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 assert(!_young_gen->performs_in_place_marking(), "No young generation do in place marking"); 462 collect_generation(_young_gen, 463 full, 464 size, 465 is_tlab, 466 run_verification && VerifyGCLevel <= 0, 467 do_clear_all_soft_refs, 468 false); 469 470 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) && 471 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) { 472 // Allocation request was met by young GC. 473 size = 0; 474 } 475 } 476 477 bool must_restore_marks_for_biased_locking = false; 478 479 if (max_generation == OldGen && _old_gen->should_collect(full, size, is_tlab)) { 480 if (!complete) { 481 // The full_collections increment was missed above. 482 increment_total_full_collections(); 483 } 484 485 pre_full_gc_dump(NULL); // do any pre full gc dumps 486 487 if (!prepared_for_verification && run_verification && 488 VerifyGCLevel <= 1 && VerifyBeforeGC) { 489 prepare_for_verify(); 490 } 491 492 assert(_old_gen->performs_in_place_marking(), "All old generations do in place marking"); 493 494 if (do_young_collection) { 495 // We did a young GC. Need a new GC id for the old GC. 496 GCIdMarkAndRestore gc_id_mark; 497 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true); 498 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true); 499 } else { 500 // No young GC done. Use the same GC id as was set up earlier in this method. 501 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true); 502 } 503 504 must_restore_marks_for_biased_locking = true; 505 collected_old = true; 506 } 507 508 // Update "complete" boolean wrt what actually transpired -- 509 // for instance, a promotion failure could have led to 510 // a whole heap collection. 511 complete = complete || collected_old; 512 513 if (complete) { // We did a full collection 514 // FIXME: See comment at pre_full_gc_dump call 515 post_full_gc_dump(NULL); // do any post full gc dumps 516 } 517 518 print_heap_change(young_prev_used, old_prev_used); 519 MetaspaceAux::print_metaspace_change(metadata_prev_used); 520 521 // Adjust generation sizes. 522 if (collected_old) { 523 _old_gen->compute_new_size(); 524 } 525 _young_gen->compute_new_size(); 526 527 if (complete) { 528 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 529 ClassLoaderDataGraph::purge(); 530 MetaspaceAux::verify_metrics(); 531 // Resize the metaspace capacity after full collections 532 MetaspaceGC::compute_new_size(); 533 update_full_collections_completed(); 534 } 535 536 // Track memory usage and detect low memory after GC finishes 537 MemoryService::track_memory_usage(); 538 539 gc_epilogue(complete); 540 541 if (must_restore_marks_for_biased_locking) { 542 BiasedLocking::restore_marks(); 543 } 544 } 545 546 print_heap_after_gc(); 547 548 #ifdef TRACESPINNING 549 ParallelTaskTerminator::print_termination_counts(); 550 #endif 551 } 552 553 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) { 554 return collector_policy()->satisfy_failed_allocation(size, is_tlab); 555 } 556 557 #ifdef ASSERT 558 class AssertNonScavengableClosure: public OopClosure { 559 public: 560 virtual void do_oop(oop* p) { 561 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p), 562 "Referent should not be scavengable."); } 563 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); } 564 }; 565 static AssertNonScavengableClosure assert_is_non_scavengable_closure; 566 #endif 567 568 void GenCollectedHeap::process_roots(StrongRootsScope* scope, 569 ScanningOption so, 570 OopClosure* strong_roots, 571 OopClosure* weak_roots, 572 CLDClosure* strong_cld_closure, 573 CLDClosure* weak_cld_closure, 574 CodeBlobClosure* code_roots) { 575 // General roots. 576 assert(Threads::thread_claim_parity() != 0, "must have called prologue code"); 577 assert(code_roots != NULL, "code root closure should always be set"); 578 // _n_termination for _process_strong_tasks should be set up stream 579 // in a method not running in a GC worker. Otherwise the GC worker 580 // could be trying to change the termination condition while the task 581 // is executing in another GC worker. 