1 /* 2 * Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/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 gen_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 if (!prepared_for_verification && run_verification && 485 VerifyGCLevel <= 1 && VerifyBeforeGC) { 486 prepare_for_verify(); 487 } 488 489 if (do_young_collection) { 490 // We did a young GC. Need a new GC id for the old GC. 491 GCIdMarkAndRestore gc_id_mark; 492 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true); 493 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true); 494 } else { 495 // No young GC done. Use the same GC id as was set up earlier in this method. 496 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true); 497 } 498 499 must_restore_marks_for_biased_locking = true; 500 collected_old = true; 501 } 502 503 // Update "complete" boolean wrt what actually transpired -- 504 // for instance, a promotion failure could have led to 505 // a whole heap collection. 506 complete = complete || collected_old; 507 508 print_heap_change(young_prev_used, old_prev_used); 509 MetaspaceAux::print_metaspace_change(metadata_prev_used); 510 511 // Adjust generation sizes. 512 if (collected_old) { 513 _old_gen->compute_new_size(); 514 } 515 _young_gen->compute_new_size(); 516 517 if (complete) { 518 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 519 ClassLoaderDataGraph::purge(); 520 MetaspaceAux::verify_metrics(); 521 // Resize the metaspace capacity after full collections 522 MetaspaceGC::compute_new_size(); 523 update_full_collections_completed(); 524 } 525 526 // Track memory usage and detect low memory after GC finishes 527 MemoryService::track_memory_usage(); 528 529 gc_epilogue(complete); 530 531 if (must_restore_marks_for_biased_locking) { 532 BiasedLocking::restore_marks(); 533 } 534 } 535 536 print_heap_after_gc(); 537 538 #ifdef TRACESPINNING 539 ParallelTaskTerminator::print_termination_counts(); 540 #endif 541 } 542 543 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) { 544 return gen_policy()->satisfy_failed_allocation(size, is_tlab); 545 } 546 547 #ifdef ASSERT 548 class AssertNonScavengableClosure: public OopClosure { 549 public: 550 virtual void do_oop(oop* p) { 551 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p), 552 "Referent should not be scavengable."); } 553 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); } 554 }; 555 static AssertNonScavengableClosure assert_is_non_scavengable_closure; 556 #endif 557 558 void GenCollectedHeap::process_roots(StrongRootsScope* scope, 559 ScanningOption so, 560 OopClosure* strong_roots, 561 OopClosure* weak_roots, 562 CLDClosure* strong_cld_closure, 563 CLDClosure* weak_cld_closure, 564 CodeBlobClosure* code_roots) { 565 // General roots. 566 assert(Threads::thread_claim_parity() != 0, "must have called prologue code"); 567 assert(code_roots != NULL, "code root closure should always be set"); 568 // _n_termination for _process_strong_tasks should be set up stream 569 // in a method not running in a GC worker. Otherwise the GC worker 570 // could be trying to change the termination condition while the task 571 // is executing in another GC worker. 572 573 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) { 574 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure); 575 } 576 577 // Some CLDs contained in the thread frames should be considered strong. 578 // Don't process them if they will be processed during the ClassLoaderDataGraph phase. 579 CLDClosure* roots_from_clds_p = (strong_cld_closure != weak_cld_closure) ? strong_cld_closure : NULL; 580 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway 581 CodeBlobClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots; 582 583 bool is_par = scope->n_threads() > 1; 584 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_clds_p, roots_from_code_p); 585 586 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) { 587 Universe::oops_do(strong_roots); 588 } 589 // Global (strong) JNI handles 590 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) { 591 JNIHandles::oops_do(strong_roots); 592 } 593 594 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) { 595 ObjectSynchronizer::oops_do(strong_roots); 596 } 597 if (!