1 /* 2 * Copyright (c) 2001, 2017, 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.inline.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/safepoint.hpp" 55 #include "runtime/vmThread.hpp" 56 #include "services/management.hpp" 57 #include "services/memoryService.hpp" 58 #include "utilities/align.hpp" 59 #include "utilities/events.hpp" 60 #include "utilities/stack.inline.hpp" 61 62 elapsedTimer PSMarkSweep::_accumulated_time; 63 jlong PSMarkSweep::_time_of_last_gc = 0; 64 CollectorCounters* PSMarkSweep::_counters = NULL; 65 66 void PSMarkSweep::initialize() { 67 MemRegion mr = ParallelScavengeHeap::heap()->reserved_region(); 68 set_ref_processor(new ReferenceProcessor(mr)); // a vanilla ref proc 69 _counters = new CollectorCounters("PSMarkSweep", 1); 70 } 71 72 // This method contains all heap specific policy for invoking mark sweep. 73 // PSMarkSweep::invoke_no_policy() will only attempt to mark-sweep-compact 74 // the heap. It will do nothing further. If we need to bail out for policy 75 // reasons, scavenge before full gc, or any other specialized behavior, it 76 // needs to be added here. 77 // 78 // Note that this method should only be called from the vm_thread while 79 // at a safepoint! 80 // 81 // Note that the all_soft_refs_clear flag in the collector policy 82 // may be true because this method can be called without intervening 83 // activity. For example when the heap space is tight and full measure 84 // are being taken to free space. 85 86 void PSMarkSweep::invoke(bool maximum_heap_compaction) { 87 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 88 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread"); 89 assert(!ParallelScavengeHeap::heap()->is_gc_active(), "not reentrant"); 90 91 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 92 GCCause::Cause gc_cause = heap->gc_cause(); 93 PSAdaptiveSizePolicy* policy = heap->size_policy(); 94 IsGCActiveMark mark; 95 96 if (ScavengeBeforeFullGC) { 97 PSScavenge::invoke_no_policy(); 98 } 99 100 const bool clear_all_soft_refs = 101 heap->collector_policy()->should_clear_all_soft_refs(); 102 103 uint count = maximum_heap_compaction ? 1 : MarkSweepAlwaysCompactCount; 104 UIntFlagSetting flag_setting(MarkSweepAlwaysCompactCount, count); 105 PSMarkSweep::invoke_no_policy(clear_all_soft_refs || maximum_heap_compaction); 106 } 107 108 // This method contains no policy. You should probably 109 // be calling invoke() instead. 110 bool PSMarkSweep::invoke_no_policy(bool clear_all_softrefs) { 111 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint"); 112 assert(ref_processor() != NULL, "Sanity"); 113 114 if (GCLocker::check_active_before_gc()) { 115 return false; 116 } 117 118 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 119 GCCause::Cause gc_cause = heap->gc_cause(); 120 121 GCIdMark gc_id_mark; 122 _gc_timer->register_gc_start(); 123 _gc_tracer->report_gc_start(gc_cause, _gc_timer->gc_start()); 124 125 PSAdaptiveSizePolicy* size_policy = heap->size_policy(); 126 127 // The scope of casr should end after code that can change 128 // CollectorPolicy::_should_clear_all_soft_refs. 129 ClearedAllSoftRefs casr(clear_all_softrefs, heap->collector_policy()); 130 131 PSYoungGen* young_gen = heap->young_gen(); 132 PSOldGen* old_gen = heap->old_gen(); 133 134 // Increment the invocation count 135 heap->increment_total_collections(true /* full */); 136 137 // Save information needed to minimize mangling 138 heap->record_gen_tops_before_GC(); 139 140 // We need to track unique mark sweep invocations as well. 141 _total_invocations++; 142 143 heap->print_heap_before_gc(); 144 heap->trace_heap_before_gc(_gc_tracer); 145 146 // Fill in TLABs 147 heap->accumulate_statistics_all_tlabs(); 148 heap->ensure_parsability(true); // retire TLABs 149 150 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) { 151 HandleMark hm; // Discard invalid handles created during verification 152 Universe::verify("Before GC"); 153 } 154 155 // Verify object start arrays 156 if (VerifyObjectStartArray && 157 VerifyBeforeGC) { 158 old_gen->verify_object_start_array(); 159 } 160 161 // Filled in below to track the state of the young gen after the collection. 