1 2 /* 3 * Copyright (c) 2002, 2014, Oracle and/or its affiliates. All rights reserved. 4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 5 * 6 * This code is free software; you can redistribute it and/or modify it 7 * under the terms of the GNU General Public License version 2 only, as 8 * published by the Free Software Foundation. 9 * 10 * This code is distributed in the hope that it will be useful, but WITHOUT 11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 13 * version 2 for more details (a copy is included in the LICENSE file that 14 * accompanied this code). 15 * 16 * You should have received a copy of the GNU General Public License version 17 * 2 along with this work; if not, write to the Free Software Foundation, 18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 19 * 20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 21 * or visit www.oracle.com if you need additional information or have any 22 * questions. 23 * 24 */ 25 26 #include "precompiled.hpp" 27 #include "classfile/stringTable.hpp" 28 #include "code/codeCache.hpp" 29 #include "gc_implementation/parallelScavenge/cardTableExtension.hpp" 30 #include "gc_implementation/parallelScavenge/gcTaskManager.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 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC 61 62 HeapWord* PSScavenge::_to_space_top_before_gc = NULL; 63 int PSScavenge::_consecutive_skipped_scavenges = 0; 64 ReferenceProcessor* PSScavenge::_ref_processor = NULL; 65 CardTableExtension* PSScavenge::_card_table = NULL; 66 bool PSScavenge::_survivor_overflow = false; 67 uint PSScavenge::_tenuring_threshold = 0; 68 HeapWord* PSScavenge::_young_generation_boundary = NULL; 69 uintptr_t PSScavenge::_young_generation_boundary_compressed = 0; 70 elapsedTimer PSScavenge::_accumulated_time; 71 STWGCTimer PSScavenge::_gc_timer; 72 ParallelScavengeTracer PSScavenge::_gc_tracer; 73 Stack<markOop, mtGC> PSScavenge::_preserved_mark_stack; 74 Stack<oop, mtGC> PSScavenge::_preserved_oop_stack; 75 CollectorCounters* PSScavenge::_counters = NULL; 76 77 // Define before use 78 class PSIsAliveClosure: public BoolObjectClosure { 79 public: 80 bool do_object_b(oop p) { 81 return (!PSScavenge::is_obj_in_young(p)) || p->is_forwarded(); 82 } 83 }; 84 85 PSIsAliveClosure PSScavenge::_is_alive_closure; 86 87 class PSKeepAliveClosure: public OopClosure { 88 protected: 89 MutableSpace* _to_space; 90 PSPromotionManager* _promotion_manager; 91 92 public: 93 PSKeepAliveClosure(PSPromotionManager* pm) : _promotion_manager(pm) { 94 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 95 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 96 _to_space = heap->young_gen()->to_space(); 97 98 assert(_promotion_manager != NULL, "Sanity"); 99 } 100 101 template <class T> void do_oop_work(T* p) { 102 assert (!oopDesc::is_null(*p), "expected non-null ref"); 103 assert ((oopDesc::load_decode_heap_oop_not_null(p))->is_oop(), 104 "expected an oop while scanning weak refs"); 105 106 // Weak refs may be visited more than once. 107 if (PSScavenge::should_scavenge(p, _to_space)) { 108 PSScavenge::copy_and_push_safe_barrier<T, /*promote_immediately=*/false>(_promotion_manager, p); 109 } 110 } 111 virtual void do_oop(oop* p) { PSKeepAliveClosure::do_oop_work(p); } 112 virtual void do_oop(narrowOop* p) { PSKeepAliveClosure::do_oop_work(p); } 113 }; 114 115 class PSEvacuateFollowersClosure: public VoidClosure { 116 private: 117 PSPromotionManager* _promotion_manager; 118 public: 119 PSEvacuateFollowersClosure(PSPromotionManager* pm) : _promotion_manager(pm) {} 120 121 virtual void do_void() { 122 assert(_promotion_manager != NULL, "Sanity"); 123 _promotion_manager->drain_stacks(true); 124 guarantee(_promotion_manager->stacks_empty(), 125 "stacks should be empty at this point"); 126 } 127 }; 128 129 class PSPromotionFailedClosure : public ObjectClosure { 130 virtual void do_object(oop obj) { 131 if (obj->is_forwarded()) { 132 obj->init_mark(); 133 } 134 } 135 }; 136 137 class PSRefProcTaskProxy: public GCTask { 138 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 139 ProcessTask & _rp_task; 140 uint _work_id; 141 public: 142 PSRefProcTaskProxy(ProcessTask & rp_task, uint work_id) 143 : _rp_task(rp_task), 144 _work_id(work_id) 145 { } 146 147 private: 148 virtual char* name() { return (char *)"Process referents by policy in parallel"; } 149 virtual void do_it(GCTaskManager* manager, uint which); 150 }; 151 152 void PSRefProcTaskProxy::do_it(GCTaskManager* manager, uint which) 153 { 154 PSPromotionManager* promotion_manager = 155 PSPromotionManager::gc_thread_promotion_manager(which); 156 assert(promotion_manager != NULL, "sanity check"); 157 PSKeepAliveClosure keep_alive(promotion_manager); 158 PSEvacuateFollowersClosure evac_followers(promotion_manager); 159 PSIsAliveClosure is_alive; 160 _rp_task.work(_work_id, is_alive, keep_alive, evac_followers); 161 } 162 163 class PSRefEnqueueTaskProxy: public GCTask { 164 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 165 EnqueueTask& _enq_task; 166 uint _work_id; 167 168 public: 169 PSRefEnqueueTaskProxy(EnqueueTask& enq_task, uint work_id) 170 : _enq_task(enq_task), 171 _work_id(work_id) 172 { } 173 174 virtual char* name() { return (char *)"Enqueue reference objects in parallel"; } 175 virtual void do_it(GCTaskManager* manager, uint which) 176 { 177 _enq_task.work(_work_id); 178 } 179 }; 180 181 class PSRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 182 virtual void execute(ProcessTask& task); 183 virtual void execute(EnqueueTask& task); 184 }; 185 186 void PSRefProcTaskExecutor::execute(ProcessTask& task) 187 { 188 GCTaskQueue* q = GCTaskQueue::create(); 189 GCTaskManager* manager = ParallelScavengeHeap::gc_task_manager(); 190 for(uint i=0; i < manager->active_workers(); i++) { 191 q->enqueue(new PSRefProcTaskProxy(task, i)); 192 } 193 ParallelTaskTerminator terminator(manager->active_workers(), 194 (TaskQueueSetSuper*) PSPromotionManager::stack_array_depth()); 195 if (task.marks_oops_alive() && manager->active_workers() > 1) { 196 for (uint j = 0; j < manager->active_workers(); j++) { 197 q->enqueue(new StealTask(&terminator)); 198 } 199 } 200 manager->execute_and_wait(q); 201 } 202 203 204 void PSRefProcTaskExecutor::execute(EnqueueTask& task) 205 { 206 GCTaskQueue* q = GCTaskQueue::create(); 207 GCTaskManager* manager = ParallelScavengeHeap::gc_task_manager(); 208 for(uint i=0; i < manager->active_workers(); i++) { 209 q->enqueue(new PSRefEnqueueTaskProxy(task, i)); 210 } 211 manager->execute_and_wait(q); 212 } 213 214 // This method contains all heap specific policy for invoking scavenge. 215 // PSScavenge::invoke_no_policy() will do nothing but attempt to 216 // scavenge. It will not clean up after failed promotions, bail out if 217 // we've exceeded policy time limits, or any other special behavior. 218 // All such policy should be placed here. 219 // 220 // Note that this method should only be called from the vm_thread while 221 // at a safepoint! 222 bool PSScavenge::invoke() { 223 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 224 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread"); 225 assert(!Universe::heap()->is_gc_active(), "not reentrant"); 226 227 ParallelScavengeHeap* const heap = (ParallelScavengeHeap*)Universe::heap(); 228 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 229 230 PSAdaptiveSizePolicy* policy = heap->size_policy(); 231 IsGCActiveMark mark; 232 233 const bool scavenge_done = PSScavenge::invoke_no_policy(); 234 const bool need_full_gc = !scavenge_done || 235 policy->should_full_GC(heap->old_gen()->free_in_bytes()); 236 bool full_gc_done = false; 237 238 if (UsePerfData) { 