annotate hotspot/src/share/vm/runtime/safepoint.cpp @ 12108:b2ee55606008

7150390: JFR test crashed on assert(_jni_lock_count == count) failed: must be equal Reviewed-by: dholmes, minqi, kvn, coleenp
author never
date Tue, 06 Mar 2012 16:32:23 -0800
parents 030466036615
children 673ea6efaf18
rev   line source
duke@1 1 /*
never@11631 2 * Copyright (c) 1997, 2012, 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"
stefank@7397 26 #include "classfile/systemDictionary.hpp"
stefank@7397 27 #include "code/codeCache.hpp"
stefank@7397 28 #include "code/icBuffer.hpp"
stefank@7397 29 #include "code/nmethod.hpp"
stefank@7397 30 #include "code/pcDesc.hpp"
stefank@7397 31 #include "code/scopeDesc.hpp"
stefank@7397 32 #include "gc_interface/collectedHeap.hpp"
stefank@7397 33 #include "interpreter/interpreter.hpp"
stefank@7397 34 #include "memory/resourceArea.hpp"
stefank@7397 35 #include "memory/universe.inline.hpp"
stefank@7397 36 #include "oops/oop.inline.hpp"
coleenp@8076 37 #include "oops/symbol.hpp"
stefank@7397 38 #include "runtime/compilationPolicy.hpp"
stefank@7397 39 #include "runtime/deoptimization.hpp"
stefank@7397 40 #include "runtime/frame.inline.hpp"
stefank@7397 41 #include "runtime/interfaceSupport.hpp"
stefank@7397 42 #include "runtime/mutexLocker.hpp"
stefank@7397 43 #include "runtime/osThread.hpp"
stefank@7397 44 #include "runtime/safepoint.hpp"
stefank@7397 45 #include "runtime/signature.hpp"
stefank@7397 46 #include "runtime/stubCodeGenerator.hpp"
stefank@7397 47 #include "runtime/stubRoutines.hpp"
stefank@7397 48 #include "runtime/sweeper.hpp"
stefank@7397 49 #include "runtime/synchronizer.hpp"
stefank@7397 50 #include "services/runtimeService.hpp"
stefank@7397 51 #include "utilities/events.hpp"
stefank@7397 52 #ifdef TARGET_ARCH_x86
stefank@7397 53 # include "nativeInst_x86.hpp"
stefank@7397 54 # include "vmreg_x86.inline.hpp"
stefank@7397 55 #endif
stefank@7397 56 #ifdef TARGET_ARCH_sparc
stefank@7397 57 # include "nativeInst_sparc.hpp"
stefank@7397 58 # include "vmreg_sparc.inline.hpp"
stefank@7397 59 #endif
stefank@7397 60 #ifdef TARGET_ARCH_zero
stefank@7397 61 # include "nativeInst_zero.hpp"
stefank@7397 62 # include "vmreg_zero.inline.hpp"
stefank@7397 63 #endif
bobv@8107 64 #ifdef TARGET_ARCH_arm
bobv@8107 65 # include "nativeInst_arm.hpp"
bobv@8107 66 # include "vmreg_arm.inline.hpp"
bobv@8107 67 #endif
bobv@8107 68 #ifdef TARGET_ARCH_ppc
bobv@8107 69 # include "nativeInst_ppc.hpp"
bobv@8107 70 # include "vmreg_ppc.inline.hpp"
bobv@8107 71 #endif
stefank@7397 72 #ifdef TARGET_OS_FAMILY_linux
stefank@7397 73 # include "thread_linux.inline.hpp"
stefank@7397 74 #endif
stefank@7397 75 #ifdef TARGET_OS_FAMILY_solaris
stefank@7397 76 # include "thread_solaris.inline.hpp"
stefank@7397 77 #endif
stefank@7397 78 #ifdef TARGET_OS_FAMILY_windows
stefank@7397 79 # include "thread_windows.inline.hpp"
stefank@7397 80 #endif
never@10565 81 #ifdef TARGET_OS_FAMILY_bsd
never@10565 82 # include "thread_bsd.inline.hpp"
never@10565 83 #endif
stefank@7397 84 #ifndef SERIALGC
stefank@7397 85 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
stefank@7397 86 #include "gc_implementation/shared/concurrentGCThread.hpp"
stefank@7397 87 #endif
stefank@7397 88 #ifdef COMPILER1
stefank@7397 89 #include "c1/c1_globals.hpp"
stefank@7397 90 #endif
duke@1 91
duke@1 92 // --------------------------------------------------------------------------------------------------
duke@1 93 // Implementation of Safepoint begin/end
duke@1 94
duke@1 95 SafepointSynchronize::SynchronizeState volatile SafepointSynchronize::_state = SafepointSynchronize::_not_synchronized;
duke@1 96 volatile int SafepointSynchronize::_waiting_to_block = 0;
duke@1 97 volatile int SafepointSynchronize::_safepoint_counter = 0;
never@11631 98 int SafepointSynchronize::_current_jni_active_count = 0;
xlu@5042 99 long SafepointSynchronize::_end_of_last_safepoint = 0;
duke@1 100 static volatile int PageArmed = 0 ; // safepoint polling page is RO|RW vs PROT_NONE
duke@1 101 static volatile int TryingToBlock = 0 ; // proximate value -- for advisory use only
duke@1 102 static bool timeout_error_printed = false;
duke@1 103
duke@1 104 // Roll all threads forward to a safepoint and suspend them all
duke@1 105 void SafepointSynchronize::begin() {
duke@1 106
duke@1 107 Thread* myThread = Thread::current();
duke@1 108 assert(myThread->is_VM_thread(), "Only VM thread may execute a safepoint");
duke@1 109
xlu@5042 110 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) {
xlu@5042 111 _safepoint_begin_time = os::javaTimeNanos();
xlu@5042 112 _ts_of_current_safepoint = tty->time_stamp().seconds();
xlu@5042 113 }
duke@1 114
duke@1 115 #ifndef SERIALGC
duke@1 116 if (UseConcMarkSweepGC) {
duke@1 117 // In the future we should investigate whether CMS can use the
duke@1 118 // more-general mechanism below. DLD (01/05).
duke@1 119 ConcurrentMarkSweepThread::synchronize(false);
ysr@3262 120 } else if (UseG1GC) {
duke@1 121 ConcurrentGCThread::safepoint_synchronize();
duke@1 122 }
duke@1 123 #endif // SERIALGC
duke@1 124
duke@1 125 // By getting the Threads_lock, we assure that no threads are about to start or
duke@1 126 // exit. It is released again in SafepointSynchronize::end().
duke@1 127 Threads_lock->lock();
duke@1 128
duke@1 129 assert( _state == _not_synchronized, "trying to safepoint synchronize with wrong state");
duke@1 130
duke@1 131 int nof_threads = Threads::number_of_threads();
duke@1 132
duke@1 133 if (TraceSafepoint) {
duke@1 134 tty->print_cr("Safepoint synchronization initiated. (%d)", nof_threads);
duke@1 135 }
duke@1 136
duke@1 137 RuntimeService::record_safepoint_begin();
duke@1 138
duke@1 139 MutexLocker mu(Safepoint_lock);
duke@1 140
never@11631 141 // Reset the count of active JNI critical threads
never@11631 142 _current_jni_active_count = 0;
never@11631 143
duke@1 144 // Set number of threads to wait for, before we initiate the callbacks
duke@1 145 _waiting_to_block = nof_threads;
duke@1 146 TryingToBlock = 0 ;
duke@1 147 int still_running = nof_threads;
duke@1 148
duke@1 149 // Save the starting time, so that it can be compared to see if this has taken
duke@1 150 // too long to complete.
duke@1 151 jlong safepoint_limit_time;
duke@1 152 timeout_error_printed = false;
duke@1 153
xlu@4006 154 // PrintSafepointStatisticsTimeout can be specified separately. When
xlu@4006 155 // specified, PrintSafepointStatistics will be set to true in
xlu@4006 156 // deferred_initialize_stat method. The initialization has to be done
xlu@4006 157 // early enough to avoid any races. See bug 6880029 for details.
xlu@4006 158 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) {
xlu@4006 159 deferred_initialize_stat();
xlu@4006 160 }
xlu@4006 161
duke@1 162 // Begin the process of bringing the system to a safepoint.
duke@1 163 // Java threads can be in several different states and are
duke@1 164 // stopped by different mechanisms:
duke@1 165 //
duke@1 166 // 1. Running interpreted
duke@1 167 // The interpeter dispatch table is changed to force it to
duke@1 168 // check for a safepoint condition between bytecodes.
duke@1 169 // 2. Running in native code
duke@1 170 // When returning from the native code, a Java thread must check
duke@1 171 // the safepoint _state to see if we must block. If the
duke@1 172 // VM thread sees a Java thread in native, it does
duke@1 173 // not wait for this thread to block. The order of the memory
duke@1 174 // writes and reads of both the safepoint state and the Java
duke@1 175 // threads state is critical. In order to guarantee that the
duke@1 176 // memory writes are serialized with respect to each other,
duke@1 177 // the VM thread issues a memory barrier instruction
duke@1 178 // (on MP systems). In order to avoid the overhead of issuing
duke@1 179 // a memory barrier for each Java thread making native calls, each Java
duke@1 180 // thread performs a write to a single memory page after changing
duke@1 181 // the thread state. The VM thread performs a sequence of
duke@1 182 // mprotect OS calls which forces all previous writes from all
duke@1 183 // Java threads to be serialized. This is done in the
duke@1 184 // os::serialize_thread_states() call. This has proven to be
duke@1 185 // much more efficient than executing a membar instruction
duke@1 186 // on every call to native code.
