annotate src/hotspot/share/runtime/safepoint.cpp @ 47792:87141990dde5

8185580: Refactor Threads::possibly_parallel_oops_do() to use Threads::parallel_java_threads_do() Reviewed-by: dholmes, coleenp
author rkennke
date Tue, 17 Oct 2017 18:54:03 +0200
parents 52d46d7e3454
children 69c081ca110a
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"
rkennke@46702 36 #include "gc/shared/strongRootsScope.hpp"
rkennke@46702 37 #include "gc/shared/workgroup.hpp"
stefank@7397 38 #include "interpreter/interpreter.hpp"
rprotacio@33763 39 #include "logging/log.hpp"
stuefe@46701 40 #include "logging/logStream.hpp"
stefank@7397 41 #include "memory/resourceArea.hpp"
stefank@7397 42 #include "memory/universe.inline.hpp"
stefank@7397 43 #include "oops/oop.inline.hpp"
coleenp@8076 44 #include "oops/symbol.hpp"
dholmes@40655 45 #include "runtime/atomic.hpp"
stefank@7397 46 #include "runtime/compilationPolicy.hpp"
stefank@7397 47 #include "runtime/deoptimization.hpp"
stefank@7397 48 #include "runtime/frame.inline.hpp"
stefank@7397 49 #include "runtime/interfaceSupport.hpp"
stefank@7397 50 #include "runtime/mutexLocker.hpp"
goetz@24351 51 #include "runtime/orderAccess.inline.hpp"
stefank@7397 52 #include "runtime/osThread.hpp"
stefank@7397 53 #include "runtime/safepoint.hpp"
stefank@7397 54 #include "runtime/signature.hpp"
stefank@7397 55 #include "runtime/stubCodeGenerator.hpp"
stefank@7397 56 #include "runtime/stubRoutines.hpp"
stefank@7397 57 #include "runtime/sweeper.hpp"
stefank@7397 58 #include "runtime/synchronizer.hpp"
stefank@14583 59 #include "runtime/thread.inline.hpp"
rehn@37161 60 #include "runtime/timerTrace.hpp"
stefank@7397 61 #include "services/runtimeService.hpp"
dsimms@37176 62 #include "trace/tracing.hpp"
dsimms@37176 63 #include "trace/traceMacros.hpp"
stefank@7397 64 #include "utilities/events.hpp"
jprovino@15482 65 #include "utilities/macros.hpp"
stefank@7397 66 #ifdef COMPILER1
stefank@7397 67 #include "c1/c1_globals.hpp"
stefank@7397 68 #endif
duke@1 69
duke@1 70 // --------------------------------------------------------------------------------------------------
duke@1 71 // Implementation of Safepoint begin/end
duke@1 72
duke@1 73 SafepointSynchronize::SynchronizeState volatile SafepointSynchronize::_state = SafepointSynchronize::_not_synchronized;
duke@1 74 volatile int SafepointSynchronize::_waiting_to_block = 0;
duke@1 75 volatile int SafepointSynchronize::_safepoint_counter = 0;
never@11631 76 int SafepointSynchronize::_current_jni_active_count = 0;
xlu@5042 77 long SafepointSynchronize::_end_of_last_safepoint = 0;
duke@1 78 static volatile int PageArmed = 0 ; // safepoint polling page is RO|RW vs PROT_NONE
duke@1 79 static volatile int TryingToBlock = 0 ; // proximate value -- for advisory use only
duke@1 80 static bool timeout_error_printed = false;
duke@1 81
duke@1 82 // Roll all threads forward to a safepoint and suspend them all
duke@1 83 void SafepointSynchronize::begin() {
dsimms@37176 84 EventSafepointBegin begin_event;
duke@1 85 Thread* myThread = Thread::current();
duke@1 86 assert(myThread->is_VM_thread(), "Only VM thread may execute a safepoint");
duke@1 87
xlu@5042 88 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) {
xlu@5042 89 _safepoint_begin_time = os::javaTimeNanos();
xlu@5042 90 _ts_of_current_safepoint = tty->time_stamp().seconds();
xlu@5042 91 }
duke@1 92
eosterlund@47791 93 Universe::heap()->safepoint_synchronize_begin();
duke@1 94
duke@1 95 // By getting the Threads_lock, we assure that no threads are about to start or
duke@1 96 // exit. It is released again in SafepointSynchronize::end().
duke@1 97 Threads_lock->lock();
duke@1 98
duke@1 99 assert( _state == _not_synchronized, "trying to safepoint synchronize with wrong state");
duke@1 100
duke@1 101 int nof_threads = Threads::number_of_threads();
duke@1 102
rprotacio@33763 103 log_debug(safepoint)("Safepoint synchronization initiated. (%d)", nof_threads);
duke@1 104
duke@1 105 RuntimeService::record_safepoint_begin();
duke@1 106
duke@1 107 MutexLocker mu(Safepoint_lock);
duke@1 108
never@11631 109 // Reset the count of active JNI critical threads
never@11631 110 _current_jni_active_count = 0;
never@11631 111
duke@1 112 // Set number of threads to wait for, before we initiate the callbacks
duke@1 113 _waiting_to_block = nof_threads;
duke@1 114 TryingToBlock = 0 ;
duke@1 115 int still_running = nof_threads;
duke@1 116
duke@1 117 // Save the starting time, so that it can be compared to see if this has taken
duke@1 118 // too long to complete.
goetz@33589 119 jlong safepoint_limit_time = 0;
duke@1 120 timeout_error_printed = false;
duke@1 121
xlu@4006 122 // PrintSafepointStatisticsTimeout can be specified separately. When
xlu@4006 123 // specified, PrintSafepointStatistics will be set to true in
xlu@4006 124 // deferred_initialize_stat method. The initialization has to be done
xlu@4006 125 // early enough to avoid any races. See bug 6880029 for details.
xlu@4006 126 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) {
xlu@4006 127 deferred_initialize_stat();
xlu@4006 128 }
xlu@4006 129
duke@1 130 // Begin the process of bringing the system to a safepoint.
duke@1 131 // Java threads can be in several different states and are
duke@1 132 // stopped by different mechanisms:
duke@1 133 //
duke@1 134 // 1. Running interpreted
jwilhelm@22551 135 // The interpreter dispatch table is changed to force it to
duke@1 136 // check for a safepoint condition between bytecodes.
duke@1 137 // 2. Running in native code
duke@1 138 // When returning from the native code, a Java thread must check
duke@1 139 // the safepoint _state to see if we must block. If the
duke@1 140 // VM thread sees a Java thread in native, it does
duke@1 141 // not wait for this thread to block. The order of the memory
duke@1 142 // writes and reads of both the safepoint state and the Java
duke@1 143 // threads state is critical. In order to guarantee that the
duke@1 144 // memory writes are serialized with respect to each other,
duke@1 145 // the VM thread issues a memory barrier instruction
duke@1 146 // (on MP systems). In order to avoid the overhead of issuing
duke@1 147 // a memory barrier for each Java thread making native calls, each Java
duke@1 148 // thread performs a write to a single memory page after changing
duke@1 149 // the thread state. The VM thread performs a sequence of
duke@1 150 // mprotect OS calls which forces all previous writes from all
duke@1 151 // Java threads to be serialized. This is done in the
duke@1 152 // os::serialize_thread_states() call. This has proven to be
duke@1 153 // much more efficient than executing a membar instruction
duke@1 154 // on every call to native code.
duke@1 155 // 3. Running compiled Code
duke@1 156 // Compiled code reads a global (Safepoint Polling) page that
duke@1 157 // is set to fault if we are trying to get to a safepoint.
duke@1 158 // 4. Blocked
duke@1 159 // A thread which is blocked will not be allowed to return from the
duke@1 160 // block condition until the safepoint operation is complete.
duke@1 161 // 5. In VM or Transitioning between states
duke@1 162 // If a Java thread is currently running in the VM or transitioning
duke@1 163 // between states, the safepointing code will wait for the thread to
duke@1 164 // block itself when it attempts transitions to a new state.
duke@1 165 //
dsimms@37176 166 {
egahlin@40664 167 EventSafepointStateSynchronization sync_event;
dsimms@37176 168 int initial_running = 0;
duke@1 169
dsimms@37176 170 _state = _synchronizing;
dsimms@37176 171 OrderAccess::fence();
duke@1 172
dsimms@37176 173 // Flush all thread states to memory
dsimms@37176 174 if (!UseMembar) {
dsimms@37176 175 os::serialize_thread_states();
dsimms@37176 176 }
duke@1 177
dsimms@37176 178 // Make interpreter safepoint aware
dsimms@37176 179 Interpreter::notice_safepoints();
duke@1 180
dsimms@37176 181 if (DeferPollingPageLoopCount < 0) {
dsimms@37176 182 // Make polling safepoint aware
dsimms@37176 183 guarantee (PageArmed == 0, "invariant") ;
dsimms@37176 184 PageArmed = 1 ;
dsimms@37176 185 os::make_polling_page_unreadable();
dsimms@37176 186 }
dsimms@37176 187
dsimms@37176 188 // Consider using active_processor_count() ... but that call is expensive.
dsimms@37176 189 int ncpus = os::processor_count() ;
duke@1 190
duke@1 191 #ifdef ASSERT
dsimms@37176 192 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) {
dsimms@37176 193 assert(cur->safepoint_state()->is_running(), "Illegal initial state");
dsimms@37176 194 // Clear the visited flag to ensure that the critical counts are collected properly.
