Mercurial > hg > graal-compiler
annotate src/share/vm/runtime/safepoint.cpp @ 1476:1f81c0d18c75
Build also release version of VM. Fix towards making SpecJVM2008 run.
author | Thomas Wuerthinger <wuerthinger@ssw.jku.at> |
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date | Fri, 26 Nov 2010 12:12:35 +0100 |
parents | 0f6600cee529 |
children | f03d0a26bf83 |
rev | line source |
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0 | 1 /* |
579 | 2 * Copyright 1997-2009 Sun Microsystems, Inc. All Rights Reserved. |
0 | 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
4 * | |
5 * This code is free software; you can redistribute it and/or modify it | |
6 * under the terms of the GNU General Public License version 2 only, as | |
7 * published by the Free Software Foundation. | |
8 * | |
9 * This code is distributed in the hope that it will be useful, but WITHOUT | |
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
12 * version 2 for more details (a copy is included in the LICENSE file that | |
13 * accompanied this code). | |
14 * | |
15 * You should have received a copy of the GNU General Public License version | |
16 * 2 along with this work; if not, write to the Free Software Foundation, | |
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
18 * | |
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, | |
20 * CA 95054 USA or visit www.sun.com if you need additional information or | |
21 * have any questions. | |
22 * | |
23 */ | |
24 | |
25 # include "incls/_precompiled.incl" | |
26 # include "incls/_safepoint.cpp.incl" | |
27 | |
28 // -------------------------------------------------------------------------------------------------- | |
29 // Implementation of Safepoint begin/end | |
30 | |
31 SafepointSynchronize::SynchronizeState volatile SafepointSynchronize::_state = SafepointSynchronize::_not_synchronized; | |
32 volatile int SafepointSynchronize::_waiting_to_block = 0; | |
33 volatile int SafepointSynchronize::_safepoint_counter = 0; | |
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34 long SafepointSynchronize::_end_of_last_safepoint = 0; |
0 | 35 static volatile int PageArmed = 0 ; // safepoint polling page is RO|RW vs PROT_NONE |
36 static volatile int TryingToBlock = 0 ; // proximate value -- for advisory use only | |
37 static bool timeout_error_printed = false; | |
38 | |
39 // Roll all threads forward to a safepoint and suspend them all | |
40 void SafepointSynchronize::begin() { | |
41 | |
42 Thread* myThread = Thread::current(); | |
43 assert(myThread->is_VM_thread(), "Only VM thread may execute a safepoint"); | |
44 | |
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45 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) { |
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46 _safepoint_begin_time = os::javaTimeNanos(); |
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47 _ts_of_current_safepoint = tty->time_stamp().seconds(); |
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48 } |
0 | 49 |
50 #ifndef SERIALGC | |
51 if (UseConcMarkSweepGC) { | |
52 // In the future we should investigate whether CMS can use the | |
53 // more-general mechanism below. DLD (01/05). | |
54 ConcurrentMarkSweepThread::synchronize(false); | |
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55 } else if (UseG1GC) { |
0 | 56 ConcurrentGCThread::safepoint_synchronize(); |
57 } | |
58 #endif // SERIALGC | |
59 | |
60 // By getting the Threads_lock, we assure that no threads are about to start or | |
61 // exit. It is released again in SafepointSynchronize::end(). | |
62 Threads_lock->lock(); | |
63 | |
64 assert( _state == _not_synchronized, "trying to safepoint synchronize with wrong state"); | |
65 | |
66 int nof_threads = Threads::number_of_threads(); | |
67 | |
68 if (TraceSafepoint) { | |
69 tty->print_cr("Safepoint synchronization initiated. (%d)", nof_threads); | |
70 } | |
71 | |
72 RuntimeService::record_safepoint_begin(); | |
73 | |
74 { | |
75 MutexLocker mu(Safepoint_lock); | |
76 | |
77 // Set number of threads to wait for, before we initiate the callbacks | |
78 _waiting_to_block = nof_threads; | |
79 TryingToBlock = 0 ; | |
80 int still_running = nof_threads; | |
81 | |
82 // Save the starting time, so that it can be compared to see if this has taken | |
83 // too long to complete. | |
84 jlong safepoint_limit_time; | |
85 timeout_error_printed = false; | |
86 | |
1003 | 87 // PrintSafepointStatisticsTimeout can be specified separately. When |
88 // specified, PrintSafepointStatistics will be set to true in | |
89 // deferred_initialize_stat method. The initialization has to be done | |
90 // early enough to avoid any races. See bug 6880029 for details. | |
91 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) { | |
92 deferred_initialize_stat(); | |
93 } | |
94 | |
0 | 95 // Begin the process of bringing the system to a safepoint. |
96 // Java threads can be in several different states and are | |
97 // stopped by different mechanisms: | |
98 // | |
99 // 1. Running interpreted | |
100 // The interpeter dispatch table is changed to force it to | |
101 // check for a safepoint condition between bytecodes. | |
102 // 2. Running in native code | |
103 // When returning from the native code, a Java thread must check | |
104 // the safepoint _state to see if we must block. If the | |
105 // VM thread sees a Java thread in native, it does | |
106 // not wait for this thread to block. The order of the memory | |
107 // writes and reads of both the safepoint state and the Java | |
108 // threads state is critical. In order to guarantee that the | |
109 // memory writes are serialized with respect to each other, | |
110 // the VM thread issues a memory barrier instruction | |
111 // (on MP systems). In order to avoid the overhead of issuing | |
112 // a memory barrier for each Java thread making native calls, each Java | |
113 // thread performs a write to a single memory page after changing | |
114 // the thread state. The VM thread performs a sequence of | |
115 // mprotect OS calls which forces all previous writes from all | |
116 // Java threads to be serialized. This is done in the | |
117 // os::serialize_thread_states() call. This has proven to be | |
118 // much more efficient than executing a membar instruction | |
119 // on every call to native code. | |
120 // 3. Running compiled Code | |
121 // Compiled code reads a global (Safepoint Polling) page that | |
122 // is set to fault if we are trying to get to a safepoint. | |
123 // 4. Blocked | |
124 // A thread which is blocked will not be allowed to return from the | |
125 // block condition until the safepoint operation is complete. | |
126 // 5. In VM or Transitioning between states | |
127 // If a Java thread is currently running in the VM or transitioning | |
128 // between states, the safepointing code will wait for the thread to | |
129 // block itself when it attempts transitions to a new state. | |
130 // | |
131 _state = _synchronizing; | |
132 OrderAccess::fence(); | |
133 | |
134 // Flush all thread states to memory | |
135 if (!UseMembar) { | |
136 os::serialize_thread_states(); | |
137 } | |
138 | |
139 // Make interpreter safepoint aware | |
140 Interpreter::notice_safepoints(); | |
141 | |
142 if (UseCompilerSafepoints && DeferPollingPageLoopCount < 0) { | |
143 // Make polling safepoint aware | |