_process_strong_tasks->is_task_claimed(GCH_PS_FlatProfiler_oops_do)) { 598 FlatProfiler::oops_do(strong_roots); 599 } 600 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) { 601 Management::oops_do(strong_roots); 602 } 603 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) { 604 JvmtiExport::oops_do(strong_roots); 605 } 606 607 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) { 608 SystemDictionary::roots_oops_do(strong_roots, weak_roots); 609 } 610 611 // All threads execute the following. A specific chunk of buckets 612 // from the StringTable are the individual tasks. 613 if (weak_roots != NULL) { 614 if (is_par) { 615 StringTable::possibly_parallel_oops_do(weak_roots); 616 } else { 617 StringTable::oops_do(weak_roots); 618 } 619 } 620 621 if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) { 622 if (so & SO_ScavengeCodeCache) { 623 assert(code_roots != NULL, "must supply closure for code cache"); 624 625 // We only visit parts of the CodeCache when scavenging. 626 CodeCache::scavenge_root_nmethods_do(code_roots); 627 } 628 if (so & SO_AllCodeCache) { 629 assert(code_roots != NULL, "must supply closure for code cache"); 630 631 // CMSCollector uses this to do intermediate-strength collections. 632 // We scan the entire code cache, since CodeCache::do_unloading is not called. 633 CodeCache::blobs_do(code_roots); 634 } 635 // Verify that the code cache contents are not subject to 636 // movement by a scavenging collection. 637 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations)); 638 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable)); 639 } 640 } 641 642 void GenCollectedHeap::gen_process_roots(StrongRootsScope* scope, 643 GenerationType type, 644 bool young_gen_as_roots, 645 ScanningOption so, 646 bool only_strong_roots, 647 OopsInGenClosure* not_older_gens, 648 OopsInGenClosure* older_gens, 649 CLDClosure* cld_closure) { 650 const bool is_adjust_phase = !only_strong_roots && !young_gen_as_roots; 651 652 bool is_moving_collection = false; 653 if (type == YoungGen || is_adjust_phase) { 654 // young collections are always moving 655 is_moving_collection = true; 656 } 657 658 MarkingCodeBlobClosure mark_code_closure(not_older_gens, is_moving_collection); 659 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : not_older_gens; 660 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure; 661 662 process_roots(scope, so, 663 not_older_gens, weak_roots, 664 cld_closure, weak_cld_closure, 665 &mark_code_closure); 666 667 if (young_gen_as_roots) { 668 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) { 669 if (type == OldGen) { 670 not_older_gens->set_generation(_young_gen); 671 _young_gen->oop_iterate(not_older_gens); 672 } 673 not_older_gens->reset_generation(); 674 } 675 } 676 // When collection is parallel, all threads get to cooperate to do 677 // old generation scanning. 678 if (type == YoungGen) { 679 older_gens->set_generation(_old_gen); 680 rem_set()->younger_refs_iterate(_old_gen, older_gens, scope->n_threads()); 681 older_gens->reset_generation(); 682 } 683 684 _process_strong_tasks->all_tasks_completed(scope->n_threads()); 685 } 686 687 688 class AlwaysTrueClosure: public BoolObjectClosure { 689 public: 690 bool do_object_b(oop p) { return true; } 691 }; 692 static AlwaysTrueClosure always_true; 693 694 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) { 695 JNIHandles::weak_oops_do(&always_true, root_closure); 696 _young_gen->ref_processor()->weak_oops_do(root_closure); 697 _old_gen->ref_processor()->weak_oops_do(root_closure); 698 } 699 700 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \ 701 void GenCollectedHeap:: \ 702 oop_since_save_marks_iterate(GenerationType gen, \ 703 OopClosureType* cur, \ 704 OopClosureType* older) { \ 705 if (gen == YoungGen) { \ 706 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \ 707 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \ 708 } else { \ 709 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \ 710 } \ 711 } 712 713 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN) 714 715 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN 716 717 bool GenCollectedHeap::no_allocs_since_save_marks() { 718 return _young_gen->no_allocs_since_save_marks() && 719 _old_gen->no_allocs_since_save_marks(); 720 } 721 722 bool GenCollectedHeap::supports_inline_contig_alloc() const { 723 return _young_gen->supports_inline_contig_alloc(); 724 } 725 726 HeapWord** GenCollectedHeap::top_addr() const { 727 return _young_gen->top_addr(); 728 } 729 730 HeapWord** GenCollectedHeap::end_addr() const { 731 return _young_gen->end_addr(); 732 } 733 734 // public collection interfaces 735 736 void GenCollectedHeap::collect(GCCause::Cause cause) { 737 if (should_do_concurrent_full_gc(cause)) { 738 #if INCLUDE_ALL_GCS 739 // Mostly concurrent full collection. 