1 /* 2 * Copyright (c) 1997, 2019, 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/classLoaderDataGraph.inline.hpp" 27 #include "classfile/stringTable.hpp" 28 #include "classfile/symbolTable.hpp" 29 #include "classfile/systemDictionary.hpp" 30 #include "code/codeCache.hpp" 31 #include "code/icBuffer.hpp" 32 #include "code/nmethod.hpp" 33 #include "code/pcDesc.hpp" 34 #include "code/scopeDesc.hpp" 35 #include "gc/shared/collectedHeap.hpp" 36 #include "gc/shared/gcLocker.hpp" 37 #include "gc/shared/strongRootsScope.hpp" 38 #include "gc/shared/workgroup.hpp" 39 #include "interpreter/interpreter.hpp" 40 #include "jfr/jfrEvents.hpp" 41 #include "logging/log.hpp" 42 #include "logging/logStream.hpp" 43 #include "memory/resourceArea.hpp" 44 #include "memory/universe.hpp" 45 #include "oops/oop.inline.hpp" 46 #include "oops/symbol.hpp" 47 #include "runtime/atomic.hpp" 48 #include "runtime/compilationPolicy.hpp" 49 #include "runtime/deoptimization.hpp" 50 #include "runtime/frame.inline.hpp" 51 #include "runtime/handles.inline.hpp" 52 #include "runtime/interfaceSupport.inline.hpp" 53 #include "runtime/mutexLocker.hpp" 54 #include "runtime/orderAccess.hpp" 55 #include "runtime/osThread.hpp" 56 #include "runtime/safepoint.hpp" 57 #include "runtime/safepointMechanism.inline.hpp" 58 #include "runtime/signature.hpp" 59 #include "runtime/stubCodeGenerator.hpp" 60 #include "runtime/stubRoutines.hpp" 61 #include "runtime/sweeper.hpp" 62 #include "runtime/synchronizer.hpp" 63 #include "runtime/thread.inline.hpp" 64 #include "runtime/threadSMR.hpp" 65 #include "runtime/timerTrace.hpp" 66 #include "services/runtimeService.hpp" 67 #include "utilities/events.hpp" 68 #include "utilities/macros.hpp" 69 #ifdef COMPILER1 70 #include "c1/c1_globals.hpp" 71 #endif 72 73 static void post_safepoint_begin_event(EventSafepointBegin& event, 74 uint64_t safepoint_id, 75 int thread_count, 76 int critical_thread_count) { 77 if (event.should_commit()) { 78 event.set_safepointId(safepoint_id); 79 event.set_totalThreadCount(thread_count); 80 event.set_jniCriticalThreadCount(critical_thread_count); 81 event.commit(); 82 } 83 } 84 85 static void post_safepoint_cleanup_event(EventSafepointCleanup& event, uint64_t safepoint_id) { 86 if (event.should_commit()) { 87 event.set_safepointId(safepoint_id); 88 event.commit(); 89 } 90 } 91 92 static void post_safepoint_synchronize_event(EventSafepointStateSynchronization& event, 93 uint64_t safepoint_id, 94 int initial_number_of_threads, 95 int threads_waiting_to_block, 96 uint64_t iterations) { 97 if (event.should_commit()) { 98 event.set_safepointId(safepoint_id); 99 event.set_initialThreadCount(initial_number_of_threads); 100 event.set_runningThreadCount(threads_waiting_to_block); 101 event.set_iterations(iterations); 102 event.commit(); 103 } 104 } 105 106 static void post_safepoint_cleanup_task_event(EventSafepointCleanupTask& event, 107 uint64_t safepoint_id, 108 const char* name) { 109 if (event.should_commit()) { 110 event.set_safepointId(safepoint_id); 111 event.set_name(name); 112 event.commit(); 113 } 114 } 115 116 static void post_safepoint_end_event(EventSafepointEnd& event, uint64_t safepoint_id) { 117 if (event.should_commit()) { 118 event.set_safepointId(safepoint_id); 119 event.commit(); 120 } 121 } 122 123 // -------------------------------------------------------------------------------------------------- 124 // Implementation of Safepoint begin/end 125 126 SafepointSynchronize::SynchronizeState volatile SafepointSynchronize::_state = SafepointSynchronize::_not_synchronized; 127 int SafepointSynchronize::_waiting_to_block = 0; 128 volatile uint64_t SafepointSynchronize::_safepoint_counter = 0; 129 const uint64_t SafepointSynchronize::InactiveSafepointCounter = 0; 130 int SafepointSynchronize::_current_jni_active_count = 0; 131 132 WaitBarrier* SafepointSynchronize::_wait_barrier; 133 134 static volatile bool PageArmed = false; // safepoint polling page is RO|RW vs PROT_NONE 135 static bool timeout_error_printed = false; 136 137 // Statistic related 138 static jlong _safepoint_begin_time = 0; 139 static volatile int _nof_threads_hit_polling_page = 0; 140 141 void SafepointSynchronize::init(Thread* vmthread) { 142 // WaitBarrier should never be destroyed since we will have 143 // threads waiting on it while exiting. 144 _wait_barrier = new WaitBarrier(vmthread); 145 SafepointTracing::init(); 146 } 147 148 void SafepointSynchronize::increment_jni_active_count() { 149 assert(Thread::current()->is_VM_thread(), "Only VM thread may increment"); 150 ++_current_jni_active_count; 151 } 152 153 void SafepointSynchronize::decrement_waiting_to_block() { 154 assert(_waiting_to_block > 0, "sanity check"); 155 assert(Thread::current()->is_VM_thread(), "Only VM thread may decrement"); 156 --_waiting_to_block; 157 } 158 159 static bool thread_not_running(ThreadSafepointState *cur_state) { 160 if (!cur_state->is_running()) { 161 return true; 162 } 163 cur_state->examine_state_of_thread(SafepointSynchronize::safepoint_counter()); 164 if (!cur_state->is_running()) { 165 return true; 166 } 167 LogTarget(Trace, safepoint) lt; 168 if (lt.is_enabled()) { 169 ResourceMark rm; 170 LogStream ls(lt); 171 cur_state->print_on(&ls); 172 } 173 return false; 174 } 175 176 #ifdef ASSERT 177 static void assert_list_is_valid(const ThreadSafepointState* tss_head, int still_running) { 178 int a = 0; 179 const ThreadSafepointState *tmp_tss = tss_head; 180 while (tmp_tss != NULL) { 181 ++a; 182 assert(tmp_tss->is_running(), "Illegal initial state"); 183 tmp_tss = tmp_tss->get_next(); 184 } 185 assert(a == still_running, "Must be the same"); 186 } 187 #endif // ASSERT 188 189 static void back_off(int iteration) { 190 // iteration will be 1 the first time we enter this spin back-off. 191 // naked_short_nanosleep takes tenths of micros which means that 192 // number of nanoseconds is irrelevant if it's below that. We do 193 // 20 1 ns sleeps with a total cost of ~1 ms, then we do 1 ms sleeps. 