1 /* 2 * Copyright (c) 2001, 2011, 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/symbolTable.hpp" 27 #include "classfile/systemDictionary.hpp" 28 #include "code/codeCache.hpp" 29 #include "gc_implementation/parallelScavenge/generationSizer.hpp" 30 #include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp" 31 #include "gc_implementation/parallelScavenge/psAdaptiveSizePolicy.hpp" 32 #include "gc_implementation/parallelScavenge/psMarkSweep.hpp" 33 #include "gc_implementation/parallelScavenge/psMarkSweepDecorator.hpp" 34 #include "gc_implementation/parallelScavenge/psOldGen.hpp" 35 #include "gc_implementation/parallelScavenge/psPermGen.hpp" 36 #include "gc_implementation/parallelScavenge/psScavenge.hpp" 37 #include "gc_implementation/parallelScavenge/psYoungGen.hpp" 38 #include "gc_implementation/shared/isGCActiveMark.hpp" 39 #include "gc_implementation/shared/spaceDecorator.hpp" 40 #include "gc_interface/gcCause.hpp" 41 #include "memory/gcLocker.inline.hpp" 42 #include "memory/referencePolicy.hpp" 43 #include "memory/referenceProcessor.hpp" 44 #include "oops/oop.inline.hpp" 45 #include "runtime/biasedLocking.hpp" 46 #include "runtime/fprofiler.hpp" 47 #include "runtime/safepoint.hpp" 48 #include "runtime/vmThread.hpp" 49 #include "services/management.hpp" 50 #include "services/memoryService.hpp" 51 #include "utilities/events.hpp" 52 #include "utilities/stack.inline.hpp" 53 54 elapsedTimer PSMarkSweep::_accumulated_time; 55 unsigned int PSMarkSweep::_total_invocations = 0; 56 jlong PSMarkSweep::_time_of_last_gc = 0; 57 CollectorCounters* PSMarkSweep::_counters = NULL; 58 59 void PSMarkSweep::initialize() { 60 MemRegion mr = Universe::heap()->reserved_region(); 61 _ref_processor = new ReferenceProcessor(mr); // a vanilla ref proc 62 _counters = new CollectorCounters("PSMarkSweep", 1); 63 } 64 65 // This method contains all heap specific policy for invoking mark sweep. 66 // PSMarkSweep::invoke_no_policy() will only attempt to mark-sweep-compact 67 // the heap. It will do nothing further. If we need to bail out for policy 68 // reasons, scavenge before full gc, or any other specialized behavior, it 69 // needs to be added here. 70 // 71 // Note that this method should only be called from the vm_thread while 72 // at a safepoint! 73 // 74 // Note that the all_soft_refs_clear flag in the collector policy 75 // may be true because this method can be called without intervening 76 // activity. For example when the heap space is tight and full measure 77 // are being taken to free space. 78 79 void PSMarkSweep::invoke(bool maximum_heap_compaction) { 80 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 81 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread"); 82 assert(!Universe::heap()->is_gc_active(), "not reentrant"); 83 84 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 85 GCCause::Cause gc_cause = heap->gc_cause(); 86 PSAdaptiveSizePolicy* policy = heap->size_policy(); 87 IsGCActiveMark mark; 88 89 if (ScavengeBeforeFullGC) { 90 PSScavenge::invoke_no_policy(); 91 } 92 93 const bool clear_all_soft_refs = 94 heap->collector_policy()->should_clear_all_soft_refs(); 95 96 int count = (maximum_heap_compaction)?1:MarkSweepAlwaysCompactCount; 97 IntFlagSetting flag_setting(MarkSweepAlwaysCompactCount, count); 98 PSMarkSweep::invoke_no_policy(clear_all_soft_refs || maximum_heap_compaction); 99 } 100 101 // This method contains no policy. You should probably 102 // be calling invoke() instead. 103 void PSMarkSweep::invoke_no_policy(bool clear_all_softrefs) { 104 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint"); 105 assert(ref_processor() != NULL, "Sanity"); 106 107 if (GC_locker::check_active_before_gc()) { 108 return; 109 } 110 111 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 112 GCCause::Cause gc_cause = heap->gc_cause(); 113 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 114 PSAdaptiveSizePolicy* size_policy = heap->size_policy(); 115 116 // The scope of casr should end after code that can change 117 // CollectorPolicy::_should_clear_all_soft_refs. 118 ClearedAllSoftRefs casr(clear_all_softrefs, heap->collector_policy()); 119 120 