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/systemDictionary.hpp" 28 #include "code/codeCache.hpp" 29 #include "code/icBuffer.hpp" 30 #include "code/nmethod.hpp" 31 #include "code/pcDesc.hpp" 32 #include "code/scopeDesc.hpp" 33 #include "gc/shared/collectedHeap.hpp" 34 #include "gc/shared/gcLocker.inline.hpp" 35 #include "interpreter/interpreter.hpp" 36 #include "logging/log.hpp" 37 #include "memory/resourceArea.hpp" 38 #include "memory/universe.inline.hpp" 39 #include "oops/oop.inline.hpp" 40 #include "oops/symbol.hpp" 41 #include "runtime/atomic.inline.hpp" 42 #include "runtime/compilationPolicy.hpp" 43 #include "runtime/deoptimization.hpp" 44 #include "runtime/frame.inline.hpp" 45 #include "runtime/interfaceSupport.hpp" 46 #include "runtime/mutexLocker.hpp" 47 #include "runtime/orderAccess.inline.hpp" 48 #include "runtime/osThread.hpp" 49 #include "runtime/safepoint.hpp" 50 #include "runtime/signature.hpp" 51 #include "runtime/stubCodeGenerator.hpp" 52 #include "runtime/stubRoutines.hpp" 53 #include "runtime/sweeper.hpp" 54 #include "runtime/synchronizer.hpp" 55 #include "runtime/thread.inline.hpp" 56 #include "services/runtimeService.hpp" 57 #include "utilities/events.hpp" 58 #include "utilities/macros.hpp" 59 #if INCLUDE_ALL_GCS 60 #include "gc/cms/concurrentMarkSweepThread.hpp" 61 #include "gc/g1/suspendibleThreadSet.hpp" 62 #endif // INCLUDE_ALL_GCS 63 #ifdef COMPILER1 64 #include "c1/c1_globals.hpp" 65 #endif 66 67 // -------------------------------------------------------------------------------------------------- 68 // Implementation of Safepoint begin/end 69 70 SafepointSynchronize::SynchronizeState volatile SafepointSynchronize::_state = SafepointSynchronize::_not_synchronized; 71 volatile int SafepointSynchronize::_waiting_to_block = 0; 72 volatile int SafepointSynchronize::_safepoint_counter = 0; 73 int SafepointSynchronize::_current_jni_active_count = 0; 74 long SafepointSynchronize::_end_of_last_safepoint = 0; 75 static volatile int PageArmed = 0 ; // safepoint polling page is RO|RW vs PROT_NONE 76 static volatile int TryingToBlock = 0 ; // proximate value -- for advisory use only 77 static bool timeout_error_printed = false; 78 79 // Roll all threads forward to a safepoint and suspend them all 80 void SafepointSynchronize::begin() { 81 82 Thread* myThread = Thread::current(); 83 assert(myThread->is_VM_thread(), "Only VM thread may execute a safepoint"); 84 85 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) { 86 _safepoint_begin_time = os::javaTimeNanos(); 87 _ts_of_current_safepoint = tty->time_stamp().seconds(); 88 } 89 90 #if INCLUDE_ALL_GCS 91 if (UseConcMarkSweepGC) { 92 // In the future we should investigate whether CMS can use the 93 // more-general mechanism below. DLD (01/05). 94 ConcurrentMarkSweepThread::synchronize(false); 95 } else if (UseG1GC) { 96 SuspendibleThreadSet::synchronize(); 97 } 98 #endif // INCLUDE_ALL_GCS 99 100 // By getting the Threads_lock, we assure that no threads are about to start or 101 // exit. It is released again in SafepointSynchronize::end(). 102 Threads_lock->lock(); 103 104 assert( _state == _not_synchronized, "trying to safepoint synchronize with wrong state"); 105 106 int nof_threads = Threads::number_of_threads(); 107 108 log_debug(safepoint)("Safepoint synchronization initiated. (%d)", nof_threads); 109 110 RuntimeService::record_safepoint_begin(); 111 112 MutexLocker mu(Safepoint_lock); 113 114 // Reset the count of active JNI critical threads 115 _current_jni_active_count = 0; 116 117 // Set number of threads to wait for, before we initiate the callbacks 118 _waiting_to_block = nof_threads; 119 TryingToBlock = 0 ; 120 int still_running = nof_threads; 121 122 // Save the starting time, so that it can be compared to see if this has taken 123 // too long to complete. 124 jlong safepoint_limit_time = 0; 125 timeout_error_printed = false; 126 127 // PrintSafepointStatisticsTimeout can be specified separately. When 128 // specified, PrintSafepointStatistics will be set to true in 129 // deferred_initialize_stat method. The initialization has to be done 130 // early enough to avoid any races. See bug 6880029 for details. 131 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) { 132 deferred_initialize_stat(); 133 } 134 135 // Begin the process of bringing the system to a safepoint. 136 // Java threads can be in several different states and are 137 // stopped by different mechanisms: 138 // 139 // 1. Running interpreted 140 // The interpreter dispatch table is changed to force it to 141 // check for a safepoint condition between bytecodes. 142 // 2. Running in native code 143 // When returning from the native code, a Java thread must check 144 // the safepoint _state to see if we must block. If the 145 // VM thread sees a Java thread in native, it does 146 // not wait for this thread to block. The order of the memory 147 // writes and reads of both the safepoint state and the Java 148 // threads state is critical. In order to guarantee that the 149 // memory writes are serialized with respect to each other, 150 // the VM thread issues a memory barrier instruction 151 // (on MP systems). In order to avoid the overhead of issuing 152 // a memory barrier for each Java thread making native calls, each Java 153 // thread performs a write to a single memory page after changing 154 // the thread state. The VM thread performs a sequence of 155 // mprotect OS calls which forces all previous writes from all 156 // Java threads to be serialized. This is done in the 157 // os::serialize_thread_states() call. This has proven to be 158 // much more efficient than executing a membar instruction 159 // on every call to native code. 160 // 3. Running compiled Code 161 // Compiled code reads a global (Safepoint Polling) page that 162 // is set to fault if we are trying to get to a safepoint. 163 // 4. Blocked 164 // A thread which is blocked will not be allowed to return from the 165 // block condition until the safepoint operation is complete. 