194 jlong sleep_ns = 1; 195 if (iteration > 20) { 196 sleep_ns = NANOUNITS / MILLIUNITS; // 1 ms 197 } 198 os::naked_short_nanosleep(sleep_ns); 199 } 200 201 int SafepointSynchronize::synchronize_threads(jlong safepoint_limit_time, int nof_threads, int* initial_running) 202 { 203 JavaThreadIteratorWithHandle jtiwh; 204 205 #ifdef ASSERT 206 for (; JavaThread *cur = jtiwh.next(); ) { 207 assert(cur->safepoint_state()->is_running(), "Illegal initial state"); 208 } 209 jtiwh.rewind(); 210 #endif // ASSERT 211 212 // Iterate through all threads until it has been determined how to stop them all at a safepoint. 213 int still_running = nof_threads; 214 ThreadSafepointState *tss_head = NULL; 215 ThreadSafepointState **p_prev = &tss_head; 216 for (; JavaThread *cur = jtiwh.next(); ) { 217 ThreadSafepointState *cur_tss = cur->safepoint_state(); 218 assert(cur_tss->get_next() == NULL, "Must be NULL"); 219 if (thread_not_running(cur_tss)) { 220 --still_running; 221 } else { 222 *p_prev = cur_tss; 223 p_prev = cur_tss->next_ptr(); 224 } 225 } 226 *p_prev = NULL; 227 228 DEBUG_ONLY(assert_list_is_valid(tss_head, still_running);) 229 230 *initial_running = still_running; 231 232 int iterations = 1; // The first iteration is above. 233 234 while (still_running > 0) { 235 // Check if this has taken too long: 236 if (SafepointTimeout && safepoint_limit_time < os::javaTimeNanos()) { 237 print_safepoint_timeout(); 238 } 239 if (int(iterations) == -1) { // overflow - something is wrong. 240 // We can only overflow here when we are using global 241 // polling pages. We keep this guarantee in its original 242 // form so that searches of the bug database for this 243 // failure mode find the right bugs. 244 guarantee (!PageArmed, "invariant"); 245 } 246 247 p_prev = &tss_head; 248 ThreadSafepointState *cur_tss = tss_head; 249 while (cur_tss != NULL) { 250 assert(cur_tss->is_running(), "Illegal initial state"); 251 if (thread_not_running(cur_tss)) { 252 --still_running; 253 *p_prev = NULL; 254 ThreadSafepointState *tmp = cur_tss; 255 cur_tss = cur_tss->get_next(); 256 tmp->set_next(NULL); 257 } else { 258 *p_prev = cur_tss; 259 p_prev = cur_tss->next_ptr(); 260 cur_tss = cur_tss->get_next(); 261 } 262 } 263 264 DEBUG_ONLY(assert_list_is_valid(tss_head, still_running);) 265 266 if (still_running > 0) { 267 back_off(iterations); 268 } 269 270 iterations++; 271 } 272 273 assert(tss_head == NULL, "Must be empty"); 274 275 return iterations; 276 } 277 278 void SafepointSynchronize::arm_safepoint() { 279 // Begin the process of bringing the system to a safepoint. 280 // Java threads can be in several different states and are 281 // stopped by different mechanisms: 282 // 283 // 1. Running interpreted 284 // When executing branching/returning byte codes interpreter 285 // checks if the poll is armed, if so blocks in SS::block(). 286 // When using global polling the interpreter dispatch table 287 // is changed to force it to check for a safepoint condition 288 // between bytecodes. 289 // 2. Running in native code 290 // When returning from the native code, a Java thread must check 291 // the safepoint _state to see if we must block. If the 292 // VM thread sees a Java thread in native, it does 293 // not wait for this thread to block. The order of the memory 294 // writes and reads of both the safepoint state and the Java 295 // threads state is critical. In order to guarantee that the 296 // memory writes are serialized with respect to each other, 297 // the VM thread issues a memory barrier instruction. 298 // 3. Running compiled Code 299 // Compiled code reads the local polling page that 300 // is set to fault if we are trying to get to a safepoint. 301 // 4. Blocked 302 // A thread which is blocked will not be allowed to return from the 303 // block condition until the safepoint operation is complete. 304 // 5. In VM or Transitioning between states 305 // If a Java thread is currently running in the VM or transitioning 306 // between states, the safepointing code will poll the thread state 307 // until the thread blocks itself when it attempts transitions to a 308 // new state or locking a safepoint checked monitor. 309 310 // We must never miss a thread with correct safepoint id, so we must make sure we arm 311 // the wait barrier for the next safepoint id/counter. 312 // Arming must be done after resetting _current_jni_active_count, _waiting_to_block. 313 _wait_barrier->arm(static_cast<int>(_safepoint_counter + 1)); 314 315 assert((_safepoint_counter & 0x1) == 0, "must be even"); 316 // The store to _safepoint_counter must happen after any stores in arming. 317 OrderAccess::release_store(&_safepoint_counter, _safepoint_counter + 1); 318 319 // We are synchronizing 320 OrderAccess::storestore(); // Ordered with _safepoint_counter 321 _state = _synchronizing; 322 323 if (SafepointMechanism::uses_thread_local_poll()) { 324 // Arming the per thread poll while having _state != _not_synchronized means safepointing 325 log_trace(safepoint)("Setting thread local yield flag for threads"); 326 OrderAccess::storestore(); // storestore, global state -> local state 327 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *cur = jtiwh.next(); ) { 328 // Make sure the threads start polling, it is time to yield. 329 SafepointMechanism::arm_local_poll(cur); 330 } 331 } 332 OrderAccess::fence(); // storestore|storeload, global state -> local state 333 334 if (SafepointMechanism::uses_global_page_poll()) { 335 // Make interpreter safepoint aware 336 Interpreter::notice_safepoints(); 337 338 // Make polling safepoint aware 339 guarantee (!PageArmed, "invariant") ; 340 PageArmed = true; 341 os::make_polling_page_unreadable(); 342 } 343 } 344 345 // Roll all threads forward to a safepoint and suspend them all 346 void SafepointSynchronize::begin() { 347 assert(Thread::current()->is_VM_thread(), "Only VM thread may execute a safepoint"); 348 349 EventSafepointBegin begin_event; 350 SafepointTracing::begin(VMThread::vm_op_type()); 351 352 Universe::heap()->safepoint_synchronize_begin(); 353 354 // By getting the Threads_lock, we assure that no threads are about to start or 355 // exit. It is released again in SafepointSynchronize::end(). 