1 /* 2 * Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/symbolTable.hpp" 27 #include "classfile/systemDictionary.hpp" 28 #include "classfile/vmSymbols.hpp" 29 #include "code/codeCache.hpp" 30 #include "code/icBuffer.hpp" 31 #include "gc/shared/collectedHeap.inline.hpp" 32 #include "gc/shared/collectorCounters.hpp" 33 #include "gc/shared/gcId.hpp" 34 #include "gc/shared/gcLocker.inline.hpp" 35 #include "gc/shared/gcTrace.hpp" 36 #include "gc/shared/gcTraceTime.inline.hpp" 37 #include "gc/shared/genCollectedHeap.hpp" 38 #include "gc/shared/genOopClosures.inline.hpp" 39 #include "gc/shared/generationSpec.hpp" 40 #include "gc/shared/space.hpp" 41 #include "gc/shared/strongRootsScope.hpp" 42 #include "gc/shared/vmGCOperations.hpp" 43 #include "gc/shared/workgroup.hpp" 44 #include "memory/filemap.hpp" 45 #include "memory/resourceArea.hpp" 46 #include "oops/oop.inline.hpp" 47 #include "runtime/biasedLocking.hpp" 48 #include "runtime/fprofiler.hpp" 49 #include "runtime/handles.hpp" 50 #include "runtime/handles.inline.hpp" 51 #include "runtime/java.hpp" 52 #include "runtime/vmThread.hpp" 53 #include "services/management.hpp" 54 #include "services/memoryService.hpp" 55 #include "utilities/macros.hpp" 56 #include "utilities/stack.inline.hpp" 57 #include "utilities/vmError.hpp" 58 #if INCLUDE_ALL_GCS 59 #include "gc/cms/concurrentMarkSweepThread.hpp" 60 #include "gc/cms/vmCMSOperations.hpp" 61 #endif // INCLUDE_ALL_GCS 62 63 NOT_PRODUCT(size_t GenCollectedHeap::_skip_header_HeapWords = 0;) 64 65 // The set of potentially parallel tasks in root scanning. 66 enum GCH_strong_roots_tasks { 67 GCH_PS_Universe_oops_do, 68 GCH_PS_JNIHandles_oops_do, 69 GCH_PS_ObjectSynchronizer_oops_do, 70 GCH_PS_FlatProfiler_oops_do, 71 GCH_PS_Management_oops_do, 72 GCH_PS_SystemDictionary_oops_do, 73 GCH_PS_ClassLoaderDataGraph_oops_do, 74 GCH_PS_jvmti_oops_do, 75 GCH_PS_CodeCache_oops_do, 76 GCH_PS_younger_gens, 77 // Leave this one last. 78 GCH_PS_NumElements 79 }; 80 81 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy) : 82 CollectedHeap(), 83 _rem_set(NULL), 84 _gen_policy(policy), 85 _process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)), 86 _full_collections_completed(0) 87 { 88 assert(policy != NULL, "Sanity check"); 89 if (UseConcMarkSweepGC) { 90 _workers = new WorkGang("GC Thread", ParallelGCThreads, 91 /* are_GC_task_threads */true, 92 /* are_ConcurrentGC_threads */false); 93 _workers->initialize_workers(); 94 } else { 95 // Serial GC does not use workers. 96 _workers = NULL; 97 } 98 } 99 100 jint GenCollectedHeap::initialize() { 101 CollectedHeap::pre_initialize(); 102 103 // While there are no constraints in the GC code that HeapWordSize 104 // be any particular value, there are multiple other areas in the 105 // system which believe this to be true (e.g. oop->object_size in some 106 // cases incorrectly returns the size in wordSize units rather than 107 // HeapWordSize). 108 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 109 110 // Allocate space for the heap. 111 112 char* heap_address; 113 ReservedSpace heap_rs; 114 115 size_t heap_alignment = collector_policy()->heap_alignment(); 116 117 heap_address = allocate(heap_alignment, &heap_rs); 118 119 if (!heap_rs.is_reserved()) { 120 vm_shutdown_during_initialization( 121 "Could not reserve enough space for object heap"); 122 return JNI_ENOMEM; 123 } 124 125 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 126 127 _rem_set = collector_policy()->create_rem_set(reserved_region()); 128 set_barrier_set(rem_set()->bs()); 129 130 ReservedSpace young_rs = heap_rs.first_part(gen_policy()->young_gen_spec()->max_size(), false, false); 131 _young_gen = gen_policy()->young_gen_spec()->init(young_rs, rem_set()); 132 heap_rs = heap_rs.last_part(gen_policy()->young_gen_spec()->max_size()); 133 134 ReservedSpace old_rs = heap_rs.first_part(gen_policy()->old_gen_spec()->max_size(), false, false); 135 _old_gen = gen_policy()->old_gen_spec()->init(old_rs, rem_set()); 136 clear_incremental_collection_failed(); 137 138 #if INCLUDE_ALL_GCS 139 // If we are running CMS, create the collector responsible 140 // for collecting the CMS generations. 141 if (collector_policy()->is_concurrent_mark_sweep_policy()) { 142 bool success = create_cms_collector(); 143 if (!success) return JNI_ENOMEM; 144 } 145 #endif // INCLUDE_ALL_GCS 146 147 return JNI_OK; 148 } 149 150 char* GenCollectedHeap::allocate(size_t alignment, 151 ReservedSpace* heap_rs){ 152 // Now figure out the total size. 153 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size(); 154 assert(alignment % pageSize == 0, "Must be"); 155 156 GenerationSpec* young_spec = gen_policy()->young_gen_spec(); 157 GenerationSpec* old_spec = gen_policy()->old_gen_spec(); 158 159 // Check for overflow. 