Mercurial > hg > truffle
annotate src/share/vm/runtime/safepoint.cpp @ 20197:ce8f6bb717c9
8042195: Introduce umbrella header orderAccess.inline.hpp.
Reviewed-by: dholmes, kvn, stefank, twisti
author | goetz |
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date | Tue, 29 Apr 2014 15:17:27 +0200 |
parents | 581e70386ec9 |
children | 833b0f92429a |
rev | line source |
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0 | 1 /* |
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2 * Copyright (c) 1997, 2014, 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" |
6162 | 26 #include "classfile/symbolTable.hpp" |
1972 | 27 #include "classfile/systemDictionary.hpp" |
28 #include "code/codeCache.hpp" | |
29 #include "code/icBuffer.hpp" | |
30 #include "code/nmethod.hpp" | |
31 #include "code/pcDesc.hpp" | |
32 #include "code/scopeDesc.hpp" | |
33 #include "gc_interface/collectedHeap.hpp" | |
34 #include "interpreter/interpreter.hpp" | |
35 #include "memory/resourceArea.hpp" | |
36 #include "memory/universe.inline.hpp" | |
37 #include "oops/oop.inline.hpp" | |
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38 #include "oops/symbol.hpp" |
1972 | 39 #include "runtime/compilationPolicy.hpp" |
40 #include "runtime/deoptimization.hpp" | |
41 #include "runtime/frame.inline.hpp" | |
42 #include "runtime/interfaceSupport.hpp" | |
43 #include "runtime/mutexLocker.hpp" | |
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44 #include "runtime/orderAccess.inline.hpp" |
1972 | 45 #include "runtime/osThread.hpp" |
46 #include "runtime/safepoint.hpp" | |
47 #include "runtime/signature.hpp" | |
48 #include "runtime/stubCodeGenerator.hpp" | |
49 #include "runtime/stubRoutines.hpp" | |
50 #include "runtime/sweeper.hpp" | |
51 #include "runtime/synchronizer.hpp" | |
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52 #include "runtime/thread.inline.hpp" |
6197 | 53 #include "services/memTracker.hpp" |
1972 | 54 #include "services/runtimeService.hpp" |
55 #include "utilities/events.hpp" | |
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56 #include "utilities/macros.hpp" |
1972 | 57 #ifdef TARGET_ARCH_x86 |
58 # include "nativeInst_x86.hpp" | |
59 # include "vmreg_x86.inline.hpp" | |
60 #endif | |
61 #ifdef TARGET_ARCH_sparc | |
62 # include "nativeInst_sparc.hpp" | |
63 # include "vmreg_sparc.inline.hpp" | |
64 #endif | |
65 #ifdef TARGET_ARCH_zero | |
66 # include "nativeInst_zero.hpp" | |
67 # include "vmreg_zero.inline.hpp" | |
68 #endif | |
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69 #ifdef TARGET_ARCH_arm |
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70 # include "nativeInst_arm.hpp" |
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71 # include "vmreg_arm.inline.hpp" |
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72 #endif |
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73 #ifdef TARGET_ARCH_ppc |
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74 # include "nativeInst_ppc.hpp" |
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75 # include "vmreg_ppc.inline.hpp" |
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76 #endif |
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77 #if INCLUDE_ALL_GCS |
1972 | 78 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp" |
20192 | 79 #include "gc_implementation/shared/suspendibleThreadSet.hpp" |
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80 #endif // INCLUDE_ALL_GCS |
1972 | 81 #ifdef COMPILER1 |
82 #include "c1/c1_globals.hpp" | |
83 #endif | |
0 | 84 |
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85 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC |
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86 |
0 | 87 // -------------------------------------------------------------------------------------------------- |
88 // Implementation of Safepoint begin/end | |
89 | |
90 SafepointSynchronize::SynchronizeState volatile SafepointSynchronize::_state = SafepointSynchronize::_not_synchronized; | |
91 volatile int SafepointSynchronize::_waiting_to_block = 0; | |
92 volatile int SafepointSynchronize::_safepoint_counter = 0; | |
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93 int SafepointSynchronize::_current_jni_active_count = 0; |
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94 long SafepointSynchronize::_end_of_last_safepoint = 0; |
0 | 95 static volatile int PageArmed = 0 ; // safepoint polling page is RO|RW vs PROT_NONE |
96 static volatile int TryingToBlock = 0 ; // proximate value -- for advisory use only | |
97 static bool timeout_error_printed = false; | |
98 | |
99 // Roll all threads forward to a safepoint and suspend them all | |
100 void SafepointSynchronize::begin() { | |
101 | |
102 Thread* myThread = Thread::current(); | |
103 assert(myThread->is_VM_thread(), "Only VM thread may execute a safepoint"); | |
104 | |
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105 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) { |
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106 _safepoint_begin_time = os::javaTimeNanos(); |
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107 _ts_of_current_safepoint = tty->time_stamp().seconds(); |
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108 } |
0 | 109 |
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110 #if INCLUDE_ALL_GCS |
0 | 111 if (UseConcMarkSweepGC) { |
112 // In the future we should investigate whether CMS can use the | |
113 // more-general mechanism below. DLD (01/05). | |
114 ConcurrentMarkSweepThread::synchronize(false); | |
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115 } else if (UseG1GC) { |
20192 | 116 SuspendibleThreadSet::synchronize(); |
0 | 117 } |
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118 #endif // INCLUDE_ALL_GCS |
0 | 119 |
120 // By getting the Threads_lock, we assure that no threads are about to start or | |
121 // exit. It is released again in SafepointSynchronize::end(). | |
122 Threads_lock->lock(); | |
123 | |
124 assert( _state == _not_synchronized, "trying to safepoint synchronize with wrong state"); | |
125 | |
126 int nof_threads = Threads::number_of_threads(); | |
127 | |
128 if (TraceSafepoint) { | |
129 tty->print_cr("Safepoint synchronization initiated. (%d)", nof_threads); | |
130 } | |
131 | |
132 RuntimeService::record_safepoint_begin(); | |
133 | |
134 MutexLocker mu(Safepoint_lock); | |
135 | |
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136 // Reset the count of active JNI critical threads |
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137 _current_jni_active_count = 0; |
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138 |
0 | 139 // Set number of threads to wait for, before we initiate the callbacks |
140 _waiting_to_block = nof_threads; | |
141 TryingToBlock = 0 ; | |
142 int still_running = nof_threads; | |
143 | |
144 // Save the starting time, so that it can be compared to see if this has taken | |
145 // too long to complete. | |
146 jlong safepoint_limit_time; | |
147 timeout_error_printed = false; | |
148 | |
1003 | 149 // PrintSafepointStatisticsTimeout can be specified separately. When |
150 // specified, PrintSafepointStatistics will be set to true in | |
151 // deferred_initialize_stat method. The initialization has to be done | |
152 // early enough to avoid any races. See bug 6880029 for details. | |
153 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) { | |
154 deferred_initialize_stat(); | |
155 } | |
156 | |
0 | 157 // Begin the process of bringing the system to a safepoint. |
158 // Java threads can be in several different states and are | |
159 // stopped by different mechanisms: | |
