690 oldptr, wasoop?"oop":" ", oldptr == newptr ? ' ' : '!',
691 newptr, is_oop?"oop":" ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":" "));
692 }
694 #ifdef SPARC
695 static void print_me(intptr_t *new_sp, intptr_t *old_sp, bool *was_oops) {
696 #ifdef _LP64
697 tty->print_cr("--------+------address-----+------before-----------+-------after----------+");
698 const int incr = 1; // Increment to skip a long, in units of intptr_t
699 #else
700 tty->print_cr("--------+--address-+------before-----------+-------after----------+");
701 const int incr = 2; // Increment to skip a long, in units of intptr_t
702 #endif
703 tty->print_cr("---SP---|");
704 for( int i=0; i<16; i++ ) {
705 tty->print("blob %c%d |"PTR_FORMAT" ","LO"[i>>3],i&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); }
706 tty->print_cr("--------|");
707 for( int i1=0; i1<frame::memory_parameter_word_sp_offset-16; i1++ ) {
708 tty->print("argv pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); }
709 tty->print(" pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++);
710 tty->print_cr("--------|");
711 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;
712 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;
713 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;
714 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;
715 tty->print_cr(" FSR |"PTR_FORMAT" "PTR64_FORMAT" "PTR64_FORMAT,new_sp,*(jlong*)old_sp,*(jlong*)new_sp);
716 old_sp += incr; new_sp += incr; was_oops += incr;
717 // Skip the floats
718 tty->print_cr("--Float-|"PTR_FORMAT,new_sp);
719 tty->print_cr("---FP---|");
720 old_sp += incr*32; new_sp += incr*32; was_oops += incr*32;
721 for( int i2=0; i2<16; i2++ ) {
722 tty->print("call %c%d |"PTR_FORMAT" ","LI"[i2>>3],i2&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); }
723 tty->print_cr("");
724 }
725 #endif // SPARC
726 #endif // PRODUCT
729 void SafepointSynchronize::handle_polling_page_exception(JavaThread *thread) {
730 assert(thread->is_Java_thread(), "polling reference encountered by VM thread");
731 assert(thread->thread_state() == _thread_in_Java, "should come from Java code");
732 assert(SafepointSynchronize::is_synchronizing(), "polling encountered outside safepoint synchronization");
734 // Uncomment this to get some serious before/after printing of the
735 // Sparc safepoint-blob frame structure.
736 /*
737 intptr_t* sp = thread->last_Java_sp();
738 intptr_t stack_copy[150];
739 for( int i=0; i<150; i++ ) stack_copy[i] = sp[i];
740 bool was_oops[150];
741 for( int i=0; i<150; i++ )
742 was_oops[i] = stack_copy[i] ? ((oop)stack_copy[i])->is_oop() : false;
743 */
745 if (ShowSafepointMsgs) {
746 tty->print("handle_polling_page_exception: ");
747 }
749 if (PrintSafepointStatistics) {
750 inc_page_trap_count();
751 }
753 ThreadSafepointState* state = thread->safepoint_state();
755 state->handle_polling_page_exception();
756 // print_me(sp,stack_copy,was_oops);
757 }
760 void SafepointSynchronize::print_safepoint_timeout(SafepointTimeoutReason reason) {
761 if (!timeout_error_printed) {
762 timeout_error_printed = true;
763 // Print out the thread infor which didn't reach the safepoint for debugging
764 // purposes (useful when there are lots of threads in the debugger).