582 583 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) { 584 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure); 585 } 586 587 // Some CLDs contained in the thread frames should be considered strong. 588 // Don't process them if they will be processed during the ClassLoaderDataGraph phase. 589 CLDClosure* roots_from_clds_p = (strong_cld_closure != weak_cld_closure) ? strong_cld_closure : NULL; 590 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway 591 CodeBlobClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots; 592 593 bool is_par = scope->n_threads() > 1; 594 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_clds_p, roots_from_code_p); 595 596 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) { 597 Universe::oops_do(strong_roots); 598 } 599 // Global (strong) JNI handles 600 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) { 601 JNIHandles::oops_do(strong_roots); 602 } 603 604 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) { 605 ObjectSynchronizer::oops_do(strong_roots); 606 } 607 if (!_process_strong_tasks->is_task_claimed(GCH_PS_FlatProfiler_oops_do)) { 608 FlatProfiler::oops_do(strong_roots); 609 } 610 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) { 611 Management::oops_do(strong_roots); 612 } 613 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) { 614 JvmtiExport::oops_do(strong_roots); 615 } 616 617 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) { 618 SystemDictionary::roots_oops_do(strong_roots, weak_roots); 619 } 620 621 // All threads execute the following. A specific chunk of buckets 622 // from the StringTable are the individual tasks. 623 if (weak_roots != NULL) { 624 if (is_par) { 625 StringTable::possibly_parallel_oops_do(weak_roots); 626 } else { 627 StringTable::oops_do(weak_roots); 628 } 629 } 630 631 if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) { 632 if (so & SO_ScavengeCodeCache) { 633 assert(code_roots != NULL, "must supply closure for code cache"); 634 635 // We only visit parts of the CodeCache when scavenging. 636 CodeCache::scavenge_root_nmethods_do(code_roots); 637 } 638 if (so & SO_AllCodeCache) { 639 assert(code_roots != NULL, "must supply closure for code cache"); 640 641 // CMSCollector uses this to do intermediate-strength collections. 642 // We scan the entire code cache, since CodeCache::do_unloading is not called. 643 CodeCache::blobs_do(code_roots); 644 } 645 // Verify that the code cache contents are not subject to 646 // movement by a scavenging collection. 647 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations)); 648 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable)); 649 } 650 } 651 652 void GenCollectedHeap::gen_process_roots(StrongRootsScope* scope, 653 GenerationType type, 654 bool young_gen_as_roots, 655 ScanningOption so, 656 bool only_strong_roots, 657 OopsInGenClosure* not_older_gens, 658 OopsInGenClosure* older_gens, 659 CLDClosure* cld_closure) { 660 const bool is_adjust_phase = !only_strong_roots && !young_gen_as_roots; 661 662 bool is_moving_collection = false; 663 if (type == YoungGen || is_adjust_phase) { 664 // young collections are always moving 665 is_moving_collection = true; 666 } 667 668 MarkingCodeBlobClosure mark_code_closure(not_older_gens, is_moving_collection); 669 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : not_older_gens; 670 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure; 671 672 process_roots(scope, so, 673 not_older_gens, weak_roots, 674 cld_closure, weak_cld_closure, 675 &mark_code_closure); 676 677 if (young_gen_as_roots) { 678 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) { 679 if (type == OldGen) { 680 not_older_gens->set_generation(_young_gen); 681 _young_gen->oop_iterate(not_older_gens); 682 } 683 not_older_gens->reset_generation(); 684 } 685 } 686 // When collection is parallel, all threads get to cooperate to do 687 // old generation scanning. 