Mercurial > hg > graal-compiler
annotate src/share/vm/runtime/safepoint.cpp @ 4712:e7dead7e90af
7117303: VM uses non-monotonic time source and complains that it is non-monotonic
Summary: Replaces calls to os::javaTimeMillis(), which does not (and cannot) guarantee monotonicity, in GC code to an equivalent expression that uses os::javaTimeNanos(). os::javaTimeNanos is guaranteed monotonically non-decreasing if the underlying platform provides a monotonic time source. Changes in OS files are to make use of the newly defined constants in globalDefinitions.hpp.
Reviewed-by: dholmes, ysr
author | johnc |
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date | Mon, 19 Dec 2011 10:02:05 -0800 |
parents | f08d439fab8c |
children | 1a2723f7ad8e |
rev | line source |
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0 | 1 /* |
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2 * Copyright (c) 1997, 2011, 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" | |
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37 #include "oops/symbol.hpp" |
1972 | 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 | |
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64 #ifdef TARGET_ARCH_arm |
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65 # include "nativeInst_arm.hpp" |
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66 # include "vmreg_arm.inline.hpp" |
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67 #endif |
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68 #ifdef TARGET_ARCH_ppc |
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69 # include "nativeInst_ppc.hpp" |
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70 # include "vmreg_ppc.inline.hpp" |
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71 #endif |
1972 | 72 #ifdef TARGET_OS_FAMILY_linux |
73 # include "thread_linux.inline.hpp" | |
74 #endif | |
75 #ifdef TARGET_OS_FAMILY_solaris | |
76 # include "thread_solaris.inline.hpp" | |
77 #endif | |
78 #ifdef TARGET_OS_FAMILY_windows | |
79 # include "thread_windows.inline.hpp" | |
80 #endif | |
3960 | 81 #ifdef TARGET_OS_FAMILY_bsd |
82 # include "thread_bsd.inline.hpp" | |
83 #endif | |
1972 | 84 #ifndef SERIALGC |
85 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp" | |
86 #include "gc_implementation/shared/concurrentGCThread.hpp" | |
87 #endif | |
88 #ifdef COMPILER1 | |
89 #include "c1/c1_globals.hpp" | |
90 #endif | |
0 | 91 |
92 // -------------------------------------------------------------------------------------------------- | |
93 // Implementation of Safepoint begin/end | |
94 | |
95 SafepointSynchronize::SynchronizeState volatile SafepointSynchronize::_state = SafepointSynchronize::_not_synchronized; | |
96 volatile int SafepointSynchronize::_waiting_to_block = 0; | |
97 volatile int SafepointSynchronize::_safepoint_counter = 0; | |
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98 long SafepointSynchronize::_end_of_last_safepoint = 0; |
0 | 99 static volatile int PageArmed = 0 ; // safepoint polling page is RO|RW vs PROT_NONE |
100 static volatile int TryingToBlock = 0 ; // proximate value -- for advisory use only | |
101 static bool timeout_error_printed = false; | |
102 | |
103 // Roll all threads forward to a safepoint and suspend them all | |
104 void SafepointSynchronize::begin() { | |
105 | |
106 Thread* myThread = Thread::current(); | |
107 assert(myThread->is_VM_thread(), "Only VM thread may execute a safepoint"); | |
108 | |
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109 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) { |
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110 _safepoint_begin_time = os::javaTimeNanos(); |
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111 _ts_of_current_safepoint = tty->time_stamp().seconds(); |
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112 } |
0 | 113 |
114 #ifndef SERIALGC | |
115 if (UseConcMarkSweepGC) { | |
116 // In the future we should investigate whether CMS can use the | |
117 // more-general mechanism below. DLD (01/05). | |
118 ConcurrentMarkSweepThread::synchronize(false); | |
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119 } else if (UseG1GC) { |
0 | 120 ConcurrentGCThread::safepoint_synchronize(); |
121 } | |
122 #endif // SERIALGC | |
123 | |
124 // By getting the Threads_lock, we assure that no threads are about to start or | |
125 // exit. It is released again in SafepointSynchronize::end(). | |
126 Threads_lock->lock(); | |
127 | |
128 assert( _state == _not_synchronized, "trying to safepoint synchronize with wrong state"); | |
129 | |
130 int nof_threads = Threads::number_of_threads(); | |
131 | |
132 if (TraceSafepoint) { | |
133 tty->print_cr("Safepoint synchronization initiated. (%d)", nof_threads); | |
134 } | |
135 | |
136 RuntimeService::record_safepoint_begin(); | |
137 | |
138 { | |
139 MutexLocker mu(Safepoint_lock); | |
140 | |
141 // Set number of threads to wait for, before we initiate the callbacks | |
142 _waiting_to_block = nof_threads; | |
143 TryingToBlock = 0 ; | |
144 int still_running = nof_threads; | |
145 | |
146 // Save the starting time, so that it can be compared to see if this has taken | |
147 // too long to complete. | |
148 jlong safepoint_limit_time; | |
149 timeout_error_printed = false; | |
150 | |
1003 | 151 // PrintSafepointStatisticsTimeout can be specified separately. When |
152 // specified, PrintSafepointStatistics will be set to true in | |
153 // deferred_initialize_stat method. The initialization has to be done | |
154 // early enough to avoid any races. See bug 6880029 for details. | |
155 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) { | |
156 deferred_initialize_stat(); | |
157 } | |
158 | |
0 | 159 // Begin the process of bringing the system to a safepoint. |
160 // Java threads can be in several different states and are | |
161 // stopped by different mechanisms: | |
162 // | |
163 // 1. Running interpreted | |
164 // The interpeter dispatch table is changed to force it to | |
165 // check for a safepoint condition between bytecodes. | |
166 // 2. Running in native code | |
167 // When returning from the native code, a Java thread must check | |
168 // the safepoint _state to see if we must block. If the | |
169 // VM thread sees a Java thread in native, it does | |
170 // not wait for this thread to block. The order of the memory | |
171 // writes and reads of both the safepoint state and the Java | |
172 // threads state is critical. In order to guarantee that the | |
173 // memory writes are serialized with respect to each other, | |
174 // the VM thread issues a memory barrier instruction | |
175 // (on MP systems). In order to avoid the overhead of issuing | |
176 // a memory barrier for each Java thread making native calls, each Java | |
177 // thread performs a write to a single memory page after changing | |
178 // the thread state. The VM thread performs a sequence of | |
179 // mprotect OS calls which forces all previous writes from all | |
180 // Java threads to be serialized. This is done in the | |
181 // os::serialize_thread_states() call. This has proven to be | |
182 // much more efficient than executing a membar instruction | |
183 // on every call to native code. | |
184 // 3. Running compiled Code | |
185 // Compiled code reads a global (Safepoint Polling) page that | |
186 // is set to fault if we are trying to get to a safepoint. | |
187 // 4. Blocked | |
188 // A thread which is blocked will not be allowed to return from the | |