160 // | |
161 // 1. Running interpreted | |
162 // The interpeter dispatch table is changed to force it to | |
163 // check for a safepoint condition between bytecodes. | |
164 // 2. Running in native code | |
165 // When returning from the native code, a Java thread must check | |
166 // the safepoint _state to see if we must block. If the | |
167 // VM thread sees a Java thread in native, it does | |
168 // not wait for this thread to block. The order of the memory | |
169 // writes and reads of both the safepoint state and the Java | |
170 // threads state is critical. In order to guarantee that the | |
171 // memory writes are serialized with respect to each other, | |
172 // the VM thread issues a memory barrier instruction | |
173 // (on MP systems). In order to avoid the overhead of issuing | |
174 // a memory barrier for each Java thread making native calls, each Java | |
175 // thread performs a write to a single memory page after changing | |
176 // the thread state. The VM thread performs a sequence of | |
177 // mprotect OS calls which forces all previous writes from all | |
178 // Java threads to be serialized. This is done in the | |
179 // os::serialize_thread_states() call. This has proven to be | |
180 // much more efficient than executing a membar instruction | |
181 // on every call to native code. | |
182 // 3. Running compiled Code | |
183 // Compiled code reads a global (Safepoint Polling) page that | |
184 // is set to fault if we are trying to get to a safepoint. | |
185 // 4. Blocked | |
186 // A thread which is blocked will not be allowed to return from the | |
187 // block condition until the safepoint operation is complete. | |
188 // 5. In VM or Transitioning between states | |
189 // If a Java thread is currently running in the VM or transitioning | |
190 // between states, the safepointing code will wait for the thread to | |
191 // block itself when it attempts transitions to a new state. | |
192 // | |
193 _state = _synchronizing; | |
194 OrderAccess::fence(); | |
195 | |
196 // Flush all thread states to memory | |
197 if (!UseMembar) { | |
198 os::serialize_thread_states(); | |
199 } | |
200 | |
201 // Make interpreter safepoint aware | |
202 Interpreter::notice_safepoints(); | |
203 | |
204 if (UseCompilerSafepoints && DeferPollingPageLoopCount < 0) { | |
205 // Make polling safepoint aware | |
206 guarantee (PageArmed == 0, "invariant") ; | |
207 PageArmed = 1 ; | |
208 os::make_polling_page_unreadable(); | |
209 } | |
210 | |
211 // Consider using active_processor_count() ... but that call is expensive. | |
212 int ncpus = os::processor_count() ; | |
213 | |
214 #ifdef ASSERT | |
215 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) { | |
216 assert(cur->safepoint_state()->is_running(), "Illegal initial state"); | |
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217 // Clear the visited flag to ensure that the critical counts are collected properly. |
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218 cur->set_visited_for_critical_count(false); |
0 | 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 | |
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378 #ifdef ASSERT |
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379 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) { |
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380 // make sure all the threads were visited |
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381 assert(cur->was_visited_for_critical_count(), "missed a thread"); |
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382 } |
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383 #endif // ASSERT |
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384 |
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385 // Update the count of active JNI critical regions |
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386 GC_locker::set_jni_lock_count(_current_jni_active_count); |
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387 |
0 | 388 if (TraceSafepoint) { |
389 VM_Operation *op = VMThread::vm_operation(); | |
390 tty->print_cr("Entering safepoint region: %s", (op != NULL) ? op->name() : "no vm operation"); | |
391 } | |
392 | |
393 RuntimeService::record_safepoint_synchronized(); | |
394 if (PrintSafepointStatistics) { | |
395 update_statistics_on_sync_end(os::javaTimeNanos()); | |
396 } | |
397 | |
398 // Call stuff that needs to be run when a safepoint is just about to be completed | |
399 do_cleanup_tasks(); | |
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400 |
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401 if (PrintSafepointStatistics) { |
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402 // Record how much time spend on the above cleanup tasks |
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403 update_statistics_on_cleanup_end(os::javaTimeNanos()); |
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404 } |
0 | 405 } |
406 | |
407 // Wake up all threads, so they are ready to resume execution after the safepoint | |
408 // operation has been carried out | |
409 void SafepointSynchronize::end() { | |
410 | |
411 assert(Threads_lock->owned_by_self(), "must hold Threads_lock"); | |
412 assert((_safepoint_counter & 0x1) == 1, "must be odd"); | |
413 _safepoint_counter ++; | |
414 // memory fence isn't required here since an odd _safepoint_counter | |
415 // value can do no harm and a fence is issued below anyway. | |
416 | |
417 DEBUG_ONLY(Thread* myThread = Thread::current();) | |
418 assert(myThread->is_VM_thread(), "Only VM thread can execute a safepoint"); | |
419 | |
420 if (PrintSafepointStatistics) { | |
421 end_statistics(os::javaTimeNanos()); | |
422 } | |
423 | |
424 #ifdef ASSERT | |
425 // A pending_exception cannot be installed during a safepoint. The threads | |
426 // may install an async exception after they come back from a safepoint into | |
427 // pending_exception after they unblock. But that should happen later. | |
428 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) { | |
429 assert (!(cur->has_pending_exception() && | |
430 cur->safepoint_state()->is_at_poll_safepoint()), | |
431 "safepoint installed a pending exception"); | |
432 } | |
433 #endif // ASSERT | |
434 | |
435 if (PageArmed) { | |
436 // Make polling safepoint aware | |
437 os::make_polling_page_readable(); | |
438 PageArmed = 0 ; | |
439 } | |
440 | |
441 // Remove safepoint check from interpreter | |
442 Interpreter::ignore_safepoints(); | |
443 | |
444 { | |
445 MutexLocker mu(Safepoint_lock); | |
446 | |
447 assert(_state == _synchronized, "must be synchronized before ending safepoint synchronization"); | |
448 | |
449 // Set to not synchronized, so the threads will not go into the signal_thread_blocked method | |
450 // when they get restarted. | |
451 _state = _not_synchronized; | |
452 OrderAccess::fence(); | |
453 | |
454 if (TraceSafepoint) { | |
455 tty->print_cr("Leaving safepoint region"); | |
456 } | |
457 | |
458 // Start suspended threads | |
459 for(JavaThread *current = Threads::first(); current; current = current->next()) { | |
605 | 460 // A problem occurring on Solaris is when attempting to restart threads |
0 | 461 // the first #cpus - 1 go well, but then the VMThread is preempted when we get |
462 // to the next one (since it has been running the longest). We then have | |
463 // to wait for a cpu to become available before we can continue restarting | |
464 // threads. | |
465 // FIXME: This causes the performance of the VM to degrade when active and with | |
466 // large numbers of threads. Apparently this is due to the synchronous nature | |
