Mercurial > hg > graal-compiler
annotate src/share/vm/runtime/safepoint.cpp @ 2162:ccfcb502af3f
6566340: Restore use of stillborn flag to signify a thread that was stopped before it started
Summary: Restore use of stillborn flag
Reviewed-by: acorn, alanb
author | dholmes |
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date | Tue, 25 Jan 2011 00:14:21 -0500 |
parents | f95d63e2154a |
children | 3582bf76420e |
rev | line source |
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0 | 1 /* |
1972 | 2 * Copyright (c) 1997, 2010, Oracle and/or its affiliates. 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 * | |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
0 | 22 * |
23 */ | |
24 | |
1972 | 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/symbolOop.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_OS_FAMILY_linux | |
65 # include "thread_linux.inline.hpp" | |
66 #endif | |
67 #ifdef TARGET_OS_FAMILY_solaris | |
68 # include "thread_solaris.inline.hpp" | |
69 #endif | |
70 #ifdef TARGET_OS_FAMILY_windows | |
71 # include "thread_windows.inline.hpp" | |
72 #endif | |
73 #ifndef SERIALGC | |
74 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp" | |
75 #include "gc_implementation/shared/concurrentGCThread.hpp" | |
76 #endif | |
77 #ifdef COMPILER1 | |
78 #include "c1/c1_globals.hpp" | |
79 #endif | |
0 | 80 |
81 // -------------------------------------------------------------------------------------------------- | |
82 // Implementation of Safepoint begin/end | |
83 | |
84 SafepointSynchronize::SynchronizeState volatile SafepointSynchronize::_state = SafepointSynchronize::_not_synchronized; | |
85 volatile int SafepointSynchronize::_waiting_to_block = 0; | |
86 volatile int SafepointSynchronize::_safepoint_counter = 0; | |
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87 long SafepointSynchronize::_end_of_last_safepoint = 0; |
0 | 88 static volatile int PageArmed = 0 ; // safepoint polling page is RO|RW vs PROT_NONE |
89 static volatile int TryingToBlock = 0 ; // proximate value -- for advisory use only | |
90 static bool timeout_error_printed = false; | |
91 | |
92 // Roll all threads forward to a safepoint and suspend them all | |
93 void SafepointSynchronize::begin() { | |
94 | |
95 Thread* myThread = Thread::current(); | |
96 assert(myThread->is_VM_thread(), "Only VM thread may execute a safepoint"); | |
97 | |
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98 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) { |
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99 _safepoint_begin_time = os::javaTimeNanos(); |
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100 _ts_of_current_safepoint = tty->time_stamp().seconds(); |
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101 } |
0 | 102 |
103 #ifndef SERIALGC | |
104 if (UseConcMarkSweepGC) { | |
105 // In the future we should investigate whether CMS can use the | |
106 // more-general mechanism below. DLD (01/05). | |
107 ConcurrentMarkSweepThread::synchronize(false); | |
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108 } else if (UseG1GC) { |
0 | 109 ConcurrentGCThread::safepoint_synchronize(); |
110 } | |
111 #endif // SERIALGC | |
112 | |
113 // By getting the Threads_lock, we assure that no threads are about to start or | |
114 // exit. It is released again in SafepointSynchronize::end(). | |
115 Threads_lock->lock(); | |
116 | |
117 assert( _state == _not_synchronized, "trying to safepoint synchronize with wrong state"); | |
118 | |
119 int nof_threads = Threads::number_of_threads(); | |
120 | |
121 if (TraceSafepoint) { | |
122 tty->print_cr("Safepoint synchronization initiated. (%d)", nof_threads); | |
123 } | |
124 | |
125 RuntimeService::record_safepoint_begin(); | |
126 | |
127 { | |
128 MutexLocker mu(Safepoint_lock); | |
129 | |
130 // Set number of threads to wait for, before we initiate the callbacks | |
131 _waiting_to_block = nof_threads; | |
132 TryingToBlock = 0 ; | |
133 int still_running = nof_threads; | |
134 | |
135 // Save the starting time, so that it can be compared to see if this has taken | |
136 // too long to complete. | |
137 jlong safepoint_limit_time; | |
138 timeout_error_printed = false; | |
139 | |
1003 | 140 // PrintSafepointStatisticsTimeout can be specified separately. When |
141 // specified, PrintSafepointStatistics will be set to true in | |
142 // deferred_initialize_stat method. The initialization has to be done | |
143 // early enough to avoid any races. See bug 6880029 for details. | |
144 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) { | |
145 deferred_initialize_stat(); | |
146 } | |
147 | |
0 | 148 // Begin the process of bringing the system to a safepoint. |
149 // Java threads can be in several different states and are | |
150 // stopped by different mechanisms: | |
151 // | |
152 // 1. Running interpreted | |
153 // The interpeter dispatch table is changed to force it to | |
154 // check for a safepoint condition between bytecodes. | |
155 // 2. Running in native code | |
156 // When returning from the native code, a Java thread must check | |
157 // the safepoint _state to see if we must block. If the | |
158 // VM thread sees a Java thread in native, it does | |
159 // not wait for this thread to block. The order of the memory | |
160 // writes and reads of both the safepoint state and the Java | |
161 // threads state is critical. In order to guarantee that the | |
162 // memory writes are serialized with respect to each other, | |
163 // the VM thread issues a memory barrier instruction | |
164 // (on MP systems). In order to avoid the overhead of issuing | |
165 // a memory barrier for each Java thread making native calls, each Java | |
166 // thread performs a write to a single memory page after changing | |
167 // the thread state. The VM thread performs a sequence of | |
168 // mprotect OS calls which forces all previous writes from all | |
169 // Java threads to be serialized. This is done in the | |
170 // os::serialize_thread_states() call. This has proven to be | |
171 // much more efficient than executing a membar instruction | |
172 // on every call to native code. | |
173 // 3. Running compiled Code | |
174 // Compiled code reads a global (Safepoint Polling) page that | |
175 // is set to fault if we are trying to get to a safepoint. | |
176 // 4. Blocked | |
177 // A thread which is blocked will not be allowed to return from the | |
178 // block condition until the safepoint operation is complete. | |
179 // 5. In VM or Transitioning between states | |
180 // If a Java thread is currently running in the VM or transitioning | |
181 // between states, the safepointing code will wait for the thread to | |
182 // block itself when it attempts transitions to a new state. | |
183 // | |
184 _state = _synchronizing; | |
185 OrderAccess::fence(); | |
186 | |
187 // Flush all thread states to memory | |
188 if (!UseMembar) { | |
189 os::serialize_thread_states(); | |
190 } | |
191 | |
192 // Make interpreter safepoint aware | |
193 Interpreter::notice_safepoints(); | |
194 | |
195 if (UseCompilerSafepoints && DeferPollingPageLoopCount < 0) { | |
196 // Make polling safepoint aware | |
197 guarantee (PageArmed == 0, "invariant") ; | |
198 PageArmed = 1 ; | |
