1 #ifdef USE_PRAGMA_IDENT_SRC 2 #pragma ident "@(#)psMarkSweep.cpp 1.92 07/06/08 23:11:01 JVM" 3 #endif 4 /* 5 * Copyright 2001-2007 Sun Microsystems, Inc. All Rights Reserved. 6 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 7 * 8 * This code is free software; you can redistribute it and/or modify it 9 * under the terms of the GNU General Public License version 2 only, as 10 * published by the Free Software Foundation. 11 * 12 * This code is distributed in the hope that it will be useful, but WITHOUT 13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 15 * version 2 for more details (a copy is included in the LICENSE file that 16 * accompanied this code). 17 * 18 * You should have received a copy of the GNU General Public License version 19 * 2 along with this work; if not, write to the Free Software Foundation, 20 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 21 * 22 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, 23 * CA 95054 USA or visit www.sun.com if you need additional information or 24 * have any questions. 25 * 26 */ 27 28 #include "incls/_precompiled.incl" 29 #include "incls/_psMarkSweep.cpp.incl" 30 31 elapsedTimer PSMarkSweep::_accumulated_time; 32 unsigned int PSMarkSweep::_total_invocations = 0; 33 jlong PSMarkSweep::_time_of_last_gc = 0; 34 CollectorCounters* PSMarkSweep::_counters = NULL; 35 36 void PSMarkSweep::initialize() { 37 MemRegion mr = Universe::heap()->reserved_region(); 38 _ref_processor = new ReferenceProcessor(mr, 39 true, // atomic_discovery 40 false); // mt_discovery 41 if (!UseParallelOldGC || !VerifyParallelOldWithMarkSweep) { 42 _counters = new CollectorCounters("PSMarkSweep", 1); 43 } 44 } 45 46 // This method contains all heap specific policy for invoking mark sweep. 47 // PSMarkSweep::invoke_no_policy() will only attempt to mark-sweep-compact 48 // the heap. It will do nothing further. If we need to bail out for policy 49 // reasons, scavenge before full gc, or any other specialized behavior, it 50 // needs to be added here. 51 // 52 // Note that this method should only be called from the vm_thread while 53 // at a safepoint! 54 void PSMarkSweep::invoke(bool maximum_heap_compaction) { 55 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 56 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread"); 57 assert(!Universe::heap()->is_gc_active(), "not reentrant"); 58 59 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 60 GCCause::Cause gc_cause = heap->gc_cause(); 61 PSAdaptiveSizePolicy* policy = heap->size_policy(); 62 63 // Before each allocation/collection attempt, find out from the 64 // policy object if GCs are, on the whole, taking too long. If so, 65 // bail out without attempting a collection. The exceptions are 66 // for explicitly requested GC's. 67 if (!policy->gc_time_limit_exceeded() || 68 GCCause::is_user_requested_gc(gc_cause) || 69 GCCause::is_serviceability_requested_gc(gc_cause)) { 70 IsGCActiveMark mark; 71 72 if (ScavengeBeforeFullGC) { 73 PSScavenge::invoke_no_policy(); 74 } 75 76 int count = (maximum_heap_compaction)?1:MarkSweepAlwaysCompactCount; 77 IntFlagSetting flag_setting(MarkSweepAlwaysCompactCount, count); 78 PSMarkSweep::invoke_no_policy(maximum_heap_compaction); 79 } 80 } 81 82 // This method contains no policy. You should probably 83 // be calling invoke() instead. 84 void PSMarkSweep::invoke_no_policy(bool clear_all_softrefs) { 85 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint"); 86 assert(ref_processor() != NULL, "Sanity"); 87 88 if (GC_locker::check_active_before_gc()) { 89 return; 90 } 91 92 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 93 GCCause::Cause gc_cause = heap->gc_cause(); 94 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 95 PSAdaptiveSizePolicy* size_policy = heap->size_policy(); 96 97 PSYoungGen* young_gen = heap->young_gen(); 98 PSOldGen* old_gen = heap->old_gen(); 99 PSPermGen* perm_gen = heap->perm_gen(); 100 101 // Increment the invocation count 102 heap->increment_total_collections(true /* full */); 103 104 // We need to track unique mark sweep invocations as well. 