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 "classfile/stringTable.hpp" 27 #include "classfile/symbolTable.hpp" 28 #include "classfile/systemDictionary.hpp" 29 #include "code/codeCache.hpp" 30 #include "gc/parallel/parallelScavengeHeap.hpp" 31 #include "gc/parallel/psAdaptiveSizePolicy.hpp" 32 #include "gc/parallel/psMarkSweep.hpp" 33 #include "gc/parallel/psMarkSweepDecorator.hpp" 34 #include "gc/parallel/psOldGen.hpp" 35 #include "gc/parallel/psScavenge.hpp" 36 #include "gc/parallel/psYoungGen.hpp" 37 #include "gc/serial/markSweep.hpp" 38 #include "gc/shared/gcCause.hpp" 39 #include "gc/shared/gcHeapSummary.hpp" 40 #include "gc/shared/gcId.hpp" 41 #include "gc/shared/gcLocker.inline.hpp" 42 #include "gc/shared/gcTimer.hpp" 43 #include "gc/shared/gcTrace.hpp" 44 #include "gc/shared/gcTraceTime.inline.hpp" 45 #include "gc/shared/isGCActiveMark.hpp" 46 #include "gc/shared/referencePolicy.hpp" 47 #include "gc/shared/referenceProcessor.hpp" 48 #include "gc/shared/spaceDecorator.hpp" 49 #include "logging/log.hpp" 50 #include "oops/oop.inline.hpp" 51 #include "runtime/biasedLocking.hpp" 52 #include "runtime/fprofiler.hpp" 53 #include "runtime/safepoint.hpp" 54 #include "runtime/vmThread.hpp" 55 #include "services/management.hpp" 56 #include "services/memoryService.hpp" 57 #include "utilities/events.hpp" 58 #include "utilities/stack.inline.hpp" 59 60 elapsedTimer PSMarkSweep::_accumulated_time; 61 jlong PSMarkSweep::_time_of_last_gc = 0; 62 CollectorCounters* PSMarkSweep::_counters = NULL; 63 64 void PSMarkSweep::initialize() { 65 MemRegion mr = ParallelScavengeHeap::heap()->reserved_region(); 66 set_ref_processor(new ReferenceProcessor(mr)); // a vanilla ref proc 67 _counters = new CollectorCounters("PSMarkSweep", 1); 68 } 69 70 // This method contains all heap specific policy for invoking mark sweep. 71 // PSMarkSweep::invoke_no_policy() will only attempt to mark-sweep-compact 72 // the heap. It will do nothing further. If we need to bail out for policy 73 // reasons, scavenge before full gc, or any other specialized behavior, it 74 // needs to be added here. 75 // 76 // Note that this method should only be called from the vm_thread while 77 // at a safepoint! 78 // 79 // Note that the all_soft_refs_clear flag in the collector policy 80 // may be true because this method can be called without intervening 81 // activity. For example when the heap space is tight and full measure 82 // are being taken to free space. 83 84 void PSMarkSweep::invoke(bool maximum_heap_compaction) { 85 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 86 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread"); 87 assert(!ParallelScavengeHeap::heap()->is_gc_active(), "not reentrant"); 88 89 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 90 GCCause::Cause gc_cause = heap->gc_cause(); 91 PSAdaptiveSizePolicy* policy = heap->size_policy(); 92 IsGCActiveMark mark; 93 94 if (ScavengeBeforeFullGC) { 95 PSScavenge::invoke_no_policy(); 96 } 97 98 const bool clear_all_soft_refs = 99 heap->collector_policy()->should_clear_all_soft_refs(); 100 101 uint count = maximum_heap_compaction ? 1 : MarkSweepAlwaysCompactCount; 102 UIntFlagSetting flag_setting(MarkSweepAlwaysCompactCount, count); 103 PSMarkSweep::invoke_no_policy(clear_all_soft_refs || maximum_heap_compaction); 104 } 105 106 // This method contains no policy. You should probably 107 // be calling invoke() instead. 