1 /* 2 * Copyright (c) 2001, 2015, 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 "classfile/stringTable.hpp" 27 #include "classfile/systemDictionary.hpp" 28 #include "code/codeCache.hpp" 29 #include "gc/parallel/parallelScavengeHeap.hpp" 30 #include "gc/parallel/psAdaptiveSizePolicy.hpp" 31 #include "gc/parallel/psMarkSweep.hpp" 32 #include "gc/parallel/psMarkSweepDecorator.hpp" 33 #include "gc/parallel/psOldGen.hpp" 34 #include "gc/parallel/psScavenge.hpp" 35 #include "gc/parallel/psYoungGen.hpp" 36 #include "gc/serial/markSweep.hpp" 37 #include "gc/shared/gcCause.hpp" 38 #include "gc/shared/gcHeapSummary.hpp" 39 #include "gc/shared/gcId.hpp" 40 #include "gc/shared/gcLocker.inline.hpp" 41 #include "gc/shared/gcTimer.hpp" 42 #include "gc/shared/gcTrace.hpp" 43 #include "gc/shared/gcTraceTime.hpp" 44 #include "gc/shared/isGCActiveMark.hpp" 45 #include "gc/shared/referencePolicy.hpp" 46 #include "gc/shared/referenceProcessor.hpp" 47 #include "gc/shared/spaceDecorator.hpp" 48 #include "logging/log.hpp" 49 #include "oops/oop.inline.hpp" 50 #include "runtime/biasedLocking.hpp" 51 #include "runtime/fprofiler.hpp" 52 #include "runtime/safepoint.hpp" 53 #include "runtime/vmThread.hpp" 54 #include "services/management.hpp" 55 #include "services/memoryService.hpp" 56 #include "utilities/events.hpp" 57 #include "utilities/stack.inline.hpp" 58 59 elapsedTimer PSMarkSweep::_accumulated_time; 60 jlong PSMarkSweep::_time_of_last_gc = 0; 61 CollectorCounters* PSMarkSweep::_counters = NULL; 62 63 void PSMarkSweep::initialize() { 64 MemRegion mr = ParallelScavengeHeap::heap()->reserved_region(); 65 set_ref_processor(new ReferenceProcessor(mr)); // a vanilla ref proc 66 _counters = new CollectorCounters("PSMarkSweep", 1); 67 } 68 69 // This method contains all heap specific policy for invoking mark sweep. 70 // PSMarkSweep::invoke_no_policy() will only attempt to mark-sweep-compact 71 // the heap. It will do nothing further. If we need to bail out for policy 72 // reasons, scavenge before full gc, or any other specialized behavior, it 73 // needs to be added here. 74 // 75 // Note that this method should only be called from the vm_thread while 76 // at a safepoint! 77 // 78 // Note that the all_soft_refs_clear flag in the collector policy 79 // may be true because this method can be called without intervening 80 // activity. For example when the heap space is tight and full measure 81 // are being taken to free space. 82 83 void PSMarkSweep::invoke(bool maximum_heap_compaction) { 84 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 85 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread"); 86 assert(!ParallelScavengeHeap::heap()->is_gc_active(), "not reentrant"); 87 88 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 89 GCCause::Cause gc_cause = heap->gc_cause(); 90 PSAdaptiveSizePolicy* policy = heap->size_policy(); 91 IsGCActiveMark mark; 92 93 if (ScavengeBeforeFullGC) { 94 PSScavenge::invoke_no_policy(); 95 } 96 97 const bool clear_all_soft_refs = 98 heap->collector_policy()->should_clear_all_soft_refs(); 99 100 uint count = maximum_heap_compaction ? 1 : MarkSweepAlwaysCompactCount; 101 UIntXFlagSetting flag_setting(MarkSweepAlwaysCompactCount, count); 102 PSMarkSweep::invoke_no_policy(clear_all_soft_refs || maximum_heap_compaction); 103 } 104 105 // This method contains no policy. You should probably 106 // be calling invoke() instead. 