1 /* 2 * Copyright (c) 1997, 2010, 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/systemDictionary.hpp" 27 #include "code/codeCache.hpp" 28 #include "code/icBuffer.hpp" 29 #include "code/nmethod.hpp" 30 #include "code/pcDesc.hpp" 31 #include "code/scopeDesc.hpp" 32 #include "gc_interface/collectedHeap.hpp" 33 #include "interpreter/interpreter.hpp" 34 #include "memory/resourceArea.hpp" 35 #include "memory/universe.inline.hpp" 36 #include "oops/oop.inline.hpp" 37 #include "oops/symbolOop.hpp" 38 #include "runtime/compilationPolicy.hpp" 39 #include "runtime/deoptimization.hpp" 40 #include "runtime/frame.inline.hpp" 41 #include "runtime/interfaceSupport.hpp" 42 #include "runtime/mutexLocker.hpp" 43 #include "runtime/osThread.hpp" 44 #include "runtime/safepoint.hpp" 45 #include "runtime/signature.hpp" 46 #include "runtime/stubCodeGenerator.hpp" 47 #include "runtime/stubRoutines.hpp" 48 #include "runtime/sweeper.hpp" 49 #include "runtime/synchronizer.hpp" 50 #include "services/runtimeService.hpp" 51 #include "utilities/events.hpp" 52 #ifdef TARGET_ARCH_x86 53 # include "nativeInst_x86.hpp" 54 # include "vmreg_x86.inline.hpp" 55 #endif 56 #ifdef TARGET_ARCH_sparc 57 # include "nativeInst_sparc.hpp" 58 # include "vmreg_sparc.inline.hpp" 59 #endif 60 #ifdef TARGET_ARCH_zero 61 # include "nativeInst_zero.hpp" 62 # include "vmreg_zero.inline.hpp" 63 #endif 64 #ifdef TARGET_OS_FAMILY_linux 65 # include "thread_linux.inline.hpp" 66 #endif 67 #ifdef TARGET_OS_FAMILY_solaris 68 # include "thread_solaris.inline.hpp" 69 #endif 70 #ifdef TARGET_OS_FAMILY_windows 71 # include "thread_windows.inline.hpp" 72 #endif 73 #ifndef SERIALGC 74 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp" 75 #include "gc_implementation/shared/concurrentGCThread.hpp" 76 #endif 77 #ifdef COMPILER1 78 #include "c1/c1_globals.hpp" 79 #endif 80 81 // -------------------------------------------------------------------------------------------------- 82 // Implementation of Safepoint begin/end 83 84 SafepointSynchronize::SynchronizeState volatile SafepointSynchronize::_state = SafepointSynchronize::_not_synchronized; 85 volatile int SafepointSynchronize::_waiting_to_block = 0; 86 volatile int SafepointSynchronize::_safepoint_counter = 0; 87 long SafepointSynchronize::_end_of_last_safepoint = 0; 88 static volatile int PageArmed = 0 ; // safepoint polling page is RO|RW vs PROT_NONE 89 static volatile int TryingToBlock = 0 ; // proximate value -- for advisory use only 90 static bool timeout_error_printed = false; 91 92 // Roll all threads forward to a safepoint and suspend them all 93 void SafepointSynchronize::begin() { 94 95 Thread* myThread = Thread::current(); 96 assert(myThread->is_VM_thread(), "Only VM thread may execute a safepoint"); 97 98 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) { 99 _safepoint_begin_time = os::javaTimeNanos(); 100 _ts_of_current_safepoint = tty->time_stamp().seconds(); 101 } 102 103 #ifndef SERIALGC 104 if (UseConcMarkSweepGC) { 105 // In the future we should investigate whether CMS can use the 106 // more-general mechanism below. DLD (01/05). 107 ConcurrentMarkSweepThread::synchronize(false); 108 } else if (UseG1GC) { 109 ConcurrentGCThread::safepoint_synchronize(); 110 } 111 #endif // SERIALGC 112 113 // By getting the Threads_lock, we assure that no threads are about to start or 114 // exit. It is released again in SafepointSynchronize::end(). 115 Threads_lock->lock(); 116 117 assert( _state == _not_synchronized, "trying to safepoint synchronize with wrong state"); 118 119 int nof_threads = Threads::number_of_threads(); 120 121 if (TraceSafepoint) { 122 tty->print_cr("Safepoint synchronization initiated. (%d)", nof_threads); 123 } 124 125 RuntimeService::record_safepoint_begin(); 126 127 { 128 MutexLocker mu(Safepoint_lock); 129 130 // Set number of threads to wait for, before we initiate the callbacks 131 _waiting_to_block = nof_threads; 132 TryingToBlock = 0 ; 133 int still_running = nof_threads; 134 135 // Save the starting time, so that it can be compared to see if this has taken 136 // too long to complete. 137 jlong safepoint_limit_time; 138 timeout_error_printed = false; 139 140 // PrintSafepointStatisticsTimeout can be specified separately. When 141 // specified, PrintSafepointStatistics will be set to true in 142 // deferred_initialize_stat method. The initialization has to be done 143 // early enough to avoid any races. See bug 6880029 for details. 144 if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) { 145 deferred_initialize_stat(); 146 } 147 148 // Begin the process of bringing the system to a safepoint. 149 // Java threads can be in several different states and are 150 // stopped by different mechanisms: 151 // 152 // 1. Running interpreted 153 // The interpeter dispatch table is changed to force it to 154 // check for a safepoint condition between bytecodes. 155 // 2. Running in native code 156 // When returning from the native code, a Java thread must check 157 // the safepoint _state to see if we must block. If the 158 // VM thread sees a Java thread in native, it does 159 // not wait for this thread to block. The order of the memory 160 // writes and reads of both the safepoint state and the Java 161 // threads state is critical. In order to guarantee that the 162 // memory writes are serialized with respect to each other, 163 // the VM thread issues a memory barrier instruction 164 // (on MP systems). In order to avoid the overhead of issuing 165 // a memory barrier for each Java thread making native calls, each Java 166 // thread performs a write to a single memory page after changing 167 // the thread state. The VM thread performs a sequence of 168 // mprotect OS calls which forces all previous writes from all 169 // Java threads to be serialized. This is done in the 170 // os::serialize_thread_states() call. This has proven to be 171 // much more efficient than executing a membar instruction 172 // on every call to native code. 173 // 3. Running compiled Code 174 // Compiled code reads a global (Safepoint Polling) page that 175 // is set to fault if we are trying to get to a safepoint. 