160 size_t total_reserved = young_spec->max_size() + old_spec->max_size(); 161 if (total_reserved < young_spec->max_size()) { 162 vm_exit_during_initialization("The size of the object heap + VM data exceeds " 163 "the maximum representable size"); 164 } 165 assert(total_reserved % alignment == 0, 166 "Gen size; total_reserved=" SIZE_FORMAT ", alignment=" 167 SIZE_FORMAT, total_reserved, alignment); 168 169 *heap_rs = Universe::reserve_heap(total_reserved, alignment); 170 return heap_rs->base(); 171 } 172 173 void GenCollectedHeap::post_initialize() { 174 CollectedHeap::post_initialize(); 175 ref_processing_init(); 176 assert((_young_gen->kind() == Generation::DefNew) || 177 (_young_gen->kind() == Generation::ParNew), 178 "Wrong youngest generation type"); 179 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen; 180 181 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep || 182 _old_gen->kind() == Generation::MarkSweepCompact, 183 "Wrong generation kind"); 184 185 _gen_policy->initialize_size_policy(def_new_gen->eden()->capacity(), 186 _old_gen->capacity(), 187 def_new_gen->from()->capacity()); 188 _gen_policy->initialize_gc_policy_counters(); 189 } 190 191 void GenCollectedHeap::ref_processing_init() { 192 _young_gen->ref_processor_init(); 193 _old_gen->ref_processor_init(); 194 } 195 196 size_t GenCollectedHeap::capacity() const { 197 return _young_gen->capacity() + _old_gen->capacity(); 198 } 199 200 size_t GenCollectedHeap::used() const { 201 return _young_gen->used() + _old_gen->used(); 202 } 203 204 void GenCollectedHeap::save_used_regions() { 205 _old_gen->save_used_region(); 206 _young_gen->save_used_region(); 207 } 208 209 size_t GenCollectedHeap::max_capacity() const { 210 return _young_gen->max_capacity() + _old_gen->max_capacity(); 211 } 212 213 // Update the _full_collections_completed counter 214 // at the end of a stop-world full GC. 215 unsigned int GenCollectedHeap::update_full_collections_completed() { 216 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 217 assert(_full_collections_completed <= _total_full_collections, 218 "Can't complete more collections than were started"); 219 _full_collections_completed = _total_full_collections; 220 ml.notify_all(); 221 return _full_collections_completed; 222 } 223 224 // Update the _full_collections_completed counter, as appropriate, 225 // at the end of a concurrent GC cycle. Note the conditional update 226 // below to allow this method to be called by a concurrent collector 227 // without synchronizing in any manner with the VM thread (which 228 // may already have initiated a STW full collection "concurrently"). 229 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) { 230 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 231 assert((_full_collections_completed <= _total_full_collections) && 232 (count <= _total_full_collections), 233 "Can't complete more collections than were started"); 234 if (count > _full_collections_completed) { 235 _full_collections_completed = count; 236 ml.notify_all(); 237 } 238 return _full_collections_completed; 239 } 240 241 242 #ifndef PRODUCT 243 // Override of memory state checking method in CollectedHeap: 244 // Some collectors (CMS for example) can't have badHeapWordVal written 245 // in the first two words of an object. (For instance , in the case of 246 // CMS these words hold state used to synchronize between certain 247 // (concurrent) GC steps and direct allocating mutators.) 248 // The skip_header_HeapWords() method below, allows us to skip 249 // over the requisite number of HeapWord's. Note that (for 250 // generational collectors) this means that those many words are 251 // skipped in each object, irrespective of the generation in which 252 // that object lives. The resultant loss of precision seems to be 253 // harmless and the pain of avoiding that imprecision appears somewhat 254 // higher than we are prepared to pay for such rudimentary debugging 255 // support. 256 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr, 257 size_t size) { 258 if (CheckMemoryInitialization && ZapUnusedHeapArea) { 259 // We are asked to check a size in HeapWords, 260 // but the memory is mangled in juint words. 261 juint* start = (juint*) (addr + skip_header_HeapWords()); 262 juint* end = (juint*) (addr + size); 263 for (juint* slot = start; slot < end; slot += 1) { 264 assert(*slot == badHeapWordVal, 265 "Found non badHeapWordValue in pre-allocation check"); 266 } 267 } 268 } 269 #endif 270 271 HeapWord* GenCollectedHeap::attempt_allocation(size_t size, 272 bool is_tlab, 273 bool first_only) { 274 HeapWord* res = NULL; 275 276 if (_young_gen->should_allocate(size, is_tlab)) { 277 res = _young_gen->allocate(size, is_tlab); 278 if (res != NULL || first_only) { 279 return res; 280 } 281 } 282 283 if (_old_gen->should_allocate(size, is_tlab)) { 284 res = _old_gen->allocate(size, is_tlab); 285 } 286 287 return res; 288 } 289 290 HeapWord* GenCollectedHeap::mem_allocate(size_t size, 291 bool* gc_overhead_limit_was_exceeded) { 292 return collector_policy()->mem_allocate_work(size, 293 false /* is_tlab */, 294 gc_overhead_limit_was_exceeded); 295 } 296 297 bool GenCollectedHeap::must_clear_all_soft_refs() { 298 return _gc_cause == GCCause::_last_ditch_collection; 299 } 300 301 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 302 if (!UseConcMarkSweepGC) { 303 return false; 304 } 305 306 switch (cause) { 307 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 308 case GCCause::_java_lang_system_gc: 309 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 310 default: return false; 311 } 312 } 313 314 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size, 315 bool is_tlab, bool run_verification, bool clear_soft_refs, 316 bool restore_marks_for_biased_locking) { 317 FormatBuffer<> title("Collect gen: %s", gen->short_name()); 318 GCTraceTime(Debug, gc) t1(title); 319 TraceCollectorStats tcs(gen->counters()); 320 TraceMemoryManagerStats tmms(gen->kind(),gc_cause()); 321 322 gen->stat_record()->invocations++; 323 gen->stat_record()->accumulated_time.start(); 324 325 // Must be done anew before each collection because 326 // a previous collection will do mangling and will 327 // change top of some spaces. 