467 // of suspending threads. | |
468 // | |
469 // TODO-FIXME: the comments above are vestigial and no longer apply. | |
470 // Furthermore, using solaris' schedctl in this particular context confers no benefit | |
471 if (VMThreadHintNoPreempt) { | |
472 os::hint_no_preempt(); | |
473 } | |
474 ThreadSafepointState* cur_state = current->safepoint_state(); | |
475 assert(cur_state->type() != ThreadSafepointState::_running, "Thread not suspended at safepoint"); | |
476 cur_state->restart(); | |
477 assert(cur_state->is_running(), "safepoint state has not been reset"); | |
478 } | |
479 | |
480 RuntimeService::record_safepoint_end(); | |
481 | |
482 // Release threads lock, so threads can be created/destroyed again. It will also starts all threads | |
483 // blocked in signal_thread_blocked | |
484 Threads_lock->unlock(); | |
485 | |
486 } | |
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487 #if INCLUDE_ALL_GCS |
0 | 488 // If there are any concurrent GC threads resume them. |
489 if (UseConcMarkSweepGC) { | |
490 ConcurrentMarkSweepThread::desynchronize(false); | |
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491 } else if (UseG1GC) { |
20192 | 492 SuspendibleThreadSet::desynchronize(); |
0 | 493 } |
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494 #endif // INCLUDE_ALL_GCS |
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495 // record this time so VMThread can keep track how much time has elasped |
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496 // since last safepoint. |
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497 _end_of_last_safepoint = os::javaTimeMillis(); |
0 | 498 } |
499 | |
500 bool SafepointSynchronize::is_cleanup_needed() { | |
501 // Need a safepoint if some inline cache buffers is non-empty | |
502 if (!InlineCacheBuffer::is_empty()) return true; | |
503 return false; | |
504 } | |
505 | |
506 | |
507 | |
508 // Various cleaning tasks that should be done periodically at safepoints | |
509 void SafepointSynchronize::do_cleanup_tasks() { | |
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510 { |
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511 TraceTime t1("deflating idle monitors", TraceSafepointCleanupTime); |
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512 ObjectSynchronizer::deflate_idle_monitors(); |
0 | 513 } |
514 | |
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515 { |
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516 TraceTime t2("updating inline caches", TraceSafepointCleanupTime); |
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517 InlineCacheBuffer::update_inline_caches(); |
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518 } |
1783 | 519 { |
520 TraceTime t3("compilation policy safepoint handler", TraceSafepointCleanupTime); | |
521 CompilationPolicy::policy()->do_safepoint_work(); | |
0 | 522 } |
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523 |
6162 | 524 { |
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525 TraceTime t4("mark nmethods", TraceSafepointCleanupTime); |
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526 NMethodSweeper::mark_active_nmethods(); |
6162 | 527 } |
528 | |
529 if (SymbolTable::needs_rehashing()) { | |
530 TraceTime t5("rehashing symbol table", TraceSafepointCleanupTime); | |
531 SymbolTable::rehash_table(); | |
532 } | |
533 | |
534 if (StringTable::needs_rehashing()) { | |
535 TraceTime t6("rehashing string table", TraceSafepointCleanupTime); | |
536 StringTable::rehash_table(); | |
537 } | |
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538 |
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539 // rotate log files? |
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540 if (UseGCLogFileRotation) { |
17827 | 541 gclog_or_tty->rotate_log(false); |
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542 } |
6197 | 543 |
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544 { |
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545 // CMS delays purging the CLDG until the beginning of the next safepoint and to |
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546 // make sure concurrent sweep is done |
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547 TraceTime t7("purging class loader data graph", TraceSafepointCleanupTime); |
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548 ClassLoaderDataGraph::purge_if_needed(); |
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549 } |
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550 |
6197 | 551 if (MemTracker::is_on()) { |
552 MemTracker::sync(); | |
553 } | |
0 | 554 } |
555 | |
556 | |
557 bool SafepointSynchronize::safepoint_safe(JavaThread *thread, JavaThreadState state) { | |
558 switch(state) { | |
559 case _thread_in_native: | |
560 // native threads are safe if they have no java stack or have walkable stack | |
561 return !thread->has_last_Java_frame() || thread->frame_anchor()->walkable(); | |
562 | |
563 // blocked threads should have already have walkable stack | |
564 case _thread_blocked: | |
565 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "blocked and not walkable"); | |
566 return true; | |
567 | |
568 default: | |
569 return false; | |
570 } | |
571 } | |
572 | |
573 | |
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574 // See if the thread is running inside a lazy critical native and |
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575 // update the thread critical count if so. Also set a suspend flag to |
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576 // cause the native wrapper to return into the JVM to do the unlock |
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577 // once the native finishes. |
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578 void SafepointSynchronize::check_for_lazy_critical_native(JavaThread *thread, JavaThreadState state) { |
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579 if (state == _thread_in_native && |
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580 thread->has_last_Java_frame() && |
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581 thread->frame_anchor()->walkable()) { |
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582 // This thread might be in a critical native nmethod so look at |
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583 // the top of the stack and increment the critical count if it |
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584 // is. |
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585 frame wrapper_frame = thread->last_frame(); |
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586 CodeBlob* stub_cb = wrapper_frame.cb(); |
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587 if (stub_cb != NULL && |
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588 stub_cb->is_nmethod() && |
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589 stub_cb->as_nmethod_or_null()->is_lazy_critical_native()) { |
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590 // A thread could potentially be in a critical native across |
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591 // more than one safepoint, so only update the critical state on |
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592 // the first one. When it returns it will perform the unlock. |
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593 if (!thread->do_critical_native_unlock()) { |
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594 #ifdef ASSERT |
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595 if (!thread->in_critical()) { |