765 tty->print_cr("");
766 tty->print_cr("# SafepointSynchronize::begin: Timeout detected:");
767 if (reason == _spinning_timeout) {
768 tty->print_cr("# SafepointSynchronize::begin: Timed out while spinning to reach a safepoint.");
769 } else if (reason == _blocking_timeout) {
770 tty->print_cr("# SafepointSynchronize::begin: Timed out while waiting for threads to stop.");
771 }
773 tty->print_cr("# SafepointSynchronize::begin: Threads which did not reach the safepoint:");
774 ThreadSafepointState *cur_state;
775 ResourceMark rm;
776 for(JavaThread *cur_thread = Threads::first(); cur_thread;
777 cur_thread = cur_thread->next()) {
778 cur_state = cur_thread->safepoint_state();
780 if (cur_thread->thread_state() != _thread_blocked &&
781 ((reason == _spinning_timeout && cur_state->is_running()) ||
782 (reason == _blocking_timeout && !cur_state->has_called_back()))) {
783 tty->print("# ");
784 cur_thread->print();
785 tty->print_cr("");
786 }
787 }
788 tty->print_cr("# SafepointSynchronize::begin: (End of list)");
789 }
791 // To debug the long safepoint, specify both DieOnSafepointTimeout &
792 // ShowMessageBoxOnError.
793 if (DieOnSafepointTimeout) {
794 char msg[1024];
795 VM_Operation *op = VMThread::vm_operation();
796 sprintf(msg, "Safepoint sync time longer than " INTX_FORMAT "ms detected when executing %s.",
797 SafepointTimeoutDelay,
798 op != NULL ? op->name() : "no vm operation");
799 fatal(msg);
800 }
801 }
804 // -------------------------------------------------------------------------------------------------------
805 // Implementation of ThreadSafepointState
807 ThreadSafepointState::ThreadSafepointState(JavaThread *thread) {
808 _thread = thread;
809 _type = _running;
810 _has_called_back = false;
811 _at_poll_safepoint = false;
812 }
814 void ThreadSafepointState::create(JavaThread *thread) {
815 ThreadSafepointState *state = new ThreadSafepointState(thread);
816 thread->set_safepoint_state(state);
817 }
819 void ThreadSafepointState::destroy(JavaThread *thread) {
820 if (thread->safepoint_state()) {
821 delete(thread->safepoint_state());
822 thread->set_safepoint_state(NULL);
823 }
824 }
826 void ThreadSafepointState::examine_state_of_thread() {
827 assert(is_running(), "better be running or just have hit safepoint poll");
829 JavaThreadState state = _thread->thread_state();
831 // Save the state at the start of safepoint processing.
832 _orig_thread_state = state;
834 // Check for a thread that is suspended. Note that thread resume tries
835 // to grab the Threads_lock which we own here, so a thread cannot be
836 // resumed during safepoint synchronization.
838 // We check to see if this thread is suspended without locking to
839 // avoid deadlocking with a third thread that is waiting for this
840 // thread to be suspended. The third thread can notice the safepoint
841 // that we're trying to start at the beginning of its SR_lock->wait()
842 // call. If that happens, then the third thread will block on the
843 // safepoint while still holding the underlying SR_lock. We won't be
844 // able to get the SR_lock and we'll deadlock.
845 //
846 // We don't need to grab the SR_lock here for two reasons:
847 // 1) The suspend flags are both volatile and are set with an
848 // Atomic::cmpxchg() call so we should see the suspended
849 // state right away.
850 // 2) We're being called from the safepoint polling loop; if
851 // we don't see the suspended state on this iteration, then
852 // we'll come around again.
853 //
854 bool is_suspended = _thread->is_ext_suspended();
855 if (is_suspended) {
856 roll_forward(_at_safepoint);
857 return;
858 }
860 // Some JavaThread states have an initial safepoint state of
861 // running, but are actually at a safepoint. We will happily
862 // agree and update the safepoint state here.
863 if (SafepointSynchronize::safepoint_safe(_thread, state)) {
864 roll_forward(_at_safepoint);
865 return;
866 }
868 if (state == _thread_in_vm) {
869 roll_forward(_call_back);
870 return;
871 }
873 // All other thread states will continue to run until they
874 // transition and self-block in state _blocked
875 // Safepoint polling in compiled code causes the Java threads to do the same.
876 // Note: new threads may require a malloc so they must be allowed to finish
878 assert(is_running(), "examine_state_of_thread on non-running thread");
879 return;
880 }
882 // Returns true is thread could not be rolled forward at present position.