166 // 5. In VM or Transitioning between states 167 // If a Java thread is currently running in the VM or transitioning 168 // between states, the safepointing code will wait for the thread to 169 // block itself when it attempts transitions to a new state. 170 // 171 _state = _synchronizing; 172 OrderAccess::fence(); 173 174 // Flush all thread states to memory 175 if (!UseMembar) { 176 os::serialize_thread_states(); 177 } 178 179 // Make interpreter safepoint aware 180 Interpreter::notice_safepoints(); 181 182 if (DeferPollingPageLoopCount < 0) { 183 // Make polling safepoint aware 184 guarantee (PageArmed == 0, "invariant") ; 185 PageArmed = 1 ; 186 os::make_polling_page_unreadable(); 187 } 188 189 // Consider using active_processor_count() ... but that call is expensive. 190 int ncpus = os::processor_count() ; 191 192 #ifdef ASSERT 193 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) { 194 assert(cur->safepoint_state()->is_running(), "Illegal initial state"); 195 // Clear the visited flag to ensure that the critical counts are collected properly. 196 cur->set_visited_for_critical_count(false); 197 } 198 #endif // ASSERT 199 200 if (SafepointTimeout) 201 safepoint_limit_time = os::javaTimeNanos() + (jlong)SafepointTimeoutDelay * MICROUNITS; 202 203 // Iterate through all threads until it have been determined how to stop them all at a safepoint 204 unsigned int iterations = 0; 205 int steps = 0 ; 206 while(still_running > 0) { 207 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) { 208 assert(!cur->is_ConcurrentGC_thread(), "A concurrent GC thread is unexpectly being suspended"); 209 ThreadSafepointState *cur_state = cur->safepoint_state(); 210 if (cur_state->is_running()) { 211 cur_state->examine_state_of_thread(); 212 if (!cur_state->is_running()) { 213 still_running--; 214 // consider adjusting steps downward: 215 // steps = 0 216 // steps -= NNN 217 // steps >>= 1 218 // steps = MIN(steps, 2000-100) 219 // if (iterations != 0) steps -= NNN 220 } 221 if (log_is_enabled(Trace, safepoint)) { 222 ResourceMark rm; 223 cur_state->print_on(LogHandle(safepoint)::debug_stream()); 224 } 225 } 226 } 227 228 if (PrintSafepointStatistics && iterations == 0) { 229 begin_statistics(nof_threads, still_running); 230 } 231 232 if (still_running > 0) { 233 // Check for if it takes to long 234 if (SafepointTimeout && safepoint_limit_time < os::javaTimeNanos()) { 235 print_safepoint_timeout(_spinning_timeout); 236 } 237 238 // Spin to avoid context switching. 239 // There's a tension between allowing the mutators to run (and rendezvous) 240 // vs spinning. As the VM thread spins, wasting cycles, it consumes CPU that 241 // a mutator might otherwise use profitably to reach a safepoint. Excessive 242 // spinning by the VM thread on a saturated system can increase rendezvous latency. 243 // Blocking or yielding incur their own penalties in the form of context switching 244 // and the resultant loss of $ residency. 245 // 246 // Further complicating matters is that yield() does not work as naively expected 247 // on many platforms -- yield() does not guarantee that any other ready threads 248 // will run. As such we revert to naked_short_sleep() after some number of iterations. 249 // nakes_short_sleep() is implemented as a short unconditional sleep. 250 // Typical operating systems round a "short" sleep period up to 10 msecs, so sleeping 251 // can actually increase the time it takes the VM thread to detect that a system-wide 252 // stop-the-world safepoint has been reached. In a pathological scenario such as that 253 // described in CR6415670 the VMthread may sleep just before the mutator(s) become safe. 254 // In that case the mutators will be stalled waiting for the safepoint to complete and the 255 // the VMthread will be sleeping, waiting for the mutators to rendezvous. The VMthread 256 // will eventually wake up and detect that all mutators are safe, at which point 257 // we'll again make progress. 258 // 259 // Beware too that that the VMThread typically runs at elevated priority. 260 // Its default priority is higher than the default mutator priority. 261 // Obviously, this complicates spinning. 262 // 263 // Note too that on Windows XP SwitchThreadTo() has quite different behavior than Sleep(0). 264 // Sleep(0) will _not yield to lower priority threads, while SwitchThreadTo() will. 265 // 266 // See the comments in synchronizer.cpp for additional remarks on spinning. 267 // 268 // In the future we might: 269 // 1. Modify the safepoint scheme to avoid potentially unbounded spinning. 270 // This is tricky as the path used by a thread exiting the JVM (say on 271 // on JNI call-out) simply stores into its state field. The burden 272 // is placed on the VM thread, which must poll (spin). 273 // 2. Find something useful to do while spinning. If the safepoint is GC-related 274 // we might aggressively scan the stacks of threads that are already safe. 275 // 3. Use Solaris schedctl to examine the state of the still-running mutators. 276 // If all the mutators are ONPROC there's no reason to sleep or yield. 277 // 4. YieldTo() any still-running mutators that are ready but OFFPROC. 278 // 5. Check system saturation. If the system is not fully saturated then 279 // simply spin and avoid sleep/yield. 280 // 6. As still-running mutators rendezvous they could unpark the sleeping 281 // VMthread. This works well for still-running mutators that become 282 // safe. The VMthread must still poll for mutators that call-out. 283 // 7. Drive the policy on time-since-begin instead of iterations. 284 // 8. Consider making the spin duration a function of the # of CPUs: 285 // Spin = (((ncpus-1) * M) + K) + F(still_running) 286 // Alternately, instead of counting iterations of the outer loop 287 // we could count the # of threads visited in the inner loop, above. 288 // 9. On windows consider using the return value from SwitchThreadTo() 289 // to drive subsequent spin/SwitchThreadTo()/Sleep(N) decisions. 