239 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters(); 240 const int ffs_val = need_full_gc ? full_follows_scavenge : not_skipped; 241 counters->update_full_follows_scavenge(ffs_val); 242 } 243 244 if (need_full_gc) { 245 GCCauseSetter gccs(heap, GCCause::_adaptive_size_policy); 246 CollectorPolicy* cp = heap->collector_policy(); 247 const bool clear_all_softrefs = cp->should_clear_all_soft_refs(); 248 249 if (UseParallelOldGC) { 250 full_gc_done = PSParallelCompact::invoke_no_policy(clear_all_softrefs); 251 } else { 252 full_gc_done = PSMarkSweep::invoke_no_policy(clear_all_softrefs); 253 } 254 } 255 256 return full_gc_done; 257 } 258 259 // This method contains no policy. You should probably 260 // be calling invoke() instead. 261 bool PSScavenge::invoke_no_policy() { 262 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 263 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread"); 264 265 assert(_preserved_mark_stack.is_empty(), "should be empty"); 266 assert(_preserved_oop_stack.is_empty(), "should be empty"); 267 268 _gc_timer.register_gc_start(); 269 270 TimeStamp scavenge_entry; 271 TimeStamp scavenge_midpoint; 272 TimeStamp scavenge_exit; 273 274 scavenge_entry.update(); 275 276 if (GC_locker::check_active_before_gc()) { 277 return false; 278 } 279 280 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 281 GCCause::Cause gc_cause = heap->gc_cause(); 282 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 283 284 // Check for potential problems. 285 if (!should_attempt_scavenge()) { 286 return false; 287 } 288 289 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start()); 290 291 bool promotion_failure_occurred = false; 292 293 PSYoungGen* young_gen = heap->young_gen(); 294 PSOldGen* old_gen = heap->old_gen(); 295 PSAdaptiveSizePolicy* size_policy = heap->size_policy(); 296 297 heap->increment_total_collections(); 298 299 AdaptiveSizePolicyOutput(size_policy, heap->total_collections()); 300 301 if ((gc_cause != GCCause::_java_lang_system_gc) || 302 UseAdaptiveSizePolicyWithSystemGC) { 303 // Gather the feedback data for eden occupancy. 304 young_gen->eden_space()->accumulate_statistics(); 305 } 306 307 if (ZapUnusedHeapArea) { 308 // Save information needed to minimize mangling 309 heap->record_gen_tops_before_GC(); 310 } 311 312 heap->print_heap_before_gc(); 313 heap->trace_heap_before_gc(&_gc_tracer); 314 315 assert(!NeverTenure || _tenuring_threshold == markOopDesc::max_age + 1, "Sanity"); 316 assert(!AlwaysTenure || _tenuring_threshold == 0, "Sanity"); 317 318 size_t prev_used = heap->used(); 319 320 // Fill in TLABs 321 heap->accumulate_statistics_all_tlabs(); 322 heap->ensure_parsability(true); // retire TLABs 323 324 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) { 325 HandleMark hm; // Discard invalid handles created during verification 326 Universe::verify(" VerifyBeforeGC:"); 327 } 328 329 { 330 ResourceMark rm; 331 HandleMark hm; 332 333 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps); 334 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); 335 GCTraceTime t1(GCCauseString("GC", gc_cause), PrintGC, !PrintGCDetails, NULL, _gc_tracer.gc_id()); 336 TraceCollectorStats tcs(counters()); 337 TraceMemoryManagerStats tms(false /* not full GC */,gc_cause); 338 339 if (TraceYoungGenTime) accumulated_time()->start(); 340 341 // Let the size policy know we're starting 342 size_policy->minor_collection_begin(); 343 344 // Verify the object start arrays. 