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596 GC_locker::increment_debug_jni_lock_count(); |
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597 } |
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598 #endif |
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599 thread->enter_critical(); |
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600 // Make sure the native wrapper calls back on return to |
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601 // perform the needed critical unlock. |
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602 thread->set_critical_native_unlock(); |
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603 } |
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604 } |
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605 } |
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606 } |
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607 |
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608 |
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609 |
0 | 610 // ------------------------------------------------------------------------------------------------------- |
611 // Implementation of Safepoint callback point | |
612 | |
613 void SafepointSynchronize::block(JavaThread *thread) { | |
614 assert(thread != NULL, "thread must be set"); | |
615 assert(thread->is_Java_thread(), "not a Java thread"); | |
616 | |
617 // Threads shouldn't block if they are in the middle of printing, but... | |
618 ttyLocker::break_tty_lock_for_safepoint(os::current_thread_id()); | |
619 | |
620 // Only bail from the block() call if the thread is gone from the | |
621 // thread list; starting to exit should still block. | |
622 if (thread->is_terminated()) { | |
623 // block current thread if we come here from native code when VM is gone | |
624 thread->block_if_vm_exited(); | |
625 | |
626 // otherwise do nothing | |
627 return; | |
628 } | |
629 | |
630 JavaThreadState state = thread->thread_state(); | |
631 thread->frame_anchor()->make_walkable(thread); | |
632 | |
633 // Check that we have a valid thread_state at this point | |
634 switch(state) { | |
635 case _thread_in_vm_trans: | |
636 case _thread_in_Java: // From compiled code | |
637 | |
638 // We are highly likely to block on the Safepoint_lock. In order to avoid blocking in this case, | |
639 // we pretend we are still in the VM. | |
640 thread->set_thread_state(_thread_in_vm); | |
641 | |
642 if (is_synchronizing()) { | |
643 Atomic::inc (&TryingToBlock) ; | |
644 } | |
645 | |
646 // We will always be holding the Safepoint_lock when we are examine the state | |
647 // of a thread. Hence, the instructions between the Safepoint_lock->lock() and | |
648 // Safepoint_lock->unlock() are happening atomic with regards to the safepoint code | |
649 Safepoint_lock->lock_without_safepoint_check(); | |
650 if (is_synchronizing()) { | |
651 // Decrement the number of threads to wait for and signal vm thread | |
652 assert(_waiting_to_block > 0, "sanity check"); | |
653 _waiting_to_block--; | |
654 thread->safepoint_state()->set_has_called_back(true); | |
655 | |
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656 DEBUG_ONLY(thread->set_visited_for_critical_count(true)); |
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657 if (thread->in_critical()) { |
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658 // Notice that this thread is in a critical section |
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659 increment_jni_active_count(); |
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660 } |
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661 |
0 | 662 // Consider (_waiting_to_block < 2) to pipeline the wakeup of the VM thread |
663 if (_waiting_to_block == 0) { | |
664 Safepoint_lock->notify_all(); | |
665 } | |
666 } | |
667 | |
668 // We transition the thread to state _thread_blocked here, but | |
669 // we can't do our usual check for external suspension and then | |
670 // self-suspend after the lock_without_safepoint_check() call | |
671 // below because we are often called during transitions while | |
672 // we hold different locks. That would leave us suspended while | |
673 // holding a resource which results in deadlocks. | |
674 thread->set_thread_state(_thread_blocked); | |
675 Safepoint_lock->unlock(); | |
676 | |
677 // We now try to acquire the threads lock. Since this lock is hold by the VM thread during | |
678 // the entire safepoint, the threads will all line up here during the safepoint. | |
679 Threads_lock->lock_without_safepoint_check(); | |
680 // restore original state. This is important if the thread comes from compiled code, so it | |
681 // will continue to execute with the _thread_in_Java state. | |
682 thread->set_thread_state(state); | |
683 Threads_lock->unlock(); | |
684 break; | |
685 | |
686 case _thread_in_native_trans: | |
687 case _thread_blocked_trans: | |
688 case _thread_new_trans: | |
689 if (thread->safepoint_state()->type() == ThreadSafepointState::_call_back) { | |
690 thread->print_thread_state(); | |
691 fatal("Deadlock in safepoint code. " | |
692 "Should have called back to the VM before blocking."); | |
693 } | |
694 | |
695 // We transition the thread to state _thread_blocked here, but | |
696 // we can't do our usual check for external suspension and then | |
697 // self-suspend after the lock_without_safepoint_check() call | |
698 // below because we are often called during transitions while | |
699 // we hold different locks. That would leave us suspended while | |
700 // holding a resource which results in deadlocks. | |
701 thread->set_thread_state(_thread_blocked); | |
702 | |
703 // It is not safe to suspend a thread if we discover it is in _thread_in_native_trans. Hence, | |
704 // the safepoint code might still be waiting for it to block. We need to change the state here, | |
705 // so it can see that it is at a safepoint. | |
706 | |
707 // Block until the safepoint operation is completed. | |
708 Threads_lock->lock_without_safepoint_check(); | |
709 | |
710 // Restore state | |
711 thread->set_thread_state(state); | |
712 | |
713 Threads_lock->unlock(); | |
714 break; | |
715 | |
716 default: | |
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717 fatal(err_msg("Illegal threadstate encountered: %d", state)); |
0 | 718 } |
719 | |
720 // Check for pending. async. exceptions or suspends - except if the | |
721 // thread was blocked inside the VM. has_special_runtime_exit_condition() | |
722 // is called last since it grabs a lock and we only want to do that when | |
723 // we must. | |
724 // | |
725 // Note: we never deliver an async exception at a polling point as the | |
726 // compiler may not have an exception handler for it. The polling | |
727 // code will notice the async and deoptimize and the exception will | |
728 // be delivered. (Polling at a return point is ok though). Sure is | |
729 // a lot of bother for a deprecated feature... | |
730 // | |
731 // We don't deliver an async exception if the thread state is | |
732 // _thread_in_native_trans so JNI functions won't be called with | |
733 // a surprising pending exception. If the thread state is going back to java, | |
734 // async exception is checked in check_special_condition_for_native_trans(). | |
735 | |
736 if (state != _thread_blocked_trans && | |
737 state != _thread_in_vm_trans && | |
738 thread->has_special_runtime_exit_condition()) { | |
739 thread->handle_special_runtime_exit_condition( | |
740 !thread->is_at_poll_safepoint() && (state != _thread_in_native_trans)); | |
741 } | |
742 } | |
743 | |
744 // ------------------------------------------------------------------------------------------------------ | |