199 os::make_polling_page_unreadable(); | |
200 } | |
201 | |
202 // Consider using active_processor_count() ... but that call is expensive. | |
203 int ncpus = os::processor_count() ; | |
204 | |
205 #ifdef ASSERT | |
206 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) { | |
207 assert(cur->safepoint_state()->is_running(), "Illegal initial state"); | |
208 } | |
209 #endif // ASSERT | |
210 | |
211 if (SafepointTimeout) | |
212 safepoint_limit_time = os::javaTimeNanos() + (jlong)SafepointTimeoutDelay * MICROUNITS; | |
213 | |
214 // Iterate through all threads until it have been determined how to stop them all at a safepoint | |
215 unsigned int iterations = 0; | |
216 int steps = 0 ; | |
217 while(still_running > 0) { | |
218 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) { | |
219 assert(!cur->is_ConcurrentGC_thread(), "A concurrent GC thread is unexpectly being suspended"); | |
220 ThreadSafepointState *cur_state = cur->safepoint_state(); | |
221 if (cur_state->is_running()) { | |
222 cur_state->examine_state_of_thread(); | |
223 if (!cur_state->is_running()) { | |
224 still_running--; | |
225 // consider adjusting steps downward: | |
226 // steps = 0 | |
227 // steps -= NNN | |
228 // steps >>= 1 | |
229 // steps = MIN(steps, 2000-100) | |
230 // if (iterations != 0) steps -= NNN | |
231 } | |
232 if (TraceSafepoint && Verbose) cur_state->print(); | |
233 } | |
234 } | |
235 | |
1003 | 236 if (PrintSafepointStatistics && iterations == 0) { |
0 | 237 begin_statistics(nof_threads, still_running); |
238 } | |
239 | |
240 if (still_running > 0) { | |
241 // Check for if it takes to long | |
242 if (SafepointTimeout && safepoint_limit_time < os::javaTimeNanos()) { | |
243 print_safepoint_timeout(_spinning_timeout); | |
244 } | |
245 | |
246 // Spin to avoid context switching. | |
247 // There's a tension between allowing the mutators to run (and rendezvous) | |
248 // vs spinning. As the VM thread spins, wasting cycles, it consumes CPU that | |
249 // a mutator might otherwise use profitably to reach a safepoint. Excessive | |
250 // spinning by the VM thread on a saturated system can increase rendezvous latency. | |
251 // Blocking or yielding incur their own penalties in the form of context switching | |
252 // and the resultant loss of $ residency. | |
253 // | |
254 // Further complicating matters is that yield() does not work as naively expected | |
255 // on many platforms -- yield() does not guarantee that any other ready threads | |
256 // will run. As such we revert yield_all() after some number of iterations. | |
257 // Yield_all() is implemented as a short unconditional sleep on some platforms. | |
258 // Typical operating systems round a "short" sleep period up to 10 msecs, so sleeping | |
259 // can actually increase the time it takes the VM thread to detect that a system-wide | |
260 // stop-the-world safepoint has been reached. In a pathological scenario such as that | |
261 // described in CR6415670 the VMthread may sleep just before the mutator(s) become safe. | |
262 // In that case the mutators will be stalled waiting for the safepoint to complete and the | |
263 // the VMthread will be sleeping, waiting for the mutators to rendezvous. The VMthread | |
264 // will eventually wake up and detect that all mutators are safe, at which point | |
265 // we'll again make progress. | |
266 // | |
267 // Beware too that that the VMThread typically runs at elevated priority. | |
268 // Its default priority is higher than the default mutator priority. | |
269 // Obviously, this complicates spinning. | |
270 // | |
271 // Note too that on Windows XP SwitchThreadTo() has quite different behavior than Sleep(0). | |
272 // Sleep(0) will _not yield to lower priority threads, while SwitchThreadTo() will. | |
273 // | |
274 // See the comments in synchronizer.cpp for additional remarks on spinning. | |
275 // | |
276 // In the future we might: | |
277 // 1. Modify the safepoint scheme to avoid potentally unbounded spinning. | |
278 // This is tricky as the path used by a thread exiting the JVM (say on | |
279 // on JNI call-out) simply stores into its state field. The burden | |
280 // is placed on the VM thread, which must poll (spin). | |
281 // 2. Find something useful to do while spinning. If the safepoint is GC-related | |
282 // we might aggressively scan the stacks of threads that are already safe. | |
283 // 3. Use Solaris schedctl to examine the state of the still-running mutators. | |
284 // If all the mutators are ONPROC there's no reason to sleep or yield. | |
285 // 4. YieldTo() any still-running mutators that are ready but OFFPROC. | |
286 // 5. Check system saturation. If the system is not fully saturated then | |
287 // simply spin and avoid sleep/yield. | |
288 // 6. As still-running mutators rendezvous they could unpark the sleeping | |
289 // VMthread. This works well for still-running mutators that become | |
290 // safe. The VMthread must still poll for mutators that call-out. | |
291 // 7. Drive the policy on time-since-begin instead of iterations. | |
292 // 8. Consider making the spin duration a function of the # of CPUs: | |
293 // Spin = (((ncpus-1) * M) + K) + F(still_running) | |
294 // Alternately, instead of counting iterations of the outer loop | |
295 // we could count the # of threads visited in the inner loop, above. | |
296 // 9. On windows consider using the return value from SwitchThreadTo() | |
297 // to drive subsequent spin/SwitchThreadTo()/Sleep(N) decisions. | |
298 | |
299 if (UseCompilerSafepoints && int(iterations) == DeferPollingPageLoopCount) { | |
300 guarantee (PageArmed == 0, "invariant") ; | |
301 PageArmed = 1 ; | |
302 os::make_polling_page_unreadable(); | |
303 } | |
304 | |
305 // Instead of (ncpus > 1) consider either (still_running < (ncpus + EPSILON)) or | |
306 // ((still_running + _waiting_to_block - TryingToBlock)) < ncpus) | |
307 ++steps ; | |
308 if (ncpus > 1 && steps < SafepointSpinBeforeYield) { | |
309 SpinPause() ; // MP-Polite spin | |
310 } else | |
311 if (steps < DeferThrSuspendLoopCount) { | |
312 os::NakedYield() ; | |
313 } else { | |
314 os::yield_all(steps) ; | |
315 // Alternately, the VM thread could transiently depress its scheduling priority or | |
316 // transiently increase the priority of the tardy mutator(s). | |
317 } | |
318 | |
319 iterations ++ ; | |
320 } | |
321 assert(iterations < (uint)max_jint, "We have been iterating in the safepoint loop too long"); | |
322 } | |
323 assert(still_running == 0, "sanity check"); | |
324 | |
325 if (PrintSafepointStatistics) { | |
326 update_statistics_on_spin_end(); | |
327 } | |
328 | |
329 // wait until all threads are stopped | |
330 while (_waiting_to_block > 0) { | |
331 if (TraceSafepoint) tty->print_cr("Waiting for %d thread(s) to block", _waiting_to_block); | |
332 if (!SafepointTimeout || timeout_error_printed) { | |
333 Safepoint_lock->wait(true); // true, means with no safepoint checks | |
334 } else { | |
335 // Compute remaining time | |
336 jlong remaining_time = safepoint_limit_time - os::javaTimeNanos(); | |
337 | |
338 // If there is no remaining time, then there is an error | |
339 if (remaining_time < 0 || Safepoint_lock->wait(true, remaining_time / MICROUNITS)) { | |
