Mercurial > hg > truffle
annotate src/share/vm/runtime/safepoint.cpp @ 12355:cefad50507d8
Merge with hs25-b53
| author | Gilles Duboscq <duboscq@ssw.jku.at> |
|---|---|
| date | Fri, 11 Oct 2013 10:38:03 +0200 |
| parents | 89e4d67fdd2a 268e7a2178d7 |
| children | 6b2d8d20ecbd |
| rev | line source |
|---|---|
| 0 | 1 /* |
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2 * Copyright (c) 1997, 2013, 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" | |
| 44 #include "runtime/osThread.hpp" | |
| 45 #include "runtime/safepoint.hpp" | |
| 46 #include "runtime/signature.hpp" | |
| 47 #include "runtime/stubCodeGenerator.hpp" | |
| 48 #include "runtime/stubRoutines.hpp" | |
| 49 #include "runtime/sweeper.hpp" | |
| 50 #include "runtime/synchronizer.hpp" | |
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51 #include "runtime/thread.inline.hpp" |
| 6197 | 52 #include "services/memTracker.hpp" |
| 1972 | 53 #include "services/runtimeService.hpp" |
| 54 #include "utilities/events.hpp" | |
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55 #include "utilities/macros.hpp" |
| 1972 | 56 #ifdef TARGET_ARCH_x86 |
| 57 # include "nativeInst_x86.hpp" | |
| 58 # include "vmreg_x86.inline.hpp" | |
| 59 #endif | |
| 60 #ifdef TARGET_ARCH_sparc | |
| 61 # include "nativeInst_sparc.hpp" | |
| 62 # include "vmreg_sparc.inline.hpp" | |
| 63 #endif | |
| 64 #ifdef TARGET_ARCH_zero | |
| 65 # include "nativeInst_zero.hpp" | |
| 66 # include "vmreg_zero.inline.hpp" | |
| 67 #endif | |
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68 #ifdef TARGET_ARCH_arm |
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69 # include "nativeInst_arm.hpp" |
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70 # include "vmreg_arm.inline.hpp" |
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71 #endif |
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72 #ifdef TARGET_ARCH_ppc |
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73 # include "nativeInst_ppc.hpp" |
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74 # include "vmreg_ppc.inline.hpp" |
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75 #endif |
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76 #if INCLUDE_ALL_GCS |
| 1972 | 77 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp" |
| 78 #include "gc_implementation/shared/concurrentGCThread.hpp" | |
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79 #endif // INCLUDE_ALL_GCS |
| 1972 | 80 #ifdef COMPILER1 |
| 81 #include "c1/c1_globals.hpp" | |
| 82 #endif | |
| 0 | 83 |
| 84 // -------------------------------------------------------------------------------------------------- | |
| 85 // Implementation of Safepoint begin/end | |
| 86 | |
| 87 SafepointSynchronize::SynchronizeState volatile SafepointSynchronize::_state = SafepointSynchronize::_not_synchronized; | |
| 88 volatile int SafepointSynchronize::_waiting_to_block = 0; | |
| 89 volatile int SafepointSynchronize::_safepoint_counter = 0; | |
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90 int SafepointSynchronize::_current_jni_active_count = 0; |
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91 long SafepointSynchronize::_end_of_last_safepoint = 0; |
| 0 | 92 static volatile int PageArmed = 0 ; // safepoint polling page is RO|RW vs PROT_NONE |
| 93 static volatile int TryingToBlock = 0 ; // proximate value -- for advisory use only | |
| 94 static bool timeout_error_printed = false; | |
| 95 | |
| 96 // Roll all threads forward to a safepoint and suspend them all | |
| 97 void SafepointSynchronize::begin() { | |
| 98 | |
| 99 Thread* myThread = Thread::current(); | |
| 100 assert(myThread->is_VM_thread(), "Only VM thread may execute a safepoint"); | |
| 101 | |
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102 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) { |
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103 _safepoint_begin_time = os::javaTimeNanos(); |
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104 _ts_of_current_safepoint = tty->time_stamp().seconds(); |
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105 } |
| 0 | 106 |
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107 #if INCLUDE_ALL_GCS |
| 0 | 108 if (UseConcMarkSweepGC) { |
| 109 // In the future we should investigate whether CMS can use the | |
| 110 // more-general mechanism below. DLD (01/05). | |
| 111 ConcurrentMarkSweepThread::synchronize(false); | |
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112 } else if (UseG1GC) { |
| 0 | 113 ConcurrentGCThread::safepoint_synchronize(); |
| 114 } | |
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115 #endif // INCLUDE_ALL_GCS |
| 0 | 116 |
| 117 // By getting the Threads_lock, we assure that no threads are about to start or | |
| 118 // exit. It is released again in SafepointSynchronize::end(). | |
| 119 Threads_lock->lock(); | |
| 120 | |
| 121 assert( _state == _not_synchronized, "trying to safepoint synchronize with wrong state"); | |
| 122 | |
| 123 int nof_threads = Threads::number_of_threads(); | |
| 124 | |
| 125 if (TraceSafepoint) { | |
| 126 tty->print_cr("Safepoint synchronization initiated. (%d)", nof_threads); | |
| 127 } | |
| 128 | |
| 129 RuntimeService::record_safepoint_begin(); | |
| 130 | |
| 131 MutexLocker mu(Safepoint_lock); | |
| 132 | |
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133 // Reset the count of active JNI critical threads |
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134 _current_jni_active_count = 0; |
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135 |
| 0 | 136 // Set number of threads to wait for, before we initiate the callbacks |
| 137 _waiting_to_block = nof_threads; | |
| 138 TryingToBlock = 0 ; | |
| 139 int still_running = nof_threads; | |
| 140 | |
| 141 // Save the starting time, so that it can be compared to see if this has taken | |
| 142 // too long to complete. | |
| 143 jlong safepoint_limit_time; | |
| 144 timeout_error_printed = false; | |
| 145 | |
| 1003 | 146 // PrintSafepointStatisticsTimeout can be specified separately. When |
| 147 // specified, PrintSafepointStatistics will be set to true in | |
| 148 // deferred_initialize_stat method. The initialization has to be done | |
| 149 // early enough to avoid any races. See bug 6880029 for details. | |
| 150 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) { | |
| 151 deferred_initialize_stat(); | |
| 152 } | |
| 153 | |
| 0 | 154 // Begin the process of bringing the system to a safepoint. |
| 155 // Java threads can be in several different states and are | |
| 156 // stopped by different mechanisms: | |
| 157 // | |
| 158 // 1. Running interpreted | |
| 159 // The interpeter dispatch table is changed to force it to | |
| 160 // check for a safepoint condition between bytecodes. | |
| 161 // 2. Running in native code | |
| 162 // When returning from the native code, a Java thread must check | |
| 163 // the safepoint _state to see if we must block. If the | |
| 164 // VM thread sees a Java thread in native, it does | |
| 165 // not wait for this thread to block. The order of the memory | |
| 166 // writes and reads of both the safepoint state and the Java | |
| 167 // threads state is critical. In order to guarantee that the | |
| 168 // memory writes are serialized with respect to each other, | |
| 169 // the VM thread issues a memory barrier instruction | |
| 170 // (on MP systems). In order to avoid the overhead of issuing | |
| 171 // a memory barrier for each Java thread making native calls, each Java | |
| 172 // thread performs a write to a single memory page after changing | |
| 173 // the thread state. The VM thread performs a sequence of | |
| 174 // mprotect OS calls which forces all previous writes from all | |
| 175 // Java threads to be serialized. This is done in the | |
| 176 // os::serialize_thread_states() call. This has proven to be | |
| 177 // much more efficient than executing a membar instruction | |
| 178 // on every call to native code. | |
| 179 // 3. Running compiled Code | |
| 180 // Compiled code reads a global (Safepoint Polling) page that | |
| 181 // is set to fault if we are trying to get to a safepoint. | |
| 182 // 4. Blocked | |
| 183 // A thread which is blocked will not be allowed to return from the | |
| 184 // block condition until the safepoint operation is complete. | |
| 185 // 5. In VM or Transitioning between states | |
| 186 // If a Java thread is currently running in the VM or transitioning | |
| 187 // between states, the safepointing code will wait for the thread to | |
| 188 // block itself when it attempts transitions to a new state. | |