162 bool eden_empty; 163 bool survivors_empty; 164 bool young_gen_empty; 165 166 { 167 HandleMark hm; 168 169 GCTraceCPUTime tcpu; 170 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause, true); 171 172 heap->pre_full_gc_dump(_gc_timer); 173 174 TraceCollectorStats tcs(counters()); 175 TraceMemoryManagerStats tms(true /* Full GC */,gc_cause); 176 177 if (log_is_enabled(Debug, gc, heap, exit)) { 178 accumulated_time()->start(); 179 } 180 181 // Let the size policy know we're starting 182 size_policy->major_collection_begin(); 183 184 CodeCache::gc_prologue(); 185 BiasedLocking::preserve_marks(); 186 187 // Capture metadata size before collection for sizing. 188 size_t metadata_prev_used = MetaspaceAux::used_bytes(); 189 190 size_t old_gen_prev_used = old_gen->used_in_bytes(); 191 size_t young_gen_prev_used = young_gen->used_in_bytes(); 192 193 allocate_stacks(); 194 195 #if defined(COMPILER2) || INCLUDE_JVMCI 196 DerivedPointerTable::clear(); 197 #endif 198 199 ref_processor()->enable_discovery(); 200 ref_processor()->setup_policy(clear_all_softrefs); 201 202 mark_sweep_phase1(clear_all_softrefs); 203 204 mark_sweep_phase2(); 205 206 #if defined(COMPILER2) || INCLUDE_JVMCI 207 // Don't add any more derived pointers during phase3 208 assert(DerivedPointerTable::is_active(), "Sanity"); 209 DerivedPointerTable::set_active(false); 210 #endif 211 212 mark_sweep_phase3(); 213 214 mark_sweep_phase4(); 215 216 restore_marks(); 217 218 deallocate_stacks(); 219 220 if (ZapUnusedHeapArea) { 221 // Do a complete mangle (top to end) because the usage for 222 // scratch does not maintain a top pointer. 223 young_gen->to_space()->mangle_unused_area_complete(); 224 } 225 226 eden_empty = young_gen->eden_space()->is_empty(); 227 if (!eden_empty) { 228 eden_empty = absorb_live_data_from_eden(size_policy, young_gen, old_gen); 229 } 230 231 // Update heap occupancy information which is used as 232 // input to soft ref clearing policy at the next gc. 233 Universe::update_heap_info_at_gc(); 234 235 survivors_empty = young_gen->from_space()->is_empty() && 236 young_gen->to_space()->is_empty(); 237 young_gen_empty = eden_empty && survivors_empty; 238 239 ModRefBarrierSet* modBS = barrier_set_cast<ModRefBarrierSet>(heap->barrier_set()); 240 MemRegion old_mr = heap->old_gen()->reserved(); 241 if (young_gen_empty) { 242 modBS->clear(MemRegion(old_mr.start(), old_mr.end())); 243 } else { 244 modBS->invalidate(MemRegion(old_mr.start(), old_mr.end())); 245 } 246 247 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 248 ClassLoaderDataGraph::purge(); 249 MetaspaceAux::verify_metrics(); 250 251 BiasedLocking::restore_marks(); 252 CodeCache::gc_epilogue(); 253 JvmtiExport::gc_epilogue(); 254 255 #if defined(COMPILER2) || INCLUDE_JVMCI 256 DerivedPointerTable::update_pointers(); 257 #endif 258 259 ReferenceProcessorPhaseTimes pt(_gc_timer, ref_processor()->num_q()); 260 261 ref_processor()->enqueue_discovered_references(NULL, &pt); 262 263 pt.print_enqueue_phase(); 264 265 // Update time of last GC 266 reset_millis_since_last_gc(); 267 268 // Let the size policy know we're done 269 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause); 270 271 if (UseAdaptiveSizePolicy) { 272 273 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections()); 274 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT, 275 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes()); 276 277 // Don't check if the size_policy is ready here. Let 278 // the size_policy check that internally. 