340 print_safepoint_timeout(_blocking_timeout); | |
341 } | |
342 } | |
343 } | |
344 assert(_waiting_to_block == 0, "sanity check"); | |
345 | |
346 #ifndef PRODUCT | |
347 if (SafepointTimeout) { | |
348 jlong current_time = os::javaTimeNanos(); | |
349 if (safepoint_limit_time < current_time) { | |
350 tty->print_cr("# SafepointSynchronize: Finished after " | |
351 INT64_FORMAT_W(6) " ms", | |
352 ((current_time - safepoint_limit_time) / MICROUNITS + | |
353 SafepointTimeoutDelay)); | |
354 } | |
355 } | |
356 #endif | |
357 | |
358 assert((_safepoint_counter & 0x1) == 0, "must be even"); | |
359 assert(Threads_lock->owned_by_self(), "must hold Threads_lock"); | |
360 _safepoint_counter ++; | |
361 | |
362 // Record state | |
363 _state = _synchronized; | |
364 | |
365 OrderAccess::fence(); | |
366 | |
367 if (TraceSafepoint) { | |
368 VM_Operation *op = VMThread::vm_operation(); | |
369 tty->print_cr("Entering safepoint region: %s", (op != NULL) ? op->name() : "no vm operation"); | |
370 } | |
371 | |
372 RuntimeService::record_safepoint_synchronized(); | |
373 if (PrintSafepointStatistics) { | |
374 update_statistics_on_sync_end(os::javaTimeNanos()); | |
375 } | |
376 | |
377 // Call stuff that needs to be run when a safepoint is just about to be completed | |
378 do_cleanup_tasks(); | |
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379 |
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380 if (PrintSafepointStatistics) { |
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381 // Record how much time spend on the above cleanup tasks |
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382 update_statistics_on_cleanup_end(os::javaTimeNanos()); |
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383 } |
0 | 384 } |
385 } | |
386 | |
387 // Wake up all threads, so they are ready to resume execution after the safepoint | |
388 // operation has been carried out | |
389 void SafepointSynchronize::end() { | |
390 | |
391 assert(Threads_lock->owned_by_self(), "must hold Threads_lock"); | |
392 assert((_safepoint_counter & 0x1) == 1, "must be odd"); | |
393 _safepoint_counter ++; | |
394 // memory fence isn't required here since an odd _safepoint_counter | |
395 // value can do no harm and a fence is issued below anyway. | |
396 | |
397 DEBUG_ONLY(Thread* myThread = Thread::current();) | |
398 assert(myThread->is_VM_thread(), "Only VM thread can execute a safepoint"); | |
399 | |
400 if (PrintSafepointStatistics) { | |
401 end_statistics(os::javaTimeNanos()); | |
402 } | |
403 | |
404 #ifdef ASSERT | |
405 // A pending_exception cannot be installed during a safepoint. The threads | |
406 // may install an async exception after they come back from a safepoint into | |
407 // pending_exception after they unblock. But that should happen later. | |
408 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) { | |
409 assert (!(cur->has_pending_exception() && | |
410 cur->safepoint_state()->is_at_poll_safepoint()), | |
411 "safepoint installed a pending exception"); | |
412 } | |
413 #endif // ASSERT | |
414 | |
415 if (PageArmed) { | |
416 // Make polling safepoint aware | |
417 os::make_polling_page_readable(); | |
418 PageArmed = 0 ; | |
419 } | |
420 | |
421 // Remove safepoint check from interpreter | |
422 Interpreter::ignore_safepoints(); | |
423 | |
424 { | |
425 MutexLocker mu(Safepoint_lock); | |
426 | |
427 assert(_state == _synchronized, "must be synchronized before ending safepoint synchronization"); | |
428 | |
429 // Set to not synchronized, so the threads will not go into the signal_thread_blocked method | |
430 // when they get restarted. | |
431 _state = _not_synchronized; | |
432 OrderAccess::fence(); | |
433 | |
434 if (TraceSafepoint) { | |
435 tty->print_cr("Leaving safepoint region"); | |
436 } | |
437 | |
438 // Start suspended threads | |
439 for(JavaThread *current = Threads::first(); current; current = current->next()) { | |
605 | 440 // A problem occurring on Solaris is when attempting to restart threads |
0 | 441 // the first #cpus - 1 go well, but then the VMThread is preempted when we get |
442 // to the next one (since it has been running the longest). We then have | |
443 // to wait for a cpu to become available before we can continue restarting | |
444 // threads. | |
445 // FIXME: This causes the performance of the VM to degrade when active and with | |
446 // large numbers of threads. Apparently this is due to the synchronous nature | |
447 // of suspending threads. | |
448 // | |
449 // TODO-FIXME: the comments above are vestigial and no longer apply. | |
450 // Furthermore, using solaris' schedctl in this particular context confers no benefit | |
451 if (VMThreadHintNoPreempt) { | |
452 os::hint_no_preempt(); | |
453 } | |
454 ThreadSafepointState* cur_state = current->safepoint_state(); | |
455 assert(cur_state->type() != ThreadSafepointState::_running, "Thread not suspended at safepoint"); | |
456 cur_state->restart(); | |
457 assert(cur_state->is_running(), "safepoint state has not been reset"); | |
458 } | |
459 | |
460 RuntimeService::record_safepoint_end(); | |
461 | |
462 // Release threads lock, so threads can be created/destroyed again. It will also starts all threads | |
463 // blocked in signal_thread_blocked | |
464 Threads_lock->unlock(); | |
465 | |
466 } | |
467 #ifndef SERIALGC | |
468 // If there are any concurrent GC threads resume them. | |
469 if (UseConcMarkSweepGC) { | |
470 ConcurrentMarkSweepThread::desynchronize(false); | |
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471 } else if (UseG1GC) { |
0 | 472 ConcurrentGCThread::safepoint_desynchronize(); |
473 } | |
474 #endif // SERIALGC | |
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475 // record this time so VMThread can keep track how much time has elasped |
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476 // since last safepoint. |
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477 _end_of_last_safepoint = os::javaTimeMillis(); |
0 | 478 } |
479 | |
480 bool SafepointSynchronize::is_cleanup_needed() { | |
481 // Need a safepoint if some inline cache buffers is non-empty | |
482 if (!InlineCacheBuffer::is_empty()) return true; | |
483 return false; | |
484 } | |
485 | |
486 | |
487 | |
488 // Various cleaning tasks that should be done periodically at safepoints | |
489 void SafepointSynchronize::do_cleanup_tasks() { | |
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490 { |
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491 TraceTime t1("deflating idle monitors", TraceSafepointCleanupTime); |
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492 ObjectSynchronizer::deflate_idle_monitors(); |
0 | 493 } |
494 | |
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495 { |
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496 TraceTime t2("updating inline caches", TraceSafepointCleanupTime); |
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497 InlineCacheBuffer::update_inline_caches(); |
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498 } |
1783 | 499 { |
500 TraceTime t3("compilation policy safepoint handler", TraceSafepointCleanupTime); | |
501 CompilationPolicy::policy()->do_safepoint_work(); | |
0 | 502 } |