| 189 // | |
| 190 _state = _synchronizing; | |
| 191 OrderAccess::fence(); | |
| 192 | |
| 193 // Flush all thread states to memory | |
| 194 if (!UseMembar) { | |
| 195 os::serialize_thread_states(); | |
| 196 } | |
| 197 | |
| 198 // Make interpreter safepoint aware | |
| 199 Interpreter::notice_safepoints(); | |
| 200 | |
| 201 if (UseCompilerSafepoints && DeferPollingPageLoopCount < 0) { | |
| 202 // Make polling safepoint aware | |
| 203 guarantee (PageArmed == 0, "invariant") ; | |
| 204 PageArmed = 1 ; | |
| 205 os::make_polling_page_unreadable(); | |
| 206 } | |
| 207 | |
| 208 // Consider using active_processor_count() ... but that call is expensive. | |
| 209 int ncpus = os::processor_count() ; | |
| 210 | |
| 211 #ifdef ASSERT | |
| 212 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) { | |
| 213 assert(cur->safepoint_state()->is_running(), "Illegal initial state"); | |
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214 // Clear the visited flag to ensure that the critical counts are collected properly. |
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215 cur->set_visited_for_critical_count(false); |
| 0 | 216 } |
| 217 #endif // ASSERT | |
| 218 | |
| 219 if (SafepointTimeout) | |
| 220 safepoint_limit_time = os::javaTimeNanos() + (jlong)SafepointTimeoutDelay * MICROUNITS; | |
| 221 | |
| 222 // Iterate through all threads until it have been determined how to stop them all at a safepoint | |
| 223 unsigned int iterations = 0; | |
| 224 int steps = 0 ; | |
| 225 while(still_running > 0) { | |
| 226 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) { | |
| 227 assert(!cur->is_ConcurrentGC_thread(), "A concurrent GC thread is unexpectly being suspended"); | |
| 228 ThreadSafepointState *cur_state = cur->safepoint_state(); | |
| 229 if (cur_state->is_running()) { | |
| 230 cur_state->examine_state_of_thread(); | |
| 231 if (!cur_state->is_running()) { | |
| 232 still_running--; | |
| 233 // consider adjusting steps downward: | |
| 234 // steps = 0 | |
| 235 // steps -= NNN | |
| 236 // steps >>= 1 | |
| 237 // steps = MIN(steps, 2000-100) | |
| 238 // if (iterations != 0) steps -= NNN | |
| 239 } | |
| 240 if (TraceSafepoint && Verbose) cur_state->print(); | |
| 241 } | |
| 242 } | |
| 243 | |
| 1003 | 244 if (PrintSafepointStatistics && iterations == 0) { |
| 0 | 245 begin_statistics(nof_threads, still_running); |
| 246 } | |
| 247 | |
| 248 if (still_running > 0) { | |
| 249 // Check for if it takes to long | |
| 250 if (SafepointTimeout && safepoint_limit_time < os::javaTimeNanos()) { | |
| 251 print_safepoint_timeout(_spinning_timeout); | |
| 252 } | |
| 253 | |
| 254 // Spin to avoid context switching. | |
| 255 // There's a tension between allowing the mutators to run (and rendezvous) | |
| 256 // vs spinning. As the VM thread spins, wasting cycles, it consumes CPU that | |
| 257 // a mutator might otherwise use profitably to reach a safepoint. Excessive | |
| 258 // spinning by the VM thread on a saturated system can increase rendezvous latency. | |
| 259 // Blocking or yielding incur their own penalties in the form of context switching | |
| 260 // and the resultant loss of $ residency. | |
| 261 // | |
| 262 // Further complicating matters is that yield() does not work as naively expected | |
| 263 // on many platforms -- yield() does not guarantee that any other ready threads | |
| 264 // will run. As such we revert yield_all() after some number of iterations. | |
| 265 // Yield_all() is implemented as a short unconditional sleep on some platforms. | |
| 266 // Typical operating systems round a "short" sleep period up to 10 msecs, so sleeping | |
| 267 // can actually increase the time it takes the VM thread to detect that a system-wide | |
| 268 // stop-the-world safepoint has been reached. In a pathological scenario such as that | |
| 269 // described in CR6415670 the VMthread may sleep just before the mutator(s) become safe. | |
| 270 // In that case the mutators will be stalled waiting for the safepoint to complete and the | |
| 271 // the VMthread will be sleeping, waiting for the mutators to rendezvous. The VMthread | |
| 272 // will eventually wake up and detect that all mutators are safe, at which point | |
| 273 // we'll again make progress. | |
| 274 // | |
| 275 // Beware too that that the VMThread typically runs at elevated priority. | |
| 276 // Its default priority is higher than the default mutator priority. | |
| 277 // Obviously, this complicates spinning. | |
| 278 // | |
| 279 // Note too that on Windows XP SwitchThreadTo() has quite different behavior than Sleep(0). | |
| 280 // Sleep(0) will _not yield to lower priority threads, while SwitchThreadTo() will. | |
| 281 // | |
| 282 // See the comments in synchronizer.cpp for additional remarks on spinning. | |
| 283 // | |
| 284 // In the future we might: | |
| 285 // 1. Modify the safepoint scheme to avoid potentally unbounded spinning. | |
| 286 // This is tricky as the path used by a thread exiting the JVM (say on | |
| 287 // on JNI call-out) simply stores into its state field. The burden | |
| 288 // is placed on the VM thread, which must poll (spin). | |
| 289 // 2. Find something useful to do while spinning. If the safepoint is GC-related | |
| 290 // we might aggressively scan the stacks of threads that are already safe. | |
| 291 // 3. Use Solaris schedctl to examine the state of the still-running mutators. | |
| 292 // If all the mutators are ONPROC there's no reason to sleep or yield. | |
| 293 // 4. YieldTo() any still-running mutators that are ready but OFFPROC. | |
| 294 // 5. Check system saturation. If the system is not fully saturated then | |
| 295 // simply spin and avoid sleep/yield. | |
| 296 // 6. As still-running mutators rendezvous they could unpark the sleeping | |
| 297 // VMthread. This works well for still-running mutators that become | |
| 298 // safe. The VMthread must still poll for mutators that call-out. | |
| 299 // 7. Drive the policy on time-since-begin instead of iterations. | |
| 300 // 8. Consider making the spin duration a function of the # of CPUs: | |
| 301 // Spin = (((ncpus-1) * M) + K) + F(still_running) | |
| 302 // Alternately, instead of counting iterations of the outer loop | |
| 303 // we could count the # of threads visited in the inner loop, above. | |
| 304 // 9. On windows consider using the return value from SwitchThreadTo() | |
| 305 // to drive subsequent spin/SwitchThreadTo()/Sleep(N) decisions. | |
| 306 | |
| 307 if (UseCompilerSafepoints && int(iterations) == DeferPollingPageLoopCount) { | |
| 308 guarantee (PageArmed == 0, "invariant") ; | |
| 309 PageArmed = 1 ; | |
| 310 os::make_polling_page_unreadable(); | |
| 311 } | |
| 312 | |
| 313 // Instead of (ncpus > 1) consider either (still_running < (ncpus + EPSILON)) or | |
| 314 // ((still_running + _waiting_to_block - TryingToBlock)) < ncpus) | |
| 315 ++steps ; | |
| 316 if (ncpus > 1 && steps < SafepointSpinBeforeYield) { | |
| 317 SpinPause() ; // MP-Polite spin | |
| 318 } else | |
| 319 if (steps < DeferThrSuspendLoopCount) { | |
| 320 os::NakedYield() ; | |
| 321 } else { | |
| 322 os::yield_all(steps) ; | |
| 323 // Alternately, the VM thread could transiently depress its scheduling priority or | |
| 324 // transiently increase the priority of the tardy mutator(s). | |
| 325 } | |
| 326 | |
| 327 iterations ++ ; | |
| 328 } | |
| 329 assert(iterations < (uint)max_jint, "We have been iterating in the safepoint loop too long"); | |
| 330 } | |
| 331 assert(still_running == 0, "sanity check"); | |
| 332 | |
| 333 if (PrintSafepointStatistics) { | |
| 334 update_statistics_on_spin_end(); | |
| 335 } | |
| 336 | |
| 337 // wait until all threads are stopped | |
| 338 while (_waiting_to_block > 0) { | |
| 339 if (TraceSafepoint) tty->print_cr("Waiting for %d thread(s) to block", _waiting_to_block); | |
| 340 if (!SafepointTimeout || timeout_error_printed) { | |
| 341 Safepoint_lock->wait(true); // true, means with no safepoint checks | |
| 342 } else { | |
| 343 // Compute remaining time | |
| 344 jlong remaining_time = safepoint_limit_time - os::javaTimeNanos(); | |
| 345 | |
| 346 // If there is no remaining time, then there is an error | |
| 347 if (remaining_time < 0 || Safepoint_lock->wait(true, remaining_time / MICROUNITS)) { | |
| 348 print_safepoint_timeout(_blocking_timeout); | |
| 349 } | |
| 350 } | |
| 351 } | |
| 352 assert(_waiting_to_block == 0, "sanity check"); | |
| 353 | |
| 354 #ifndef PRODUCT | |
| 355 if (SafepointTimeout) { | |
| 356 jlong current_time = os::javaTimeNanos(); | |
| 357 if (safepoint_limit_time < current_time) { | |