279 if (UseAdaptiveGenerationSizePolicyAtMajorCollection && 280 AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) { 281 // Swap the survivor spaces if from_space is empty. The 282 // resize_young_gen() called below is normally used after 283 // a successful young GC and swapping of survivor spaces; 284 // otherwise, it will fail to resize the young gen with 285 // the current implementation. 286 if (young_gen->from_space()->is_empty()) { 287 young_gen->from_space()->clear(SpaceDecorator::Mangle); 288 young_gen->swap_spaces(); 289 } 290 291 // Calculate optimal free space amounts 292 assert(young_gen->max_size() > 293 young_gen->from_space()->capacity_in_bytes() + 294 young_gen->to_space()->capacity_in_bytes(), 295 "Sizes of space in young gen are out-of-bounds"); 296 297 size_t young_live = young_gen->used_in_bytes(); 298 size_t eden_live = young_gen->eden_space()->used_in_bytes(); 299 size_t old_live = old_gen->used_in_bytes(); 300 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes(); 301 size_t max_old_gen_size = old_gen->max_gen_size(); 302 size_t max_eden_size = young_gen->max_size() - 303 young_gen->from_space()->capacity_in_bytes() - 304 young_gen->to_space()->capacity_in_bytes(); 305 306 // Used for diagnostics 307 size_policy->clear_generation_free_space_flags(); 308 309 size_policy->compute_generations_free_space(young_live, 310 eden_live, 311 old_live, 312 cur_eden, 313 max_old_gen_size, 314 max_eden_size, 315 true /* full gc*/); 316 317 size_policy->check_gc_overhead_limit(young_live, 318 eden_live, 319 max_old_gen_size, 320 max_eden_size, 321 true /* full gc*/, 322 gc_cause, 323 heap->collector_policy()); 324 325 size_policy->decay_supplemental_growth(true /* full gc*/); 326 327 heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes()); 328 329 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(), 330 size_policy->calculated_survivor_size_in_bytes()); 331 } 332 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections()); 333 } 334 335 if (UsePerfData) { 336 heap->gc_policy_counters()->update_counters(); 337 heap->gc_policy_counters()->update_old_capacity( 338 old_gen->capacity_in_bytes()); 339 heap->gc_policy_counters()->update_young_capacity( 340 young_gen->capacity_in_bytes()); 341 } 342 343 heap->resize_all_tlabs(); 344 345 // We collected the heap, recalculate the metaspace capacity 346 MetaspaceGC::compute_new_size(); 347 348 if (log_is_enabled(Debug, gc, heap, exit)) { 349 accumulated_time()->stop(); 350 } 351 352 young_gen->print_used_change(young_gen_prev_used); 353 old_gen->print_used_change(old_gen_prev_used); 354 MetaspaceAux::print_metaspace_change(metadata_prev_used); 355 356 // Track memory usage and detect low memory 357 MemoryService::track_memory_usage(); 358 heap->update_counters(); 359 360 heap->post_full_gc_dump(_gc_timer); 361 } 362 363 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) { 364 HandleMark hm; // Discard invalid handles created during verification 365 Universe::verify("After GC"); 366 } 367 368 // Re-verify object start arrays 369 if (VerifyObjectStartArray && 370 VerifyAfterGC) { 371 old_gen->verify_object_start_array(); 372 } 373 374 if (ZapUnusedHeapArea) { 375 old_gen->object_space()->check_mangled_unused_area_complete(); 376 } 377 378 NOT_PRODUCT(ref_processor()->verify_no_references_recorded()); 379 380 heap->print_heap_after_gc(); 381 heap->trace_heap_after_gc(_gc_tracer); 382 383 #ifdef TRACESPINNING 384 