105 _total_invocations++; 106 107 AdaptiveSizePolicyOutput(size_policy, heap->total_collections()); 108 109 if (PrintHeapAtGC) { 110 Universe::print_heap_before_gc(); 111 } 112 113 // Fill in TLABs 114 heap->accumulate_statistics_all_tlabs(); 115 heap->ensure_parsability(true); // retire TLABs 116 117 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) { 118 HandleMark hm; // Discard invalid handles created during verification 119 gclog_or_tty->print(" VerifyBeforeGC:"); 120 Universe::verify(true); 121 } 122 123 // Verify object start arrays 124 if (VerifyObjectStartArray && 125 VerifyBeforeGC) { 126 old_gen->verify_object_start_array(); 127 perm_gen->verify_object_start_array(); 128 } 129 130 // Filled in below to track the state of the young gen after the collection. 131 bool eden_empty; 132 bool survivors_empty; 133 bool young_gen_empty; 134 135 { 136 HandleMark hm; 137 const bool is_system_gc = gc_cause == GCCause::_java_lang_system_gc; 138 // This is useful for debugging but don't change the output the 139 // the customer sees. 140 const char* gc_cause_str = "Full GC"; 141 if (is_system_gc && PrintGCDetails) { 142 gc_cause_str = "Full GC (System)"; 143 } 144 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps); 145 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); 146 TraceTime t1(gc_cause_str, PrintGC, !PrintGCDetails, gclog_or_tty); 147 TraceCollectorStats tcs(counters()); 148 TraceMemoryManagerStats tms(true /* Full GC */); 149 150 if (TraceGen1Time) accumulated_time()->start(); 151 152 // Let the size policy know we're starting 153 size_policy->major_collection_begin(); 154 155 // When collecting the permanent generation methodOops may be moving, 156 // so we either have to flush all bcp data or convert it into bci. 157 CodeCache::gc_prologue(); 158 Threads::gc_prologue(); 159 BiasedLocking::preserve_marks(); 160 161 // Capture heap size before collection for printing. 162 size_t prev_used = heap->used(); 163 164 // Capture perm gen size before collection for sizing. 165 size_t perm_gen_prev_used = perm_gen->used_in_bytes(); 166 167 // For PrintGCDetails 168 size_t old_gen_prev_used = old_gen->used_in_bytes(); 169 size_t young_gen_prev_used = young_gen->used_in_bytes(); 170 171 allocate_stacks(); 172 173 NOT_PRODUCT(ref_processor()->verify_no_references_recorded()); 174 COMPILER2_PRESENT(DerivedPointerTable::clear()); 175 176 ref_processor()->enable_discovery(); 177 178 mark_sweep_phase1(clear_all_softrefs); 179 180 mark_sweep_phase2(); 181 182 // Don't add any more derived pointers during phase3 183 COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity")); 184 COMPILER2_PRESENT(DerivedPointerTable::set_active(false)); 185 186 mark_sweep_phase3(); 187 188 mark_sweep_phase4(); 189 190 restore_marks(); 191 192 deallocate_stacks(); 193 194 eden_empty = young_gen->eden_space()->is_empty(); 195 if (!eden_empty) { 196 eden_empty = absorb_live_data_from_eden(size_policy, young_gen, old_gen); 197 } 198 199 // Update heap occupancy information which is used as 200 // input to soft ref clearing policy at the next gc. 201 Universe::update_heap_info_at_gc(); 202 203 survivors_empty = young_gen->from_space()->is_empty() && 204 young_gen->to_space()->is_empty(); 205 young_gen_empty = eden_empty && survivors_empty; 206 207 BarrierSet* bs = heap->barrier_set(); 208 if (bs->is_a(BarrierSet::ModRef)) { 209 ModRefBarrierSet* modBS = (ModRefBarrierSet*)bs; 210 MemRegion old_mr = heap->old_gen()->reserved(); 211 MemRegion perm_mr = heap->perm_gen()->reserved(); 212 assert(perm_mr.end() <= old_mr.start(), "Generations out of order"); 213 214 if (young_gen_empty) { 215 modBS->clear(MemRegion(perm_mr.start(), old_mr.end())); 216 } else { 217 modBS->invalidate(MemRegion(perm_mr.start(), old_mr.end())); 218 } 219 } 220 221 BiasedLocking::restore_marks(); 222 Threads::gc_epilogue(); 223 CodeCache::gc_epilogue(); 224 225 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 226 227 ref_processor()->enqueue_discovered_references(NULL); 228 229 // Update time of last GC 230 reset_millis_since_last_gc(); 231 232 // Let