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); 170 171 os::trace_page_sizes("Heap", 172 collector_policy()->min_heap_byte_size(), 173 total_reserved, 174 alignment, 175 heap_rs->base(), 176 heap_rs->size()); 177 178 return heap_rs->base(); 179 } 180 181 void GenCollectedHeap::post_initialize() { 182 ref_processing_init(); 183 assert((_young_gen->kind() == Generation::DefNew) || 184 (_young_gen->kind() == Generation::ParNew), 185 "Wrong youngest generation type"); 186 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen; 187 188 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep || 189 _old_gen->kind() == Generation::MarkSweepCompact, 190 "Wrong generation kind"); 191 192 _gen_policy->initialize_size_policy(def_new_gen->eden()->capacity(), 193 _old_gen->capacity(), 194 def_new_gen->from()->capacity()); 195 _gen_policy->initialize_gc_policy_counters(); 196 } 197 198 void GenCollectedHeap::ref_processing_init() { 199 _young_gen->ref_processor_init(); 200 _old_gen->ref_processor_init(); 201 } 202 203 size_t GenCollectedHeap::capacity() const { 204 return _young_gen->capacity() + _old_gen->capacity(); 205 } 206 207 size_t GenCollectedHeap::used() const { 208 return _young_gen->used() + _old_gen->used(); 209 } 210 211 void GenCollectedHeap::save_used_regions() { 212 _old_gen->save_used_region(); 213 _young_gen->save_used_region(); 214 } 215 216 size_t GenCollectedHeap::max_capacity() const { 217 return _young_gen->max_capacity() + _old_gen->max_capacity(); 218 } 219 220 // Update the _full_collections_completed counter 221 // at the end of a stop-world full GC. 222 unsigned int GenCollectedHeap::update_full_collections_completed() { 223 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 224 assert(_full_collections_completed <= _total_full_collections, 225 "Can't complete more collections than were started"); 226 _full_collections_completed = _total_full_collections; 227 ml.notify_all(); 228 return _full_collections_completed; 229 } 230 231 // Update the _full_collections_completed counter, as appropriate, 232 // at the end of a concurrent GC cycle. Note the conditional update 233 // below to allow this method to be called by a concurrent collector 234 // without synchronizing in any manner with the VM thread (which 235 // may already have initiated a STW full collection "concurrently"). 236 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) { 237 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 238 assert((_full_collections_completed <= _total_full_collections) && 239 (count <= _total_full_collections), 240 "Can't complete more collections than were started"); 241 if (count > _full_collections_completed) { 242 _full_collections_completed = count; 243 ml.notify_all(); 244 } 245 return _full_collections_completed; 246 } 247 248 249 #ifndef PRODUCT 250 // Override of memory state checking method in CollectedHeap: 251 // Some collectors (CMS for example) can't have badHeapWordVal written 252 // in the first two words of an object. (For instance , in the case of 253 // CMS these words hold state used to synchronize between certain 254 // (concurrent) GC steps and direct allocating mutators.) 255 // The skip_header_HeapWords() method below, allows us to skip 256 // over the requisite number of HeapWord's. Note that (for 257 // generational collectors) this means that those many words are 258 // skipped in each object, irrespective of the generation in which 259 // that object lives. The resultant loss of precision seems to be 260 // harmless and the pain of avoiding that imprecision appears somewhat 261 // higher than we are prepared to pay for such rudimentary debugging 262 // support. 263 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr, 264 size_t size) { 265 if (CheckMemoryInitialization && ZapUnusedHeapArea) { 266 // We are asked to check a size in HeapWords, 267 // but the memory is mangled in juint words. 