1 /* 2 * Copyright (c) 1997, 2015, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/stringTable.hpp" 27 #include "classfile/symbolTable.hpp" 28 #include "classfile/systemDictionary.hpp" 29 #include "code/codeCache.hpp" 30 #include "code/icBuffer.hpp" 31 #include "code/nmethod.hpp" 32 #include "code/pcDesc.hpp" 33 #include "code/scopeDesc.hpp" 34 #include "gc/shared/collectedHeap.hpp" 35 #include "gc/shared/gcLocker.inline.hpp" 36 #include "interpreter/interpreter.hpp" 37 #include "logging/log.hpp" 38 #include "memory/resourceArea.hpp" 39 #include "memory/universe.inline.hpp" 40 #include "oops/oop.inline.hpp" 41 #include "oops/symbol.hpp" 42 #include "runtime/atomic.inline.hpp" 43 #include "runtime/compilationPolicy.hpp" 44 #include "runtime/deoptimization.hpp" 45 #include "runtime/frame.inline.hpp" 46 #include "runtime/interfaceSupport.hpp" 47 #include "runtime/mutexLocker.hpp" 48 #include "runtime/orderAccess.inline.hpp" 49 #include "runtime/osThread.hpp" 50 #include "runtime/safepoint.hpp" 51 #include "runtime/signature.hpp" 52 #include "runtime/stubCodeGenerator.hpp" 53 #include "runtime/stubRoutines.hpp" 54 #include "runtime/sweeper.hpp" 55 #include "runtime/synchronizer.hpp" 56 #include "runtime/thread.inline.hpp" 57 #include "services/runtimeService.hpp" 58 #include "utilities/events.hpp" 59 #include "utilities/macros.hpp" 60 #if INCLUDE_ALL_GCS 61 #include "gc/cms/concurrentMarkSweepThread.hpp" 62 #include "gc/g1/suspendibleThreadSet.hpp" 63 #endif // INCLUDE_ALL_GCS 64 #ifdef COMPILER1 65 #include "c1/c1_globals.hpp" 66 #endif 67 68 // -------------------------------------------------------------------------------------------------- 69 // Implementation of Safepoint begin/end 70 71 SafepointSynchronize::SynchronizeState volatile SafepointSynchronize::_state = SafepointSynchronize::_not_synchronized; 72 volatile int SafepointSynchronize::_waiting_to_block = 0; 73 volatile int SafepointSynchronize::_safepoint_counter = 0; 74 int SafepointSynchronize::_current_jni_active_count = 0; 75 long SafepointSynchronize::_end_of_last_safepoint = 0; 76 static volatile int PageArmed = 0 ; // safepoint polling page is RO|RW vs PROT_NONE 77 static volatile int TryingToBlock = 0 ; // proximate value -- for advisory use only 78 static bool timeout_error_printed = false; 79 80 // Roll all threads forward to a safepoint and suspend them all 81 void SafepointSynchronize::begin() { 82 83 Thread* myThread = Thread::current(); 84 assert(myThread->is_VM_thread(), "Only VM thread may execute a safepoint"); 85 86 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) { 87 _safepoint_begin_time = os::javaTimeNanos(); 88 _ts_of_current_safepoint = tty->time_stamp().seconds(); 89 } 90 91 #if INCLUDE_ALL_GCS 92 if (UseConcMarkSweepGC) { 93 // In the future we should investigate whether CMS can use the 94 // more-general mechanism below. DLD (01/05). 95 ConcurrentMarkSweepThread::synchronize(false); 96 } else if (UseG1GC) { 97 SuspendibleThreadSet::synchronize(); 98 } 99 #endif // INCLUDE_ALL_GCS 100 101 // By getting the Threads_lock, we assure that no threads are about to start or 102 // exit. It is released again in SafepointSynchronize::end(). 103 Threads_lock->lock(); 104 105 assert( _state == _not_synchronized, "trying to safepoint synchronize with wrong state"); 106 107 int nof_threads = Threads::number_of_threads(); 108 109 log_debug(safepoint)("Safepoint synchronization initiated. (%d)", nof_threads); 110 111 RuntimeService::record_safepoint_begin(); 112 113 MutexLocker mu(Safepoint_lock); 114 115 // Reset the count of active JNI critical threads 116 _current_jni_active_count = 0; 117 118 // Set number of threads to wait for, before we initiate the callbacks 119 _waiting_to_block = nof_threads; 120 TryingToBlock = 0 ; 121 int still_running = nof_threads; 122 123 // Save the starting time, so that it can be compared to see if this has taken 124 // too long to complete. 125 jlong safepoint_limit_time = 0; 126 timeout_error_printed = false; 127 128 // PrintSafepointStatisticsTimeout can be specified separately. When 129 // specified, PrintSafepointStatistics will be set to true in 130 // deferred_initialize_stat method. The initialization has to be done 131 // early enough to avoid any races. See bug 6880029 for details. 132 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) { 133 deferred_initialize_stat(); 134 } 135 136 // Begin the process of bringing the system to a safepoint. 137 // Java threads can be in several different states and are 138 // stopped by different mechanisms: 139 // 140 // 1. Running interpreted 141 // The interpreter dispatch table is changed to force it to 142 // check for a safepoint condition between bytecodes. 143 // 2. Running in native code 144 // When returning from the native code, a Java thread must check 145 // the safepoint _state to see if we must block. If the 146 // VM thread sees a Java thread in native, it does 147 // not wait for this thread to block. The order of the memory 148 // writes and reads of both the safepoint state and the Java 149 // threads state is critical. In order to guarantee that the 150 // memory writes are serialized with respect to each other, 151 // the VM thread issues a memory barrier instruction 152 // (on MP systems). In order to avoid the overhead of issuing 153 // a memory barrier for each Java thread making native calls, each Java 154 // thread performs a write to a single memory page after changing 155 // the thread state. The VM thread performs a sequence of 156 // mprotect OS calls which forces all previous writes from all 157 // Java threads to be serialized. This is done in the 158 // os::serialize_thread_states() call. This has proven to be 159 // much more efficient than executing a membar instruction 160 // on every call to native code. 161 // 3. Running compiled Code 162 // Compiled code reads a global (Safepoint Polling) page that 163 // is set to fault if we are trying to get to a safepoint. 164 // 4. Blocked 165 // A thread which is blocked will not be allowed to return from the 166 // block condition until the safepoint operation is complete. 