107 bool PSMarkSweep::invoke_no_policy(bool clear_all_softrefs) { 108 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint"); 109 assert(ref_processor() != NULL, "Sanity"); 110 111 if (GC_locker::check_active_before_gc()) { 112 return false; 113 } 114 115 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 116 GCCause::Cause gc_cause = heap->gc_cause(); 117 118 GCIdMark gc_id_mark; 119 _gc_timer->register_gc_start(); 120 _gc_tracer->report_gc_start(gc_cause, _gc_timer->gc_start()); 121 122 PSAdaptiveSizePolicy* size_policy = heap->size_policy(); 123 124 // The scope of casr should end after code that can change 125 // CollectorPolicy::_should_clear_all_soft_refs. 126 ClearedAllSoftRefs casr(clear_all_softrefs, heap->collector_policy()); 127 128 PSYoungGen* young_gen = heap->young_gen(); 129 PSOldGen* old_gen = heap->old_gen(); 130 131 // Increment the invocation count 132 heap->increment_total_collections(true /* full */); 133 134 // Save information needed to minimize mangling 135 heap->record_gen_tops_before_GC(); 136 137 // We need to track unique mark sweep invocations as well. 138 _total_invocations++; 139 140 heap->print_heap_before_gc(); 141 heap->trace_heap_before_gc(_gc_tracer); 142 143 // Fill in TLABs 144 heap->accumulate_statistics_all_tlabs(); 145 heap->ensure_parsability(true); // retire TLABs 146 147 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) { 148 HandleMark hm; // Discard invalid handles created during verification 149 Universe::verify("Before GC"); 150 } 151 152 // Verify object start arrays 153 if (VerifyObjectStartArray && 154 VerifyBeforeGC) { 155 old_gen->verify_object_start_array(); 156 } 157 158 heap->pre_full_gc_dump(_gc_timer); 159 160 // Filled in below to track the state of the young gen after the collection. 161 bool eden_empty; 162 bool survivors_empty; 163 bool young_gen_empty; 164 165 { 166 HandleMark hm; 167 168 GCTraceCPUTime tcpu; 169 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause, true); 170 TraceCollectorStats tcs(counters()); 171 TraceMemoryManagerStats tms(true /* Full GC */,gc_cause); 172 173 if (TraceOldGenTime) accumulated_time()->start(); 174 175 // Let the size policy know we're starting 176 size_policy->major_collection_begin(); 177 178 CodeCache::gc_prologue(); 179 BiasedLocking::preserve_marks(); 180 181 // Capture metadata size before collection for sizing. 182 size_t metadata_prev_used = MetaspaceAux::used_bytes(); 183 184 size_t old_gen_prev_used = old_gen->used_in_bytes(); 185 size_t young_gen_prev_used = young_gen->used_in_bytes(); 186 187 allocate_stacks(); 188 189 #if defined(COMPILER2) || INCLUDE_JVMCI 190 DerivedPointerTable::clear(); 191 #endif 192 193 ref_processor()->enable_discovery(); 194 ref_processor()->setup_policy(clear_all_softrefs); 195 196 mark_sweep_phase1(clear_all_softrefs); 197 198 mark_sweep_phase2(); 199 200 #if defined(COMPILER2) || INCLUDE_JVMCI 201 // Don't add any more derived pointers during phase3 202 assert(DerivedPointerTable::is_active(), "Sanity"); 203 DerivedPointerTable::set_active(false); 204 #endif 205 206 mark_sweep_phase3(); 207 208 mark_sweep_phase4(); 209 210 restore_marks(); 211 212 deallocate_stacks(); 213 214 if (ZapUnusedHeapArea) { 215 // Do a complete mangle (top to end) because the usage for 216 // scratch does not maintain a top pointer. 217 young_gen->to_space()->mangle_unused_area_complete(); 218 } 219 220 eden_empty = young_gen->eden_space()->is_empty(); 221 if (!eden_empty) { 222 eden_empty = absorb_live_data_from_eden(size_policy, young_gen, old_gen); 223 } 224 225 // Update heap occupancy information which is used as 226 // input to soft ref clearing policy at the next gc. 227 Universe::update_heap_info_at_gc(); 228 229 survivors_empty = young_gen->from_space()->is_empty() && 230 young_gen->to_space()->is_empty(); 231 young_gen_empty = eden_empty && survivors_empty; 232 233 ModRefBarrierSet* modBS = barrier_set_cast<ModRefBarrierSet>(heap->barrier_set()); 234 MemRegion old_mr = heap->old_gen()->reserved(); 235 if (young_gen_empty) { 236 modBS->clear(MemRegion(old_mr.start(), old_mr.end())); 237 } else { 238 modBS->invalidate(MemRegion(old_mr.start(), old_mr.end())); 239 } 240 241 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 