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503 |
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504 TraceTime t4("sweeping nmethods", TraceSafepointCleanupTime); |
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505 NMethodSweeper::scan_stacks(); |
0 | 506 } |
507 | |
508 | |
509 bool SafepointSynchronize::safepoint_safe(JavaThread *thread, JavaThreadState state) { | |
510 switch(state) { | |
511 case _thread_in_native: | |
512 // native threads are safe if they have no java stack or have walkable stack | |
513 return !thread->has_last_Java_frame() || thread->frame_anchor()->walkable(); | |
514 | |
515 // blocked threads should have already have walkable stack | |
516 case _thread_blocked: | |
517 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "blocked and not walkable"); | |
518 return true; | |
519 | |
520 default: | |
521 return false; | |
522 } | |
523 } | |
524 | |
525 | |
526 // ------------------------------------------------------------------------------------------------------- | |
527 // Implementation of Safepoint callback point | |
528 | |
529 void SafepointSynchronize::block(JavaThread *thread) { | |
530 assert(thread != NULL, "thread must be set"); | |
531 assert(thread->is_Java_thread(), "not a Java thread"); | |
532 | |
533 // Threads shouldn't block if they are in the middle of printing, but... | |
534 ttyLocker::break_tty_lock_for_safepoint(os::current_thread_id()); | |
535 | |
536 // Only bail from the block() call if the thread is gone from the | |
537 // thread list; starting to exit should still block. | |
538 if (thread->is_terminated()) { | |
539 // block current thread if we come here from native code when VM is gone | |
540 thread->block_if_vm_exited(); | |
541 | |
542 // otherwise do nothing | |
543 return; | |
544 } | |
545 | |
546 JavaThreadState state = thread->thread_state(); | |
547 thread->frame_anchor()->make_walkable(thread); | |
548 | |
549 // Check that we have a valid thread_state at this point | |
550 switch(state) { | |
551 case _thread_in_vm_trans: | |
552 case _thread_in_Java: // From compiled code | |
553 | |
554 // We are highly likely to block on the Safepoint_lock. In order to avoid blocking in this case, | |
555 // we pretend we are still in the VM. | |
556 thread->set_thread_state(_thread_in_vm); | |
557 | |
558 if (is_synchronizing()) { | |
559 Atomic::inc (&TryingToBlock) ; | |
560 } | |
561 | |
562 // We will always be holding the Safepoint_lock when we are examine the state | |
563 // of a thread. Hence, the instructions between the Safepoint_lock->lock() and | |
564 // Safepoint_lock->unlock() are happening atomic with regards to the safepoint code | |
565 Safepoint_lock->lock_without_safepoint_check(); | |
566 if (is_synchronizing()) { | |
567 // Decrement the number of threads to wait for and signal vm thread | |
568 assert(_waiting_to_block > 0, "sanity check"); | |
569 _waiting_to_block--; | |
570 thread->safepoint_state()->set_has_called_back(true); | |
571 | |
572 // Consider (_waiting_to_block < 2) to pipeline the wakeup of the VM thread | |
573 if (_waiting_to_block == 0) { | |
574 Safepoint_lock->notify_all(); | |
575 } | |
576 } | |
577 | |
578 // We transition the thread to state _thread_blocked here, but | |
579 // we can't do our usual check for external suspension and then | |
580 // self-suspend after the lock_without_safepoint_check() call | |
581 // below because we are often called during transitions while | |
582 // we hold different locks. That would leave us suspended while | |
583 // holding a resource which results in deadlocks. | |
584 thread->set_thread_state(_thread_blocked); | |
585 Safepoint_lock->unlock(); | |
586 | |
587 // We now try to acquire the threads lock. Since this lock is hold by the VM thread during | |
588 // the entire safepoint, the threads will all line up here during the safepoint. | |
589 Threads_lock->lock_without_safepoint_check(); | |
590 // restore original state. This is important if the thread comes from compiled code, so it | |
591 // will continue to execute with the _thread_in_Java state. | |
592 thread->set_thread_state(state); | |
593 Threads_lock->unlock(); | |
594 break; | |
595 | |
596 case _thread_in_native_trans: | |
597 case _thread_blocked_trans: | |
598 case _thread_new_trans: | |
599 if (thread->safepoint_state()->type() == ThreadSafepointState::_call_back) { | |
600 thread->print_thread_state(); | |
601 fatal("Deadlock in safepoint code. " | |
602 "Should have called back to the VM before blocking."); | |
603 } | |
604 | |
605 // We transition the thread to state _thread_blocked here, but | |
606 // we can't do our usual check for external suspension and then | |
607 // self-suspend after the lock_without_safepoint_check() call | |
608 // below because we are often called during transitions while | |
609 // we hold different locks. That would leave us suspended while | |
610 // holding a resource which results in deadlocks. | |
611 thread->set_thread_state(_thread_blocked); | |
612 | |
613 // It is not safe to suspend a thread if we discover it is in _thread_in_native_trans. Hence, | |
614 // the safepoint code might still be waiting for it to block. We need to change the state here, | |
615 // so it can see that it is at a safepoint. | |
616 | |
617 // Block until the safepoint operation is completed. | |
618 Threads_lock->lock_without_safepoint_check(); | |
619 | |
620 // Restore state | |
621 thread->set_thread_state(state); | |
622 | |
623 Threads_lock->unlock(); | |
624 break; | |
625 | |
626 default: | |
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627 fatal(err_msg("Illegal threadstate encountered: %d", state)); |
0 | 628 } |
629 | |
630 // Check for pending. async. exceptions or suspends - except if the | |
631 // thread was blocked inside the VM. has_special_runtime_exit_condition() | |
632 // is called last since it grabs a lock and we only want to do that when | |
633 // we must. | |
634 // | |
635 // Note: we never deliver an async exception at a polling point as the | |
636 // compiler may not have an exception handler for it. The polling | |
637 // code will notice the async and deoptimize and the exception will | |
638 // be delivered. (Polling at a return point is ok though). Sure is | |
639 // a lot of bother for a deprecated feature... | |
640 // | |
641 // We don't deliver an async exception if the thread state is | |
642 // _thread_in_native_trans so JNI functions won't be called with | |
643 // a surprising pending exception. If the thread state is going back to java, | |
644 // async exception is checked in check_special_condition_for_native_trans(). | |
645 | |
646 if (state != _thread_blocked_trans && | |
647 state != _thread_in_vm_trans && | |
648 thread->has_special_runtime_exit_condition()) { | |
649 thread->handle_special_runtime_exit_condition( | |
650 !thread->is_at_poll_safepoint() && (state != _thread_in_native_trans)); | |
651 } | |
652 } | |
653 | |
654 // ------------------------------------------------------------------------------------------------------ | |
655 // Exception handlers | |
656 | |
657 #ifndef PRODUCT | |
658 #ifdef _LP64 | |
659 #define PTR_PAD "" | |
660 #else | |
661 #define PTR_PAD " " | |
662 #endif | |
663 | |