ParallelTaskTerminator::print_termination_counts(); 385 #endif 386 387 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections()); 388 389 _gc_timer->register_gc_end(); 390 391 _gc_tracer->report_gc_end(_gc_timer->gc_end(), _gc_timer->time_partitions()); 392 393 return true; 394 } 395 396 bool PSMarkSweep::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy, 397 PSYoungGen* young_gen, 398 PSOldGen* old_gen) { 399 MutableSpace* const eden_space = young_gen->eden_space(); 400 assert(!eden_space->is_empty(), "eden must be non-empty"); 401 assert(young_gen->virtual_space()->alignment() == 402 old_gen->virtual_space()->alignment(), "alignments do not match"); 403 404 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) { 405 return false; 406 } 407 408 // Both generations must be completely committed. 409 if (young_gen->virtual_space()->uncommitted_size() != 0) { 410 return false; 411 } 412 if (old_gen->virtual_space()->uncommitted_size() != 0) { 413 return false; 414 } 415 416 // Figure out how much to take from eden. Include the average amount promoted 417 // in the total; otherwise the next young gen GC will simply bail out to a 418 // full GC. 419 const size_t alignment = old_gen->virtual_space()->alignment(); 420 const size_t eden_used = eden_space->used_in_bytes(); 421 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average(); 422 const size_t absorb_size = align_up(eden_used + promoted, alignment); 423 const size_t eden_capacity = eden_space->capacity_in_bytes(); 424 425 if (absorb_size >= eden_capacity) { 426 return false; // Must leave some space in eden. 427 } 428 429 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size; 430 if (new_young_size < young_gen->min_gen_size()) { 431 return false; // Respect young gen minimum size. 432 } 433 434 log_trace(heap, ergo)(" absorbing " SIZE_FORMAT "K: " 435 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K " 436 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K " 437 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ", 438 absorb_size / K, 439 eden_capacity / K, (eden_capacity - absorb_size) / K, 440 young_gen->from_space()->used_in_bytes() / K, 441 young_gen->to_space()->used_in_bytes() / K, 442 young_gen->capacity_in_bytes() / K, new_young_size / K); 443 444 // Fill the unused part of the old gen. 445 MutableSpace* const old_space = old_gen->object_space(); 446 HeapWord* const unused_start = old_space->top(); 447 size_t const unused_words = pointer_delta(old_space->end(), unused_start); 448 449 if (unused_words > 0) { 450 if (unused_words < CollectedHeap::min_fill_size()) { 451 return false; // If the old gen cannot be filled, must give up. 452 } 453 CollectedHeap::fill_with_objects(unused_start, unused_words); 454 } 455 456 // Take the live data from eden and set both top and end in the old gen to 457 // eden top. (Need to set end because reset_after_change() mangles the region 458 // from end to virtual_space->high() in debug builds). 459 HeapWord* const new_top = eden_space->top(); 460 old_gen->virtual_space()->expand_into(young_gen->virtual_space(), 461 absorb_size); 462 young_gen->reset_after_change(); 463 old_space->set_top(new_top); 464 old_space->set_end(new_top); 465 old_gen->reset_after_change(); 466 467 // Update the object start array for the filler object and the data from eden. 468 ObjectStartArray* const start_array = old_gen->start_array(); 469 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) { 470 start_array->allocate_block(p); 471 } 472 473 // Could update the promoted average here, but it is not typically updated at 474 // full GCs and the value to use is unclear. Something like 475 // 476 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc. 477 478 size_policy->set_bytes_absorbed_from_eden(absorb_size); 479 return true; 480 } 481 482 void PSMarkSweep::allocate_stacks() { 483 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 484 PSYoungGen* young_gen = heap->young_gen(); 485 486 MutableSpace* to_space = young_gen->to_space(); 487 _preserved_marks = (PreservedMark*)to_space->top(); 488 _preserved_count = 0; 489 490 // We want to calculate the size in bytes first. 