duke@1 187 // 3. Running compiled Code
duke@1 188 // Compiled code reads a global (Safepoint Polling) page that
duke@1 189 // is set to fault if we are trying to get to a safepoint.
duke@1 190 // 4. Blocked
duke@1 191 // A thread which is blocked will not be allowed to return from the
duke@1 192 // block condition until the safepoint operation is complete.
duke@1 193 // 5. In VM or Transitioning between states
duke@1 194 // If a Java thread is currently running in the VM or transitioning
duke@1 195 // between states, the safepointing code will wait for the thread to
duke@1 196 // block itself when it attempts transitions to a new state.
duke@1 197 //
duke@1 198 _state = _synchronizing;
duke@1 199 OrderAccess::fence();
duke@1 200
duke@1 201 // Flush all thread states to memory
duke@1 202 if (!UseMembar) {
duke@1 203 os::serialize_thread_states();
duke@1 204 }
duke@1 205
duke@1 206 // Make interpreter safepoint aware
duke@1 207 Interpreter::notice_safepoints();
duke@1 208
duke@1 209 if (UseCompilerSafepoints && DeferPollingPageLoopCount < 0) {
duke@1 210 // Make polling safepoint aware
duke@1 211 guarantee (PageArmed == 0, "invariant") ;
duke@1 212 PageArmed = 1 ;
duke@1 213 os::make_polling_page_unreadable();
duke@1 214 }
duke@1 215
duke@1 216 // Consider using active_processor_count() ... but that call is expensive.
duke@1 217 int ncpus = os::processor_count() ;
duke@1 218
duke@1 219 #ifdef ASSERT
duke@1 220 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) {
duke@1 221 assert(cur->safepoint_state()->is_running(), "Illegal initial state");
never@12108 222 // Clear the visited flag to ensure that the critical counts are collected properly.
never@12108 223 cur->set_visited_for_critical_count(false);
duke@1 224 }
duke@1 225 #endif // ASSERT
duke@1 226
duke@1 227 if (SafepointTimeout)
duke@1 228 safepoint_limit_time = os::javaTimeNanos() + (jlong)SafepointTimeoutDelay * MICROUNITS;
duke@1 229
duke@1 230 // Iterate through all threads until it have been determined how to stop them all at a safepoint
duke@1 231 unsigned int iterations = 0;
duke@1 232 int steps = 0 ;
duke@1 233 while(still_running > 0) {
duke@1 234 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) {
duke@1 235 assert(!cur->is_ConcurrentGC_thread(), "A concurrent GC thread is unexpectly being suspended");
duke@1 236 ThreadSafepointState *cur_state = cur->safepoint_state();
duke@1 237 if (cur_state->is_running()) {
duke@1 238 cur_state->examine_state_of_thread();
duke@1 239 if (!cur_state->is_running()) {
duke@1 240 still_running--;
duke@1 241 // consider adjusting steps downward:
duke@1 242 // steps = 0
duke@1 243 // steps -= NNN
duke@1 244 // steps >>= 1
duke@1 245 // steps = MIN(steps, 2000-100)
duke@1 246 // if (iterations != 0) steps -= NNN
duke@1 247 }
duke@1 248 if (TraceSafepoint && Verbose) cur_state->print();
duke@1 249 }
duke@1 250 }
duke@1 251
xlu@4006 252 if (PrintSafepointStatistics && iterations == 0) {
duke@1 253 begin_statistics(nof_threads, still_running);
duke@1 254 }
duke@1 255
duke@1 256 if (still_running > 0) {
duke@1 257 // Check for if it takes to long
duke@1 258 if (SafepointTimeout && safepoint_limit_time < os::javaTimeNanos()) {
duke@1 259 print_safepoint_timeout(_spinning_timeout);
duke@1 260 }
duke@1 261
duke@1 262 // Spin to avoid context switching.
duke@1 263 // There's a tension between allowing the mutators to run (and rendezvous)
duke@1 264 // vs spinning. As the VM thread spins, wasting cycles, it consumes CPU that
duke@1 265 // a mutator might otherwise use profitably to reach a safepoint. Excessive
duke@1 266 // spinning by the VM thread on a saturated system can increase rendezvous latency.
duke@1 267 // Blocking or yielding incur their own penalties in the form of context switching
duke@1 268 // and the resultant loss of $ residency.
duke@1 269 //
duke@1 270 // Further complicating matters is that yield() does not work as naively expected
duke@1 271 // on many platforms -- yield() does not guarantee that any other ready threads
duke@1 272 // will run. As such we revert yield_all() after some number of iterations.
duke@1 273 // Yield_all() is implemented as a short unconditional sleep on some platforms.
duke@1 274 // Typical operating systems round a "short" sleep period up to 10 msecs, so sleeping
duke@1 275 // can actually increase the time it takes the VM thread to detect that a system-wide
duke@1 276 // stop-the-world safepoint has been reached. In a pathological scenario such as that
duke@1 277 // described in CR6415670 the VMthread may sleep just before the mutator(s) become safe.
duke@1 278 // In that case the mutators will be stalled waiting for the safepoint to complete and the
duke@1 279 // the VMthread will be sleeping, waiting for the mutators to rendezvous. The VMthread
duke@1 280 // will eventually wake up and detect that all mutators are safe, at which point
duke@1 281 // we'll again make progress.
duke@1 282 //
duke@1 283 // Beware too that that the VMThread typically runs at elevated priority.
duke@1 284 // Its default priority is higher than the default mutator priority.
duke@1 285 // Obviously, this complicates spinning.
duke@1 286 //
duke@1 287 // Note too that on Windows XP SwitchThreadTo() has quite different behavior than Sleep(0).
duke@1 288 // Sleep(0) will _not yield to lower priority threads, while SwitchThreadTo() will.
duke@1 289 //
duke@1 290 // See the comments in synchronizer.cpp for additional remarks on spinning.
duke@1 291 //
duke@1 292 // In the future we might:
duke@1 293 // 1. Modify the safepoint scheme to avoid potentally unbounded spinning.
duke@1 294 // This is tricky as the path used by a thread exiting the JVM (say on
duke@1 295 // on JNI call-out) simply stores into its state field. The burden
duke@1 296 // is placed on the VM thread, which must poll (spin).
duke@1 297 // 2. Find something useful to do while spinning. If the safepoint is GC-related
duke@1 298 // we might aggressively scan the stacks of threads that are already safe.
duke@1 299 // 3. Use Solaris schedctl to examine the state of the still-running mutators.
duke@1 300 // If all the mutators are ONPROC there's no reason to sleep or yield.
duke@1 301 // 4. YieldTo() any still-running mutators that are ready but OFFPROC.
duke@1 302 // 5. Check system saturation. If the system is not fully saturated then
duke@1 303 // simply spin and avoid sleep/yield.
duke@1 304 // 6. As still-running mutators rendezvous they could unpark the sleeping
duke@1 305 // VMthread. This works well for still-running mutators that become
duke@1 306 // safe. The VMthread must still poll for mutators that call-out.
duke@1 307 // 7. Drive the policy on time-since-begin instead of iterations.
duke@1 308 // 8. Consider making the spin duration a function of the # of CPUs:
duke@1 309 // Spin = (((ncpus-1) * M) + K) + F(still_running)
duke@1 310 // Alternately, instead of counting iterations of the outer loop
duke@1 311 // we could count the # of threads visited in the inner loop, above.
duke@1 312 // 9. On windows consider using the return value from SwitchThreadTo()
duke@1 313 // to drive subsequent spin/SwitchThreadTo()/Sleep(N) decisions.
duke@1 314
duke@1 315 if (UseCompilerSafepoints && int(iterations) == DeferPollingPageLoopCount) {
duke@1 316 guarantee (PageArmed == 0, "invariant") ;
duke@1 317 PageArmed = 1 ;
duke@1 318 os::make_polling_page_unreadable();
duke@1 319 }
duke@1 320
duke@1 321 // Instead of (ncpus > 1) consider either (still_running < (ncpus + EPSILON)) or
duke@1 322 // ((still_running + _waiting_to_block - TryingToBlock)) < ncpus)
duke@1 323 ++steps ;
duke@1 324 if (ncpus > 1 && steps < SafepointSpinBeforeYield) {
duke@1 325 SpinPause() ; // MP-Polite spin
duke@1 326 } else
duke@1 327 if (steps < DeferThrSuspendLoopCount) {
duke@1 328 os::NakedYield() ;
duke@1 329 } else {
duke@1 330 os::yield_all(steps) ;
duke@1 331 // Alternately, the VM thread could transiently depress its scheduling priority or
duke@1 332 // transiently increase the priority of the tardy mutator(s).
