annotate hotspot/src/share/vm/runtime/safepoint.cpp @ 46701:f559541c0daa

8181917: Refactor UL LogStreams to avoid using resource area Reviewed-by: ehelin, mlarsson
author stuefe
date Fri, 21 Jul 2017 09:50:12 +0200
parents 75aa3e39d02c
children 13ae789b982e
rev   line source
duke@1 1 /*
shade@46473 2 * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
duke@1 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@1 4 *
duke@1 5 * This code is free software; you can redistribute it and/or modify it
duke@1 6 * under the terms of the GNU General Public License version 2 only, as
duke@1 7 * published by the Free Software Foundation.
duke@1 8 *
duke@1 9 * This code is distributed in the hope that it will be useful, but WITHOUT
duke@1 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@1 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
duke@1 12 * version 2 for more details (a copy is included in the LICENSE file that
duke@1 13 * accompanied this code).
duke@1 14 *
duke@1 15 * You should have received a copy of the GNU General Public License version
duke@1 16 * 2 along with this work; if not, write to the Free Software Foundation,
duke@1 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@1 18 *
trims@5547 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
trims@5547 20 * or visit www.oracle.com if you need additional information or have any
trims@5547 21 * questions.
duke@1 22 *
duke@1 23 */
duke@1 24
stefank@7397 25 #include "precompiled.hpp"
gziemski@24426 26 #include "classfile/stringTable.hpp"
mgronlun@34666 27 #include "classfile/symbolTable.hpp"
stefank@7397 28 #include "classfile/systemDictionary.hpp"
stefank@7397 29 #include "code/codeCache.hpp"
stefank@7397 30 #include "code/icBuffer.hpp"
stefank@7397 31 #include "code/nmethod.hpp"
stefank@7397 32 #include "code/pcDesc.hpp"
stefank@7397 33 #include "code/scopeDesc.hpp"
pliden@30764 34 #include "gc/shared/collectedHeap.hpp"
pliden@30764 35 #include "gc/shared/gcLocker.inline.hpp"
stefank@7397 36 #include "interpreter/interpreter.hpp"
rprotacio@33763 37 #include "logging/log.hpp"
stuefe@46701 38 #include "logging/logStream.hpp"
stefank@7397 39 #include "memory/resourceArea.hpp"
stefank@7397 40 #include "memory/universe.inline.hpp"
stefank@7397 41 #include "oops/oop.inline.hpp"
coleenp@8076 42 #include "oops/symbol.hpp"
dholmes@40655 43 #include "runtime/atomic.hpp"
stefank@7397 44 #include "runtime/compilationPolicy.hpp"
stefank@7397 45 #include "runtime/deoptimization.hpp"
stefank@7397 46 #include "runtime/frame.inline.hpp"
stefank@7397 47 #include "runtime/interfaceSupport.hpp"
stefank@7397 48 #include "runtime/mutexLocker.hpp"
goetz@24351 49 #include "runtime/orderAccess.inline.hpp"
stefank@7397 50 #include "runtime/osThread.hpp"
stefank@7397 51 #include "runtime/safepoint.hpp"
stefank@7397 52 #include "runtime/signature.hpp"
stefank@7397 53 #include "runtime/stubCodeGenerator.hpp"
stefank@7397 54 #include "runtime/stubRoutines.hpp"
stefank@7397 55 #include "runtime/sweeper.hpp"
stefank@7397 56 #include "runtime/synchronizer.hpp"
stefank@14583 57 #include "runtime/thread.inline.hpp"
rehn@37161 58 #include "runtime/timerTrace.hpp"
stefank@7397 59 #include "services/runtimeService.hpp"
dsimms@37176 60 #include "trace/tracing.hpp"
dsimms@37176 61 #include "trace/traceMacros.hpp"
stefank@7397 62 #include "utilities/events.hpp"
jprovino@15482 63 #include "utilities/macros.hpp"
jprovino@15482 64 #if INCLUDE_ALL_GCS
pliden@30764 65 #include "gc/cms/concurrentMarkSweepThread.hpp"
pliden@30764 66 #include "gc/g1/suspendibleThreadSet.hpp"
jprovino@15482 67 #endif // INCLUDE_ALL_GCS
stefank@7397 68 #ifdef COMPILER1
stefank@7397 69 #include "c1/c1_globals.hpp"
stefank@7397 70 #endif
duke@1 71
duke@1 72 // --------------------------------------------------------------------------------------------------
duke@1 73 // Implementation of Safepoint begin/end
duke@1 74
duke@1 75 SafepointSynchronize::SynchronizeState volatile SafepointSynchronize::_state = SafepointSynchronize::_not_synchronized;
duke@1 76 volatile int SafepointSynchronize::_waiting_to_block = 0;
duke@1 77 volatile int SafepointSynchronize::_safepoint_counter = 0;
never@11631 78 int SafepointSynchronize::_current_jni_active_count = 0;
xlu@5042 79 long SafepointSynchronize::_end_of_last_safepoint = 0;
duke@1 80 static volatile int PageArmed = 0 ; // safepoint polling page is RO|RW vs PROT_NONE
duke@1 81 static volatile int TryingToBlock = 0 ; // proximate value -- for advisory use only
duke@1 82 static bool timeout_error_printed = false;
duke@1 83
duke@1 84 // Roll all threads forward to a safepoint and suspend them all
duke@1 85 void SafepointSynchronize::begin() {
dsimms@37176 86 EventSafepointBegin begin_event;
duke@1 87 Thread* myThread = Thread::current();
duke@1 88 assert(myThread->is_VM_thread(), "Only VM thread may execute a safepoint");
duke@1 89
xlu@5042 90 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) {
xlu@5042 91 _safepoint_begin_time = os::javaTimeNanos();
xlu@5042 92 _ts_of_current_safepoint = tty->time_stamp().seconds();
xlu@5042 93 }
duke@1 94
jprovino@15482 95 #if INCLUDE_ALL_GCS
duke@1 96 if (UseConcMarkSweepGC) {
duke@1 97 // In the future we should investigate whether CMS can use the
duke@1 98 // more-general mechanism below. DLD (01/05).
duke@1 99 ConcurrentMarkSweepThread::synchronize(false);
ysr@3262 100 } else if (UseG1GC) {
pliden@24094 101 SuspendibleThreadSet::synchronize();
duke@1 102 }
jprovino@15482 103 #endif // INCLUDE_ALL_GCS
duke@1 104
duke@1 105 // By getting the Threads_lock, we assure that no threads are about to start or
duke@1 106 // exit. It is released again in SafepointSynchronize::end().
duke@1 107 Threads_lock->lock();
duke@1 108
duke@1 109 assert( _state == _not_synchronized, "trying to safepoint synchronize with wrong state");
duke@1 110
duke@1 111 int nof_threads = Threads::number_of_threads();
duke@1 112
rprotacio@33763 113 log_debug(safepoint)("Safepoint synchronization initiated. (%d)", nof_threads);
duke@1 114
duke@1 115 RuntimeService::record_safepoint_begin();
duke@1 116
duke@1 117 MutexLocker mu(Safepoint_lock);
duke@1 118
never@11631 119 // Reset the count of active JNI critical threads
never@11631 120 _current_jni_active_count = 0;
never@11631 121
duke@1 122 // Set number of threads to wait for, before we initiate the callbacks
duke@1 123 _waiting_to_block = nof_threads;
duke@1 124 TryingToBlock = 0 ;
duke@1 125 int still_running = nof_threads;
duke@1 126
duke@1 127 // Save the starting time, so that it can be compared to see if this has taken
duke@1 128 // too long to complete.
goetz@33589 129 jlong safepoint_limit_time = 0;
duke@1 130 timeout_error_printed = false;
duke@1 131
xlu@4006 132 // PrintSafepointStatisticsTimeout can be specified separately. When
xlu@4006 133 // specified, PrintSafepointStatistics will be set to true in
xlu@4006 134 // deferred_initialize_stat method. The initialization has to be done
xlu@4006 135 // early enough to avoid any races. See bug 6880029 for details.
xlu@4006 136 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) {
xlu@4006 137 deferred_initialize_stat();
xlu@4006 138 }
xlu@4006 139
duke@1 140 // Begin the process of bringing the system to a safepoint.
duke@1 141 // Java threads can be in several different states and are
duke@1 142 // stopped by different mechanisms:
duke@1 143 //
duke@1 144 // 1. Running interpreted
jwilhelm@22551 145 // The interpreter dispatch table is changed to force it to
duke@1 146 // check for a safepoint condition between bytecodes.
duke@1 147 // 2. Running in native code
duke@1 148 // When returning from the native code, a Java thread must check
duke@1 149 // the safepoint _state to see if we must block. If the
duke@1 150 // VM thread sees a Java thread in native, it does
duke@1 151 // not wait for this thread to block. The order of the memory
duke@1 152 // writes and reads of both the safepoint state and the Java
duke@1 153 // threads state is critical. In order to guarantee that the
duke@1 154 // memory writes are serialized with respect to each other,
duke@1 155 // the VM thread issues a memory barrier instruction
duke@1 156 // (on MP systems). In order to avoid the overhead of issuing
duke@1 157 // a memory barrier for each Java thread making native calls, each Java
duke@1 158 // thread performs a write to a single memory page after changing
duke@1 159 // the thread state. The VM thread performs a sequence of
duke@1 160 // mprotect OS calls which forces all previous writes from all
duke@1 161 // Java threads to be serialized. This is done in the
duke@1 162 // os::serialize_thread_states() call. This has proven to be
duke@1 163 // much more efficient than executing a membar instruction
duke@1 164 // on every call to native code.