189 // block condition until the safepoint operation is complete. | |
190 // 5. In VM or Transitioning between states | |
191 // If a Java thread is currently running in the VM or transitioning | |
192 // between states, the safepointing code will wait for the thread to | |
193 // block itself when it attempts transitions to a new state. | |
194 // | |
195 _state = _synchronizing; | |
196 OrderAccess::fence(); | |
197 | |
198 // Flush all thread states to memory | |
199 if (!UseMembar) { | |
200 os::serialize_thread_states(); | |
201 } | |
202 | |
203 // Make interpreter safepoint aware | |
204 Interpreter::notice_safepoints(); | |
205 | |
206 if (UseCompilerSafepoints && DeferPollingPageLoopCount < 0) { | |
207 // Make polling safepoint aware | |
208 guarantee (PageArmed == 0, "invariant") ; | |
209 PageArmed = 1 ; | |
210 os::make_polling_page_unreadable(); | |
211 } | |
212 | |
213 // Consider using active_processor_count() ... but that call is expensive. | |
214 int ncpus = os::processor_count() ; | |
215 | |
216 #ifdef ASSERT | |
217 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) { | |
218 assert(cur->safepoint_state()->is_running(), "Illegal initial state"); | |
219 } | |
220 #endif // ASSERT | |
221 | |
222 if (SafepointTimeout) | |
223 safepoint_limit_time = os::javaTimeNanos() + (jlong)SafepointTimeoutDelay * MICROUNITS; | |
224 | |
225 // Iterate through all threads until it have been determined how to stop them all at a safepoint | |
226 unsigned int iterations = 0; | |
227 int steps = 0 ; | |
228 while(still_running > 0) { | |
229 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) { | |
230 assert(!cur->is_ConcurrentGC_thread(), "A concurrent GC thread is unexpectly being suspended"); | |
231 ThreadSafepointState *cur_state = cur->safepoint_state(); | |
232 if (cur_state->is_running()) { | |
233 cur_state->examine_state_of_thread(); | |
234 if (!cur_state->is_running()) { | |
235 still_running--; | |
236 // consider adjusting steps downward: | |
237 // steps = 0 | |
238 // steps -= NNN | |
239 // steps >>= 1 | |
240 // steps = MIN(steps, 2000-100) | |
241 // if (iterations != 0) steps -= NNN | |
242 } | |
243 if (TraceSafepoint && Verbose) cur_state->print(); | |
244 } | |
245 } | |
246 | |
1003 | 247 if (PrintSafepointStatistics && iterations == 0) { |
0 | 248 begin_statistics(nof_threads, still_running); |
249 } | |
250 | |
251 if (still_running > 0) { | |
252 // Check for if it takes to long | |
253 if (SafepointTimeout && safepoint_limit_time < os::javaTimeNanos()) { | |
254 print_safepoint_timeout(_spinning_timeout); | |
255 } | |
256 | |
257 // Spin to avoid context switching. | |
258 // There's a tension between allowing the mutators to run (and rendezvous) | |
259 // vs spinning. As the VM thread spins, wasting cycles, it consumes CPU that | |
260 // a mutator might otherwise use profitably to reach a safepoint. Excessive | |
261 // spinning by the VM thread on a saturated system can increase rendezvous latency. | |
262 // Blocking or yielding incur their own penalties in the form of context switching | |
263 // and the resultant loss of $ residency. | |
264 // | |
265 // Further complicating matters is that yield() does not work as naively expected | |
266 // on many platforms -- yield() does not guarantee that any other ready threads | |
267 // will run. As such we revert yield_all() after some number of iterations. | |
268 // Yield_all() is implemented as a short unconditional sleep on some platforms. | |
269 // Typical operating systems round a "short" sleep period up to 10 msecs, so sleeping | |
270 // can actually increase the time it takes the VM thread to detect that a system-wide | |
271 // stop-the-world safepoint has been reached. In a pathological scenario such as that | |
272 // described in CR6415670 the VMthread may sleep just before the mutator(s) become safe. | |
273 // In that case the mutators will be stalled waiting for the safepoint to complete and the | |
274 // the VMthread will be sleeping, waiting for the mutators to rendezvous. The VMthread | |
275 // will eventually wake up and detect that all mutators are safe, at which point | |
276 // we'll again make progress. | |
277 // | |
278 // Beware too that that the VMThread typically runs at elevated priority. | |
279 // Its default priority is higher than the default mutator priority. | |
280 // Obviously, this complicates spinning. | |
281 // | |
282 // Note too that on Windows XP SwitchThreadTo() has quite different behavior than Sleep(0). | |
283 // Sleep(0) will _not yield to lower priority threads, while SwitchThreadTo() will. | |
284 // | |
285 // See the comments in synchronizer.cpp for additional remarks on spinning. | |
286 // | |
287 // In the future we might: | |
288 // 1. Modify the safepoint scheme to avoid potentally unbounded spinning. | |
289 // This is tricky as the path used by a thread exiting the JVM (say on | |
290 // on JNI call-out) simply stores into its state field. The burden | |
291 // is placed on the VM thread, which must poll (spin). | |
292 // 2. Find something useful to do while spinning. If the safepoint is GC-related | |
293 // we might aggressively scan the stacks of threads that are already safe. | |
294 // 3. Use Solaris schedctl to examine the state of the still-running mutators. | |
295 // If all the mutators are ONPROC there's no reason to sleep or yield. | |
296 // 4. YieldTo() any still-running mutators that are ready but OFFPROC. | |
297 // 5. Check system saturation. If the system is not fully saturated then | |
298 // simply spin and avoid sleep/yield. | |
299 // 6. As still-running mutators rendezvous they could unpark the sleeping | |
300 // VMthread. This works well for still-running mutators that become | |
301 // safe. The VMthread must still poll for mutators that call-out. | |
302 // 7. Drive the policy on time-since-begin instead of iterations. | |
303 // 8. Consider making the spin duration a function of the # of CPUs: | |
304 // Spin = (((ncpus-1) * M) + K) + F(still_running) | |
305 // Alternately, instead of counting iterations of the outer loop | |
306 // we could count the # of threads visited in the inner loop, above. | |
307 // 9. On windows consider using the return value from SwitchThreadTo() | |
308 // to drive subsequent spin/SwitchThreadTo()/Sleep(N) decisions. | |
309 | |
310 if (UseCompilerSafepoints && int(iterations) == DeferPollingPageLoopCount) { | |
311 guarantee (PageArmed == 0, "invariant") ; | |
312 PageArmed = 1 ; | |
313 os::make_polling_page_unreadable(); | |
314 } | |
315 | |
316 // Instead of (ncpus > 1) consider either (still_running < (ncpus + EPSILON)) or | |
317 // ((still_running + _waiting_to_block - TryingToBlock)) < ncpus) | |
318 ++steps ; | |
319 if (ncpus > 1 && steps < SafepointSpinBeforeYield) { | |
320 SpinPause() ; // MP-Polite spin | |
321 } else | |
322 if (steps < DeferThrSuspendLoopCount) { | |
323 os::NakedYield() ; | |
324 } else { | |
325 os::yield_all(steps) ; | |
326 // Alternately, the VM thread could transiently depress its scheduling priority or | |
327 // transiently increase the priority of the tardy mutator(s). | |
328 } | |
329 | |
330 iterations ++ ; | |
331 } | |
332 assert(iterations < (uint)max_jint, "We have been iterating in the safepoint loop too long"); | |
333 } | |
334 assert(still_running == 0, "sanity check"); | |
335 | |
336 if (PrintSafepointStatistics) { | |
337 update_statistics_on_spin_end(); | |
338 } | |
339 | |
340 // wait until all threads are stopped | |
341 while (_waiting_to_block > 0) { | |