740 collect_mostly_concurrent(cause); 741 #else // INCLUDE_ALL_GCS 742 ShouldNotReachHere(); 743 #endif // INCLUDE_ALL_GCS 744 } else if (cause == GCCause::_wb_young_gc) { 745 // Young collection for the WhiteBox API. 746 collect(cause, YoungGen); 747 } else { 748 #ifdef ASSERT 749 if (cause == GCCause::_scavenge_alot) { 750 // Young collection only. 751 collect(cause, YoungGen); 752 } else { 753 // Stop-the-world full collection. 754 collect(cause, OldGen); 755 } 756 #else 757 // Stop-the-world full collection. 758 collect(cause, OldGen); 759 #endif 760 } 761 } 762 763 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) { 764 // The caller doesn't have the Heap_lock 765 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock"); 766 MutexLocker ml(Heap_lock); 767 collect_locked(cause, max_generation); 768 } 769 770 void GenCollectedHeap::collect_locked(GCCause::Cause cause) { 771 // The caller has the Heap_lock 772 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock"); 773 collect_locked(cause, OldGen); 774 } 775 776 // this is the private collection interface 777 // The Heap_lock is expected to be held on entry. 778 779 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) { 780 // Read the GC count while holding the Heap_lock 781 unsigned int gc_count_before = total_collections(); 782 unsigned int full_gc_count_before = total_full_collections(); 783 { 784 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back 785 VM_GenCollectFull op(gc_count_before, full_gc_count_before, 786 cause, max_generation); 787 VMThread::execute(&op); 788 } 789 } 790 791 #if INCLUDE_ALL_GCS 792 bool GenCollectedHeap::create_cms_collector() { 793 794 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep, 795 "Unexpected generation kinds"); 796 // Skip two header words in the block content verification 797 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();) 798 assert(_gen_policy->is_concurrent_mark_sweep_policy(), "Unexpected policy type"); 799 CMSCollector* collector = 800 new CMSCollector((ConcurrentMarkSweepGeneration*)_old_gen, 801 _rem_set, 802 _gen_policy->as_concurrent_mark_sweep_policy()); 803 804 if (collector == NULL || !collector->completed_initialization()) { 805 if (collector) { 806 delete collector; // Be nice in embedded situation 807 } 808 vm_shutdown_during_initialization("Could not create CMS collector"); 809 return false; 810 } 811 return true; // success 812 } 813 814 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) { 815 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock"); 816 817 MutexLocker ml(Heap_lock); 818 // Read the GC counts while holding the Heap_lock 819 unsigned int full_gc_count_before = total_full_collections(); 820 unsigned int gc_count_before = total_collections(); 821 { 822 MutexUnlocker mu(Heap_lock); 823 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause); 824 VMThread::execute(&op); 825 } 826 } 827 #endif // INCLUDE_ALL_GCS 828 829 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) { 830 do_full_collection(clear_all_soft_refs, OldGen); 831 } 832 833 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs, 834 GenerationType last_generation) { 835 GenerationType local_last_generation; 836 if (!incremental_collection_will_fail(false /* don't consult_young */) && 837 gc_cause() == GCCause::_gc_locker) { 838 local_last_generation = YoungGen; 839 } else { 840 local_last_generation = last_generation; 841 } 842 843 do_collection(true, // full 844 clear_all_soft_refs, // clear_all_soft_refs 845 0, // size 846 false, // is_tlab 847 local_last_generation); // last_generation 848 // Hack XXX FIX ME !!! 849 // A scavenge may not have been attempted, or may have 850 // been attempted and failed, because the old gen was too full 851 if (local_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker && 852 incremental_collection_will_fail(false /* don't consult_young */)) { 853 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed"); 854 // This time allow the old gen to be collected as well 855 do_collection(true, // full 856 clear_all_soft_refs, // clear_all_soft_refs 857 0, // size 858 false, // is_tlab 859 OldGen); // last_generation 860 } 861 } 862 863 bool GenCollectedHeap::is_in_young(oop p) { 864 bool result = ((HeapWord*)p) < _old_gen->reserved().start(); 865 assert(result == _young_gen->is_in_reserved(p), 866 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p)); 867 return result; 868 } 869 870 // Returns "TRUE" iff "p" points into the committed areas of the heap. 871 bool GenCollectedHeap::is_in(const void* p) const { 872 return _young_gen->is_in(p) || _old_gen->is_in(p); 873 } 874 875 #ifdef ASSERT 876 // Don't implement this by using is_in_young(). This method is used 877 // in some cases to check that is_in_young() is correct. 