duke@1 165 // 3. Running compiled Code
duke@1 166 // Compiled code reads a global (Safepoint Polling) page that
duke@1 167 // is set to fault if we are trying to get to a safepoint.
duke@1 168 // 4. Blocked
duke@1 169 // A thread which is blocked will not be allowed to return from the
duke@1 170 // block condition until the safepoint operation is complete.
duke@1 171 // 5. In VM or Transitioning between states
duke@1 172 // If a Java thread is currently running in the VM or transitioning
duke@1 173 // between states, the safepointing code will wait for the thread to
duke@1 174 // block itself when it attempts transitions to a new state.
duke@1 175 //
dsimms@37176 176 {
egahlin@40664 177 EventSafepointStateSynchronization sync_event;
dsimms@37176 178 int initial_running = 0;
duke@1 179
dsimms@37176 180 _state = _synchronizing;
dsimms@37176 181 OrderAccess::fence();
duke@1 182
dsimms@37176 183 // Flush all thread states to memory
dsimms@37176 184 if (!UseMembar) {
dsimms@37176 185 os::serialize_thread_states();
dsimms@37176 186 }
duke@1 187
dsimms@37176 188 // Make interpreter safepoint aware
dsimms@37176 189 Interpreter::notice_safepoints();
duke@1 190
dsimms@37176 191 if (DeferPollingPageLoopCount < 0) {
dsimms@37176 192 // Make polling safepoint aware
dsimms@37176 193 guarantee (PageArmed == 0, "invariant") ;
dsimms@37176 194 PageArmed = 1 ;
dsimms@37176 195 os::make_polling_page_unreadable();
dsimms@37176 196 }
dsimms@37176 197
dsimms@37176 198 // Consider using active_processor_count() ... but that call is expensive.
dsimms@37176 199 int ncpus = os::processor_count() ;
duke@1 200
duke@1 201 #ifdef ASSERT
dsimms@37176 202 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) {
dsimms@37176 203 assert(cur->safepoint_state()->is_running(), "Illegal initial state");
dsimms@37176 204 // Clear the visited flag to ensure that the critical counts are collected properly.
dsimms@37176 205 cur->set_visited_for_critical_count(false);
dsimms@37176 206 }
duke@1 207 #endif // ASSERT
duke@1 208
dsimms@37176 209 if (SafepointTimeout)
dsimms@37176 210 safepoint_limit_time = os::javaTimeNanos() + (jlong)SafepointTimeoutDelay * MICROUNITS;
duke@1 211
dsimms@37176 212 // Iterate through all threads until it have been determined how to stop them all at a safepoint
dsimms@37176 213 unsigned int iterations = 0;
dsimms@37176 214 int steps = 0 ;
dsimms@37176 215 while(still_running > 0) {
dsimms@37176 216 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) {
dsimms@37176 217 assert(!cur->is_ConcurrentGC_thread(), "A concurrent GC thread is unexpectly being suspended");
dsimms@37176 218 ThreadSafepointState *cur_state = cur->safepoint_state();
dsimms@37176 219 if (cur_state->is_running()) {
dsimms@37176 220 cur_state->examine_state_of_thread();
dsimms@37176 221 if (!cur_state->is_running()) {
dsimms@37176 222 still_running--;
dsimms@37176 223 // consider adjusting steps downward:
dsimms@37176 224 // steps = 0
dsimms@37176 225 // steps -= NNN
dsimms@37176 226 // steps >>= 1
dsimms@37176 227 // steps = MIN(steps, 2000-100)
dsimms@37176 228 // if (iterations != 0) steps -= NNN
dsimms@37176 229 }
stuefe@46701 230 LogTarget(Trace, safepoint) lt;
stuefe@46701 231 if (lt.is_enabled()) {
dsimms@37176 232 ResourceMark rm;
stuefe@46701 233 LogStream ls(lt);
stuefe@46701 234 cur_state->print_on(&ls);
dsimms@37176 235 }
duke@1 236 }
dsimms@37176 237 }
dsimms@37176 238
dsimms@37176 239 if (iterations == 0) {
dsimms@37176 240 initial_running = still_running;
dsimms@37176 241 if (PrintSafepointStatistics) {
dsimms@37176 242 begin_statistics(nof_threads, still_running);
dsimms@37176 243 }
dsimms@37176 244 }
dsimms@37176 245
dsimms@37176 246 if (still_running > 0) {
dsimms@37176 247 // Check for if it takes to long
dsimms@37176 248 if (SafepointTimeout && safepoint_limit_time < os::javaTimeNanos()) {
dsimms@37176 249 print_safepoint_timeout(_spinning_timeout);
dsimms@37176 250 }
dsimms@37176 251
dsimms@37176 252 // Spin to avoid context switching.
dsimms@37176 253 // There's a tension between allowing the mutators to run (and rendezvous)
dsimms@37176 254 // vs spinning. As the VM thread spins, wasting cycles, it consumes CPU that
dsimms@37176 255 // a mutator might otherwise use profitably to reach a safepoint. Excessive
dsimms@37176 256 // spinning by the VM thread on a saturated system can increase rendezvous latency.
dsimms@37176 257 // Blocking or yielding incur their own penalties in the form of context switching
dsimms@37176 258 // and the resultant loss of $ residency.
dsimms@37176 259 //
dsimms@37176 260 // Further complicating matters is that yield() does not work as naively expected
dsimms@37176 261 // on many platforms -- yield() does not guarantee that any other ready threads
dsimms@37176 262 // will run. As such we revert to naked_short_sleep() after some number of iterations.
dsimms@37176 263 // nakes_short_sleep() is implemented as a short unconditional sleep.
dsimms@37176 264 // Typical operating systems round a "short" sleep period up to 10 msecs, so sleeping
dsimms@37176 265 // can actually increase the time it takes the VM thread to detect that a system-wide
dsimms@37176 266 // stop-the-world safepoint has been reached. In a pathological scenario such as that
dsimms@37176 267 // described in CR6415670 the VMthread may sleep just before the mutator(s) become safe.
dsimms@37176 268 // In that case the mutators will be stalled waiting for the safepoint to complete and the
dsimms@37176 269 // the VMthread will be sleeping, waiting for the mutators to rendezvous. The VMthread
dsimms@37176 270 // will eventually wake up and detect that all mutators are safe, at which point
dsimms@37176 271 // we'll again make progress.
dsimms@37176 272 //
dsimms@37176 273 // Beware too that that the VMThread typically runs at elevated priority.
dsimms@37176 274 // Its default priority is higher than the default mutator priority.
dsimms@37176 275 // Obviously, this complicates spinning.
dsimms@37176 276 //
dsimms@37176 277 // Note too that on Windows XP SwitchThreadTo() has quite different behavior than Sleep(0).
dsimms@37176 278 // Sleep(0) will _not yield to lower priority threads, while SwitchThreadTo() will.
dsimms@37176 279 //
dsimms@37176 280 // See the comments in synchronizer.cpp for additional remarks on spinning.
dsimms@37176 281 //
dsimms@37176 282 // In the future we might:
dsimms@37176 283 // 1. Modify the safepoint scheme to avoid potentially unbounded spinning.
dsimms@37176 284 // This is tricky as the path used by a thread exiting the JVM (say on
dsimms@37176 285 // on JNI call-out) simply stores into its state field. The burden
dsimms@37176 286 // is placed on the VM thread, which must poll (spin).
dsimms@37176 287 // 2. Find something useful to do while spinning. If the safepoint is GC-related
dsimms@37176 288 // we might aggressively scan the stacks of threads that are already safe.
dsimms@37176 289 // 3. Use Solaris schedctl to examine the state of the still-running mutators.
dsimms@37176 290 // If all the mutators are ONPROC there's no reason to sleep or yield.
dsimms@37176 291 // 4. YieldTo() any still-running mutators that are ready but OFFPROC.
dsimms@37176 292 // 5. Check system saturation. If the system is not fully saturated then
dsimms@37176 293 // simply spin and avoid sleep/yield.
dsimms@37176 294 // 6. As still-running mutators rendezvous they could unpark the sleeping
dsimms@37176 295 // VMthread. This works well for still-running mutators that become
dsimms@37176 296 // safe. The VMthread must still poll for mutators that call-out.
dsimms@37176 297 // 7. Drive the policy on time-since-begin instead of iterations.
dsimms@37176 298 // 8. Consider making the spin duration a function of the # of CPUs:
dsimms@37176 299 // Spin = (((ncpus-1) * M) + K) + F(still_running)
dsimms@37176 300 // Alternately, instead of counting iterations of the outer loop
dsimms@37176 301 // we could count the # of threads visited in the inner loop, above.
dsimms@37176 302 // 9. On windows consider using the return value from SwitchThreadTo()
dsimms@37176 303 // to drive subsequent spin/SwitchThreadTo()/Sleep(N) decisions.
