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