144 guarantee (PageArmed == 0, "invariant") ; | |
145 PageArmed = 1 ; | |
146 os::make_polling_page_unreadable(); | |
147 } | |
148 | |
149 // Consider using active_processor_count() ... but that call is expensive. | |
150 int ncpus = os::processor_count() ; | |
151 | |
152 #ifdef ASSERT | |
153 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) { | |
154 assert(cur->safepoint_state()->is_running(), "Illegal initial state"); | |
155 } | |
156 #endif // ASSERT | |
157 | |
158 if (SafepointTimeout) | |
159 safepoint_limit_time = os::javaTimeNanos() + (jlong)SafepointTimeoutDelay * MICROUNITS; | |
160 | |
161 // Iterate through all threads until it have been determined how to stop them all at a safepoint | |
162 unsigned int iterations = 0; | |
163 int steps = 0 ; | |
164 while(still_running > 0) { | |
165 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) { | |
166 assert(!cur->is_ConcurrentGC_thread(), "A concurrent GC thread is unexpectly being suspended"); | |
167 ThreadSafepointState *cur_state = cur->safepoint_state(); | |
168 if (cur_state->is_running()) { | |
169 cur_state->examine_state_of_thread(); | |
170 if (!cur_state->is_running()) { | |
171 still_running--; | |
172 // consider adjusting steps downward: | |
173 // steps = 0 | |
174 // steps -= NNN | |
175 // steps >>= 1 | |
176 // steps = MIN(steps, 2000-100) | |
177 // if (iterations != 0) steps -= NNN | |
178 } | |
179 if (TraceSafepoint && Verbose) cur_state->print(); | |
180 } | |
181 } | |
182 | |
1003 | 183 if (PrintSafepointStatistics && iterations == 0) { |
0 | 184 begin_statistics(nof_threads, still_running); |
185 } | |
186 | |
187 if (still_running > 0) { | |
188 // Check for if it takes to long | |
189 if (SafepointTimeout && safepoint_limit_time < os::javaTimeNanos()) { | |
190 print_safepoint_timeout(_spinning_timeout); | |
191 } | |
192 | |
193 // Spin to avoid context switching. | |
194 // There's a tension between allowing the mutators to run (and rendezvous) | |
195 // vs spinning. As the VM thread spins, wasting cycles, it consumes CPU that | |
196 // a mutator might otherwise use profitably to reach a safepoint. Excessive | |
197 // spinning by the VM thread on a saturated system can increase rendezvous latency. | |
198 // Blocking or yielding incur their own penalties in the form of context switching | |
199 // and the resultant loss of $ residency. | |
200 // | |
201 // Further complicating matters is that yield() does not work as naively expected | |
202 // on many platforms -- yield() does not guarantee that any other ready threads | |
203 // will run. As such we revert yield_all() after some number of iterations. | |
204 // Yield_all() is implemented as a short unconditional sleep on some platforms. | |
205 // Typical operating systems round a "short" sleep period up to 10 msecs, so sleeping | |
206 // can actually increase the time it takes the VM thread to detect that a system-wide | |
207 // stop-the-world safepoint has been reached. In a pathological scenario such as that | |
208 // described in CR6415670 the VMthread may sleep just before the mutator(s) become safe. | |
209 // In that case the mutators will be stalled waiting for the safepoint to complete and the | |
210 // the VMthread will be sleeping, waiting for the mutators to rendezvous. The VMthread | |
211 // will eventually wake up and detect that all mutators are safe, at which point | |
212 // we'll again make progress. | |
213 // | |
214 // Beware too that that the VMThread typically runs at elevated priority. | |
215 // Its default priority is higher than the default mutator priority. | |
216 // Obviously, this complicates spinning. | |
217 // | |
218 // Note too that on Windows XP SwitchThreadTo() has quite different behavior than Sleep(0). | |
219 // Sleep(0) will _not yield to lower priority threads, while SwitchThreadTo() will. | |
220 // | |
221 // See the comments in synchronizer.cpp for additional remarks on spinning. | |
222 // | |
223 // In the future we might: | |
224 // 1. Modify the safepoint scheme to avoid potentally unbounded spinning. | |
225 // This is tricky as the path used by a thread exiting the JVM (say on | |
226 // on JNI call-out) simply stores into its state field. The burden | |
227 // is placed on the VM thread, which must poll (spin). | |
228 // 2. Find something useful to do while spinning. If the safepoint is GC-related | |
229 // we might aggressively scan the stacks of threads that are already safe. | |
230 // 3. Use Solaris schedctl to examine the state of the still-running mutators. | |
231 // If all the mutators are ONPROC there's no reason to sleep or yield. | |
232 // 4. YieldTo() any still-running mutators that are ready but OFFPROC. | |
233 // 5. Check system saturation. If the system is not fully saturated then | |
234 // simply spin and avoid sleep/yield. | |
235 // 6. As still-running mutators rendezvous they could unpark the sleeping | |
236 // VMthread. This works well for still-running mutators that become | |
237 // safe. The VMthread must still poll for mutators that call-out. | |
238 // 7. Drive the policy on time-since-begin instead of iterations. | |
239 // 8. Consider making the spin duration a function of the # of CPUs: | |
240 // Spin = (((ncpus-1) * M) + K) + F(still_running) | |
241 // Alternately, instead of counting iterations of the outer loop | |
242 // we could count the # of threads visited in the inner loop, above. | |
243 // 9. On windows consider using the return value from SwitchThreadTo() | |
244 // to drive subsequent spin/SwitchThreadTo()/Sleep(N) decisions. | |
245 | |
246 if (UseCompilerSafepoints && int(iterations) == DeferPollingPageLoopCount) { | |
247 guarantee (PageArmed == 0, "invariant") ; | |
248 PageArmed = 1 ; | |
249 os::make_polling_page_unreadable(); | |
250 } | |
251 | |
252 // Instead of (ncpus > 1) consider either (still_running < (ncpus + EPSILON)) or | |
253 // ((still_running + _waiting_to_block - TryingToBlock)) < ncpus) | |
254 ++steps ; | |
255 if (ncpus > 1 && steps < SafepointSpinBeforeYield) { | |
256 SpinPause() ; // MP-Polite spin | |
257 } else | |
258 if (steps < DeferThrSuspendLoopCount) { | |
259 os::NakedYield() ; | |
260 } else { | |
261 os::yield_all(steps) ; | |
262 // Alternately, the VM thread could transiently depress its scheduling priority or | |
263 // transiently increase the priority of the tardy mutator(s). | |
264 } | |
265 | |
266 iterations ++ ; | |
267 } | |
268 assert(iterations < (uint)max_jint, "We have been iterating in the safepoint loop too long"); | |
269 } | |
270 assert(still_running == 0, "sanity check"); | |
271 | |
272 if (PrintSafepointStatistics) { | |
273 update_statistics_on_spin_end(); | |
274 } | |
275 | |
276 // wait until all threads are stopped | |
277 while (_waiting_to_block > 0) { | |
278 if (TraceSafepoint) tty->print_cr("Waiting for %d thread(s) to block", _waiting_to_block); | |
279 if (!SafepointTimeout || timeout_error_printed) { | |
280 Safepoint_lock->wait(true); // true, means with no safepoint checks | |
281 } else { | |
282 // Compute remaining time | |
283 jlong remaining_time = safepoint_limit_time - os::javaTimeNanos(); | |
284 | |
285 // If there is no remaining time, then there is an error | |
286 if (remaining_time < 0 || Safepoint_lock->wait(true, remaining_time / MICROUNITS)) { | |
287 print_safepoint_timeout(_blocking_timeout); | |