duke@1 333 }
duke@1 334
duke@1 335 iterations ++ ;
duke@1 336 }
duke@1 337 assert(iterations < (uint)max_jint, "We have been iterating in the safepoint loop too long");
duke@1 338 }
duke@1 339 assert(still_running == 0, "sanity check");
duke@1 340
duke@1 341 if (PrintSafepointStatistics) {
duke@1 342 update_statistics_on_spin_end();
duke@1 343 }
duke@1 344
duke@1 345 // wait until all threads are stopped
duke@1 346 while (_waiting_to_block > 0) {
duke@1 347 if (TraceSafepoint) tty->print_cr("Waiting for %d thread(s) to block", _waiting_to_block);
duke@1 348 if (!SafepointTimeout || timeout_error_printed) {
duke@1 349 Safepoint_lock->wait(true); // true, means with no safepoint checks
duke@1 350 } else {
duke@1 351 // Compute remaining time
duke@1 352 jlong remaining_time = safepoint_limit_time - os::javaTimeNanos();
duke@1 353
duke@1 354 // If there is no remaining time, then there is an error
duke@1 355 if (remaining_time < 0 || Safepoint_lock->wait(true, remaining_time / MICROUNITS)) {
duke@1 356 print_safepoint_timeout(_blocking_timeout);
duke@1 357 }
duke@1 358 }
duke@1 359 }
duke@1 360 assert(_waiting_to_block == 0, "sanity check");
duke@1 361
duke@1 362 #ifndef PRODUCT
duke@1 363 if (SafepointTimeout) {
duke@1 364 jlong current_time = os::javaTimeNanos();
duke@1 365 if (safepoint_limit_time < current_time) {
duke@1 366 tty->print_cr("# SafepointSynchronize: Finished after "
duke@1 367 INT64_FORMAT_W(6) " ms",
duke@1 368 ((current_time - safepoint_limit_time) / MICROUNITS +
duke@1 369 SafepointTimeoutDelay));
duke@1 370 }
duke@1 371 }
duke@1 372 #endif
duke@1 373
duke@1 374 assert((_safepoint_counter & 0x1) == 0, "must be even");
duke@1 375 assert(Threads_lock->owned_by_self(), "must hold Threads_lock");
duke@1 376 _safepoint_counter ++;
duke@1 377
duke@1 378 // Record state
duke@1 379 _state = _synchronized;
duke@1 380
duke@1 381 OrderAccess::fence();
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
never@11631 391 GC_locker::set_jni_lock_count(_current_jni_active_count);
never@11631 392
duke@1 393 if (TraceSafepoint) {
duke@1 394 VM_Operation *op = VMThread::vm_operation();
duke@1 395 tty->print_cr("Entering safepoint region: %s", (op != NULL) ? op->name() : "no vm operation");
duke@1 396 }
duke@1 397
duke@1 398 RuntimeService::record_safepoint_synchronized();
duke@1 399 if (PrintSafepointStatistics) {
duke@1 400 update_statistics_on_sync_end(os::javaTimeNanos());
duke@1 401 }
duke@1 402
duke@1 403 // Call stuff that needs to be run when a safepoint is just about to be completed
duke@1 404 do_cleanup_tasks();
xlu@5042 405
xlu@5042 406 if (PrintSafepointStatistics) {
xlu@5042 407 // Record how much time spend on the above cleanup tasks
xlu@5042 408 update_statistics_on_cleanup_end(os::javaTimeNanos());
xlu@5042 409 }
duke@1 410 }
duke@1 411
duke@1 412 // Wake up all threads, so they are ready to resume execution after the safepoint
duke@1 413 // operation has been carried out
duke@1 414 void SafepointSynchronize::end() {
duke@1 415
duke@1 416 assert(Threads_lock->owned_by_self(), "must hold Threads_lock");
duke@1 417 assert((_safepoint_counter & 0x1) == 1, "must be odd");
duke@1 418 _safepoint_counter ++;
duke@1 419 // memory fence isn't required here since an odd _safepoint_counter
duke@1 420 // value can do no harm and a fence is issued below anyway.
duke@1 421
duke@1 422 DEBUG_ONLY(Thread* myThread = Thread::current();)
duke@1 423 assert(myThread->is_VM_thread(), "Only VM thread can execute a safepoint");
duke@1 424
duke@1 425 if (PrintSafepointStatistics) {
duke@1 426 end_statistics(os::javaTimeNanos());
duke@1 427 }
duke@1 428
duke@1 429 #ifdef ASSERT
duke@1 430 // A pending_exception cannot be installed during a safepoint. The threads
duke@1 431 // may install an async exception after they come back from a safepoint into
duke@1 432 // pending_exception after they unblock. But that should happen later.
duke@1 433 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) {
duke@1 434 assert (!(cur->has_pending_exception() &&
duke@1 435 cur->safepoint_state()->is_at_poll_safepoint()),
duke@1 436 "safepoint installed a pending exception");
duke@1 437 }
duke@1 438 #endif // ASSERT
duke@1 439
duke@1 440 if (PageArmed) {
duke@1 441 // Make polling safepoint aware
duke@1 442 os::make_polling_page_readable();
duke@1 443 PageArmed = 0 ;
duke@1 444 }
duke@1 445
duke@1 446 // Remove safepoint check from interpreter
duke@1 447 Interpreter::ignore_safepoints();
duke@1 448
duke@1 449 {
duke@1 450 MutexLocker mu(Safepoint_lock);
duke@1 451
duke@1 452 assert(_state == _synchronized, "must be synchronized before ending safepoint synchronization");
duke@1 453
duke@1 454 // Set to not synchronized, so the threads will not go into the signal_thread_blocked method
duke@1 455 // when they get restarted.
duke@1 456 _state = _not_synchronized;
duke@1 457 OrderAccess::fence();
duke@1 458
duke@1 459 if (TraceSafepoint) {
duke@1 460 tty->print_cr("Leaving safepoint region");
duke@1 461 }
duke@1 462
duke@1 463 // Start suspended threads
duke@1 464 for(JavaThread *current = Threads::first(); current; current = current->next()) {
twisti@2131 465 // A problem occurring on Solaris is when attempting to restart threads
duke@1 466 // the first #cpus - 1 go well, but then the VMThread is preempted when we get
duke@1 467 // to the next one (since it has been running the longest). We then have
duke@1 468 // to wait for a cpu to become available before we can continue restarting
duke@1 469 // threads.
duke@1 470 // FIXME: This causes the performance of the VM to degrade when active and with
duke@1 471 // large numbers of threads. Apparently this is due to the synchronous nature
duke@1 472 // of suspending threads.
duke@1 473 //
duke@1 474 // TODO-FIXME: the comments above are vestigial and no longer apply.
duke@1 475 // Furthermore, using solaris' schedctl in this particular context confers no benefit
duke@1 476 if (VMThreadHintNoPreempt) {
duke@1 477 os::hint_no_preempt();
duke@1 478 }
duke@1 479 ThreadSafepointState* cur_state = current->safepoint_state();
duke@1 480 assert(cur_state->type() != ThreadSafepointState::_running, "Thread not suspended at safepoint");
duke@1 481 cur_state->restart();
duke@1 482 assert(cur_state->is_running(), "safepoint state has not been reset");
duke@1 483 }
duke@1 484
duke@1 485 RuntimeService::record_safepoint_end();
duke@1 486
duke@1 487 // Release threads lock, so threads can be created/destroyed again. It will also starts all threads
duke@1 488 // blocked in signal_thread_blocked
duke@1 489 Threads_lock->unlock();
duke@1 490
duke@1 491 }
duke@1 492 #ifndef SERIALGC
duke@1 493 // If there are any concurrent GC threads resume them.
duke@1 494 if (UseConcMarkSweepGC) {
duke@1 495 ConcurrentMarkSweepThread::desynchronize(false);
ysr@3262 496 } else if (UseG1GC) {
duke@1 497 ConcurrentGCThread::safepoint_desynchronize();
duke@1 498 }
duke@1 499 #endif // SERIALGC
xlu@5042 500 // record this time so VMThread can keep track how much time has elasped
xlu@5042 501 // since last safepoint.
xlu@5042 502 _end_of_last_safepoint = os::javaTimeMillis();
duke@1 503 }
duke@1 504
duke@1 505 bool SafepointSynchronize::is_cleanup_needed() {
duke@1 506 // Need a safepoint if some inline cache buffers is non-empty
duke@1 507 if (!InlineCacheBuffer::is_empty()) return true;
duke@1 508 return false;
duke@1 509 }
duke@1 510
duke@1 511
duke@1 512
duke@1 513 // Various cleaning tasks that should be done periodically at safepoints
duke@1 514 void SafepointSynchronize::do_cleanup_tasks() {
xlu@5042 515 {
xlu@5086 516 TraceTime t1("deflating idle monitors", TraceSafepointCleanupTime);
xlu@5042 517 ObjectSynchronizer::deflate_idle_monitors();
duke@1 518 }
duke@1 519
xlu@5042 520 {
xlu@5086 521 TraceTime t2("updating inline caches", TraceSafepointCleanupTime);
xlu@5042 522 InlineCacheBuffer::update_inline_caches();
xlu@5042 523 }
iveresov@6453 524 {
iveresov@6453 525 TraceTime t3("compilation policy safepoint handler", TraceSafepointCleanupTime);
iveresov@6453 526 CompilationPolicy::policy()->do_safepoint_work();
duke@1 527 }
xlu@5042 528
xlu@5086 529 TraceTime t4("sweeping nmethods", TraceSafepointCleanupTime);
never@5533 530 NMethodSweeper::scan_stacks();
minqi@9990 531
minqi@9990 532 // rotate log files?