688 if (type == YoungGen) { 689 older_gens->set_generation(_old_gen); 690 rem_set()->younger_refs_iterate(_old_gen, older_gens, scope->n_threads()); 691 older_gens->reset_generation(); 692 } 693 694 _process_strong_tasks->all_tasks_completed(scope->n_threads()); 695 } 696 697 698 class AlwaysTrueClosure: public BoolObjectClosure { 699 public: 700 bool do_object_b(oop p) { return true; } 701 }; 702 static AlwaysTrueClosure always_true; 703 704 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) { 705 JNIHandles::weak_oops_do(&always_true, root_closure); 706 _young_gen->ref_processor()->weak_oops_do(root_closure); 707 _old_gen->ref_processor()->weak_oops_do(root_closure); 708 } 709 710 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \ 711 void GenCollectedHeap:: \ 712 oop_since_save_marks_iterate(GenerationType gen, \ 713 OopClosureType* cur, \ 714 OopClosureType* older) { \ 715 if (gen == YoungGen) { \ 716 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \ 717 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \ 718 } else { \ 719 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \ 720 } \ 721 } 722 723 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN) 724 725 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN 726 727 bool GenCollectedHeap::no_allocs_since_save_marks() { 728 return _young_gen->no_allocs_since_save_marks() && 729 _old_gen->no_allocs_since_save_marks(); 730 } 731 732 bool GenCollectedHeap::supports_inline_contig_alloc() const { 733 return _young_gen->supports_inline_contig_alloc(); 734 } 735 736 HeapWord** GenCollectedHeap::top_addr() const { 737 return _young_gen->top_addr(); 738 } 739 740 HeapWord** GenCollectedHeap::end_addr() const { 741 return _young_gen->end_addr(); 742 } 743 744 // public collection interfaces 745 746 void GenCollectedHeap::collect(GCCause::Cause cause) { 747 if (should_do_concurrent_full_gc(cause)) { 748 #if INCLUDE_ALL_GCS 749 // Mostly concurrent full collection. 750 collect_mostly_concurrent(cause); 751 #else // INCLUDE_ALL_GCS 752 ShouldNotReachHere(); 753 #endif // INCLUDE_ALL_GCS 754 } else if (cause == GCCause::_wb_young_gc) { 755 // Young collection for the WhiteBox API. 756 collect(cause, YoungGen); 757 } else { 758 #ifdef ASSERT 759 if (cause == GCCause::_scavenge_alot) { 760 // Young collection only. 761 collect(cause, YoungGen); 762 } else { 763 // Stop-the-world full collection. 764 collect(cause, OldGen); 765 } 766 #else 767 // Stop-the-world full collection. 768 collect(cause, OldGen); 769 #endif 770 } 771 } 772 773 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) { 774 // The caller doesn't have the Heap_lock 775 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock"); 776 MutexLocker ml(Heap_lock); 777 collect_locked(cause, max_generation); 778 } 779 780 void GenCollectedHeap::collect_locked(GCCause::Cause cause) { 781 // The caller has the Heap_lock 782 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock"); 783 collect_locked(cause, OldGen); 784 } 785 786 // this is the private collection interface 787 // The Heap_lock is expected to be held on entry. 788 789 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) { 790 // Read the GC count while holding the Heap_lock 791 unsigned int gc_count_before = total_collections(); 792 unsigned int full_gc_count_before = total_full_collections(); 793 { 794 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back 795 VM_GenCollectFull op(gc_count_before, full_gc_count_before, 796 cause, max_generation); 797 VMThread::execute(&op); 798 } 799 } 800 801 #if INCLUDE_ALL_GCS 802 bool GenCollectedHeap::create_cms_collector() { 803 804 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep, 805 "Unexpected generation kinds"); 806 // Skip two header words in the block content verification 