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 "logging/log.hpp" 51 #include "oops/oop.inline.hpp" 52 #include "runtime/biasedLocking.hpp" 53 #include "runtime/fprofiler.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 (TraceOldGenTime) accumulated_time()->start(); 178 179 // Let the size policy know we're starting 180 size_policy->major_collection_begin(); 181 182 CodeCache::gc_prologue(); 183 BiasedLocking::preserve_marks(); 184 185 // Capture metadata size before collection for sizing. 186 size_t metadata_prev_used = MetaspaceAux::used_bytes(); 187 188 size_t old_gen_prev_used = old_gen->used_in_bytes(); 189 size_t young_gen_prev_used = young_gen->used_in_bytes(); 190 191 allocate_stacks(); 192 193 #if defined(COMPILER2) || INCLUDE_JVMCI 194 DerivedPointerTable::clear(); 195 #endif 196 197 ref_processor()->enable_discovery(); 198 ref_processor()->setup_policy(clear_all_softrefs); 199 200 mark_sweep_phase1(clear_all_softrefs); 201 202 mark_sweep_phase2(); 203 204 #if defined(COMPILER2) || INCLUDE_JVMCI 205 // Don't add any more derived pointers during phase3 206 assert(DerivedPointerTable::is_active(), "Sanity"); 207 DerivedPointerTable::set_active(false); 208 #endif 209 210 mark_sweep_phase3(); 211 212 mark_sweep_phase4(); 213 214 restore_marks(); 215 216 deallocate_stacks(); 217 218 if (ZapUnusedHeapArea) { 219 // Do a complete mangle (top to end) because the usage for 220 // scratch does not maintain a top pointer. 221 young_gen->to_space()->mangle_unused_area_complete(); 222 } 223 224 eden_empty = young_gen->eden_space()->is_empty(); 225 if (!eden_empty) { 226 eden_empty = absorb_live_data_from_eden(size_policy, young_gen, old_gen); 227 } 228 229 // Update heap occupancy information which is used as 230 // input to soft ref clearing policy at the next gc. 231 Universe::update_heap_info_at_gc(); 232 233 survivors_empty = young_gen->from_space()->is_empty() && 234 young_gen->to_space()->is_empty(); 235 young_gen_empty = eden_empty && survivors_empty; 236 237 ModRefBarrierSet* modBS = barrier_set_cast<ModRefBarrierSet>(heap->barrier_set()); 238 MemRegion old_mr = heap->old_gen()->reserved(); 239 if (young_gen_empty) { 240 modBS->clear(MemRegion(old_mr.start(), old_mr.end())); 241 } else { 242 modBS->invalidate(MemRegion(old_mr.start(), old_mr.end())); 243 } 244 245 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 246 ClassLoaderDataGraph::purge(); 247 MetaspaceAux::verify_metrics(); 248 249 BiasedLocking::restore_marks(); 250 CodeCache::gc_epilogue(); 251 JvmtiExport::gc_epilogue(); 252 253 #if defined(COMPILER2) || INCLUDE_JVMCI 254 DerivedPointerTable::update_pointers(); 255 #endif 256 257 ref_processor()->enqueue_discovered_references(NULL); 258 259 // Update time of last GC 260 reset_millis_since_last_gc(); 261 262 // Let the size policy know we're done 263 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause); 264 265 if (UseAdaptiveSizePolicy) { 266 267 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections()); 268 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT, 269 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes()); 270 271 // Don't check if the size_policy is ready here. Let 272 // the size_policy check that internally. 273 if (UseAdaptiveGenerationSizePolicyAtMajorCollection && 274 AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) { 275 // Swap the survivor spaces if from_space is empty. The 276 // resize_young_gen() called below is normally used after 277 // a successful young GC and swapping of survivor spaces; 278 // otherwise, it will fail to resize the young gen with 279 // the current implementation. 280 if (young_gen->from_space()->is_empty()) { 281 young_gen->from_space()->clear(SpaceDecorator::Mangle); 282 young_gen->swap_spaces(); 283 } 284 285 // Calculate optimal free space amounts 286 assert(young_gen->max_size() > 287 young_gen->from_space()->capacity_in_bytes() + 288 young_gen->to_space()->capacity_in_bytes(), 289 "Sizes of space in young gen are out-of-bounds"); 290 291 size_t young_live = young_gen->used_in_bytes(); 292 size_t eden_live = young_gen->eden_space()->used_in_bytes(); 293 size_t old_live = old_gen->used_in_bytes(); 294 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes(); 295 size_t max_old_gen_size = old_gen->max_gen_size(); 296 size_t max_eden_size = young_gen->max_size() - 297 young_gen->from_space()->capacity_in_bytes() - 298 