342 if (TraceSafepoint) tty->print_cr("Waiting for %d thread(s) to block", _waiting_to_block); | |
343 if (!SafepointTimeout || timeout_error_printed) { | |
344 Safepoint_lock->wait(true); // true, means with no safepoint checks | |
345 } else { | |
346 // Compute remaining time | |
347 jlong remaining_time = safepoint_limit_time - os::javaTimeNanos(); | |
348 | |
349 // If there is no remaining time, then there is an error | |
350 if (remaining_time < 0 || Safepoint_lock->wait(true, remaining_time / MICROUNITS)) { | |
351 print_safepoint_timeout(_blocking_timeout); | |
352 } | |
353 } | |
354 } | |
355 assert(_waiting_to_block == 0, "sanity check"); | |
356 | |
357 #ifndef PRODUCT | |
358 if (SafepointTimeout) { | |
359 jlong current_time = os::javaTimeNanos(); | |
360 if (safepoint_limit_time < current_time) { | |
361 tty->print_cr("# SafepointSynchronize: Finished after " | |
362 INT64_FORMAT_W(6) " ms", | |
363 ((current_time - safepoint_limit_time) / MICROUNITS + | |
364 SafepointTimeoutDelay)); | |
365 } | |
366 } | |
367 #endif | |
368 | |
369 assert((_safepoint_counter & 0x1) == 0, "must be even"); | |
370 assert(Threads_lock->owned_by_self(), "must hold Threads_lock"); | |
371 _safepoint_counter ++; | |
372 | |
373 // Record state | |
374 _state = _synchronized; | |
375 | |
376 OrderAccess::fence(); | |
377 | |
378 if (TraceSafepoint) { | |
379 VM_Operation *op = VMThread::vm_operation(); | |
380 tty->print_cr("Entering safepoint region: %s", (op != NULL) ? op->name() : "no vm operation"); | |
381 } | |
382 | |
383 RuntimeService::record_safepoint_synchronized(); | |
384 if (PrintSafepointStatistics) { | |
385 update_statistics_on_sync_end(os::javaTimeNanos()); | |
386 } | |
387 | |
388 // Call stuff that needs to be run when a safepoint is just about to be completed | |
389 do_cleanup_tasks(); | |
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390 |
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391 if (PrintSafepointStatistics) { |
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392 // Record how much time spend on the above cleanup tasks |
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393 update_statistics_on_cleanup_end(os::javaTimeNanos()); |
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394 } |
0 | 395 } |
396 } | |
397 | |
398 // Wake up all threads, so they are ready to resume execution after the safepoint | |
399 // operation has been carried out | |
400 void SafepointSynchronize::end() { | |
401 | |
402 assert(Threads_lock->owned_by_self(), "must hold Threads_lock"); | |
403 assert((_safepoint_counter & 0x1) == 1, "must be odd"); | |
404 _safepoint_counter ++; | |
405 // memory fence isn't required here since an odd _safepoint_counter | |
406 // value can do no harm and a fence is issued below anyway. | |
407 | |
408 DEBUG_ONLY(Thread* myThread = Thread::current();) | |
409 assert(myThread->is_VM_thread(), "Only VM thread can execute a safepoint"); | |
410 | |
411 if (PrintSafepointStatistics) { | |
412 end_statistics(os::javaTimeNanos()); | |
413 } | |
414 | |
415 #ifdef ASSERT | |
416 // A pending_exception cannot be installed during a safepoint. The threads | |
417 // may install an async exception after they come back from a safepoint into | |
418 // pending_exception after they unblock. But that should happen later. | |
419 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) { | |
420 assert (!(cur->has_pending_exception() && | |
421 cur->safepoint_state()->is_at_poll_safepoint()), | |
422 "safepoint installed a pending exception"); | |
423 } | |
424 #endif // ASSERT | |
425 | |
426 if (PageArmed) { | |
427 // Make polling safepoint aware | |
428 os::make_polling_page_readable(); | |
429 PageArmed = 0 ; | |
430 } | |
431 | |
432 // Remove safepoint check from interpreter | |
433 Interpreter::ignore_safepoints(); | |
434 | |
435 { | |
436 MutexLocker mu(Safepoint_lock); | |
437 | |
438 assert(_state == _synchronized, "must be synchronized before ending safepoint synchronization"); | |
439 | |
440 // Set to not synchronized, so the threads will not go into the signal_thread_blocked method | |
441 // when they get restarted. | |
442 _state = _not_synchronized; | |
443 OrderAccess::fence(); | |
444 | |
445 if (TraceSafepoint) { | |
446 tty->print_cr("Leaving safepoint region"); | |
447 } | |
448 | |
449 // Start suspended threads | |
450 for(JavaThread *current = Threads::first(); current; current = current->next()) { | |
605 | 451 // A problem occurring on Solaris is when attempting to restart threads |
0 | 452 // the first #cpus - 1 go well, but then the VMThread is preempted when we get |
453 // to the next one (since it has been running the longest). We then have | |
454 // to wait for a cpu to become available before we can continue restarting | |
455 // threads. | |
456 // FIXME: This causes the performance of the VM to degrade when active and with | |
457 // large numbers of threads. Apparently this is due to the synchronous nature | |
458 // of suspending threads. | |
459 // | |
460 // TODO-FIXME: the comments above are vestigial and no longer apply. | |
461 // Furthermore, using solaris' schedctl in this particular context confers no benefit | |
462 if (VMThreadHintNoPreempt) { | |
463 os::hint_no_preempt(); | |
464 } | |
465 ThreadSafepointState* cur_state = current->safepoint_state(); | |
466 assert(cur_state->type() != ThreadSafepointState::_running, "Thread not suspended at safepoint"); | |
467 cur_state->restart(); | |
468 assert(cur_state->is_running(), "safepoint state has not been reset"); | |
469 } | |
470 | |
471 RuntimeService::record_safepoint_end(); | |
472 | |
473 // Release threads lock, so threads can be created/destroyed again. It will also starts all threads | |
474 // blocked in signal_thread_blocked | |
475 Threads_lock->unlock(); | |
476 | |
477 } | |
478 #ifndef SERIALGC | |
479 // If there are any concurrent GC threads resume them. | |
480 if (UseConcMarkSweepGC) { | |
481 ConcurrentMarkSweepThread::desynchronize(false); | |
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482 } else if (UseG1GC) { |
0 | 483 ConcurrentGCThread::safepoint_desynchronize(); |
484 } | |
485 #endif // SERIALGC | |
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486 // record this time so VMThread can keep track how much time has elasped |
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487 // since last safepoint. |
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488 _end_of_last_safepoint = os::javaTimeMillis(); |
0 | 489 } |
490 | |
491 bool SafepointSynchronize::is_cleanup_needed() { | |
492 // Need a safepoint if some inline cache buffers is non-empty | |
493 if (!InlineCacheBuffer::is_empty()) return true; | |
494 return false; | |
495 } | |
496 | |
497 | |
498 | |
499 // Various cleaning tasks that should be done periodically at safepoints | |
500 void SafepointSynchronize::do_cleanup_tasks() { | |
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501 { |
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502 TraceTime t1("deflating idle monitors", TraceSafepointCleanupTime); |
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503 ObjectSynchronizer::deflate_idle_monitors(); |
0 | 504 } |
505 | |
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506 { |
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507 TraceTime t2("updating inline caches", TraceSafepointCleanupTime); |
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508 InlineCacheBuffer::update_inline_caches(); |
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509 } |