dsimms@37176 195 cur->set_visited_for_critical_count(false);
dsimms@37176 196 }
duke@1 197 #endif // ASSERT
duke@1 198
dsimms@37176 199 if (SafepointTimeout)
dsimms@37176 200 safepoint_limit_time = os::javaTimeNanos() + (jlong)SafepointTimeoutDelay * MICROUNITS;
duke@1 201
dsimms@37176 202 // Iterate through all threads until it have been determined how to stop them all at a safepoint
dsimms@37176 203 unsigned int iterations = 0;
dsimms@37176 204 int steps = 0 ;
dsimms@37176 205 while(still_running > 0) {
dsimms@37176 206 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) {
dsimms@37176 207 assert(!cur->is_ConcurrentGC_thread(), "A concurrent GC thread is unexpectly being suspended");
dsimms@37176 208 ThreadSafepointState *cur_state = cur->safepoint_state();
dsimms@37176 209 if (cur_state->is_running()) {
dsimms@37176 210 cur_state->examine_state_of_thread();
dsimms@37176 211 if (!cur_state->is_running()) {
dsimms@37176 212 still_running--;
dsimms@37176 213 // consider adjusting steps downward:
dsimms@37176 214 // steps = 0
dsimms@37176 215 // steps -= NNN
dsimms@37176 216 // steps >>= 1
dsimms@37176 217 // steps = MIN(steps, 2000-100)
dsimms@37176 218 // if (iterations != 0) steps -= NNN
dsimms@37176 219 }
stuefe@46701 220 LogTarget(Trace, safepoint) lt;
stuefe@46701 221 if (lt.is_enabled()) {
dsimms@37176 222 ResourceMark rm;
stuefe@46701 223 LogStream ls(lt);
stuefe@46701 224 cur_state->print_on(&ls);
dsimms@37176 225 }
duke@1 226 }
dsimms@37176 227 }
dsimms@37176 228
dsimms@37176 229 if (iterations == 0) {
dsimms@37176 230 initial_running = still_running;
dsimms@37176 231 if (PrintSafepointStatistics) {
dsimms@37176 232 begin_statistics(nof_threads, still_running);
dsimms@37176 233 }
dsimms@37176 234 }
dsimms@37176 235
dsimms@37176 236 if (still_running > 0) {
dsimms@37176 237 // Check for if it takes to long
dsimms@37176 238 if (SafepointTimeout && safepoint_limit_time < os::javaTimeNanos()) {
dsimms@37176 239 print_safepoint_timeout(_spinning_timeout);
dsimms@37176 240 }
dsimms@37176 241
dsimms@37176 242 // Spin to avoid context switching.
dsimms@37176 243 // There's a tension between allowing the mutators to run (and rendezvous)
dsimms@37176 244 // vs spinning. As the VM thread spins, wasting cycles, it consumes CPU that
dsimms@37176 245 // a mutator might otherwise use profitably to reach a safepoint. Excessive
dsimms@37176 246 // spinning by the VM thread on a saturated system can increase rendezvous latency.
dsimms@37176 247 // Blocking or yielding incur their own penalties in the form of context switching
dsimms@37176 248 // and the resultant loss of $ residency.
dsimms@37176 249 //
dsimms@37176 250 // Further complicating matters is that yield() does not work as naively expected
dsimms@37176 251 // on many platforms -- yield() does not guarantee that any other ready threads
dsimms@37176 252 // will run. As such we revert to naked_short_sleep() after some number of iterations.
dsimms@37176 253 // nakes_short_sleep() is implemented as a short unconditional sleep.
dsimms@37176 254 // Typical operating systems round a "short" sleep period up to 10 msecs, so sleeping
dsimms@37176 255 // can actually increase the time it takes the VM thread to detect that a system-wide
dsimms@37176 256 // stop-the-world safepoint has been reached. In a pathological scenario such as that
dsimms@37176 257 // described in CR6415670 the VMthread may sleep just before the mutator(s) become safe.
dsimms@37176 258 // In that case the mutators will be stalled waiting for the safepoint to complete and the
dsimms@37176 259 // the VMthread will be sleeping, waiting for the mutators to rendezvous. The VMthread
dsimms@37176 260 // will eventually wake up and detect that all mutators are safe, at which point
dsimms@37176 261 // we'll again make progress.
dsimms@37176 262 //
dsimms@37176 263 // Beware too that that the VMThread typically runs at elevated priority.
dsimms@37176 264 // Its default priority is higher than the default mutator priority.
dsimms@37176 265 // Obviously, this complicates spinning.
dsimms@37176 266 //
dsimms@37176 267 // Note too that on Windows XP SwitchThreadTo() has quite different behavior than Sleep(0).
dsimms@37176 268 // Sleep(0) will _not yield to lower priority threads, while SwitchThreadTo() will.
dsimms@37176 269 //
dsimms@37176 270 // See the comments in synchronizer.cpp for additional remarks on spinning.
dsimms@37176 271 //
dsimms@37176 272 // In the future we might:
dsimms@37176 273 // 1. Modify the safepoint scheme to avoid potentially unbounded spinning.
dsimms@37176 274 // This is tricky as the path used by a thread exiting the JVM (say on
dsimms@37176 275 // on JNI call-out) simply stores into its state field. The burden
dsimms@37176 276 // is placed on the VM thread, which must poll (spin).
dsimms@37176 277 // 2. Find something useful to do while spinning. If the safepoint is GC-related
dsimms@37176 278 // we might aggressively scan the stacks of threads that are already safe.
dsimms@37176 279 // 3. Use Solaris schedctl to examine the state of the still-running mutators.
dsimms@37176 280 // If all the mutators are ONPROC there's no reason to sleep or yield.
dsimms@37176 281 // 4. YieldTo() any still-running mutators that are ready but OFFPROC.
dsimms@37176 282 // 5. Check system saturation. If the system is not fully saturated then
dsimms@37176 283 // simply spin and avoid sleep/yield.
dsimms@37176 284 // 6. As still-running mutators rendezvous they could unpark the sleeping
dsimms@37176 285 // VMthread. This works well for still-running mutators that become
dsimms@37176 286 // safe. The VMthread must still poll for mutators that call-out.
dsimms@37176 287 // 7. Drive the policy on time-since-begin instead of iterations.
dsimms@37176 288 // 8. Consider making the spin duration a function of the # of CPUs:
dsimms@37176 289 // Spin = (((ncpus-1) * M) + K) + F(still_running)
dsimms@37176 290 // Alternately, instead of counting iterations of the outer loop
dsimms@37176 291 // we could count the # of threads visited in the inner loop, above.
dsimms@37176 292 // 9. On windows consider using the return value from SwitchThreadTo()
dsimms@37176 293 // to drive subsequent spin/SwitchThreadTo()/Sleep(N) decisions.
dsimms@37176 294
dsimms@37176 295 if (int(iterations) == DeferPollingPageLoopCount) {
dsimms@37176 296 guarantee (PageArmed == 0, "invariant") ;
dsimms@37176 297 PageArmed = 1 ;
dsimms@37176 298 os::make_polling_page_unreadable();
dsimms@37176 299 }
dsimms@37176 300
dsimms@37176 301 // Instead of (ncpus > 1) consider either (still_running < (ncpus + EPSILON)) or
dsimms@37176 302 // ((still_running + _waiting_to_block - TryingToBlock)) < ncpus)
dsimms@37176 303 ++steps ;
dsimms@37176 304 if (ncpus > 1 && steps < SafepointSpinBeforeYield) {
dsimms@37176 305 SpinPause() ; // MP-Polite spin
dsimms@37176 306 } else
dsimms@37176 307 if (steps < DeferThrSuspendLoopCount) {
dsimms@37176 308 os::naked_yield() ;
dsimms@37176 309 } else {
dsimms@37176 310 os::naked_short_sleep(1);
dsimms@37176 311 }
dsimms@37176 312
dsimms@37176 313 iterations ++ ;
dsimms@37176 314 }
dsimms@37176 315 assert(iterations < (uint)max_jint, "We have been iterating in the safepoint loop too long");
dsimms@37176 316 }
dsimms@37176 317 assert(still_running == 0, "sanity check");
dsimms@37176 318
dsimms@37176 319 if (PrintSafepointStatistics) {
dsimms@37176 320 update_statistics_on_spin_end();
dsimms@37176 321 }
dsimms@37176 322
dsimms@37176 323 if (sync_event.should_commit()) {
egahlin@47784 324 // Group this event together with the ones committed after the counter is increased
egahlin@47784 325 sync_event.set_safepointId(safepoint_counter() + 1);
dsimms@37176 326 sync_event.set_initialThreadCount(initial_running);
dsimms@37176 327 sync_event.set_runningThreadCount(_waiting_to_block);
dsimms@37176 328 sync_event.set_iterations(iterations);
dsimms@37176 329 sync_event.commit();
dsimms@37176 330 }
dsimms@37176 331 } //EventSafepointStateSync
dsimms@37176 332
dsimms@37176 333 // wait until all threads are stopped
dsimms@37176 334 {
dsimms@37176 335 EventSafepointWaitBlocked wait_blocked_event;
dsimms@37176 336 int initial_waiting_to_block = _waiting_to_block;
dsimms@37176 337
dsimms@37176 338 while (_waiting_to_block > 0) {