108 bool PSMarkSweep::invoke_no_policy(bool clear_all_softrefs) { 109 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint"); 110 assert(ref_processor() != NULL, "Sanity"); 111 112 if (GCLocker::check_active_before_gc()) { 113 return false; 114 } 115 116 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 117 GCCause::Cause gc_cause = heap->gc_cause(); 118 119 GCIdMark gc_id_mark; 120 _gc_timer->register_gc_start(); 121 _gc_tracer->report_gc_start(gc_cause, _gc_timer->gc_start()); 122 123 PSAdaptiveSizePolicy* size_policy = heap->size_policy(); 124 125 // The scope of casr should end after code that can change 126 // CollectorPolicy::_should_clear_all_soft_refs. 127 ClearedAllSoftRefs casr(clear_all_softrefs, heap->collector_policy()); 128 129 PSYoungGen* young_gen = heap->young_gen(); 130 PSOldGen* old_gen = heap->old_gen(); 131 132 // Increment the invocation count 133 heap->increment_total_collections(true /* full */); 134 135 // Save information needed to minimize mangling 136 heap->record_gen_tops_before_GC(); 137 138 // We need to track unique mark sweep invocations as well. 139 _total_invocations++; 140 141 heap->print_heap_before_gc(); 142 heap->trace_heap_before_gc(_gc_tracer); 143 144 // Fill in TLABs 145 heap->accumulate_statistics_all_tlabs(); 146 heap->ensure_parsability(true); // retire TLABs 147 148 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) { 149 HandleMark hm; // Discard invalid handles created during verification 150 Universe::verify("Before GC"); 151 } 152 153 // Verify object start arrays 154 if (VerifyObjectStartArray && 155 VerifyBeforeGC) { 156 old_gen->verify_object_start_array(); 157 } 158 159 // Filled in below to track the state of the young gen after the collection. 160 bool eden_empty; 161 bool survivors_empty; 162 bool young_gen_empty; 163 164 { 165 HandleMark hm; 166 167 GCTraceCPUTime tcpu; 168 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause, true); 169 170 heap->pre_full_gc_dump(_gc_timer); 171 172 TraceCollectorStats tcs(counters()); 173 TraceMemoryManagerStats tms(true /* Full GC */,gc_cause); 174 175 if (TraceOldGenTime) accumulated_time()->start(); 176 177 // Let the size policy know we're starting 178 size_policy->major_collection_begin(); 179 180 CodeCache::gc_prologue(); 181 BiasedLocking::preserve_marks(); 182 183 // Capture metadata size before collection for sizing. 184 size_t metadata_prev_used = MetaspaceAux::used_bytes(); 185 186 size_t old_gen_prev_used = old_gen->used_in_bytes(); 187 size_t young_gen_prev_used = young_gen->used_in_bytes(); 188 189 allocate_stacks(); 190 191 #if defined(COMPILER2) || INCLUDE_JVMCI 192 DerivedPointerTable::clear(); 193 #endif 194 195 ref_processor()->enable_discovery(); 196 ref_processor()->setup_policy(clear_all_softrefs); 197 198 mark_sweep_phase1(clear_all_softrefs); 199 200 mark_sweep_phase2(); 201 202 #if defined(COMPILER2) || INCLUDE_JVMCI 203 // Don't add any more derived pointers during phase3 204 assert(DerivedPointerTable::is_active(), "Sanity"); 205 DerivedPointerTable::set_active(false); 206 #endif 207 208 mark_sweep_phase3(); 209 210 mark_sweep_phase4(); 211 212 restore_marks(); 213 214 deallocate_stacks(); 215 216 if (ZapUnusedHeapArea) { 217 // Do a complete mangle (top to end) because the usage for 218 // scratch does not maintain a top pointer. 219 young_gen->to_space()->mangle_unused_area_complete(); 220 } 221 222 eden_empty = young_gen->eden_space()->is_empty(); 223 if (!eden_empty) { 224 eden_empty = absorb_live_data_from_eden(size_policy, young_gen, old_gen); 225 } 226 227 // Update heap occupancy information which is used as 228 // input to soft ref clearing policy at the next gc. 229 Universe::update_heap_info_at_gc(); 230 231 survivors_empty = young_gen->from_space()->is_empty() && 232 young_gen->to_space()->is_empty(); 233 young_gen_empty = eden_empty && survivors_empty; 234 235 ModRefBarrierSet* modBS = barrier_set_cast<ModRefBarrierSet>(heap->barrier_set()); 236 MemRegion old_mr = heap->old_gen()->reserved(); 237 if (young_gen_empty) { 238 modBS->clear(MemRegion(old_mr.start(), old_mr.end())); 239 } else { 240 modBS->invalidate(MemRegion(old_mr.start(), old_mr.end())); 241 } 242 243 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 244 