242 ClassLoaderDataGraph::purge(); 243 MetaspaceAux::verify_metrics(); 244 245 BiasedLocking::restore_marks(); 246 CodeCache::gc_epilogue(); 247 JvmtiExport::gc_epilogue(); 248 249 #if defined(COMPILER2) || INCLUDE_JVMCI 250 DerivedPointerTable::update_pointers(); 251 #endif 252 253 ref_processor()->enqueue_discovered_references(NULL); 254 255 // Update time of last GC 256 reset_millis_since_last_gc(); 257 258 // Let the size policy know we're done 259 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause); 260 261 if (UseAdaptiveSizePolicy) { 262 263 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections()); 264 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT, 265 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes()); 266 267 // Don't check if the size_policy is ready here. Let 268 // the size_policy check that internally. 269 if (UseAdaptiveGenerationSizePolicyAtMajorCollection && 270 AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) { 271 // Swap the survivor spaces if from_space is empty. The 272 // resize_young_gen() called below is normally used after 273 // a successful young GC and swapping of survivor spaces; 274 // otherwise, it will fail to resize the young gen with 275 // the current implementation. 276 if (young_gen->from_space()->is_empty()) { 277 young_gen->from_space()->clear(SpaceDecorator::Mangle); 278 young_gen->swap_spaces(); 279 } 280 281 // Calculate optimal free space amounts 282 assert(young_gen->max_size() > 283 young_gen->from_space()->capacity_in_bytes() + 284 young_gen->to_space()->capacity_in_bytes(), 285 "Sizes of space in young gen are out-of-bounds"); 286 287 size_t young_live = young_gen->used_in_bytes(); 288 size_t eden_live = young_gen->eden_space()->used_in_bytes(); 289 size_t old_live = old_gen->used_in_bytes(); 290 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes(); 291 size_t max_old_gen_size = old_gen->max_gen_size(); 292 size_t max_eden_size = young_gen->max_size() - 293 young_gen->from_space()->capacity_in_bytes() - 294 young_gen->to_space()->capacity_in_bytes(); 295 296 // Used for diagnostics 297 size_policy->clear_generation_free_space_flags(); 298 299 size_policy->compute_generations_free_space(young_live, 300 eden_live, 301 old_live, 302 cur_eden, 303 max_old_gen_size, 304 max_eden_size, 305 true /* full gc*/); 306 307 size_policy->check_gc_overhead_limit(young_live, 308 eden_live, 309 max_old_gen_size, 310 max_eden_size, 311 true /* full gc*/, 312 gc_cause, 313 heap->collector_policy()); 314 315 size_policy->decay_supplemental_growth(true /* full gc*/); 316 317 heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes()); 318 319 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(), 320 size_policy->calculated_survivor_size_in_bytes()); 321 } 322 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections()); 323 } 324 325 if (UsePerfData) { 326 heap->gc_policy_counters()->update_counters(); 327 heap->gc_policy_counters()->update_old_capacity( 328 old_gen->capacity_in_bytes()); 329 heap->gc_policy_counters()->update_young_capacity( 330 young_gen->capacity_in_bytes()); 331 } 332 333 heap->resize_all_tlabs(); 334 335 // We collected the heap, recalculate the metaspace capacity 336 MetaspaceGC::compute_new_size(); 337 338 if (TraceOldGenTime) accumulated_time()->stop(); 339 340 young_gen->print_used_change(young_gen_prev_used); 341 old_gen->print_used_change(old_gen_prev_used); 342 MetaspaceAux::print_metaspace_change(metadata_prev_used); 343 344 // Track memory usage and detect low memory 345 MemoryService::track_memory_usage(); 346 heap->update_counters(); 347 } 348 349 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) { 350 HandleMark hm; // Discard invalid handles created during verification 351 Universe::verify("After GC"); 352 } 