dsimms@37176 339 log_debug(safepoint)("Waiting for %d thread(s) to block", _waiting_to_block);
dsimms@37176 340 if (!SafepointTimeout || timeout_error_printed) {
dsimms@37176 341 Safepoint_lock->wait(true); // true, means with no safepoint checks
dsimms@37176 342 } else {
dsimms@37176 343 // Compute remaining time
dsimms@37176 344 jlong remaining_time = safepoint_limit_time - os::javaTimeNanos();
dsimms@37176 345
dsimms@37176 346 // If there is no remaining time, then there is an error
dsimms@37176 347 if (remaining_time < 0 || Safepoint_lock->wait(true, remaining_time / MICROUNITS)) {
dsimms@37176 348 print_safepoint_timeout(_blocking_timeout);
rprotacio@33763 349 }
duke@1 350 }
duke@1 351 }
dsimms@37176 352 assert(_waiting_to_block == 0, "sanity check");
duke@1 353
dsimms@37176 354 #ifndef PRODUCT
dsimms@37176 355 if (SafepointTimeout) {
dsimms@37176 356 jlong current_time = os::javaTimeNanos();
dsimms@37176 357 if (safepoint_limit_time < current_time) {
dsimms@37176 358 tty->print_cr("# SafepointSynchronize: Finished after "
dsimms@37176 359 INT64_FORMAT_W(6) " ms",
jwilhelm@46630 360 (int64_t)((current_time - safepoint_limit_time) / MICROUNITS +
jwilhelm@46630 361 (jlong)SafepointTimeoutDelay));
duke@1 362 }
duke@1 363 }
duke@1 364 #endif
duke@1 365
dsimms@37176 366 assert((_safepoint_counter & 0x1) == 0, "must be even");
dsimms@37176 367 assert(Threads_lock->owned_by_self(), "must hold Threads_lock");
dsimms@37176 368 _safepoint_counter ++;
duke@1 369
dsimms@37176 370 // Record state
dsimms@37176 371 _state = _synchronized;
duke@1 372
dsimms@37176 373 OrderAccess::fence();
dsimms@37176 374
dsimms@37176 375 if (wait_blocked_event.should_commit()) {
dsimms@37176 376 wait_blocked_event.set_safepointId(safepoint_counter());
dsimms@37176 377 wait_blocked_event.set_runningThreadCount(initial_waiting_to_block);
dsimms@37176 378 wait_blocked_event.commit();
dsimms@37176 379 }
dsimms@37176 380 } // EventSafepointWaitBlocked
duke@1 381
never@12108 382 #ifdef ASSERT
never@12108 383 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) {
never@12108 384 // make sure all the threads were visited
never@12108 385 assert(cur->was_visited_for_critical_count(), "missed a thread");
never@12108 386 }
never@12108 387 #endif // ASSERT
never@12108 388
never@11631 389 // Update the count of active JNI critical regions
david@35492 390 GCLocker::set_jni_lock_count(_current_jni_active_count);
never@11631 391
rprotacio@33763 392 if (log_is_enabled(Debug, safepoint)) {
rehn@46496 393 log_debug(safepoint)("Entering safepoint region: %s", VMThread::vm_safepoint_description());
duke@1 394 }
duke@1 395
duke@1 396 RuntimeService::record_safepoint_synchronized();
duke@1 397 if (PrintSafepointStatistics) {
duke@1 398 update_statistics_on_sync_end(os::javaTimeNanos());
duke@1 399 }
duke@1 400
duke@1 401 // Call stuff that needs to be run when a safepoint is just about to be completed
dsimms@37176 402 {
dsimms@37176 403 EventSafepointCleanup cleanup_event;
dsimms@37176 404 do_cleanup_tasks();
dsimms@37176 405 if (cleanup_event.should_commit()) {
dsimms@37176 406 cleanup_event.set_safepointId(safepoint_counter());
dsimms@37176 407 cleanup_event.commit();
dsimms@37176 408 }
dsimms@37176 409 }
xlu@5042 410
xlu@5042 411 if (PrintSafepointStatistics) {
xlu@5042 412 // Record how much time spend on the above cleanup tasks
xlu@5042 413 update_statistics_on_cleanup_end(os::javaTimeNanos());
xlu@5042 414 }
dsimms@37176 415 if (begin_event.should_commit()) {
dsimms@37176 416 begin_event.set_safepointId(safepoint_counter());
dsimms@37176 417 begin_event.set_totalThreadCount(nof_threads);
dsimms@37176 418 begin_event.set_jniCriticalThreadCount(_current_jni_active_count);
dsimms@37176 419 begin_event.commit();
dsimms@37176 420 }
duke@1 421 }
duke@1 422
duke@1 423 // Wake up all threads, so they are ready to resume execution after the safepoint
duke@1 424 // operation has been carried out
duke@1 425 void SafepointSynchronize::end() {
dsimms@37176 426 EventSafepointEnd event;
dsimms@37176 427 int safepoint_id = safepoint_counter(); // Keep the odd counter as "id"
duke@1 428
duke@1 429 assert(Threads_lock->owned_by_self(), "must hold Threads_lock");
duke@1 430 assert((_safepoint_counter & 0x1) == 1, "must be odd");
duke@1 431 _safepoint_counter ++;
duke@1 432 // memory fence isn't required here since an odd _safepoint_counter
duke@1 433 // value can do no harm and a fence is issued below anyway.
duke@1 434
duke@1 435 DEBUG_ONLY(Thread* myThread = Thread::current();)
duke@1 436 assert(myThread->is_VM_thread(), "Only VM thread can execute a safepoint");
duke@1 437
duke@1 438 if (PrintSafepointStatistics) {
duke@1 439 end_statistics(os::javaTimeNanos());
duke@1 440 }
duke@1 441
duke@1 442 #ifdef ASSERT
duke@1 443 // A pending_exception cannot be installed during a safepoint. The threads
duke@1 444 // may install an async exception after they come back from a safepoint into
duke@1 445 // pending_exception after they unblock. But that should happen later.
duke@1 446 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) {
duke@1 447 assert (!(cur->has_pending_exception() &&
duke@1 448 cur->safepoint_state()->is_at_poll_safepoint()),
duke@1 449 "safepoint installed a pending exception");
duke@1 450 }
duke@1 451 #endif // ASSERT
duke@1 452
duke@1 453 if (PageArmed) {
duke@1 454 // Make polling safepoint aware
duke@1 455 os::make_polling_page_readable();
duke@1 456 PageArmed = 0 ;
duke@1 457 }
duke@1 458
duke@1 459 // Remove safepoint check from interpreter
duke@1 460 Interpreter::ignore_safepoints();
duke@1 461
duke@1 462 {
duke@1 463 MutexLocker mu(Safepoint_lock);
duke@1 464
duke@1 465 assert(_state == _synchronized, "must be synchronized before ending safepoint synchronization");
duke@1 466
duke@1 467 // Set to not synchronized, so the threads will not go into the signal_thread_blocked method
duke@1 468 // when they get restarted.
duke@1 469 _state = _not_synchronized;
duke@1 470 OrderAccess::fence();
duke@1 471
rprotacio@33763 472 log_debug(safepoint)("Leaving safepoint region");
duke@1 473
duke@1 474 // Start suspended threads
duke@1 475 for(JavaThread *current = Threads::first(); current; current = current->next()) {
twisti@2131 476 // A problem occurring on Solaris is when attempting to restart threads
duke@1 477 // the first #cpus - 1 go well, but then the VMThread is preempted when we get
duke@1 478 // to the next one (since it has been running the longest). We then have
duke@1 479 // to wait for a cpu to become available before we can continue restarting
duke@1 480 // threads.
duke@1 481 // FIXME: This causes the performance of the VM to degrade when active and with
duke@1 482 // large numbers of threads. Apparently this is due to the synchronous nature
duke@1 483 // of suspending threads.
duke@1 484 //
duke@1 485 // TODO-FIXME: the comments above are vestigial and no longer apply.
duke@1 486 // Furthermore, using solaris' schedctl in this particular context confers no benefit
duke@1 487 if (VMThreadHintNoPreempt) {
duke@1 488 os::hint_no_preempt();
duke@1 489 }
duke@1 490 ThreadSafepointState* cur_state = current->safepoint_state();
duke@1 491 assert(cur_state->type() != ThreadSafepointState::_running, "Thread not suspended at safepoint");
duke@1 492 cur_state->restart();
duke@1 493 assert(cur_state->is_running(), "safepoint state has not been reset");
duke@1 494 }
duke@1 495
duke@1 496 RuntimeService::record_safepoint_end();
duke@1 497
duke@1 498 // Release threads lock, so threads can be created/destroyed again. It will also starts all threads
duke@1 499 // blocked in signal_thread_blocked
duke@1 500 Threads_lock->unlock();
duke@1 501
duke@1 502 }
eosterlund@47791 503 Universe::heap()->safepoint_synchronize_end();
jwilhelm@22551 504 // record this time so VMThread can keep track how much time has elapsed
xlu@5042 505 // since last safepoint.
xlu@5042 506 _end_of_last_safepoint = os::javaTimeMillis();
dsimms@37176 507
dsimms@37176 508 if (event.should_commit()) {
dsimms@37176 509 event.set_safepointId(safepoint_id);
dsimms@37176 510 event.commit();
dsimms@37176 511 }
duke@1 512 }
duke@1 513
duke@1 514 bool SafepointSynchronize::is_cleanup_needed() {
rehn@46541 515 // Need a safepoint if there are many monitors to deflate.