| 358 tty->print_cr("# SafepointSynchronize: Finished after " | |
| 359 INT64_FORMAT_W(6) " ms", | |
| 360 ((current_time - safepoint_limit_time) / MICROUNITS + | |
| 361 SafepointTimeoutDelay)); | |
| 362 } | |
| 363 } | |
| 364 #endif | |
| 365 | |
| 366 assert((_safepoint_counter & 0x1) == 0, "must be even"); | |
| 367 assert(Threads_lock->owned_by_self(), "must hold Threads_lock"); | |
| 368 _safepoint_counter ++; | |
| 369 | |
| 370 // Record state | |
| 371 _state = _synchronized; | |
| 372 | |
| 373 OrderAccess::fence(); | |
| 374 | |
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375 #ifdef ASSERT |
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376 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) { |
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377 // make sure all the threads were visited |
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378 assert(cur->was_visited_for_critical_count(), "missed a thread"); |
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379 } |
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380 #endif // ASSERT |
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381 |
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382 // Update the count of active JNI critical regions |
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383 GC_locker::set_jni_lock_count(_current_jni_active_count); |
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384 |
| 0 | 385 if (TraceSafepoint) { |
| 386 VM_Operation *op = VMThread::vm_operation(); | |
| 387 tty->print_cr("Entering safepoint region: %s", (op != NULL) ? op->name() : "no vm operation"); | |
| 388 } | |
| 389 | |
| 390 RuntimeService::record_safepoint_synchronized(); | |
| 391 if (PrintSafepointStatistics) { | |
| 392 update_statistics_on_sync_end(os::javaTimeNanos()); | |
| 393 } | |
| 394 | |
| 395 // Call stuff that needs to be run when a safepoint is just about to be completed | |
| 396 do_cleanup_tasks(); | |
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397 |
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398 if (PrintSafepointStatistics) { |
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399 // Record how much time spend on the above cleanup tasks |
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400 update_statistics_on_cleanup_end(os::javaTimeNanos()); |
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401 } |
| 0 | 402 } |
| 403 | |
| 404 // Wake up all threads, so they are ready to resume execution after the safepoint | |
| 405 // operation has been carried out | |
| 406 void SafepointSynchronize::end() { | |
| 407 | |
| 408 assert(Threads_lock->owned_by_self(), "must hold Threads_lock"); | |
| 409 assert((_safepoint_counter & 0x1) == 1, "must be odd"); | |
| 410 _safepoint_counter ++; | |
| 411 // memory fence isn't required here since an odd _safepoint_counter | |
| 412 // value can do no harm and a fence is issued below anyway. | |
| 413 | |
| 414 DEBUG_ONLY(Thread* myThread = Thread::current();) | |
| 415 assert(myThread->is_VM_thread(), "Only VM thread can execute a safepoint"); | |
| 416 | |
| 417 if (PrintSafepointStatistics) { | |
| 418 end_statistics(os::javaTimeNanos()); | |
| 419 } | |
| 420 | |
| 421 #ifdef ASSERT | |
| 422 // A pending_exception cannot be installed during a safepoint. The threads | |
| 423 // may install an async exception after they come back from a safepoint into | |
| 424 // pending_exception after they unblock. But that should happen later. | |
| 425 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) { | |
| 426 assert (!(cur->has_pending_exception() && | |
| 427 cur->safepoint_state()->is_at_poll_safepoint()), | |
| 428 "safepoint installed a pending exception"); | |
| 429 } | |
| 430 #endif // ASSERT | |
| 431 | |
| 432 if (PageArmed) { | |
| 433 // Make polling safepoint aware | |
| 434 os::make_polling_page_readable(); | |
| 435 PageArmed = 0 ; | |
| 436 } | |
| 437 | |
| 438 // Remove safepoint check from interpreter | |
| 439 Interpreter::ignore_safepoints(); | |
| 440 | |
| 441 { | |
| 442 MutexLocker mu(Safepoint_lock); | |
| 443 | |
| 444 assert(_state == _synchronized, "must be synchronized before ending safepoint synchronization"); | |
| 445 | |
| 446 // Set to not synchronized, so the threads will not go into the signal_thread_blocked method | |
| 447 // when they get restarted. | |
| 448 _state = _not_synchronized; | |
| 449 OrderAccess::fence(); | |
| 450 | |
| 451 if (TraceSafepoint) { | |
| 452 tty->print_cr("Leaving safepoint region"); | |
| 453 } | |
| 454 | |
| 455 // Start suspended threads | |
| 456 for(JavaThread *current = Threads::first(); current; current = current->next()) { | |
| 605 | 457 // A problem occurring on Solaris is when attempting to restart threads |
| 0 | 458 // the first #cpus - 1 go well, but then the VMThread is preempted when we get |
| 459 // to the next one (since it has been running the longest). We then have | |
| 460 // to wait for a cpu to become available before we can continue restarting | |
| 461 // threads. | |
| 462 // FIXME: This causes the performance of the VM to degrade when active and with | |
| 463 // large numbers of threads. Apparently this is due to the synchronous nature | |
| 464 // of suspending threads. | |
| 465 // | |
| 466 // TODO-FIXME: the comments above are vestigial and no longer apply. | |
| 467 // Furthermore, using solaris' schedctl in this particular context confers no benefit | |
| 468 if (VMThreadHintNoPreempt) { | |
| 469 os::hint_no_preempt(); | |
| 470 } | |
| 471 ThreadSafepointState* cur_state = current->safepoint_state(); | |
| 472 assert(cur_state->type() != ThreadSafepointState::_running, "Thread not suspended at safepoint"); | |
| 473 cur_state->restart(); | |
| 474 assert(cur_state->is_running(), "safepoint state has not been reset"); | |
| 475 } | |
| 476 | |
| 477 RuntimeService::record_safepoint_end(); | |
| 478 | |
| 479 // Release threads lock, so threads can be created/destroyed again. It will also starts all threads | |
| 480 // blocked in signal_thread_blocked | |
| 481 Threads_lock->unlock(); | |
| 482 | |
| 483 } | |
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484 #if INCLUDE_ALL_GCS |
| 0 | 485 // If there are any concurrent GC threads resume them. |
| 486 if (UseConcMarkSweepGC) { | |
| 487 ConcurrentMarkSweepThread::desynchronize(false); | |
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488 } else if (UseG1GC) { |
| 0 | 489 ConcurrentGCThread::safepoint_desynchronize(); |
| 490 } | |
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491 #endif // INCLUDE_ALL_GCS |
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492 // record this time so VMThread can keep track how much time has elasped |
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493 // since last safepoint. |
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494 _end_of_last_safepoint = os::javaTimeMillis(); |
| 0 | 495 } |
| 496 | |
| 497 bool SafepointSynchronize::is_cleanup_needed() { | |
| 498 // Need a safepoint if some inline cache buffers is non-empty | |
| 499 if (!InlineCacheBuffer::is_empty()) return true; | |
| 500 return false; | |
| 501 } | |
| 502 | |
| 503 | |
| 504 | |
| 505 // Various cleaning tasks that should be done periodically at safepoints | |
| 506 void SafepointSynchronize::do_cleanup_tasks() { | |
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507 { |
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508 TraceTime t1("deflating idle monitors", TraceSafepointCleanupTime); |
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509 ObjectSynchronizer::deflate_idle_monitors(); |
| 0 | 510 } |
| 511 | |
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512 { |
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513 TraceTime t2("updating inline caches", TraceSafepointCleanupTime); |
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514 InlineCacheBuffer::update_inline_caches(); |
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515 } |
| 1783 | 516 { |
| 517 TraceTime t3("compilation policy safepoint handler", TraceSafepointCleanupTime); | |
| 518 CompilationPolicy::policy()->do_safepoint_work(); | |
| 0 | 519 } |
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520 |
| 6162 | 521 { |
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522 TraceTime t4("mark nmethods", TraceSafepointCleanupTime); |
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523 NMethodSweeper::mark_active_nmethods(); |
| 6162 | 524 } |
| 525 | |
| 526 if (SymbolTable::needs_rehashing()) { | |
| 527 TraceTime t5("rehashing symbol table", TraceSafepointCleanupTime); | |
| 528 SymbolTable::rehash_table(); | |
