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::young_process_roots(StrongRootsScope* scope, 648 OopsInGenClosure* root_closure, 649 OopsInGenClosure* old_gen_closure, 650 CLDClosure* cld_closure) { 651 MarkingCodeBlobClosure mark_code_closure(root_closure, CodeBlobToOopClosure::FixRelocations); 652 653 process_roots(scope, SO_ScavengeCodeCache, root_closure, root_closure, 654 cld_closure, cld_closure, &mark_code_closure); 655 656 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) { 657 root_closure->reset_generation(); 658 } 659 660 // When collection is parallel, all threads get to cooperate to do 661 // old generation scanning. 662 old_gen_closure->set_generation(_old_gen); 663 rem_set()->younger_refs_iterate(_old_gen, old_gen_closure, scope->n_threads()); 664 old_gen_closure->reset_generation(); 665 666 _process_strong_tasks->all_tasks_completed(scope->n_threads()); 667 } 668 669 void GenCollectedHeap::old_process_roots(StrongRootsScope* scope, 670 bool young_gen_as_roots, 671 ScanningOption so, 672 bool only_strong_roots, 673 OopsInGenClosure* root_closure, 674 CLDClosure* cld_closure) { 675 const bool is_moving_collection = !only_strong_roots && !young_gen_as_roots; 676 677 MarkingCodeBlobClosure mark_code_closure(root_closure, is_moving_collection); 678 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : root_closure; 679 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure; 680 681 process_roots(scope, so, root_closure, weak_roots, cld_closure, weak_cld_closure, &mark_code_closure); 682 683 if (young_gen_as_roots && 684 !_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) { 685 root_closure->set_generation(_young_gen); 686 _young_gen->oop_iterate(root_closure); 687 root_closure->reset_generation(); 688 } 689 690 _process_strong_tasks->all_tasks_completed(scope->n_threads()); 691 } 692 693 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) { 694 JNIHandles::weak_oops_do(root_closure); 695 _young_gen->ref_processor()->weak_oops_do(root_closure); 696 _old_gen->ref_processor()->weak_oops_do(root_closure); 697 } 698 699 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \ 700 void GenCollectedHeap:: \ 701 oop_since_save_marks_iterate(GenerationType gen, \ 702 OopClosureType* cur, \ 703 OopClosureType* older) { \ 704 if (gen == YoungGen) { \ 705 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \ 706 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \ 707 } else { \ 708 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \ 709 } \ 710 } 711 712 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN) 713 714 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN 715 716 bool GenCollectedHeap::no_allocs_since_save_marks() { 717 return _young_gen->no_allocs_since_save_marks() && 718 _old_gen->no_allocs_since_save_marks(); 719 } 720 721 bool GenCollectedHeap::supports_inline_contig_alloc() const { 722 return _young_gen->supports_inline_contig_alloc(); 723 } 724 725 HeapWord** GenCollectedHeap::top_addr() const { 726 return _young_gen->top_addr(); 727 } 728 729 HeapWord** GenCollectedHeap::end_addr() const { 730 return _young_gen->end_addr(); 731 } 732 733 // public collection interfaces 734 735 void GenCollectedHeap::collect(GCCause::Cause cause) { 736 if (should_do_concurrent_full_gc(cause)) { 737 #if INCLUDE_ALL_GCS 738 // Mostly concurrent full collection. 739 collect_mostly_concurrent(cause); 740 #else // INCLUDE_ALL_GCS 741 ShouldNotReachHere(); 742 #endif // INCLUDE_ALL_GCS 743 } else if (cause == GCCause::_wb_young_gc) { 744 // Young collection for the WhiteBox API. 745 collect(cause, YoungGen); 746 } else { 747 #ifdef ASSERT 748 if (cause == GCCause::_scavenge_alot) { 749 // Young collection only. 750 collect(cause, YoungGen); 751 } else { 752 // Stop-the-world full collection. 753 collect(cause, OldGen); 754 } 755 #else 756 // Stop-the-world full collection. 757 collect(cause, OldGen); 758 #endif 759 } 760 } 761 762 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) { 763 // The caller doesn't have the Heap_lock 764 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock"); 765 MutexLocker ml(Heap_lock); 766 collect_locked(cause, max_generation); 767 } 768 769 void GenCollectedHeap::collect_locked(GCCause::Cause cause) { 770 // The caller has the Heap_lock 771 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock"); 772 collect_locked(cause, OldGen); 773 } 774 775 // this is the private collection interface 776 // The Heap_lock is expected to be held on entry. 