268 juint* start = (juint*) (addr + skip_header_HeapWords()); 269 juint* end = (juint*) (addr + size); 270 for (juint* slot = start; slot < end; slot += 1) { 271 assert(*slot == badHeapWordVal, 272 "Found non badHeapWordValue in pre-allocation check"); 273 } 274 } 275 } 276 #endif 277 278 HeapWord* GenCollectedHeap::attempt_allocation(size_t size, 279 bool is_tlab, 280 bool first_only) { 281 HeapWord* res = NULL; 282 283 if (_young_gen->should_allocate(size, is_tlab)) { 284 res = _young_gen->allocate(size, is_tlab); 285 if (res != NULL || first_only) { 286 return res; 287 } 288 } 289 290 if (_old_gen->should_allocate(size, is_tlab)) { 291 res = _old_gen->allocate(size, is_tlab); 292 } 293 294 return res; 295 } 296 297 HeapWord* GenCollectedHeap::mem_allocate(size_t size, 298 bool* gc_overhead_limit_was_exceeded) { 299 return gen_policy()->mem_allocate_work(size, 300 false /* is_tlab */, 301 gc_overhead_limit_was_exceeded); 302 } 303 304 bool GenCollectedHeap::must_clear_all_soft_refs() { 305 return _gc_cause == GCCause::_metadata_GC_clear_soft_refs || 306 _gc_cause == GCCause::_wb_full_gc; 307 } 308 309 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 310 if (!UseConcMarkSweepGC) { 311 return false; 312 } 313 314 switch (cause) { 315 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 316 case GCCause::_java_lang_system_gc: 317 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 318 default: return false; 319 } 320 } 321 322 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size, 323 bool is_tlab, bool run_verification, bool clear_soft_refs, 324 bool restore_marks_for_biased_locking) { 325 FormatBuffer<> title("Collect gen: %s", gen->short_name()); 326 GCTraceTime(Trace, gc, phases) t1(title); 327 TraceCollectorStats tcs(gen->counters()); 328 TraceMemoryManagerStats tmms(gen->kind(),gc_cause()); 329 330 gen->stat_record()->invocations++; 331 gen->stat_record()->accumulated_time.start(); 332 333 // Must be done anew before each collection because 334 // a previous collection will do mangling and will 335 // change top of some spaces. 336 record_gen_tops_before_GC(); 337 338 log_trace(gc)("%s invoke=%d size=" SIZE_FORMAT, heap()->is_young_gen(gen) ? "Young" : "Old", gen->stat_record()->invocations, size * HeapWordSize); 339 340 if (run_verification && VerifyBeforeGC) { 341 HandleMark hm; // Discard invalid handles created during verification 342 Universe::verify("Before GC"); 343 } 344 COMPILER2_PRESENT(DerivedPointerTable::clear()); 345 346 if (restore_marks_for_biased_locking) { 347 // We perform this mark word preservation work lazily 348 // because it's only at this point that we know whether we 349 // absolutely have to do it; we want to avoid doing it for 350 // scavenge-only collections where it's unnecessary 351 BiasedLocking::preserve_marks(); 352 } 353 354 // Do collection work 355 { 356 // Note on ref discovery: For what appear to be historical reasons, 357 // GCH enables and disabled (by enqueing) refs discovery. 358 // In the future this should be moved into the generation's 359 // collect method so that ref discovery and enqueueing concerns 360 // are local to a generation. The collect method could return 361 // an appropriate indication in the case that notification on 362 // the ref lock was needed. This will make the treatment of 363 // weak refs more uniform (and indeed remove such concerns 364 // from GCH). XXX 365 366 HandleMark hm; // Discard invalid handles created during gc 367 save_marks(); // save marks for all gens 368 // We want to discover references, but not process them yet. 369 // This mode is disabled in process_discovered_references if the 370 // generation does some collection work, or in 371 // enqueue_discovered_references if the generation returns 372 // without doing any work. 373 ReferenceProcessor* rp = gen->ref_processor(); 374 // If the discovery of ("weak") refs in this generation is 375 // atomic wrt other collectors in this configuration, we 376 // are guaranteed to have empty discovered ref lists. 