1 /* 2 * Copyright (c) 2002, 2010, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 26 # include "incls/_precompiled.incl" 27 # include "incls/_psScavenge.cpp.incl" 28 29 HeapWord* PSScavenge::_to_space_top_before_gc = NULL; 30 int PSScavenge::_consecutive_skipped_scavenges = 0; 31 ReferenceProcessor* PSScavenge::_ref_processor = NULL; 32 CardTableExtension* PSScavenge::_card_table = NULL; 33 bool PSScavenge::_survivor_overflow = false; 34 int PSScavenge::_tenuring_threshold = 0; 35 HeapWord* PSScavenge::_young_generation_boundary = NULL; 36 elapsedTimer PSScavenge::_accumulated_time; 37 Stack<markOop> PSScavenge::_preserved_mark_stack; 38 Stack<oop> PSScavenge::_preserved_oop_stack; 39 CollectorCounters* PSScavenge::_counters = NULL; 40 bool PSScavenge::_promotion_failed = false; 41 42 // Define before use 43 class PSIsAliveClosure: public BoolObjectClosure { 44 public: 45 void do_object(oop p) { 46 assert(false, "Do not call."); 47 } 48 bool do_object_b(oop p) { 49 return (!PSScavenge::is_obj_in_young((HeapWord*) p)) || p->is_forwarded(); 50 } 51 }; 52 53 PSIsAliveClosure PSScavenge::_is_alive_closure; 54 55 class PSKeepAliveClosure: public OopClosure { 56 protected: 57 MutableSpace* _to_space; 58 PSPromotionManager* _promotion_manager; 59 60 public: 61 PSKeepAliveClosure(PSPromotionManager* pm) : _promotion_manager(pm) { 62 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 63 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 64 _to_space = heap->young_gen()->to_space(); 65 66 assert(_promotion_manager != NULL, "Sanity"); 67 } 68 69 template <class T> void do_oop_work(T* p) { 70 assert (!oopDesc::is_null(*p), "expected non-null ref"); 71 assert ((oopDesc::load_decode_heap_oop_not_null(p))->is_oop(), 72 "expected an oop while scanning weak refs"); 73 74 // Weak refs may be visited more than once. 75 if (PSScavenge::should_scavenge(p, _to_space)) { 76 PSScavenge::copy_and_push_safe_barrier(_promotion_manager, p); 77 } 78 } 79 virtual void do_oop(oop* p) { PSKeepAliveClosure::do_oop_work(p); } 80 virtual void do_oop(narrowOop* p) { PSKeepAliveClosure::do_oop_work(p); } 81 }; 82 83 class PSEvacuateFollowersClosure: public VoidClosure { 84 private: 85 PSPromotionManager* _promotion_manager; 86 public: 87 PSEvacuateFollowersClosure(PSPromotionManager* pm) : _promotion_manager(pm) {} 88 89 virtual void do_void() { 90 assert(_promotion_manager != NULL, "Sanity"); 91 _promotion_manager->drain_stacks(true); 92 guarantee(_promotion_manager->stacks_empty(), 93 "stacks should be empty at this point"); 94 } 95 }; 96 97 class PSPromotionFailedClosure : public ObjectClosure { 98 virtual void do_object(oop obj) { 99 if (obj->is_forwarded()) { 100 obj->init_mark(); 101 } 102 } 103 }; 104 105 class PSRefProcTaskProxy: public GCTask { 106 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 107 ProcessTask & _rp_task; 108 uint _work_id; 109 public: 110 PSRefProcTaskProxy(ProcessTask & rp_task, uint work_id) 111 : _rp_task(rp_task), 112 _work_id(work_id) 113 { } 114 115 private: 116 virtual char* name() { return (char *)"Process referents by policy in parallel"; } 117 virtual void do_it(GCTaskManager* manager, uint which); 118 }; 119 120 void PSRefProcTaskProxy::do_it(GCTaskManager* manager, uint which) 121 { 122 PSPromotionManager* promotion_manager = 123 PSPromotionManager::gc_thread_promotion_manager(which); 124 assert(promotion_manager != NULL, "sanity check"); 125 PSKeepAliveClosure keep_alive(promotion_manager); 126 PSEvacuateFollowersClosure evac_followers(promotion_manager); 127 PSIsAliveClosure is_alive; 128 _rp_task.work(_work_id, is_alive, keep_alive, evac_followers); 129 } 130 131 class PSRefEnqueueTaskProxy: public GCTask { 132 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 133 EnqueueTask& _enq_task; 134 uint _work_id; 135 136 public: 