745 // Exception handlers | |
746 | |
747 #ifndef PRODUCT | |
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749 #ifdef SPARC |
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750 |
0 | 751 #ifdef _LP64 |
752 #define PTR_PAD "" | |
753 #else | |
754 #define PTR_PAD " " | |
755 #endif | |
756 | |
757 static void print_ptrs(intptr_t oldptr, intptr_t newptr, bool wasoop) { | |
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758 bool is_oop = newptr ? (cast_to_oop(newptr))->is_oop() : false; |
0 | 759 tty->print_cr(PTR_FORMAT PTR_PAD " %s %c " PTR_FORMAT PTR_PAD " %s %s", |
760 oldptr, wasoop?"oop":" ", oldptr == newptr ? ' ' : '!', | |
761 newptr, is_oop?"oop":" ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":" ")); | |
762 } | |
763 | |
764 static void print_longs(jlong oldptr, jlong newptr, bool wasoop) { | |
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765 bool is_oop = newptr ? (cast_to_oop(newptr))->is_oop() : false; |
0 | 766 tty->print_cr(PTR64_FORMAT " %s %c " PTR64_FORMAT " %s %s", |
767 oldptr, wasoop?"oop":" ", oldptr == newptr ? ' ' : '!', | |
768 newptr, is_oop?"oop":" ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":" ")); | |
769 } | |
770 | |
771 static void print_me(intptr_t *new_sp, intptr_t *old_sp, bool *was_oops) { | |
772 #ifdef _LP64 | |
773 tty->print_cr("--------+------address-----+------before-----------+-------after----------+"); | |
774 const int incr = 1; // Increment to skip a long, in units of intptr_t | |
775 #else | |
776 tty->print_cr("--------+--address-+------before-----------+-------after----------+"); | |
777 const int incr = 2; // Increment to skip a long, in units of intptr_t | |
778 #endif | |
779 tty->print_cr("---SP---|"); | |
780 for( int i=0; i<16; i++ ) { | |
781 tty->print("blob %c%d |"PTR_FORMAT" ","LO"[i>>3],i&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); } | |
782 tty->print_cr("--------|"); | |
783 for( int i1=0; i1<frame::memory_parameter_word_sp_offset-16; i1++ ) { | |
784 tty->print("argv pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); } | |
785 tty->print(" pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); | |
786 tty->print_cr("--------|"); | |
787 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; | |
788 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; | |
789 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; | |
790 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; | |
791 tty->print_cr(" FSR |"PTR_FORMAT" "PTR64_FORMAT" "PTR64_FORMAT,new_sp,*(jlong*)old_sp,*(jlong*)new_sp); | |
792 old_sp += incr; new_sp += incr; was_oops += incr; | |
793 // Skip the floats | |
794 tty->print_cr("--Float-|"PTR_FORMAT,new_sp); | |
795 tty->print_cr("---FP---|"); | |
796 old_sp += incr*32; new_sp += incr*32; was_oops += incr*32; | |
797 for( int i2=0; i2<16; i2++ ) { | |
798 tty->print("call %c%d |"PTR_FORMAT" ","LI"[i2>>3],i2&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); } | |
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799 tty->cr(); |
0 | 800 } |
801 #endif // SPARC | |
802 #endif // PRODUCT | |
803 | |
804 | |
805 void SafepointSynchronize::handle_polling_page_exception(JavaThread *thread) { | |
806 assert(thread->is_Java_thread(), "polling reference encountered by VM thread"); | |
807 assert(thread->thread_state() == _thread_in_Java, "should come from Java code"); | |
808 assert(SafepointSynchronize::is_synchronizing(), "polling encountered outside safepoint synchronization"); | |
809 | |
810 // Uncomment this to get some serious before/after printing of the | |
811 // Sparc safepoint-blob frame structure. | |
812 /* | |
813 intptr_t* sp = thread->last_Java_sp(); | |
814 intptr_t stack_copy[150]; | |
815 for( int i=0; i<150; i++ ) stack_copy[i] = sp[i]; | |
816 bool was_oops[150]; | |
817 for( int i=0; i<150; i++ ) | |
818 was_oops[i] = stack_copy[i] ? ((oop)stack_copy[i])->is_oop() : false; | |
819 */ | |
820 | |
821 if (ShowSafepointMsgs) { | |
822 tty->print("handle_polling_page_exception: "); | |
823 } | |
824 | |
825 if (PrintSafepointStatistics) { | |
826 inc_page_trap_count(); | |
827 } | |
828 | |
829 ThreadSafepointState* state = thread->safepoint_state(); | |
830 | |
831 state->handle_polling_page_exception(); | |
832 // print_me(sp,stack_copy,was_oops); | |
833 } | |
834 | |
835 | |
836 void SafepointSynchronize::print_safepoint_timeout(SafepointTimeoutReason reason) { | |
837 if (!timeout_error_printed) { | |
838 timeout_error_printed = true; | |
839 // Print out the thread infor which didn't reach the safepoint for debugging | |
840 // purposes (useful when there are lots of threads in the debugger). | |
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841 tty->cr(); |
0 | 842 tty->print_cr("# SafepointSynchronize::begin: Timeout detected:"); |
843 if (reason == _spinning_timeout) { | |
844 tty->print_cr("# SafepointSynchronize::begin: Timed out while spinning to reach a safepoint."); | |
845 } else if (reason == _blocking_timeout) { | |
846 tty->print_cr("# SafepointSynchronize::begin: Timed out while waiting for threads to stop."); | |
847 } | |
848 | |
849 tty->print_cr("# SafepointSynchronize::begin: Threads which did not reach the safepoint:"); | |
850 ThreadSafepointState *cur_state; | |
851 ResourceMark rm; | |
852 for(JavaThread *cur_thread = Threads::first(); cur_thread; | |
853 cur_thread = cur_thread->next()) { | |
854 cur_state = cur_thread->safepoint_state(); | |
855 | |
856 if (cur_thread->thread_state() != _thread_blocked && | |
857 ((reason == _spinning_timeout && cur_state->is_running()) || | |
858 (reason == _blocking_timeout && !cur_state->has_called_back()))) { | |
859 tty->print("# "); | |
860 cur_thread->print(); | |
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861 tty->cr(); |
0 | 862 } |
863 } | |
864 tty->print_cr("# SafepointSynchronize::begin: (End of list)"); | |
865 } | |
866 | |
867 // To debug the long safepoint, specify both DieOnSafepointTimeout & | |
868 // ShowMessageBoxOnError. | |
869 if (DieOnSafepointTimeout) { | |
870 char msg[1024]; | |
871 VM_Operation *op = VMThread::vm_operation(); | |
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872 sprintf(msg, "Safepoint sync time longer than " INTX_FORMAT "ms detected when executing %s.", |
0 | 873 SafepointTimeoutDelay, |
874 op != NULL ? op->name() : "no vm operation"); | |
875 fatal(msg); | |
876 } | |
877 } | |
878 | |
879 | |
880 // ------------------------------------------------------------------------------------------------------- | |
881 // Implementation of ThreadSafepointState | |
882 | |
883 ThreadSafepointState::ThreadSafepointState(JavaThread *thread) { | |
884 _thread = thread; | |
885 _type = _running; | |
886 _has_called_back = false; | |
887 _at_poll_safepoint = false; | |
888 } | |
889 | |
890 void ThreadSafepointState::create(JavaThread *thread) { | |
891 ThreadSafepointState *state = new ThreadSafepointState(thread); | |
892 thread->set_safepoint_state(state); | |
893 } | |
894 | |
895 void ThreadSafepointState::destroy(JavaThread *thread) { | |
896 if (thread->safepoint_state()) { | |
897 delete(thread->safepoint_state()); | |
898 thread->set_safepoint_state(NULL); | |
899 } | |
900 } | |
901 | |
902 void ThreadSafepointState::examine_state_of_thread() { | |
903 assert(is_running(), "better be running or just have hit safepoint poll"); | |
904 | |
905 JavaThreadState state = _thread->thread_state(); | |
906 | |
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907 // Save the state at the start of safepoint processing. |
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908 _orig_thread_state = state; |