176 // 4. Blocked 177 // A thread which is blocked will not be allowed to return from the 178 // block condition until the safepoint operation is complete. 179 // 5. In VM or Transitioning between states 180 // If a Java thread is currently running in the VM or transitioning 181 // between states, the safepointing code will wait for the thread to 182 // block itself when it attempts transitions to a new state. 183 // 184 _state = _synchronizing; 185 OrderAccess::fence(); 186 187 // Flush all thread states to memory 188 if (!UseMembar) { 189 os::serialize_thread_states(); 190 } 191 192 // Make interpreter safepoint aware 193 Interpreter::notice_safepoints(); 194 195 if (UseCompilerSafepoints && DeferPollingPageLoopCount < 0) { 196 // Make polling safepoint aware 197 guarantee (PageArmed == 0, "invariant") ; 198 PageArmed = 1 ; 199 os::make_polling_page_unreadable(); 200 } 201 202 // Consider using active_processor_count() ... but that call is expensive. 203 int ncpus = os::processor_count() ; 204 205 #ifdef ASSERT 206 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) { 207 assert(cur->safepoint_state()->is_running(), "Illegal initial state"); 208 } 209 #endif // ASSERT 210 211 if (SafepointTimeout) 212 safepoint_limit_time = os::javaTimeNanos() + (jlong)SafepointTimeoutDelay * MICROUNITS; 213 214 // Iterate through all threads until it have been determined how to stop them all at a safepoint 215 unsigned int iterations = 0; 216 int steps = 0 ; 217 while(still_running > 0) { 218 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) { 219 assert(!cur->is_ConcurrentGC_thread(), "A concurrent GC thread is unexpectly being suspended"); 220 ThreadSafepointState *cur_state = cur->safepoint_state(); 221 if (cur_state->is_running()) { 222 cur_state->examine_state_of_thread(); 223 if (!cur_state->is_running()) { 224 still_running--; 225 // consider adjusting steps downward: 226 // steps = 0 227 // steps -= NNN 228 // steps >>= 1 229 // steps = MIN(steps, 2000-100) 230 // if (iterations != 0) steps -= NNN 231 } 232 if (TraceSafepoint && Verbose) cur_state->print(); 233 } 234 } 235 236 if (PrintSafepointStatistics && iterations == 0) { 237 begin_statistics(nof_threads, still_running); 238 } 239 240 if (still_running > 0) { 241 // Check for if it takes to long 242 if (SafepointTimeout && safepoint_limit_time < os::javaTimeNanos()) { 243 print_safepoint_timeout(_spinning_timeout); 244 } 245 246 // Spin to avoid context switching. 247 // There's a tension between allowing the mutators to run (and rendezvous) 248 // vs spinning. As the VM thread spins, wasting cycles, it consumes CPU that 249 // a mutator might otherwise use profitably to reach a safepoint. Excessive 250 // spinning by the VM thread on a saturated system can increase rendezvous latency. 251 // Blocking or yielding incur their own penalties in the form of context switching 252 // and the resultant loss of $ residency. 253 // 254 // Further complicating matters is that yield() does not work as naively expected 255 // on many platforms -- yield() does not guarantee that any other ready threads 256 // will run. As such we revert yield_all() after some number of iterations. 257 // Yield_all() is implemented as a short unconditional sleep on some platforms. 258 // Typical operating systems round a "short" sleep period up to 10 msecs, so sleeping 259 // can actually increase the time it takes the VM thread to detect that a system-wide 260 // stop-the-world safepoint has been reached. In a pathological scenario such as that 261 // described in CR6415670 the VMthread may sleep just before the mutator(s) become safe. 262 // In that case the mutators will be stalled waiting for the safepoint to complete and the 263 // the VMthread will be sleeping, waiting for the mutators to rendezvous. The VMthread 264 // will eventually wake up and detect that all mutators are safe, at which point 265 // we'll again make progress. 266 // 267 // Beware too that that the VMThread typically runs at elevated priority. 268 // Its default priority is higher than the default mutator priority. 269 // Obviously, this complicates spinning. 270 // 271 // Note too that on Windows XP SwitchThreadTo() has quite different behavior than Sleep(0). 272 // Sleep(0) will _not yield to lower priority threads, while SwitchThreadTo() will. 273 // 274 // See the comments in synchronizer.cpp for additional remarks on spinning. 275 // 276 // In the future we might: 277 // 1. Modify the safepoint scheme to avoid potentally unbounded spinning. 278 // This is tricky as the path used by a thread exiting the JVM (say on 279 // on JNI call-out) simply stores into its state field. The burden 280 // is placed on the VM thread, which must poll (spin). 281 // 2. Find something useful to do while spinning. If the safepoint is GC-related 282 // we might aggressively scan the stacks of threads that are already safe. 283 // 3. Use Solaris schedctl to examine the state of the still-running mutators. 284 // If all the mutators are ONPROC there's no reason to sleep or yield. 285 // 4. YieldTo() any still-running mutators that are ready but OFFPROC. 