young_gen->to_space()->capacity_in_bytes(); 299 300 // Used for diagnostics 301 size_policy->clear_generation_free_space_flags(); 302 303 size_policy->compute_generations_free_space(young_live, 304 eden_live, 305 old_live, 306 cur_eden, 307 max_old_gen_size, 308 max_eden_size, 309 true /* full gc*/); 310 311 size_policy->check_gc_overhead_limit(young_live, 312 eden_live, 313 max_old_gen_size, 314 max_eden_size, 315 true /* full gc*/, 316 gc_cause, 317 heap->collector_policy()); 318 319 size_policy->decay_supplemental_growth(true /* full gc*/); 320 321 heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes()); 322 323 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(), 324 size_policy->calculated_survivor_size_in_bytes()); 325 } 326 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections()); 327 } 328 329 if (UsePerfData) { 330 heap->gc_policy_counters()->update_counters(); 331 heap->gc_policy_counters()->update_old_capacity( 332 old_gen->capacity_in_bytes()); 333 heap->gc_policy_counters()->update_young_capacity( 334 young_gen->capacity_in_bytes()); 335 } 336 337 heap->resize_all_tlabs(); 338 339 // We collected the heap, recalculate the metaspace capacity 340 MetaspaceGC::compute_new_size(); 341 342 if (TraceOldGenTime) accumulated_time()->stop(); 343 344 young_gen->print_used_change(young_gen_prev_used); 345 old_gen->print_used_change(old_gen_prev_used); 346 MetaspaceAux::print_metaspace_change(metadata_prev_used); 347 348 // Track memory usage and detect low memory 349 MemoryService::track_memory_usage(); 350 heap->update_counters(); 351 352 heap->post_full_gc_dump(_gc_timer); 353 } 354 355 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) { 356 HandleMark hm; // Discard invalid handles created during verification 357 Universe::verify("After GC"); 358 } 359 360 // Re-verify object start arrays 361 if (VerifyObjectStartArray && 362 VerifyAfterGC) { 363 old_gen->verify_object_start_array(); 364 } 365 366 if (ZapUnusedHeapArea) { 367 old_gen->object_space()->check_mangled_unused_area_complete(); 368 } 369 370 NOT_PRODUCT(ref_processor()->verify_no_references_recorded()); 371 372 heap->print_heap_after_gc(); 373 heap->trace_heap_after_gc(_gc_tracer); 374 375 #ifdef TRACESPINNING 376 ParallelTaskTerminator::print_termination_counts(); 377 #endif 378 379 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections()); 380 381 _gc_timer->register_gc_end(); 382 383 _gc_tracer->report_gc_end(_gc_timer->gc_end(), _gc_timer->time_partitions()); 384 385 return true; 386 } 387 388 bool PSMarkSweep::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy, 389 PSYoungGen* young_gen, 390 PSOldGen* old_gen) { 391 MutableSpace* const eden_space = young_gen->eden_space(); 392 assert(!eden_space->is_empty(), "eden must be non-empty"); 393 assert(young_gen->virtual_space()->alignment() == 394 old_gen->virtual_space()->alignment(), "alignments do not match"); 395 396 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) { 397 return false; 398 } 399 400 // Both generations must be completely committed. 401 if (young_gen->virtual_space()->uncommitted_size() != 0) { 402 return false; 403 } 404 if (old_gen->virtual_space()->uncommitted_size() != 0) { 405 return false; 406 } 407 408 // Figure out how much to take from eden. Include the average amount promoted 409 // in the total; otherwise the next young gen GC will simply bail out to a 410 // full GC. 411 const size_t alignment = old_gen->virtual_space()->alignment(); 412 const size_t eden_used = eden_space->used_in_bytes(); 413 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average(); 414 const size_t absorb_size = align_up(eden_used + promoted, alignment); 415 const size_t eden_capacity = eden_space->capacity_in_bytes(); 416 417 if (absorb_size >= eden_capacity) { 418 return false; // Must leave some space in eden. 419 } 420 421 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size; 422 if (new_young_size < young_gen->min_gen_size()) { 423 return false; // Respect young gen minimum size. 424 } 425 426 log_trace(heap, ergo)(" absorbing " SIZE_FORMAT "K: " 427 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K " 428 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K " 429 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ", 430 absorb_size / K, 431 eden_capacity / K, (eden_capacity - absorb_size) / K, 432 young_gen->from_space()->used_in_bytes() / K, 433 young_gen->to_space()->used_in_bytes() / K, 