annotate src/hotspot/share/runtime/safepoint.cpp @ 47955:69c081ca110a

8184765: Dynamically resize SystemDictionary Summary: Implemented dynamic resizing, which triggers when load factor is too high Reviewed-by: coleenp, rehn
author gziemski
date Thu, 02 Nov 2017 11:00:34 -0500
parents 87141990dde5
children 0ce0ac68ace7
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@47955 26 #include "classfile/classLoaderData.hpp"
gziemski@24426 27 #include "classfile/stringTable.hpp"
mgronlun@34666 28 #include "classfile/symbolTable.hpp"
stefank@7397 29 #include "classfile/systemDictionary.hpp"
stefank@7397 30 #include "code/codeCache.hpp"
stefank@7397 31 #include "code/icBuffer.hpp"
stefank@7397 32 #include "code/nmethod.hpp"
stefank@7397 33 #include "code/pcDesc.hpp"
stefank@7397 34 #include "code/scopeDesc.hpp"
pliden@30764 35 #include "gc/shared/collectedHeap.hpp"
pliden@30764 36 #include "gc/shared/gcLocker.inline.hpp"
rkennke@46702 37 #include "gc/shared/strongRootsScope.hpp"
rkennke@46702 38 #include "gc/shared/workgroup.hpp"
stefank@7397 39 #include "interpreter/interpreter.hpp"
rprotacio@33763 40 #include "logging/log.hpp"
stuefe@46701 41 #include "logging/logStream.hpp"
stefank@7397 42 #include "memory/resourceArea.hpp"
stefank@7397 43 #include "memory/universe.inline.hpp"
stefank@7397 44 #include "oops/oop.inline.hpp"
coleenp@8076 45 #include "oops/symbol.hpp"
dholmes@40655 46 #include "runtime/atomic.hpp"
stefank@7397 47 #include "runtime/compilationPolicy.hpp"
stefank@7397 48 #include "runtime/deoptimization.hpp"
stefank@7397 49 #include "runtime/frame.inline.hpp"
stefank@7397 50 #include "runtime/interfaceSupport.hpp"
stefank@7397 51 #include "runtime/mutexLocker.hpp"
goetz@24351 52 #include "runtime/orderAccess.inline.hpp"
stefank@7397 53 #include "runtime/osThread.hpp"
stefank@7397 54 #include "runtime/safepoint.hpp"
stefank@7397 55 #include "runtime/signature.hpp"
stefank@7397 56 #include "runtime/stubCodeGenerator.hpp"
stefank@7397 57 #include "runtime/stubRoutines.hpp"
stefank@7397 58 #include "runtime/sweeper.hpp"
stefank@7397 59 #include "runtime/synchronizer.hpp"
stefank@14583 60 #include "runtime/thread.inline.hpp"
rehn@37161 61 #include "runtime/timerTrace.hpp"
stefank@7397 62 #include "services/runtimeService.hpp"
dsimms@37176 63 #include "trace/tracing.hpp"
dsimms@37176 64 #include "trace/traceMacros.hpp"
stefank@7397 65 #include "utilities/events.hpp"
jprovino@15482 66 #include "utilities/macros.hpp"
stefank@7397 67 #ifdef COMPILER1
stefank@7397 68 #include "c1/c1_globals.hpp"
stefank@7397 69 #endif
duke@1 70
duke@1 71 // --------------------------------------------------------------------------------------------------
duke@1 72 // Implementation of Safepoint begin/end
duke@1 73
duke@1 74 SafepointSynchronize::SynchronizeState volatile SafepointSynchronize::_state = SafepointSynchronize::_not_synchronized;
duke@1 75 volatile int SafepointSynchronize::_waiting_to_block = 0;
duke@1 76 volatile int SafepointSynchronize::_safepoint_counter = 0;
never@11631 77 int SafepointSynchronize::_current_jni_active_count = 0;
xlu@5042 78 long SafepointSynchronize::_end_of_last_safepoint = 0;
duke@1 79 static volatile int PageArmed = 0 ; // safepoint polling page is RO|RW vs PROT_NONE
duke@1 80 static volatile int TryingToBlock = 0 ; // proximate value -- for advisory use only
duke@1 81 static bool timeout_error_printed = false;
duke@1 82
duke@1 83 // Roll all threads forward to a safepoint and suspend them all
duke@1 84 void SafepointSynchronize::begin() {
dsimms@37176 85 EventSafepointBegin begin_event;
duke@1 86 Thread* myThread = Thread::current();
duke@1 87 assert(myThread->is_VM_thread(), "Only VM thread may execute a safepoint");
duke@1 88
xlu@5042 89 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) {
xlu@5042 90 _safepoint_begin_time = os::javaTimeNanos();
xlu@5042 91 _ts_of_current_safepoint = tty->time_stamp().seconds();
xlu@5042 92 }
duke@1 93
eosterlund@47791 94 Universe::heap()->safepoint_synchronize_begin();
duke@1 95
duke@1 96 // By getting the Threads_lock, we assure that no threads are about to start or
duke@1 97 // exit. It is released again in SafepointSynchronize::end().
duke@1 98 Threads_lock->lock();
duke@1 99
duke@1 100 assert( _state == _not_synchronized, "trying to safepoint synchronize with wrong state");
duke@1 101
duke@1 102 int nof_threads = Threads::number_of_threads();
duke@1 103
rprotacio@33763 104 log_debug(safepoint)("Safepoint synchronization initiated. (%d)", nof_threads);
duke@1 105
duke@1 106 RuntimeService::record_safepoint_begin();
duke@1 107
duke@1 108 MutexLocker mu(Safepoint_lock);
duke@1 109
never@11631 110 // Reset the count of active JNI critical threads
never@11631 111 _current_jni_active_count = 0;
never@11631 112
duke@1 113 // Set number of threads to wait for, before we initiate the callbacks
duke@1 114 _waiting_to_block = nof_threads;
duke@1 115 TryingToBlock = 0 ;
duke@1 116 int still_running = nof_threads;
duke@1 117
duke@1 118 // Save the starting time, so that it can be compared to see if this has taken
duke@1 119 // too long to complete.
goetz@33589 120 jlong safepoint_limit_time = 0;
duke@1 121 timeout_error_printed = false;
duke@1 122
xlu@4006 123 // PrintSafepointStatisticsTimeout can be specified separately. When
xlu@4006 124 // specified, PrintSafepointStatistics will be set to true in
xlu@4006 125 // deferred_initialize_stat method. The initialization has to be done
xlu@4006 126 // early enough to avoid any races. See bug 6880029 for details.
xlu@4006 127 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) {
xlu@4006 128 deferred_initialize_stat();
xlu@4006 129 }
xlu@4006 130
duke@1 131 // Begin the process of bringing the system to a safepoint.
duke@1 132 // Java threads can be in several different states and are
duke@1 133 // stopped by different mechanisms:
duke@1 134 //
duke@1 135 // 1. Running interpreted
jwilhelm@22551 136 // The interpreter dispatch table is changed to force it to
duke@1 137 // check for a safepoint condition between bytecodes.
duke@1 138 // 2. Running in native code
duke@1 139 // When returning from the native code, a Java thread must check
duke@1 140 // the safepoint _state to see if we must block. If the
duke@1 141 // VM thread sees a Java thread in native, it does
duke@1 142 // not wait for this thread to block. The order of the memory
duke@1 143 // writes and reads of both the safepoint state and the Java
duke@1 144 // threads state is critical. In order to guarantee that the
duke@1 145 // memory writes are serialized with respect to each other,
duke@1 146 // the VM thread issues a memory barrier instruction
duke@1 147 // (on MP systems). In order to avoid the overhead of issuing
duke@1 148 // a memory barrier for each Java thread making native calls, each Java
duke@1 149 // thread performs a write to a single memory page after changing
duke@1 150 // the thread state. The VM thread performs a sequence of
duke@1 151 // mprotect OS calls which forces all previous writes from all
duke@1 152 // Java threads to be serialized. This is done in the
duke@1 153 // os::serialize_thread_states() call. This has proven to be
duke@1 154 // much more efficient than executing a membar instruction
duke@1 155 // on every call to native code.
duke@1 156 // 3. Running compiled Code
duke@1 157 // Compiled code reads a global (Safepoint Polling) page that
duke@1 158 // is set to fault if we are trying to get to a safepoint.
duke@1 159 // 4. Blocked
duke@1 160 // A thread which is blocked will not be allowed to return from the
duke@1 161 // block condition until the safepoint operation is complete.
duke@1 162 // 5. In VM or Transitioning between states
duke@1 163 // If a Java thread is currently running in the VM or transitioning
duke@1 164 // between states, the safepointing code will wait for the thread to
duke@1 165 // block itself when it attempts transitions to a new state.
duke@1 166 //
dsimms@37176 167 {
egahlin@40664 168 EventSafepointStateSynchronization sync_event;
dsimms@37176 169 int initial_running = 0;
duke@1 170
dsimms@37176 171 _state = _synchronizing;
dsimms@37176 172 OrderAccess::fence();
duke@1 173
dsimms@37176 174 // Flush all thread states to memory
dsimms@37176 175 if (!UseMembar) {
dsimms@37176 176 os::serialize_thread_states();
dsimms@37176 177 }
duke@1 178
dsimms@37176 179 // Make interpreter safepoint aware
dsimms@37176 180 Interpreter::notice_safepoints();
duke@1 181
dsimms@37176 182 if (DeferPollingPageLoopCount < 0) {
dsimms@37176 183 // Make polling safepoint aware
dsimms@37176 184 guarantee (PageArmed == 0, "invariant") ;
dsimms@37176 185 PageArmed = 1 ;
dsimms@37176 186 os::make_polling_page_unreadable();
dsimms@37176 187 }
dsimms@37176 188
dsimms@37176 189 // Consider using active_processor_count() ... but that call is expensive.