137 PSRefEnqueueTaskProxy(EnqueueTask& enq_task, uint work_id) 138 : _enq_task(enq_task), 139 _work_id(work_id) 140 { } 141 142 virtual char* name() { return (char *)"Enqueue reference objects in parallel"; } 143 virtual void do_it(GCTaskManager* manager, uint which) 144 { 145 _enq_task.work(_work_id); 146 } 147 }; 148 149 class PSRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 150 virtual void execute(ProcessTask& task); 151 virtual void execute(EnqueueTask& task); 152 }; 153 154 void PSRefProcTaskExecutor::execute(ProcessTask& task) 155 { 156 GCTaskQueue* q = GCTaskQueue::create(); 157 for(uint i=0; i<ParallelGCThreads; i++) { 158 q->enqueue(new PSRefProcTaskProxy(task, i)); 159 } 160 ParallelTaskTerminator terminator( 161 ParallelScavengeHeap::gc_task_manager()->workers(), 162 (TaskQueueSetSuper*) PSPromotionManager::stack_array_depth()); 163 if (task.marks_oops_alive() && ParallelGCThreads > 1) { 164 for (uint j=0; j<ParallelGCThreads; j++) { 165 q->enqueue(new StealTask(&terminator)); 166 } 167 } 168 ParallelScavengeHeap::gc_task_manager()->execute_and_wait(q); 169 } 170 171 172 void PSRefProcTaskExecutor::execute(EnqueueTask& task) 173 { 174 GCTaskQueue* q = GCTaskQueue::create(); 175 for(uint i=0; i<ParallelGCThreads; i++) { 176 q->enqueue(new PSRefEnqueueTaskProxy(task, i)); 177 } 178 ParallelScavengeHeap::gc_task_manager()->execute_and_wait(q); 179 } 180 181 // This method contains all heap specific policy for invoking scavenge. 182 // PSScavenge::invoke_no_policy() will do nothing but attempt to 183 // scavenge. It will not clean up after failed promotions, bail out if 184 // we've exceeded policy time limits, or any other special behavior. 185 // All such policy should be placed here. 186 // 187 // Note that this method should only be called from the vm_thread while 188 // at a safepoint! 189 void PSScavenge::invoke() { 190 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 191 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread"); 192 assert(!Universe::heap()->is_gc_active(), "not reentrant"); 193 194 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 195 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 196 197 PSAdaptiveSizePolicy* policy = heap->size_policy(); 198 IsGCActiveMark mark; 199 200 bool scavenge_was_done = PSScavenge::invoke_no_policy(); 201 202 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 203 if (UsePerfData) 204 counters->update_full_follows_scavenge(0); 205 if (!scavenge_was_done || 206 policy->should_full_GC(heap->old_gen()->free_in_bytes())) { 207 if (UsePerfData) 208 counters->update_full_follows_scavenge(full_follows_scavenge); 209 GCCauseSetter gccs(heap, GCCause::_adaptive_size_policy); 210 CollectorPolicy* cp = heap->collector_policy(); 211 const bool clear_all_softrefs = cp->should_clear_all_soft_refs(); 212 213 if (UseParallelOldGC) { 214 PSParallelCompact::invoke_no_policy(clear_all_softrefs); 215 } else { 216 PSMarkSweep::invoke_no_policy(clear_all_softrefs); 217 } 218 } 219 } 220 221 // This method contains no policy. You should probably 222 // be calling invoke() instead. 223 bool PSScavenge::invoke_no_policy() { 224 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 225 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread"); 226 227 assert(_preserved_mark_stack.is_empty(), "should be empty"); 228 assert(_preserved_oop_stack.is_empty(), "should be empty"); 229 230 TimeStamp scavenge_entry; 231 TimeStamp scavenge_midpoint; 232 TimeStamp scavenge_exit; 233 234 scavenge_entry.update(); 235 236 if (GC_locker::check_active_before_gc()) { 237 return false; 238 } 239 240 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 241 GCCause::Cause gc_cause = heap->gc_cause(); 242 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 243 244 // Check for potential problems. 