1 /* 2 * Copyright (c) 2001, 2016, 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/events.hpp" 59 #include "utilities/stack.inline.hpp" 60 61 elapsedTimer PSMarkSweep::_accumulated_time; 62 jlong PSMarkSweep::_time_of_last_gc = 0; 63 CollectorCounters* PSMarkSweep::_counters = NULL; 64 65 void PSMarkSweep::initialize() { 66 MemRegion mr = ParallelScavengeHeap::heap()->reserved_region(); 67 set_ref_processor(new ReferenceProcessor(mr)); // a vanilla ref proc 68 _counters = new CollectorCounters("PSMarkSweep", 1); 69 } 70 71 // This method contains all heap specific policy for invoking mark sweep. 72 // PSMarkSweep::invoke_no_policy() will only attempt to mark-sweep-compact 73 // the heap. It will do nothing further. If we need to bail out for policy 74 // reasons, scavenge before full gc, or any other specialized behavior, it 75 // needs to be added here. 76 // 77 // Note that this method should only be called from the vm_thread while 78 // at a safepoint! 79 // 80 // Note that the all_soft_refs_clear flag in the collector policy 81 // may be true because this method can be called without intervening 82 // activity. For example when the heap space is tight and full measure 83 // are being taken to free space. 84 85 void PSMarkSweep::invoke(bool maximum_heap_compaction) { 86 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 87 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread"); 88 assert(!ParallelScavengeHeap::heap()->is_gc_active(), "not reentrant"); 89 90 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 91 GCCause::Cause gc_cause = heap->gc_cause(); 92 PSAdaptiveSizePolicy* policy = heap->size_policy(); 93 IsGCActiveMark mark; 94 95 if (ScavengeBeforeFullGC) { 96 PSScavenge::invoke_no_policy(); 97 } 98 99 const bool clear_all_soft_refs = 100 heap->collector_policy()->should_clear_all_soft_refs(); 101 102 uint count = maximum_heap_compaction ? 1 : MarkSweepAlwaysCompactCount; 103 UIntFlagSetting flag_setting(MarkSweepAlwaysCompactCount, count); 104 PSMarkSweep::invoke_no_policy(clear_all_soft_refs || maximum_heap_compaction); 105 } 106 107 // This method contains no policy. You should probably 108 // be calling invoke() instead. 109 bool PSMarkSweep::invoke_no_policy(bool clear_all_softrefs) { 110 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint"); 111 assert(ref_processor() != NULL, "Sanity"); 112 113 if (GCLocker::check_active_before_gc()) { 114 return false; 115 } 116 117 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 118 GCCause::Cause gc_cause = heap->gc_cause(); 119 120 GCIdMark gc_id_mark; 121 _gc_timer->register_gc_start(); 122 _gc_tracer->report_gc_start(gc_cause, _gc_timer->gc_start()); 123 124 PSAdaptiveSizePolicy* size_policy = heap->size_policy(); 125 126 // The scope of casr should end after code that can change 127 // CollectorPolicy::_should_clear_all_soft_refs. 128 ClearedAllSoftRefs casr(clear_all_softrefs, heap->collector_policy()); 129 130 PSYoungGen* young_gen = heap->young_gen(); 131 PSOldGen* old_gen = heap->old_gen(); 132 133 // Increment the invocation count 134 heap->increment_total_collections(true /* full */); 135 136 // Save information needed to minimize mangling 137 heap->record_gen_tops_before_GC(); 138 139 // We need to track unique mark sweep invocations as well. 140 _total_invocations++; 141 142 heap->print_heap_before_gc(); 143 heap->trace_heap_before_gc(_gc_tracer); 144 145 // Fill in TLABs 146 heap->accumulate_statistics_all_tlabs(); 147 heap->ensure_parsability(true); // retire TLABs 148 149 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) { 150 HandleMark hm; // Discard invalid handles created during verification 151 Universe::verify("Before GC"); 152 } 153 154 // Verify object start arrays 155 if (VerifyObjectStartArray && 156 VerifyBeforeGC) { 157 old_gen->verify_object_start_array(); 158 } 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); 170 171 heap->pre_full_gc_dump(_gc_timer); 172 173 TraceCollectorStats tcs(counters()); 174 TraceMemoryManagerStats tms(true /* Full GC */,gc_cause); 175 176 if (TraceOldGenTime) accumulated_time()->start(); 177 178 // Let the size policy know we're starting 179 size_policy->major_collection_begin(); 180 181 CodeCache::gc_prologue(); 182 BiasedLocking::preserve_marks(); 183 184 // Capture metadata size before collection for sizing. 