286 // 5. Check system saturation. If the system is not fully saturated then 287 // simply spin and avoid sleep/yield. 288 // 6. As still-running mutators rendezvous they could unpark the sleeping 289 // VMthread. This works well for still-running mutators that become 290 // safe. The VMthread must still poll for mutators that call-out. 291 // 7. Drive the policy on time-since-begin instead of iterations. 292 // 8. Consider making the spin duration a function of the # of CPUs: 293 // Spin = (((ncpus-1) * M) + K) + F(still_running) 294 // Alternately, instead of counting iterations of the outer loop 295 // we could count the # of threads visited in the inner loop, above. 296 // 9. On windows consider using the return value from SwitchThreadTo() 297 // to drive subsequent spin/SwitchThreadTo()/Sleep(N) decisions. 298 299 if (UseCompilerSafepoints && int(iterations) == DeferPollingPageLoopCount) { 300 guarantee (PageArmed == 0, "invariant") ; 301 PageArmed = 1 ; 302 os::make_polling_page_unreadable(); 303 } 304 305 // Instead of (ncpus > 1) consider either (still_running < (ncpus + EPSILON)) or 306 // ((still_running + _waiting_to_block - TryingToBlock)) < ncpus) 307 ++steps ; 308 if (ncpus > 1 && steps < SafepointSpinBeforeYield) { 309 SpinPause() ; // MP-Polite spin 310 } else 311 if (steps < DeferThrSuspendLoopCount) { 312 os::NakedYield() ; 313 } else { 314 os::yield_all(steps) ; 315 // Alternately, the VM thread could transiently depress its scheduling priority or 316 // transiently increase the priority of the tardy mutator(s). 317 } 318 319 iterations ++ ; 320 } 321 assert(iterations < (uint)max_jint, "We have been iterating in the safepoint loop too long"); 322 } 323 assert(still_running == 0, "sanity check"); 324 325 if (PrintSafepointStatistics) { 326 update_statistics_on_spin_end(); 327 } 328 329 // wait until all threads are stopped 330 while (_waiting_to_block > 0) { 331 if (TraceSafepoint) tty->print_cr("Waiting for %d thread(s) to block", _waiting_to_block); 332 if (!SafepointTimeout || timeout_error_printed) { 333 Safepoint_lock->wait(true); // true, means with no safepoint checks 334 } else { 335 // Compute remaining time 336 jlong remaining_time = safepoint_limit_time - os::javaTimeNanos(); 337 338 // If there is no remaining time, then there is an error 339 if (remaining_time < 0 || Safepoint_lock->wait(true, remaining_time / MICROUNITS)) { 340 print_safepoint_timeout(_blocking_timeout); 341 } 342 } 343 } 344 assert(_waiting_to_block == 0, "sanity check"); 345 346 #ifndef PRODUCT 347 if (SafepointTimeout) { 348 jlong current_time = os::javaTimeNanos(); 349 if (safepoint_limit_time < current_time) { 350 tty->print_cr("# SafepointSynchronize: Finished after " 351 INT64_FORMAT_W(6) " ms", 352 ((current_time - safepoint_limit_time) / MICROUNITS + 353 SafepointTimeoutDelay)); 354 } 355 } 356 #endif 357 358 assert((_safepoint_counter & 0x1) == 0, "must be even"); 359 assert(Threads_lock->owned_by_self(), "must hold Threads_lock"); 360 _safepoint_counter ++; 361 362 // Record state 363 _state = _synchronized; 364 365 OrderAccess::fence(); 366 367 if (TraceSafepoint) { 368 VM_Operation *op = VMThread::vm_operation(); 369 tty->print_cr("Entering safepoint region: %s", (op != NULL) ? op->name() : "no vm operation"); 370 } 371 372 RuntimeService::record_safepoint_synchronized(); 373 if (PrintSafepointStatistics) { 374 update_statistics_on_sync_end(os::javaTimeNanos()); 375 } 376 377 // Call stuff that needs to be run when a safepoint is just about to be completed 378 do_cleanup_tasks(); 379 380 if (PrintSafepointStatistics) { 381 // Record how much time spend on the above cleanup tasks 382 update_statistics_on_cleanup_end(os::javaTimeNanos()); 383 } 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 if (TraceSafepoint) { 435 tty->print_cr("Leaving safepoint region"); 436 } 437 438 // Start suspended threads 439 for(JavaThread *current = Threads::first(); current; current = current->next()) { 440 // A problem occurring on Solaris is when attempting to restart threads 441 // the first #cpus - 1 go well, but then the VMThread is preempted when we get 442 // to the next one (since it has been running the longest). We then have 443 // to wait for a cpu to become available before we can continue restarting 444 // threads. 445 // FIXME: This causes the performance of the VM to degrade when active and with 446 // large numbers of threads. Apparently this is due to the synchronous nature 447 // of suspending threads. 448 // 449 // TODO-FIXME: the comments above are vestigial and no longer apply. 450 // Furthermore, using solaris' schedctl in this particular context confers no benefit 451 if (VMThreadHintNoPreempt) { 452 os::hint_no_preempt(); 453 } 454 ThreadSafepointState* cur_state = current->safepoint_state(); 455 assert(cur_state->type() != ThreadSafepointState::_running, "Thread not suspended at safepoint"); 456 cur_state->restart(); 457 assert(cur_state->is_running(), "safepoint state has not been reset"); 458 } 459 460 RuntimeService::record_safepoint_end(); 461 462 // Release threads lock, so threads can be created/destroyed again. It will also starts all threads 463 // blocked in signal_thread_blocked 464 Threads_lock->unlock(); 465 466 } 467 #ifndef SERIALGC 468 // If there are any concurrent GC threads resume them. 469 if (UseConcMarkSweepGC) { 470 ConcurrentMarkSweepThread::desynchronize(false); 471 } else if (UseG1GC) { 472 ConcurrentGCThread::safepoint_desynchronize(); 473 } 474 #endif // SERIALGC 475 // record this time so VMThread can keep track how much time has elasped 476 // since last safepoint. 