288 } | |
289 } | |
290 } | |
291 assert(_waiting_to_block == 0, "sanity check"); | |
292 | |
293 #ifndef PRODUCT | |
294 if (SafepointTimeout) { | |
295 jlong current_time = os::javaTimeNanos(); | |
296 if (safepoint_limit_time < current_time) { | |
297 tty->print_cr("# SafepointSynchronize: Finished after " | |
298 INT64_FORMAT_W(6) " ms", | |
299 ((current_time - safepoint_limit_time) / MICROUNITS + | |
300 SafepointTimeoutDelay)); | |
301 } | |
302 } | |
303 #endif | |
304 | |
305 assert((_safepoint_counter & 0x1) == 0, "must be even"); | |
306 assert(Threads_lock->owned_by_self(), "must hold Threads_lock"); | |
307 _safepoint_counter ++; | |
308 | |
309 // Record state | |
310 _state = _synchronized; | |
311 | |
312 OrderAccess::fence(); | |
313 | |
314 if (TraceSafepoint) { | |
315 VM_Operation *op = VMThread::vm_operation(); | |
316 tty->print_cr("Entering safepoint region: %s", (op != NULL) ? op->name() : "no vm operation"); | |
317 } | |
318 | |
319 RuntimeService::record_safepoint_synchronized(); | |
320 if (PrintSafepointStatistics) { | |
321 update_statistics_on_sync_end(os::javaTimeNanos()); | |
322 } | |
323 | |
324 // Call stuff that needs to be run when a safepoint is just about to be completed | |
325 do_cleanup_tasks(); | |
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326 |
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327 if (PrintSafepointStatistics) { |
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328 // Record how much time spend on the above cleanup tasks |
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329 update_statistics_on_cleanup_end(os::javaTimeNanos()); |
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330 } |
0 | 331 } |
332 } | |
333 | |
334 // Wake up all threads, so they are ready to resume execution after the safepoint | |
335 // operation has been carried out | |
336 void SafepointSynchronize::end() { | |
337 | |
338 assert(Threads_lock->owned_by_self(), "must hold Threads_lock"); | |
339 assert((_safepoint_counter & 0x1) == 1, "must be odd"); | |
340 _safepoint_counter ++; | |
341 // memory fence isn't required here since an odd _safepoint_counter | |
342 // value can do no harm and a fence is issued below anyway. | |
343 | |
344 DEBUG_ONLY(Thread* myThread = Thread::current();) | |
345 assert(myThread->is_VM_thread(), "Only VM thread can execute a safepoint"); | |
346 | |
347 if (PrintSafepointStatistics) { | |
348 end_statistics(os::javaTimeNanos()); | |
349 } | |
350 | |
351 #ifdef ASSERT | |
352 // A pending_exception cannot be installed during a safepoint. The threads | |
353 // may install an async exception after they come back from a safepoint into | |
354 // pending_exception after they unblock. But that should happen later. | |
355 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) { | |
356 assert (!(cur->has_pending_exception() && | |
357 cur->safepoint_state()->is_at_poll_safepoint()), | |
358 "safepoint installed a pending exception"); | |
359 } | |
360 #endif // ASSERT | |
361 | |
362 if (PageArmed) { | |
363 // Make polling safepoint aware | |
364 os::make_polling_page_readable(); | |
365 PageArmed = 0 ; | |
366 } | |
367 | |
368 // Remove safepoint check from interpreter | |
369 Interpreter::ignore_safepoints(); | |
370 | |
371 { | |
372 MutexLocker mu(Safepoint_lock); | |
373 | |
374 assert(_state == _synchronized, "must be synchronized before ending safepoint synchronization"); | |
375 | |
376 // Set to not synchronized, so the threads will not go into the signal_thread_blocked method | |
377 // when they get restarted. | |
378 _state = _not_synchronized; | |
379 OrderAccess::fence(); | |
380 | |
381 if (TraceSafepoint) { | |
382 tty->print_cr("Leaving safepoint region"); | |
383 } | |
384 | |
385 // Start suspended threads | |
386 for(JavaThread *current = Threads::first(); current; current = current->next()) { | |
605 | 387 // A problem occurring on Solaris is when attempting to restart threads |
0 | 388 // the first #cpus - 1 go well, but then the VMThread is preempted when we get |
389 // to the next one (since it has been running the longest). We then have | |
390 // to wait for a cpu to become available before we can continue restarting | |
391 // threads. | |
392 // FIXME: This causes the performance of the VM to degrade when active and with | |
393 // large numbers of threads. Apparently this is due to the synchronous nature | |
394 // of suspending threads. | |
395 // | |
396 // TODO-FIXME: the comments above are vestigial and no longer apply. | |
397 // Furthermore, using solaris' schedctl in this particular context confers no benefit | |
398 if (VMThreadHintNoPreempt) { | |
399 os::hint_no_preempt(); | |
400 } | |
401 ThreadSafepointState* cur_state = current->safepoint_state(); | |
402 assert(cur_state->type() != ThreadSafepointState::_running, "Thread not suspended at safepoint"); | |
403 cur_state->restart(); | |
404 assert(cur_state->is_running(), "safepoint state has not been reset"); | |
405 } | |
406 | |
407 RuntimeService::record_safepoint_end(); | |
408 | |
409 // Release threads lock, so threads can be created/destroyed again. It will also starts all threads | |
410 // blocked in signal_thread_blocked | |
411 Threads_lock->unlock(); | |
412 | |
413 } | |
414 #ifndef SERIALGC | |
415 // If there are any concurrent GC threads resume them. | |
416 if (UseConcMarkSweepGC) { | |
417 ConcurrentMarkSweepThread::desynchronize(false); | |
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418 } else if (UseG1GC) { |
0 | 419 ConcurrentGCThread::safepoint_desynchronize(); |
420 } | |
421 #endif // SERIALGC | |
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422 // record this time so VMThread can keep track how much time has elasped |
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423 // since last safepoint. |
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424 _end_of_last_safepoint = os::javaTimeMillis(); |
0 | 425 } |
426 | |
427 bool SafepointSynchronize::is_cleanup_needed() { | |
428 // Need a safepoint if some inline cache buffers is non-empty | |
429 if (!InlineCacheBuffer::is_empty()) return true; | |
430 return false; | |
431 } | |
432 | |
433 jlong CounterDecay::_last_timestamp = 0; | |
434 | |
435 static void do_method(methodOop m) { | |
436 m->invocation_counter()->decay(); | |
437 } | |
438 | |
439 void CounterDecay::decay() { | |
440 _last_timestamp = os::javaTimeMillis(); | |
441 | |
442 // This operation is going to be performed only at the end of a safepoint | |
443 // and hence GC's will not be going on, all Java mutators are suspended | |
444 // at this point and hence SystemDictionary_lock is also not needed. | |
445 assert(SafepointSynchronize::is_at_safepoint(), "can only be executed at a safepoint"); | |
446 int nclasses = SystemDictionary::number_of_classes(); | |
447 double classes_per_tick = nclasses * (CounterDecayMinIntervalLength * 1e-3 / | |
448 CounterHalfLifeTime); | |
449 for (int i = 0; i < classes_per_tick; i++) { | |
450 klassOop k = SystemDictionary::try_get_next_class(); | |
451 if (k != NULL && k->klass_part()->oop_is_instance()) { | |
452 instanceKlass::cast(k)->methods_do(do_method); | |
453 } | |
454 } | |
455 } | |
456 | |
457 // Various cleaning tasks that should be done periodically at safepoints | |
458 void SafepointSynchronize::do_cleanup_tasks() { | |
