1 /* 2 * Copyright (c) 2001, 2018, 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 "aot/aotLoader.hpp" 27 #include "classfile/stringTable.hpp" 28 #include "classfile/symbolTable.hpp" 29 #include "classfile/systemDictionary.hpp" 30 #include "code/codeCache.hpp" 31 #include "gc/parallel/parallelScavengeHeap.hpp" 32 #include "gc/parallel/psAdaptiveSizePolicy.hpp" 33 #include "gc/parallel/psMarkSweep.hpp" 34 #include "gc/parallel/psMarkSweepDecorator.hpp" 35 #include "gc/parallel/psOldGen.hpp" 36 #include "gc/parallel/psScavenge.hpp" 37 #include "gc/parallel/psYoungGen.hpp" 38 #include "gc/serial/markSweep.hpp" 39 #include "gc/shared/gcCause.hpp" 40 #include "gc/shared/gcHeapSummary.hpp" 41 #include "gc/shared/gcId.hpp" 42 #include "gc/shared/gcLocker.hpp" 43 #include "gc/shared/gcTimer.hpp" 44 #include "gc/shared/gcTrace.hpp" 45 #include "gc/shared/gcTraceTime.inline.hpp" 46 #include "gc/shared/isGCActiveMark.hpp" 47 #include "gc/shared/referencePolicy.hpp" 48 #include "gc/shared/referenceProcessor.hpp" 49 #include "gc/shared/spaceDecorator.hpp" 50 #include "gc/shared/weakProcessor.hpp" 51 #include "logging/log.hpp" 52 #include "oops/oop.inline.hpp" 53 #include "runtime/biasedLocking.hpp" 54 #include "runtime/flags/flagSetting.hpp" 55 #include "runtime/handles.inline.hpp" 56 #include "runtime/safepoint.hpp" 57 #include "runtime/vmThread.hpp" 58 #include "services/management.hpp" 59 #include "services/memoryService.hpp" 60 #include "utilities/align.hpp" 61 #include "utilities/events.hpp" 62 #include "utilities/stack.inline.hpp" 63 64 elapsedTimer PSMarkSweep::_accumulated_time; 65 jlong PSMarkSweep::_time_of_last_gc = 0; 66 CollectorCounters* PSMarkSweep::_counters = NULL; 67 68 SpanSubjectToDiscoveryClosure PSMarkSweep::_span_based_discoverer; 69 70 void PSMarkSweep::initialize() { 71 _span_based_discoverer.set_span(ParallelScavengeHeap::heap()->reserved_region()); 72 set_ref_processor(new ReferenceProcessor(&_span_based_discoverer)); // a vanilla ref proc 73 _counters = new CollectorCounters("PSMarkSweep", 1); 74 MarkSweep::initialize(); 75 } 76 77 // This method contains all heap specific policy for invoking mark sweep. 78 // PSMarkSweep::invoke_no_policy() will only attempt to mark-sweep-compact 79 // the heap. It will do nothing further. If we need to bail out for policy 80 // reasons, scavenge before full gc, or any other specialized behavior, it 81 // needs to be added here. 82 // 83 // Note that this method should only be called from the vm_thread while 84 // at a safepoint! 85 // 86 // Note that the all_soft_refs_clear flag in the collector policy 87 // may be true because this method can be called without intervening 88 // activity. For example when the heap space is tight and full measure 89 // are being taken to free space. 90 91 void PSMarkSweep::invoke(bool maximum_heap_compaction) { 92 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 93 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread"); 94 assert(!ParallelScavengeHeap::heap()->is_gc_active(), "not reentrant"); 95 96 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 97 GCCause::Cause gc_cause = heap->gc_cause(); 98 PSAdaptiveSizePolicy* policy = heap->size_policy(); 99 IsGCActiveMark mark; 100 101 if (ScavengeBeforeFullGC) { 102 PSScavenge::invoke_no_policy(); 103 } 104 105 const bool clear_all_soft_refs = 106 heap->soft_ref_policy()->should_clear_all_soft_refs(); 107 108 uint count = maximum_heap_compaction ? 1 : MarkSweepAlwaysCompactCount; 109 UIntFlagSetting flag_setting(MarkSweepAlwaysCompactCount, count); 110 PSMarkSweep::invoke_no_policy(clear_all_soft_refs || maximum_heap_compaction); 111 } 112 113 // This method contains no policy. You should probably 114 // be calling invoke() instead. 