807 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();) 808 assert(_gen_policy->is_concurrent_mark_sweep_policy(), "Unexpected policy type"); 809 CMSCollector* collector = 810 new CMSCollector((ConcurrentMarkSweepGeneration*)_old_gen, 811 _rem_set, 812 _gen_policy->as_concurrent_mark_sweep_policy()); 813 814 if (collector == NULL || !collector->completed_initialization()) { 815 if (collector) { 816 delete collector; // Be nice in embedded situation 817 } 818 vm_shutdown_during_initialization("Could not create CMS collector"); 819 return false; 820 } 821 return true; // success 822 } 823 824 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) { 825 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock"); 826 827 MutexLocker ml(Heap_lock); 828 // Read the GC counts while holding the Heap_lock 829 unsigned int full_gc_count_before = total_full_collections(); 830 unsigned int gc_count_before = total_collections(); 831 { 832 MutexUnlocker mu(Heap_lock); 833 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause); 834 VMThread::execute(&op); 835 } 836 } 837 #endif // INCLUDE_ALL_GCS 838 839 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) { 840 do_full_collection(clear_all_soft_refs, OldGen); 841 } 842 843 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs, 844 GenerationType last_generation) { 845 GenerationType local_last_generation; 846 if (!incremental_collection_will_fail(false /* don't consult_young */) && 847 gc_cause() == GCCause::_gc_locker) { 848 local_last_generation = YoungGen; 849 } else { 850 local_last_generation = last_generation; 851 } 852 853 do_collection(true, // full 854 clear_all_soft_refs, // clear_all_soft_refs 855 0, // size 856 false, // is_tlab 857 local_last_generation); // last_generation 858 // Hack XXX FIX ME !!! 859 // A scavenge may not have been attempted, or may have 860 // been attempted and failed, because the old gen was too full 861 if (local_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker && 862 incremental_collection_will_fail(false /* don't consult_young */)) { 863 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed"); 864 // This time allow the old gen to be collected as well 865 do_collection(true, // full 866 clear_all_soft_refs, // clear_all_soft_refs 867 0, // size 868 false, // is_tlab 869 OldGen); // last_generation 870 } 871 } 872 873 bool GenCollectedHeap::is_in_young(oop p) { 874 bool result = ((HeapWord*)p) < _old_gen->reserved().start(); 875 assert(result == _young_gen->is_in_reserved(p), 876 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p)); 877 return result; 878 } 879 880 // Returns "TRUE" iff "p" points into the committed areas of the heap. 881 bool GenCollectedHeap::is_in(const void* p) const { 882 return _young_gen->is_in(p) || _old_gen->is_in(p); 883 } 884 885 #ifdef ASSERT 886 // Don't implement this by using is_in_young(). This method is used 887 // in some cases to check that is_in_young() is correct. 888 bool GenCollectedHeap::is_in_partial_collection(const void* p) { 889 assert(is_in_reserved(p) || p == NULL, 890 "Does not work if address is non-null and outside of the heap"); 891 return p < _young_gen->reserved().end() && p != NULL; 892 } 893 #endif 894 895 void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) { 896 NoHeaderExtendedOopClosure no_header_cl(cl); 897 oop_iterate(&no_header_cl); 898 } 899 900 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) { 901 _young_gen->oop_iterate(cl); 902 _old_gen->oop_iterate(cl); 903 } 904 905 void GenCollectedHeap::object_iterate(ObjectClosure* cl) { 906 _young_gen->object_iterate(cl); 907 _old_gen->object_iterate(cl); 908 } 909 910 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) { 911 _young_gen->safe_object_iterate(cl); 912 _old_gen->safe_object_iterate(cl); 913 } 914 915 Space* GenCollectedHeap::space_containing(const void* addr) const { 916 Space* res = _young_gen->space_containing(addr); 917 