345 if (VerifyObjectStartArray && 346 VerifyBeforeGC) { 347 old_gen->verify_object_start_array(); 348 } 349 350 // Verify no unmarked old->young roots 351 if (VerifyRememberedSets) { 352 CardTableExtension::verify_all_young_refs_imprecise(); 353 } 354 355 if (!ScavengeWithObjectsInToSpace) { 356 assert(young_gen->to_space()->is_empty(), 357 "Attempt to scavenge with live objects in to_space"); 358 young_gen->to_space()->clear(SpaceDecorator::Mangle); 359 } else if (ZapUnusedHeapArea) { 360 young_gen->to_space()->mangle_unused_area(); 361 } 362 save_to_space_top_before_gc(); 363 364 COMPILER2_PRESENT(DerivedPointerTable::clear()); 365 366 reference_processor()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/); 367 reference_processor()->setup_policy(false); 368 369 // We track how much was promoted to the next generation for 370 // the AdaptiveSizePolicy. 371 size_t old_gen_used_before = old_gen->used_in_bytes(); 372 373 // For PrintGCDetails 374 size_t young_gen_used_before = young_gen->used_in_bytes(); 375 376 // Reset our survivor overflow. 377 set_survivor_overflow(false); 378 379 // We need to save the old top values before 380 // creating the promotion_manager. We pass the top 381 // values to the card_table, to prevent it from 382 // straying into the promotion labs. 383 HeapWord* old_top = old_gen->object_space()->top(); 384 385 // Release all previously held resources 386 gc_task_manager()->release_all_resources(); 387 388 // Set the number of GC threads to be used in this collection 389 gc_task_manager()->set_active_gang(); 390 gc_task_manager()->task_idle_workers(); 391 // Get the active number of workers here and use that value 392 // throughout the methods. 393 uint active_workers = gc_task_manager()->active_workers(); 394 heap->set_par_threads(active_workers); 395 396 PSPromotionManager::pre_scavenge(); 397 398 // We'll use the promotion manager again later. 399 PSPromotionManager* promotion_manager = PSPromotionManager::vm_thread_promotion_manager(); 400 { 401 GCTraceTime tm("Scavenge", false, false, &_gc_timer, _gc_tracer.gc_id()); 402 ParallelScavengeHeap::ParStrongRootsScope psrs; 403 404 GCTaskQueue* q = GCTaskQueue::create(); 405 406 if (!old_gen->object_space()->is_empty()) { 407 // There are only old-to-young pointers if there are objects 408 // in the old gen. 409 uint stripe_total = active_workers; 410 for(uint i=0; i < stripe_total; i++) { 411 q->enqueue(new OldToYoungRootsTask(old_gen, old_top, i, stripe_total)); 412 } 413 } 414 415 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::universe)); 416 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jni_handles)); 417 // We scan the thread roots in parallel 418 Threads::create_thread_roots_tasks(q); 419 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::object_synchronizer)); 420 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::flat_profiler)); 421 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::management)); 422 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::system_dictionary)); 423 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::class_loader_data)); 424 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jvmti)); 425 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::code_cache)); 426 427 ParallelTaskTerminator terminator( 428 active_workers, 429 (TaskQueueSetSuper*) promotion_manager->stack_array_depth()); 430 if (active_workers > 1) { 431 for (uint j = 0; j < active_workers; j++) { 432 q->enqueue(new StealTask(&terminator)); 433 } 434 } 435 436 gc_task_manager()->execute_and_wait(q); 437 } 438 439 scavenge_midpoint.update(); 440 441 // Process reference objects discovered during scavenge 442 { 443 GCTraceTime tm("References", false, false, &_gc_timer, _gc_tracer.gc_id()); 444 445 reference_processor()->setup_policy(false); // not always_clear 446 reference_processor()->set_active_mt_degree(active_workers); 447 PSKeepAliveClosure keep_alive(promotion_manager); 448 PSEvacuateFollowersClosure evac_followers(promotion_manager); 449 ReferenceProcessorStats stats; 450 if (reference_processor()->processing_is_mt()) { 451 PSRefProcTaskExecutor task_executor; 452 stats = reference_processor()->process_discovered_references( 453 &_is_alive_closure, &keep_alive, &evac_followers, &task_executor, 454 &_gc_timer, _gc_tracer.gc_id()); 455 } else { 456 stats = reference_processor()->process_discovered_references( 457 &_is_alive_closure, &keep_alive, &evac_followers, NULL, &_gc_timer, _gc_tracer.gc_id()); 458 } 459 460 _gc_tracer.report_gc_reference_stats(stats); 461 462 // Enqueue reference objects discovered during scavenge. 