dsimms@37176 190 int ncpus = os::processor_count() ;
duke@1 191
duke@1 192 #ifdef ASSERT
dsimms@37176 193 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) {
dsimms@37176 194 assert(cur->safepoint_state()->is_running(), "Illegal initial state");
dsimms@37176 195 // Clear the visited flag to ensure that the critical counts are collected properly.
dsimms@37176 196 cur->set_visited_for_critical_count(false);
dsimms@37176 197 }
duke@1 198 #endif // ASSERT
duke@1 199
dsimms@37176 200 if (SafepointTimeout)
dsimms@37176 201 safepoint_limit_time = os::javaTimeNanos() + (jlong)SafepointTimeoutDelay * MICROUNITS;
duke@1 202
dsimms@37176 203 // Iterate through all threads until it have been determined how to stop them all at a safepoint
dsimms@37176 204 unsigned int iterations = 0;
dsimms@37176 205 int steps = 0 ;
dsimms@37176 206 while(still_running > 0) {
dsimms@37176 207 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) {
dsimms@37176 208 assert(!cur->is_ConcurrentGC_thread(), "A concurrent GC thread is unexpectly being suspended");
dsimms@37176 209 ThreadSafepointState *cur_state = cur->safepoint_state();
dsimms@37176 210 if (cur_state->is_running()) {
dsimms@37176 211 cur_state->examine_state_of_thread();
dsimms@37176 212 if (!cur_state->is_running()) {
dsimms@37176 213 still_running--;
dsimms@37176 214 // consider adjusting steps downward:
dsimms@37176 215 // steps = 0
dsimms@37176 216 // steps -= NNN
dsimms@37176 217 // steps >>= 1
dsimms@37176 218 // steps = MIN(steps, 2000-100)
dsimms@37176 219 // if (iterations != 0) steps -= NNN
dsimms@37176 220 }
stuefe@46701 221 LogTarget(Trace, safepoint) lt;
stuefe@46701 222 if (lt.is_enabled()) {
dsimms@37176 223 ResourceMark rm;
stuefe@46701 224 LogStream ls(lt);
stuefe@46701 225 cur_state->print_on(&ls);
dsimms@37176 226 }
duke@1 227 }
dsimms@37176 228 }
dsimms@37176 229
dsimms@37176 230 if (iterations == 0) {
dsimms@37176 231 initial_running = still_running;
dsimms@37176 232 if (PrintSafepointStatistics) {
dsimms@37176 233 begin_statistics(nof_threads, still_running);
dsimms@37176 234 }
dsimms@37176 235 }
dsimms@37176 236
dsimms@37176 237 if (still_running > 0) {
dsimms@37176 238 // Check for if it takes to long
dsimms@37176 239 if (SafepointTimeout && safepoint_limit_time < os::javaTimeNanos()) {
dsimms@37176 240 print_safepoint_timeout(_spinning_timeout);
dsimms@37176 241 }
dsimms@37176 242
dsimms@37176 243 // Spin to avoid context switching.
dsimms@37176 244 // There's a tension between allowing the mutators to run (and rendezvous)
dsimms@37176 245 // vs spinning. As the VM thread spins, wasting cycles, it consumes CPU that
dsimms@37176 246 // a mutator might otherwise use profitably to reach a safepoint. Excessive
dsimms@37176 247 // spinning by the VM thread on a saturated system can increase rendezvous latency.
dsimms@37176 248 // Blocking or yielding incur their own penalties in the form of context switching
dsimms@37176 249 // and the resultant loss of $ residency.
dsimms@37176 250 //
dsimms@37176 251 // Further complicating matters is that yield() does not work as naively expected
dsimms@37176 252 // on many platforms -- yield() does not guarantee that any other ready threads
dsimms@37176 253 // will run. As such we revert to naked_short_sleep() after some number of iterations.
dsimms@37176 254 // nakes_short_sleep() is implemented as a short unconditional sleep.
dsimms@37176 255 // Typical operating systems round a "short" sleep period up to 10 msecs, so sleeping
dsimms@37176 256 // can actually increase the time it takes the VM thread to detect that a system-wide
dsimms@37176 257 // stop-the-world safepoint has been reached. In a pathological scenario such as that
dsimms@37176 258 // described in CR6415670 the VMthread may sleep just before the mutator(s) become safe.
dsimms@37176 259 // In that case the mutators will be stalled waiting for the safepoint to complete and the
dsimms@37176 260 // the VMthread will be sleeping, waiting for the mutators to rendezvous. The VMthread
dsimms@37176 261 // will eventually wake up and detect that all mutators are safe, at which point
dsimms@37176 262 // we'll again make progress.
dsimms@37176 263 //
dsimms@37176 264 // Beware too that that the VMThread typically runs at elevated priority.
dsimms@37176 265 // Its default priority is higher than the default mutator priority.
dsimms@37176 266 // Obviously, this complicates spinning.
dsimms@37176 267 //
dsimms@37176 268 // Note too that on Windows XP SwitchThreadTo() has quite different behavior than Sleep(0).
dsimms@37176 269 // Sleep(0) will _not yield to lower priority threads, while SwitchThreadTo() will.
dsimms@37176 270 //
dsimms@37176 271 // See the comments in synchronizer.cpp for additional remarks on spinning.
dsimms@37176 272 //
dsimms@37176 273 // In the future we might:
dsimms@37176 274 // 1. Modify the safepoint scheme to avoid potentially unbounded spinning.
dsimms@37176 275 // This is tricky as the path used by a thread exiting the JVM (say on
dsimms@37176 276 // on JNI call-out) simply stores into its state field. The burden
dsimms@37176 277 // is placed on the VM thread, which must poll (spin).
dsimms@37176 278 // 2. Find something useful to do while spinning. If the safepoint is GC-related
dsimms@37176 279 // we might aggressively scan the stacks of threads that are already safe.
dsimms@37176 280 // 3. Use Solaris schedctl to examine the state of the still-running mutators.
dsimms@37176 281 // If all the mutators are ONPROC there's no reason to sleep or yield.
dsimms@37176 282 // 4. YieldTo() any still-running mutators that are ready but OFFPROC.
dsimms@37176 283 // 5. Check system saturation. If the system is not fully saturated then
dsimms@37176 284 // simply spin and avoid sleep/yield.
dsimms@37176 285 // 6. As still-running mutators rendezvous they could unpark the sleeping
dsimms@37176 286 // VMthread. This works well for still-running mutators that become
dsimms@37176 287 // safe. The VMthread must still poll for mutators that call-out.
dsimms@37176 288 // 7. Drive the policy on time-since-begin instead of iterations.
dsimms@37176 289 // 8. Consider making the spin duration a function of the # of CPUs:
dsimms@37176 290 // Spin = (((ncpus-1) * M) + K) + F(still_running)
dsimms@37176 291 // Alternately, instead of counting iterations of the outer loop
dsimms@37176 292 // we could count the # of threads visited in the inner loop, above.
dsimms@37176 293 // 9. On windows consider using the return value from SwitchThreadTo()
dsimms@37176 294 // to drive subsequent spin/SwitchThreadTo()/Sleep(N) decisions.