356 Threads_lock->lock(); 357 358 assert( _state == _not_synchronized, "trying to safepoint synchronize with wrong state"); 359 360 int nof_threads = Threads::number_of_threads(); 361 362 _nof_threads_hit_polling_page = 0; 363 364 log_debug(safepoint)("Safepoint synchronization initiated using %s wait barrier. (%d threads)", _wait_barrier->description(), nof_threads); 365 366 // Reset the count of active JNI critical threads 367 _current_jni_active_count = 0; 368 369 // Set number of threads to wait for 370 _waiting_to_block = nof_threads; 371 372 jlong safepoint_limit_time = 0; 373 if (SafepointTimeout) { 374 // Set the limit time, so that it can be compared to see if this has taken 375 // too long to complete. 376 safepoint_limit_time = SafepointTracing::start_of_safepoint() + (jlong)SafepointTimeoutDelay * (NANOUNITS / MILLIUNITS); 377 timeout_error_printed = false; 378 } 379 380 EventSafepointStateSynchronization sync_event; 381 int initial_running = 0; 382 383 // Arms the safepoint, _current_jni_active_count and _waiting_to_block must be set before. 384 arm_safepoint(); 385 386 // Will spin until all threads are safe. 387 int iterations = synchronize_threads(safepoint_limit_time, nof_threads, &initial_running); 388 assert(_waiting_to_block == 0, "No thread should be running"); 389 390 #ifndef PRODUCT 391 if (safepoint_limit_time != 0) { 392 jlong current_time = os::javaTimeNanos(); 393 if (safepoint_limit_time < current_time) { 394 log_warning(safepoint)("# SafepointSynchronize: Finished after " 395 INT64_FORMAT_W(6) " ms", 396 (int64_t)(current_time - SafepointTracing::start_of_safepoint()) / (NANOUNITS / MILLIUNITS)); 397 } 398 } 399 #endif 400 401 assert(Threads_lock->owned_by_self(), "must hold Threads_lock"); 402 403 // Record state 404 _state = _synchronized; 405 406 OrderAccess::fence(); 407 408 #ifdef ASSERT 409 // Make sure all the threads were visited. 410 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *cur = jtiwh.next(); ) { 411 assert(cur->was_visited_for_critical_count(_safepoint_counter), "missed a thread"); 412 } 413 #endif // ASSERT 414 415 // Update the count of active JNI critical regions 416 GCLocker::set_jni_lock_count(_current_jni_active_count); 417 418 post_safepoint_synchronize_event(sync_event, 419 _safepoint_counter, 420 initial_running, 421 _waiting_to_block, iterations); 422 423 SafepointTracing::synchronized(nof_threads, initial_running, _nof_threads_hit_polling_page); 424 425 // We do the safepoint cleanup first since a GC related safepoint 426 // needs cleanup to be completed before running the GC op. 427 EventSafepointCleanup cleanup_event; 428 do_cleanup_tasks(); 429 post_safepoint_cleanup_event(cleanup_event, _safepoint_counter); 430 431 post_safepoint_begin_event(begin_event, _safepoint_counter, nof_threads, _current_jni_active_count); 432 SafepointTracing::cleanup(); 433 } 434 435 void SafepointSynchronize::disarm_safepoint() { 436 uint64_t safepoint_id = _safepoint_counter; 437 { 438 JavaThreadIteratorWithHandle jtiwh; 439 #ifdef ASSERT 440 // A pending_exception cannot be installed during a safepoint. The threads 441 // may install an async exception after they come back from a safepoint into 442 // pending_exception after they unblock. But that should happen later. 443 for (; JavaThread *cur = jtiwh.next(); ) { 444 assert (!(cur->has_pending_exception() && 445 cur->safepoint_state()->is_at_poll_safepoint()), 446 "safepoint installed a pending exception"); 447 } 448 #endif // ASSERT 449 450 if (SafepointMechanism::uses_global_page_poll()) { 451 guarantee (PageArmed, "invariant"); 452 // Make polling safepoint aware 453 os::make_polling_page_readable(); 454 PageArmed = false; 455 // Remove safepoint check from interpreter 456 Interpreter::ignore_safepoints(); 457 } 458 459 OrderAccess::fence(); // keep read and write of _state from floating up 460 assert(_state == _synchronized, "must be synchronized before ending safepoint synchronization"); 461 462 // Change state first to _not_synchronized. 463 // No threads should see _synchronized when running. 464 _state = _not_synchronized; 465 466 // Set the next dormant (even) safepoint id. 467 assert((_safepoint_counter & 0x1) == 1, "must be odd"); 468 OrderAccess::release_store(&_safepoint_counter, _safepoint_counter + 1); 469 470 OrderAccess::fence(); // Keep the local state from floating up. 471 472 jtiwh.rewind(); 473 for (; JavaThread *current = jtiwh.next(); ) { 474 // Clear the visited flag to ensure that the critical counts are collected properly. 475 DEBUG_ONLY(current->reset_visited_for_critical_count(safepoint_id);) 476 ThreadSafepointState* cur_state = current->safepoint_state(); 477 assert(!cur_state->is_running(), "Thread not suspended at safepoint"); 478 cur_state->restart(); // TSS _running 479 assert(cur_state->is_running(), "safepoint state has not been reset"); 480 481 SafepointMechanism::disarm_if_needed(current, false /* NO release */); 482 } 483 } // ~JavaThreadIteratorWithHandle 484 485 // Release threads lock, so threads can be created/destroyed again. 486 Threads_lock->unlock(); 487 488 // Wake threads after local state is correctly set. 489 _wait_barrier->disarm(); 490 } 491 492 // Wake up all threads, so they are ready to resume execution after the safepoint 493 // operation has been carried out 494 void SafepointSynchronize::end() { 495 assert(Threads_lock->owned_by_self(), "must hold Threads_lock"); 496 EventSafepointEnd event; 497 uint64_t safepoint_id = _safepoint_counter; 498 assert(Thread::current()->is_VM_thread(), "Only VM thread can execute a safepoint"); 499 500 disarm_safepoint(); 501 502 Universe::heap()->safepoint_synchronize_end(); 503 504 SafepointTracing::end(); 505 506 post_safepoint_end_event(event, safepoint_id); 507 } 508 509 bool SafepointSynchronize::is_cleanup_needed() { 510 // Need a safepoint if there are many monitors to deflate. 