dsimms@37176 304
dsimms@37176 305 if (int(iterations) == DeferPollingPageLoopCount) {
dsimms@37176 306 guarantee (PageArmed == 0, "invariant") ;
dsimms@37176 307 PageArmed = 1 ;
dsimms@37176 308 os::make_polling_page_unreadable();
dsimms@37176 309 }
dsimms@37176 310
dsimms@37176 311 // Instead of (ncpus > 1) consider either (still_running < (ncpus + EPSILON)) or
dsimms@37176 312 // ((still_running + _waiting_to_block - TryingToBlock)) < ncpus)
dsimms@37176 313 ++steps ;
dsimms@37176 314 if (ncpus > 1 && steps < SafepointSpinBeforeYield) {
dsimms@37176 315 SpinPause() ; // MP-Polite spin
dsimms@37176 316 } else
dsimms@37176 317 if (steps < DeferThrSuspendLoopCount) {
dsimms@37176 318 os::naked_yield() ;
dsimms@37176 319 } else {
dsimms@37176 320 os::naked_short_sleep(1);
dsimms@37176 321 }
dsimms@37176 322
dsimms@37176 323 iterations ++ ;
dsimms@37176 324 }
dsimms@37176 325 assert(iterations < (uint)max_jint, "We have been iterating in the safepoint loop too long");
dsimms@37176 326 }
dsimms@37176 327 assert(still_running == 0, "sanity check");
dsimms@37176 328
dsimms@37176 329 if (PrintSafepointStatistics) {
dsimms@37176 330 update_statistics_on_spin_end();
dsimms@37176 331 }
dsimms@37176 332
dsimms@37176 333 if (sync_event.should_commit()) {
dsimms@37176 334 sync_event.set_safepointId(safepoint_counter());
dsimms@37176 335 sync_event.set_initialThreadCount(initial_running);
dsimms@37176 336 sync_event.set_runningThreadCount(_waiting_to_block);
dsimms@37176 337 sync_event.set_iterations(iterations);
dsimms@37176 338 sync_event.commit();
dsimms@37176 339 }
dsimms@37176 340 } //EventSafepointStateSync
dsimms@37176 341
dsimms@37176 342 // wait until all threads are stopped
dsimms@37176 343 {
dsimms@37176 344 EventSafepointWaitBlocked wait_blocked_event;
dsimms@37176 345 int initial_waiting_to_block = _waiting_to_block;
dsimms@37176 346
dsimms@37176 347 while (_waiting_to_block > 0) {
dsimms@37176 348 log_debug(safepoint)("Waiting for %d thread(s) to block", _waiting_to_block);
dsimms@37176 349 if (!SafepointTimeout || timeout_error_printed) {
dsimms@37176 350 Safepoint_lock->wait(true); // true, means with no safepoint checks
dsimms@37176 351 } else {
dsimms@37176 352 // Compute remaining time
dsimms@37176 353 jlong remaining_time = safepoint_limit_time - os::javaTimeNanos();
dsimms@37176 354
dsimms@37176 355 // If there is no remaining time, then there is an error
dsimms@37176 356 if (remaining_time < 0 || Safepoint_lock->wait(true, remaining_time / MICROUNITS)) {
dsimms@37176 357 print_safepoint_timeout(_blocking_timeout);
rprotacio@33763 358 }
duke@1 359 }
duke@1 360 }
dsimms@37176 361 assert(_waiting_to_block == 0, "sanity check");
duke@1 362
dsimms@37176 363 #ifndef PRODUCT
dsimms@37176 364 if (SafepointTimeout) {
dsimms@37176 365 jlong current_time = os::javaTimeNanos();
dsimms@37176 366 if (safepoint_limit_time < current_time) {
dsimms@37176 367 tty->print_cr("# SafepointSynchronize: Finished after "
dsimms@37176 368 INT64_FORMAT_W(6) " ms",
jwilhelm@46630 369 (int64_t)((current_time - safepoint_limit_time) / MICROUNITS +
jwilhelm@46630 370 (jlong)SafepointTimeoutDelay));
duke@1 371 }
duke@1 372 }
duke@1 373 #endif
duke@1 374
dsimms@37176 375 assert((_safepoint_counter & 0x1) == 0, "must be even");
dsimms@37176 376 assert(Threads_lock->owned_by_self(), "must hold Threads_lock");
dsimms@37176 377 _safepoint_counter ++;
duke@1 378
dsimms@37176 379 // Record state
dsimms@37176 380 _state = _synchronized;
duke@1 381
dsimms@37176 382 OrderAccess::fence();
dsimms@37176 383
dsimms@37176 384 if (wait_blocked_event.should_commit()) {
dsimms@37176 385 wait_blocked_event.set_safepointId(safepoint_counter());
dsimms@37176 386 wait_blocked_event.set_runningThreadCount(initial_waiting_to_block);
dsimms@37176 387 wait_blocked_event.commit();
dsimms@37176 388 }
dsimms@37176 389 } // EventSafepointWaitBlocked
duke@1 390
never@12108 391 #ifdef ASSERT
never@12108 392 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) {
never@12108 393 // make sure all the threads were visited
never@12108 394 assert(cur->was_visited_for_critical_count(), "missed a thread");
never@12108 395 }
never@12108 396 #endif // ASSERT
never@12108 397
never@11631 398 // Update the count of active JNI critical regions
david@35492 399 GCLocker::set_jni_lock_count(_current_jni_active_count);
never@11631 400
rprotacio@33763 401 if (log_is_enabled(Debug, safepoint)) {
rehn@46496 402 log_debug(safepoint)("Entering safepoint region: %s", VMThread::vm_safepoint_description());
duke@1 403 }
duke@1 404
duke@1 405 RuntimeService::record_safepoint_synchronized();
duke@1 406 if (PrintSafepointStatistics) {
duke@1 407 update_statistics_on_sync_end(os::javaTimeNanos());
duke@1 408 }
duke@1 409
duke@1 410 // Call stuff that needs to be run when a safepoint is just about to be completed
dsimms@37176 411 {
dsimms@37176 412 EventSafepointCleanup cleanup_event;
dsimms@37176 413 do_cleanup_tasks();
dsimms@37176 414 if (cleanup_event.should_commit()) {
dsimms@37176 415 cleanup_event.set_safepointId(safepoint_counter());
dsimms@37176 416 cleanup_event.commit();
dsimms@37176 417 }
dsimms@37176 418 }
xlu@5042 419
xlu@5042 420 if (PrintSafepointStatistics) {
xlu@5042 421 // Record how much time spend on the above cleanup tasks
xlu@5042 422 update_statistics_on_cleanup_end(os::javaTimeNanos());
xlu@5042 423 }
dsimms@37176 424 if (begin_event.should_commit()) {
dsimms@37176 425 begin_event.set_safepointId(safepoint_counter());
dsimms@37176 426 begin_event.set_totalThreadCount(nof_threads);
dsimms@37176 427 begin_event.set_jniCriticalThreadCount(_current_jni_active_count);
dsimms@37176 428 begin_event.commit();
dsimms@37176 429 }
duke@1 430 }
duke@1 431
duke@1 432 // Wake up all threads, so they are ready to resume execution after the safepoint
duke@1 433 // operation has been carried out
duke@1 434 void SafepointSynchronize::end() {
dsimms@37176 435 EventSafepointEnd event;
dsimms@37176 436 int safepoint_id = safepoint_counter(); // Keep the odd counter as "id"
duke@1 437
duke@1 438 assert(Threads_lock->owned_by_self(), "must hold Threads_lock");
duke@1 439 assert((_safepoint_counter & 0x1) == 1, "must be odd");
duke@1 440 _safepoint_counter ++;
duke@1 441 // memory fence isn't required here since an odd _safepoint_counter
duke@1 442 // value can do no harm and a fence is issued below anyway.
duke@1 443
duke@1 444 DEBUG_ONLY(Thread* myThread = Thread::current();)
duke@1 445 assert(myThread->is_VM_thread(), "Only VM thread can execute a safepoint");
duke@1 446
duke@1 447 if (PrintSafepointStatistics) {
duke@1 448 end_statistics(os::javaTimeNanos());
duke@1 449 }
duke@1 450
duke@1 451 #ifdef ASSERT
duke@1 452 // A pending_exception cannot be installed during a safepoint. The threads
duke@1 453 // may install an async exception after they come back from a safepoint into
duke@1 454 // pending_exception after they unblock. But that should happen later.
duke@1 455 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) {
duke@1 456 assert (!(cur->has_pending_exception() &&
duke@1 457 cur->safepoint_state()->is_at_poll_safepoint()),
duke@1 458 "safepoint installed a pending exception");
duke@1 459 }
duke@1 460 #endif // ASSERT
duke@1 461
duke@1 462 if (PageArmed) {
duke@1 463 // Make polling safepoint aware
duke@1 464 os::make_polling_page_readable();
duke@1 465 PageArmed = 0 ;
duke@1 466 }
duke@1 467
duke@1 468 // Remove safepoint check from interpreter
duke@1 469 Interpreter::ignore_safepoints();
duke@1 470
duke@1 471 {
duke@1 472 MutexLocker mu(Safepoint_lock);
duke@1 473
duke@1 474 assert(_state == _synchronized, "must be synchronized before ending safepoint synchronization");
duke@1 475
duke@1 476 // Set to not synchronized, so the threads will not go into the signal_thread_blocked method
duke@1 477 // when they get restarted.
