Mercurial > hg > graal-compiler
annotate src/share/vm/runtime/safepoint.cpp @ 3960:f08d439fab8c
7089790: integrate bsd-port changes
Reviewed-by: kvn, twisti, jrose
Contributed-by: Kurt Miller <kurt@intricatesoftware.com>, Greg Lewis <glewis@eyesbeyond.com>, Jung-uk Kim <jkim@freebsd.org>, Christos Zoulas <christos@zoulas.com>, Landon Fuller <landonf@plausible.coop>, The FreeBSD Foundation <board@freebsdfoundation.org>, Michael Franz <mvfranz@gmail.com>, Roger Hoover <rhoover@apple.com>, Alexander Strange <astrange@apple.com>
| author | never |
|---|---|
| date | Sun, 25 Sep 2011 16:03:29 -0700 |
| parents | 2a241e764894 |
| children | 1a2723f7ad8e |
| rev | line source |
|---|---|
| 0 | 1 /* |
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2 * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved. |
| 0 | 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 4 * | |
| 5 * This code is free software; you can redistribute it and/or modify it | |
| 6 * under the terms of the GNU General Public License version 2 only, as | |
| 7 * published by the Free Software Foundation. | |
| 8 * | |
| 9 * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 12 * version 2 for more details (a copy is included in the LICENSE file that | |
| 13 * accompanied this code). | |
| 14 * | |
| 15 * You should have received a copy of the GNU General Public License version | |
| 16 * 2 along with this work; if not, write to the Free Software Foundation, | |
| 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 18 * | |
|
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
| 0 | 22 * |
| 23 */ | |
| 24 | |
| 1972 | 25 #include "precompiled.hpp" |
| 26 #include "classfile/systemDictionary.hpp" | |
| 27 #include "code/codeCache.hpp" | |
| 28 #include "code/icBuffer.hpp" | |
| 29 #include "code/nmethod.hpp" | |
| 30 #include "code/pcDesc.hpp" | |
| 31 #include "code/scopeDesc.hpp" | |
| 32 #include "gc_interface/collectedHeap.hpp" | |
| 33 #include "interpreter/interpreter.hpp" | |
| 34 #include "memory/resourceArea.hpp" | |
| 35 #include "memory/universe.inline.hpp" | |
| 36 #include "oops/oop.inline.hpp" | |
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37 #include "oops/symbol.hpp" |
| 1972 | 38 #include "runtime/compilationPolicy.hpp" |
| 39 #include "runtime/deoptimization.hpp" | |
| 40 #include "runtime/frame.inline.hpp" | |
| 41 #include "runtime/interfaceSupport.hpp" | |
| 42 #include "runtime/mutexLocker.hpp" | |
| 43 #include "runtime/osThread.hpp" | |
| 44 #include "runtime/safepoint.hpp" | |
| 45 #include "runtime/signature.hpp" | |
| 46 #include "runtime/stubCodeGenerator.hpp" | |
| 47 #include "runtime/stubRoutines.hpp" | |
| 48 #include "runtime/sweeper.hpp" | |
| 49 #include "runtime/synchronizer.hpp" | |
| 50 #include "services/runtimeService.hpp" | |
| 51 #include "utilities/events.hpp" | |
| 52 #ifdef TARGET_ARCH_x86 | |
| 53 # include "nativeInst_x86.hpp" | |
| 54 # include "vmreg_x86.inline.hpp" | |
| 55 #endif | |
| 56 #ifdef TARGET_ARCH_sparc | |
| 57 # include "nativeInst_sparc.hpp" | |
| 58 # include "vmreg_sparc.inline.hpp" | |
| 59 #endif | |
| 60 #ifdef TARGET_ARCH_zero | |
| 61 # include "nativeInst_zero.hpp" | |
| 62 # include "vmreg_zero.inline.hpp" | |
| 63 #endif | |
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64 #ifdef TARGET_ARCH_arm |
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65 # include "nativeInst_arm.hpp" |
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66 # include "vmreg_arm.inline.hpp" |
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67 #endif |
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68 #ifdef TARGET_ARCH_ppc |
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69 # include "nativeInst_ppc.hpp" |
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70 # include "vmreg_ppc.inline.hpp" |
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71 #endif |
| 1972 | 72 #ifdef TARGET_OS_FAMILY_linux |
| 73 # include "thread_linux.inline.hpp" | |
| 74 #endif | |
| 75 #ifdef TARGET_OS_FAMILY_solaris | |
| 76 # include "thread_solaris.inline.hpp" | |
| 77 #endif | |
| 78 #ifdef TARGET_OS_FAMILY_windows | |
| 79 # include "thread_windows.inline.hpp" | |
| 80 #endif | |
| 3960 | 81 #ifdef TARGET_OS_FAMILY_bsd |
| 82 # include "thread_bsd.inline.hpp" | |
| 83 #endif | |
| 1972 | 84 #ifndef SERIALGC |
| 85 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp" | |
| 86 #include "gc_implementation/shared/concurrentGCThread.hpp" | |
| 87 #endif | |
| 88 #ifdef COMPILER1 | |
| 89 #include "c1/c1_globals.hpp" | |
| 90 #endif | |
| 0 | 91 |
| 92 // -------------------------------------------------------------------------------------------------- | |
| 93 // Implementation of Safepoint begin/end | |
| 94 | |
| 95 SafepointSynchronize::SynchronizeState volatile SafepointSynchronize::_state = SafepointSynchronize::_not_synchronized; | |
| 96 volatile int SafepointSynchronize::_waiting_to_block = 0; | |
| 97 volatile int SafepointSynchronize::_safepoint_counter = 0; | |
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98 long SafepointSynchronize::_end_of_last_safepoint = 0; |
| 0 | 99 static volatile int PageArmed = 0 ; // safepoint polling page is RO|RW vs PROT_NONE |
| 100 static volatile int TryingToBlock = 0 ; // proximate value -- for advisory use only | |
| 101 static bool timeout_error_printed = false; | |
| 102 | |
| 103 // Roll all threads forward to a safepoint and suspend them all | |
| 104 void SafepointSynchronize::begin() { | |
| 105 | |
| 106 Thread* myThread = Thread::current(); | |
| 107 assert(myThread->is_VM_thread(), "Only VM thread may execute a safepoint"); | |
| 108 | |
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109 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) { |
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110 _safepoint_begin_time = os::javaTimeNanos(); |
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111 _ts_of_current_safepoint = tty->time_stamp().seconds(); |
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112 } |
| 0 | 113 |
| 114 #ifndef SERIALGC | |
| 115 if (UseConcMarkSweepGC) { | |
| 116 // In the future we should investigate whether CMS can use the | |
| 117 // more-general mechanism below. DLD (01/05). | |
| 118 ConcurrentMarkSweepThread::synchronize(false); | |
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119 } else if (UseG1GC) { |
| 0 | 120 ConcurrentGCThread::safepoint_synchronize(); |
| 121 } | |
| 122 #endif // SERIALGC | |
| 123 | |
| 124 // By getting the Threads_lock, we assure that no threads are about to start or | |
| 125 // exit. It is released again in SafepointSynchronize::end(). | |
| 126 Threads_lock->lock(); | |
| 127 | |
| 128 assert( _state == _not_synchronized, "trying to safepoint synchronize with wrong state"); | |
| 129 | |
| 130 int nof_threads = Threads::number_of_threads(); | |
| 131 | |
| 132 if (TraceSafepoint) { | |
| 133 tty->print_cr("Safepoint synchronization initiated. (%d)", nof_threads); | |
| 134 } | |
| 135 | |
| 136 RuntimeService::record_safepoint_begin(); | |
| 137 | |
| 138 { | |
| 139 MutexLocker mu(Safepoint_lock); | |
| 140 | |
| 141 // Set number of threads to wait for, before we initiate the callbacks | |
| 142 _waiting_to_block = nof_threads; | |
| 143 TryingToBlock = 0 ; | |
| 144 int still_running = nof_threads; | |
| 145 | |
| 146 // Save the starting time, so that it can be compared to see if this has taken | |
| 147 // too long to complete. | |
| 148 jlong safepoint_limit_time; | |
| 149 timeout_error_printed = false; | |
| 150 | |
| 1003 | 151 // PrintSafepointStatisticsTimeout can be specified separately. When |
| 152 // specified, PrintSafepointStatistics will be set to true in | |
| 153 // deferred_initialize_stat method. The initialization has to be done | |
| 154 // early enough to avoid any races. See bug 6880029 for details. | |
| 155 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) { | |
| 156 deferred_initialize_stat(); | |
| 157 } | |
| 158 | |
| 0 | 159 // Begin the process of bringing the system to a safepoint. |
