Mercurial > hg > truffle
annotate src/share/vm/runtime/safepoint.cpp @ 1917:f42a2f0c16bb
6996563: 6984311 changes forgot to update vmStructs.cpp for new field _operands
Summary: Add missing line to vmStructs. Also fix bug with class dumper.
Reviewed-by: twisti, kvn
author | jrose |
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date | Fri, 05 Nov 2010 12:18:30 -0700 |
parents | ce6848d0666d |
children | f95d63e2154a |
rev | line source |
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0 | 1 /* |
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2 * Copyright (c) 1997, 2009, 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 | |
25 # include "incls/_precompiled.incl" | |
26 # include "incls/_safepoint.cpp.incl" | |
27 | |
28 // -------------------------------------------------------------------------------------------------- | |
29 // Implementation of Safepoint begin/end | |
30 | |
31 SafepointSynchronize::SynchronizeState volatile SafepointSynchronize::_state = SafepointSynchronize::_not_synchronized; | |
32 volatile int SafepointSynchronize::_waiting_to_block = 0; | |
33 volatile int SafepointSynchronize::_safepoint_counter = 0; | |
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34 long SafepointSynchronize::_end_of_last_safepoint = 0; |
0 | 35 static volatile int PageArmed = 0 ; // safepoint polling page is RO|RW vs PROT_NONE |
36 static volatile int TryingToBlock = 0 ; // proximate value -- for advisory use only | |
37 static bool timeout_error_printed = false; | |
38 | |
39 // Roll all threads forward to a safepoint and suspend them all | |
40 void SafepointSynchronize::begin() { | |
41 | |
42 Thread* myThread = Thread::current(); | |
43 assert(myThread->is_VM_thread(), "Only VM thread may execute a safepoint"); | |
44 | |
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45 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) { |
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46 _safepoint_begin_time = os::javaTimeNanos(); |
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47 _ts_of_current_safepoint = tty->time_stamp().seconds(); |
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48 } |
0 | 49 |
50 #ifndef SERIALGC | |
51 if (UseConcMarkSweepGC) { | |
52 // In the future we should investigate whether CMS can use the | |
53 // more-general mechanism below. DLD (01/05). | |
54 ConcurrentMarkSweepThread::synchronize(false); | |
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55 } else if (UseG1GC) { |
0 | 56 ConcurrentGCThread::safepoint_synchronize(); |
57 } | |
58 #endif // SERIALGC | |
59 | |
60 // By getting the Threads_lock, we assure that no threads are about to start or | |
61 // exit. It is released again in SafepointSynchronize::end(). | |
62 Threads_lock->lock(); | |
63 | |
64 assert( _state == _not_synchronized, "trying to safepoint synchronize with wrong state"); | |
65 | |
66 int nof_threads = Threads::number_of_threads(); | |
67 | |
68 if (TraceSafepoint) { | |
69 tty->print_cr("Safepoint synchronization initiated. (%d)", nof_threads); | |
70 } | |
71 | |
72 RuntimeService::record_safepoint_begin(); | |
73 | |
74 { | |
75 MutexLocker mu(Safepoint_lock); | |
76 | |
77 // Set number of threads to wait for, before we initiate the callbacks | |
78 _waiting_to_block = nof_threads; | |
79 TryingToBlock = 0 ; | |
80 int still_running = nof_threads; | |
81 | |
82 // Save the starting time, so that it can be compared to see if this has taken | |
83 // too long to complete. | |
84 jlong safepoint_limit_time; | |
85 timeout_error_printed = false; | |
86 | |
1003 | 87 // PrintSafepointStatisticsTimeout can be specified separately. When |
88 // specified, PrintSafepointStatistics will be set to true in | |
89 // deferred_initialize_stat method. The initialization has to be done | |
90 // early enough to avoid any races. See bug 6880029 for details. | |
91 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) { | |
92 deferred_initialize_stat(); | |
93 } | |
94 | |
0 | 95 // Begin the process of bringing the system to a safepoint. |
96 // Java threads can be in several different states and are | |
97 // stopped by different mechanisms: | |
98 // | |
99 // 1. Running interpreted | |
100 // The interpeter dispatch table is changed to force it to | |
101 // check for a safepoint condition between bytecodes. | |
102 // 2. Running in native code | |
103 // When returning from the native code, a Java thread must check | |
104 // the safepoint _state to see if we must block. If the | |
105 // VM thread sees a Java thread in native, it does | |
106 // not wait for this thread to block. The order of the memory | |
107 // writes and reads of both the safepoint state and the Java | |
108 // threads state is critical. In order to guarantee that the | |
109 // memory writes are serialized with respect to each other, | |
110 // the VM thread issues a memory barrier instruction | |
111 // (on MP systems). In order to avoid the overhead of issuing | |
112 // a memory barrier for each Java thread making native calls, each Java | |
113 // thread performs a write to a single memory page after changing | |
114 // the thread state. The VM thread performs a sequence of | |
115 // mprotect OS calls which forces all previous writes from all | |
116 // Java threads to be serialized. This is done in the | |
117 // os::serialize_thread_states() call. This has proven to be | |
118 // much more efficient than executing a membar instruction | |
119 // on every call to native code. | |
120 // 3. Running compiled Code | |
121 // Compiled code reads a global (Safepoint Polling) page that | |
122 // is set to fault if we are trying to get to a safepoint. | |
123 // 4. Blocked | |
124 // A thread which is blocked will not be allowed to return from the | |
125 // block condition until the safepoint operation is complete. | |
126 // 5. In VM or Transitioning between states | |
127 // If a Java thread is currently running in the VM or transitioning | |
128 // between states, the safepointing code will wait for the thread to | |
129 // block itself when it attempts transitions to a new state. | |
130 // | |
131 _state = _synchronizing; | |
132 OrderAccess::fence(); | |
133 | |
134 // Flush all thread states to memory | |
135 if (!UseMembar) { | |
136 os::serialize_thread_states(); | |
137 } | |
138 | |
139 // Make interpreter safepoint aware | |
140 Interpreter::notice_safepoints(); | |
141 | |
142 if (UseCompilerSafepoints && DeferPollingPageLoopCount < 0) { | |
143 // Make polling safepoint aware | |
144 guarantee (PageArmed == 0, "invariant") ; | |
145 PageArmed = 1 ; | |
146 os::make_polling_page_unreadable(); | |
147 } | |
148 | |
149 // Consider using active_processor_count() ... but that call is expensive. | |
150 int ncpus = os::processor_count() ; | |
151 | |
152 #ifdef ASSERT | |
153 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) { | |
154 assert(cur->safepoint_state()->is_running(), "Illegal initial state"); | |
155 } | |
156 #endif // ASSERT | |
157 | |
158 if (SafepointTimeout) | |
159 safepoint_limit_time = os::javaTimeNanos() + (jlong)SafepointTimeoutDelay * MICROUNITS; | |
160 | |