290 291 if (int(iterations) == DeferPollingPageLoopCount) { 292 guarantee (PageArmed == 0, "invariant") ; 293 PageArmed = 1 ; 294 os::make_polling_page_unreadable(); 295 } 296 297 // Instead of (ncpus > 1) consider either (still_running < (ncpus + EPSILON)) or 298 // ((still_running + _waiting_to_block - TryingToBlock)) < ncpus) 299 ++steps ; 300 if (ncpus > 1 && steps < SafepointSpinBeforeYield) { 301 SpinPause() ; // MP-Polite spin 302 } else 303 if (steps < DeferThrSuspendLoopCount) { 304 os::naked_yield() ; 305 } else { 306 os::naked_short_sleep(1); 307 } 308 309 iterations ++ ; 310 } 311 assert(iterations < (uint)max_jint, "We have been iterating in the safepoint loop too long"); 312 } 313 assert(still_running == 0, "sanity check"); 314 315 if (PrintSafepointStatistics) { 316 update_statistics_on_spin_end(); 317 } 318 319 // wait until all threads are stopped 320 while (_waiting_to_block > 0) { 321 log_debug(safepoint)("Waiting for %d thread(s) to block", _waiting_to_block); 322 if (!SafepointTimeout || timeout_error_printed) { 323 Safepoint_lock->wait(true); // true, means with no safepoint checks 324 } else { 325 // Compute remaining time 326 jlong remaining_time = safepoint_limit_time - os::javaTimeNanos(); 327 328 // If there is no remaining time, then there is an error 329 if (remaining_time < 0 || Safepoint_lock->wait(true, remaining_time / MICROUNITS)) { 330 print_safepoint_timeout(_blocking_timeout); 331 } 332 } 333 } 334 assert(_waiting_to_block == 0, "sanity check"); 335 336 #ifndef PRODUCT 337 if (SafepointTimeout) { 338 jlong current_time = os::javaTimeNanos(); 339 if (safepoint_limit_time < current_time) { 340 tty->print_cr("# SafepointSynchronize: Finished after " 341 INT64_FORMAT_W(6) " ms", 342 ((current_time - safepoint_limit_time) / MICROUNITS + 343 (jlong)SafepointTimeoutDelay)); 344 } 345 } 346 #endif 347 348 assert((_safepoint_counter & 0x1) == 0, "must be even"); 349 assert(Threads_lock->owned_by_self(), "must hold Threads_lock"); 350 _safepoint_counter ++; 351 352 // Record state 353 _state = _synchronized; 354 355 OrderAccess::fence(); 356 357 #ifdef ASSERT 358 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) { 359 // make sure all the threads were visited 360 assert(cur->was_visited_for_critical_count(), "missed a thread"); 361 } 362 #endif // ASSERT 363 364 // Update the count of active JNI critical regions 365 GC_locker::set_jni_lock_count(_current_jni_active_count); 366 367 if (log_is_enabled(Debug, safepoint)) { 368 VM_Operation *op = VMThread::vm_operation(); 369 log_debug(safepoint)("Entering safepoint region: %s", 370 (op != NULL) ? op->name() : "no vm operation"); 371 } 372 373 RuntimeService::record_safepoint_synchronized(); 374 if (PrintSafepointStatistics) { 375 update_statistics_on_sync_end(os::javaTimeNanos()); 376 } 377 378 // Call stuff that needs to be run when a safepoint is just about to be completed 379 do_cleanup_tasks(); 380 381 if (PrintSafepointStatistics) { 382 // Record how much time spend on the above cleanup tasks 383 update_statistics_on_cleanup_end(os::javaTimeNanos()); 384 } 385 } 386 387 // Wake up all threads, so they are ready to resume execution after the safepoint 388 // operation has been carried out 389 void SafepointSynchronize::end() { 390 391 assert(Threads_lock->owned_by_self(), "must hold Threads_lock"); 392 assert((_safepoint_counter & 0x1) == 1, "must be odd"); 393 _safepoint_counter ++; 394 // memory fence isn't required here since an odd _safepoint_counter 395 // value can do no harm and a fence is issued below anyway. 396 397 DEBUG_ONLY(Thread* myThread = Thread::current();) 398 assert(myThread->is_VM_thread(), "Only VM thread can execute a safepoint"); 399 400 if (PrintSafepointStatistics) { 401 end_statistics(os::javaTimeNanos()); 402 } 403 404 #ifdef ASSERT 405 // A pending_exception cannot be installed during a safepoint. The threads 406 // may install an async exception after they come back from a safepoint into 407 // pending_exception after they unblock. But that should happen later. 408 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) { 409 assert (!(cur->has_pending_exception() && 410 cur->safepoint_state()->is_at_poll_safepoint()), 411 "safepoint installed a pending exception"); 412 } 413 #endif // ASSERT 414 415 if (PageArmed) { 416 // Make polling safepoint aware 417 os::make_polling_page_readable(); 418 PageArmed = 0 ; 419 } 420 421 // Remove safepoint check from interpreter 422 Interpreter::ignore_safepoints(); 423 424 { 425 MutexLocker mu(Safepoint_lock); 426 427 assert(_state == _synchronized, "must be synchronized before ending safepoint synchronization"); 428 429 // Set to not synchronized, so the threads will not go into the signal_thread_blocked method 430 // when they get restarted. 431 _state = _not_synchronized; 432 OrderAccess::fence(); 433 434 log_debug(safepoint)("Leaving safepoint region"); 435 436 // Start suspended threads 437 for(JavaThread *current = Threads::first(); current; current = current->next()) { 438 // A problem occurring on Solaris is when attempting to restart threads 439 // the first #cpus - 1 go well, but then the VMThread is preempted when we get 440 // to the next one (since it has been running the longest). We then have 441 // to wait for a cpu to become available before we can continue restarting 442 // threads. 443 // FIXME: This causes the performance of the VM to degrade when active and with 444 // large numbers of threads. Apparently this is due to the synchronous nature 445 // of suspending threads. 446 // 447 // TODO-FIXME: the comments above are vestigial and no longer apply. 448 // Furthermore, using solaris' schedctl in this particular context confers no benefit 449 if (VMThreadHintNoPreempt) { 450 os::hint_no_preempt(); 451 } 452 ThreadSafepointState* cur_state = current->safepoint_state(); 453 assert(cur_state->type() != ThreadSafepointState::_running, "Thread not suspended at safepoint"); 454 cur_state->restart(); 455 assert(cur_state->is_running(), "safepoint state has not been reset"); 456 } 457 458 RuntimeService::record_safepoint_end(); 459 460 // Release threads lock, so threads can be created/destroyed again. It will also starts all threads 461 // blocked in signal_thread_blocked 462 Threads_lock->unlock(); 463 464 } 465 #if INCLUDE_ALL_GCS 466 // If there are any concurrent GC threads resume them. 467 if (UseConcMarkSweepGC) { 468 ConcurrentMarkSweepThread::desynchronize(false); 469 } else if (UseG1GC) { 470 SuspendibleThreadSet::desynchronize(); 471 } 472 #endif // INCLUDE_ALL_GCS 473 // record this time so VMThread can keep track how much time has elapsed 474 // since last safepoint. 