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459 { |
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460 TraceTime t1("deflating idle monitors", TraceSafepointCleanupTime); |
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461 ObjectSynchronizer::deflate_idle_monitors(); |
0 | 462 } |
463 | |
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464 { |
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465 TraceTime t2("updating inline caches", TraceSafepointCleanupTime); |
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466 InlineCacheBuffer::update_inline_caches(); |
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467 } |
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468 |
0 | 469 if(UseCounterDecay && CounterDecay::is_decay_needed()) { |
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470 TraceTime t3("decaying counter", TraceSafepointCleanupTime); |
0 | 471 CounterDecay::decay(); |
472 } | |
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473 |
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474 TraceTime t4("sweeping nmethods", TraceSafepointCleanupTime); |
0 | 475 NMethodSweeper::sweep(); |
476 } | |
477 | |
478 | |
479 bool SafepointSynchronize::safepoint_safe(JavaThread *thread, JavaThreadState state) { | |
480 switch(state) { | |
481 case _thread_in_native: | |
482 // native threads are safe if they have no java stack or have walkable stack | |
483 return !thread->has_last_Java_frame() || thread->frame_anchor()->walkable(); | |
484 | |
485 // blocked threads should have already have walkable stack | |
486 case _thread_blocked: | |
487 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "blocked and not walkable"); | |
488 return true; | |
489 | |
490 default: | |
491 return false; | |
492 } | |
493 } | |
494 | |
495 | |
496 // ------------------------------------------------------------------------------------------------------- | |
497 // Implementation of Safepoint callback point | |
498 | |
499 void SafepointSynchronize::block(JavaThread *thread) { | |
500 assert(thread != NULL, "thread must be set"); | |
501 assert(thread->is_Java_thread(), "not a Java thread"); | |
502 | |
503 // Threads shouldn't block if they are in the middle of printing, but... | |
504 ttyLocker::break_tty_lock_for_safepoint(os::current_thread_id()); | |
505 | |
506 // Only bail from the block() call if the thread is gone from the | |
507 // thread list; starting to exit should still block. | |
508 if (thread->is_terminated()) { | |
509 // block current thread if we come here from native code when VM is gone | |
510 thread->block_if_vm_exited(); | |
511 | |
512 // otherwise do nothing | |
513 return; | |
514 } | |
515 | |
516 JavaThreadState state = thread->thread_state(); | |
517 thread->frame_anchor()->make_walkable(thread); | |
518 | |
519 // Check that we have a valid thread_state at this point | |
520 switch(state) { | |
521 case _thread_in_vm_trans: | |
522 case _thread_in_Java: // From compiled code | |
523 | |
524 // We are highly likely to block on the Safepoint_lock. In order to avoid blocking in this case, | |
525 // we pretend we are still in the VM. | |
526 thread->set_thread_state(_thread_in_vm); | |
527 | |
528 if (is_synchronizing()) { | |
529 Atomic::inc (&TryingToBlock) ; | |
530 } | |
531 | |
532 // We will always be holding the Safepoint_lock when we are examine the state | |
533 // of a thread. Hence, the instructions between the Safepoint_lock->lock() and | |
534 // Safepoint_lock->unlock() are happening atomic with regards to the safepoint code | |
535 Safepoint_lock->lock_without_safepoint_check(); | |
536 if (is_synchronizing()) { | |
537 // Decrement the number of threads to wait for and signal vm thread | |
538 assert(_waiting_to_block > 0, "sanity check"); | |
539 _waiting_to_block--; | |
540 thread->safepoint_state()->set_has_called_back(true); | |
541 | |
542 // Consider (_waiting_to_block < 2) to pipeline the wakeup of the VM thread | |
543 if (_waiting_to_block == 0) { | |
544 Safepoint_lock->notify_all(); | |
545 } | |
546 } | |
547 | |
548 // We transition the thread to state _thread_blocked here, but | |
549 // we can't do our usual check for external suspension and then | |
550 // self-suspend after the lock_without_safepoint_check() call | |
551 // below because we are often called during transitions while | |
552 // we hold different locks. That would leave us suspended while | |
553 // holding a resource which results in deadlocks. | |
554 thread->set_thread_state(_thread_blocked); | |
555 Safepoint_lock->unlock(); | |
556 | |
557 // We now try to acquire the threads lock. Since this lock is hold by the VM thread during | |
558 // the entire safepoint, the threads will all line up here during the safepoint. | |
559 Threads_lock->lock_without_safepoint_check(); | |
560 // restore original state. This is important if the thread comes from compiled code, so it | |
561 // will continue to execute with the _thread_in_Java state. | |
562 thread->set_thread_state(state); | |
563 Threads_lock->unlock(); | |
564 break; | |
565 | |
566 case _thread_in_native_trans: | |
567 case _thread_blocked_trans: | |
568 case _thread_new_trans: | |
569 if (thread->safepoint_state()->type() == ThreadSafepointState::_call_back) { | |
570 thread->print_thread_state(); | |
571 fatal("Deadlock in safepoint code. " | |
572 "Should have called back to the VM before blocking."); | |
573 } | |
574 | |
575 // We transition the thread to state _thread_blocked here, but | |
576 // we can't do our usual check for external suspension and then | |
577 // self-suspend after the lock_without_safepoint_check() call | |
578 // below because we are often called during transitions while | |
579 // we hold different locks. That would leave us suspended while | |
580 // holding a resource which results in deadlocks. | |
581 thread->set_thread_state(_thread_blocked); | |
582 | |
583 // It is not safe to suspend a thread if we discover it is in _thread_in_native_trans. Hence, | |
584 // the safepoint code might still be waiting for it to block. We need to change the state here, | |
585 // so it can see that it is at a safepoint. | |
586 | |
587 // Block until the safepoint operation is completed. | |
588 Threads_lock->lock_without_safepoint_check(); | |
589 | |
590 // Restore state | |
591 thread->set_thread_state(state); | |
592 | |
593 Threads_lock->unlock(); | |
594 break; | |
595 | |
596 default: | |
597 fatal1("Illegal threadstate encountered: %d", state); | |
598 } | |
599 | |
600 // Check for pending. async. exceptions or suspends - except if the | |
601 // thread was blocked inside the VM. has_special_runtime_exit_condition() | |
602 // is called last since it grabs a lock and we only want to do that when | |
603 // we must. | |
604 // | |
605 // Note: we never deliver an async exception at a polling point as the | |
606 // compiler may not have an exception handler for it. The polling | |
607 // code will notice the async and deoptimize and the exception will | |
608 // be delivered. (Polling at a return point is ok though). Sure is | |
609 // a lot of bother for a deprecated feature... | |
610 // | |
611 // We don't deliver an async exception if the thread state is | |
612 // _thread_in_native_trans so JNI functions won't be called with | |
613 // a surprising pending exception. If the thread state is going back to java, | |