777 778 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) { 779 // Read the GC count while holding the Heap_lock 780 unsigned int gc_count_before = total_collections(); 781 unsigned int full_gc_count_before = total_full_collections(); 782 { 783 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back 784 VM_GenCollectFull op(gc_count_before, full_gc_count_before, 785 cause, max_generation); 786 VMThread::execute(&op); 787 } 788 } 789 790 #if INCLUDE_ALL_GCS 791 bool GenCollectedHeap::create_cms_collector() { 792 793 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep, 794 "Unexpected generation kinds"); 795 // Skip two header words in the block content verification 796 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();) 797 assert(_gen_policy->is_concurrent_mark_sweep_policy(), "Unexpected policy type"); 798 CMSCollector* collector = 799 new CMSCollector((ConcurrentMarkSweepGeneration*)_old_gen, 800 _rem_set, 801 _gen_policy->as_concurrent_mark_sweep_policy()); 802 803 if (collector == NULL || !collector->completed_initialization()) { 804 if (collector) { 805 delete collector; // Be nice in embedded situation 806 } 807 vm_shutdown_during_initialization("Could not create CMS collector"); 808 return false; 809 } 810 return true; // success 811 } 812 813 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) { 814 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock"); 815 816 MutexLocker ml(Heap_lock); 817 // Read the GC counts while holding the Heap_lock 818 unsigned int full_gc_count_before = total_full_collections(); 819 unsigned int gc_count_before = total_collections(); 820 { 821 MutexUnlocker mu(Heap_lock); 822 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause); 823 VMThread::execute(&op); 824 } 825 } 826 #endif // INCLUDE_ALL_GCS 827 828 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) { 829 do_full_collection(clear_all_soft_refs, OldGen); 830 } 831 832 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs, 833 GenerationType last_generation) { 834 GenerationType local_last_generation; 835 if (!incremental_collection_will_fail(false /* don't consult_young */) && 836 gc_cause() == GCCause::_gc_locker) { 837 local_last_generation = YoungGen; 838 } else { 839 local_last_generation = last_generation; 840 } 841 842 do_collection(true, // full 843 clear_all_soft_refs, // clear_all_soft_refs 844 0, // size 845 false, // is_tlab 846 local_last_generation); // last_generation 847 // Hack XXX FIX ME !!! 848 // A scavenge may not have been attempted, or may have 849 // been attempted and failed, because the old gen was too full 850 if (local_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker && 851 incremental_collection_will_fail(false /* don't consult_young */)) { 852 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed"); 853 // This time allow the old gen to be collected as well 854 do_collection(true, // full 855 clear_all_soft_refs, // clear_all_soft_refs 856 0, // size 857 false, // is_tlab 858 OldGen); // last_generation 859 } 860 } 861 862 bool GenCollectedHeap::is_in_young(oop p) { 863 bool result = ((HeapWord*)p) < _old_gen->reserved().start(); 864 assert(result == _young_gen->is_in_reserved(p), 865 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p)); 866 return result; 867 } 868 869 // Returns "TRUE" iff "p" points into the committed areas of the heap. 870 bool GenCollectedHeap::is_in(const void* p) const { 871 return _young_gen->is_in(p) || _old_gen->is_in(p); 872 } 873 874 #ifdef ASSERT 875 // Don't implement this by using is_in_young(). This method is used 876 // in some cases to check that is_in_young() is correct. 