878 bool GenCollectedHeap::is_in_partial_collection(const void* p) { 879 assert(is_in_reserved(p) || p == NULL, 880 "Does not work if address is non-null and outside of the heap"); 881 return p < _young_gen->reserved().end() && p != NULL; 882 } 883 #endif 884 885 void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) { 886 NoHeaderExtendedOopClosure no_header_cl(cl); 887 oop_iterate(&no_header_cl); 888 } 889 890 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) { 891 _young_gen->oop_iterate(cl); 892 _old_gen->oop_iterate(cl); 893 } 894 895 void GenCollectedHeap::object_iterate(ObjectClosure* cl) { 896 _young_gen->object_iterate(cl); 897 _old_gen->object_iterate(cl); 898 } 899 900 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) { 901 _young_gen->safe_object_iterate(cl); 902 _old_gen->safe_object_iterate(cl); 903 } 904 905 Space* GenCollectedHeap::space_containing(const void* addr) const { 906 Space* res = _young_gen->space_containing(addr); 907 if (res != NULL) { 908 return res; 909 } 910 res = _old_gen->space_containing(addr); 911 assert(res != NULL, "Could not find containing space"); 912 return res; 913 } 914 915 HeapWord* GenCollectedHeap::block_start(const void* addr) const { 916 assert(is_in_reserved(addr), "block_start of address outside of heap"); 917 if (_young_gen->is_in_reserved(addr)) { 918 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation"); 919 return _young_gen->block_start(addr); 920 } 921 922 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 923 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation"); 924 return _old_gen->block_start(addr); 925 } 926 927 size_t GenCollectedHeap::block_size(const HeapWord* addr) const { 928 assert(is_in_reserved(addr), "block_size of address outside of heap"); 929 if (_young_gen->is_in_reserved(addr)) { 930 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation"); 931 return _young_gen->block_size(addr); 932 } 933 934 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 935 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation"); 936 return _old_gen->block_size(addr); 937 } 938 939 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const { 940 assert(is_in_reserved(addr), "block_is_obj of address outside of heap"); 941 assert(block_start(addr) == addr, "addr must be a block start"); 942 if (_young_gen->is_in_reserved(addr)) { 943 return _young_gen->block_is_obj(addr); 944 } 945 946 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 947 return _old_gen->block_is_obj(addr); 948 } 949 950 bool GenCollectedHeap::supports_tlab_allocation() const { 951 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 952 return _young_gen->supports_tlab_allocation(); 953 } 954 955 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const { 956 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 957 if (_young_gen->supports_tlab_allocation()) { 958 return _young_gen->tlab_capacity(); 959 } 960 return 0; 961 } 962 963 size_t GenCollectedHeap::tlab_used(Thread* thr) const { 964 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 965 if (_young_gen->supports_tlab_allocation()) { 966 return _young_gen->tlab_used(); 967 } 968 return 0; 969 } 970 971 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const { 972 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 973 if (_young_gen->supports_tlab_allocation()) { 974 return _young_gen->unsafe_max_tlab_alloc(); 975 } 976 return 0; 977 } 978 979 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) { 980 bool gc_overhead_limit_was_exceeded; 981 return gen_policy()->mem_allocate_work(size /* size */, 982 true /* is_tlab */, 983 &gc_overhead_limit_was_exceeded); 984 } 985 986 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size 987 // from the list headed by "*prev_ptr". 988 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) { 989 bool first = true; 990 size_t min_size = 0; // "first" makes this conceptually infinite. 