353 354 // Re-verify object start arrays 355 if (VerifyObjectStartArray && 356 VerifyAfterGC) { 357 old_gen->verify_object_start_array(); 358 } 359 360 if (ZapUnusedHeapArea) { 361 old_gen->object_space()->check_mangled_unused_area_complete(); 362 } 363 364 NOT_PRODUCT(ref_processor()->verify_no_references_recorded()); 365 366 heap->print_heap_after_gc(); 367 heap->trace_heap_after_gc(_gc_tracer); 368 369 heap->post_full_gc_dump(_gc_timer); 370 371 #ifdef TRACESPINNING 372 ParallelTaskTerminator::print_termination_counts(); 373 #endif 374 375 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections()); 376 377 _gc_timer->register_gc_end(); 378 379 _gc_tracer->report_gc_end(_gc_timer->gc_end(), _gc_timer->time_partitions()); 380 381 return true; 382 } 383 384 bool PSMarkSweep::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy, 385 PSYoungGen* young_gen, 386 PSOldGen* old_gen) { 387 MutableSpace* const eden_space = young_gen->eden_space(); 388 assert(!eden_space->is_empty(), "eden must be non-empty"); 389 assert(young_gen->virtual_space()->alignment() == 390 old_gen->virtual_space()->alignment(), "alignments do not match"); 391 392 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) { 393 return false; 394 } 395 396 // Both generations must be completely committed. 397 if (young_gen->virtual_space()->uncommitted_size() != 0) { 398 return false; 399 } 400 if (old_gen->virtual_space()->uncommitted_size() != 0) { 401 return false; 402 } 403 404 // Figure out how much to take from eden. Include the average amount promoted 405 // in the total; otherwise the next young gen GC will simply bail out to a 406 // full GC. 407 const size_t alignment = old_gen->virtual_space()->alignment(); 408 const size_t eden_used = eden_space->used_in_bytes(); 409 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average(); 410 const size_t absorb_size = align_size_up(eden_used + promoted, alignment); 411 const size_t eden_capacity = eden_space->capacity_in_bytes(); 412 413 if (absorb_size >= eden_capacity) { 414 return false; // Must leave some space in eden. 415 } 416 417 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size; 418 if (new_young_size < young_gen->min_gen_size()) { 419 return false; // Respect young gen minimum size. 420 } 421 422 log_trace(heap, ergo)(" absorbing " SIZE_FORMAT "K: " 423 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K " 424 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K " 425 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ", 426 absorb_size / K, 427 eden_capacity / K, (eden_capacity - absorb_size) / K, 428 young_gen->from_space()->used_in_bytes() / K, 429 young_gen->to_space()->used_in_bytes() / K, 430 young_gen->capacity_in_bytes() / K, new_young_size / K); 431 432 // Fill the unused part of the old gen. 433 MutableSpace* const old_space = old_gen->object_space(); 434 HeapWord* const unused_start = old_space->top(); 435 size_t const unused_words = pointer_delta(old_space->end(), unused_start); 436 437 if (unused_words > 0) { 438 if (unused_words < CollectedHeap::min_fill_size()) { 439 return false; // If the old gen cannot be filled, must give up. 440 } 441 CollectedHeap::fill_with_objects(unused_start, unused_words); 442 } 443 444 // Take the live data from eden and set both top and end in the old gen to 445 // eden top. (Need to set end because reset_after_change() mangles the region 446 // from end to virtual_space->high() in debug builds). 