1 /* 2 * Copyright (c) 2002, 2012, 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/symbolTable.hpp" 27 #include "code/codeCache.hpp" 28 #include "gc_implementation/parallelScavenge/cardTableExtension.hpp" 29 #include "gc_implementation/parallelScavenge/gcTaskManager.hpp" 30 #include "gc_implementation/parallelScavenge/generationSizer.hpp" 31 #include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp" 32 #include "gc_implementation/parallelScavenge/psAdaptiveSizePolicy.hpp" 33 #include "gc_implementation/parallelScavenge/psMarkSweep.hpp" 34 #include "gc_implementation/parallelScavenge/psParallelCompact.hpp" 35 #include "gc_implementation/parallelScavenge/psScavenge.inline.hpp" 36 #include "gc_implementation/parallelScavenge/psTasks.hpp" 37 #include "gc_implementation/shared/gcHeapSummary.hpp" 38 #include "gc_implementation/shared/gcTimer.hpp" 39 #include "gc_implementation/shared/gcTrace.hpp" 40 #include "gc_implementation/shared/gcTraceTime.hpp" 41 #include "gc_implementation/shared/isGCActiveMark.hpp" 42 #include "gc_implementation/shared/spaceDecorator.hpp" 43 #include "gc_interface/gcCause.hpp" 44 #include "memory/collectorPolicy.hpp" 45 #include "memory/gcLocker.inline.hpp" 46 #include "memory/referencePolicy.hpp" 47 #include "memory/referenceProcessor.hpp" 48 #include "memory/resourceArea.hpp" 49 #include "oops/oop.inline.hpp" 50 #include "oops/oop.psgc.inline.hpp" 51 #include "runtime/biasedLocking.hpp" 52 #include "runtime/fprofiler.hpp" 53 #include "runtime/handles.inline.hpp" 54 #include "runtime/threadCritical.hpp" 55 #include "runtime/vmThread.hpp" 56 #include "runtime/vm_operations.hpp" 57 #include "services/memoryService.hpp" 58 #include "utilities/stack.inline.hpp" 59 60 61 HeapWord* PSScavenge::_to_space_top_before_gc = NULL; 62 int PSScavenge::_consecutive_skipped_scavenges = 0; 63 ReferenceProcessor* PSScavenge::_ref_processor = NULL; 64 CardTableExtension* PSScavenge::_card_table = NULL; 65 bool PSScavenge::_survivor_overflow = false; 66 int PSScavenge::_tenuring_threshold = 0; 67 HeapWord* PSScavenge::_young_generation_boundary = NULL; 68 elapsedTimer PSScavenge::_accumulated_time; 69 STWGCTimer PSScavenge::_gc_timer; 70 ParallelScavengeTracer PSScavenge::_gc_tracer; 71 Stack<markOop, mtGC> PSScavenge::_preserved_mark_stack; 72 Stack<oop, mtGC> PSScavenge::_preserved_oop_stack; 73 CollectorCounters* PSScavenge::_counters = NULL; 74 75 // Define before use 76 class PSIsAliveClosure: public BoolObjectClosure { 77 public: 78 void do_object(oop p) { 79 assert(false, "Do not call."); 80 } 81 bool do_object_b(oop p) { 82 return (!PSScavenge::is_obj_in_young((HeapWord*) p)) || p->is_forwarded(); 83 } 84 }; 85 86 PSIsAliveClosure PSScavenge::_is_alive_closure; 87 88 class PSKeepAliveClosure: public OopClosure { 89 protected: 90 MutableSpace* _to_space; 91 PSPromotionManager* _promotion_manager; 92 93 public: 94 PSKeepAliveClosure(PSPromotionManager* pm) : _promotion_manager(pm) { 95 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 96 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 97 _to_space = heap->young_gen()->to_space(); 98 99 assert(_promotion_manager != NULL, "Sanity"); 100 } 101 102 template <class T> void do_oop_work(T* p) { 103 assert (!oopDesc::is_null(*p), "expected non-null ref"); 104 assert ((oopDesc::load_decode_heap_oop_not_null(p))->is_oop(), 105 "expected an oop while scanning weak refs"); 106 107 // Weak refs may be visited more than once. 108 if (PSScavenge::should_scavenge(p, _to_space)) { 109 PSScavenge::copy_and_push_safe_barrier<T, /*promote_immediately=*/false>(_promotion_manager, p); 110 } 111 } 112 virtual void do_oop(oop* p) { PSKeepAliveClosure::do_oop_work(p); } 113 virtual void do_oop(narrowOop* p) { PSKeepAliveClosure::do_oop_work(p); } 114 }; 115 