| 160 // Java threads can be in several different states and are | |
| 161 // stopped by different mechanisms: | |
| 162 // | |
| 163 // 1. Running interpreted | |
| 164 // The interpeter dispatch table is changed to force it to | |
| 165 // check for a safepoint condition between bytecodes. | |
| 166 // 2. Running in native code | |
| 167 // When returning from the native code, a Java thread must check | |
| 168 // the safepoint _state to see if we must block. If the | |
| 169 // VM thread sees a Java thread in native, it does | |
| 170 // not wait for this thread to block. The order of the memory | |
| 171 // writes and reads of both the safepoint state and the Java | |
| 172 // threads state is critical. In order to guarantee that the | |
| 173 // memory writes are serialized with respect to each other, | |
| 174 // the VM thread issues a memory barrier instruction | |
| 175 // (on MP systems). In order to avoid the overhead of issuing | |
| 176 // a memory barrier for each Java thread making native calls, each Java | |
| 177 // thread performs a write to a single memory page after changing | |
| 178 // the thread state. The VM thread performs a sequence of | |
| 179 // mprotect OS calls which forces all previous writes from all | |
| 180 // Java threads to be serialized. This is done in the | |
| 181 // os::serialize_thread_states() call. This has proven to be | |
| 182 // much more efficient than executing a membar instruction | |
| 183 // on every call to native code. | |
| 184 // 3. Running compiled Code | |
| 185 // Compiled code reads a global (Safepoint Polling) page that | |
| 186 // is set to fault if we are trying to get to a safepoint. | |
| 187 // 4. Blocked | |
| 188 // A thread which is blocked will not be allowed to return from the | |
| 189 // block condition until the safepoint operation is complete. | |
| 190 // 5. In VM or Transitioning between states | |
| 191 // If a Java thread is currently running in the VM or transitioning | |
| 192 // between states, the safepointing code will wait for the thread to | |
| 193 // block itself when it attempts transitions to a new state. | |
| 194 // | |
| 195 _state = _synchronizing; | |
| 196 OrderAccess::fence(); | |
| 197 | |
| 198 // Flush all thread states to memory | |
| 199 if (!UseMembar) { | |
| 200 os::serialize_thread_states(); | |
| 201 } | |
| 202 | |
| 203 // Make interpreter safepoint aware | |
| 204 Interpreter::notice_safepoints(); | |
| 205 | |
| 206 if (UseCompilerSafepoints && DeferPollingPageLoopCount < 0) { | |
| 207 // Make polling safepoint aware | |
| 208 guarantee (PageArmed == 0, "invariant") ; | |
| 209 PageArmed = 1 ; | |
| 210 os::make_polling_page_unreadable(); | |
| 211 } | |
| 212 | |
| 213 // Consider using active_processor_count() ... but that call is expensive. | |
| 214 int ncpus = os::processor_count() ; | |
| 215 | |
| 216 #ifdef ASSERT | |
| 217 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) { | |
| 218 assert(cur->safepoint_state()->is_running(), "Illegal initial state"); | |
| 219 } | |
| 220 #endif // ASSERT | |
| 221 | |
| 222 if (SafepointTimeout) | |
| 223 safepoint_limit_time = os::javaTimeNanos() + (jlong)SafepointTimeoutDelay * MICROUNITS; | |
| 224 | |
| 225 // Iterate through all threads until it have been determined how to stop them all at a safepoint | |
| 226 unsigned int iterations = 0; | |
| 227 int steps = 0 ; | |
| 228 while(still_running > 0) { | |
| 229 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) { | |
| 230 assert(!cur->is_ConcurrentGC_thread(), "A concurrent GC thread is unexpectly being suspended"); | |
| 231 ThreadSafepointState *cur_state = cur->safepoint_state(); | |
| 232 if (cur_state->is_running()) { | |
| 233 cur_state->examine_state_of_thread(); | |
| 234 if (!cur_state->is_running()) { | |
| 235 still_running--; | |
| 236 // consider adjusting steps downward: | |
| 237 // steps = 0 | |
| 238 // steps -= NNN | |
| 239 // steps >>= 1 | |
| 240 // steps = MIN(steps, 2000-100) | |
| 241 // if (iterations != 0) steps -= NNN | |
| 242 } | |
| 243 if (TraceSafepoint && Verbose) cur_state->print(); | |
| 244 } | |
| 245 } | |
| 246 | |
| 1003 | 247 if (PrintSafepointStatistics && iterations == 0) { |
| 0 | 248 begin_statistics(nof_threads, still_running); |
| 249 } | |
| 250 | |
| 251 if (still_running > 0) { | |
| 252 // Check for if it takes to long | |
| 253 if (SafepointTimeout && safepoint_limit_time < os::javaTimeNanos()) { | |
| 254 print_safepoint_timeout(_spinning_timeout); | |
| 255 } | |
| 256 | |
| 257 // Spin to avoid context switching. | |
| 258 // There's a tension between allowing the mutators to run (and rendezvous) | |
| 259 // vs spinning. As the VM thread spins, wasting cycles, it consumes CPU that | |
| 260 // a mutator might otherwise use profitably to reach a safepoint. Excessive | |
| 261 // spinning by the VM thread on a saturated system can increase rendezvous latency. | |
| 262 // Blocking or yielding incur their own penalties in the form of context switching | |
| 263 // and the resultant loss of $ residency. | |
| 264 // | |
| 265 // Further complicating matters is that yield() does not work as naively expected | |
| 266 // on many platforms -- yield() does not guarantee that any other ready threads | |
| 267 // will run. As such we revert yield_all() after some number of iterations. | |
| 268 // Yield_all() is implemented as a short unconditional sleep on some platforms. | |
| 269 // Typical operating systems round a "short" sleep period up to 10 msecs, so sleeping | |
| 270 // can actually increase the time it takes the VM thread to detect that a system-wide | |
| 271 // stop-the-world safepoint has been reached. In a pathological scenario such as that | |
| 272 // described in CR6415670 the VMthread may sleep just before the mutator(s) become safe. | |
| 273 // In that case the mutators will be stalled waiting for the safepoint to complete and the | |
| 274 // the VMthread will be sleeping, waiting for the mutators to rendezvous. The VMthread | |
| 275 // will eventually wake up and detect that all mutators are safe, at which point | |
| 276 // we'll again make progress. | |
| 277 // | |
| 278 // Beware too that that the VMThread typically runs at elevated priority. | |
| 279 // Its default priority is higher than the default mutator priority. | |
| 280 // Obviously, this complicates spinning. | |
| 281 // | |
| 282 // Note too that on Windows XP SwitchThreadTo() has quite different behavior than Sleep(0). | |
| 283 // Sleep(0) will _not yield to lower priority threads, while SwitchThreadTo() will. | |
| 284 // | |
| 285 // See the comments in synchronizer.cpp for additional remarks on spinning. | |
| 286 // | |
| 287 // In the future we might: | |
| 288 // 1. Modify the safepoint scheme to avoid potentally unbounded spinning. | |
| 289 // This is tricky as the path used by a thread exiting the JVM (say on | |
| 290 // on JNI call-out) simply stores into its state field. The burden | |
| 291 // is placed on the VM thread, which must poll (spin). | |
| 292 // 2. Find something useful to do while spinning. If the safepoint is GC-related | |
| 293 // we might aggressively scan the stacks of threads that are already safe. | |
| 294 // 3. Use Solaris schedctl to examine the state of the still-running mutators. | |
| 295 // If all the mutators are ONPROC there's no reason to sleep or yield. | |
| 296 // 4. YieldTo() any still-running mutators that are ready but OFFPROC. | |
| 297 // 5. Check system saturation. If the system is not fully saturated then | |
| 298 // simply spin and avoid sleep/yield. | |
| 299 // 6. As still-running mutators rendezvous they could unpark the sleeping | |
| 300 // VMthread. This works well for still-running mutators that become | |
| 301 // safe. The VMthread must still poll for mutators that call-out. | |
| 302 // 7. Drive the policy on time-since-begin instead of iterations. | |
| 303 // 8. Consider making the spin duration a function of the # of CPUs: | |