475 _end_of_last_safepoint = os::javaTimeMillis(); 476 } 477 478 bool SafepointSynchronize::is_cleanup_needed() { 479 // Need a safepoint if some inline cache buffers is non-empty 480 if (!InlineCacheBuffer::is_empty()) return true; 481 return false; 482 } 483 484 485 486 // Various cleaning tasks that should be done periodically at safepoints 487 void SafepointSynchronize::do_cleanup_tasks() { 488 { 489 TraceTime t1("deflating idle monitors", TraceSafepointCleanupTime); 490 ObjectSynchronizer::deflate_idle_monitors(); 491 } 492 493 { 494 TraceTime t2("updating inline caches", TraceSafepointCleanupTime); 495 InlineCacheBuffer::update_inline_caches(); 496 } 497 { 498 TraceTime t3("compilation policy safepoint handler", TraceSafepointCleanupTime); 499 CompilationPolicy::policy()->do_safepoint_work(); 500 } 501 502 { 503 TraceTime t4("mark nmethods", TraceSafepointCleanupTime); 504 NMethodSweeper::mark_active_nmethods(); 505 } 506 507 if (SymbolTable::needs_rehashing()) { 508 TraceTime t5("rehashing symbol table", TraceSafepointCleanupTime); 509 SymbolTable::rehash_table(); 510 } 511 512 if (StringTable::needs_rehashing()) { 513 TraceTime t6("rehashing string table", TraceSafepointCleanupTime); 514 StringTable::rehash_table(); 515 } 516 517 // rotate log files? 518 if (UseGCLogFileRotation) { 519 gclog_or_tty->rotate_log(false); 520 } 521 522 { 523 // CMS delays purging the CLDG until the beginning of the next safepoint and to 524 // make sure concurrent sweep is done 525 TraceTime t7("purging class loader data graph", TraceSafepointCleanupTime); 526 ClassLoaderDataGraph::purge_if_needed(); 527 } 528 } 529 530 531 bool SafepointSynchronize::safepoint_safe(JavaThread *thread, JavaThreadState state) { 532 switch(state) { 533 case _thread_in_native: 534 // native threads are safe if they have no java stack or have walkable stack 535 return !thread->has_last_Java_frame() || thread->frame_anchor()->walkable(); 536 537 // blocked threads should have already have walkable stack 538 case _thread_blocked: 539 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "blocked and not walkable"); 540 return true; 541 542 default: 543 return false; 544 } 545 } 546 547 548 // See if the thread is running inside a lazy critical native and 549 // update the thread critical count if so. Also set a suspend flag to 550 // cause the native wrapper to return into the JVM to do the unlock 551 // once the native finishes. 552 void SafepointSynchronize::check_for_lazy_critical_native(JavaThread *thread, JavaThreadState state) { 553 if (state == _thread_in_native && 554 thread->has_last_Java_frame() && 555 thread->frame_anchor()->walkable()) { 556 // This thread might be in a critical native nmethod so look at 557 // the top of the stack and increment the critical count if it 558 // is. 559 frame wrapper_frame = thread->last_frame(); 560 CodeBlob* stub_cb = wrapper_frame.cb(); 561 if (stub_cb != NULL && 562 stub_cb->is_nmethod() && 563 stub_cb->as_nmethod_or_null()->is_lazy_critical_native()) { 564 // A thread could potentially be in a critical native across 565 // more than one safepoint, so only update the critical state on 566 // the first one. When it returns it will perform the unlock. 567 if (!thread->do_critical_native_unlock()) { 568 #ifdef ASSERT 569 if (!thread->in_critical()) { 570 GC_locker::increment_debug_jni_lock_count(); 571 } 572 #endif 573 thread->enter_critical(); 574 // Make sure the native wrapper calls back on return to 575 // perform the needed critical unlock. 576 thread->set_critical_native_unlock(); 577 } 578 } 579 } 580 } 581 582 583 584 // ------------------------------------------------------------------------------------------------------- 585 // Implementation of Safepoint callback point 586 587 void SafepointSynchronize::block(JavaThread *thread) { 588 assert(thread != NULL, "thread must be set"); 589 assert(thread->is_Java_thread(), "not a Java thread"); 590 591 // Threads shouldn't block if they are in the middle of printing, but... 592 ttyLocker::break_tty_lock_for_safepoint(os::current_thread_id()); 593 594 // Only bail from the block() call if the thread is gone from the 595 // thread list; starting to exit should still block. 596 if (thread->is_terminated()) { 597 // block current thread if we come here from native code when VM is gone 598 thread->block_if_vm_exited(); 599 600 // otherwise do nothing 601 return; 602 } 603 604 JavaThreadState state = thread->thread_state(); 605 thread->frame_anchor()->make_walkable(thread); 606 607 // Check that we have a valid thread_state at this point 608 switch(state) { 609 case _thread_in_vm_trans: 610 case _thread_in_Java: // From compiled code 611 612 // We are highly likely to block on the Safepoint_lock. In order to avoid blocking in this case, 613 // we pretend we are still in the VM. 614 thread->set_thread_state(_thread_in_vm); 615 616 if (is_synchronizing()) { 617 Atomic::inc (&TryingToBlock) ; 618 } 619 620 // We will always be holding the Safepoint_lock when we are examine the state 621 // of a thread. Hence, the instructions between the Safepoint_lock->lock() and 622 // Safepoint_lock->unlock() are happening atomic with regards to the safepoint code 623 Safepoint_lock->lock_without_safepoint_check(); 624 if (is_synchronizing()) { 625 // Decrement the number of threads to wait for and signal vm thread 626 assert(_waiting_to_block > 0, "sanity check"); 627 _waiting_to_block--; 628 thread->safepoint_state()->set_has_called_back(true); 629 630 DEBUG_ONLY(thread->set_visited_for_critical_count(true)); 631 if (thread->in_critical()) { 632 // Notice that this thread is in a critical section 633 increment_jni_active_count(); 634 } 635 636 // Consider (_waiting_to_block < 2) to pipeline the wakeup of the VM thread 637 if (_waiting_to_block == 0) { 638 Safepoint_lock->notify_all(); 639 } 640 } 641 642 // We transition the thread to state _thread_blocked here, but 643 // we can't do our usual check for external suspension and then 644 // self-suspend after the lock_without_safepoint_check() call 645 // below because we are often called during transitions while 646 // we hold different locks. That would leave us suspended while 647 // holding a resource which results in deadlocks. 