115 bool PSMarkSweep::invoke_no_policy(bool clear_all_softrefs) { 116 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint"); 117 assert(ref_processor() != NULL, "Sanity"); 118 119 if (GCLocker::check_active_before_gc()) { 120 return false; 121 } 122 123 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 124 GCCause::Cause gc_cause = heap->gc_cause(); 125 126 GCIdMark gc_id_mark; 127 _gc_timer->register_gc_start(); 128 _gc_tracer->report_gc_start(gc_cause, _gc_timer->gc_start()); 129 130 PSAdaptiveSizePolicy* size_policy = heap->size_policy(); 131 132 // The scope of casr should end after code that can change 133 // CollectorPolicy::_should_clear_all_soft_refs. 134 ClearedAllSoftRefs casr(clear_all_softrefs, heap->soft_ref_policy()); 135 136 PSYoungGen* young_gen = heap->young_gen(); 137 PSOldGen* old_gen = heap->old_gen(); 138 139 // Increment the invocation count 140 heap->increment_total_collections(true /* full */); 141 142 // Save information needed to minimize mangling 143 heap->record_gen_tops_before_GC(); 144 145 // We need to track unique mark sweep invocations as well. 146 _total_invocations++; 147 148 heap->print_heap_before_gc(); 149 heap->trace_heap_before_gc(_gc_tracer); 150 151 // Fill in TLABs 152 heap->accumulate_statistics_all_tlabs(); 153 heap->ensure_parsability(true); // retire TLABs 154 155 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) { 156 HandleMark hm; // Discard invalid handles created during verification 157 Universe::verify("Before GC"); 158 } 159 160 // Verify object start arrays 161 if (VerifyObjectStartArray && 162 VerifyBeforeGC) { 163 old_gen->verify_object_start_array(); 164 } 165 166 // Filled in below to track the state of the young gen after the collection. 167 bool eden_empty; 168 bool survivors_empty; 169 bool young_gen_empty; 170 171 { 172 HandleMark hm; 173 174 GCTraceCPUTime tcpu; 175 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause, true); 176 177 heap->pre_full_gc_dump(_gc_timer); 178 179 TraceCollectorStats tcs(counters()); 180 TraceMemoryManagerStats tms(heap->old_gc_manager(),gc_cause); 181 182 if (log_is_enabled(Debug, gc, heap, exit)) { 183 accumulated_time()->start(); 184 } 185 186 // Let the size policy know we're starting 187 size_policy->major_collection_begin(); 188 189 CodeCache::gc_prologue(); 190 BiasedLocking::preserve_marks(); 191 192 // Capture metadata size before collection for sizing. 193 size_t metadata_prev_used = MetaspaceUtils::used_bytes(); 194 195 size_t old_gen_prev_used = old_gen->used_in_bytes(); 196 size_t young_gen_prev_used = young_gen->used_in_bytes(); 197 198 allocate_stacks(); 199 200 #if COMPILER2_OR_JVMCI 201 DerivedPointerTable::clear(); 202 #endif 203 204 ref_processor()->enable_discovery(); 205 ref_processor()->setup_policy(clear_all_softrefs); 206 207 mark_sweep_phase1(clear_all_softrefs); 208 209 mark_sweep_phase2(); 210 211 #if COMPILER2_OR_JVMCI 212 // Don't add any more derived pointers during phase3 213 assert(DerivedPointerTable::is_active(), "Sanity"); 214 DerivedPointerTable::set_active(false); 215 #endif 216 217 mark_sweep_phase3(); 218 219 mark_sweep_phase4(); 220 221 restore_marks(); 222 223 deallocate_stacks(); 224 225 if (ZapUnusedHeapArea) { 226 // Do a complete mangle (top to end) because the usage for 227 // scratch does not maintain a top pointer. 228 young_gen->to_space()->mangle_unused_area_complete(); 229 } 230 231 eden_empty = young_gen->eden_space()->is_empty(); 232 if (!eden_empty) { 233 eden_empty = absorb_live_data_from_eden(size_policy, young_gen, old_gen); 234 } 235 236 // Update heap occupancy information which is used as 237 // input to soft ref clearing policy at the next gc. 238 Universe::update_heap_info_at_gc(); 239 240 survivors_empty = young_gen->from_space()->is_empty() && 241 young_gen->to_space()->is_empty(); 242 young_gen_empty = eden_empty && survivors_empty; 243 244 PSCardTable* card_table = heap->card_table(); 245 MemRegion old_mr = heap->old_gen()->reserved(); 246 if (young_gen_empty) { 247 card_table->clear(MemRegion(old_mr.start(), old_mr.end())); 248 } else { 249 