434 young_gen->capacity_in_bytes() / K, new_young_size / K); 435 436 // Fill the unused part of the old gen. 437 MutableSpace* const old_space = old_gen->object_space(); 438 HeapWord* const unused_start = old_space->top(); 439 size_t const unused_words = pointer_delta(old_space->end(), unused_start); 440 441 if (unused_words > 0) { 442 if (unused_words < CollectedHeap::min_fill_size()) { 443 return false; // If the old gen cannot be filled, must give up. 444 } 445 CollectedHeap::fill_with_objects(unused_start, unused_words); 446 } 447 448 // Take the live data from eden and set both top and end in the old gen to 449 // eden top. (Need to set end because reset_after_change() mangles the region 450 // from end to virtual_space->high() in debug builds). 451 HeapWord* const new_top = eden_space->top(); 452 old_gen->virtual_space()->expand_into(young_gen->virtual_space(), 453 absorb_size); 454 young_gen->reset_after_change(); 455 old_space->set_top(new_top); 456 old_space->set_end(new_top); 457 old_gen->reset_after_change(); 458 459 // Update the object start array for the filler object and the data from eden. 460 ObjectStartArray* const start_array = old_gen->start_array(); 461 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) { 462 start_array->allocate_block(p); 463 } 464 465 // Could update the promoted average here, but it is not typically updated at 466 // full GCs and the value to use is unclear. Something like 467 // 468 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc. 469 470 size_policy->set_bytes_absorbed_from_eden(absorb_size); 471 return true; 472 } 473 474 void PSMarkSweep::allocate_stacks() { 475 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 476 PSYoungGen* young_gen = heap->young_gen(); 477 478 MutableSpace* to_space = young_gen->to_space(); 479 _preserved_marks = (PreservedMark*)to_space->top(); 480 _preserved_count = 0; 481 482 // We want to calculate the size in bytes first. 483 _preserved_count_max = pointer_delta(to_space->end(), to_space->top(), sizeof(jbyte)); 484 // Now divide by the size of a PreservedMark 485 _preserved_count_max /= sizeof(PreservedMark); 486 } 487 488 489 void PSMarkSweep::deallocate_stacks() { 490 _preserved_mark_stack.clear(true); 491 _preserved_oop_stack.clear(true); 492 _marking_stack.clear(); 493 _objarray_stack.clear(true); 494 } 495 496 void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) { 497 // Recursively traverse all live objects and mark them 498 GCTraceTime(Info, gc, phases) tm("Phase 1: Mark live objects", _gc_timer); 499 500 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 501 502 // Need to clear claim bits before the tracing starts. 503 ClassLoaderDataGraph::clear_claimed_marks(); 504 505 // General strong roots. 506 { 507 ParallelScavengeHeap::ParStrongRootsScope psrs; 508 Universe::oops_do(mark_and_push_closure()); 509 JNIHandles::oops_do(mark_and_push_closure()); // Global (strong) JNI handles 510 MarkingCodeBlobClosure each_active_code_blob(mark_and_push_closure(), !CodeBlobToOopClosure::FixRelocations); 511 Threads::oops_do(mark_and_push_closure(), &each_active_code_blob); 512 ObjectSynchronizer::oops_do(mark_and_push_closure()); 513 FlatProfiler::oops_do(mark_and_push_closure()); 514 Management::oops_do(mark_and_push_closure()); 515 JvmtiExport::oops_do(mark_and_push_closure()); 516 SystemDictionary::always_strong_oops_do(mark_and_push_closure()); 517 ClassLoaderDataGraph::always_strong_cld_do(follow_cld_closure()); 518 // Do not treat nmethods as strong roots for mark/sweep, since we can unload them. 519 //CodeCache::scavenge_root_nmethods_do(CodeBlobToOopClosure(mark_and_push_closure())); 520 AOTLoader::oops_do(mark_and_push_closure()); 521 } 522 523 // Flush marking stack. 524 follow_stack(); 525 526 // Process reference objects found during marking 527 { 528 GCTraceTime(Debug, gc, phases) t("Reference Processing", _gc_timer); 529 530 ref_processor()->setup_policy(clear_all_softrefs); 531 const ReferenceProcessorStats& stats = 532 ref_processor()->process_discovered_references( 533 is_alive_closure(), mark_and_push_closure(), follow_stack_closure(), NULL, _gc_timer); 534 gc_tracer()->report_gc_reference_stats(stats); 535 } 536 537 // This is the point where the entire marking should have completed. 538 assert(_marking_stack.is_empty(), "Marking should have completed"); 539 540 { 541 GCTraceTime(Debug, gc, phases) t("Class Unloading", _gc_timer); 542 543 // Unload classes and purge the SystemDictionary. 