167 // 5. In VM or Transitioning between states 168 // If a Java thread is currently running in the VM or transitioning 169 // between states, the safepointing code will wait for the thread to 170 // block itself when it attempts transitions to a new state. 171 // 172 _state = _synchronizing; 173 OrderAccess::fence(); 174 175 // Flush all thread states to memory 176 if (!UseMembar) { 177 os::serialize_thread_states(); 178 } 179 180 // Make interpreter safepoint aware 181 Interpreter::notice_safepoints(); 182 183 if (DeferPollingPageLoopCount < 0) { 184 // Make polling safepoint aware 185 guarantee (PageArmed == 0, "invariant") ; 186 PageArmed = 1 ; 187 os::make_polling_page_unreadable(); 188 } 189 190 // Consider using active_processor_count() ... but that call is expensive. 191 int ncpus = os::processor_count() ; 192 193 #ifdef ASSERT 194 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) { 195 assert(cur->safepoint_state()->is_running(), "Illegal initial state"); 196 // Clear the visited flag to ensure that the critical counts are collected properly. 197 cur->set_visited_for_critical_count(false); 198 } 199 #endif // ASSERT 200 201 if (SafepointTimeout) 202 safepoint_limit_time = os::javaTimeNanos() + (jlong)SafepointTimeoutDelay * MICROUNITS; 203 204 // Iterate through all threads until it have been determined how to stop them all at a safepoint 205 unsigned int iterations = 0; 206 int steps = 0 ; 207 while(still_running > 0) { 208 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) { 209 assert(!cur->is_ConcurrentGC_thread(), "A concurrent GC thread is unexpectly being suspended"); 210 ThreadSafepointState *cur_state = cur->safepoint_state(); 211 if (cur_state->is_running()) { 212 cur_state->examine_state_of_thread(); 213 if (!cur_state->is_running()) { 214 still_running--; 215 // consider adjusting steps downward: 216 // steps = 0 217 // steps -= NNN 218 // steps >>= 1 219 // steps = MIN(steps, 2000-100) 220 // if (iterations != 0) steps -= NNN 221 } 222 if (log_is_enabled(Trace, safepoint)) { 223 ResourceMark rm; 224 cur_state->print_on(LogHandle(safepoint)::debug_stream()); 225 } 226 } 227 } 228 229 if (PrintSafepointStatistics && iterations == 0) { 230 begin_statistics(nof_threads, still_running); 231 } 232 233 if (still_running > 0) { 234 // Check for if it takes to long 235 if (SafepointTimeout && safepoint_limit_time < os::javaTimeNanos()) { 236 print_safepoint_timeout(_spinning_timeout); 237 } 238 239 // Spin to avoid context switching. 240 // There's a tension between allowing the mutators to run (and rendezvous) 241 // vs spinning. As the VM thread spins, wasting cycles, it consumes CPU that 242 // a mutator might otherwise use profitably to reach a safepoint. Excessive 243 // spinning by the VM thread on a saturated system can increase rendezvous latency. 244 // Blocking or yielding incur their own penalties in the form of context switching 245 // and the resultant loss of $ residency. 246 // 247 // Further complicating matters is that yield() does not work as naively expected 248 // on many platforms -- yield() does not guarantee that any other ready threads 249 // will run. As such we revert to naked_short_sleep() after some number of iterations. 250 // nakes_short_sleep() is implemented as a short unconditional sleep. 251 // Typical operating systems round a "short" sleep period up to 10 msecs, so sleeping 252 // can actually increase the time it takes the VM thread to detect that a system-wide 253 // stop-the-world safepoint has been reached. In a pathological scenario such as that 254 // described in CR6415670 the VMthread may sleep just before the mutator(s) become safe. 255 // In that case the mutators will be stalled waiting for the safepoint to complete and the 256 // the VMthread will be sleeping, waiting for the mutators to rendezvous. The VMthread 257 // will eventually wake up and detect that all mutators are safe, at which point 258 // we'll again make progress. 259 // 260 // Beware too that that the VMThread typically runs at elevated priority. 261 // Its default priority is higher than the default mutator priority. 262 // Obviously, this complicates spinning. 263 // 264 // Note too that on Windows XP SwitchThreadTo() has quite different behavior than Sleep(0). 265 // Sleep(0) will _not yield to lower priority threads, while SwitchThreadTo() will. 266 // 267 // See the comments in synchronizer.cpp for additional remarks on spinning. 268 // 269 // In the future we might: 270 // 1. Modify the safepoint scheme to avoid potentially unbounded spinning. 271 // This is tricky as the path used by a thread exiting the JVM (say on 272 // on JNI call-out) simply stores into its state field. The burden 273 // is placed on the VM thread, which must poll (spin). 274 // 2. Find something useful to do while spinning. If the safepoint is GC-related 275 // we might aggressively scan the stacks of threads that are already safe. 276 // 3. Use Solaris schedctl to examine the state of the still-running mutators. 277 // If all the mutators are ONPROC there's no reason to sleep or yield. 278 // 4. YieldTo() any still-running mutators that are ready but OFFPROC. 279 // 5. Check system saturation. If the system is not fully saturated then 280 // simply spin and avoid sleep/yield. 281 // 6. As still-running mutators rendezvous they could unpark the sleeping 282 // VMthread. This works well for still-running mutators that become 283 // safe. The VMthread must still poll for mutators that call-out. 284 // 7. Drive the policy on time-since-begin instead of iterations. 285 // 8. Consider making the spin duration a function of the # of CPUs: 286 // Spin = (((ncpus-1) * M) + K) + F(still_running) 287 // Alternately, instead of counting iterations of the outer loop 288 // we could count the # of threads visited in the inner loop, above. 289 // 9. On windows consider using the return value from SwitchThreadTo() 290 // to drive subsequent spin/SwitchThreadTo()/Sleep(N) decisions. 