duke@1 478 _state = _not_synchronized;
duke@1 479 OrderAccess::fence();
duke@1 480
rprotacio@33763 481 log_debug(safepoint)("Leaving safepoint region");
duke@1 482
duke@1 483 // Start suspended threads
duke@1 484 for(JavaThread *current = Threads::first(); current; current = current->next()) {
twisti@2131 485 // A problem occurring on Solaris is when attempting to restart threads
duke@1 486 // the first #cpus - 1 go well, but then the VMThread is preempted when we get
duke@1 487 // to the next one (since it has been running the longest). We then have
duke@1 488 // to wait for a cpu to become available before we can continue restarting
duke@1 489 // threads.
duke@1 490 // FIXME: This causes the performance of the VM to degrade when active and with
duke@1 491 // large numbers of threads. Apparently this is due to the synchronous nature
duke@1 492 // of suspending threads.
duke@1 493 //
duke@1 494 // TODO-FIXME: the comments above are vestigial and no longer apply.
duke@1 495 // Furthermore, using solaris' schedctl in this particular context confers no benefit
duke@1 496 if (VMThreadHintNoPreempt) {
duke@1 497 os::hint_no_preempt();
duke@1 498 }
duke@1 499 ThreadSafepointState* cur_state = current->safepoint_state();
duke@1 500 assert(cur_state->type() != ThreadSafepointState::_running, "Thread not suspended at safepoint");
duke@1 501 cur_state->restart();
duke@1 502 assert(cur_state->is_running(), "safepoint state has not been reset");
duke@1 503 }
duke@1 504
duke@1 505 RuntimeService::record_safepoint_end();
duke@1 506
duke@1 507 // Release threads lock, so threads can be created/destroyed again. It will also starts all threads
duke@1 508 // blocked in signal_thread_blocked
duke@1 509 Threads_lock->unlock();
duke@1 510
duke@1 511 }
jprovino@15482 512 #if INCLUDE_ALL_GCS
duke@1 513 // If there are any concurrent GC threads resume them.
duke@1 514 if (UseConcMarkSweepGC) {
duke@1 515 ConcurrentMarkSweepThread::desynchronize(false);
ysr@3262 516 } else if (UseG1GC) {
pliden@24094 517 SuspendibleThreadSet::desynchronize();
duke@1 518 }
jprovino@15482 519 #endif // INCLUDE_ALL_GCS
jwilhelm@22551 520 // record this time so VMThread can keep track how much time has elapsed
xlu@5042 521 // since last safepoint.
xlu@5042 522 _end_of_last_safepoint = os::javaTimeMillis();
dsimms@37176 523
dsimms@37176 524 if (event.should_commit()) {
dsimms@37176 525 event.set_safepointId(safepoint_id);
dsimms@37176 526 event.commit();
dsimms@37176 527 }
duke@1 528 }
duke@1 529
duke@1 530 bool SafepointSynchronize::is_cleanup_needed() {
rehn@46541 531 // Need a safepoint if there are many monitors to deflate.
rehn@46541 532 if (ObjectSynchronizer::is_cleanup_needed()) return true;
duke@1 533 // Need a safepoint if some inline cache buffers is non-empty
duke@1 534 if (!InlineCacheBuffer::is_empty()) return true;
duke@1 535 return false;
duke@1 536 }
duke@1 537
dsimms@37176 538 static void event_safepoint_cleanup_task_commit(EventSafepointCleanupTask& event, const char* name) {
dsimms@37176 539 if (event.should_commit()) {
dsimms@37176 540 event.set_safepointId(SafepointSynchronize::safepoint_counter());
dsimms@37176 541 event.set_name(name);
dsimms@37176 542 event.commit();
dsimms@37176 543 }
dsimms@37176 544 }
duke@1 545
duke@1 546 // Various cleaning tasks that should be done periodically at safepoints
duke@1 547 void SafepointSynchronize::do_cleanup_tasks() {
xlu@5042 548 {
dsimms@37176 549 const char* name = "deflating idle monitors";
dsimms@37176 550 EventSafepointCleanupTask event;
mockner@38151 551 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
xlu@5042 552 ObjectSynchronizer::deflate_idle_monitors();
dsimms@37176 553 event_safepoint_cleanup_task_commit(event, name);
duke@1 554 }
duke@1 555
xlu@5042 556 {
dsimms@37176 557 const char* name = "updating inline caches";
dsimms@37176 558 EventSafepointCleanupTask event;
mockner@38151 559 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
xlu@5042 560 InlineCacheBuffer::update_inline_caches();
dsimms@37176 561 event_safepoint_cleanup_task_commit(event, name);
xlu@5042 562 }
iveresov@6453 563 {
dsimms@37176 564 const char* name = "compilation policy safepoint handler";
dsimms@37176 565 EventSafepointCleanupTask event;
mockner@38151 566 TraceTime timer("compilation policy safepoint handler", TRACETIME_LOG(Info, safepoint, cleanup));
iveresov@6453 567 CompilationPolicy::policy()->do_safepoint_work();
dsimms@37176 568 event_safepoint_cleanup_task_commit(event, name);
duke@1 569 }
xlu@5042 570
coleenp@13087 571 {
dsimms@37176 572 const char* name = "mark nmethods";
dsimms@37176 573 EventSafepointCleanupTask event;
mockner@38151 574 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
anoll@20290 575 NMethodSweeper::mark_active_nmethods();
dsimms@37176 576 event_safepoint_cleanup_task_commit(event, name);
coleenp@13087 577 }
coleenp@13087 578
coleenp@13087 579 if (SymbolTable::needs_rehashing()) {
dsimms@37176 580 const char* name = "rehashing symbol table";
dsimms@37176 581 EventSafepointCleanupTask event;
mockner@38151 582 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
coleenp@13087 583 SymbolTable::rehash_table();
dsimms@37176 584 event_safepoint_cleanup_task_commit(event, name);
coleenp@13087 585 }
coleenp@13087 586
coleenp@13087 587 if (StringTable::needs_rehashing()) {
dsimms@37176 588 const char* name = "rehashing string table";
dsimms@37176 589 EventSafepointCleanupTask event;
mockner@38151 590 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
coleenp@13087 591 StringTable::rehash_table();
dsimms@37176 592 event_safepoint_cleanup_task_commit(event, name);
coleenp@13087 593 }
minqi@9990 594
coleenp@24457 595 {
coleenp@24457 596 // CMS delays purging the CLDG until the beginning of the next safepoint and to
coleenp@24457 597 // make sure concurrent sweep is done
dsimms@37176 598 const char* name = "purging class loader data graph";
dsimms@37176 599 EventSafepointCleanupTask event;
mockner@38151 600 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
coleenp@24457 601 ClassLoaderDataGraph::purge_if_needed();
dsimms@37176 602 event_safepoint_cleanup_task_commit(event, name);
coleenp@24457 603 }
duke@1 604 }
duke@1 605
duke@1 606
duke@1 607 bool SafepointSynchronize::safepoint_safe(JavaThread *thread, JavaThreadState state) {
duke@1 608 switch(state) {
duke@1 609 case _thread_in_native:
duke@1 610 // native threads are safe if they have no java stack or have walkable stack
duke@1 611 return !thread->has_last_Java_frame() || thread->frame_anchor()->walkable();
duke@1 612
duke@1 613 // blocked threads should have already have walkable stack
duke@1 614 case _thread_blocked:
duke@1 615 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "blocked and not walkable");
duke@1 616 return true;
duke@1 617
duke@1 618 default:
duke@1 619 return false;
duke@1 620 }
duke@1 621 }
duke@1 622
duke@1 623
never@11637 624 // See if the thread is running inside a lazy critical native and
never@11637 625 // update the thread critical count if so. Also set a suspend flag to
never@11637 626 // cause the native wrapper to return into the JVM to do the unlock
never@11637 627 // once the native finishes.
never@11637 628 void SafepointSynchronize::check_for_lazy_critical_native(JavaThread *thread, JavaThreadState state) {
never@11637 629 if (state == _thread_in_native &&
never@11637 630 thread->has_last_Java_frame() &&
never@11637 631 thread->frame_anchor()->walkable()) {
never@11637 632 // This thread might be in a critical native nmethod so look at
never@11637 633 // the top of the stack and increment the critical count if it
never@11637 634 // is.
never@11637 635 frame wrapper_frame = thread->last_frame();
never@11637 636 CodeBlob* stub_cb = wrapper_frame.cb();
never@11637 637 if (stub_cb != NULL &&
never@11637 638 stub_cb->is_nmethod() &&
never@11637 639 stub_cb->as_nmethod_or_null()->is_lazy_critical_native()) {
never@11637 640 // A thread could potentially be in a critical native across
never@11637 641 // more than one safepoint, so only update the critical state on
never@11637 642 // the first one. When it returns it will perform the unlock.
never@11637 643 if (!thread->do_critical_native_unlock()) {
never@11637 644 #ifdef ASSERT
never@11637 645 if (!thread->in_critical()) {
david@35492 646 GCLocker::increment_debug_jni_lock_count();
never@11637 647 }
never@11637 648 #endif
never@11637 649 thread->enter_critical();
never@11637 650 // Make sure the native wrapper calls back on return to
never@11637 651 // perform the needed critical unlock.