377 if (rp->discovery_is_atomic()) { 378 rp->enable_discovery(); 379 rp->setup_policy(clear_soft_refs); 380 } else { 381 // collect() below will enable discovery as appropriate 382 } 383 gen->collect(full, clear_soft_refs, size, is_tlab); 384 if (!rp->enqueuing_is_done()) { 385 rp->enqueue_discovered_references(); 386 } else { 387 rp->set_enqueuing_is_done(false); 388 } 389 rp->verify_no_references_recorded(); 390 } 391 392 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 393 394 gen->stat_record()->accumulated_time.stop(); 395 396 update_gc_stats(gen, full); 397 398 if (run_verification && VerifyAfterGC) { 399 HandleMark hm; // Discard invalid handles created during verification 400 Universe::verify("After GC"); 401 } 402 } 403 404 void GenCollectedHeap::do_collection(bool full, 405 bool clear_all_soft_refs, 406 size_t size, 407 bool is_tlab, 408 GenerationType max_generation) { 409 ResourceMark rm; 410 DEBUG_ONLY(Thread* my_thread = Thread::current();) 411 412 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 413 assert(my_thread->is_VM_thread() || 414 my_thread->is_ConcurrentGC_thread(), 415 "incorrect thread type capability"); 416 assert(Heap_lock->is_locked(), 417 "the requesting thread should have the Heap_lock"); 418 guarantee(!is_gc_active(), "collection is not reentrant"); 419 420 if (GCLocker::check_active_before_gc()) { 421 return; // GC is disabled (e.g. JNI GetXXXCritical operation) 422 } 423 424 GCIdMarkAndRestore gc_id_mark; 425 426 const bool do_clear_all_soft_refs = clear_all_soft_refs || 427 collector_policy()->should_clear_all_soft_refs(); 428 429 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 430 431 const size_t metadata_prev_used = MetaspaceAux::used_bytes(); 432 433 print_heap_before_gc(); 434 435 { 436 FlagSetting fl(_is_gc_active, true); 437 438 bool complete = full && (max_generation == OldGen); 439 bool old_collects_young = complete && !ScavengeBeforeFullGC; 440 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab); 441 442 FormatBuffer<> gc_string("%s", "Pause "); 443 if (do_young_collection) { 444 gc_string.append("Young"); 445 } else { 446 gc_string.append("Full"); 447 } 448 449 GCTraceCPUTime tcpu; 450 GCTraceTime(Info, gc) t(gc_string, NULL, gc_cause(), true); 451 452 gc_prologue(complete); 453 increment_total_collections(complete); 454 455 size_t young_prev_used = _young_gen->used(); 456 size_t old_prev_used = _old_gen->used(); 457 458 bool run_verification = total_collections() >= VerifyGCStartAt; 459 460 bool prepared_for_verification = false; 461 bool collected_old = false; 462 463 if (do_young_collection) { 464 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) { 465 prepare_for_verify(); 466 prepared_for_verification = true; 467 } 468 469 collect_generation(_young_gen, 470 full, 471 size, 472 is_tlab, 473 run_verification && VerifyGCLevel <= 0, 474 do_clear_all_soft_refs, 475 false); 476 477 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) && 478 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) { 479 // Allocation request was met by young GC. 480 size = 0; 481 } 482 } 483 484 bool must_restore_marks_for_biased_locking = false; 485 486 if (max_generation == OldGen && _old_gen->should_collect(full, size, is_tlab)) { 487 if (!complete) { 488 // The full_collections increment was missed above. 489 increment_total_full_collections(); 490 } 491 492 if (!prepared_for_verification && run_verification && 493 VerifyGCLevel <= 1 && VerifyBeforeGC) { 494 prepare_for_verify(); 495 } 496 497 if (do_young_collection) { 498 // We did a young GC. Need a new GC id for the old GC. 499 GCIdMarkAndRestore gc_id_mark; 500 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true); 501 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true); 502 } else { 503 // No young GC done. Use the same GC id as was set up earlier in this method. 