328 record_gen_tops_before_GC(); 329 330 log_trace(gc)("%s invoke=%d size=" SIZE_FORMAT, heap()->is_young_gen(gen) ? "Young" : "Old", gen->stat_record()->invocations, size * HeapWordSize); 331 332 if (run_verification && VerifyBeforeGC) { 333 HandleMark hm; // Discard invalid handles created during verification 334 Universe::verify("Before GC"); 335 } 336 COMPILER2_PRESENT(DerivedPointerTable::clear()); 337 338 if (restore_marks_for_biased_locking) { 339 // We perform this mark word preservation work lazily 340 // because it's only at this point that we know whether we 341 // absolutely have to do it; we want to avoid doing it for 342 // scavenge-only collections where it's unnecessary 343 BiasedLocking::preserve_marks(); 344 } 345 346 // Do collection work 347 { 348 // Note on ref discovery: For what appear to be historical reasons, 349 // GCH enables and disabled (by enqueing) refs discovery. 350 // In the future this should be moved into the generation's 351 // collect method so that ref discovery and enqueueing concerns 352 // are local to a generation. The collect method could return 353 // an appropriate indication in the case that notification on 354 // the ref lock was needed. This will make the treatment of 355 // weak refs more uniform (and indeed remove such concerns 356 // from GCH). XXX 357 358 HandleMark hm; // Discard invalid handles created during gc 359 save_marks(); // save marks for all gens 360 // We want to discover references, but not process them yet. 361 // This mode is disabled in process_discovered_references if the 362 // generation does some collection work, or in 363 // enqueue_discovered_references if the generation returns 364 // without doing any work. 365 ReferenceProcessor* rp = gen->ref_processor(); 366 // If the discovery of ("weak") refs in this generation is 367 // atomic wrt other collectors in this configuration, we 368 // are guaranteed to have empty discovered ref lists. 369 if (rp->discovery_is_atomic()) { 370 rp->enable_discovery(); 371 rp->setup_policy(clear_soft_refs); 372 } else { 373 // collect() below will enable discovery as appropriate 374 } 375 gen->collect(full, clear_soft_refs, size, is_tlab); 376 if (!rp->enqueuing_is_done()) { 377 rp->enqueue_discovered_references(); 378 } else { 379 rp->set_enqueuing_is_done(false); 380 } 381 rp->verify_no_references_recorded(); 382 } 383 384 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 385 386 gen->stat_record()->accumulated_time.stop(); 387 388 update_gc_stats(gen, full); 389 390 if (run_verification && VerifyAfterGC) { 391 HandleMark hm; // Discard invalid handles created during verification 392 Universe::verify("After GC"); 393 } 394 } 395 396 void GenCollectedHeap::do_collection(bool full, 397 bool clear_all_soft_refs, 398 size_t size, 399 bool is_tlab, 400 GenerationType max_generation) { 401 ResourceMark rm; 402 DEBUG_ONLY(Thread* my_thread = Thread::current();) 403 404 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 405 assert(my_thread->is_VM_thread() || 406 my_thread->is_ConcurrentGC_thread(), 407 "incorrect thread type capability"); 408 assert(Heap_lock->is_locked(), 409 "the requesting thread should have the Heap_lock"); 410 guarantee(!is_gc_active(), "collection is not reentrant"); 411 412 if (GCLocker::check_active_before_gc()) { 413 return; // GC is disabled (e.g. JNI GetXXXCritical operation) 414 } 415 416 GCIdMarkAndRestore gc_id_mark; 417 418 const bool do_clear_all_soft_refs = clear_all_soft_refs || 419 collector_policy()->should_clear_all_soft_refs(); 420 421 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 422 423 const size_t metadata_prev_used = MetaspaceAux::used_bytes(); 424 425 print_heap_before_gc(); 426 427 { 428 FlagSetting fl(_is_gc_active, true); 429 430 bool complete = full && (max_generation == OldGen); 431 bool old_collects_young = complete && !ScavengeBeforeFullGC; 432 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab); 433 434 FormatBuffer<> gc_string("%s", "Pause "); 435 if (do_young_collection) { 436 gc_string.append("Young"); 437 } else { 438 gc_string.append("Full"); 439 } 440 441 GCTraceCPUTime tcpu; 442 GCTraceTime(Info, gc) t(gc_string, NULL, gc_cause(), true); 443 444 gc_prologue(complete); 445 increment_total_collections(complete); 446 447 size_t young_prev_used = _young_gen->used(); 448 size_t old_prev_used = _old_gen->used(); 449 450 bool run_verification = total_collections() >= VerifyGCStartAt; 451 452 bool prepared_for_verification = false; 453 bool collected_old = false; 454 455 if (do_young_collection) { 456 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) { 457 prepare_for_verify(); 458 prepared_for_verification = true; 459 } 460 461 collect_generation(_young_gen, 462 full, 463 size, 464 is_tlab, 465 run_verification && VerifyGCLevel <= 0, 466 do_clear_all_soft_refs, 467 false); 468 469 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) && 470 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) { 471 // Allocation request was met by young GC. 472 size = 0; 473 } 474 } 475 476 bool must_restore_marks_for_biased_locking = false; 477 478 if (max_generation == OldGen && _old_gen->should_collect(full, size, is_tlab)) { 479 if (!complete) { 480 // The full_collections increment was missed above. 