161 // Iterate through all threads until it have been determined how to stop them all at a safepoint | |
162 unsigned int iterations = 0; | |
163 int steps = 0 ; | |
164 while(still_running > 0) { | |
165 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) { | |
166 assert(!cur->is_ConcurrentGC_thread(), "A concurrent GC thread is unexpectly being suspended"); | |
167 ThreadSafepointState *cur_state = cur->safepoint_state(); | |
168 if (cur_state->is_running()) { | |
169 cur_state->examine_state_of_thread(); | |
170 if (!cur_state->is_running()) { | |
171 still_running--; | |
172 // consider adjusting steps downward: | |
173 // steps = 0 | |
174 // steps -= NNN | |
175 // steps >>= 1 | |
176 // steps = MIN(steps, 2000-100) | |
177 // if (iterations != 0) steps -= NNN | |
178 } | |
179 if (TraceSafepoint && Verbose) cur_state->print(); | |
180 } | |
181 } | |
182 | |
1003 | 183 if (PrintSafepointStatistics && iterations == 0) { |
0 | 184 begin_statistics(nof_threads, still_running); |
185 } | |
186 | |
187 if (still_running > 0) { | |
188 // Check for if it takes to long | |
189 if (SafepointTimeout && safepoint_limit_time < os::javaTimeNanos()) { | |
190 print_safepoint_timeout(_spinning_timeout); | |
191 } | |
192 | |
193 // Spin to avoid context switching. | |
194 // There's a tension between allowing the mutators to run (and rendezvous) | |
195 // vs spinning. As the VM thread spins, wasting cycles, it consumes CPU that | |
196 // a mutator might otherwise use profitably to reach a safepoint. Excessive | |
197 // spinning by the VM thread on a saturated system can increase rendezvous latency. | |
198 // Blocking or yielding incur their own penalties in the form of context switching | |
199 // and the resultant loss of $ residency. | |
200 // | |
201 // Further complicating matters is that yield() does not work as naively expected | |
202 // on many platforms -- yield() does not guarantee that any other ready threads | |
203 // will run. As such we revert yield_all() after some number of iterations. | |
204 // Yield_all() is implemented as a short unconditional sleep on some platforms. | |
205 // Typical operating systems round a "short" sleep period up to 10 msecs, so sleeping | |
206 // can actually increase the time it takes the VM thread to detect that a system-wide | |
207 // stop-the-world safepoint has been reached. In a pathological scenario such as that | |
208 // described in CR6415670 the VMthread may sleep just before the mutator(s) become safe. | |
209 // In that case the mutators will be stalled waiting for the safepoint to complete and the | |
210 // the VMthread will be sleeping, waiting for the mutators to rendezvous. The VMthread | |
211 // will eventually wake up and detect that all mutators are safe, at which point | |
212 // we'll again make progress. | |
213 // | |
214 // Beware too that that the VMThread typically runs at elevated priority. | |
215 // Its default priority is higher than the default mutator priority. | |
216 // Obviously, this complicates spinning. | |
217 // | |
218 // Note too that on Windows XP SwitchThreadTo() has quite different behavior than Sleep(0). | |
219 // Sleep(0) will _not yield to lower priority threads, while SwitchThreadTo() will. | |
220 // | |
221 // See the comments in synchronizer.cpp for additional remarks on spinning. | |
222 // | |
223 // In the future we might: | |
224 // 1. Modify the safepoint scheme to avoid potentally unbounded spinning. | |
225 // This is tricky as the path used by a thread exiting the JVM (say on | |
226 // on JNI call-out) simply stores into its state field. The burden | |
227 // is placed on the VM thread, which must poll (spin). | |
228 // 2. Find something useful to do while spinning. If the safepoint is GC-related | |
229 // we might aggressively scan the stacks of threads that are already safe. | |
230 // 3. Use Solaris schedctl to examine the state of the still-running mutators. | |
231 // If all the mutators are ONPROC there's no reason to sleep or yield. | |
232 // 4. YieldTo() any still-running mutators that are ready but OFFPROC. | |
233 // 5. Check system saturation. If the system is not fully saturated then | |
234 // simply spin and avoid sleep/yield. | |
235 // 6. As still-running mutators rendezvous they could unpark the sleeping | |
236 // VMthread. This works well for still-running mutators that become | |
237 // safe. The VMthread must still poll for mutators that call-out. | |
238 // 7. Drive the policy on time-since-begin instead of iterations. | |
239 // 8. Consider making the spin duration a function of the # of CPUs: | |
240 // Spin = (((ncpus-1) * M) + K) + F(still_running) | |
241 // Alternately, instead of counting iterations of the outer loop | |
242 // we could count the # of threads visited in the inner loop, above. | |
243 // 9. On windows consider using the return value from SwitchThreadTo() | |
244 // to drive subsequent spin/SwitchThreadTo()/Sleep(N) decisions. | |
245 | |
246 if (UseCompilerSafepoints && int(iterations) == DeferPollingPageLoopCount) { | |
247 guarantee (PageArmed == 0, "invariant") ; | |
248 PageArmed = 1 ; | |
249 os::make_polling_page_unreadable(); | |
250 } | |
251 | |
252 // Instead of (ncpus > 1) consider either (still_running < (ncpus + EPSILON)) or | |
253 // ((still_running + _waiting_to_block - TryingToBlock)) < ncpus) | |
254 ++steps ; | |
255 if (ncpus > 1 && steps < SafepointSpinBeforeYield) { | |
256 SpinPause() ; // MP-Polite spin | |
257 } else | |
258 if (steps < DeferThrSuspendLoopCount) { | |
259 os::NakedYield() ; | |
260 } else { | |
261 os::yield_all(steps) ; | |
262 // Alternately, the VM thread could transiently depress its scheduling priority or | |
263 // transiently increase the priority of the tardy mutator(s). | |
264 } | |
265 | |
266 iterations ++ ; | |
267 } | |
268 assert(iterations < (uint)max_jint, "We have been iterating in the safepoint loop too long"); | |
269 } | |
270 assert(still_running == 0, "sanity check"); | |
271 | |
272 if (PrintSafepointStatistics) { | |
273 update_statistics_on_spin_end(); | |
274 } | |
275 | |
276 // wait until all threads are stopped | |
277 while (_waiting_to_block > 0) { | |
278 if (TraceSafepoint) tty->print_cr("Waiting for %d thread(s) to block", _waiting_to_block); | |
279 if (!SafepointTimeout || timeout_error_printed) { | |
280 Safepoint_lock->wait(true); // true, means with no safepoint checks | |
281 } else { | |
282 // Compute remaining time | |
283 jlong remaining_time = safepoint_limit_time - os::javaTimeNanos(); | |
284 | |
285 // If there is no remaining time, then there is an error | |
286 if (remaining_time < 0 || Safepoint_lock->wait(true, remaining_time / MICROUNITS)) { | |
287 print_safepoint_timeout(_blocking_timeout); | |
288 } | |
289 } | |
290 } | |
291 assert(_waiting_to_block == 0, "sanity check"); | |
292 | |
293 #ifndef PRODUCT | |
294 if (SafepointTimeout) { | |
295 jlong current_time = os::javaTimeNanos(); | |
296 if (safepoint_limit_time < current_time) { | |
297 tty->print_cr("# SafepointSynchronize: Finished after " | |
298 INT64_FORMAT_W(6) " ms", | |
299 ((current_time - safepoint_limit_time) / MICROUNITS + | |