291 292 if (int(iterations) == DeferPollingPageLoopCount) { 293 guarantee (PageArmed == 0, "invariant") ; 294 PageArmed = 1 ; 295 os::make_polling_page_unreadable(); 296 } 297 298 // Instead of (ncpus > 1) consider either (still_running < (ncpus + EPSILON)) or 299 // ((still_running + _waiting_to_block - TryingToBlock)) < ncpus) 300 ++steps ; 301 if (ncpus > 1 && steps < SafepointSpinBeforeYield) { 302 SpinPause() ; // MP-Polite spin 303 } else 304 if (steps < DeferThrSuspendLoopCount) { 305 os::naked_yield() ; 306 } else { 307 os::naked_short_sleep(1); 308 } 309 310 iterations ++ ; 311 } 312 assert(iterations < (uint)max_jint, "We have been iterating in the safepoint loop too long"); 313 } 314 assert(still_running == 0, "sanity check"); 315 316 if (PrintSafepointStatistics) { 317 update_statistics_on_spin_end(); 318 } 319 320 // wait until all threads are stopped 321 while (_waiting_to_block > 0) { 322 log_debug(safepoint)("Waiting for %d thread(s) to block", _waiting_to_block); 323 if (!SafepointTimeout || timeout_error_printed) { 324 Safepoint_lock->wait(true); // true, means with no safepoint checks 325 } else { 326 // Compute remaining time 327 jlong remaining_time = safepoint_limit_time - os::javaTimeNanos(); 328 329 // If there is no remaining time, then there is an error 330 if (remaining_time < 0 || Safepoint_lock->wait(true, remaining_time / MICROUNITS)) { 331 print_safepoint_timeout(_blocking_timeout); 332 } 333 } 334 } 335 assert(_waiting_to_block == 0, "sanity check"); 336 337 #ifndef PRODUCT 338 if (SafepointTimeout) { 339 jlong current_time = os::javaTimeNanos(); 340 if (safepoint_limit_time < current_time) { 341 tty->print_cr("# SafepointSynchronize: Finished after " 342 INT64_FORMAT_W(6) " ms", 343 ((current_time - safepoint_limit_time) / MICROUNITS + 344 (jlong)SafepointTimeoutDelay)); 345 } 346 } 347 #endif 348 349 assert((_safepoint_counter & 0x1) == 0, "must be even"); 350 assert(Threads_lock->owned_by_self(), "must hold Threads_lock"); 351 _safepoint_counter ++; 352 353 // Record state 354 _state = _synchronized; 355 356 OrderAccess::fence(); 357 358 #ifdef ASSERT 359 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) { 360 // make sure all the threads were visited 361 assert(cur->was_visited_for_critical_count(), "missed a thread"); 362 } 363 #endif // ASSERT 364 365 // Update the count of active JNI critical regions 366 GC_locker::set_jni_lock_count(_current_jni_active_count); 367 368 if (log_is_enabled(Debug, safepoint)) { 369 VM_Operation *op = VMThread::vm_operation(); 370 log_debug(safepoint)("Entering safepoint region: %s", 371 (op != NULL) ? op->name() : "no vm operation"); 372 } 373 374 RuntimeService::record_safepoint_synchronized(); 375 if (PrintSafepointStatistics) { 376 update_statistics_on_sync_end(os::javaTimeNanos()); 377 } 378 379 // Call stuff that needs to be run when a safepoint is just about to be completed 380 do_cleanup_tasks(); 381 382 if (PrintSafepointStatistics) { 383 // Record how much time spend on the above cleanup tasks 384 update_statistics_on_cleanup_end(os::javaTimeNanos()); 385 } 386 } 387 388 // Wake up all threads, so they are ready to resume execution after the safepoint 389 // operation has been carried out 390 void SafepointSynchronize::end() { 391 392 assert(Threads_lock->owned_by_self(), "must hold Threads_lock"); 393 assert((_safepoint_counter & 0x1) == 1, "must be odd"); 394 _safepoint_counter ++; 395 // memory fence isn't required here since an odd _safepoint_counter 396 // value can do no harm and a fence is issued below anyway. 397 398 DEBUG_ONLY(Thread* myThread = Thread::current();) 399 assert(myThread->is_VM_thread(), "Only VM thread can execute a safepoint"); 400 401 if (PrintSafepointStatistics) { 402 end_statistics(os::javaTimeNanos()); 403 } 404 405 #ifdef ASSERT 406 // A pending_exception cannot be installed during a safepoint. The threads 407 // may install an async exception after they come back from a safepoint into 408 // pending_exception after they unblock. But that should happen later. 409 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) { 410 assert (!(cur->has_pending_exception() && 411 cur->safepoint_state()->is_at_poll_safepoint()), 412 "safepoint installed a pending exception"); 413 } 414 #endif // ASSERT 415 416 if (PageArmed) { 417 // Make polling safepoint aware 418 os::make_polling_page_readable(); 419 PageArmed = 0 ; 420 } 421 422 // Remove safepoint check from interpreter 423 Interpreter::ignore_safepoints(); 424 425 { 426 MutexLocker mu(Safepoint_lock); 427 428 assert(_state == _synchronized, "must be synchronized before ending safepoint synchronization"); 429 430 // Set to not synchronized, so the threads will not go into the signal_thread_blocked method 431 // when they get restarted. 432 _state = _not_synchronized; 433 OrderAccess::fence(); 434 435 log_debug(safepoint)("Leaving safepoint region"); 436 437 // Start suspended threads 438 for(JavaThread *current = Threads::first(); current; current = current->next()) { 439 // A problem occurring on Solaris is when attempting to restart threads 440 // the first #cpus - 1 go well, but then the VMThread is preempted when we get 441 // to the next one (since it has been running the longest). We then have 442 // to wait for a cpu to become available before we can continue restarting 443 // threads. 444 // FIXME: This causes the performance of the VM to degrade when active and with 445 // large numbers of threads. Apparently this is due to the synchronous nature 446 // of suspending threads. 447 // 448 // TODO-FIXME: the comments above are vestigial and no longer apply. 449 // Furthermore, using solaris' schedctl in this particular context confers no benefit 450 if (VMThreadHintNoPreempt) { 451 os::hint_no_preempt(); 452 } 453 ThreadSafepointState* cur_state = current->safepoint_state(); 454 assert(cur_state->type() != ThreadSafepointState::_running, "Thread not suspended at safepoint"); 455 cur_state->restart(); 456 assert(cur_state->is_running(), "safepoint state has not been reset"); 457 } 458 459 RuntimeService::record_safepoint_end(); 460 461 // Release threads lock, so threads can be created/destroyed again. It will also starts all threads 462 // blocked in signal_thread_blocked 463 Threads_lock->unlock(); 464 465 } 466 #if INCLUDE_ALL_GCS 467 // If there are any concurrent GC threads resume them. 468 if (UseConcMarkSweepGC) { 469 ConcurrentMarkSweepThread::desynchronize(false); 470 } else if (UseG1GC) { 471 SuspendibleThreadSet::desynchronize(); 472 } 473 #endif // INCLUDE_ALL_GCS 474 // record this time so VMThread can keep track how much time has elapsed 475 // since last safepoint. 