rehn@46541 516 if (ObjectSynchronizer::is_cleanup_needed()) return true;
duke@1 517 // Need a safepoint if some inline cache buffers is non-empty
duke@1 518 if (!InlineCacheBuffer::is_empty()) return true;
duke@1 519 return false;
duke@1 520 }
duke@1 521
dsimms@37176 522 static void event_safepoint_cleanup_task_commit(EventSafepointCleanupTask& event, const char* name) {
dsimms@37176 523 if (event.should_commit()) {
dsimms@37176 524 event.set_safepointId(SafepointSynchronize::safepoint_counter());
dsimms@37176 525 event.set_name(name);
dsimms@37176 526 event.commit();
dsimms@37176 527 }
dsimms@37176 528 }
duke@1 529
rkennke@46702 530 class ParallelSPCleanupThreadClosure : public ThreadClosure {
rkennke@46702 531 private:
rkennke@46702 532 CodeBlobClosure* _nmethod_cl;
rkennke@46702 533 DeflateMonitorCounters* _counters;
rkennke@46702 534
rkennke@46702 535 public:
rkennke@46702 536 ParallelSPCleanupThreadClosure(DeflateMonitorCounters* counters) :
rkennke@46702 537 _counters(counters),
rkennke@46702 538 _nmethod_cl(NMethodSweeper::prepare_mark_active_nmethods()) {}
rkennke@46702 539
rkennke@46702 540 void do_thread(Thread* thread) {
rkennke@46702 541 ObjectSynchronizer::deflate_thread_local_monitors(thread, _counters);
rkennke@46702 542 if (_nmethod_cl != NULL && thread->is_Java_thread() &&
rkennke@46702 543 ! thread->is_Code_cache_sweeper_thread()) {
rkennke@46702 544 JavaThread* jt = (JavaThread*) thread;
rkennke@46702 545 jt->nmethods_do(_nmethod_cl);
rkennke@46702 546 }
rkennke@46702 547 }
rkennke@46702 548 };
rkennke@46702 549
rkennke@46702 550 class ParallelSPCleanupTask : public AbstractGangTask {
rkennke@46702 551 private:
rkennke@46702 552 SubTasksDone _subtasks;
rkennke@46702 553 ParallelSPCleanupThreadClosure _cleanup_threads_cl;
rkennke@46702 554 uint _num_workers;
rkennke@46702 555 DeflateMonitorCounters* _counters;
rkennke@46702 556 public:
rkennke@46702 557 ParallelSPCleanupTask(uint num_workers, DeflateMonitorCounters* counters) :
rkennke@46702 558 AbstractGangTask("Parallel Safepoint Cleanup"),
rkennke@46702 559 _cleanup_threads_cl(ParallelSPCleanupThreadClosure(counters)),
rkennke@46702 560 _num_workers(num_workers),
rkennke@46702 561 _subtasks(SubTasksDone(SafepointSynchronize::SAFEPOINT_CLEANUP_NUM_TASKS)),
rkennke@46702 562 _counters(counters) {}
rkennke@46702 563
rkennke@46702 564 void work(uint worker_id) {
rkennke@46702 565 // All threads deflate monitors and mark nmethods (if necessary).
rkennke@47792 566 Threads::possibly_parallel_threads_do(true, &_cleanup_threads_cl);
rkennke@46702 567
rkennke@46702 568 if (!_subtasks.is_task_claimed(SafepointSynchronize::SAFEPOINT_CLEANUP_DEFLATE_MONITORS)) {
rkennke@46702 569 const char* name = "deflating idle monitors";
rkennke@46702 570 EventSafepointCleanupTask event;
rkennke@46702 571 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
rkennke@46702 572 ObjectSynchronizer::deflate_idle_monitors(_counters);
rkennke@46702 573 event_safepoint_cleanup_task_commit(event, name);
rkennke@46702 574 }
rkennke@46702 575
rkennke@46702 576 if (!_subtasks.is_task_claimed(SafepointSynchronize::SAFEPOINT_CLEANUP_UPDATE_INLINE_CACHES)) {
rkennke@46702 577 const char* name = "updating inline caches";
rkennke@46702 578 EventSafepointCleanupTask event;
rkennke@46702 579 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
rkennke@46702 580 InlineCacheBuffer::update_inline_caches();
rkennke@46702 581 event_safepoint_cleanup_task_commit(event, name);
rkennke@46702 582 }
rkennke@46702 583
rkennke@46702 584 if (!_subtasks.is_task_claimed(SafepointSynchronize::SAFEPOINT_CLEANUP_COMPILATION_POLICY)) {
rkennke@46702 585 const char* name = "compilation policy safepoint handler";
rkennke@46702 586 EventSafepointCleanupTask event;
rkennke@46702 587 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
rkennke@46702 588 CompilationPolicy::policy()->do_safepoint_work();
rkennke@46702 589 event_safepoint_cleanup_task_commit(event, name);
rkennke@46702 590 }
rkennke@46702 591
rkennke@46702 592 if (!_subtasks.is_task_claimed(SafepointSynchronize::SAFEPOINT_CLEANUP_SYMBOL_TABLE_REHASH)) {
rkennke@46702 593 if (SymbolTable::needs_rehashing()) {
rkennke@46702 594 const char* name = "rehashing symbol table";
rkennke@46702 595 EventSafepointCleanupTask event;
rkennke@46702 596 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
rkennke@46702 597 SymbolTable::rehash_table();
rkennke@46702 598 event_safepoint_cleanup_task_commit(event, name);
rkennke@46702 599 }
rkennke@46702 600 }
rkennke@46702 601
rkennke@46702 602 if (!_subtasks.is_task_claimed(SafepointSynchronize::SAFEPOINT_CLEANUP_STRING_TABLE_REHASH)) {
rkennke@46702 603 if (StringTable::needs_rehashing()) {
rkennke@46702 604 const char* name = "rehashing string table";
rkennke@46702 605 EventSafepointCleanupTask event;
rkennke@46702 606 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
rkennke@46702 607 StringTable::rehash_table();
rkennke@46702 608 event_safepoint_cleanup_task_commit(event, name);
rkennke@46702 609 }
rkennke@46702 610 }
rkennke@46702 611
rkennke@46702 612 if (!_subtasks.is_task_claimed(SafepointSynchronize::SAFEPOINT_CLEANUP_CLD_PURGE)) {
rkennke@46702 613 // CMS delays purging the CLDG until the beginning of the next safepoint and to
rkennke@46702 614 // make sure concurrent sweep is done
rkennke@46702 615 const char* name = "purging class loader data graph";
rkennke@46702 616 EventSafepointCleanupTask event;
rkennke@46702 617 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
rkennke@46702 618 ClassLoaderDataGraph::purge_if_needed();
rkennke@46702 619 event_safepoint_cleanup_task_commit(event, name);
rkennke@46702 620 }
rkennke@46702 621 _subtasks.all_tasks_completed(_num_workers);
rkennke@46702 622 }
rkennke@46702 623 };
rkennke@46702 624
rkennke@46702 625 // Various cleaning tasks that should be done periodically at safepoints.
duke@1 626 void SafepointSynchronize::do_cleanup_tasks() {
rkennke@46702 627
rkennke@46702 628 TraceTime timer("safepoint cleanup tasks", TRACETIME_LOG(Info, safepoint, cleanup));
rkennke@46702 629
rkennke@46702 630 // Prepare for monitor deflation.
rkennke@46702 631 DeflateMonitorCounters deflate_counters;
rkennke@46702 632 ObjectSynchronizer::prepare_deflate_idle_monitors(&deflate_counters);
rkennke@46702 633
rkennke@46702 634 CollectedHeap* heap = Universe::heap();
rkennke@46702 635 assert(heap != NULL, "heap not initialized yet?");
rkennke@46702 636 WorkGang* cleanup_workers = heap->get_safepoint_workers();
rkennke@46702 637 if (cleanup_workers != NULL) {
rkennke@46702 638 // Parallel cleanup using GC provided thread pool.
rkennke@46702 639 uint num_cleanup_workers = cleanup_workers->active_workers();
rkennke@46702 640 ParallelSPCleanupTask cleanup(num_cleanup_workers, &deflate_counters);
rkennke@46702 641 StrongRootsScope srs(num_cleanup_workers);
rkennke@46702 642 cleanup_workers->run_task(&cleanup);
rkennke@46702 643 } else {
rkennke@46702 644 // Serial cleanup using VMThread.
rkennke@46702 645 ParallelSPCleanupTask cleanup(1, &deflate_counters);
rkennke@46702 646 StrongRootsScope srs(1);
rkennke@46702 647 cleanup.work(0);
duke@1 648 }
duke@1 649
rkennke@46702 650 // Finish monitor deflation.
rkennke@46702 651 ObjectSynchronizer::finish_deflate_idle_monitors(&deflate_counters);
duke@1 652 }
duke@1 653
duke@1 654
duke@1 655 bool SafepointSynchronize::safepoint_safe(JavaThread *thread, JavaThreadState state) {
duke@1 656 switch(state) {
duke@1 657 case _thread_in_native:
duke@1 658 // native threads are safe if they have no java stack or have walkable stack
duke@1 659 return !thread->has_last_Java_frame() || thread->frame_anchor()->walkable();
duke@1 660
duke@1 661 // blocked threads should have already have walkable stack
duke@1 662 case _thread_blocked:
duke@1 663 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "blocked and not walkable");
duke@1 664 return true;
duke@1 665
duke@1 666 default:
duke@1 667 return false;
duke@1 668 }
duke@1 669 }
duke@1 670
duke@1 671
never@11637 672 // See if the thread is running inside a lazy critical native and
never@11637 673 // update the thread critical count if so. Also set a suspend flag to
never@11637 674 // cause the native wrapper to return into the JVM to do the unlock
never@11637 675 // once the native finishes.
never@11637 676 void SafepointSynchronize::check_for_lazy_critical_native(JavaThread *thread, JavaThreadState state) {
never@11637 677 if (state == _thread_in_native &&
never@11637 678 thread->has_last_Java_frame() &&
never@11637 679 thread->frame_anchor()->walkable()) {
never@11637 680 // This thread might be in a critical native nmethod so look at
never@11637 681 // the top of the stack and increment the critical count if it
never@11637 682 // is.