| 529 } | |
| 530 | |
| 531 if (StringTable::needs_rehashing()) { | |
| 532 TraceTime t6("rehashing string table", TraceSafepointCleanupTime); | |
| 533 StringTable::rehash_table(); | |
| 534 } | |
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535 |
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536 // rotate log files? |
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537 if (UseGCLogFileRotation) { |
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538 gclog_or_tty->rotate_log(); |
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539 } |
| 6197 | 540 |
| 541 if (MemTracker::is_on()) { | |
| 542 MemTracker::sync(); | |
| 543 } | |
| 0 | 544 } |
| 545 | |
| 546 | |
| 547 bool SafepointSynchronize::safepoint_safe(JavaThread *thread, JavaThreadState state) { | |
| 548 switch(state) { | |
| 549 case _thread_in_native: | |
| 550 // native threads are safe if they have no java stack or have walkable stack | |
| 551 return !thread->has_last_Java_frame() || thread->frame_anchor()->walkable(); | |
| 552 | |
| 553 // blocked threads should have already have walkable stack | |
| 554 case _thread_blocked: | |
| 555 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "blocked and not walkable"); | |
| 556 return true; | |
| 557 | |
| 558 default: | |
| 559 return false; | |
| 560 } | |
| 561 } | |
| 562 | |
| 563 | |
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564 // See if the thread is running inside a lazy critical native and |
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565 // update the thread critical count if so. Also set a suspend flag to |
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566 // cause the native wrapper to return into the JVM to do the unlock |
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567 // once the native finishes. |
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568 void SafepointSynchronize::check_for_lazy_critical_native(JavaThread *thread, JavaThreadState state) { |
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569 if (state == _thread_in_native && |
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570 thread->has_last_Java_frame() && |
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571 thread->frame_anchor()->walkable()) { |
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572 // This thread might be in a critical native nmethod so look at |
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573 // the top of the stack and increment the critical count if it |
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574 // is. |
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575 frame wrapper_frame = thread->last_frame(); |
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576 CodeBlob* stub_cb = wrapper_frame.cb(); |
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577 if (stub_cb != NULL && |
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578 stub_cb->is_nmethod() && |
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579 stub_cb->as_nmethod_or_null()->is_lazy_critical_native()) { |
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580 // A thread could potentially be in a critical native across |
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581 // more than one safepoint, so only update the critical state on |
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582 // the first one. When it returns it will perform the unlock. |
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583 if (!thread->do_critical_native_unlock()) { |
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584 #ifdef ASSERT |
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585 if (!thread->in_critical()) { |
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586 GC_locker::increment_debug_jni_lock_count(); |
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587 } |
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588 #endif |
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589 thread->enter_critical(); |
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590 // Make sure the native wrapper calls back on return to |
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591 // perform the needed critical unlock. |
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592 thread->set_critical_native_unlock(); |
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593 } |
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594 } |
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595 } |
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596 } |
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597 |
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598 |
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599 |
| 0 | 600 // ------------------------------------------------------------------------------------------------------- |
| 601 // Implementation of Safepoint callback point | |
| 602 | |
| 603 void SafepointSynchronize::block(JavaThread *thread) { | |
| 604 assert(thread != NULL, "thread must be set"); | |
| 605 assert(thread->is_Java_thread(), "not a Java thread"); | |
| 606 | |
| 607 // Threads shouldn't block if they are in the middle of printing, but... | |
| 608 ttyLocker::break_tty_lock_for_safepoint(os::current_thread_id()); | |
| 609 | |
| 610 // Only bail from the block() call if the thread is gone from the | |
| 611 // thread list; starting to exit should still block. | |
| 612 if (thread->is_terminated()) { | |
| 613 // block current thread if we come here from native code when VM is gone | |
| 614 thread->block_if_vm_exited(); | |
| 615 | |
| 616 // otherwise do nothing | |
| 617 return; | |
| 618 } | |
| 619 | |
| 620 JavaThreadState state = thread->thread_state(); | |
| 621 thread->frame_anchor()->make_walkable(thread); | |
| 622 | |
| 623 // Check that we have a valid thread_state at this point | |
| 624 switch(state) { | |
| 625 case _thread_in_vm_trans: | |
| 626 case _thread_in_Java: // From compiled code | |
| 627 | |
| 628 // We are highly likely to block on the Safepoint_lock. In order to avoid blocking in this case, | |
| 629 // we pretend we are still in the VM. | |
| 630 thread->set_thread_state(_thread_in_vm); | |
| 631 | |
| 632 if (is_synchronizing()) { | |
| 633 Atomic::inc (&TryingToBlock) ; | |
| 634 } | |
| 635 | |
| 636 // We will always be holding the Safepoint_lock when we are examine the state | |
| 637 // of a thread. Hence, the instructions between the Safepoint_lock->lock() and | |
| 638 // Safepoint_lock->unlock() are happening atomic with regards to the safepoint code | |
| 639 Safepoint_lock->lock_without_safepoint_check(); | |
| 640 if (is_synchronizing()) { | |
| 641 // Decrement the number of threads to wait for and signal vm thread | |
| 642 assert(_waiting_to_block > 0, "sanity check"); | |
| 643 _waiting_to_block--; | |
| 644 thread->safepoint_state()->set_has_called_back(true); | |
| 645 | |
|
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646 DEBUG_ONLY(thread->set_visited_for_critical_count(true)); |
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647 if (thread->in_critical()) { |
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648 // Notice that this thread is in a critical section |
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649 increment_jni_active_count(); |
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650 } |
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651 |
| 0 | 652 // Consider (_waiting_to_block < 2) to pipeline the wakeup of the VM thread |
| 653 if (_waiting_to_block == 0) { | |
| 654 Safepoint_lock->notify_all(); | |
| 655 } | |
| 656 } | |
| 657 | |
| 658 // We transition the thread to state _thread_blocked here, but | |
| 659 // we can't do our usual check for external suspension and then | |
| 660 // self-suspend after the lock_without_safepoint_check() call | |
| 661 // below because we are often called during transitions while | |
| 662 // we hold different locks. That would leave us suspended while | |
| 663 // holding a resource which results in deadlocks. | |
| 664 thread->set_thread_state(_thread_blocked); | |
| 665 Safepoint_lock->unlock(); | |
| 666 | |
| 667 // We now try to acquire the threads lock. Since this lock is hold by the VM thread during | |
| 668 // the entire safepoint, the threads will all line up here during the safepoint. | |
| 669 Threads_lock->lock_without_safepoint_check(); | |
| 670 // restore original state. This is important if the thread comes from compiled code, so it | |
| 671 // will continue to execute with the _thread_in_Java state. | |
| 672 thread->set_thread_state(state); | |