491 _preserved_count_max = pointer_delta(to_space->end(), to_space->top(), sizeof(jbyte)); 492 // Now divide by the size of a PreservedMark 493 _preserved_count_max /= sizeof(PreservedMark); 494 } 495 496 497 void PSMarkSweep::deallocate_stacks() { 498 _preserved_mark_stack.clear(true); 499 _preserved_oop_stack.clear(true); 500 _marking_stack.clear(); 501 _objarray_stack.clear(true); 502 } 503 504 void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) { 505 // Recursively traverse all live objects and mark them 506 GCTraceTime(Info, gc, phases) tm("Phase 1: Mark live objects", _gc_timer); 507 508 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 509 510 // Need to clear claim bits before the tracing starts. 511 ClassLoaderDataGraph::clear_claimed_marks(); 512 513 // General strong roots. 514 { 515 ParallelScavengeHeap::ParStrongRootsScope psrs; 516 Universe::oops_do(mark_and_push_closure()); 517 JNIHandles::oops_do(mark_and_push_closure()); // Global (strong) JNI handles 518 MarkingCodeBlobClosure each_active_code_blob(mark_and_push_closure(), !CodeBlobToOopClosure::FixRelocations); 519 Threads::oops_do(mark_and_push_closure(), &each_active_code_blob); 520 ObjectSynchronizer::oops_do(mark_and_push_closure()); 521 Management::oops_do(mark_and_push_closure()); 522 JvmtiExport::oops_do(mark_and_push_closure()); 523 SystemDictionary::always_strong_oops_do(mark_and_push_closure()); 524 ClassLoaderDataGraph::always_strong_cld_do(follow_cld_closure()); 525 // Do not treat nmethods as strong roots for mark/sweep, since we can unload them. 526 //CodeCache::scavenge_root_nmethods_do(CodeBlobToOopClosure(mark_and_push_closure())); 527 AOTLoader::oops_do(mark_and_push_closure()); 528 } 529 530 // Flush marking stack. 531 follow_stack(); 532 533 // Process reference objects found during marking 534 { 535 GCTraceTime(Debug, gc, phases) t("Reference Processing", _gc_timer); 536 537 ref_processor()->setup_policy(clear_all_softrefs); 538 ReferenceProcessorPhaseTimes pt(_gc_timer, ref_processor()->num_q()); 539 const ReferenceProcessorStats& stats = 540 ref_processor()->process_discovered_references( 541 is_alive_closure(), mark_and_push_closure(), follow_stack_closure(), NULL, &pt); 542 gc_tracer()->report_gc_reference_stats(stats); 543 pt.print_all_references(); 544 } 545 546 // This is the point where the entire marking should have completed. 547 assert(_marking_stack.is_empty(), "Marking should have completed"); 548 549 { 550 GCTraceTime(Debug, gc, phases) t("Weak Processing", _gc_timer); 551 WeakProcessor::weak_oops_do(is_alive_closure(), &do_nothing_cl); 552 } 553 554 { 555 GCTraceTime(Debug, gc, phases) t("Class Unloading", _gc_timer); 556 557 // Unload classes and purge the SystemDictionary. 558 bool purged_class = SystemDictionary::do_unloading(is_alive_closure(), _gc_timer); 559 560 // Unload nmethods. 561 CodeCache::do_unloading(is_alive_closure(), purged_class); 562 563 // Prune dead klasses from subklass/sibling/implementor lists. 564 Klass::clean_weak_klass_links(is_alive_closure()); 565 } 566 567 { 568 GCTraceTime(Debug, gc, phases) t("Scrub String Table", _gc_timer); 569 // Delete entries for dead interned strings. 570 StringTable::unlink(is_alive_closure()); 571 } 572 573 { 574 GCTraceTime(Debug, gc, phases) t("Scrub Symbol Table", _gc_timer); 575 // Clean up unreferenced symbols in symbol table. 