300 SafepointTimeoutDelay)); | |
301 } | |
302 } | |
303 #endif | |
304 | |
305 assert((_safepoint_counter & 0x1) == 0, "must be even"); | |
306 assert(Threads_lock->owned_by_self(), "must hold Threads_lock"); | |
307 _safepoint_counter ++; | |
308 | |
309 // Record state | |
310 _state = _synchronized; | |
311 | |
312 OrderAccess::fence(); | |
313 | |
314 if (TraceSafepoint) { | |
315 VM_Operation *op = VMThread::vm_operation(); | |
316 tty->print_cr("Entering safepoint region: %s", (op != NULL) ? op->name() : "no vm operation"); | |
317 } | |
318 | |
319 RuntimeService::record_safepoint_synchronized(); | |
320 if (PrintSafepointStatistics) { | |
321 update_statistics_on_sync_end(os::javaTimeNanos()); | |
322 } | |
323 | |
324 // Call stuff that needs to be run when a safepoint is just about to be completed | |
325 do_cleanup_tasks(); | |
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326 |
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327 if (PrintSafepointStatistics) { |
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328 // Record how much time spend on the above cleanup tasks |
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329 update_statistics_on_cleanup_end(os::javaTimeNanos()); |
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330 } |
0 | 331 } |
332 } | |
333 | |
334 // Wake up all threads, so they are ready to resume execution after the safepoint | |
335 // operation has been carried out | |
336 void SafepointSynchronize::end() { | |
337 | |
338 assert(Threads_lock->owned_by_self(), "must hold Threads_lock"); | |
339 assert((_safepoint_counter & 0x1) == 1, "must be odd"); | |
340 _safepoint_counter ++; | |
341 // memory fence isn't required here since an odd _safepoint_counter | |
342 // value can do no harm and a fence is issued below anyway. | |
343 | |
344 DEBUG_ONLY(Thread* myThread = Thread::current();) | |
345 assert(myThread->is_VM_thread(), "Only VM thread can execute a safepoint"); | |
346 | |
347 if (PrintSafepointStatistics) { | |
348 end_statistics(os::javaTimeNanos()); | |
349 } | |
350 | |
351 #ifdef ASSERT | |
352 // A pending_exception cannot be installed during a safepoint. The threads | |
353 // may install an async exception after they come back from a safepoint into | |
354 // pending_exception after they unblock. But that should happen later. | |
355 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) { | |
356 assert (!(cur->has_pending_exception() && | |
357 cur->safepoint_state()->is_at_poll_safepoint()), | |
358 "safepoint installed a pending exception"); | |
359 } | |
360 #endif // ASSERT | |
361 | |
362 if (PageArmed) { | |
363 // Make polling safepoint aware | |
364 os::make_polling_page_readable(); | |
365 PageArmed = 0 ; | |
366 } | |
367 | |
368 // Remove safepoint check from interpreter | |
369 Interpreter::ignore_safepoints(); | |
370 | |
371 { | |
372 MutexLocker mu(Safepoint_lock); | |
373 | |
374 assert(_state == _synchronized, "must be synchronized before ending safepoint synchronization"); | |
375 | |
376 // Set to not synchronized, so the threads will not go into the signal_thread_blocked method | |
377 // when they get restarted. | |
378 _state = _not_synchronized; | |
379 OrderAccess::fence(); | |
380 | |
381 if (TraceSafepoint) { | |
382 tty->print_cr("Leaving safepoint region"); | |
383 } | |
384 | |
385 // Start suspended threads | |
386 for(JavaThread *current = Threads::first(); current; current = current->next()) { | |
605 | 387 // A problem occurring on Solaris is when attempting to restart threads |
0 | 388 // the first #cpus - 1 go well, but then the VMThread is preempted when we get |
389 // to the next one (since it has been running the longest). We then have | |
390 // to wait for a cpu to become available before we can continue restarting | |
391 // threads. | |
392 // FIXME: This causes the performance of the VM to degrade when active and with | |
393 // large numbers of threads. Apparently this is due to the synchronous nature | |
394 // of suspending threads. | |
395 // | |
396 // TODO-FIXME: the comments above are vestigial and no longer apply. | |
397 // Furthermore, using solaris' schedctl in this particular context confers no benefit | |
398 if (VMThreadHintNoPreempt) { | |
399 os::hint_no_preempt(); | |
400 } | |
401 ThreadSafepointState* cur_state = current->safepoint_state(); | |
402 assert(cur_state->type() != ThreadSafepointState::_running, "Thread not suspended at safepoint"); | |
403 cur_state->restart(); | |
404 assert(cur_state->is_running(), "safepoint state has not been reset"); | |
405 } | |
406 | |
407 RuntimeService::record_safepoint_end(); | |
408 | |
409 // Release threads lock, so threads can be created/destroyed again. It will also starts all threads | |
410 // blocked in signal_thread_blocked | |
411 Threads_lock->unlock(); | |
412 | |
413 } | |
414 #ifndef SERIALGC | |
415 // If there are any concurrent GC threads resume them. | |
416 if (UseConcMarkSweepGC) { | |
417 ConcurrentMarkSweepThread::desynchronize(false); | |
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418 } else if (UseG1GC) { |
0 | 419 ConcurrentGCThread::safepoint_desynchronize(); |
420 } | |
421 #endif // SERIALGC | |
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422 // record this time so VMThread can keep track how much time has elasped |
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423 // since last safepoint. |
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424 _end_of_last_safepoint = os::javaTimeMillis(); |
0 | 425 } |
426 | |
427 bool SafepointSynchronize::is_cleanup_needed() { | |
428 // Need a safepoint if some inline cache buffers is non-empty | |
429 if (!InlineCacheBuffer::is_empty()) return true; | |
430 return false; | |
431 } | |
432 | |
433 | |
434 | |
435 // Various cleaning tasks that should be done periodically at safepoints | |
436 void SafepointSynchronize::do_cleanup_tasks() { | |
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437 { |
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438 TraceTime t1("deflating idle monitors", TraceSafepointCleanupTime); |
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439 ObjectSynchronizer::deflate_idle_monitors(); |
0 | 440 } |
441 | |
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442 { |
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443 TraceTime t2("updating inline caches", TraceSafepointCleanupTime); |
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444 InlineCacheBuffer::update_inline_caches(); |
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445 } |
1783 | 446 { |
447 TraceTime t3("compilation policy safepoint handler", TraceSafepointCleanupTime); | |
448 CompilationPolicy::policy()->do_safepoint_work(); | |
0 | 449 } |
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450 |
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451 TraceTime t4("sweeping nmethods", TraceSafepointCleanupTime); |
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452 NMethodSweeper::scan_stacks(); |
0 | 453 } |
454 | |
455 | |
456 bool SafepointSynchronize::safepoint_safe(JavaThread *thread, JavaThreadState state) { | |
457 switch(state) { | |