dsimms@37176 295
dsimms@37176 296 if (int(iterations) == DeferPollingPageLoopCount) {
dsimms@37176 297 guarantee (PageArmed == 0, "invariant") ;
dsimms@37176 298 PageArmed = 1 ;
dsimms@37176 299 os::make_polling_page_unreadable();
dsimms@37176 300 }
dsimms@37176 301
dsimms@37176 302 // Instead of (ncpus > 1) consider either (still_running < (ncpus + EPSILON)) or
dsimms@37176 303 // ((still_running + _waiting_to_block - TryingToBlock)) < ncpus)
dsimms@37176 304 ++steps ;
dsimms@37176 305 if (ncpus > 1 && steps < SafepointSpinBeforeYield) {
dsimms@37176 306 SpinPause() ; // MP-Polite spin
dsimms@37176 307 } else
dsimms@37176 308 if (steps < DeferThrSuspendLoopCount) {
dsimms@37176 309 os::naked_yield() ;
dsimms@37176 310 } else {
dsimms@37176 311 os::naked_short_sleep(1);
dsimms@37176 312 }
dsimms@37176 313
dsimms@37176 314 iterations ++ ;
dsimms@37176 315 }
dsimms@37176 316 assert(iterations < (uint)max_jint, "We have been iterating in the safepoint loop too long");
dsimms@37176 317 }
dsimms@37176 318 assert(still_running == 0, "sanity check");
dsimms@37176 319
dsimms@37176 320 if (PrintSafepointStatistics) {
dsimms@37176 321 update_statistics_on_spin_end();
dsimms@37176 322 }
dsimms@37176 323
dsimms@37176 324 if (sync_event.should_commit()) {
egahlin@47784 325 // Group this event together with the ones committed after the counter is increased
egahlin@47784 326 sync_event.set_safepointId(safepoint_counter() + 1);
dsimms@37176 327 sync_event.set_initialThreadCount(initial_running);
dsimms@37176 328 sync_event.set_runningThreadCount(_waiting_to_block);
dsimms@37176 329 sync_event.set_iterations(iterations);
dsimms@37176 330 sync_event.commit();
dsimms@37176 331 }
dsimms@37176 332 } //EventSafepointStateSync
dsimms@37176 333
dsimms@37176 334 // wait until all threads are stopped
dsimms@37176 335 {
dsimms@37176 336 EventSafepointWaitBlocked wait_blocked_event;
dsimms@37176 337 int initial_waiting_to_block = _waiting_to_block;
dsimms@37176 338
dsimms@37176 339 while (_waiting_to_block > 0) {
dsimms@37176 340 log_debug(safepoint)("Waiting for %d thread(s) to block", _waiting_to_block);
dsimms@37176 341 if (!SafepointTimeout || timeout_error_printed) {
dsimms@37176 342 Safepoint_lock->wait(true); // true, means with no safepoint checks
dsimms@37176 343 } else {
dsimms@37176 344 // Compute remaining time
dsimms@37176 345 jlong remaining_time = safepoint_limit_time - os::javaTimeNanos();
dsimms@37176 346
dsimms@37176 347 // If there is no remaining time, then there is an error
dsimms@37176 348 if (remaining_time < 0 || Safepoint_lock->wait(true, remaining_time / MICROUNITS)) {
dsimms@37176 349 print_safepoint_timeout(_blocking_timeout);
rprotacio@33763 350 }
duke@1 351 }
duke@1 352 }
dsimms@37176 353 assert(_waiting_to_block == 0, "sanity check");
duke@1 354
dsimms@37176 355 #ifndef PRODUCT
dsimms@37176 356 if (SafepointTimeout) {
dsimms@37176 357 jlong current_time = os::javaTimeNanos();
dsimms@37176 358 if (safepoint_limit_time < current_time) {
dsimms@37176 359 tty->print_cr("# SafepointSynchronize: Finished after "
dsimms@37176 360 INT64_FORMAT_W(6) " ms",
jwilhelm@46630 361 (int64_t)((current_time - safepoint_limit_time) / MICROUNITS +
jwilhelm@46630 362 (jlong)SafepointTimeoutDelay));
duke@1 363 }
duke@1 364 }
duke@1 365 #endif
duke@1 366
dsimms@37176 367 assert((_safepoint_counter & 0x1) == 0, "must be even");
dsimms@37176 368 assert(Threads_lock->owned_by_self(), "must hold Threads_lock");
dsimms@37176 369 _safepoint_counter ++;
duke@1 370
dsimms@37176 371 // Record state
dsimms@37176 372 _state = _synchronized;
duke@1 373
dsimms@37176 374 OrderAccess::fence();
dsimms@37176 375
dsimms@37176 376 if (wait_blocked_event.should_commit()) {
dsimms@37176 377 wait_blocked_event.set_safepointId(safepoint_counter());
dsimms@37176 378 wait_blocked_event.set_runningThreadCount(initial_waiting_to_block);
dsimms@37176 379 wait_blocked_event.commit();
dsimms@37176 380 }
dsimms@37176 381 } // EventSafepointWaitBlocked
duke@1 382
never@12108 383 #ifdef ASSERT
never@12108 384 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) {
never@12108 385 // make sure all the threads were visited
never@12108 386 assert(cur->was_visited_for_critical_count(), "missed a thread");
never@12108 387 }
never@12108 388 #endif // ASSERT
never@12108 389
never@11631 390 // Update the count of active JNI critical regions
david@35492 391 GCLocker::set_jni_lock_count(_current_jni_active_count);
never@11631 392
rprotacio@33763 393 if (log_is_enabled(Debug, safepoint)) {
rehn@46496 394 log_debug(safepoint)("Entering safepoint region: %s", VMThread::vm_safepoint_description());
duke@1 395 }
duke@1 396
duke@1 397 RuntimeService::record_safepoint_synchronized();
duke@1 398 if (PrintSafepointStatistics) {
duke@1 399 update_statistics_on_sync_end(os::javaTimeNanos());
duke@1 400 }
duke@1 401
duke@1 402 // Call stuff that needs to be run when a safepoint is just about to be completed
dsimms@37176 403 {
dsimms@37176 404 EventSafepointCleanup cleanup_event;
dsimms@37176 405 do_cleanup_tasks();
dsimms@37176 406 if (cleanup_event.should_commit()) {
dsimms@37176 407 cleanup_event.set_safepointId(safepoint_counter());
dsimms@37176 408 cleanup_event.commit();
dsimms@37176 409 }
dsimms@37176 410 }
xlu@5042 411
xlu@5042 412 if (PrintSafepointStatistics) {
xlu@5042 413 // Record how much time spend on the above cleanup tasks
xlu@5042 414 update_statistics_on_cleanup_end(os::javaTimeNanos());
xlu@5042 415 }
dsimms@37176 416 if (begin_event.should_commit()) {
dsimms@37176 417 begin_event.set_safepointId(safepoint_counter());
dsimms@37176 418 begin_event.set_totalThreadCount(nof_threads);
dsimms@37176 419 begin_event.set_jniCriticalThreadCount(_current_jni_active_count);
dsimms@37176 420 begin_event.commit();
dsimms@37176 421 }
duke@1 422 }
duke@1 423
duke@1 424 // Wake up all threads, so they are ready to resume execution after the safepoint
duke@1 425 // operation has been carried out
duke@1 426 void SafepointSynchronize::end() {
dsimms@37176 427 EventSafepointEnd event;
dsimms@37176 428 int safepoint_id = safepoint_counter(); // Keep the odd counter as "id"
duke@1 429
duke@1 430 assert(Threads_lock->owned_by_self(), "must hold Threads_lock");
duke@1 431 assert((_safepoint_counter & 0x1) == 1, "must be odd");
duke@1 432 _safepoint_counter ++;
duke@1 433 // memory fence isn't required here since an odd _safepoint_counter
duke@1 434 // value can do no harm and a fence is issued below anyway.
duke@1 435
duke@1 436 DEBUG_ONLY(Thread* myThread = Thread::current();)
duke@1 437 assert(myThread->is_VM_thread(), "Only VM thread can execute a safepoint");
duke@1 438
duke@1 439 if (PrintSafepointStatistics) {
duke@1 440 end_statistics(os::javaTimeNanos());
duke@1 441 }
duke@1 442
duke@1 443 #ifdef ASSERT
duke@1 444 // A pending_exception cannot be installed during a safepoint. The threads
duke@1 445 // may install an async exception after they come back from a safepoint into
duke@1 446 // pending_exception after they unblock. But that should happen later.
duke@1 447 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) {
duke@1 448 assert (!(cur->has_pending_exception() &&
duke@1 449 cur->safepoint_state()->is_at_poll_safepoint()),
duke@1 450 "safepoint installed a pending exception");
duke@1 451 }
duke@1 452 #endif // ASSERT
duke@1 453
duke@1 454 if (PageArmed) {
duke@1 455 // Make polling safepoint aware
duke@1 456 os::make_polling_page_readable();
duke@1 457 PageArmed = 0 ;
duke@1 458 }
duke@1 459
duke@1 460 // Remove safepoint check from interpreter
duke@1 461 Interpreter::ignore_safepoints();
duke@1 462
duke@1 463 {
duke@1 464 MutexLocker mu(Safepoint_lock);
duke@1 465
duke@1 466 assert(_state == _synchronized, "must be synchronized before ending safepoint synchronization");
duke@1 467
duke@1 468 // Set to not synchronized, so the threads will not go into the signal_thread_blocked method
duke@1 469 // when they get restarted.
duke@1 470 _state = _not_synchronized;
duke@1 471 OrderAccess::fence();
duke@1 472
rprotacio@33763 473 log_debug(safepoint)("Leaving safepoint region");
duke@1 474
duke@1 475 // Start suspended threads
duke@1 476 for(JavaThread *current = Threads::first(); current; current = current->next()) {
twisti@2131 477 // A problem occurring on Solaris is when attempting to restart threads
duke@1 478 // the first #cpus - 1 go well, but then the VMThread is preempted when we get
duke@1 479 // to the next one (since it has been running the longest). We then have
duke@1 480 // to wait for a cpu to become available before we can continue restarting
duke@1 481 // threads.
duke@1 482 // FIXME: This causes the performance of the VM to degrade when active and with
duke@1 483 // large numbers of threads. Apparently this is due to the synchronous nature
duke@1 484 // of suspending threads.
duke@1 485 //
duke@1 486 // TODO-FIXME: the comments above are vestigial and no longer apply.
duke@1 487 // Furthermore, using solaris' schedctl in this particular context confers no benefit
duke@1 488 if (VMThreadHintNoPreempt) {
duke@1 489 os::hint_no_preempt();
duke@1 490 }
duke@1 491 ThreadSafepointState* cur_state = current->safepoint_state();
duke@1 492 assert(cur_state->type() != ThreadSafepointState::_running, "Thread not suspended at safepoint");
duke@1 493 cur_state->restart();
duke@1 494 assert(cur_state->is_running(), "safepoint state has not been reset");
duke@1 495 }
duke@1 496
duke@1 497 RuntimeService::record_safepoint_end();
duke@1 498
duke@1 499 // Release threads lock, so threads can be created/destroyed again. It will also starts all threads
duke@1 500 // blocked in signal_thread_blocked
duke@1 501 Threads_lock->unlock();
duke@1 502
duke@1 503 }
eosterlund@47791 504 Universe::heap()->safepoint_synchronize_end();
jwilhelm@22551 505 // record this time so VMThread can keep track how much time has elapsed
xlu@5042 506 // since last safepoint.
xlu@5042 507 _end_of_last_safepoint = os::javaTimeMillis();
dsimms@37176 508
dsimms@37176 509 if (event.should_commit()) {
dsimms@37176 510 event.set_safepointId(safepoint_id);
dsimms@37176 511 event.commit();
dsimms@37176 512 }
duke@1 513 }
duke@1 514
duke@1 515 bool SafepointSynchronize::is_cleanup_needed() {
rehn@46541 516 // Need a safepoint if there are many monitors to deflate.