116 class PSEvacuateFollowersClosure: public VoidClosure { 117 private: 118 PSPromotionManager* _promotion_manager; 119 public: 120 PSEvacuateFollowersClosure(PSPromotionManager* pm) : _promotion_manager(pm) {} 121 122 virtual void do_void() { 123 assert(_promotion_manager != NULL, "Sanity"); 124 _promotion_manager->drain_stacks(true); 125 guarantee(_promotion_manager->stacks_empty(), 126 "stacks should be empty at this point"); 127 } 128 }; 129 130 class PSPromotionFailedClosure : public ObjectClosure { 131 virtual void do_object(oop obj) { 132 if (obj->is_forwarded()) { 133 obj->init_mark(); 134 } 135 } 136 }; 137 138 class PSRefProcTaskProxy: public GCTask { 139 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 140 ProcessTask & _rp_task; 141 uint _work_id; 142 public: 143 PSRefProcTaskProxy(ProcessTask & rp_task, uint work_id) 144 : _rp_task(rp_task), 145 _work_id(work_id) 146 { } 147 148 private: 149 virtual char* name() { return (char *)"Process referents by policy in parallel"; } 150 virtual void do_it(GCTaskManager* manager, uint which); 151 }; 152 153 void PSRefProcTaskProxy::do_it(GCTaskManager* manager, uint which) 154 { 155 PSPromotionManager* promotion_manager = 156 PSPromotionManager::gc_thread_promotion_manager(which); 157 assert(promotion_manager != NULL, "sanity check"); 158 PSKeepAliveClosure keep_alive(promotion_manager); 159 PSEvacuateFollowersClosure evac_followers(promotion_manager); 160 PSIsAliveClosure is_alive; 161 _rp_task.work(_work_id, is_alive, keep_alive, evac_followers); 162 } 163 164 class PSRefEnqueueTaskProxy: public GCTask { 165 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 166 EnqueueTask& _enq_task; 167 uint _work_id; 168 169 public: 170 PSRefEnqueueTaskProxy(EnqueueTask& enq_task, uint work_id) 171 : _enq_task(enq_task), 172 _work_id(work_id) 173 { } 174 175 virtual char* name() { return (char *)"Enqueue reference objects in parallel"; } 176 virtual void do_it(GCTaskManager* manager, uint which) 177 { 178 _enq_task.work(_work_id); 179 } 180 }; 181 182 class PSRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 183 virtual void execute(ProcessTask& task); 184 virtual void execute(EnqueueTask& task); 185 }; 186 187 void PSRefProcTaskExecutor::execute(ProcessTask& task) 188 { 189 GCTaskQueue* q = GCTaskQueue::create(); 190 GCTaskManager* manager = ParallelScavengeHeap::gc_task_manager(); 191 for(uint i=0; i < manager->active_workers(); i++) { 192 q->enqueue(new PSRefProcTaskProxy(task, i)); 193 } 194 ParallelTaskTerminator terminator(manager->active_workers(), 195 (TaskQueueSetSuper*) PSPromotionManager::stack_array_depth()); 196 if (task.marks_oops_alive() && manager->active_workers() > 1) { 197 for (uint j = 0; j < manager->active_workers(); j++) { 198 q->enqueue(new StealTask(&terminator)); 199 } 200 } 201 manager->execute_and_wait(q); 202 } 203 204 205 void PSRefProcTaskExecutor::execute(EnqueueTask& task) 206 { 207 GCTaskQueue* q = GCTaskQueue::create(); 208 GCTaskManager* manager = ParallelScavengeHeap::gc_task_manager(); 209 for(uint i=0; i < manager->active_workers(); i++) { 210 q->enqueue(new PSRefEnqueueTaskProxy(task, i)); 211 } 212 manager->execute_and_wait(q); 213 } 214 215 // This method contains all heap specific policy for invoking scavenge. 216 // PSScavenge::invoke_no_policy() will do nothing but attempt to 217 // scavenge. It will not clean up after failed promotions, bail out if 218 // we've exceeded policy time limits, or any other special behavior. 219 // All such policy should be placed here. 220 // 221 // Note that this method should only be called from the vm_thread while 222 // at a safepoint! 