458 case _thread_in_native: | |
459 // native threads are safe if they have no java stack or have walkable stack | |
460 return !thread->has_last_Java_frame() || thread->frame_anchor()->walkable(); | |
461 | |
462 // blocked threads should have already have walkable stack | |
463 case _thread_blocked: | |
464 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "blocked and not walkable"); | |
465 return true; | |
466 | |
467 default: | |
468 return false; | |
469 } | |
470 } | |
471 | |
472 | |
473 // ------------------------------------------------------------------------------------------------------- | |
474 // Implementation of Safepoint callback point | |
475 | |
476 void SafepointSynchronize::block(JavaThread *thread) { | |
477 assert(thread != NULL, "thread must be set"); | |
478 assert(thread->is_Java_thread(), "not a Java thread"); | |
479 | |
480 // Threads shouldn't block if they are in the middle of printing, but... | |
481 ttyLocker::break_tty_lock_for_safepoint(os::current_thread_id()); | |
482 | |
483 // Only bail from the block() call if the thread is gone from the | |
484 // thread list; starting to exit should still block. | |
485 if (thread->is_terminated()) { | |
486 // block current thread if we come here from native code when VM is gone | |
487 thread->block_if_vm_exited(); | |
488 | |
489 // otherwise do nothing | |
490 return; | |
491 } | |
492 | |
493 JavaThreadState state = thread->thread_state(); | |
494 thread->frame_anchor()->make_walkable(thread); | |
495 | |
496 // Check that we have a valid thread_state at this point | |
497 switch(state) { | |
498 case _thread_in_vm_trans: | |
499 case _thread_in_Java: // From compiled code | |
500 | |
501 // We are highly likely to block on the Safepoint_lock. In order to avoid blocking in this case, | |
502 // we pretend we are still in the VM. | |
503 thread->set_thread_state(_thread_in_vm); | |
504 | |
505 if (is_synchronizing()) { | |
506 Atomic::inc (&TryingToBlock) ; | |
507 } | |
508 | |
509 // We will always be holding the Safepoint_lock when we are examine the state | |
510 // of a thread. Hence, the instructions between the Safepoint_lock->lock() and | |
511 // Safepoint_lock->unlock() are happening atomic with regards to the safepoint code | |
512 Safepoint_lock->lock_without_safepoint_check(); | |
513 if (is_synchronizing()) { | |
514 // Decrement the number of threads to wait for and signal vm thread | |
515 assert(_waiting_to_block > 0, "sanity check"); | |
516 _waiting_to_block--; | |
517 thread->safepoint_state()->set_has_called_back(true); | |
518 | |
519 // Consider (_waiting_to_block < 2) to pipeline the wakeup of the VM thread | |
520 if (_waiting_to_block == 0) { | |
521 Safepoint_lock->notify_all(); | |
522 } | |
523 } | |
524 | |
525 // We transition the thread to state _thread_blocked here, but | |
526 // we can't do our usual check for external suspension and then | |
527 // self-suspend after the lock_without_safepoint_check() call | |
528 // below because we are often called during transitions while | |
529 // we hold different locks. That would leave us suspended while | |
530 // holding a resource which results in deadlocks. | |
531 thread->set_thread_state(_thread_blocked); | |
532 Safepoint_lock->unlock(); | |
533 | |
534 // We now try to acquire the threads lock. Since this lock is hold by the VM thread during | |
535 // the entire safepoint, the threads will all line up here during the safepoint. | |
536 Threads_lock->lock_without_safepoint_check(); | |
537 // restore original state. This is important if the thread comes from compiled code, so it | |
538 // will continue to execute with the _thread_in_Java state. | |
539 thread->set_thread_state(state); | |
540 Threads_lock->unlock(); | |
541 break; | |
542 | |
543 case _thread_in_native_trans: | |
544 case _thread_blocked_trans: | |
545 case _thread_new_trans: | |
546 if (thread->safepoint_state()->type() == ThreadSafepointState::_call_back) { | |
547 thread->print_thread_state(); | |
548 fatal("Deadlock in safepoint code. " | |
549 "Should have called back to the VM before blocking."); | |
550 } | |
551 | |
552 // We transition the thread to state _thread_blocked here, but | |
553 // we can't do our usual check for external suspension and then | |
554 // self-suspend after the lock_without_safepoint_check() call | |
555 // below because we are often called during transitions while | |
556 // we hold different locks. That would leave us suspended while | |
557 // holding a resource which results in deadlocks. | |
558 thread->set_thread_state(_thread_blocked); | |
559 | |
560 // It is not safe to suspend a thread if we discover it is in _thread_in_native_trans. Hence, | |
561 // the safepoint code might still be waiting for it to block. We need to change the state here, | |
562 // so it can see that it is at a safepoint. | |
563 | |
564 // Block until the safepoint operation is completed. | |
565 Threads_lock->lock_without_safepoint_check(); | |
566 | |
567 // Restore state | |
568 thread->set_thread_state(state); | |
569 | |
570 Threads_lock->unlock(); | |
571 break; | |
572 | |
573 default: | |
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574 fatal(err_msg("Illegal threadstate encountered: %d", state)); |
0 | 575 } |
576 | |
577 // Check for pending. async. exceptions or suspends - except if the | |
578 // thread was blocked inside the VM. has_special_runtime_exit_condition() | |
579 // is called last since it grabs a lock and we only want to do that when | |
580 // we must. | |
581 // | |
582 // Note: we never deliver an async exception at a polling point as the | |
583 // compiler may not have an exception handler for it. The polling | |
584 // code will notice the async and deoptimize and the exception will | |
585 // be delivered. (Polling at a return point is ok though). Sure is | |
586 // a lot of bother for a deprecated feature... | |
587 // | |
588 // We don't deliver an async exception if the thread state is | |
589 // _thread_in_native_trans so JNI functions won't be called with | |
590 // a surprising pending exception. If the thread state is going back to java, | |
591 // async exception is checked in check_special_condition_for_native_trans(). | |
592 | |
593 if (state != _thread_blocked_trans && | |
594 state != _thread_in_vm_trans && | |
595 thread->has_special_runtime_exit_condition()) { | |
596 thread->handle_special_runtime_exit_condition( | |
597 !thread->is_at_poll_safepoint() && (state != _thread_in_native_trans)); | |
598 } | |
599 } | |
600 | |
601 // ------------------------------------------------------------------------------------------------------ | |
602 // Exception handlers | |
603 | |
604 #ifndef PRODUCT | |
605 #ifdef _LP64 | |
606 #define PTR_PAD "" | |
607 #else | |
608 #define PTR_PAD " " | |
609 #endif | |
610 | |
611 static void print_ptrs(intptr_t oldptr, intptr_t newptr, bool wasoop) { | |
612 bool is_oop = newptr ? ((oop)newptr)->is_oop() : false; | |
613 tty->print_cr(PTR_FORMAT PTR_PAD " %s %c " PTR_FORMAT PTR_PAD " %s %s", | |
614 oldptr, wasoop?"oop":" ", oldptr == newptr ? ' ' : '!', | |
615 newptr, is_oop?"oop":" ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":" ")); | |