never@11637 652 thread->set_critical_native_unlock();
never@11637 653 }
never@11637 654 }
never@11637 655 }
never@11637 656 }
never@11637 657
never@11637 658
never@11637 659
duke@1 660 // -------------------------------------------------------------------------------------------------------
duke@1 661 // Implementation of Safepoint callback point
duke@1 662
duke@1 663 void SafepointSynchronize::block(JavaThread *thread) {
duke@1 664 assert(thread != NULL, "thread must be set");
duke@1 665 assert(thread->is_Java_thread(), "not a Java thread");
duke@1 666
duke@1 667 // Threads shouldn't block if they are in the middle of printing, but...
duke@1 668 ttyLocker::break_tty_lock_for_safepoint(os::current_thread_id());
duke@1 669
duke@1 670 // Only bail from the block() call if the thread is gone from the
duke@1 671 // thread list; starting to exit should still block.
duke@1 672 if (thread->is_terminated()) {
duke@1 673 // block current thread if we come here from native code when VM is gone
duke@1 674 thread->block_if_vm_exited();
duke@1 675
duke@1 676 // otherwise do nothing
duke@1 677 return;
duke@1 678 }
duke@1 679
duke@1 680 JavaThreadState state = thread->thread_state();
duke@1 681 thread->frame_anchor()->make_walkable(thread);
duke@1 682
duke@1 683 // Check that we have a valid thread_state at this point
duke@1 684 switch(state) {
duke@1 685 case _thread_in_vm_trans:
duke@1 686 case _thread_in_Java: // From compiled code
duke@1 687
duke@1 688 // We are highly likely to block on the Safepoint_lock. In order to avoid blocking in this case,
duke@1 689 // we pretend we are still in the VM.
duke@1 690 thread->set_thread_state(_thread_in_vm);
duke@1 691
duke@1 692 if (is_synchronizing()) {
duke@1 693 Atomic::inc (&TryingToBlock) ;
duke@1 694 }
duke@1 695
duke@1 696 // We will always be holding the Safepoint_lock when we are examine the state
duke@1 697 // of a thread. Hence, the instructions between the Safepoint_lock->lock() and
duke@1 698 // Safepoint_lock->unlock() are happening atomic with regards to the safepoint code
duke@1 699 Safepoint_lock->lock_without_safepoint_check();
duke@1 700 if (is_synchronizing()) {
duke@1 701 // Decrement the number of threads to wait for and signal vm thread
duke@1 702 assert(_waiting_to_block > 0, "sanity check");
duke@1 703 _waiting_to_block--;
duke@1 704 thread->safepoint_state()->set_has_called_back(true);
duke@1 705
never@12108 706 DEBUG_ONLY(thread->set_visited_for_critical_count(true));
never@11631 707 if (thread->in_critical()) {
never@11631 708 // Notice that this thread is in a critical section
never@11631 709 increment_jni_active_count();
never@11631 710 }
never@11631 711
duke@1 712 // Consider (_waiting_to_block < 2) to pipeline the wakeup of the VM thread
duke@1 713 if (_waiting_to_block == 0) {
duke@1 714 Safepoint_lock->notify_all();
duke@1 715 }
duke@1 716 }
duke@1 717
duke@1 718 // We transition the thread to state _thread_blocked here, but
duke@1 719 // we can't do our usual check for external suspension and then
duke@1 720 // self-suspend after the lock_without_safepoint_check() call
duke@1 721 // below because we are often called during transitions while
duke@1 722 // we hold different locks. That would leave us suspended while
duke@1 723 // holding a resource which results in deadlocks.
duke@1 724 thread->set_thread_state(_thread_blocked);
duke@1 725 Safepoint_lock->unlock();
duke@1 726
duke@1 727 // We now try to acquire the threads lock. Since this lock is hold by the VM thread during
duke@1 728 // the entire safepoint, the threads will all line up here during the safepoint.
duke@1 729 Threads_lock->lock_without_safepoint_check();
duke@1 730 // restore original state. This is important if the thread comes from compiled code, so it
duke@1 731 // will continue to execute with the _thread_in_Java state.
duke@1 732 thread->set_thread_state(state);
duke@1 733 Threads_lock->unlock();
duke@1 734 break;
duke@1 735
duke@1 736 case _thread_in_native_trans:
duke@1 737 case _thread_blocked_trans:
duke@1 738 case _thread_new_trans:
duke@1 739 if (thread->safepoint_state()->type() == ThreadSafepointState::_call_back) {
duke@1 740 thread->print_thread_state();
duke@1 741 fatal("Deadlock in safepoint code. "
duke@1 742 "Should have called back to the VM before blocking.");
duke@1 743 }
duke@1 744
duke@1 745 // We transition the thread to state _thread_blocked here, but
duke@1 746 // we can't do our usual check for external suspension and then
duke@1 747 // self-suspend after the lock_without_safepoint_check() call
duke@1 748 // below because we are often called during transitions while
duke@1 749 // we hold different locks. That would leave us suspended while
duke@1 750 // holding a resource which results in deadlocks.
duke@1 751 thread->set_thread_state(_thread_blocked);
duke@1 752
duke@1 753 // It is not safe to suspend a thread if we discover it is in _thread_in_native_trans. Hence,
duke@1 754 // the safepoint code might still be waiting for it to block. We need to change the state here,
duke@1 755 // so it can see that it is at a safepoint.
duke@1 756
duke@1 757 // Block until the safepoint operation is completed.
duke@1 758 Threads_lock->lock_without_safepoint_check();
duke@1 759
duke@1 760 // Restore state
duke@1 761 thread->set_thread_state(state);
duke@1 762
duke@1 763 Threads_lock->unlock();
duke@1 764 break;
duke@1 765
duke@1 766 default:
david@33105 767 fatal("Illegal threadstate encountered: %d", state);
duke@1 768 }
duke@1 769
duke@1 770 // Check for pending. async. exceptions or suspends - except if the
duke@1 771 // thread was blocked inside the VM. has_special_runtime_exit_condition()
duke@1 772 // is called last since it grabs a lock and we only want to do that when
duke@1 773 // we must.
duke@1 774 //
duke@1 775 // Note: we never deliver an async exception at a polling point as the
duke@1 776 // compiler may not have an exception handler for it. The polling
duke@1 777 // code will notice the async and deoptimize and the exception will
duke@1 778 // be delivered. (Polling at a return point is ok though). Sure is
duke@1 779 // a lot of bother for a deprecated feature...
duke@1 780 //
duke@1 781 // We don't deliver an async exception if the thread state is
duke@1 782 // _thread_in_native_trans so JNI functions won't be called with
duke@1 783 // a surprising pending exception. If the thread state is going back to java,
duke@1 784 // async exception is checked in check_special_condition_for_native_trans().
duke@1 785
duke@1 786 if (state != _thread_blocked_trans &&
duke@1 787 state != _thread_in_vm_trans &&
duke@1 788 thread->has_special_runtime_exit_condition()) {
duke@1 789 thread->handle_special_runtime_exit_condition(
duke@1 790 !thread->is_at_poll_safepoint() && (state != _thread_in_native_trans));
duke@1 791 }
duke@1 792 }
duke@1 793
duke@1 794 // ------------------------------------------------------------------------------------------------------
duke@1 795 // Exception handlers
duke@1 796
duke@1 797
duke@1 798 void SafepointSynchronize::handle_polling_page_exception(JavaThread *thread) {
duke@1 799 assert(thread->is_Java_thread(), "polling reference encountered by VM thread");
duke@1 800 assert(thread->thread_state() == _thread_in_Java, "should come from Java code");
duke@1 801 assert(SafepointSynchronize::is_synchronizing(), "polling encountered outside safepoint synchronization");
duke@1 802
duke@1 803 if (ShowSafepointMsgs) {
duke@1 804 tty->print("handle_polling_page_exception: ");
duke@1 805 }
duke@1 806
duke@1 807 if (PrintSafepointStatistics) {
duke@1 808 inc_page_trap_count();
duke@1 809 }
duke@1 810
duke@1 811 ThreadSafepointState* state = thread->safepoint_state();
duke@1 812
duke@1 813 state->handle_polling_page_exception();
duke@1 814 }
duke@1 815
duke@1 816
duke@1 817 void SafepointSynchronize::print_safepoint_timeout(SafepointTimeoutReason reason) {
duke@1 818 if (!timeout_error_printed) {
duke@1 819 timeout_error_printed = true;
jwilhelm@22551 820 // Print out the thread info which didn't reach the safepoint for debugging
duke@1 821 // purposes (useful when there are lots of threads in the debugger).
drchase@24424 822 tty->cr();
duke@1 823 tty->print_cr("# SafepointSynchronize::begin: Timeout detected:");
duke@1 824 if (reason == _spinning_timeout) {
duke@1 825 tty->print_cr("# SafepointSynchronize::begin: Timed out while spinning to reach a safepoint.");
duke@1 826 } else if (reason == _blocking_timeout) {
duke@1 827 tty->print_cr("# SafepointSynchronize::begin: Timed out while waiting for threads to stop.");
duke@1 828 }
duke@1 829
duke@1 830 tty->print_cr("# SafepointSynchronize::begin: Threads which did not reach the safepoint:");
duke@1 831 ThreadSafepointState *cur_state;
duke@1 832 ResourceMark rm;
duke@1 833 for(JavaThread *cur_thread = Threads::first(); cur_thread;
duke@1 834 cur_thread = cur_thread->next()) {
duke@1 835 cur_state = cur_thread->safepoint_state();
duke@1 836
duke@1 837 if (cur_thread->thread_state() != _thread_blocked &&
duke@1 838 ((reason == _spinning_timeout && cur_state->is_running()) ||
duke@1 839 (reason == _blocking_timeout && !cur_state->has_called_back()))) {
duke@1 840 tty->print("# ");
duke@1 841 cur_thread->print();
drchase@24424 842 tty->cr();
duke@1 843 }
duke@1 844 }
duke@1 845 tty->print_cr("# SafepointSynchronize::begin: (End of list)");
duke@1 846 }
duke@1 847
duke@1 848 // To debug the long safepoint, specify both DieOnSafepointTimeout &
duke@1 849 // ShowMessageBoxOnError.