minqi@9990 533 if (UseGCLogFileRotation) {
minqi@9990 534 gclog_or_tty->rotate_log();
minqi@9990 535 }
duke@1 536 }
duke@1 537
duke@1 538
duke@1 539 bool SafepointSynchronize::safepoint_safe(JavaThread *thread, JavaThreadState state) {
duke@1 540 switch(state) {
duke@1 541 case _thread_in_native:
duke@1 542 // native threads are safe if they have no java stack or have walkable stack
duke@1 543 return !thread->has_last_Java_frame() || thread->frame_anchor()->walkable();
duke@1 544
duke@1 545 // blocked threads should have already have walkable stack
duke@1 546 case _thread_blocked:
duke@1 547 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "blocked and not walkable");
duke@1 548 return true;
duke@1 549
duke@1 550 default:
duke@1 551 return false;
duke@1 552 }
duke@1 553 }
duke@1 554
duke@1 555
never@11637 556 // See if the thread is running inside a lazy critical native and
never@11637 557 // update the thread critical count if so. Also set a suspend flag to
never@11637 558 // cause the native wrapper to return into the JVM to do the unlock
never@11637 559 // once the native finishes.
never@11637 560 void SafepointSynchronize::check_for_lazy_critical_native(JavaThread *thread, JavaThreadState state) {
never@11637 561 if (state == _thread_in_native &&
never@11637 562 thread->has_last_Java_frame() &&
never@11637 563 thread->frame_anchor()->walkable()) {
never@11637 564 // This thread might be in a critical native nmethod so look at
never@11637 565 // the top of the stack and increment the critical count if it
never@11637 566 // is.
never@11637 567 frame wrapper_frame = thread->last_frame();
never@11637 568 CodeBlob* stub_cb = wrapper_frame.cb();
never@11637 569 if (stub_cb != NULL &&
never@11637 570 stub_cb->is_nmethod() &&
never@11637 571 stub_cb->as_nmethod_or_null()->is_lazy_critical_native()) {
never@11637 572 // A thread could potentially be in a critical native across
never@11637 573 // more than one safepoint, so only update the critical state on
never@11637 574 // the first one. When it returns it will perform the unlock.
never@11637 575 if (!thread->do_critical_native_unlock()) {
never@11637 576 #ifdef ASSERT
never@11637 577 if (!thread->in_critical()) {
never@11637 578 GC_locker::increment_debug_jni_lock_count();
never@11637 579 }
never@11637 580 #endif
never@11637 581 thread->enter_critical();
never@11637 582 // Make sure the native wrapper calls back on return to
never@11637 583 // perform the needed critical unlock.
never@11637 584 thread->set_critical_native_unlock();
never@11637 585 }
never@11637 586 }
never@11637 587 }
never@11637 588 }
never@11637 589
never@11637 590
never@11637 591
duke@1 592 // -------------------------------------------------------------------------------------------------------
duke@1 593 // Implementation of Safepoint callback point
duke@1 594
duke@1 595 void SafepointSynchronize::block(JavaThread *thread) {
duke@1 596 assert(thread != NULL, "thread must be set");
duke@1 597 assert(thread->is_Java_thread(), "not a Java thread");
duke@1 598
duke@1 599 // Threads shouldn't block if they are in the middle of printing, but...
duke@1 600 ttyLocker::break_tty_lock_for_safepoint(os::current_thread_id());
duke@1 601
duke@1 602 // Only bail from the block() call if the thread is gone from the
duke@1 603 // thread list; starting to exit should still block.
duke@1 604 if (thread->is_terminated()) {
duke@1 605 // block current thread if we come here from native code when VM is gone
duke@1 606 thread->block_if_vm_exited();
duke@1 607
duke@1 608 // otherwise do nothing
duke@1 609 return;
duke@1 610 }
duke@1 611
duke@1 612 JavaThreadState state = thread->thread_state();
duke@1 613 thread->frame_anchor()->make_walkable(thread);
duke@1 614
duke@1 615 // Check that we have a valid thread_state at this point
duke@1 616 switch(state) {
duke@1 617 case _thread_in_vm_trans:
duke@1 618 case _thread_in_Java: // From compiled code
duke@1 619
duke@1 620 // We are highly likely to block on the Safepoint_lock. In order to avoid blocking in this case,
duke@1 621 // we pretend we are still in the VM.
duke@1 622 thread->set_thread_state(_thread_in_vm);
duke@1 623
duke@1 624 if (is_synchronizing()) {
duke@1 625 Atomic::inc (&TryingToBlock) ;
duke@1 626 }
duke@1 627
duke@1 628 // We will always be holding the Safepoint_lock when we are examine the state
duke@1 629 // of a thread. Hence, the instructions between the Safepoint_lock->lock() and
duke@1 630 // Safepoint_lock->unlock() are happening atomic with regards to the safepoint code
duke@1 631 Safepoint_lock->lock_without_safepoint_check();
duke@1 632 if (is_synchronizing()) {
duke@1 633 // Decrement the number of threads to wait for and signal vm thread
duke@1 634 assert(_waiting_to_block > 0, "sanity check");
duke@1 635 _waiting_to_block--;
duke@1 636 thread->safepoint_state()->set_has_called_back(true);
duke@1 637
never@12108 638 DEBUG_ONLY(thread->set_visited_for_critical_count(true));
never@11631 639 if (thread->in_critical()) {
never@11631 640 // Notice that this thread is in a critical section
never@11631 641 increment_jni_active_count();
never@11631 642 }
never@11631 643
duke@1 644 // Consider (_waiting_to_block < 2) to pipeline the wakeup of the VM thread
duke@1 645 if (_waiting_to_block == 0) {
duke@1 646 Safepoint_lock->notify_all();
duke@1 647 }
duke@1 648 }
duke@1 649
duke@1 650 // We transition the thread to state _thread_blocked here, but
duke@1 651 // we can't do our usual check for external suspension and then
duke@1 652 // self-suspend after the lock_without_safepoint_check() call
duke@1 653 // below because we are often called during transitions while
duke@1 654 // we hold different locks. That would leave us suspended while
duke@1 655 // holding a resource which results in deadlocks.
duke@1 656 thread->set_thread_state(_thread_blocked);
duke@1 657 Safepoint_lock->unlock();
duke@1 658
duke@1 659 // We now try to acquire the threads lock. Since this lock is hold by the VM thread during
duke@1 660 // the entire safepoint, the threads will all line up here during the safepoint.
duke@1 661 Threads_lock->lock_without_safepoint_check();
duke@1 662 // restore original state. This is important if the thread comes from compiled code, so it
duke@1 663 // will continue to execute with the _thread_in_Java state.
duke@1 664 thread->set_thread_state(state);
duke@1 665 Threads_lock->unlock();
duke@1 666 break;
duke@1 667
duke@1 668 case _thread_in_native_trans:
duke@1 669 case _thread_blocked_trans:
duke@1 670 case _thread_new_trans:
duke@1 671 if (thread->safepoint_state()->type() == ThreadSafepointState::_call_back) {
duke@1 672 thread->print_thread_state();
duke@1 673 fatal("Deadlock in safepoint code. "
duke@1 674 "Should have called back to the VM before blocking.");
duke@1 675 }
duke@1 676
duke@1 677 // We transition the thread to state _thread_blocked here, but
duke@1 678 // we can't do our usual check for external suspension and then
duke@1 679 // self-suspend after the lock_without_safepoint_check() call
duke@1 680 // below because we are often called during transitions while
duke@1 681 // we hold different locks. That would leave us suspended while
duke@1 682 // holding a resource which results in deadlocks.
duke@1 683 thread->set_thread_state(_thread_blocked);
duke@1 684
duke@1 685 // It is not safe to suspend a thread if we discover it is in _thread_in_native_trans. Hence,
duke@1 686 // the safepoint code might still be waiting for it to block. We need to change the state here,
duke@1 687 // so it can see that it is at a safepoint.
duke@1 688
duke@1 689 // Block until the safepoint operation is completed.
duke@1 690 Threads_lock->lock_without_safepoint_check();
duke@1 691
duke@1 692 // Restore state
duke@1 693 thread->set_thread_state(state);
duke@1 694
duke@1 695 Threads_lock->unlock();
duke@1 696 break;
duke@1 697
duke@1 698 default:
jcoomes@5403 699 fatal(err_msg("Illegal threadstate encountered: %d", state));
duke@1 700 }
duke@1 701
duke@1 702 // Check for pending. async. exceptions or suspends - except if the
duke@1 703 // thread was blocked inside the VM. has_special_runtime_exit_condition()
duke@1 704 // is called last since it grabs a lock and we only want to do that when
duke@1 705 // we must.