664 static void print_ptrs(intptr_t oldptr, intptr_t newptr, bool wasoop) { | |
665 bool is_oop = newptr ? ((oop)newptr)->is_oop() : false; | |
666 tty->print_cr(PTR_FORMAT PTR_PAD " %s %c " PTR_FORMAT PTR_PAD " %s %s", | |
667 oldptr, wasoop?"oop":" ", oldptr == newptr ? ' ' : '!', | |
668 newptr, is_oop?"oop":" ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":" ")); | |
669 } | |
670 | |
671 static void print_longs(jlong oldptr, jlong newptr, bool wasoop) { | |
672 bool is_oop = newptr ? ((oop)(intptr_t)newptr)->is_oop() : false; | |
673 tty->print_cr(PTR64_FORMAT " %s %c " PTR64_FORMAT " %s %s", | |
674 oldptr, wasoop?"oop":" ", oldptr == newptr ? ' ' : '!', | |
675 newptr, is_oop?"oop":" ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":" ")); | |
676 } | |
677 | |
678 #ifdef SPARC | |
679 static void print_me(intptr_t *new_sp, intptr_t *old_sp, bool *was_oops) { | |
680 #ifdef _LP64 | |
681 tty->print_cr("--------+------address-----+------before-----------+-------after----------+"); | |
682 const int incr = 1; // Increment to skip a long, in units of intptr_t | |
683 #else | |
684 tty->print_cr("--------+--address-+------before-----------+-------after----------+"); | |
685 const int incr = 2; // Increment to skip a long, in units of intptr_t | |
686 #endif | |
687 tty->print_cr("---SP---|"); | |
688 for( int i=0; i<16; i++ ) { | |
689 tty->print("blob %c%d |"PTR_FORMAT" ","LO"[i>>3],i&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); } | |
690 tty->print_cr("--------|"); | |
691 for( int i1=0; i1<frame::memory_parameter_word_sp_offset-16; i1++ ) { | |
692 tty->print("argv pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); } | |
693 tty->print(" pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); | |
694 tty->print_cr("--------|"); | |
695 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; | |
696 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; | |
697 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; | |
698 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; | |
699 tty->print_cr(" FSR |"PTR_FORMAT" "PTR64_FORMAT" "PTR64_FORMAT,new_sp,*(jlong*)old_sp,*(jlong*)new_sp); | |
700 old_sp += incr; new_sp += incr; was_oops += incr; | |
701 // Skip the floats | |
702 tty->print_cr("--Float-|"PTR_FORMAT,new_sp); | |
703 tty->print_cr("---FP---|"); | |
704 old_sp += incr*32; new_sp += incr*32; was_oops += incr*32; | |
705 for( int i2=0; i2<16; i2++ ) { | |
706 tty->print("call %c%d |"PTR_FORMAT" ","LI"[i2>>3],i2&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); } | |
707 tty->print_cr(""); | |
708 } | |
709 #endif // SPARC | |
710 #endif // PRODUCT | |
711 | |
712 | |
713 void SafepointSynchronize::handle_polling_page_exception(JavaThread *thread) { | |
714 assert(thread->is_Java_thread(), "polling reference encountered by VM thread"); | |
715 assert(thread->thread_state() == _thread_in_Java, "should come from Java code"); | |
716 assert(SafepointSynchronize::is_synchronizing(), "polling encountered outside safepoint synchronization"); | |
717 | |
718 // Uncomment this to get some serious before/after printing of the | |
719 // Sparc safepoint-blob frame structure. | |
720 /* | |
721 intptr_t* sp = thread->last_Java_sp(); | |
722 intptr_t stack_copy[150]; | |
723 for( int i=0; i<150; i++ ) stack_copy[i] = sp[i]; | |
724 bool was_oops[150]; | |
725 for( int i=0; i<150; i++ ) | |
726 was_oops[i] = stack_copy[i] ? ((oop)stack_copy[i])->is_oop() : false; | |
727 */ | |
728 | |
729 if (ShowSafepointMsgs) { | |
730 tty->print("handle_polling_page_exception: "); | |
731 } | |
732 | |
733 if (PrintSafepointStatistics) { | |
734 inc_page_trap_count(); | |
735 } | |
736 | |
737 ThreadSafepointState* state = thread->safepoint_state(); | |
738 | |
739 state->handle_polling_page_exception(); | |
740 // print_me(sp,stack_copy,was_oops); | |
741 } | |
742 | |
743 | |
744 void SafepointSynchronize::print_safepoint_timeout(SafepointTimeoutReason reason) { | |
745 if (!timeout_error_printed) { | |
746 timeout_error_printed = true; | |
747 // Print out the thread infor which didn't reach the safepoint for debugging | |
748 // purposes (useful when there are lots of threads in the debugger). | |
749 tty->print_cr(""); | |
750 tty->print_cr("# SafepointSynchronize::begin: Timeout detected:"); | |
751 if (reason == _spinning_timeout) { | |
752 tty->print_cr("# SafepointSynchronize::begin: Timed out while spinning to reach a safepoint."); | |
753 } else if (reason == _blocking_timeout) { | |
754 tty->print_cr("# SafepointSynchronize::begin: Timed out while waiting for threads to stop."); | |
755 } | |
756 | |
757 tty->print_cr("# SafepointSynchronize::begin: Threads which did not reach the safepoint:"); | |
758 ThreadSafepointState *cur_state; | |
759 ResourceMark rm; | |
760 for(JavaThread *cur_thread = Threads::first(); cur_thread; | |
761 cur_thread = cur_thread->next()) { | |
762 cur_state = cur_thread->safepoint_state(); | |
763 | |
764 if (cur_thread->thread_state() != _thread_blocked && | |
765 ((reason == _spinning_timeout && cur_state->is_running()) || | |
766 (reason == _blocking_timeout && !cur_state->has_called_back()))) { | |
767 tty->print("# "); | |
768 cur_thread->print(); | |
769 tty->print_cr(""); | |
770 } | |
771 } | |
772 tty->print_cr("# SafepointSynchronize::begin: (End of list)"); | |
773 } | |
774 | |
775 // To debug the long safepoint, specify both DieOnSafepointTimeout & | |
776 // ShowMessageBoxOnError. | |
777 if (DieOnSafepointTimeout) { | |
778 char msg[1024]; | |
779 VM_Operation *op = VMThread::vm_operation(); | |
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780 sprintf(msg, "Safepoint sync time longer than " INTX_FORMAT "ms detected when executing %s.", |
0 | 781 SafepointTimeoutDelay, |
782 op != NULL ? op->name() : "no vm operation"); | |
783 fatal(msg); | |
784 } | |
785 } | |
786 | |
787 | |
788 // ------------------------------------------------------------------------------------------------------- | |
789 // Implementation of ThreadSafepointState | |
790 | |
791 ThreadSafepointState::ThreadSafepointState(JavaThread *thread) { | |
792 _thread = thread; | |
793 _type = _running; | |
794 _has_called_back = false; | |
795 _at_poll_safepoint = false; | |
796 } | |
797 | |
798 void ThreadSafepointState::create(JavaThread *thread) { | |
799 ThreadSafepointState *state = new ThreadSafepointState(thread); | |
800 thread->set_safepoint_state(state); | |
801 } | |
802 | |
803 void ThreadSafepointState::destroy(JavaThread *thread) { | |
804 if (thread->safepoint_state()) { | |
805 delete(thread->safepoint_state()); | |
806 thread->set_safepoint_state(NULL); | |
807 } | |
808 } | |
809 | |
810 void ThreadSafepointState::examine_state_of_thread() { | |
811 assert(is_running(), "better be running or just have hit safepoint poll"); | |
812 | |
813 JavaThreadState state = _thread->thread_state(); | |
814 | |
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815 // Save the state at the start of safepoint processing. |
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816 _orig_thread_state = state; |
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817 |
0 | 818 // Check for a thread that is suspended. Note that thread resume tries |
819 // to grab the Threads_lock which we own here, so a thread cannot be | |