card_table->invalidate(MemRegion(old_mr.start(), old_mr.end())); 250 } 251 252 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 253 ClassLoaderDataGraph::purge(); 254 MetaspaceUtils::verify_metrics(); 255 256 BiasedLocking::restore_marks(); 257 CodeCache::gc_epilogue(); 258 JvmtiExport::gc_epilogue(); 259 260 #if COMPILER2_OR_JVMCI 261 DerivedPointerTable::update_pointers(); 262 #endif 263 264 ReferenceProcessorPhaseTimes pt(_gc_timer, ref_processor()->num_queues()); 265 266 ref_processor()->enqueue_discovered_references(NULL, &pt); 267 268 pt.print_enqueue_phase(); 269 270 // Update time of last GC 271 reset_millis_since_last_gc(); 272 273 // Let the size policy know we're done 274 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause); 275 276 if (UseAdaptiveSizePolicy) { 277 278 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections()); 279 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT, 280 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes()); 281 282 // Don't check if the size_policy is ready here. Let 283 // the size_policy check that internally. 284 if (UseAdaptiveGenerationSizePolicyAtMajorCollection && 285 AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) { 286 // Swap the survivor spaces if from_space is empty. The 287 // resize_young_gen() called below is normally used after 288 // a successful young GC and swapping of survivor spaces; 289 // otherwise, it will fail to resize the young gen with 290 // the current implementation. 291 if (young_gen->from_space()->is_empty()) { 292 young_gen->from_space()->clear(SpaceDecorator::Mangle); 293 young_gen->swap_spaces(); 294 } 295 296 // Calculate optimal free space amounts 297 assert(young_gen->max_size() > 298 young_gen->from_space()->capacity_in_bytes() + 299 young_gen->to_space()->capacity_in_bytes(), 300 "Sizes of space in young gen are out-of-bounds"); 301 302 size_t young_live = young_gen->used_in_bytes(); 303 size_t eden_live = young_gen->eden_space()->used_in_bytes(); 304 size_t old_live = old_gen->used_in_bytes(); 305 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes(); 306 size_t max_old_gen_size = old_gen->max_gen_size(); 307 size_t max_eden_size = young_gen->max_size() - 308 young_gen->from_space()->capacity_in_bytes() - 309 young_gen->to_space()->capacity_in_bytes(); 310 311 // Used for diagnostics 312 size_policy->clear_generation_free_space_flags(); 313 314 size_policy->compute_generations_free_space(young_live, 315 eden_live, 316 old_live, 317 cur_eden, 318 max_old_gen_size, 319 max_eden_size, 320 true /* full gc*/); 321 322 size_policy->check_gc_overhead_limit(young_live, 323 eden_live, 324 max_old_gen_size, 325 max_eden_size, 326 true /* full gc*/, 327 gc_cause, 328 heap->soft_ref_policy()); 329 330 size_policy->decay_supplemental_growth(true /* full gc*/); 331 332 heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes()); 333 334 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(), 335 size_policy->calculated_survivor_size_in_bytes()); 336 } 337 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections()); 338 } 339 340 if (UsePerfData) { 341 heap->gc_policy_counters()->update_counters(); 342 heap->gc_policy_counters()->update_old_capacity( 343 old_gen->capacity_in_bytes()); 344 heap->gc_policy_counters()->update_young_capacity( 345 young_gen->capacity_in_bytes()); 346 } 347 348 heap->resize_all_tlabs(); 349 350 // We collected the heap, recalculate the metaspace capacity 351 MetaspaceGC::compute_new_size(); 352 353 if (log_is_enabled(Debug, gc, heap, exit)) { 354 accumulated_time()->stop(); 355 } 356 357 young_gen->print_used_change(young_gen_prev_used); 358 old_gen->print_used_change(old_gen_prev_used); 359 MetaspaceUtils::print_metaspace_change(metadata_prev_used); 360 361 // Track memory usage and detect low memory 362 MemoryService::track_memory_usage(); 363 heap->update_counters(); 364 365 heap->post_full_gc_dump(_gc_timer); 366 } 367 