877 bool GenCollectedHeap::is_in_partial_collection(const void* p) { 878 assert(is_in_reserved(p) || p == NULL, 879 "Does not work if address is non-null and outside of the heap"); 880 return p < _young_gen->reserved().end() && p != NULL; 881 } 882 #endif 883 884 void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) { 885 NoHeaderExtendedOopClosure no_header_cl(cl); 886 oop_iterate(&no_header_cl); 887 } 888 889 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) { 890 _young_gen->oop_iterate(cl); 891 _old_gen->oop_iterate(cl); 892 } 893 894 void GenCollectedHeap::object_iterate(ObjectClosure* cl) { 895 _young_gen->object_iterate(cl); 896 _old_gen->object_iterate(cl); 897 } 898 899 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) { 900 _young_gen->safe_object_iterate(cl); 901 _old_gen->safe_object_iterate(cl); 902 } 903 904 Space* GenCollectedHeap::space_containing(const void* addr) const { 905 Space* res = _young_gen->space_containing(addr); 906 if (res != NULL) { 907 return res; 908 } 909 res = _old_gen->space_containing(addr); 910 assert(res != NULL, "Could not find containing space"); 911 return res; 912 } 913 914 HeapWord* GenCollectedHeap::block_start(const void* addr) const { 915 assert(is_in_reserved(addr), "block_start of address outside of heap"); 916 if (_young_gen->is_in_reserved(addr)) { 917 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation"); 918 return _young_gen->block_start(addr); 919 } 920 921 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 922 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation"); 923 return _old_gen->block_start(addr); 924 } 925 926 size_t GenCollectedHeap::block_size(const HeapWord* addr) const { 927 assert(is_in_reserved(addr), "block_size of address outside of heap"); 928 if (_young_gen->is_in_reserved(addr)) { 929 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation"); 930 return _young_gen->block_size(addr); 931 } 932 933 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 934 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation"); 935 return _old_gen->block_size(addr); 936 } 937 938 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const { 939 assert(is_in_reserved(addr), "block_is_obj of address outside of heap"); 940 assert(block_start(addr) == addr, "addr must be a block start"); 941 if (_young_gen->is_in_reserved(addr)) { 942 return _young_gen->block_is_obj(addr); 943 } 944 945 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 946 return _old_gen->block_is_obj(addr); 947 } 948 949 bool GenCollectedHeap::supports_tlab_allocation() const { 950 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 951 return _young_gen->supports_tlab_allocation(); 952 } 953 954 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const { 955 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 956 if (_young_gen->supports_tlab_allocation()) { 957 return _young_gen->tlab_capacity(); 958 } 959 return 0; 960 } 961 962 size_t GenCollectedHeap::tlab_used(Thread* thr) const { 963 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 964 if (_young_gen->supports_tlab_allocation()) { 965 return _young_gen->tlab_used(); 966 } 967 return 0; 968 } 969 970 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const { 971 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 972 if (_young_gen->supports_tlab_allocation()) { 973 return _young_gen->unsafe_max_tlab_alloc(); 974 } 975 return 0; 976 } 977 978 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) { 979 bool gc_overhead_limit_was_exceeded; 980 return gen_policy()->mem_allocate_work(size /* size */, 981 true /* is_tlab */, 982 &gc_overhead_limit_was_exceeded); 983 } 984 985 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size 986 // from the list headed by "*prev_ptr". 987 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) { 988 bool first = true; 989 size_t min_size = 0; // "first" makes this conceptually infinite. 990 ScratchBlock **smallest_ptr, *smallest; 991 ScratchBlock *cur = *prev_ptr; 992 while (cur) { 993 assert(*prev_ptr == cur, "just checking"); 994 if (first || cur->num_words < min_size) { 995 smallest_ptr = prev_ptr; 996 smallest = cur; 997 min_size = smallest->num_words; 998 first = false; 999 } 1000 prev_ptr = &cur->next; 1001 cur = cur->next; 1002 } 1003 smallest = *smallest_ptr; 1004 *smallest_ptr = smallest->next; 1005 return smallest; 1006 } 1007 1008 // Sort the scratch block list headed by res into decreasing size order, 1009 // and set "res" to the result. 