476 _end_of_last_safepoint = os::javaTimeMillis(); 477 } 478 479 bool SafepointSynchronize::is_cleanup_needed() { 480 // Need a safepoint if some inline cache buffers is non-empty 481 if (!InlineCacheBuffer::is_empty()) return true; 482 return false; 483 } 484 485 486 487 // Various cleaning tasks that should be done periodically at safepoints 488 void SafepointSynchronize::do_cleanup_tasks() { 489 { 490 TraceTime t1("deflating idle monitors", TraceSafepointCleanupTime); 491 ObjectSynchronizer::deflate_idle_monitors(); 492 } 493 494 { 495 TraceTime t2("updating inline caches", TraceSafepointCleanupTime); 496 InlineCacheBuffer::update_inline_caches(); 497 } 498 { 499 TraceTime t3("compilation policy safepoint handler", TraceSafepointCleanupTime); 500 CompilationPolicy::policy()->do_safepoint_work(); 501 } 502 503 { 504 TraceTime t4("mark nmethods", TraceSafepointCleanupTime); 505 NMethodSweeper::mark_active_nmethods(); 506 } 507 508 if (SymbolTable::needs_rehashing()) { 509 TraceTime t5("rehashing symbol table", TraceSafepointCleanupTime); 510 SymbolTable::rehash_table(); 511 } 512 513 if (StringTable::needs_rehashing()) { 514 TraceTime t6("rehashing string table", TraceSafepointCleanupTime); 515 StringTable::rehash_table(); 516 } 517 518 { 519 // CMS delays purging the CLDG until the beginning of the next safepoint and to 520 // make sure concurrent sweep is done 521 TraceTime t7("purging class loader data graph", TraceSafepointCleanupTime); 522 ClassLoaderDataGraph::purge_if_needed(); 523 } 524 } 525 526 527 bool SafepointSynchronize::safepoint_safe(JavaThread *thread, JavaThreadState state) { 528 switch(state) { 529 case _thread_in_native: 530 // native threads are safe if they have no java stack or have walkable stack 531 return !thread->has_last_Java_frame() || thread->frame_anchor()->walkable(); 532 533 // blocked threads should have already have walkable stack 534 case _thread_blocked: 535 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "blocked and not walkable"); 536 return true; 537 538 default: 539 return false; 540 } 541 } 542 543 544 // See if the thread is running inside a lazy critical native and 545 // update the thread critical count if so. Also set a suspend flag to 546 // cause the native wrapper to return into the JVM to do the unlock 547 // once the native finishes. 548 void SafepointSynchronize::check_for_lazy_critical_native(JavaThread *thread, JavaThreadState state) { 549 if (state == _thread_in_native && 550 thread->has_last_Java_frame() && 551 thread->frame_anchor()->walkable()) { 552 // This thread might be in a critical native nmethod so look at 553 // the top of the stack and increment the critical count if it 554 // is. 555 frame wrapper_frame = thread->last_frame(); 556 CodeBlob* stub_cb = wrapper_frame.cb(); 557 if (stub_cb != NULL && 558 stub_cb->is_nmethod() && 559 stub_cb->as_nmethod_or_null()->is_lazy_critical_native()) { 560 // A thread could potentially be in a critical native across 561 // more than one safepoint, so only update the critical state on 562 // the first one. When it returns it will perform the unlock. 563 if (!thread->do_critical_native_unlock()) { 564 #ifdef ASSERT 565 if (!thread->in_critical()) { 566 GC_locker::increment_debug_jni_lock_count(); 567 } 568 #endif 569 thread->enter_critical(); 570 // Make sure the native wrapper calls back on return to 571 // perform the needed critical unlock. 572 thread->set_critical_native_unlock(); 573 } 574 } 575 } 576 } 577 578 579 580 // ------------------------------------------------------------------------------------------------------- 581 // Implementation of Safepoint callback point 582 583 void SafepointSynchronize::block(JavaThread *thread) { 584 assert(thread != NULL, "thread must be set"); 585 assert(thread->is_Java_thread(), "not a Java thread"); 586 587 // Threads shouldn't block if they are in the middle of printing, but... 588 ttyLocker::break_tty_lock_for_safepoint(os::current_thread_id()); 589 590 // Only bail from the block() call if the thread is gone from the 591 // thread list; starting to exit should still block. 592 if (thread->is_terminated()) { 593 // block current thread if we come here from native code when VM is gone 594 thread->block_if_vm_exited(); 595 596 // otherwise do nothing 597 return; 598 } 599 600 JavaThreadState state = thread->thread_state(); 601 thread->frame_anchor()->make_walkable(thread); 602 603 // Check that we have a valid thread_state at this point 604 switch(state) { 605 case _thread_in_vm_trans: 606 case _thread_in_Java: // From compiled code 607 608 // We are highly likely to block on the Safepoint_lock. In order to avoid blocking in this case, 609 // we pretend we are still in the VM. 610 thread->set_thread_state(_thread_in_vm); 611 612 if (is_synchronizing()) { 613 Atomic::inc (&TryingToBlock) ; 614 } 615 616 // We will always be holding the Safepoint_lock when we are examine the state 617 // of a thread. Hence, the instructions between the Safepoint_lock->lock() and 618 // Safepoint_lock->unlock() are happening atomic with regards to the safepoint code 619 Safepoint_lock->lock_without_safepoint_check(); 620 if (is_synchronizing()) { 621 // Decrement the number of threads to wait for and signal vm thread 622 assert(_waiting_to_block > 0, "sanity check"); 623 _waiting_to_block--; 624 thread->safepoint_state()->set_has_called_back(true); 625 626 DEBUG_ONLY(thread->set_visited_for_critical_count(true)); 627 if (thread->in_critical()) { 628 // Notice that this thread is in a critical section 629 increment_jni_active_count(); 630 } 631 632 // Consider (_waiting_to_block < 2) to pipeline the wakeup of the VM thread 633 if (_waiting_to_block == 0) { 634 Safepoint_lock->notify_all(); 635 } 636 } 637 638 // We transition the thread to state _thread_blocked here, but 639 // we can't do our usual check for external suspension and then 640 // self-suspend after the lock_without_safepoint_check() call 641 // below because we are often called during transitions while 642 // we hold different locks. That would leave us suspended while 643 // holding a resource which results in deadlocks. 