245 if (!should_attempt_scavenge()) { 246 return false; 247 } 248 249 bool promotion_failure_occurred = false; 250 251 PSYoungGen* young_gen = heap->young_gen(); 252 PSOldGen* old_gen = heap->old_gen(); 253 PSPermGen* perm_gen = heap->perm_gen(); 254 PSAdaptiveSizePolicy* size_policy = heap->size_policy(); 255 heap->increment_total_collections(); 256 257 AdaptiveSizePolicyOutput(size_policy, heap->total_collections()); 258 259 if ((gc_cause != GCCause::_java_lang_system_gc) || 260 UseAdaptiveSizePolicyWithSystemGC) { 261 // Gather the feedback data for eden occupancy. 262 young_gen->eden_space()->accumulate_statistics(); 263 } 264 265 if (ZapUnusedHeapArea) { 266 // Save information needed to minimize mangling 267 heap->record_gen_tops_before_GC(); 268 } 269 270 if (PrintHeapAtGC) { 271 Universe::print_heap_before_gc(); 272 } 273 274 assert(!NeverTenure || _tenuring_threshold == markOopDesc::max_age + 1, "Sanity"); 275 assert(!AlwaysTenure || _tenuring_threshold == 0, "Sanity"); 276 277 size_t prev_used = heap->used(); 278 assert(promotion_failed() == false, "Sanity"); 279 280 // Fill in TLABs 281 heap->accumulate_statistics_all_tlabs(); 282 heap->ensure_parsability(true); // retire TLABs 283 284 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) { 285 HandleMark hm; // Discard invalid handles created during verification 286 gclog_or_tty->print(" VerifyBeforeGC:"); 287 Universe::verify(true); 288 } 289 290 { 291 ResourceMark rm; 292 HandleMark hm; 293 294 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps); 295 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); 296 TraceTime t1("GC", PrintGC, !PrintGCDetails, gclog_or_tty); 297 TraceCollectorStats tcs(counters()); 298 TraceMemoryManagerStats tms(false /* not full GC */); 299 300 if (TraceGen0Time) accumulated_time()->start(); 301 302 // Let the size policy know we're starting 303 size_policy->minor_collection_begin(); 304 305 // Verify the object start arrays. 306 if (VerifyObjectStartArray && 307 VerifyBeforeGC) { 308 old_gen->verify_object_start_array(); 309 perm_gen->verify_object_start_array(); 310 } 311 312 // Verify no unmarked old->young roots 313 if (VerifyRememberedSets) { 314 CardTableExtension::verify_all_young_refs_imprecise(); 315 } 316 317 if (!ScavengeWithObjectsInToSpace) { 318 assert(young_gen->to_space()->is_empty(), 319 "Attempt to scavenge with live objects in to_space"); 320 young_gen->to_space()->clear(SpaceDecorator::Mangle); 321 } else if (ZapUnusedHeapArea) { 322 young_gen->to_space()->mangle_unused_area(); 323 } 324 save_to_space_top_before_gc(); 325 326 NOT_PRODUCT(reference_processor()->verify_no_references_recorded()); 327 COMPILER2_PRESENT(DerivedPointerTable::clear()); 328 329 reference_processor()->enable_discovery(); 330 reference_processor()->setup_policy(false); 331 332 // We track how much was promoted to the next generation for 333 // the AdaptiveSizePolicy. 334 size_t old_gen_used_before = old_gen->used_in_bytes(); 335 336 // For PrintGCDetails 337 size_t young_gen_used_before = young_gen->used_in_bytes(); 338 339 // Reset our survivor overflow. 340 set_survivor_overflow(false); 341 342 // We need to save the old/perm top values before 343 // creating the promotion_manager. We pass the top 344 // values to the card_table, to prevent it from 345 // straying into the promotion labs. 346 HeapWord* old_top = old_gen->object_space()->top(); 347 HeapWord* perm_top = perm_gen->object_space()->top(); 348 349 // Release all previously held resources 350 gc_task_manager()->release_all_resources(); 351 352 PSPromotionManager::pre_scavenge(); 353 354 // We'll use the promotion manager again later. 