1783 | 510 { |
511 TraceTime t3("compilation policy safepoint handler", TraceSafepointCleanupTime); | |
512 CompilationPolicy::policy()->do_safepoint_work(); | |
0 | 513 } |
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514 |
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515 TraceTime t4("sweeping nmethods", TraceSafepointCleanupTime); |
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516 NMethodSweeper::scan_stacks(); |
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517 |
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518 // rotate log files? |
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519 if (UseGCLogFileRotation) { |
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520 gclog_or_tty->rotate_log(); |
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521 } |
0 | 522 } |
523 | |
524 | |
525 bool SafepointSynchronize::safepoint_safe(JavaThread *thread, JavaThreadState state) { | |
526 switch(state) { | |
527 case _thread_in_native: | |
528 // native threads are safe if they have no java stack or have walkable stack | |
529 return !thread->has_last_Java_frame() || thread->frame_anchor()->walkable(); | |
530 | |
531 // blocked threads should have already have walkable stack | |
532 case _thread_blocked: | |
533 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "blocked and not walkable"); | |
534 return true; | |
535 | |
536 default: | |
537 return false; | |
538 } | |
539 } | |
540 | |
541 | |
542 // ------------------------------------------------------------------------------------------------------- | |
543 // Implementation of Safepoint callback point | |
544 | |
545 void SafepointSynchronize::block(JavaThread *thread) { | |
546 assert(thread != NULL, "thread must be set"); | |
547 assert(thread->is_Java_thread(), "not a Java thread"); | |
548 | |
549 // Threads shouldn't block if they are in the middle of printing, but... | |
550 ttyLocker::break_tty_lock_for_safepoint(os::current_thread_id()); | |
551 | |
552 // Only bail from the block() call if the thread is gone from the | |
553 // thread list; starting to exit should still block. | |
554 if (thread->is_terminated()) { | |
555 // block current thread if we come here from native code when VM is gone | |
556 thread->block_if_vm_exited(); | |
557 | |
558 // otherwise do nothing | |
559 return; | |
560 } | |
561 | |
562 JavaThreadState state = thread->thread_state(); | |
563 thread->frame_anchor()->make_walkable(thread); | |
564 | |
565 // Check that we have a valid thread_state at this point | |
566 switch(state) { | |
567 case _thread_in_vm_trans: | |
568 case _thread_in_Java: // From compiled code | |
569 | |
570 // We are highly likely to block on the Safepoint_lock. In order to avoid blocking in this case, | |
571 // we pretend we are still in the VM. | |
572 thread->set_thread_state(_thread_in_vm); | |
573 | |
574 if (is_synchronizing()) { | |
575 Atomic::inc (&TryingToBlock) ; | |
576 } | |
577 | |
578 // We will always be holding the Safepoint_lock when we are examine the state | |
579 // of a thread. Hence, the instructions between the Safepoint_lock->lock() and | |
580 // Safepoint_lock->unlock() are happening atomic with regards to the safepoint code | |
581 Safepoint_lock->lock_without_safepoint_check(); | |
582 if (is_synchronizing()) { | |
583 // Decrement the number of threads to wait for and signal vm thread | |
584 assert(_waiting_to_block > 0, "sanity check"); | |
585 _waiting_to_block--; | |
586 thread->safepoint_state()->set_has_called_back(true); | |
587 | |
588 // Consider (_waiting_to_block < 2) to pipeline the wakeup of the VM thread | |
589 if (_waiting_to_block == 0) { | |
590 Safepoint_lock->notify_all(); | |
591 } | |
592 } | |
593 | |
594 // We transition the thread to state _thread_blocked here, but | |
595 // we can't do our usual check for external suspension and then | |
596 // self-suspend after the lock_without_safepoint_check() call | |
597 // below because we are often called during transitions while | |
598 // we hold different locks. That would leave us suspended while | |
599 // holding a resource which results in deadlocks. | |
600 thread->set_thread_state(_thread_blocked); | |
601 Safepoint_lock->unlock(); | |
602 | |
603 // We now try to acquire the threads lock. Since this lock is hold by the VM thread during | |
604 // the entire safepoint, the threads will all line up here during the safepoint. | |
605 Threads_lock->lock_without_safepoint_check(); | |
606 // restore original state. This is important if the thread comes from compiled code, so it | |
607 // will continue to execute with the _thread_in_Java state. | |
608 thread->set_thread_state(state); | |
609 Threads_lock->unlock(); | |
610 break; | |
611 | |
612 case _thread_in_native_trans: | |
613 case _thread_blocked_trans: | |
614 case _thread_new_trans: | |
615 if (thread->safepoint_state()->type() == ThreadSafepointState::_call_back) { | |
616 thread->print_thread_state(); | |
617 fatal("Deadlock in safepoint code. " | |
618 "Should have called back to the VM before blocking."); | |
619 } | |
620 | |
621 // We transition the thread to state _thread_blocked here, but | |
622 // we can't do our usual check for external suspension and then | |
623 // self-suspend after the lock_without_safepoint_check() call | |
624 // below because we are often called during transitions while | |
625 // we hold different locks. That would leave us suspended while | |
626 // holding a resource which results in deadlocks. | |
627 thread->set_thread_state(_thread_blocked); | |
628 | |
629 // It is not safe to suspend a thread if we discover it is in _thread_in_native_trans. Hence, | |
630 // the safepoint code might still be waiting for it to block. We need to change the state here, | |
631 // so it can see that it is at a safepoint. | |
632 | |
633 // Block until the safepoint operation is completed. | |
634 Threads_lock->lock_without_safepoint_check(); | |
635 | |
636 // Restore state | |
637 thread->set_thread_state(state); | |
638 | |
639 Threads_lock->unlock(); | |
640 break; | |
641 | |
642 default: | |
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643 fatal(err_msg("Illegal threadstate encountered: %d", state)); |
0 | 644 } |
645 | |
646 // Check for pending. async. exceptions or suspends - except if the | |
647 // thread was blocked inside the VM. has_special_runtime_exit_condition() | |
648 // is called last since it grabs a lock and we only want to do that when | |
649 // we must. | |
650 // | |
651 // Note: we never deliver an async exception at a polling point as the | |
652 // compiler may not have an exception handler for it. The polling | |
653 // code will notice the async and deoptimize and the exception will | |
654 // be delivered. (Polling at a return point is ok though). Sure is | |
655 // a lot of bother for a deprecated feature... | |
656 // | |
657 // We don't deliver an async exception if the thread state is | |
658 // _thread_in_native_trans so JNI functions won't be called with | |
659 // a surprising pending exception. If the thread state is going back to java, | |
660 // async exception is checked in check_special_condition_for_native_trans(). | |
661 | |
662 if (state != _thread_blocked_trans && | |
663 state != _thread_in_vm_trans && | |
664 thread->has_special_runtime_exit_condition()) { | |
665 thread->handle_special_runtime_exit_condition( | |
666 !thread->is_at_poll_safepoint() && (state != _thread_in_native_trans)); | |
667 } | |
668 } | |
669 | |