481 increment_total_full_collections(); 482 } 483 484 pre_full_gc_dump(NULL); // do any pre full gc dumps 485 486 if (!prepared_for_verification && run_verification && 487 VerifyGCLevel <= 1 && VerifyBeforeGC) { 488 prepare_for_verify(); 489 } 490 491 if (do_young_collection) { 492 // We did a young GC. Need a new GC id for the old GC. 493 GCIdMarkAndRestore gc_id_mark; 494 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true); 495 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true); 496 } else { 497 // No young GC done. Use the same GC id as was set up earlier in this method. 498 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true); 499 } 500 501 must_restore_marks_for_biased_locking = true; 502 collected_old = true; 503 } 504 505 // Update "complete" boolean wrt what actually transpired -- 506 // for instance, a promotion failure could have led to 507 // a whole heap collection. 508 complete = complete || collected_old; 509 510 if (complete) { // We did a full collection 511 // FIXME: See comment at pre_full_gc_dump call 512 post_full_gc_dump(NULL); // do any post full gc dumps 513 } 514 515 print_heap_change(young_prev_used, old_prev_used); 516 MetaspaceAux::print_metaspace_change(metadata_prev_used); 517 518 // Adjust generation sizes. 519 if (collected_old) { 520 _old_gen->compute_new_size(); 521 } 522 _young_gen->compute_new_size(); 523 524 if (complete) { 525 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 526 ClassLoaderDataGraph::purge(); 527 MetaspaceAux::verify_metrics(); 528 // Resize the metaspace capacity after full collections 529 MetaspaceGC::compute_new_size(); 530 update_full_collections_completed(); 531 } 532 533 // Track memory usage and detect low memory after GC finishes 534 MemoryService::track_memory_usage(); 535 536 gc_epilogue(complete); 537 538 if (must_restore_marks_for_biased_locking) { 539 BiasedLocking::restore_marks(); 540 } 541 } 542 543 print_heap_after_gc(); 544 545 #ifdef TRACESPINNING 546 ParallelTaskTerminator::print_termination_counts(); 547 #endif 548 } 549 550 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) { 551 return collector_policy()->satisfy_failed_allocation(size, is_tlab); 552 } 553 554 #ifdef ASSERT 555 class AssertNonScavengableClosure: public OopClosure { 556 public: 557 virtual void do_oop(oop* p) { 558 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p), 559 "Referent should not be scavengable."); } 560 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); } 561 }; 562 static AssertNonScavengableClosure assert_is_non_scavengable_closure; 563 #endif 564 565 void GenCollectedHeap::process_roots(StrongRootsScope* scope, 566 ScanningOption so, 567 OopClosure* strong_roots, 568 OopClosure* weak_roots, 569 CLDClosure* strong_cld_closure, 570 CLDClosure* weak_cld_closure, 571 CodeBlobClosure* code_roots) { 572 // General roots. 573 assert(Threads::thread_claim_parity() != 0, "must have called prologue code"); 574 assert(code_roots != NULL, "code root closure should always be set"); 575 // _n_termination for _process_strong_tasks should be set up stream 576 // in a method not running in a GC worker. Otherwise the GC worker 577 // could be trying to change the termination condition while the task 578 // is executing in another GC worker. 579 580 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) { 581 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure); 582 } 583 584 // Some CLDs contained in the thread frames should be considered strong. 585 // Don't process them if they will be processed during the ClassLoaderDataGraph phase. 586 CLDClosure* roots_from_clds_p = (strong_cld_closure != weak_cld_closure) ? strong_cld_closure : NULL; 587 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway 588 CodeBlobClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots; 589 590 bool is_par = scope->n_threads() > 1; 591 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_clds_p, roots_from_code_p); 592 593 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) { 594 Universe::oops_do(strong_roots); 595 } 596 // Global (strong) JNI handles 597 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) { 598 JNIHandles::oops_do(strong_roots); 599 } 600 601 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) { 602 ObjectSynchronizer::oops_do(strong_roots); 603 } 604 if (!_process_strong_tasks->is_task_claimed(GCH_PS_FlatProfiler_oops_do)) { 605 FlatProfiler::oops_do(strong_roots); 606 } 607 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) { 608 Management::oops_do(strong_roots); 609 } 610 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) { 611 JvmtiExport::oops_do(strong_roots); 612 } 613 614 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) { 615 SystemDictionary::roots_oops_do(strong_roots, weak_roots); 616 } 617 618 // All threads execute the following. A specific chunk of buckets 619 // from the StringTable are the individual tasks. 620 if (weak_roots != NULL) { 621 if (is_par) { 622 StringTable::possibly_parallel_oops_do(weak_roots); 623 } else { 624 StringTable::oops_do(weak_roots); 625 } 626 } 627 628 if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) { 629 if (so & SO_ScavengeCodeCache) { 630 assert(code_roots != NULL, "must supply closure for code cache"); 631 632 // We only visit parts of the CodeCache when scavenging. 