| 304 // Spin = (((ncpus-1) * M) + K) + F(still_running) | |
| 305 // Alternately, instead of counting iterations of the outer loop | |
| 306 // we could count the # of threads visited in the inner loop, above. | |
| 307 // 9. On windows consider using the return value from SwitchThreadTo() | |
| 308 // to drive subsequent spin/SwitchThreadTo()/Sleep(N) decisions. | |
| 309 | |
| 310 if (UseCompilerSafepoints && int(iterations) == DeferPollingPageLoopCount) { | |
| 311 guarantee (PageArmed == 0, "invariant") ; | |
| 312 PageArmed = 1 ; | |
| 313 os::make_polling_page_unreadable(); | |
| 314 } | |
| 315 | |
| 316 // Instead of (ncpus > 1) consider either (still_running < (ncpus + EPSILON)) or | |
| 317 // ((still_running + _waiting_to_block - TryingToBlock)) < ncpus) | |
| 318 ++steps ; | |
| 319 if (ncpus > 1 && steps < SafepointSpinBeforeYield) { | |
| 320 SpinPause() ; // MP-Polite spin | |
| 321 } else | |
| 322 if (steps < DeferThrSuspendLoopCount) { | |
| 323 os::NakedYield() ; | |
| 324 } else { | |
| 325 os::yield_all(steps) ; | |
| 326 // Alternately, the VM thread could transiently depress its scheduling priority or | |
| 327 // transiently increase the priority of the tardy mutator(s). | |
| 328 } | |
| 329 | |
| 330 iterations ++ ; | |
| 331 } | |
| 332 assert(iterations < (uint)max_jint, "We have been iterating in the safepoint loop too long"); | |
| 333 } | |
| 334 assert(still_running == 0, "sanity check"); | |
| 335 | |
| 336 if (PrintSafepointStatistics) { | |
| 337 update_statistics_on_spin_end(); | |
| 338 } | |
| 339 | |
| 340 // wait until all threads are stopped | |
| 341 while (_waiting_to_block > 0) { | |
| 342 if (TraceSafepoint) tty->print_cr("Waiting for %d thread(s) to block", _waiting_to_block); | |
| 343 if (!SafepointTimeout || timeout_error_printed) { | |
| 344 Safepoint_lock->wait(true); // true, means with no safepoint checks | |
| 345 } else { | |
| 346 // Compute remaining time | |
| 347 jlong remaining_time = safepoint_limit_time - os::javaTimeNanos(); | |
| 348 | |
| 349 // If there is no remaining time, then there is an error | |
| 350 if (remaining_time < 0 || Safepoint_lock->wait(true, remaining_time / MICROUNITS)) { | |
| 351 print_safepoint_timeout(_blocking_timeout); | |
| 352 } | |
| 353 } | |
| 354 } | |
| 355 assert(_waiting_to_block == 0, "sanity check"); | |
| 356 | |
| 357 #ifndef PRODUCT | |
| 358 if (SafepointTimeout) { | |
| 359 jlong current_time = os::javaTimeNanos(); | |
| 360 if (safepoint_limit_time < current_time) { | |
| 361 tty->print_cr("# SafepointSynchronize: Finished after " | |
| 362 INT64_FORMAT_W(6) " ms", | |
| 363 ((current_time - safepoint_limit_time) / MICROUNITS + | |
| 364 SafepointTimeoutDelay)); | |
| 365 } | |
| 366 } | |
| 367 #endif | |
| 368 | |
| 369 assert((_safepoint_counter & 0x1) == 0, "must be even"); | |
| 370 assert(Threads_lock->owned_by_self(), "must hold Threads_lock"); | |
| 371 _safepoint_counter ++; | |
| 372 | |
| 373 // Record state | |
| 374 _state = _synchronized; | |
| 375 | |
| 376 OrderAccess::fence(); | |
| 377 | |
| 378 if (TraceSafepoint) { | |
| 379 VM_Operation *op = VMThread::vm_operation(); | |
| 380 tty->print_cr("Entering safepoint region: %s", (op != NULL) ? op->name() : "no vm operation"); | |
| 381 } | |
| 382 | |
| 383 RuntimeService::record_safepoint_synchronized(); | |
| 384 if (PrintSafepointStatistics) { | |
| 385 update_statistics_on_sync_end(os::javaTimeNanos()); | |
| 386 } | |
| 387 | |
| 388 // Call stuff that needs to be run when a safepoint is just about to be completed | |
| 389 do_cleanup_tasks(); | |
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390 |
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391 if (PrintSafepointStatistics) { |
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392 // Record how much time spend on the above cleanup tasks |
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393 update_statistics_on_cleanup_end(os::javaTimeNanos()); |
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394 } |
| 0 | 395 } |
| 396 } | |
| 397 | |
| 398 // Wake up all threads, so they are ready to resume execution after the safepoint | |
| 399 // operation has been carried out | |
| 400 void SafepointSynchronize::end() { | |
| 401 | |
| 402 assert(Threads_lock->owned_by_self(), "must hold Threads_lock"); | |
| 403 assert((_safepoint_counter & 0x1) == 1, "must be odd"); | |
| 404 _safepoint_counter ++; | |
| 405 // memory fence isn't required here since an odd _safepoint_counter | |
| 406 // value can do no harm and a fence is issued below anyway. | |
| 407 | |
| 408 DEBUG_ONLY(Thread* myThread = Thread::current();) | |
| 409 assert(myThread->is_VM_thread(), "Only VM thread can execute a safepoint"); | |
| 410 | |
| 411 if (PrintSafepointStatistics) { | |
| 412 end_statistics(os::javaTimeNanos()); | |
| 413 } | |
| 414 | |
| 415 #ifdef ASSERT | |
| 416 // A pending_exception cannot be installed during a safepoint. The threads | |
| 417 // may install an async exception after they come back from a safepoint into | |
| 418 // pending_exception after they unblock. But that should happen later. | |
| 419 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) { | |
| 420 assert (!(cur->has_pending_exception() && | |
| 421 cur->safepoint_state()->is_at_poll_safepoint()), | |
| 422 "safepoint installed a pending exception"); | |
| 423 } | |
| 424 #endif // ASSERT | |
| 425 | |
| 426 if (PageArmed) { | |
| 427 // Make polling safepoint aware | |
| 428 os::make_polling_page_readable(); | |
| 429 PageArmed = 0 ; | |
| 430 } | |
| 431 | |
| 432 // Remove safepoint check from interpreter | |
| 433 Interpreter::ignore_safepoints(); | |
| 434 | |
| 435 { | |
| 436 MutexLocker mu(Safepoint_lock); | |
| 437 | |
| 438 assert(_state == _synchronized, "must be synchronized before ending safepoint synchronization"); | |
| 439 | |
| 440 // Set to not synchronized, so the threads will not go into the signal_thread_blocked method | |
| 441 // when they get restarted. | |
| 442 _state = _not_synchronized; | |
| 443 OrderAccess::fence(); | |
| 444 | |
| 445 if (TraceSafepoint) { | |
| 446 tty->print_cr("Leaving safepoint region"); | |
| 447 } | |
| 448 | |
| 449 // Start suspended threads | |
| 450 for(JavaThread *current = Threads::first(); current; current = current->next()) { | |
| 605 | 451 // A problem occurring on Solaris is when attempting to restart threads |
| 0 | 452 // the first #cpus - 1 go well, but then the VMThread is preempted when we get |
| 453 // to the next one (since it has been running the longest). We then have | |
| 454 // to wait for a cpu to become available before we can continue restarting | |
| 455 // threads. | |
| 456 // FIXME: This causes the performance of the VM to degrade when active and with | |
| 457 // large numbers of threads. Apparently this is due to the synchronous nature | |
| 458 // of suspending threads. | |
| 459 // | |
| 460 // TODO-FIXME: the comments above are vestigial and no longer apply. | |
| 461 // Furthermore, using solaris' schedctl in this particular context confers no benefit | |
| 462 if (VMThreadHintNoPreempt) { | |
| 463 os::hint_no_preempt(); | |
| 464 } | |
| 465 ThreadSafepointState* cur_state = current->safepoint_state(); | |
| 466 assert(cur_state->type() != ThreadSafepointState::_running, "Thread not suspended at safepoint"); | |
| 467 cur_state->restart(); | |
| 468 assert(cur_state->is_running(), "safepoint state has not been reset"); | |
| 469 } | |
| 470 | |
| 471 RuntimeService::record_safepoint_end(); | |
| 472 | |
| 473 // Release threads lock, so threads can be created/destroyed again. It will also starts all threads | |
| 474 // blocked in signal_thread_blocked | |
| 475 Threads_lock->unlock(); | |
| 476 | |
| 477 } | |
| 478 #ifndef SERIALGC | |
| 479 // If there are any concurrent GC threads resume them. | |
| 480 if (UseConcMarkSweepGC) { | |
| 481 ConcurrentMarkSweepThread::desynchronize(false); | |
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482 } else if (UseG1GC) { |
| 0 | 483 ConcurrentGCThread::safepoint_desynchronize(); |