223 bool PSScavenge::invoke() { 224 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 225 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread"); 226 assert(!Universe::heap()->is_gc_active(), "not reentrant"); 227 228 ParallelScavengeHeap* const heap = (ParallelScavengeHeap*)Universe::heap(); 229 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 230 231 PSAdaptiveSizePolicy* policy = heap->size_policy(); 232 IsGCActiveMark mark; 233 234 const bool scavenge_done = PSScavenge::invoke_no_policy(); 235 const bool need_full_gc = !scavenge_done || 236 policy->should_full_GC(heap->old_gen()->free_in_bytes()); 237 bool full_gc_done = false; 238 239 if (UsePerfData) { 240 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters(); 241 const int ffs_val = need_full_gc ? full_follows_scavenge : not_skipped; 242 counters->update_full_follows_scavenge(ffs_val); 243 } 244 245 if (need_full_gc) { 246 GCCauseSetter gccs(heap, GCCause::_adaptive_size_policy); 247 CollectorPolicy* cp = heap->collector_policy(); 248 const bool clear_all_softrefs = cp->should_clear_all_soft_refs(); 249 250 if (UseParallelOldGC) { 251 full_gc_done = PSParallelCompact::invoke_no_policy(clear_all_softrefs); 252 } else { 253 full_gc_done = PSMarkSweep::invoke_no_policy(clear_all_softrefs); 254 } 255 } 256 257 return full_gc_done; 258 } 259 260 // This method contains no policy. You should probably 261 // be calling invoke() instead. 262 bool PSScavenge::invoke_no_policy() { 263 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 264 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread"); 265 266 assert(_preserved_mark_stack.is_empty(), "should be empty"); 267 assert(_preserved_oop_stack.is_empty(), "should be empty"); 268 269 _gc_timer.register_gc_start(os::elapsed_counter()); 270 271 TimeStamp scavenge_entry; 272 TimeStamp scavenge_midpoint; 273 TimeStamp scavenge_exit; 274 275 scavenge_entry.update(); 276 277 if (GC_locker::check_active_before_gc()) { 278 return false; 279 } 280 281 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 282 GCCause::Cause gc_cause = heap->gc_cause(); 283 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 284 285 // Check for potential problems. 286 if (!should_attempt_scavenge()) { 287 return false; 288 } 289 290 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start()); 291 292 bool promotion_failure_occurred = false; 293 294 PSYoungGen* young_gen = heap->young_gen(); 295 PSOldGen* old_gen = heap->old_gen(); 296 PSPermGen* perm_gen = heap->perm_gen(); 297 PSAdaptiveSizePolicy* size_policy = heap->size_policy(); 298 299 heap->increment_total_collections(); 300 301 AdaptiveSizePolicyOutput(size_policy, heap->total_collections()); 302 303 if ((gc_cause != GCCause::_java_lang_system_gc) || 304 UseAdaptiveSizePolicyWithSystemGC) { 305 // Gather the feedback data for eden occupancy. 306 young_gen->eden_space()->accumulate_statistics(); 307 } 308 309 if (ZapUnusedHeapArea) { 310 // Save information needed to minimize mangling 311 heap->record_gen_tops_before_GC(); 312 } 313 314 heap->print_heap_before_gc(); 315 heap->trace_heap_before_gc(&_gc_tracer); 316 317 assert(!NeverTenure || _tenuring_threshold == markOopDesc::max_age + 1, "Sanity"); 318 assert(!AlwaysTenure || _tenuring_threshold == 0, "Sanity"); 319 320 size_t prev_used = heap->used(); 321 322 // Fill in TLABs 323 heap->accumulate_statistics_all_tlabs(); 324 heap->ensure_parsability(true); // retire TLABs 325 326 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) { 327 HandleMark hm; // Discard invalid handles created during verification 328 gclog_or_tty->print(" VerifyBeforeGC:"); 329 Universe::verify(); 330 } 331 332 { 333 ResourceMark rm; 334 HandleMark hm; 335 336 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); 337 GCTraceTime t1(GCCauseString("GC", gc_cause), PrintGC, !PrintGCDetails, NULL); 338 TraceCollectorStats tcs(counters()); 339 TraceMemoryManagerStats tms(false /* not full GC */,gc_cause); 340 341 if (TraceGen0Time) accumulated_time()->start(); 342 343 // Let the size policy know we're starting 344 size_policy->minor_collection_begin(); 345 346 // Verify the object start arrays. 