670 // ------------------------------------------------------------------------------------------------------ | |
671 // Exception handlers | |
672 | |
673 #ifndef PRODUCT | |
674 #ifdef _LP64 | |
675 #define PTR_PAD "" | |
676 #else | |
677 #define PTR_PAD " " | |
678 #endif | |
679 | |
680 static void print_ptrs(intptr_t oldptr, intptr_t newptr, bool wasoop) { | |
681 bool is_oop = newptr ? ((oop)newptr)->is_oop() : false; | |
682 tty->print_cr(PTR_FORMAT PTR_PAD " %s %c " PTR_FORMAT PTR_PAD " %s %s", | |
683 oldptr, wasoop?"oop":" ", oldptr == newptr ? ' ' : '!', | |
684 newptr, is_oop?"oop":" ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":" ")); | |
685 } | |
686 | |
687 static void print_longs(jlong oldptr, jlong newptr, bool wasoop) { | |
688 bool is_oop = newptr ? ((oop)(intptr_t)newptr)->is_oop() : false; | |
689 tty->print_cr(PTR64_FORMAT " %s %c " PTR64_FORMAT " %s %s", | |
690 oldptr, wasoop?"oop":" ", oldptr == newptr ? ' ' : '!', | |
691 newptr, is_oop?"oop":" ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":" ")); | |
692 } | |
693 | |
694 #ifdef SPARC | |
695 static void print_me(intptr_t *new_sp, intptr_t *old_sp, bool *was_oops) { | |
696 #ifdef _LP64 | |
697 tty->print_cr("--------+------address-----+------before-----------+-------after----------+"); | |
698 const int incr = 1; // Increment to skip a long, in units of intptr_t | |
699 #else | |
700 tty->print_cr("--------+--address-+------before-----------+-------after----------+"); | |
701 const int incr = 2; // Increment to skip a long, in units of intptr_t | |
702 #endif | |
703 tty->print_cr("---SP---|"); | |
704 for( int i=0; i<16; i++ ) { | |
705 tty->print("blob %c%d |"PTR_FORMAT" ","LO"[i>>3],i&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); } | |
706 tty->print_cr("--------|"); | |
707 for( int i1=0; i1<frame::memory_parameter_word_sp_offset-16; i1++ ) { | |
708 tty->print("argv pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); } | |
709 tty->print(" pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); | |
710 tty->print_cr("--------|"); | |
711 tty->print(" G1 |"PTR_FORMAT" ",new_sp); print_longs(*(jlong*)old_sp,*(jlong*)new_sp,was_oops[incr-1]); old_sp += incr; new_sp += incr; was_oops += incr; | |
712 tty->print(" G3 |"PTR_FORMAT" ",new_sp); print_longs(*(jlong*)old_sp,*(jlong*)new_sp,was_oops[incr-1]); old_sp += incr; new_sp += incr; was_oops += incr; | |
713 tty->print(" G4 |"PTR_FORMAT" ",new_sp); print_longs(*(jlong*)old_sp,*(jlong*)new_sp,was_oops[incr-1]); old_sp += incr; new_sp += incr; was_oops += incr; | |
714 tty->print(" G5 |"PTR_FORMAT" ",new_sp); print_longs(*(jlong*)old_sp,*(jlong*)new_sp,was_oops[incr-1]); old_sp += incr; new_sp += incr; was_oops += incr; | |
715 tty->print_cr(" FSR |"PTR_FORMAT" "PTR64_FORMAT" "PTR64_FORMAT,new_sp,*(jlong*)old_sp,*(jlong*)new_sp); | |
716 old_sp += incr; new_sp += incr; was_oops += incr; | |
717 // Skip the floats | |
718 tty->print_cr("--Float-|"PTR_FORMAT,new_sp); | |
719 tty->print_cr("---FP---|"); | |
720 old_sp += incr*32; new_sp += incr*32; was_oops += incr*32; | |
721 for( int i2=0; i2<16; i2++ ) { | |
722 tty->print("call %c%d |"PTR_FORMAT" ","LI"[i2>>3],i2&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); } | |
723 tty->print_cr(""); | |
724 } | |
725 #endif // SPARC | |
726 #endif // PRODUCT | |
727 | |
728 | |
729 void SafepointSynchronize::handle_polling_page_exception(JavaThread *thread) { | |
730 assert(thread->is_Java_thread(), "polling reference encountered by VM thread"); | |
731 assert(thread->thread_state() == _thread_in_Java, "should come from Java code"); | |
732 assert(SafepointSynchronize::is_synchronizing(), "polling encountered outside safepoint synchronization"); | |
733 | |
734 // Uncomment this to get some serious before/after printing of the | |
735 // Sparc safepoint-blob frame structure. | |
736 /* | |
737 intptr_t* sp = thread->last_Java_sp(); | |
738 intptr_t stack_copy[150]; | |
739 for( int i=0; i<150; i++ ) stack_copy[i] = sp[i]; | |
740 bool was_oops[150]; | |
741 for( int i=0; i<150; i++ ) | |
742 was_oops[i] = stack_copy[i] ? ((oop)stack_copy[i])->is_oop() : false; | |
743 */ | |
744 | |
745 if (ShowSafepointMsgs) { | |
746 tty->print("handle_polling_page_exception: "); | |
747 } | |
748 | |
749 if (PrintSafepointStatistics) { | |
750 inc_page_trap_count(); | |
751 } | |
752 | |
753 ThreadSafepointState* state = thread->safepoint_state(); | |
754 | |
755 state->handle_polling_page_exception(); | |
756 // print_me(sp,stack_copy,was_oops); | |
757 } | |
758 | |
759 | |
760 void SafepointSynchronize::print_safepoint_timeout(SafepointTimeoutReason reason) { | |
761 if (!timeout_error_printed) { | |
762 timeout_error_printed = true; | |
763 // Print out the thread infor which didn't reach the safepoint for debugging | |
764 // purposes (useful when there are lots of threads in the debugger). | |
765 tty->print_cr(""); | |
766 tty->print_cr("# SafepointSynchronize::begin: Timeout detected:"); | |
767 if (reason == _spinning_timeout) { | |
768 tty->print_cr("# SafepointSynchronize::begin: Timed out while spinning to reach a safepoint."); | |
769 } else if (reason == _blocking_timeout) { | |
770 tty->print_cr("# SafepointSynchronize::begin: Timed out while waiting for threads to stop."); | |
771 } | |
772 | |
773 tty->print_cr("# SafepointSynchronize::begin: Threads which did not reach the safepoint:"); | |
774 ThreadSafepointState *cur_state; | |
775 ResourceMark rm; | |
776 for(JavaThread *cur_thread = Threads::first(); cur_thread; | |
777 cur_thread = cur_thread->next()) { | |
778 cur_state = cur_thread->safepoint_state(); | |
779 | |
780 if (cur_thread->thread_state() != _thread_blocked && | |
781 ((reason == _spinning_timeout && cur_state->is_running()) || | |
782 (reason == _blocking_timeout && !cur_state->has_called_back()))) { | |
783 tty->print("# "); | |
784 cur_thread->print(); | |
785 tty->print_cr(""); | |
786 } | |
787 } | |
788 tty->print_cr("# SafepointSynchronize::begin: (End of list)"); | |
789 } | |
790 | |
791 // To debug the long safepoint, specify both DieOnSafepointTimeout & | |
792 // ShowMessageBoxOnError. | |
793 if (DieOnSafepointTimeout) { | |
794 char msg[1024]; | |
795 VM_Operation *op = VMThread::vm_operation(); | |
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796 sprintf(msg, "Safepoint sync time longer than " INTX_FORMAT "ms detected when executing %s.", |
0 | 797 SafepointTimeoutDelay, |
798 op != NULL ? op->name() : "no vm operation"); | |
799 fatal(msg); | |
800 } | |
801 } | |
802 | |
803 | |
804 // ------------------------------------------------------------------------------------------------------- | |
805 // Implementation of ThreadSafepointState | |
806 | |
807 ThreadSafepointState::ThreadSafepointState(JavaThread *thread) { | |
808 _thread = thread; | |
809 _type = _running; | |
810 _has_called_back = false; | |
811 _at_poll_safepoint = false; | |
812 } | |
813 | |
814 void ThreadSafepointState::create(JavaThread *thread) { | |
815 ThreadSafepointState *state = new ThreadSafepointState(thread); | |
816 thread->set_safepoint_state(state); | |
817 } | |
818 | |
819 void ThreadSafepointState::destroy(JavaThread *thread) { | |
820 if (thread->safepoint_state()) { | |
821 delete(thread->safepoint_state()); | |
822 thread->set_safepoint_state(NULL); | |
823 } | |
824 } | |
825 | |
826 void ThreadSafepointState::examine_state_of_thread() { | |
827 assert(is_running(), "better be running or just have hit safepoint poll"); | |
828 | |
829 JavaThreadState state = _thread->thread_state(); | |