never@11637 683 frame wrapper_frame = thread->last_frame();
never@11637 684 CodeBlob* stub_cb = wrapper_frame.cb();
never@11637 685 if (stub_cb != NULL &&
never@11637 686 stub_cb->is_nmethod() &&
never@11637 687 stub_cb->as_nmethod_or_null()->is_lazy_critical_native()) {
never@11637 688 // A thread could potentially be in a critical native across
never@11637 689 // more than one safepoint, so only update the critical state on
never@11637 690 // the first one. When it returns it will perform the unlock.
never@11637 691 if (!thread->do_critical_native_unlock()) {
never@11637 692 #ifdef ASSERT
never@11637 693 if (!thread->in_critical()) {
david@35492 694 GCLocker::increment_debug_jni_lock_count();
never@11637 695 }
never@11637 696 #endif
never@11637 697 thread->enter_critical();
never@11637 698 // Make sure the native wrapper calls back on return to
never@11637 699 // perform the needed critical unlock.
never@11637 700 thread->set_critical_native_unlock();
never@11637 701 }
never@11637 702 }
never@11637 703 }
never@11637 704 }
never@11637 705
never@11637 706
never@11637 707
duke@1 708 // -------------------------------------------------------------------------------------------------------
duke@1 709 // Implementation of Safepoint callback point
duke@1 710
duke@1 711 void SafepointSynchronize::block(JavaThread *thread) {
duke@1 712 assert(thread != NULL, "thread must be set");
duke@1 713 assert(thread->is_Java_thread(), "not a Java thread");
duke@1 714
duke@1 715 // Threads shouldn't block if they are in the middle of printing, but...
duke@1 716 ttyLocker::break_tty_lock_for_safepoint(os::current_thread_id());
duke@1 717
duke@1 718 // Only bail from the block() call if the thread is gone from the
duke@1 719 // thread list; starting to exit should still block.
duke@1 720 if (thread->is_terminated()) {
duke@1 721 // block current thread if we come here from native code when VM is gone
duke@1 722 thread->block_if_vm_exited();
duke@1 723
duke@1 724 // otherwise do nothing
duke@1 725 return;
duke@1 726 }
duke@1 727
duke@1 728 JavaThreadState state = thread->thread_state();
duke@1 729 thread->frame_anchor()->make_walkable(thread);
duke@1 730
duke@1 731 // Check that we have a valid thread_state at this point
duke@1 732 switch(state) {
duke@1 733 case _thread_in_vm_trans:
duke@1 734 case _thread_in_Java: // From compiled code
duke@1 735
duke@1 736 // We are highly likely to block on the Safepoint_lock. In order to avoid blocking in this case,
duke@1 737 // we pretend we are still in the VM.
duke@1 738 thread->set_thread_state(_thread_in_vm);
duke@1 739
duke@1 740 if (is_synchronizing()) {
duke@1 741 Atomic::inc (&TryingToBlock) ;
duke@1 742 }
duke@1 743
duke@1 744 // We will always be holding the Safepoint_lock when we are examine the state
duke@1 745 // of a thread. Hence, the instructions between the Safepoint_lock->lock() and
duke@1 746 // Safepoint_lock->unlock() are happening atomic with regards to the safepoint code
duke@1 747 Safepoint_lock->lock_without_safepoint_check();
duke@1 748 if (is_synchronizing()) {
duke@1 749 // Decrement the number of threads to wait for and signal vm thread
duke@1 750 assert(_waiting_to_block > 0, "sanity check");
duke@1 751 _waiting_to_block--;
duke@1 752 thread->safepoint_state()->set_has_called_back(true);
duke@1 753
never@12108 754 DEBUG_ONLY(thread->set_visited_for_critical_count(true));
never@11631 755 if (thread->in_critical()) {
never@11631 756 // Notice that this thread is in a critical section
never@11631 757 increment_jni_active_count();
never@11631 758 }
never@11631 759
duke@1 760 // Consider (_waiting_to_block < 2) to pipeline the wakeup of the VM thread
duke@1 761 if (_waiting_to_block == 0) {
duke@1 762 Safepoint_lock->notify_all();
duke@1 763 }
duke@1 764 }
duke@1 765
duke@1 766 // We transition the thread to state _thread_blocked here, but
duke@1 767 // we can't do our usual check for external suspension and then
duke@1 768 // self-suspend after the lock_without_safepoint_check() call
duke@1 769 // below because we are often called during transitions while
duke@1 770 // we hold different locks. That would leave us suspended while
duke@1 771 // holding a resource which results in deadlocks.
duke@1 772 thread->set_thread_state(_thread_blocked);
duke@1 773 Safepoint_lock->unlock();
duke@1 774
duke@1 775 // We now try to acquire the threads lock. Since this lock is hold by the VM thread during
duke@1 776 // the entire safepoint, the threads will all line up here during the safepoint.
duke@1 777 Threads_lock->lock_without_safepoint_check();
duke@1 778 // restore original state. This is important if the thread comes from compiled code, so it
duke@1 779 // will continue to execute with the _thread_in_Java state.
duke@1 780 thread->set_thread_state(state);
duke@1 781 Threads_lock->unlock();
duke@1 782 break;
duke@1 783
duke@1 784 case _thread_in_native_trans:
duke@1 785 case _thread_blocked_trans:
duke@1 786 case _thread_new_trans:
duke@1 787 if (thread->safepoint_state()->type() == ThreadSafepointState::_call_back) {
duke@1 788 thread->print_thread_state();
duke@1 789 fatal("Deadlock in safepoint code. "
duke@1 790 "Should have called back to the VM before blocking.");
duke@1 791 }
duke@1 792
duke@1 793 // We transition the thread to state _thread_blocked here, but
duke@1 794 // we can't do our usual check for external suspension and then
duke@1 795 // self-suspend after the lock_without_safepoint_check() call
duke@1 796 // below because we are often called during transitions while
duke@1 797 // we hold different locks. That would leave us suspended while
duke@1 798 // holding a resource which results in deadlocks.
duke@1 799 thread->set_thread_state(_thread_blocked);
duke@1 800
duke@1 801 // It is not safe to suspend a thread if we discover it is in _thread_in_native_trans. Hence,
duke@1 802 // the safepoint code might still be waiting for it to block. We need to change the state here,
duke@1 803 // so it can see that it is at a safepoint.
duke@1 804
duke@1 805 // Block until the safepoint operation is completed.
duke@1 806 Threads_lock->lock_without_safepoint_check();
duke@1 807
duke@1 808 // Restore state
duke@1 809 thread->set_thread_state(state);
duke@1 810
duke@1 811 Threads_lock->unlock();
duke@1 812 break;
duke@1 813
duke@1 814 default:
david@33105 815 fatal("Illegal threadstate encountered: %d", state);
duke@1 816 }
duke@1 817
duke@1 818 // Check for pending. async. exceptions or suspends - except if the
duke@1 819 // thread was blocked inside the VM. has_special_runtime_exit_condition()
duke@1 820 // is called last since it grabs a lock and we only want to do that when
duke@1 821 // we must.
duke@1 822 //
duke@1 823 // Note: we never deliver an async exception at a polling point as the
duke@1 824 // compiler may not have an exception handler for it. The polling
duke@1 825 // code will notice the async and deoptimize and the exception will
duke@1 826 // be delivered. (Polling at a return point is ok though). Sure is
duke@1 827 // a lot of bother for a deprecated feature...
duke@1 828 //
duke@1 829 // We don't deliver an async exception if the thread state is
duke@1 830 // _thread_in_native_trans so JNI functions won't be called with
duke@1 831 // a surprising pending exception. If the thread state is going back to java,
duke@1 832 // async exception is checked in check_special_condition_for_native_trans().
duke@1 833
duke@1 834 if (state != _thread_blocked_trans &&
duke@1 835 state != _thread_in_vm_trans &&
duke@1 836 thread->has_special_runtime_exit_condition()) {
duke@1 837 thread->handle_special_runtime_exit_condition(
duke@1 838 !thread->is_at_poll_safepoint() && (state != _thread_in_native_trans));
duke@1 839 }
duke@1 840 }
duke@1 841
duke@1 842 // ------------------------------------------------------------------------------------------------------
duke@1 843 // Exception handlers
duke@1 844
duke@1 845
duke@1 846 void SafepointSynchronize::handle_polling_page_exception(JavaThread *thread) {
duke@1 847 assert(thread->is_Java_thread(), "polling reference encountered by VM thread");
duke@1 848 assert(thread->thread_state() == _thread_in_Java, "should come from Java code");
duke@1 849 assert(SafepointSynchronize::is_synchronizing(), "polling encountered outside safepoint synchronization");
duke@1 850
duke@1 851 if (ShowSafepointMsgs) {
duke@1 852 tty->print("handle_polling_page_exception: ");
duke@1 853 }
duke@1 854
duke@1 855 if (PrintSafepointStatistics) {
duke@1 856 inc_page_trap_count();
duke@1 857 }
duke@1 858
duke@1 859 ThreadSafepointState* state = thread->safepoint_state();
duke@1 860
duke@1 861 state->handle_polling_page_exception();
duke@1 862 }
duke@1 863
duke@1 864
duke@1 865 void SafepointSynchronize::print_safepoint_timeout(SafepointTimeoutReason reason) {
duke@1 866 if (!timeout_error_printed) {
duke@1 867 timeout_error_printed = true;
jwilhelm@22551 868 // Print out the thread info which didn't reach the safepoint for debugging
duke@1 869 // purposes (useful when there are lots of threads in the debugger).