447 HeapWord* const new_top = eden_space->top(); 448 old_gen->virtual_space()->expand_into(young_gen->virtual_space(), 449 absorb_size); 450 young_gen->reset_after_change(); 451 old_space->set_top(new_top); 452 old_space->set_end(new_top); 453 old_gen->reset_after_change(); 454 455 // Update the object start array for the filler object and the data from eden. 456 ObjectStartArray* const start_array = old_gen->start_array(); 457 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) { 458 start_array->allocate_block(p); 459 } 460 461 // Could update the promoted average here, but it is not typically updated at 462 // full GCs and the value to use is unclear. Something like 463 // 464 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc. 465 466 size_policy->set_bytes_absorbed_from_eden(absorb_size); 467 return true; 468 } 469 470 void PSMarkSweep::allocate_stacks() { 471 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 472 PSYoungGen* young_gen = heap->young_gen(); 473 474 MutableSpace* to_space = young_gen->to_space(); 475 _preserved_marks = (PreservedMark*)to_space->top(); 476 _preserved_count = 0; 477 478 // We want to calculate the size in bytes first. 479 _preserved_count_max = pointer_delta(to_space->end(), to_space->top(), sizeof(jbyte)); 480 // Now divide by the size of a PreservedMark 481 _preserved_count_max /= sizeof(PreservedMark); 482 } 483 484 485 void PSMarkSweep::deallocate_stacks() { 486 _preserved_mark_stack.clear(true); 487 _preserved_oop_stack.clear(true); 488 _marking_stack.clear(); 489 _objarray_stack.clear(true); 490 } 491 492 void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) { 493 // Recursively traverse all live objects and mark them 494 GCTraceTime(Trace, gc) tm("Phase 1: Mark live objects", _gc_timer); 495 496 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 497 498 // Need to clear claim bits before the tracing starts. 499 ClassLoaderDataGraph::clear_claimed_marks(); 500 501 // General strong roots. 502 { 503 ParallelScavengeHeap::ParStrongRootsScope psrs; 504 Universe::oops_do(mark_and_push_closure()); 505 JNIHandles::oops_do(mark_and_push_closure()); // Global (strong) JNI handles 506 CLDToOopClosure mark_and_push_from_cld(mark_and_push_closure()); 507 MarkingCodeBlobClosure each_active_code_blob(mark_and_push_closure(), !CodeBlobToOopClosure::FixRelocations); 508 Threads::oops_do(mark_and_push_closure(), &mark_and_push_from_cld, &each_active_code_blob); 509 ObjectSynchronizer::oops_do(mark_and_push_closure()); 510 FlatProfiler::oops_do(mark_and_push_closure()); 511 Management::oops_do(mark_and_push_closure()); 512 JvmtiExport::oops_do(mark_and_push_closure()); 513 SystemDictionary::always_strong_oops_do(mark_and_push_closure()); 514 ClassLoaderDataGraph::always_strong_cld_do(follow_cld_closure()); 515 // Do not treat nmethods as strong roots for mark/sweep, since we can unload them. 516 //CodeCache::scavenge_root_nmethods_do(CodeBlobToOopClosure(mark_and_push_closure())); 517 } 518 519 // Flush marking stack. 520 follow_stack(); 521 522 // Process reference objects found during marking 523 { 524 ref_processor()->setup_policy(clear_all_softrefs); 525 const ReferenceProcessorStats& stats = 526 ref_processor()->process_discovered_references( 527 is_alive_closure(), mark_and_push_closure(), follow_stack_closure(), NULL, _gc_timer); 528 gc_tracer()->report_gc_reference_stats(stats); 529 } 530 531 // This is the point where the entire marking should have completed. 532 assert(_marking_stack.is_empty(), "Marking should have completed"); 533 534 // Unload classes and purge the SystemDictionary. 535 bool purged_class = SystemDictionary::do_unloading(is_alive_closure()); 536 537 // Unload nmethods. 538 CodeCache::do_unloading(is_alive_closure(), purged_class); 539 540 // Prune dead klasses from subklass/sibling/implementor lists. 541 Klass::clean_weak_klass_links(is_alive_closure()); 542 543 // Delete entries for dead interned strings. 544 StringTable::unlink(is_alive_closure()); 545 546 // Clean up unreferenced symbols in symbol table. 