633 CodeCache::scavenge_root_nmethods_do(code_roots); 634 } 635 if (so & SO_AllCodeCache) { 636 assert(code_roots != NULL, "must supply closure for code cache"); 637 638 // CMSCollector uses this to do intermediate-strength collections. 639 // We scan the entire code cache, since CodeCache::do_unloading is not called. 640 CodeCache::blobs_do(code_roots); 641 } 642 // Verify that the code cache contents are not subject to 643 // movement by a scavenging collection. 644 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations)); 645 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable)); 646 } 647 } 648 649 void GenCollectedHeap::gen_process_roots(StrongRootsScope* scope, 650 GenerationType type, 651 bool young_gen_as_roots, 652 ScanningOption so, 653 bool only_strong_roots, 654 OopsInGenClosure* not_older_gens, 655 OopsInGenClosure* older_gens, 656 CLDClosure* cld_closure) { 657 const bool is_adjust_phase = !only_strong_roots && !young_gen_as_roots; 658 659 bool is_moving_collection = false; 660 if (type == YoungGen || is_adjust_phase) { 661 // young collections are always moving 662 is_moving_collection = true; 663 } 664 665 MarkingCodeBlobClosure mark_code_closure(not_older_gens, is_moving_collection); 666 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : not_older_gens; 667 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure; 668 669 process_roots(scope, so, 670 not_older_gens, weak_roots, 671 cld_closure, weak_cld_closure, 672 &mark_code_closure); 673 674 if (young_gen_as_roots) { 675 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) { 676 if (type == OldGen) { 677 not_older_gens->set_generation(_young_gen); 678 _young_gen->oop_iterate(not_older_gens); 679 } 680 not_older_gens->reset_generation(); 681 } 682 } 683 // When collection is parallel, all threads get to cooperate to do 684 // old generation scanning. 685 if (type == YoungGen) { 686 older_gens->set_generation(_old_gen); 687 rem_set()->younger_refs_iterate(_old_gen, older_gens, scope->n_threads()); 688 older_gens->reset_generation(); 689 } 690 691 _process_strong_tasks->all_tasks_completed(scope->n_threads()); 692 } 693 694 695 class AlwaysTrueClosure: public BoolObjectClosure { 696 public: 697 bool do_object_b(oop p) { return true; } 698 }; 699 static AlwaysTrueClosure always_true; 700 701 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) { 702 JNIHandles::weak_oops_do(&always_true, root_closure); 703 _young_gen->ref_processor()->weak_oops_do(root_closure); 704 _old_gen->ref_processor()->weak_oops_do(root_closure); 705 } 706 707 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \ 708 void GenCollectedHeap:: \ 709 oop_since_save_marks_iterate(GenerationType gen, \ 710 OopClosureType* cur, \ 711 OopClosureType* older) { \ 712 if (gen == YoungGen) { \ 713 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \ 714 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \ 715 } else { \ 716 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \ 717 } \ 718 } 719 720 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN) 721 722 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN 723 724 bool GenCollectedHeap::no_allocs_since_save_marks() { 725 return _young_gen->no_allocs_since_save_marks() && 726 _old_gen->no_allocs_since_save_marks(); 727 } 728 729 bool GenCollectedHeap::supports_inline_contig_alloc() const { 730 return _young_gen->supports_inline_contig_alloc(); 731 } 732 733 HeapWord** GenCollectedHeap::top_addr() const { 734 return _young_gen->top_addr(); 735 } 736 737 HeapWord** GenCollectedHeap::end_addr() const { 738 return _young_gen->end_addr(); 739 } 740 741 // public collection interfaces 742 743 void GenCollectedHeap::collect(GCCause::Cause cause) { 744 if (should_do_concurrent_full_gc(cause)) { 745 #if INCLUDE_ALL_GCS 746 // Mostly concurrent full collection. 747 collect_mostly_concurrent(cause); 748 #else // INCLUDE_ALL_GCS 749 ShouldNotReachHere(); 750 #endif // INCLUDE_ALL_GCS 751 } else if (cause == GCCause::_wb_young_gc) { 752 // Young collection for the WhiteBox API. 753 collect(cause, YoungGen); 754 } else { 755 #ifdef ASSERT 756 if (cause == GCCause::_scavenge_alot) { 757 // Young collection only. 758 collect(cause, YoungGen); 759 } else { 760 // Stop-the-world full collection. 761 collect(cause, OldGen); 762 } 763 #else 764 // Stop-the-world full collection. 765 collect(cause, OldGen); 766 #endif 767 } 768 } 769 770 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) { 771 // The caller doesn't have the Heap_lock 772 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock"); 773 MutexLocker ml(Heap_lock); 774 collect_locked(cause, max_generation); 775 } 776 777 void GenCollectedHeap::collect_locked(GCCause::Cause cause) { 778 // The caller has the Heap_lock 779 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock"); 780 collect_locked(cause, OldGen); 781 } 782 783 // this is the private collection interface 784 // The Heap_lock is expected to be held on entry. 