drchase@24424 870 tty->cr();
duke@1 871 tty->print_cr("# SafepointSynchronize::begin: Timeout detected:");
duke@1 872 if (reason == _spinning_timeout) {
duke@1 873 tty->print_cr("# SafepointSynchronize::begin: Timed out while spinning to reach a safepoint.");
duke@1 874 } else if (reason == _blocking_timeout) {
duke@1 875 tty->print_cr("# SafepointSynchronize::begin: Timed out while waiting for threads to stop.");
duke@1 876 }
duke@1 877
duke@1 878 tty->print_cr("# SafepointSynchronize::begin: Threads which did not reach the safepoint:");
duke@1 879 ThreadSafepointState *cur_state;
duke@1 880 ResourceMark rm;
duke@1 881 for(JavaThread *cur_thread = Threads::first(); cur_thread;
duke@1 882 cur_thread = cur_thread->next()) {
duke@1 883 cur_state = cur_thread->safepoint_state();
duke@1 884
duke@1 885 if (cur_thread->thread_state() != _thread_blocked &&
duke@1 886 ((reason == _spinning_timeout && cur_state->is_running()) ||
duke@1 887 (reason == _blocking_timeout && !cur_state->has_called_back()))) {
duke@1 888 tty->print("# ");
duke@1 889 cur_thread->print();
drchase@24424 890 tty->cr();
duke@1 891 }
duke@1 892 }
duke@1 893 tty->print_cr("# SafepointSynchronize::begin: (End of list)");
duke@1 894 }
duke@1 895
duke@1 896 // To debug the long safepoint, specify both DieOnSafepointTimeout &
duke@1 897 // ShowMessageBoxOnError.
duke@1 898 if (DieOnSafepointTimeout) {
david@33105 899 fatal("Safepoint sync time longer than " INTX_FORMAT "ms detected when executing %s.",
rehn@46496 900 SafepointTimeoutDelay, VMThread::vm_safepoint_description());
duke@1 901 }
duke@1 902 }
duke@1 903
duke@1 904
duke@1 905 // -------------------------------------------------------------------------------------------------------
duke@1 906 // Implementation of ThreadSafepointState
duke@1 907
duke@1 908 ThreadSafepointState::ThreadSafepointState(JavaThread *thread) {
duke@1 909 _thread = thread;
duke@1 910 _type = _running;
duke@1 911 _has_called_back = false;
duke@1 912 _at_poll_safepoint = false;
duke@1 913 }
duke@1 914
duke@1 915 void ThreadSafepointState::create(JavaThread *thread) {
duke@1 916 ThreadSafepointState *state = new ThreadSafepointState(thread);
duke@1 917 thread->set_safepoint_state(state);
duke@1 918 }
duke@1 919
duke@1 920 void ThreadSafepointState::destroy(JavaThread *thread) {
duke@1 921 if (thread->safepoint_state()) {
duke@1 922 delete(thread->safepoint_state());
duke@1 923 thread->set_safepoint_state(NULL);
duke@1 924 }
duke@1 925 }
duke@1 926
duke@1 927 void ThreadSafepointState::examine_state_of_thread() {
duke@1 928 assert(is_running(), "better be running or just have hit safepoint poll");
duke@1 929
duke@1 930 JavaThreadState state = _thread->thread_state();
duke@1 931
never@6269 932 // Save the state at the start of safepoint processing.
never@6269 933 _orig_thread_state = state;
never@6269 934
duke@1 935 // Check for a thread that is suspended. Note that thread resume tries
duke@1 936 // to grab the Threads_lock which we own here, so a thread cannot be
duke@1 937 // resumed during safepoint synchronization.
duke@1 938
dcubed@3826 939 // We check to see if this thread is suspended without locking to
dcubed@3826 940 // avoid deadlocking with a third thread that is waiting for this
dcubed@3826 941 // thread to be suspended. The third thread can notice the safepoint
dcubed@3826 942 // that we're trying to start at the beginning of its SR_lock->wait()
dcubed@3826 943 // call. If that happens, then the third thread will block on the
dcubed@3826 944 // safepoint while still holding the underlying SR_lock. We won't be
dcubed@3826 945 // able to get the SR_lock and we'll deadlock.
dcubed@3826 946 //
dcubed@3826 947 // We don't need to grab the SR_lock here for two reasons:
dcubed@3826 948 // 1) The suspend flags are both volatile and are set with an
dcubed@3826 949 // Atomic::cmpxchg() call so we should see the suspended
dcubed@3826 950 // state right away.
dcubed@3826 951 // 2) We're being called from the safepoint polling loop; if
dcubed@3826 952 // we don't see the suspended state on this iteration, then
dcubed@3826 953 // we'll come around again.
dcubed@3826 954 //
dcubed@3826 955 bool is_suspended = _thread->is_ext_suspended();
duke@1 956 if (is_suspended) {
duke@1 957 roll_forward(_at_safepoint);
duke@1 958 return;
duke@1 959 }
duke@1 960
duke@1 961 // Some JavaThread states have an initial safepoint state of
duke@1 962 // running, but are actually at a safepoint. We will happily
duke@1 963 // agree and update the safepoint state here.
duke@1 964 if (SafepointSynchronize::safepoint_safe(_thread, state)) {
never@12108 965 SafepointSynchronize::check_for_lazy_critical_native(_thread, state);
never@11631 966 roll_forward(_at_safepoint);
never@11631 967 return;
duke@1 968 }
duke@1 969
duke@1 970 if (state == _thread_in_vm) {
duke@1 971 roll_forward(_call_back);
duke@1 972 return;
duke@1 973 }
duke@1 974
duke@1 975 // All other thread states will continue to run until they
duke@1 976 // transition and self-block in state _blocked
duke@1 977 // Safepoint polling in compiled code causes the Java threads to do the same.
duke@1 978 // Note: new threads may require a malloc so they must be allowed to finish
duke@1 979
duke@1 980 assert(is_running(), "examine_state_of_thread on non-running thread");
duke@1 981 return;
duke@1 982 }
duke@1 983
duke@1 984 // Returns true is thread could not be rolled forward at present position.
duke@1 985 void ThreadSafepointState::roll_forward(suspend_type type) {
duke@1 986 _type = type;
duke@1 987
duke@1 988 switch(_type) {
duke@1 989 case _at_safepoint:
duke@1 990 SafepointSynchronize::signal_thread_at_safepoint();
never@12108 991 DEBUG_ONLY(_thread->set_visited_for_critical_count(true));
never@12108 992 if (_thread->in_critical()) {
never@12108 993 // Notice that this thread is in a critical section
never@12108 994 SafepointSynchronize::increment_jni_active_count();
never@12108 995 }
duke@1 996 break;
duke@1 997
duke@1 998 case _call_back:
duke@1 999 set_has_called_back(false);
duke@1 1000 break;
duke@1 1001
duke@1 1002 case _running:
duke@1 1003 default:
duke@1 1004 ShouldNotReachHere();
duke@1 1005 }
duke@1 1006 }
duke@1 1007
duke@1 1008 void ThreadSafepointState::restart() {
duke@1 1009 switch(type()) {
duke@1 1010 case _at_safepoint:
duke@1 1011 case _call_back:
duke@1 1012 break;
duke@1 1013
duke@1 1014 case _running:
duke@1 1015 default:
bpittore@31592 1016 tty->print_cr("restart thread " INTPTR_FORMAT " with state %d",
david@33148 1017 p2i(_thread), _type);
duke@1 1018 _thread->print();
duke@1 1019 ShouldNotReachHere();
duke@1 1020 }
duke@1 1021 _type = _running;
duke@1 1022 set_has_called_back(false);
duke@1 1023 }
duke@1 1024
duke@1 1025
duke@1 1026 void ThreadSafepointState::print_on(outputStream *st) const {
goetz@33589 1027 const char *s = NULL;
duke@1 1028
duke@1 1029 switch(_type) {
duke@1 1030 case _running : s = "_running"; break;
duke@1 1031 case _at_safepoint : s = "_at_safepoint"; break;
duke@1 1032 case _call_back : s = "_call_back"; break;
duke@1 1033 default:
duke@1 1034 ShouldNotReachHere();
duke@1 1035 }
duke@1 1036
duke@1 1037 st->print_cr("Thread: " INTPTR_FORMAT
duke@1 1038 " [0x%2x] State: %s _has_called_back %d _at_poll_safepoint %d",
david@33148 1039 p2i(_thread), _thread->osthread()->thread_id(), s, _has_called_back,
duke@1 1040 _at_poll_safepoint);
duke@1 1041
duke@1 1042 _thread->print_thread_state_on(st);
duke@1 1043 }
duke@1 1044
duke@1 1045 // ---------------------------------------------------------------------------------------------------------------------
duke@1 1046
duke@1 1047 // Block the thread at the safepoint poll or poll return.
duke@1 1048 void ThreadSafepointState::handle_polling_page_exception() {
duke@1 1049
duke@1 1050 // Check state. block() will set thread state to thread_in_vm which will
duke@1 1051 // cause the safepoint state _type to become _call_back.