PSYoungGen* young_gen = heap->young_gen(); 121 PSOldGen* old_gen = heap->old_gen(); 122 PSPermGen* perm_gen = heap->perm_gen(); 123 124 // Increment the invocation count 125 heap->increment_total_collections(true /* full */); 126 127 // Save information needed to minimize mangling 128 heap->record_gen_tops_before_GC(); 129 130 // We need to track unique mark sweep invocations as well. 131 _total_invocations++; 132 133 AdaptiveSizePolicyOutput(size_policy, heap->total_collections()); 134 135 if (PrintHeapAtGC) { 136 Universe::print_heap_before_gc(); 137 } 138 139 // Fill in TLABs 140 heap->accumulate_statistics_all_tlabs(); 141 heap->ensure_parsability(true); // retire TLABs 142 143 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) { 144 HandleMark hm; // Discard invalid handles created during verification 145 gclog_or_tty->print(" VerifyBeforeGC:"); 146 Universe::verify(true); 147 } 148 149 // Verify object start arrays 150 if (VerifyObjectStartArray && 151 VerifyBeforeGC) { 152 old_gen->verify_object_start_array(); 153 perm_gen->verify_object_start_array(); 154 } 155 156 heap->pre_full_gc_dump(); 157 158 // Filled in below to track the state of the young gen after the collection. 159 bool eden_empty; 160 bool survivors_empty; 161 bool young_gen_empty; 162 163 { 164 HandleMark hm; 165 const bool is_system_gc = gc_cause == GCCause::_java_lang_system_gc; 166 // This is useful for debugging but don't change the output the 167 // the customer sees. 168 const char* gc_cause_str = "Full GC"; 169 if (is_system_gc && PrintGCDetails) { 170 gc_cause_str = "Full GC (System)"; 171 } 172 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps); 173 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); 174 TraceTime t1(gc_cause_str, PrintGC, !PrintGCDetails, gclog_or_tty); 175 TraceCollectorStats tcs(counters()); 176 TraceMemoryManagerStats tms(true /* Full GC */,gc_cause); 177 178 if (TraceGen1Time) accumulated_time()->start(); 179 180 // Let the size policy know we're starting 181 size_policy->major_collection_begin(); 182 183 // When collecting the permanent generation methodOops may be moving, 184 // so we either have to flush all bcp data or convert it into bci. 185 CodeCache::gc_prologue(); 186 Threads::gc_prologue(); 187 BiasedLocking::preserve_marks(); 188 189 // Capture heap size before collection for printing. 190 size_t prev_used = heap->used(); 191 192 // Capture perm gen size before collection for sizing. 193 size_t perm_gen_prev_used = perm_gen->used_in_bytes(); 194 195 // For PrintGCDetails 196 size_t old_gen_prev_used = old_gen->used_in_bytes(); 197 size_t young_gen_prev_used = young_gen->used_in_bytes(); 198 199 allocate_stacks(); 200 201 COMPILER2_PRESENT(DerivedPointerTable::clear()); 202 203 ref_processor()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/); 204 ref_processor()->setup_policy(clear_all_softrefs); 205 206 mark_sweep_phase1(clear_all_softrefs); 207 208 mark_sweep_phase2(); 209 210 // Don't add any more derived pointers during phase3 211 COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity")); 212 COMPILER2_PRESENT(DerivedPointerTable::set_active(false)); 213 214 mark_sweep_phase3(); 215 216 mark_sweep_phase4(); 217 218 restore_marks(); 219 220 deallocate_stacks(); 221 222 if (ZapUnusedHeapArea) { 223 // Do a complete mangle (top to end) because the usage for 224 // scratch does not maintain a top pointer. 225 young_gen->to_space()->mangle_unused_area_complete(); 226 } 227 228 eden_empty = young_gen->eden_space()->is_empty(); 229 if (!eden_empty) { 230 eden_empty = absorb_live_data_from_eden(size_policy, young_gen, old_gen); 231 } 232 233 // Update heap occupancy information which is used as 234 // input to soft ref clearing policy at the next gc. 235 Universe::update_heap_info_at_gc(); 236 237 survivors_empty = young_gen->from_space()->is_empty() && 238 young_gen->to_space()->is_empty(); 239 young_gen_empty = eden_empty && survivors_empty; 240 241 BarrierSet* bs = heap->barrier_set(); 242 if (bs->is_a(BarrierSet::ModRef)) { 243 ModRefBarrierSet* modBS = (ModRefBarrierSet*)bs; 244 MemRegion old_mr = heap->old_gen()->reserved(); 245 