duke@1 706 //
duke@1 707 // Note: we never deliver an async exception at a polling point as the
duke@1 708 // compiler may not have an exception handler for it. The polling
duke@1 709 // code will notice the async and deoptimize and the exception will
duke@1 710 // be delivered. (Polling at a return point is ok though). Sure is
duke@1 711 // a lot of bother for a deprecated feature...
duke@1 712 //
duke@1 713 // We don't deliver an async exception if the thread state is
duke@1 714 // _thread_in_native_trans so JNI functions won't be called with
duke@1 715 // a surprising pending exception. If the thread state is going back to java,
duke@1 716 // async exception is checked in check_special_condition_for_native_trans().
duke@1 717
duke@1 718 if (state != _thread_blocked_trans &&
duke@1 719 state != _thread_in_vm_trans &&
duke@1 720 thread->has_special_runtime_exit_condition()) {
duke@1 721 thread->handle_special_runtime_exit_condition(
duke@1 722 !thread->is_at_poll_safepoint() && (state != _thread_in_native_trans));
duke@1 723 }
duke@1 724 }
duke@1 725
duke@1 726 // ------------------------------------------------------------------------------------------------------
duke@1 727 // Exception handlers
duke@1 728
duke@1 729 #ifndef PRODUCT
duke@1 730 #ifdef _LP64
duke@1 731 #define PTR_PAD ""
duke@1 732 #else
duke@1 733 #define PTR_PAD " "
duke@1 734 #endif
duke@1 735
duke@1 736 static void print_ptrs(intptr_t oldptr, intptr_t newptr, bool wasoop) {
duke@1 737 bool is_oop = newptr ? ((oop)newptr)->is_oop() : false;
duke@1 738 tty->print_cr(PTR_FORMAT PTR_PAD " %s %c " PTR_FORMAT PTR_PAD " %s %s",
duke@1 739 oldptr, wasoop?"oop":" ", oldptr == newptr ? ' ' : '!',
duke@1 740 newptr, is_oop?"oop":" ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":" "));
duke@1 741 }
duke@1 742
duke@1 743 static void print_longs(jlong oldptr, jlong newptr, bool wasoop) {
duke@1 744 bool is_oop = newptr ? ((oop)(intptr_t)newptr)->is_oop() : false;
duke@1 745 tty->print_cr(PTR64_FORMAT " %s %c " PTR64_FORMAT " %s %s",
duke@1 746 oldptr, wasoop?"oop":" ", oldptr == newptr ? ' ' : '!',
duke@1 747 newptr, is_oop?"oop":" ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":" "));
duke@1 748 }
duke@1 749
duke@1 750 #ifdef SPARC
duke@1 751 static void print_me(intptr_t *new_sp, intptr_t *old_sp, bool *was_oops) {
duke@1 752 #ifdef _LP64
duke@1 753 tty->print_cr("--------+------address-----+------before-----------+-------after----------+");
duke@1 754 const int incr = 1; // Increment to skip a long, in units of intptr_t
duke@1 755 #else
duke@1 756 tty->print_cr("--------+--address-+------before-----------+-------after----------+");
duke@1 757 const int incr = 2; // Increment to skip a long, in units of intptr_t
duke@1 758 #endif
duke@1 759 tty->print_cr("---SP---|");
duke@1 760 for( int i=0; i<16; i++ ) {
duke@1 761 tty->print("blob %c%d |"PTR_FORMAT" ","LO"[i>>3],i&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); }
duke@1 762 tty->print_cr("--------|");
duke@1 763 for( int i1=0; i1<frame::memory_parameter_word_sp_offset-16; i1++ ) {
duke@1 764 tty->print("argv pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); }
duke@1 765 tty->print(" pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++);
duke@1 766 tty->print_cr("--------|");
duke@1 767 tty->print(" G1 |"PTR_FORMAT" ",new_sp); print_longs(*(jlong*)old_sp,*(jlong*)new_sp,was_oops[incr-1]); old_sp += incr; new_sp += incr; was_oops += incr;
duke@1 768 tty->print(" G3 |"PTR_FORMAT" ",new_sp); print_longs(*(jlong*)old_sp,*(jlong*)new_sp,was_oops[incr-1]); old_sp += incr; new_sp += incr; was_oops += incr;
duke@1 769 tty->print(" G4 |"PTR_FORMAT" ",new_sp); print_longs(*(jlong*)old_sp,*(jlong*)new_sp,was_oops[incr-1]); old_sp += incr; new_sp += incr; was_oops += incr;
duke@1 770 tty->print(" G5 |"PTR_FORMAT" ",new_sp); print_longs(*(jlong*)old_sp,*(jlong*)new_sp,was_oops[incr-1]); old_sp += incr; new_sp += incr; was_oops += incr;
duke@1 771 tty->print_cr(" FSR |"PTR_FORMAT" "PTR64_FORMAT" "PTR64_FORMAT,new_sp,*(jlong*)old_sp,*(jlong*)new_sp);
duke@1 772 old_sp += incr; new_sp += incr; was_oops += incr;
duke@1 773 // Skip the floats
duke@1 774 tty->print_cr("--Float-|"PTR_FORMAT,new_sp);
duke@1 775 tty->print_cr("---FP---|");
duke@1 776 old_sp += incr*32; new_sp += incr*32; was_oops += incr*32;
duke@1 777 for( int i2=0; i2<16; i2++ ) {
duke@1 778 tty->print("call %c%d |"PTR_FORMAT" ","LI"[i2>>3],i2&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); }
duke@1 779 tty->print_cr("");
duke@1 780 }
duke@1 781 #endif // SPARC
duke@1 782 #endif // PRODUCT
duke@1 783
duke@1 784
duke@1 785 void SafepointSynchronize::handle_polling_page_exception(JavaThread *thread) {
duke@1 786 assert(thread->is_Java_thread(), "polling reference encountered by VM thread");
duke@1 787 assert(thread->thread_state() == _thread_in_Java, "should come from Java code");
duke@1 788 assert(SafepointSynchronize::is_synchronizing(), "polling encountered outside safepoint synchronization");
duke@1 789
duke@1 790 // Uncomment this to get some serious before/after printing of the
duke@1 791 // Sparc safepoint-blob frame structure.
duke@1 792 /*
duke@1 793 intptr_t* sp = thread->last_Java_sp();
duke@1 794 intptr_t stack_copy[150];
duke@1 795 for( int i=0; i<150; i++ ) stack_copy[i] = sp[i];
duke@1 796 bool was_oops[150];
duke@1 797 for( int i=0; i<150; i++ )
duke@1 798 was_oops[i] = stack_copy[i] ? ((oop)stack_copy[i])->is_oop() : false;
duke@1 799 */
duke@1 800
duke@1 801 if (ShowSafepointMsgs) {
duke@1 802 tty->print("handle_polling_page_exception: ");
duke@1 803 }
duke@1 804
duke@1 805 if (PrintSafepointStatistics) {
duke@1 806 inc_page_trap_count();
duke@1 807 }
duke@1 808
duke@1 809 ThreadSafepointState* state = thread->safepoint_state();
duke@1 810
duke@1 811 state->handle_polling_page_exception();
duke@1 812 // print_me(sp,stack_copy,was_oops);
duke@1 813 }
duke@1 814
duke@1 815
duke@1 816 void SafepointSynchronize::print_safepoint_timeout(SafepointTimeoutReason reason) {
duke@1 817 if (!timeout_error_printed) {
duke@1 818 timeout_error_printed = true;
duke@1 819 // Print out the thread infor which didn't reach the safepoint for debugging
duke@1 820 // purposes (useful when there are lots of threads in the debugger).
duke@1 821 tty->print_cr("");
duke@1 822 tty->print_cr("# SafepointSynchronize::begin: Timeout detected:");
duke@1 823 if (reason == _spinning_timeout) {
duke@1 824 tty->print_cr("# SafepointSynchronize::begin: Timed out while spinning to reach a safepoint.");
duke@1 825 } else if (reason == _blocking_timeout) {
duke@1 826 tty->print_cr("# SafepointSynchronize::begin: Timed out while waiting for threads to stop.");
duke@1 827 }
duke@1 828
duke@1 829 tty->print_cr("# SafepointSynchronize::begin: Threads which did not reach the safepoint:");
duke@1 830 ThreadSafepointState *cur_state;
duke@1 831 ResourceMark rm;
duke@1 832 for(JavaThread *cur_thread = Threads::first(); cur_thread;
duke@1 833 cur_thread = cur_thread->next()) {
duke@1 834 cur_state = cur_thread->safepoint_state();
duke@1 835
duke@1 836 if (cur_thread->thread_state() != _thread_blocked &&
duke@1 837 ((reason == _spinning_timeout && cur_state->is_running()) ||
duke@1 838 (reason == _blocking_timeout && !cur_state->has_called_back()))) {
duke@1 839 tty->print("# ");
duke@1 840 cur_thread->print();
duke@1 841 tty->print_cr("");
duke@1 842 }
duke@1 843 }
duke@1 844 tty->print_cr("# SafepointSynchronize::begin: (End of list)");
duke@1 845 }
duke@1 846
duke@1 847 // To debug the long safepoint, specify both DieOnSafepointTimeout &
duke@1 848 // ShowMessageBoxOnError.