648 thread->set_thread_state(_thread_blocked); 649 Safepoint_lock->unlock(); 650 651 // We now try to acquire the threads lock. Since this lock is hold by the VM thread during 652 // the entire safepoint, the threads will all line up here during the safepoint. 653 Threads_lock->lock_without_safepoint_check(); 654 // restore original state. This is important if the thread comes from compiled code, so it 655 // will continue to execute with the _thread_in_Java state. 656 thread->set_thread_state(state); 657 Threads_lock->unlock(); 658 break; 659 660 case _thread_in_native_trans: 661 case _thread_blocked_trans: 662 case _thread_new_trans: 663 if (thread->safepoint_state()->type() == ThreadSafepointState::_call_back) { 664 thread->print_thread_state(); 665 fatal("Deadlock in safepoint code. " 666 "Should have called back to the VM before blocking."); 667 } 668 669 // We transition the thread to state _thread_blocked here, but 670 // we can't do our usual check for external suspension and then 671 // self-suspend after the lock_without_safepoint_check() call 672 // below because we are often called during transitions while 673 // we hold different locks. That would leave us suspended while 674 // holding a resource which results in deadlocks. 675 thread->set_thread_state(_thread_blocked); 676 677 // It is not safe to suspend a thread if we discover it is in _thread_in_native_trans. Hence, 678 // the safepoint code might still be waiting for it to block. We need to change the state here, 679 // so it can see that it is at a safepoint. 680 681 // Block until the safepoint operation is completed. 682 Threads_lock->lock_without_safepoint_check(); 683 684 // Restore state 685 thread->set_thread_state(state); 686 687 Threads_lock->unlock(); 688 break; 689 690 default: 691 fatal("Illegal threadstate encountered: %d", state); 692 } 693 694 // Check for pending. async. exceptions or suspends - except if the 695 // thread was blocked inside the VM. has_special_runtime_exit_condition() 696 // is called last since it grabs a lock and we only want to do that when 697 // we must. 698 // 699 // Note: we never deliver an async exception at a polling point as the 700 // compiler may not have an exception handler for it. The polling 701 // code will notice the async and deoptimize and the exception will 702 // be delivered. (Polling at a return point is ok though). Sure is 703 // a lot of bother for a deprecated feature... 704 // 705 // We don't deliver an async exception if the thread state is 706 // _thread_in_native_trans so JNI functions won't be called with 707 // a surprising pending exception. If the thread state is going back to java, 708 // async exception is checked in check_special_condition_for_native_trans(). 709 710 if (state != _thread_blocked_trans && 711 state != _thread_in_vm_trans && 712 thread->has_special_runtime_exit_condition()) { 713 thread->handle_special_runtime_exit_condition( 714 !thread->is_at_poll_safepoint() && (state != _thread_in_native_trans)); 715 } 716 } 717 718 // ------------------------------------------------------------------------------------------------------ 719 // Exception handlers 720 721 722 void SafepointSynchronize::handle_polling_page_exception(JavaThread *thread) { 723 assert(thread->is_Java_thread(), "polling reference encountered by VM thread"); 724 assert(thread->thread_state() == _thread_in_Java, "should come from Java code"); 725 assert(SafepointSynchronize::is_synchronizing(), "polling encountered outside safepoint synchronization"); 726 727 if (ShowSafepointMsgs) { 728 tty->print("handle_polling_page_exception: "); 729 } 730 731 if (PrintSafepointStatistics) { 732 inc_page_trap_count(); 733 } 734 735 ThreadSafepointState* state = thread->safepoint_state(); 736 737 state->handle_polling_page_exception(); 738 } 739 740 741 void SafepointSynchronize::print_safepoint_timeout(SafepointTimeoutReason reason) { 742 if (!timeout_error_printed) { 743 timeout_error_printed = true; 744 // Print out the thread info which didn't reach the safepoint for debugging 745 // purposes (useful when there are lots of threads in the debugger). 746 tty->cr(); 747 tty->print_cr("# SafepointSynchronize::begin: Timeout detected:"); 748 if (reason == _spinning_timeout) { 749 tty->print_cr("# SafepointSynchronize::begin: Timed out while spinning to reach a safepoint."); 750 } else if (reason == _blocking_timeout) { 751 tty->print_cr("# SafepointSynchronize::begin: Timed out while waiting for threads to stop."); 752 } 753 754 tty->print_cr("# SafepointSynchronize::begin: Threads which did not reach the safepoint:"); 755 ThreadSafepointState *cur_state; 756 ResourceMark rm; 757 for(JavaThread *cur_thread = Threads::first(); cur_thread; 758 cur_thread = cur_thread->next()) { 759 cur_state = cur_thread->safepoint_state(); 760 761 if (cur_thread->thread_state() != _thread_blocked && 762 ((reason == _spinning_timeout && cur_state->is_running()) || 763 (reason == _blocking_timeout && !cur_state->has_called_back()))) { 764 tty->print("# "); 765 cur_thread->print(); 766 tty->cr(); 767 } 768 } 769 tty->print_cr("# SafepointSynchronize::begin: (End of list)"); 770 } 771 772 // To debug the long safepoint, specify both DieOnSafepointTimeout & 773 // ShowMessageBoxOnError. 