355 PSPromotionManager* promotion_manager = PSPromotionManager::vm_thread_promotion_manager(); 356 { 357 // TraceTime("Roots"); 358 ParallelScavengeHeap::ParStrongRootsScope psrs; 359 360 GCTaskQueue* q = GCTaskQueue::create(); 361 362 for(uint i=0; i<ParallelGCThreads; i++) { 363 q->enqueue(new OldToYoungRootsTask(old_gen, old_top, i)); 364 } 365 366 q->enqueue(new SerialOldToYoungRootsTask(perm_gen, perm_top)); 367 368 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::universe)); 369 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jni_handles)); 370 // We scan the thread roots in parallel 371 Threads::create_thread_roots_tasks(q); 372 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::object_synchronizer)); 373 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::flat_profiler)); 374 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::management)); 375 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::system_dictionary)); 376 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jvmti)); 377 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::code_cache)); 378 379 ParallelTaskTerminator terminator( 380 gc_task_manager()->workers(), 381 (TaskQueueSetSuper*) promotion_manager->stack_array_depth()); 382 if (ParallelGCThreads>1) { 383 for (uint j=0; j<ParallelGCThreads; j++) { 384 q->enqueue(new StealTask(&terminator)); 385 } 386 } 387 388 gc_task_manager()->execute_and_wait(q); 389 } 390 391 scavenge_midpoint.update(); 392 393 // Process reference objects discovered during scavenge 394 { 395 reference_processor()->setup_policy(false); // not always_clear 396 PSKeepAliveClosure keep_alive(promotion_manager); 397 PSEvacuateFollowersClosure evac_followers(promotion_manager); 398 if (reference_processor()->processing_is_mt()) { 399 PSRefProcTaskExecutor task_executor; 400 reference_processor()->process_discovered_references( 401 &_is_alive_closure, &keep_alive, &evac_followers, &task_executor); 402 } else { 403 reference_processor()->process_discovered_references( 404 &_is_alive_closure, &keep_alive, &evac_followers, NULL); 405 } 406 } 407 408 // Enqueue reference objects discovered during scavenge. 409 if (reference_processor()->processing_is_mt()) { 410 PSRefProcTaskExecutor task_executor; 411 reference_processor()->enqueue_discovered_references(&task_executor); 412 } else { 413 reference_processor()->enqueue_discovered_references(NULL); 414 } 415 416 // Finally, flush the promotion_manager's labs, and deallocate its stacks. 417 PSPromotionManager::post_scavenge(); 418 419 promotion_failure_occurred = promotion_failed(); 420 if (promotion_failure_occurred) { 421 clean_up_failed_promotion(); 422 if (PrintGC) { 423 gclog_or_tty->print("--"); 424 } 425 } 426 427 // Let the size policy know we're done. Note that we count promotion 428 // failure cleanup time as part of the collection (otherwise, we're 429 // implicitly saying it's mutator time). 430 size_policy->minor_collection_end(gc_cause); 431 432 if (!promotion_failure_occurred) { 433 // Swap the survivor spaces. 434 435 436 young_gen->eden_space()->clear(SpaceDecorator::Mangle); 437 young_gen->from_space()->clear(SpaceDecorator::Mangle); 438 young_gen->swap_spaces(); 439 440 size_t survived = young_gen->from_space()->used_in_bytes(); 441 size_t promoted = old_gen->used_in_bytes() - old_gen_used_before; 442 size_policy->update_averages(_survivor_overflow, survived, promoted); 443 444 // A successful scavenge should restart the GC time limit count which is 445 // for full GC's. 446 size_policy->reset_gc_overhead_limit_count(); 447 if (UseAdaptiveSizePolicy) { 448 // Calculate the new survivor size and tenuring threshold 449 450 if (PrintAdaptiveSizePolicy) { 451 gclog_or_tty->print("AdaptiveSizeStart: "); 452 gclog_or_tty->stamp(); 453 gclog_or_tty->print_cr(" collection: %d ", 454 heap->total_collections()); 455 456 if (Verbose) { 457 gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d" 458 " perm_gen_capacity: %d ", 459 