rehn@46541 517 if (ObjectSynchronizer::is_cleanup_needed()) return true;
duke@1 518 // Need a safepoint if some inline cache buffers is non-empty
duke@1 519 if (!InlineCacheBuffer::is_empty()) return true;
duke@1 520 return false;
duke@1 521 }
duke@1 522
dsimms@37176 523 static void event_safepoint_cleanup_task_commit(EventSafepointCleanupTask& event, const char* name) {
dsimms@37176 524 if (event.should_commit()) {
dsimms@37176 525 event.set_safepointId(SafepointSynchronize::safepoint_counter());
dsimms@37176 526 event.set_name(name);
dsimms@37176 527 event.commit();
dsimms@37176 528 }
dsimms@37176 529 }
duke@1 530
rkennke@46702 531 class ParallelSPCleanupThreadClosure : public ThreadClosure {
rkennke@46702 532 private:
rkennke@46702 533 CodeBlobClosure* _nmethod_cl;
rkennke@46702 534 DeflateMonitorCounters* _counters;
rkennke@46702 535
rkennke@46702 536 public:
rkennke@46702 537 ParallelSPCleanupThreadClosure(DeflateMonitorCounters* counters) :
rkennke@46702 538 _counters(counters),
rkennke@46702 539 _nmethod_cl(NMethodSweeper::prepare_mark_active_nmethods()) {}
rkennke@46702 540
rkennke@46702 541 void do_thread(Thread* thread) {
rkennke@46702 542 ObjectSynchronizer::deflate_thread_local_monitors(thread, _counters);
rkennke@46702 543 if (_nmethod_cl != NULL && thread->is_Java_thread() &&
rkennke@46702 544 ! thread->is_Code_cache_sweeper_thread()) {
rkennke@46702 545 JavaThread* jt = (JavaThread*) thread;
rkennke@46702 546 jt->nmethods_do(_nmethod_cl);
rkennke@46702 547 }
rkennke@46702 548 }
rkennke@46702 549 };
rkennke@46702 550
rkennke@46702 551 class ParallelSPCleanupTask : public AbstractGangTask {
rkennke@46702 552 private:
rkennke@46702 553 SubTasksDone _subtasks;
rkennke@46702 554 ParallelSPCleanupThreadClosure _cleanup_threads_cl;
rkennke@46702 555 uint _num_workers;
rkennke@46702 556 DeflateMonitorCounters* _counters;
rkennke@46702 557 public:
rkennke@46702 558 ParallelSPCleanupTask(uint num_workers, DeflateMonitorCounters* counters) :
rkennke@46702 559 AbstractGangTask("Parallel Safepoint Cleanup"),
rkennke@46702 560 _cleanup_threads_cl(ParallelSPCleanupThreadClosure(counters)),
rkennke@46702 561 _num_workers(num_workers),
rkennke@46702 562 _subtasks(SubTasksDone(SafepointSynchronize::SAFEPOINT_CLEANUP_NUM_TASKS)),
rkennke@46702 563 _counters(counters) {}
rkennke@46702 564
rkennke@46702 565 void work(uint worker_id) {
rkennke@46702 566 // All threads deflate monitors and mark nmethods (if necessary).
rkennke@47792 567 Threads::possibly_parallel_threads_do(true, &_cleanup_threads_cl);
rkennke@46702 568
rkennke@46702 569 if (!_subtasks.is_task_claimed(SafepointSynchronize::SAFEPOINT_CLEANUP_DEFLATE_MONITORS)) {
rkennke@46702 570 const char* name = "deflating idle monitors";
rkennke@46702 571 EventSafepointCleanupTask event;
rkennke@46702 572 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
rkennke@46702 573 ObjectSynchronizer::deflate_idle_monitors(_counters);
rkennke@46702 574 event_safepoint_cleanup_task_commit(event, name);
rkennke@46702 575 }
rkennke@46702 576
rkennke@46702 577 if (!_subtasks.is_task_claimed(SafepointSynchronize::SAFEPOINT_CLEANUP_UPDATE_INLINE_CACHES)) {
rkennke@46702 578 const char* name = "updating inline caches";
rkennke@46702 579 EventSafepointCleanupTask event;
rkennke@46702 580 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
rkennke@46702 581 InlineCacheBuffer::update_inline_caches();
rkennke@46702 582 event_safepoint_cleanup_task_commit(event, name);
rkennke@46702 583 }
rkennke@46702 584
rkennke@46702 585 if (!_subtasks.is_task_claimed(SafepointSynchronize::SAFEPOINT_CLEANUP_COMPILATION_POLICY)) {
rkennke@46702 586 const char* name = "compilation policy safepoint handler";
rkennke@46702 587 EventSafepointCleanupTask event;
rkennke@46702 588 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
rkennke@46702 589 CompilationPolicy::policy()->do_safepoint_work();
rkennke@46702 590 event_safepoint_cleanup_task_commit(event, name);
rkennke@46702 591 }
rkennke@46702 592
rkennke@46702 593 if (!_subtasks.is_task_claimed(SafepointSynchronize::SAFEPOINT_CLEANUP_SYMBOL_TABLE_REHASH)) {
rkennke@46702 594 if (SymbolTable::needs_rehashing()) {
rkennke@46702 595 const char* name = "rehashing symbol table";
rkennke@46702 596 EventSafepointCleanupTask event;
rkennke@46702 597 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
rkennke@46702 598 SymbolTable::rehash_table();
rkennke@46702 599 event_safepoint_cleanup_task_commit(event, name);
rkennke@46702 600 }
rkennke@46702 601 }
rkennke@46702 602
rkennke@46702 603 if (!_subtasks.is_task_claimed(SafepointSynchronize::SAFEPOINT_CLEANUP_STRING_TABLE_REHASH)) {
rkennke@46702 604 if (StringTable::needs_rehashing()) {
rkennke@46702 605 const char* name = "rehashing string table";
rkennke@46702 606 EventSafepointCleanupTask event;
rkennke@46702 607 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
rkennke@46702 608 StringTable::rehash_table();
rkennke@46702 609 event_safepoint_cleanup_task_commit(event, name);
rkennke@46702 610 }
rkennke@46702 611 }
rkennke@46702 612
rkennke@46702 613 if (!_subtasks.is_task_claimed(SafepointSynchronize::SAFEPOINT_CLEANUP_CLD_PURGE)) {
rkennke@46702 614 // CMS delays purging the CLDG until the beginning of the next safepoint and to
rkennke@46702 615 // make sure concurrent sweep is done
rkennke@46702 616 const char* name = "purging class loader data graph";
rkennke@46702 617 EventSafepointCleanupTask event;
rkennke@46702 618 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
rkennke@46702 619 ClassLoaderDataGraph::purge_if_needed();
rkennke@46702 620 event_safepoint_cleanup_task_commit(event, name);
rkennke@46702 621 }
gziemski@47955 622
gziemski@47955 623 if (!_subtasks.is_task_claimed(SafepointSynchronize::SAFEPOINT_CLEANUP_SYSTEM_DICTIONARY_RESIZE)) {
gziemski@47955 624 const char* name = "resizing system dictionaries";
gziemski@47955 625 EventSafepointCleanupTask event;
gziemski@47955 626 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
gziemski@47955 627 ClassLoaderDataGraph::resize_if_needed();
gziemski@47955 628 event_safepoint_cleanup_task_commit(event, name);
gziemski@47955 629 }
rkennke@46702 630 _subtasks.all_tasks_completed(_num_workers);
rkennke@46702 631 }
rkennke@46702 632 };
rkennke@46702 633
rkennke@46702 634 // Various cleaning tasks that should be done periodically at safepoints.
duke@1 635 void SafepointSynchronize::do_cleanup_tasks() {
rkennke@46702 636
rkennke@46702 637 TraceTime timer("safepoint cleanup tasks", TRACETIME_LOG(Info, safepoint, cleanup));
rkennke@46702 638
rkennke@46702 639 // Prepare for monitor deflation.
rkennke@46702 640 DeflateMonitorCounters deflate_counters;
rkennke@46702 641 ObjectSynchronizer::prepare_deflate_idle_monitors(&deflate_counters);
rkennke@46702 642
rkennke@46702 643 CollectedHeap* heap = Universe::heap();
rkennke@46702 644 assert(heap != NULL, "heap not initialized yet?");
rkennke@46702 645 WorkGang* cleanup_workers = heap->get_safepoint_workers();
rkennke@46702 646 if (cleanup_workers != NULL) {
rkennke@46702 647 // Parallel cleanup using GC provided thread pool.
rkennke@46702 648 uint num_cleanup_workers = cleanup_workers->active_workers();
rkennke@46702 649 ParallelSPCleanupTask cleanup(num_cleanup_workers, &deflate_counters);
rkennke@46702 650 StrongRootsScope srs(num_cleanup_workers);
rkennke@46702 651 cleanup_workers->run_task(&cleanup);
rkennke@46702 652 } else {
rkennke@46702 653 // Serial cleanup using VMThread.
rkennke@46702 654 ParallelSPCleanupTask cleanup(1, &deflate_counters);
rkennke@46702 655 StrongRootsScope srs(1);
rkennke@46702 656 cleanup.work(0);
duke@1 657 }
duke@1 658
rkennke@46702 659 // Finish monitor deflation.
rkennke@46702 660 ObjectSynchronizer::finish_deflate_idle_monitors(&deflate_counters);
duke@1 661 }
duke@1 662
duke@1 663
duke@1 664 bool SafepointSynchronize::safepoint_safe(JavaThread *thread, JavaThreadState state) {
duke@1 665 switch(state) {
duke@1 666 case _thread_in_native:
duke@1 667 // native threads are safe if they have no java stack or have walkable stack
duke@1 668 return !thread->has_last_Java_frame() || thread->frame_anchor()->walkable();
duke@1 669
duke@1 670 // blocked threads should have already have walkable stack
duke@1 671 case _thread_blocked:
duke@1 672 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "blocked and not walkable");
duke@1 673 return true;
duke@1 674
duke@1 675 default:
duke@1 676 return false;
duke@1 677 }
duke@1 678 }
duke@1 679
duke@1 680
never@11637 681 // See if the thread is running inside a lazy critical native and
never@11637 682 // update the thread critical count if so. Also set a suspend flag to
never@11637 683 // cause the native wrapper to return into the JVM to do the unlock
never@11637 684 // once the native finishes.
