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