614 // async exception is checked in check_special_condition_for_native_trans(). | |
615 | |
616 if (state != _thread_blocked_trans && | |
617 state != _thread_in_vm_trans && | |
618 thread->has_special_runtime_exit_condition()) { | |
619 thread->handle_special_runtime_exit_condition( | |
620 !thread->is_at_poll_safepoint() && (state != _thread_in_native_trans)); | |
621 } | |
622 } | |
623 | |
624 // ------------------------------------------------------------------------------------------------------ | |
625 // Exception handlers | |
626 | |
627 #ifndef PRODUCT | |
628 #ifdef _LP64 | |
629 #define PTR_PAD "" | |
630 #else | |
631 #define PTR_PAD " " | |
632 #endif | |
633 | |
634 static void print_ptrs(intptr_t oldptr, intptr_t newptr, bool wasoop) { | |
635 bool is_oop = newptr ? ((oop)newptr)->is_oop() : false; | |
636 tty->print_cr(PTR_FORMAT PTR_PAD " %s %c " PTR_FORMAT PTR_PAD " %s %s", | |
637 oldptr, wasoop?"oop":" ", oldptr == newptr ? ' ' : '!', | |
638 newptr, is_oop?"oop":" ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":" ")); | |
639 } | |
640 | |
641 static void print_longs(jlong oldptr, jlong newptr, bool wasoop) { | |
642 bool is_oop = newptr ? ((oop)(intptr_t)newptr)->is_oop() : false; | |
643 tty->print_cr(PTR64_FORMAT " %s %c " PTR64_FORMAT " %s %s", | |
644 oldptr, wasoop?"oop":" ", oldptr == newptr ? ' ' : '!', | |
645 newptr, is_oop?"oop":" ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":" ")); | |
646 } | |
647 | |
648 #ifdef SPARC | |
649 static void print_me(intptr_t *new_sp, intptr_t *old_sp, bool *was_oops) { | |
650 #ifdef _LP64 | |
651 tty->print_cr("--------+------address-----+------before-----------+-------after----------+"); | |
652 const int incr = 1; // Increment to skip a long, in units of intptr_t | |
653 #else | |
654 tty->print_cr("--------+--address-+------before-----------+-------after----------+"); | |
655 const int incr = 2; // Increment to skip a long, in units of intptr_t | |
656 #endif | |
657 tty->print_cr("---SP---|"); | |
658 for( int i=0; i<16; i++ ) { | |
659 tty->print("blob %c%d |"PTR_FORMAT" ","LO"[i>>3],i&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); } | |
660 tty->print_cr("--------|"); | |
661 for( int i1=0; i1<frame::memory_parameter_word_sp_offset-16; i1++ ) { | |
662 tty->print("argv pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); } | |
663 tty->print(" pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); | |
664 tty->print_cr("--------|"); | |
665 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; | |
666 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; | |
667 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; | |
668 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; | |
669 tty->print_cr(" FSR |"PTR_FORMAT" "PTR64_FORMAT" "PTR64_FORMAT,new_sp,*(jlong*)old_sp,*(jlong*)new_sp); | |
670 old_sp += incr; new_sp += incr; was_oops += incr; | |
671 // Skip the floats | |
672 tty->print_cr("--Float-|"PTR_FORMAT,new_sp); | |
673 tty->print_cr("---FP---|"); | |
674 old_sp += incr*32; new_sp += incr*32; was_oops += incr*32; | |
675 for( int i2=0; i2<16; i2++ ) { | |
676 tty->print("call %c%d |"PTR_FORMAT" ","LI"[i2>>3],i2&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); } | |
677 tty->print_cr(""); | |
678 } | |
679 #endif // SPARC | |
680 #endif // PRODUCT | |
681 | |
682 | |
683 void SafepointSynchronize::handle_polling_page_exception(JavaThread *thread) { | |
684 assert(thread->is_Java_thread(), "polling reference encountered by VM thread"); | |
685 assert(thread->thread_state() == _thread_in_Java, "should come from Java code"); | |
686 assert(SafepointSynchronize::is_synchronizing(), "polling encountered outside safepoint synchronization"); | |
687 | |
688 // Uncomment this to get some serious before/after printing of the | |
689 // Sparc safepoint-blob frame structure. | |
690 /* | |
691 intptr_t* sp = thread->last_Java_sp(); | |
692 intptr_t stack_copy[150]; | |
693 for( int i=0; i<150; i++ ) stack_copy[i] = sp[i]; | |
694 bool was_oops[150]; | |
695 for( int i=0; i<150; i++ ) | |
696 was_oops[i] = stack_copy[i] ? ((oop)stack_copy[i])->is_oop() : false; | |
697 */ | |
698 | |
699 if (ShowSafepointMsgs) { | |
700 tty->print("handle_polling_page_exception: "); | |
701 } | |
702 | |
703 if (PrintSafepointStatistics) { | |
704 inc_page_trap_count(); | |
705 } | |
706 | |
707 ThreadSafepointState* state = thread->safepoint_state(); | |
708 | |
709 state->handle_polling_page_exception(); | |
710 // print_me(sp,stack_copy,was_oops); | |
711 } | |
712 | |
713 | |
714 void SafepointSynchronize::print_safepoint_timeout(SafepointTimeoutReason reason) { | |
715 if (!timeout_error_printed) { | |
716 timeout_error_printed = true; | |
717 // Print out the thread infor which didn't reach the safepoint for debugging | |
718 // purposes (useful when there are lots of threads in the debugger). | |
719 tty->print_cr(""); | |
720 tty->print_cr("# SafepointSynchronize::begin: Timeout detected:"); | |
721 if (reason == _spinning_timeout) { | |
722 tty->print_cr("# SafepointSynchronize::begin: Timed out while spinning to reach a safepoint."); | |
723 } else if (reason == _blocking_timeout) { | |
724 tty->print_cr("# SafepointSynchronize::begin: Timed out while waiting for threads to stop."); | |
725 } | |
726 | |
727 tty->print_cr("# SafepointSynchronize::begin: Threads which did not reach the safepoint:"); | |
728 ThreadSafepointState *cur_state; | |
729 ResourceMark rm; | |
730 for(JavaThread *cur_thread = Threads::first(); cur_thread; | |
731 cur_thread = cur_thread->next()) { | |
732 cur_state = cur_thread->safepoint_state(); | |
733 | |
734 if (cur_thread->thread_state() != _thread_blocked && | |
735 ((reason == _spinning_timeout && cur_state->is_running()) || | |
736 (reason == _blocking_timeout && !cur_state->has_called_back()))) { | |
737 tty->print("# "); | |
738 cur_thread->print(); | |
739 tty->print_cr(""); | |
740 } | |
741 } | |
742 tty->print_cr("# SafepointSynchronize::begin: (End of list)"); | |
743 } | |
744 | |
745 // To debug the long safepoint, specify both DieOnSafepointTimeout & | |
746 // ShowMessageBoxOnError. | |
747 if (DieOnSafepointTimeout) { | |
748 char msg[1024]; | |
749 VM_Operation *op = VMThread::vm_operation(); | |
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750 sprintf(msg, "Safepoint sync time longer than " INTX_FORMAT "ms detected when executing %s.", |
0 | 751 SafepointTimeoutDelay, |
752 op != NULL ? op->name() : "no vm operation"); | |
753 fatal(msg); | |
754 } | |
755 } | |
756 | |
757 | |
758 // ------------------------------------------------------------------------------------------------------- | |
759 // Implementation of ThreadSafepointState | |
760 | |
761 ThreadSafepointState::ThreadSafepointState(JavaThread *thread) { | |
762 _thread = thread; | |
763 _type = _running; | |
764 _has_called_back = false; | |
765 _at_poll_safepoint = false; | |
766 } | |
767 | |
768 void ThreadSafepointState::create(JavaThread *thread) { | |
769 ThreadSafepointState *state = new ThreadSafepointState(thread); | |
770 thread->set_safepoint_state(state); | |
771 } | |
772 | |
773 void ThreadSafepointState::destroy(JavaThread *thread) { | |
774 if (thread->safepoint_state()) { | |
775 delete(thread->safepoint_state()); | |
776 thread->set_safepoint_state(NULL); | |
777 } | |