| 484 } | |
| 485 #endif // SERIALGC | |
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486 // record this time so VMThread can keep track how much time has elasped |
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487 // since last safepoint. |
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488 _end_of_last_safepoint = os::javaTimeMillis(); |
| 0 | 489 } |
| 490 | |
| 491 bool SafepointSynchronize::is_cleanup_needed() { | |
| 492 // Need a safepoint if some inline cache buffers is non-empty | |
| 493 if (!InlineCacheBuffer::is_empty()) return true; | |
| 494 return false; | |
| 495 } | |
| 496 | |
| 497 | |
| 498 | |
| 499 // Various cleaning tasks that should be done periodically at safepoints | |
| 500 void SafepointSynchronize::do_cleanup_tasks() { | |
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501 { |
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502 TraceTime t1("deflating idle monitors", TraceSafepointCleanupTime); |
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503 ObjectSynchronizer::deflate_idle_monitors(); |
| 0 | 504 } |
| 505 | |
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506 { |
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507 TraceTime t2("updating inline caches", TraceSafepointCleanupTime); |
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508 InlineCacheBuffer::update_inline_caches(); |
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509 } |
| 1783 | 510 { |
| 511 TraceTime t3("compilation policy safepoint handler", TraceSafepointCleanupTime); | |
| 512 CompilationPolicy::policy()->do_safepoint_work(); | |
| 0 | 513 } |
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514 |
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515 TraceTime t4("sweeping nmethods", TraceSafepointCleanupTime); |
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516 NMethodSweeper::scan_stacks(); |
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517 |
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518 // rotate log files? |
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519 if (UseGCLogFileRotation) { |
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520 gclog_or_tty->rotate_log(); |
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521 } |
| 0 | 522 } |
| 523 | |
| 524 | |
| 525 bool SafepointSynchronize::safepoint_safe(JavaThread *thread, JavaThreadState state) { | |
| 526 switch(state) { | |
| 527 case _thread_in_native: | |
| 528 // native threads are safe if they have no java stack or have walkable stack | |
| 529 return !thread->has_last_Java_frame() || thread->frame_anchor()->walkable(); | |
| 530 | |
| 531 // blocked threads should have already have walkable stack | |
| 532 case _thread_blocked: | |
| 533 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "blocked and not walkable"); | |
| 534 return true; | |
| 535 | |
| 536 default: | |
| 537 return false; | |
| 538 } | |
| 539 } | |
| 540 | |
| 541 | |
| 542 // ------------------------------------------------------------------------------------------------------- | |
| 543 // Implementation of Safepoint callback point | |
| 544 | |
| 545 void SafepointSynchronize::block(JavaThread *thread) { | |
| 546 assert(thread != NULL, "thread must be set"); | |
| 547 assert(thread->is_Java_thread(), "not a Java thread"); | |
| 548 | |
| 549 // Threads shouldn't block if they are in the middle of printing, but... | |
| 550 ttyLocker::break_tty_lock_for_safepoint(os::current_thread_id()); | |
| 551 | |
| 552 // Only bail from the block() call if the thread is gone from the | |
| 553 // thread list; starting to exit should still block. | |
| 554 if (thread->is_terminated()) { | |
| 555 // block current thread if we come here from native code when VM is gone | |
| 556 thread->block_if_vm_exited(); | |
| 557 | |
| 558 // otherwise do nothing | |
| 559 return; | |
| 560 } | |
| 561 | |
| 562 JavaThreadState state = thread->thread_state(); | |
| 563 thread->frame_anchor()->make_walkable(thread); | |
| 564 | |
| 565 // Check that we have a valid thread_state at this point | |
| 566 switch(state) { | |
| 567 case _thread_in_vm_trans: | |
| 568 case _thread_in_Java: // From compiled code | |
| 569 | |
| 570 // We are highly likely to block on the Safepoint_lock. In order to avoid blocking in this case, | |
| 571 // we pretend we are still in the VM. | |
| 572 thread->set_thread_state(_thread_in_vm); | |
| 573 | |
| 574 if (is_synchronizing()) { | |
| 575 Atomic::inc (&TryingToBlock) ; | |
| 576 } | |
| 577 | |
| 578 // We will always be holding the Safepoint_lock when we are examine the state | |
| 579 // of a thread. Hence, the instructions between the Safepoint_lock->lock() and | |
| 580 // Safepoint_lock->unlock() are happening atomic with regards to the safepoint code | |
| 581 Safepoint_lock->lock_without_safepoint_check(); | |
| 582 if (is_synchronizing()) { | |
| 583 // Decrement the number of threads to wait for and signal vm thread | |
| 584 assert(_waiting_to_block > 0, "sanity check"); | |
| 585 _waiting_to_block--; | |
| 586 thread->safepoint_state()->set_has_called_back(true); | |
| 587 | |
| 588 // Consider (_waiting_to_block < 2) to pipeline the wakeup of the VM thread | |
| 589 if (_waiting_to_block == 0) { | |
| 590 Safepoint_lock->notify_all(); | |
| 591 } | |
| 592 } | |
| 593 | |
| 594 // We transition the thread to state _thread_blocked here, but | |
| 595 // we can't do our usual check for external suspension and then | |
| 596 // self-suspend after the lock_without_safepoint_check() call | |
| 597 // below because we are often called during transitions while | |
| 598 // we hold different locks. That would leave us suspended while | |
| 599 // holding a resource which results in deadlocks. | |
| 600 thread->set_thread_state(_thread_blocked); | |
| 601 Safepoint_lock->unlock(); | |
| 602 | |
| 603 // We now try to acquire the threads lock. Since this lock is hold by the VM thread during | |
| 604 // the entire safepoint, the threads will all line up here during the safepoint. | |
| 605 Threads_lock->lock_without_safepoint_check(); | |
| 606 // restore original state. This is important if the thread comes from compiled code, so it | |
| 607 // will continue to execute with the _thread_in_Java state. | |
| 608 thread->set_thread_state(state); | |
| 609 Threads_lock->unlock(); | |
| 610 break; | |
| 611 | |
| 612 case _thread_in_native_trans: | |
| 613 case _thread_blocked_trans: | |
| 614 case _thread_new_trans: | |
| 615 if (thread->safepoint_state()->type() == ThreadSafepointState::_call_back) { | |
| 616 thread->print_thread_state(); | |
| 617 fatal("Deadlock in safepoint code. " | |
| 618 "Should have called back to the VM before blocking."); | |
| 619 } | |
| 620 | |
| 621 // We transition the thread to state _thread_blocked here, but | |
| 622 // we can't do our usual check for external suspension and then | |
| 623 // self-suspend after the lock_without_safepoint_check() call | |
| 624 // below because we are often called during transitions while | |
| 625 // we hold different locks. That would leave us suspended while | |
| 626 // holding a resource which results in deadlocks. | |
| 627 thread->set_thread_state(_thread_blocked); | |
| 628 | |
| 629 // It is not safe to suspend a thread if we discover it is in _thread_in_native_trans. Hence, | |
| 630 // the safepoint code might still be waiting for it to block. We need to change the state here, | |
| 631 // so it can see that it is at a safepoint. | |
| 632 | |
| 633 // Block until the safepoint operation is completed. | |
| 634 Threads_lock->lock_without_safepoint_check(); | |
| 635 | |
| 636 // Restore state | |
| 637 thread->set_thread_state(state); | |
| 638 | |
| 639 Threads_lock->unlock(); | |
| 640 break; | |
| 641 | |
| 642 default: | |
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643 fatal(err_msg("Illegal threadstate encountered: %d", state)); |
| 0 | 644 } |
| 645 | |
| 646 // Check for pending. async. exceptions or suspends - except if the | |