185 size_t metadata_prev_used = MetaspaceAux::used_bytes(); 186 187 size_t old_gen_prev_used = old_gen->used_in_bytes(); 188 size_t young_gen_prev_used = young_gen->used_in_bytes(); 189 190 allocate_stacks(); 191 192 #if defined(COMPILER2) || INCLUDE_JVMCI 193 DerivedPointerTable::clear(); 194 #endif 195 196 ref_processor()->enable_discovery(); 197 ref_processor()->setup_policy(clear_all_softrefs); 198 199 mark_sweep_phase1(clear_all_softrefs); 200 201 mark_sweep_phase2(); 202 203 #if defined(COMPILER2) || INCLUDE_JVMCI 204 // Don't add any more derived pointers during phase3 205 assert(DerivedPointerTable::is_active(), "Sanity"); 206 DerivedPointerTable::set_active(false); 207 #endif 208 209 mark_sweep_phase3(); 210 211 mark_sweep_phase4(); 212 213 restore_marks(); 214 215 deallocate_stacks(); 216 217 if (ZapUnusedHeapArea) { 218 // Do a complete mangle (top to end) because the usage for 219 // scratch does not maintain a top pointer. 220 young_gen->to_space()->mangle_unused_area_complete(); 221 } 222 223 eden_empty = young_gen->eden_space()->is_empty(); 224 if (!eden_empty) { 225 eden_empty = absorb_live_data_from_eden(size_policy, young_gen, old_gen); 226 } 227 228 // Update heap occupancy information which is used as 229 // input to soft ref clearing policy at the next gc. 230 Universe::update_heap_info_at_gc(); 231 232 survivors_empty = young_gen->from_space()->is_empty() && 233 young_gen->to_space()->is_empty(); 234 young_gen_empty = eden_empty && survivors_empty; 235 236 PSCardTable* card_table = heap->card_table(); 237 MemRegion old_mr = heap->old_gen()->reserved(); 238 if (young_gen_empty) { 239 card_table->clear(MemRegion(old_mr.start(), old_mr.end())); 240 } else { 241 card_table->invalidate(MemRegion(old_mr.start(), old_mr.end())); 242 } 243 244 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 245 ClassLoaderDataGraph::purge(); 246 MetaspaceAux::verify_metrics(); 247 248 BiasedLocking::restore_marks(); 249 CodeCache::gc_epilogue(); 250 JvmtiExport::gc_epilogue(); 251 252 #if defined(COMPILER2) || INCLUDE_JVMCI 253 DerivedPointerTable::update_pointers(); 254 #endif 255 256 ref_processor()->enqueue_discovered_references(NULL); 257 258 // Update time of last GC 259 reset_millis_since_last_gc(); 260 261 // Let the size policy know we're done 262 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause); 263 264 if (UseAdaptiveSizePolicy) { 265 266 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections()); 267 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT, 268 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes()); 269 270 // Don't check if the size_policy is ready here. Let 271 // the size_policy check that internally. 272 if (UseAdaptiveGenerationSizePolicyAtMajorCollection && 273 AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) { 274 // Swap the survivor spaces if from_space is empty. The 275 // resize_young_gen() called below is normally used after 276 // a successful young GC and swapping of survivor spaces; 277 // otherwise, it will fail to resize the young gen with 278 // the current implementation. 279 if (young_gen->from_space()->is_empty()) { 280 young_gen->from_space()->clear(SpaceDecorator::Mangle); 281 young_gen->swap_spaces(); 282 } 283 284 // Calculate optimal free space amounts 285 assert(young_gen->max_size() > 286 young_gen->from_space()->capacity_in_bytes() + 287 young_gen->to_space()->capacity_in_bytes(), 288 "Sizes of space in young gen are out-of-bounds"); 289 290 size_t young_live = young_gen->used_in_bytes(); 291 size_t eden_live = young_gen->eden_space()->used_in_bytes(); 292 size_t old_live = old_gen->used_in_bytes(); 293 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes(); 294 size_t max_old_gen_size = old_gen->max_gen_size(); 295 size_t max_eden_size = young_gen->max_size() - 296 young_gen->from_space()->capacity_in_bytes() - 297 young_gen->to_space()->capacity_in_bytes(); 298 299 // Used for diagnostics 300 size_policy->clear_generation_free_space_flags(); 301 302 size_policy->compute_generations_free_space(young_live, 303 eden_live, 304 old_live, 305 cur_eden, 306 max_old_gen_size, 307 max_eden_size, 308 true /* full gc*/); 309 310 size_policy->check_gc_overhead_limit(young_live, 311 eden_live, 