774 if (DieOnSafepointTimeout) { 775 VM_Operation *op = VMThread::vm_operation(); 776 fatal("Safepoint sync time longer than " INTX_FORMAT "ms detected when executing %s.", 777 SafepointTimeoutDelay, 778 op != NULL ? op->name() : "no vm operation"); 779 } 780 } 781 782 783 // ------------------------------------------------------------------------------------------------------- 784 // Implementation of ThreadSafepointState 785 786 ThreadSafepointState::ThreadSafepointState(JavaThread *thread) { 787 _thread = thread; 788 _type = _running; 789 _has_called_back = false; 790 _at_poll_safepoint = false; 791 } 792 793 void ThreadSafepointState::create(JavaThread *thread) { 794 ThreadSafepointState *state = new ThreadSafepointState(thread); 795 thread->set_safepoint_state(state); 796 } 797 798 void ThreadSafepointState::destroy(JavaThread *thread) { 799 if (thread->safepoint_state()) { 800 delete(thread->safepoint_state()); 801 thread->set_safepoint_state(NULL); 802 } 803 } 804 805 void ThreadSafepointState::examine_state_of_thread() { 806 assert(is_running(), "better be running or just have hit safepoint poll"); 807 808 JavaThreadState state = _thread->thread_state(); 809 810 // Save the state at the start of safepoint processing. 811 _orig_thread_state = state; 812 813 // Check for a thread that is suspended. Note that thread resume tries 814 // to grab the Threads_lock which we own here, so a thread cannot be 815 // resumed during safepoint synchronization. 816 817 // We check to see if this thread is suspended without locking to 818 // avoid deadlocking with a third thread that is waiting for this 819 // thread to be suspended. The third thread can notice the safepoint 820 // that we're trying to start at the beginning of its SR_lock->wait() 821 // call. If that happens, then the third thread will block on the 822 // safepoint while still holding the underlying SR_lock. We won't be 823 // able to get the SR_lock and we'll deadlock. 824 // 825 // We don't need to grab the SR_lock here for two reasons: 826 // 1) The suspend flags are both volatile and are set with an 827 // Atomic::cmpxchg() call so we should see the suspended 828 // state right away. 829 // 2) We're being called from the safepoint polling loop; if 830 // we don't see the suspended state on this iteration, then 831 // we'll come around again. 832 // 833 bool is_suspended = _thread->is_ext_suspended(); 834 if (is_suspended) { 835 roll_forward(_at_safepoint); 836 return; 837 } 838 839 // Some JavaThread states have an initial safepoint state of 840 // running, but are actually at a safepoint. We will happily 841 // agree and update the safepoint state here. 842 if (SafepointSynchronize::safepoint_safe(_thread, state)) { 843 SafepointSynchronize::check_for_lazy_critical_native(_thread, state); 844 roll_forward(_at_safepoint); 845 return; 846 } 847 848 if (state == _thread_in_vm) { 849 roll_forward(_call_back); 850 return; 851 } 852 853 // All other thread states will continue to run until they 854 // transition and self-block in state _blocked 855 // Safepoint polling in compiled code causes the Java threads to do the same. 856 // Note: new threads may require a malloc so they must be allowed to finish 857 858 assert(is_running(), "examine_state_of_thread on non-running thread"); 859 return; 860 } 861 862 // Returns true is thread could not be rolled forward at present position. 863 void ThreadSafepointState::roll_forward(suspend_type type) { 864 _type = type; 865 866 switch(_type) { 867 case _at_safepoint: 868 SafepointSynchronize::signal_thread_at_safepoint(); 869 DEBUG_ONLY(_thread->set_visited_for_critical_count(true)); 870 if (_thread->in_critical()) { 871 // Notice that this thread is in a critical section 872 SafepointSynchronize::increment_jni_active_count(); 873 } 874 break; 875 876 case _call_back: 877 set_has_called_back(false); 878 break; 879 880 case _running: 881 default: 882 ShouldNotReachHere(); 883 } 884 } 885 886 void ThreadSafepointState::restart() { 887 switch(type()) { 888 case _at_safepoint: 889 case _call_back: 890 break; 891 892 case _running: 893 default: 894 tty->print_cr("restart thread " INTPTR_FORMAT " with state %d", 895 p2i(_thread), _type); 896 _thread->print(); 897 ShouldNotReachHere(); 898 } 899 _type = _running; 900 set_has_called_back(false); 901 } 902 903 904 void ThreadSafepointState::print_on(outputStream *st) const { 905 const char *s = NULL; 906 907 switch(_type) { 908 case _running : s = "_running"; break; 909 case _at_safepoint : s = "_at_safepoint"; break; 910 case _call_back : s = "_call_back"; break; 911 default: 912 ShouldNotReachHere(); 913 } 914 915 st->print_cr("Thread: " INTPTR_FORMAT 916 " [0x%2x] State: %s _has_called_back %d _at_poll_safepoint %d", 917 p2i(_thread), _thread->osthread()->thread_id(), s, _has_called_back, 918 _at_poll_safepoint); 919 920 _thread->print_thread_state_on(st); 921 } 922 923 // --------------------------------------------------------------------------------------------------------------------- 924 925 // Block the thread at the safepoint poll or poll return. 926 void ThreadSafepointState::handle_polling_page_exception() { 927 928 // Check state. block() will set thread state to thread_in_vm which will 929 // cause the safepoint state _type to become _call_back. 930 assert(type() == ThreadSafepointState::_running, 931 "polling page exception on thread not running state"); 932 933 // Step 1: Find the nmethod from the return address 934 if (ShowSafepointMsgs && Verbose) { 935 tty->print_cr("Polling page exception at " INTPTR_FORMAT, p2i(thread()->saved_exception_pc())); 936 } 937 address real_return_addr = thread()->saved_exception_pc(); 938 939 CodeBlob *cb = CodeCache::find_blob(real_return_addr); 940 assert(cb != NULL && cb->is_nmethod(), "return address should be in nmethod"); 941 nmethod* nm = (nmethod*)cb; 942 943 // Find frame of caller 944 frame stub_fr = thread()->last_frame(); 945 CodeBlob* stub_cb = stub_fr.cb(); 946 assert(stub_cb->is_safepoint_stub(), "must be a safepoint stub"); 947 RegisterMap map(thread(), true); 948 frame caller_fr = stub_fr.sender(&map); 949 950 // Should only be poll_return or poll 951 assert( nm->is_at_poll_or_poll_return(real_return_addr), "should not be at call" ); 952 953 // This is a poll immediately before a return. The exception handling code 954 // has already had the effect of causing the return to occur, so the execution 955 // will continue immediately after the call. In addition, the oopmap at the 956 // return point does not mark the return value as an oop (if it is), so 957 // it needs a handle here to be updated. 