616 } | |
617 | |
618 static void print_longs(jlong oldptr, jlong newptr, bool wasoop) { | |
619 bool is_oop = newptr ? ((oop)(intptr_t)newptr)->is_oop() : false; | |
620 tty->print_cr(PTR64_FORMAT " %s %c " PTR64_FORMAT " %s %s", | |
621 oldptr, wasoop?"oop":" ", oldptr == newptr ? ' ' : '!', | |
622 newptr, is_oop?"oop":" ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":" ")); | |
623 } | |
624 | |
625 #ifdef SPARC | |
626 static void print_me(intptr_t *new_sp, intptr_t *old_sp, bool *was_oops) { | |
627 #ifdef _LP64 | |
628 tty->print_cr("--------+------address-----+------before-----------+-------after----------+"); | |
629 const int incr = 1; // Increment to skip a long, in units of intptr_t | |
630 #else | |
631 tty->print_cr("--------+--address-+------before-----------+-------after----------+"); | |
632 const int incr = 2; // Increment to skip a long, in units of intptr_t | |
633 #endif | |
634 tty->print_cr("---SP---|"); | |
635 for( int i=0; i<16; i++ ) { | |
636 tty->print("blob %c%d |"PTR_FORMAT" ","LO"[i>>3],i&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); } | |
637 tty->print_cr("--------|"); | |
638 for( int i1=0; i1<frame::memory_parameter_word_sp_offset-16; i1++ ) { | |
639 tty->print("argv pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); } | |
640 tty->print(" pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); | |
641 tty->print_cr("--------|"); | |
642 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; | |
643 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; | |
644 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; | |
645 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; | |
646 tty->print_cr(" FSR |"PTR_FORMAT" "PTR64_FORMAT" "PTR64_FORMAT,new_sp,*(jlong*)old_sp,*(jlong*)new_sp); | |
647 old_sp += incr; new_sp += incr; was_oops += incr; | |
648 // Skip the floats | |
649 tty->print_cr("--Float-|"PTR_FORMAT,new_sp); | |
650 tty->print_cr("---FP---|"); | |
651 old_sp += incr*32; new_sp += incr*32; was_oops += incr*32; | |
652 for( int i2=0; i2<16; i2++ ) { | |
653 tty->print("call %c%d |"PTR_FORMAT" ","LI"[i2>>3],i2&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); } | |
654 tty->print_cr(""); | |
655 } | |
656 #endif // SPARC | |
657 #endif // PRODUCT | |
658 | |
659 | |
660 void SafepointSynchronize::handle_polling_page_exception(JavaThread *thread) { | |
661 assert(thread->is_Java_thread(), "polling reference encountered by VM thread"); | |
662 assert(thread->thread_state() == _thread_in_Java, "should come from Java code"); | |
663 assert(SafepointSynchronize::is_synchronizing(), "polling encountered outside safepoint synchronization"); | |
664 | |
665 // Uncomment this to get some serious before/after printing of the | |
666 // Sparc safepoint-blob frame structure. | |
667 /* | |
668 intptr_t* sp = thread->last_Java_sp(); | |
669 intptr_t stack_copy[150]; | |
670 for( int i=0; i<150; i++ ) stack_copy[i] = sp[i]; | |
671 bool was_oops[150]; | |
672 for( int i=0; i<150; i++ ) | |
673 was_oops[i] = stack_copy[i] ? ((oop)stack_copy[i])->is_oop() : false; | |
674 */ | |
675 | |
676 if (ShowSafepointMsgs) { | |
677 tty->print("handle_polling_page_exception: "); | |
678 } | |
679 | |
680 if (PrintSafepointStatistics) { | |
681 inc_page_trap_count(); | |
682 } | |
683 | |
684 ThreadSafepointState* state = thread->safepoint_state(); | |
685 | |
686 state->handle_polling_page_exception(); | |
687 // print_me(sp,stack_copy,was_oops); | |
688 } | |
689 | |
690 | |
691 void SafepointSynchronize::print_safepoint_timeout(SafepointTimeoutReason reason) { | |
692 if (!timeout_error_printed) { | |
693 timeout_error_printed = true; | |
694 // Print out the thread infor which didn't reach the safepoint for debugging | |
695 // purposes (useful when there are lots of threads in the debugger). | |
696 tty->print_cr(""); | |
697 tty->print_cr("# SafepointSynchronize::begin: Timeout detected:"); | |
698 if (reason == _spinning_timeout) { | |
699 tty->print_cr("# SafepointSynchronize::begin: Timed out while spinning to reach a safepoint."); | |
700 } else if (reason == _blocking_timeout) { | |
701 tty->print_cr("# SafepointSynchronize::begin: Timed out while waiting for threads to stop."); | |
702 } | |
703 | |
704 tty->print_cr("# SafepointSynchronize::begin: Threads which did not reach the safepoint:"); | |
705 ThreadSafepointState *cur_state; | |
706 ResourceMark rm; | |
707 for(JavaThread *cur_thread = Threads::first(); cur_thread; | |
708 cur_thread = cur_thread->next()) { | |
709 cur_state = cur_thread->safepoint_state(); | |
710 | |
711 if (cur_thread->thread_state() != _thread_blocked && | |
712 ((reason == _spinning_timeout && cur_state->is_running()) || | |
713 (reason == _blocking_timeout && !cur_state->has_called_back()))) { | |
714 tty->print("# "); | |
715 cur_thread->print(); | |
716 tty->print_cr(""); | |
717 } | |
718 } | |
719 tty->print_cr("# SafepointSynchronize::begin: (End of list)"); | |
720 } | |
721 | |
722 // To debug the long safepoint, specify both DieOnSafepointTimeout & | |
723 // ShowMessageBoxOnError. | |
724 if (DieOnSafepointTimeout) { | |
725 char msg[1024]; | |
726 VM_Operation *op = VMThread::vm_operation(); | |
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727 sprintf(msg, "Safepoint sync time longer than " INTX_FORMAT "ms detected when executing %s.", |
0 | 728 SafepointTimeoutDelay, |
729 op != NULL ? op->name() : "no vm operation"); | |
730 fatal(msg); | |
731 } | |
732 } | |
733 | |
734 | |
735 // ------------------------------------------------------------------------------------------------------- | |
736 // Implementation of ThreadSafepointState | |
737 | |
738 ThreadSafepointState::ThreadSafepointState(JavaThread *thread) { | |
739 _thread = thread; | |
740 _type = _running; | |
741 _has_called_back = false; | |
742 _at_poll_safepoint = false; | |
743 } | |
744 | |
745 void ThreadSafepointState::create(JavaThread *thread) { | |
746 ThreadSafepointState *state = new ThreadSafepointState(thread); | |
747 thread->set_safepoint_state(state); | |
748 } | |
749 | |
750 void ThreadSafepointState::destroy(JavaThread *thread) { | |
751 if (thread->safepoint_state()) { | |
752 delete(thread->safepoint_state()); | |
753 thread->set_safepoint_state(NULL); | |
754 } | |
755 } | |
756 | |
757 void ThreadSafepointState::examine_state_of_thread() { | |
758 assert(is_running(), "better be running or just have hit safepoint poll"); | |
759 | |
760 JavaThreadState state = _thread->thread_state(); | |
761 | |
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762 // Save the state at the start of safepoint processing. |
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763 _orig_thread_state = state; |
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764 |
0 | 765 // Check for a thread that is suspended. Note that thread resume tries |
766 // to grab the Threads_lock which we own here, so a thread cannot be | |
767 // resumed during safepoint synchronization. | |
768 | |
979 | 769 // We check to see if this thread is suspended without locking to |
770 // avoid deadlocking with a third thread that is waiting for this | |