511 if (ObjectSynchronizer::is_cleanup_needed()) return true; 512 // Need a safepoint if some inline cache buffers is non-empty 513 if (!InlineCacheBuffer::is_empty()) return true; 514 return false; 515 } 516 517 class ParallelSPCleanupThreadClosure : public ThreadClosure { 518 private: 519 CodeBlobClosure* _nmethod_cl; 520 DeflateMonitorCounters* _counters; 521 522 public: 523 ParallelSPCleanupThreadClosure(DeflateMonitorCounters* counters) : 524 _nmethod_cl(UseCodeAging ? NMethodSweeper::prepare_reset_hotness_counters() : NULL), 525 _counters(counters) {} 526 527 void do_thread(Thread* thread) { 528 ObjectSynchronizer::deflate_thread_local_monitors(thread, _counters); 529 if (_nmethod_cl != NULL && thread->is_Java_thread() && 530 ! thread->is_Code_cache_sweeper_thread()) { 531 JavaThread* jt = (JavaThread*) thread; 532 jt->nmethods_do(_nmethod_cl); 533 } 534 } 535 }; 536 537 class ParallelSPCleanupTask : public AbstractGangTask { 538 private: 539 SubTasksDone _subtasks; 540 ParallelSPCleanupThreadClosure _cleanup_threads_cl; 541 uint _num_workers; 542 DeflateMonitorCounters* _counters; 543 public: 544 ParallelSPCleanupTask(uint num_workers, DeflateMonitorCounters* counters) : 545 AbstractGangTask("Parallel Safepoint Cleanup"), 546 _subtasks(SubTasksDone(SafepointSynchronize::SAFEPOINT_CLEANUP_NUM_TASKS)), 547 _cleanup_threads_cl(ParallelSPCleanupThreadClosure(counters)), 548 _num_workers(num_workers), 549 _counters(counters) {} 550 551 void work(uint worker_id) { 552 uint64_t safepoint_id = SafepointSynchronize::safepoint_counter(); 553 // All threads deflate monitors and mark nmethods (if necessary). 554 Threads::possibly_parallel_threads_do(true, &_cleanup_threads_cl); 555 556 if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_DEFLATE_MONITORS)) { 557 const char* name = "deflating global idle monitors"; 558 EventSafepointCleanupTask event; 559 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup)); 560 ObjectSynchronizer::deflate_idle_monitors(_counters); 561 562 post_safepoint_cleanup_task_event(event, safepoint_id, name); 563 } 564 565 if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_UPDATE_INLINE_CACHES)) { 566 const char* name = "updating inline caches"; 567 EventSafepointCleanupTask event; 568 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup)); 569 InlineCacheBuffer::update_inline_caches(); 570 571 post_safepoint_cleanup_task_event(event, safepoint_id, name); 572 } 573 574 if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_COMPILATION_POLICY)) { 575 const char* name = "compilation policy safepoint handler"; 576 EventSafepointCleanupTask event; 577 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup)); 578 CompilationPolicy::policy()->do_safepoint_work(); 579 580 post_safepoint_cleanup_task_event(event, safepoint_id, name); 581 } 582 583 if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_SYMBOL_TABLE_REHASH)) { 584 if (SymbolTable::needs_rehashing()) { 585 const char* name = "rehashing symbol table"; 586 EventSafepointCleanupTask event; 587 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup)); 588 SymbolTable::rehash_table(); 589 590 post_safepoint_cleanup_task_event(event, safepoint_id, name); 591 } 592 } 593 594 if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_STRING_TABLE_REHASH)) { 595 if (StringTable::needs_rehashing()) { 596 const char* name = "rehashing string table"; 597 EventSafepointCleanupTask event; 598 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup)); 599 StringTable::rehash_table(); 600 601 post_safepoint_cleanup_task_event(event, safepoint_id, name); 602 } 603 } 604 605 if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_CLD_PURGE)) { 606 // CMS delays purging the CLDG until the beginning of the next safepoint and to 607 // make sure concurrent sweep is done 608 const char* name = "purging class loader data graph"; 609 EventSafepointCleanupTask event; 610 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup)); 611 ClassLoaderDataGraph::purge_if_needed(); 612 613 post_safepoint_cleanup_task_event(event, safepoint_id, name); 614 } 615 616 if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_SYSTEM_DICTIONARY_RESIZE)) { 617 const char* name = "resizing system dictionaries"; 618 EventSafepointCleanupTask event; 619 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup)); 620 ClassLoaderDataGraph::resize_if_needed(); 621 622 post_safepoint_cleanup_task_event(event, safepoint_id, name); 623 } 624 625 _subtasks.all_tasks_completed(_num_workers); 626 } 627 }; 628 629 // Various cleaning tasks that should be done periodically at safepoints. 630 void SafepointSynchronize::do_cleanup_tasks() { 631 632 TraceTime timer("safepoint cleanup tasks", TRACETIME_LOG(Info, safepoint, cleanup)); 633 634 // Prepare for monitor deflation. 635 DeflateMonitorCounters deflate_counters; 636 ObjectSynchronizer::prepare_deflate_idle_monitors(&deflate_counters); 637 638 CollectedHeap* heap = Universe::heap(); 639 assert(heap != NULL, "heap not initialized yet?"); 640 WorkGang* cleanup_workers = heap->get_safepoint_workers(); 641 if (cleanup_workers != NULL) { 642 // Parallel cleanup using GC provided thread pool. 643 uint num_cleanup_workers = cleanup_workers->active_workers(); 644 ParallelSPCleanupTask cleanup(num_cleanup_workers, &deflate_counters); 645 StrongRootsScope srs(num_cleanup_workers); 646 cleanup_workers->run_task(&cleanup); 647 } else { 648 // Serial cleanup using VMThread. 649 ParallelSPCleanupTask cleanup(1, &deflate_counters); 650 StrongRootsScope srs(1); 651 cleanup.work(0); 652 } 653 654 // Needs to be done single threaded by the VMThread. This walks 655 // the thread stacks looking for references to metadata before 656 // deciding to remove it from the metaspaces. 657 if (ClassLoaderDataGraph::should_clean_metaspaces_and_reset()) { 658 const char* name = "cleanup live ClassLoaderData metaspaces"; 659 TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup)); 660 ClassLoaderDataGraph::walk_metadata_and_clean_metaspaces(); 661 } 662 663 // Finish monitor deflation. 664 ObjectSynchronizer::finish_deflate_idle_monitors(&deflate_counters); 665 666 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 667 } 668 669 // Methods for determining if a JavaThread is safepoint safe. 670 671 // False means unsafe with undetermined state. 672 // True means a determined state, but it may be an unsafe state. 673 // If called from a non-safepoint context safepoint_count MUST be InactiveSafepointCounter. 