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes(), 460 perm_gen->capacity_in_bytes()); 461 } 462 } 463 464 465 if (UsePerfData) { 466 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 467 counters->update_old_eden_size( 468 size_policy->calculated_eden_size_in_bytes()); 469 counters->update_old_promo_size( 470 size_policy->calculated_promo_size_in_bytes()); 471 counters->update_old_capacity(old_gen->capacity_in_bytes()); 472 counters->update_young_capacity(young_gen->capacity_in_bytes()); 473 counters->update_survived(survived); 474 counters->update_promoted(promoted); 475 counters->update_survivor_overflowed(_survivor_overflow); 476 } 477 478 size_t survivor_limit = 479 size_policy->max_survivor_size(young_gen->max_size()); 480 _tenuring_threshold = 481 size_policy->compute_survivor_space_size_and_threshold( 482 _survivor_overflow, 483 _tenuring_threshold, 484 survivor_limit); 485 486 if (PrintTenuringDistribution) { 487 gclog_or_tty->cr(); 488 gclog_or_tty->print_cr("Desired survivor size %ld bytes, new threshold %d (max %d)", 489 size_policy->calculated_survivor_size_in_bytes(), 490 _tenuring_threshold, MaxTenuringThreshold); 491 } 492 493 if (UsePerfData) { 494 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 495 counters->update_tenuring_threshold(_tenuring_threshold); 496 counters->update_survivor_size_counters(); 497 } 498 499 // Do call at minor collections? 500 // Don't check if the size_policy is ready at this 501 // level. Let the size_policy check that internally. 502 if (UseAdaptiveSizePolicy && 503 UseAdaptiveGenerationSizePolicyAtMinorCollection && 504 ((gc_cause != GCCause::_java_lang_system_gc) || 505 UseAdaptiveSizePolicyWithSystemGC)) { 506 507 // Calculate optimial free space amounts 508 assert(young_gen->max_size() > 509 young_gen->from_space()->capacity_in_bytes() + 510 young_gen->to_space()->capacity_in_bytes(), 511 "Sizes of space in young gen are out-of-bounds"); 512 size_t max_eden_size = young_gen->max_size() - 513 young_gen->from_space()->capacity_in_bytes() - 514 young_gen->to_space()->capacity_in_bytes(); 515 size_policy->compute_generation_free_space(young_gen->used_in_bytes(), 516 young_gen->eden_space()->used_in_bytes(), 517 old_gen->used_in_bytes(), 518 perm_gen->used_in_bytes(), 519 young_gen->eden_space()->capacity_in_bytes(), 520 old_gen->max_gen_size(), 521 max_eden_size, 522 false /* full gc*/, 523 gc_cause, 524 heap->collector_policy()); 525 526 } 527 // Resize the young generation at every collection 528 // even if new sizes have not been calculated. This is 529 // to allow resizes that may have been inhibited by the 530 // relative location of the "to" and "from" spaces. 531 532 // Resizing the old gen at minor collects can cause increases 533 // that don't feed back to the generation sizing policy until 534 // a major collection. Don't resize the old gen here. 535 536 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(), 537 size_policy->calculated_survivor_size_in_bytes()); 538 539 if (PrintAdaptiveSizePolicy) { 540 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ", 541 heap->total_collections()); 542 } 543 } 544 545 // Update the structure of the eden. With NUMA-eden CPU hotplugging or offlining can 546 // cause the change of the heap layout. Make sure eden is reshaped if that's the case. 547 // Also update() will case adaptive NUMA chunk resizing. 548 assert(young_gen->eden_space()->is_empty(), "eden space should be empty now"); 549 young_gen->eden_space()->update(); 550 551 heap->gc_policy_counters()->update_counters(); 552 553 heap->resize_all_tlabs(); 554 555 assert(young_gen->to_space()->is_empty(), "to space should be empty now"); 556 } 557 558 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 559 560 NOT_PRODUCT(reference_processor()->verify_no_references_recorded()); 561 562 // Re-verify object start arrays 563 if (VerifyObjectStartArray && 564 VerifyAfterGC) { 565 old_gen->verify_object_start_array(); 566 perm_gen->verify_object_start_array(); 567 } 568 569 // Verify all old -> young cards are now precise 570 if (VerifyRememberedSets) { 571 // Precise verification will give false positives. Until this is fixed, 572 // use imprecise verification. 