ClassLoaderDataGraph::purge(); 245 MetaspaceAux::verify_metrics(); 246 247 BiasedLocking::restore_marks(); 248 CodeCache::gc_epilogue(); 249 JvmtiExport::gc_epilogue(); 250 251 #if defined(COMPILER2) || INCLUDE_JVMCI 252 DerivedPointerTable::update_pointers(); 253 #endif 254 255 ref_processor()->enqueue_discovered_references(NULL); 256 257 // Update time of last GC 258 reset_millis_since_last_gc(); 259 260 // Let the size policy know we're done 261 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause); 262 263 if (UseAdaptiveSizePolicy) { 264 265 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections()); 266 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT, 267 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes()); 268 269 // Don't check if the size_policy is ready here. Let 270 // the size_policy check that internally. 271 if (UseAdaptiveGenerationSizePolicyAtMajorCollection && 272 AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) { 273 // Swap the survivor spaces if from_space is empty. The 274 // resize_young_gen() called below is normally used after 275 // a successful young GC and swapping of survivor spaces; 276 // otherwise, it will fail to resize the young gen with 277 // the current implementation. 278 if (young_gen->from_space()->is_empty()) { 279 young_gen->from_space()->clear(SpaceDecorator::Mangle); 280 young_gen->swap_spaces(); 281 } 282 283 // Calculate optimal free space amounts 284 assert(young_gen->max_size() > 285 young_gen->from_space()->capacity_in_bytes() + 286 young_gen->to_space()->capacity_in_bytes(), 287 "Sizes of space in young gen are out-of-bounds"); 288 289 size_t young_live = young_gen->used_in_bytes(); 290 size_t eden_live = young_gen->eden_space()->used_in_bytes(); 291 size_t old_live = old_gen->used_in_bytes(); 292 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes(); 293 size_t max_old_gen_size = old_gen->max_gen_size(); 294 size_t max_eden_size = young_gen->max_size() - 295 young_gen->from_space()->capacity_in_bytes() - 296 young_gen->to_space()->capacity_in_bytes(); 297 298 // Used for diagnostics 299 size_policy->clear_generation_free_space_flags(); 300 301 size_policy->compute_generations_free_space(young_live, 302 eden_live, 303 old_live, 304 cur_eden, 305 max_old_gen_size, 306 max_eden_size, 307 true /* full gc*/); 308 309 size_policy->check_gc_overhead_limit(young_live, 310 eden_live, 311 max_old_gen_size, 312 max_eden_size, 313 true /* full gc*/, 314 gc_cause, 315 heap->collector_policy()); 316 317 size_policy->decay_supplemental_growth(true /* full gc*/); 318 319 heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes()); 320 321 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(), 322 size_policy->calculated_survivor_size_in_bytes()); 323 } 324 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections()); 325 } 326 327 if (UsePerfData) { 328 heap->gc_policy_counters()->update_counters(); 329 heap->gc_policy_counters()->update_old_capacity( 330 old_gen->capacity_in_bytes()); 331 heap->gc_policy_counters()->update_young_capacity( 332 young_gen->capacity_in_bytes()); 333 } 334 335 heap->resize_all_tlabs(); 336 337 // We collected the heap, recalculate the metaspace capacity 338 MetaspaceGC::compute_new_size(); 339 340 if (TraceOldGenTime) accumulated_time()->stop(); 341 342 young_gen->print_used_change(young_gen_prev_used); 343 old_gen->print_used_change(old_gen_prev_used); 344 MetaspaceAux::print_metaspace_change(metadata_prev_used); 345 346 // Track memory usage and detect low memory 347 MemoryService::track_memory_usage(); 348 heap->update_counters(); 349 350 heap->post_full_gc_dump(_gc_timer); 351 } 352 353 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) { 354 HandleMark hm; // Discard invalid handles created during verification 355 Universe::verify("After GC"); 356 } 357 358 // Re-verify