never@11637 685 void SafepointSynchronize::check_for_lazy_critical_native(JavaThread *thread, JavaThreadState state) {
never@11637 686 if (state == _thread_in_native &&
never@11637 687 thread->has_last_Java_frame() &&
never@11637 688 thread->frame_anchor()->walkable()) {
never@11637 689 // This thread might be in a critical native nmethod so look at
never@11637 690 // the top of the stack and increment the critical count if it
never@11637 691 // is.
never@11637 692 frame wrapper_frame = thread->last_frame();
never@11637 693 CodeBlob* stub_cb = wrapper_frame.cb();
never@11637 694 if (stub_cb != NULL &&
never@11637 695 stub_cb->is_nmethod() &&
never@11637 696 stub_cb->as_nmethod_or_null()->is_lazy_critical_native()) {
never@11637 697 // A thread could potentially be in a critical native across
never@11637 698 // more than one safepoint, so only update the critical state on
never@11637 699 // the first one. When it returns it will perform the unlock.
never@11637 700 if (!thread->do_critical_native_unlock()) {
never@11637 701 #ifdef ASSERT
never@11637 702 if (!thread->in_critical()) {
david@35492 703 GCLocker::increment_debug_jni_lock_count();
never@11637 704 }
never@11637 705 #endif
never@11637 706 thread->enter_critical();
never@11637 707 // Make sure the native wrapper calls back on return to
never@11637 708 // perform the needed critical unlock.
never@11637 709 thread->set_critical_native_unlock();
never@11637 710 }
never@11637 711 }
never@11637 712 }
never@11637 713 }
never@11637 714
never@11637 715
never@11637 716
duke@1 717 // -------------------------------------------------------------------------------------------------------
duke@1 718 // Implementation of Safepoint callback point
duke@1 719
duke@1 720 void SafepointSynchronize::block(JavaThread *thread) {
duke@1 721 assert(thread != NULL, "thread must be set");
duke@1 722 assert(thread->is_Java_thread(), "not a Java thread");
duke@1 723
duke@1 724 // Threads shouldn't block if they are in the middle of printing, but...
duke@1 725 ttyLocker::break_tty_lock_for_safepoint(os::current_thread_id());
duke@1 726
duke@1 727 // Only bail from the block() call if the thread is gone from the
duke@1 728 // thread list; starting to exit should still block.
duke@1 729 if (thread->is_terminated()) {
duke@1 730 // block current thread if we come here from native code when VM is gone
duke@1 731 thread->block_if_vm_exited();
duke@1 732
duke@1 733 // otherwise do nothing
duke@1 734 return;
duke@1 735 }
duke@1 736
duke@1 737 JavaThreadState state = thread->thread_state();
duke@1 738 thread->frame_anchor()->make_walkable(thread);
duke@1 739
duke@1 740 // Check that we have a valid thread_state at this point
duke@1 741 switch(state) {
duke@1 742 case _thread_in_vm_trans:
duke@1 743 case _thread_in_Java: // From compiled code
duke@1 744
duke@1 745 // We are highly likely to block on the Safepoint_lock. In order to avoid blocking in this case,
duke@1 746 // we pretend we are still in the VM.
duke@1 747 thread->set_thread_state(_thread_in_vm);
duke@1 748
duke@1 749 if (is_synchronizing()) {
duke@1 750 Atomic::inc (&TryingToBlock) ;
duke@1 751 }
duke@1 752
duke@1 753 // We will always be holding the Safepoint_lock when we are examine the state
duke@1 754 // of a thread. Hence, the instructions between the Safepoint_lock->lock() and
duke@1 755 // Safepoint_lock->unlock() are happening atomic with regards to the safepoint code
duke@1 756 Safepoint_lock->lock_without_safepoint_check();
duke@1 757 if (is_synchronizing()) {
duke@1 758 // Decrement the number of threads to wait for and signal vm thread
duke@1 759 assert(_waiting_to_block > 0, "sanity check");
duke@1 760 _waiting_to_block--;
duke@1 761 thread->safepoint_state()->set_has_called_back(true);
duke@1 762
never@12108 763 DEBUG_ONLY(thread->set_visited_for_critical_count(true));
never@11631 764 if (thread->in_critical()) {
never@11631 765 // Notice that this thread is in a critical section
never@11631 766 increment_jni_active_count();
never@11631 767 }
never@11631 768
duke@1 769 // Consider (_waiting_to_block < 2) to pipeline the wakeup of the VM thread
duke@1 770 if (_waiting_to_block == 0) {
duke@1 771 Safepoint_lock->notify_all();
duke@1 772 }
duke@1 773 }
duke@1 774
duke@1 775 // We transition the thread to state _thread_blocked here, but
duke@1 776 // we can't do our usual check for external suspension and then
duke@1 777 // self-suspend after the lock_without_safepoint_check() call
duke@1 778 // below because we are often called during transitions while
duke@1 779 // we hold different locks. That would leave us suspended while
duke@1 780 // holding a resource which results in deadlocks.
duke@1 781 thread->set_thread_state(_thread_blocked);
duke@1 782 Safepoint_lock->unlock();
duke@1 783
duke@1 784 // We now try to acquire the threads lock. Since this lock is hold by the VM thread during
duke@1 785 // the entire safepoint, the threads will all line up here during the safepoint.
duke@1 786 Threads_lock->lock_without_safepoint_check();
duke@1 787 // restore original state. This is important if the thread comes from compiled code, so it
duke@1 788 // will continue to execute with the _thread_in_Java state.
duke@1 789 thread->set_thread_state(state);
duke@1 790 Threads_lock->unlock();
duke@1 791 break;
duke@1 792
duke@1 793 case _thread_in_native_trans:
duke@1 794 case _thread_blocked_trans:
duke@1 795 case _thread_new_trans:
duke@1 796 if (thread->safepoint_state()->type() == ThreadSafepointState::_call_back) {
duke@1 797 thread->print_thread_state();
duke@1 798 fatal("Deadlock in safepoint code. "
duke@1 799 "Should have called back to the VM before blocking.");
duke@1 800 }
duke@1 801
duke@1 802 // We transition the thread to state _thread_blocked here, but
duke@1 803 // we can't do our usual check for external suspension and then
duke@1 804 // self-suspend after the lock_without_safepoint_check() call
duke@1 805 // below because we are often called during transitions while
duke@1 806 // we hold different locks. That would leave us suspended while
duke@1 807 // holding a resource which results in deadlocks.
duke@1 808 thread->set_thread_state(_thread_blocked);
duke@1 809
duke@1 810 // It is not safe to suspend a thread if we discover it is in _thread_in_native_trans. Hence,
duke@1 811 // the safepoint code might still be waiting for it to block. We need to change the state here,
duke@1 812 // so it can see that it is at a safepoint.
duke@1 813
duke@1 814 // Block until the safepoint operation is completed.
duke@1 815 Threads_lock->lock_without_safepoint_check();
duke@1 816
duke@1 817 // Restore state
duke@1 818 thread->set_thread_state(state);
duke@1 819
duke@1 820 Threads_lock->unlock();
duke@1 821 break;
duke@1 822
duke@1 823 default:
david@33105 824 fatal("Illegal threadstate encountered: %d", state);
duke@1 825 }
duke@1 826
duke@1 827 // Check for pending. async. exceptions or suspends - except if the
duke@1 828 // thread was blocked inside the VM. has_special_runtime_exit_condition()
duke@1 829 // is called last since it grabs a lock and we only want to do that when
duke@1 830 // we must.
duke@1 831 //
duke@1 832 // Note: we never deliver an async exception at a polling point as the
duke@1 833 // compiler may not have an exception handler for it. The polling
duke@1 834 // code will notice the async and deoptimize and the exception will
duke@1 835 // be delivered. (Polling at a return point is ok though). Sure is
duke@1 836 // a lot of bother for a deprecated feature...
duke@1 837 //
duke@1 838 // We don't deliver an async exception if the thread state is
duke@1 839 // _thread_in_native_trans so JNI functions won't be called with
duke@1 840 // a surprising pending exception. If the thread state is going back to java,
duke@1 841 // async exception is checked in check_special_condition_for_native_trans().
duke@1 842
duke@1 843 if (state != _thread_blocked_trans &&
duke@1 844 state != _thread_in_vm_trans &&
duke@1 845 thread->has_special_runtime_exit_condition()) {
duke@1 846 thread->handle_special_runtime_exit_condition(
duke@1 847 !thread->is_at_poll_safepoint() && (state != _thread_in_native_trans));
duke@1 848 }
duke@1 849 }
duke@1 850
duke@1 851 // ------------------------------------------------------------------------------------------------------
duke@1 852 // Exception handlers
duke@1 853
duke@1 854
duke@1 855 void SafepointSynchronize::handle_polling_page_exception(JavaThread *thread) {
duke@1 856 assert(thread->is_Java_thread(), "polling reference encountered by VM thread");
duke@1 857 assert(thread->thread_state() == _thread_in_Java, "should come from Java code");
duke@1 858 assert(SafepointSynchronize::is_synchronizing(), "polling encountered outside safepoint synchronization");
duke@1 859
duke@1 860 if (ShowSafepointMsgs) {
duke@1 861 tty->print("handle_polling_page_exception: ");
duke@1 862 }
duke@1 863
duke@1 864 if (PrintSafepointStatistics) {
duke@1 865 inc_page_trap_count();
duke@1 866 }
duke@1 867
duke@1 868 ThreadSafepointState* state = thread->safepoint_state();
duke@1 869
duke@1 870 state->handle_polling_page_exception();
duke@1 871 }
duke@1 872
duke@1 873
duke@1 874 void SafepointSynchronize::print_safepoint_timeout(SafepointTimeoutReason reason) {
duke@1 875 if (!timeout_error_printed) {
duke@1 876 timeout_error_printed = true;
jwilhelm@22551 877 // Print out the thread info which didn't reach the safepoint for debugging
duke@1 878 // purposes (useful when there are lots of threads in the debugger).