MemRegion perm_mr = heap->perm_gen()->reserved(); 246 assert(perm_mr.end() <= old_mr.start(), "Generations out of order"); 247 248 if (young_gen_empty) { 249 modBS->clear(MemRegion(perm_mr.start(), old_mr.end())); 250 } else { 251 modBS->invalidate(MemRegion(perm_mr.start(), old_mr.end())); 252 } 253 } 254 255 BiasedLocking::restore_marks(); 256 Threads::gc_epilogue(); 257 CodeCache::gc_epilogue(); 258 JvmtiExport::gc_epilogue(); 259 260 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 261 262 ref_processor()->enqueue_discovered_references(NULL); 263 264 // Update time of last GC 265 reset_millis_since_last_gc(); 266 267 // Let the size policy know we're done 268 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause); 269 270 if (UseAdaptiveSizePolicy) { 271 272 if (PrintAdaptiveSizePolicy) { 273 gclog_or_tty->print("AdaptiveSizeStart: "); 274 gclog_or_tty->stamp(); 275 gclog_or_tty->print_cr(" collection: %d ", 276 heap->total_collections()); 277 if (Verbose) { 278 gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d" 279 " perm_gen_capacity: %d ", 280 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes(), 281 perm_gen->capacity_in_bytes()); 282 } 283 } 284 285 // Don't check if the size_policy is ready here. Let 286 // the size_policy check that internally. 287 if (UseAdaptiveGenerationSizePolicyAtMajorCollection && 288 ((gc_cause != GCCause::_java_lang_system_gc) || 289 UseAdaptiveSizePolicyWithSystemGC)) { 290 // Calculate optimal free space amounts 291 assert(young_gen->max_size() > 292 young_gen->from_space()->capacity_in_bytes() + 293 young_gen->to_space()->capacity_in_bytes(), 294 "Sizes of space in young gen are out-of-bounds"); 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 size_policy->compute_generation_free_space(young_gen->used_in_bytes(), 299 young_gen->eden_space()->used_in_bytes(), 300 old_gen->used_in_bytes(), 301 perm_gen->used_in_bytes(), 302 young_gen->eden_space()->capacity_in_bytes(), 303 old_gen->max_gen_size(), 304 max_eden_size, 305 true /* full gc*/, 306 gc_cause, 307 heap->collector_policy()); 308 309 heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes()); 310 311 // Don't resize the young generation at an major collection. A 312 // desired young generation size may have been calculated but 313 // resizing the young generation complicates the code because the 314 // resizing of the old generation may have moved the boundary 315 // between the young generation and the old generation. Let the 316 // young generation resizing happen at the minor collections. 317 } 318 if (PrintAdaptiveSizePolicy) { 319 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ", 320 heap->total_collections()); 321 } 322 } 323 324 if (UsePerfData) { 325 heap->gc_policy_counters()->update_counters(); 326 heap->gc_policy_counters()->update_old_capacity( 327 old_gen->capacity_in_bytes()); 328 heap->gc_policy_counters()->update_young_capacity( 329 young_gen->capacity_in_bytes()); 330 } 331 332 heap->resize_all_tlabs(); 333 334 // We collected the perm gen, so we'll resize it here. 335 perm_gen->compute_new_size(perm_gen_prev_used); 336 337 if (TraceGen1Time) accumulated_time()->stop(); 338 339 if (PrintGC) { 340 if (PrintGCDetails) { 341 // Don't print a GC timestamp here. This is after the GC so 342 // would be confusing. 343 young_gen->print_used_change(young_gen_prev_used); 344 old_gen->print_used_change(old_gen_prev_used); 345 } 346 heap->print_heap_change(prev_used); 347 // Do perm gen after heap becase prev_used does 348 // not include the perm gen (done this way in the other 349 // collectors). 