| 647 // thread was blocked inside the VM. has_special_runtime_exit_condition() | |
| 648 // is called last since it grabs a lock and we only want to do that when | |
| 649 // we must. | |
| 650 // | |
| 651 // Note: we never deliver an async exception at a polling point as the | |
| 652 // compiler may not have an exception handler for it. The polling | |
| 653 // code will notice the async and deoptimize and the exception will | |
| 654 // be delivered. (Polling at a return point is ok though). Sure is | |
| 655 // a lot of bother for a deprecated feature... | |
| 656 // | |
| 657 // We don't deliver an async exception if the thread state is | |
| 658 // _thread_in_native_trans so JNI functions won't be called with | |
| 659 // a surprising pending exception. If the thread state is going back to java, | |
| 660 // async exception is checked in check_special_condition_for_native_trans(). | |
| 661 | |
| 662 if (state != _thread_blocked_trans && | |
| 663 state != _thread_in_vm_trans && | |
| 664 thread->has_special_runtime_exit_condition()) { | |
| 665 thread->handle_special_runtime_exit_condition( | |
| 666 !thread->is_at_poll_safepoint() && (state != _thread_in_native_trans)); | |
| 667 } | |
| 668 } | |
| 669 | |
| 670 // ------------------------------------------------------------------------------------------------------ | |
| 671 // Exception handlers | |
| 672 | |
| 673 #ifndef PRODUCT | |
| 674 #ifdef _LP64 | |
| 675 #define PTR_PAD "" | |
| 676 #else | |
| 677 #define PTR_PAD " " | |
| 678 #endif | |
| 679 | |
| 680 static void print_ptrs(intptr_t oldptr, intptr_t newptr, bool wasoop) { | |
| 681 bool is_oop = newptr ? ((oop)newptr)->is_oop() : false; | |
| 682 tty->print_cr(PTR_FORMAT PTR_PAD " %s %c " PTR_FORMAT PTR_PAD " %s %s", | |
| 683 oldptr, wasoop?"oop":" ", oldptr == newptr ? ' ' : '!', | |
| 684 newptr, is_oop?"oop":" ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":" ")); | |
| 685 } | |
| 686 | |
| 687 static void print_longs(jlong oldptr, jlong newptr, bool wasoop) { | |
| 688 bool is_oop = newptr ? ((oop)(intptr_t)newptr)->is_oop() : false; | |
| 689 tty->print_cr(PTR64_FORMAT " %s %c " PTR64_FORMAT " %s %s", | |
| 690 oldptr, wasoop?"oop":" ", oldptr == newptr ? ' ' : '!', | |
| 691 newptr, is_oop?"oop":" ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":" ")); | |
| 692 } | |
| 693 | |
| 694 #ifdef SPARC | |
| 695 static void print_me(intptr_t *new_sp, intptr_t *old_sp, bool *was_oops) { | |
| 696 #ifdef _LP64 | |
| 697 tty->print_cr("--------+------address-----+------before-----------+-------after----------+"); | |
| 698 const int incr = 1; // Increment to skip a long, in units of intptr_t | |
| 699 #else | |
| 700 tty->print_cr("--------+--address-+------before-----------+-------after----------+"); | |
| 701 const int incr = 2; // Increment to skip a long, in units of intptr_t | |
| 702 #endif | |
| 703 tty->print_cr("---SP---|"); | |
| 704 for( int i=0; i<16; i++ ) { | |
| 705 tty->print("blob %c%d |"PTR_FORMAT" ","LO"[i>>3],i&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); } | |
| 706 tty->print_cr("--------|"); | |
| 707 for( int i1=0; i1<frame::memory_parameter_word_sp_offset-16; i1++ ) { | |
| 708 tty->print("argv pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); } | |
| 709 tty->print(" pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); | |
| 710 tty->print_cr("--------|"); | |
| 711 tty->print(" G1 |"PTR_FORMAT" ",new_sp); print_longs(*(jlong*)old_sp,*(jlong*)new_sp,was_oops[incr-1]); old_sp += incr; new_sp += incr; was_oops += incr; | |
| 712 tty->print(" G3 |"PTR_FORMAT" ",new_sp); print_longs(*(jlong*)old_sp,*(jlong*)new_sp,was_oops[incr-1]); old_sp += incr; new_sp += incr; was_oops += incr; | |
| 713 tty->print(" G4 |"PTR_FORMAT" ",new_sp); print_longs(*(jlong*)old_sp,*(jlong*)new_sp,was_oops[incr-1]); old_sp += incr; new_sp += incr; was_oops += incr; | |
| 714 tty->print(" G5 |"PTR_FORMAT" ",new_sp); print_longs(*(jlong*)old_sp,*(jlong*)new_sp,was_oops[incr-1]); old_sp += incr; new_sp += incr; was_oops += incr; | |
| 715 tty->print_cr(" FSR |"PTR_FORMAT" "PTR64_FORMAT" "PTR64_FORMAT,new_sp,*(jlong*)old_sp,*(jlong*)new_sp); | |
| 716 old_sp += incr; new_sp += incr; was_oops += incr; | |
| 717 // Skip the floats | |
| 718 tty->print_cr("--Float-|"PTR_FORMAT,new_sp); | |
| 719 tty->print_cr("---FP---|"); | |
| 720 old_sp += incr*32; new_sp += incr*32; was_oops += incr*32; | |
| 721 for( int i2=0; i2<16; i2++ ) { | |
| 722 tty->print("call %c%d |"PTR_FORMAT" ","LI"[i2>>3],i2&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); } | |
| 723 tty->print_cr(""); | |
| 724 } | |
| 725 #endif // SPARC | |
| 726 #endif // PRODUCT | |
| 727 | |
| 728 | |
| 729 void SafepointSynchronize::handle_polling_page_exception(JavaThread *thread) { | |
| 730 assert(thread->is_Java_thread(), "polling reference encountered by VM thread"); | |
| 731 assert(thread->thread_state() == _thread_in_Java, "should come from Java code"); | |
| 732 assert(SafepointSynchronize::is_synchronizing(), "polling encountered outside safepoint synchronization"); | |
| 733 | |
| 734 // Uncomment this to get some serious before/after printing of the | |
| 735 // Sparc safepoint-blob frame structure. | |
| 736 /* | |
| 737 intptr_t* sp = thread->last_Java_sp(); | |
| 738 intptr_t stack_copy[150]; | |
| 739 for( int i=0; i<150; i++ ) stack_copy[i] = sp[i]; | |
| 740 bool was_oops[150]; | |
| 741 for( int i=0; i<150; i++ ) | |
| 742 was_oops[i] = stack_copy[i] ? ((oop)stack_copy[i])->is_oop() : false; | |
| 743 */ | |
| 744 | |
| 745 if (ShowSafepointMsgs) { | |
| 746 tty->print("handle_polling_page_exception: "); | |
| 747 } | |
| 748 | |
| 749 if (PrintSafepointStatistics) { | |
| 750 inc_page_trap_count(); | |
| 751 } | |
| 752 | |
| 753 ThreadSafepointState* state = thread->safepoint_state(); | |
| 754 | |
| 755 state->handle_polling_page_exception(); | |
| 756 // print_me(sp,stack_copy,was_oops); | |
| 757 } | |
| 758 | |
| 759 | |
| 760 void SafepointSynchronize::print_safepoint_timeout(SafepointTimeoutReason reason) { | |
| 761 if (!timeout_error_printed) { | |
| 762 timeout_error_printed = true; | |
| 763 // Print out the thread infor which didn't reach the safepoint for debugging | |
| 764 // purposes (useful when there are lots of threads in the debugger). | |
| 765 tty->print_cr(""); | |
| 766 tty->print_cr("# SafepointSynchronize::begin: Timeout detected:"); | |
| 767 if (reason == _spinning_timeout) { | |
| 768 tty->print_cr("# SafepointSynchronize::begin: Timed out while spinning to reach a safepoint."); | |
| 769 } else if (reason == _blocking_timeout) { | |
| 770 tty->print_cr("# SafepointSynchronize::begin: Timed out while waiting for threads to stop."); | |
| 771 } | |
| 772 | |
| 773 tty->print_cr("# SafepointSynchronize::begin: Threads which did not reach the safepoint:"); | |
| 774 ThreadSafepointState *cur_state; | |
| 775 ResourceMark rm; | |
| 776 for(JavaThread *cur_thread = Threads::first(); cur_thread; | |
| 777 cur_thread = cur_thread->next()) { | |
| 778 cur_state = cur_thread->safepoint_state(); | |
| 779 | |
| 780 if (cur_thread->thread_state() != _thread_blocked && | |
| 781 ((reason == _spinning_timeout && cur_state->is_running()) || | |
| 782 (reason == _blocking_timeout && !cur_state->has_called_back()))) { | |
| 783 tty->print("# "); | |
| 784 cur_thread->print(); | |
| 785 tty->print_cr(""); | |
| 786 } | |
| 787 } | |
| 788 tty->print_cr("# SafepointSynchronize::begin: (End of list)"); | |
| 789 } | |
| 790 | |
| 791 // To debug the long safepoint, specify both DieOnSafepointTimeout & | |
| 792 // ShowMessageBoxOnError. | |
| 793 if (DieOnSafepointTimeout) { | |
| 794 char msg[1024]; | |
| 795 VM_Operation *op = VMThread::vm_operation(); | |
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796 sprintf(msg, "Safepoint sync time longer than " INTX_FORMAT "ms detected when executing %s.", |
| 0 | 797 SafepointTimeoutDelay, |
| 798 op != NULL ? op->name() : "no vm operation"); | |
| 799 fatal(msg); | |
| 800 } | |
| 801 } | |