463 if (reference_processor()->processing_is_mt()) { 464 PSRefProcTaskExecutor task_executor; 465 reference_processor()->enqueue_discovered_references(&task_executor); 466 } else { 467 reference_processor()->enqueue_discovered_references(NULL); 468 } 469 } 470 471 { 472 GCTraceTime tm("StringTable", false, false, &_gc_timer, _gc_tracer.gc_id()); 473 // Unlink any dead interned Strings and process the remaining live ones. 474 PSScavengeRootsClosure root_closure(promotion_manager); 475 StringTable::unlink_or_oops_do(&_is_alive_closure, &root_closure); 476 } 477 478 // Finally, flush the promotion_manager's labs, and deallocate its stacks. 479 promotion_failure_occurred = PSPromotionManager::post_scavenge(_gc_tracer); 480 if (promotion_failure_occurred) { 481 clean_up_failed_promotion(); 482 if (PrintGC) { 483 gclog_or_tty->print("--"); 484 } 485 } 486 487 // Let the size policy know we're done. Note that we count promotion 488 // failure cleanup time as part of the collection (otherwise, we're 489 // implicitly saying it's mutator time). 490 size_policy->minor_collection_end(gc_cause); 491 492 if (!promotion_failure_occurred) { 493 // Swap the survivor spaces. 494 young_gen->eden_space()->clear(SpaceDecorator::Mangle); 495 young_gen->from_space()->clear(SpaceDecorator::Mangle); 496 young_gen->swap_spaces(); 497 498 size_t survived = young_gen->from_space()->used_in_bytes(); 499 size_t promoted = old_gen->used_in_bytes() - old_gen_used_before; 500 size_policy->update_averages(_survivor_overflow, survived, promoted); 501 502 // A successful scavenge should restart the GC time limit count which is 503 // for full GC's. 504 size_policy->reset_gc_overhead_limit_count(); 505 if (UseAdaptiveSizePolicy) { 506 // Calculate the new survivor size and tenuring threshold 507 508 if (PrintAdaptiveSizePolicy) { 509 gclog_or_tty->print("AdaptiveSizeStart: "); 510 gclog_or_tty->stamp(); 511 gclog_or_tty->print_cr(" collection: %d ", 512 heap->total_collections()); 513 514 if (Verbose) { 515 gclog_or_tty->print("old_gen_capacity: " SIZE_FORMAT 516 " young_gen_capacity: " SIZE_FORMAT, 517 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes()); 518 } 519 } 520 521 522 if (UsePerfData) { 523 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 524 counters->update_old_eden_size( 525 size_policy->calculated_eden_size_in_bytes()); 526 counters->update_old_promo_size( 527 size_policy->calculated_promo_size_in_bytes()); 528 counters->update_old_capacity(old_gen->capacity_in_bytes()); 529 counters->update_young_capacity(young_gen->capacity_in_bytes()); 530 counters->update_survived(survived); 531 counters->update_promoted(promoted); 532 counters->update_survivor_overflowed(_survivor_overflow); 533 } 534 535 size_t max_young_size = young_gen->max_size(); 536 537 // Deciding a free ratio in the young generation is tricky, so if 538 // MinHeapFreeRatio or MaxHeapFreeRatio are in use (implicating 539 // that the old generation size may have been limited because of them) we 540 // should then limit our young generation size using NewRatio to have it 541 // follow the old generation size. 542 if (MinHeapFreeRatio != 0 || MaxHeapFreeRatio != 100) { 543 max_young_size = MIN2(old_gen->capacity_in_bytes() / NewRatio, young_gen->max_size()); 544 } 545 546 size_t survivor_limit = 547 size_policy->max_survivor_size(max_young_size); 548 _tenuring_threshold = 549 size_policy->compute_survivor_space_size_and_threshold( 