duke@1 849 if (DieOnSafepointTimeout) {
duke@1 850 char msg[1024];
duke@1 851 VM_Operation *op = VMThread::vm_operation();
xlu@1889 852 sprintf(msg, "Safepoint sync time longer than " INTX_FORMAT "ms detected when executing %s.",
duke@1 853 SafepointTimeoutDelay,
duke@1 854 op != NULL ? op->name() : "no vm operation");
duke@1 855 fatal(msg);
duke@1 856 }
duke@1 857 }
duke@1 858
duke@1 859
duke@1 860 // -------------------------------------------------------------------------------------------------------
duke@1 861 // Implementation of ThreadSafepointState
duke@1 862
duke@1 863 ThreadSafepointState::ThreadSafepointState(JavaThread *thread) {
duke@1 864 _thread = thread;
duke@1 865 _type = _running;
duke@1 866 _has_called_back = false;
duke@1 867 _at_poll_safepoint = false;
duke@1 868 }
duke@1 869
duke@1 870 void ThreadSafepointState::create(JavaThread *thread) {
duke@1 871 ThreadSafepointState *state = new ThreadSafepointState(thread);
duke@1 872 thread->set_safepoint_state(state);
duke@1 873 }
duke@1 874
duke@1 875 void ThreadSafepointState::destroy(JavaThread *thread) {
duke@1 876 if (thread->safepoint_state()) {
duke@1 877 delete(thread->safepoint_state());
duke@1 878 thread->set_safepoint_state(NULL);
duke@1 879 }
duke@1 880 }
duke@1 881
duke@1 882 void ThreadSafepointState::examine_state_of_thread() {
duke@1 883 assert(is_running(), "better be running or just have hit safepoint poll");
duke@1 884
duke@1 885 JavaThreadState state = _thread->thread_state();
duke@1 886
never@6269 887 // Save the state at the start of safepoint processing.
never@6269 888 _orig_thread_state = state;
never@6269 889
duke@1 890 // Check for a thread that is suspended. Note that thread resume tries
duke@1 891 // to grab the Threads_lock which we own here, so a thread cannot be
duke@1 892 // resumed during safepoint synchronization.
duke@1 893
dcubed@3826 894 // We check to see if this thread is suspended without locking to
dcubed@3826 895 // avoid deadlocking with a third thread that is waiting for this
dcubed@3826 896 // thread to be suspended. The third thread can notice the safepoint
dcubed@3826 897 // that we're trying to start at the beginning of its SR_lock->wait()
dcubed@3826 898 // call. If that happens, then the third thread will block on the
dcubed@3826 899 // safepoint while still holding the underlying SR_lock. We won't be
dcubed@3826 900 // able to get the SR_lock and we'll deadlock.
dcubed@3826 901 //
dcubed@3826 902 // We don't need to grab the SR_lock here for two reasons:
dcubed@3826 903 // 1) The suspend flags are both volatile and are set with an
dcubed@3826 904 // Atomic::cmpxchg() call so we should see the suspended
dcubed@3826 905 // state right away.
dcubed@3826 906 // 2) We're being called from the safepoint polling loop; if
dcubed@3826 907 // we don't see the suspended state on this iteration, then
dcubed@3826 908 // we'll come around again.
dcubed@3826 909 //
dcubed@3826 910 bool is_suspended = _thread->is_ext_suspended();
duke@1 911 if (is_suspended) {
duke@1 912 roll_forward(_at_safepoint);
duke@1 913 return;
duke@1 914 }
duke@1 915
duke@1 916 // Some JavaThread states have an initial safepoint state of
duke@1 917 // running, but are actually at a safepoint. We will happily
duke@1 918 // agree and update the safepoint state here.
duke@1 919 if (SafepointSynchronize::safepoint_safe(_thread, state)) {
never@12108 920 SafepointSynchronize::check_for_lazy_critical_native(_thread, state);
never@11631 921 roll_forward(_at_safepoint);
never@11631 922 return;
duke@1 923 }
duke@1 924
duke@1 925 if (state == _thread_in_vm) {
duke@1 926 roll_forward(_call_back);
duke@1 927 return;
duke@1 928 }
duke@1 929
duke@1 930 // All other thread states will continue to run until they
duke@1 931 // transition and self-block in state _blocked
duke@1 932 // Safepoint polling in compiled code causes the Java threads to do the same.
duke@1 933 // Note: new threads may require a malloc so they must be allowed to finish
duke@1 934
duke@1 935 assert(is_running(), "examine_state_of_thread on non-running thread");
duke@1 936 return;
duke@1 937 }
duke@1 938
duke@1 939 // Returns true is thread could not be rolled forward at present position.
duke@1 940 void ThreadSafepointState::roll_forward(suspend_type type) {
duke@1 941 _type = type;
duke@1 942
duke@1 943 switch(_type) {
duke@1 944 case _at_safepoint:
duke@1 945 SafepointSynchronize::signal_thread_at_safepoint();
never@12108 946 DEBUG_ONLY(_thread->set_visited_for_critical_count(true));
never@12108 947 if (_thread->in_critical()) {
never@12108 948 // Notice that this thread is in a critical section
never@12108 949 SafepointSynchronize::increment_jni_active_count();
never@12108 950 }
duke@1 951 break;
duke@1 952
duke@1 953 case _call_back:
duke@1 954 set_has_called_back(false);
duke@1 955 break;
duke@1 956
duke@1 957 case _running:
duke@1 958 default:
duke@1 959 ShouldNotReachHere();
duke@1 960 }
duke@1 961 }
duke@1 962
duke@1 963 void ThreadSafepointState::restart() {
duke@1 964 switch(type()) {
duke@1 965 case _at_safepoint:
duke@1 966 case _call_back:
duke@1 967 break;
duke@1 968
duke@1 969 case _running:
duke@1 970 default:
duke@1 971 tty->print_cr("restart thread "INTPTR_FORMAT" with state %d",
duke@1 972 _thread, _type);
duke@1 973 _thread->print();
duke@1 974 ShouldNotReachHere();
duke@1 975 }
duke@1 976 _type = _running;
duke@1 977 set_has_called_back(false);
duke@1 978 }
duke@1 979
duke@1 980
duke@1 981 void ThreadSafepointState::print_on(outputStream *st) const {
duke@1 982 const char *s;
duke@1 983
duke@1 984 switch(_type) {
duke@1 985 case _running : s = "_running"; break;
duke@1 986 case _at_safepoint : s = "_at_safepoint"; break;
duke@1 987 case _call_back : s = "_call_back"; break;
duke@1 988 default:
duke@1 989 ShouldNotReachHere();
duke@1 990 }
duke@1 991
duke@1 992 st->print_cr("Thread: " INTPTR_FORMAT
duke@1 993 " [0x%2x] State: %s _has_called_back %d _at_poll_safepoint %d",
duke@1 994 _thread, _thread->osthread()->thread_id(), s, _has_called_back,
duke@1 995 _at_poll_safepoint);
duke@1 996
duke@1 997 _thread->print_thread_state_on(st);
duke@1 998 }
duke@1 999
duke@1 1000
duke@1 1001 // ---------------------------------------------------------------------------------------------------------------------
duke@1 1002
duke@1 1003 // Block the thread at the safepoint poll or poll return.
duke@1 1004 void ThreadSafepointState::handle_polling_page_exception() {
duke@1 1005
duke@1 1006 // Check state. block() will set thread state to thread_in_vm which will
duke@1 1007 // cause the safepoint state _type to become _call_back.
duke@1 1008 assert(type() == ThreadSafepointState::_running,
duke@1 1009 "polling page exception on thread not running state");
duke@1 1010
duke@1 1011 // Step 1: Find the nmethod from the return address
duke@1 1012 if (ShowSafepointMsgs && Verbose) {
duke@1 1013 tty->print_cr("Polling page exception at " INTPTR_FORMAT, thread()->saved_exception_pc());
duke@1 1014 }
duke@1 1015 address real_return_addr = thread()->saved_exception_pc();
duke@1 1016
duke@1 1017 CodeBlob *cb = CodeCache::find_blob(real_return_addr);
duke@1 1018 assert(cb != NULL && cb->is_nmethod(), "return address should be in nmethod");
duke@1 1019 nmethod* nm = (nmethod*)cb;
duke@1 1020
duke@1 1021 // Find frame of caller
duke@1 1022 frame stub_fr = thread()->last_frame();
duke@1 1023 CodeBlob* stub_cb = stub_fr.cb();
duke@1 1024 assert(stub_cb->is_safepoint_stub(), "must be a safepoint stub");
duke@1 1025 RegisterMap map(thread(), true);
duke@1 1026 frame caller_fr = stub_fr.sender(&map);
duke@1 1027
duke@1 1028 // Should only be poll_return or poll
duke@1 1029 assert( nm->is_at_poll_or_poll_return(real_return_addr), "should not be at call" );
duke@1 1030
duke@1 1031 // This is a poll immediately before a return. The exception handling code
duke@1 1032 // has already had the effect of causing the return to occur, so the execution
duke@1 1033 // will continue immediately after the call. In addition, the oopmap at the
duke@1 1034 // return point does not mark the return value as an oop (if it is), so
duke@1 1035 // it needs a handle here to be updated.