674 bool SafepointSynchronize::try_stable_load_state(JavaThreadState *state, JavaThread *thread, uint64_t safepoint_count) { 675 assert((safepoint_count != InactiveSafepointCounter && 676 Thread::current() == (Thread*)VMThread::vm_thread() && 677 SafepointSynchronize::_state != _not_synchronized) 678 || safepoint_count == InactiveSafepointCounter, "Invalid check"); 679 680 // To handle the thread_blocked state on the backedge of the WaitBarrier from 681 // previous safepoint and reading the reset value (0/InactiveSafepointCounter) we 682 // re-read state after we read thread safepoint id. The JavaThread changes its 683 // thread state from thread_blocked before resetting safepoint id to 0. 684 // This guarantees the second read will be from an updated thread state. It can 685 // either be different state making this an unsafe state or it can see blocked 686 // again. When we see blocked twice with a 0 safepoint id, either: 687 // - It is normally blocked, e.g. on Mutex, TBIVM. 688 // - It was in SS:block(), looped around to SS:block() and is blocked on the WaitBarrier. 689 // - It was in SS:block() but now on a Mutex. 690 // All of these cases are safe. 691 692 *state = thread->thread_state(); 693 OrderAccess::loadload(); 694 uint64_t sid = thread->safepoint_state()->get_safepoint_id(); // Load acquire 695 if (sid != InactiveSafepointCounter && sid != safepoint_count) { 696 // In an old safepoint, state not relevant. 697 return false; 698 } 699 return *state == thread->thread_state(); 700 } 701 702 static bool safepoint_safe_with(JavaThread *thread, JavaThreadState state) { 703 switch(state) { 704 case _thread_in_native: 705 // native threads are safe if they have no java stack or have walkable stack 706 return !thread->has_last_Java_frame() || thread->frame_anchor()->walkable(); 707 708 case _thread_blocked: 709 // On wait_barrier or blocked. 710 // Blocked threads should already have walkable stack. 711 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "blocked and not walkable"); 712 return true; 713 714 default: 715 return false; 716 } 717 } 718 719 bool SafepointSynchronize::handshake_safe(JavaThread *thread) { 720 // This function must be called with the Threads_lock held so an externally 721 // suspended thread cannot be resumed thus it is safe. 722 assert(Threads_lock->owned_by_self() && Thread::current()->is_VM_thread(), 723 "Must hold Threads_lock and be VMThread"); 724 if (thread->is_ext_suspended() || thread->is_terminated()) { 725 return true; 726 } 727 JavaThreadState stable_state; 728 if (try_stable_load_state(&stable_state, thread, InactiveSafepointCounter)) { 729 return safepoint_safe_with(thread, stable_state); 730 } 731 return false; 732 } 733 734 // See if the thread is running inside a lazy critical native and 735 // update the thread critical count if so. Also set a suspend flag to 736 // cause the native wrapper to return into the JVM to do the unlock 737 // once the native finishes. 738 static void check_for_lazy_critical_native(JavaThread *thread, JavaThreadState state) { 739 if (state == _thread_in_native && 740 thread->has_last_Java_frame() && 741 thread->frame_anchor()->walkable()) { 742 // This thread might be in a critical native nmethod so look at 743 // the top of the stack and increment the critical count if it 744 // is. 745 frame wrapper_frame = thread->last_frame(); 746 CodeBlob* stub_cb = wrapper_frame.cb(); 747 if (stub_cb != NULL && 748 stub_cb->is_nmethod() && 749 stub_cb->as_nmethod_or_null()->is_lazy_critical_native()) { 750 // A thread could potentially be in a critical native across 751 // more than one safepoint, so only update the critical state on 752 // the first one. When it returns it will perform the unlock. 753 if (!thread->do_critical_native_unlock()) { 754 #ifdef ASSERT 755 if (!thread->in_critical()) { 756 GCLocker::increment_debug_jni_lock_count(); 757 } 758 #endif 759 thread->enter_critical(); 760 // Make sure the native wrapper calls back on return to 761 // perform the needed critical unlock. 762 thread->set_critical_native_unlock(); 763 } 764 } 765 } 766 } 767 768 // ------------------------------------------------------------------------------------------------------- 769 // Implementation of Safepoint blocking point 770 771 void SafepointSynchronize::block(JavaThread *thread) { 772 assert(thread != NULL, "thread must be set"); 773 assert(thread->is_Java_thread(), "not a Java thread"); 774 775 // Threads shouldn't block if they are in the middle of printing, but... 776 ttyLocker::break_tty_lock_for_safepoint(os::current_thread_id()); 777 778 // Only bail from the block() call if the thread is gone from the 779 // thread list; starting to exit should still block. 780 if (thread->is_terminated()) { 781 // block current thread if we come here from native code when VM is gone 782 thread->block_if_vm_exited(); 783 784 // otherwise do nothing 785 return; 786 } 787 788 JavaThreadState state = thread->thread_state(); 789 thread->frame_anchor()->make_walkable(thread); 790 791 uint64_t safepoint_id = SafepointSynchronize::safepoint_counter(); 792 // Check that we have a valid thread_state at this point 793 switch(state) { 794 case _thread_in_vm_trans: 795 case _thread_in_Java: // From compiled code 796 case _thread_in_native_trans: 797 case _thread_blocked_trans: 798 case _thread_new_trans: 799 800 // We have no idea where the VMThread is, it might even be at next safepoint. 801 // So we can miss this poll, but stop at next. 802 803 // Load dependent store, it must not pass loading of safepoint_id. 804 thread->safepoint_state()->set_safepoint_id(safepoint_id); // Release store 805 806 // This part we can skip if we notice we miss or are in a future safepoint. 807 OrderAccess::storestore(); 808 thread->set_thread_state(_thread_blocked); 809 810 OrderAccess::fence(); // Load in wait barrier should not float up 811 _wait_barrier->wait(static_cast<int>(safepoint_id)); 812 assert(_state != _synchronized, "Can't be"); 813 814 // If barrier is disarmed stop store from floating above loads in barrier. 815 OrderAccess::loadstore(); 816 thread->set_thread_state(state); 817 818 // Then we reset the safepoint id to inactive. 