544 bool purged_class = SystemDictionary::do_unloading(is_alive_closure(), _gc_timer); 545 546 // Unload nmethods. 547 CodeCache::do_unloading(is_alive_closure(), purged_class); 548 549 // Prune dead klasses from subklass/sibling/implementor lists. 550 Klass::clean_weak_klass_links(is_alive_closure()); 551 } 552 553 { 554 GCTraceTime(Debug, gc, phases) t("Scrub String Table", _gc_timer); 555 // Delete entries for dead interned strings. 556 StringTable::unlink(is_alive_closure()); 557 } 558 559 { 560 GCTraceTime(Debug, gc, phases) t("Scrub Symbol Table", _gc_timer); 561 // Clean up unreferenced symbols in symbol table. 562 SymbolTable::unlink(); 563 } 564 565 _gc_tracer->report_object_count_after_gc(is_alive_closure()); 566 } 567 568 569 void PSMarkSweep::mark_sweep_phase2() { 570 GCTraceTime(Info, gc, phases) tm("Phase 2: Compute new object addresses", _gc_timer); 571 572 // Now all live objects are marked, compute the new object addresses. 573 574 // It is not required that we traverse spaces in the same order in 575 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops 576 // tracking expects us to do so. See comment under phase4. 577 578 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 579 PSOldGen* old_gen = heap->old_gen(); 580 581 // Begin compacting into the old gen 582 PSMarkSweepDecorator::set_destination_decorator_tenured(); 583 584 // This will also compact the young gen spaces. 585 old_gen->precompact(); 586 } 587 588 void PSMarkSweep::mark_sweep_phase3() { 589 // Adjust the pointers to reflect the new locations 590 GCTraceTime(Info, gc, phases) tm("Phase 3: Adjust pointers", _gc_timer); 591 592 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 593 PSYoungGen* young_gen = heap->young_gen(); 594 PSOldGen* old_gen = heap->old_gen(); 595 596 // Need to clear claim bits before the tracing starts. 597 ClassLoaderDataGraph::clear_claimed_marks(); 598 599 // General strong roots. 600 Universe::oops_do(adjust_pointer_closure()); 601 JNIHandles::oops_do(adjust_pointer_closure()); // Global (strong) JNI handles 602 Threads::oops_do(adjust_pointer_closure(), NULL); 603 ObjectSynchronizer::oops_do(adjust_pointer_closure()); 604 FlatProfiler::oops_do(adjust_pointer_closure()); 605 Management::oops_do(adjust_pointer_closure()); 606 JvmtiExport::oops_do(adjust_pointer_closure()); 607 SystemDictionary::oops_do(adjust_pointer_closure()); 608 ClassLoaderDataGraph::cld_do(adjust_cld_closure()); 609 610 // Now adjust pointers in remaining weak roots. (All of which should 611 // have been cleared if they pointed to non-surviving objects.) 612 // Global (weak) JNI handles 613 JNIHandles::weak_oops_do(adjust_pointer_closure()); 614 615 CodeBlobToOopClosure adjust_from_blobs(adjust_pointer_closure(), CodeBlobToOopClosure::FixRelocations); 616 CodeCache::blobs_do(&adjust_from_blobs); 617 AOTLoader::oops_do(adjust_pointer_closure()); 618 StringTable::oops_do(adjust_pointer_closure()); 619 ref_processor()->weak_oops_do(adjust_pointer_closure()); 620 PSScavenge::reference_processor()->weak_oops_do(adjust_pointer_closure()); 621 622 adjust_marks(); 623 624 young_gen->adjust_pointers(); 625 old_gen->adjust_pointers(); 626 } 627 628 void PSMarkSweep::mark_sweep_phase4() { 629 EventMark m("4 compact heap"); 630 GCTraceTime(Info, gc, phases) tm("Phase 4: Move objects", _gc_timer); 631 632 // All pointers are now adjusted, move objects accordingly 633 634 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 635 PSYoungGen* young_gen = heap->young_gen(); 636 PSOldGen* old_gen = heap->old_gen(); 637 638 old_gen->compact(); 639 young_gen->compact(); 640 } 641 642 jlong PSMarkSweep::millis_since_last_gc() { 643 // We need a monotonically non-decreasing time in ms but 644 // os::javaTimeMillis() does not guarantee monotonicity. 645 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 646 jlong ret_val = now - _time_of_last_gc; 647 // XXX See note in genCollectedHeap::millis_since_last_gc(). 648 if (ret_val < 0) { 649 NOT_PRODUCT(log_warning(gc)("time warp: " JLONG_FORMAT, ret_val);) 650 return 0; 651 } 652 return ret_val; 653 } 654 655 void PSMarkSweep::reset_millis_since_last_gc() { 656 // We need a monotonically non-decreasing time in ms but 657 // os::javaTimeMillis() does not guarantee monotonicity. 658 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 659 }