duke@1 1036 if( nm->is_at_poll_return(real_return_addr) ) {
duke@1 1037 // See if return type is an oop.
duke@1 1038 bool return_oop = nm->method()->is_returning_oop();
duke@1 1039 Handle return_value;
duke@1 1040 if (return_oop) {
duke@1 1041 // The oop result has been saved on the stack together with all
duke@1 1042 // the other registers. In order to preserve it over GCs we need
duke@1 1043 // to keep it in a handle.
duke@1 1044 oop result = caller_fr.saved_oop_result(&map);
duke@1 1045 assert(result == NULL || result->is_oop(), "must be oop");
duke@1 1046 return_value = Handle(thread(), result);
duke@1 1047 assert(Universe::heap()->is_in_or_null(result), "must be heap pointer");
duke@1 1048 }
duke@1 1049
duke@1 1050 // Block the thread
duke@1 1051 SafepointSynchronize::block(thread());
duke@1 1052
duke@1 1053 // restore oop result, if any
duke@1 1054 if (return_oop) {
duke@1 1055 caller_fr.set_saved_oop_result(&map, return_value());
duke@1 1056 }
duke@1 1057 }
duke@1 1058
duke@1 1059 // This is a safepoint poll. Verify the return address and block.
duke@1 1060 else {
duke@1 1061 set_at_poll_safepoint(true);
duke@1 1062
duke@1 1063 // verify the blob built the "return address" correctly
duke@1 1064 assert(real_return_addr == caller_fr.pc(), "must match");
duke@1 1065
duke@1 1066 // Block the thread
duke@1 1067 SafepointSynchronize::block(thread());
duke@1 1068 set_at_poll_safepoint(false);
duke@1 1069
duke@1 1070 // If we have a pending async exception deoptimize the frame
duke@1 1071 // as otherwise we may never deliver it.
duke@1 1072 if (thread()->has_async_condition()) {
duke@1 1073 ThreadInVMfromJavaNoAsyncException __tiv(thread());
never@7106 1074 Deoptimization::deoptimize_frame(thread(), caller_fr.id());
duke@1 1075 }
duke@1 1076
duke@1 1077 // If an exception has been installed we must check for a pending deoptimization
duke@1 1078 // Deoptimize frame if exception has been thrown.
duke@1 1079
duke@1 1080 if (thread()->has_pending_exception() ) {
duke@1 1081 RegisterMap map(thread(), true);
duke@1 1082 frame caller_fr = stub_fr.sender(&map);
duke@1 1083 if (caller_fr.is_deoptimized_frame()) {
duke@1 1084 // The exception patch will destroy registers that are still
duke@1 1085 // live and will be needed during deoptimization. Defer the
duke@1 1086 // Async exception should have defered the exception until the
duke@1 1087 // next safepoint which will be detected when we get into
duke@1 1088 // the interpreter so if we have an exception now things
duke@1 1089 // are messed up.
duke@1 1090
duke@1 1091 fatal("Exception installed and deoptimization is pending");
duke@1 1092 }
duke@1 1093 }
duke@1 1094 }
duke@1 1095 }
duke@1 1096
duke@1 1097
duke@1 1098 //
duke@1 1099 // Statistics & Instrumentations
duke@1 1100 //
duke@1 1101 SafepointSynchronize::SafepointStats* SafepointSynchronize::_safepoint_stats = NULL;
xlu@5042 1102 jlong SafepointSynchronize::_safepoint_begin_time = 0;
duke@1 1103 int SafepointSynchronize::_cur_stat_index = 0;
duke@1 1104 julong SafepointSynchronize::_safepoint_reasons[VM_Operation::VMOp_Terminating];
duke@1 1105 julong SafepointSynchronize::_coalesced_vmop_count = 0;
duke@1 1106 jlong SafepointSynchronize::_max_sync_time = 0;
xlu@5042 1107 jlong SafepointSynchronize::_max_vmop_time = 0;
xlu@5042 1108 float SafepointSynchronize::_ts_of_current_safepoint = 0.0f;
duke@1 1109
xlu@5042 1110 static jlong cleanup_end_time = 0;
duke@1 1111 static bool need_to_track_page_armed_status = false;
duke@1 1112 static bool init_done = false;
duke@1 1113
xlu@5042 1114 // Helper method to print the header.
xlu@5042 1115 static void print_header() {
xlu@5042 1116 tty->print(" vmop "
xlu@5042 1117 "[threads: total initially_running wait_to_block] ");
xlu@5042 1118 tty->print("[time: spin block sync cleanup vmop] ");
xlu@5042 1119
xlu@5042 1120 // no page armed status printed out if it is always armed.
xlu@5042 1121 if (need_to_track_page_armed_status) {
xlu@5042 1122 tty->print("page_armed ");
xlu@5042 1123 }
xlu@5042 1124
xlu@5042 1125 tty->print_cr("page_trap_count");
xlu@5042 1126 }
xlu@5042 1127
duke@1 1128 void SafepointSynchronize::deferred_initialize_stat() {
duke@1 1129 if (init_done) return;
duke@1 1130
duke@1 1131 if (PrintSafepointStatisticsCount <= 0) {
duke@1 1132 fatal("Wrong PrintSafepointStatisticsCount");
duke@1 1133 }
duke@1 1134
duke@1 1135 // If PrintSafepointStatisticsTimeout is specified, the statistics data will
duke@1 1136 // be printed right away, in which case, _safepoint_stats will regress to
duke@1 1137 // a single element array. Otherwise, it is a circular ring buffer with default
duke@1 1138 // size of PrintSafepointStatisticsCount.
duke@1 1139 int stats_array_size;
duke@1 1140 if (PrintSafepointStatisticsTimeout > 0) {
duke@1 1141 stats_array_size = 1;
duke@1 1142 PrintSafepointStatistics = true;
duke@1 1143 } else {
duke@1 1144 stats_array_size = PrintSafepointStatisticsCount;
duke@1 1145 }
duke@1 1146 _safepoint_stats = (SafepointStats*)os::malloc(stats_array_size
duke@1 1147 * sizeof(SafepointStats));
duke@1 1148 guarantee(_safepoint_stats != NULL,
duke@1 1149 "not enough memory for safepoint instrumentation data");
duke@1 1150
duke@1 1151 if (UseCompilerSafepoints && DeferPollingPageLoopCount >= 0) {
duke@1 1152 need_to_track_page_armed_status = true;
duke@1 1153 }
duke@1 1154 init_done = true;
duke@1 1155 }
duke@1 1156
duke@1 1157 void SafepointSynchronize::begin_statistics(int nof_threads, int nof_running) {
xlu@4006 1158 assert(init_done, "safepoint statistics array hasn't been initialized");
duke@1 1159 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
duke@1 1160
xlu@5042 1161 spstat->_time_stamp = _ts_of_current_safepoint;
xlu@5042 1162
duke@1 1163 VM_Operation *op = VMThread::vm_operation();
duke@1 1164 spstat->_vmop_type = (op != NULL ? op->type() : -1);
duke@1 1165 if (op != NULL) {
duke@1 1166 _safepoint_reasons[spstat->_vmop_type]++;
duke@1 1167 }
duke@1 1168
duke@1 1169 spstat->_nof_total_threads = nof_threads;
duke@1 1170 spstat->_nof_initial_running_threads = nof_running;
duke@1 1171 spstat->_nof_threads_hit_page_trap = 0;
duke@1 1172
duke@1 1173 // Records the start time of spinning. The real time spent on spinning
duke@1 1174 // will be adjusted when spin is done. Same trick is applied for time
duke@1 1175 // spent on waiting for threads to block.
duke@1 1176 if (nof_running != 0) {
duke@1 1177 spstat->_time_to_spin = os::javaTimeNanos();
duke@1 1178 } else {
duke@1 1179 spstat->_time_to_spin = 0;
duke@1 1180 }
duke@1 1181 }
duke@1 1182
duke@1 1183 void SafepointSynchronize::update_statistics_on_spin_end() {
duke@1 1184 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
duke@1 1185
duke@1 1186 jlong cur_time = os::javaTimeNanos();
duke@1 1187
duke@1 1188 spstat->_nof_threads_wait_to_block = _waiting_to_block;
duke@1 1189 if (spstat->_nof_initial_running_threads != 0) {
duke@1 1190 spstat->_time_to_spin = cur_time - spstat->_time_to_spin;
duke@1 1191 }
duke@1 1192
duke@1 1193 if (need_to_track_page_armed_status) {
duke@1 1194 spstat->_page_armed = (PageArmed == 1);
duke@1 1195 }
duke@1 1196
duke@1 1197 // Records the start time of waiting for to block. Updated when block is done.