drchase@24424 879 tty->cr();
duke@1 880 tty->print_cr("# SafepointSynchronize::begin: Timeout detected:");
duke@1 881 if (reason == _spinning_timeout) {
duke@1 882 tty->print_cr("# SafepointSynchronize::begin: Timed out while spinning to reach a safepoint.");
duke@1 883 } else if (reason == _blocking_timeout) {
duke@1 884 tty->print_cr("# SafepointSynchronize::begin: Timed out while waiting for threads to stop.");
duke@1 885 }
duke@1 886
duke@1 887 tty->print_cr("# SafepointSynchronize::begin: Threads which did not reach the safepoint:");
duke@1 888 ThreadSafepointState *cur_state;
duke@1 889 ResourceMark rm;
duke@1 890 for(JavaThread *cur_thread = Threads::first(); cur_thread;
duke@1 891 cur_thread = cur_thread->next()) {
duke@1 892 cur_state = cur_thread->safepoint_state();
duke@1 893
duke@1 894 if (cur_thread->thread_state() != _thread_blocked &&
duke@1 895 ((reason == _spinning_timeout && cur_state->is_running()) ||
duke@1 896 (reason == _blocking_timeout && !cur_state->has_called_back()))) {
duke@1 897 tty->print("# ");
duke@1 898 cur_thread->print();
drchase@24424 899 tty->cr();
duke@1 900 }
duke@1 901 }
duke@1 902 tty->print_cr("# SafepointSynchronize::begin: (End of list)");
duke@1 903 }
duke@1 904
duke@1 905 // To debug the long safepoint, specify both DieOnSafepointTimeout &
duke@1 906 // ShowMessageBoxOnError.
duke@1 907 if (DieOnSafepointTimeout) {
david@33105 908 fatal("Safepoint sync time longer than " INTX_FORMAT "ms detected when executing %s.",
rehn@46496 909 SafepointTimeoutDelay, VMThread::vm_safepoint_description());
duke@1 910 }
duke@1 911 }
duke@1 912
duke@1 913
duke@1 914 // -------------------------------------------------------------------------------------------------------
duke@1 915 // Implementation of ThreadSafepointState
duke@1 916
duke@1 917 ThreadSafepointState::ThreadSafepointState(JavaThread *thread) {
duke@1 918 _thread = thread;
duke@1 919 _type = _running;
duke@1 920 _has_called_back = false;
duke@1 921 _at_poll_safepoint = false;
duke@1 922 }
duke@1 923
duke@1 924 void ThreadSafepointState::create(JavaThread *thread) {
duke@1 925 ThreadSafepointState *state = new ThreadSafepointState(thread);
duke@1 926 thread->set_safepoint_state(state);
duke@1 927 }
duke@1 928
duke@1 929 void ThreadSafepointState::destroy(JavaThread *thread) {
duke@1 930 if (thread->safepoint_state()) {
duke@1 931 delete(thread->safepoint_state());
duke@1 932 thread->set_safepoint_state(NULL);
duke@1 933 }
duke@1 934 }
duke@1 935
duke@1 936 void ThreadSafepointState::examine_state_of_thread() {
duke@1 937 assert(is_running(), "better be running or just have hit safepoint poll");
duke@1 938
duke@1 939 JavaThreadState state = _thread->thread_state();
duke@1 940
never@6269 941 // Save the state at the start of safepoint processing.
never@6269 942 _orig_thread_state = state;
never@6269 943
duke@1 944 // Check for a thread that is suspended. Note that thread resume tries
duke@1 945 // to grab the Threads_lock which we own here, so a thread cannot be
duke@1 946 // resumed during safepoint synchronization.
duke@1 947
dcubed@3826 948 // We check to see if this thread is suspended without locking to
dcubed@3826 949 // avoid deadlocking with a third thread that is waiting for this
dcubed@3826 950 // thread to be suspended. The third thread can notice the safepoint
dcubed@3826 951 // that we're trying to start at the beginning of its SR_lock->wait()
dcubed@3826 952 // call. If that happens, then the third thread will block on the
dcubed@3826 953 // safepoint while still holding the underlying SR_lock. We won't be
dcubed@3826 954 // able to get the SR_lock and we'll deadlock.
dcubed@3826 955 //
dcubed@3826 956 // We don't need to grab the SR_lock here for two reasons:
dcubed@3826 957 // 1) The suspend flags are both volatile and are set with an
dcubed@3826 958 // Atomic::cmpxchg() call so we should see the suspended
dcubed@3826 959 // state right away.
dcubed@3826 960 // 2) We're being called from the safepoint polling loop; if
dcubed@3826 961 // we don't see the suspended state on this iteration, then
dcubed@3826 962 // we'll come around again.
dcubed@3826 963 //
dcubed@3826 964 bool is_suspended = _thread->is_ext_suspended();
duke@1 965 if (is_suspended) {
duke@1 966 roll_forward(_at_safepoint);
duke@1 967 return;
duke@1 968 }
duke@1 969
duke@1 970 // Some JavaThread states have an initial safepoint state of
duke@1 971 // running, but are actually at a safepoint. We will happily
duke@1 972 // agree and update the safepoint state here.
duke@1 973 if (SafepointSynchronize::safepoint_safe(_thread, state)) {
never@12108 974 SafepointSynchronize::check_for_lazy_critical_native(_thread, state);
never@11631 975 roll_forward(_at_safepoint);
never@11631 976 return;
duke@1 977 }
duke@1 978
duke@1 979 if (state == _thread_in_vm) {
duke@1 980 roll_forward(_call_back);
duke@1 981 return;
duke@1 982 }
duke@1 983
duke@1 984 // All other thread states will continue to run until they
duke@1 985 // transition and self-block in state _blocked
duke@1 986 // Safepoint polling in compiled code causes the Java threads to do the same.
duke@1 987 // Note: new threads may require a malloc so they must be allowed to finish
duke@1 988
duke@1 989 assert(is_running(), "examine_state_of_thread on non-running thread");
duke@1 990 return;
duke@1 991 }
duke@1 992
duke@1 993 // Returns true is thread could not be rolled forward at present position.
duke@1 994 void ThreadSafepointState::roll_forward(suspend_type type) {
duke@1 995 _type = type;
duke@1 996
duke@1 997 switch(_type) {
duke@1 998 case _at_safepoint:
duke@1 999 SafepointSynchronize::signal_thread_at_safepoint();
never@12108 1000 DEBUG_ONLY(_thread->set_visited_for_critical_count(true));
never@12108 1001 if (_thread->in_critical()) {
never@12108 1002 // Notice that this thread is in a critical section
never@12108 1003 SafepointSynchronize::increment_jni_active_count();
never@12108 1004 }
duke@1 1005 break;
duke@1 1006
duke@1 1007 case _call_back:
duke@1 1008 set_has_called_back(false);
duke@1 1009 break;
duke@1 1010
duke@1 1011 case _running:
duke@1 1012 default:
duke@1 1013 ShouldNotReachHere();
duke@1 1014 }
duke@1 1015 }
duke@1 1016
duke@1 1017 void ThreadSafepointState::restart() {
duke@1 1018 switch(type()) {
duke@1 1019 case _at_safepoint:
duke@1 1020 case _call_back:
duke@1 1021 break;
duke@1 1022
duke@1 1023 case _running:
duke@1 1024 default:
bpittore@31592 1025 tty->print_cr("restart thread " INTPTR_FORMAT " with state %d",
david@33148 1026 p2i(_thread), _type);
duke@1 1027 _thread->print();
duke@1 1028 ShouldNotReachHere();
duke@1 1029 }
duke@1 1030 _type = _running;
duke@1 1031 set_has_called_back(false);
duke@1 1032 }
duke@1 1033
duke@1 1034
duke@1 1035 void ThreadSafepointState::print_on(outputStream *st) const {
goetz@33589 1036 const char *s = NULL;
duke@1 1037
duke@1 1038 switch(_type) {
duke@1 1039 case _running : s = "_running"; break;
duke@1 1040 case _at_safepoint : s = "_at_safepoint"; break;
duke@1 1041 case _call_back : s = "_call_back"; break;
duke@1 1042 default:
duke@1 1043 ShouldNotReachHere();
duke@1 1044 }
duke@1 1045
duke@1 1046 st->print_cr("Thread: " INTPTR_FORMAT
duke@1 1047 " [0x%2x] State: %s _has_called_back %d _at_poll_safepoint %d",
david@33148 1048 p2i(_thread), _thread->osthread()->thread_id(), s, _has_called_back,
duke@1 1049 _at_poll_safepoint);
duke@1 1050
duke@1 1051 _thread->print_thread_state_on(st);
duke@1 1052 }
duke@1 1053
duke@1 1054 // ---------------------------------------------------------------------------------------------------------------------
duke@1 1055
duke@1 1056 // Block the thread at the safepoint poll or poll return.
duke@1 1057 void ThreadSafepointState::handle_polling_page_exception() {
duke@1 1058
duke@1 1059 // Check state. block() will set thread state to thread_in_vm which will
duke@1 1060 // cause the safepoint state _type to become _call_back.