883 void ThreadSafepointState::roll_forward(suspend_type type) {
884 _type = type;
886 switch(_type) {
887 case _at_safepoint:
888 SafepointSynchronize::signal_thread_at_safepoint();
889 break;
891 case _call_back:
892 set_has_called_back(false);
893 break;
895 case _running:
896 default:
897 ShouldNotReachHere();
898 }
899 }
901 void ThreadSafepointState::restart() {
902 switch(type()) {
903 case _at_safepoint:
904 case _call_back:
905 break;
907 case _running:
908 default:
909 tty->print_cr("restart thread "INTPTR_FORMAT" with state %d",
910 _thread, _type);
911 _thread->print();
912 ShouldNotReachHere();
913 }
914 _type = _running;
915 set_has_called_back(false);
916 }
919 void ThreadSafepointState::print_on(outputStream *st) const {
920 const char *s;
922 switch(_type) {
923 case _running : s = "_running"; break;
924 case _at_safepoint : s = "_at_safepoint"; break;
925 case _call_back : s = "_call_back"; break;
926 default:
927 ShouldNotReachHere();
928 }
930 st->print_cr("Thread: " INTPTR_FORMAT
931 " [0x%2x] State: %s _has_called_back %d _at_poll_safepoint %d",
932 _thread, _thread->osthread()->thread_id(), s, _has_called_back,
933 _at_poll_safepoint);
935 _thread->print_thread_state_on(st);
936 }
939 // ---------------------------------------------------------------------------------------------------------------------
941 // Block the thread at the safepoint poll or poll return.
942 void ThreadSafepointState::handle_polling_page_exception() {
944 // Check state. block() will set thread state to thread_in_vm which will
945 // cause the safepoint state _type to become _call_back.
946 assert(type() == ThreadSafepointState::_running,
947 "polling page exception on thread not running state");
949 // Step 1: Find the nmethod from the return address
950 if (ShowSafepointMsgs && Verbose) {
951 tty->print_cr("Polling page exception at " INTPTR_FORMAT, thread()->saved_exception_pc());
952 }
953 address real_return_addr = thread()->saved_exception_pc();
955 CodeBlob *cb = CodeCache::find_blob(real_return_addr);
956 assert(cb != NULL && cb->is_nmethod(), "return address should be in nmethod");
957 nmethod* nm = (nmethod*)cb;
959 // Find frame of caller
960 frame stub_fr = thread()->last_frame();
961 CodeBlob* stub_cb = stub_fr.cb();
962 assert(stub_cb->is_safepoint_stub(), "must be a safepoint stub");
963 RegisterMap map(thread(), true);
964 frame caller_fr = stub_fr.sender(&map);
966 // Should only be poll_return or poll
967 assert( nm->is_at_poll_or_poll_return(real_return_addr), "should not be at call" );
969 // This is a poll immediately before a return. The exception handling code
970 // has already had the effect of causing the return to occur, so the execution
971 // will continue immediately after the call. In addition, the oopmap at the
972 // return point does not mark the return value as an oop (if it is), so
973 // it needs a handle here to be updated.
974 if( nm->is_at_poll_return(real_return_addr) ) {
975 // See if return type is an oop.
976 bool return_oop = nm->method()->is_returning_oop();
977 Handle return_value;
978 if (return_oop) {
979 // The oop result has been saved on the stack together with all
980 // the other registers. In order to preserve it over GCs we need
981 // to keep it in a handle.
982 oop result = caller_fr.saved_oop_result(&map);
983 assert(result == NULL || result->is_oop(), "must be oop");
984 return_value = Handle(thread(), result);
985 assert(Universe::heap()->is_in_or_null(result), "must be heap pointer");
986 }
988 // Block the thread
989 SafepointSynchronize::block(thread());
991 // restore oop result, if any
992 if (return_oop) {
993 caller_fr.set_saved_oop_result(&map, return_value());
994 }
995 }
997 // This is a safepoint poll. Verify the return address and block.
998 else {
999 set_at_poll_safepoint(true);
1001 // verify the blob built the "return address" correctly
1002 assert(real_return_addr == caller_fr.pc(), "must match");
1004 // Block the thread
1005 SafepointSynchronize::block(thread());
1006 set_at_poll_safepoint(false);
1008 // If we have a pending async exception deoptimize the frame
1009 // as otherwise we may never deliver it.