| 802 | |
| 803 | |
| 804 // ------------------------------------------------------------------------------------------------------- | |
| 805 // Implementation of ThreadSafepointState | |
| 806 | |
| 807 ThreadSafepointState::ThreadSafepointState(JavaThread *thread) { | |
| 808 _thread = thread; | |
| 809 _type = _running; | |
| 810 _has_called_back = false; | |
| 811 _at_poll_safepoint = false; | |
| 812 } | |
| 813 | |
| 814 void ThreadSafepointState::create(JavaThread *thread) { | |
| 815 ThreadSafepointState *state = new ThreadSafepointState(thread); | |
| 816 thread->set_safepoint_state(state); | |
| 817 } | |
| 818 | |
| 819 void ThreadSafepointState::destroy(JavaThread *thread) { | |
| 820 if (thread->safepoint_state()) { | |
| 821 delete(thread->safepoint_state()); | |
| 822 thread->set_safepoint_state(NULL); | |
| 823 } | |
| 824 } | |
| 825 | |
| 826 void ThreadSafepointState::examine_state_of_thread() { | |
| 827 assert(is_running(), "better be running or just have hit safepoint poll"); | |
| 828 | |
| 829 JavaThreadState state = _thread->thread_state(); | |
| 830 | |
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831 // Save the state at the start of safepoint processing. |
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832 _orig_thread_state = state; |
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833 |
| 0 | 834 // Check for a thread that is suspended. Note that thread resume tries |
| 835 // to grab the Threads_lock which we own here, so a thread cannot be | |
| 836 // resumed during safepoint synchronization. | |
| 837 | |
| 979 | 838 // We check to see if this thread is suspended without locking to |
| 839 // avoid deadlocking with a third thread that is waiting for this | |
| 840 // thread to be suspended. The third thread can notice the safepoint | |
| 841 // that we're trying to start at the beginning of its SR_lock->wait() | |
| 842 // call. If that happens, then the third thread will block on the | |
| 843 // safepoint while still holding the underlying SR_lock. We won't be | |
| 844 // able to get the SR_lock and we'll deadlock. | |
| 845 // | |
| 846 // We don't need to grab the SR_lock here for two reasons: | |
| 847 // 1) The suspend flags are both volatile and are set with an | |
| 848 // Atomic::cmpxchg() call so we should see the suspended | |
| 849 // state right away. | |
| 850 // 2) We're being called from the safepoint polling loop; if | |
| 851 // we don't see the suspended state on this iteration, then | |
| 852 // we'll come around again. | |
| 853 // | |
| 854 bool is_suspended = _thread->is_ext_suspended(); | |
| 0 | 855 if (is_suspended) { |
| 856 roll_forward(_at_safepoint); | |
| 857 return; | |
| 858 } | |
| 859 | |
| 860 // Some JavaThread states have an initial safepoint state of | |
| 861 // running, but are actually at a safepoint. We will happily | |
| 862 // agree and update the safepoint state here. | |
| 863 if (SafepointSynchronize::safepoint_safe(_thread, state)) { | |
| 864 roll_forward(_at_safepoint); | |
| 865 return; | |
| 866 } | |
| 867 | |
| 868 if (state == _thread_in_vm) { | |
| 869 roll_forward(_call_back); | |
| 870 return; | |
| 871 } | |
| 872 | |
| 873 // All other thread states will continue to run until they | |
| 874 // transition and self-block in state _blocked | |
| 875 // Safepoint polling in compiled code causes the Java threads to do the same. | |
| 876 // Note: new threads may require a malloc so they must be allowed to finish | |
| 877 | |
| 878 assert(is_running(), "examine_state_of_thread on non-running thread"); | |
| 879 return; | |
| 880 } | |
| 881 | |
| 882 // Returns true is thread could not be rolled forward at present position. | |
| 883 void ThreadSafepointState::roll_forward(suspend_type type) { | |
| 884 _type = type; | |
| 885 | |
| 886 switch(_type) { | |
| 887 case _at_safepoint: | |
| 888 SafepointSynchronize::signal_thread_at_safepoint(); | |
| 889 break; | |
| 890 | |
| 891 case _call_back: | |
| 892 set_has_called_back(false); | |
| 893 break; | |
| 894 | |
| 895 case _running: | |
| 896 default: | |
| 897 ShouldNotReachHere(); | |
| 898 } | |
| 899 } | |
| 900 | |
| 901 void ThreadSafepointState::restart() { | |
| 902 switch(type()) { | |
| 903 case _at_safepoint: | |
| 904 case _call_back: | |
| 905 break; | |
| 906 | |
| 907 case _running: | |
| 908 default: | |
| 909 tty->print_cr("restart thread "INTPTR_FORMAT" with state %d", | |
| 910 _thread, _type); | |
| 911 _thread->print(); | |
| 912 ShouldNotReachHere(); | |
| 913 } | |
| 914 _type = _running; | |
| 915 set_has_called_back(false); | |
| 916 } | |
| 917 | |
| 918 | |
| 919 void ThreadSafepointState::print_on(outputStream *st) const { | |
| 920 const char *s; | |
| 921 | |
| 922 switch(_type) { | |
| 923 case _running : s = "_running"; break; | |
| 924 case _at_safepoint : s = "_at_safepoint"; break; | |
| 925 case _call_back : s = "_call_back"; break; | |
| 926 default: | |
| 927 ShouldNotReachHere(); | |
| 928 } | |
| 929 | |
| 930 st->print_cr("Thread: " INTPTR_FORMAT | |
| 931 " [0x%2x] State: %s _has_called_back %d _at_poll_safepoint %d", | |
| 932 _thread, _thread->osthread()->thread_id(), s, _has_called_back, | |
| 933 _at_poll_safepoint); | |
| 934 | |
| 935 _thread->print_thread_state_on(st); | |
| 936 } | |
| 937 | |
| 938 | |
| 939 // --------------------------------------------------------------------------------------------------------------------- | |
| 940 | |
| 941 // Block the thread at the safepoint poll or poll return. | |
| 942 void ThreadSafepointState::handle_polling_page_exception() { | |
| 943 | |
| 944 // Check state. block() will set thread state to thread_in_vm which will | |
| 945 // cause the safepoint state _type to become _call_back. | |
| 946 assert(type() == ThreadSafepointState::_running, | |
| 947 "polling page exception on thread not running state"); | |
| 948 | |
| 949 // Step 1: Find the nmethod from the return address | |
| 950 if (ShowSafepointMsgs && Verbose) { | |
| 951 tty->print_cr("Polling page exception at " INTPTR_FORMAT, thread()->saved_exception_pc()); | |
| 952 } | |
| 953 address real_return_addr = thread()->saved_exception_pc(); | |
| 954 | |
| 955 CodeBlob *cb = CodeCache::find_blob(real_return_addr); | |
| 956 assert(cb != NULL && cb->is_nmethod(), "return address should be in nmethod"); | |
| 957 nmethod* nm = (nmethod*)cb; | |
| 958 | |
| 959 // Find frame of caller | |
| 960 frame stub_fr = thread()->last_frame(); | |
| 961 CodeBlob* stub_cb = stub_fr.cb(); | |
| 962 assert(stub_cb->is_safepoint_stub(), "must be a safepoint stub"); | |
| 963 RegisterMap map(thread(), true); | |
| 964 frame caller_fr = stub_fr.sender(&map); | |
| 965 | |
| 966 // Should only be poll_return or poll | |
| 967 assert( nm->is_at_poll_or_poll_return(real_return_addr), "should not be at call" ); | |
| 968 | |
| 969 // This is a poll immediately before a return. The exception handling code | |
| 970 // has already had the effect of causing the return to occur, so the execution | |
| 971 // will continue immediately after the call. In addition, the oopmap at the | |
| 972 // return point does not mark the return value as an oop (if it is), so | |
| 973 // it needs a handle here to be updated. | |
| 974 if( nm->is_at_poll_return(real_return_addr) ) { | |
| 975 // See if return type is an oop. | |
| 976 bool return_oop = nm->method()->is_returning_oop(); | |
| 977 Handle return_value; | |
| 978 if (return_oop) { | |
| 979 // The oop result has been saved on the stack together with all | |
| 980 // the other registers. In order to preserve it over GCs we need | |
| 981 // to keep it in a handle. | |
| 982 oop result = caller_fr.saved_oop_result(&map); | |
| 983 assert(result == NULL || result->is_oop(), "must be oop"); | |
| 984 return_value = Handle(thread(), result); | |
| 985 assert(Universe::heap()->is_in_or_null(result), "must be heap pointer"); | |
| 986 } | |
| 987 | |
| 988 // Block the thread | |
| 989 SafepointSynchronize::block(thread()); | |
| 990 | |
| 991 // restore oop result, if any | |