550 _survivor_overflow, 551 _tenuring_threshold, 552 survivor_limit); 553 554 if (PrintTenuringDistribution) { 555 gclog_or_tty->cr(); 556 gclog_or_tty->print_cr("Desired survivor size " SIZE_FORMAT " bytes, new threshold " 557 UINTX_FORMAT " (max threshold " UINTX_FORMAT ")", 558 size_policy->calculated_survivor_size_in_bytes(), 559 _tenuring_threshold, MaxTenuringThreshold); 560 } 561 562 if (UsePerfData) { 563 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 564 counters->update_tenuring_threshold(_tenuring_threshold); 565 counters->update_survivor_size_counters(); 566 } 567 568 // Do call at minor collections? 569 // Don't check if the size_policy is ready at this 570 // level. Let the size_policy check that internally. 571 if (UseAdaptiveGenerationSizePolicyAtMinorCollection && 572 ((gc_cause != GCCause::_java_lang_system_gc) || 573 UseAdaptiveSizePolicyWithSystemGC)) { 574 575 // Calculate optimal free space amounts 576 assert(young_gen->max_size() > 577 young_gen->from_space()->capacity_in_bytes() + 578 young_gen->to_space()->capacity_in_bytes(), 579 "Sizes of space in young gen are out-of-bounds"); 580 581 size_t young_live = young_gen->used_in_bytes(); 582 size_t eden_live = young_gen->eden_space()->used_in_bytes(); 583 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes(); 584 size_t max_old_gen_size = old_gen->max_gen_size(); 585 size_t max_eden_size = max_young_size - 586 young_gen->from_space()->capacity_in_bytes() - 587 young_gen->to_space()->capacity_in_bytes(); 588 589 // Used for diagnostics 590 size_policy->clear_generation_free_space_flags(); 591 592 size_policy->compute_eden_space_size(young_live, 593 eden_live, 594 cur_eden, 595 max_eden_size, 596 false /* not full gc*/); 597 598 size_policy->check_gc_overhead_limit(young_live, 599 eden_live, 600 max_old_gen_size, 601 max_eden_size, 602 false /* not full gc*/, 603 gc_cause, 604 heap->collector_policy()); 605 606 size_policy->decay_supplemental_growth(false /* not full gc*/); 607 } 608 // Resize the young generation at every collection 609 // even if new sizes have not been calculated. This is 610 // to allow resizes that may have been inhibited by the 611 // relative location of the "to" and "from" spaces. 612 613 // Resizing the old gen at minor collects can cause increases 614 // that don't feed back to the generation sizing policy until 615 // a major collection. Don't resize the old gen here. 616 617 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(), 618 size_policy->calculated_survivor_size_in_bytes()); 619 620 if (PrintAdaptiveSizePolicy) { 621 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ", 622 heap->total_collections()); 623 } 624 } 625 626 // Update the structure of the eden. With NUMA-eden CPU hotplugging or offlining can 627 // cause the change of the heap layout. Make sure eden is reshaped if that's the case. 628 // Also update() will case adaptive NUMA chunk resizing. 629 assert(young_gen->eden_space()->is_empty(), "eden space should be empty now"); 630 young_gen->eden_space()->update(); 631 632 heap->gc_policy_counters()->update_counters(); 633 634 heap->resize_all_tlabs(); 635 636 assert(young_gen->to_space()->is_empty(), "to space should be empty now"); 637 } 638 639 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 640 641 NOT_PRODUCT(reference_processor()->verify_no_references_recorded()); 642 643 { 644 GCTraceTime tm("Prune Scavenge Root Methods", false, false, &_gc_timer, _gc_tracer.gc_id()); 645 646 CodeCache::prune_scavenge_root_nmethods(); 647 } 648 649 // Re-verify object start arrays 650 if (VerifyObjectStartArray && 651 VerifyAfterGC) { 652 old_gen->verify_object_start_array(); 653 } 654 655 // Verify all old -> young cards are now precise 656 if (VerifyRememberedSets) { 657 // Precise verification will give false positives. Until this is fixed, 658 // use imprecise verification. 