504 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true); 505 } 506 507 must_restore_marks_for_biased_locking = true; 508 collected_old = true; 509 } 510 511 // Update "complete" boolean wrt what actually transpired -- 512 // for instance, a promotion failure could have led to 513 // a whole heap collection. 514 complete = complete || collected_old; 515 516 print_heap_change(young_prev_used, old_prev_used); 517 MetaspaceAux::print_metaspace_change(metadata_prev_used); 518 519 // Adjust generation sizes. 520 if (collected_old) { 521 _old_gen->compute_new_size(); 522 } 523 _young_gen->compute_new_size(); 524 525 if (complete) { 526 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 527 ClassLoaderDataGraph::purge(); 528 MetaspaceAux::verify_metrics(); 529 // Resize the metaspace capacity after full collections 530 MetaspaceGC::compute_new_size(); 531 update_full_collections_completed(); 532 } 533 534 // Track memory usage and detect low memory after GC finishes 535 MemoryService::track_memory_usage(); 536 537 gc_epilogue(complete); 538 539 if (must_restore_marks_for_biased_locking) { 540 BiasedLocking::restore_marks(); 541 } 542 } 543 544 print_heap_after_gc(); 545 546 #ifdef TRACESPINNING 547 ParallelTaskTerminator::print_termination_counts(); 548 #endif 549 } 550 551 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) { 552 return gen_policy()->satisfy_failed_allocation(size, is_tlab); 553 } 554 555 #ifdef ASSERT 556 class AssertNonScavengableClosure: public OopClosure { 557 public: 558 virtual void do_oop(oop* p) { 559 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p), 560 "Referent should not be scavengable."); } 561 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); } 562 }; 563 static AssertNonScavengableClosure assert_is_non_scavengable_closure; 564 #endif 565 566 void GenCollectedHeap::process_roots(StrongRootsScope* scope, 567 ScanningOption so, 568 OopClosure* strong_roots, 569 OopClosure* weak_roots, 570 CLDClosure* strong_cld_closure, 571 CLDClosure* weak_cld_closure, 572 CodeBlobToOopClosure* code_roots) { 573 // General roots. 574 assert(Threads::thread_claim_parity() != 0, "must have called prologue code"); 575 assert(code_roots != NULL, "code root closure should always be set"); 576 // _n_termination for _process_strong_tasks should be set up stream 577 // in a method not running in a GC worker. Otherwise the GC worker 578 // could be trying to change the termination condition while the task 579 // is executing in another GC worker. 580 581 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) { 582 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure); 583 } 584 585 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway 586 CodeBlobToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots; 587 588 bool is_par = scope->n_threads() > 1; 589 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_code_p); 590 591 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) { 592 Universe::oops_do(strong_roots); 593 } 594 // Global (strong) JNI handles 595 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) { 596 JNIHandles::oops_do(strong_roots); 597 } 598 599 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) { 600 ObjectSynchronizer::oops_do(strong_roots); 601 } 602 if (!_process_strong_tasks->is_task_claimed(GCH_PS_FlatProfiler_oops_do)) { 603 FlatProfiler::oops_do(strong_roots); 604 } 605 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) { 606 Management::oops_do(strong_roots); 607 } 608 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) { 609 JvmtiExport::oops_do(strong_roots); 610 } 611 612 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) { 613 SystemDictionary::roots_oops_do(strong_roots, weak_roots); 614 } 615 616 // All threads execute the following. A specific chunk of buckets 617 // from the StringTable are the individual tasks. 618 if (weak_roots != NULL) { 619 if (is_par) { 620 StringTable::possibly_parallel_oops_do(weak_roots); 621 } else { 622 StringTable::oops_do(weak_roots); 623 } 624 } 625 626 if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) { 627 if (so & SO_ScavengeCodeCache) { 628 assert(code_roots != NULL, "must supply closure for code cache"); 629 630 // We only visit parts of the CodeCache when scavenging. 