312 max_old_gen_size, 313 max_eden_size, 314 true /* full gc*/, 315 gc_cause, 316 heap->collector_policy()); 317 318 size_policy->decay_supplemental_growth(true /* full gc*/); 319 320 heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes()); 321 322 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(), 323 size_policy->calculated_survivor_size_in_bytes()); 324 } 325 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections()); 326 } 327 328 if (UsePerfData) { 329 heap->gc_policy_counters()->update_counters(); 330 heap->gc_policy_counters()->update_old_capacity( 331 old_gen->capacity_in_bytes()); 332 heap->gc_policy_counters()->update_young_capacity( 333 young_gen->capacity_in_bytes()); 334 } 335 336 heap->resize_all_tlabs(); 337 338 // We collected the heap, recalculate the metaspace capacity 339 MetaspaceGC::compute_new_size(); 340 341 if (TraceOldGenTime) accumulated_time()->stop(); 342 343 young_gen->print_used_change(young_gen_prev_used); 344 old_gen->print_used_change(old_gen_prev_used); 345 MetaspaceAux::print_metaspace_change(metadata_prev_used); 346 347 // Track memory usage and detect low memory 348 MemoryService::track_memory_usage(); 349 heap->update_counters(); 350 351 heap->post_full_gc_dump(_gc_timer); 352 } 353 354 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) { 355 HandleMark hm; // Discard invalid handles created during verification 356 Universe::verify("After GC"); 357 } 358 359 // Re-verify object start arrays 360 if (VerifyObjectStartArray && 361 VerifyAfterGC) { 362 old_gen->verify_object_start_array(); 363 } 364 365 if (ZapUnusedHeapArea) { 366 old_gen->object_space()->check_mangled_unused_area_complete(); 367 } 368 369 NOT_PRODUCT(ref_processor()->verify_no_references_recorded()); 370 371 heap->print_heap_after_gc(); 372 heap->trace_heap_after_gc(_gc_tracer); 373 374 #ifdef TRACESPINNING 375 ParallelTaskTerminator::print_termination_counts(); 376 #endif 377 378 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections()); 379 380 _gc_timer->register_gc_end(); 381 382 _gc_tracer->report_gc_end(_gc_timer->gc_end(), _gc_timer->time_partitions()); 383 384 return true; 385 } 386 387 bool PSMarkSweep::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy, 388 PSYoungGen* young_gen, 389 PSOldGen* old_gen) { 390 MutableSpace* const eden_space = young_gen->eden_space(); 391 assert(!eden_space->is_empty(), "eden must be non-empty"); 392 assert(young_gen->virtual_space()->alignment() == 393 old_gen->virtual_space()->alignment(), "alignments do not match"); 394 395 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) { 396 return false; 397 } 398 399 // Both generations must be completely committed. 400 if (young_gen->virtual_space()->uncommitted_size() != 0) { 401 return false; 402 } 403 if (old_gen->virtual_space()->uncommitted_size() != 0) { 404 return false; 405 } 406 407 // Figure out how much to take from eden. Include the average amount promoted 408 // in the total; otherwise the next young gen GC will simply bail out to a 409 // full GC. 410 const size_t alignment = old_gen->virtual_space()->alignment(); 411 const size_t eden_used = eden_space->used_in_bytes(); 412 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average(); 413 const size_t absorb_size = align_size_up(eden_used + promoted, alignment); 414 const size_t eden_capacity = eden_space->capacity_in_bytes(); 415 416 if (absorb_size >= eden_capacity) { 417 return false; // Must leave some space in eden. 418 } 419 420 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size; 421 if (new_young_size < young_gen->min_gen_size()) { 422 return false; // Respect young gen minimum size. 423 } 424 425 log_trace(heap, ergo)(" absorbing " SIZE_FORMAT "K: " 426 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K " 427 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K " 428 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ", 429 absorb_size / K, 430 eden_capacity / K, (eden_capacity - absorb_size) / K, 431 young_gen->from_space()->used_in_bytes() / K, 432 young_gen->to_space()->used_in_bytes() / K, 433 young_gen->capacity_in_bytes() / K, new_young_size / K); 434 435 // Fill the unused part of the old gen. 436 MutableSpace* const old_space = old_gen->object_space(); 437 HeapWord* const unused_start = old_space->top(); 438 size_t const unused_words = pointer_delta(old_space->end(), unused_start); 439 440 if (unused_words > 0) { 441 if (unused_words < CollectedHeap::min_fill_size()) { 442 return false; // If the old gen cannot be filled, must give up. 443 } 444 CollectedHeap::fill_with_objects(unused_start, unused_words); 445 } 446 447 // Take the live data from eden and set both top and end in the old gen to 448 // eden top. (Need to set end because reset_after_change() mangles the region 449 // from end to virtual_space->high() in debug builds). 