1010 if (thread()->has_async_condition()) {
1011 ThreadInVMfromJavaNoAsyncException __tiv(thread());
1012 Deoptimization::deoptimize_frame(thread(), caller_fr.id());
1013 }
1015 // If an exception has been installed we must check for a pending deoptimization
1016 // Deoptimize frame if exception has been thrown.
1018 if (thread()->has_pending_exception() ) {
1019 RegisterMap map(thread(), true);
1020 frame caller_fr = stub_fr.sender(&map);
1021 if (caller_fr.is_deoptimized_frame()) {
1022 // The exception patch will destroy registers that are still
1023 // live and will be needed during deoptimization. Defer the
1024 // Async exception should have defered the exception until the
1025 // next safepoint which will be detected when we get into
1026 // the interpreter so if we have an exception now things
1027 // are messed up.
1029 fatal("Exception installed and deoptimization is pending");
1030 }
1031 }
1032 }
1033 }
1036 //
1037 // Statistics & Instrumentations
1038 //
1039 SafepointSynchronize::SafepointStats* SafepointSynchronize::_safepoint_stats = NULL;
1040 jlong SafepointSynchronize::_safepoint_begin_time = 0;
1041 int SafepointSynchronize::_cur_stat_index = 0;
1042 julong SafepointSynchronize::_safepoint_reasons[VM_Operation::VMOp_Terminating];
1043 julong SafepointSynchronize::_coalesced_vmop_count = 0;
1044 jlong SafepointSynchronize::_max_sync_time = 0;
1045 jlong SafepointSynchronize::_max_vmop_time = 0;
1046 float SafepointSynchronize::_ts_of_current_safepoint = 0.0f;
1048 static jlong cleanup_end_time = 0;
1049 static bool need_to_track_page_armed_status = false;
1050 static bool init_done = false;
1052 // Helper method to print the header.
1053 static void print_header() {
1054 tty->print(" vmop "
1055 "[threads: total initially_running wait_to_block] ");
1056 tty->print("[time: spin block sync cleanup vmop] ");
1058 // no page armed status printed out if it is always armed.
1059 if (need_to_track_page_armed_status) {
1060 tty->print("page_armed ");
1061 }
1063 tty->print_cr("page_trap_count");
1064 }
1066 void SafepointSynchronize::deferred_initialize_stat() {
1067 if (init_done) return;
1069 if (PrintSafepointStatisticsCount <= 0) {
1070 fatal("Wrong PrintSafepointStatisticsCount");
1071 }
1073 // If PrintSafepointStatisticsTimeout is specified, the statistics data will
1074 // be printed right away, in which case, _safepoint_stats will regress to
1075 // a single element array. Otherwise, it is a circular ring buffer with default
1076 // size of PrintSafepointStatisticsCount.
1077 int stats_array_size;
1078 if (PrintSafepointStatisticsTimeout > 0) {
1079 stats_array_size = 1;
1080 PrintSafepointStatistics = true;
1081 } else {
1082 stats_array_size = PrintSafepointStatisticsCount;
1083 }
1084 _safepoint_stats = (SafepointStats*)os::malloc(stats_array_size
1085 * sizeof(SafepointStats));
1086 guarantee(_safepoint_stats != NULL,
1087 "not enough memory for safepoint instrumentation data");
1089 if (UseCompilerSafepoints && DeferPollingPageLoopCount >= 0) {
1090 need_to_track_page_armed_status = true;
1091 }
1092 init_done = true;
1093 }
1095 void SafepointSynchronize::begin_statistics(int nof_threads, int nof_running) {
1096 assert(init_done, "safepoint statistics array hasn't been initialized");
1097 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
1099 spstat->_time_stamp = _ts_of_current_safepoint;
1101 VM_Operation *op = VMThread::vm_operation();
1102 spstat->_vmop_type = (op != NULL ? op->type() : -1);
1103 if (op != NULL) {
1104 _safepoint_reasons[spstat->_vmop_type]++;
1105 }
1107 spstat->_nof_total_threads = nof_threads;
1108 spstat->_nof_initial_running_threads = nof_running;
1109 spstat->_nof_threads_hit_page_trap = 0;
1111 // Records the start time of spinning. The real time spent on spinning
1112 // will be adjusted when spin is done. Same trick is applied for time
1113 // spent on waiting for threads to block.