1010 static void sort_scratch_list(ScratchBlock*& list) { 1011 ScratchBlock* sorted = NULL; 1012 ScratchBlock* unsorted = list; 1013 while (unsorted) { 1014 ScratchBlock *smallest = removeSmallestScratch(&unsorted); 1015 smallest->next = sorted; 1016 sorted = smallest; 1017 } 1018 list = sorted; 1019 } 1020 1021 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor, 1022 size_t max_alloc_words) { 1023 ScratchBlock* res = NULL; 1024 _young_gen->contribute_scratch(res, requestor, max_alloc_words); 1025 _old_gen->contribute_scratch(res, requestor, max_alloc_words); 1026 sort_scratch_list(res); 1027 return res; 1028 } 1029 1030 void GenCollectedHeap::release_scratch() { 1031 _young_gen->reset_scratch(); 1032 _old_gen->reset_scratch(); 1033 } 1034 1035 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure { 1036 void do_generation(Generation* gen) { 1037 gen->prepare_for_verify(); 1038 } 1039 }; 1040 1041 void GenCollectedHeap::prepare_for_verify() { 1042 ensure_parsability(false); // no need to retire TLABs 1043 GenPrepareForVerifyClosure blk; 1044 generation_iterate(&blk, false); 1045 } 1046 1047 void GenCollectedHeap::generation_iterate(GenClosure* cl, 1048 bool old_to_young) { 1049 if (old_to_young) { 1050 cl->do_generation(_old_gen); 1051 cl->do_generation(_young_gen); 1052 } else { 1053 cl->do_generation(_young_gen); 1054 cl->do_generation(_old_gen); 1055 } 1056 } 1057 1058 bool GenCollectedHeap::is_maximal_no_gc() const { 1059 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc(); 1060 } 1061 1062 void GenCollectedHeap::save_marks() { 1063 _young_gen->save_marks(); 1064 _old_gen->save_marks(); 1065 } 1066 1067 GenCollectedHeap* GenCollectedHeap::heap() { 1068 CollectedHeap* heap = Universe::heap(); 1069 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()"); 1070 assert(heap->kind() == CollectedHeap::GenCollectedHeap, "Not a GenCollectedHeap"); 1071 return (GenCollectedHeap*)heap; 1072 } 1073 1074 void GenCollectedHeap::prepare_for_compaction() { 1075 // Start by compacting into same gen. 1076 CompactPoint cp(_old_gen); 1077 _old_gen->prepare_for_compaction(&cp); 1078 _young_gen->prepare_for_compaction(&cp); 1079 } 1080 1081 void GenCollectedHeap::verify(VerifyOption option /* ignored */) { 1082 log_debug(gc, verify)("%s", _old_gen->name()); 1083 _old_gen->verify(); 1084 1085 log_debug(gc, verify)("%s", _old_gen->name()); 1086 _young_gen->verify(); 1087 1088 log_debug(gc, verify)("RemSet"); 1089 rem_set()->verify(); 1090 } 1091 1092 void GenCollectedHeap::print_on(outputStream* st) const { 1093 _young_gen->print_on(st); 1094 _old_gen->print_on(st); 1095 MetaspaceAux::print_on(st); 1096 } 1097 1098 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const { 1099 if (workers() != NULL) { 1100 workers()->threads_do(tc); 1101 } 1102 #if INCLUDE_ALL_GCS 1103 if (UseConcMarkSweepGC) { 1104 ConcurrentMarkSweepThread::threads_do(tc); 1105 } 1106 #endif // INCLUDE_ALL_GCS 1107 } 1108 1109 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const { 1110 #if INCLUDE_ALL_GCS 1111 if (UseConcMarkSweepGC) { 1112 workers()->print_worker_threads_on(st); 1113 ConcurrentMarkSweepThread::print_all_on(st); 1114 } 1115 #endif // INCLUDE_ALL_GCS 1116 } 1117 1118 void GenCollectedHeap::print_on_error(outputStream* st) const { 1119 this->CollectedHeap::print_on_error(st); 1120 1121 #if INCLUDE_ALL_GCS 1122 if (UseConcMarkSweepGC) { 1123 st->cr(); 1124 CMSCollector::print_on_error(st); 1125 } 1126 #endif // INCLUDE_ALL_GCS 1127 } 1128 1129 void GenCollectedHeap::print_tracing_info() const { 1130 if (TraceYoungGenTime) { 1131 _young_gen->print_summary_info(); 1132 } 1133 if (TraceOldGenTime) { 1134 _old_gen->print_summary_info(); 1135 } 1136 } 1137 1138 void GenCollectedHeap::print_heap_change(size_t young_prev_used, size_t old_prev_used) const { 1139 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)", 1140 _young_gen->short_name(), young_prev_used / K, _young_gen->used() /K, _young_gen->capacity() /K); 1141 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)", 1142 _old_gen->short_name(), old_prev_used / K, _old_gen->used() /K, _old_gen->capacity() /K); 1143 } 1144 1145 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure { 1146 private: 1147 bool _full; 1148 public: 1149 void do_generation(Generation* gen) { 1150 gen->gc_prologue(_full); 1151 } 1152 GenGCPrologueClosure(bool full) : _full(full) {}; 1153 }; 1154 1155 void GenCollectedHeap::gc_prologue(bool full) { 1156 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 1157 1158 always_do_update_barrier = false; 1159 // Fill TLAB's and such 1160 CollectedHeap::accumulate_statistics_all_tlabs(); 1161 ensure_parsability(true); // retire TLABs 1162 1163 // Walk generations 1164 GenGCPrologueClosure blk(full); 1165 generation_iterate(&blk, false); // not old-to-young. 