771 // thread to be suspended. The third thread can notice the safepoint | |
772 // that we're trying to start at the beginning of its SR_lock->wait() | |
773 // call. If that happens, then the third thread will block on the | |
774 // safepoint while still holding the underlying SR_lock. We won't be | |
775 // able to get the SR_lock and we'll deadlock. | |
776 // | |
777 // We don't need to grab the SR_lock here for two reasons: | |
778 // 1) The suspend flags are both volatile and are set with an | |
779 // Atomic::cmpxchg() call so we should see the suspended | |
780 // state right away. | |
781 // 2) We're being called from the safepoint polling loop; if | |
782 // we don't see the suspended state on this iteration, then | |
783 // we'll come around again. | |
784 // | |
785 bool is_suspended = _thread->is_ext_suspended(); | |
0 | 786 if (is_suspended) { |
787 roll_forward(_at_safepoint); | |
788 return; | |
789 } | |
790 | |
791 // Some JavaThread states have an initial safepoint state of | |
792 // running, but are actually at a safepoint. We will happily | |
793 // agree and update the safepoint state here. | |
794 if (SafepointSynchronize::safepoint_safe(_thread, state)) { | |
795 roll_forward(_at_safepoint); | |
796 return; | |
797 } | |
798 | |
799 if (state == _thread_in_vm) { | |
800 roll_forward(_call_back); | |
801 return; | |
802 } | |
803 | |
804 // All other thread states will continue to run until they | |
805 // transition and self-block in state _blocked | |
806 // Safepoint polling in compiled code causes the Java threads to do the same. | |
807 // Note: new threads may require a malloc so they must be allowed to finish | |
808 | |
809 assert(is_running(), "examine_state_of_thread on non-running thread"); | |
810 return; | |
811 } | |
812 | |
813 // Returns true is thread could not be rolled forward at present position. | |
814 void ThreadSafepointState::roll_forward(suspend_type type) { | |
815 _type = type; | |
816 | |
817 switch(_type) { | |
818 case _at_safepoint: | |
819 SafepointSynchronize::signal_thread_at_safepoint(); | |
820 break; | |
821 | |
822 case _call_back: | |
823 set_has_called_back(false); | |
824 break; | |
825 | |
826 case _running: | |
827 default: | |
828 ShouldNotReachHere(); | |
829 } | |
830 } | |
831 | |
832 void ThreadSafepointState::restart() { | |
833 switch(type()) { | |
834 case _at_safepoint: | |
835 case _call_back: | |
836 break; | |
837 | |
838 case _running: | |
839 default: | |
840 tty->print_cr("restart thread "INTPTR_FORMAT" with state %d", | |
841 _thread, _type); | |
842 _thread->print(); | |
843 ShouldNotReachHere(); | |
844 } | |
845 _type = _running; | |
846 set_has_called_back(false); | |
847 } | |
848 | |
849 | |
850 void ThreadSafepointState::print_on(outputStream *st) const { | |
851 const char *s; | |
852 | |
853 switch(_type) { | |
854 case _running : s = "_running"; break; | |
855 case _at_safepoint : s = "_at_safepoint"; break; | |
856 case _call_back : s = "_call_back"; break; | |
857 default: | |
858 ShouldNotReachHere(); | |
859 } | |
860 | |
861 st->print_cr("Thread: " INTPTR_FORMAT | |
862 " [0x%2x] State: %s _has_called_back %d _at_poll_safepoint %d", | |
863 _thread, _thread->osthread()->thread_id(), s, _has_called_back, | |
864 _at_poll_safepoint); | |
865 | |
866 _thread->print_thread_state_on(st); | |
867 } | |
868 | |
869 | |
870 // --------------------------------------------------------------------------------------------------------------------- | |
871 | |
872 // Block the thread at the safepoint poll or poll return. | |
873 void ThreadSafepointState::handle_polling_page_exception() { | |
874 | |
875 // Check state. block() will set thread state to thread_in_vm which will | |
876 // cause the safepoint state _type to become _call_back. | |
877 assert(type() == ThreadSafepointState::_running, | |
878 "polling page exception on thread not running state"); | |
879 | |
880 // Step 1: Find the nmethod from the return address | |
881 if (ShowSafepointMsgs && Verbose) { | |
882 tty->print_cr("Polling page exception at " INTPTR_FORMAT, thread()->saved_exception_pc()); | |
883 } | |
884 address real_return_addr = thread()->saved_exception_pc(); | |
885 | |
886 CodeBlob *cb = CodeCache::find_blob(real_return_addr); | |
887 assert(cb != NULL && cb->is_nmethod(), "return address should be in nmethod"); | |
888 nmethod* nm = (nmethod*)cb; | |
889 | |
890 // Find frame of caller | |
891 frame stub_fr = thread()->last_frame(); | |
892 CodeBlob* stub_cb = stub_fr.cb(); | |
893 assert(stub_cb->is_safepoint_stub(), "must be a safepoint stub"); | |
894 RegisterMap map(thread(), true); | |
895 frame caller_fr = stub_fr.sender(&map); | |
896 | |
897 // Should only be poll_return or poll | |
898 assert( nm->is_at_poll_or_poll_return(real_return_addr), "should not be at call" ); | |
899 | |
900 // This is a poll immediately before a return. The exception handling code | |
901 // has already had the effect of causing the return to occur, so the execution | |
902 // will continue immediately after the call. In addition, the oopmap at the | |
903 // return point does not mark the return value as an oop (if it is), so | |
904 // it needs a handle here to be updated. | |
905 if( nm->is_at_poll_return(real_return_addr) ) { | |
906 // See if return type is an oop. | |
907 bool return_oop = nm->method()->is_returning_oop(); | |
908 Handle return_value; | |
909 if (return_oop) { | |
910 // The oop result has been saved on the stack together with all | |
911 // the other registers. In order to preserve it over GCs we need | |
912 // to keep it in a handle. | |
913 oop result = caller_fr.saved_oop_result(&map); | |
914 assert(result == NULL || result->is_oop(), "must be oop"); | |
915 return_value = Handle(thread(), result); | |
916 assert(Universe::heap()->is_in_or_null(result), "must be heap pointer"); | |
917 } | |
918 | |
919 // Block the thread | |
920 SafepointSynchronize::block(thread()); | |
921 | |
922 // restore oop result, if any | |
923 if (return_oop) { | |
924 caller_fr.set_saved_oop_result(&map, return_value()); | |
925 } | |
926 } | |
927 | |
928 // This is a safepoint poll. Verify the return address and block. | |
929 else { | |
930 set_at_poll_safepoint(true); | |
931 | |
932 // verify the blob built the "return address" correctly | |
933 assert(real_return_addr == caller_fr.pc(), "must match"); | |
934 | |
935 // Block the thread | |
936 SafepointSynchronize::block(thread()); | |
937 set_at_poll_safepoint(false); | |
938 | |
939 // If we have a pending async exception deoptimize the frame | |
940 // as otherwise we may never deliver it. | |
941 if (thread()->has_async_condition()) { | |
942 ThreadInVMfromJavaNoAsyncException __tiv(thread()); | |
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943 Deoptimization::deoptimize_frame(thread(), caller_fr.id()); |
0 | 944 } |
945 | |
946 // If an exception has been installed we must check for a pending deoptimization | |
947 // Deoptimize frame if exception has been thrown. | |
948 | |
949 if (thread()->has_pending_exception() ) { | |
950 RegisterMap map(thread(), true); | |
951 frame caller_fr = stub_fr.sender(&map); | |