1114 if (nof_running != 0) {
1115 spstat->_time_to_spin = os::javaTimeNanos();
1116 } else {
1117 spstat->_time_to_spin = 0;
1118 }
1119 }
1121 void SafepointSynchronize::update_statistics_on_spin_end() {
1122 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
1124 jlong cur_time = os::javaTimeNanos();
1126 spstat->_nof_threads_wait_to_block = _waiting_to_block;
1127 if (spstat->_nof_initial_running_threads != 0) {
1128 spstat->_time_to_spin = cur_time - spstat->_time_to_spin;
1129 }
1131 if (need_to_track_page_armed_status) {
1132 spstat->_page_armed = (PageArmed == 1);
1133 }
1135 // Records the start time of waiting for to block. Updated when block is done.
1136 if (_waiting_to_block != 0) {
1137 spstat->_time_to_wait_to_block = cur_time;
1138 } else {
1139 spstat->_time_to_wait_to_block = 0;
1140 }
1141 }
1143 void SafepointSynchronize::update_statistics_on_sync_end(jlong end_time) {
1144 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
1146 if (spstat->_nof_threads_wait_to_block != 0) {
1147 spstat->_time_to_wait_to_block = end_time -
1148 spstat->_time_to_wait_to_block;
1149 }
1151 // Records the end time of sync which will be used to calculate the total
1152 // vm operation time. Again, the real time spending in syncing will be deducted
1153 // from the start of the sync time later when end_statistics is called.
1154 spstat->_time_to_sync = end_time - _safepoint_begin_time;
1155 if (spstat->_time_to_sync > _max_sync_time) {
1156 _max_sync_time = spstat->_time_to_sync;
1157 }
1159 spstat->_time_to_do_cleanups = end_time;
1160 }
1162 void SafepointSynchronize::update_statistics_on_cleanup_end(jlong end_time) {
1163 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
1165 // Record how long spent in cleanup tasks.
1166 spstat->_time_to_do_cleanups = end_time - spstat->_time_to_do_cleanups;
1168 cleanup_end_time = end_time;
1169 }
1171 void SafepointSynchronize::end_statistics(jlong vmop_end_time) {
1172 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
1174 // Update the vm operation time.
1175 spstat->_time_to_exec_vmop = vmop_end_time - cleanup_end_time;
1176 if (spstat->_time_to_exec_vmop > _max_vmop_time) {
1177 _max_vmop_time = spstat->_time_to_exec_vmop;
1178 }
1179 // Only the sync time longer than the specified
1180 // PrintSafepointStatisticsTimeout will be printed out right away.
1181 // By default, it is -1 meaning all samples will be put into the list.
1182 if ( PrintSafepointStatisticsTimeout > 0) {
1183 if (spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) {
1184 print_statistics();
1185 }
1186 } else {
1187 // The safepoint statistics will be printed out when the _safepoin_stats
1188 // array fills up.
1189 if (_cur_stat_index == PrintSafepointStatisticsCount - 1) {
1190 print_statistics();
1191 _cur_stat_index = 0;
1192 } else {
1193 _cur_stat_index++;
1194 }
1195 }
1196 }
1198 void SafepointSynchronize::print_statistics() {
1199 SafepointStats* sstats = _safepoint_stats;
1201 for (int index = 0; index <= _cur_stat_index; index++) {
1202 if (index % 30 == 0) {
1203 print_header();
1204 }
1205 sstats = &_safepoint_stats[index];
1206 tty->print("%.3f: ", sstats->_time_stamp);
1207 tty->print("%-26s ["
1208 INT32_FORMAT_W(8)INT32_FORMAT_W(11)INT32_FORMAT_W(15)
1209 " ] ",
1210 sstats->_vmop_type == -1 ? "no vm operation" :
1211 VM_Operation::name(sstats->_vmop_type),
1212 sstats->_nof_total_threads,
1213 sstats->_nof_initial_running_threads,
1214 sstats->_nof_threads_wait_to_block);
1215 // "/ MICROUNITS " is to convert the unit from nanos to millis.