the size policy know we're done 233 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause); 234 235 if (UseAdaptiveSizePolicy) { 236 237 if (PrintAdaptiveSizePolicy) { 238 gclog_or_tty->print("AdaptiveSizeStart: "); 239 gclog_or_tty->stamp(); 240 gclog_or_tty->print_cr(" collection: %d ", 241 heap->total_collections()); 242 if (Verbose) { 243 gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d" 244 " perm_gen_capacity: %d ", 245 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes(), 246 perm_gen->capacity_in_bytes()); 247 } 248 } 249 250 // Don't check if the size_policy is ready here. Let 251 // the size_policy check that internally. 252 if (UseAdaptiveGenerationSizePolicyAtMajorCollection && 253 ((gc_cause != GCCause::_java_lang_system_gc) || 254 UseAdaptiveSizePolicyWithSystemGC)) { 255 // Calculate optimal free space amounts 256 assert(young_gen->max_size() > 257 young_gen->from_space()->capacity_in_bytes() + 258 young_gen->to_space()->capacity_in_bytes(), 259 "Sizes of space in young gen are out-of-bounds"); 260 size_t max_eden_size = young_gen->max_size() - 261 young_gen->from_space()->capacity_in_bytes() - 262 young_gen->to_space()->capacity_in_bytes(); 263 size_policy->compute_generation_free_space(young_gen->used_in_bytes(), 264 young_gen->eden_space()->used_in_bytes(), 265 old_gen->used_in_bytes(), 266 perm_gen->used_in_bytes(), 267 young_gen->eden_space()->capacity_in_bytes(), 268 old_gen->max_gen_size(), 269 max_eden_size, 270 true /* full gc*/, 271 gc_cause); 272 273 heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes()); 274 275 // Don't resize the young generation at an major collection. A 276 // desired young generation size may have been calculated but 277 // resizing the young generation complicates the code because the 278 // resizing of the old generation may have moved the boundary 279 // between the young generation and the old generation. Let the 280 // young generation resizing happen at the minor collections. 281 } 282 if (PrintAdaptiveSizePolicy) { 283 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ", 284 heap->total_collections()); 285 } 286 } 287 288 if (UsePerfData) { 289 heap->gc_policy_counters()->update_counters(); 290 heap->gc_policy_counters()->update_old_capacity( 291 old_gen->capacity_in_bytes()); 292 heap->gc_policy_counters()->update_young_capacity( 293 young_gen->capacity_in_bytes()); 294 } 295 296 heap->resize_all_tlabs(); 297 298 // We collected the perm gen, so we'll resize it here. 299 perm_gen->compute_new_size(perm_gen_prev_used); 300 301 if (TraceGen1Time) accumulated_time()->stop(); 302 303 if (PrintGC) { 304 if (PrintGCDetails) { 305 // Don't print a GC timestamp here. This is after the GC so 306 // would be confusing. 307 young_gen->print_used_change(young_gen_prev_used); 308 old_gen->print_used_change(old_gen_prev_used); 309 } 310 heap->print_heap_change(prev_used); 311 // Do perm gen after heap becase prev_used does 312 // not include the perm gen (done this way in the other 313 // collectors). 314 if (PrintGCDetails) { 315 perm_gen->print_used_change(perm_gen_prev_used); 316 } 317 } 318 319 // Track memory usage and detect low memory 320 MemoryService::track_memory_usage(); 321 heap->update_counters(); 322 323 if (PrintGCDetails) { 324 if (size_policy->print_gc_time_limit_would_be_exceeded()) { 325 if (size_policy->gc_time_limit_exceeded()) { 326 gclog_or_tty->print_cr(" GC time is exceeding GCTimeLimit " 327 "of %d%%", GCTimeLimit); 328 } else { 329 gclog_or_tty->print_cr(" GC time would exceed GCTimeLimit " 330 "of %d%%", GCTimeLimit); 331 } 332 } 333 size_policy->set_print_gc_time_limit_would_be_exceeded(false); 334 } 335 } 336 337 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) { 338 HandleMark hm; // Discard invalid handles created during verification 339 gclog_or_tty->print(" VerifyAfterGC:"); 340 Universe::verify(false); 341 } 342 343 // Re-verify object start arrays 344 if (VerifyObjectStartArray && 345 VerifyAfterGC) { 346 old_gen->verify_object_start_array(); 347 perm_gen->verify_object_start_array(); 348 } 349 350 