477 _end_of_last_safepoint = os::javaTimeMillis(); 478 } 479 480 bool SafepointSynchronize::is_cleanup_needed() { 481 // Need a safepoint if some inline cache buffers is non-empty 482 if (!InlineCacheBuffer::is_empty()) return true; 483 return false; 484 } 485 486 487 488 // Various cleaning tasks that should be done periodically at safepoints 489 void SafepointSynchronize::do_cleanup_tasks() { 490 { 491 TraceTime t1("deflating idle monitors", TraceSafepointCleanupTime); 492 ObjectSynchronizer::deflate_idle_monitors(); 493 } 494 495 { 496 TraceTime t2("updating inline caches", TraceSafepointCleanupTime); 497 InlineCacheBuffer::update_inline_caches(); 498 } 499 { 500 TraceTime t3("compilation policy safepoint handler", TraceSafepointCleanupTime); 501 CompilationPolicy::policy()->do_safepoint_work(); 502 } 503 504 TraceTime t4("sweeping nmethods", TraceSafepointCleanupTime); 505 NMethodSweeper::scan_stacks(); 506 } 507 508 509 bool SafepointSynchronize::safepoint_safe(JavaThread *thread, JavaThreadState state) { 510 switch(state) { 511 case _thread_in_native: 512 // native threads are safe if they have no java stack or have walkable stack 513 return !thread->has_last_Java_frame() || thread->frame_anchor()->walkable(); 514 515 // blocked threads should have already have walkable stack 516 case _thread_blocked: 517 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "blocked and not walkable"); 518 return true; 519 520 default: 521 return false; 522 } 523 } 524 525 526 // ------------------------------------------------------------------------------------------------------- 527 // Implementation of Safepoint callback point 528 529 void SafepointSynchronize::block(JavaThread *thread) { 530 assert(thread != NULL, "thread must be set"); 531 assert(thread->is_Java_thread(), "not a Java thread"); 532 533 // Threads shouldn't block if they are in the middle of printing, but... 534 ttyLocker::break_tty_lock_for_safepoint(os::current_thread_id()); 535 536 // Only bail from the block() call if the thread is gone from the 537 // thread list; starting to exit should still block. 538 if (thread->is_terminated()) { 539 // block current thread if we come here from native code when VM is gone 540 thread->block_if_vm_exited(); 541 542 // otherwise do nothing 543 return; 544 } 545 546 JavaThreadState state = thread->thread_state(); 547 thread->frame_anchor()->make_walkable(thread); 548 549 // Check that we have a valid thread_state at this point 550 switch(state) { 551 case _thread_in_vm_trans: 552 case _thread_in_Java: // From compiled code 553 554 // We are highly likely to block on the Safepoint_lock. In order to avoid blocking in this case, 555 // we pretend we are still in the VM. 556 thread->set_thread_state(_thread_in_vm); 557 558 if (is_synchronizing()) { 559 Atomic::inc (&TryingToBlock) ; 560 } 561 562 // We will always be holding the Safepoint_lock when we are examine the state 563 // of a thread. Hence, the instructions between the Safepoint_lock->lock() and 564 // Safepoint_lock->unlock() are happening atomic with regards to the safepoint code 565 Safepoint_lock->lock_without_safepoint_check(); 566 if (is_synchronizing()) { 567 // Decrement the number of threads to wait for and signal vm thread 568 assert(_waiting_to_block > 0, "sanity check"); 569 _waiting_to_block--; 570 thread->safepoint_state()->set_has_called_back(true); 571 572 // Consider (_waiting_to_block < 2) to pipeline the wakeup of the VM thread 573 if (_waiting_to_block == 0) { 574 Safepoint_lock->notify_all(); 575 } 576 } 577 578 // We transition the thread to state _thread_blocked here, but 579 // we can't do our usual check for external suspension and then 580 // self-suspend after the lock_without_safepoint_check() call 581 // below because we are often called during transitions while 582 // we hold different locks. That would leave us suspended while 583 // holding a resource which results in deadlocks. 584 thread->set_thread_state(_thread_blocked); 585 Safepoint_lock->unlock(); 586 587 // We now try to acquire the threads lock. Since this lock is hold by the VM thread during 588 // the entire safepoint, the threads will all line up here during the safepoint. 589 Threads_lock->lock_without_safepoint_check(); 590 // restore original state. This is important if the thread comes from compiled code, so it 591 // will continue to execute with the _thread_in_Java state. 592 thread->set_thread_state(state); 593 Threads_lock->unlock(); 594 break; 595 596 case _thread_in_native_trans: 597 case _thread_blocked_trans: 598 case _thread_new_trans: 599 if (thread->safepoint_state()->type() == ThreadSafepointState::_call_back) { 600 thread->print_thread_state(); 601 fatal("Deadlock in safepoint code. " 602 "Should have called back to the VM before blocking."); 603 } 604 605 // We transition the thread to state _thread_blocked here, but 606 // we can't do our usual check for external suspension and then 607 // self-suspend after the lock_without_safepoint_check() call 608 // below because we are often called during transitions while 609 // we hold different locks. That would leave us suspended while 610 // holding a resource which results in deadlocks. 611 thread->set_thread_state(_thread_blocked); 612 613 // It is not safe to suspend a thread if we discover it is in _thread_in_native_trans. Hence, 614 // the safepoint code might still be waiting for it to block. We need to change the state here, 615 // so it can see that it is at a safepoint. 616 617 // Block until the safepoint operation is completed. 