952 if (caller_fr.is_deoptimized_frame()) { | |
953 // The exception patch will destroy registers that are still | |
954 // live and will be needed during deoptimization. Defer the | |
955 // Async exception should have defered the exception until the | |
956 // next safepoint which will be detected when we get into | |
957 // the interpreter so if we have an exception now things | |
958 // are messed up. | |
959 | |
960 fatal("Exception installed and deoptimization is pending"); | |
961 } | |
962 } | |
963 } | |
964 } | |
965 | |
966 | |
967 // | |
968 // Statistics & Instrumentations | |
969 // | |
970 SafepointSynchronize::SafepointStats* SafepointSynchronize::_safepoint_stats = NULL; | |
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971 jlong SafepointSynchronize::_safepoint_begin_time = 0; |
0 | 972 int SafepointSynchronize::_cur_stat_index = 0; |
973 julong SafepointSynchronize::_safepoint_reasons[VM_Operation::VMOp_Terminating]; | |
974 julong SafepointSynchronize::_coalesced_vmop_count = 0; | |
975 jlong SafepointSynchronize::_max_sync_time = 0; | |
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976 jlong SafepointSynchronize::_max_vmop_time = 0; |
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977 float SafepointSynchronize::_ts_of_current_safepoint = 0.0f; |
0 | 978 |
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979 static jlong cleanup_end_time = 0; |
0 | 980 static bool need_to_track_page_armed_status = false; |
981 static bool init_done = false; | |
982 | |
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983 // Helper method to print the header. |
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984 static void print_header() { |
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985 tty->print(" vmop " |
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986 "[threads: total initially_running wait_to_block] "); |
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987 tty->print("[time: spin block sync cleanup vmop] "); |
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988 |
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989 // no page armed status printed out if it is always armed. |
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990 if (need_to_track_page_armed_status) { |
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991 tty->print("page_armed "); |
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992 } |
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993 |
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994 tty->print_cr("page_trap_count"); |
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995 } |
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996 |
0 | 997 void SafepointSynchronize::deferred_initialize_stat() { |
998 if (init_done) return; | |
999 | |
1000 if (PrintSafepointStatisticsCount <= 0) { | |
1001 fatal("Wrong PrintSafepointStatisticsCount"); | |
1002 } | |
1003 | |
1004 // If PrintSafepointStatisticsTimeout is specified, the statistics data will | |
1005 // be printed right away, in which case, _safepoint_stats will regress to | |
1006 // a single element array. Otherwise, it is a circular ring buffer with default | |
1007 // size of PrintSafepointStatisticsCount. | |
1008 int stats_array_size; | |
1009 if (PrintSafepointStatisticsTimeout > 0) { | |
1010 stats_array_size = 1; | |
1011 PrintSafepointStatistics = true; | |
1012 } else { | |
1013 stats_array_size = PrintSafepointStatisticsCount; | |
1014 } | |
1015 _safepoint_stats = (SafepointStats*)os::malloc(stats_array_size | |
1016 * sizeof(SafepointStats)); | |
1017 guarantee(_safepoint_stats != NULL, | |
1018 "not enough memory for safepoint instrumentation data"); | |
1019 | |
1020 if (UseCompilerSafepoints && DeferPollingPageLoopCount >= 0) { | |
1021 need_to_track_page_armed_status = true; | |
1022 } | |
1023 init_done = true; | |
1024 } | |
1025 | |
1026 void SafepointSynchronize::begin_statistics(int nof_threads, int nof_running) { | |
1003 | 1027 assert(init_done, "safepoint statistics array hasn't been initialized"); |
0 | 1028 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; |
1029 | |
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1030 spstat->_time_stamp = _ts_of_current_safepoint; |
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1031 |
0 | 1032 VM_Operation *op = VMThread::vm_operation(); |
1033 spstat->_vmop_type = (op != NULL ? op->type() : -1); | |
1034 if (op != NULL) { | |
1035 _safepoint_reasons[spstat->_vmop_type]++; | |
1036 } | |
1037 | |
1038 spstat->_nof_total_threads = nof_threads; | |
1039 spstat->_nof_initial_running_threads = nof_running; | |
1040 spstat->_nof_threads_hit_page_trap = 0; | |
1041 | |
1042 // Records the start time of spinning. The real time spent on spinning | |
1043 // will be adjusted when spin is done. Same trick is applied for time | |
1044 // spent on waiting for threads to block. | |
1045 if (nof_running != 0) { | |
1046 spstat->_time_to_spin = os::javaTimeNanos(); | |
1047 } else { | |
1048 spstat->_time_to_spin = 0; | |
1049 } | |
1050 } | |
1051 | |
1052 void SafepointSynchronize::update_statistics_on_spin_end() { | |
1053 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; | |
1054 | |
1055 jlong cur_time = os::javaTimeNanos(); | |
1056 | |
1057 spstat->_nof_threads_wait_to_block = _waiting_to_block; | |
1058 if (spstat->_nof_initial_running_threads != 0) { | |
1059 spstat->_time_to_spin = cur_time - spstat->_time_to_spin; | |
1060 } | |
1061 | |
1062 if (need_to_track_page_armed_status) { | |
1063 spstat->_page_armed = (PageArmed == 1); | |
1064 } | |
1065 | |
1066 // Records the start time of waiting for to block. Updated when block is done. | |
1067 if (_waiting_to_block != 0) { | |
1068 spstat->_time_to_wait_to_block = cur_time; | |
1069 } else { | |
1070 spstat->_time_to_wait_to_block = 0; | |
1071 } | |
1072 } | |
1073 | |
1074 void SafepointSynchronize::update_statistics_on_sync_end(jlong end_time) { | |
1075 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; | |
1076 | |
1077 if (spstat->_nof_threads_wait_to_block != 0) { | |
1078 spstat->_time_to_wait_to_block = end_time - | |
1079 spstat->_time_to_wait_to_block; | |
1080 } | |
1081 | |
1082 // Records the end time of sync which will be used to calculate the total | |
1083 // vm operation time. Again, the real time spending in syncing will be deducted | |
1084 // from the start of the sync time later when end_statistics is called. | |
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1085 spstat->_time_to_sync = end_time - _safepoint_begin_time; |
0 | 1086 if (spstat->_time_to_sync > _max_sync_time) { |
1087 _max_sync_time = spstat->_time_to_sync; | |
1088 } | |
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1089 |
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1090 spstat->_time_to_do_cleanups = end_time; |
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1091 } |
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1092 |
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1093 void SafepointSynchronize::update_statistics_on_cleanup_end(jlong end_time) { |