631 CodeCache::scavenge_root_nmethods_do(code_roots); 632 } 633 if (so & SO_AllCodeCache) { 634 assert(code_roots != NULL, "must supply closure for code cache"); 635 636 // CMSCollector uses this to do intermediate-strength collections. 637 // We scan the entire code cache, since CodeCache::do_unloading is not called. 638 CodeCache::blobs_do(code_roots); 639 } 640 // Verify that the code cache contents are not subject to 641 // movement by a scavenging collection. 642 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations)); 643 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable)); 644 } 645 } 646 647 void GenCollectedHeap::gen_process_roots(StrongRootsScope* scope, 648 GenerationType type, 649 bool young_gen_as_roots, 650 ScanningOption so, 651 bool only_strong_roots, 652 OopsInGenClosure* not_older_gens, 653 OopsInGenClosure* older_gens, 654 CLDClosure* cld_closure) { 655 const bool is_adjust_phase = !only_strong_roots && !young_gen_as_roots; 656 657 bool is_moving_collection = false; 658 if (type == YoungGen || is_adjust_phase) { 659 // young collections are always moving 660 is_moving_collection = true; 661 } 662 663 MarkingCodeBlobClosure mark_code_closure(not_older_gens, is_moving_collection); 664 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : not_older_gens; 665 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure; 666 667 process_roots(scope, so, 668 not_older_gens, weak_roots, 669 cld_closure, weak_cld_closure, 670 &mark_code_closure); 671 672 if (young_gen_as_roots) { 673 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) { 674 if (type == OldGen) { 675 not_older_gens->set_generation(_young_gen); 676 _young_gen->oop_iterate(not_older_gens); 677 } 678 not_older_gens->reset_generation(); 679 } 680 } 681 // When collection is parallel, all threads get to cooperate to do 682 // old generation scanning. 683 if (type == YoungGen) { 684 older_gens->set_generation(_old_gen); 685 rem_set()->younger_refs_iterate(_old_gen, older_gens, scope->n_threads()); 686 older_gens->reset_generation(); 687 } 688 689 _process_strong_tasks->all_tasks_completed(scope->n_threads()); 690 } 691 692 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) { 693 JNIHandles::weak_oops_do(root_closure); 694 _young_gen->ref_processor()->weak_oops_do(root_closure); 695 _old_gen->ref_processor()->weak_oops_do(root_closure); 696 } 697 698 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \ 699 void GenCollectedHeap:: \ 700 oop_since_save_marks_iterate(GenerationType gen, \ 701 OopClosureType* cur, \ 702 OopClosureType* older) { \ 703 if (gen == YoungGen) { \ 704 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \ 705 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \ 706 } else { \ 707 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \ 708 } \ 709 } 710 711 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN) 712 713 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN 714 715 bool GenCollectedHeap::no_allocs_since_save_marks() { 716 return _young_gen->no_allocs_since_save_marks() && 717 _old_gen->no_allocs_since_save_marks(); 718 } 719 720 bool GenCollectedHeap::supports_inline_contig_alloc() const { 721 return _young_gen->supports_inline_contig_alloc(); 722 } 723 724 HeapWord** GenCollectedHeap::top_addr() const { 725 return _young_gen->top_addr(); 726 } 727 728 HeapWord** GenCollectedHeap::end_addr() const { 729 return _young_gen->end_addr(); 730 } 731 732 // public collection interfaces 733 734 void GenCollectedHeap::collect(GCCause::Cause cause) { 735 if (should_do_concurrent_full_gc(cause)) { 736 #if INCLUDE_ALL_GCS 737 // Mostly concurrent full collection. 