618 Threads_lock->lock_without_safepoint_check(); 619 620 // Restore state 621 thread->set_thread_state(state); 622 623 Threads_lock->unlock(); 624 break; 625 626 default: 627 fatal(err_msg("Illegal threadstate encountered: %d", state)); 628 } 629 630 // Check for pending. async. exceptions or suspends - except if the 631 // thread was blocked inside the VM. has_special_runtime_exit_condition() 632 // is called last since it grabs a lock and we only want to do that when 633 // we must. 634 // 635 // Note: we never deliver an async exception at a polling point as the 636 // compiler may not have an exception handler for it. The polling 637 // code will notice the async and deoptimize and the exception will 638 // be delivered. (Polling at a return point is ok though). Sure is 639 // a lot of bother for a deprecated feature... 640 // 641 // We don't deliver an async exception if the thread state is 642 // _thread_in_native_trans so JNI functions won't be called with 643 // a surprising pending exception. If the thread state is going back to java, 644 // async exception is checked in check_special_condition_for_native_trans(). 645 646 if (state != _thread_blocked_trans && 647 state != _thread_in_vm_trans && 648 thread->has_special_runtime_exit_condition()) { 649 thread->handle_special_runtime_exit_condition( 650 !thread->is_at_poll_safepoint() && (state != _thread_in_native_trans)); 651 } 652 } 653 654 // ------------------------------------------------------------------------------------------------------ 655 // Exception handlers 656 657 #ifndef PRODUCT 658 #ifdef _LP64 659 #define PTR_PAD "" 660 #else 661 #define PTR_PAD " " 662 #endif 663 664 static void print_ptrs(intptr_t oldptr, intptr_t newptr, bool wasoop) { 665 bool is_oop = newptr ? ((oop)newptr)->is_oop() : false; 666 tty->print_cr(PTR_FORMAT PTR_PAD " %s %c " PTR_FORMAT PTR_PAD " %s %s", 667 oldptr, wasoop?"oop":" ", oldptr == newptr ? ' ' : '!', 668 newptr, is_oop?"oop":" ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":" ")); 669 } 670 671 static void print_longs(jlong oldptr, jlong newptr, bool wasoop) { 672 bool is_oop = newptr ? ((oop)(intptr_t)newptr)->is_oop() : false; 673 tty->print_cr(PTR64_FORMAT " %s %c " PTR64_FORMAT " %s %s", 674 oldptr, wasoop?"oop":" ", oldptr == newptr ? ' ' : '!', 675 newptr, is_oop?"oop":" ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":" ")); 676 } 677 678 #ifdef SPARC 679 static void print_me(intptr_t *new_sp, intptr_t *old_sp, bool *was_oops) { 680 #ifdef _LP64 681 tty->print_cr("--------+------address-----+------before-----------+-------after----------+"); 682 const int incr = 1; // Increment to skip a long, in units of intptr_t 683 #else 684 tty->print_cr("--------+--address-+------before-----------+-------after----------+"); 685 const int incr = 2; // Increment to skip a long, in units of intptr_t 686 #endif 687 tty->print_cr("---SP---|"); 688 for( int i=0; i<16; i++ ) { 689 tty->print("blob %c%d |"PTR_FORMAT" ","LO"[i>>3],i&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); } 690 tty->print_cr("--------|"); 691 for( int i1=0; i1<frame::memory_parameter_word_sp_offset-16; i1++ ) { 692 tty->print("argv pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); } 693 tty->print(" pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); 694 tty->print_cr("--------|"); 695 tty->print(" G1 |"PTR_FORMAT" ",new_sp); print_longs(*(jlong*)old_sp,*(jlong*)new_sp,was_oops[incr-1]); old_sp += incr; new_sp += incr; was_oops += incr; 696 tty->print(" G3 |"PTR_FORMAT" ",new_sp); print_longs(*(jlong*)old_sp,*(jlong*)new_sp,was_oops[incr-1]); old_sp += incr; new_sp += incr; was_oops += incr; 697 tty->print(" G4 |"PTR_FORMAT" ",new_sp); print_longs(*(jlong*)old_sp,*(jlong*)new_sp,was_oops[incr-1]); old_sp += incr; new_sp += incr; was_oops += incr; 698 tty->print(" G5 |"PTR_FORMAT" ",new_sp); print_longs(*(jlong*)old_sp,*(jlong*)new_sp,was_oops[incr-1]); old_sp += incr; new_sp += incr; was_oops += incr; 699 tty->print_cr(" FSR |"PTR_FORMAT" "PTR64_FORMAT" "PTR64_FORMAT,new_sp,*(jlong*)old_sp,*(jlong*)new_sp); 700 old_sp += incr; new_sp += incr; was_oops += incr; 701 // Skip the floats 702 tty->print_cr("--Float-|"PTR_FORMAT,new_sp); 703 tty->print_cr("---FP---|"); 704 old_sp += incr*32; new_sp += incr*32; was_oops += incr*32; 705 for( int i2=0; i2<16; i2++ ) { 706 tty->print("call %c%d |"PTR_FORMAT" ","LI"[i2>>3],i2&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); } 707 tty->print_cr(""); 708 } 709 #endif // SPARC 710 #endif // PRODUCT 711 712 713 void SafepointSynchronize::handle_polling_page_exception(JavaThread *thread) { 714 assert(thread->is_Java_thread(), "polling reference encountered by VM thread"); 715 assert(thread->thread_state() == _thread_in_Java, "should come from Java code"); 716 assert(SafepointSynchronize::is_synchronizing(), "polling encountered outside safepoint synchronization"); 717 718 // Uncomment this to get some serious before/after printing of the 719 // Sparc safepoint-blob frame structure. 720 /* 721 intptr_t* sp = thread->last_Java_sp(); 722 intptr_t stack_copy[150]; 723 for( int i=0; i<150; i++ ) stack_copy[i] = sp[i]; 724 bool was_oops[150]; 725 for( int i=0; i<150; i++ ) 726 was_oops[i] = stack_copy[i] ? ((oop)stack_copy[i])->is_oop() : false; 727 */ 728 729 if (ShowSafepointMsgs) { 730 tty->print("handle_polling_page_exception: "); 731 } 732 733 if (PrintSafepointStatistics) { 734 inc_page_trap_count(); 735 } 736 737 ThreadSafepointState* state = thread->safepoint_state(); 738 739 state->handle_polling_page_exception(); 740 // print_me(sp,stack_copy,was_oops); 741 } 742 743 744 void SafepointSynchronize::print_safepoint_timeout(SafepointTimeoutReason reason) { 745 if (!timeout_error_printed) { 746 timeout_error_printed = true; 747 // Print out the thread infor which didn't reach the safepoint for debugging 748 // purposes (useful when there are lots of threads in the debugger). 