duke@1 1061 assert(type() == ThreadSafepointState::_running,
duke@1 1062 "polling page exception on thread not running state");
duke@1 1063
duke@1 1064 // Step 1: Find the nmethod from the return address
duke@1 1065 if (ShowSafepointMsgs && Verbose) {
david@33148 1066 tty->print_cr("Polling page exception at " INTPTR_FORMAT, p2i(thread()->saved_exception_pc()));
duke@1 1067 }
duke@1 1068 address real_return_addr = thread()->saved_exception_pc();
duke@1 1069
duke@1 1070 CodeBlob *cb = CodeCache::find_blob(real_return_addr);
rbackman@38133 1071 assert(cb != NULL && cb->is_compiled(), "return address should be in nmethod");
rbackman@38133 1072 CompiledMethod* nm = (CompiledMethod*)cb;
duke@1 1073
duke@1 1074 // Find frame of caller
duke@1 1075 frame stub_fr = thread()->last_frame();
duke@1 1076 CodeBlob* stub_cb = stub_fr.cb();
duke@1 1077 assert(stub_cb->is_safepoint_stub(), "must be a safepoint stub");
duke@1 1078 RegisterMap map(thread(), true);
duke@1 1079 frame caller_fr = stub_fr.sender(&map);
duke@1 1080
duke@1 1081 // Should only be poll_return or poll
duke@1 1082 assert( nm->is_at_poll_or_poll_return(real_return_addr), "should not be at call" );
duke@1 1083
duke@1 1084 // This is a poll immediately before a return. The exception handling code
duke@1 1085 // has already had the effect of causing the return to occur, so the execution
duke@1 1086 // will continue immediately after the call. In addition, the oopmap at the
duke@1 1087 // return point does not mark the return value as an oop (if it is), so
duke@1 1088 // it needs a handle here to be updated.
duke@1 1089 if( nm->is_at_poll_return(real_return_addr) ) {
duke@1 1090 // See if return type is an oop.
duke@1 1091 bool return_oop = nm->method()->is_returning_oop();
duke@1 1092 Handle return_value;
duke@1 1093 if (return_oop) {
duke@1 1094 // The oop result has been saved on the stack together with all
duke@1 1095 // the other registers. In order to preserve it over GCs we need
duke@1 1096 // to keep it in a handle.
duke@1 1097 oop result = caller_fr.saved_oop_result(&map);
coleenp@46968 1098 assert(oopDesc::is_oop_or_null(result), "must be oop");
duke@1 1099 return_value = Handle(thread(), result);
duke@1 1100 assert(Universe::heap()->is_in_or_null(result), "must be heap pointer");
duke@1 1101 }
duke@1 1102
duke@1 1103 // Block the thread
duke@1 1104 SafepointSynchronize::block(thread());
duke@1 1105
duke@1 1106 // restore oop result, if any
duke@1 1107 if (return_oop) {
duke@1 1108 caller_fr.set_saved_oop_result(&map, return_value());
duke@1 1109 }
duke@1 1110 }
duke@1 1111
duke@1 1112 // This is a safepoint poll. Verify the return address and block.
duke@1 1113 else {
duke@1 1114 set_at_poll_safepoint(true);
duke@1 1115
duke@1 1116 // verify the blob built the "return address" correctly
duke@1 1117 assert(real_return_addr == caller_fr.pc(), "must match");
duke@1 1118
duke@1 1119 // Block the thread
duke@1 1120 SafepointSynchronize::block(thread());
duke@1 1121 set_at_poll_safepoint(false);
duke@1 1122
duke@1 1123 // If we have a pending async exception deoptimize the frame
duke@1 1124 // as otherwise we may never deliver it.
duke@1 1125 if (thread()->has_async_condition()) {
duke@1 1126 ThreadInVMfromJavaNoAsyncException __tiv(thread());
never@7106 1127 Deoptimization::deoptimize_frame(thread(), caller_fr.id());
duke@1 1128 }
duke@1 1129
duke@1 1130 // If an exception has been installed we must check for a pending deoptimization
duke@1 1131 // Deoptimize frame if exception has been thrown.
duke@1 1132
duke@1 1133 if (thread()->has_pending_exception() ) {
duke@1 1134 RegisterMap map(thread(), true);
duke@1 1135 frame caller_fr = stub_fr.sender(&map);
duke@1 1136 if (caller_fr.is_deoptimized_frame()) {
duke@1 1137 // The exception patch will destroy registers that are still
duke@1 1138 // live and will be needed during deoptimization. Defer the
jwilhelm@22551 1139 // Async exception should have deferred the exception until the
duke@1 1140 // next safepoint which will be detected when we get into
duke@1 1141 // the interpreter so if we have an exception now things
duke@1 1142 // are messed up.
duke@1 1143
duke@1 1144 fatal("Exception installed and deoptimization is pending");
duke@1 1145 }
duke@1 1146 }
duke@1 1147 }
duke@1 1148 }
duke@1 1149
duke@1 1150
duke@1 1151 //
duke@1 1152 // Statistics & Instrumentations
duke@1 1153 //
duke@1 1154 SafepointSynchronize::SafepointStats* SafepointSynchronize::_safepoint_stats = NULL;
xlu@5042 1155 jlong SafepointSynchronize::_safepoint_begin_time = 0;
duke@1 1156 int SafepointSynchronize::_cur_stat_index = 0;
duke@1 1157 julong SafepointSynchronize::_safepoint_reasons[VM_Operation::VMOp_Terminating];
duke@1 1158 julong SafepointSynchronize::_coalesced_vmop_count = 0;
duke@1 1159 jlong SafepointSynchronize::_max_sync_time = 0;
xlu@5042 1160 jlong SafepointSynchronize::_max_vmop_time = 0;
xlu@5042 1161 float SafepointSynchronize::_ts_of_current_safepoint = 0.0f;
duke@1 1162
xlu@5042 1163 static jlong cleanup_end_time = 0;
duke@1 1164 static bool need_to_track_page_armed_status = false;
duke@1 1165 static bool init_done = false;
duke@1 1166
xlu@5042 1167 // Helper method to print the header.
xlu@5042 1168 static void print_header() {
shade@46473 1169 // The number of spaces is significant here, and should match the format
shade@46473 1170 // specifiers in print_statistics().
shade@46473 1171
shade@46473 1172 tty->print(" vmop "
shade@46473 1173 "[ threads: total initially_running wait_to_block ]"
shade@46473 1174 "[ time: spin block sync cleanup vmop ] ");
xlu@5042 1175
xlu@5042 1176 // no page armed status printed out if it is always armed.
xlu@5042 1177 if (need_to_track_page_armed_status) {
xlu@5042 1178 tty->print("page_armed ");
xlu@5042 1179 }
xlu@5042 1180
xlu@5042 1181 tty->print_cr("page_trap_count");
xlu@5042 1182 }
xlu@5042 1183
duke@1 1184 void SafepointSynchronize::deferred_initialize_stat() {
duke@1 1185 if (init_done) return;
duke@1 1186
duke@1 1187 // If PrintSafepointStatisticsTimeout is specified, the statistics data will
duke@1 1188 // be printed right away, in which case, _safepoint_stats will regress to
duke@1 1189 // a single element array. Otherwise, it is a circular ring buffer with default
duke@1 1190 // size of PrintSafepointStatisticsCount.
duke@1 1191 int stats_array_size;
duke@1 1192 if (PrintSafepointStatisticsTimeout > 0) {
duke@1 1193 stats_array_size = 1;
duke@1 1194 PrintSafepointStatistics = true;
duke@1 1195 } else {
duke@1 1196 stats_array_size = PrintSafepointStatisticsCount;
duke@1 1197 }
duke@1 1198 _safepoint_stats = (SafepointStats*)os::malloc(stats_array_size
zgu@13195 1199 * sizeof(SafepointStats), mtInternal);
duke@1 1200 guarantee(_safepoint_stats != NULL,
duke@1 1201 "not enough memory for safepoint instrumentation data");
duke@1 1202
shade@27662 1203 if (DeferPollingPageLoopCount >= 0) {
duke@1 1204 need_to_track_page_armed_status = true;
duke@1 1205 }
duke@1 1206 init_done = true;
duke@1 1207 }
duke@1 1208
duke@1 1209 void SafepointSynchronize::begin_statistics(int nof_threads, int nof_running) {
xlu@4006 1210 assert(init_done, "safepoint statistics array hasn't been initialized");
duke@1 1211 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
duke@1 1212
xlu@5042 1213 spstat->_time_stamp = _ts_of_current_safepoint;
xlu@5042 1214
duke@1 1215 VM_Operation *op = VMThread::vm_operation();
duke@1 1216 spstat->_vmop_type = (op != NULL ? op->type() : -1);
duke@1 1217 if (op != NULL) {
duke@1 1218 _safepoint_reasons[spstat->_vmop_type]++;
duke@1 1219 }
duke@1 1220
duke@1 1221 spstat->_nof_total_threads = nof_threads;
duke@1 1222 spstat->_nof_initial_running_threads = nof_running;
duke@1 1223 spstat->_nof_threads_hit_page_trap = 0;
duke@1 1224
duke@1 1225 // Records the start time of spinning. The real time spent on spinning
duke@1 1226 // will be adjusted when spin is done. Same trick is applied for time
duke@1 1227 // spent on waiting for threads to block.
duke@1 1228 if (nof_running != 0) {
duke@1 1229 spstat->_time_to_spin = os::javaTimeNanos();
duke@1 1230 } else {
duke@1 1231 spstat->_time_to_spin = 0;
duke@1 1232 }
duke@1 1233 }
duke@1 1234
duke@1 1235 void SafepointSynchronize::update_statistics_on_spin_end() {
duke@1 1236 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
duke@1 1237
duke@1 1238 jlong cur_time = os::javaTimeNanos();
duke@1 1239
duke@1 1240 spstat->_nof_threads_wait_to_block = _waiting_to_block;
duke@1 1241 if (spstat->_nof_initial_running_threads != 0) {
duke@1 1242 spstat->_time_to_spin = cur_time - spstat->_time_to_spin;
duke@1 1243 }
duke@1 1244
duke@1 1245 if (need_to_track_page_armed_status) {
duke@1 1246 spstat->_page_armed = (PageArmed == 1);
duke@1 1247 }
duke@1 1248
duke@1 1249 // Records the start time of waiting for to block. Updated when block is done.