duke@1 850 if (DieOnSafepointTimeout) {
david@33105 851 fatal("Safepoint sync time longer than " INTX_FORMAT "ms detected when executing %s.",
rehn@46496 852 SafepointTimeoutDelay, VMThread::vm_safepoint_description());
duke@1 853 }
duke@1 854 }
duke@1 855
duke@1 856
duke@1 857 // -------------------------------------------------------------------------------------------------------
duke@1 858 // Implementation of ThreadSafepointState
duke@1 859
duke@1 860 ThreadSafepointState::ThreadSafepointState(JavaThread *thread) {
duke@1 861 _thread = thread;
duke@1 862 _type = _running;
duke@1 863 _has_called_back = false;
duke@1 864 _at_poll_safepoint = false;
duke@1 865 }
duke@1 866
duke@1 867 void ThreadSafepointState::create(JavaThread *thread) {
duke@1 868 ThreadSafepointState *state = new ThreadSafepointState(thread);
duke@1 869 thread->set_safepoint_state(state);
duke@1 870 }
duke@1 871
duke@1 872 void ThreadSafepointState::destroy(JavaThread *thread) {
duke@1 873 if (thread->safepoint_state()) {
duke@1 874 delete(thread->safepoint_state());
duke@1 875 thread->set_safepoint_state(NULL);
duke@1 876 }
duke@1 877 }
duke@1 878
duke@1 879 void ThreadSafepointState::examine_state_of_thread() {
duke@1 880 assert(is_running(), "better be running or just have hit safepoint poll");
duke@1 881
duke@1 882 JavaThreadState state = _thread->thread_state();
duke@1 883
never@6269 884 // Save the state at the start of safepoint processing.
never@6269 885 _orig_thread_state = state;
never@6269 886
duke@1 887 // Check for a thread that is suspended. Note that thread resume tries
duke@1 888 // to grab the Threads_lock which we own here, so a thread cannot be
duke@1 889 // resumed during safepoint synchronization.
duke@1 890
dcubed@3826 891 // We check to see if this thread is suspended without locking to
dcubed@3826 892 // avoid deadlocking with a third thread that is waiting for this
dcubed@3826 893 // thread to be suspended. The third thread can notice the safepoint
dcubed@3826 894 // that we're trying to start at the beginning of its SR_lock->wait()
dcubed@3826 895 // call. If that happens, then the third thread will block on the
dcubed@3826 896 // safepoint while still holding the underlying SR_lock. We won't be
dcubed@3826 897 // able to get the SR_lock and we'll deadlock.
dcubed@3826 898 //
dcubed@3826 899 // We don't need to grab the SR_lock here for two reasons:
dcubed@3826 900 // 1) The suspend flags are both volatile and are set with an
dcubed@3826 901 // Atomic::cmpxchg() call so we should see the suspended
dcubed@3826 902 // state right away.
dcubed@3826 903 // 2) We're being called from the safepoint polling loop; if
dcubed@3826 904 // we don't see the suspended state on this iteration, then
dcubed@3826 905 // we'll come around again.
dcubed@3826 906 //
dcubed@3826 907 bool is_suspended = _thread->is_ext_suspended();
duke@1 908 if (is_suspended) {
duke@1 909 roll_forward(_at_safepoint);
duke@1 910 return;
duke@1 911 }
duke@1 912
duke@1 913 // Some JavaThread states have an initial safepoint state of
duke@1 914 // running, but are actually at a safepoint. We will happily
duke@1 915 // agree and update the safepoint state here.
duke@1 916 if (SafepointSynchronize::safepoint_safe(_thread, state)) {
never@12108 917 SafepointSynchronize::check_for_lazy_critical_native(_thread, state);
never@11631 918 roll_forward(_at_safepoint);
never@11631 919 return;
duke@1 920 }
duke@1 921
duke@1 922 if (state == _thread_in_vm) {
duke@1 923 roll_forward(_call_back);
duke@1 924 return;
duke@1 925 }
duke@1 926
duke@1 927 // All other thread states will continue to run until they
duke@1 928 // transition and self-block in state _blocked
duke@1 929 // Safepoint polling in compiled code causes the Java threads to do the same.
duke@1 930 // Note: new threads may require a malloc so they must be allowed to finish
duke@1 931
duke@1 932 assert(is_running(), "examine_state_of_thread on non-running thread");
duke@1 933 return;
duke@1 934 }
duke@1 935
duke@1 936 // Returns true is thread could not be rolled forward at present position.
duke@1 937 void ThreadSafepointState::roll_forward(suspend_type type) {
duke@1 938 _type = type;
duke@1 939
duke@1 940 switch(_type) {
duke@1 941 case _at_safepoint:
duke@1 942 SafepointSynchronize::signal_thread_at_safepoint();
never@12108 943 DEBUG_ONLY(_thread->set_visited_for_critical_count(true));
never@12108 944 if (_thread->in_critical()) {
never@12108 945 // Notice that this thread is in a critical section
never@12108 946 SafepointSynchronize::increment_jni_active_count();
never@12108 947 }
duke@1 948 break;
duke@1 949
duke@1 950 case _call_back:
duke@1 951 set_has_called_back(false);
duke@1 952 break;
duke@1 953
duke@1 954 case _running:
duke@1 955 default:
duke@1 956 ShouldNotReachHere();
duke@1 957 }
duke@1 958 }
duke@1 959
duke@1 960 void ThreadSafepointState::restart() {
duke@1 961 switch(type()) {
duke@1 962 case _at_safepoint:
duke@1 963 case _call_back:
duke@1 964 break;
duke@1 965
duke@1 966 case _running:
duke@1 967 default:
bpittore@31592 968 tty->print_cr("restart thread " INTPTR_FORMAT " with state %d",
david@33148 969 p2i(_thread), _type);
duke@1 970 _thread->print();
duke@1 971 ShouldNotReachHere();
duke@1 972 }
duke@1 973 _type = _running;
duke@1 974 set_has_called_back(false);
duke@1 975 }
duke@1 976
duke@1 977
duke@1 978 void ThreadSafepointState::print_on(outputStream *st) const {
goetz@33589 979 const char *s = NULL;
duke@1 980
duke@1 981 switch(_type) {
duke@1 982 case _running : s = "_running"; break;
duke@1 983 case _at_safepoint : s = "_at_safepoint"; break;
duke@1 984 case _call_back : s = "_call_back"; break;
duke@1 985 default:
duke@1 986 ShouldNotReachHere();
duke@1 987 }
duke@1 988
duke@1 989 st->print_cr("Thread: " INTPTR_FORMAT
duke@1 990 " [0x%2x] State: %s _has_called_back %d _at_poll_safepoint %d",
david@33148 991 p2i(_thread), _thread->osthread()->thread_id(), s, _has_called_back,
duke@1 992 _at_poll_safepoint);
duke@1 993
duke@1 994 _thread->print_thread_state_on(st);
duke@1 995 }
duke@1 996
duke@1 997 // ---------------------------------------------------------------------------------------------------------------------
duke@1 998
duke@1 999 // Block the thread at the safepoint poll or poll return.
duke@1 1000 void ThreadSafepointState::handle_polling_page_exception() {
duke@1 1001
duke@1 1002 // Check state. block() will set thread state to thread_in_vm which will
duke@1 1003 // cause the safepoint state _type to become _call_back.
duke@1 1004 assert(type() == ThreadSafepointState::_running,
duke@1 1005 "polling page exception on thread not running state");
duke@1 1006
duke@1 1007 // Step 1: Find the nmethod from the return address
duke@1 1008 if (ShowSafepointMsgs && Verbose) {
david@33148 1009 tty->print_cr("Polling page exception at " INTPTR_FORMAT, p2i(thread()->saved_exception_pc()));
duke@1 1010 }
duke@1 1011 address real_return_addr = thread()->saved_exception_pc();
duke@1 1012
duke@1 1013 CodeBlob *cb = CodeCache::find_blob(real_return_addr);
rbackman@38133 1014 assert(cb != NULL && cb->is_compiled(), "return address should be in nmethod");
rbackman@38133 1015 CompiledMethod* nm = (CompiledMethod*)cb;
duke@1 1016
duke@1 1017 // Find frame of caller
duke@1 1018 frame stub_fr = thread()->last_frame();
duke@1 1019 CodeBlob* stub_cb = stub_fr.cb();
duke@1 1020 assert(stub_cb->is_safepoint_stub(), "must be a safepoint stub");
duke@1 1021 RegisterMap map(thread(), true);
duke@1 1022 frame caller_fr = stub_fr.sender(&map);
duke@1 1023
duke@1 1024 // Should only be poll_return or poll
duke@1 1025 assert( nm->is_at_poll_or_poll_return(real_return_addr), "should not be at call" );
duke@1 1026
duke@1 1027 // This is a poll immediately before a return. The exception handling code
duke@1 1028 // has already had the effect of causing the return to occur, so the execution
duke@1 1029 // will continue immediately after the call. In addition, the oopmap at the
duke@1 1030 // return point does not mark the return value as an oop (if it is), so
duke@1 1031 // it needs a handle here to be updated.