749 tty->print_cr(""); 750 tty->print_cr("# SafepointSynchronize::begin: Timeout detected:"); 751 if (reason == _spinning_timeout) { 752 tty->print_cr("# SafepointSynchronize::begin: Timed out while spinning to reach a safepoint."); 753 } else if (reason == _blocking_timeout) { 754 tty->print_cr("# SafepointSynchronize::begin: Timed out while waiting for threads to stop."); 755 } 756 757 tty->print_cr("# SafepointSynchronize::begin: Threads which did not reach the safepoint:"); 758 ThreadSafepointState *cur_state; 759 ResourceMark rm; 760 for(JavaThread *cur_thread = Threads::first(); cur_thread; 761 cur_thread = cur_thread->next()) { 762 cur_state = cur_thread->safepoint_state(); 763 764 if (cur_thread->thread_state() != _thread_blocked && 765 ((reason == _spinning_timeout && cur_state->is_running()) || 766 (reason == _blocking_timeout && !cur_state->has_called_back()))) { 767 tty->print("# "); 768 cur_thread->print(); 769 tty->print_cr(""); 770 } 771 } 772 tty->print_cr("# SafepointSynchronize::begin: (End of list)"); 773 } 774 775 // To debug the long safepoint, specify both DieOnSafepointTimeout & 776 // ShowMessageBoxOnError. 777 if (DieOnSafepointTimeout) { 778 char msg[1024]; 779 VM_Operation *op = VMThread::vm_operation(); 780 sprintf(msg, "Safepoint sync time longer than " INTX_FORMAT "ms detected when executing %s.", 781 SafepointTimeoutDelay, 782 op != NULL ? op->name() : "no vm operation"); 783 fatal(msg); 784 } 785 } 786 787 788 // ------------------------------------------------------------------------------------------------------- 789 // Implementation of ThreadSafepointState 790 791 ThreadSafepointState::ThreadSafepointState(JavaThread *thread) { 792 _thread = thread; 793 _type = _running; 794 _has_called_back = false; 795 _at_poll_safepoint = false; 796 } 797 798 void ThreadSafepointState::create(JavaThread *thread) { 799 ThreadSafepointState *state = new ThreadSafepointState(thread); 800 thread->set_safepoint_state(state); 801 } 802 803 void ThreadSafepointState::destroy(JavaThread *thread) { 804 if (thread->safepoint_state()) { 805 delete(thread->safepoint_state()); 806 thread->set_safepoint_state(NULL); 807 } 808 } 809 810 void ThreadSafepointState::examine_state_of_thread() { 811 assert(is_running(), "better be running or just have hit safepoint poll"); 812 813 JavaThreadState state = _thread->thread_state(); 814 815 // Save the state at the start of safepoint processing. 816 _orig_thread_state = state; 817 818 // Check for a thread that is suspended. Note that thread resume tries 819 // to grab the Threads_lock which we own here, so a thread cannot be 820 // resumed during safepoint synchronization. 821 822 // We check to see if this thread is suspended without locking to 823 // avoid deadlocking with a third thread that is waiting for this 824 // thread to be suspended. The third thread can notice the safepoint 825 // that we're trying to start at the beginning of its SR_lock->wait() 826 // call. If that happens, then the third thread will block on the 827 // safepoint while still holding the underlying SR_lock. We won't be 828 // able to get the SR_lock and we'll deadlock. 829 // 830 // We don't need to grab the SR_lock here for two reasons: 831 // 1) The suspend flags are both volatile and are set with an 832 // Atomic::cmpxchg() call so we should see the suspended 833 // state right away. 834 // 2) We're being called from the safepoint polling loop; if 835 // we don't see the suspended state on this iteration, then 836 // we'll come around again. 837 // 838 bool is_suspended = _thread->is_ext_suspended(); 839 if (is_suspended) { 840 roll_forward(_at_safepoint); 841 return; 842 } 843 844 // Some JavaThread states have an initial safepoint state of 845 // running, but are actually at a safepoint. We will happily 846 // agree and update the safepoint state here. 847 if (SafepointSynchronize::safepoint_safe(_thread, state)) { 848 roll_forward(_at_safepoint); 849 return; 850 } 851 852 if (state == _thread_in_vm) { 853 roll_forward(_call_back); 854 return; 855 } 856 857 // All other thread states will continue to run until they 858 // transition and self-block in state _blocked 859 // Safepoint polling in compiled code causes the Java threads to do the same. 860 // Note: new threads may require a malloc so they must be allowed to finish 861 862 assert(is_running(), "examine_state_of_thread on non-running thread"); 863 return; 864 } 865 866 // Returns true is thread could not be rolled forward at present position. 867 void ThreadSafepointState::roll_forward(suspend_type type) { 868 _type = type; 869 870 switch(_type) { 871 case _at_safepoint: 872 SafepointSynchronize::signal_thread_at_safepoint(); 873 break; 874 875 case _call_back: 876 set_has_called_back(false); 877 break; 878 879 case _running: 880 default: 881 ShouldNotReachHere(); 882 } 883 } 884 885 void ThreadSafepointState::restart() { 886 switch(type()) { 887 case _at_safepoint: 888 case _call_back: 889 break; 890 891 case _running: 892 default: 893 tty->print_cr("restart thread "INTPTR_FORMAT" with state %d", 894 _thread, _type); 895 _thread->print(); 896 ShouldNotReachHere(); 897 } 898 _type = _running; 899 set_has_called_back(false); 900 } 901 902 903 void ThreadSafepointState::print_on(outputStream *st) const { 904 const char *s; 905 906 switch(_type) { 907 case _running : s = "_running"; break; 908 case _at_safepoint : s = "_at_safepoint"; break; 909 case _call_back : s = "_call_back"; break; 910 default: 911 ShouldNotReachHere(); 912 } 913 914 st->print_cr("Thread: " INTPTR_FORMAT 915 " [0x%2x] State: %s _has_called_back %d _at_poll_safepoint %d", 916 _thread, _thread->osthread()->thread_id(), s, _has_called_back, 917 _at_poll_safepoint); 918 919 _thread->print_thread_state_on(st); 920 } 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, 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 VM_DeoptimizeFrame deopt(thread(), caller_fr.id()); 997 VMThread::execute(&deopt); 998 } 999 1000 // If an exception has been installed we must check for a pending deoptimization 1001 // Deoptimize frame if exception has been thrown. 