830 | |
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831 // Save the state at the start of safepoint processing. |
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832 _orig_thread_state = state; |
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833 |
0 | 834 // Check for a thread that is suspended. Note that thread resume tries |
835 // to grab the Threads_lock which we own here, so a thread cannot be | |
836 // resumed during safepoint synchronization. | |
837 | |
979 | 838 // We check to see if this thread is suspended without locking to |
839 // avoid deadlocking with a third thread that is waiting for this | |
840 // thread to be suspended. The third thread can notice the safepoint | |
841 // that we're trying to start at the beginning of its SR_lock->wait() | |
842 // call. If that happens, then the third thread will block on the | |
843 // safepoint while still holding the underlying SR_lock. We won't be | |
844 // able to get the SR_lock and we'll deadlock. | |
845 // | |
846 // We don't need to grab the SR_lock here for two reasons: | |
847 // 1) The suspend flags are both volatile and are set with an | |
848 // Atomic::cmpxchg() call so we should see the suspended | |
849 // state right away. | |
850 // 2) We're being called from the safepoint polling loop; if | |
851 // we don't see the suspended state on this iteration, then | |
852 // we'll come around again. | |
853 // | |
854 bool is_suspended = _thread->is_ext_suspended(); | |
0 | 855 if (is_suspended) { |
856 roll_forward(_at_safepoint); | |
857 return; | |
858 } | |
859 | |
860 // Some JavaThread states have an initial safepoint state of | |
861 // running, but are actually at a safepoint. We will happily | |
862 // agree and update the safepoint state here. | |
863 if (SafepointSynchronize::safepoint_safe(_thread, state)) { | |
864 roll_forward(_at_safepoint); | |
865 return; | |
866 } | |
867 | |
868 if (state == _thread_in_vm) { | |
869 roll_forward(_call_back); | |
870 return; | |
871 } | |
872 | |
873 // All other thread states will continue to run until they | |
874 // transition and self-block in state _blocked | |
875 // Safepoint polling in compiled code causes the Java threads to do the same. | |
876 // Note: new threads may require a malloc so they must be allowed to finish | |
877 | |
878 assert(is_running(), "examine_state_of_thread on non-running thread"); | |
879 return; | |
880 } | |
881 | |
882 // Returns true is thread could not be rolled forward at present position. | |
883 void ThreadSafepointState::roll_forward(suspend_type type) { | |
884 _type = type; | |
885 | |
886 switch(_type) { | |
887 case _at_safepoint: | |
888 SafepointSynchronize::signal_thread_at_safepoint(); | |
889 break; | |
890 | |
891 case _call_back: | |
892 set_has_called_back(false); | |
893 break; | |
894 | |
895 case _running: | |
896 default: | |
897 ShouldNotReachHere(); | |
898 } | |
899 } | |
900 | |
901 void ThreadSafepointState::restart() { | |
902 switch(type()) { | |
903 case _at_safepoint: | |
904 case _call_back: | |
905 break; | |
906 | |
907 case _running: | |
908 default: | |
909 tty->print_cr("restart thread "INTPTR_FORMAT" with state %d", | |
910 _thread, _type); | |
911 _thread->print(); | |
912 ShouldNotReachHere(); | |
913 } | |
914 _type = _running; | |
915 set_has_called_back(false); | |
916 } | |
917 | |
918 | |
919 void ThreadSafepointState::print_on(outputStream *st) const { | |
920 const char *s; | |
921 | |
922 switch(_type) { | |
923 case _running : s = "_running"; break; | |
924 case _at_safepoint : s = "_at_safepoint"; break; | |
925 case _call_back : s = "_call_back"; break; | |
926 default: | |
927 ShouldNotReachHere(); | |
928 } | |
929 | |
930 st->print_cr("Thread: " INTPTR_FORMAT | |
931 " [0x%2x] State: %s _has_called_back %d _at_poll_safepoint %d", | |
932 _thread, _thread->osthread()->thread_id(), s, _has_called_back, | |
933 _at_poll_safepoint); | |
934 | |
935 _thread->print_thread_state_on(st); | |
936 } | |
937 | |
938 | |
939 // --------------------------------------------------------------------------------------------------------------------- | |
940 | |
941 // Block the thread at the safepoint poll or poll return. | |
942 void ThreadSafepointState::handle_polling_page_exception() { | |
943 | |
944 // Check state. block() will set thread state to thread_in_vm which will | |
945 // cause the safepoint state _type to become _call_back. | |
946 assert(type() == ThreadSafepointState::_running, | |
947 "polling page exception on thread not running state"); | |
948 | |
949 // Step 1: Find the nmethod from the return address | |
950 if (ShowSafepointMsgs && Verbose) { | |
951 tty->print_cr("Polling page exception at " INTPTR_FORMAT, thread()->saved_exception_pc()); | |
952 } | |
953 address real_return_addr = thread()->saved_exception_pc(); | |
954 | |
955 CodeBlob *cb = CodeCache::find_blob(real_return_addr); | |
956 assert(cb != NULL && cb->is_nmethod(), "return address should be in nmethod"); | |
957 nmethod* nm = (nmethod*)cb; | |
958 | |
959 // Find frame of caller | |
960 frame stub_fr = thread()->last_frame(); | |
961 CodeBlob* stub_cb = stub_fr.cb(); | |
962 assert(stub_cb->is_safepoint_stub(), "must be a safepoint stub"); | |
963 RegisterMap map(thread(), true); | |
964 frame caller_fr = stub_fr.sender(&map); | |
965 | |
966 // Should only be poll_return or poll | |
967 assert( nm->is_at_poll_or_poll_return(real_return_addr), "should not be at call" ); | |
968 | |
969 // This is a poll immediately before a return. The exception handling code | |
970 // has already had the effect of causing the return to occur, so the execution | |
971 // will continue immediately after the call. In addition, the oopmap at the | |
972 // return point does not mark the return value as an oop (if it is), so | |
973 // it needs a handle here to be updated. | |
974 if( nm->is_at_poll_return(real_return_addr) ) { | |
975 // See if return type is an oop. | |
976 bool return_oop = nm->method()->is_returning_oop(); | |
977 Handle return_value; | |
978 if (return_oop) { | |
979 // The oop result has been saved on the stack together with all | |
980 // the other registers. In order to preserve it over GCs we need | |
981 // to keep it in a handle. | |
982 oop result = caller_fr.saved_oop_result(&map); | |
983 assert(result == NULL || result->is_oop(), "must be oop"); | |
984 return_value = Handle(thread(), result); | |
985 assert(Universe::heap()->is_in_or_null(result), "must be heap pointer"); | |
986 } | |
987 | |
988 // Block the thread | |
989 SafepointSynchronize::block(thread()); | |
990 | |
991 // restore oop result, if any | |
992 if (return_oop) { | |
993 caller_fr.set_saved_oop_result(&map, return_value()); | |
994 } | |
995 } | |
996 | |
997 // This is a safepoint poll. Verify the return address and block. | |
998 else { | |
999 set_at_poll_safepoint(true); | |
1000 | |
1001 // verify the blob built the "return address" correctly | |
1002 assert(real_return_addr == caller_fr.pc(), "must match"); | |
1003 | |
1004 // Block the thread | |
1005 SafepointSynchronize::block(thread()); | |
1006 set_at_poll_safepoint(false); | |
1007 | |
1008 // If we have a pending async exception deoptimize the frame | |
1009 // as otherwise we may never deliver it. | |
1010 if (thread()->has_async_condition()) { | |
1011 ThreadInVMfromJavaNoAsyncException __tiv(thread()); | |
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1012 Deoptimization::deoptimize_frame(thread(), caller_fr.id()); |
0 | 1013 } |