820 // resumed during safepoint synchronization. | |
821 | |
979 | 822 // We check to see if this thread is suspended without locking to |
823 // avoid deadlocking with a third thread that is waiting for this | |
824 // thread to be suspended. The third thread can notice the safepoint | |
825 // that we're trying to start at the beginning of its SR_lock->wait() | |
826 // call. If that happens, then the third thread will block on the | |
827 // safepoint while still holding the underlying SR_lock. We won't be | |
828 // able to get the SR_lock and we'll deadlock. | |
829 // | |
830 // We don't need to grab the SR_lock here for two reasons: | |
831 // 1) The suspend flags are both volatile and are set with an | |
832 // Atomic::cmpxchg() call so we should see the suspended | |
833 // state right away. | |
834 // 2) We're being called from the safepoint polling loop; if | |
835 // we don't see the suspended state on this iteration, then | |
836 // we'll come around again. | |
837 // | |
838 bool is_suspended = _thread->is_ext_suspended(); | |
0 | 839 if (is_suspended) { |
840 roll_forward(_at_safepoint); | |
841 return; | |
842 } | |
843 | |
844 // Some JavaThread states have an initial safepoint state of | |
845 // running, but are actually at a safepoint. We will happily | |
846 // agree and update the safepoint state here. | |
847 if (SafepointSynchronize::safepoint_safe(_thread, state)) { | |
848 roll_forward(_at_safepoint); | |
849 return; | |
850 } | |
851 | |
852 if (state == _thread_in_vm) { | |
853 roll_forward(_call_back); | |
854 return; | |
855 } | |
856 | |
857 // All other thread states will continue to run until they | |
858 // transition and self-block in state _blocked | |
859 // Safepoint polling in compiled code causes the Java threads to do the same. | |
860 // Note: new threads may require a malloc so they must be allowed to finish | |
861 | |
862 assert(is_running(), "examine_state_of_thread on non-running thread"); | |
863 return; | |
864 } | |
865 | |
866 // Returns true is thread could not be rolled forward at present position. | |
867 void ThreadSafepointState::roll_forward(suspend_type type) { | |
868 _type = type; | |
869 | |
870 switch(_type) { | |
871 case _at_safepoint: | |
872 SafepointSynchronize::signal_thread_at_safepoint(); | |
873 break; | |
874 | |
875 case _call_back: | |
876 set_has_called_back(false); | |
877 break; | |
878 | |
879 case _running: | |
880 default: | |
881 ShouldNotReachHere(); | |
882 } | |
883 } | |
884 | |
885 void ThreadSafepointState::restart() { | |
886 switch(type()) { | |
887 case _at_safepoint: | |
888 case _call_back: | |
889 break; | |
890 | |
891 case _running: | |
892 default: | |
893 tty->print_cr("restart thread "INTPTR_FORMAT" with state %d", | |
894 _thread, _type); | |
895 _thread->print(); | |
896 ShouldNotReachHere(); | |
897 } | |
898 _type = _running; | |
899 set_has_called_back(false); | |
900 } | |
901 | |
902 | |
903 void ThreadSafepointState::print_on(outputStream *st) const { | |
904 const char *s; | |
905 | |
906 switch(_type) { | |
907 case _running : s = "_running"; break; | |
908 case _at_safepoint : s = "_at_safepoint"; break; | |
909 case _call_back : s = "_call_back"; break; | |
910 default: | |
911 ShouldNotReachHere(); | |
912 } | |
913 | |
914 st->print_cr("Thread: " INTPTR_FORMAT | |
915 " [0x%2x] State: %s _has_called_back %d _at_poll_safepoint %d", | |
916 _thread, _thread->osthread()->thread_id(), s, _has_called_back, | |
917 _at_poll_safepoint); | |
918 | |
919 _thread->print_thread_state_on(st); | |
920 } | |
921 | |
922 | |
923 // --------------------------------------------------------------------------------------------------------------------- | |
924 | |
925 // Block the thread at the safepoint poll or poll return. | |
926 void ThreadSafepointState::handle_polling_page_exception() { | |
927 | |
928 // Check state. block() will set thread state to thread_in_vm which will | |
929 // cause the safepoint state _type to become _call_back. | |
930 assert(type() == ThreadSafepointState::_running, | |
931 "polling page exception on thread not running state"); | |
932 | |
933 // Step 1: Find the nmethod from the return address | |
934 if (ShowSafepointMsgs && Verbose) { | |
935 tty->print_cr("Polling page exception at " INTPTR_FORMAT, thread()->saved_exception_pc()); | |
936 } | |
937 address real_return_addr = thread()->saved_exception_pc(); | |
938 | |
939 CodeBlob *cb = CodeCache::find_blob(real_return_addr); | |
940 assert(cb != NULL && cb->is_nmethod(), "return address should be in nmethod"); | |
941 nmethod* nm = (nmethod*)cb; | |
942 | |
943 // Find frame of caller | |
944 frame stub_fr = thread()->last_frame(); | |
945 CodeBlob* stub_cb = stub_fr.cb(); | |
946 assert(stub_cb->is_safepoint_stub(), "must be a safepoint stub"); | |
947 RegisterMap map(thread(), true); | |
948 frame caller_fr = stub_fr.sender(&map); | |
949 | |
950 // Should only be poll_return or poll | |
951 assert( nm->is_at_poll_or_poll_return(real_return_addr), "should not be at call" ); | |
952 | |
953 // This is a poll immediately before a return. The exception handling code | |
954 // has already had the effect of causing the return to occur, so the execution | |
955 // will continue immediately after the call. In addition, the oopmap at the | |
956 // return point does not mark the return value as an oop (if it is), so | |
957 // it needs a handle here to be updated. | |
958 if( nm->is_at_poll_return(real_return_addr) ) { | |
959 // See if return type is an oop. | |
960 bool return_oop = nm->method()->is_returning_oop(); | |
961 Handle return_value; | |
962 if (return_oop) { | |
963 // The oop result has been saved on the stack together with all | |
964 // the other registers. In order to preserve it over GCs we need | |
965 // to keep it in a handle. | |
966 oop result = caller_fr.saved_oop_result(&map); | |
967 assert(result == NULL || result->is_oop(), "must be oop"); | |
968 return_value = Handle(thread(), result); | |
969 assert(Universe::heap()->is_in_or_null(result), "must be heap pointer"); | |
970 } | |
971 | |
972 // Block the thread | |
973 SafepointSynchronize::block(thread()); | |
974 | |
975 // restore oop result, if any | |
976 if (return_oop) { | |
977 caller_fr.set_saved_oop_result(&map, return_value()); | |
978 } | |
979 } | |
980 | |
981 // This is a safepoint poll. Verify the return address and block. | |
982 else { | |
983 set_at_poll_safepoint(true); | |
984 | |
985 // verify the blob built the "return address" correctly | |
986 assert(real_return_addr == caller_fr.pc(), "must match"); | |
987 | |
988 // Block the thread | |
989 SafepointSynchronize::block(thread()); | |
990 set_at_poll_safepoint(false); | |
991 | |
992 // If we have a pending async exception deoptimize the frame | |
993 // as otherwise we may never deliver it. | |
994 if (thread()->has_async_condition()) { | |
995 ThreadInVMfromJavaNoAsyncException __tiv(thread()); | |
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996 Deoptimization::deoptimize_frame(thread(), caller_fr.id()); |
0 | 997 } |
998 | |
999 // If an exception has been installed we must check for a pending deoptimization | |
1000 // Deoptimize frame if exception has been thrown. | |
1001 | |