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909 |
0 | 910 // Check for a thread that is suspended. Note that thread resume tries |
911 // to grab the Threads_lock which we own here, so a thread cannot be | |
912 // resumed during safepoint synchronization. | |
913 | |
979 | 914 // We check to see if this thread is suspended without locking to |
915 // avoid deadlocking with a third thread that is waiting for this | |
916 // thread to be suspended. The third thread can notice the safepoint | |
917 // that we're trying to start at the beginning of its SR_lock->wait() | |
918 // call. If that happens, then the third thread will block on the | |
919 // safepoint while still holding the underlying SR_lock. We won't be | |
920 // able to get the SR_lock and we'll deadlock. | |
921 // | |
922 // We don't need to grab the SR_lock here for two reasons: | |
923 // 1) The suspend flags are both volatile and are set with an | |
924 // Atomic::cmpxchg() call so we should see the suspended | |
925 // state right away. | |
926 // 2) We're being called from the safepoint polling loop; if | |
927 // we don't see the suspended state on this iteration, then | |
928 // we'll come around again. | |
929 // | |
930 bool is_suspended = _thread->is_ext_suspended(); | |
0 | 931 if (is_suspended) { |
932 roll_forward(_at_safepoint); | |
933 return; | |
934 } | |
935 | |
936 // Some JavaThread states have an initial safepoint state of | |
937 // running, but are actually at a safepoint. We will happily | |
938 // agree and update the safepoint state here. | |
939 if (SafepointSynchronize::safepoint_safe(_thread, state)) { | |
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940 SafepointSynchronize::check_for_lazy_critical_native(_thread, state); |
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941 roll_forward(_at_safepoint); |
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942 return; |
0 | 943 } |
944 | |
945 if (state == _thread_in_vm) { | |
946 roll_forward(_call_back); | |
947 return; | |
948 } | |
949 | |
950 // All other thread states will continue to run until they | |
951 // transition and self-block in state _blocked | |
952 // Safepoint polling in compiled code causes the Java threads to do the same. | |
953 // Note: new threads may require a malloc so they must be allowed to finish | |
954 | |
955 assert(is_running(), "examine_state_of_thread on non-running thread"); | |
956 return; | |
957 } | |
958 | |
959 // Returns true is thread could not be rolled forward at present position. | |
960 void ThreadSafepointState::roll_forward(suspend_type type) { | |
961 _type = type; | |
962 | |
963 switch(_type) { | |
964 case _at_safepoint: | |
965 SafepointSynchronize::signal_thread_at_safepoint(); | |
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966 DEBUG_ONLY(_thread->set_visited_for_critical_count(true)); |
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967 if (_thread->in_critical()) { |
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968 // Notice that this thread is in a critical section |
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969 SafepointSynchronize::increment_jni_active_count(); |
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970 } |
0 | 971 break; |
972 | |
973 case _call_back: | |
974 set_has_called_back(false); | |
975 break; | |
976 | |
977 case _running: | |
978 default: | |
979 ShouldNotReachHere(); | |
980 } | |
981 } | |
982 | |
983 void ThreadSafepointState::restart() { | |
984 switch(type()) { | |
985 case _at_safepoint: | |
986 case _call_back: | |
987 break; | |
988 | |
989 case _running: | |
990 default: | |
991 tty->print_cr("restart thread "INTPTR_FORMAT" with state %d", | |
992 _thread, _type); | |
993 _thread->print(); | |
994 ShouldNotReachHere(); | |
995 } | |
996 _type = _running; | |
997 set_has_called_back(false); | |
998 } | |
999 | |
1000 | |
1001 void ThreadSafepointState::print_on(outputStream *st) const { | |
1002 const char *s; | |
1003 | |
1004 switch(_type) { | |
1005 case _running : s = "_running"; break; | |
1006 case _at_safepoint : s = "_at_safepoint"; break; | |
1007 case _call_back : s = "_call_back"; break; | |
1008 default: | |
1009 ShouldNotReachHere(); | |
1010 } | |
1011 | |
1012 st->print_cr("Thread: " INTPTR_FORMAT | |
1013 " [0x%2x] State: %s _has_called_back %d _at_poll_safepoint %d", | |
1014 _thread, _thread->osthread()->thread_id(), s, _has_called_back, | |
1015 _at_poll_safepoint); | |
1016 | |
1017 _thread->print_thread_state_on(st); | |
1018 } | |
1019 | |
1020 | |
1021 // --------------------------------------------------------------------------------------------------------------------- | |
1022 | |
1023 // Block the thread at the safepoint poll or poll return. | |
1024 void ThreadSafepointState::handle_polling_page_exception() { | |
1025 | |
1026 // Check state. block() will set thread state to thread_in_vm which will | |
1027 // cause the safepoint state _type to become _call_back. | |
1028 assert(type() == ThreadSafepointState::_running, | |
1029 "polling page exception on thread not running state"); | |
1030 | |
1031 // Step 1: Find the nmethod from the return address | |
1032 if (ShowSafepointMsgs && Verbose) { | |
1033 tty->print_cr("Polling page exception at " INTPTR_FORMAT, thread()->saved_exception_pc()); | |
1034 } | |
1035 address real_return_addr = thread()->saved_exception_pc(); | |
1036 | |
1037 CodeBlob *cb = CodeCache::find_blob(real_return_addr); | |
1038 assert(cb != NULL && cb->is_nmethod(), "return address should be in nmethod"); | |
1039 nmethod* nm = (nmethod*)cb; | |
1040 | |
1041 // Find frame of caller | |
1042 frame stub_fr = thread()->last_frame(); | |
1043 CodeBlob* stub_cb = stub_fr.cb(); | |
1044 assert(stub_cb->is_safepoint_stub(), "must be a safepoint stub"); | |
1045 RegisterMap map(thread(), true); | |
1046 frame caller_fr = stub_fr.sender(&map); | |
1047 | |
1048 // Should only be poll_return or poll | |
1049 assert( nm->is_at_poll_or_poll_return(real_return_addr), "should not be at call" ); | |
1050 | |
1051 // This is a poll immediately before a return. The exception handling code | |
1052 // has already had the effect of causing the return to occur, so the execution | |
1053 // will continue immediately after the call. In addition, the oopmap at the | |
1054 // return point does not mark the return value as an oop (if it is), so | |
1055 // it needs a handle here to be updated. | |
1056 if( nm->is_at_poll_return(real_return_addr) ) { | |
1057 // See if return type is an oop. | |
1058 bool return_oop = nm->method()->is_returning_oop(); | |
1059 Handle return_value; | |
1060 if (return_oop) { | |
1061 // The oop result has been saved on the stack together with all | |
1062 // the other registers. In order to preserve it over GCs we need | |
1063 // to keep it in a handle. | |
1064 oop result = caller_fr.saved_oop_result(&map); | |
1065 assert(result == NULL || result->is_oop(), "must be oop"); | |
1066 return_value = Handle(thread(), result); | |
1067 assert(Universe::heap()->is_in_or_null(result), "must be heap pointer"); | |
1068 } | |
1069 | |
1070 // Block the thread | |
1071 SafepointSynchronize::block(thread()); | |
1072 | |
1073 // restore oop result, if any | |
1074 if (return_oop) { | |
1075 caller_fr.set_saved_oop_result(&map, return_value()); | |
1076 } | |
1077 } | |
1078 | |
1079 // This is a safepoint poll. Verify the return address and block. | |
1080 else { | |
1081 set_at_poll_safepoint(true); | |
1082 | |
1083 // verify the blob built the "return address" correctly | |
1084 assert(real_return_addr == caller_fr.pc(), "must match"); | |
1085 | |