819 thread->safepoint_state()->reset_safepoint_id(); // Release store 820 821 OrderAccess::fence(); 822 823 break; 824 825 default: 826 fatal("Illegal threadstate encountered: %d", state); 827 } 828 guarantee(thread->safepoint_state()->get_safepoint_id() == InactiveSafepointCounter, 829 "The safepoint id should be set only in block path"); 830 831 // Check for pending. async. exceptions or suspends - except if the 832 // thread was blocked inside the VM. has_special_runtime_exit_condition() 833 // is called last since it grabs a lock and we only want to do that when 834 // we must. 835 // 836 // Note: we never deliver an async exception at a polling point as the 837 // compiler may not have an exception handler for it. The polling 838 // code will notice the async and deoptimize and the exception will 839 // be delivered. (Polling at a return point is ok though). Sure is 840 // a lot of bother for a deprecated feature... 841 // 842 // We don't deliver an async exception if the thread state is 843 // _thread_in_native_trans so JNI functions won't be called with 844 // a surprising pending exception. If the thread state is going back to java, 845 // async exception is checked in check_special_condition_for_native_trans(). 846 847 if (state != _thread_blocked_trans && 848 state != _thread_in_vm_trans && 849 thread->has_special_runtime_exit_condition()) { 850 thread->handle_special_runtime_exit_condition( 851 !thread->is_at_poll_safepoint() && (state != _thread_in_native_trans)); 852 } 853 854 // cross_modify_fence is done by SafepointMechanism::block_if_requested_slow 855 // which is the only caller here. 856 } 857 858 // ------------------------------------------------------------------------------------------------------ 859 // Exception handlers 860 861 862 void SafepointSynchronize::handle_polling_page_exception(JavaThread *thread) { 863 assert(thread->is_Java_thread(), "polling reference encountered by VM thread"); 864 assert(thread->thread_state() == _thread_in_Java, "should come from Java code"); 865 if (!ThreadLocalHandshakes) { 866 assert(SafepointSynchronize::is_synchronizing(), "polling encountered outside safepoint synchronization"); 867 } 868 869 if (log_is_enabled(Info, safepoint, stats)) { 870 Atomic::inc(&_nof_threads_hit_polling_page); 871 } 872 873 ThreadSafepointState* state = thread->safepoint_state(); 874 875 state->handle_polling_page_exception(); 876 } 877 878 879 void SafepointSynchronize::print_safepoint_timeout() { 880 if (!timeout_error_printed) { 881 timeout_error_printed = true; 882 // Print out the thread info which didn't reach the safepoint for debugging 883 // purposes (useful when there are lots of threads in the debugger). 884 LogTarget(Warning, safepoint) lt; 885 if (lt.is_enabled()) { 886 ResourceMark rm; 887 LogStream ls(lt); 888 889 ls.cr(); 890 ls.print_cr("# SafepointSynchronize::begin: Timeout detected:"); 891 ls.print_cr("# SafepointSynchronize::begin: Timed out while spinning to reach a safepoint."); 892 ls.print_cr("# SafepointSynchronize::begin: Threads which did not reach the safepoint:"); 893 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *cur_thread = jtiwh.next(); ) { 894 if (cur_thread->safepoint_state()->is_running()) { 895 ls.print("# "); 896 cur_thread->print_on(&ls); 897 ls.cr(); 898 } 899 } 900 ls.print_cr("# SafepointSynchronize::begin: (End of list)"); 901 } 902 } 903 904 // To debug the long safepoint, specify both AbortVMOnSafepointTimeout & 905 // ShowMessageBoxOnError. 906 if (AbortVMOnSafepointTimeout) { 907 // Send the blocking thread a signal to terminate and write an error file. 908 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *cur_thread = jtiwh.next(); ) { 909 if (cur_thread->safepoint_state()->is_running()) { 910 if (!os::signal_thread(cur_thread, SIGILL, "blocking a safepoint")) { 911 break; // Could not send signal. Report fatal error. 912 } 913 // Give cur_thread a chance to report the error and terminate the VM. 914 os::sleep(Thread::current(), 3000, false); 915 } 916 } 917 fatal("Safepoint sync time longer than " INTX_FORMAT "ms detected when executing %s.", 918 SafepointTimeoutDelay, VMThread::vm_operation()->name()); 919 } 920 } 921 922 // ------------------------------------------------------------------------------------------------------- 923 // Implementation of ThreadSafepointState 924 925 ThreadSafepointState::ThreadSafepointState(JavaThread *thread) 926 : _at_poll_safepoint(false), _thread(thread), _safepoint_safe(false), 927 _safepoint_id(SafepointSynchronize::InactiveSafepointCounter), 928 _orig_thread_state(_thread_uninitialized), _next(NULL) { 929 } 930 931 void ThreadSafepointState::create(JavaThread *thread) { 932 ThreadSafepointState *state = new ThreadSafepointState(thread); 933 thread->set_safepoint_state(state); 934 } 935 936 void ThreadSafepointState::destroy(JavaThread *thread) { 937 if (thread->safepoint_state()) { 938 delete(thread->safepoint_state()); 939 thread->set_safepoint_state(NULL); 940 } 941 } 942 943 uint64_t ThreadSafepointState::get_safepoint_id() const { 944 return OrderAccess::load_acquire(&_safepoint_id); 945 } 946 947 void ThreadSafepointState::reset_safepoint_id() { 948 OrderAccess::release_store(&_safepoint_id, SafepointSynchronize::InactiveSafepointCounter); 949 } 950 951 void ThreadSafepointState::set_safepoint_id(uint64_t safepoint_id) { 952 OrderAccess::release_store(&_safepoint_id, safepoint_id); 953 } 954 955 void ThreadSafepointState::examine_state_of_thread(uint64_t safepoint_count) { 956 assert(is_running(), "better be running or just have hit safepoint poll"); 957 958 JavaThreadState stable_state; 959 if (!SafepointSynchronize::try_stable_load_state(&stable_state, _thread, safepoint_count)) { 960 // We could not get stable state of the JavaThread. 961 // Consider it running and just return. 962 return; 963 } 964 965 // Save the state at the start of safepoint processing. 966 _orig_thread_state = stable_state; 967 968 // Check for a thread that is suspended. Note that thread resume tries 969 // to grab the Threads_lock which we own here, so a thread cannot be 970 // resumed during safepoint synchronization. 