347 if (VerifyObjectStartArray && 348 VerifyBeforeGC) { 349 old_gen->verify_object_start_array(); 350 perm_gen->verify_object_start_array(); 351 } 352 353 // Verify no unmarked old->young roots 354 if (VerifyRememberedSets) { 355 CardTableExtension::verify_all_young_refs_imprecise(); 356 } 357 358 if (!ScavengeWithObjectsInToSpace) { 359 assert(young_gen->to_space()->is_empty(), 360 "Attempt to scavenge with live objects in to_space"); 361 young_gen->to_space()->clear(SpaceDecorator::Mangle); 362 } else if (ZapUnusedHeapArea) { 363 young_gen->to_space()->mangle_unused_area(); 364 } 365 save_to_space_top_before_gc(); 366 367 COMPILER2_PRESENT(DerivedPointerTable::clear()); 368 369 reference_processor()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/); 370 reference_processor()->setup_policy(false); 371 372 // We track how much was promoted to the next generation for 373 // the AdaptiveSizePolicy. 374 size_t old_gen_used_before = old_gen->used_in_bytes(); 375 376 // For PrintGCDetails 377 size_t young_gen_used_before = young_gen->used_in_bytes(); 378 379 // Reset our survivor overflow. 380 set_survivor_overflow(false); 381 382 // We need to save the old/perm top values before 383 // creating the promotion_manager. We pass the top 384 // values to the card_table, to prevent it from 385 // straying into the promotion labs. 386 HeapWord* old_top = old_gen->object_space()->top(); 387 HeapWord* perm_top = perm_gen->object_space()->top(); 388 389 // Release all previously held resources 390 gc_task_manager()->release_all_resources(); 391 392 // Set the number of GC threads to be used in this collection 393 gc_task_manager()->set_active_gang(); 394 gc_task_manager()->task_idle_workers(); 395 // Get the active number of workers here and use that value 396 // throughout the methods. 397 uint active_workers = gc_task_manager()->active_workers(); 398 heap->set_par_threads(active_workers); 399 400 PSPromotionManager::pre_scavenge(); 401 402 // We'll use the promotion manager again later. 403 PSPromotionManager* promotion_manager = PSPromotionManager::vm_thread_promotion_manager(); 404 { 405 GCTraceTime tm("Scavenge", false, false, &_gc_timer); 406 ParallelScavengeHeap::ParStrongRootsScope psrs; 407 408 GCTaskQueue* q = GCTaskQueue::create(); 409 410 uint stripe_total = active_workers; 411 for(uint i=0; i < stripe_total; i++) { 412 q->enqueue(new OldToYoungRootsTask(old_gen, old_top, i, stripe_total)); 413 } 414 415 q->enqueue(new SerialOldToYoungRootsTask(perm_gen, perm_top)); 416 417 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::universe)); 418 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jni_handles)); 419 // We scan the thread roots in parallel 420 Threads::create_thread_roots_tasks(q); 421 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::object_synchronizer)); 422 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::flat_profiler)); 423 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::management)); 424 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::system_dictionary)); 425 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jvmti)); 426 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::code_cache)); 427 428 ParallelTaskTerminator terminator( 429 active_workers, 430 (TaskQueueSetSuper*) promotion_manager->stack_array_depth()); 431 if (active_workers > 1) { 432 for (uint j = 0; j < active_workers; j++) { 433 q->enqueue(new StealTask(&terminator)); 434 } 435 } 436 437 gc_task_manager()->execute_and_wait(q); 438 } 439 440 scavenge_midpoint.update(); 