1166 }; 1167 1168 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure { 1169 private: 1170 bool _full; 1171 public: 1172 void do_generation(Generation* gen) { 1173 gen->gc_epilogue(_full); 1174 } 1175 GenGCEpilogueClosure(bool full) : _full(full) {}; 1176 }; 1177 1178 void GenCollectedHeap::gc_epilogue(bool full) { 1179 #if defined(COMPILER2) || INCLUDE_JVMCI 1180 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 1181 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr())); 1182 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps"); 1183 #endif /* COMPILER2 || INCLUDE_JVMCI */ 1184 1185 resize_all_tlabs(); 1186 1187 GenGCEpilogueClosure blk(full); 1188 generation_iterate(&blk, false); // not old-to-young. 1189 1190 if (!CleanChunkPoolAsync) { 1191 Chunk::clean_chunk_pool(); 1192 } 1193 1194 MetaspaceCounters::update_performance_counters(); 1195 CompressedClassSpaceCounters::update_performance_counters(); 1196 1197 always_do_update_barrier = UseConcMarkSweepGC; 1198 }; 1199 1200 #ifndef PRODUCT 1201 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure { 1202 private: 1203 public: 1204 void do_generation(Generation* gen) { 1205 gen->record_spaces_top(); 1206 } 1207 }; 1208 1209 void GenCollectedHeap::record_gen_tops_before_GC() { 1210 if (ZapUnusedHeapArea) { 1211 GenGCSaveTopsBeforeGCClosure blk; 1212 generation_iterate(&blk, false); // not old-to-young. 1213 } 1214 } 1215 #endif // not PRODUCT 1216 1217 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure { 1218 public: 1219 void do_generation(Generation* gen) { 1220 gen->ensure_parsability(); 1221 } 1222 }; 1223 1224 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) { 1225 CollectedHeap::ensure_parsability(retire_tlabs); 1226 GenEnsureParsabilityClosure ep_cl; 1227 generation_iterate(&ep_cl, false); 1228 } 1229 1230 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen, 1231 oop obj, 1232 size_t obj_size) { 1233 guarantee(old_gen == _old_gen, "We only get here with an old generation"); 1234 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in"); 1235 HeapWord* result = NULL; 1236 1237 result = old_gen->expand_and_allocate(obj_size, false); 1238 1239 if (result != NULL) { 1240 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size); 1241 } 1242 return oop(result); 1243 } 1244 1245 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure { 1246 jlong _time; // in ms 1247 jlong _now; // in ms 1248 1249 public: 1250 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { } 1251 1252 jlong time() { return _time; } 1253 1254 void do_generation(Generation* gen) { 1255 _time = MIN2(_time, gen->time_of_last_gc(_now)); 1256 } 1257 }; 1258 1259 jlong GenCollectedHeap::millis_since_last_gc() { 1260 // We need a monotonically non-decreasing time in ms but 1261 // os::javaTimeMillis() does not guarantee monotonicity. 1262 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 1263 GenTimeOfLastGCClosure tolgc_cl(now); 1264 // iterate over generations getting the oldest 1265 // time that a generation was collected 1266 generation_iterate(&tolgc_cl, false); 1267 1268 // javaTimeNanos() is guaranteed to be monotonically non-decreasing 1269 // provided the underlying platform provides such a time source 1270 // (and it is bug free). So we still have to guard against getting 1271 // back a time later than 'now'. 1272 jlong retVal = now - tolgc_cl.time(); 1273 if (retVal < 0) { 1274 NOT_PRODUCT(log_warning(gc)("time warp: " JLONG_FORMAT, retVal);) 1275 return 0; 1276 } 1277 return retVal; 1278 } 1279 1280 void GenCollectedHeap::stop() { 1281 #if INCLUDE_ALL_GCS 1282 if (UseConcMarkSweepGC) { 1283 ConcurrentMarkSweepThread::cmst()->stop(); 1284 } 1285 #endif 1286 }