if (res != NULL) { 918 return res; 919 } 920 res = _old_gen->space_containing(addr); 921 assert(res != NULL, "Could not find containing space"); 922 return res; 923 } 924 925 HeapWord* GenCollectedHeap::block_start(const void* addr) const { 926 assert(is_in_reserved(addr), "block_start 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_start(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_start(addr); 935 } 936 937 size_t GenCollectedHeap::block_size(const HeapWord* addr) const { 938 assert(is_in_reserved(addr), "block_size of address outside of heap"); 939 if (_young_gen->is_in_reserved(addr)) { 940 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation"); 941 return _young_gen->block_size(addr); 942 } 943 944 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 945 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation"); 946 return _old_gen->block_size(addr); 947 } 948 949 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const { 950 assert(is_in_reserved(addr), "block_is_obj of address outside of heap"); 951 assert(block_start(addr) == addr, "addr must be a block start"); 952 if (_young_gen->is_in_reserved(addr)) { 953 return _young_gen->block_is_obj(addr); 954 } 955 956 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 957 return _old_gen->block_is_obj(addr); 958 } 959 960 bool GenCollectedHeap::supports_tlab_allocation() const { 961 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 962 return _young_gen->supports_tlab_allocation(); 963 } 964 965 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const { 966 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 967 if (_young_gen->supports_tlab_allocation()) { 968 return _young_gen->tlab_capacity(); 969 } 970 return 0; 971 } 972 973 size_t GenCollectedHeap::tlab_used(Thread* thr) const { 974 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 975 if (_young_gen->supports_tlab_allocation()) { 976 return _young_gen->tlab_used(); 977 } 978 return 0; 979 } 980 981 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const { 982 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 983 if (_young_gen->supports_tlab_allocation()) { 984 return _young_gen->unsafe_max_tlab_alloc(); 985 } 986 return 0; 987 } 988 989 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) { 990 bool gc_overhead_limit_was_exceeded; 991 return collector_policy()->mem_allocate_work(size /* size */, 992 true /* is_tlab */, 993 &gc_overhead_limit_was_exceeded); 994 } 995 996 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size 997 // from the list headed by "*prev_ptr". 998 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) { 999 bool first = true; 1000 size_t min_size = 0; // "first" makes this conceptually infinite. 1001 ScratchBlock **smallest_ptr, *smallest; 1002 ScratchBlock *cur = *prev_ptr; 1003 while (cur) { 1004 assert(*prev_ptr == cur, "just checking"); 1005 if (first || cur->num_words < min_size) { 1006 smallest_ptr = prev_ptr; 1007 smallest = cur; 1008 min_size = smallest->num_words; 1009 first = false; 1010 } 1011 prev_ptr = &cur->next; 1012 cur = cur->next; 1013 } 1014 smallest = *smallest_ptr; 1015 *smallest_ptr = smallest->next; 1016 return smallest; 1017 } 1018 1019 // Sort the scratch block list headed by res into decreasing size order, 1020 // and set "res" to the result. 1021 static void sort_scratch_list(ScratchBlock*& list) { 1022 ScratchBlock* sorted = NULL; 1023 ScratchBlock* unsorted = list; 1024 while (unsorted) { 1025 ScratchBlock *smallest = removeSmallestScratch(&unsorted); 1026 smallest->next = sorted; 1027 sorted = smallest; 1028 } 1029 list = sorted; 1030 } 1031 1032 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor, 1033 size_t max_alloc_words) { 1034 ScratchBlock* res = NULL; 1035 _young_gen->contribute_scratch(res, requestor, max_alloc_words); 1036 _old_gen->contribute_scratch(res, requestor, max_alloc_words); 1037 sort_scratch_list(res); 1038 return res; 1039 } 1040 1041 void GenCollectedHeap::release_scratch() { 1042 _young_gen->reset_scratch(); 1043 _old_gen->reset_scratch(); 1044 } 1045 1046 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure { 1047 void do_generation(Generation* gen) { 1048 gen->prepare_for_verify(); 1049 } 1050 }; 1051 1052 void GenCollectedHeap::prepare_for_verify() { 1053 ensure_parsability(false); // no need to retire TLABs 1054 GenPrepareForVerifyClosure blk; 1055 generation_iterate(&blk, false); 1056 } 1057 1058 void GenCollectedHeap::generation_iterate(GenClosure* cl, 1059 bool old_to_young) { 1060 if (old_to_young) { 1061 cl->do_generation(_old_gen); 1062 cl->do_generation(_young_gen); 1063 } else { 1064 cl->do_generation(_young_gen); 1065 cl->do_generation(_old_gen); 1066 } 1067 } 1068 1069 bool GenCollectedHeap::is_maximal_no_gc() const { 1070 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc(); 1071 } 1072 1073 void GenCollectedHeap::save_marks() { 1074 _young_gen->save_marks(); 1075 _old_gen->save_marks(); 1076 } 1077 1078 GenCollectedHeap* GenCollectedHeap::heap() { 1079 CollectedHeap* heap = Universe::heap(); 1080 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()"); 1081 assert(heap->kind() == CollectedHeap::GenCollectedHeap, "Not a GenCollectedHeap"); 1082 return (GenCollectedHeap*)heap; 1083 } 1084 1085 void GenCollectedHeap::prepare_for_compaction() { 1086 // Start by compacting into same gen. 1087 CompactPoint cp(_old_gen); 1088 _old_gen->prepare_for_compaction(&cp); 1089 _young_gen->prepare_for_compaction(&cp); 1090 } 1091 1092 void GenCollectedHeap::verify(VerifyOption option /* ignored */) { 1093 log_debug(gc, verify)("%s", _old_gen->name()); 1094 _old_gen->verify(); 1095 1096 log_debug(gc, verify)("%s", _old_gen->name()); 1097 _young_gen->verify(); 1098 1099 log_debug(gc, verify)("RemSet"); 1100 rem_set()->verify(); 1101 } 1102 1103 void GenCollectedHeap::print_on(outputStream* st) const { 1104 _young_gen->print_on(st); 1105 _old_gen->print_on(st); 1106 MetaspaceAux::print_on(st); 1107 } 1108 1109 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const { 1110 if (workers() != NULL) { 1111 workers()->threads_do(tc); 1112 } 1113 #if INCLUDE_ALL_GCS 1114 if (UseConcMarkSweepGC) { 1115 ConcurrentMarkSweepThread::threads_do(tc); 1116 } 1117 #endif // INCLUDE_ALL_GCS 1118 } 1119 1120 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const { 1121 #if INCLUDE_ALL_GCS 1122 if (UseConcMarkSweepGC) { 1123 workers()->print_worker_threads_on(st); 1124 ConcurrentMarkSweepThread::print_all_on(st); 1125 } 1126 #endif // INCLUDE_ALL_GCS 1127 } 1128 1129 void GenCollectedHeap::print_on_error(outputStream* st) const { 1130 this->CollectedHeap::print_on_error(st); 1131 1132 #if INCLUDE_ALL_GCS 1133 if (UseConcMarkSweepGC) { 1134 st->cr(); 1135 CMSCollector::print_on_error(st); 1136 } 1137 #endif // INCLUDE_ALL_GCS 1138 } 1139 1140 void GenCollectedHeap::print_tracing_info() const { 1141 if (TraceYoungGenTime) { 1142 _young_gen->print_summary_info(); 1143 } 1144 if (TraceOldGenTime) { 1145 _old_gen->print_summary_info(); 1146 } 1147 } 1148 1149 void GenCollectedHeap::print_heap_change(size_t young_prev_used, size_t old_prev_used) const { 1150 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)", 1151 _young_gen->short_name(), young_prev_used / K, _young_gen->used() /K, _young_gen->capacity() /K); 1152 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)", 1153 _old_gen->short_name(), old_prev_used / K, _old_gen->used() /K, _old_gen->capacity() /K); 1154 } 1155 1156 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure { 1157 private: 1158 bool _full; 1159 public: 1160 void do_generation(Generation* gen) { 1161 gen->gc_prologue(_full); 1162 } 1163 GenGCPrologueClosure(bool full) : _full(full) {}; 1164 }; 1165 1166 void GenCollectedHeap::gc_prologue(bool full) { 1167 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 1168 1169 always_do_update_barrier = false; 1170 // Fill TLAB's and such 1171 CollectedHeap::accumulate_statistics_all_tlabs(); 1172 ensure_parsability(true); // retire TLABs 1173 1174 // Walk generations 1175 GenGCPrologueClosure blk(full); 1176 generation_iterate(&blk, false); // not old-to-young. 