738 collect_mostly_concurrent(cause); 739 #else // INCLUDE_ALL_GCS 740 ShouldNotReachHere(); 741 #endif // INCLUDE_ALL_GCS 742 } else if (cause == GCCause::_wb_young_gc) { 743 // Young collection for the WhiteBox API. 744 collect(cause, YoungGen); 745 } else { 746 #ifdef ASSERT 747 if (cause == GCCause::_scavenge_alot) { 748 // Young collection only. 749 collect(cause, YoungGen); 750 } else { 751 // Stop-the-world full collection. 752 collect(cause, OldGen); 753 } 754 #else 755 // Stop-the-world full collection. 756 collect(cause, OldGen); 757 #endif 758 } 759 } 760 761 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) { 762 // The caller doesn't have the Heap_lock 763 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock"); 764 MutexLocker ml(Heap_lock); 765 collect_locked(cause, max_generation); 766 } 767 768 void GenCollectedHeap::collect_locked(GCCause::Cause cause) { 769 // The caller has the Heap_lock 770 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock"); 771 collect_locked(cause, OldGen); 772 } 773 774 // this is the private collection interface 775 // The Heap_lock is expected to be held on entry. 776 777 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) { 778 // Read the GC count while holding the Heap_lock 779 unsigned int gc_count_before = total_collections(); 780 unsigned int full_gc_count_before = total_full_collections(); 781 { 782 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back 783 VM_GenCollectFull op(gc_count_before, full_gc_count_before, 784 cause, max_generation); 785 VMThread::execute(&op); 786 } 787 } 788 789 #if INCLUDE_ALL_GCS 790 bool GenCollectedHeap::create_cms_collector() { 791 792 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep, 793 "Unexpected generation kinds"); 794 // Skip two header words in the block content verification 795 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();) 796 assert(_gen_policy->is_concurrent_mark_sweep_policy(), "Unexpected policy type"); 797 CMSCollector* collector = 798 new CMSCollector((ConcurrentMarkSweepGeneration*)_old_gen, 799 _rem_set, 800 _gen_policy->as_concurrent_mark_sweep_policy()); 801 802 if (collector == NULL || !collector->completed_initialization()) { 803 if (collector) { 804 delete collector; // Be nice in embedded situation 805 } 806 vm_shutdown_during_initialization("Could not create CMS collector"); 807 return false; 808 } 809 return true; // success 810 } 811 812 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) { 813 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock"); 814 815 MutexLocker ml(Heap_lock); 816 // Read the GC counts while holding the Heap_lock 817 unsigned int full_gc_count_before = total_full_collections(); 818 unsigned int gc_count_before = total_collections(); 819 { 820 MutexUnlocker mu(Heap_lock); 821 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause); 822 VMThread::execute(&op); 823 } 824 } 825 #endif // INCLUDE_ALL_GCS 826 827 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) { 828 do_full_collection(clear_all_soft_refs, OldGen); 829 } 830 831 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs, 832 GenerationType last_generation) { 833 GenerationType local_last_generation; 834 if (!incremental_collection_will_fail(false /* don't consult_young */) && 835 gc_cause() == GCCause::_gc_locker) { 836 local_last_generation = YoungGen; 837 } else { 838 local_last_generation = last_generation; 839 } 840 841 do_collection(true, // full 842 clear_all_soft_refs, // clear_all_soft_refs 843 0, // size 844 false, // is_tlab 845 local_last_generation); // last_generation 846 // Hack XXX FIX ME !!! 