1014 | |
1015 // If an exception has been installed we must check for a pending deoptimization | |
1016 // Deoptimize frame if exception has been thrown. | |
1017 | |
1018 if (thread()->has_pending_exception() ) { | |
1019 RegisterMap map(thread(), true); | |
1020 frame caller_fr = stub_fr.sender(&map); | |
1021 if (caller_fr.is_deoptimized_frame()) { | |
1022 // The exception patch will destroy registers that are still | |
1023 // live and will be needed during deoptimization. Defer the | |
1024 // Async exception should have defered the exception until the | |
1025 // next safepoint which will be detected when we get into | |
1026 // the interpreter so if we have an exception now things | |
1027 // are messed up. | |
1028 | |
1029 fatal("Exception installed and deoptimization is pending"); | |
1030 } | |
1031 } | |
1032 } | |
1033 } | |
1034 | |
1035 | |
1036 // | |
1037 // Statistics & Instrumentations | |
1038 // | |
1039 SafepointSynchronize::SafepointStats* SafepointSynchronize::_safepoint_stats = NULL; | |
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1040 jlong SafepointSynchronize::_safepoint_begin_time = 0; |
0 | 1041 int SafepointSynchronize::_cur_stat_index = 0; |
1042 julong SafepointSynchronize::_safepoint_reasons[VM_Operation::VMOp_Terminating]; | |
1043 julong SafepointSynchronize::_coalesced_vmop_count = 0; | |
1044 jlong SafepointSynchronize::_max_sync_time = 0; | |
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1045 jlong SafepointSynchronize::_max_vmop_time = 0; |
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1046 float SafepointSynchronize::_ts_of_current_safepoint = 0.0f; |
0 | 1047 |
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1048 static jlong cleanup_end_time = 0; |
0 | 1049 static bool need_to_track_page_armed_status = false; |
1050 static bool init_done = false; | |
1051 | |
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1052 // Helper method to print the header. |
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1053 static void print_header() { |
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1054 tty->print(" vmop " |
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1055 "[threads: total initially_running wait_to_block] "); |
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1056 tty->print("[time: spin block sync cleanup vmop] "); |
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1057 |
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1058 // no page armed status printed out if it is always armed. |
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1059 if (need_to_track_page_armed_status) { |
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1060 tty->print("page_armed "); |
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1061 } |
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1062 |
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1063 tty->print_cr("page_trap_count"); |
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1064 } |
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1065 |
0 | 1066 void SafepointSynchronize::deferred_initialize_stat() { |
1067 if (init_done) return; | |
1068 | |
1069 if (PrintSafepointStatisticsCount <= 0) { | |
1070 fatal("Wrong PrintSafepointStatisticsCount"); | |
1071 } | |
1072 | |
1073 // If PrintSafepointStatisticsTimeout is specified, the statistics data will | |
1074 // be printed right away, in which case, _safepoint_stats will regress to | |
1075 // a single element array. Otherwise, it is a circular ring buffer with default | |
1076 // size of PrintSafepointStatisticsCount. | |
1077 int stats_array_size; | |
1078 if (PrintSafepointStatisticsTimeout > 0) { | |
1079 stats_array_size = 1; | |
1080 PrintSafepointStatistics = true; | |
1081 } else { | |
1082 stats_array_size = PrintSafepointStatisticsCount; | |
1083 } | |
1084 _safepoint_stats = (SafepointStats*)os::malloc(stats_array_size | |
1085 * sizeof(SafepointStats)); | |
1086 guarantee(_safepoint_stats != NULL, | |
1087 "not enough memory for safepoint instrumentation data"); | |
1088 | |
1089 if (UseCompilerSafepoints && DeferPollingPageLoopCount >= 0) { | |
1090 need_to_track_page_armed_status = true; | |
1091 } | |
1092 init_done = true; | |
1093 } | |
1094 | |
1095 void SafepointSynchronize::begin_statistics(int nof_threads, int nof_running) { | |
1003 | 1096 assert(init_done, "safepoint statistics array hasn't been initialized"); |
0 | 1097 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; |
1098 | |
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1099 spstat->_time_stamp = _ts_of_current_safepoint; |
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1100 |
0 | 1101 VM_Operation *op = VMThread::vm_operation(); |
1102 spstat->_vmop_type = (op != NULL ? op->type() : -1); | |
1103 if (op != NULL) { | |
1104 _safepoint_reasons[spstat->_vmop_type]++; | |
1105 } | |
1106 | |
1107 spstat->_nof_total_threads = nof_threads; | |
1108 spstat->_nof_initial_running_threads = nof_running; | |
1109 spstat->_nof_threads_hit_page_trap = 0; | |
1110 | |
1111 // Records the start time of spinning. The real time spent on spinning | |
1112 // will be adjusted when spin is done. Same trick is applied for time | |
1113 // spent on waiting for threads to block. | |
1114 if (nof_running != 0) { | |
1115 spstat->_time_to_spin = os::javaTimeNanos(); | |
1116 } else { | |
1117 spstat->_time_to_spin = 0; | |
1118 } | |
1119 } | |
1120 | |
1121 void SafepointSynchronize::update_statistics_on_spin_end() { | |
1122 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; | |
1123 | |
1124 jlong cur_time = os::javaTimeNanos(); | |
1125 | |
1126 spstat->_nof_threads_wait_to_block = _waiting_to_block; | |
1127 if (spstat->_nof_initial_running_threads != 0) { | |
1128 spstat->_time_to_spin = cur_time - spstat->_time_to_spin; | |
1129 } | |
1130 | |
1131 if (need_to_track_page_armed_status) { | |
1132 spstat->_page_armed = (PageArmed == 1); | |
1133 } | |
1134 | |
1135 // Records the start time of waiting for to block. Updated when block is done. | |
1136 if (_waiting_to_block != 0) { | |
1137 spstat->_time_to_wait_to_block = cur_time; | |
1138 } else { | |
1139 spstat->_time_to_wait_to_block = 0; | |
1140 } | |
1141 } | |
1142 | |
1143 void SafepointSynchronize::update_statistics_on_sync_end(jlong end_time) { | |
1144 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; | |
1145 | |
1146 if (spstat->_nof_threads_wait_to_block != 0) { | |
1147 spstat->_time_to_wait_to_block = end_time - | |
1148 spstat->_time_to_wait_to_block; | |
1149 } | |
1150 | |
1151 // Records the end time of sync which will be used to calculate the total | |
1152 // vm operation time. Again, the real time spending in syncing will be deducted | |
1153 // from the start of the sync time later when end_statistics is called. | |
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1154 spstat->_time_to_sync = end_time - _safepoint_begin_time; |
0 | 1155 if (spstat->_time_to_sync > _max_sync_time) { |
1156 _max_sync_time = spstat->_time_to_sync; | |
1157 } | |
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1158 |
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1159 spstat->_time_to_do_cleanups = end_time; |
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1160 } |
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1161 |
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1162 void SafepointSynchronize::update_statistics_on_cleanup_end(jlong end_time) { |
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1163 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; |