958 if( nm->is_at_poll_return(real_return_addr) ) { 959 // See if return type is an oop. 960 bool return_oop = nm->method()->is_returning_oop(); 961 Handle return_value; 962 if (return_oop) { 963 // The oop result has been saved on the stack together with all 964 // the other registers. In order to preserve it over GCs we need 965 // to keep it in a handle. 966 oop result = caller_fr.saved_oop_result(&map); 967 assert(result == NULL || result->is_oop(), "must be oop"); 968 return_value = Handle(thread(), result); 969 assert(Universe::heap()->is_in_or_null(result), "must be heap pointer"); 970 } 971 972 // Block the thread 973 SafepointSynchronize::block(thread()); 974 975 // restore oop result, if any 976 if (return_oop) { 977 caller_fr.set_saved_oop_result(&map, return_value()); 978 } 979 } 980 981 // This is a safepoint poll. Verify the return address and block. 982 else { 983 set_at_poll_safepoint(true); 984 985 // verify the blob built the "return address" correctly 986 assert(real_return_addr == caller_fr.pc(), "must match"); 987 988 // Block the thread 989 SafepointSynchronize::block(thread()); 990 set_at_poll_safepoint(false); 991 992 // If we have a pending async exception deoptimize the frame 993 // as otherwise we may never deliver it. 994 if (thread()->has_async_condition()) { 995 ThreadInVMfromJavaNoAsyncException __tiv(thread()); 996 Deoptimization::deoptimize_frame(thread(), caller_fr.id()); 997 } 998 999 // If an exception has been installed we must check for a pending deoptimization 1000 // Deoptimize frame if exception has been thrown. 1001 1002 if (thread()->has_pending_exception() ) { 1003 RegisterMap map(thread(), true); 1004 frame caller_fr = stub_fr.sender(&map); 1005 if (caller_fr.is_deoptimized_frame()) { 1006 // The exception patch will destroy registers that are still 1007 // live and will be needed during deoptimization. Defer the 1008 // Async exception should have deferred the exception until the 1009 // next safepoint which will be detected when we get into 1010 // the interpreter so if we have an exception now things 1011 // are messed up. 1012 1013 fatal("Exception installed and deoptimization is pending"); 1014 } 1015 } 1016 } 1017 } 1018 1019 1020 // 1021 // Statistics & Instrumentations 1022 // 1023 SafepointSynchronize::SafepointStats* SafepointSynchronize::_safepoint_stats = NULL; 1024 jlong SafepointSynchronize::_safepoint_begin_time = 0; 1025 int SafepointSynchronize::_cur_stat_index = 0; 1026 julong SafepointSynchronize::_safepoint_reasons[VM_Operation::VMOp_Terminating]; 1027 julong SafepointSynchronize::_coalesced_vmop_count = 0; 1028 jlong SafepointSynchronize::_max_sync_time = 0; 1029 jlong SafepointSynchronize::_max_vmop_time = 0; 1030 float SafepointSynchronize::_ts_of_current_safepoint = 0.0f; 1031 1032 static jlong cleanup_end_time = 0; 1033 static bool need_to_track_page_armed_status = false; 1034 static bool init_done = false; 1035 1036 // Helper method to print the header. 1037 static void print_header() { 1038 tty->print(" vmop " 1039 "[threads: total initially_running wait_to_block] "); 1040 tty->print("[time: spin block sync cleanup vmop] "); 1041 1042 // no page armed status printed out if it is always armed. 1043 if (need_to_track_page_armed_status) { 1044 tty->print("page_armed "); 1045 } 1046 1047 tty->print_cr("page_trap_count"); 1048 } 1049 1050 void SafepointSynchronize::deferred_initialize_stat() { 1051 if (init_done) return; 1052 1053 // If PrintSafepointStatisticsTimeout is specified, the statistics data will 1054 // be printed right away, in which case, _safepoint_stats will regress to 1055 // a single element array. Otherwise, it is a circular ring buffer with default 1056 // size of PrintSafepointStatisticsCount. 1057 int stats_array_size; 1058 if (PrintSafepointStatisticsTimeout > 0) { 1059 stats_array_size = 1; 1060 PrintSafepointStatistics = true; 1061 } else { 1062 stats_array_size = PrintSafepointStatisticsCount; 1063 } 1064 _safepoint_stats = (SafepointStats*)os::malloc(stats_array_size 1065 * sizeof(SafepointStats), mtInternal); 1066 guarantee(_safepoint_stats != NULL, 1067 "not enough memory for safepoint instrumentation data"); 1068 1069 if (DeferPollingPageLoopCount >= 0) { 1070 need_to_track_page_armed_status = true; 1071 } 1072 init_done = true; 1073 } 1074 1075 void SafepointSynchronize::begin_statistics(int nof_threads, int nof_running) { 1076 assert(init_done, "safepoint statistics array hasn't been initialized"); 1077 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; 1078 1079 spstat->_time_stamp = _ts_of_current_safepoint; 1080 1081 VM_Operation *op = VMThread::vm_operation(); 1082 spstat->_vmop_type = (op != NULL ? op->type() : -1); 1083 if (op != NULL) { 1084 _safepoint_reasons[spstat->_vmop_type]++; 1085 } 1086 1087 spstat->_nof_total_threads = nof_threads; 1088 spstat->_nof_initial_running_threads = nof_running; 1089 spstat->_nof_threads_hit_page_trap = 0; 1090 1091 // Records the start time of spinning. The real time spent on spinning 1092 // will be adjusted when spin is done. Same trick is applied for time 1093 // spent on waiting for threads to block. 1094 if (nof_running != 0) { 1095 spstat->_time_to_spin = os::javaTimeNanos(); 1096 } else { 1097 spstat->_time_to_spin = 0; 1098 } 1099 } 1100 1101 void SafepointSynchronize::update_statistics_on_spin_end() { 1102 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; 1103 1104 jlong cur_time = os::javaTimeNanos(); 1105 1106 spstat->_nof_threads_wait_to_block = _waiting_to_block; 1107 if (spstat->_nof_initial_running_threads != 0) { 1108 spstat->_time_to_spin = cur_time - spstat->_time_to_spin; 1109 } 1110 1111 if (need_to_track_page_armed_status) { 1112 spstat->_page_armed = (PageArmed == 1); 1113 } 1114 1115 // Records the start time of waiting for to block. Updated when block is done. 1116 if (_waiting_to_block != 0) { 1117 spstat->_time_to_wait_to_block = cur_time; 1118 } else { 1119 spstat->_time_to_wait_to_block = 0; 1120 } 1121 } 1122 1123 void SafepointSynchronize::update_statistics_on_sync_end(jlong end_time) { 1124 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; 1125 1126 if (spstat->_nof_threads_wait_to_block != 0) { 1127 spstat->_time_to_wait_to_block = end_time - 1128 spstat->_time_to_wait_to_block; 1129 } 1130 1131 // Records the end time of sync which will be used to calculate the total 1132 // vm operation time. Again, the real time spending in syncing will be deducted 1133 // from the start of the sync time later when end_statistics is called. 