785 786 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) { 787 // Read the GC count while holding the Heap_lock 788 unsigned int gc_count_before = total_collections(); 789 unsigned int full_gc_count_before = total_full_collections(); 790 { 791 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back 792 VM_GenCollectFull op(gc_count_before, full_gc_count_before, 793 cause, max_generation); 794 VMThread::execute(&op); 795 } 796 } 797 798 #if INCLUDE_ALL_GCS 799 bool GenCollectedHeap::create_cms_collector() { 800 801 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep, 802 "Unexpected generation kinds"); 803 // Skip two header words in the block content verification 804 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();) 805 assert(_gen_policy->is_concurrent_mark_sweep_policy(), "Unexpected policy type"); 806 CMSCollector* collector = 807 new CMSCollector((ConcurrentMarkSweepGeneration*)_old_gen, 808 _rem_set, 809 _gen_policy->as_concurrent_mark_sweep_policy()); 810 811 if (collector == NULL || !collector->completed_initialization()) { 812 if (collector) { 813 delete collector; // Be nice in embedded situation 814 } 815 vm_shutdown_during_initialization("Could not create CMS collector"); 816 return false; 817 } 818 return true; // success 819 } 820 821 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) { 822 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock"); 823 824 MutexLocker ml(Heap_lock); 825 // Read the GC counts while holding the Heap_lock 826 unsigned int full_gc_count_before = total_full_collections(); 827 unsigned int gc_count_before = total_collections(); 828 { 829 MutexUnlocker mu(Heap_lock); 830 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause); 831 VMThread::execute(&op); 832 } 833 } 834 #endif // INCLUDE_ALL_GCS 835 836 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) { 837 do_full_collection(clear_all_soft_refs, OldGen); 838 } 839 840 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs, 841 GenerationType last_generation) { 842 GenerationType local_last_generation; 843 if (!incremental_collection_will_fail(false /* don't consult_young */) && 844 gc_cause() == GCCause::_gc_locker) { 845 local_last_generation = YoungGen; 846 } else { 847 local_last_generation = last_generation; 848 } 849 850 do_collection(true, // full 851 clear_all_soft_refs, // clear_all_soft_refs 852 0, // size 853 false, // is_tlab 854 local_last_generation); // last_generation 855 // Hack XXX FIX ME !!! 856 // A scavenge may not have been attempted, or may have 857 // been attempted and failed, because the old gen was too full 858 if (local_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker && 859 incremental_collection_will_fail(false /* don't consult_young */)) { 860 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed"); 861 // This time allow the old gen to be collected as well 862 do_collection(true, // full 863 clear_all_soft_refs, // clear_all_soft_refs 864 0, // size 865 false, // is_tlab 866 OldGen); // last_generation 867 } 868 } 869 870 bool GenCollectedHeap::is_in_young(oop p) { 871 bool result = ((HeapWord*)p) < _old_gen->reserved().start(); 872 assert(result == _young_gen->is_in_reserved(p), 873 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p)); 874 return result; 875 } 876 877 // Returns "TRUE" iff "p" points into the committed areas of the heap. 878 bool GenCollectedHeap::is_in(const void* p) const { 879 return _young_gen->is_in(p) || _old_gen->is_in(p); 880 } 881 882 #ifdef ASSERT 883 // Don't implement this by using is_in_young(). This method is used 884 // in some cases to check that is_in_young() is correct. 885 bool GenCollectedHeap::is_in_partial_collection(const void* p) { 886 assert(is_in_reserved(p) || p == NULL, 887 "Does not work if address is non-null and outside of the heap"); 888 return p < _young_gen->reserved().end() && p != NULL; 889 } 890 #endif 891 892 void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) { 893 NoHeaderExtendedOopClosure no_header_cl(cl); 894 oop_iterate(&no_header_cl); 895 } 896 897 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) { 898 _young_gen->oop_iterate(cl); 899 _old_gen->oop_iterate(cl); 900 } 901 902 void GenCollectedHeap::object_iterate(ObjectClosure* cl) { 903 _young_gen->object_iterate(cl); 904 _old_gen->object_iterate(cl); 905 } 906 907 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) { 908 _young_gen->safe_object_iterate(cl); 909 _old_gen->safe_object_iterate(cl); 910 } 911 912 Space* GenCollectedHeap::space_containing(const void* addr) const { 913 Space* res = _young_gen->space_containing(addr); 914 if (res != NULL) { 915 return res; 916 } 917 res = _old_gen->space_containing(addr); 918 assert(res != NULL, "Could not find containing space"); 919 return res; 920 } 921 922 HeapWord* GenCollectedHeap::block_start(const void* addr) const { 923 assert(is_in_reserved(addr), "block_start of address outside of heap"); 924 if (_young_gen->is_in_reserved(addr)) { 925 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation"); 926 return _young_gen->block_start(addr); 927 } 928 929 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 930 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation"); 931 return _old_gen->block_start(addr); 932 } 933 934 size_t GenCollectedHeap::block_size(const HeapWord* addr) const { 935 assert(is_in_reserved(addr), "block_size of address outside of heap"); 936 if (_young_gen->is_in_reserved(addr)) { 937 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation"); 938 return _young_gen->block_size(addr); 939 } 940 941 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 942 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation"); 943 return _old_gen->block_size(addr); 944 } 945 946 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const { 947 assert(is_in_reserved(addr), "block_is_obj