450 HeapWord* const new_top = eden_space->top(); 451 old_gen->virtual_space()->expand_into(young_gen->virtual_space(), 452 absorb_size); 453 young_gen->reset_after_change(); 454 old_space->set_top(new_top); 455 old_space->set_end(new_top); 456 old_gen->reset_after_change(); 457 458 // Update the object start array for the filler object and the data from eden. 459 ObjectStartArray* const start_array = old_gen->start_array(); 460 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) { 461 start_array->allocate_block(p); 462 } 463 464 // Could update the promoted average here, but it is not typically updated at 465 // full GCs and the value to use is unclear. Something like 466 // 467 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc. 468 469 size_policy->set_bytes_absorbed_from_eden(absorb_size); 470 return true; 471 } 472 473 void PSMarkSweep::allocate_stacks() { 474 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 475 PSYoungGen* young_gen = heap->young_gen(); 476 477 MutableSpace* to_space = young_gen->to_space(); 478 _preserved_marks = (PreservedMark*)to_space->top(); 479 _preserved_count = 0; 480 481 // We want to calculate the size in bytes first. 482 _preserved_count_max = pointer_delta(to_space->end(), to_space->top(), sizeof(jbyte)); 483 // Now divide by the size of a PreservedMark 484 _preserved_count_max /= sizeof(PreservedMark); 485 } 486 487 488 void PSMarkSweep::deallocate_stacks() { 489 _preserved_mark_stack.clear(true); 490 _preserved_oop_stack.clear(true); 491 _marking_stack.clear(); 492 _objarray_stack.clear(true); 493 } 494 495 void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) { 496 // Recursively traverse all live objects and mark them 497 GCTraceTime(Info, gc, phases) tm("Phase 1: Mark live objects", _gc_timer); 498 499 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 500 501 // Need to clear claim bits before the tracing starts. 502 ClassLoaderDataGraph::clear_claimed_marks(); 503 504 // General strong roots. 505 { 506 ParallelScavengeHeap::ParStrongRootsScope psrs; 507 Universe::oops_do(mark_and_push_closure()); 508 JNIHandles::oops_do(mark_and_push_closure()); // Global (strong) JNI handles 509 MarkingCodeBlobClosure each_active_code_blob(mark_and_push_closure(), !CodeBlobToOopClosure::FixRelocations); 510 Threads::oops_do(mark_and_push_closure(), &each_active_code_blob); 511 ObjectSynchronizer::oops_do(mark_and_push_closure()); 512 FlatProfiler::oops_do(mark_and_push_closure()); 513 Management::oops_do(mark_and_push_closure()); 514 JvmtiExport::oops_do(mark_and_push_closure()); 515 SystemDictionary::always_strong_oops_do(mark_and_push_closure()); 516 ClassLoaderDataGraph::always_strong_cld_do(follow_cld_closure()); 517 // Do not treat nmethods as strong roots for mark/sweep, since we can unload them. 518 //CodeCache::scavenge_root_nmethods_do(CodeBlobToOopClosure(mark_and_push_closure())); 519 AOTLoader::oops_do(mark_and_push_closure()); 520 } 521 522 // Flush marking stack. 523 follow_stack(); 524 525 // Process reference objects found during marking 526 { 527 GCTraceTime(Debug, gc, phases) t("Reference Processing", _gc_timer); 528 529 ref_processor()->setup_policy(clear_all_softrefs); 530 const ReferenceProcessorStats& stats = 531 ref_processor()->process_discovered_references( 532 is_alive_closure(), mark_and_push_closure(), follow_stack_closure(), NULL, _gc_timer); 533 gc_tracer()->report_gc_reference_stats(stats); 534 } 535 536 // This is the point where the entire marking should have completed. 537 assert(_marking_stack.is_empty(), "Marking should have completed"); 538 539 { 540 GCTraceTime(Debug, gc, phases) t("Class Unloading", _gc_timer); 541 542 // Unload classes and purge the SystemDictionary. 