644 thread->set_thread_state(_thread_blocked); 645 Safepoint_lock->unlock(); 646 647 // We now try to acquire the threads lock. Since this lock is hold by the VM thread during 648 // the entire safepoint, the threads will all line up here during the safepoint. 649 Threads_lock->lock_without_safepoint_check(); 650 // restore original state. This is important if the thread comes from compiled code, so it 651 // will continue to execute with the _thread_in_Java state. 652 thread->set_thread_state(state); 653 Threads_lock->unlock(); 654 break; 655 656 case _thread_in_native_trans: 657 case _thread_blocked_trans: 658 case _thread_new_trans: 659 if (thread->safepoint_state()->type() == ThreadSafepointState::_call_back) { 660 thread->print_thread_state(); 661 fatal("Deadlock in safepoint code. " 662 "Should have called back to the VM before blocking."); 663 } 664 665 // We transition the thread to state _thread_blocked here, but 666 // we can't do our usual check for external suspension and then 667 // self-suspend after the lock_without_safepoint_check() call 668 // below because we are often called during transitions while 669 // we hold different locks. That would leave us suspended while 670 // holding a resource which results in deadlocks. 671 thread->set_thread_state(_thread_blocked); 672 673 // It is not safe to suspend a thread if we discover it is in _thread_in_native_trans. Hence, 674 // the safepoint code might still be waiting for it to block. We need to change the state here, 675 // so it can see that it is at a safepoint. 676 677 // Block until the safepoint operation is completed. 678 Threads_lock->lock_without_safepoint_check(); 679 680 // Restore state 681 thread->set_thread_state(state); 682 683 Threads_lock->unlock(); 684 break; 685 686 default: 687 fatal("Illegal threadstate encountered: %d", state); 688 } 689 690 // Check for pending. async. exceptions or suspends - except if the 691 // thread was blocked inside the VM. has_special_runtime_exit_condition() 692 // is called last since it grabs a lock and we only want to do that when 693 // we must. 694 // 695 // Note: we never deliver an async exception at a polling point as the 696 // compiler may not have an exception handler for it. The polling 697 // code will notice the async and deoptimize and the exception will 698 // be delivered. (Polling at a return point is ok though). Sure is 699 // a lot of bother for a deprecated feature... 700 // 701 // We don't deliver an async exception if the thread state is 702 // _thread_in_native_trans so JNI functions won't be called with 703 // a surprising pending exception. If the thread state is going back to java, 704 // async exception is checked in check_special_condition_for_native_trans(). 705 706 if (state != _thread_blocked_trans && 707 state != _thread_in_vm_trans && 708 thread->has_special_runtime_exit_condition()) { 709 thread->handle_special_runtime_exit_condition( 710 !thread->is_at_poll_safepoint() && (state != _thread_in_native_trans)); 711 } 712 } 713 714 // ------------------------------------------------------------------------------------------------------ 715 // Exception handlers 716 717 718 void SafepointSynchronize::handle_polling_page_exception(JavaThread *thread) { 719 assert(thread->is_Java_thread(), "polling reference encountered by VM thread"); 720 assert(thread->thread_state() == _thread_in_Java, "should come from Java code"); 721 assert(SafepointSynchronize::is_synchronizing(), "polling encountered outside safepoint synchronization"); 722 723 if (ShowSafepointMsgs) { 724 tty->print("handle_polling_page_exception: "); 725 } 726 727 if (PrintSafepointStatistics) { 728 inc_page_trap_count(); 729 } 730 731 ThreadSafepointState* state = thread->safepoint_state(); 732 733 state->handle_polling_page_exception(); 734 } 735 736 737 void SafepointSynchronize::print_safepoint_timeout(SafepointTimeoutReason reason) { 738 if (!timeout_error_printed) { 739 timeout_error_printed = true; 740 // Print out the thread info which didn't reach the safepoint for debugging 741 // purposes (useful when there are lots of threads in the debugger). 742 tty->cr(); 743 tty->print_cr("# SafepointSynchronize::begin: Timeout detected:"); 744 if (reason == _spinning_timeout) { 745 tty->print_cr("# SafepointSynchronize::begin: Timed out while spinning to reach a safepoint."); 746 } else if (reason == _blocking_timeout) { 747 tty->print_cr("# SafepointSynchronize::begin: Timed out while waiting for threads to stop."); 748 } 749 750 tty->print_cr("# SafepointSynchronize::begin: Threads which did not reach the safepoint:"); 751 ThreadSafepointState *cur_state; 752 ResourceMark rm; 753 for(JavaThread *cur_thread = Threads::first(); cur_thread; 754 cur_thread = cur_thread->next()) { 755 cur_state = cur_thread->safepoint_state(); 756 757 if (cur_thread->thread_state() != _thread_blocked && 758 ((reason == _spinning_timeout && cur_state->is_running()) || 759 (reason == _blocking_timeout && !cur_state->has_called_back()))) { 760 tty->print("# "); 761 cur_thread->print(); 762 tty->cr(); 763 } 764 } 765 tty->print_cr("# SafepointSynchronize::begin: (End of list)"); 766 } 767 768 // To debug the long safepoint, specify both DieOnSafepointTimeout & 769 // ShowMessageBoxOnError. 