of address outside of heap"); 948 assert(block_start(addr) == addr, "addr must be a block start"); 949 if (_young_gen->is_in_reserved(addr)) { 950 return _young_gen->block_is_obj(addr); 951 } 952 953 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 954 return _old_gen->block_is_obj(addr); 955 } 956 957 bool GenCollectedHeap::supports_tlab_allocation() const { 958 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 959 return _young_gen->supports_tlab_allocation(); 960 } 961 962 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const { 963 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 964 if (_young_gen->supports_tlab_allocation()) { 965 return _young_gen->tlab_capacity(); 966 } 967 return 0; 968 } 969 970 size_t GenCollectedHeap::tlab_used(Thread* thr) const { 971 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 972 if (_young_gen->supports_tlab_allocation()) { 973 return _young_gen->tlab_used(); 974 } 975 return 0; 976 } 977 978 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const { 979 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 980 if (_young_gen->supports_tlab_allocation()) { 981 return _young_gen->unsafe_max_tlab_alloc(); 982 } 983 return 0; 984 } 985 986 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) { 987 bool gc_overhead_limit_was_exceeded; 988 return collector_policy()->mem_allocate_work(size /* size */, 989 true /* is_tlab */, 990 &gc_overhead_limit_was_exceeded); 991 } 992 993 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size 994 // from the list headed by "*prev_ptr". 995 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) { 996 bool first = true; 997 size_t min_size = 0; // "first" makes this conceptually infinite. 998 ScratchBlock **smallest_ptr, *smallest; 999 ScratchBlock *cur = *prev_ptr; 1000 while (cur) { 1001 assert(*prev_ptr == cur, "just checking"); 1002 if (first || cur->num_words < min_size) { 1003 smallest_ptr = prev_ptr; 1004 smallest = cur; 1005 min_size = smallest->num_words; 1006 first = false; 1007 } 1008 prev_ptr = &cur->next; 1009 cur = cur->next; 1010 } 1011 smallest = *smallest_ptr; 1012 *smallest_ptr = smallest->next; 1013 return smallest; 1014 } 1015 1016 // Sort the scratch block list headed by res into decreasing size order, 1017 // and set "res" to the result. 1018 static void sort_scratch_list(ScratchBlock*& list) { 1019 ScratchBlock* sorted = NULL; 1020 ScratchBlock* unsorted = list; 1021 while (unsorted) { 1022 ScratchBlock *smallest = removeSmallestScratch(&unsorted); 1023 smallest->next = sorted; 1024 sorted = smallest; 1025 } 1026 list = sorted; 1027 } 1028 1029 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor, 1030 size_t max_alloc_words) { 1031 ScratchBlock* res = NULL; 1032 _young_gen->contribute_scratch(res, requestor, max_alloc_words); 1033 _old_gen->contribute_scratch(res, requestor, max_alloc_words); 1034 sort_scratch_list(res); 1035 return res; 1036 } 1037 1038 void GenCollectedHeap::release_scratch() { 1039 _young_gen->reset_scratch(); 1040 _old_gen->reset_scratch(); 1041 } 1042 1043 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure { 1044 void do_generation(Generation* gen) { 1045 gen->prepare_for_verify(); 1046 } 1047 }; 1048 1049 void GenCollectedHeap::prepare_for_verify() { 1050 ensure_parsability(false); // no need to retire TLABs 1051 GenPrepareForVerifyClosure blk; 1052 generation_iterate(&blk, false); 1053 } 1054 1055 void GenCollectedHeap::generation_iterate(GenClosure* cl, 1056 bool old_to_young) { 1057 if (old_to_young) { 1058 cl->do_generation(_old_gen); 1059 cl->do_generation(_young_gen); 1060 } else { 1061 cl->do_generation(_young_gen); 1062 cl->do_generation(_old_gen); 1063 } 1064 } 1065 1066 bool GenCollectedHeap::is_maximal_no_gc() const { 1067 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc(); 1068 } 1069 1070 void GenCollectedHeap::save_marks() { 1071 _young_gen->save_marks(); 1072 _old_gen->save_marks(); 1073 } 1074 1075 GenCollectedHeap* GenCollectedHeap::heap() { 1076 CollectedHeap* heap = Universe::heap(); 1077 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()"); 1078 assert(heap->kind() == CollectedHeap::GenCollectedHeap, "Not a GenCollectedHeap"); 1079 return (GenCollectedHeap*)heap; 1080 } 1081 1082 void GenCollectedHeap::prepare_for_compaction() { 1083 // Start by compacting into same gen. 1084 CompactPoint cp(_old_gen); 1085 _old_gen->prepare_for_compaction(&cp); 1086 _young_gen->prepare_for_compaction(&cp); 1087 } 1088 1089 void GenCollectedHeap::verify(VerifyOption option /* ignored */) { 1090 log_debug(gc, verify)("%s", _old_gen->name()); 1091 _old_gen->verify(); 1092 1093 log_debug(gc, verify)("%s", _old_gen->name()); 1094 _young_gen->verify(); 1095 1096 log_debug(gc, verify)("RemSet"); 1097 rem_set()->verify(); 1098 } 1099 1100 void GenCollectedHeap::print_on(outputStream* st) const { 1101 _young_gen->print_on(st); 1102 _old_gen->print_on(st); 1103 MetaspaceAux::print_on(st); 1104 } 1105 1106 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const { 1107 if (workers() != NULL) { 1108 workers()->threads_do(tc); 1109 } 1110 #if INCLUDE_ALL_GCS 1111 if (UseConcMarkSweepGC) { 1112 ConcurrentMarkSweepThread::threads_do(tc); 1113 } 1114 #endif // INCLUDE_ALL_GCS 1115 } 1116 1117 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const { 1118 #if INCLUDE_ALL_GCS 1119 if (UseConcMarkSweepGC) { 1120 