object start arrays 359 if (VerifyObjectStartArray && 360 VerifyAfterGC) { 361 old_gen->verify_object_start_array(); 362 } 363 364 if (ZapUnusedHeapArea) { 365 old_gen->object_space()->check_mangled_unused_area_complete(); 366 } 367 368 NOT_PRODUCT(ref_processor()->verify_no_references_recorded()); 369 370 heap->print_heap_after_gc(); 371 heap->trace_heap_after_gc(_gc_tracer); 372 373 #ifdef TRACESPINNING 374 ParallelTaskTerminator::print_termination_counts(); 375 #endif 376 377 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections()); 378 379 _gc_timer->register_gc_end(); 380 381 _gc_tracer->report_gc_end(_gc_timer->gc_end(), _gc_timer->time_partitions()); 382 383 return true; 384 } 385 386 bool PSMarkSweep::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy, 387 PSYoungGen* young_gen, 388 PSOldGen* old_gen) { 389 MutableSpace* const eden_space = young_gen->eden_space(); 390 assert(!eden_space->is_empty(), "eden must be non-empty"); 391 assert(young_gen->virtual_space()->alignment() == 392 old_gen->virtual_space()->alignment(), "alignments do not match"); 393 394 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) { 395 return false; 396 } 397 398 // Both generations must be completely committed. 399 if (young_gen->virtual_space()->uncommitted_size() != 0) { 400 return false; 401 } 402 if (old_gen->virtual_space()->uncommitted_size() != 0) { 403 return false; 404 } 405 406 // Figure out how much to take from eden. Include the average amount promoted 407 // in the total; otherwise the next young gen GC will simply bail out to a 408 // full GC. 409 const size_t alignment = old_gen->virtual_space()->alignment(); 410 const size_t eden_used = eden_space->used_in_bytes(); 411 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average(); 412 const size_t absorb_size = align_size_up(eden_used + promoted, alignment); 413 const size_t eden_capacity = eden_space->capacity_in_bytes(); 414 415 if (absorb_size >= eden_capacity) { 416 return false; // Must leave some space in eden. 417 } 418 419 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size; 420 if (new_young_size < young_gen->min_gen_size()) { 421 return false; // Respect young gen minimum size. 422 } 423 424 log_trace(heap, ergo)(" absorbing " SIZE_FORMAT "K: " 425 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K " 426 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K " 427 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ", 428 absorb_size / K, 429 eden_capacity / K, (eden_capacity - absorb_size) / K, 430 young_gen->from_space()->used_in_bytes() / K, 431 young_gen->to_space()->used_in_bytes() / K, 432 young_gen->capacity_in_bytes() / K, new_young_size / K); 433 434 // Fill the unused part of the old gen. 435 MutableSpace* const old_space = old_gen->object_space(); 436 HeapWord* const unused_start = old_space->top(); 437 size_t const unused_words = pointer_delta(old_space->end(), unused_start); 438 439 if (unused_words > 0) { 440 if (unused_words < CollectedHeap::min_fill_size()) { 441 return false; // If the old gen cannot be filled, must give up. 442 } 443 CollectedHeap::fill_with_objects(unused_start, unused_words); 444 } 445 446 // Take the live data from eden and set both top and end in the old gen to 447 // eden top. (Need to set end because reset_after_change() mangles the region 448 // from end to virtual_space->high() in debug builds). 