770 if (DieOnSafepointTimeout) { 771 VM_Operation *op = VMThread::vm_operation(); 772 fatal("Safepoint sync time longer than " INTX_FORMAT "ms detected when executing %s.", 773 SafepointTimeoutDelay, 774 op != NULL ? op->name() : "no vm operation"); 775 } 776 } 777 778 779 // ------------------------------------------------------------------------------------------------------- 780 // Implementation of ThreadSafepointState 781 782 ThreadSafepointState::ThreadSafepointState(JavaThread *thread) { 783 _thread = thread; 784 _type = _running; 785 _has_called_back = false; 786 _at_poll_safepoint = false; 787 } 788 789 void ThreadSafepointState::create(JavaThread *thread) { 790 ThreadSafepointState *state = new ThreadSafepointState(thread); 791 thread->set_safepoint_state(state); 792 } 793 794 void ThreadSafepointState::destroy(JavaThread *thread) { 795 if (thread->safepoint_state()) { 796 delete(thread->safepoint_state()); 797 thread->set_safepoint_state(NULL); 798 } 799 } 800 801 void ThreadSafepointState::examine_state_of_thread() { 802 assert(is_running(), "better be running or just have hit safepoint poll"); 803 804 JavaThreadState state = _thread->thread_state(); 805 806 // Save the state at the start of safepoint processing. 807 _orig_thread_state = state; 808 809 // Check for a thread that is suspended. Note that thread resume tries 810 // to grab the Threads_lock which we own here, so a thread cannot be 811 // resumed during safepoint synchronization. 812 813 // We check to see if this thread is suspended without locking to 814 // avoid deadlocking with a third thread that is waiting for this 815 // thread to be suspended. The third thread can notice the safepoint 816 // that we're trying to start at the beginning of its SR_lock->wait() 817 // call. If that happens, then the third thread will block on the 818 // safepoint while still holding the underlying SR_lock. We won't be 819 // able to get the SR_lock and we'll deadlock. 820 // 821 // We don't need to grab the SR_lock here for two reasons: 822 // 1) The suspend flags are both volatile and are set with an 823 // Atomic::cmpxchg() call so we should see the suspended 824 // state right away. 825 // 2) We're being called from the safepoint polling loop; if 826 // we don't see the suspended state on this iteration, then 827 // we'll come around again. 828 // 829 bool is_suspended = _thread->is_ext_suspended(); 830 if (is_suspended) { 831 roll_forward(_at_safepoint); 832 return; 833 } 834 835 // Some JavaThread states have an initial safepoint state of 836 // running, but are actually at a safepoint. We will happily 837 // agree and update the safepoint state here. 838 if (SafepointSynchronize::safepoint_safe(_thread, state)) { 839 SafepointSynchronize::check_for_lazy_critical_native(_thread, state); 840 roll_forward(_at_safepoint); 841 return; 842 } 843 844 if (state == _thread_in_vm) { 845 roll_forward(_call_back); 846 return; 847 } 848 849 // All other thread states will continue to run until they 850 // transition and self-block in state _blocked 851 // Safepoint polling in compiled code causes the Java threads to do the same. 852 // Note: new threads may require a malloc so they must be allowed to finish 853 854 assert(is_running(), "examine_state_of_thread on non-running thread"); 855 return; 856 } 857 858 // Returns true is thread could not be rolled forward at present position. 859 void ThreadSafepointState::roll_forward(suspend_type type) { 860 _type = type; 861 862 switch(_type) { 863 case _at_safepoint: 864 SafepointSynchronize::signal_thread_at_safepoint(); 865 DEBUG_ONLY(_thread->set_visited_for_critical_count(true)); 866 if (_thread->in_critical()) { 867 // Notice that this thread is in a critical section 868 SafepointSynchronize::increment_jni_active_count(); 869 } 870 break; 871 872 case _call_back: 873 set_has_called_back(false); 874 break; 875 876 case _running: 877 default: 878 ShouldNotReachHere(); 879 } 880 } 881 882 void ThreadSafepointState::restart() { 883 switch(type()) { 884 case _at_safepoint: 885 case _call_back: 886 break; 887 888 case _running: 889 default: 890 tty->print_cr("restart thread " INTPTR_FORMAT " with state %d", 891 p2i(_thread), _type); 892 _thread->print(); 893 ShouldNotReachHere(); 894 } 895 _type = _running; 896 set_has_called_back(false); 897 } 898 899 900 void ThreadSafepointState::print_on(outputStream *st) const { 901 const char *s = NULL; 902 903 switch(_type) { 904 case _running : s = "_running"; break; 905 case _at_safepoint : s = "_at_safepoint"; break; 906 case _call_back : s = "_call_back"; break; 907 default: 908 ShouldNotReachHere(); 909 } 910 911 st->print_cr("Thread: " INTPTR_FORMAT 912 " [0x%2x] State: %s _has_called_back %d _at_poll_safepoint %d", 913 p2i(_thread), _thread->osthread()->thread_id(), s, _has_called_back, 914 _at_poll_safepoint); 915 916 _thread->print_thread_state_on(st); 917 } 918 919 // --------------------------------------------------------------------------------------------------------------------- 920 921 // Block the thread at the safepoint poll or poll return. 922 void ThreadSafepointState::handle_polling_page_exception() { 923 924 // Check state. block() will set thread state to thread_in_vm which will 925 // cause the safepoint state _type to become _call_back. 926 assert(type() == ThreadSafepointState::_running, 927 "polling page exception on thread not running state"); 928 929 // Step 1: Find the nmethod from the return address 930 if (ShowSafepointMsgs && Verbose) { 931 tty->print_cr("Polling page exception at " INTPTR_FORMAT, p2i(thread()->saved_exception_pc())); 932 } 933 address real_return_addr = thread()->saved_exception_pc(); 934 935 CodeBlob *cb = CodeCache::find_blob(real_return_addr); 936 assert(cb != NULL && cb->is_nmethod(), "return address should be in nmethod"); 937 nmethod* nm = (nmethod*)cb; 938 939 // Find frame of caller 940 frame stub_fr = thread()->last_frame(); 941 CodeBlob* stub_cb = stub_fr.cb(); 942 assert(stub_cb->is_safepoint_stub(), "must be a safepoint stub"); 943 RegisterMap map(thread(), true); 944 frame caller_fr = stub_fr.sender(&map); 945 946 // Should only be poll_return or poll 947 assert( nm->is_at_poll_or_poll_return(real_return_addr), "should not be at call" ); 948 949 // This is a poll immediately before a return. The exception handling code 950 // has already had the effect of causing the return to occur, so the execution 951 // will continue immediately after the call. In addition, the oopmap at the 952 // return point does not mark the return value as an oop (if it is), so 953 // it needs a handle here to be updated. 