duke@1 1250 if (_waiting_to_block != 0) {
duke@1 1251 spstat->_time_to_wait_to_block = cur_time;
duke@1 1252 } else {
duke@1 1253 spstat->_time_to_wait_to_block = 0;
duke@1 1254 }
duke@1 1255 }
duke@1 1256
duke@1 1257 void SafepointSynchronize::update_statistics_on_sync_end(jlong end_time) {
duke@1 1258 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
duke@1 1259
duke@1 1260 if (spstat->_nof_threads_wait_to_block != 0) {
duke@1 1261 spstat->_time_to_wait_to_block = end_time -
duke@1 1262 spstat->_time_to_wait_to_block;
duke@1 1263 }
duke@1 1264
duke@1 1265 // Records the end time of sync which will be used to calculate the total
duke@1 1266 // vm operation time. Again, the real time spending in syncing will be deducted
duke@1 1267 // from the start of the sync time later when end_statistics is called.
xlu@5042 1268 spstat->_time_to_sync = end_time - _safepoint_begin_time;
duke@1 1269 if (spstat->_time_to_sync > _max_sync_time) {
duke@1 1270 _max_sync_time = spstat->_time_to_sync;
duke@1 1271 }
xlu@5042 1272
xlu@5042 1273 spstat->_time_to_do_cleanups = end_time;
xlu@5042 1274 }
xlu@5042 1275
xlu@5042 1276 void SafepointSynchronize::update_statistics_on_cleanup_end(jlong end_time) {
xlu@5042 1277 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
xlu@5042 1278
xlu@5042 1279 // Record how long spent in cleanup tasks.
xlu@5042 1280 spstat->_time_to_do_cleanups = end_time - spstat->_time_to_do_cleanups;
xlu@5042 1281
xlu@5042 1282 cleanup_end_time = end_time;
duke@1 1283 }
duke@1 1284
duke@1 1285 void SafepointSynchronize::end_statistics(jlong vmop_end_time) {
duke@1 1286 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
duke@1 1287
duke@1 1288 // Update the vm operation time.
xlu@5042 1289 spstat->_time_to_exec_vmop = vmop_end_time - cleanup_end_time;
xlu@5042 1290 if (spstat->_time_to_exec_vmop > _max_vmop_time) {
xlu@5042 1291 _max_vmop_time = spstat->_time_to_exec_vmop;
xlu@5042 1292 }
duke@1 1293 // Only the sync time longer than the specified
duke@1 1294 // PrintSafepointStatisticsTimeout will be printed out right away.
duke@1 1295 // By default, it is -1 meaning all samples will be put into the list.
duke@1 1296 if ( PrintSafepointStatisticsTimeout > 0) {
gziemski@33222 1297 if (spstat->_time_to_sync > (jlong)PrintSafepointStatisticsTimeout * MICROUNITS) {
duke@1 1298 print_statistics();
duke@1 1299 }
duke@1 1300 } else {
duke@1 1301 // The safepoint statistics will be printed out when the _safepoin_stats
duke@1 1302 // array fills up.
xlu@5042 1303 if (_cur_stat_index == PrintSafepointStatisticsCount - 1) {
duke@1 1304 print_statistics();
duke@1 1305 _cur_stat_index = 0;
xlu@5042 1306 } else {
xlu@5042 1307 _cur_stat_index++;
duke@1 1308 }
duke@1 1309 }
duke@1 1310 }
duke@1 1311
duke@1 1312 void SafepointSynchronize::print_statistics() {
xlu@5042 1313 for (int index = 0; index <= _cur_stat_index; index++) {
xlu@5042 1314 if (index % 30 == 0) {
xlu@5042 1315 print_header();
xlu@5042 1316 }
shade@46473 1317 SafepointStats* sstats = &_safepoint_stats[index];
shade@46473 1318 tty->print("%8.3f: ", sstats->_time_stamp);
shade@46473 1319 tty->print("%-30s [ "
shade@46473 1320 INT32_FORMAT_W(8) " " INT32_FORMAT_W(17) " " INT32_FORMAT_W(13) " "
shade@46473 1321 "]",
shade@46473 1322 (sstats->_vmop_type == -1 ? "no vm operation" : VM_Operation::name(sstats->_vmop_type)),
duke@1 1323 sstats->_nof_total_threads,
duke@1 1324 sstats->_nof_initial_running_threads,
duke@1 1325 sstats->_nof_threads_wait_to_block);
duke@1 1326 // "/ MICROUNITS " is to convert the unit from nanos to millis.
shade@46473 1327 tty->print("[ "
shade@46473 1328 INT64_FORMAT_W(7) " " INT64_FORMAT_W(7) " "
shade@46473 1329 INT64_FORMAT_W(7) " " INT64_FORMAT_W(7) " "
shade@46473 1330 INT64_FORMAT_W(7) " ] ",
jwilhelm@46630 1331 (int64_t)(sstats->_time_to_spin / MICROUNITS),
jwilhelm@46630 1332 (int64_t)(sstats->_time_to_wait_to_block / MICROUNITS),
jwilhelm@46630 1333 (int64_t)(sstats->_time_to_sync / MICROUNITS),
jwilhelm@46630 1334 (int64_t)(sstats->_time_to_do_cleanups / MICROUNITS),
jwilhelm@46630 1335 (int64_t)(sstats->_time_to_exec_vmop / MICROUNITS));
duke@1 1336
duke@1 1337 if (need_to_track_page_armed_status) {
shade@46473 1338 tty->print(INT32_FORMAT_W(10) " ", sstats->_page_armed);
duke@1 1339 }
shade@46473 1340 tty->print_cr(INT32_FORMAT_W(15) " ", sstats->_nof_threads_hit_page_trap);
duke@1 1341 }
duke@1 1342 }
duke@1 1343
duke@1 1344 // This method will be called when VM exits. It will first call
duke@1 1345 // print_statistics to print out the rest of the sampling. Then
duke@1 1346 // it tries to summarize the sampling.
duke@1 1347 void SafepointSynchronize::print_stat_on_exit() {
duke@1 1348 if (_safepoint_stats == NULL) return;
duke@1 1349
duke@1 1350 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
duke@1 1351
duke@1 1352 // During VM exit, end_statistics may not get called and in that
duke@1 1353 // case, if the sync time is less than PrintSafepointStatisticsTimeout,
duke@1 1354 // don't print it out.
duke@1 1355 // Approximate the vm op time.
duke@1 1356 _safepoint_stats[_cur_stat_index]._time_to_exec_vmop =
xlu@5042 1357 os::javaTimeNanos() - cleanup_end_time;
duke@1 1358
duke@1 1359 if ( PrintSafepointStatisticsTimeout < 0 ||
gziemski@33222 1360 spstat->_time_to_sync > (jlong)PrintSafepointStatisticsTimeout * MICROUNITS) {
duke@1 1361 print_statistics();
duke@1 1362 }
drchase@24424 1363 tty->cr();
duke@1 1364
duke@1 1365 // Print out polling page sampling status.
duke@1 1366 if (!need_to_track_page_armed_status) {
shade@27662 1367 tty->print_cr("Polling page always armed");
duke@1 1368 } else {
david@33148 1369 tty->print_cr("Defer polling page loop count = " INTX_FORMAT "\n",
david@33148 1370 DeferPollingPageLoopCount);
duke@1 1371 }
duke@1 1372
duke@1 1373 for (int index = 0; index < VM_Operation::VMOp_Terminating; index++) {
duke@1 1374 if (_safepoint_reasons[index] != 0) {
bpittore@31592 1375 tty->print_cr("%-26s" UINT64_FORMAT_W(10), VM_Operation::name(index),
duke@1 1376 _safepoint_reasons[index]);
duke@1 1377 }
duke@1 1378 }
duke@1 1379
bpittore@31592 1380 tty->print_cr(UINT64_FORMAT_W(5) " VM operations coalesced during safepoint",
duke@1 1381 _coalesced_vmop_count);
bpittore@31592 1382 tty->print_cr("Maximum sync time " INT64_FORMAT_W(5) " ms",
jwilhelm@46630 1383 (int64_t)(_max_sync_time / MICROUNITS));
xlu@5042 1384 tty->print_cr("Maximum vm operation time (except for Exit VM operation) "
bpittore@31592 1385 INT64_FORMAT_W(5) " ms",
jwilhelm@46630 1386 (int64_t)(_max_vmop_time / MICROUNITS));
duke@1 1387 }
duke@1 1388
duke@1 1389 // ------------------------------------------------------------------------------------------------
duke@1 1390 // Non-product code
duke@1 1391
duke@1 1392 #ifndef PRODUCT
duke@1 1393
duke@1 1394 void SafepointSynchronize::print_state() {
duke@1 1395 if (_state == _not_synchronized) {
duke@1 1396 tty->print_cr("not synchronized");
duke@1 1397 } else if (_state == _synchronizing || _state == _synchronized) {
duke@1 1398 tty->print_cr("State: %s", (_state == _synchronizing) ? "synchronizing" :
duke@1 1399 "synchronized");
duke@1 1400
duke@1 1401 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) {
duke@1 1402 cur->safepoint_state()->print();
duke@1 1403 }
duke@1 1404 }
duke@1 1405 }
duke@1 1406
duke@1 1407 void SafepointSynchronize::safepoint_msg(const char* format, ...) {
duke@1 1408 if (ShowSafepointMsgs) {
duke@1 1409 va_list ap;
duke@1 1410 va_start(ap, format);
duke@1 1411 tty->vprint_cr(format, ap);
duke@1 1412 va_end(ap);
duke@1 1413 }
duke@1 1414 }
duke@1 1415
duke@1 1416 #endif // !PRODUCT