449 HeapWord* const new_top = eden_space->top(); 450 old_gen->virtual_space()->expand_into(young_gen->virtual_space(), 451 absorb_size); 452 young_gen->reset_after_change(); 453 old_space->set_top(new_top); 454 old_space->set_end(new_top); 455 old_gen->reset_after_change(); 456 457 // Update the object start array for the filler object and the data from eden. 458 ObjectStartArray* const start_array = old_gen->start_array(); 459 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) { 460 start_array->allocate_block(p); 461 } 462 463 // Could update the promoted average here, but it is not typically updated at 464 // full GCs and the value to use is unclear. Something like 465 // 466 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc. 467 468 size_policy->set_bytes_absorbed_from_eden(absorb_size); 469 return true; 470 } 471 472 void PSMarkSweep::allocate_stacks() { 473 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 474 PSYoungGen* young_gen = heap->young_gen(); 475 476 MutableSpace* to_space = young_gen->to_space(); 477 _preserved_marks = (PreservedMark*)to_space->top(); 478 _preserved_count = 0; 479 480 // We want to calculate the size in bytes first. 481 _preserved_count_max = pointer_delta(to_space->end(), to_space->top(), sizeof(jbyte)); 482 // Now divide by the size of a PreservedMark 483 _preserved_count_max /= sizeof(PreservedMark); 484 } 485 486 487 void PSMarkSweep::deallocate_stacks() { 488 _preserved_mark_stack.clear(true); 489 _preserved_oop_stack.clear(true); 490 _marking_stack.clear(); 491 _objarray_stack.clear(true); 492 } 493 494 void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) { 495 // Recursively traverse all live objects and mark them 496 GCTraceTime(Info, gc, phases) tm("Phase 1: Mark live objects", _gc_timer); 497 498 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 499 500 // Need to clear claim bits before the tracing starts. 501 ClassLoaderDataGraph::clear_claimed_marks(); 502 503 // General strong roots. 504 { 505 ParallelScavengeHeap::ParStrongRootsScope psrs; 506 Universe::oops_do(mark_and_push_closure()); 507 JNIHandles::oops_do(mark_and_push_closure()); // Global (strong) JNI handles 508 MarkingCodeBlobClosure each_active_code_blob(mark_and_push_closure(), !CodeBlobToOopClosure::FixRelocations); 509 Threads::oops_do(mark_and_push_closure(), &each_active_code_blob); 510 ObjectSynchronizer::oops_do(mark_and_push_closure()); 511 FlatProfiler::oops_do(mark_and_push_closure()); 512 Management::oops_do(mark_and_push_closure()); 513 JvmtiExport::oops_do(mark_and_push_closure()); 514 SystemDictionary::always_strong_oops_do(mark_and_push_closure()); 515 ClassLoaderDataGraph::always_strong_cld_do(follow_cld_closure()); 516 // Do not treat nmethods as strong roots for mark/sweep, since we can unload them. 517 //CodeCache::scavenge_root_nmethods_do(CodeBlobToOopClosure(mark_and_push_closure())); 518 } 519 520 // Flush marking stack. 521 follow_stack(); 522 523 // Process reference objects found during marking 524 { 525 GCTraceTime(Debug, gc, phases) t("Reference Processing", _gc_timer); 526 527 ref_processor()->setup_policy(clear_all_softrefs); 528 const ReferenceProcessorStats& stats = 529 ref_processor()->process_discovered_references( 530 is_alive_closure(), mark_and_push_closure(), follow_stack_closure(), NULL, _gc_timer); 531 gc_tracer()->report_gc_reference_stats(stats); 532 } 533 534 // This is the point where the entire marking should have completed. 535 assert(_marking_stack.is_empty(), "Marking should have completed"); 536 537 if (ClassUnloading) { 538 GCTraceTime(Debug, gc, phases) t("Class Unloading", _gc_timer); 539 540 // Unload classes and purge the SystemDictionary. 541 bool purged_class = SystemDictionary::do_unloading(is_alive_closure()); 542 543 // Unload nmethods. 544 CodeCache::do_unloading(is_alive_closure(), purged_class); 545 546 // Prune dead klasses from subklass/sibling/implementor lists. 547 Klass::clean_weak_klass_links(is_alive_closure()); 548 } else { 549 // Unload nmethods. 550 GCTraceTime(Debug, gc, phases) t("NMethod Unloading", _gc_timer); 551 CodeCache::do_unloading(is_alive_closure(), false); 552 } 553 554 555 { 556 GCTraceTime(Debug, gc, phases) t("Scrub String Table", _gc_timer); 557 // Delete entries for dead interned strings. 