1177 }; 1178 1179 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure { 1180 private: 1181 bool _full; 1182 public: 1183 void do_generation(Generation* gen) { 1184 gen->gc_epilogue(_full); 1185 } 1186 GenGCEpilogueClosure(bool full) : _full(full) {}; 1187 }; 1188 1189 void GenCollectedHeap::gc_epilogue(bool full) { 1190 #if defined(COMPILER2) || INCLUDE_JVMCI 1191 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 1192 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr())); 1193 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps"); 1194 #endif /* COMPILER2 || INCLUDE_JVMCI */ 1195 1196 resize_all_tlabs(); 1197 1198 GenGCEpilogueClosure blk(full); 1199 generation_iterate(&blk, false); // not old-to-young. 1200 1201 if (!CleanChunkPoolAsync) { 1202 Chunk::clean_chunk_pool(); 1203 } 1204 1205 MetaspaceCounters::update_performance_counters(); 1206 CompressedClassSpaceCounters::update_performance_counters(); 1207 1208 always_do_update_barrier = UseConcMarkSweepGC; 1209 }; 1210 1211 #ifndef PRODUCT 1212 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure { 1213 private: 1214 public: 1215 void do_generation(Generation* gen) { 1216 gen->record_spaces_top(); 1217 } 1218 }; 1219 1220 void GenCollectedHeap::record_gen_tops_before_GC() { 1221 if (ZapUnusedHeapArea) { 1222 GenGCSaveTopsBeforeGCClosure blk; 1223 generation_iterate(&blk, false); // not old-to-young. 1224 } 1225 } 1226 #endif // not PRODUCT 1227 1228 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure { 1229 public: 1230 void do_generation(Generation* gen) { 1231 gen->ensure_parsability(); 1232 } 1233 }; 1234 1235 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) { 1236 CollectedHeap::ensure_parsability(retire_tlabs); 1237 GenEnsureParsabilityClosure ep_cl; 1238 generation_iterate(&ep_cl, false); 1239 } 1240 1241 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen, 1242 oop obj, 1243 size_t obj_size) { 1244 guarantee(old_gen == _old_gen, "We only get here with an old generation"); 1245 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in"); 1246 HeapWord* result = NULL; 1247 1248 result = old_gen->expand_and_allocate(obj_size, false); 1249 1250 if (result != NULL) { 1251 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size); 1252 } 1253 return oop(result); 1254 } 1255 1256 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure { 1257 jlong _time; // in ms 1258 jlong _now; // in ms 1259 1260 public: 1261 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { } 1262 1263 jlong time() { return _time; } 1264 1265 void do_generation(Generation* gen) { 1266 _time = MIN2(_time, gen->time_of_last_gc(_now)); 1267 } 1268 }; 1269 1270 jlong GenCollectedHeap::millis_since_last_gc() { 1271 // We need a monotonically non-decreasing time in ms but 1272 // os::javaTimeMillis() does not guarantee monotonicity. 1273 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 1274 GenTimeOfLastGCClosure tolgc_cl(now); 1275 // iterate over generations getting the oldest 1276 // time that a generation was collected 1277 generation_iterate(&tolgc_cl, false); 1278 1279 // javaTimeNanos() is guaranteed to be monotonically non-decreasing 1280 // provided the underlying platform provides such a time source 1281 // (and it is bug free). So we still have to guard against getting 1282 // back a time later than 'now'. 1283 jlong retVal = now - tolgc_cl.time(); 1284 if (retVal < 0) { 1285 NOT_PRODUCT(warning("time warp: " JLONG_FORMAT, retVal);) 1286 return 0; 1287 } 1288 return retVal; 1289 } 1290 1291 void GenCollectedHeap::stop() { 1292 #if INCLUDE_ALL_GCS 1293 if (UseConcMarkSweepGC) { 1294 ConcurrentMarkSweepThread::stop(); 1295 } 1296 #endif 1297 }