| 673 Threads_lock->unlock(); | |
| 674 break; | |
| 675 | |
| 676 case _thread_in_native_trans: | |
| 677 case _thread_blocked_trans: | |
| 678 case _thread_new_trans: | |
| 679 if (thread->safepoint_state()->type() == ThreadSafepointState::_call_back) { | |
| 680 thread->print_thread_state(); | |
| 681 fatal("Deadlock in safepoint code. " | |
| 682 "Should have called back to the VM before blocking."); | |
| 683 } | |
| 684 | |
| 685 // We transition the thread to state _thread_blocked here, but | |
| 686 // we can't do our usual check for external suspension and then | |
| 687 // self-suspend after the lock_without_safepoint_check() call | |
| 688 // below because we are often called during transitions while | |
| 689 // we hold different locks. That would leave us suspended while | |
| 690 // holding a resource which results in deadlocks. | |
| 691 thread->set_thread_state(_thread_blocked); | |
| 692 | |
| 693 // It is not safe to suspend a thread if we discover it is in _thread_in_native_trans. Hence, | |
| 694 // the safepoint code might still be waiting for it to block. We need to change the state here, | |
| 695 // so it can see that it is at a safepoint. | |
| 696 | |
| 697 // Block until the safepoint operation is completed. | |
| 698 Threads_lock->lock_without_safepoint_check(); | |
| 699 | |
| 700 // Restore state | |
| 701 thread->set_thread_state(state); | |
| 702 | |
| 703 Threads_lock->unlock(); | |
| 704 break; | |
| 705 | |
| 706 default: | |
|
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707 fatal(err_msg("Illegal threadstate encountered: %d", state)); |
| 0 | 708 } |
| 709 | |
| 710 // Check for pending. async. exceptions or suspends - except if the | |
| 711 // thread was blocked inside the VM. has_special_runtime_exit_condition() | |
| 712 // is called last since it grabs a lock and we only want to do that when | |
| 713 // we must. | |
| 714 // | |
| 715 // Note: we never deliver an async exception at a polling point as the | |
| 716 // compiler may not have an exception handler for it. The polling | |
| 717 // code will notice the async and deoptimize and the exception will | |
| 718 // be delivered. (Polling at a return point is ok though). Sure is | |
| 719 // a lot of bother for a deprecated feature... | |
| 720 // | |
| 721 // We don't deliver an async exception if the thread state is | |
| 722 // _thread_in_native_trans so JNI functions won't be called with | |
| 723 // a surprising pending exception. If the thread state is going back to java, | |
| 724 // async exception is checked in check_special_condition_for_native_trans(). | |
| 725 | |
| 726 if (state != _thread_blocked_trans && | |
| 727 state != _thread_in_vm_trans && | |
| 728 thread->has_special_runtime_exit_condition()) { | |
| 729 thread->handle_special_runtime_exit_condition( | |
| 730 !thread->is_at_poll_safepoint() && (state != _thread_in_native_trans)); | |
| 731 } | |
| 732 } | |
| 733 | |
| 734 // ------------------------------------------------------------------------------------------------------ | |
| 735 // Exception handlers | |
| 736 | |
| 737 #ifndef PRODUCT | |
|
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738 |
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739 #ifdef SPARC |
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740 |
| 0 | 741 #ifdef _LP64 |
| 742 #define PTR_PAD "" | |
| 743 #else | |
| 744 #define PTR_PAD " " | |
| 745 #endif | |
| 746 | |
| 747 static void print_ptrs(intptr_t oldptr, intptr_t newptr, bool wasoop) { | |
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748 bool is_oop = newptr ? (cast_to_oop(newptr))->is_oop() : false; |
| 0 | 749 tty->print_cr(PTR_FORMAT PTR_PAD " %s %c " PTR_FORMAT PTR_PAD " %s %s", |
| 750 oldptr, wasoop?"oop":" ", oldptr == newptr ? ' ' : '!', | |
| 751 newptr, is_oop?"oop":" ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":" ")); | |
| 752 } | |
| 753 | |
| 754 static void print_longs(jlong oldptr, jlong newptr, bool wasoop) { | |
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755 bool is_oop = newptr ? (cast_to_oop(newptr))->is_oop() : false; |
| 0 | 756 tty->print_cr(PTR64_FORMAT " %s %c " PTR64_FORMAT " %s %s", |
| 757 oldptr, wasoop?"oop":" ", oldptr == newptr ? ' ' : '!', | |
| 758 newptr, is_oop?"oop":" ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":" ")); | |
| 759 } | |
| 760 | |
| 761 static void print_me(intptr_t *new_sp, intptr_t *old_sp, bool *was_oops) { | |
| 762 #ifdef _LP64 | |
| 763 tty->print_cr("--------+------address-----+------before-----------+-------after----------+"); | |
| 764 const int incr = 1; // Increment to skip a long, in units of intptr_t | |
| 765 #else | |
| 766 tty->print_cr("--------+--address-+------before-----------+-------after----------+"); | |
| 767 const int incr = 2; // Increment to skip a long, in units of intptr_t | |
| 768 #endif | |
| 769 tty->print_cr("---SP---|"); | |
| 770 for( int i=0; i<16; i++ ) { | |
| 771 tty->print("blob %c%d |"PTR_FORMAT" ","LO"[i>>3],i&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); } | |
| 772 tty->print_cr("--------|"); | |
| 773 for( int i1=0; i1<frame::memory_parameter_word_sp_offset-16; i1++ ) { | |
| 774 tty->print("argv pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); } | |
| 775 tty->print(" pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); | |
| 776 tty->print_cr("--------|"); | |
| 777 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; | |
| 778 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; | |
| 779 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; | |
| 780 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; | |
| 781 tty->print_cr(" FSR |"PTR_FORMAT" "PTR64_FORMAT" "PTR64_FORMAT,new_sp,*(jlong*)old_sp,*(jlong*)new_sp); | |
| 782 old_sp += incr; new_sp += incr; was_oops += incr; | |
| 783 // Skip the floats | |
| 784 tty->print_cr("--Float-|"PTR_FORMAT,new_sp); | |
| 785 tty->print_cr("---FP---|"); | |
| 786 old_sp += incr*32; new_sp += incr*32; was_oops += incr*32; | |
| 787 for( int i2=0; i2<16; i2++ ) { | |
| 788 tty->print("call %c%d |"PTR_FORMAT" ","LI"[i2>>3],i2&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); } | |
| 789 tty->print_cr(""); | |
| 790 } | |
| 791 #endif // SPARC | |
| 792 #endif // PRODUCT | |
| 793 | |
| 794 | |
| 795 void SafepointSynchronize::handle_polling_page_exception(JavaThread *thread) { | |
| 796 assert(thread->is_Java_thread(), "polling reference encountered by VM thread"); | |
| 797 assert(thread->thread_state() == _thread_in_Java, "should come from Java code"); | |
| 798 assert(SafepointSynchronize::is_synchronizing(), "polling encountered outside safepoint synchronization"); | |
| 799 | |
| 800 // Uncomment this to get some serious before/after printing of the | |
| 801 // Sparc safepoint-blob frame structure. | |
| 802 /* | |
| 803 intptr_t* sp = thread->last_Java_sp(); | |
| 804 intptr_t stack_copy[150]; | |
| 805 for( int i=0; i<150; i++ ) stack_copy[i] = sp[i]; | |
| 806 bool was_oops[150]; | |
| 807 for( int i=0; i<150; i++ ) | |
| 808 was_oops[i] = stack_copy[i] ? ((oop)stack_copy[i])->is_oop() : false; | |
| 809 */ | |
| 810 | |
| 811 if (ShowSafepointMsgs) { | |
| 812 tty->print("handle_polling_page_exception: "); | |
| 813 } | |
| 814 | |
| 815 if (PrintSafepointStatistics) { | |
| 816 inc_page_trap_count(); | |
| 817 } | |
| 818 | |
| 819 ThreadSafepointState* state = thread->safepoint_state(); | |
| 820 | |
| 821 state->handle_polling_page_exception(); | |
| 822 // print_me(sp,stack_copy,was_oops); | |
| 823 } | |
| 824 | |
| 825 | |
| 826 void SafepointSynchronize::print_safepoint_timeout(SafepointTimeoutReason reason) { | |
| 827 if (!timeout_error_printed) { | |
| 828 timeout_error_printed = true; | |
| 829 // Print out the thread infor which didn't reach the safepoint for debugging | |
| 830 // purposes (useful when there are lots of threads in the debugger). | |
| 831 tty->print_cr(""); | |
| 832 tty->print_cr("# SafepointSynchronize::begin: Timeout detected:"); | |
| 833 if (reason == _spinning_timeout) { | |
| 834 tty->print_cr("# SafepointSynchronize::begin: Timed out while spinning to reach a safepoint."); | |
| 835 } else if (reason == _blocking_timeout) { | |
| 836 tty->print_cr("# SafepointSynchronize::begin: Timed out while waiting for threads to stop."); | |
| 837 } | |
| 838 | |
| 839 tty->print_cr("# SafepointSynchronize::begin: Threads which did not reach the safepoint:"); | |
| 840 ThreadSafepointState *cur_state; | |
| 841 ResourceMark rm; | |
| 842 for(JavaThread *cur_thread = Threads::first(); cur_thread; | |
| 843 cur_thread = cur_thread->next()) { | |
| 844 cur_state = cur_thread->safepoint_state(); | |