1002 1003 if (thread()->has_pending_exception() ) { 1004 RegisterMap map(thread(), true); 1005 frame caller_fr = stub_fr.sender(&map); 1006 if (caller_fr.is_deoptimized_frame()) { 1007 // The exception patch will destroy registers that are still 1008 // live and will be needed during deoptimization. Defer the 1009 // Async exception should have defered the exception until the 1010 // next safepoint which will be detected when we get into 1011 // the interpreter so if we have an exception now things 1012 // are messed up. 1013 1014 fatal("Exception installed and deoptimization is pending"); 1015 } 1016 } 1017 } 1018 } 1019 1020 1021 // 1022 // Statistics & Instrumentations 1023 // 1024 SafepointSynchronize::SafepointStats* SafepointSynchronize::_safepoint_stats = NULL; 1025 jlong SafepointSynchronize::_safepoint_begin_time = 0; 1026 int SafepointSynchronize::_cur_stat_index = 0; 1027 julong SafepointSynchronize::_safepoint_reasons[VM_Operation::VMOp_Terminating]; 1028 julong SafepointSynchronize::_coalesced_vmop_count = 0; 1029 jlong SafepointSynchronize::_max_sync_time = 0; 1030 jlong SafepointSynchronize::_max_vmop_time = 0; 1031 float SafepointSynchronize::_ts_of_current_safepoint = 0.0f; 1032 1033 static jlong cleanup_end_time = 0; 1034 static bool need_to_track_page_armed_status = false; 1035 static bool init_done = false; 1036 1037 // Helper method to print the header. 1038 static void print_header() { 1039 tty->print(" vmop " 1040 "[threads: total initially_running wait_to_block] "); 1041 tty->print("[time: spin block sync cleanup vmop] "); 1042 1043 // no page armed status printed out if it is always armed. 1044 if (need_to_track_page_armed_status) { 1045 tty->print("page_armed "); 1046 } 1047 1048 tty->print_cr("page_trap_count"); 1049 } 1050 1051 void SafepointSynchronize::deferred_initialize_stat() { 1052 if (init_done) return; 1053 1054 if (PrintSafepointStatisticsCount <= 0) { 1055 fatal("Wrong PrintSafepointStatisticsCount"); 1056 } 1057 1058 // If PrintSafepointStatisticsTimeout is specified, the statistics data will 1059 // be printed right away, in which case, _safepoint_stats will regress to 1060 // a single element array. Otherwise, it is a circular ring buffer with default 1061 // size of PrintSafepointStatisticsCount. 1062 int stats_array_size; 1063 if (PrintSafepointStatisticsTimeout > 0) { 1064 stats_array_size = 1; 1065 PrintSafepointStatistics = true; 1066 } else { 1067 stats_array_size = PrintSafepointStatisticsCount; 1068 } 1069 _safepoint_stats = (SafepointStats*)os::malloc(stats_array_size 1070 * sizeof(SafepointStats)); 1071 guarantee(_safepoint_stats != NULL, 1072 "not enough memory for safepoint instrumentation data"); 1073 1074 if (UseCompilerSafepoints && DeferPollingPageLoopCount >= 0) { 1075 need_to_track_page_armed_status = true; 1076 } 1077 init_done = true; 1078 } 1079 1080 void SafepointSynchronize::begin_statistics(int nof_threads, int nof_running) { 1081 assert(init_done, "safepoint statistics array hasn't been initialized"); 1082 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; 1083 1084 spstat->_time_stamp = _ts_of_current_safepoint; 1085 1086 VM_Operation *op = VMThread::vm_operation(); 1087 spstat->_vmop_type = (op != NULL ? op->type() : -1); 1088 if (op != NULL) { 1089 _safepoint_reasons[spstat->_vmop_type]++; 1090 } 1091 1092 spstat->_nof_total_threads = nof_threads; 1093 spstat->_nof_initial_running_threads = nof_running; 1094 spstat->_nof_threads_hit_page_trap = 0; 1095 1096 // Records the start time of spinning. The real time spent on spinning 1097 // will be adjusted when spin is done. Same trick is applied for time 1098 // spent on waiting for threads to block. 1099 if (nof_running != 0) { 1100 spstat->_time_to_spin = os::javaTimeNanos(); 1101 } else { 1102 spstat->_time_to_spin = 0; 1103 } 1104 } 1105 1106 void SafepointSynchronize::update_statistics_on_spin_end() { 1107 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; 1108 1109 jlong cur_time = os::javaTimeNanos(); 1110 1111 spstat->_nof_threads_wait_to_block = _waiting_to_block; 1112 if (spstat->_nof_initial_running_threads != 0) { 1113 spstat->_time_to_spin = cur_time - spstat->_time_to_spin; 1114 } 1115 1116 if (need_to_track_page_armed_status) { 1117 spstat->_page_armed = (PageArmed == 1); 1118 } 1119 1120 // Records the start time of waiting for to block. Updated when block is done. 1121 if (_waiting_to_block != 0) { 1122 spstat->_time_to_wait_to_block = cur_time; 1123 } else { 1124 spstat->_time_to_wait_to_block = 0; 1125 } 1126 } 1127 1128 void SafepointSynchronize::update_statistics_on_sync_end(jlong end_time) { 1129 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; 1130 1131 if (spstat->_nof_threads_wait_to_block != 0) { 1132 spstat->_time_to_wait_to_block = end_time - 1133 spstat->_time_to_wait_to_block; 1134 } 1135 1136 // Records the end time of sync which will be used to calculate the total 1137 // vm operation time. Again, the real time spending in syncing will be deducted 1138 // from the start of the sync time later when end_statistics is called. 