441 442 // Process reference objects discovered during scavenge 443 { 444 GCTraceTime tm("References", false, false, &_gc_timer); 445 446 reference_processor()->setup_policy(false); // not always_clear 447 reference_processor()->set_active_mt_degree(active_workers); 448 PSKeepAliveClosure keep_alive(promotion_manager); 449 PSEvacuateFollowersClosure evac_followers(promotion_manager); 450 ReferenceProcessorStats stats; 451 if (reference_processor()->processing_is_mt()) { 452 PSRefProcTaskExecutor task_executor; 453 stats = reference_processor()->process_discovered_references( 454 &_is_alive_closure, &keep_alive, &evac_followers, &task_executor, 455 &_gc_timer); 456 } else { 457 stats = reference_processor()->process_discovered_references( 458 &_is_alive_closure, &keep_alive, &evac_followers, NULL, &_gc_timer); 459 } 460 461 _gc_tracer.report_gc_reference_stats(stats); 462 463 // Enqueue reference objects discovered during scavenge. 464 if (reference_processor()->processing_is_mt()) { 465 PSRefProcTaskExecutor task_executor; 466 reference_processor()->enqueue_discovered_references(&task_executor); 467 } else { 468 reference_processor()->enqueue_discovered_references(NULL); 469 } 470 } 471 472 if (!JavaObjectsInPerm) { 473 GCTraceTime tm("StringTable", false, false, &_gc_timer); 474 // Unlink any dead interned Strings 475 StringTable::unlink(&_is_alive_closure); 476 // Process the remaining live ones 477 PSScavengeRootsClosure root_closure(promotion_manager); 478 StringTable::oops_do(&root_closure); 479 } 480 481 // Finally, flush the promotion_manager's labs, and deallocate its stacks. 482 promotion_failure_occurred = PSPromotionManager::post_scavenge(_gc_tracer); 483 if (promotion_failure_occurred) { 484 clean_up_failed_promotion(); 485 if (PrintGC) { 486 gclog_or_tty->print("--"); 487 } 488 } 489 490 // Let the size policy know we're done. Note that we count promotion 491 // failure cleanup time as part of the collection (otherwise, we're 492 // implicitly saying it's mutator time). 493 size_policy->minor_collection_end(gc_cause); 494 495 if (!promotion_failure_occurred) { 496 // Swap the survivor spaces. 497 young_gen->eden_space()->clear(SpaceDecorator::Mangle); 498 young_gen->from_space()->clear(SpaceDecorator::Mangle); 499 young_gen->swap_spaces(); 500 501 size_t survived = young_gen->from_space()->used_in_bytes(); 502 size_t promoted = old_gen->used_in_bytes() - old_gen_used_before; 503 size_policy->update_averages(_survivor_overflow, survived, promoted); 504 505 // A successful scavenge should restart the GC time limit count which is 506 // for full GC's. 507 size_policy->reset_gc_overhead_limit_count(); 508 if (UseAdaptiveSizePolicy) { 509 // Calculate the new survivor size and tenuring threshold 510 511 if (PrintAdaptiveSizePolicy) { 512 gclog_or_tty->print("AdaptiveSizeStart: "); 513 gclog_or_tty->stamp(); 514 gclog_or_tty->print_cr(" collection: %d ", 515 heap->total_collections()); 516 517 if (Verbose) { 518 gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d" 519 " perm_gen_capacity: %d ", 520 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes(), 521 perm_gen->capacity_in_bytes()); 522 } 523 } 524 525 526 if (UsePerfData) { 527 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 528 counters->update_old_eden_size( 529 size_policy->calculated_eden_size_in_bytes()); 530 counters->update_old_promo_size( 531 size_policy->calculated_promo_size_in_bytes()); 532 counters->update_old_capacity(old_gen->capacity_in_bytes()); 533 counters->update_young_capacity(young_gen->capacity_in_bytes()); 534 counters->update_survived(survived); 535 counters->update_promoted(promoted); 536 counters->update_survivor_overflowed(_survivor_overflow); 537 } 538 539 size_t survivor_limit = 540 