350 if (PrintGCDetails) { 351 perm_gen->print_used_change(perm_gen_prev_used); 352 } 353 } 354 355 // Track memory usage and detect low memory 356 MemoryService::track_memory_usage(); 357 heap->update_counters(); 358 } 359 360 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) { 361 HandleMark hm; // Discard invalid handles created during verification 362 gclog_or_tty->print(" VerifyAfterGC:"); 363 Universe::verify(false); 364 } 365 366 // Re-verify object start arrays 367 if (VerifyObjectStartArray && 368 VerifyAfterGC) { 369 old_gen->verify_object_start_array(); 370 perm_gen->verify_object_start_array(); 371 } 372 373 if (ZapUnusedHeapArea) { 374 old_gen->object_space()->check_mangled_unused_area_complete(); 375 perm_gen->object_space()->check_mangled_unused_area_complete(); 376 } 377 378 NOT_PRODUCT(ref_processor()->verify_no_references_recorded()); 379 380 if (PrintHeapAtGC) { 381 Universe::print_heap_after_gc(); 382 } 383 384 heap->post_full_gc_dump(); 385 386 #ifdef TRACESPINNING 387 ParallelTaskTerminator::print_termination_counts(); 388 #endif 389 } 390 391 bool PSMarkSweep::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy, 392 PSYoungGen* young_gen, 393 PSOldGen* old_gen) { 394 MutableSpace* const eden_space = young_gen->eden_space(); 395 assert(!eden_space->is_empty(), "eden must be non-empty"); 396 assert(young_gen->virtual_space()->alignment() == 397 old_gen->virtual_space()->alignment(), "alignments do not match"); 398 399 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) { 400 return false; 401 } 402 403 // Both generations must be completely committed. 404 if (young_gen->virtual_space()->uncommitted_size() != 0) { 405 return false; 406 } 407 if (old_gen->virtual_space()->uncommitted_size() != 0) { 408 return false; 409 } 410 411 // Figure out how much to take from eden. Include the average amount promoted 412 // in the total; otherwise the next young gen GC will simply bail out to a 413 // full GC. 414 const size_t alignment = old_gen->virtual_space()->alignment(); 415 const size_t eden_used = eden_space->used_in_bytes(); 416 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average(); 417 const size_t absorb_size = align_size_up(eden_used + promoted, alignment); 418 const size_t eden_capacity = eden_space->capacity_in_bytes(); 419 420 if (absorb_size >= eden_capacity) { 421 return false; // Must leave some space in eden. 422 } 423 424 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size; 425 if (new_young_size < young_gen->min_gen_size()) { 426 return false; // Respect young gen minimum size. 427 } 428 429 if (TraceAdaptiveGCBoundary && Verbose) { 430 gclog_or_tty->print(" absorbing " SIZE_FORMAT "K: " 431 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K " 432 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K " 433 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ", 434 absorb_size / K, 435 eden_capacity / K, (eden_capacity - absorb_size) / K, 436 young_gen->from_space()->used_in_bytes() / K, 437 young_gen->to_space()->used_in_bytes() / K, 438 young_gen->capacity_in_bytes() / K, new_young_size / K); 439 } 440 441 // Fill the unused part of the old gen. 442 MutableSpace* const old_space = old_gen->object_space(); 443 HeapWord* const unused_start = old_space->top(); 444 size_t const unused_words = pointer_delta(old_space->end(), unused_start); 445 446 if (unused_words > 0) { 447 if (unused_words < CollectedHeap::min_fill_size()) { 448 return false; // If the old gen cannot be filled, must give up. 449 } 450 CollectedHeap::fill_with_objects(unused_start, unused_words); 451 } 452 453 // Take the live data from eden and set both top and end in the old gen to 454 // eden top. (Need to set end because reset_after_change() mangles the region 455 // from end to virtual_space->high() in debug builds). 456 HeapWord* const new_top = eden_space->top(); 457 old_gen->virtual_space()->expand_into(young_gen->virtual_space(), 458 absorb_size); 459 young_gen->reset_after_change(); 460 old_space->set_top(new_top); 461 old_space->set_end(new_top); 462 old_gen->reset_after_change(); 463 464 // Update the object start array for the filler object and the data from eden. 465 ObjectStartArray* const start_array = old_gen->start_array(); 466 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) { 467 start_array->allocate_block(p); 468 } 469 470 // Could update the promoted average here, but it is not typically updated at 471 // full GCs and the value to use is unclear. Something like 472 // 473 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc. 474 475 size_policy->set_bytes_absorbed_from_eden(absorb_size); 476 return true; 477 } 478 479 void PSMarkSweep::allocate_stacks() { 480 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 481 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 482 483 PSYoungGen* young_gen = heap->young_gen(); 484 485 MutableSpace* to_space = young_gen->to_space(); 486 _preserved_marks = (PreservedMark*)to_space->top(); 487 _preserved_count = 0; 488 489 // We want to calculate the size in bytes first. 