368 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) { 369 HandleMark hm; // Discard invalid handles created during verification 370 Universe::verify("After GC"); 371 } 372 373 // Re-verify object start arrays 374 if (VerifyObjectStartArray && 375 VerifyAfterGC) { 376 old_gen->verify_object_start_array(); 377 } 378 379 if (ZapUnusedHeapArea) { 380 old_gen->object_space()->check_mangled_unused_area_complete(); 381 } 382 383 NOT_PRODUCT(ref_processor()->verify_no_references_recorded()); 384 385 heap->print_heap_after_gc(); 386 heap->trace_heap_after_gc(_gc_tracer); 387 388 #ifdef TRACESPINNING 389 ParallelTaskTerminator::print_termination_counts(); 390 #endif 391 392 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections()); 393 394 _gc_timer->register_gc_end(); 395 396 _gc_tracer->report_gc_end(_gc_timer->gc_end(), _gc_timer->time_partitions()); 397 398 return true; 399 } 400 401 bool PSMarkSweep::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy, 402 PSYoungGen* young_gen, 403 PSOldGen* old_gen) { 404 MutableSpace* const eden_space = young_gen->eden_space(); 405 assert(!eden_space->is_empty(), "eden must be non-empty"); 406 assert(young_gen->virtual_space()->alignment() == 407 old_gen->virtual_space()->alignment(), "alignments do not match"); 408 409 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) { 410 return false; 411 } 412 413 // Both generations must be completely committed. 414 if (young_gen->virtual_space()->uncommitted_size() != 0) { 415 return false; 416 } 417 if (old_gen->virtual_space()->uncommitted_size() != 0) { 418 return false; 419 } 420 421 // Figure out how much to take from eden. Include the average amount promoted 422 // in the total; otherwise the next young gen GC will simply bail out to a 423 // full GC. 424 const size_t alignment = old_gen->virtual_space()->alignment(); 425 const size_t eden_used = eden_space->used_in_bytes(); 426 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average(); 427 const size_t absorb_size = align_up(eden_used + promoted, alignment); 428 const size_t eden_capacity = eden_space->capacity_in_bytes(); 429 430 if (absorb_size >= eden_capacity) { 431 return false; // Must leave some space in eden. 432 } 433 434 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size; 435 if (new_young_size < young_gen->min_gen_size()) { 436 return false; // Respect young gen minimum size. 437 } 438 439 log_trace(heap, ergo)(" absorbing " SIZE_FORMAT "K: " 440 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K " 441 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K " 442 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ", 443 absorb_size / K, 444 eden_capacity / K, (eden_capacity - absorb_size) / K, 445 young_gen->from_space()->used_in_bytes() / K, 446 young_gen->to_space()->used_in_bytes() / K, 447 young_gen->capacity_in_bytes() / K, new_young_size / K); 448 449 // Fill the unused part of the old gen. 450 MutableSpace* const old_space = old_gen->object_space(); 451 HeapWord* const unused_start = old_space->top(); 452 size_t const unused_words = pointer_delta(old_space->end(), unused_start); 453 454 if (unused_words > 0) { 455 if (unused_words < CollectedHeap::min_fill_size()) { 456 return false; // If the old gen cannot be filled, must give up. 457 } 458 CollectedHeap::fill_with_objects(unused_start, unused_words); 459 } 460 461 // Take the live data from eden and set both top and end in the old gen to 462 // eden top. (Need to set end because reset_after_change() mangles the region 463 // from end to virtual_space->high() in debug builds). 