1134 spstat->_time_to_sync = end_time - _safepoint_begin_time; 1135 if (spstat->_time_to_sync > _max_sync_time) { 1136 _max_sync_time = spstat->_time_to_sync; 1137 } 1138 1139 spstat->_time_to_do_cleanups = end_time; 1140 } 1141 1142 void SafepointSynchronize::update_statistics_on_cleanup_end(jlong end_time) { 1143 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; 1144 1145 // Record how long spent in cleanup tasks. 1146 spstat->_time_to_do_cleanups = end_time - spstat->_time_to_do_cleanups; 1147 1148 cleanup_end_time = end_time; 1149 } 1150 1151 void SafepointSynchronize::end_statistics(jlong vmop_end_time) { 1152 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; 1153 1154 // Update the vm operation time. 1155 spstat->_time_to_exec_vmop = vmop_end_time - cleanup_end_time; 1156 if (spstat->_time_to_exec_vmop > _max_vmop_time) { 1157 _max_vmop_time = spstat->_time_to_exec_vmop; 1158 } 1159 // Only the sync time longer than the specified 1160 // PrintSafepointStatisticsTimeout will be printed out right away. 1161 // By default, it is -1 meaning all samples will be put into the list. 1162 if ( PrintSafepointStatisticsTimeout > 0) { 1163 if (spstat->_time_to_sync > (jlong)PrintSafepointStatisticsTimeout * MICROUNITS) { 1164 print_statistics(); 1165 } 1166 } else { 1167 // The safepoint statistics will be printed out when the _safepoin_stats 1168 // array fills up. 1169 if (_cur_stat_index == PrintSafepointStatisticsCount - 1) { 1170 print_statistics(); 1171 _cur_stat_index = 0; 1172 } else { 1173 _cur_stat_index++; 1174 } 1175 } 1176 } 1177 1178 void SafepointSynchronize::print_statistics() { 1179 SafepointStats* sstats = _safepoint_stats; 1180 1181 for (int index = 0; index <= _cur_stat_index; index++) { 1182 if (index % 30 == 0) { 1183 print_header(); 1184 } 1185 sstats = &_safepoint_stats[index]; 1186 tty->print("%.3f: ", sstats->_time_stamp); 1187 tty->print("%-26s [" 1188 INT32_FORMAT_W(8) INT32_FORMAT_W(11) INT32_FORMAT_W(15) 1189 " ] ", 1190 sstats->_vmop_type == -1 ? "no vm operation" : 1191 VM_Operation::name(sstats->_vmop_type), 1192 sstats->_nof_total_threads, 1193 sstats->_nof_initial_running_threads, 1194 sstats->_nof_threads_wait_to_block); 1195 // "/ MICROUNITS " is to convert the unit from nanos to millis. 1196 tty->print(" [" 1197 INT64_FORMAT_W(6) INT64_FORMAT_W(6) 1198 INT64_FORMAT_W(6) INT64_FORMAT_W(6) 1199 INT64_FORMAT_W(6) " ] ", 1200 sstats->_time_to_spin / MICROUNITS, 1201 sstats->_time_to_wait_to_block / MICROUNITS, 1202 sstats->_time_to_sync / MICROUNITS, 1203 sstats->_time_to_do_cleanups / MICROUNITS, 1204 sstats->_time_to_exec_vmop / MICROUNITS); 1205 1206 if (need_to_track_page_armed_status) { 1207 tty->print(INT32_FORMAT " ", sstats->_page_armed); 1208 } 1209 tty->print_cr(INT32_FORMAT " ", sstats->_nof_threads_hit_page_trap); 1210 } 1211 } 1212 1213 // This method will be called when VM exits. It will first call 1214 // print_statistics to print out the rest of the sampling. Then 1215 // it tries to summarize the sampling. 1216 void SafepointSynchronize::print_stat_on_exit() { 1217 if (_safepoint_stats == NULL) return; 1218 1219 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; 1220 1221 // During VM exit, end_statistics may not get called and in that 1222 // case, if the sync time is less than PrintSafepointStatisticsTimeout, 1223 // don't print it out. 1224 // Approximate the vm op time. 1225 _safepoint_stats[_cur_stat_index]._time_to_exec_vmop = 1226 os::javaTimeNanos() - cleanup_end_time; 1227 1228 if ( PrintSafepointStatisticsTimeout < 0 || 1229 spstat->_time_to_sync > (jlong)PrintSafepointStatisticsTimeout * MICROUNITS) { 1230 print_statistics(); 1231 } 1232 tty->cr(); 1233 1234 // Print out polling page sampling status. 1235 if (!need_to_track_page_armed_status) { 1236 tty->print_cr("Polling page always armed"); 1237 } else { 1238 tty->print_cr("Defer polling page loop count = " INTX_FORMAT "\n", 1239 DeferPollingPageLoopCount); 1240 } 1241 1242 for (int index = 0; index < VM_Operation::VMOp_Terminating; index++) { 1243 if (_safepoint_reasons[index] != 0) { 1244 tty->print_cr("%-26s" UINT64_FORMAT_W(10), VM_Operation::name(index), 1245 _safepoint_reasons[index]); 1246 } 1247 } 1248 1249 tty->print_cr(UINT64_FORMAT_W(5) " VM operations coalesced during safepoint", 1250 _coalesced_vmop_count); 1251 tty->print_cr("Maximum sync time " INT64_FORMAT_W(5) " ms", 1252 _max_sync_time / MICROUNITS); 1253 tty->print_cr("Maximum vm operation time (except for Exit VM operation) " 1254 INT64_FORMAT_W(5) " ms", 1255 _max_vmop_time / MICROUNITS); 1256 } 1257 1258 // ------------------------------------------------------------------------------------------------ 1259 // Non-product code 1260 1261 #ifndef PRODUCT 1262 1263 void SafepointSynchronize::print_state() { 1264 if (_state == _not_synchronized) { 1265 tty->print_cr("not synchronized"); 1266 } else if (_state == _synchronizing || _state == _synchronized) { 1267 tty->print_cr("State: %s", (_state == _synchronizing) ? "synchronizing" : 1268 "synchronized"); 1269 1270 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) { 1271 cur->safepoint_state()->print(); 1272 } 1273 } 1274 } 1275 1276 void SafepointSynchronize::safepoint_msg(const char* format, ...) { 1277 if (ShowSafepointMsgs) { 1278 va_list ap; 1279 va_start(ap, format); 1280 tty->vprint_cr(format, ap); 1281 va_end(ap); 1282 } 1283 } 1284 1285 #endif // !PRODUCT