| 845 | |
| 846 if (cur_thread->thread_state() != _thread_blocked && | |
| 847 ((reason == _spinning_timeout && cur_state->is_running()) || | |
| 848 (reason == _blocking_timeout && !cur_state->has_called_back()))) { | |
| 849 tty->print("# "); | |
| 850 cur_thread->print(); | |
| 851 tty->print_cr(""); | |
| 852 } | |
| 853 } | |
| 854 tty->print_cr("# SafepointSynchronize::begin: (End of list)"); | |
| 855 } | |
| 856 | |
| 857 // To debug the long safepoint, specify both DieOnSafepointTimeout & | |
| 858 // ShowMessageBoxOnError. | |
| 859 if (DieOnSafepointTimeout) { | |
| 860 char msg[1024]; | |
| 861 VM_Operation *op = VMThread::vm_operation(); | |
|
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862 sprintf(msg, "Safepoint sync time longer than " INTX_FORMAT "ms detected when executing %s.", |
| 0 | 863 SafepointTimeoutDelay, |
| 864 op != NULL ? op->name() : "no vm operation"); | |
| 865 fatal(msg); | |
| 866 } | |
| 867 } | |
| 868 | |
| 869 | |
| 870 // ------------------------------------------------------------------------------------------------------- | |
| 871 // Implementation of ThreadSafepointState | |
| 872 | |
| 873 ThreadSafepointState::ThreadSafepointState(JavaThread *thread) { | |
| 874 _thread = thread; | |
| 875 _type = _running; | |
| 876 _has_called_back = false; | |
| 877 _at_poll_safepoint = false; | |
| 878 } | |
| 879 | |
| 880 void ThreadSafepointState::create(JavaThread *thread) { | |
| 881 ThreadSafepointState *state = new ThreadSafepointState(thread); | |
| 882 thread->set_safepoint_state(state); | |
| 883 } | |
| 884 | |
| 885 void ThreadSafepointState::destroy(JavaThread *thread) { | |
| 886 if (thread->safepoint_state()) { | |
| 887 delete(thread->safepoint_state()); | |
| 888 thread->set_safepoint_state(NULL); | |
| 889 } | |
| 890 } | |
| 891 | |
| 892 void ThreadSafepointState::examine_state_of_thread() { | |
| 893 assert(is_running(), "better be running or just have hit safepoint poll"); | |
| 894 | |
| 895 JavaThreadState state = _thread->thread_state(); | |
| 896 | |
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897 // Save the state at the start of safepoint processing. |
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898 _orig_thread_state = state; |
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899 |
| 0 | 900 // Check for a thread that is suspended. Note that thread resume tries |
| 901 // to grab the Threads_lock which we own here, so a thread cannot be | |
| 902 // resumed during safepoint synchronization. | |
| 903 | |
| 979 | 904 // We check to see if this thread is suspended without locking to |
| 905 // avoid deadlocking with a third thread that is waiting for this | |
| 906 // thread to be suspended. The third thread can notice the safepoint | |
| 907 // that we're trying to start at the beginning of its SR_lock->wait() | |
| 908 // call. If that happens, then the third thread will block on the | |
| 909 // safepoint while still holding the underlying SR_lock. We won't be | |
| 910 // able to get the SR_lock and we'll deadlock. | |
| 911 // | |
| 912 // We don't need to grab the SR_lock here for two reasons: | |
| 913 // 1) The suspend flags are both volatile and are set with an | |
| 914 // Atomic::cmpxchg() call so we should see the suspended | |
| 915 // state right away. | |
| 916 // 2) We're being called from the safepoint polling loop; if | |
| 917 // we don't see the suspended state on this iteration, then | |
| 918 // we'll come around again. | |
| 919 // | |
| 920 bool is_suspended = _thread->is_ext_suspended(); | |
| 0 | 921 if (is_suspended) { |
| 922 roll_forward(_at_safepoint); | |
| 923 return; | |
| 924 } | |
| 925 | |
| 926 // Some JavaThread states have an initial safepoint state of | |
| 927 // running, but are actually at a safepoint. We will happily | |
| 928 // agree and update the safepoint state here. | |
| 929 if (SafepointSynchronize::safepoint_safe(_thread, state)) { | |
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930 SafepointSynchronize::check_for_lazy_critical_native(_thread, state); |
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931 roll_forward(_at_safepoint); |
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932 return; |
| 0 | 933 } |
| 934 | |
| 935 if (state == _thread_in_vm) { | |
| 936 roll_forward(_call_back); | |
| 937 return; | |
| 938 } | |
| 939 | |
| 940 // All other thread states will continue to run until they | |
| 941 // transition and self-block in state _blocked | |
| 942 // Safepoint polling in compiled code causes the Java threads to do the same. | |
| 943 // Note: new threads may require a malloc so they must be allowed to finish | |
| 944 | |
| 945 assert(is_running(), "examine_state_of_thread on non-running thread"); | |
| 946 return; | |
| 947 } | |
| 948 | |
| 949 // Returns true is thread could not be rolled forward at present position. | |
| 950 void ThreadSafepointState::roll_forward(suspend_type type) { | |
| 951 _type = type; | |
| 952 | |
| 953 switch(_type) { | |
| 954 case _at_safepoint: | |
| 955 SafepointSynchronize::signal_thread_at_safepoint(); | |
|
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956 DEBUG_ONLY(_thread->set_visited_for_critical_count(true)); |
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957 if (_thread->in_critical()) { |
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958 // Notice that this thread is in a critical section |
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959 SafepointSynchronize::increment_jni_active_count(); |
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960 } |
| 0 | 961 break; |
| 962 | |
| 963 case _call_back: | |
| 964 set_has_called_back(false); | |
| 965 break; | |
| 966 | |
| 967 case _running: | |
| 968 default: | |
| 969 ShouldNotReachHere(); | |
| 970 } | |
| 971 } | |
| 972 | |
| 973 void ThreadSafepointState::restart() { | |
| 974 switch(type()) { | |
| 975 case _at_safepoint: | |
| 976 case _call_back: | |
| 977 break; | |
| 978 | |
| 979 case _running: | |
| 980 default: | |
| 981 tty->print_cr("restart thread "INTPTR_FORMAT" with state %d", | |
| 982 _thread, _type); | |
| 983 _thread->print(); | |
| 984 ShouldNotReachHere(); | |
| 985 } | |
| 986 _type = _running; | |
| 987 set_has_called_back(false); | |
| 988 } | |
| 989 | |
| 990 | |
| 991 void ThreadSafepointState::print_on(outputStream *st) const { | |
| 992 const char *s; | |
| 993 | |
| 994 switch(_type) { | |
| 995 case _running : s = "_running"; break; | |
| 996 case _at_safepoint : s = "_at_safepoint"; break; | |
| 997 case _call_back : s = "_call_back"; break; | |
| 998 default: | |
| 999 ShouldNotReachHere(); | |
| 1000 } | |
| 1001 | |
| 1002 st->print_cr("Thread: " INTPTR_FORMAT | |
| 1003 " [0x%2x] State: %s _has_called_back %d _at_poll_safepoint %d", | |
| 1004 _thread, _thread->osthread()->thread_id(), s, _has_called_back, | |
| 1005 _at_poll_safepoint); | |
| 1006 | |
| 1007 _thread->print_thread_state_on(st); | |
| 1008 } | |
| 1009 | |
| 1010 | |
| 1011 // --------------------------------------------------------------------------------------------------------------------- | |
| 1012 | |
| 1013 // Block the thread at the safepoint poll or poll return. | |
| 1014 void ThreadSafepointState::handle_polling_page_exception() { | |
| 1015 | |
| 1016 // Check state. block() will set thread state to thread_in_vm which will | |
| 1017 // cause the safepoint state _type to become _call_back. | |
| 1018 assert(type() == ThreadSafepointState::_running, | |
| 1019 "polling page exception on thread not running state"); | |
| 1020 | |
| 1021 // Step 1: Find the nmethod from the return address | |
| 1022 if (ShowSafepointMsgs && Verbose) { | |
| 1023 tty->print_cr("Polling page exception at " INTPTR_FORMAT, thread()->saved_exception_pc()); | |
| 1024 } | |
| 1025 address real_return_addr = thread()->saved_exception_pc(); | |
| 1026 | |
| 1027 CodeBlob *cb = CodeCache::find_blob(real_return_addr); | |
| 1028 assert(cb != NULL && cb->is_nmethod(), "return address should be in nmethod"); | |
| 1029 nmethod* nm = (nmethod*)cb; | |
| 1030 | |
| 1031 // Find frame of caller | |
| 1032 frame stub_fr = thread()->last_frame(); | |
| 1033 CodeBlob* stub_cb = stub_fr.cb(); | |
| 1034 assert(stub_cb->is_safepoint_stub(), "must be a safepoint stub"); | |
| 1035 RegisterMap map(thread(), true); | |
| 1036 frame caller_fr = stub_fr.sender(&map); | |
| 1037 | |
| 1038 // Should only be poll_return or poll | |
| 1039 assert( nm->is_at_poll_or_poll_return(real_return_addr), "should not be at call" ); | |
| 1040 | |
| 1041 // This is a poll immediately before a return. The exception handling code | |