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1164 |
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1165 // Record how long spent in cleanup tasks. |
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1166 spstat->_time_to_do_cleanups = end_time - spstat->_time_to_do_cleanups; |
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1167 |
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1168 cleanup_end_time = end_time; |
0 | 1169 } |
1170 | |
1171 void SafepointSynchronize::end_statistics(jlong vmop_end_time) { | |
1172 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; | |
1173 | |
1174 // Update the vm operation time. | |
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1175 spstat->_time_to_exec_vmop = vmop_end_time - cleanup_end_time; |
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1176 if (spstat->_time_to_exec_vmop > _max_vmop_time) { |
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1177 _max_vmop_time = spstat->_time_to_exec_vmop; |
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1178 } |
0 | 1179 // Only the sync time longer than the specified |
1180 // PrintSafepointStatisticsTimeout will be printed out right away. | |
1181 // By default, it is -1 meaning all samples will be put into the list. | |
1182 if ( PrintSafepointStatisticsTimeout > 0) { | |
1183 if (spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) { | |
1184 print_statistics(); | |
1185 } | |
1186 } else { | |
1187 // The safepoint statistics will be printed out when the _safepoin_stats | |
1188 // array fills up. | |
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1189 if (_cur_stat_index == PrintSafepointStatisticsCount - 1) { |
0 | 1190 print_statistics(); |
1191 _cur_stat_index = 0; | |
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1192 } else { |
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1193 _cur_stat_index++; |
0 | 1194 } |
1195 } | |
1196 } | |
1197 | |
1198 void SafepointSynchronize::print_statistics() { | |
1199 SafepointStats* sstats = _safepoint_stats; | |
1200 | |
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1201 for (int index = 0; index <= _cur_stat_index; index++) { |
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1202 if (index % 30 == 0) { |
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1203 print_header(); |
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1204 } |
0 | 1205 sstats = &_safepoint_stats[index]; |
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1206 tty->print("%.3f: ", sstats->_time_stamp); |
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1207 tty->print("%-26s [" |
0 | 1208 INT32_FORMAT_W(8)INT32_FORMAT_W(11)INT32_FORMAT_W(15) |
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1209 " ] ", |
0 | 1210 sstats->_vmop_type == -1 ? "no vm operation" : |
1211 VM_Operation::name(sstats->_vmop_type), | |
1212 sstats->_nof_total_threads, | |
1213 sstats->_nof_initial_running_threads, | |
1214 sstats->_nof_threads_wait_to_block); | |
1215 // "/ MICROUNITS " is to convert the unit from nanos to millis. | |
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1216 tty->print(" [" |
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1217 INT64_FORMAT_W(6)INT64_FORMAT_W(6) |
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1218 INT64_FORMAT_W(6)INT64_FORMAT_W(6) |
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1219 INT64_FORMAT_W(6)" ] ", |
0 | 1220 sstats->_time_to_spin / MICROUNITS, |
1221 sstats->_time_to_wait_to_block / MICROUNITS, | |
1222 sstats->_time_to_sync / MICROUNITS, | |
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1223 sstats->_time_to_do_cleanups / MICROUNITS, |
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1224 sstats->_time_to_exec_vmop / MICROUNITS); |
0 | 1225 |
1226 if (need_to_track_page_armed_status) { | |
1227 tty->print(INT32_FORMAT" ", sstats->_page_armed); | |
1228 } | |
1229 tty->print_cr(INT32_FORMAT" ", sstats->_nof_threads_hit_page_trap); | |
1230 } | |
1231 } | |
1232 | |
1233 // This method will be called when VM exits. It will first call | |
1234 // print_statistics to print out the rest of the sampling. Then | |
1235 // it tries to summarize the sampling. | |
1236 void SafepointSynchronize::print_stat_on_exit() { | |
1237 if (_safepoint_stats == NULL) return; | |
1238 | |
1239 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; | |
1240 | |
1241 // During VM exit, end_statistics may not get called and in that | |
1242 // case, if the sync time is less than PrintSafepointStatisticsTimeout, | |
1243 // don't print it out. | |
1244 // Approximate the vm op time. | |
1245 _safepoint_stats[_cur_stat_index]._time_to_exec_vmop = | |
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6933402: RFE: Improve PrintSafepointStatistics output to track cleanup time
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diff
changeset
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1246 os::javaTimeNanos() - cleanup_end_time; |
0 | 1247 |
1248 if ( PrintSafepointStatisticsTimeout < 0 || | |
1249 spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) { | |
1250 print_statistics(); | |
1251 } | |
1252 tty->print_cr(""); | |
1253 | |
1254 // Print out polling page sampling status. | |
1255 if (!need_to_track_page_armed_status) { | |
1256 if (UseCompilerSafepoints) { | |
1257 tty->print_cr("Polling page always armed"); | |
1258 } | |
1259 } else { | |
1260 tty->print_cr("Defer polling page loop count = %d\n", | |
1261 DeferPollingPageLoopCount); | |
1262 } | |
1263 | |
1264 for (int index = 0; index < VM_Operation::VMOp_Terminating; index++) { | |
1265 if (_safepoint_reasons[index] != 0) { | |
1266 tty->print_cr("%-26s"UINT64_FORMAT_W(10), VM_Operation::name(index), | |
1267 _safepoint_reasons[index]); | |
1268 } | |
1269 } | |
1270 | |
1271 tty->print_cr(UINT64_FORMAT_W(5)" VM operations coalesced during safepoint", | |
1272 _coalesced_vmop_count); | |
1273 tty->print_cr("Maximum sync time "INT64_FORMAT_W(5)" ms", | |
1274 _max_sync_time / MICROUNITS); | |
1291
4b0f2f4918ed
6933402: RFE: Improve PrintSafepointStatistics output to track cleanup time
xlu
parents:
1003
diff
changeset
|
1275 tty->print_cr("Maximum vm operation time (except for Exit VM operation) " |
4b0f2f4918ed
6933402: RFE: Improve PrintSafepointStatistics output to track cleanup time
xlu
parents:
1003
diff
changeset
|
1276 INT64_FORMAT_W(5)" ms", |
4b0f2f4918ed
6933402: RFE: Improve PrintSafepointStatistics output to track cleanup time
xlu
parents:
1003
diff
changeset
|
1277 _max_vmop_time / MICROUNITS); |
0 | 1278 } |
1279 | |
1280 // ------------------------------------------------------------------------------------------------ | |
1281 // Non-product code | |
1282 | |
1283 #ifndef PRODUCT | |
1284 | |
1285 void SafepointSynchronize::print_state() { | |
1286 if (_state == _not_synchronized) { | |
1287 tty->print_cr("not synchronized"); | |
1288 } else if (_state == _synchronizing || _state == _synchronized) { | |
1289 tty->print_cr("State: %s", (_state == _synchronizing) ? "synchronizing" : | |
1290 "synchronized"); | |
1291 | |
1292 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) { | |
1293 cur->safepoint_state()->print(); | |
1294 } | |
1295 } | |
1296 } | |
1297 | |
1298 void SafepointSynchronize::safepoint_msg(const char* format, ...) { | |
1299 if (ShowSafepointMsgs) { | |
1300 va_list ap; | |
1301 va_start(ap, format); | |
1302 tty->vprint_cr(format, ap); | |
1303 va_end(ap); | |
1304 } | |
1305 } | |
1306 | |
1307 #endif // !PRODUCT |