1086 // Block the thread | |
1087 SafepointSynchronize::block(thread()); | |
1088 set_at_poll_safepoint(false); | |
1089 | |
1090 // If we have a pending async exception deoptimize the frame | |
1091 // as otherwise we may never deliver it. | |
1092 if (thread()->has_async_condition()) { | |
1093 ThreadInVMfromJavaNoAsyncException __tiv(thread()); | |
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1094 Deoptimization::deoptimize_frame(thread(), caller_fr.id()); |
0 | 1095 } |
1096 | |
1097 // If an exception has been installed we must check for a pending deoptimization | |
1098 // Deoptimize frame if exception has been thrown. | |
1099 | |
1100 if (thread()->has_pending_exception() ) { | |
1101 RegisterMap map(thread(), true); | |
1102 frame caller_fr = stub_fr.sender(&map); | |
1103 if (caller_fr.is_deoptimized_frame()) { | |
1104 // The exception patch will destroy registers that are still | |
1105 // live and will be needed during deoptimization. Defer the | |
1106 // Async exception should have defered the exception until the | |
1107 // next safepoint which will be detected when we get into | |
1108 // the interpreter so if we have an exception now things | |
1109 // are messed up. | |
1110 | |
1111 fatal("Exception installed and deoptimization is pending"); | |
1112 } | |
1113 } | |
1114 } | |
1115 } | |
1116 | |
1117 | |
1118 // | |
1119 // Statistics & Instrumentations | |
1120 // | |
1121 SafepointSynchronize::SafepointStats* SafepointSynchronize::_safepoint_stats = NULL; | |
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1122 jlong SafepointSynchronize::_safepoint_begin_time = 0; |
0 | 1123 int SafepointSynchronize::_cur_stat_index = 0; |
1124 julong SafepointSynchronize::_safepoint_reasons[VM_Operation::VMOp_Terminating]; | |
1125 julong SafepointSynchronize::_coalesced_vmop_count = 0; | |
1126 jlong SafepointSynchronize::_max_sync_time = 0; | |
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1127 jlong SafepointSynchronize::_max_vmop_time = 0; |
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1128 float SafepointSynchronize::_ts_of_current_safepoint = 0.0f; |
0 | 1129 |
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1130 static jlong cleanup_end_time = 0; |
0 | 1131 static bool need_to_track_page_armed_status = false; |
1132 static bool init_done = false; | |
1133 | |
1291
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1134 // Helper method to print the header. |
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1135 static void print_header() { |
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1136 tty->print(" vmop " |
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1137 "[threads: total initially_running wait_to_block] "); |
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1138 tty->print("[time: spin block sync cleanup vmop] "); |
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1139 |
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1140 // no page armed status printed out if it is always armed. |
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1141 if (need_to_track_page_armed_status) { |
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1142 tty->print("page_armed "); |
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1143 } |
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1144 |
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1145 tty->print_cr("page_trap_count"); |
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1146 } |
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1147 |
0 | 1148 void SafepointSynchronize::deferred_initialize_stat() { |
1149 if (init_done) return; | |
1150 | |
1151 if (PrintSafepointStatisticsCount <= 0) { | |
1152 fatal("Wrong PrintSafepointStatisticsCount"); | |
1153 } | |
1154 | |
1155 // If PrintSafepointStatisticsTimeout is specified, the statistics data will | |
1156 // be printed right away, in which case, _safepoint_stats will regress to | |
1157 // a single element array. Otherwise, it is a circular ring buffer with default | |
1158 // size of PrintSafepointStatisticsCount. | |
1159 int stats_array_size; | |
1160 if (PrintSafepointStatisticsTimeout > 0) { | |
1161 stats_array_size = 1; | |
1162 PrintSafepointStatistics = true; | |
1163 } else { | |
1164 stats_array_size = PrintSafepointStatisticsCount; | |
1165 } | |
1166 _safepoint_stats = (SafepointStats*)os::malloc(stats_array_size | |
6197 | 1167 * sizeof(SafepointStats), mtInternal); |
0 | 1168 guarantee(_safepoint_stats != NULL, |
1169 "not enough memory for safepoint instrumentation data"); | |
1170 | |
1171 if (UseCompilerSafepoints && DeferPollingPageLoopCount >= 0) { | |
1172 need_to_track_page_armed_status = true; | |
1173 } | |
1174 init_done = true; | |
1175 } | |
1176 | |
1177 void SafepointSynchronize::begin_statistics(int nof_threads, int nof_running) { | |
1003 | 1178 assert(init_done, "safepoint statistics array hasn't been initialized"); |
0 | 1179 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; |
1180 | |
1291
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1181 spstat->_time_stamp = _ts_of_current_safepoint; |
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1182 |
0 | 1183 VM_Operation *op = VMThread::vm_operation(); |
1184 spstat->_vmop_type = (op != NULL ? op->type() : -1); | |
1185 if (op != NULL) { | |
1186 _safepoint_reasons[spstat->_vmop_type]++; | |
1187 } | |
1188 | |
1189 spstat->_nof_total_threads = nof_threads; | |
1190 spstat->_nof_initial_running_threads = nof_running; | |
1191 spstat->_nof_threads_hit_page_trap = 0; | |
1192 | |
1193 // Records the start time of spinning. The real time spent on spinning | |
1194 // will be adjusted when spin is done. Same trick is applied for time | |
1195 // spent on waiting for threads to block. | |
1196 if (nof_running != 0) { | |
1197 spstat->_time_to_spin = os::javaTimeNanos(); | |
1198 } else { | |
1199 spstat->_time_to_spin = 0; | |
1200 } | |
1201 } | |
1202 | |
1203 void SafepointSynchronize::update_statistics_on_spin_end() { | |
1204 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; | |
1205 | |
1206 jlong cur_time = os::javaTimeNanos(); | |
1207 | |
1208 spstat->_nof_threads_wait_to_block = _waiting_to_block; | |
1209 if (spstat->_nof_initial_running_threads != 0) { | |
1210 spstat->_time_to_spin = cur_time - spstat->_time_to_spin; | |
1211 } | |
1212 | |
1213 if (need_to_track_page_armed_status) { | |
1214 spstat->_page_armed = (PageArmed == 1); | |
1215 } | |
1216 | |
1217 // Records the start time of waiting for to block. Updated when block is done. | |
1218 if (_waiting_to_block != 0) { | |
1219 spstat->_time_to_wait_to_block = cur_time; | |
1220 } else { | |
1221 spstat->_time_to_wait_to_block = 0; | |
1222 } | |
1223 } | |
1224 | |
1225 void SafepointSynchronize::update_statistics_on_sync_end(jlong end_time) { | |
1226 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; | |
1227 | |
1228 if (spstat->_nof_threads_wait_to_block != 0) { | |
1229 spstat->_time_to_wait_to_block = end_time - | |
1230 spstat->_time_to_wait_to_block; | |
1231 } | |
1232 | |
1233 // Records the end time of sync which will be used to calculate the total | |
1234 // vm operation time. Again, the real time spending in syncing will be deducted | |
1235 // from the start of the sync time later when end_statistics is called. | |
1291
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1236 spstat->_time_to_sync = end_time - _safepoint_begin_time; |
0 | 1237 if (spstat->_time_to_sync > _max_sync_time) { |
1238 _max_sync_time = spstat->_time_to_sync; | |
1239 } | |
1291
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1240 |