954 if( nm->is_at_poll_return(real_return_addr) ) { 955 // See if return type is an oop. 956 bool return_oop = nm->method()->is_returning_oop(); 957 Handle return_value; 958 if (return_oop) { 959 // The oop result has been saved on the stack together with all 960 // the other registers. In order to preserve it over GCs we need 961 // to keep it in a handle. 962 oop result = caller_fr.saved_oop_result(&map); 963 assert(result == NULL || result->is_oop(), "must be oop"); 964 return_value = Handle(thread(), result); 965 assert(Universe::heap()->is_in_or_null(result), "must be heap pointer"); 966 } 967 968 // Block the thread 969 SafepointSynchronize::block(thread()); 970 971 // restore oop result, if any 972 if (return_oop) { 973 caller_fr.set_saved_oop_result(&map, return_value()); 974 } 975 } 976 977 // This is a safepoint poll. Verify the return address and block. 978 else { 979 set_at_poll_safepoint(true); 980 981 // verify the blob built the "return address" correctly 982 assert(real_return_addr == caller_fr.pc(), "must match"); 983 984 // Block the thread 985 SafepointSynchronize::block(thread()); 986 set_at_poll_safepoint(false); 987 988 // If we have a pending async exception deoptimize the frame 989 // as otherwise we may never deliver it. 990 if (thread()->has_async_condition()) { 991 ThreadInVMfromJavaNoAsyncException __tiv(thread()); 992 Deoptimization::deoptimize_frame(thread(), caller_fr.id()); 993 } 994 995 // If an exception has been installed we must check for a pending deoptimization 996 // Deoptimize frame if exception has been thrown. 997 998 if (thread()->has_pending_exception() ) { 999 RegisterMap map(thread(), true); 1000 frame caller_fr = stub_fr.sender(&map); 1001 if (caller_fr.is_deoptimized_frame()) { 1002 // The exception patch will destroy registers that are still 1003 // live and will be needed during deoptimization. Defer the 1004 // Async exception should have deferred the exception until the 1005 // next safepoint which will be detected when we get into 1006 // the interpreter so if we have an exception now things 1007 // are messed up. 1008 1009 fatal("Exception installed and deoptimization is pending"); 1010 } 1011 } 1012 } 1013 } 1014 1015 1016 // 1017 // Statistics & Instrumentations 1018 // 1019 SafepointSynchronize::SafepointStats* SafepointSynchronize::_safepoint_stats = NULL; 1020 jlong SafepointSynchronize::_safepoint_begin_time = 0; 1021 int SafepointSynchronize::_cur_stat_index = 0; 1022 julong SafepointSynchronize::_safepoint_reasons[VM_Operation::VMOp_Terminating]; 1023 julong SafepointSynchronize::_coalesced_vmop_count = 0; 1024 jlong SafepointSynchronize::_max_sync_time = 0; 1025 jlong SafepointSynchronize::_max_vmop_time = 0; 1026 float SafepointSynchronize::_ts_of_current_safepoint = 0.0f; 1027 1028 static jlong cleanup_end_time = 0; 1029 static bool need_to_track_page_armed_status = false; 1030 static bool init_done = false; 1031 1032 // Helper method to print the header. 1033 static void print_header() { 1034 tty->print(" vmop " 1035 "[threads: total initially_running wait_to_block] "); 1036 tty->print("[time: spin block sync cleanup vmop] "); 1037 1038 // no page armed status printed out if it is always armed. 1039 if (need_to_track_page_armed_status) { 1040 tty->print("page_armed "); 1041 } 1042 1043 tty->print_cr("page_trap_count"); 1044 } 1045 1046 void SafepointSynchronize::deferred_initialize_stat() { 1047 if (init_done) return; 1048 1049 // If PrintSafepointStatisticsTimeout is specified, the statistics data will 1050 // be printed right away, in which case, _safepoint_stats will regress to 1051 // a single element array. Otherwise, it is a circular ring buffer with default 1052 // size of PrintSafepointStatisticsCount. 1053 int stats_array_size; 1054 if (PrintSafepointStatisticsTimeout > 0) { 1055 stats_array_size = 1; 1056 PrintSafepointStatistics = true; 1057 } else { 1058 stats_array_size = PrintSafepointStatisticsCount; 1059 } 1060 _safepoint_stats = (SafepointStats*)os::malloc(stats_array_size 1061 * sizeof(SafepointStats), mtInternal); 1062 guarantee(_safepoint_stats != NULL, 1063 "not enough memory for safepoint instrumentation data"); 1064 1065 if (DeferPollingPageLoopCount >= 0) { 1066 need_to_track_page_armed_status = true; 1067 } 1068 init_done = true; 1069 } 1070 1071 void SafepointSynchronize::begin_statistics(int nof_threads, int nof_running) { 1072 assert(init_done, "safepoint statistics array hasn't been initialized"); 1073 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; 1074 1075 spstat->_time_stamp = _ts_of_current_safepoint; 1076 1077 VM_Operation *op = VMThread::vm_operation(); 1078 spstat->_vmop_type = (op != NULL ? op->type() : -1); 1079 if (op != NULL) { 1080 _safepoint_reasons[spstat->_vmop_type]++; 1081 } 1082 1083 spstat->_nof_total_threads = nof_threads; 1084 spstat->_nof_initial_running_threads = nof_running; 1085 spstat->_nof_threads_hit_page_trap = 0; 1086 1087 // Records the start time of spinning. The real time spent on spinning 1088 // will be adjusted when spin is done. Same trick is applied for time 1089 // spent on waiting for threads to block. 1090 if (nof_running != 0) { 1091 spstat->_time_to_spin = os::javaTimeNanos(); 1092 } else { 1093 spstat->_time_to_spin = 0; 1094 } 1095 } 1096 1097 void SafepointSynchronize::update_statistics_on_spin_end() { 1098 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; 1099 1100 jlong cur_time = os::javaTimeNanos(); 1101 1102 spstat->_nof_threads_wait_to_block = _waiting_to_block; 1103 if (spstat->_nof_initial_running_threads != 0) { 1104 spstat->_time_to_spin = cur_time - spstat->_time_to_spin; 1105 } 1106 1107 if (need_to_track_page_armed_status) { 1108 spstat->_page_armed = (PageArmed == 1); 1109 } 1110 1111 // Records the start time of waiting for to block. Updated when block is done. 1112 if (_waiting_to_block != 0) { 1113 spstat->_time_to_wait_to_block = cur_time; 1114 } else { 1115 spstat->_time_to_wait_to_block = 0; 1116 } 1117 } 1118 1119 void SafepointSynchronize::update_statistics_on_sync_end(jlong end_time) { 1120 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; 1121 1122 if (spstat->_nof_threads_wait_to_block != 0) { 1123 spstat->_time_to_wait_to_block = end_time - 1124 spstat->_time_to_wait_to_block; 1125 } 1126 1127 // Records the end time of sync which will be used to calculate the total 1128 // vm operation time. Again, the real time spending in syncing will be deducted 1129 // from the start of the sync time later when end_statistics is called. 