778 } | |
779 | |
780 void ThreadSafepointState::examine_state_of_thread() { | |
781 assert(is_running(), "better be running or just have hit safepoint poll"); | |
782 | |
783 JavaThreadState state = _thread->thread_state(); | |
784 | |
785 // Check for a thread that is suspended. Note that thread resume tries | |
786 // to grab the Threads_lock which we own here, so a thread cannot be | |
787 // resumed during safepoint synchronization. | |
788 | |
979 | 789 // We check to see if this thread is suspended without locking to |
790 // avoid deadlocking with a third thread that is waiting for this | |
791 // thread to be suspended. The third thread can notice the safepoint | |
792 // that we're trying to start at the beginning of its SR_lock->wait() | |
793 // call. If that happens, then the third thread will block on the | |
794 // safepoint while still holding the underlying SR_lock. We won't be | |
795 // able to get the SR_lock and we'll deadlock. | |
796 // | |
797 // We don't need to grab the SR_lock here for two reasons: | |
798 // 1) The suspend flags are both volatile and are set with an | |
799 // Atomic::cmpxchg() call so we should see the suspended | |
800 // state right away. | |
801 // 2) We're being called from the safepoint polling loop; if | |
802 // we don't see the suspended state on this iteration, then | |
803 // we'll come around again. | |
804 // | |
805 bool is_suspended = _thread->is_ext_suspended(); | |
0 | 806 if (is_suspended) { |
807 roll_forward(_at_safepoint); | |
808 return; | |
809 } | |
810 | |
811 // Some JavaThread states have an initial safepoint state of | |
812 // running, but are actually at a safepoint. We will happily | |
813 // agree and update the safepoint state here. | |
814 if (SafepointSynchronize::safepoint_safe(_thread, state)) { | |
815 roll_forward(_at_safepoint); | |
816 return; | |
817 } | |
818 | |
819 if (state == _thread_in_vm) { | |
820 roll_forward(_call_back); | |
821 return; | |
822 } | |
823 | |
824 // All other thread states will continue to run until they | |
825 // transition and self-block in state _blocked | |
826 // Safepoint polling in compiled code causes the Java threads to do the same. | |
827 // Note: new threads may require a malloc so they must be allowed to finish | |
828 | |
829 assert(is_running(), "examine_state_of_thread on non-running thread"); | |
830 return; | |
831 } | |
832 | |
833 // Returns true is thread could not be rolled forward at present position. | |
834 void ThreadSafepointState::roll_forward(suspend_type type) { | |
835 _type = type; | |
836 | |
837 switch(_type) { | |
838 case _at_safepoint: | |
839 SafepointSynchronize::signal_thread_at_safepoint(); | |
840 break; | |
841 | |
842 case _call_back: | |
843 set_has_called_back(false); | |
844 break; | |
845 | |
846 case _running: | |
847 default: | |
848 ShouldNotReachHere(); | |
849 } | |
850 } | |
851 | |
852 void ThreadSafepointState::restart() { | |
853 switch(type()) { | |
854 case _at_safepoint: | |
855 case _call_back: | |
856 break; | |
857 | |
858 case _running: | |
859 default: | |
860 tty->print_cr("restart thread "INTPTR_FORMAT" with state %d", | |
861 _thread, _type); | |
862 _thread->print(); | |
863 ShouldNotReachHere(); | |
864 } | |
865 _type = _running; | |
866 set_has_called_back(false); | |
867 } | |
868 | |
869 | |
870 void ThreadSafepointState::print_on(outputStream *st) const { | |
871 const char *s; | |
872 | |
873 switch(_type) { | |
874 case _running : s = "_running"; break; | |
875 case _at_safepoint : s = "_at_safepoint"; break; | |
876 case _call_back : s = "_call_back"; break; | |
877 default: | |
878 ShouldNotReachHere(); | |
879 } | |
880 | |
881 st->print_cr("Thread: " INTPTR_FORMAT | |
882 " [0x%2x] State: %s _has_called_back %d _at_poll_safepoint %d", | |
883 _thread, _thread->osthread()->thread_id(), s, _has_called_back, | |
884 _at_poll_safepoint); | |
885 | |
886 _thread->print_thread_state_on(st); | |
887 } | |
888 | |
889 | |
890 // --------------------------------------------------------------------------------------------------------------------- | |
891 | |
892 // Block the thread at the safepoint poll or poll return. | |
893 void ThreadSafepointState::handle_polling_page_exception() { | |
894 | |
895 // Check state. block() will set thread state to thread_in_vm which will | |
896 // cause the safepoint state _type to become _call_back. | |
897 assert(type() == ThreadSafepointState::_running, | |
898 "polling page exception on thread not running state"); | |
899 | |
900 // Step 1: Find the nmethod from the return address | |
901 if (ShowSafepointMsgs && Verbose) { | |
902 tty->print_cr("Polling page exception at " INTPTR_FORMAT, thread()->saved_exception_pc()); | |
903 } | |
904 address real_return_addr = thread()->saved_exception_pc(); | |
905 | |
906 CodeBlob *cb = CodeCache::find_blob(real_return_addr); | |
907 assert(cb != NULL && cb->is_nmethod(), "return address should be in nmethod"); | |
908 nmethod* nm = (nmethod*)cb; | |
909 | |
910 // Find frame of caller | |
911 frame stub_fr = thread()->last_frame(); | |
912 CodeBlob* stub_cb = stub_fr.cb(); | |
913 assert(stub_cb->is_safepoint_stub(), "must be a safepoint stub"); | |
914 RegisterMap map(thread(), true); | |
915 frame caller_fr = stub_fr.sender(&map); | |
916 | |
917 // Should only be poll_return or poll | |
918 assert( nm->is_at_poll_or_poll_return(real_return_addr), "should not be at call" ); | |
919 | |
920 // This is a poll immediately before a return. The exception handling code | |
921 // has already had the effect of causing the return to occur, so the execution | |
922 // will continue immediately after the call. In addition, the oopmap at the | |
923 // return point does not mark the return value as an oop (if it is), so | |
924 // it needs a handle here to be updated. | |
925 if( nm->is_at_poll_return(real_return_addr) ) { | |
926 // See if return type is an oop. | |
927 bool return_oop = nm->method()->is_returning_oop(); | |
928 Handle return_value; | |
929 if (return_oop) { | |
930 // The oop result has been saved on the stack together with all | |
931 // the other registers. In order to preserve it over GCs we need | |
932 // to keep it in a handle. | |
933 oop result = caller_fr.saved_oop_result(&map); | |
934 assert(result == NULL || result->is_oop(), "must be oop"); | |
935 return_value = Handle(thread(), result); | |
936 assert(Universe::heap()->is_in_or_null(result), "must be heap pointer"); | |
937 } | |
938 | |
939 // Block the thread | |
940 SafepointSynchronize::block(thread()); | |
941 | |
942 // restore oop result, if any | |
943 if (return_oop) { | |
944 caller_fr.set_saved_oop_result(&map, return_value()); | |
945 } | |
946 } | |
947 | |
948 // This is a safepoint poll. Verify the return address and block. | |
949 else { | |
950 set_at_poll_safepoint(true); | |
951 | |
952 // verify the blob built the "return address" correctly | |
953 assert(real_return_addr == caller_fr.pc(), "must match"); | |
954 | |
955 // Block the thread | |
956 SafepointSynchronize::block(thread()); | |
957 set_at_poll_safepoint(false); | |
958 | |
959 // If we have a pending async exception deoptimize the frame | |
960 // as otherwise we may never deliver it. | |
961 if (thread()->has_async_condition()) { | |
962 ThreadInVMfromJavaNoAsyncException __tiv(thread()); | |