547 SymbolTable::unlink(); 548 _gc_tracer->report_object_count_after_gc(is_alive_closure()); 549 } 550 551 552 void PSMarkSweep::mark_sweep_phase2() { 553 GCTraceTime(Trace, gc) tm("Phase 2: Compute new object addresses", _gc_timer); 554 555 // Now all live objects are marked, compute the new object addresses. 556 557 // It is not required that we traverse spaces in the same order in 558 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops 559 // tracking expects us to do so. See comment under phase4. 560 561 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 562 PSOldGen* old_gen = heap->old_gen(); 563 564 // Begin compacting into the old gen 565 PSMarkSweepDecorator::set_destination_decorator_tenured(); 566 567 // This will also compact the young gen spaces. 568 old_gen->precompact(); 569 } 570 571 // This should be moved to the shared markSweep code! 572 class PSAlwaysTrueClosure: public BoolObjectClosure { 573 public: 574 bool do_object_b(oop p) { return true; } 575 }; 576 static PSAlwaysTrueClosure always_true; 577 578 void PSMarkSweep::mark_sweep_phase3() { 579 // Adjust the pointers to reflect the new locations 580 GCTraceTime(Trace, gc) tm("Phase 3: Adjust pointers", _gc_timer); 581 582 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 583 PSYoungGen* young_gen = heap->young_gen(); 584 PSOldGen* old_gen = heap->old_gen(); 585 586 // Need to clear claim bits before the tracing starts. 587 ClassLoaderDataGraph::clear_claimed_marks(); 588 589 // General strong roots. 590 Universe::oops_do(adjust_pointer_closure()); 591 JNIHandles::oops_do(adjust_pointer_closure()); // Global (strong) JNI handles 592 CLDToOopClosure adjust_from_cld(adjust_pointer_closure()); 593 Threads::oops_do(adjust_pointer_closure(), &adjust_from_cld, NULL); 594 ObjectSynchronizer::oops_do(adjust_pointer_closure()); 595 FlatProfiler::oops_do(adjust_pointer_closure()); 596 Management::oops_do(adjust_pointer_closure()); 597 JvmtiExport::oops_do(adjust_pointer_closure()); 598 SystemDictionary::oops_do(adjust_pointer_closure()); 599 ClassLoaderDataGraph::cld_do(adjust_cld_closure()); 600 601 // Now adjust pointers in remaining weak roots. (All of which should 602 // have been cleared if they pointed to non-surviving objects.) 603 // Global (weak) JNI handles 604 JNIHandles::weak_oops_do(&always_true, adjust_pointer_closure()); 605 606 CodeBlobToOopClosure adjust_from_blobs(adjust_pointer_closure(), CodeBlobToOopClosure::FixRelocations); 607 CodeCache::blobs_do(&adjust_from_blobs); 608 StringTable::oops_do(adjust_pointer_closure()); 609 ref_processor()->weak_oops_do(adjust_pointer_closure()); 610 PSScavenge::reference_processor()->weak_oops_do(adjust_pointer_closure()); 611 612 adjust_marks(); 613 614 young_gen->adjust_pointers(); 615 old_gen->adjust_pointers(); 616 } 617 618 void PSMarkSweep::mark_sweep_phase4() { 619 EventMark m("4 compact heap"); 620 GCTraceTime(Trace, gc) tm("Phase 4: Move objects", _gc_timer); 621 622 // All pointers are now adjusted, move objects accordingly 623 624 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 625 PSYoungGen* young_gen = heap->young_gen(); 626 PSOldGen* old_gen = heap->old_gen(); 627 628 old_gen->compact(); 629 young_gen->compact(); 630 } 631 632 jlong PSMarkSweep::millis_since_last_gc() { 633 // We need a monotonically non-decreasing time in ms but 634 // os::javaTimeMillis() does not guarantee monotonicity. 635 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 636 jlong ret_val = now - _time_of_last_gc; 637 // XXX See note in genCollectedHeap::millis_since_last_gc(). 638 if (ret_val < 0) { 639 NOT_PRODUCT(warning("time warp: " JLONG_FORMAT, ret_val);) 640 return 0; 641 } 642 return ret_val; 643 } 644 645 void PSMarkSweep::reset_millis_since_last_gc() { 646 // We need a monotonically non-decreasing time in ms but 647 // os::javaTimeMillis() does not guarantee monotonicity. 648 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 649 }