size_policy->max_survivor_size(young_gen->max_size()); 541 _tenuring_threshold = 542 size_policy->compute_survivor_space_size_and_threshold( 543 _survivor_overflow, 544 _tenuring_threshold, 545 survivor_limit); 546 547 if (PrintTenuringDistribution) { 548 gclog_or_tty->cr(); 549 gclog_or_tty->print_cr("Desired survivor size %ld bytes, new threshold %d (max %d)", 550 size_policy->calculated_survivor_size_in_bytes(), 551 _tenuring_threshold, MaxTenuringThreshold); 552 } 553 554 if (UsePerfData) { 555 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 556 counters->update_tenuring_threshold(_tenuring_threshold); 557 counters->update_survivor_size_counters(); 558 } 559 560 // Do call at minor collections? 561 // Don't check if the size_policy is ready at this 562 // level. Let the size_policy check that internally. 563 if (UseAdaptiveSizePolicy && 564 UseAdaptiveGenerationSizePolicyAtMinorCollection && 565 ((gc_cause != GCCause::_java_lang_system_gc) || 566 UseAdaptiveSizePolicyWithSystemGC)) { 567 568 // Calculate optimial free space amounts 569 assert(young_gen->max_size() > 570 young_gen->from_space()->capacity_in_bytes() + 571 young_gen->to_space()->capacity_in_bytes(), 572 "Sizes of space in young gen are out-of-bounds"); 573 size_t max_eden_size = young_gen->max_size() - 574 young_gen->from_space()->capacity_in_bytes() - 575 young_gen->to_space()->capacity_in_bytes(); 576 size_policy->compute_generation_free_space(young_gen->used_in_bytes(), 577 young_gen->eden_space()->used_in_bytes(), 578 old_gen->used_in_bytes(), 579 perm_gen->used_in_bytes(), 580 young_gen->eden_space()->capacity_in_bytes(), 581 old_gen->max_gen_size(), 582 max_eden_size, 583 false /* full gc*/, 584 gc_cause, 585 heap->collector_policy()); 586 587 } 588 // Resize the young generation at every collection 589 // even if new sizes have not been calculated. This is 590 // to allow resizes that may have been inhibited by the 591 // relative location of the "to" and "from" spaces. 592 593 // Resizing the old gen at minor collects can cause increases 594 // that don't feed back to the generation sizing policy until 595 // a major collection. Don't resize the old gen here. 596 597 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(), 598 size_policy->calculated_survivor_size_in_bytes()); 599 600 if (PrintAdaptiveSizePolicy) { 601 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ", 602 heap->total_collections()); 603 } 604 } 605 606 // Update the structure of the eden. With NUMA-eden CPU hotplugging or offlining can 607 // cause the change of the heap layout. Make sure eden is reshaped if that's the case. 608 // Also update() will case adaptive NUMA chunk resizing. 609 assert(young_gen->eden_space()->is_empty(), "eden space should be empty now"); 610 young_gen->eden_space()->update(); 611 612 heap->gc_policy_counters()->update_counters(); 613 614 heap->resize_all_tlabs(); 615 616 assert(young_gen->to_space()->is_empty(), "to space should be empty now"); 617 } 618 619 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 620 621 NOT_PRODUCT(reference_processor()->verify_no_references_recorded()); 622 623 { 624 GCTraceTime tm("Prune Scavenge Root Methods", false, false, &_gc_timer); 625 626 CodeCache::prune_scavenge_root_nmethods(); 627 } 628 629 // Re-verify object start arrays 630 if (VerifyObjectStartArray && 631 VerifyAfterGC) { 632 old_gen->verify_object_start_array(); 633 perm_gen->verify_object_start_array(); 634 } 635 636 // Verify all old -> young cards are now precise 637 if (VerifyRememberedSets) { 638 // Precise verification will give false positives. Until this is fixed, 639 // use imprecise verification. 