573 // CardTableExtension::verify_all_young_refs_precise(); 574 CardTableExtension::verify_all_young_refs_imprecise(); 575 } 576 577 if (TraceGen0Time) accumulated_time()->stop(); 578 579 if (PrintGC) { 580 if (PrintGCDetails) { 581 // Don't print a GC timestamp here. This is after the GC so 582 // would be confusing. 583 young_gen->print_used_change(young_gen_used_before); 584 } 585 heap->print_heap_change(prev_used); 586 } 587 588 // Track memory usage and detect low memory 589 MemoryService::track_memory_usage(); 590 heap->update_counters(); 591 } 592 593 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) { 594 HandleMark hm; // Discard invalid handles created during verification 595 gclog_or_tty->print(" VerifyAfterGC:"); 596 Universe::verify(false); 597 } 598 599 if (PrintHeapAtGC) { 600 Universe::print_heap_after_gc(); 601 } 602 603 if (ZapUnusedHeapArea) { 604 young_gen->eden_space()->check_mangled_unused_area_complete(); 605 young_gen->from_space()->check_mangled_unused_area_complete(); 606 young_gen->to_space()->check_mangled_unused_area_complete(); 607 } 608 609 scavenge_exit.update(); 610 611 if (PrintGCTaskTimeStamps) { 612 tty->print_cr("VM-Thread " INT64_FORMAT " " INT64_FORMAT " " INT64_FORMAT, 613 scavenge_entry.ticks(), scavenge_midpoint.ticks(), 614 scavenge_exit.ticks()); 615 gc_task_manager()->print_task_time_stamps(); 616 } 617 618 #ifdef TRACESPINNING 619 ParallelTaskTerminator::print_termination_counts(); 620 #endif 621 622 return !promotion_failure_occurred; 623 } 624 625 // This method iterates over all objects in the young generation, 626 // unforwarding markOops. It then restores any preserved mark oops, 627 // and clears the _preserved_mark_stack. 628 void PSScavenge::clean_up_failed_promotion() { 629 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 630 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 631 assert(promotion_failed(), "Sanity"); 632 633 PSYoungGen* young_gen = heap->young_gen(); 634 635 { 636 ResourceMark rm; 637 638 // Unforward all pointers in the young gen. 639 PSPromotionFailedClosure unforward_closure; 640 young_gen->object_iterate(&unforward_closure); 641 642 if (PrintGC && Verbose) { 643 gclog_or_tty->print_cr("Restoring %d marks", _preserved_oop_stack.size()); 644 } 645 646 // Restore any saved marks. 647 while (!_preserved_oop_stack.is_empty()) { 648 oop obj = _preserved_oop_stack.pop(); 649 markOop mark = _preserved_mark_stack.pop(); 650 obj->set_mark(mark); 651 } 652 653 // Clear the preserved mark and oop stack caches. 654 _preserved_mark_stack.clear(true); 655 _preserved_oop_stack.clear(true); 656 _promotion_failed = false; 657 } 658 659 // Reset the PromotionFailureALot counters. 660 NOT_PRODUCT(Universe::heap()->reset_promotion_should_fail();) 661 } 662 663 // This method is called whenever an attempt to promote an object 664 // fails. Some markOops will need preservation, some will not. Note 665 // that the entire eden is traversed after a failed promotion, with 666 // all forwarded headers replaced by the default markOop. This means 667 // it is not neccessary to preserve most markOops. 