659 // CardTableExtension::verify_all_young_refs_precise(); 660 CardTableExtension::verify_all_young_refs_imprecise(); 661 } 662 663 if (TraceYoungGenTime) accumulated_time()->stop(); 664 665 if (PrintGC) { 666 if (PrintGCDetails) { 667 // Don't print a GC timestamp here. This is after the GC so 668 // would be confusing. 669 young_gen->print_used_change(young_gen_used_before); 670 } 671 heap->print_heap_change(prev_used); 672 } 673 674 // Track memory usage and detect low memory 675 MemoryService::track_memory_usage(); 676 heap->update_counters(); 677 678 gc_task_manager()->release_idle_workers(); 679 } 680 681 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) { 682 HandleMark hm; // Discard invalid handles created during verification 683 Universe::verify(" VerifyAfterGC:"); 684 } 685 686 heap->print_heap_after_gc(); 687 heap->trace_heap_after_gc(&_gc_tracer); 688 _gc_tracer.report_tenuring_threshold(tenuring_threshold()); 689 690 if (ZapUnusedHeapArea) { 691 young_gen->eden_space()->check_mangled_unused_area_complete(); 692 young_gen->from_space()->check_mangled_unused_area_complete(); 693 young_gen->to_space()->check_mangled_unused_area_complete(); 694 } 695 696 scavenge_exit.update(); 697 698 if (PrintGCTaskTimeStamps) { 699 tty->print_cr("VM-Thread " INT64_FORMAT " " INT64_FORMAT " " INT64_FORMAT, 700 scavenge_entry.ticks(), scavenge_midpoint.ticks(), 701 scavenge_exit.ticks()); 702 gc_task_manager()->print_task_time_stamps(); 703 } 704 705 #ifdef TRACESPINNING 706 ParallelTaskTerminator::print_termination_counts(); 707 #endif 708 709 710 _gc_timer.register_gc_end(); 711 712 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions()); 713 714 return !promotion_failure_occurred; 715 } 716 717 // This method iterates over all objects in the young generation, 718 // unforwarding markOops. It then restores any preserved mark oops, 719 // and clears the _preserved_mark_stack. 720 void PSScavenge::clean_up_failed_promotion() { 721 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 722 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 723 724 PSYoungGen* young_gen = heap->young_gen(); 725 726 { 727 ResourceMark rm; 728 729 // Unforward all pointers in the young gen. 730 PSPromotionFailedClosure unforward_closure; 731 young_gen->object_iterate(&unforward_closure); 732 733 if (PrintGC && Verbose) { 734 gclog_or_tty->print_cr("Restoring " SIZE_FORMAT " marks", _preserved_oop_stack.size()); 735 } 736 737 // Restore any saved marks. 738 while (!_preserved_oop_stack.is_empty()) { 739 oop obj = _preserved_oop_stack.pop(); 740 markOop mark = _preserved_mark_stack.pop(); 741 obj->set_mark(mark); 742 } 743 744 // Clear the preserved mark and oop stack caches. 745 _preserved_mark_stack.clear(true); 746 _preserved_oop_stack.clear(true); 747 } 748 749 // Reset the PromotionFailureALot counters. 750 NOT_PRODUCT(Universe::heap()->reset_promotion_should_fail();) 751 } 752 753 // This method is called whenever an attempt to promote an object 754 // fails. Some markOops will need preservation, some will not. Note 755 // that the entire eden is traversed after a failed promotion, with 756 // all forwarded headers replaced by the default markOop. This means 757 // it is not necessary to preserve most markOops. 758 void PSScavenge::oop_promotion_failed(oop obj, markOop obj_mark) { 759 if (obj_mark->must_be_preserved_for_promotion_failure(obj)) { 760 // Should use per-worker private stacks here rather than 761 // locking a common pair of stacks. 