640 // CardTableExtension::verify_all_young_refs_precise(); 641 CardTableExtension::verify_all_young_refs_imprecise(); 642 } 643 644 if (TraceGen0Time) accumulated_time()->stop(); 645 646 if (PrintGC) { 647 if (PrintGCDetails) { 648 // Don't print a GC timestamp here. This is after the GC so 649 // would be confusing. 650 young_gen->print_used_change(young_gen_used_before); 651 } 652 heap->print_heap_change(prev_used); 653 } 654 655 // Track memory usage and detect low memory 656 MemoryService::track_memory_usage(); 657 heap->update_counters(); 658 659 gc_task_manager()->release_idle_workers(); 660 } 661 662 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) { 663 HandleMark hm; // Discard invalid handles created during verification 664 gclog_or_tty->print(" VerifyAfterGC:"); 665 Universe::verify(); 666 } 667 668 heap->print_heap_after_gc(); 669 heap->trace_heap_after_gc(&_gc_tracer); 670 _gc_tracer.report_tenuring_threshold(tenuring_threshold()); 671 672 if (ZapUnusedHeapArea) { 673 young_gen->eden_space()->check_mangled_unused_area_complete(); 674 young_gen->from_space()->check_mangled_unused_area_complete(); 675 young_gen->to_space()->check_mangled_unused_area_complete(); 676 } 677 678 scavenge_exit.update(); 679 680 if (PrintGCTaskTimeStamps) { 681 tty->print_cr("VM-Thread " INT64_FORMAT " " INT64_FORMAT " " INT64_FORMAT, 682 scavenge_entry.ticks(), scavenge_midpoint.ticks(), 683 scavenge_exit.ticks()); 684 gc_task_manager()->print_task_time_stamps(); 685 } 686 687 #ifdef TRACESPINNING 688 ParallelTaskTerminator::print_termination_counts(); 689 #endif 690 691 692 _gc_timer.register_gc_end(os::elapsed_counter()); 693 694 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions()); 695 696 return !promotion_failure_occurred; 697 } 698 699 // This method iterates over all objects in the young generation, 700 // unforwarding markOops. It then restores any preserved mark oops, 701 // and clears the _preserved_mark_stack. 702 void PSScavenge::clean_up_failed_promotion() { 703 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 704 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 705 706 PSYoungGen* young_gen = heap->young_gen(); 707 708 { 709 ResourceMark rm; 710 711 // Unforward all pointers in the young gen. 712 PSPromotionFailedClosure unforward_closure; 713 young_gen->object_iterate(&unforward_closure); 714 715 if (PrintGC && Verbose) { 716 gclog_or_tty->print_cr("Restoring %d marks", _preserved_oop_stack.size()); 717 } 718 719 // Restore any saved marks. 720 while (!_preserved_oop_stack.is_empty()) { 721 oop obj = _preserved_oop_stack.pop(); 722 markOop mark = _preserved_mark_stack.pop(); 723 obj->set_mark(mark); 724 } 725 726 // Clear the preserved mark and oop stack caches. 727 _preserved_mark_stack.clear(true); 728 _preserved_oop_stack.clear(true); 729 } 730 731 // Reset the PromotionFailureALot counters. 732 NOT_PRODUCT(Universe::heap()->reset_promotion_should_fail();) 733 } 734 735 // This method is called whenever an attempt to promote an object 736 // fails. Some markOops will need preservation, some will not. Note 737 // that the entire eden is traversed after a failed promotion, with 738 // all forwarded headers replaced by the default markOop. This means 739 // it is not necessary to preserve most markOops. 740 void PSScavenge::oop_promotion_failed(oop obj, markOop obj_mark) { 741 if (obj_mark->must_be_preserved_for_promotion_failure(obj)) { 742 // Should use per-worker private stacks here rather than 743 // locking a common pair of stacks. 