duke@1 1052 assert(type() == ThreadSafepointState::_running,
duke@1 1053 "polling page exception on thread not running state");
duke@1 1054
duke@1 1055 // Step 1: Find the nmethod from the return address
duke@1 1056 if (ShowSafepointMsgs && Verbose) {
david@33148 1057 tty->print_cr("Polling page exception at " INTPTR_FORMAT, p2i(thread()->saved_exception_pc()));
duke@1 1058 }
duke@1 1059 address real_return_addr = thread()->saved_exception_pc();
duke@1 1060
duke@1 1061 CodeBlob *cb = CodeCache::find_blob(real_return_addr);
rbackman@38133 1062 assert(cb != NULL && cb->is_compiled(), "return address should be in nmethod");
rbackman@38133 1063 CompiledMethod* nm = (CompiledMethod*)cb;
duke@1 1064
duke@1 1065 // Find frame of caller
duke@1 1066 frame stub_fr = thread()->last_frame();
duke@1 1067 CodeBlob* stub_cb = stub_fr.cb();
duke@1 1068 assert(stub_cb->is_safepoint_stub(), "must be a safepoint stub");
duke@1 1069 RegisterMap map(thread(), true);
duke@1 1070 frame caller_fr = stub_fr.sender(&map);
duke@1 1071
duke@1 1072 // Should only be poll_return or poll
duke@1 1073 assert( nm->is_at_poll_or_poll_return(real_return_addr), "should not be at call" );
duke@1 1074
duke@1 1075 // This is a poll immediately before a return. The exception handling code
duke@1 1076 // has already had the effect of causing the return to occur, so the execution
duke@1 1077 // will continue immediately after the call. In addition, the oopmap at the
duke@1 1078 // return point does not mark the return value as an oop (if it is), so
duke@1 1079 // it needs a handle here to be updated.
duke@1 1080 if( nm->is_at_poll_return(real_return_addr) ) {
duke@1 1081 // See if return type is an oop.
duke@1 1082 bool return_oop = nm->method()->is_returning_oop();
duke@1 1083 Handle return_value;
duke@1 1084 if (return_oop) {
duke@1 1085 // The oop result has been saved on the stack together with all
duke@1 1086 // the other registers. In order to preserve it over GCs we need
duke@1 1087 // to keep it in a handle.
duke@1 1088 oop result = caller_fr.saved_oop_result(&map);
coleenp@46968 1089 assert(oopDesc::is_oop_or_null(result), "must be oop");
duke@1 1090 return_value = Handle(thread(), result);
duke@1 1091 assert(Universe::heap()->is_in_or_null(result), "must be heap pointer");
duke@1 1092 }
duke@1 1093
duke@1 1094 // Block the thread
duke@1 1095 SafepointSynchronize::block(thread());
duke@1 1096
duke@1 1097 // restore oop result, if any
duke@1 1098 if (return_oop) {
duke@1 1099 caller_fr.set_saved_oop_result(&map, return_value());
duke@1 1100 }
duke@1 1101 }
duke@1 1102
duke@1 1103 // This is a safepoint poll. Verify the return address and block.
duke@1 1104 else {
duke@1 1105 set_at_poll_safepoint(true);
duke@1 1106
duke@1 1107 // verify the blob built the "return address" correctly
duke@1 1108 assert(real_return_addr == caller_fr.pc(), "must match");
duke@1 1109
duke@1 1110 // Block the thread
duke@1 1111 SafepointSynchronize::block(thread());
duke@1 1112 set_at_poll_safepoint(false);
duke@1 1113
duke@1 1114 // If we have a pending async exception deoptimize the frame
duke@1 1115 // as otherwise we may never deliver it.
duke@1 1116 if (thread()->has_async_condition()) {
duke@1 1117 ThreadInVMfromJavaNoAsyncException __tiv(thread());
never@7106 1118 Deoptimization::deoptimize_frame(thread(), caller_fr.id());
duke@1 1119 }
duke@1 1120
duke@1 1121 // If an exception has been installed we must check for a pending deoptimization
duke@1 1122 // Deoptimize frame if exception has been thrown.
duke@1 1123
duke@1 1124 if (thread()->has_pending_exception() ) {
duke@1 1125 RegisterMap map(thread(), true);
duke@1 1126 frame caller_fr = stub_fr.sender(&map);
duke@1 1127 if (caller_fr.is_deoptimized_frame()) {
duke@1 1128 // The exception patch will destroy registers that are still
duke@1 1129 // live and will be needed during deoptimization. Defer the
jwilhelm@22551 1130 // Async exception should have deferred the exception until the
duke@1 1131 // next safepoint which will be detected when we get into
duke@1 1132 // the interpreter so if we have an exception now things
duke@1 1133 // are messed up.
duke@1 1134
duke@1 1135 fatal("Exception installed and deoptimization is pending");
duke@1 1136 }
duke@1 1137 }
duke@1 1138 }
duke@1 1139 }
duke@1 1140
duke@1 1141
duke@1 1142 //
duke@1 1143 // Statistics & Instrumentations
duke@1 1144 //
duke@1 1145 SafepointSynchronize::SafepointStats* SafepointSynchronize::_safepoint_stats = NULL;
xlu@5042 1146 jlong SafepointSynchronize::_safepoint_begin_time = 0;
duke@1 1147 int SafepointSynchronize::_cur_stat_index = 0;
duke@1 1148 julong SafepointSynchronize::_safepoint_reasons[VM_Operation::VMOp_Terminating];
duke@1 1149 julong SafepointSynchronize::_coalesced_vmop_count = 0;
duke@1 1150 jlong SafepointSynchronize::_max_sync_time = 0;
xlu@5042 1151 jlong SafepointSynchronize::_max_vmop_time = 0;
xlu@5042 1152 float SafepointSynchronize::_ts_of_current_safepoint = 0.0f;
duke@1 1153
xlu@5042 1154 static jlong cleanup_end_time = 0;
duke@1 1155 static bool need_to_track_page_armed_status = false;
duke@1 1156 static bool init_done = false;
duke@1 1157
xlu@5042 1158 // Helper method to print the header.
xlu@5042 1159 static void print_header() {
shade@46473 1160 // The number of spaces is significant here, and should match the format
shade@46473 1161 // specifiers in print_statistics().
shade@46473 1162
shade@46473 1163 tty->print(" vmop "
shade@46473 1164 "[ threads: total initially_running wait_to_block ]"
shade@46473 1165 "[ time: spin block sync cleanup vmop ] ");
xlu@5042 1166
xlu@5042 1167 // no page armed status printed out if it is always armed.
xlu@5042 1168 if (need_to_track_page_armed_status) {
xlu@5042 1169 tty->print("page_armed ");
xlu@5042 1170 }
xlu@5042 1171
xlu@5042 1172 tty->print_cr("page_trap_count");
xlu@5042 1173 }
xlu@5042 1174
duke@1 1175 void SafepointSynchronize::deferred_initialize_stat() {
duke@1 1176 if (init_done) return;
duke@1 1177
duke@1 1178 // If PrintSafepointStatisticsTimeout is specified, the statistics data will
duke@1 1179 // be printed right away, in which case, _safepoint_stats will regress to
duke@1 1180 // a single element array. Otherwise, it is a circular ring buffer with default
duke@1 1181 // size of PrintSafepointStatisticsCount.
duke@1 1182 int stats_array_size;
duke@1 1183 if (PrintSafepointStatisticsTimeout > 0) {
duke@1 1184 stats_array_size = 1;
duke@1 1185 PrintSafepointStatistics = true;
duke@1 1186 } else {
duke@1 1187 stats_array_size = PrintSafepointStatisticsCount;
duke@1 1188 }
duke@1 1189 _safepoint_stats = (SafepointStats*)os::malloc(stats_array_size
zgu@13195 1190 * sizeof(SafepointStats), mtInternal);
duke@1 1191 guarantee(_safepoint_stats != NULL,
duke@1 1192 "not enough memory for safepoint instrumentation data");
duke@1 1193
shade@27662 1194 if (DeferPollingPageLoopCount >= 0) {
duke@1 1195 need_to_track_page_armed_status = true;
duke@1 1196 }
duke@1 1197 init_done = true;
duke@1 1198 }
duke@1 1199
duke@1 1200 void SafepointSynchronize::begin_statistics(int nof_threads, int nof_running) {
xlu@4006 1201 assert(init_done, "safepoint statistics array hasn't been initialized");
duke@1 1202 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
duke@1 1203
xlu@5042 1204 spstat->_time_stamp = _ts_of_current_safepoint;
xlu@5042 1205
duke@1 1206 VM_Operation *op = VMThread::vm_operation();
duke@1 1207 spstat->_vmop_type = (op != NULL ? op->type() : -1);
duke@1 1208 if (op != NULL) {
duke@1 1209 _safepoint_reasons[spstat->_vmop_type]++;
duke@1 1210 }
duke@1 1211
duke@1 1212 spstat->_nof_total_threads = nof_threads;
duke@1 1213 spstat->_nof_initial_running_threads = nof_running;
duke@1 1214 spstat->_nof_threads_hit_page_trap = 0;
duke@1 1215
duke@1 1216 // Records the start time of spinning. The real time spent on spinning
duke@1 1217 // will be adjusted when spin is done. Same trick is applied for time
duke@1 1218 // spent on waiting for threads to block.
duke@1 1219 if (nof_running != 0) {
duke@1 1220 spstat->_time_to_spin = os::javaTimeNanos();
duke@1 1221 } else {
duke@1 1222 spstat->_time_to_spin = 0;
duke@1 1223 }
duke@1 1224 }
duke@1 1225
duke@1 1226 void SafepointSynchronize::update_statistics_on_spin_end() {
duke@1 1227 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
duke@1 1228
duke@1 1229 jlong cur_time = os::javaTimeNanos();
duke@1 1230
duke@1 1231 spstat->_nof_threads_wait_to_block = _waiting_to_block;
duke@1 1232 if (spstat->_nof_initial_running_threads != 0) {
duke@1 1233 spstat->_time_to_spin = cur_time - spstat->_time_to_spin;
duke@1 1234 }
duke@1 1235
duke@1 1236 if (need_to_track_page_armed_status) {
duke@1 1237 spstat->_page_armed = (PageArmed == 1);
duke@1 1238 }
duke@1 1239
duke@1 1240 // Records the start time of waiting for to block. Updated when block is done.