991 ScratchBlock **smallest_ptr, *smallest; 992 ScratchBlock *cur = *prev_ptr; 993 while (cur) { 994 assert(*prev_ptr == cur, "just checking"); 995 if (first || cur->num_words < min_size) { 996 smallest_ptr = prev_ptr; 997 smallest = cur; 998 min_size = smallest->num_words; 999 first = false; 1000 } 1001 prev_ptr = &cur->next; 1002 cur = cur->next; 1003 } 1004 smallest = *smallest_ptr; 1005 *smallest_ptr = smallest->next; 1006 return smallest; 1007 } 1008 1009 // Sort the scratch block list headed by res into decreasing size order, 1010 // and set "res" to the result. 1011 static void sort_scratch_list(ScratchBlock*& list) { 1012 ScratchBlock* sorted = NULL; 1013 ScratchBlock* unsorted = list; 1014 while (unsorted) { 1015 ScratchBlock *smallest = removeSmallestScratch(&unsorted); 1016 smallest->next = sorted; 1017 sorted = smallest; 1018 } 1019 list = sorted; 1020 } 1021 1022 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor, 1023 size_t max_alloc_words) { 1024 ScratchBlock* res = NULL; 1025 _young_gen->contribute_scratch(res, requestor, max_alloc_words); 1026 _old_gen->contribute_scratch(res, requestor, max_alloc_words); 1027 sort_scratch_list(res); 1028 return res; 1029 } 1030 1031 void GenCollectedHeap::release_scratch() { 1032 _young_gen->reset_scratch(); 1033 _old_gen->reset_scratch(); 1034 } 1035 1036 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure { 1037 void do_generation(Generation* gen) { 1038 gen->prepare_for_verify(); 1039 } 1040 }; 1041 1042 void GenCollectedHeap::prepare_for_verify() { 1043 ensure_parsability(false); // no need to retire TLABs 1044 GenPrepareForVerifyClosure blk; 1045 generation_iterate(&blk, false); 1046 } 1047 1048 void GenCollectedHeap::generation_iterate(GenClosure* cl, 1049 bool old_to_young) { 1050 if (old_to_young) { 1051 cl->do_generation(_old_gen); 1052 cl->do_generation(_young_gen); 1053 } else { 1054 cl->do_generation(_young_gen); 1055 cl->do_generation(_old_gen); 1056 } 1057 } 1058 1059 bool GenCollectedHeap::is_maximal_no_gc() const { 1060 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc(); 1061 } 1062 1063 void GenCollectedHeap::save_marks() { 1064 _young_gen->save_marks(); 1065 _old_gen->save_marks(); 1066 } 1067 1068 GenCollectedHeap* GenCollectedHeap::heap() { 1069 CollectedHeap* heap = Universe::heap(); 1070 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()"); 1071 assert(heap->kind() == CollectedHeap::GenCollectedHeap, "Not a GenCollectedHeap"); 1072 return (GenCollectedHeap*)heap; 1073 } 1074 1075 void GenCollectedHeap::prepare_for_compaction() { 1076 // Start by compacting into same gen. 1077 CompactPoint cp(_old_gen); 1078 _old_gen->prepare_for_compaction(&cp); 1079 _young_gen->prepare_for_compaction(&cp); 1080 } 1081 1082 void GenCollectedHeap::verify(VerifyOption option /* ignored */) { 1083 log_debug(gc, verify)("%s", _old_gen->name()); 1084 _old_gen->verify(); 1085 1086 log_debug(gc, verify)("%s", _old_gen->name()); 1087 _young_gen->verify(); 1088 1089 log_debug(gc, verify)("RemSet"); 1090 rem_set()->verify(); 1091 } 1092 1093 void GenCollectedHeap::print_on(outputStream* st) const { 1094 _young_gen->print_on(st); 1095 _old_gen->print_on(st); 1096 MetaspaceAux::print_on(st); 1097 } 1098 1099 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const { 1100 if (workers() != NULL) { 1101 workers()->threads_do(tc); 1102 } 1103 #if INCLUDE_ALL_GCS 1104 if (UseConcMarkSweepGC) { 1105 ConcurrentMarkSweepThread::threads_do(tc); 1106 } 1107 #endif // INCLUDE_ALL_GCS 1108 } 1109 1110 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const { 1111 #if INCLUDE_ALL_GCS 1112 if (UseConcMarkSweepGC) { 1113 workers()->print_worker_threads_on(st); 1114 ConcurrentMarkSweepThread::print_all_on(st); 1115 } 1116 #endif // INCLUDE_ALL_GCS 1117 } 1118 1119 void GenCollectedHeap::print_on_error(outputStream* st) const { 1120 this->CollectedHeap::print_on_error(st); 1121 1122 #if INCLUDE_ALL_GCS 1123 if (UseConcMarkSweepGC) { 1124 st->cr(); 1125 CMSCollector::print_on_error(st); 1126 } 1127 #endif // INCLUDE_ALL_GCS 1128 } 1129 1130 void GenCollectedHeap::print_tracing_info() const { 1131 if (TraceYoungGenTime) { 1132 _young_gen->print_summary_info(); 1133 } 1134 if (TraceOldGenTime) { 1135 _old_gen->print_summary_info(); 1136 } 1137 } 1138 1139 void GenCollectedHeap::print_heap_change(size_t young_prev_used, size_t old_prev_used) const { 1140 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)", 1141 _young_gen->short_name(), young_prev_used / K, _young_gen->used() /K, _young_gen->capacity() /K); 1142 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)", 