847 // A scavenge may not have been attempted, or may have 848 // been attempted and failed, because the old gen was too full 849 if (local_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker && 850 incremental_collection_will_fail(false /* don't consult_young */)) { 851 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed"); 852 // This time allow the old gen to be collected as well 853 do_collection(true, // full 854 clear_all_soft_refs, // clear_all_soft_refs 855 0, // size 856 false, // is_tlab 857 OldGen); // last_generation 858 } 859 } 860 861 bool GenCollectedHeap::is_in_young(oop p) { 862 bool result = ((HeapWord*)p) < _old_gen->reserved().start(); 863 assert(result == _young_gen->is_in_reserved(p), 864 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p)); 865 return result; 866 } 867 868 // Returns "TRUE" iff "p" points into the committed areas of the heap. 869 bool GenCollectedHeap::is_in(const void* p) const { 870 return _young_gen->is_in(p) || _old_gen->is_in(p); 871 } 872 873 #ifdef ASSERT 874 // Don't implement this by using is_in_young(). This method is used 875 // in some cases to check that is_in_young() is correct. 876 bool GenCollectedHeap::is_in_partial_collection(const void* p) { 877 assert(is_in_reserved(p) || p == NULL, 878 "Does not work if address is non-null and outside of the heap"); 879 return p < _young_gen->reserved().end() && p != NULL; 880 } 881 #endif 882 883 void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) { 884 NoHeaderExtendedOopClosure no_header_cl(cl); 885 oop_iterate(&no_header_cl); 886 } 887 888 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) { 889 _young_gen->oop_iterate(cl); 890 _old_gen->oop_iterate(cl); 891 } 892 893 void GenCollectedHeap::object_iterate(ObjectClosure* cl) { 894 _young_gen->object_iterate(cl); 895 _old_gen->object_iterate(cl); 896 } 897 898 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) { 899 _young_gen->safe_object_iterate(cl); 900 _old_gen->safe_object_iterate(cl); 901 } 902 903 Space* GenCollectedHeap::space_containing(const void* addr) const { 904 Space* res = _young_gen->space_containing(addr); 905 if (res != NULL) { 906 return res; 907 } 908 res = _old_gen->space_containing(addr); 909 assert(res != NULL, "Could not find containing space"); 910 return res; 911 } 912 913 HeapWord* GenCollectedHeap::block_start(const void* addr) const { 914 assert(is_in_reserved(addr), "block_start of address outside of heap"); 915 if (_young_gen->is_in_reserved(addr)) { 916 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation"); 917 return _young_gen->block_start(addr); 918 } 919 920 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 921 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation"); 922 return _old_gen->block_start(addr); 923 } 924 925 size_t GenCollectedHeap::block_size(const HeapWord* addr) const { 926 assert(is_in_reserved(addr), "block_size of address outside of heap"); 927 if (_young_gen->is_in_reserved(addr)) { 928 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation"); 929 return _young_gen->block_size(addr); 930 } 931 932 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 933 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation"); 934 return _old_gen->block_size(addr); 935 } 936 937 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const { 938 assert(is_in_reserved(addr), "block_is_obj of address outside of heap"); 939 assert(block_start(addr) == addr, "addr must be a block start"); 940 if (_young_gen->is_in_reserved(addr)) { 941 return _young_gen->block_is_obj(addr); 942 } 943 944 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 945 return _old_gen->block_is_obj(addr); 946 } 947 948 bool GenCollectedHeap::supports_tlab_allocation() const { 949 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 950 return _young_gen->supports_tlab_allocation(); 951 } 952 953 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const { 954 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 955 if (_young_gen->supports_tlab_allocation()) { 956 return _young_gen->tlab_capacity(); 957 } 958 return 0; 959 } 960 961 size_t GenCollectedHeap::tlab_used(Thread* thr) const { 962 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 963 if (_young_gen->supports_tlab_allocation()) { 964 return _young_gen->tlab_used(); 965 } 966 return 0; 967 } 968 969 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const { 970 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 971 if (_young_gen->supports_tlab_allocation()) { 972 return _young_gen->unsafe_max_tlab_alloc(); 973 } 974 return 0; 975 } 976 977 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) { 978 bool gc_overhead_limit_was_exceeded; 979 return gen_policy()->mem_allocate_work(size /* size */, 980 true /* is_tlab */, 981 &gc_overhead_limit_was_exceeded); 982 } 983 984 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size 985 // from the list headed by "*prev_ptr". 