744 ThreadCritical tc; 745 _preserved_oop_stack.push(obj); 746 _preserved_mark_stack.push(obj_mark); 747 } 748 } 749 750 bool PSScavenge::should_attempt_scavenge() { 751 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 752 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 753 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 754 755 if (UsePerfData) { 756 counters->update_scavenge_skipped(not_skipped); 757 } 758 759 PSYoungGen* young_gen = heap->young_gen(); 760 PSOldGen* old_gen = heap->old_gen(); 761 762 if (!ScavengeWithObjectsInToSpace) { 763 // Do not attempt to promote unless to_space is empty 764 if (!young_gen->to_space()->is_empty()) { 765 _consecutive_skipped_scavenges++; 766 if (UsePerfData) { 767 counters->update_scavenge_skipped(to_space_not_empty); 768 } 769 return false; 770 } 771 } 772 773 // Test to see if the scavenge will likely fail. 774 PSAdaptiveSizePolicy* policy = heap->size_policy(); 775 776 // A similar test is done in the policy's should_full_GC(). If this is 777 // changed, decide if that test should also be changed. 778 size_t avg_promoted = (size_t) policy->padded_average_promoted_in_bytes(); 779 size_t promotion_estimate = MIN2(avg_promoted, young_gen->used_in_bytes()); 780 bool result = promotion_estimate < old_gen->free_in_bytes(); 781 782 if (PrintGCDetails && Verbose) { 783 gclog_or_tty->print(result ? " do scavenge: " : " skip scavenge: "); 784 gclog_or_tty->print_cr(" average_promoted " SIZE_FORMAT 785 " padded_average_promoted " SIZE_FORMAT 786 " free in old gen " SIZE_FORMAT, 787 (size_t) policy->average_promoted_in_bytes(), 788 (size_t) policy->padded_average_promoted_in_bytes(), 789 old_gen->free_in_bytes()); 790 if (young_gen->used_in_bytes() < 791 (size_t) policy->padded_average_promoted_in_bytes()) { 792 gclog_or_tty->print_cr(" padded_promoted_average is greater" 793 " than maximum promotion = " SIZE_FORMAT, young_gen->used_in_bytes()); 794 } 795 } 796 797 if (result) { 798 _consecutive_skipped_scavenges = 0; 799 } else { 800 _consecutive_skipped_scavenges++; 801 if (UsePerfData) { 802 counters->update_scavenge_skipped(promoted_too_large); 803 } 804 } 805 return result; 806 } 807 808 // Used to add tasks 809 GCTaskManager* const PSScavenge::gc_task_manager() { 810 assert(ParallelScavengeHeap::gc_task_manager() != NULL, 811 "shouldn't return NULL"); 812 return ParallelScavengeHeap::gc_task_manager(); 813 } 814 815 void PSScavenge::initialize() { 816 // Arguments must have been parsed 817 818 if (AlwaysTenure) { 819 _tenuring_threshold = 0; 820 } else if (NeverTenure) { 821 _tenuring_threshold = markOopDesc::max_age + 1; 822 } else { 823 // We want to smooth out our startup times for the AdaptiveSizePolicy 824 _tenuring_threshold = (UseAdaptiveSizePolicy) ? InitialTenuringThreshold : 825 MaxTenuringThreshold; 826 } 827 828 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 829 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 830 831 PSYoungGen* young_gen = heap->young_gen(); 832 PSOldGen* old_gen = heap->old_gen(); 833 PSPermGen* perm_gen = heap->perm_gen(); 834 835 // Set boundary between young_gen and old_gen 836 assert(perm_gen->reserved().end() <= old_gen->object_space()->bottom(), 837 "perm above old"); 838 assert(old_gen->reserved().end() <= young_gen->eden_space()->bottom(), 839 "old above young"); 840 _young_generation_boundary = young_gen->eden_space()->bottom(); 841 842 // Initialize ref handling object for scavenging. 843 MemRegion mr = young_gen->reserved(); 844 845 _ref_processor = 846 new ReferenceProcessor(mr, // span 847 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing 848 (int) ParallelGCThreads, // mt processing degree 849 true, // mt discovery 850 (int) ParallelGCThreads, // mt discovery degree 851 true, // atomic_discovery 852 NULL, // header provides liveness info 853 false); // next field updates do not need write barrier 854 855 // Cache the cardtable 856 BarrierSet* bs = Universe::heap()->barrier_set(); 857 assert(bs->kind() == BarrierSet::CardTableModRef, "Wrong barrier set kind"); 858 _card_table = (CardTableExtension*)bs; 859 860 _counters = new CollectorCounters("PSScavenge", 0); 861 }