1139 spstat->_time_to_sync = end_time - _safepoint_begin_time; 1140 if (spstat->_time_to_sync > _max_sync_time) { 1141 _max_sync_time = spstat->_time_to_sync; 1142 } 1143 1144 spstat->_time_to_do_cleanups = end_time; 1145 } 1146 1147 void SafepointSynchronize::update_statistics_on_cleanup_end(jlong end_time) { 1148 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; 1149 1150 // Record how long spent in cleanup tasks. 1151 spstat->_time_to_do_cleanups = end_time - spstat->_time_to_do_cleanups; 1152 1153 cleanup_end_time = end_time; 1154 } 1155 1156 void SafepointSynchronize::end_statistics(jlong vmop_end_time) { 1157 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; 1158 1159 // Update the vm operation time. 1160 spstat->_time_to_exec_vmop = vmop_end_time - cleanup_end_time; 1161 if (spstat->_time_to_exec_vmop > _max_vmop_time) { 1162 _max_vmop_time = spstat->_time_to_exec_vmop; 1163 } 1164 // Only the sync time longer than the specified 1165 // PrintSafepointStatisticsTimeout will be printed out right away. 1166 // By default, it is -1 meaning all samples will be put into the list. 1167 if ( PrintSafepointStatisticsTimeout > 0) { 1168 if (spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) { 1169 print_statistics(); 1170 } 1171 } else { 1172 // The safepoint statistics will be printed out when the _safepoin_stats 1173 // array fills up. 1174 if (_cur_stat_index == PrintSafepointStatisticsCount - 1) { 1175 print_statistics(); 1176 _cur_stat_index = 0; 1177 } else { 1178 _cur_stat_index++; 1179 } 1180 } 1181 } 1182 1183 void SafepointSynchronize::print_statistics() { 1184 SafepointStats* sstats = _safepoint_stats; 1185 1186 for (int index = 0; index <= _cur_stat_index; index++) { 1187 if (index % 30 == 0) { 1188 print_header(); 1189 } 1190 sstats = &_safepoint_stats[index]; 1191 tty->print("%.3f: ", sstats->_time_stamp); 1192 tty->print("%-26s [" 1193 INT32_FORMAT_W(8)INT32_FORMAT_W(11)INT32_FORMAT_W(15) 1194 " ] ", 1195 sstats->_vmop_type == -1 ? "no vm operation" : 1196 VM_Operation::name(sstats->_vmop_type), 1197 sstats->_nof_total_threads, 1198 sstats->_nof_initial_running_threads, 1199 sstats->_nof_threads_wait_to_block); 1200 // "/ MICROUNITS " is to convert the unit from nanos to millis. 1201 tty->print(" [" 1202 INT64_FORMAT_W(6)INT64_FORMAT_W(6) 1203 INT64_FORMAT_W(6)INT64_FORMAT_W(6) 1204 INT64_FORMAT_W(6)" ] ", 1205 sstats->_time_to_spin / MICROUNITS, 1206 sstats->_time_to_wait_to_block / MICROUNITS, 1207 sstats->_time_to_sync / MICROUNITS, 1208 sstats->_time_to_do_cleanups / MICROUNITS, 1209 sstats->_time_to_exec_vmop / MICROUNITS); 1210 1211 if (need_to_track_page_armed_status) { 1212 tty->print(INT32_FORMAT" ", sstats->_page_armed); 1213 } 1214 tty->print_cr(INT32_FORMAT" ", sstats->_nof_threads_hit_page_trap); 1215 } 1216 } 1217 1218 // This method will be called when VM exits. It will first call 1219 // print_statistics to print out the rest of the sampling. Then 1220 // it tries to summarize the sampling. 1221 void SafepointSynchronize::print_stat_on_exit() { 1222 if (_safepoint_stats == NULL) return; 1223 1224 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; 1225 1226 // During VM exit, end_statistics may not get called and in that 1227 // case, if the sync time is less than PrintSafepointStatisticsTimeout, 1228 // don't print it out. 1229 // Approximate the vm op time. 1230 _safepoint_stats[_cur_stat_index]._time_to_exec_vmop = 1231 os::javaTimeNanos() - cleanup_end_time; 1232 1233 if ( PrintSafepointStatisticsTimeout < 0 || 1234 spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) { 1235 print_statistics(); 1236 } 1237 tty->print_cr(""); 1238 1239 // Print out polling page sampling status. 1240 if (!need_to_track_page_armed_status) { 1241 if (UseCompilerSafepoints) { 1242 tty->print_cr("Polling page always armed"); 1243 } 1244 } else { 1245 tty->print_cr("Defer polling page loop count = %d\n", 1246 DeferPollingPageLoopCount); 1247 } 1248 1249 for (int index = 0; index < VM_Operation::VMOp_Terminating; index++) { 1250 if (_safepoint_reasons[index] != 0) { 1251 tty->print_cr("%-26s"UINT64_FORMAT_W(10), VM_Operation::name(index), 1252 _safepoint_reasons[index]); 1253 } 1254 } 1255 1256 tty->print_cr(UINT64_FORMAT_W(5)" VM operations coalesced during safepoint", 1257 _coalesced_vmop_count); 1258 tty->print_cr("Maximum sync time "INT64_FORMAT_W(5)" ms", 1259 _max_sync_time / MICROUNITS); 1260 tty->print_cr("Maximum vm operation time (except for Exit VM operation) " 1261 INT64_FORMAT_W(5)" ms", 1262 _max_vmop_time / MICROUNITS); 1263 } 1264 1265 // ------------------------------------------------------------------------------------------------ 1266 // Non-product code 1267 1268 #ifndef PRODUCT 1269 1270 void SafepointSynchronize::print_state() { 1271 if (_state == _not_synchronized) { 1272 tty->print_cr("not synchronized"); 1273 } else if (_state == _synchronizing || _state == _synchronized) { 1274 tty->print_cr("State: %s", (_state == _synchronizing) ? "synchronizing" : 1275 "synchronized"); 1276 1277 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) { 1278 cur->safepoint_state()->print(); 1279 } 1280 } 1281 } 1282 1283 void SafepointSynchronize::safepoint_msg(const char* format, ...) { 1284 if (ShowSafepointMsgs) { 1285 va_list ap; 1286 va_start(ap, format); 1287 tty->vprint_cr(format, ap); 1288 va_end(ap); 1289 } 1290 } 1291 1292 #endif // !PRODUCT