1143 _old_gen->short_name(), old_prev_used / K, _old_gen->used() /K, _old_gen->capacity() /K); 1144 } 1145 1146 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure { 1147 private: 1148 bool _full; 1149 public: 1150 void do_generation(Generation* gen) { 1151 gen->gc_prologue(_full); 1152 } 1153 GenGCPrologueClosure(bool full) : _full(full) {}; 1154 }; 1155 1156 void GenCollectedHeap::gc_prologue(bool full) { 1157 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 1158 1159 always_do_update_barrier = false; 1160 // Fill TLAB's and such 1161 CollectedHeap::accumulate_statistics_all_tlabs(); 1162 ensure_parsability(true); // retire TLABs 1163 1164 // Walk generations 1165 GenGCPrologueClosure blk(full); 1166 generation_iterate(&blk, false); // not old-to-young. 1167 }; 1168 1169 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure { 1170 private: 1171 bool _full; 1172 public: 1173 void do_generation(Generation* gen) { 1174 gen->gc_epilogue(_full); 1175 } 1176 GenGCEpilogueClosure(bool full) : _full(full) {}; 1177 }; 1178 1179 void GenCollectedHeap::gc_epilogue(bool full) { 1180 #if defined(COMPILER2) || INCLUDE_JVMCI 1181 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 1182 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr())); 1183 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps"); 1184 #endif /* COMPILER2 || INCLUDE_JVMCI */ 1185 1186 resize_all_tlabs(); 1187 1188 GenGCEpilogueClosure blk(full); 1189 generation_iterate(&blk, false); // not old-to-young. 1190 1191 if (!CleanChunkPoolAsync) { 1192 Chunk::clean_chunk_pool(); 1193 } 1194 1195 MetaspaceCounters::update_performance_counters(); 1196 CompressedClassSpaceCounters::update_performance_counters(); 1197 1198 always_do_update_barrier = UseConcMarkSweepGC; 1199 }; 1200 1201 #ifndef PRODUCT 1202 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure { 1203 private: 1204 public: 1205 void do_generation(Generation* gen) { 1206 gen->record_spaces_top(); 1207 } 1208 }; 1209 1210 void GenCollectedHeap::record_gen_tops_before_GC() { 1211 if (ZapUnusedHeapArea) { 1212 GenGCSaveTopsBeforeGCClosure blk; 1213 generation_iterate(&blk, false); // not old-to-young. 1214 } 1215 } 1216 #endif // not PRODUCT 1217 1218 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure { 1219 public: 1220 void do_generation(Generation* gen) { 1221 gen->ensure_parsability(); 1222 } 1223 }; 1224 1225 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) { 1226 CollectedHeap::ensure_parsability(retire_tlabs); 1227 GenEnsureParsabilityClosure ep_cl; 1228 generation_iterate(&ep_cl, false); 1229 } 1230 1231 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen, 1232 oop obj, 1233 size_t obj_size) { 1234 guarantee(old_gen == _old_gen, "We only get here with an old generation"); 1235 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in"); 1236 HeapWord* result = NULL; 1237 1238 result = old_gen->expand_and_allocate(obj_size, false); 1239 1240 if (result != NULL) { 1241 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size); 1242 } 1243 return oop(result); 1244 } 1245 1246 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure { 1247 jlong _time; // in ms 1248 jlong _now; // in ms 1249 1250 public: 1251 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { } 1252 1253 jlong time() { return _time; } 1254 1255 void do_generation(Generation* gen) { 1256 _time = MIN2(_time, gen->time_of_last_gc(_now)); 1257 } 1258 }; 1259 1260 jlong GenCollectedHeap::millis_since_last_gc() { 1261 // We need a monotonically non-decreasing time in ms but 1262 // os::javaTimeMillis() does not guarantee monotonicity. 1263 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 1264 GenTimeOfLastGCClosure tolgc_cl(now); 1265 // iterate over generations getting the oldest 1266 // time that a generation was collected 1267 generation_iterate(&tolgc_cl, false); 1268 1269 // javaTimeNanos() is guaranteed to be monotonically non-decreasing 1270 // provided the underlying platform provides such a time source 1271 // (and it is bug free). So we still have to guard against getting 1272 // back a time later than 'now'. 1273 jlong retVal = now - tolgc_cl.time(); 1274 if (retVal < 0) { 1275 NOT_PRODUCT(warning("time warp: " JLONG_FORMAT, retVal);) 1276 return 0; 1277 } 1278 return retVal; 1279 } 1280 1281 void GenCollectedHeap::stop() { 1282 #if INCLUDE_ALL_GCS 1283 if (UseConcMarkSweepGC) { 1284 ConcurrentMarkSweepThread::stop(); 1285 } 1286 #endif 1287 }