1002 if (thread()->has_pending_exception() ) { | |
1003 RegisterMap map(thread(), true); | |
1004 frame caller_fr = stub_fr.sender(&map); | |
1005 if (caller_fr.is_deoptimized_frame()) { | |
1006 // The exception patch will destroy registers that are still | |
1007 // live and will be needed during deoptimization. Defer the | |
1008 // Async exception should have defered the exception until the | |
1009 // next safepoint which will be detected when we get into | |
1010 // the interpreter so if we have an exception now things | |
1011 // are messed up. | |
1012 | |
1013 fatal("Exception installed and deoptimization is pending"); | |
1014 } | |
1015 } | |
1016 } | |
1017 } | |
1018 | |
1019 | |
1020 // | |
1021 // Statistics & Instrumentations | |
1022 // | |
1023 SafepointSynchronize::SafepointStats* SafepointSynchronize::_safepoint_stats = NULL; | |
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1024 jlong SafepointSynchronize::_safepoint_begin_time = 0; |
0 | 1025 int SafepointSynchronize::_cur_stat_index = 0; |
1026 julong SafepointSynchronize::_safepoint_reasons[VM_Operation::VMOp_Terminating]; | |
1027 julong SafepointSynchronize::_coalesced_vmop_count = 0; | |
1028 jlong SafepointSynchronize::_max_sync_time = 0; | |
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1029 jlong SafepointSynchronize::_max_vmop_time = 0; |
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1030 float SafepointSynchronize::_ts_of_current_safepoint = 0.0f; |
0 | 1031 |
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1032 static jlong cleanup_end_time = 0; |
0 | 1033 static bool need_to_track_page_armed_status = false; |
1034 static bool init_done = false; | |
1035 | |
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1036 // Helper method to print the header. |
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1037 static void print_header() { |
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1038 tty->print(" vmop " |
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1039 "[threads: total initially_running wait_to_block] "); |
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1040 tty->print("[time: spin block sync cleanup vmop] "); |
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1041 |
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1042 // no page armed status printed out if it is always armed. |
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1043 if (need_to_track_page_armed_status) { |
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1044 tty->print("page_armed "); |
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1045 } |
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1046 |
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1047 tty->print_cr("page_trap_count"); |
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1048 } |
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1049 |
0 | 1050 void SafepointSynchronize::deferred_initialize_stat() { |
1051 if (init_done) return; | |
1052 | |
1053 if (PrintSafepointStatisticsCount <= 0) { | |
1054 fatal("Wrong PrintSafepointStatisticsCount"); | |
1055 } | |
1056 | |
1057 // If PrintSafepointStatisticsTimeout is specified, the statistics data will | |
1058 // be printed right away, in which case, _safepoint_stats will regress to | |
1059 // a single element array. Otherwise, it is a circular ring buffer with default | |
1060 // size of PrintSafepointStatisticsCount. | |
1061 int stats_array_size; | |
1062 if (PrintSafepointStatisticsTimeout > 0) { | |
1063 stats_array_size = 1; | |
1064 PrintSafepointStatistics = true; | |
1065 } else { | |
1066 stats_array_size = PrintSafepointStatisticsCount; | |
1067 } | |
1068 _safepoint_stats = (SafepointStats*)os::malloc(stats_array_size | |
1069 * sizeof(SafepointStats)); | |
1070 guarantee(_safepoint_stats != NULL, | |
1071 "not enough memory for safepoint instrumentation data"); | |
1072 | |
1073 if (UseCompilerSafepoints && DeferPollingPageLoopCount >= 0) { | |
1074 need_to_track_page_armed_status = true; | |
1075 } | |
1076 init_done = true; | |
1077 } | |
1078 | |
1079 void SafepointSynchronize::begin_statistics(int nof_threads, int nof_running) { | |
1003 | 1080 assert(init_done, "safepoint statistics array hasn't been initialized"); |
0 | 1081 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; |
1082 | |
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1083 spstat->_time_stamp = _ts_of_current_safepoint; |
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1084 |
0 | 1085 VM_Operation *op = VMThread::vm_operation(); |
1086 spstat->_vmop_type = (op != NULL ? op->type() : -1); | |
1087 if (op != NULL) { | |
1088 _safepoint_reasons[spstat->_vmop_type]++; | |
1089 } | |
1090 | |
1091 spstat->_nof_total_threads = nof_threads; | |
1092 spstat->_nof_initial_running_threads = nof_running; | |
1093 spstat->_nof_threads_hit_page_trap = 0; | |
1094 | |
1095 // Records the start time of spinning. The real time spent on spinning | |
1096 // will be adjusted when spin is done. Same trick is applied for time | |
1097 // spent on waiting for threads to block. | |
1098 if (nof_running != 0) { | |
1099 spstat->_time_to_spin = os::javaTimeNanos(); | |
1100 } else { | |
1101 spstat->_time_to_spin = 0; | |
1102 } | |
1103 } | |
1104 | |
1105 void SafepointSynchronize::update_statistics_on_spin_end() { | |
1106 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; | |
1107 | |
1108 jlong cur_time = os::javaTimeNanos(); | |
1109 | |
1110 spstat->_nof_threads_wait_to_block = _waiting_to_block; | |
1111 if (spstat->_nof_initial_running_threads != 0) { | |
1112 spstat->_time_to_spin = cur_time - spstat->_time_to_spin; | |
1113 } | |
1114 | |
1115 if (need_to_track_page_armed_status) { | |
1116 spstat->_page_armed = (PageArmed == 1); | |
1117 } | |
1118 | |
1119 // Records the start time of waiting for to block. Updated when block is done. | |
1120 if (_waiting_to_block != 0) { | |
1121 spstat->_time_to_wait_to_block = cur_time; | |
1122 } else { | |
1123 spstat->_time_to_wait_to_block = 0; | |
1124 } | |
1125 } | |
1126 | |
1127 void SafepointSynchronize::update_statistics_on_sync_end(jlong end_time) { | |
1128 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; | |
1129 | |
1130 if (spstat->_nof_threads_wait_to_block != 0) { | |
1131 spstat->_time_to_wait_to_block = end_time - | |
1132 spstat->_time_to_wait_to_block; | |
1133 } | |
1134 | |
1135 // Records the end time of sync which will be used to calculate the total | |
1136 // vm operation time. Again, the real time spending in syncing will be deducted | |
1137 // from the start of the sync time later when end_statistics is called. | |
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1138 spstat->_time_to_sync = end_time - _safepoint_begin_time; |
0 | 1139 if (spstat->_time_to_sync > _max_sync_time) { |
1140 _max_sync_time = spstat->_time_to_sync; | |
1141 } | |
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1142 |
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1143 spstat->_time_to_do_cleanups = end_time; |
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1144 } |
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1145 |
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1146 void SafepointSynchronize::update_statistics_on_cleanup_end(jlong end_time) { |
