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