490 _preserved_count_max = pointer_delta(to_space->end(), to_space->top(), sizeof(jbyte)); 491 // Now divide by the size of a PreservedMark 492 _preserved_count_max /= sizeof(PreservedMark); 493 } 494 495 496 void PSMarkSweep::deallocate_stacks() { 497 _preserved_mark_stack.clear(true); 498 _preserved_oop_stack.clear(true); 499 _marking_stack.clear(); 500 _objarray_stack.clear(true); 501 _revisit_klass_stack.clear(true); 502 _revisit_mdo_stack.clear(true); 503 } 504 505 void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) { 506 // Recursively traverse all live objects and mark them 507 EventMark m("1 mark object"); 508 TraceTime tm("phase 1", PrintGCDetails && Verbose, true, gclog_or_tty); 509 trace(" 1"); 510 511 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 512 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 513 514 // General strong roots. 515 { 516 ParallelScavengeHeap::ParStrongRootsScope psrs; 517 Universe::oops_do(mark_and_push_closure()); 518 JNIHandles::oops_do(mark_and_push_closure()); // Global (strong) JNI handles 519 CodeBlobToOopClosure each_active_code_blob(mark_and_push_closure(), /*do_marking=*/ true); 520 Threads::oops_do(mark_and_push_closure(), &each_active_code_blob); 521 ObjectSynchronizer::oops_do(mark_and_push_closure()); 522 FlatProfiler::oops_do(mark_and_push_closure()); 523 Management::oops_do(mark_and_push_closure()); 524 JvmtiExport::oops_do(mark_and_push_closure()); 525 SystemDictionary::always_strong_oops_do(mark_and_push_closure()); 526 // Do not treat nmethods as strong roots for mark/sweep, since we can unload them. 527 //CodeCache::scavenge_root_nmethods_do(CodeBlobToOopClosure(mark_and_push_closure())); 528 } 529 530 // Flush marking stack. 531 follow_stack(); 532 533 // Process reference objects found during marking 534 { 535 ref_processor()->setup_policy(clear_all_softrefs); 536 ref_processor()->process_discovered_references( 537 is_alive_closure(), mark_and_push_closure(), follow_stack_closure(), NULL); 538 } 539 540 // Follow system dictionary roots and unload classes 541 bool purged_class = SystemDictionary::do_unloading(is_alive_closure()); 542 543 // Follow code cache roots 544 CodeCache::do_unloading(is_alive_closure(), mark_and_push_closure(), 545 purged_class); 546 follow_stack(); // Flush marking stack 547 548 // Update subklass/sibling/implementor links of live klasses 549 follow_weak_klass_links(); 550 assert(_marking_stack.is_empty(), "just drained"); 551 552 // Visit memoized mdo's and clear unmarked weak refs 553 follow_mdo_weak_refs(); 554 assert(_marking_stack.is_empty(), "just drained"); 555 556 // Visit interned string tables and delete unmarked oops 557 StringTable::unlink(is_alive_closure()); 558 // Clean up unreferenced symbols in symbol table. 559 SymbolTable::unlink(); 560 561 assert(_marking_stack.is_empty(), "stack should be empty by now"); 562 } 563 564 565 void PSMarkSweep::mark_sweep_phase2() { 566 EventMark m("2 compute new addresses"); 567 TraceTime tm("phase 2", PrintGCDetails && Verbose, true, gclog_or_tty); 568 trace("2"); 569 570 // Now all live objects are marked, compute the new object addresses. 571 572 // It is imperative that we traverse perm_gen LAST. If dead space is 573 // allowed a range of dead object may get overwritten by a dead int 574 // array. If perm_gen is not traversed last a klassOop may get 575 // overwritten. This is fine since it is dead, but if the class has dead 576 // instances we have to skip them, and in order to find their size we 577 // need the klassOop! 578 // 579 // It is not required that we traverse spaces in the same order in 580 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops 581 // tracking expects us to do so. See comment under phase4. 