NOT_PRODUCT(ref_processor()->verify_no_references_recorded()); 351 352 if (PrintHeapAtGC) { 353 Universe::print_heap_after_gc(); 354 } 355 } 356 357 bool PSMarkSweep::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy, 358 PSYoungGen* young_gen, 359 PSOldGen* old_gen) { 360 MutableSpace* const eden_space = young_gen->eden_space(); 361 assert(!eden_space->is_empty(), "eden must be non-empty"); 362 assert(young_gen->virtual_space()->alignment() == 363 old_gen->virtual_space()->alignment(), "alignments do not match"); 364 365 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) { 366 return false; 367 } 368 369 // Both generations must be completely committed. 370 if (young_gen->virtual_space()->uncommitted_size() != 0) { 371 return false; 372 } 373 if (old_gen->virtual_space()->uncommitted_size() != 0) { 374 return false; 375 } 376 377 // Figure out how much to take from eden. Include the average amount promoted 378 // in the total; otherwise the next young gen GC will simply bail out to a 379 // full GC. 380 const size_t alignment = old_gen->virtual_space()->alignment(); 381 const size_t eden_used = eden_space->used_in_bytes(); 382 const size_t promoted = (size_t)(size_policy->avg_promoted()->padded_average()); 383 const size_t absorb_size = align_size_up(eden_used + promoted, alignment); 384 const size_t eden_capacity = eden_space->capacity_in_bytes(); 385 386 if (absorb_size >= eden_capacity) { 387 return false; // Must leave some space in eden. 388 } 389 390 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size; 391 if (new_young_size < young_gen->min_gen_size()) { 392 return false; // Respect young gen minimum size. 393 } 394 395 if (TraceAdaptiveGCBoundary && Verbose) { 396 gclog_or_tty->print(" absorbing " SIZE_FORMAT "K: " 397 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K " 398 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K " 399 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ", 400 absorb_size / K, 401 eden_capacity / K, (eden_capacity - absorb_size) / K, 402 young_gen->from_space()->used_in_bytes() / K, 403 young_gen->to_space()->used_in_bytes() / K, 404 young_gen->capacity_in_bytes() / K, new_young_size / K); 405 } 406 407 // Fill the unused part of the old gen. 408 MutableSpace* const old_space = old_gen->object_space(); 409 MemRegion old_gen_unused(old_space->top(), old_space->end()); 410 411 // If the unused part of the old gen cannot be filled, skip 412 // absorbing eden. 413 if (old_gen_unused.word_size() < SharedHeap::min_fill_size()) { 414 return false; 415 } 416 417 if (!old_gen_unused.is_empty()) { 418 SharedHeap::fill_region_with_object(old_gen_unused); 419 } 420 421 // Take the live data from eden and set both top and end in the old gen to 422 // eden top. (Need to set end because reset_after_change() mangles the region 423 // from end to virtual_space->high() in debug builds). 424 HeapWord* const new_top = eden_space->top(); 425 old_gen->virtual_space()->expand_into(young_gen->virtual_space(), 426 absorb_size); 427 young_gen->reset_after_change(); 428 old_space->set_top(new_top); 429 old_space->set_end(new_top); 430 old_gen->reset_after_change(); 431 432 // Update the object start array for the filler object and the data from eden. 433 ObjectStartArray* const start_array = old_gen->start_array(); 434 HeapWord* const start = old_gen_unused.start(); 435 for (HeapWord* addr = start; addr < new_top; addr += oop(addr)->size()) { 436 start_array->allocate_block(addr); 437 } 438 439 // Could update the promoted average here, but it is not typically updated at 440 // full GCs and the value to use is unclear. Something like 441 // 442 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc. 443 444 size_policy->set_bytes_absorbed_from_eden(absorb_size); 445 return true; 446 } 447 448 void PSMarkSweep::allocate_stacks() { 449 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 450 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 451 452 PSYoungGen* young_gen = heap->young_gen(); 453 454 MutableSpace* to_space = young_gen->to_space(); 455 _preserved_marks = (PreservedMark*)to_space->top(); 456 _preserved_count = 0; 457 458 // We want to calculate the size in bytes first. 