1130 spstat->_time_to_sync = end_time - _safepoint_begin_time; 1131 if (spstat->_time_to_sync > _max_sync_time) { 1132 _max_sync_time = spstat->_time_to_sync; 1133 } 1134 1135 spstat->_time_to_do_cleanups = end_time; 1136 } 1137 1138 void SafepointSynchronize::update_statistics_on_cleanup_end(jlong end_time) { 1139 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; 1140 1141 // Record how long spent in cleanup tasks. 1142 spstat->_time_to_do_cleanups = end_time - spstat->_time_to_do_cleanups; 1143 1144 cleanup_end_time = end_time; 1145 } 1146 1147 void SafepointSynchronize::end_statistics(jlong vmop_end_time) { 1148 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; 1149 1150 // Update the vm operation time. 1151 spstat->_time_to_exec_vmop = vmop_end_time - cleanup_end_time; 1152 if (spstat->_time_to_exec_vmop > _max_vmop_time) { 1153 _max_vmop_time = spstat->_time_to_exec_vmop; 1154 } 1155 // Only the sync time longer than the specified 1156 // PrintSafepointStatisticsTimeout will be printed out right away. 1157 // By default, it is -1 meaning all samples will be put into the list. 1158 if ( PrintSafepointStatisticsTimeout > 0) { 1159 if (spstat->_time_to_sync > (jlong)PrintSafepointStatisticsTimeout * MICROUNITS) { 1160 print_statistics(); 1161 } 1162 } else { 1163 // The safepoint statistics will be printed out when the _safepoin_stats 1164 // array fills up. 1165 if (_cur_stat_index == PrintSafepointStatisticsCount - 1) { 1166 print_statistics(); 1167 _cur_stat_index = 0; 1168 } else { 1169 _cur_stat_index++; 1170 } 1171 } 1172 } 1173 1174 void SafepointSynchronize::print_statistics() { 1175 SafepointStats* sstats = _safepoint_stats; 1176 1177 for (int index = 0; index <= _cur_stat_index; index++) { 1178 if (index % 30 == 0) { 1179 print_header(); 1180 } 1181 sstats = &_safepoint_stats[index]; 1182 tty->print("%.3f: ", sstats->_time_stamp); 1183 tty->print("%-26s [" 1184 INT32_FORMAT_W(8) INT32_FORMAT_W(11) INT32_FORMAT_W(15) 1185 " ] ", 1186 sstats->_vmop_type == -1 ? "no vm operation" : 1187 VM_Operation::name(sstats->_vmop_type), 1188 sstats->_nof_total_threads, 1189 sstats->_nof_initial_running_threads, 1190 sstats->_nof_threads_wait_to_block); 1191 // "/ MICROUNITS " is to convert the unit from nanos to millis. 1192 tty->print(" [" 1193 INT64_FORMAT_W(6) INT64_FORMAT_W(6) 1194 INT64_FORMAT_W(6) INT64_FORMAT_W(6) 1195 INT64_FORMAT_W(6) " ] ", 1196 sstats->_time_to_spin / MICROUNITS, 1197 sstats->_time_to_wait_to_block / MICROUNITS, 1198 sstats->_time_to_sync / MICROUNITS, 1199 sstats->_time_to_do_cleanups / MICROUNITS, 1200 sstats->_time_to_exec_vmop / MICROUNITS); 1201 1202 if (need_to_track_page_armed_status) { 1203 tty->print(INT32_FORMAT " ", sstats->_page_armed); 1204 } 1205 tty->print_cr(INT32_FORMAT " ", sstats->_nof_threads_hit_page_trap); 1206 } 1207 } 1208 1209 // This method will be called when VM exits. It will first call 1210 // print_statistics to print out the rest of the sampling. Then 1211 // it tries to summarize the sampling. 1212 void SafepointSynchronize::print_stat_on_exit() { 1213 if (_safepoint_stats == NULL) return; 1214 1215 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; 1216 1217 // During VM exit, end_statistics may not get called and in that 1218 // case, if the sync time is less than PrintSafepointStatisticsTimeout, 1219 // don't print it out. 1220 // Approximate the vm op time. 1221 _safepoint_stats[_cur_stat_index]._time_to_exec_vmop = 1222 os::javaTimeNanos() - cleanup_end_time; 1223 1224 if ( PrintSafepointStatisticsTimeout < 0 || 1225 spstat->_time_to_sync > (jlong)PrintSafepointStatisticsTimeout * MICROUNITS) { 1226 print_statistics(); 1227 } 1228 tty->cr(); 1229 1230 // Print out polling page sampling status. 1231 if (!need_to_track_page_armed_status) { 1232 tty->print_cr("Polling page always armed"); 1233 } else { 1234 tty->print_cr("Defer polling page loop count = " INTX_FORMAT "\n", 1235 DeferPollingPageLoopCount); 1236 } 1237 1238 for (int index = 0; index < VM_Operation::VMOp_Terminating; index++) { 1239 if (_safepoint_reasons[index] != 0) { 1240 tty->print_cr("%-26s" UINT64_FORMAT_W(10), VM_Operation::name(index), 1241 _safepoint_reasons[index]); 1242 } 1243 } 1244 1245 tty->print_cr(UINT64_FORMAT_W(5) " VM operations coalesced during safepoint", 1246 _coalesced_vmop_count); 1247 tty->print_cr("Maximum sync time " INT64_FORMAT_W(5) " ms", 1248 _max_sync_time / MICROUNITS); 1249 tty->print_cr("Maximum vm operation time (except for Exit VM operation) " 1250 INT64_FORMAT_W(5) " ms", 1251 _max_vmop_time / MICROUNITS); 1252 } 1253 1254 // ------------------------------------------------------------------------------------------------ 1255 // Non-product code 1256 1257 #ifndef PRODUCT 1258 1259 void SafepointSynchronize::print_state() { 1260 if (_state == _not_synchronized) { 1261 tty->print_cr("not synchronized"); 1262 } else if (_state == _synchronizing || _state == _synchronized) { 1263 tty->print_cr("State: %s", (_state == _synchronizing) ? "synchronizing" : 1264 "synchronized"); 1265 1266 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) { 1267 cur->safepoint_state()->print(); 1268 } 1269 } 1270 } 1271 1272 void SafepointSynchronize::safepoint_msg(const char* format, ...) { 1273 if (ShowSafepointMsgs) { 1274 va_list ap; 1275 va_start(ap, format); 1276 tty->vprint_cr(format, ap); 1277 va_end(ap); 1278 } 1279 } 1280 1281 #endif // !PRODUCT