971 972 // We check to see if this thread is suspended without locking to 973 // avoid deadlocking with a third thread that is waiting for this 974 // thread to be suspended. The third thread can notice the safepoint 975 // that we're trying to start at the beginning of its SR_lock->wait() 976 // call. If that happens, then the third thread will block on the 977 // safepoint while still holding the underlying SR_lock. We won't be 978 // able to get the SR_lock and we'll deadlock. 979 // 980 // We don't need to grab the SR_lock here for two reasons: 981 // 1) The suspend flags are both volatile and are set with an 982 // Atomic::cmpxchg() call so we should see the suspended 983 // state right away. 984 // 2) We're being called from the safepoint polling loop; if 985 // we don't see the suspended state on this iteration, then 986 // we'll come around again. 987 // 988 bool is_suspended = _thread->is_ext_suspended(); 989 if (is_suspended) { 990 account_safe_thread(); 991 return; 992 } 993 994 if (safepoint_safe_with(_thread, stable_state)) { 995 check_for_lazy_critical_native(_thread, stable_state); 996 account_safe_thread(); 997 return; 998 } 999 1000 // All other thread states will continue to run until they 1001 // transition and self-block in state _blocked 1002 // Safepoint polling in compiled code causes the Java threads to do the same. 1003 // Note: new threads may require a malloc so they must be allowed to finish 1004 1005 assert(is_running(), "examine_state_of_thread on non-running thread"); 1006 return; 1007 } 1008 1009 void ThreadSafepointState::account_safe_thread() { 1010 SafepointSynchronize::decrement_waiting_to_block(); 1011 if (_thread->in_critical()) { 1012 // Notice that this thread is in a critical section 1013 SafepointSynchronize::increment_jni_active_count(); 1014 } 1015 DEBUG_ONLY(_thread->set_visited_for_critical_count(SafepointSynchronize::safepoint_counter());) 1016 assert(!_safepoint_safe, "Must be unsafe before safe"); 1017 _safepoint_safe = true; 1018 } 1019 1020 void ThreadSafepointState::restart() { 1021 assert(_safepoint_safe, "Must be safe before unsafe"); 1022 _safepoint_safe = false; 1023 } 1024 1025 void ThreadSafepointState::print_on(outputStream *st) const { 1026 const char *s = _safepoint_safe ? "_at_safepoint" : "_running"; 1027 1028 st->print_cr("Thread: " INTPTR_FORMAT 1029 " [0x%2x] State: %s _at_poll_safepoint %d", 1030 p2i(_thread), _thread->osthread()->thread_id(), s, _at_poll_safepoint); 1031 1032 _thread->print_thread_state_on(st); 1033 } 1034 1035 // --------------------------------------------------------------------------------------------------------------------- 1036 1037 // Block the thread at poll or poll return for safepoint/handshake. 1038 void ThreadSafepointState::handle_polling_page_exception() { 1039 1040 // If we're using a global poll, then the thread should not be 1041 // marked as safepoint safe yet. 1042 assert(!SafepointMechanism::uses_global_page_poll() || !_safepoint_safe, 1043 "polling page exception on thread safepoint safe"); 1044 1045 // Step 1: Find the nmethod from the return address 1046 address real_return_addr = thread()->saved_exception_pc(); 1047 1048 CodeBlob *cb = CodeCache::find_blob(real_return_addr); 1049 assert(cb != NULL && cb->is_compiled(), "return address should be in nmethod"); 1050 CompiledMethod* nm = (CompiledMethod*)cb; 1051 1052 // Find frame of caller 1053 frame stub_fr = thread()->last_frame(); 1054 CodeBlob* stub_cb = stub_fr.cb(); 1055 assert(stub_cb->is_safepoint_stub(), "must be a safepoint stub"); 1056 RegisterMap map(thread(), true); 1057 frame caller_fr = stub_fr.sender(&map); 1058 1059 // Should only be poll_return or poll 1060 assert( nm->is_at_poll_or_poll_return(real_return_addr), "should not be at call" ); 1061 1062 // This is a poll immediately before a return. The exception handling code 1063 // has already had the effect of causing the return to occur, so the execution 1064 // will continue immediately after the call. In addition, the oopmap at the 1065 // return point does not mark the return value as an oop (if it is), so 1066 // it needs a handle here to be updated. 1067 if( nm->is_at_poll_return(real_return_addr) ) { 1068 // See if return type is an oop. 1069 bool return_oop = nm->method()->is_returning_oop(); 1070 Handle return_value; 1071 if (return_oop) { 1072 // The oop result has been saved on the stack together with all 1073 // the other registers. In order to preserve it over GCs we need 1074 // to keep it in a handle. 1075 oop result = caller_fr.saved_oop_result(&map); 1076 assert(oopDesc::is_oop_or_null(result), "must be oop"); 1077 return_value = Handle(thread(), result); 1078 assert(Universe::heap()->is_in_or_null(result), "must be heap pointer"); 1079 } 1080 1081 // Block the thread 1082 SafepointMechanism::block_if_requested(thread()); 1083 1084 // restore oop result, if any 1085 if (return_oop) { 1086 caller_fr.set_saved_oop_result(&map, return_value()); 1087 } 1088 } 1089 1090 // This is a safepoint poll. Verify the return address and block. 1091 else { 1092 set_at_poll_safepoint(true); 1093 1094 // verify the blob built the "return address" correctly 1095 assert(real_return_addr == caller_fr.pc(), "must match"); 1096 1097 // Block the thread 1098 SafepointMechanism::block_if_requested(thread()); 1099 set_at_poll_safepoint(false); 1100 1101 // If we have a pending async exception deoptimize the frame 1102 // as otherwise we may never deliver it. 1103 if (thread()->has_async_condition()) { 1104 ThreadInVMfromJavaNoAsyncException __tiv(thread()); 1105 Deoptimization::deoptimize_frame(thread(), caller_fr.id()); 1106 } 1107 1108 // If an exception has been installed we must check for a pending deoptimization 1109 // Deoptimize frame if exception has been thrown. 