| 992 if (return_oop) { | |
| 993 caller_fr.set_saved_oop_result(&map, return_value()); | |
| 994 } | |
| 995 } | |
| 996 | |
| 997 // This is a safepoint poll. Verify the return address and block. | |
| 998 else { | |
| 999 set_at_poll_safepoint(true); | |
| 1000 | |
| 1001 // verify the blob built the "return address" correctly | |
| 1002 assert(real_return_addr == caller_fr.pc(), "must match"); | |
| 1003 | |
| 1004 // Block the thread | |
| 1005 SafepointSynchronize::block(thread()); | |
| 1006 set_at_poll_safepoint(false); | |
| 1007 | |
| 1008 // If we have a pending async exception deoptimize the frame | |
| 1009 // as otherwise we may never deliver it. | |
| 1010 if (thread()->has_async_condition()) { | |
| 1011 ThreadInVMfromJavaNoAsyncException __tiv(thread()); | |
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1012 Deoptimization::deoptimize_frame(thread(), caller_fr.id()); |
| 0 | 1013 } |
| 1014 | |
| 1015 // If an exception has been installed we must check for a pending deoptimization | |
| 1016 // Deoptimize frame if exception has been thrown. | |
| 1017 | |
| 1018 if (thread()->has_pending_exception() ) { | |
| 1019 RegisterMap map(thread(), true); | |
| 1020 frame caller_fr = stub_fr.sender(&map); | |
| 1021 if (caller_fr.is_deoptimized_frame()) { | |
| 1022 // The exception patch will destroy registers that are still | |
| 1023 // live and will be needed during deoptimization. Defer the | |
| 1024 // Async exception should have defered the exception until the | |
| 1025 // next safepoint which will be detected when we get into | |
| 1026 // the interpreter so if we have an exception now things | |
| 1027 // are messed up. | |
| 1028 | |
| 1029 fatal("Exception installed and deoptimization is pending"); | |
| 1030 } | |
| 1031 } | |
| 1032 } | |
| 1033 } | |
| 1034 | |
| 1035 | |
| 1036 // | |
| 1037 // Statistics & Instrumentations | |
| 1038 // | |
| 1039 SafepointSynchronize::SafepointStats* SafepointSynchronize::_safepoint_stats = NULL; | |
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1040 jlong SafepointSynchronize::_safepoint_begin_time = 0; |
| 0 | 1041 int SafepointSynchronize::_cur_stat_index = 0; |
| 1042 julong SafepointSynchronize::_safepoint_reasons[VM_Operation::VMOp_Terminating]; | |
| 1043 julong SafepointSynchronize::_coalesced_vmop_count = 0; | |
| 1044 jlong SafepointSynchronize::_max_sync_time = 0; | |
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1045 jlong SafepointSynchronize::_max_vmop_time = 0; |
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1046 float SafepointSynchronize::_ts_of_current_safepoint = 0.0f; |
| 0 | 1047 |
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1048 static jlong cleanup_end_time = 0; |
| 0 | 1049 static bool need_to_track_page_armed_status = false; |
| 1050 static bool init_done = false; | |
| 1051 | |
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1052 // Helper method to print the header. |
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1053 static void print_header() { |
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1054 tty->print(" vmop " |
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1055 "[threads: total initially_running wait_to_block] "); |
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1056 tty->print("[time: spin block sync cleanup vmop] "); |
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1057 |
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1058 // no page armed status printed out if it is always armed. |
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1059 if (need_to_track_page_armed_status) { |
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1060 tty->print("page_armed "); |
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1061 } |
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1062 |
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1063 tty->print_cr("page_trap_count"); |
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1064 } |
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1065 |
| 0 | 1066 void SafepointSynchronize::deferred_initialize_stat() { |
| 1067 if (init_done) return; | |
| 1068 | |
| 1069 if (PrintSafepointStatisticsCount <= 0) { | |
| 1070 fatal("Wrong PrintSafepointStatisticsCount"); | |
| 1071 } | |
| 1072 | |
| 1073 // If PrintSafepointStatisticsTimeout is specified, the statistics data will | |
| 1074 // be printed right away, in which case, _safepoint_stats will regress to | |
| 1075 // a single element array. Otherwise, it is a circular ring buffer with default | |
| 1076 // size of PrintSafepointStatisticsCount. | |
| 1077 int stats_array_size; | |
| 1078 if (PrintSafepointStatisticsTimeout > 0) { | |
| 1079 stats_array_size = 1; | |
| 1080 PrintSafepointStatistics = true; | |
| 1081 } else { | |
| 1082 stats_array_size = PrintSafepointStatisticsCount; | |
| 1083 } | |
| 1084 _safepoint_stats = (SafepointStats*)os::malloc(stats_array_size | |
| 1085 * sizeof(SafepointStats)); | |
| 1086 guarantee(_safepoint_stats != NULL, | |
| 1087 "not enough memory for safepoint instrumentation data"); | |
| 1088 | |
| 1089 if (UseCompilerSafepoints && DeferPollingPageLoopCount >= 0) { | |
| 1090 need_to_track_page_armed_status = true; | |
| 1091 } | |
| 1092 init_done = true; | |
| 1093 } | |
| 1094 | |
| 1095 void SafepointSynchronize::begin_statistics(int nof_threads, int nof_running) { | |
| 1003 | 1096 assert(init_done, "safepoint statistics array hasn't been initialized"); |
| 0 | 1097 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; |
| 1098 | |
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1099 spstat->_time_stamp = _ts_of_current_safepoint; |
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1100 |
| 0 | 1101 VM_Operation *op = VMThread::vm_operation(); |
| 1102 spstat->_vmop_type = (op != NULL ? op->type() : -1); | |
| 1103 if (op != NULL) { | |
| 1104 _safepoint_reasons[spstat->_vmop_type]++; | |
| 1105 } | |
| 1106 | |
| 1107 spstat->_nof_total_threads = nof_threads; | |
| 1108 spstat->_nof_initial_running_threads = nof_running; | |
| 1109 spstat->_nof_threads_hit_page_trap = 0; | |
| 1110 | |
| 1111 // Records the start time of spinning. The real time spent on spinning | |
| 1112 // will be adjusted when spin is done. Same trick is applied for time | |
| 1113 // spent on waiting for threads to block. | |
| 1114 if (nof_running != 0) { | |
| 1115 spstat->_time_to_spin = os::javaTimeNanos(); | |
| 1116 } else { | |
| 1117 spstat->_time_to_spin = 0; | |
| 1118 } | |
| 1119 } | |
| 1120 | |
| 1121 void SafepointSynchronize::update_statistics_on_spin_end() { | |
| 1122 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; | |
| 1123 | |
| 1124 jlong cur_time = os::javaTimeNanos(); | |
| 1125 | |
| 1126 spstat->_nof_threads_wait_to_block = _waiting_to_block; | |
| 1127 if (spstat->_nof_initial_running_threads != 0) { | |
| 1128 spstat->_time_to_spin = cur_time - spstat->_time_to_spin; | |
| 1129 } | |
| 1130 | |
| 1131 if (need_to_track_page_armed_status) { | |
| 1132 spstat->_page_armed = (PageArmed == 1); | |
| 1133 } | |
| 1134 | |
| 1135 // Records the start time of waiting for to block. Updated when block is done. | |
| 1136 if (_waiting_to_block != 0) { | |
| 1137 spstat->_time_to_wait_to_block = cur_time; | |
| 1138 } else { | |
| 1139 spstat->_time_to_wait_to_block = 0; | |
| 1140 } | |
| 1141 } | |
| 1142 | |
| 1143 void SafepointSynchronize::update_statistics_on_sync_end(jlong end_time) { | |
| 1144 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; | |
| 1145 | |
| 1146 if (spstat->_nof_threads_wait_to_block != 0) { | |
| 1147 spstat->_time_to_wait_to_block = end_time - | |
| 1148 spstat->_time_to_wait_to_block; | |
| 1149 } | |
| 1150 | |
| 1151 // Records the end time of sync which will be used to calculate the total | |
| 1152 // vm operation time. Again, the real time spending in syncing will be deducted | |
| 1153 // from the start of the sync time later when end_statistics is called. | |