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1147 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; |
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1148 |
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1149 // Record how long spent in cleanup tasks. |
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1150 spstat->_time_to_do_cleanups = end_time - spstat->_time_to_do_cleanups; |
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1151 |
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1152 cleanup_end_time = end_time; |
0 | 1153 } |
1154 | |
1155 void SafepointSynchronize::end_statistics(jlong vmop_end_time) { | |
1156 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; | |
1157 | |
1158 // Update the vm operation time. | |
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1159 spstat->_time_to_exec_vmop = vmop_end_time - cleanup_end_time; |
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1160 if (spstat->_time_to_exec_vmop > _max_vmop_time) { |
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1161 _max_vmop_time = spstat->_time_to_exec_vmop; |
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1162 } |
0 | 1163 // Only the sync time longer than the specified |
1164 // PrintSafepointStatisticsTimeout will be printed out right away. | |
1165 // By default, it is -1 meaning all samples will be put into the list. | |
1166 if ( PrintSafepointStatisticsTimeout > 0) { | |
1167 if (spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) { | |
1168 print_statistics(); | |
1169 } | |
1170 } else { | |
1171 // The safepoint statistics will be printed out when the _safepoin_stats | |
1172 // array fills up. | |
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1173 if (_cur_stat_index == PrintSafepointStatisticsCount - 1) { |
0 | 1174 print_statistics(); |
1175 _cur_stat_index = 0; | |
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1176 } else { |
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1177 _cur_stat_index++; |
0 | 1178 } |
1179 } | |
1180 } | |
1181 | |
1182 void SafepointSynchronize::print_statistics() { | |
1183 SafepointStats* sstats = _safepoint_stats; | |
1184 | |
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1185 for (int index = 0; index <= _cur_stat_index; index++) { |
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1186 if (index % 30 == 0) { |
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1187 print_header(); |
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1188 } |
0 | 1189 sstats = &_safepoint_stats[index]; |
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1190 tty->print("%.3f: ", sstats->_time_stamp); |
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1191 tty->print("%-26s [" |
0 | 1192 INT32_FORMAT_W(8)INT32_FORMAT_W(11)INT32_FORMAT_W(15) |
1291
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1193 " ] ", |
0 | 1194 sstats->_vmop_type == -1 ? "no vm operation" : |
1195 VM_Operation::name(sstats->_vmop_type), | |
1196 sstats->_nof_total_threads, | |
1197 sstats->_nof_initial_running_threads, | |
1198 sstats->_nof_threads_wait_to_block); | |
1199 // "/ MICROUNITS " is to convert the unit from nanos to millis. | |
1291
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1200 tty->print(" [" |
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1201 INT64_FORMAT_W(6)INT64_FORMAT_W(6) |
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1202 INT64_FORMAT_W(6)INT64_FORMAT_W(6) |
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1203 INT64_FORMAT_W(6)" ] ", |
0 | 1204 sstats->_time_to_spin / MICROUNITS, |
1205 sstats->_time_to_wait_to_block / MICROUNITS, | |
1206 sstats->_time_to_sync / MICROUNITS, | |
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1207 sstats->_time_to_do_cleanups / MICROUNITS, |
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1208 sstats->_time_to_exec_vmop / MICROUNITS); |
0 | 1209 |
1210 if (need_to_track_page_armed_status) { | |
1211 tty->print(INT32_FORMAT" ", sstats->_page_armed); | |
1212 } | |
1213 tty->print_cr(INT32_FORMAT" ", sstats->_nof_threads_hit_page_trap); | |
1214 } | |
1215 } | |
1216 | |
1217 // This method will be called when VM exits. It will first call | |
1218 // print_statistics to print out the rest of the sampling. Then | |
1219 // it tries to summarize the sampling. | |
1220 void SafepointSynchronize::print_stat_on_exit() { | |
1221 if (_safepoint_stats == NULL) return; | |
1222 | |
1223 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; | |
1224 | |
1225 // During VM exit, end_statistics may not get called and in that | |
1226 // case, if the sync time is less than PrintSafepointStatisticsTimeout, | |
1227 // don't print it out. | |
1228 // Approximate the vm op time. | |
1229 _safepoint_stats[_cur_stat_index]._time_to_exec_vmop = | |
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1230 os::javaTimeNanos() - cleanup_end_time; |
0 | 1231 |
1232 if ( PrintSafepointStatisticsTimeout < 0 || | |
1233 spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) { | |
1234 print_statistics(); | |
1235 } | |
1236 tty->print_cr(""); | |
1237 | |
1238 // Print out polling page sampling status. | |
1239 if (!need_to_track_page_armed_status) { | |
1240 if (UseCompilerSafepoints) { | |
1241 tty->print_cr("Polling page always armed"); | |
1242 } | |
1243 } else { | |
1244 tty->print_cr("Defer polling page loop count = %d\n", | |
1245 DeferPollingPageLoopCount); | |
1246 } | |
1247 | |
1248 for (int index = 0; index < VM_Operation::VMOp_Terminating; index++) { | |
1249 if (_safepoint_reasons[index] != 0) { | |
1250 tty->print_cr("%-26s"UINT64_FORMAT_W(10), VM_Operation::name(index), | |
1251 _safepoint_reasons[index]); | |
1252 } | |
1253 } | |
1254 | |
1255 tty->print_cr(UINT64_FORMAT_W(5)" VM operations coalesced during safepoint", | |
1256 _coalesced_vmop_count); | |
1257 tty->print_cr("Maximum sync time "INT64_FORMAT_W(5)" ms", | |
1258 _max_sync_time / MICROUNITS); | |
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1259 tty->print_cr("Maximum vm operation time (except for Exit VM operation) " |
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1260 INT64_FORMAT_W(5)" ms", |
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1261 _max_vmop_time / MICROUNITS); |
0 | 1262 } |
1263 | |
1264 // ------------------------------------------------------------------------------------------------ | |
1265 // Non-product code | |
1266 | |
1267 #ifndef PRODUCT | |
1268 | |
1269 void SafepointSynchronize::print_state() { | |
1270 if (_state == _not_synchronized) { | |
1271 tty->print_cr("not synchronized"); | |
1272 } else if (_state == _synchronizing || _state == _synchronized) { | |
1273 tty->print_cr("State: %s", (_state == _synchronizing) ? "synchronizing" : | |
1274 "synchronized"); | |
1275 | |
1276 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) { | |
1277 cur->safepoint_state()->print(); | |
1278 } | |
1279 } | |
1280 } | |
1281 | |
1282 void SafepointSynchronize::safepoint_msg(const char* format, ...) { | |
1283 if (ShowSafepointMsgs) { | |
1284 va_list ap; | |
1285 va_start(ap, format); | |
1286 tty->vprint_cr(format, ap); | |
1287 va_end(ap); | |
1288 } | |
1289 } | |
1290 | |
1291 #endif // !PRODUCT |