1110 1111 if (thread()->has_pending_exception() ) { 1112 RegisterMap map(thread(), true); 1113 frame caller_fr = stub_fr.sender(&map); 1114 if (caller_fr.is_deoptimized_frame()) { 1115 // The exception patch will destroy registers that are still 1116 // live and will be needed during deoptimization. Defer the 1117 // Async exception should have deferred the exception until the 1118 // next safepoint which will be detected when we get into 1119 // the interpreter so if we have an exception now things 1120 // are messed up. 1121 1122 fatal("Exception installed and deoptimization is pending"); 1123 } 1124 } 1125 } 1126 } 1127 1128 1129 // ------------------------------------------------------------------------------------------------------- 1130 // Implementation of SafepointTracing 1131 1132 jlong SafepointTracing::_last_safepoint_begin_time_ns = 0; 1133 jlong SafepointTracing::_last_safepoint_sync_time_ns = 0; 1134 jlong SafepointTracing::_last_safepoint_cleanup_time_ns = 0; 1135 jlong SafepointTracing::_last_safepoint_end_time_ns = 0; 1136 jlong SafepointTracing::_last_safepoint_end_time_epoch_ms = 0; 1137 jlong SafepointTracing::_last_app_time_ns = 0; 1138 int SafepointTracing::_nof_threads = 0; 1139 int SafepointTracing::_nof_running = 0; 1140 int SafepointTracing::_page_trap = 0; 1141 VM_Operation::VMOp_Type SafepointTracing::_current_type; 1142 jlong SafepointTracing::_max_sync_time = 0; 1143 jlong SafepointTracing::_max_vmop_time = 0; 1144 uint64_t SafepointTracing::_op_count[VM_Operation::VMOp_Terminating] = {0}; 1145 1146 void SafepointTracing::init() { 1147 // Application start 1148 _last_safepoint_end_time_ns = os::javaTimeNanos(); 1149 // amount of time since epoch 1150 _last_safepoint_end_time_epoch_ms = os::javaTimeMillis(); 1151 } 1152 1153 // Helper method to print the header. 1154 static void print_header(outputStream* st) { 1155 // The number of spaces is significant here, and should match the format 1156 // specifiers in print_statistics(). 1157 1158 st->print("VM Operation " 1159 "[ threads: total initial_running ]" 1160 "[ time: sync cleanup vmop total ]"); 1161 1162 st->print_cr(" page_trap_count"); 1163 } 1164 1165 // This prints a nice table. To get the statistics to not shift due to the logging uptime 1166 // decorator, use the option as: -Xlog:safepoint+stats:[outputfile]:none 1167 void SafepointTracing::statistics_log() { 1168 LogTarget(Info, safepoint, stats) lt; 1169 assert (lt.is_enabled(), "should only be called when printing statistics is enabled"); 1170 LogStream ls(lt); 1171 1172 static int _cur_stat_index = 0; 1173 1174 // Print header every 30 entries 1175 if ((_cur_stat_index % 30) == 0) { 1176 print_header(&ls); 1177 _cur_stat_index = 1; // wrap 1178 } else { 1179 _cur_stat_index++; 1180 } 1181 1182 ls.print("%-28s [ " 1183 INT32_FORMAT_W(8) " " INT32_FORMAT_W(8) " " 1184 "]", 1185 VM_Operation::name(_current_type), 1186 _nof_threads, 1187 _nof_running); 1188 ls.print("[ " 1189 INT64_FORMAT_W(10) " " INT64_FORMAT_W(10) " " 1190 INT64_FORMAT_W(10) " " INT64_FORMAT_W(10) " ]", 1191 (int64_t)(_last_safepoint_sync_time_ns - _last_safepoint_begin_time_ns), 1192 (int64_t)(_last_safepoint_cleanup_time_ns - _last_safepoint_sync_time_ns), 1193 (int64_t)(_last_safepoint_end_time_ns - _last_safepoint_cleanup_time_ns), 1194 (int64_t)(_last_safepoint_end_time_ns - _last_safepoint_begin_time_ns)); 1195 1196 ls.print_cr(INT32_FORMAT_W(16), _page_trap); 1197 } 1198 1199 // This method will be called when VM exits. This tries to summarize the sampling. 1200 // Current thread may already be deleted, so don't use ResourceMark. 1201 void SafepointTracing::statistics_exit_log() { 1202 if (!log_is_enabled(Info, safepoint, stats)) { 1203 return; 1204 } 1205 for (int index = 0; index < VM_Operation::VMOp_Terminating; index++) { 1206 if (_op_count[index] != 0) { 1207 log_info(safepoint, stats)("%-28s" UINT64_FORMAT_W(10), VM_Operation::name(index), 1208 _op_count[index]); 1209 } 1210 } 1211 1212 log_info(safepoint, stats)("VM operations coalesced during safepoint " INT64_FORMAT, 1213 VMThread::get_coalesced_count()); 1214 log_info(safepoint, stats)("Maximum sync time " INT64_FORMAT" ns", 1215 (int64_t)(_max_sync_time)); 1216 log_info(safepoint, stats)("Maximum vm operation time (except for Exit VM operation) " 1217 INT64_FORMAT " ns", 1218 (int64_t)(_max_vmop_time)); 1219 } 1220 1221 void SafepointTracing::begin(VM_Operation::VMOp_Type type) { 1222 _op_count[type]++; 1223 _current_type = type; 1224 1225 // update the time stamp to begin recording safepoint time 1226 _last_safepoint_begin_time_ns = os::javaTimeNanos(); 1227 _last_safepoint_sync_time_ns = 0; 1228 _last_safepoint_cleanup_time_ns = 0; 1229 1230 _last_app_time_ns = _last_safepoint_begin_time_ns - _last_safepoint_end_time_ns; 1231 _last_safepoint_end_time_ns = 0; 1232 1233 RuntimeService::record_safepoint_begin(_last_app_time_ns); 1234 } 1235 1236 void SafepointTracing::synchronized(int nof_threads, int nof_running, int traps) { 1237 _last_safepoint_sync_time_ns = os::javaTimeNanos(); 1238 _nof_threads = nof_threads; 1239 _nof_running = nof_running; 1240 _page_trap = traps; 1241 RuntimeService::record_safepoint_synchronized(_last_safepoint_sync_time_ns - _last_safepoint_begin_time_ns); 1242 } 1243 1244 void SafepointTracing::cleanup() { 1245 _last_safepoint_cleanup_time_ns = os::javaTimeNanos(); 1246 } 1247 1248 void SafepointTracing::end() { 1249 _last_safepoint_end_time_ns = os::javaTimeNanos(); 1250 // amount of time since epoch 1251 _last_safepoint_end_time_epoch_ms = os::javaTimeMillis(); 1252 1253 if (_max_sync_time < (_last_safepoint_sync_time_ns - _last_safepoint_begin_time_ns)) { 1254 _max_sync_time = _last_safepoint_sync_time_ns - _last_safepoint_begin_time_ns; 1255 } 1256 if (_max_vmop_time < (_last_safepoint_end_time_ns - _last_safepoint_sync_time_ns)) { 1257 _max_vmop_time = _last_safepoint_end_time_ns - _last_safepoint_sync_time_ns; 1258 } 1259 if (log_is_enabled(Info, safepoint, stats)) { 1260 statistics_log(); 1261 } 1262 1263 log_info(safepoint)( 1264 "Safepoint \"%s\", " 1265 "Time since last: " JLONG_FORMAT " ns, " 1266 "Reaching safepoint: " JLONG_FORMAT " ns, " 1267 "At safepoint: " JLONG_FORMAT " ns, " 1268 "Total: " JLONG_FORMAT " ns", 1269 VM_Operation::name(_current_type), 1270 _last_app_time_ns, 1271 _last_safepoint_cleanup_time_ns - _last_safepoint_begin_time_ns, 1272 _last_safepoint_end_time_ns - _last_safepoint_cleanup_time_ns, 1273 _last_safepoint_end_time_ns - _last_safepoint_begin_time_ns 1274 ); 1275 1276 RuntimeService::record_safepoint_end(_last_safepoint_end_time_ns - _last_safepoint_cleanup_time_ns); 1277 }