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1154 spstat->_time_to_sync = end_time - _safepoint_begin_time; |
| 0 | 1155 if (spstat->_time_to_sync > _max_sync_time) { |
| 1156 _max_sync_time = spstat->_time_to_sync; | |
| 1157 } | |
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1158 |
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1159 spstat->_time_to_do_cleanups = end_time; |
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1160 } |
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1161 |
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1162 void SafepointSynchronize::update_statistics_on_cleanup_end(jlong end_time) { |
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1163 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; |
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1164 |
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1165 // Record how long spent in cleanup tasks. |
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1166 spstat->_time_to_do_cleanups = end_time - spstat->_time_to_do_cleanups; |
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1167 |
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1168 cleanup_end_time = end_time; |
| 0 | 1169 } |
| 1170 | |
| 1171 void SafepointSynchronize::end_statistics(jlong vmop_end_time) { | |
| 1172 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; | |
| 1173 | |
| 1174 // Update the vm operation time. | |
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1175 spstat->_time_to_exec_vmop = vmop_end_time - cleanup_end_time; |
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1176 if (spstat->_time_to_exec_vmop > _max_vmop_time) { |
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1177 _max_vmop_time = spstat->_time_to_exec_vmop; |
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1178 } |
| 0 | 1179 // Only the sync time longer than the specified |
| 1180 // PrintSafepointStatisticsTimeout will be printed out right away. | |
| 1181 // By default, it is -1 meaning all samples will be put into the list. | |
| 1182 if ( PrintSafepointStatisticsTimeout > 0) { | |
| 1183 if (spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) { | |
| 1184 print_statistics(); | |
| 1185 } | |
| 1186 } else { | |
| 1187 // The safepoint statistics will be printed out when the _safepoin_stats | |
| 1188 // array fills up. | |
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1189 if (_cur_stat_index == PrintSafepointStatisticsCount - 1) { |
| 0 | 1190 print_statistics(); |
| 1191 _cur_stat_index = 0; | |
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1192 } else { |
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1193 _cur_stat_index++; |
| 0 | 1194 } |
| 1195 } | |
| 1196 } | |
| 1197 | |
| 1198 void SafepointSynchronize::print_statistics() { | |
| 1199 SafepointStats* sstats = _safepoint_stats; | |
| 1200 | |
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1201 for (int index = 0; index <= _cur_stat_index; index++) { |
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1202 if (index % 30 == 0) { |
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1203 print_header(); |
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1204 } |
| 0 | 1205 sstats = &_safepoint_stats[index]; |
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1206 tty->print("%.3f: ", sstats->_time_stamp); |
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1207 tty->print("%-26s [" |
| 0 | 1208 INT32_FORMAT_W(8)INT32_FORMAT_W(11)INT32_FORMAT_W(15) |
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1209 " ] ", |
| 0 | 1210 sstats->_vmop_type == -1 ? "no vm operation" : |
| 1211 VM_Operation::name(sstats->_vmop_type), | |
| 1212 sstats->_nof_total_threads, | |
| 1213 sstats->_nof_initial_running_threads, | |
| 1214 sstats->_nof_threads_wait_to_block); | |
| 1215 // "/ MICROUNITS " is to convert the unit from nanos to millis. | |
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1216 tty->print(" [" |
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1217 INT64_FORMAT_W(6)INT64_FORMAT_W(6) |
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1218 INT64_FORMAT_W(6)INT64_FORMAT_W(6) |
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1219 INT64_FORMAT_W(6)" ] ", |
| 0 | 1220 sstats->_time_to_spin / MICROUNITS, |
| 1221 sstats->_time_to_wait_to_block / MICROUNITS, | |
| 1222 sstats->_time_to_sync / MICROUNITS, | |
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1223 sstats->_time_to_do_cleanups / MICROUNITS, |
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1224 sstats->_time_to_exec_vmop / MICROUNITS); |
| 0 | 1225 |
| 1226 if (need_to_track_page_armed_status) { | |
| 1227 tty->print(INT32_FORMAT" ", sstats->_page_armed); | |
| 1228 } | |
| 1229 tty->print_cr(INT32_FORMAT" ", sstats->_nof_threads_hit_page_trap); | |
| 1230 } | |
| 1231 } | |
| 1232 | |
| 1233 // This method will be called when VM exits. It will first call | |
| 1234 // print_statistics to print out the rest of the sampling. Then | |
| 1235 // it tries to summarize the sampling. | |
| 1236 void SafepointSynchronize::print_stat_on_exit() { | |
| 1237 if (_safepoint_stats == NULL) return; | |
| 1238 | |
| 1239 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; | |
| 1240 | |
| 1241 // During VM exit, end_statistics may not get called and in that | |
| 1242 // case, if the sync time is less than PrintSafepointStatisticsTimeout, | |
| 1243 // don't print it out. | |
| 1244 // Approximate the vm op time. | |
| 1245 _safepoint_stats[_cur_stat_index]._time_to_exec_vmop = | |
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1246 os::javaTimeNanos() - cleanup_end_time; |
| 0 | 1247 |
| 1248 if ( PrintSafepointStatisticsTimeout < 0 || | |
| 1249 spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) { | |
| 1250 print_statistics(); | |
| 1251 } | |
| 1252 tty->print_cr(""); | |
| 1253 | |
| 1254 // Print out polling page sampling status. | |
| 1255 if (!need_to_track_page_armed_status) { | |
| 1256 if (UseCompilerSafepoints) { | |
| 1257 tty->print_cr("Polling page always armed"); | |
| 1258 } | |
| 1259 } else { | |
| 1260 tty->print_cr("Defer polling page loop count = %d\n", | |
| 1261 DeferPollingPageLoopCount); | |
| 1262 } | |
| 1263 | |
| 1264 for (int index = 0; index < VM_Operation::VMOp_Terminating; index++) { | |
| 1265 if (_safepoint_reasons[index] != 0) { | |
| 1266 tty->print_cr("%-26s"UINT64_FORMAT_W(10), VM_Operation::name(index), | |
| 1267 _safepoint_reasons[index]); | |
| 1268 } | |
| 1269 } | |
| 1270 | |
| 1271 tty->print_cr(UINT64_FORMAT_W(5)" VM operations coalesced during safepoint", | |
| 1272 _coalesced_vmop_count); | |
| 1273 tty->print_cr("Maximum sync time "INT64_FORMAT_W(5)" ms", | |
| 1274 _max_sync_time / MICROUNITS); | |
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1275 tty->print_cr("Maximum vm operation time (except for Exit VM operation) " |
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1276 INT64_FORMAT_W(5)" ms", |
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1277 _max_vmop_time / MICROUNITS); |
| 0 | 1278 } |
| 1279 | |
| 1280 // ------------------------------------------------------------------------------------------------ | |
| 1281 // Non-product code | |
| 1282 | |
| 1283 #ifndef PRODUCT | |
| 1284 | |
| 1285 void SafepointSynchronize::print_state() { | |
| 1286 if (_state == _not_synchronized) { | |
| 1287 tty->print_cr("not synchronized"); | |
| 1288 } else if (_state == _synchronizing || _state == _synchronized) { | |
| 1289 tty->print_cr("State: %s", (_state == _synchronizing) ? "synchronizing" : | |
| 1290 "synchronized"); | |
| 1291 | |
| 1292 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) { | |
| 1293 cur->safepoint_state()->print(); | |
| 1294 } | |
| 1295 } | |
| 1296 } | |
| 1297 | |
| 1298 void SafepointSynchronize::safepoint_msg(const char* format, ...) { | |
| 1299 if (ShowSafepointMsgs) { | |
| 1300 va_list ap; | |
| 1301 va_start(ap, format); | |
| 1302 tty->vprint_cr(format, ap); | |
| 1303 va_end(ap); | |
| 1304 } | |
| 1305 } | |
| 1306 | |
| 1307 #endif // !PRODUCT |