582 583 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 584 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 585 586 PSOldGen* old_gen = heap->old_gen(); 587 PSPermGen* perm_gen = heap->perm_gen(); 588 589 // Begin compacting into the old gen 590 PSMarkSweepDecorator::set_destination_decorator_tenured(); 591 592 // This will also compact the young gen spaces. 593 old_gen->precompact(); 594 595 // Compact the perm gen into the perm gen 596 PSMarkSweepDecorator::set_destination_decorator_perm_gen(); 597 598 perm_gen->precompact(); 599 } 600 601 // This should be moved to the shared markSweep code! 602 class PSAlwaysTrueClosure: public BoolObjectClosure { 603 public: 604 void do_object(oop p) { ShouldNotReachHere(); } 605 bool do_object_b(oop p) { return true; } 606 }; 607 static PSAlwaysTrueClosure always_true; 608 609 void PSMarkSweep::mark_sweep_phase3() { 610 // Adjust the pointers to reflect the new locations 611 EventMark m("3 adjust pointers"); 612 TraceTime tm("phase 3", PrintGCDetails && Verbose, true, gclog_or_tty); 613 trace("3"); 614 615 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 616 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 617 618 PSYoungGen* young_gen = heap->young_gen(); 619 PSOldGen* old_gen = heap->old_gen(); 620 PSPermGen* perm_gen = heap->perm_gen(); 621 622 // General strong roots. 623 Universe::oops_do(adjust_root_pointer_closure()); 624 JNIHandles::oops_do(adjust_root_pointer_closure()); // Global (strong) JNI handles 625 Threads::oops_do(adjust_root_pointer_closure(), NULL); 626 ObjectSynchronizer::oops_do(adjust_root_pointer_closure()); 627 FlatProfiler::oops_do(adjust_root_pointer_closure()); 628 Management::oops_do(adjust_root_pointer_closure()); 629 JvmtiExport::oops_do(adjust_root_pointer_closure()); 630 // SO_AllClasses 631 SystemDictionary::oops_do(adjust_root_pointer_closure()); 632 //CodeCache::scavenge_root_nmethods_oops_do(adjust_root_pointer_closure()); 633 634 // Now adjust pointers in remaining weak roots. (All of which should 635 // have been cleared if they pointed to non-surviving objects.) 636 // Global (weak) JNI handles 637 JNIHandles::weak_oops_do(&always_true, adjust_root_pointer_closure()); 638 639 CodeCache::oops_do(adjust_pointer_closure()); 640 StringTable::oops_do(adjust_root_pointer_closure()); 641 ref_processor()->weak_oops_do(adjust_root_pointer_closure()); 642 PSScavenge::reference_processor()->weak_oops_do(adjust_root_pointer_closure()); 643 644 adjust_marks(); 645 646 young_gen->adjust_pointers(); 647 old_gen->adjust_pointers(); 648 perm_gen->adjust_pointers(); 649 } 650 651 void PSMarkSweep::mark_sweep_phase4() { 652 EventMark m("4 compact heap"); 653 TraceTime tm("phase 4", PrintGCDetails && Verbose, true, gclog_or_tty); 654 trace("4"); 655 656 // All pointers are now adjusted, move objects accordingly 657 658 // It is imperative that we traverse perm_gen first in phase4. All 659 // classes must be allocated earlier than their instances, and traversing 660 // perm_gen first makes sure that all klassOops have moved to their new 661 // location before any instance does a dispatch through it's klass! 662 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 663 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 664 665 PSYoungGen* young_gen = heap->young_gen(); 666 PSOldGen* old_gen = heap->old_gen(); 667 PSPermGen* perm_gen = heap->perm_gen(); 668 669 perm_gen->compact(); 670 old_gen->compact(); 671 young_gen->compact(); 672 } 673 674 jlong PSMarkSweep::millis_since_last_gc() { 675 // We need a montonically increasing time in ms but os::javaTimeMillis() 676 // does not guarantee montonicity. 677 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 678 jlong ret_val = now - _time_of_last_gc; 679 // XXX See note in genCollectedHeap::millis_since_last_gc(). 680 if (ret_val < 0) { 681 NOT_PRODUCT(warning("time warp: "INT64_FORMAT, ret_val);) 682 return 0; 683 } 684 return ret_val; 685 } 686 687 void PSMarkSweep::reset_millis_since_last_gc() { 688 // We need a montonically increasing time in ms but os::javaTimeMillis() 689 // does not guarantee montonicity. 690 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 691 }