668 void PSScavenge::oop_promotion_failed(oop obj, markOop obj_mark) { 669 _promotion_failed = true; 670 if (obj_mark->must_be_preserved_for_promotion_failure(obj)) { 671 ThreadCritical tc; 672 _preserved_oop_stack.push(obj); 673 _preserved_mark_stack.push(obj_mark); 674 } 675 } 676 677 bool PSScavenge::should_attempt_scavenge() { 678 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 679 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 680 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 681 682 if (UsePerfData) { 683 counters->update_scavenge_skipped(not_skipped); 684 } 685 686 PSYoungGen* young_gen = heap->young_gen(); 687 PSOldGen* old_gen = heap->old_gen(); 688 689 if (!ScavengeWithObjectsInToSpace) { 690 // Do not attempt to promote unless to_space is empty 691 if (!young_gen->to_space()->is_empty()) { 692 _consecutive_skipped_scavenges++; 693 if (UsePerfData) { 694 counters->update_scavenge_skipped(to_space_not_empty); 695 } 696 return false; 697 } 698 } 699 700 // Test to see if the scavenge will likely fail. 701 PSAdaptiveSizePolicy* policy = heap->size_policy(); 702 703 // A similar test is done in the policy's should_full_GC(). If this is 704 // changed, decide if that test should also be changed. 705 size_t avg_promoted = (size_t) policy->padded_average_promoted_in_bytes(); 706 size_t promotion_estimate = MIN2(avg_promoted, young_gen->used_in_bytes()); 707 bool result = promotion_estimate < old_gen->free_in_bytes(); 708 709 if (PrintGCDetails && Verbose) { 710 gclog_or_tty->print(result ? " do scavenge: " : " skip scavenge: "); 711 gclog_or_tty->print_cr(" average_promoted " SIZE_FORMAT 712 " padded_average_promoted " SIZE_FORMAT 713 " free in old gen " SIZE_FORMAT, 714 (size_t) policy->average_promoted_in_bytes(), 715 (size_t) policy->padded_average_promoted_in_bytes(), 716 old_gen->free_in_bytes()); 717 if (young_gen->used_in_bytes() < 718 (size_t) policy->padded_average_promoted_in_bytes()) { 719 gclog_or_tty->print_cr(" padded_promoted_average is greater" 720 " than maximum promotion = " SIZE_FORMAT, young_gen->used_in_bytes()); 721 } 722 } 723 724 if (result) { 725 _consecutive_skipped_scavenges = 0; 726 } else { 727 _consecutive_skipped_scavenges++; 728 if (UsePerfData) { 729 counters->update_scavenge_skipped(promoted_too_large); 730 } 731 } 732 return result; 733 } 734 735 // Used to add tasks 736 GCTaskManager* const PSScavenge::gc_task_manager() { 737 assert(ParallelScavengeHeap::gc_task_manager() != NULL, 738 "shouldn't return NULL"); 739 return ParallelScavengeHeap::gc_task_manager(); 740 } 741 742 void PSScavenge::initialize() { 743 // Arguments must have been parsed 744 745 if (AlwaysTenure) { 746 _tenuring_threshold = 0; 747 } else if (NeverTenure) { 748 _tenuring_threshold = markOopDesc::max_age + 1; 749 } else { 750 // We want to smooth out our startup times for the AdaptiveSizePolicy 751 _tenuring_threshold = (UseAdaptiveSizePolicy) ? InitialTenuringThreshold : 752 MaxTenuringThreshold; 753 } 754 755 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 756 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 757 758 PSYoungGen* young_gen = heap->young_gen(); 759 PSOldGen* old_gen = heap->old_gen(); 760 PSPermGen* perm_gen = heap->perm_gen(); 761 762 // Set boundary between young_gen and old_gen 763 assert(perm_gen->reserved().end() <= old_gen->object_space()->bottom(), 764 "perm above old"); 765 assert(old_gen->reserved().end() <= young_gen->eden_space()->bottom(), 766 "old above young"); 767 _young_generation_boundary = young_gen->eden_space()->bottom(); 768 769 // Initialize ref handling object for scavenging. 770 MemRegion mr = young_gen->reserved(); 771 _ref_processor = ReferenceProcessor::create_ref_processor( 772 mr, // span 773 true, // atomic_discovery 774 true, // mt_discovery 775 NULL, // is_alive_non_header 776 ParallelGCThreads, 777 ParallelRefProcEnabled); 778 779 // Cache the cardtable 780 BarrierSet* bs = Universe::heap()->barrier_set(); 781 assert(bs->kind() == BarrierSet::CardTableModRef, "Wrong barrier set kind"); 782 _card_table = (CardTableExtension*)bs; 783 784 _counters = new CollectorCounters("PSScavenge", 0); 785 }