459 _preserved_count_max = pointer_delta(to_space->end(), to_space->top(), sizeof(jbyte)); 460 // Now divide by the size of a PreservedMark 461 _preserved_count_max /= sizeof(PreservedMark); 462 463 _preserved_mark_stack = NULL; 464 _preserved_oop_stack = NULL; 465 466 _marking_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(4000, true); 467 468 int size = SystemDictionary::number_of_classes() * 2; 469 _revisit_klass_stack = new (ResourceObj::C_HEAP) GrowableArray<Klass*>(size, true); 470 } 471 472 473 void PSMarkSweep::deallocate_stacks() { 474 if (_preserved_oop_stack) { 475 delete _preserved_mark_stack; 476 _preserved_mark_stack = NULL; 477 delete _preserved_oop_stack; 478 _preserved_oop_stack = NULL; 479 } 480 481 delete _marking_stack; 482 delete _revisit_klass_stack; 483 } 484 485 void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) { 486 // Recursively traverse all live objects and mark them 487 EventMark m("1 mark object"); 488 TraceTime tm("phase 1", PrintGCDetails && Verbose, true, gclog_or_tty); 489 trace(" 1"); 490 491 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 492 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 493 494 // General strong roots. 495 Universe::oops_do(mark_and_push_closure()); 496 ReferenceProcessor::oops_do(mark_and_push_closure()); 497 JNIHandles::oops_do(mark_and_push_closure()); // Global (strong) JNI handles 498 Threads::oops_do(mark_and_push_closure()); 499 ObjectSynchronizer::oops_do(mark_and_push_closure()); 500 FlatProfiler::oops_do(mark_and_push_closure()); 501 Management::oops_do(mark_and_push_closure()); 502 JvmtiExport::oops_do(mark_and_push_closure()); 503 SystemDictionary::always_strong_oops_do(mark_and_push_closure()); 504 vmSymbols::oops_do(mark_and_push_closure()); 505 506 // Flush marking stack. 507 follow_stack(); 508 509 // Process reference objects found during marking 510 511 // Skipping the reference processing for VerifyParallelOldWithMarkSweep 512 // affects the marking (makes it different). 513 { 514 ReferencePolicy *soft_ref_policy; 515 if (clear_all_softrefs) { 516 soft_ref_policy = new AlwaysClearPolicy(); 517 } else { 518 #ifdef COMPILER2 519 soft_ref_policy = new LRUMaxHeapPolicy(); 520 #else 521 soft_ref_policy = new LRUCurrentHeapPolicy(); 522 #endif // COMPILER2 523 } 524 assert(soft_ref_policy != NULL,"No soft reference policy"); 525 ref_processor()->process_discovered_references( 526 soft_ref_policy, is_alive_closure(), mark_and_push_closure(), 527 follow_stack_closure(), NULL); 528 } 529 530 // Follow system dictionary roots and unload classes 531 bool purged_class = SystemDictionary::do_unloading(is_alive_closure()); 532 533 // Follow code cache roots 534 CodeCache::do_unloading(is_alive_closure(), mark_and_push_closure(), 535 purged_class); 536 follow_stack(); // Flush marking stack 537 538 // Update subklass/sibling/implementor links of live klasses 539 follow_weak_klass_links(); 540 assert(_marking_stack->is_empty(), "just drained"); 541 542 // Visit symbol and interned string tables and delete unmarked oops 543 SymbolTable::unlink(is_alive_closure()); 544 StringTable::unlink(is_alive_closure()); 545 546 assert(_marking_stack->is_empty(), "stack should be empty by now"); 547 } 548 549 550 void PSMarkSweep::mark_sweep_phase2() { 551 EventMark m("2 compute new addresses"); 552 TraceTime tm("phase 2", PrintGCDetails && Verbose, true, gclog_or_tty); 553 trace("2"); 554 555 // Now all live objects are marked, compute the new object addresses. 556 557 // It is imperative that we traverse perm_gen LAST. If dead space is 558 // allowed a range of dead object may get overwritten by a dead int 559 // array. If perm_gen is not traversed last a klassOop may get 560 // overwritten. This is fine since it is dead, but if the class has dead 561 // instances we have to skip them, and in order to find their size we 562 // need the klassOop! 