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1241 spstat->_time_to_do_cleanups = end_time; |
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1242 } |
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1243 |
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1244 void SafepointSynchronize::update_statistics_on_cleanup_end(jlong end_time) { |
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1245 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; |
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1246 |
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1247 // Record how long spent in cleanup tasks. |
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1248 spstat->_time_to_do_cleanups = end_time - spstat->_time_to_do_cleanups; |
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1249 |
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1250 cleanup_end_time = end_time; |
0 | 1251 } |
1252 | |
1253 void SafepointSynchronize::end_statistics(jlong vmop_end_time) { | |
1254 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; | |
1255 | |
1256 // Update the vm operation time. | |
1291
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1257 spstat->_time_to_exec_vmop = vmop_end_time - cleanup_end_time; |
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1258 if (spstat->_time_to_exec_vmop > _max_vmop_time) { |
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1259 _max_vmop_time = spstat->_time_to_exec_vmop; |
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1260 } |
0 | 1261 // Only the sync time longer than the specified |
1262 // PrintSafepointStatisticsTimeout will be printed out right away. | |
1263 // By default, it is -1 meaning all samples will be put into the list. | |
1264 if ( PrintSafepointStatisticsTimeout > 0) { | |
1265 if (spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) { | |
1266 print_statistics(); | |
1267 } | |
1268 } else { | |
1269 // The safepoint statistics will be printed out when the _safepoin_stats | |
1270 // array fills up. | |
1291
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1271 if (_cur_stat_index == PrintSafepointStatisticsCount - 1) { |
0 | 1272 print_statistics(); |
1273 _cur_stat_index = 0; | |
1291
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1274 } else { |
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1275 _cur_stat_index++; |
0 | 1276 } |
1277 } | |
1278 } | |
1279 | |
1280 void SafepointSynchronize::print_statistics() { | |
1281 SafepointStats* sstats = _safepoint_stats; | |
1282 | |
1291
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1283 for (int index = 0; index <= _cur_stat_index; index++) { |
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1284 if (index % 30 == 0) { |
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1285 print_header(); |
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1286 } |
0 | 1287 sstats = &_safepoint_stats[index]; |
1291
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1288 tty->print("%.3f: ", sstats->_time_stamp); |
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1289 tty->print("%-26s [" |
0 | 1290 INT32_FORMAT_W(8)INT32_FORMAT_W(11)INT32_FORMAT_W(15) |
1291
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1291 " ] ", |
0 | 1292 sstats->_vmop_type == -1 ? "no vm operation" : |
1293 VM_Operation::name(sstats->_vmop_type), | |
1294 sstats->_nof_total_threads, | |
1295 sstats->_nof_initial_running_threads, | |
1296 sstats->_nof_threads_wait_to_block); | |
1297 // "/ MICROUNITS " is to convert the unit from nanos to millis. | |
1291
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1298 tty->print(" [" |
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1299 INT64_FORMAT_W(6)INT64_FORMAT_W(6) |
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1300 INT64_FORMAT_W(6)INT64_FORMAT_W(6) |
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1301 INT64_FORMAT_W(6)" ] ", |
0 | 1302 sstats->_time_to_spin / MICROUNITS, |
1303 sstats->_time_to_wait_to_block / MICROUNITS, | |
1304 sstats->_time_to_sync / MICROUNITS, | |
1291
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1305 sstats->_time_to_do_cleanups / MICROUNITS, |
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1306 sstats->_time_to_exec_vmop / MICROUNITS); |
0 | 1307 |
1308 if (need_to_track_page_armed_status) { | |
1309 tty->print(INT32_FORMAT" ", sstats->_page_armed); | |
1310 } | |
1311 tty->print_cr(INT32_FORMAT" ", sstats->_nof_threads_hit_page_trap); | |
1312 } | |
1313 } | |
1314 | |
1315 // This method will be called when VM exits. It will first call | |
1316 // print_statistics to print out the rest of the sampling. Then | |
1317 // it tries to summarize the sampling. | |
1318 void SafepointSynchronize::print_stat_on_exit() { | |
1319 if (_safepoint_stats == NULL) return; | |
1320 | |
1321 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; | |
1322 | |
1323 // During VM exit, end_statistics may not get called and in that | |
1324 // case, if the sync time is less than PrintSafepointStatisticsTimeout, | |
1325 // don't print it out. | |
1326 // Approximate the vm op time. | |
1327 _safepoint_stats[_cur_stat_index]._time_to_exec_vmop = | |
1291
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1328 os::javaTimeNanos() - cleanup_end_time; |
0 | 1329 |
1330 if ( PrintSafepointStatisticsTimeout < 0 || | |
1331 spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) { | |
1332 print_statistics(); | |
1333 } | |
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1334 tty->cr(); |
0 | 1335 |
1336 // Print out polling page sampling status. | |
1337 if (!need_to_track_page_armed_status) { | |
1338 if (UseCompilerSafepoints) { | |
1339 tty->print_cr("Polling page always armed"); | |
1340 } | |
1341 } else { | |
1342 tty->print_cr("Defer polling page loop count = %d\n", | |
1343 DeferPollingPageLoopCount); | |
1344 } | |
1345 | |
1346 for (int index = 0; index < VM_Operation::VMOp_Terminating; index++) { | |
1347 if (_safepoint_reasons[index] != 0) { | |
1348 tty->print_cr("%-26s"UINT64_FORMAT_W(10), VM_Operation::name(index), | |
1349 _safepoint_reasons[index]); | |
1350 } | |
1351 } | |
1352 | |
1353 tty->print_cr(UINT64_FORMAT_W(5)" VM operations coalesced during safepoint", | |
1354 _coalesced_vmop_count); | |
1355 tty->print_cr("Maximum sync time "INT64_FORMAT_W(5)" ms", | |
1356 _max_sync_time / MICROUNITS); | |
1291
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1357 tty->print_cr("Maximum vm operation time (except for Exit VM operation) " |
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1358 INT64_FORMAT_W(5)" ms", |
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1359 _max_vmop_time / MICROUNITS); |
0 | 1360 } |
1361 | |
1362 // ------------------------------------------------------------------------------------------------ | |
1363 // Non-product code | |
1364 | |
1365 #ifndef PRODUCT | |
1366 | |
1367 void SafepointSynchronize::print_state() { | |
1368 if (_state == _not_synchronized) { | |
1369 tty->print_cr("not synchronized"); | |
1370 } else if (_state == _synchronizing || _state == _synchronized) { | |
1371 tty->print_cr("State: %s", (_state == _synchronizing) ? "synchronizing" : | |
1372 "synchronized"); | |
1373 | |
1374 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) { | |
1375 cur->safepoint_state()->print(); | |
1376 } | |
1377 } | |
1378 } | |
1379 | |
1380 void SafepointSynchronize::safepoint_msg(const char* format, ...) { | |
1381 if (ShowSafepointMsgs) { | |
1382 va_list ap; | |
1383 va_start(ap, format); | |
1384 tty->vprint_cr(format, ap); | |
1385 va_end(ap); | |
1386 } | |
1387 } | |
1388 | |
1389 #endif // !PRODUCT |