duke@1 1032 if( nm->is_at_poll_return(real_return_addr) ) {
duke@1 1033 // See if return type is an oop.
duke@1 1034 bool return_oop = nm->method()->is_returning_oop();
duke@1 1035 Handle return_value;
duke@1 1036 if (return_oop) {
duke@1 1037 // The oop result has been saved on the stack together with all
duke@1 1038 // the other registers. In order to preserve it over GCs we need
duke@1 1039 // to keep it in a handle.
duke@1 1040 oop result = caller_fr.saved_oop_result(&map);
duke@1 1041 assert(result == NULL || result->is_oop(), "must be oop");
duke@1 1042 return_value = Handle(thread(), result);
duke@1 1043 assert(Universe::heap()->is_in_or_null(result), "must be heap pointer");
duke@1 1044 }
duke@1 1045
duke@1 1046 // Block the thread
duke@1 1047 SafepointSynchronize::block(thread());
duke@1 1048
duke@1 1049 // restore oop result, if any
duke@1 1050 if (return_oop) {
duke@1 1051 caller_fr.set_saved_oop_result(&map, return_value());
duke@1 1052 }
duke@1 1053 }
duke@1 1054
duke@1 1055 // This is a safepoint poll. Verify the return address and block.
duke@1 1056 else {
duke@1 1057 set_at_poll_safepoint(true);
duke@1 1058
duke@1 1059 // verify the blob built the "return address" correctly
duke@1 1060 assert(real_return_addr == caller_fr.pc(), "must match");
duke@1 1061
duke@1 1062 // Block the thread
duke@1 1063 SafepointSynchronize::block(thread());
duke@1 1064 set_at_poll_safepoint(false);
duke@1 1065
duke@1 1066 // If we have a pending async exception deoptimize the frame
duke@1 1067 // as otherwise we may never deliver it.
duke@1 1068 if (thread()->has_async_condition()) {
duke@1 1069 ThreadInVMfromJavaNoAsyncException __tiv(thread());
never@7106 1070 Deoptimization::deoptimize_frame(thread(), caller_fr.id());
duke@1 1071 }
duke@1 1072
duke@1 1073 // If an exception has been installed we must check for a pending deoptimization
duke@1 1074 // Deoptimize frame if exception has been thrown.
duke@1 1075
duke@1 1076 if (thread()->has_pending_exception() ) {
duke@1 1077 RegisterMap map(thread(), true);
duke@1 1078 frame caller_fr = stub_fr.sender(&map);
duke@1 1079 if (caller_fr.is_deoptimized_frame()) {
duke@1 1080 // The exception patch will destroy registers that are still
duke@1 1081 // live and will be needed during deoptimization. Defer the
jwilhelm@22551 1082 // Async exception should have deferred the exception until the
duke@1 1083 // next safepoint which will be detected when we get into
duke@1 1084 // the interpreter so if we have an exception now things
duke@1 1085 // are messed up.
duke@1 1086
duke@1 1087 fatal("Exception installed and deoptimization is pending");
duke@1 1088 }
duke@1 1089 }
duke@1 1090 }
duke@1 1091 }
duke@1 1092
duke@1 1093
duke@1 1094 //
duke@1 1095 // Statistics & Instrumentations
duke@1 1096 //
duke@1 1097 SafepointSynchronize::SafepointStats* SafepointSynchronize::_safepoint_stats = NULL;
xlu@5042 1098 jlong SafepointSynchronize::_safepoint_begin_time = 0;
duke@1 1099 int SafepointSynchronize::_cur_stat_index = 0;
duke@1 1100 julong SafepointSynchronize::_safepoint_reasons[VM_Operation::VMOp_Terminating];
duke@1 1101 julong SafepointSynchronize::_coalesced_vmop_count = 0;
duke@1 1102 jlong SafepointSynchronize::_max_sync_time = 0;
xlu@5042 1103 jlong SafepointSynchronize::_max_vmop_time = 0;
xlu@5042 1104 float SafepointSynchronize::_ts_of_current_safepoint = 0.0f;
duke@1 1105
xlu@5042 1106 static jlong cleanup_end_time = 0;
duke@1 1107 static bool need_to_track_page_armed_status = false;
duke@1 1108 static bool init_done = false;
duke@1 1109
xlu@5042 1110 // Helper method to print the header.
xlu@5042 1111 static void print_header() {
shade@46473 1112 // The number of spaces is significant here, and should match the format
shade@46473 1113 // specifiers in print_statistics().
shade@46473 1114
shade@46473 1115 tty->print(" vmop "
shade@46473 1116 "[ threads: total initially_running wait_to_block ]"
shade@46473 1117 "[ time: spin block sync cleanup vmop ] ");
xlu@5042 1118
xlu@5042 1119 // no page armed status printed out if it is always armed.
xlu@5042 1120 if (need_to_track_page_armed_status) {
xlu@5042 1121 tty->print("page_armed ");
xlu@5042 1122 }
xlu@5042 1123
xlu@5042 1124 tty->print_cr("page_trap_count");
xlu@5042 1125 }
xlu@5042 1126
duke@1 1127 void SafepointSynchronize::deferred_initialize_stat() {
duke@1 1128 if (init_done) return;
duke@1 1129
duke@1 1130 // If PrintSafepointStatisticsTimeout is specified, the statistics data will
duke@1 1131 // be printed right away, in which case, _safepoint_stats will regress to
duke@1 1132 // a single element array. Otherwise, it is a circular ring buffer with default
duke@1 1133 // size of PrintSafepointStatisticsCount.
duke@1 1134 int stats_array_size;
duke@1 1135 if (PrintSafepointStatisticsTimeout > 0) {
duke@1 1136 stats_array_size = 1;
duke@1 1137 PrintSafepointStatistics = true;
duke@1 1138 } else {
duke@1 1139 stats_array_size = PrintSafepointStatisticsCount;
duke@1 1140 }
duke@1 1141 _safepoint_stats = (SafepointStats*)os::malloc(stats_array_size
zgu@13195 1142 * sizeof(SafepointStats), mtInternal);
duke@1 1143 guarantee(_safepoint_stats != NULL,
duke@1 1144 "not enough memory for safepoint instrumentation data");
duke@1 1145
shade@27662 1146 if (DeferPollingPageLoopCount >= 0) {
duke@1 1147 need_to_track_page_armed_status = true;
duke@1 1148 }
duke@1 1149 init_done = true;
duke@1 1150 }
duke@1 1151
duke@1 1152 void SafepointSynchronize::begin_statistics(int nof_threads, int nof_running) {
xlu@4006 1153 assert(init_done, "safepoint statistics array hasn't been initialized");
duke@1 1154 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
duke@1 1155
xlu@5042 1156 spstat->_time_stamp = _ts_of_current_safepoint;
xlu@5042 1157
duke@1 1158 VM_Operation *op = VMThread::vm_operation();
duke@1 1159 spstat->_vmop_type = (op != NULL ? op->type() : -1);
duke@1 1160 if (op != NULL) {
duke@1 1161 _safepoint_reasons[spstat->_vmop_type]++;
duke@1 1162 }
duke@1 1163
duke@1 1164 spstat->_nof_total_threads = nof_threads;
duke@1 1165 spstat->_nof_initial_running_threads = nof_running;
duke@1 1166 spstat->_nof_threads_hit_page_trap = 0;
duke@1 1167
duke@1 1168 // Records the start time of spinning. The real time spent on spinning
duke@1 1169 // will be adjusted when spin is done. Same trick is applied for time
duke@1 1170 // spent on waiting for threads to block.
duke@1 1171 if (nof_running != 0) {
duke@1 1172 spstat->_time_to_spin = os::javaTimeNanos();
duke@1 1173 } else {
duke@1 1174 spstat->_time_to_spin = 0;
duke@1 1175 }
duke@1 1176 }
duke@1 1177
duke@1 1178 void SafepointSynchronize::update_statistics_on_spin_end() {
duke@1 1179 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
duke@1 1180
duke@1 1181 jlong cur_time = os::javaTimeNanos();
duke@1 1182
duke@1 1183 spstat->_nof_threads_wait_to_block = _waiting_to_block;
duke@1 1184 if (spstat->_nof_initial_running_threads != 0) {
duke@1 1185 spstat->_time_to_spin = cur_time - spstat->_time_to_spin;
duke@1 1186 }
duke@1 1187
duke@1 1188 if (need_to_track_page_armed_status) {
duke@1 1189 spstat->_page_armed = (PageArmed == 1);
duke@1 1190 }
duke@1 1191
duke@1 1192 // Records the start time of waiting for to block. Updated when block is done.