workers()->print_worker_threads_on(st); 1121 ConcurrentMarkSweepThread::print_all_on(st); 1122 } 1123 #endif // INCLUDE_ALL_GCS 1124 } 1125 1126 void GenCollectedHeap::print_on_error(outputStream* st) const { 1127 this->CollectedHeap::print_on_error(st); 1128 1129 #if INCLUDE_ALL_GCS 1130 if (UseConcMarkSweepGC) { 1131 st->cr(); 1132 CMSCollector::print_on_error(st); 1133 } 1134 #endif // INCLUDE_ALL_GCS 1135 } 1136 1137 void GenCollectedHeap::print_tracing_info() const { 1138 if (TraceYoungGenTime) { 1139 _young_gen->print_summary_info(); 1140 } 1141 if (TraceOldGenTime) { 1142 _old_gen->print_summary_info(); 1143 } 1144 } 1145 1146 void GenCollectedHeap::print_heap_change(size_t young_prev_used, size_t old_prev_used) const { 1147 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)", 1148 _young_gen->short_name(), young_prev_used / K, _young_gen->used() /K, _young_gen->capacity() /K); 1149 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)", 1150 _old_gen->short_name(), old_prev_used / K, _old_gen->used() /K, _old_gen->capacity() /K); 1151 } 1152 1153 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure { 1154 private: 1155 bool _full; 1156 public: 1157 void do_generation(Generation* gen) { 1158 gen->gc_prologue(_full); 1159 } 1160 GenGCPrologueClosure(bool full) : _full(full) {}; 1161 }; 1162 1163 void GenCollectedHeap::gc_prologue(bool full) { 1164 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 1165 1166 always_do_update_barrier = false; 1167 // Fill TLAB's and such 1168 CollectedHeap::accumulate_statistics_all_tlabs(); 1169 ensure_parsability(true); // retire TLABs 1170 1171 // Walk generations 1172 GenGCPrologueClosure blk(full); 1173 generation_iterate(&blk, false); // not old-to-young. 1174 }; 1175 1176 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure { 1177 private: 1178 bool _full; 1179 public: 1180 void do_generation(Generation* gen) { 1181 gen->gc_epilogue(_full); 1182 } 1183 GenGCEpilogueClosure(bool full) : _full(full) {}; 1184 }; 1185 1186 void GenCollectedHeap::gc_epilogue(bool full) { 1187 #if defined(COMPILER2) || INCLUDE_JVMCI 1188 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 1189 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr())); 1190 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps"); 1191 #endif /* COMPILER2 || INCLUDE_JVMCI */ 1192 1193 resize_all_tlabs(); 1194 1195 GenGCEpilogueClosure blk(full); 1196 generation_iterate(&blk, false); // not old-to-young. 1197 1198 if (!CleanChunkPoolAsync) { 1199 Chunk::clean_chunk_pool(); 1200 } 1201 1202 MetaspaceCounters::update_performance_counters(); 1203 CompressedClassSpaceCounters::update_performance_counters(); 1204 1205 always_do_update_barrier = UseConcMarkSweepGC; 1206 }; 1207 1208 #ifndef PRODUCT 1209 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure { 1210 private: 1211 public: 1212 void do_generation(Generation* gen) { 1213 gen->record_spaces_top(); 1214 } 1215 }; 1216 1217 void GenCollectedHeap::record_gen_tops_before_GC() { 1218 if (ZapUnusedHeapArea) { 1219 GenGCSaveTopsBeforeGCClosure blk; 1220 generation_iterate(&blk, false); // not old-to-young. 1221 } 1222 } 1223 #endif // not PRODUCT 1224 1225 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure { 1226 public: 1227 void do_generation(Generation* gen) { 1228 gen->ensure_parsability(); 1229 } 1230 }; 1231 1232 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) { 1233 CollectedHeap::ensure_parsability(retire_tlabs); 1234 GenEnsureParsabilityClosure ep_cl; 1235 generation_iterate(&ep_cl, false); 1236 } 1237 1238 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen, 1239 oop obj, 1240 size_t obj_size) { 1241 guarantee(old_gen == _old_gen, "We only get here with an old generation"); 1242 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in"); 1243 HeapWord* result = NULL; 1244 1245 result = old_gen->expand_and_allocate(obj_size, false); 1246 1247 if (result != NULL) { 1248 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size); 1249 } 1250 return oop(result); 1251 } 1252 1253 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure { 1254 jlong _time; // in ms 1255 jlong _now; // in ms 1256 1257 public: 1258 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { } 1259 1260 jlong time() { return _time; } 1261 1262 void do_generation(Generation* gen) { 1263 _time = MIN2(_time, gen->time_of_last_gc(_now)); 1264 } 1265 }; 1266 1267 jlong GenCollectedHeap::millis_since_last_gc() { 1268 // We need a monotonically non-decreasing time in ms but 1269 // os::javaTimeMillis() does not guarantee monotonicity. 1270 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 1271 GenTimeOfLastGCClosure tolgc_cl(now); 1272 // iterate over generations getting the oldest 1273 // time that a generation was collected 1274 generation_iterate(&tolgc_cl, false); 1275 1276 // javaTimeNanos() is guaranteed to be monotonically non-decreasing 1277 // provided the underlying platform provides such a time source 1278 // (and it is bug free). So we still have to guard against getting 1279 // back a time later than 'now'. 1280 jlong retVal = now - tolgc_cl.time(); 1281 if (retVal < 0) { 1282 NOT_PRODUCT(warning("time warp: " JLONG_FORMAT, retVal);) 1283 return 0; 1284 } 1285 return retVal; 1286 } 1287 1288 void GenCollectedHeap::stop() { 1289 #if INCLUDE_ALL_GCS 1290 if (UseConcMarkSweepGC) { 1291 ConcurrentMarkSweepThread::stop(); 1292 } 1293 #endif 1294 }