563 // 564 // It is not required that we traverse spaces in the same order in 565 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops 566 // tracking expects us to do so. See comment under phase4. 567 568 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 569 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 570 571 PSOldGen* old_gen = heap->old_gen(); 572 PSPermGen* perm_gen = heap->perm_gen(); 573 574 // Begin compacting into the old gen 575 PSMarkSweepDecorator::set_destination_decorator_tenured(); 576 577 // This will also compact the young gen spaces. 578 old_gen->precompact(); 579 580 // Compact the perm gen into the perm gen 581 PSMarkSweepDecorator::set_destination_decorator_perm_gen(); 582 583 perm_gen->precompact(); 584 } 585 586 // This should be moved to the shared markSweep code! 587 class PSAlwaysTrueClosure: public BoolObjectClosure { 588 public: 589 void do_object(oop p) { ShouldNotReachHere(); } 590 bool do_object_b(oop p) { return true; } 591 }; 592 static PSAlwaysTrueClosure always_true; 593 594 void PSMarkSweep::mark_sweep_phase3() { 595 // Adjust the pointers to reflect the new locations 596 EventMark m("3 adjust pointers"); 597 TraceTime tm("phase 3", PrintGCDetails && Verbose, true, gclog_or_tty); 598 trace("3"); 599 600 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 601 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 602 603 PSYoungGen* young_gen = heap->young_gen(); 604 PSOldGen* old_gen = heap->old_gen(); 605 PSPermGen* perm_gen = heap->perm_gen(); 606 607 // General strong roots. 608 Universe::oops_do(adjust_root_pointer_closure()); 609 ReferenceProcessor::oops_do(adjust_root_pointer_closure()); 610 JNIHandles::oops_do(adjust_root_pointer_closure()); // Global (strong) JNI handles 611 Threads::oops_do(adjust_root_pointer_closure()); 612 ObjectSynchronizer::oops_do(adjust_root_pointer_closure()); 613 FlatProfiler::oops_do(adjust_root_pointer_closure()); 614 Management::oops_do(adjust_root_pointer_closure()); 615 JvmtiExport::oops_do(adjust_root_pointer_closure()); 616 // SO_AllClasses 617 SystemDictionary::oops_do(adjust_root_pointer_closure()); 618 vmSymbols::oops_do(adjust_root_pointer_closure()); 619 620 // Now adjust pointers in remaining weak roots. (All of which should 621 // have been cleared if they pointed to non-surviving objects.) 622 // Global (weak) JNI handles 623 JNIHandles::weak_oops_do(&always_true, adjust_root_pointer_closure()); 624 625 CodeCache::oops_do(adjust_pointer_closure()); 626 SymbolTable::oops_do(adjust_root_pointer_closure()); 627 StringTable::oops_do(adjust_root_pointer_closure()); 628 ref_processor()->weak_oops_do(adjust_root_pointer_closure()); 629 PSScavenge::reference_processor()->weak_oops_do(adjust_root_pointer_closure()); 630 631 adjust_marks(); 632 633 young_gen->adjust_pointers(); 634 old_gen->adjust_pointers(); 635 perm_gen->adjust_pointers(); 636 } 637 638 void PSMarkSweep::mark_sweep_phase4() { 639 EventMark m("4 compact heap"); 640 TraceTime tm("phase 4", PrintGCDetails && Verbose, true, gclog_or_tty); 641 trace("4"); 642 643 // All pointers are now adjusted, move objects accordingly 644 645 // It is imperative that we traverse perm_gen first in phase4. All 646 // classes must be allocated earlier than their instances, and traversing 647 // perm_gen first makes sure that all klassOops have moved to their new 648 // location before any instance does a dispatch through it's klass! 649 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 650 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 651 652 PSYoungGen* young_gen = heap->young_gen(); 653 PSOldGen* old_gen = heap->old_gen(); 654 PSPermGen* perm_gen = heap->perm_gen(); 655 656 perm_gen->compact(); 657 old_gen->compact(); 658 young_gen->compact(); 659 } 660 661 jlong PSMarkSweep::millis_since_last_gc() { 662 jlong ret_val = os::javaTimeMillis() - _time_of_last_gc; 663 // XXX See note in genCollectedHeap::millis_since_last_gc(). 664 if (ret_val < 0) { 665 NOT_PRODUCT(warning("time warp: %d", ret_val);) 666 return 0; 667 } 668 return ret_val; 669 } 670 671 void PSMarkSweep::reset_millis_since_last_gc() { 672 _time_of_last_gc = os::javaTimeMillis(); 673 }