1216 tty->print(" ["
1217 INT64_FORMAT_W(6)INT64_FORMAT_W(6)
1218 INT64_FORMAT_W(6)INT64_FORMAT_W(6)
1219 INT64_FORMAT_W(6)" ] ",
1220 sstats->_time_to_spin / MICROUNITS,
1221 sstats->_time_to_wait_to_block / MICROUNITS,
1222 sstats->_time_to_sync / MICROUNITS,
1223 sstats->_time_to_do_cleanups / MICROUNITS,
1224 sstats->_time_to_exec_vmop / MICROUNITS);
1226 if (need_to_track_page_armed_status) {
1227 tty->print(INT32_FORMAT" ", sstats->_page_armed);
1228 }
1229 tty->print_cr(INT32_FORMAT" ", sstats->_nof_threads_hit_page_trap);
1230 }
1231 }
1233 // This method will be called when VM exits. It will first call
1234 // print_statistics to print out the rest of the sampling. Then
1235 // it tries to summarize the sampling.
1236 void SafepointSynchronize::print_stat_on_exit() {
1237 if (_safepoint_stats == NULL) return;
1239 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
1241 // During VM exit, end_statistics may not get called and in that
1242 // case, if the sync time is less than PrintSafepointStatisticsTimeout,
1243 // don't print it out.
1244 // Approximate the vm op time.
1245 _safepoint_stats[_cur_stat_index]._time_to_exec_vmop =
1246 os::javaTimeNanos() - cleanup_end_time;
1248 if ( PrintSafepointStatisticsTimeout < 0 ||
1249 spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) {
1250 print_statistics();
1251 }
1252 tty->print_cr("");
1254 // Print out polling page sampling status.
1255 if (!need_to_track_page_armed_status) {
1256 if (UseCompilerSafepoints) {
1257 tty->print_cr("Polling page always armed");
1258 }
1259 } else {
1260 tty->print_cr("Defer polling page loop count = %d\n",
1261 DeferPollingPageLoopCount);
1262 }
1264 for (int index = 0; index < VM_Operation::VMOp_Terminating; index++) {
1265 if (_safepoint_reasons[index] != 0) {
1266 tty->print_cr("%-26s"UINT64_FORMAT_W(10), VM_Operation::name(index),
1267 _safepoint_reasons[index]);
1268 }
1269 }
1271 tty->print_cr(UINT64_FORMAT_W(5)" VM operations coalesced during safepoint",
1272 _coalesced_vmop_count);
1273 tty->print_cr("Maximum sync time "INT64_FORMAT_W(5)" ms",
1274 _max_sync_time / MICROUNITS);
1275 tty->print_cr("Maximum vm operation time (except for Exit VM operation) "
1276 INT64_FORMAT_W(5)" ms",
1277 _max_vmop_time / MICROUNITS);
1278 }
1280 // ------------------------------------------------------------------------------------------------
1281 // Non-product code
1283 #ifndef PRODUCT
1285 void SafepointSynchronize::print_state() {
1286 if (_state == _not_synchronized) {
1287 tty->print_cr("not synchronized");
1288 } else if (_state == _synchronizing || _state == _synchronized) {
1289 tty->print_cr("State: %s", (_state == _synchronizing) ? "synchronizing" :
1290 "synchronized");
1292 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) {
1293 cur->safepoint_state()->print();
1294 }
1295 }
1296 }
1298 void SafepointSynchronize::safepoint_msg(const char* format, ...) {
1299 if (ShowSafepointMsgs) {
1300 va_list ap;
1301 va_start(ap, format);
1302 tty->vprint_cr(format, ap);
1303 va_end(ap);
1304 }
1305 }
1307 #endif // !PRODUCT