464 HeapWord* const new_top = eden_space->top(); 465 old_gen->virtual_space()->expand_into(young_gen->virtual_space(), 466 absorb_size); 467 young_gen->reset_after_change(); 468 old_space->set_top(new_top); 469 old_space->set_end(new_top); 470 old_gen->reset_after_change(); 471 472 // Update the object start array for the filler object and the data from eden. 473 ObjectStartArray* const start_array = old_gen->start_array(); 474 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) { 475 start_array->allocate_block(p); 476 } 477 478 // Could update the promoted average here, but it is not typically updated at 479 // full GCs and the value to use is unclear. Something like 480 // 481 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc. 482 483 size_policy->set_bytes_absorbed_from_eden(absorb_size); 484 return true; 485 } 486 487 void PSMarkSweep::allocate_stacks() { 488 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 489 PSYoungGen* young_gen = heap->young_gen(); 490 491 MutableSpace* to_space = young_gen->to_space(); 492 _preserved_marks = (PreservedMark*)to_space->top(); 493 _preserved_count = 0; 494 495 // We want to calculate the size in bytes first. 496 _preserved_count_max = pointer_delta(to_space->end(), to_space->top(), sizeof(jbyte)); 497 // Now divide by the size of a PreservedMark 498 _preserved_count_max /= sizeof(PreservedMark); 499 } 500 501 502 void PSMarkSweep::deallocate_stacks() { 503 _preserved_mark_stack.clear(true); 504 _preserved_oop_stack.clear(true); 505 _marking_stack.clear(); 506 _objarray_stack.clear(true); 507 } 508 509 void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) { 510 // Recursively traverse all live objects and mark them 511 GCTraceTime(Info, gc, phases) tm("Phase 1: Mark live objects", _gc_timer); 512 513 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 514 515 // Need to clear claim bits before the tracing starts. 516 ClassLoaderDataGraph::clear_claimed_marks(); 517 518 // General strong roots. 519 { 520 ParallelScavengeHeap::ParStrongRootsScope psrs; 521 Universe::oops_do(mark_and_push_closure()); 522 JNIHandles::oops_do(mark_and_push_closure()); // Global (strong) JNI handles 523 MarkingCodeBlobClosure each_active_code_blob(mark_and_push_closure(), !CodeBlobToOopClosure::FixRelocations); 524 Threads::oops_do(mark_and_push_closure(), &each_active_code_blob); 525 ObjectSynchronizer::oops_do(mark_and_push_closure()); 526 Management::oops_do(mark_and_push_closure()); 527 JvmtiExport::oops_do(mark_and_push_closure()); 528 SystemDictionary::always_strong_oops_do(mark_and_push_closure()); 529 ClassLoaderDataGraph::always_strong_cld_do(follow_cld_closure()); 530 // Do not treat nmethods as strong roots for mark/sweep, since we can unload them. 531 //CodeCache::scavenge_root_nmethods_do(CodeBlobToOopClosure(mark_and_push_closure())); 532 AOTLoader::oops_do(mark_and_push_closure()); 533 } 534 535 // Flush marking stack. 536 follow_stack(); 537 538 // Process reference objects found during marking 539 { 540 GCTraceTime(Debug, gc, phases) t("Reference Processing", _gc_timer); 541 542 ref_processor()->setup_policy(clear_all_softrefs); 543 ReferenceProcessorPhaseTimes pt(_gc_timer, ref_processor()->num_queues()); 544 const ReferenceProcessorStats& stats = 545 ref_processor()->process_discovered_references( 546 is_alive_closure(), mark_and_push_closure(), follow_stack_closure(), NULL, &pt); 547 gc_tracer()->report_gc_reference_stats(stats); 548 pt.print_all_references(); 549 } 550 551 // This is the point where the entire marking should have completed. 552 assert(_marking_stack.is_empty(), "Marking should have completed"); 553 554 { 555 GCTraceTime(Debug, gc, phases) t("Weak Processing", _gc_timer); 556 WeakProcessor::weak_oops_do(is_alive_closure(), &do_nothing_cl); 557 } 558 559 { 560 GCTraceTime(Debug, gc, phases) t("Class Unloading", _gc_timer); 561 562 // Unload classes and purge the SystemDictionary. 563 bool purged_class = SystemDictionary::do_unloading(is_alive_closure(), _gc_timer); 564 565 // Unload nmethods. 566 CodeCache::do_unloading(is_alive_closure(), purged_class); 567 568 // Prune dead klasses from subklass/sibling/implementor lists. 569 Klass::clean_weak_klass_links(purged_class); 570 } 571 572 { 573 GCTraceTime(Debug, gc, phases) t("Scrub String Table", _gc_timer); 574 // Delete entries for dead interned strings. 