558 StringTable::unlink(is_alive_closure()); 559 } 560 561 { 562 GCTraceTime(Debug, gc, phases) t("Scrub Symbol Table", _gc_timer); 563 // Clean up unreferenced symbols in symbol table. 564 SymbolTable::unlink(); 565 } 566 567 _gc_tracer->report_object_count_after_gc(is_alive_closure()); 568 } 569 570 571 void PSMarkSweep::mark_sweep_phase2() { 572 GCTraceTime(Info, gc, phases) tm("Phase 2: Compute new object addresses", _gc_timer); 573 574 // Now all live objects are marked, compute the new object addresses. 575 576 // It is not required that we traverse spaces in the same order in 577 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops 578 // tracking expects us to do so. See comment under phase4. 579 580 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 581 PSOldGen* old_gen = heap->old_gen(); 582 583 // Begin compacting into the old gen 584 PSMarkSweepDecorator::set_destination_decorator_tenured(); 585 586 // This will also compact the young gen spaces. 587 old_gen->precompact(); 588 } 589 590 void PSMarkSweep::mark_sweep_phase3() { 591 // Adjust the pointers to reflect the new locations 592 GCTraceTime(Info, gc, phases) tm("Phase 3: Adjust pointers", _gc_timer); 593 594 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 595 PSYoungGen* young_gen = heap->young_gen(); 596 PSOldGen* old_gen = heap->old_gen(); 597 598 // Need to clear claim bits before the tracing starts. 599 ClassLoaderDataGraph::clear_claimed_marks(); 600 601 // General strong roots. 602 Universe::oops_do(adjust_pointer_closure()); 603 JNIHandles::oops_do(adjust_pointer_closure()); // Global (strong) JNI handles 604 Threads::oops_do(adjust_pointer_closure(), NULL); 605 ObjectSynchronizer::oops_do(adjust_pointer_closure()); 606 FlatProfiler::oops_do(adjust_pointer_closure()); 607 Management::oops_do(adjust_pointer_closure()); 608 JvmtiExport::oops_do(adjust_pointer_closure()); 609 SystemDictionary::oops_do(adjust_pointer_closure()); 610 ClassLoaderDataGraph::cld_do(adjust_cld_closure()); 611 612 // Now adjust pointers in remaining weak roots. (All of which should 613 // have been cleared if they pointed to non-surviving objects.) 614 // Global (weak) JNI handles 615 JNIHandles::weak_oops_do(adjust_pointer_closure()); 616 617 CodeBlobToOopClosure adjust_from_blobs(adjust_pointer_closure(), CodeBlobToOopClosure::FixRelocations); 618 CodeCache::blobs_do(&adjust_from_blobs); 619 StringTable::oops_do(adjust_pointer_closure()); 620 ref_processor()->weak_oops_do(adjust_pointer_closure()); 621 PSScavenge::reference_processor()->weak_oops_do(adjust_pointer_closure()); 622 623 adjust_marks(); 624 625 young_gen->adjust_pointers(); 626 old_gen->adjust_pointers(); 627 } 628 629 void PSMarkSweep::mark_sweep_phase4() { 630 EventMark m("4 compact heap"); 631 GCTraceTime(Info, gc, phases) tm("Phase 4: Move objects", _gc_timer); 632 633 // All pointers are now adjusted, move objects accordingly 634 635 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 636 PSYoungGen* young_gen = heap->young_gen(); 637 PSOldGen* old_gen = heap->old_gen(); 638 639 old_gen->compact(); 640 young_gen->compact(); 641 } 642 643 jlong PSMarkSweep::millis_since_last_gc() { 644 // We need a monotonically non-decreasing time in ms but 645 // os::javaTimeMillis() does not guarantee monotonicity. 646 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 647 jlong ret_val = now - _time_of_last_gc; 648 // XXX See note in genCollectedHeap::millis_since_last_gc(). 649 if (ret_val < 0) { 650 NOT_PRODUCT(log_warning(gc)("time warp: " JLONG_FORMAT, ret_val);) 651 return 0; 652 } 653 return ret_val; 654 } 655 656 void PSMarkSweep::reset_millis_since_last_gc() { 657 // We need a monotonically non-decreasing time in ms but 658 // os::javaTimeMillis() does not guarantee monotonicity. 659 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 660 }