543 bool purged_class = SystemDictionary::do_unloading(is_alive_closure()); 544 545 // Unload nmethods. 546 CodeCache::do_unloading(is_alive_closure(), purged_class); 547 548 // Prune dead klasses from subklass/sibling/implementor lists. 549 Klass::clean_weak_klass_links(is_alive_closure()); 550 } 551 552 { 553 GCTraceTime(Debug, gc, phases) t("Scrub String Table", _gc_timer); 554 // Delete entries for dead interned strings. 555 StringTable::unlink(is_alive_closure()); 556 } 557 558 { 559 GCTraceTime(Debug, gc, phases) t("Scrub Symbol Table", _gc_timer); 560 // Clean up unreferenced symbols in symbol table. 561 SymbolTable::unlink(); 562 } 563 564 _gc_tracer->report_object_count_after_gc(is_alive_closure()); 565 } 566 567 568 void PSMarkSweep::mark_sweep_phase2() { 569 GCTraceTime(Info, gc, phases) tm("Phase 2: Compute new object addresses", _gc_timer); 570 571 // Now all live objects are marked, compute the new object addresses. 572 573 // It is not required that we traverse spaces in the same order in 574 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops 575 // tracking expects us to do so. See comment under phase4. 576 577 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 578 PSOldGen* old_gen = heap->old_gen(); 579 580 // Begin compacting into the old gen 581 PSMarkSweepDecorator::set_destination_decorator_tenured(); 582 583 // This will also compact the young gen spaces. 584 old_gen->precompact(); 585 } 586 587 void PSMarkSweep::mark_sweep_phase3() { 588 // Adjust the pointers to reflect the new locations 589 GCTraceTime(Info, gc, phases) tm("Phase 3: Adjust pointers", _gc_timer); 590 591 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 592 PSYoungGen* young_gen = heap->young_gen(); 593 PSOldGen* old_gen = heap->old_gen(); 594 595 // Need to clear claim bits before the tracing starts. 596 ClassLoaderDataGraph::clear_claimed_marks(); 597 598 // General strong roots. 599 Universe::oops_do(adjust_pointer_closure()); 600 JNIHandles::oops_do(adjust_pointer_closure()); // Global (strong) JNI handles 601 Threads::oops_do(adjust_pointer_closure(), NULL); 602 ObjectSynchronizer::oops_do(adjust_pointer_closure()); 603 FlatProfiler::oops_do(adjust_pointer_closure()); 604 Management::oops_do(adjust_pointer_closure()); 605 JvmtiExport::oops_do(adjust_pointer_closure()); 606 SystemDictionary::oops_do(adjust_pointer_closure()); 607 ClassLoaderDataGraph::cld_do(adjust_cld_closure()); 608 609 // Now adjust pointers in remaining weak roots. (All of which should 610 // have been cleared if they pointed to non-surviving objects.) 611 // Global (weak) JNI handles 612 JNIHandles::weak_oops_do(adjust_pointer_closure()); 613 614 CodeBlobToOopClosure adjust_from_blobs(adjust_pointer_closure(), CodeBlobToOopClosure::FixRelocations); 615 CodeCache::blobs_do(&adjust_from_blobs); 616 AOTLoader::oops_do(adjust_pointer_closure()); 617 StringTable::oops_do(adjust_pointer_closure()); 618 ref_processor()->weak_oops_do(adjust_pointer_closure()); 619 PSScavenge::reference_processor()->weak_oops_do(adjust_pointer_closure()); 620 621 adjust_marks(); 622 623 young_gen->adjust_pointers(); 624 old_gen->adjust_pointers(); 625 } 626 627 void PSMarkSweep::mark_sweep_phase4() { 628 EventMark m("4 compact heap"); 629 GCTraceTime(Info, gc, phases) tm("Phase 4: Move objects", _gc_timer); 630 631 // All pointers are now adjusted, move objects accordingly 632 633 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 634 PSYoungGen* young_gen = heap->young_gen(); 635 PSOldGen* old_gen = heap->old_gen(); 636 637 old_gen->compact(); 638 young_gen->compact(); 639 } 640 641 jlong PSMarkSweep::millis_since_last_gc() { 642 // We need a monotonically non-decreasing time in ms but 643 // os::javaTimeMillis() does not guarantee monotonicity. 644 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 645 jlong ret_val = now - _time_of_last_gc; 646 // XXX See note in genCollectedHeap::millis_since_last_gc(). 647 if (ret_val < 0) { 648 NOT_PRODUCT(log_warning(gc)("time warp: " JLONG_FORMAT, ret_val);) 649 return 0; 650 } 651 return ret_val; 652 } 653 654 void PSMarkSweep::reset_millis_since_last_gc() { 655 // We need a monotonically non-decreasing time in ms but 656 // os::javaTimeMillis() does not guarantee monotonicity. 657 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 658 }