762 ThreadCritical tc; 763 _preserved_oop_stack.push(obj); 764 _preserved_mark_stack.push(obj_mark); 765 } 766 } 767 768 bool PSScavenge::should_attempt_scavenge() { 769 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 770 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 771 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 772 773 if (UsePerfData) { 774 counters->update_scavenge_skipped(not_skipped); 775 } 776 777 PSYoungGen* young_gen = heap->young_gen(); 778 PSOldGen* old_gen = heap->old_gen(); 779 780 if (!ScavengeWithObjectsInToSpace) { 781 // Do not attempt to promote unless to_space is empty 782 if (!young_gen->to_space()->is_empty()) { 783 _consecutive_skipped_scavenges++; 784 if (UsePerfData) { 785 counters->update_scavenge_skipped(to_space_not_empty); 786 } 787 return false; 788 } 789 } 790 791 // Test to see if the scavenge will likely fail. 792 PSAdaptiveSizePolicy* policy = heap->size_policy(); 793 794 // A similar test is done in the policy's should_full_GC(). If this is 795 // changed, decide if that test should also be changed. 796 size_t avg_promoted = (size_t) policy->padded_average_promoted_in_bytes(); 797 size_t promotion_estimate = MIN2(avg_promoted, young_gen->used_in_bytes()); 798 bool result = promotion_estimate < old_gen->free_in_bytes(); 799 800 if (PrintGCDetails && Verbose) { 801 gclog_or_tty->print(result ? " do scavenge: " : " skip scavenge: "); 802 gclog_or_tty->print_cr(" average_promoted " SIZE_FORMAT 803 " padded_average_promoted " SIZE_FORMAT 804 " free in old gen " SIZE_FORMAT, 805 (size_t) policy->average_promoted_in_bytes(), 806 (size_t) policy->padded_average_promoted_in_bytes(), 807 old_gen->free_in_bytes()); 808 if (young_gen->used_in_bytes() < 809 (size_t) policy->padded_average_promoted_in_bytes()) { 810 gclog_or_tty->print_cr(" padded_promoted_average is greater" 811 " than maximum promotion = " SIZE_FORMAT, young_gen->used_in_bytes()); 812 } 813 } 814 815 if (result) { 816 _consecutive_skipped_scavenges = 0; 817 } else { 818 _consecutive_skipped_scavenges++; 819 if (UsePerfData) { 820 counters->update_scavenge_skipped(promoted_too_large); 821 } 822 } 823 return result; 824 } 825 826 // Used to add tasks 827 GCTaskManager* const PSScavenge::gc_task_manager() { 828 assert(ParallelScavengeHeap::gc_task_manager() != NULL, 829 "shouldn't return NULL"); 830 return ParallelScavengeHeap::gc_task_manager(); 831 } 832 833 void PSScavenge::initialize() { 834 // Arguments must have been parsed 835 836 if (AlwaysTenure || NeverTenure) { 837 assert(MaxTenuringThreshold == 0 || MaxTenuringThreshold == markOopDesc::max_age + 1, 838 err_msg("MaxTenuringThreshold should be 0 or markOopDesc::max_age + 1, but is %d", (int) MaxTenuringThreshold)); 839 _tenuring_threshold = MaxTenuringThreshold; 840 } else { 841 // We want to smooth out our startup times for the AdaptiveSizePolicy 842 _tenuring_threshold = (UseAdaptiveSizePolicy) ? InitialTenuringThreshold : 843 MaxTenuringThreshold; 844 } 845 846 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 847 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 848 849 PSYoungGen* young_gen = heap->young_gen(); 850 PSOldGen* old_gen = heap->old_gen(); 851 852 // Set boundary between young_gen and old_gen 853 assert(old_gen->reserved().end() <= young_gen->eden_space()->bottom(), 854 "old above young"); 855 set_young_generation_boundary(young_gen->eden_space()->bottom()); 856 857 // Initialize ref handling object for scavenging. 858 MemRegion mr = young_gen->reserved(); 859 860 _ref_processor = 861 new ReferenceProcessor(mr, // span 862 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing 863 (int) ParallelGCThreads, // mt processing degree 864 true, // mt discovery 865 (int) ParallelGCThreads, // mt discovery degree 866 true, // atomic_discovery 867 NULL); // header provides liveness info 868 869 // Cache the cardtable 870 BarrierSet* bs = Universe::heap()->barrier_set(); 871 assert(bs->kind() == BarrierSet::CardTableModRef, "Wrong barrier set kind"); 872 _card_table = (CardTableExtension*)bs; 873 874 _counters = new CollectorCounters("PSScavenge", 0); 875 }