duke@1 1241 if (_waiting_to_block != 0) {
duke@1 1242 spstat->_time_to_wait_to_block = cur_time;
duke@1 1243 } else {
duke@1 1244 spstat->_time_to_wait_to_block = 0;
duke@1 1245 }
duke@1 1246 }
duke@1 1247
duke@1 1248 void SafepointSynchronize::update_statistics_on_sync_end(jlong end_time) {
duke@1 1249 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
duke@1 1250
duke@1 1251 if (spstat->_nof_threads_wait_to_block != 0) {
duke@1 1252 spstat->_time_to_wait_to_block = end_time -
duke@1 1253 spstat->_time_to_wait_to_block;
duke@1 1254 }
duke@1 1255
duke@1 1256 // Records the end time of sync which will be used to calculate the total
duke@1 1257 // vm operation time. Again, the real time spending in syncing will be deducted
duke@1 1258 // from the start of the sync time later when end_statistics is called.
xlu@5042 1259 spstat->_time_to_sync = end_time - _safepoint_begin_time;
duke@1 1260 if (spstat->_time_to_sync > _max_sync_time) {
duke@1 1261 _max_sync_time = spstat->_time_to_sync;
duke@1 1262 }
xlu@5042 1263
xlu@5042 1264 spstat->_time_to_do_cleanups = end_time;
xlu@5042 1265 }
xlu@5042 1266
xlu@5042 1267 void SafepointSynchronize::update_statistics_on_cleanup_end(jlong end_time) {
xlu@5042 1268 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
xlu@5042 1269
xlu@5042 1270 // Record how long spent in cleanup tasks.
xlu@5042 1271 spstat->_time_to_do_cleanups = end_time - spstat->_time_to_do_cleanups;
xlu@5042 1272
xlu@5042 1273 cleanup_end_time = end_time;
duke@1 1274 }
duke@1 1275
duke@1 1276 void SafepointSynchronize::end_statistics(jlong vmop_end_time) {
duke@1 1277 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
duke@1 1278
duke@1 1279 // Update the vm operation time.
xlu@5042 1280 spstat->_time_to_exec_vmop = vmop_end_time - cleanup_end_time;
xlu@5042 1281 if (spstat->_time_to_exec_vmop > _max_vmop_time) {
xlu@5042 1282 _max_vmop_time = spstat->_time_to_exec_vmop;
xlu@5042 1283 }
duke@1 1284 // Only the sync time longer than the specified
duke@1 1285 // PrintSafepointStatisticsTimeout will be printed out right away.
duke@1 1286 // By default, it is -1 meaning all samples will be put into the list.
duke@1 1287 if ( PrintSafepointStatisticsTimeout > 0) {
gziemski@33222 1288 if (spstat->_time_to_sync > (jlong)PrintSafepointStatisticsTimeout * MICROUNITS) {
duke@1 1289 print_statistics();
duke@1 1290 }
duke@1 1291 } else {
duke@1 1292 // The safepoint statistics will be printed out when the _safepoin_stats
duke@1 1293 // array fills up.
xlu@5042 1294 if (_cur_stat_index == PrintSafepointStatisticsCount - 1) {
duke@1 1295 print_statistics();
duke@1 1296 _cur_stat_index = 0;
xlu@5042 1297 } else {
xlu@5042 1298 _cur_stat_index++;
duke@1 1299 }
duke@1 1300 }
duke@1 1301 }
duke@1 1302
duke@1 1303 void SafepointSynchronize::print_statistics() {
xlu@5042 1304 for (int index = 0; index <= _cur_stat_index; index++) {
xlu@5042 1305 if (index % 30 == 0) {
xlu@5042 1306 print_header();
xlu@5042 1307 }
shade@46473 1308 SafepointStats* sstats = &_safepoint_stats[index];
shade@46473 1309 tty->print("%8.3f: ", sstats->_time_stamp);
shade@46473 1310 tty->print("%-30s [ "
shade@46473 1311 INT32_FORMAT_W(8) " " INT32_FORMAT_W(17) " " INT32_FORMAT_W(13) " "
shade@46473 1312 "]",
shade@46473 1313 (sstats->_vmop_type == -1 ? "no vm operation" : VM_Operation::name(sstats->_vmop_type)),
duke@1 1314 sstats->_nof_total_threads,
duke@1 1315 sstats->_nof_initial_running_threads,
duke@1 1316 sstats->_nof_threads_wait_to_block);
duke@1 1317 // "/ MICROUNITS " is to convert the unit from nanos to millis.
shade@46473 1318 tty->print("[ "
shade@46473 1319 INT64_FORMAT_W(7) " " INT64_FORMAT_W(7) " "
shade@46473 1320 INT64_FORMAT_W(7) " " INT64_FORMAT_W(7) " "
shade@46473 1321 INT64_FORMAT_W(7) " ] ",
jwilhelm@46630 1322 (int64_t)(sstats->_time_to_spin / MICROUNITS),
jwilhelm@46630 1323 (int64_t)(sstats->_time_to_wait_to_block / MICROUNITS),
jwilhelm@46630 1324 (int64_t)(sstats->_time_to_sync / MICROUNITS),
jwilhelm@46630 1325 (int64_t)(sstats->_time_to_do_cleanups / MICROUNITS),
jwilhelm@46630 1326 (int64_t)(sstats->_time_to_exec_vmop / MICROUNITS));
duke@1 1327
duke@1 1328 if (need_to_track_page_armed_status) {
shade@46473 1329 tty->print(INT32_FORMAT_W(10) " ", sstats->_page_armed);
duke@1 1330 }
shade@46473 1331 tty->print_cr(INT32_FORMAT_W(15) " ", sstats->_nof_threads_hit_page_trap);
duke@1 1332 }
duke@1 1333 }
duke@1 1334
duke@1 1335 // This method will be called when VM exits. It will first call
duke@1 1336 // print_statistics to print out the rest of the sampling. Then
duke@1 1337 // it tries to summarize the sampling.
duke@1 1338 void SafepointSynchronize::print_stat_on_exit() {
duke@1 1339 if (_safepoint_stats == NULL) return;
duke@1 1340
duke@1 1341 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
duke@1 1342
duke@1 1343 // During VM exit, end_statistics may not get called and in that
duke@1 1344 // case, if the sync time is less than PrintSafepointStatisticsTimeout,
duke@1 1345 // don't print it out.
duke@1 1346 // Approximate the vm op time.
duke@1 1347 _safepoint_stats[_cur_stat_index]._time_to_exec_vmop =
xlu@5042 1348 os::javaTimeNanos() - cleanup_end_time;
duke@1 1349
duke@1 1350 if ( PrintSafepointStatisticsTimeout < 0 ||
gziemski@33222 1351 spstat->_time_to_sync > (jlong)PrintSafepointStatisticsTimeout * MICROUNITS) {
duke@1 1352 print_statistics();
duke@1 1353 }
drchase@24424 1354 tty->cr();
duke@1 1355
duke@1 1356 // Print out polling page sampling status.
duke@1 1357 if (!need_to_track_page_armed_status) {
shade@27662 1358 tty->print_cr("Polling page always armed");
duke@1 1359 } else {
david@33148 1360 tty->print_cr("Defer polling page loop count = " INTX_FORMAT "\n",
david@33148 1361 DeferPollingPageLoopCount);
duke@1 1362 }
duke@1 1363
duke@1 1364 for (int index = 0; index < VM_Operation::VMOp_Terminating; index++) {
duke@1 1365 if (_safepoint_reasons[index] != 0) {
bpittore@31592 1366 tty->print_cr("%-26s" UINT64_FORMAT_W(10), VM_Operation::name(index),
duke@1 1367 _safepoint_reasons[index]);
duke@1 1368 }
duke@1 1369 }
duke@1 1370
bpittore@31592 1371 tty->print_cr(UINT64_FORMAT_W(5) " VM operations coalesced during safepoint",
duke@1 1372 _coalesced_vmop_count);
bpittore@31592 1373 tty->print_cr("Maximum sync time " INT64_FORMAT_W(5) " ms",
jwilhelm@46630 1374 (int64_t)(_max_sync_time / MICROUNITS));
xlu@5042 1375 tty->print_cr("Maximum vm operation time (except for Exit VM operation) "
bpittore@31592 1376 INT64_FORMAT_W(5) " ms",
jwilhelm@46630 1377 (int64_t)(_max_vmop_time / MICROUNITS));
duke@1 1378 }
duke@1 1379
duke@1 1380 // ------------------------------------------------------------------------------------------------
duke@1 1381 // Non-product code
duke@1 1382
duke@1 1383 #ifndef PRODUCT
duke@1 1384
duke@1 1385 void SafepointSynchronize::print_state() {
duke@1 1386 if (_state == _not_synchronized) {
duke@1 1387 tty->print_cr("not synchronized");
duke@1 1388 } else if (_state == _synchronizing || _state == _synchronized) {
duke@1 1389 tty->print_cr("State: %s", (_state == _synchronizing) ? "synchronizing" :
duke@1 1390 "synchronized");
duke@1 1391
duke@1 1392 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) {
duke@1 1393 cur->safepoint_state()->print();
duke@1 1394 }
duke@1 1395 }
duke@1 1396 }
duke@1 1397
duke@1 1398 void SafepointSynchronize::safepoint_msg(const char* format, ...) {
duke@1 1399 if (ShowSafepointMsgs) {
duke@1 1400 va_list ap;
duke@1 1401 va_start(ap, format);
duke@1 1402 tty->vprint_cr(format, ap);
duke@1 1403 va_end(ap);
duke@1 1404 }
duke@1 1405 }
duke@1 1406
duke@1 1407 #endif // !PRODUCT