| 1042 // has already had the effect of causing the return to occur, so the execution | |
| 1043 // will continue immediately after the call. In addition, the oopmap at the | |
| 1044 // return point does not mark the return value as an oop (if it is), so | |
| 1045 // it needs a handle here to be updated. | |
| 1046 if( nm->is_at_poll_return(real_return_addr) ) { | |
| 1047 // See if return type is an oop. | |
| 1048 bool return_oop = nm->method()->is_returning_oop(); | |
| 1049 Handle return_value; | |
| 1050 if (return_oop) { | |
| 1051 // The oop result has been saved on the stack together with all | |
| 1052 // the other registers. In order to preserve it over GCs we need | |
| 1053 // to keep it in a handle. | |
| 1054 oop result = caller_fr.saved_oop_result(&map); | |
| 1055 assert(result == NULL || result->is_oop(), "must be oop"); | |
| 1056 return_value = Handle(thread(), result); | |
| 1057 assert(Universe::heap()->is_in_or_null(result), "must be heap pointer"); | |
| 1058 } | |
| 1059 | |
| 1060 // Block the thread | |
| 1061 SafepointSynchronize::block(thread()); | |
| 1062 | |
| 1063 // restore oop result, if any | |
| 1064 if (return_oop) { | |
| 1065 caller_fr.set_saved_oop_result(&map, return_value()); | |
| 1066 } | |
| 1067 } | |
| 1068 | |
| 1069 // This is a safepoint poll. Verify the return address and block. | |
| 1070 else { | |
| 1071 set_at_poll_safepoint(true); | |
| 1072 | |
| 1073 // verify the blob built the "return address" correctly | |
| 1074 assert(real_return_addr == caller_fr.pc(), "must match"); | |
| 1075 | |
| 1076 // Block the thread | |
| 1077 SafepointSynchronize::block(thread()); | |
| 1078 set_at_poll_safepoint(false); | |
| 1079 | |
| 1080 // If we have a pending async exception deoptimize the frame | |
| 1081 // as otherwise we may never deliver it. | |
| 1082 if (thread()->has_async_condition()) { | |
| 1083 ThreadInVMfromJavaNoAsyncException __tiv(thread()); | |
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1084 Deoptimization::deoptimize_frame(thread(), caller_fr.id(), Deoptimization::Reason_constraint); |
| 0 | 1085 } |
| 1086 | |
| 1087 // If an exception has been installed we must check for a pending deoptimization | |
| 1088 // Deoptimize frame if exception has been thrown. | |
| 1089 | |
| 1090 if (thread()->has_pending_exception() ) { | |
| 1091 RegisterMap map(thread(), true); | |
| 1092 frame caller_fr = stub_fr.sender(&map); | |
| 1093 if (caller_fr.is_deoptimized_frame()) { | |
| 1094 // The exception patch will destroy registers that are still | |
| 1095 // live and will be needed during deoptimization. Defer the | |
| 1096 // Async exception should have defered the exception until the | |
| 1097 // next safepoint which will be detected when we get into | |
| 1098 // the interpreter so if we have an exception now things | |
| 1099 // are messed up. | |
| 1100 | |
| 1101 fatal("Exception installed and deoptimization is pending"); | |
| 1102 } | |
| 1103 } | |
| 1104 } | |
| 1105 } | |
| 1106 | |
| 1107 | |
| 1108 // | |
| 1109 // Statistics & Instrumentations | |
| 1110 // | |
| 1111 SafepointSynchronize::SafepointStats* SafepointSynchronize::_safepoint_stats = NULL; | |
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1112 jlong SafepointSynchronize::_safepoint_begin_time = 0; |
| 0 | 1113 int SafepointSynchronize::_cur_stat_index = 0; |
| 1114 julong SafepointSynchronize::_safepoint_reasons[VM_Operation::VMOp_Terminating]; | |
| 1115 julong SafepointSynchronize::_coalesced_vmop_count = 0; | |
| 1116 jlong SafepointSynchronize::_max_sync_time = 0; | |
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1117 jlong SafepointSynchronize::_max_vmop_time = 0; |
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1118 float SafepointSynchronize::_ts_of_current_safepoint = 0.0f; |
| 0 | 1119 |
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1120 static jlong cleanup_end_time = 0; |
| 0 | 1121 static bool need_to_track_page_armed_status = false; |
| 1122 static bool init_done = false; | |
| 1123 | |
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1124 // Helper method to print the header. |
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1125 static void print_header() { |
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1126 tty->print(" vmop " |
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1127 "[threads: total initially_running wait_to_block] "); |
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1128 tty->print("[time: spin block sync cleanup vmop] "); |
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1129 |
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1130 // no page armed status printed out if it is always armed. |
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1131 if (need_to_track_page_armed_status) { |
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1132 tty->print("page_armed "); |
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1133 } |
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1134 |
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1135 tty->print_cr("page_trap_count"); |
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1136 } |
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1137 |
| 0 | 1138 void SafepointSynchronize::deferred_initialize_stat() { |
| 1139 if (init_done) return; | |
| 1140 | |
| 1141 if (PrintSafepointStatisticsCount <= 0) { | |
| 1142 fatal("Wrong PrintSafepointStatisticsCount"); | |
| 1143 } | |
| 1144 | |
| 1145 // If PrintSafepointStatisticsTimeout is specified, the statistics data will | |
| 1146 // be printed right away, in which case, _safepoint_stats will regress to | |
| 1147 // a single element array. Otherwise, it is a circular ring buffer with default | |
| 1148 // size of PrintSafepointStatisticsCount. | |
| 1149 int stats_array_size; | |
| 1150 if (PrintSafepointStatisticsTimeout > 0) { | |
| 1151 stats_array_size = 1; | |
| 1152 PrintSafepointStatistics = true; | |
| 1153 } else { | |
| 1154 stats_array_size = PrintSafepointStatisticsCount; | |
| 1155 } | |
| 1156 _safepoint_stats = (SafepointStats*)os::malloc(stats_array_size | |
| 6197 | 1157 * sizeof(SafepointStats), mtInternal); |
| 0 | 1158 guarantee(_safepoint_stats != NULL, |
| 1159 "not enough memory for safepoint instrumentation data"); | |
| 1160 | |
| 1161 if (UseCompilerSafepoints && DeferPollingPageLoopCount >= 0) { | |
| 1162 need_to_track_page_armed_status = true; | |
| 1163 } | |
| 1164 init_done = true; | |
| 1165 } | |
| 1166 | |
| 1167 void SafepointSynchronize::begin_statistics(int nof_threads, int nof_running) { | |
| 1003 | 1168 assert(init_done, "safepoint statistics array hasn't been initialized"); |
| 0 | 1169 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; |
| 1170 | |
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1171 spstat->_time_stamp = _ts_of_current_safepoint; |
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1172 |
| 0 | 1173 VM_Operation *op = VMThread::vm_operation(); |
| 1174 spstat->_vmop_type = (op != NULL ? op->type() : -1); | |
| 1175 if (op != NULL) { | |
| 1176 _safepoint_reasons[spstat->_vmop_type]++; | |
| 1177 } | |
| 1178 | |
| 1179 spstat->_nof_total_threads = nof_threads; | |
| 1180 spstat->_nof_initial_running_threads = nof_running; | |
| 1181 spstat->_nof_threads_hit_page_trap = 0; | |
| 1182 | |
| 1183 // Records the start time of spinning. The real time spent on spinning | |
| 1184 // will be adjusted when spin is done. Same trick is applied for time | |
| 1185 // spent on waiting for threads to block. | |
| 1186 if (nof_running != 0) { | |
| 1187 spstat->_time_to_spin = os::javaTimeNanos(); | |
| 1188 } else { | |
| 1189 spstat->_time_to_spin = 0; | |
| 1190 } | |
| 1191 } | |
| 1192 | |
| 1193 void SafepointSynchronize::update_statistics_on_spin_end() { | |
| 1194 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; | |
| 1195 | |
| 1196 jlong cur_time = os::javaTimeNanos(); | |
| 1197 | |
| 1198 spstat->_nof_threads_wait_to_block = _waiting_to_block; | |
| 1199 if (spstat->_nof_initial_running_threads != 0) { | |
| 1200 spstat->_time_to_spin = cur_time - spstat->_time_to_spin; | |
| 1201 } | |
| 1202 | |
| 1203 if (need_to_track_page_armed_status) { | |
| 1204 spstat->_page_armed = (PageArmed == 1); | |
| 1205 } | |
| 1206 | |
| 1207 // Records the start time of waiting for to block. Updated when block is done. | |
| 1208 if (_waiting_to_block != 0) { | |
| 1209 spstat->_time_to_wait_to_block = cur_time; | |
| 1210 } else { | |
| 1211 spstat->_time_to_wait_to_block = 0; | |
| 1212 } | |
| 1213 } | |
| 1214 | |
| 1215 void SafepointSynchronize::update_statistics_on_sync_end(jlong end_time) { | |