986 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) { 987 bool first = true; 988 size_t min_size = 0; // "first" makes this conceptually infinite. 989 ScratchBlock **smallest_ptr, *smallest; 990 ScratchBlock *cur = *prev_ptr; 991 while (cur) { 992 assert(*prev_ptr == cur, "just checking"); 993 if (first || cur->num_words < min_size) { 994 smallest_ptr = prev_ptr; 995 smallest = cur; 996 min_size = smallest->num_words; 997 first = false; 998 } 999 prev_ptr = &cur->next; 1000 cur = cur->next; 1001 } 1002 smallest = *smallest_ptr; 1003 *smallest_ptr = smallest->next; 1004 return smallest; 1005 } 1006 1007 // Sort the scratch block list headed by res into decreasing size order, 1008 // and set "res" to the result. 1009 static void sort_scratch_list(ScratchBlock*& list) { 1010 ScratchBlock* sorted = NULL; 1011 ScratchBlock* unsorted = list; 1012 while (unsorted) { 1013 ScratchBlock *smallest = removeSmallestScratch(&unsorted); 1014 smallest->next = sorted; 1015 sorted = smallest; 1016 } 1017 list = sorted; 1018 } 1019 1020 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor, 1021 size_t max_alloc_words) { 1022 ScratchBlock* res = NULL; 1023 _young_gen->contribute_scratch(res, requestor, max_alloc_words); 1024 _old_gen->contribute_scratch(res, requestor, max_alloc_words); 1025 sort_scratch_list(res); 1026 return res; 1027 } 1028 1029 void GenCollectedHeap::release_scratch() { 1030 _young_gen->reset_scratch(); 1031 _old_gen->reset_scratch(); 1032 } 1033 1034 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure { 1035 void do_generation(Generation* gen) { 1036 gen->prepare_for_verify(); 1037 } 1038 }; 1039 1040 void GenCollectedHeap::prepare_for_verify() { 1041 ensure_parsability(false); // no need to retire TLABs 1042 GenPrepareForVerifyClosure blk; 1043 generation_iterate(&blk, false); 1044 } 1045 1046 void GenCollectedHeap::generation_iterate(GenClosure* cl, 1047 bool old_to_young) { 1048 if (old_to_young) { 1049 cl->do_generation(_old_gen); 1050 cl->do_generation(_young_gen); 1051 } else { 1052 cl->do_generation(_young_gen); 1053 cl->do_generation(_old_gen); 1054 } 1055 } 1056 1057 bool GenCollectedHeap::is_maximal_no_gc() const { 1058 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc(); 1059 } 1060 1061 void GenCollectedHeap::save_marks() { 1062 _young_gen->save_marks(); 1063 _old_gen->save_marks(); 1064 } 1065 1066 GenCollectedHeap* GenCollectedHeap::heap() { 1067 CollectedHeap* heap = Universe::heap(); 1068 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()"); 1069 assert(heap->kind() == CollectedHeap::GenCollectedHeap, "Not a GenCollectedHeap"); 1070 return (GenCollectedHeap*)heap; 1071 } 1072 1073 void GenCollectedHeap::prepare_for_compaction() { 1074 // Start by compacting into same gen. 1075 CompactPoint cp(_old_gen); 1076 _old_gen->prepare_for_compaction(&cp); 1077 _young_gen->prepare_for_compaction(&cp); 1078 } 1079 1080 void GenCollectedHeap::verify(VerifyOption option /* ignored */) { 1081 log_debug(gc, verify)("%s", _old_gen->name()); 1082 _old_gen->verify(); 1083 1084 log_debug(gc, verify)("%s", _old_gen->name()); 1085 _young_gen->verify(); 1086 1087 log_debug(gc, verify)("RemSet"); 1088 rem_set()->verify(); 1089 } 1090 1091 void GenCollectedHeap::print_on(outputStream* st) const { 1092 assert_locked_or_safepoint(Heap_lock); 1093 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(log_warning(gc)("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::cmst()->stop(); 1285 } 1286 #endif 1287 }