duke@1 1193 if (_waiting_to_block != 0) {
duke@1 1194 spstat->_time_to_wait_to_block = cur_time;
duke@1 1195 } else {
duke@1 1196 spstat->_time_to_wait_to_block = 0;
duke@1 1197 }
duke@1 1198 }
duke@1 1199
duke@1 1200 void SafepointSynchronize::update_statistics_on_sync_end(jlong end_time) {
duke@1 1201 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
duke@1 1202
duke@1 1203 if (spstat->_nof_threads_wait_to_block != 0) {
duke@1 1204 spstat->_time_to_wait_to_block = end_time -
duke@1 1205 spstat->_time_to_wait_to_block;
duke@1 1206 }
duke@1 1207
duke@1 1208 // Records the end time of sync which will be used to calculate the total
duke@1 1209 // vm operation time. Again, the real time spending in syncing will be deducted
duke@1 1210 // from the start of the sync time later when end_statistics is called.
xlu@5042 1211 spstat->_time_to_sync = end_time - _safepoint_begin_time;
duke@1 1212 if (spstat->_time_to_sync > _max_sync_time) {
duke@1 1213 _max_sync_time = spstat->_time_to_sync;
duke@1 1214 }
xlu@5042 1215
xlu@5042 1216 spstat->_time_to_do_cleanups = end_time;
xlu@5042 1217 }
xlu@5042 1218
xlu@5042 1219 void SafepointSynchronize::update_statistics_on_cleanup_end(jlong end_time) {
xlu@5042 1220 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
xlu@5042 1221
xlu@5042 1222 // Record how long spent in cleanup tasks.
xlu@5042 1223 spstat->_time_to_do_cleanups = end_time - spstat->_time_to_do_cleanups;
xlu@5042 1224
xlu@5042 1225 cleanup_end_time = end_time;
duke@1 1226 }
duke@1 1227
duke@1 1228 void SafepointSynchronize::end_statistics(jlong vmop_end_time) {
duke@1 1229 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
duke@1 1230
duke@1 1231 // Update the vm operation time.
xlu@5042 1232 spstat->_time_to_exec_vmop = vmop_end_time - cleanup_end_time;
xlu@5042 1233 if (spstat->_time_to_exec_vmop > _max_vmop_time) {
xlu@5042 1234 _max_vmop_time = spstat->_time_to_exec_vmop;
xlu@5042 1235 }
duke@1 1236 // Only the sync time longer than the specified
duke@1 1237 // PrintSafepointStatisticsTimeout will be printed out right away.
duke@1 1238 // By default, it is -1 meaning all samples will be put into the list.
duke@1 1239 if ( PrintSafepointStatisticsTimeout > 0) {
gziemski@33222 1240 if (spstat->_time_to_sync > (jlong)PrintSafepointStatisticsTimeout * MICROUNITS) {
duke@1 1241 print_statistics();
duke@1 1242 }
duke@1 1243 } else {
duke@1 1244 // The safepoint statistics will be printed out when the _safepoin_stats
duke@1 1245 // array fills up.
xlu@5042 1246 if (_cur_stat_index == PrintSafepointStatisticsCount - 1) {
duke@1 1247 print_statistics();
duke@1 1248 _cur_stat_index = 0;
xlu@5042 1249 } else {
xlu@5042 1250 _cur_stat_index++;
duke@1 1251 }
duke@1 1252 }
duke@1 1253 }
duke@1 1254
duke@1 1255 void SafepointSynchronize::print_statistics() {
xlu@5042 1256 for (int index = 0; index <= _cur_stat_index; index++) {
xlu@5042 1257 if (index % 30 == 0) {
xlu@5042 1258 print_header();
xlu@5042 1259 }
shade@46473 1260 SafepointStats* sstats = &_safepoint_stats[index];
shade@46473 1261 tty->print("%8.3f: ", sstats->_time_stamp);
shade@46473 1262 tty->print("%-30s [ "
shade@46473 1263 INT32_FORMAT_W(8) " " INT32_FORMAT_W(17) " " INT32_FORMAT_W(13) " "
shade@46473 1264 "]",
shade@46473 1265 (sstats->_vmop_type == -1 ? "no vm operation" : VM_Operation::name(sstats->_vmop_type)),
duke@1 1266 sstats->_nof_total_threads,
duke@1 1267 sstats->_nof_initial_running_threads,
duke@1 1268 sstats->_nof_threads_wait_to_block);
duke@1 1269 // "/ MICROUNITS " is to convert the unit from nanos to millis.
shade@46473 1270 tty->print("[ "
shade@46473 1271 INT64_FORMAT_W(7) " " INT64_FORMAT_W(7) " "
shade@46473 1272 INT64_FORMAT_W(7) " " INT64_FORMAT_W(7) " "
shade@46473 1273 INT64_FORMAT_W(7) " ] ",
jwilhelm@46630 1274 (int64_t)(sstats->_time_to_spin / MICROUNITS),
jwilhelm@46630 1275 (int64_t)(sstats->_time_to_wait_to_block / MICROUNITS),
jwilhelm@46630 1276 (int64_t)(sstats->_time_to_sync / MICROUNITS),
jwilhelm@46630 1277 (int64_t)(sstats->_time_to_do_cleanups / MICROUNITS),
jwilhelm@46630 1278 (int64_t)(sstats->_time_to_exec_vmop / MICROUNITS));
duke@1 1279
duke@1 1280 if (need_to_track_page_armed_status) {
shade@46473 1281 tty->print(INT32_FORMAT_W(10) " ", sstats->_page_armed);
duke@1 1282 }
shade@46473 1283 tty->print_cr(INT32_FORMAT_W(15) " ", sstats->_nof_threads_hit_page_trap);
duke@1 1284 }
duke@1 1285 }
duke@1 1286
duke@1 1287 // This method will be called when VM exits. It will first call
duke@1 1288 // print_statistics to print out the rest of the sampling. Then
duke@1 1289 // it tries to summarize the sampling.
duke@1 1290 void SafepointSynchronize::print_stat_on_exit() {
duke@1 1291 if (_safepoint_stats == NULL) return;
duke@1 1292
duke@1 1293 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
duke@1 1294
duke@1 1295 // During VM exit, end_statistics may not get called and in that
duke@1 1296 // case, if the sync time is less than PrintSafepointStatisticsTimeout,
duke@1 1297 // don't print it out.
duke@1 1298 // Approximate the vm op time.
duke@1 1299 _safepoint_stats[_cur_stat_index]._time_to_exec_vmop =
xlu@5042 1300 os::javaTimeNanos() - cleanup_end_time;
duke@1 1301
duke@1 1302 if ( PrintSafepointStatisticsTimeout < 0 ||
gziemski@33222 1303 spstat->_time_to_sync > (jlong)PrintSafepointStatisticsTimeout * MICROUNITS) {
duke@1 1304 print_statistics();
duke@1 1305 }
drchase@24424 1306 tty->cr();
duke@1 1307
duke@1 1308 // Print out polling page sampling status.
duke@1 1309 if (!need_to_track_page_armed_status) {
shade@27662 1310 tty->print_cr("Polling page always armed");
duke@1 1311 } else {
david@33148 1312 tty->print_cr("Defer polling page loop count = " INTX_FORMAT "\n",
david@33148 1313 DeferPollingPageLoopCount);
duke@1 1314 }
duke@1 1315
duke@1 1316 for (int index = 0; index < VM_Operation::VMOp_Terminating; index++) {
duke@1 1317 if (_safepoint_reasons[index] != 0) {
bpittore@31592 1318 tty->print_cr("%-26s" UINT64_FORMAT_W(10), VM_Operation::name(index),
duke@1 1319 _safepoint_reasons[index]);
duke@1 1320 }
duke@1 1321 }
duke@1 1322
bpittore@31592 1323 tty->print_cr(UINT64_FORMAT_W(5) " VM operations coalesced during safepoint",
duke@1 1324 _coalesced_vmop_count);
bpittore@31592 1325 tty->print_cr("Maximum sync time " INT64_FORMAT_W(5) " ms",
jwilhelm@46630 1326 (int64_t)(_max_sync_time / MICROUNITS));
xlu@5042 1327 tty->print_cr("Maximum vm operation time (except for Exit VM operation) "
bpittore@31592 1328 INT64_FORMAT_W(5) " ms",
jwilhelm@46630 1329 (int64_t)(_max_vmop_time / MICROUNITS));
duke@1 1330 }
duke@1 1331
duke@1 1332 // ------------------------------------------------------------------------------------------------
duke@1 1333 // Non-product code
duke@1 1334
duke@1 1335 #ifndef PRODUCT
duke@1 1336
duke@1 1337 void SafepointSynchronize::print_state() {
duke@1 1338 if (_state == _not_synchronized) {
duke@1 1339 tty->print_cr("not synchronized");
duke@1 1340 } else if (_state == _synchronizing || _state == _synchronized) {
duke@1 1341 tty->print_cr("State: %s", (_state == _synchronizing) ? "synchronizing" :
duke@1 1342 "synchronized");
duke@1 1343
duke@1 1344 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) {
duke@1 1345 cur->safepoint_state()->print();
duke@1 1346 }
duke@1 1347 }
duke@1 1348 }
duke@1 1349
duke@1 1350 void SafepointSynchronize::safepoint_msg(const char* format, ...) {
duke@1 1351 if (ShowSafepointMsgs) {
duke@1 1352 va_list ap;
duke@1 1353 va_start(ap, format);
duke@1 1354 tty->vprint_cr(format, ap);
duke@1 1355 va_end(ap);
duke@1 1356 }
duke@1 1357 }
duke@1 1358
duke@1 1359 #endif // !PRODUCT