963 VM_DeoptimizeFrame deopt(thread(), caller_fr.id()); | |
964 VMThread::execute(&deopt); | |
965 } | |
966 | |
967 // If an exception has been installed we must check for a pending deoptimization | |
968 // Deoptimize frame if exception has been thrown. | |
969 | |
970 if (thread()->has_pending_exception() ) { | |
971 RegisterMap map(thread(), true); | |
972 frame caller_fr = stub_fr.sender(&map); | |
973 if (caller_fr.is_deoptimized_frame()) { | |
974 // The exception patch will destroy registers that are still | |
975 // live and will be needed during deoptimization. Defer the | |
976 // Async exception should have defered the exception until the | |
977 // next safepoint which will be detected when we get into | |
978 // the interpreter so if we have an exception now things | |
979 // are messed up. | |
980 | |
981 fatal("Exception installed and deoptimization is pending"); | |
982 } | |
983 } | |
984 } | |
985 } | |
986 | |
987 | |
988 // | |
989 // Statistics & Instrumentations | |
990 // | |
991 SafepointSynchronize::SafepointStats* SafepointSynchronize::_safepoint_stats = NULL; | |
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992 jlong SafepointSynchronize::_safepoint_begin_time = 0; |
0 | 993 int SafepointSynchronize::_cur_stat_index = 0; |
994 julong SafepointSynchronize::_safepoint_reasons[VM_Operation::VMOp_Terminating]; | |
995 julong SafepointSynchronize::_coalesced_vmop_count = 0; | |
996 jlong SafepointSynchronize::_max_sync_time = 0; | |
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997 jlong SafepointSynchronize::_max_vmop_time = 0; |
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998 float SafepointSynchronize::_ts_of_current_safepoint = 0.0f; |
0 | 999 |
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1000 static jlong cleanup_end_time = 0; |
0 | 1001 static bool need_to_track_page_armed_status = false; |
1002 static bool init_done = false; | |
1003 | |
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1004 // Helper method to print the header. |
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1005 static void print_header() { |
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1006 tty->print(" vmop " |
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1007 "[threads: total initially_running wait_to_block] "); |
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1008 tty->print("[time: spin block sync cleanup vmop] "); |
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1009 |
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1010 // no page armed status printed out if it is always armed. |
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1011 if (need_to_track_page_armed_status) { |
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1012 tty->print("page_armed "); |
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1013 } |
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1014 |
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1015 tty->print_cr("page_trap_count"); |
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1016 } |
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1017 |
0 | 1018 void SafepointSynchronize::deferred_initialize_stat() { |
1019 if (init_done) return; | |
1020 | |
1021 if (PrintSafepointStatisticsCount <= 0) { | |
1022 fatal("Wrong PrintSafepointStatisticsCount"); | |
1023 } | |
1024 | |
1025 // If PrintSafepointStatisticsTimeout is specified, the statistics data will | |
1026 // be printed right away, in which case, _safepoint_stats will regress to | |
1027 // a single element array. Otherwise, it is a circular ring buffer with default | |
1028 // size of PrintSafepointStatisticsCount. | |
1029 int stats_array_size; | |
1030 if (PrintSafepointStatisticsTimeout > 0) { | |
1031 stats_array_size = 1; | |
1032 PrintSafepointStatistics = true; | |
1033 } else { | |
1034 stats_array_size = PrintSafepointStatisticsCount; | |
1035 } | |
1036 _safepoint_stats = (SafepointStats*)os::malloc(stats_array_size | |
1037 * sizeof(SafepointStats)); | |
1038 guarantee(_safepoint_stats != NULL, | |
1039 "not enough memory for safepoint instrumentation data"); | |
1040 | |
1041 if (UseCompilerSafepoints && DeferPollingPageLoopCount >= 0) { | |
1042 need_to_track_page_armed_status = true; | |
1043 } | |
1044 init_done = true; | |
1045 } | |
1046 | |
1047 void SafepointSynchronize::begin_statistics(int nof_threads, int nof_running) { | |
1003 | 1048 assert(init_done, "safepoint statistics array hasn't been initialized"); |
0 | 1049 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; |
1050 | |
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1051 spstat->_time_stamp = _ts_of_current_safepoint; |
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1052 |
0 | 1053 VM_Operation *op = VMThread::vm_operation(); |
1054 spstat->_vmop_type = (op != NULL ? op->type() : -1); | |
1055 if (op != NULL) { | |
1056 _safepoint_reasons[spstat->_vmop_type]++; | |
1057 } | |
1058 | |
1059 spstat->_nof_total_threads = nof_threads; | |
1060 spstat->_nof_initial_running_threads = nof_running; | |
1061 spstat->_nof_threads_hit_page_trap = 0; | |
1062 | |
1063 // Records the start time of spinning. The real time spent on spinning | |
1064 // will be adjusted when spin is done. Same trick is applied for time | |
1065 // spent on waiting for threads to block. | |
1066 if (nof_running != 0) { | |
1067 spstat->_time_to_spin = os::javaTimeNanos(); | |
1068 } else { | |
1069 spstat->_time_to_spin = 0; | |
1070 } | |
1071 } | |
1072 | |
1073 void SafepointSynchronize::update_statistics_on_spin_end() { | |
1074 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; | |
1075 | |
1076 jlong cur_time = os::javaTimeNanos(); | |
1077 | |
1078 spstat->_nof_threads_wait_to_block = _waiting_to_block; | |
1079 if (spstat->_nof_initial_running_threads != 0) { | |
1080 spstat->_time_to_spin = cur_time - spstat->_time_to_spin; | |
1081 } | |
1082 | |
1083 if (need_to_track_page_armed_status) { | |
1084 spstat->_page_armed = (PageArmed == 1); | |
1085 } | |
1086 | |
1087 // Records the start time of waiting for to block. Updated when block is done. | |
1088 if (_waiting_to_block != 0) { | |
1089 spstat->_time_to_wait_to_block = cur_time; | |
1090 } else { | |
1091 spstat->_time_to_wait_to_block = 0; | |
1092 } | |
1093 } | |
1094 | |
1095 void SafepointSynchronize::update_statistics_on_sync_end(jlong end_time) { | |
1096 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; | |
1097 | |
1098 if (spstat->_nof_threads_wait_to_block != 0) { | |
1099 spstat->_time_to_wait_to_block = end_time - | |
1100 spstat->_time_to_wait_to_block; | |
1101 } | |
1102 | |
1103 // Records the end time of sync which will be used to calculate the total | |
1104 // vm operation time. Again, the real time spending in syncing will be deducted | |
1105 // from the start of the sync time later when end_statistics is called. | |
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1106 spstat->_time_to_sync = end_time - _safepoint_begin_time; |
0 | 1107 if (spstat->_time_to_sync > _max_sync_time) { |
1108 _max_sync_time = spstat->_time_to_sync; | |
1109 } | |
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1110 |
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1111 spstat->_time_to_do_cleanups = end_time; |
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1112 } |
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1113 |