576 SymbolTable::unlink(); 577 } 578 579 _gc_tracer->report_object_count_after_gc(is_alive_closure()); 580 } 581 582 583 void PSMarkSweep::mark_sweep_phase2() { 584 GCTraceTime(Info, gc, phases) tm("Phase 2: Compute new object addresses", _gc_timer); 585 586 // Now all live objects are marked, compute the new object addresses. 587 588 // It is not required that we traverse spaces in the same order in 589 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops 590 // tracking expects us to do so. See comment under phase4. 591 592 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 593 PSOldGen* old_gen = heap->old_gen(); 594 595 // Begin compacting into the old gen 596 PSMarkSweepDecorator::set_destination_decorator_tenured(); 597 598 // This will also compact the young gen spaces. 599 old_gen->precompact(); 600 } 601 602 void PSMarkSweep::mark_sweep_phase3() { 603 // Adjust the pointers to reflect the new locations 604 GCTraceTime(Info, gc, phases) tm("Phase 3: Adjust pointers", _gc_timer); 605 606 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 607 PSYoungGen* young_gen = heap->young_gen(); 608 PSOldGen* old_gen = heap->old_gen(); 609 610 // Need to clear claim bits before the tracing starts. 611 ClassLoaderDataGraph::clear_claimed_marks(); 612 613 // General strong roots. 614 Universe::oops_do(adjust_pointer_closure()); 615 JNIHandles::oops_do(adjust_pointer_closure()); // Global (strong) JNI handles 616 Threads::oops_do(adjust_pointer_closure(), NULL); 617 ObjectSynchronizer::oops_do(adjust_pointer_closure()); 618 Management::oops_do(adjust_pointer_closure()); 619 JvmtiExport::oops_do(adjust_pointer_closure()); 620 SystemDictionary::oops_do(adjust_pointer_closure()); 621 ClassLoaderDataGraph::cld_do(adjust_cld_closure()); 622 623 // Now adjust pointers in remaining weak roots. (All of which should 624 // have been cleared if they pointed to non-surviving objects.) 625 // Global (weak) JNI handles 626 WeakProcessor::oops_do(adjust_pointer_closure()); 627 628 CodeBlobToOopClosure adjust_from_blobs(adjust_pointer_closure(), CodeBlobToOopClosure::FixRelocations); 629 CodeCache::blobs_do(&adjust_from_blobs); 630 AOTLoader::oops_do(adjust_pointer_closure()); 631 StringTable::oops_do(adjust_pointer_closure()); 632 ref_processor()->weak_oops_do(adjust_pointer_closure()); 633 PSScavenge::reference_processor()->weak_oops_do(adjust_pointer_closure()); 634 635 adjust_marks(); 636 637 young_gen->adjust_pointers(); 638 old_gen->adjust_pointers(); 639 } 640 641 void PSMarkSweep::mark_sweep_phase4() { 642 EventMark m("4 compact heap"); 643 GCTraceTime(Info, gc, phases) tm("Phase 4: Move objects", _gc_timer); 644 645 // All pointers are now adjusted, move objects accordingly 646 647 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 648 PSYoungGen* young_gen = heap->young_gen(); 649 PSOldGen* old_gen = heap->old_gen(); 650 651 old_gen->compact(); 652 young_gen->compact(); 653 } 654 655 jlong PSMarkSweep::millis_since_last_gc() { 656 // We need a monotonically non-decreasing time in ms but 657 // os::javaTimeMillis() does not guarantee monotonicity. 658 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 659 jlong ret_val = now - _time_of_last_gc; 660 // XXX See note in genCollectedHeap::millis_since_last_gc(). 661 if (ret_val < 0) { 662 NOT_PRODUCT(log_warning(gc)("time warp: " JLONG_FORMAT, ret_val);) 663 return 0; 664 } 665 return ret_val; 666 } 667 668 void PSMarkSweep::reset_millis_since_last_gc() { 669 // We need a monotonically non-decreasing time in ms but 670 // os::javaTimeMillis() does not guarantee monotonicity. 671 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 672 }