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1094 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; |
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1095 |
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1096 // Record how long spent in cleanup tasks. |
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1097 spstat->_time_to_do_cleanups = end_time - spstat->_time_to_do_cleanups; |
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1098 |
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1099 cleanup_end_time = end_time; |
0 | 1100 } |
1101 | |
1102 void SafepointSynchronize::end_statistics(jlong vmop_end_time) { | |
1103 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; | |
1104 | |
1105 // Update the vm operation time. | |
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1106 spstat->_time_to_exec_vmop = vmop_end_time - cleanup_end_time; |
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1107 if (spstat->_time_to_exec_vmop > _max_vmop_time) { |
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1108 _max_vmop_time = spstat->_time_to_exec_vmop; |
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1109 } |
0 | 1110 // Only the sync time longer than the specified |
1111 // PrintSafepointStatisticsTimeout will be printed out right away. | |
1112 // By default, it is -1 meaning all samples will be put into the list. | |
1113 if ( PrintSafepointStatisticsTimeout > 0) { | |
1114 if (spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) { | |
1115 print_statistics(); | |
1116 } | |
1117 } else { | |
1118 // The safepoint statistics will be printed out when the _safepoin_stats | |
1119 // array fills up. | |
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1120 if (_cur_stat_index == PrintSafepointStatisticsCount - 1) { |
0 | 1121 print_statistics(); |
1122 _cur_stat_index = 0; | |
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1123 } else { |
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1124 _cur_stat_index++; |
0 | 1125 } |
1126 } | |
1127 } | |
1128 | |
1129 void SafepointSynchronize::print_statistics() { | |
1130 SafepointStats* sstats = _safepoint_stats; | |
1131 | |
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1132 for (int index = 0; index <= _cur_stat_index; index++) { |
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1133 if (index % 30 == 0) { |
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1134 print_header(); |
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1135 } |
0 | 1136 sstats = &_safepoint_stats[index]; |
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1137 tty->print("%.3f: ", sstats->_time_stamp); |
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1138 tty->print("%-26s [" |
0 | 1139 INT32_FORMAT_W(8)INT32_FORMAT_W(11)INT32_FORMAT_W(15) |
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1140 " ] ", |
0 | 1141 sstats->_vmop_type == -1 ? "no vm operation" : |
1142 VM_Operation::name(sstats->_vmop_type), | |
1143 sstats->_nof_total_threads, | |
1144 sstats->_nof_initial_running_threads, | |
1145 sstats->_nof_threads_wait_to_block); | |
1146 // "/ MICROUNITS " is to convert the unit from nanos to millis. | |
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1147 tty->print(" [" |
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1148 INT64_FORMAT_W(6)INT64_FORMAT_W(6) |
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1149 INT64_FORMAT_W(6)INT64_FORMAT_W(6) |
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1150 INT64_FORMAT_W(6)" ] ", |
0 | 1151 sstats->_time_to_spin / MICROUNITS, |
1152 sstats->_time_to_wait_to_block / MICROUNITS, | |
1153 sstats->_time_to_sync / MICROUNITS, | |
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1154 sstats->_time_to_do_cleanups / MICROUNITS, |
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1155 sstats->_time_to_exec_vmop / MICROUNITS); |
0 | 1156 |
1157 if (need_to_track_page_armed_status) { | |
1158 tty->print(INT32_FORMAT" ", sstats->_page_armed); | |
1159 } | |
1160 tty->print_cr(INT32_FORMAT" ", sstats->_nof_threads_hit_page_trap); | |
1161 } | |
1162 } | |
1163 | |
1164 // This method will be called when VM exits. It will first call | |
1165 // print_statistics to print out the rest of the sampling. Then | |
1166 // it tries to summarize the sampling. | |
1167 void SafepointSynchronize::print_stat_on_exit() { | |
1168 if (_safepoint_stats == NULL) return; | |
1169 | |
1170 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; | |
1171 | |
1172 // During VM exit, end_statistics may not get called and in that | |
1173 // case, if the sync time is less than PrintSafepointStatisticsTimeout, | |
1174 // don't print it out. | |
1175 // Approximate the vm op time. | |
1176 _safepoint_stats[_cur_stat_index]._time_to_exec_vmop = | |
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1177 os::javaTimeNanos() - cleanup_end_time; |
0 | 1178 |
1179 if ( PrintSafepointStatisticsTimeout < 0 || | |
1180 spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) { | |
1181 print_statistics(); | |
1182 } | |
1183 tty->print_cr(""); | |
1184 | |
1185 // Print out polling page sampling status. | |
1186 if (!need_to_track_page_armed_status) { | |
1187 if (UseCompilerSafepoints) { | |
1188 tty->print_cr("Polling page always armed"); | |
1189 } | |
1190 } else { | |
1191 tty->print_cr("Defer polling page loop count = %d\n", | |
1192 DeferPollingPageLoopCount); | |
1193 } | |
1194 | |
1195 for (int index = 0; index < VM_Operation::VMOp_Terminating; index++) { | |
1196 if (_safepoint_reasons[index] != 0) { | |
1197 tty->print_cr("%-26s"UINT64_FORMAT_W(10), VM_Operation::name(index), | |
1198 _safepoint_reasons[index]); | |
1199 } | |
1200 } | |
1201 | |
1202 tty->print_cr(UINT64_FORMAT_W(5)" VM operations coalesced during safepoint", | |
1203 _coalesced_vmop_count); | |
1204 tty->print_cr("Maximum sync time "INT64_FORMAT_W(5)" ms", | |
1205 _max_sync_time / MICROUNITS); | |
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1206 tty->print_cr("Maximum vm operation time (except for Exit VM operation) " |
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1207 INT64_FORMAT_W(5)" ms", |
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1208 _max_vmop_time / MICROUNITS); |
0 | 1209 } |
1210 | |
1211 // ------------------------------------------------------------------------------------------------ | |
1212 // Non-product code | |
1213 | |
1214 #ifndef PRODUCT | |
1215 | |
1216 void SafepointSynchronize::print_state() { | |
1217 if (_state == _not_synchronized) { | |
1218 tty->print_cr("not synchronized"); | |
1219 } else if (_state == _synchronizing || _state == _synchronized) { | |
1220 tty->print_cr("State: %s", (_state == _synchronizing) ? "synchronizing" : | |
1221 "synchronized"); | |
1222 | |
1223 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) { | |
1224 cur->safepoint_state()->print(); | |
1225 } | |
1226 } | |
1227 } | |
1228 | |
1229 void SafepointSynchronize::safepoint_msg(const char* format, ...) { | |
1230 if (ShowSafepointMsgs) { | |
1231 va_list ap; | |
1232 va_start(ap, format); | |
1233 tty->vprint_cr(format, ap); | |
1234 va_end(ap); | |
1235 } | |
1236 } | |
1237 | |
1238 #endif // !PRODUCT |