575 StringTable::unlink(is_alive_closure()); 576 } 577 578 { 579 GCTraceTime(Debug, gc, phases) t("Scrub Symbol Table", _gc_timer); 580 // Clean up unreferenced symbols in symbol table. 581 SymbolTable::unlink(); 582 } 583 584 _gc_tracer->report_object_count_after_gc(is_alive_closure()); 585 } 586 587 588 void PSMarkSweep::mark_sweep_phase2() { 589 GCTraceTime(Info, gc, phases) tm("Phase 2: Compute new object addresses", _gc_timer); 590 591 // Now all live objects are marked, compute the new object addresses. 592 593 // It is not required that we traverse spaces in the same order in 594 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops 595 // tracking expects us to do so. See comment under phase4. 596 597 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 598 PSOldGen* old_gen = heap->old_gen(); 599 600 // Begin compacting into the old gen 601 PSMarkSweepDecorator::set_destination_decorator_tenured(); 602 603 // This will also compact the young gen spaces. 604 old_gen->precompact(); 605 } 606 607 void PSMarkSweep::mark_sweep_phase3() { 608 // Adjust the pointers to reflect the new locations 609 GCTraceTime(Info, gc, phases) tm("Phase 3: Adjust pointers", _gc_timer); 610 611 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 612 PSYoungGen* young_gen = heap->young_gen(); 613 PSOldGen* old_gen = heap->old_gen(); 614 615 // Need to clear claim bits before the tracing starts. 616 ClassLoaderDataGraph::clear_claimed_marks(); 617 618 // General strong roots. 619 Universe::oops_do(adjust_pointer_closure()); 620 JNIHandles::oops_do(adjust_pointer_closure()); // Global (strong) JNI handles 621 Threads::oops_do(adjust_pointer_closure(), NULL); 622 ObjectSynchronizer::oops_do(adjust_pointer_closure()); 623 Management::oops_do(adjust_pointer_closure()); 624 JvmtiExport::oops_do(adjust_pointer_closure()); 625 SystemDictionary::oops_do(adjust_pointer_closure()); 626 ClassLoaderDataGraph::cld_do(adjust_cld_closure()); 627 628 // Now adjust pointers in remaining weak roots. (All of which should 629 // have been cleared if they pointed to non-surviving objects.) 630 // Global (weak) JNI handles 631 WeakProcessor::oops_do(adjust_pointer_closure()); 632 633 CodeBlobToOopClosure adjust_from_blobs(adjust_pointer_closure(), CodeBlobToOopClosure::FixRelocations); 634 CodeCache::blobs_do(&adjust_from_blobs); 635 AOTLoader::oops_do(adjust_pointer_closure()); 636 StringTable::oops_do(adjust_pointer_closure()); 637 ref_processor()->weak_oops_do(adjust_pointer_closure()); 638 PSScavenge::reference_processor()->weak_oops_do(adjust_pointer_closure()); 639 640 adjust_marks(); 641 642 young_gen->adjust_pointers(); 643 old_gen->adjust_pointers(); 644 } 645 646 void PSMarkSweep::mark_sweep_phase4() { 647 EventMark m("4 compact heap"); 648 GCTraceTime(Info, gc, phases) tm("Phase 4: Move objects", _gc_timer); 649 650 // All pointers are now adjusted, move objects accordingly 651 652 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 653 PSYoungGen* young_gen = heap->young_gen(); 654 PSOldGen* old_gen = heap->old_gen(); 655 656 old_gen->compact(); 657 young_gen->compact(); 658 } 659 660 jlong PSMarkSweep::millis_since_last_gc() { 661 // We need a monotonically non-decreasing time in ms but 662 // os::javaTimeMillis() does not guarantee monotonicity. 663 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 664 jlong ret_val = now - _time_of_last_gc; 665 // XXX See note in genCollectedHeap::millis_since_last_gc(). 666 if (ret_val < 0) { 667 NOT_PRODUCT(log_warning(gc)("time warp: " JLONG_FORMAT, ret_val);) 668 return 0; 669 } 670 return ret_val; 671 } 672 673 void PSMarkSweep::reset_millis_since_last_gc() { 674 // We need a monotonically non-decreasing time in ms but 675 // os::javaTimeMillis() does not guarantee monotonicity. 676 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 677 }