| 1216 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; | |
| 1217 | |
| 1218 if (spstat->_nof_threads_wait_to_block != 0) { | |
| 1219 spstat->_time_to_wait_to_block = end_time - | |
| 1220 spstat->_time_to_wait_to_block; | |
| 1221 } | |
| 1222 | |
| 1223 // Records the end time of sync which will be used to calculate the total | |
| 1224 // vm operation time. Again, the real time spending in syncing will be deducted | |
| 1225 // from the start of the sync time later when end_statistics is called. | |
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1226 spstat->_time_to_sync = end_time - _safepoint_begin_time; |
| 0 | 1227 if (spstat->_time_to_sync > _max_sync_time) { |
| 1228 _max_sync_time = spstat->_time_to_sync; | |
| 1229 } | |
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1230 |
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1231 spstat->_time_to_do_cleanups = end_time; |
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1232 } |
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1233 |
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1234 void SafepointSynchronize::update_statistics_on_cleanup_end(jlong end_time) { |
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1235 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; |
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1236 |
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1237 // Record how long spent in cleanup tasks. |
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1238 spstat->_time_to_do_cleanups = end_time - spstat->_time_to_do_cleanups; |
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1239 |
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1240 cleanup_end_time = end_time; |
| 0 | 1241 } |
| 1242 | |
| 1243 void SafepointSynchronize::end_statistics(jlong vmop_end_time) { | |
| 1244 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; | |
| 1245 | |
| 1246 // Update the vm operation time. | |
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1247 spstat->_time_to_exec_vmop = vmop_end_time - cleanup_end_time; |
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1248 if (spstat->_time_to_exec_vmop > _max_vmop_time) { |
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1249 _max_vmop_time = spstat->_time_to_exec_vmop; |
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1250 } |
| 0 | 1251 // Only the sync time longer than the specified |
| 1252 // PrintSafepointStatisticsTimeout will be printed out right away. | |
| 1253 // By default, it is -1 meaning all samples will be put into the list. | |
| 1254 if ( PrintSafepointStatisticsTimeout > 0) { | |
| 1255 if (spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) { | |
| 1256 print_statistics(); | |
| 1257 } | |
| 1258 } else { | |
| 1259 // The safepoint statistics will be printed out when the _safepoin_stats | |
| 1260 // array fills up. | |
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1261 if (_cur_stat_index == PrintSafepointStatisticsCount - 1) { |
| 0 | 1262 print_statistics(); |
| 1263 _cur_stat_index = 0; | |
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1264 } else { |
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1265 _cur_stat_index++; |
| 0 | 1266 } |
| 1267 } | |
| 1268 } | |
| 1269 | |
| 1270 void SafepointSynchronize::print_statistics() { | |
| 1271 SafepointStats* sstats = _safepoint_stats; | |
| 1272 | |
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1273 for (int index = 0; index <= _cur_stat_index; index++) { |
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1274 if (index % 30 == 0) { |
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1275 print_header(); |
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1276 } |
| 0 | 1277 sstats = &_safepoint_stats[index]; |
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1278 tty->print("%.3f: ", sstats->_time_stamp); |
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1279 tty->print("%-26s [" |
| 0 | 1280 INT32_FORMAT_W(8)INT32_FORMAT_W(11)INT32_FORMAT_W(15) |
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1281 " ] ", |
| 0 | 1282 sstats->_vmop_type == -1 ? "no vm operation" : |
| 1283 VM_Operation::name(sstats->_vmop_type), | |
| 1284 sstats->_nof_total_threads, | |
| 1285 sstats->_nof_initial_running_threads, | |
| 1286 sstats->_nof_threads_wait_to_block); | |
| 1287 // "/ MICROUNITS " is to convert the unit from nanos to millis. | |
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1288 tty->print(" [" |
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1289 INT64_FORMAT_W(6)INT64_FORMAT_W(6) |
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1290 INT64_FORMAT_W(6)INT64_FORMAT_W(6) |
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1291 INT64_FORMAT_W(6)" ] ", |
| 0 | 1292 sstats->_time_to_spin / MICROUNITS, |
| 1293 sstats->_time_to_wait_to_block / MICROUNITS, | |
| 1294 sstats->_time_to_sync / MICROUNITS, | |
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1295 sstats->_time_to_do_cleanups / MICROUNITS, |
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1296 sstats->_time_to_exec_vmop / MICROUNITS); |
| 0 | 1297 |
| 1298 if (need_to_track_page_armed_status) { | |
| 1299 tty->print(INT32_FORMAT" ", sstats->_page_armed); | |
| 1300 } | |
| 1301 tty->print_cr(INT32_FORMAT" ", sstats->_nof_threads_hit_page_trap); | |
| 1302 } | |
| 1303 } | |
| 1304 | |
| 1305 // This method will be called when VM exits. It will first call | |
| 1306 // print_statistics to print out the rest of the sampling. Then | |
| 1307 // it tries to summarize the sampling. | |
| 1308 void SafepointSynchronize::print_stat_on_exit() { | |
| 1309 if (_safepoint_stats == NULL) return; | |
| 1310 | |
| 1311 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; | |
| 1312 | |
| 1313 // During VM exit, end_statistics may not get called and in that | |
| 1314 // case, if the sync time is less than PrintSafepointStatisticsTimeout, | |
| 1315 // don't print it out. | |
| 1316 // Approximate the vm op time. | |
| 1317 _safepoint_stats[_cur_stat_index]._time_to_exec_vmop = | |
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1318 os::javaTimeNanos() - cleanup_end_time; |
| 0 | 1319 |
| 1320 if ( PrintSafepointStatisticsTimeout < 0 || | |
| 1321 spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) { | |
| 1322 print_statistics(); | |
| 1323 } | |
| 1324 tty->print_cr(""); | |
| 1325 | |
| 1326 // Print out polling page sampling status. | |
| 1327 if (!need_to_track_page_armed_status) { | |
| 1328 if (UseCompilerSafepoints) { | |
| 1329 tty->print_cr("Polling page always armed"); | |
| 1330 } | |
| 1331 } else { | |
| 1332 tty->print_cr("Defer polling page loop count = %d\n", | |
| 1333 DeferPollingPageLoopCount); | |
| 1334 } | |
| 1335 | |
| 1336 for (int index = 0; index < VM_Operation::VMOp_Terminating; index++) { | |
| 1337 if (_safepoint_reasons[index] != 0) { | |
| 1338 tty->print_cr("%-26s"UINT64_FORMAT_W(10), VM_Operation::name(index), | |
| 1339 _safepoint_reasons[index]); | |
| 1340 } | |
| 1341 } | |
| 1342 | |
| 1343 tty->print_cr(UINT64_FORMAT_W(5)" VM operations coalesced during safepoint", | |
| 1344 _coalesced_vmop_count); | |
| 1345 tty->print_cr("Maximum sync time "INT64_FORMAT_W(5)" ms", | |
| 1346 _max_sync_time / MICROUNITS); | |
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1347 tty->print_cr("Maximum vm operation time (except for Exit VM operation) " |
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1348 INT64_FORMAT_W(5)" ms", |
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1349 _max_vmop_time / MICROUNITS); |
| 0 | 1350 } |
| 1351 | |
| 1352 // ------------------------------------------------------------------------------------------------ | |
| 1353 // Non-product code | |
| 1354 | |
| 1355 #ifndef PRODUCT | |
| 1356 | |
| 1357 void SafepointSynchronize::print_state() { | |
| 1358 if (_state == _not_synchronized) { | |
| 1359 tty->print_cr("not synchronized"); | |
| 1360 } else if (_state == _synchronizing || _state == _synchronized) { | |
| 1361 tty->print_cr("State: %s", (_state == _synchronizing) ? "synchronizing" : | |
| 1362 "synchronized"); | |
| 1363 | |
| 1364 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) { | |
| 1365 cur->safepoint_state()->print(); | |
| 1366 } | |
| 1367 } | |
| 1368 } | |
| 1369 | |
| 1370 void SafepointSynchronize::safepoint_msg(const char* format, ...) { | |
| 1371 if (ShowSafepointMsgs) { | |
| 1372 va_list ap; | |
| 1373 va_start(ap, format); | |
| 1374 tty->vprint_cr(format, ap); | |
| 1375 va_end(ap); | |
| 1376 } | |
| 1377 } | |
| 1378 | |
| 1379 #endif // !PRODUCT |