duke@1 1198 if (_waiting_to_block != 0) {
duke@1 1199 spstat->_time_to_wait_to_block = cur_time;
duke@1 1200 } else {
duke@1 1201 spstat->_time_to_wait_to_block = 0;
duke@1 1202 }
duke@1 1203 }
duke@1 1204
duke@1 1205 void SafepointSynchronize::update_statistics_on_sync_end(jlong end_time) {
duke@1 1206 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
duke@1 1207
duke@1 1208 if (spstat->_nof_threads_wait_to_block != 0) {
duke@1 1209 spstat->_time_to_wait_to_block = end_time -
duke@1 1210 spstat->_time_to_wait_to_block;
duke@1 1211 }
duke@1 1212
duke@1 1213 // Records the end time of sync which will be used to calculate the total
duke@1 1214 // vm operation time. Again, the real time spending in syncing will be deducted
duke@1 1215 // from the start of the sync time later when end_statistics is called.
xlu@5042 1216 spstat->_time_to_sync = end_time - _safepoint_begin_time;
duke@1 1217 if (spstat->_time_to_sync > _max_sync_time) {
duke@1 1218 _max_sync_time = spstat->_time_to_sync;
duke@1 1219 }
xlu@5042 1220
xlu@5042 1221 spstat->_time_to_do_cleanups = end_time;
xlu@5042 1222 }
xlu@5042 1223
xlu@5042 1224 void SafepointSynchronize::update_statistics_on_cleanup_end(jlong end_time) {
xlu@5042 1225 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
xlu@5042 1226
xlu@5042 1227 // Record how long spent in cleanup tasks.
xlu@5042 1228 spstat->_time_to_do_cleanups = end_time - spstat->_time_to_do_cleanups;
xlu@5042 1229
xlu@5042 1230 cleanup_end_time = end_time;
duke@1 1231 }
duke@1 1232
duke@1 1233 void SafepointSynchronize::end_statistics(jlong vmop_end_time) {
duke@1 1234 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
duke@1 1235
duke@1 1236 // Update the vm operation time.
xlu@5042 1237 spstat->_time_to_exec_vmop = vmop_end_time - cleanup_end_time;
xlu@5042 1238 if (spstat->_time_to_exec_vmop > _max_vmop_time) {
xlu@5042 1239 _max_vmop_time = spstat->_time_to_exec_vmop;
xlu@5042 1240 }
duke@1 1241 // Only the sync time longer than the specified
duke@1 1242 // PrintSafepointStatisticsTimeout will be printed out right away.
duke@1 1243 // By default, it is -1 meaning all samples will be put into the list.
duke@1 1244 if ( PrintSafepointStatisticsTimeout > 0) {
duke@1 1245 if (spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) {
duke@1 1246 print_statistics();
duke@1 1247 }
duke@1 1248 } else {
duke@1 1249 // The safepoint statistics will be printed out when the _safepoin_stats
duke@1 1250 // array fills up.
xlu@5042 1251 if (_cur_stat_index == PrintSafepointStatisticsCount - 1) {
duke@1 1252 print_statistics();
duke@1 1253 _cur_stat_index = 0;
xlu@5042 1254 } else {
xlu@5042 1255 _cur_stat_index++;
duke@1 1256 }
duke@1 1257 }
duke@1 1258 }
duke@1 1259
duke@1 1260 void SafepointSynchronize::print_statistics() {
duke@1 1261 SafepointStats* sstats = _safepoint_stats;
duke@1 1262
xlu@5042 1263 for (int index = 0; index <= _cur_stat_index; index++) {
xlu@5042 1264 if (index % 30 == 0) {
xlu@5042 1265 print_header();
xlu@5042 1266 }
duke@1 1267 sstats = &_safepoint_stats[index];
xlu@5042 1268 tty->print("%.3f: ", sstats->_time_stamp);
xlu@5042 1269 tty->print("%-26s ["
duke@1 1270 INT32_FORMAT_W(8)INT32_FORMAT_W(11)INT32_FORMAT_W(15)
xlu@5042 1271 " ] ",
duke@1 1272 sstats->_vmop_type == -1 ? "no vm operation" :
duke@1 1273 VM_Operation::name(sstats->_vmop_type),
duke@1 1274 sstats->_nof_total_threads,
duke@1 1275 sstats->_nof_initial_running_threads,
duke@1 1276 sstats->_nof_threads_wait_to_block);
duke@1 1277 // "/ MICROUNITS " is to convert the unit from nanos to millis.
xlu@5042 1278 tty->print(" ["
xlu@5042 1279 INT64_FORMAT_W(6)INT64_FORMAT_W(6)
xlu@5042 1280 INT64_FORMAT_W(6)INT64_FORMAT_W(6)
xlu@5042 1281 INT64_FORMAT_W(6)" ] ",
duke@1 1282 sstats->_time_to_spin / MICROUNITS,
duke@1 1283 sstats->_time_to_wait_to_block / MICROUNITS,
duke@1 1284 sstats->_time_to_sync / MICROUNITS,
xlu@5042 1285 sstats->_time_to_do_cleanups / MICROUNITS,
xlu@5042 1286 sstats->_time_to_exec_vmop / MICROUNITS);
duke@1 1287
duke@1 1288 if (need_to_track_page_armed_status) {
duke@1 1289 tty->print(INT32_FORMAT" ", sstats->_page_armed);
duke@1 1290 }
duke@1 1291 tty->print_cr(INT32_FORMAT" ", sstats->_nof_threads_hit_page_trap);
duke@1 1292 }
duke@1 1293 }
duke@1 1294
duke@1 1295 // This method will be called when VM exits. It will first call
duke@1 1296 // print_statistics to print out the rest of the sampling. Then
duke@1 1297 // it tries to summarize the sampling.
duke@1 1298 void SafepointSynchronize::print_stat_on_exit() {
duke@1 1299 if (_safepoint_stats == NULL) return;
duke@1 1300
duke@1 1301 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
duke@1 1302
duke@1 1303 // During VM exit, end_statistics may not get called and in that
duke@1 1304 // case, if the sync time is less than PrintSafepointStatisticsTimeout,
duke@1 1305 // don't print it out.
duke@1 1306 // Approximate the vm op time.
duke@1 1307 _safepoint_stats[_cur_stat_index]._time_to_exec_vmop =
xlu@5042 1308 os::javaTimeNanos() - cleanup_end_time;
duke@1 1309
duke@1 1310 if ( PrintSafepointStatisticsTimeout < 0 ||
duke@1 1311 spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) {
duke@1 1312 print_statistics();
duke@1 1313 }
duke@1 1314 tty->print_cr("");
duke@1 1315
duke@1 1316 // Print out polling page sampling status.
duke@1 1317 if (!need_to_track_page_armed_status) {
duke@1 1318 if (UseCompilerSafepoints) {
duke@1 1319 tty->print_cr("Polling page always armed");
duke@1 1320 }
duke@1 1321 } else {
duke@1 1322 tty->print_cr("Defer polling page loop count = %d\n",
duke@1 1323 DeferPollingPageLoopCount);
duke@1 1324 }
duke@1 1325
duke@1 1326 for (int index = 0; index < VM_Operation::VMOp_Terminating; index++) {
duke@1 1327 if (_safepoint_reasons[index] != 0) {
duke@1 1328 tty->print_cr("%-26s"UINT64_FORMAT_W(10), VM_Operation::name(index),
duke@1 1329 _safepoint_reasons[index]);
duke@1 1330 }
duke@1 1331 }
duke@1 1332
duke@1 1333 tty->print_cr(UINT64_FORMAT_W(5)" VM operations coalesced during safepoint",
duke@1 1334 _coalesced_vmop_count);
duke@1 1335 tty->print_cr("Maximum sync time "INT64_FORMAT_W(5)" ms",
duke@1 1336 _max_sync_time / MICROUNITS);
xlu@5042 1337 tty->print_cr("Maximum vm operation time (except for Exit VM operation) "
xlu@5042 1338 INT64_FORMAT_W(5)" ms",
xlu@5042 1339 _max_vmop_time / MICROUNITS);
duke@1 1340 }
duke@1 1341
duke@1 1342 // ------------------------------------------------------------------------------------------------
duke@1 1343 // Non-product code
duke@1 1344
duke@1 1345 #ifndef PRODUCT
duke@1 1346
duke@1 1347 void SafepointSynchronize::print_state() {
duke@1 1348 if (_state == _not_synchronized) {
duke@1 1349 tty->print_cr("not synchronized");
duke@1 1350 } else if (_state == _synchronizing || _state == _synchronized) {
duke@1 1351 tty->print_cr("State: %s", (_state == _synchronizing) ? "synchronizing" :
duke@1 1352 "synchronized");
duke@1 1353
duke@1 1354 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) {
duke@1 1355 cur->safepoint_state()->print();
duke@1 1356 }
duke@1 1357 }
duke@1 1358 }
duke@1 1359
duke@1 1360 void SafepointSynchronize::safepoint_msg(const char* format, ...) {
duke@1 1361 if (ShowSafepointMsgs) {
duke@1 1362 va_list ap;
duke@1 1363 va_start(ap, format);
duke@1 1364 tty->vprint_cr(format, ap);
duke@1 1365 va_end(ap);
duke@1 1366 }
duke@1 1367 }
duke@1 1368
duke@1 1369 #endif // !PRODUCT