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1114 void SafepointSynchronize::update_statistics_on_cleanup_end(jlong end_time) { |
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1115 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; |
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1116 |
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1117 // Record how long spent in cleanup tasks. |
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1118 spstat->_time_to_do_cleanups = end_time - spstat->_time_to_do_cleanups; |
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1119 |
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1120 cleanup_end_time = end_time; |
0 | 1121 } |
1122 | |
1123 void SafepointSynchronize::end_statistics(jlong vmop_end_time) { | |
1124 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; | |
1125 | |
1126 // Update the vm operation time. | |
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1127 spstat->_time_to_exec_vmop = vmop_end_time - cleanup_end_time; |
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1128 if (spstat->_time_to_exec_vmop > _max_vmop_time) { |
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1129 _max_vmop_time = spstat->_time_to_exec_vmop; |
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1130 } |
0 | 1131 // Only the sync time longer than the specified |
1132 // PrintSafepointStatisticsTimeout will be printed out right away. | |
1133 // By default, it is -1 meaning all samples will be put into the list. | |
1134 if ( PrintSafepointStatisticsTimeout > 0) { | |
1135 if (spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) { | |
1136 print_statistics(); | |
1137 } | |
1138 } else { | |
1139 // The safepoint statistics will be printed out when the _safepoin_stats | |
1140 // array fills up. | |
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1141 if (_cur_stat_index == PrintSafepointStatisticsCount - 1) { |
0 | 1142 print_statistics(); |
1143 _cur_stat_index = 0; | |
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1144 } else { |
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1145 _cur_stat_index++; |
0 | 1146 } |
1147 } | |
1148 } | |
1149 | |
1150 void SafepointSynchronize::print_statistics() { | |
1151 SafepointStats* sstats = _safepoint_stats; | |
1152 | |
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1153 for (int index = 0; index <= _cur_stat_index; index++) { |
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1154 if (index % 30 == 0) { |
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1155 print_header(); |
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1156 } |
0 | 1157 sstats = &_safepoint_stats[index]; |
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1158 tty->print("%.3f: ", sstats->_time_stamp); |
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1159 tty->print("%-26s [" |
0 | 1160 INT32_FORMAT_W(8)INT32_FORMAT_W(11)INT32_FORMAT_W(15) |
1291
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1161 " ] ", |
0 | 1162 sstats->_vmop_type == -1 ? "no vm operation" : |
1163 VM_Operation::name(sstats->_vmop_type), | |
1164 sstats->_nof_total_threads, | |
1165 sstats->_nof_initial_running_threads, | |
1166 sstats->_nof_threads_wait_to_block); | |
1167 // "/ MICROUNITS " is to convert the unit from nanos to millis. | |
1291
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1168 tty->print(" [" |
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1169 INT64_FORMAT_W(6)INT64_FORMAT_W(6) |
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1170 INT64_FORMAT_W(6)INT64_FORMAT_W(6) |
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1171 INT64_FORMAT_W(6)" ] ", |
0 | 1172 sstats->_time_to_spin / MICROUNITS, |
1173 sstats->_time_to_wait_to_block / MICROUNITS, | |
1174 sstats->_time_to_sync / MICROUNITS, | |
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1175 sstats->_time_to_do_cleanups / MICROUNITS, |
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1176 sstats->_time_to_exec_vmop / MICROUNITS); |
0 | 1177 |
1178 if (need_to_track_page_armed_status) { | |
1179 tty->print(INT32_FORMAT" ", sstats->_page_armed); | |
1180 } | |
1181 tty->print_cr(INT32_FORMAT" ", sstats->_nof_threads_hit_page_trap); | |
1182 } | |
1183 } | |
1184 | |
1185 // This method will be called when VM exits. It will first call | |
1186 // print_statistics to print out the rest of the sampling. Then | |
1187 // it tries to summarize the sampling. | |
1188 void SafepointSynchronize::print_stat_on_exit() { | |
1189 if (_safepoint_stats == NULL) return; | |
1190 | |
1191 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; | |
1192 | |
1193 // During VM exit, end_statistics may not get called and in that | |
1194 // case, if the sync time is less than PrintSafepointStatisticsTimeout, | |
1195 // don't print it out. | |
1196 // Approximate the vm op time. | |
1197 _safepoint_stats[_cur_stat_index]._time_to_exec_vmop = | |
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1198 os::javaTimeNanos() - cleanup_end_time; |
0 | 1199 |
1200 if ( PrintSafepointStatisticsTimeout < 0 || | |
1201 spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) { | |
1202 print_statistics(); | |
1203 } | |
1204 tty->print_cr(""); | |
1205 | |
1206 // Print out polling page sampling status. | |
1207 if (!need_to_track_page_armed_status) { | |
1208 if (UseCompilerSafepoints) { | |
1209 tty->print_cr("Polling page always armed"); | |
1210 } | |
1211 } else { | |
1212 tty->print_cr("Defer polling page loop count = %d\n", | |
1213 DeferPollingPageLoopCount); | |
1214 } | |
1215 | |
1216 for (int index = 0; index < VM_Operation::VMOp_Terminating; index++) { | |
1217 if (_safepoint_reasons[index] != 0) { | |
1218 tty->print_cr("%-26s"UINT64_FORMAT_W(10), VM_Operation::name(index), | |
1219 _safepoint_reasons[index]); | |
1220 } | |
1221 } | |
1222 | |
1223 tty->print_cr(UINT64_FORMAT_W(5)" VM operations coalesced during safepoint", | |
1224 _coalesced_vmop_count); | |
1225 tty->print_cr("Maximum sync time "INT64_FORMAT_W(5)" ms", | |
1226 _max_sync_time / MICROUNITS); | |
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1227 tty->print_cr("Maximum vm operation time (except for Exit VM operation) " |
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1228 INT64_FORMAT_W(5)" ms", |
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1229 _max_vmop_time / MICROUNITS); |
0 | 1230 } |
1231 | |
1232 // ------------------------------------------------------------------------------------------------ | |
1233 // Non-product code | |
1234 | |
1235 #ifndef PRODUCT | |
1236 | |
1237 void SafepointSynchronize::print_state() { | |
1238 if (_state == _not_synchronized) { | |
1239 tty->print_cr("not synchronized"); | |
1240 } else if (_state == _synchronizing || _state == _synchronized) { | |
1241 tty->print_cr("State: %s", (_state == _synchronizing) ? "synchronizing" : | |
1242 "synchronized"); | |
1243 | |
1244 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) { | |
1245 cur->safepoint_state()->print(); | |
1246 } | |
1247 } | |
1248 } | |
1249 | |
1250 void SafepointSynchronize::safepoint_msg(const char* format, ...) { | |
1251 if (ShowSafepointMsgs) { | |
1252 va_list ap; | |
1253 va_start(ap, format); | |
1254 tty->vprint_cr(format, ap); | |
1255 va_end(ap); | |
1256 } | |
1257 } | |
1258 | |
1259 #endif // !PRODUCT |